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40 CFR 721.10011 - Barium calcium manganese strontium oxide.
Code of Federal Regulations, 2013 CFR
...2013-07-01 2013-07-01 false Barium calcium manganese strontium oxide. 721.10011...Chemical Substances ┬¦ 721.10011 Barium calcium manganese strontium oxide. (a...chemical substance identified as barium calcium manganese strontium oxide (PMN...
Code of Federal Regulations, 2010 CFR
...2009-07-01 2009-07-01 false Barium calcium manganese strontium oxide. ...Chemical Substances ┬¦ 721.10011 Barium calcium manganese strontium oxide. ...The chemical substance identified as barium calcium manganese strontium...
Conditions of preparation of calcium and barium hexaboride powders
Microsoft Academic Search
1.A study was made of the conditions of preparation of barium and calcium hexaborides by the boroncarbide and borothermic techniques and by the reaction of barium carbonate with boron in a vacuum.2.It was established that a barium hexaboride with a composition approaching theoretical can be obtained by the borothermic techniques at a temperature of 1600░C from a charge with a
T. I. Serebryakova; ╔. V. Marek
Scattering lengths of calcium and barium isotopes
SciTech Connect
We have calculated the s-wave scattering length of all the even isotopes of calcium (Ca) and barium (Ba) in order to investigate the prospect of Bose-Einstein condensation (BEC). For Ca we have used an accurate molecular potential based on detailed spectroscopic data. Our calculations show that Ca does not provide other isotopes alternative to the recently Bose condensed {sup 40}Ca that suffers strong losses because of a very large scattering length. For Ba we show by using a model potential that the even isotopes cover a broad range of scattering lengths, opening the possibility of BEC for at least one of the isotopes.
Dammalapati, U.; Willmann, L.; Knoop, S. [Kernfysisch Versneller Instituut (KVI), University of Groningen, Zernikelaan 25, 9747 AA Groningen (Netherlands); LaserLaB Vrije Universiteit, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands)
Change in ionization of barium in calcium and direct determination of barium in calcium by flame atomic absorption spectrometry using the Ba ion resonance line
NASA Astrophysics Data System (ADS)
Partial pressures of barium at various concentrations of calcium are calculated, and degree of ionization of barium in the nitrous oxide-acetylene flame are determined experimentally and theoretically using the Saha equation. The ionization of barium (50 ?g ml -1 ) in the presence of 10000 ?g ml -1 of calcium was about one third of the theoretically expected value. Using the ion resonance line of barium permits the direct determination of barium down to 3 ppm in calcium matrices by atomic absorption spectrophotometry.
Takada, Takeo; Satho, Mamoru
21 CFR 182.2122 - Aluminum calcium silicate.
...2013-04-01 2013-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents ┬¦ 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...
21 CFR 582.2122 - Aluminum calcium silicate.
...2013-04-01 2013-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents ┬¦ 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...
EPA Science Inventory
The removal of barium (Ba) and radium (Ra), which are found in many groundwater sources, was achieved in laboratory studies with an ion exchange process. In the studies, a strong acid resin in the calcium form effectively removed Ba(+2) and Ra (+2) to meet standards. The resin wa...
Pockels response in calcium barium niobate thin films
The electro-optical response of calcium barium niobate ferroelectric thin films is characterized using a single beam setup in reflection geometry. Clear evidence of a Pockels response together with an r33 coefficient as high as 130 pm/V is found. This large value and the high Curie temperature of the material under study (>250 ░C) can be considered as a promising feature for the fabrication of hybrid, integrated electro-optical modulators working at a high repetition rate.
Helsten, R.; Razzari, L.; Ferrera, M.; Ndione, P. F.; Gaidi, M.; Durand, C.; Chaker, M.; Morandotti, R.
The effect of calcium ions on the precipitation of barium sulphate 1: calcium ions in the absence of organic additives
The effect of calcium cations on the precipitation of barium sulphate is comprehensively studied using several techniques for the first time. The dominant mechanism at <0.00025M calcium ions is an ionic strength effect. Above this concentration, tests conducted at the same ionic strength show that differences in the behaviour of barium sulphate precipitation occur depending on the cation present (sodium
F. Jones; A Oliviera; G. M Parkinson; A. L Rohl; T Upson
Electron microscopy of barium strontium titanate nanostructures in the aluminum oxide matrix
Electron microscopy has revealed the mechanism of formation of barium strontium titanate nanostructures during crystallization in the bulk of pores of the aluminum matrix. The nanostructures have the form of nanotubes or nanocolumns 100-200 nm in diameter and a few microns long, which are formed by barium strontium titanate crystals 3-100 nm in size.
Zhigalina, O. M.; Vorotilov, K. A.; Kuskova, A. N.; Sigov, A. S.
Calcium barium niobate ridge waveguide on silicon substrate
A novel optical ridge waveguide using calcium barium niobate (CBN) with a high electro-optic coefficient on silicon substrate is proposed for the design and realization of the next-generation hybrid modulators with short length and low driving voltage. To overcome the etching difficulty of CBN, the design of a waveguide, including an elevated CBN layer based on etched silicon dioxide, is presented. Fabrication of a thick 2.5-?m CBN layer is performed using pulsed laser deposition. Deposited silicon dioxide on the sides and top of the CBN reduces the waveguide loss as low as 3.44 dB/cm, measured using a cutback method. Good agreement between the mode profiles of the simulation and measurement is obtained.
Mortazy, Ebrahim; Stateikina, Irina; Tehranchi, Amirhossein; Delprat, Sķbastien; Chaker, Mohamed; Wu, Ke
The effect of additives on the co-crystallisation of calcium with barium sulphate
A study has been carried out to ascertain the effect of divalent cations and scale inhibitors on the lattice parameters, crystal size and morphology of barium sulphate. The mineral barite can support up to 6% calcium substitution for barium ions in the crystal lattice. Grahmann (Neues Jahrb. Min. 1 (1920) 1). It is known that the presence of magnesium and
A. J. B. Hennessy; G. M. Graham
Life Model of Hollow Cathodes Using a Barium Calcium Aluminate Impregnated Tungsten Emitter
NASA Technical Reports Server (NTRS)
Hollow cathodes with barium calcium aluminate impregnated tungsten emitters for thermionic emission are widely used in electric propulsion. These high current, low power cathodes are employed in ion thrusters, Hall thrusters, and on the International Space Station in plasma contactors. The requirements on hollow cathode life are growing more stringent with the increasing use of electric propulsion technology. The life limiting mechanism that determines the entitlement lifetime of a barium impregnated thermionic emission cathode is the evolution and transport of barium away from the emitter surface. A model is being developed to study the process of barium transport and loss from the emitter insert in hollow cathodes. The model accounts for the production of barium through analysis of the relevant impregnate chemistry. Transport of barium through the approximately static gas is also being treated. Finally, the effect of temperature gradients within the cathode are considered.
Kovaleski, S. D.; Burke, Tom (Technical Monitor)
Barium oxide, calcium oxide, magnesia, and alkali oxide free glass
A glass composition consisting essentially of about 10-45 mole percent of SrO; about 35-75 mole percent SiO.sub.2; one or more compounds from the group of compounds consisting of La.sub.2O.sub.3, Al.sub.2O.sub.3, B.sub.2O.sub.3, and Ni; the La.sub.2O.sub.3 less than about 20 mole percent; the Al.sub.2O.sub.3 less than about 25 mole percent; the B.sub.2O.sub.3 less than about 15 mole percent; and the Ni less than about 5 mole percent. Preferably, the glass is substantially free of barium oxide, calcium oxide, magnesia, and alkali oxide. Preferably, the glass is used as a seal in a solid oxide fuel/electrolyzer cell (SOFC) stack. The SOFC stack comprises a plurality of SOFCs connected by one or more interconnect and manifold materials and sealed by the glass. Preferably, each SOFC comprises an anode, a cathode, and a solid electrolyte.
Lu, Peizhen Kathy; Mahapatra, Manoj Kumar
The action of caffeine on inward barium current through voltage-dependent calcium channels in single rabbit ear artery cells
The effect of caffeine on inward current carried by barium ions through voltage-dependent calcium channels has been investigated in single rabbit ear artery cells using whole-cell voltage-clamp techniques. Caffeine (1 ¢30 mM) caused a rapid and reversible concentration-dependent blockade of barium current and a related compound, 3-isobutyl-1-methylxanthine (IBMX), was a more potent inhibitor of barium current. Caffeine-induced inhibition of barium
A. D. Hughes; S. Hering; T. B. Bolton
Effect of chloride incorporation on the crystallization of zirconium-barium-lanthanum-aluminum fluoride glass
One aspect of the influence of preparation procedure on the crystallization behavior of a zirconium-barium-lanthanum-aluminum fluoride glass was studied. The crystallization pattern of this glass may be affected by the chlorine concentration within it. In particular, when such glasses are heated at low temperatures, the alpha-Ba-Zr-F6 crystalline phase forms only in those glasses which contain chloride.
Neilson, G. F.; Smith, G. L.; Weinberg, M. C.
Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses
We report near infrared broadband emission of bismuth-doped barium-aluminum-borate glasses. The broadband emission covers 1.3Ąm window in optical telecommunication systems. And it possesses wide full width at half maximum (FWHM) of ~200nm and long lifetime as long as 350Ąs. The luminescent properties are quite sensitive to glass compositions and excitation wavelengths. Based on energy matching conditions, we suggest that the
Xian-Geng Meng; Jian-Rong Qiu; Ming-Ying Peng; Dan-Ping Chen; Quan-Zhong Zhao; Xiong-Wei Jiang; Cong-Shan Zhu
Influence of calcium acetate or calcium citrate on intestinal aluminum absorption
Influence of calcium acetate or calcium citrate on intestinal aluminum absorption. The risk of aluminum (Al) accumulation in patients with chronic renal failure has led to use of non-Al phosphate binders. Frequently, Al and non-Al phosphate binders are co-administered. Unfortunately, calcium citrate (Ca citr), when given with Al-gel, markedly enhances Al absorption. To determine whether calcium acetate (Ca acetate) also
Charles R Nolan; Joseph R Califano; Clifford A Butzin
Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)
PubMed Central
Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.
He, Honghua; Bleby, Timothy M.; Veneklaas, Erik J.; Lambers, Hans; Kuo, John
Interaction Studies Between Crofer-22APU Alloy And P2O5 Containing Barium Calcium Alumino-borosilicate (BCABS) Sealant Glass-Ceramics
We present the effect of P2O5 addition on barium calcium aluminum borosilicate BCABS glasses of composition (mol %) 35BaO-15CaO-5Al2O3-(37-x)SiO2-8B2O3-xP2O5 (0<=x<=5). The incorporation of P2O5 increased network polymerization and crystallization tendency. However, addition of P2O5 leads to the formation of Cr2O3 at the interface, saturating it in the ions of the metal. This improves glass-to-metal bonding.
Ananthanarayanan, A.; Montagne, L.; Revel, B.; Kothiyal, G. P.
We report near infrared broadband emission of bismuth-doped barium-aluminum-borate glasses. The broadband emission covers 1.3Ąm window in optical telecommunication systems. And it possesses wide full width at half maximum (FWHM) of ~200nm and long lifetime as long as 350Ąs. The luminescent properties are quite sensitive to glass compositions and excitation wavelengths. Based on energy matching conditions, we suggest that the infrared emission may be ascribed to 3P1?© 3P0 transition of Bi+. The broad infrared emission characteristics of this material indicate that it might be a promising candidate for broadband optical fiber amplifiers and tunable lasers.
Meng, Xian-Geng; Qiu, Jian-Rong; Peng, Ming-Ying; Chen, Dan-Ping; Zhao, Quan-Zhong; Jiang, Xiong-Wei; Zhu, Cong-Shan
Infrared studies of apatites. I. Vibrational assignments for calcium, strontium, and barium hydroxyapatities utilizing isotopic substitution
The infrared spectra of powdered calcium hydroxyapatite isotopically ; substituted with D, ┬╣ŌüĖO, Ōü┤Ōü┤Ca, and Ōü┤ŌüĖCa and infrared spectra of ; powdered strontium and barium hydroxyapatites and their deuterated analogs are ; reported at 48 and - 185 deg in the 4000-200cm-┬╣ region. Band ; assignments, based on isotopic frequency shifts, band intensity, band temperature ; dependency, and comparisons between
B. O. Fowler
Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation
There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.
Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin; Wang, Xue-Lin
Conoscopic interferometry for probing electro-optic coefficients of strontium calcium barium niobate crystal
The relation between the linear electro-optic effect and conoscopic interference has been investigated in a biased electro-optic crystal strontium calcium barium niobate (CSBN). Based on the change of interference patterns with applied field, an interferometric method for probing electro-optic coefficients of electro-optic crystals has been proposed. In our case, the linear electro-optic coefficients of CSBN:50 was first probed at ?33=(141.0▒0.5)ū10 -12 m/V and ?13=(85.0▒0.5)ū10 -12 m/V.
Wang, Ankai; Gao, CH. Y.; Xu, J. Q.; Zhang, H. J.; Sun, Sh. Q.
Nonlinear prism based on the natural ferroelectric domain structure in calcium barium niobate
We show the ability of calcium barium niobate as a nonlinear material to produce conical second harmonic generation in a broad frequency range. The nonlinear properties of this system are based on the broad sized microdomain distribution appearing naturally in the as-grown crystal. The large angular deflection obtained for conical second harmonic generation allows considering this system as a nonlinear prism with variations in the second harmonic generation angle as large as 35░ in the wavelength range of 430-660 nm.
Molina, P.; ┴lvarez-GarcĒa, S.; RamĒrez, M. O.; GarcĒa-Solķ, J.; Bausß, L. E.; Zhang, Huaijin; Gao, Wenlan; Wang, Jiyang; Jiang, Minhua
Absolute index of refraction and its temperature dependence of calcium fluoride, barium fluoride, and strontium fluoride near 157 nm
We have made accurate measurements near 157 nm of the absolute index of refraction, the index of refraction, the index dispersion, and the temperature dependence of the index, for the cubic-symmetry, group-II fluorides: calcium fluoride, strontium fluoride, and barium fluoride. Accurate measurements of these quantities for calcium fluoride are needed for designs of lens systems for 157 nm excimer-laser- based exposure tools for photolithography. Measurements of these isotropic materials high ly transmissive near 157 nm, such as strontium fluoride and barium fluoride, are needed for designs which include secondary materials in addition to calcium fluoride to correct for chromatic aberrations. These optical properties were measured with precision gonimeters on prisms of the materials in a nitrogen atmosphere using the minimum deviation method. The relative refractive indices were converted to absolute indices by using values of the index of nitrogen obtained by independent interferometric measurement near 157 nm. Values of the absolute refractive indices for these materials were obtained with an accuracy of 6 X 10-6. A key result is that the dispersion of barium fluoride near 157 nm is approximately 68 percent larger than that of calcium fluoride, which makes barium fluoride a potentially useful material for combination with calcium fluoride for chromatic aberration correction near 157 nm.
Burnett, John H.; Gupta, Rajeev; Griesmann, Ulf
Copper, aluminum, iron and calcium inhibit human acetylcholinesterase in vitro.
Acetylcholinesterase (AChE) is an important part of cholinergic nerves where it participates in termination of neurotransmission. AChE can be inhibited by e.g. some Alzheimer disease drugs, nerve agents, and secondary metabolites. In this work, metal salts aluminum chloride, calcium chloride, cupric chloride, ferric chloride, potassium chloride, magnesium chloride and sodium chloride were tested for their ability to inhibit AChE. Standard Ellman assay based on human recombinant AChE was done and inhibition was measured using Dixon plot. No inhibition was proved for sodium, potassium and magnesium ions. However, aluminum, cupric, ferric and calcium ions were able to inhibit AChE via noncompetitive mechanism of inhibition. Though the inhibition is much weaker when compared to e.g. drugs with noncompetitive mechanism of action, biological relevance of the findings can be anticipated. PMID:24473150
Pohanka, Miroslav
Release of noradrenaline from slices of cat spleen by pre-treatment with calcium, strontium and barium
1. Spleen slices pre-incubated for different periods at 4░ C in Krebs solution containing varying concentrations of calcium, up to 96 mM, lost their endogenous noradrenaline stores when reincubated in normal Krebs solution at 37░ C for 2 hr. Rate of loss of noradrenaline was roughly related to the calcium concentration of the pre-incubation medium and the pre-exposure time. 2. Pre-treatment with isotonic barium or strontium (96 mM) Krebs solution also induced release of noradrenaline from spleen slices when re-exposed to normal Krebs solution. Barium was more effective than either calcium or strontium. 3. The enhanced release induced by calcium pre-treatment occurred in the absence of calcium, with or without EGTA. 4. Tissue calcium concentration of spleen slices was 0Ę68 m-mole/kg. Pre-treatment of slices with normal or 96 mM calcium-Krebs solution for 4 hr at 4░ C increased the calcium concentration to 2Ę57 and 9Ę9 m-mole/kg, respectively. 5. Ouabain, which caused a dose-dependent release of noradrenaline, did not modify the release induced by calcium pre-treatment. 6. Spleen slices prepared from cats anaesthetized with sodium pentobarbitone instead of ether were resistant to noradrenaline depletion by calcium pre-treatment. 7. Evoked release of [3H]noradrenaline by high potassium from calcium-pre-treated slices did not occur in the absence of external calcium, even though the calcium pre-treatment enhanced the tissue concentration of this ion by nearly tenfold. 8. Net uptake of noradrenaline in normal and in treated slices whose noradrenaline content was severely reduced by barium pre-treatment or sodium withdrawal was comparable. 9. Specific activity of released and endogenous [3H]noradrenaline increased as the tissue stores of noradrenaline were reduced. 10. It is suggested that the spontaneous loss of tissue noradrenaline after pre-treatment with high-calcium solution was due to inhibition of sodium-potassium-activated ATPase by intracellular accumulation of calcium ions. Evidence is presented to suggest that vesicles depleted of their endogenous transmitter by pre-treatment with calcium, strontium or barium, or by sodium withdrawal, are re-used for the storage and release of exogenous noradrenaline.
Garcia, A. G.; Kirpekar, S. M.
The retention of calcium, barium, and strontium ions by a mollisol humic acid: Spectroscopic investigation
Humic substances have a major role in controlling the mobility and bioavailability of metallic ions in soils and natural waters. The alkaline earth metals, calcium, barium, and strontium, are broadly abundant in the crust of the earth, and Ca2+ ions are known to be important in the formation of structural aggregates in soils. Yet, direct spectroscopic evidence of how Ca, Ba, and Sr ions interact with soil organic matter, is minimal. To develop a deeper understanding of the interaction of the alkaline earth cations in soil, we studied the complexation behavior of strontium, barium and calcium by humic acid (HA) using solid-state 13C CP-MAS NMR, FTIR and extended x-ray absorption fine structure (EXAFS) spectroscopy. A HA sample was extracted from an agricultural mollisol (pH 6, 32.5% clay content, 3.7% organic carbon) located in southwestern Minnesota, USA, by the standard NaOH method. The HA sample was treated with chloride salts of Ca, Sr or Ba, then freeze-dried prior to spectroscopic measurements. The FTIR spectra, obtained using pressed KBr disks, and the 13C NMR spectra revealed spectral differences, stemming mainly from deprotonation reactions of the carboxylic and phenolic groups of the HA. The association of Ca, Ba, and Sr ions with the HA caused a marked FTIR shift of the carboxylate band, with the Ba shift being the most pronounced (HA 1604.7; HA-Ca 1595.1; HA-Sr 1597; HA-Ba 1579.6), which seems to imply that Ba is the strongest bound element. An NMR shift of the carbonyl peak at 171.8 ppm was also observed to 174.5 for Ca, 173.7 for Sr, and 174.4 for Ba confirming that these cations are behaving differently towards soil HA. The EXAFS spectra indicated back-scattering from oxygen atoms, in the first shell, for Ca, Sr, and Ba with varied coordination number. Our data prove that (1) the carboxylates and phenolates are the prevailing functional groups involved in the interactions between the extracted HA and alkali metal cations, (2) barium forms the strongest complex compared to strontium and calcium.
Oufqir, Sofia; Bloom, Paul R.; Torner, Brandy M.
Interaction Studies Between Crofer-22APU Alloy And P{sub 2}O{sub 5} Containing Barium Calcium Alumino-borosilicate (BCABS) Sealant Glass-Ceramics
We present the effect of P{sub 2}O{sub 5} addition on barium calcium aluminum borosilicate BCABS glasses of composition (mol %)35BaO-15CaO-5Al{sub 2}O{sub 3}-(37-x)SiO{sub 2}-8B{sub 2}O{sub 3}-xP{sub 2}O{sub 5}(0{<=}x{<=}5). The incorporation of P{sub 2}O{sub 5} increased network polymerization and crystallization tendency. However, addition of P{sub 2}O{sub 5} leads to the formation of Cr{sub 2}O{sub 3} at the interface, saturating it in the ions of the metal. This improves glass-to-metal bonding.
Ananthanarayanan, A. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); UCCS-Unite de Catalyse et Chimie du Solide-UMR CNRS 8181, Ecole Nationale Superieure de Chimie de Lille, Universite des Sciences et Technologies de Lille, BP 108, 59562 Villeneuve d'Ascq Cedex (France); Montagne, L.; Revel, B. [UCCS-Unite de Catalyse et Chimie du Solide-UMR CNRS 8181, Ecole Nationale Superieure de Chimie de Lille, Universite des Sciences et Technologies de Lille, BP 108, 59562 Villeneuve d'Ascq Cedex (France); Kothiyal, G. P. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)
Intra-grain composition nonuniform barium strontium calcium titanate ceramics by sol-gel pervasion techniques
The use of ferroelectric ceramics in microwave devices requires that they possess low-loss, frequency-stable and highly tunable properties. The problems of traditional barium strontium calcium titanate ceramics are higher loss and inappropriate work temperature dependence. In this work, a conventional mixed oxide route was used to prepare BaTiO3, SrTiO3 and CaTiO3 precursor powders. The BaTiO3, SrTiO3 and CaTiO3 powders were thoroughly ball mill mixed. They were then added to 5 wt% polyvinyl alcohol and pressed under a uni-axial pressure of 220 MPa into discs of 12 mm diameter. We introduced nano-grains of barium strontium titanate (BST) into the BSCT ceramic by nano-grain pervasion techniques to fabricate compositionally nonuniform BSCT ceramic samples. The nano-particles of BST are prepared with the sol-gel method. The sol-gel was subjected to ultrasonic irradiation and then vacuum methods in order to easily introduce nanoparticles into bulky BSCT. The ceramics do not show a sharp change in the dielectric constant and have a wide range of Curie temperature distribution. This is attributed to the presence of a compositionally nonuniform micro-area in the samples. Compared with uniform-composition BSCT, compositionally nonuniform BSCT has favourable dielectric properties. These results suggest that the compositionally nonuniform BSCT ceramics are promising candidates as tunable microwave elements.
Xu, Honghai; Jin, Dengren; Wu, Wenbiao; Cheng, Jinrong
Reactions of calcium orthosilicate and barium zirconate with oxides and sulfates of various elements
Calcium orthosilicate and barium zirconate were evaluated as the insulation layer of thermal barrier coatings for air cooled gas turbine components. Their reactions with various oxides and sulfates were studied at 1100 C and 1300 C for times ranging up to 400 and 200 hours, respectively. These oxides and sulfates represent potential impurities or additives in gas turbine fuels and in turbine combustion air, as well as elements of potential bond coat alloys. The phase compositions of the reaction products were determined by X-ray diffraction analysis. BaZrO3 and 2CaO-SiO2 both reacted with P2O5, V2O5, Cr2O3, Al2O3, and SiO2. In addition, 2CaO-SiO2 reacted with Na2O, BaO, MgO, and CoO and BaZrO3 reacted with Fe2O3.
Zaplatynsky, I.
Planar waveguides in calcium barium niobate fabricated by MeV He ion implantation
A planar optical waveguide was formed in calcium barium niobate (CBN) crystal by 2.8-MeV He-ion implantation with a dose of 1.0ū1016 ions/cm2 at room temperature. The prism-coupling method was used to take dark mode measurements at both 633 nm and 1539 nm. The refractive-index profile (no and ne) of the He-implanted CBN waveguide was analyzed with the reflectivity calculation method. The results show that the MeV He implantation results in a decrease in refractive index in barriers for both no (4.1%) and ne (3.1%), but for ne there is an increase in the waveguide region. The intensity profile of the guide mode and waveguide loss were obtained by end-fire coupling.
Fu, G.; Wang, K.-M.; Wang, X.-L.; Zhang, H.-J.; Xu, X.-G.; Song, H.-L.; Ma, H.-J.
Effect of titanium alkoxides on the properties of barium-strontium-calcium titanate powders obtained by a sol-gel method
This is a study of the effect of titanium alkoxides on the properties of barium-strontium-calcium titanate powders produced\\u000a by a sol-gel method. Sols were synthesized using titanium tetraethoxide, titanium tetraisoproxide, and titanium tetrabutoxide.\\u000a Xerogels of titanium oxide doped with barium, strontium, and calcium in a proportion of 60:30:10 were obtained by drying the\\u000a sols at a temperature of 70░C. Thermogravimetric
T. W. Kim; N. V. Gaponenko; E. A. Stepanova; T. F. Kuznetsova; A. I. RatÆko
Chemical Compatibility of Barium-Calcium-Aluminosilicate Based Sealing Glasses with Heat Resistant Alloys
In most planar SOFC stacks operating at an intermediate temperature (700-800 degrees C), the interconnect is typically made from a ferritic stainless steel and has to be hermitically sealed to its adjacent components, such as the ceramic PEN (Positive electrode-Electrolyte-Negative electrode) by a sealing glass. To large extent the seal performance relies on the chemical compatibility of the sealing glass with the metallic interconnect. In this study, a barium-calcium-aluminosilicate (BCAS) based glass-ceramic, specifically developed as a sealant in SOFC stacks, and a ferritic stainless steel (446) were chosen as examples to investigate the chemical interactions or corrosions at the sealing glass interface with the ferritic stainless steels. Evaluation of the interfaces of coupon joints indicated that interactions between the BCAS glass-ceramic and the ferritic stainless steel depended on the exposure conditions. At the edges of joints, where oxygen or air was accessible, the interaction often led to the formation of BaCrO4, while in the interior of the joints, chromium or chromia dissolved into the glass to form a thin layer of chromium rich solid solution. It was also found that, in the interior of the joints, the interaction often resulted in the formation of pores aligning along the interface. The pore formation along the interface of sealing glass and ferritic stainless steel however could be avoided through a pre-heat treatment of the ferriitc stainless steel.
Yang, Zhenguo; Weil, K. Scott; Meinhardt, Kerry D.; Stevenson, Jeffry W.; Paxton, Dean M.; Xia, Guanguang; Kim, Dong-Sang
Chemical Interactions of Barium-Calcium-Aluminosilicate Based Sealing Glasses with Oxidation Resistant Alloys
In most planar SOFC stack designs, the interconnect, which is typically made from an oxidation resistant alloy, potentially including austenitic chromia-forming, ferritic chromia-forming, and alumina-forming alloys, has to be hermitically sealed to its adjacent components, usually by a sealing glass. To maintain the structural stability and minimize the degradation of stack performance, the sealing glass must be chemically compatible with the alloy used for the interconnect. In this work, Nicrofer6025, AISI446 and a Fecralloy were selected as examples of austenitic chromia-forming, ferritic chromia-forming, and alumina-forming alloys, respectively. Their chemical compatibility with a barium-calcium-aluminosilicate (BCAS) based glass, specifically developed as a sealant in SOFC stacks, was evaluated. It was found that the BCAS sealing glass interacted chemically with both the chromia-forming alloys and the alumina-forming alloys. The extent and nature of the interactions and their final products depended on the matrix alloy compositions, the exposure conditions and/or proximity of the glass/alloy interface to the ambient air. These interactions and their mechanisms will be discussed with the assistance of thermodynamic modeling.
Yang, Z Gary (BATTELLE (PACIFIC NW LAB)); Stevenson, Jeffry W. (BATTELLE (PACIFIC NW LAB)); Meinhardt, Kerry D. (BATTELLE (PACIFIC NW LAB))
The Effects of Aluminum on the lnflux of Calcium, Potassium, Ammonium, Nitrate, and Phosphate in an Aluminum Sensitive Cultivar of Barley (Hordeum vdgare 1.)
~ ~ ~ ~~~ The mechanism by which aluminum interferes with ion influx is not known. In this study, the effects of aluminum on the influx of the cations calcium, potassium, and ammonium and the anions nitrate and phosphate were measured in an aluminum-sensitive cultivar of barley (Hordeum vdgare 1.). Aluminum (100 PM) was found to inhibit the influx of
Brian E. Nichol; Luis A. Oliveira; Mohamed Y. Siddiqi
Analysis of the Biocompatibility of ALCAP (Aluminum, Calcium, and Phosphorus Oxides) Ceramics in Rat Femurs.
National Technical Information Service (NTIS)
Ceramics composed of aluminum, calcium, and phosphorus oxides (ALCAP) were tested for compatibility as bone replacement biomaterials. Implantation of ALCAP ceramics in rat femurs had no deleterious effect on body weights, organ/body weight ratios, muscle,...
D. R. Mattie P. K. Bajpai
The ferroelectric phase transition of calcium barium niobate: experimental evidence of Smolenskii's model for diffuse phase transitions?
We present investigations on temperature-dependent changes in the size distribution of ferroelectric domains in single crystals of the novel tungsten bronze type calcium barium niobate (CBN). Since its congruently melting composition has a relatively high ferroelectric phase transition temperature of about 265 ░C, CBN can be considered as an interesting material for various future applications. Using k-space spectroscopy, both unpoled polydomain crystals and crystals poled at room temperature have been investigated in the vicinity of the ferroelectric phase transition. In unpoled CBN, an intermixture of domain-size dependent phase transitions has been observed, which can be described with the model for diffuse phase transitions established by Smolenskii.
Heine, Urs; Voelker, Uwe; Betzler, Klaus; Burianek, Manfred; Muehlberg, Manfred
Verapamil influence on calcium and aluminum absorption by roots of three sorghum cultivars
Verapamil [a?isopropyl?a[(n?methyl?N?homoveratryl)?y?amino?propyl]?3,4?dimethoxyphenylacetonitril] (400 ?M) inhibited membrane calcium (Ca) transport, but not aluminum influx, in sorghum [Sorghum bicolor (L) Moench] roots of the acid stress sensitive cultivar, Funk G522DR. In an acid stress tolerant cultivar, SC283, neither Ca nor aluminum (Al) transport through the plasmalemma were influenced by verapamil. In a second acid stress tolerant cultivar, SC574, verapamil influenced aluminum but
R. E. Wilkinson; R. R. Duncan
Metamorphosed calcium-aluminum-rich inclusions in CK carbonaceous chondrites
CK chondrites are the only group of carbonaceous chondrites with petrologic types ranging from 3 to 6. Although CKs are described as calcium-aluminum-rich inclusion (CAI)-poor objects, the abundance of CAIs in the 18 CK3-6 we analyzed ranges from zero to approximately 16.4%. During thermal metamorphism, some of the fine-grained CAIs recrystallized as irregular assemblages of plagioclase + Ca-rich pyroxene ▒ olivine ▒ Ca-poor pyroxene ▒ magnetite. Coarse-grained CAIs display zoned spinel, fassaite destabilization, and secondary grossular and spinel. Secondary anorthite, grossular, Ca-rich pyroxene, and spinel derive from the destabilization of melilite, which is lacking in all CAIs investigated. The Al-Mg isotopic systematics measured in fine- and coarse-grained CAIs from Tanezrouft (Tnz) 057 was affected by Mg redistribution. The partial equilibration of Al-Mg isotopic signatures obtained in the core of a coarse-grained CAI (CG1-CAI) in Tnz 057 may indicate a lower peak temperature for Mg diffusion of approximately 540-580 ░C, while grossular present in the core of this CAI indicates a higher temperature of around 800 ░C for the metamorphic event on the parent body of Tnz 057. Excluding metamorphic features, the similarity in nature and abundance of CAIs in CK and CV chondrites confirms that CVs and CKs form a continuous metamorphic series from type 3 to 6.
Chaumard, NoļL.; Devouard, Bertrand; Bouvier, Audrey; Wadhwa, Meenakshi
Magnetic and Dielectric Excitations in the W-Band in Aluminum Substituted Barium and Strontium Hexaferrites
Single crystal strontium and barium hexaferrites in which Al is substituted for Fe have uniaxial anisotropy fields on the order of 20-30 kOe and have magnetic excitations at 75-110 GHz. Here, we discuss results of investigations on magnetostatic forward volume waves and dielectric resonances in such ferrites. Data on the mode frequencies were utilized to characterize the ferrites in terms
Maksym A. Popov; Igor V. Zavislyak; Alexander S. Tatarenko; Gopalan Srinivasan; A. M. Balbashov
Calcium is actively transported into intracellular organelles and out of the cytoplasm by Ca2+/Mg2+-ATPases located in the endoplasmic reticulum and plasma membranes. he effects of aluminum on calcium transport were examined in the adult rat brain. 5Ca-uptake was examined in micr...
An Isotopic and Petrologic Study of Calcium-Aluminum-Rich Inclusions from CO3 Meteorites
We have studied the mineralogy and petrology of 229 calcium-aluminum-rich inclusions (CAIs) from ten CO3 meteorites of petrologic types 3.0¢3.7. Subsets of these inclusions were measured by ion probe for magnesium, calcium, and titanium isotopes and REE abundances. Most CAIs from CO3 meteorites fall into three major types: (1) melilite-rich inclusions, which also contain spinel\\/hercynite, perovskite, and occasionally hibonite; (2)
S. S. Russell; G. R. Huss; A. J. Fahey; R. C. Greenwood; R. Hutchison; G. J. Wasserburg
Spatial and Temporal Variation in Calcium and Aluminum in Northern Hardwood Forest Floors
Acid rain results in losses of exchangeable base cations from soils, but the mechanism of base cation displacement from the forest floor is not clear, and has been hypothesized to involve mobilization of aluminum from the mineral soil. We attempted to test the hypothesis that losses of calcium from the forest floor were balanced by increases in Al in NewHampshire
R. D. Yanai; R. P. Phillips; M. A. Arthur; T. G. Siccama; E. N. Hane
Calcium-aluminum exchange isotherms were generated for three common ion exchange equilibrium equations, and their implications relative to the probable effects of acid rainfall are examined. The equations examined were those of Gaines and Thomas (1953), Vanselow (1932), and Gapon...
Calcium Modification of Spinel Inclusions in Aluminum-Killed Steel: Reaction Steps
Calcium treatment is a well-established way to modify solid alumina inclusions to liquid or partially liquid calcium aluminates. Spinels (Al2O3Ę xMgO) can also form in liquid steel after aluminum deoxidation. Like alumina, the spinels can be modified readily to liquid inclusions by a calcium treatment. The modification of spinels was studied by observing the transient evolution of inclusions, in laboratory and industrial heats. Spinel modification involves the preferential reduction of MgO from the spinel, with Mg dissolving in the steel, and it proceeds through transient calcium sulfide formation, just like in the case of alumina inclusions. Because magnesium dissolves in steel after the calcium treatment of spinels, the reoxidation of the melt will produce new spinels.
Verma, Neerav; Pistorius, Petrus C.; Fruehan, Richard J.; Potter, Michael S.; Oltmann, Helmut G.; Pretorius, Eugene B.
Calcium-Aluminum-rich Inclusions in Chondritic Meteorites
Calcium-aluminum-rich inclusions (CAIs) are submillimeter- to centimeter-sized clasts in chondritic meteorites, whose ceramic-like chemistry and mineralogy set them apart from other chondrite components. Since their first descriptions more than 30 years ago (e.g., Christophe Michel-Lķvy, 1968), they have been the objects of a vast amount of study. At first, interest centered on the close similarity of their mineralogy to the first phases predicted by thermodynamic calculations to condense out of a gas of solar composition during cooling from very high temperatures (e.g., Lord, 1965; Grossman, 1972). Immediately thereafter, CAIs were found to be extremely old (4.56 Ga) and to possess unusual isotopic compositions (in particular, in magnesium and oxygen) suggestive of a presolar dust component. In short, they appear to be the oldest and most primitive objects formed in the infant solar system.In the late 1980s (e.g., MacPherson et al., 1988), the attention of most workers in the field was focused on understanding the petrogenesis and isotopic compositions of CAIs within a relatively restricted number of chondrite varieties. Much has changed since then. We now have extended our data sets beyond CV and CM chondrites to CAIs from ordinary, enstatite, and a wider range of carbonaceous chondrites. Out of this has emerged an ironic fact: the large centimeter-sized CAI "marbles" (the so-called type Bs; see below) that are so prominent in CV chondrites, and upon which so many of the original concepts were based owing to the abundance and availability of material from the Allende meteorite, turn out to be the exceptions rather than the norm. Indeed, we now know that the Allende parent body itself experienced so much postaccretion reprocessing that its CAIs reveal only a murky picture of the early solar nebula. Another profound change since 1988 has been the development of ion microprobe technology permitting microanalysis of oxygen isotopes within standard petrographic thin sections. One of the debates raging in 1988 centered on the difficulty of making CAIs at the distance of the asteroid belt where the host chondrites presumably accreted. Since then, a combination of isotopic (especially beryllium-boron and oxygen) evidence and theoretical modeling have suggested the interesting possibility that CAIs all formed very close to the infant sun and were later dispersed out to the respective chondrite accretion regions. Yet another difference from 1988 is that the science of meteoritics has matured past the point where workers study CAIs without consideration of other chondritic components, most notably chondrules. Bulk composition differences aside, CAIs and chondrules are both products of very high temperature events in the earliest solar system. Like chondrules, many CAIs apparently solidified from partially to completely molten droplets. Moreover, chondrules and CAIs both have far more complex histories than was generally recognized in the late 1980s: both may have experienced multiple melting episodes, followed by prolonged nebular and/or asteroidal modification due to gaseous or liquid interactions and reheating as a result of shock processes. In short, although CAIs are still recognized as being the oldest objects formed in our solar system and possessing isotopic traces of the presolar dust from which they ultimately formed, they are a long way from being the primitive condensates they were once thought to be. Rather than stressing the unusual isotopic characteristics of CAIs and the presolar implications, this chapter will instead treat CAIs as probes of the earliest solar system that reveal the nature of the high-temperature events, their chronology, and the likely locales where such events occurred.This chapter is not, and does not pretend to be, an exhaustive review of the sum of knowledge about CAIs. Indeed, so much new data have been generated since 1988, especially isotopic data from an ever-growing number of sophisticated ion microprobe labs, that it would far beyond the space limitations of this chapter to a
MacPherson, G. J.
Dependence of third-order nonlinear optical effect on refractive index in barium (Li) aluminum (Ga or Si) borate ternary glasses produced by new pulling down technique
Ternary glasses of barium (Li-substituted) aluminum (Ga- or Si-substituted) borate were solidified by new technique using conventional Floating-zone Pulling Down system. It was difficult to grow single crystalline materials in this system. However, solidification of glasses was easy. Refractive indexes of these glasses were 1.5-1.7. Third-order nonlinear optical effects, ?(3), were larger than that of standard SiO 2 glass at 355 nm. Despite small refractive indexes as oxide glasses, large ?(3) were obtained.
Kimura, H.; Miyazaki, A.; Kannan, C. V.; Cheng, Z. X.
Chemical Compatibility of Barium-Calcium-Aluminosilicate Based Sealing Glasses with Ferritic Stainless Steel Interconnect in SOFCs
In most planar SOFC stack designs, the interconnect, which is typically made from a ferritic stainless steel, is hermitically sealed to the ceramic PEN (Positive electrode-Electrolyte-Negative electrode) by a sealing glass. To maintain the structural stability and minimize degradation of the stack performance, the sealing glass must be chemically compatible with the stainless steel interconnect. In this study, a barium-calcium-aluminosilicate (BCAS) based glass-ceramic, specifically developed as a sealant in SOFC stacks, and a ferritic stainless steel (446) were selected as examples to increase the understanding the chemical compatibility issues in SOFC. Evaluation of the interfaces of coupon joints indicated that interactions between the BCAS glass-ceramic and the ferritic stainless steel was dependent on the exposure conditions. At the edges of joints, where oxygen or air was accessible, the interaction often led to the formation of BaCrO4, while in the interior of the joints, chromium or chromia dissolved into the glass to form a thin layer of chromium rich solid solution. It was also found that, in the interior of the joints, the interaction often resulted in the formation of pores aligned along the interface. It appears the pore formation along the interface can be avoided through a pre-heat treatment.
Yang, Z Gary; Meinhardt, Kerry D.; Stevenson, Jeffry W.
Over the past several years, advances in the design and fabrication of planar SOFCs have led to a steady reduction in the temperatures necessary for their operation. Consequently, it appears more realistic now to use low cost heat resistant alloys for interconnect sub-components in the SOFC stack. Considering these materials requirements, heat resistant alloys, which overall demonstrate oxidation resistance at elevated temperatures, could be potential candidates. Overall, the heat resistant alloys of interest may include superalloys and the stainless steels. Depending whether a chromia or alumina scale forms on the alloy surface for protection, these heat resistant alloys can be also classified into chromia or alumina formers, repetitively. To help screening alloys and understanding the interface of sealing glass, a couple of alloy compositions have been carefully chosen as a reprehensive of different groups of alloys for the study on their chemical compatibility with a barium-aluminosilicate base glass. These alloys selected are AL 29-4, Nicrofer 6025, and Fecralloy, representing chromia forming stainless steels, superalloys and alumina formers, respectively. Results of chemical and microstructural analyses on sealing glass interfaces with different alloys will be presented, and accordingly, the applicability of alloys in terms of sealing glass chemical compatibility will be discussed. Possible means of modification on alloys for an improved applicability will be elaborated as well.
Yang, Z Gary; Weil, K. Scott; Meinhardt, Kerry D.; Stevenson, Jeffry W.; Paxton, Dean M.; Xia, Gordon; Kim, Dong-Sang
RenaGel«, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone
RenaGel«, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone.Background.This multicenter, open-label, dose-titration study assessed the safety and efficacy of RenaGel«, a nonabsorbed calcium- and aluminum-free phosphate binder, in lowering serum phosphorus. Secondary outcomes were its effects on serum intact parathyroid hormone (iPTH) and serum lipids.Methods.Phosphate binders were discontinued during a two-week washout period. Patients whose
Use of calcium\\/aluminum ratios as indicators of stress in forest ecosystems
The calcium\\/aluminum (Ca\\/Al) molar ratio of the soil solution provides a valuable measurement endpoint or ecological indicator for identification of approximate thresholds beyond which the risk of forest damage from Al stress and nutrient imbalances increases. The Ca\\/Al ratio can also be used as an indicator to assess forest ecosystem changes over time in response to acidic deposition, forest harvesting,
Christopher S. Cronan; David F. Grigal
The effects of aluminum loading on selected tissue calcium and magnesium concentrations in rats
Considerable evidence implicates elevated brain aluminum (Al) concentration in the pathogenesis of several forms of central\\u000a nervous system dysfunction seen particularly among dialysis patients. In animals Al intoxication also leads to cerebral dysfunction.\\u000a Since increased brain calcium (Ca) concentration has been associated with similar disturbances of cerebral function, this\\u000a study was initiated to examine the effects of increased Al concentration
Maria A. Burnatowska-Hledin; Gilbert H. Mayor
Photoluminescence of barium-calcium titanates obtained by the microwave-assisted hydrothermal method (MAH)
Ba 1-xCa xTiO 3 ( x = 0, 0.25, 0.50, 0.75, and 1.0) samples report the association of three types of clusters synthesized by the microwave-assisted hydrothermal at 140 ░C for 40 min. In order to evaluate influence of structural order-disorder degree among them, photoluminescence (PL) emission, X-ray diffraction, FT-Raman spectroscopy and Ultraviolet-Visible absorption were used. The PL emission of the crystalline phases grows up with the calcium concentration and reaches the highest PL emission to 0.75 Ca concentration, which is supported by the symmetry break caused by the phase transition. This PL emission is higher than that of the CaTiO 3 phase.
Souza, A. E.; Silva, R. A.; Santos, G. T. A.; Moreira, M. L.; Volanti, D. P.; Teixeira, S. R.; Longo, E.
Measurements of total fast neutron cross sections for aluminum and barium by application of Si(Li)-detectors
Total neutron cross sections of27Al and natural barium have been determined at bombarding energies in the range between 5.5 MeV and 9.6 MeV by transmission measurements. Si(Li)-detectors were used for neutron spectroscopy via charged particle reactions in the active volumes of the detectors. Inscattering corrections have been made by means of a Monte Carlo computer program. In most cases the measured cross sections have root-mean-square uncertainties of 1% to 3%. Cross sections of barium not yet measured have been calculated using optical model potential parameters obtained from an analysis of the experimental results.
Heuer, Rolf-Dieter; Ilgen, Karl
The solidification behavior of calcium oxide-aluminum oxide slags
The binary CaO-Al2O3 based slag and the ternary CaO-Al2O3-MgO based slag are common slags covering and inclusions that are found in calcium treated Al-killed, continuously cast steels. However, the effect of cooling conditions and chemistry on the solidification behavior of these slags is not well characterized. To better understand this phenomena, the solidification behavior of these slags was studied by using double hot thermocouple technique. TTT and CCT diagrams of these slags were determined to quantify the solidification behavior in both dry and humid atmospheres. In this work, these slag samples were easily undercooled and the solidification behavior of these slags was found to be a strong function of cooling conditions. The crystallization tendency of these slags follows the trends suggested by the phase diagram. In CaO-Al2O3 based slags, The eutectic composition (50%CaO) give the lowest crystallization tendency due to the lowest liquidus temperature. In a eutectic CaO-Al2O3 slag sample, dissolved water in the sample increases crystallization tendency and enhances the growth. It was also found that the crystalline phase that formed during cooling in both the dry and humid conditions is the mixture between 3CaO.Al2O 3 and CaO.Al2O3 phases. In CaO-Al2O3-MgO based slags, the crystallization tendency increases with MgO content because the high MgO content leads to the high liquidus temperature. The effect of dissolved of water on the crystallization of CaO-Al2O3-MgO based slags is not as prominent as in the eutectic CaO-Al2O3 slag. Thus, the addition of MgO to CaO-Al2O3 slags was seen to minimize or eliminate the effect of humidity on the solidification of CaO-Al2O3 based slags. In this work, Uhlmann's method was used to estimate the solid-liquid interfacial energy of CaO-Al2O3 based slag for the temperature between 1100--1250░C. The result is between 0.25--0.4 Joules/m 2.
Prapakorn, Kritsada
Oxygen isotopic abundances in calcium- aluminum-rich inclusions from ordinary chondrites: implications for nebular heterogeneity.
The oxygen isotopic compositions of two calcium-aluminum-rich inclusions (CAIs) from the unequilibrated ordinary chondrite meteorites Quinyambie and Semarkona are enriched in 16O by an amount similar to that in CAIs from carbonaceous chondrites. This may indicate that most CAIs formed in a restricted region of the solar nebula and were then unevenly distributed throughout the various chondrite accretion regions. The Semarkona CAI is isotopically homogeneous and contains highly 16O-enriched melilite, supporting the hypothesis that all CAI minerals were originally 16O-rich, but that in most carbonaceous chondrite inclusions some minerals exchanged oxygen isotopes with an external reservoir following crystallization. PMID:9545215
McKeegan, K D; Leshin, L A; Russell, S S; MacPherson, G J
Calcium-aluminum-rich inclusions from enstatite chondrites: indigenous or foreign?
The primary mineral assemblages and initial (26)Al/(27)Al ratios of rare calcium-aluminum-rich inclusions (CAIs) from enstatite (E) chondrites are similar to those of CAIs from other chondrite classes. CAIs from all chondrite classes formed under oxidizing conditions that are much different from the reducing conditions under which the E chondrites formed. Either CAIs formed at an earlier, more oxidizing epoch in the region where E chondrites ultimately formed, or they formed at a different place in the solar nebula and were transported into the E chondrite formation region. PMID:10958775
Guan; Huss; MacPherson; Wasserburg
Extreme 16O Enrichment in Calcium-Aluminum-Rich Inclusions from the Isheyevo (CH\\/CB) Chondrite
Calcium-aluminum-rich inclusions (CAIs) from the metal-rich (CH\\/CB-like) carbonaceous chondrite Isheyevo are mineralogically pristine and show no evidence for postcrystallization alteration. Many of them are composed of very refractory minerals, such as hibonite (CaAl12O19), grossite (CaAl4O7), aluminum-rich pyroxene, and perovskite (CaTiO3). Twenty-eight out of 35 studied CAIs from Isheyevo have oxygen isotopic compositions similar to those of CAIs from the CM
Matthieu Gounelle; Alexander N. Krot; Kazuhide Nagashima; Anton Kearsley
Characterization of Internal Capacitors Based on Glass-Added Barium Titanate
Barium-calcium-aluminum-borosilicate glass is added as a sintering promoter to reduce the sintering temperature of barium titanate. The dielectric properties of the glass-added barium titanate-based internal capacitors are investigated. The dielectric constants of the composites were found to increase with sintering temperature. A capacitance of about 2.3 nF/cm2 with the dissipation factor of 2.9% is obtained for a 20 wt% glass-added BaTiO3 internal capacitor after being cofired with low dielectric constant ceramic substrate at 950░C. The percent change of capacitance is confined within ▒10% and the dissipation factor is stable in the measured temperature range.
Chen, Lih-Shan; Fu, Shen-Li; Lin, Wen-Kuan; Huang, Kwan-Dar
Tantalum oxide and barium sulfate as radiopacifiers in injectable calcium phosphate-poly(lactic-co-glycolic acid) cements for monitoring in vivo degradation.
Monitoring the degradation of calcium phosphate-based bone substitute materials in vivo by means of noninvasive techniques (e.g., radiography) is often a problem due to the chemical resemblance of those substitutes with the mineral phase of bone. In the view of that, the present study aimed at enhancing the radiopacity of calcium phosphate cement enriched with poly(lactic-co-glycolic acid) (CPC-PLGA) microspheres, by adding tantalum oxide (Ta2 O5 ) or the more traditional radiopacifier barium sulfate (BaSO4 ). The radiopacifying capacity of these radiopacifiers was first evaluated in vitro by microcomputed tomography (?CT). Thereafter, both radiopacifiers were tested in vivo using a distal femoral condyle model in rabbits, with subsequent ex vivo ?CT analysis in parallel with histomorphometry. Addition of either one of the radiopacifiers proved to enhance radiopacity of CPC-PLGA in vitro. The in vivo experiment showed that both radiopacifiers did not induce alterations in biological performance compared to plain CPC-PLGA, hence both radiopacifiers can be considered safe and biocompatible. The histomorphometrical assessment of cement degradation and bone formation showed similar values for the three experimental groups. Interestingly, ?CT analysis showed that monitoring cement degradation becomes feasible upon incorporation of either type of radiopacifier, albeit that BaSO4 showed more accuracy compared to Ta2 O5 . ® 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013. PMID:23613219
Hoekstra, Jan Willem M; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Bronkhorst, Ewald M; Meijer, Gert J; Jansen, John A
Growth of highly oriented TlBaŌCaŌCuŌO{sub 9-y} superconducting films on Ag substrates using a dip-coated barium calcium copper oxide sol-gel precursor
Thin films of baŌCaŌCuŌOŌ, a precursor of TlBaŌCaŌCuŌO{sub 9-y}, were prepared by sol-gel synthesis from an all-alkoxide solution. The barium and calcium precursors were the respective metals reacted with 2-methoxyethanol, and the copper precursor was copper methoxide complexed by triethanolamine. Silver substrates were coated using the sol-gel solution by dip-coating. Subsequent processing included a low-temperature drying step (600 C), repeated
M. Paranthaman; D. B. Beach
SOLAR WIND IMPLANTATION MODEL FOR {sup 10}Be IN CALCIUM-ALUMINUM INCLUSIONS
We propose a model for the incorporation of {sup 10}Be within calcium-aluminum inclusions (CAIs) in primitive carbonaceous meteorites. In this model, {sup 10}Be is produced by energetic particle reactions in the proto-solar atmosphere of a more active proto-Sun characterized by energetic particle fluxes higher than contemporary particle fluxes. This {sup 10}Be is incorporated into the solar wind that is then implanted into CAI precursor material. This production mechanism is operational in the contemporary solar system implanting {sup 10}Be in lunar materials. The contemporary production rate of {sup 10}Be at the surface of the Sun is {approx}0.1 {sup 10}Be cm{sup -2} s{sup -1}. Scaling up the contemporary {sup 10}Be production in the proto-Sun by a factor of 10{sup 5} would increase the production rate to 10{sup 410}Be cm{sup -2} s{sup -1}. Using this enhanced production value in conjunction with refractory mass inflow rates at 0.06 AU from the proto-Sun we model {sup 10}Be concentrations in CAI precursors. We calculate the content of solar-wind-implanted {sup 10}Be would have been of the order of 10{sup 1210}Be g{sup -1} in CAIs, consistent with initial{sup 10}Be content found from boron-beryllium isotopic systematics in CAIs.
Bricker, Glynn E. [Department of Mathematics, Statistics, and Physics, Purdue University North Central, Schwarz Bldg, Westville, IN 46391 (United States); Caffee, Marc W., E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Department of Physics, Primelab: Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907 (United States)
Extinct 10Be in Type A calcium-aluminum-rich inclusions from CV chondrites
We have found clear evidence of live 10Be in five normal Type A Calcium-aluminum-rich inclusions (CAIs), one normal Type B CAI, and one FUN Type A CAI, all from CV3 chondrites. The ( 10Be/ 9Be) 0 ratios range from ś0.36 ū 10 -3 to ś0.77 ū 10 -3 and are similar to those found by previous workers. The ( 10Be/ 9Be) 0 ratios do not correlate in a temporal fashion with ( 26Al/ 27Al) 0, suggesting that 10Be and 26Al were produced by different mechanisms. An examination of possible sources for the short-lived radionuclides indicates that production of 10Be was almost certainly by particle irradiation, possibly within the solar system, and was probably accompanied by significant production of 41Ca and 53Mn. In contrast, all of the 60Fe, most of the 26Al, and some of the 53Mn were probably produced in stars and were imported into the solar system within presolar dust grains.
MacPherson, Glenn J.; Huss, Gary R.; Davis, Andrew M.
Disturbance of Intracellular calcium homeostasis and CaMKII/CREB signaling is associated with learning and memory impairments induced by chronic aluminum exposure.
Aluminum-induced neuronal injury has been implicated in various neurodegenerative disorders. However, the underlying mechanism involved in this pathogenesis still remains unknown. Our present findings demonstrated that chronic aluminum exposure resulted in spatial learning impairment and significantly increased intracellular calcium level in the hippocampus of rats. Examination of the associated protein molecules essential for induction and maintenance of long-term potentiation revealed that aluminum exposure could increase the expression level of calmodulin (CaM), but the expression levels of CaM-dependent protein kinase II (CaMKII), and phosphorylated cAMP-responsive element binding protein (CREB) were significantly reduced, whereas the total protein levels of CaMKII and CREB did not change in the aluminum-treated hippocampus. Thus, we provide a previously unrecognized mechanism whereby chronic aluminum exposure impairs hippocampal learning and memory, at least in part, through disruption of intracellular calcium homeostasis and CaM/CaMKII/CREB signaling pathway. PMID:24366850
Wang, Biao; Zhao, Jiuhan; Yu, Meng; Meng, Xin; Cui, Xin; Zhao, Yan; Zhu, Yuyan; Xing, Wei; Guan, Yifu
The formation of rims on calcium-aluminum-rich inclusions: Step I-Flash heating
Wark-Lovering rims of six calcium-aluminum-rich inclusions (CAIs) representing the main CAI types and groups in Allende, Efremovka and Vigarano were microsurgically separated and analysed by neutron activation analysis (NAA). All the rims have similar ~4x enrichments, relative to the interiors, of highly refractory lithophile and siderophile elements. The NAA results are confirmed by ion microprobe and scanning electron microscope (SEM) analyses of rim perovskites and rim metal grains. Less refractory Eu, Yb, V, Sr, Ca and Ni are less enriched in the rims. The refractory element patterns in the rims parallel the patterns in the outer parts of the CAIs. In particular, the rims on type B1 CAIs have the igneously fractionated rare earth element (REE) pattern of the melilite mantle below the rim and not the REE pattern of the bulk CAI, proving that the refractory elements in the rims were derived from the outer mantle and were not condensates onto the CAIs. The refractory elements were enriched in an Al2O3-rich residue <50 um thick after the most volatile ~80% of the outermost 200 um of each CAI had been volatilized, including much Mg, Si and Ca. Some volatilization occurred below the rim, and created refractory partial melts that crystallized hibonite and gehlenitic melilite. The required "flash heating" probably exceeded 2000 degrees C, but for only a few seconds, in order to melt only the outer CAI and to unselectively volatilize slow-diffusing O isotopes which show no mass fractionation in the rim. The volatilization did, however, produce "heavy" mass-fractionated Mg in rims. In some CAIs this was later obscured when "normal" Mg diffused in from accreted olivine grains at relatively high temperature (not the lower temperature meteorite metamorphism) and created the ~50 um set of monomineralic rim layers of pyroxene, melilite and spinel.
Wark, David; Boynton, William V.
... calcium. Veggies. You'll also find calcium in broccoli and dark green, leafy vegetables (especially collard and ... of calcium such as dark green, leafy vegetables, broccoli, chickpeas, and calcium-fortified products, including orange juice, ...
Calmodulin concentration in mucus of rainbow trout, Salmo gairdneri, exposed to combinations of acid, aluminum, and calcium
As a result of increasing acidification in various watersheds elevated levels of aluminum have been observed in soil and surface water. The toxicity of Al to fish has been shown to be positively correlated with the concentration of inorganic monomeric. The exact mechanism(s) of Al toxicity is not fully understood. Recently, the presence of calmodulin (CaM), a calcium-regulating protein, has been reported in fish gills and mucus. Calmodulin selectively binds inorganic monomeric Al causing conformational changes in the protein. Aluminum-induced conformational changes cause a reduction in the ability of calmodulin to mediate Ca-dependent phosphodiesterase and ATPase activity. Calmodulin also plays a key role in coordinating the effects of secondary messenger systems in response to cellular stimulation. Given the involvement of calmodulin in numerous biochemical pathways, its interaction with aluminum may be a key lesion in the broadly defined syndrome of aluminum toxicity. The present study was undertaken to establish a relationship between Al concentration in aqueous solution and the quantity and activity of CaM in the mucus of adult rainbow trout (Salmo gairdneri). Fish were exposed to various levels of pH, Ca, and Al. Mucus was collected and the amount of CaM was determined. The ability of the Al-exposed CaM to activate the phosphodiesterase enzyme system was also evaluated.
Lewis, T.E. (Lockheed Engineering and Sciences Company, Las Vegas, NV (USA)); Yuan, Shixing; Haug, A. (Michigan State Univ., East Lansing (USA))
Geochemical reactions and dynamics during titration of a contaminated groundwater with high uranium, aluminum, and calcium
This study investigated possible geochemical reactions during titration of a contaminated groundwater with a low pH but high concentrations of aluminum, calcium, magnesium, manganese, and trace contaminant metals/radionuclides such as uranium, technetium, nickel, and cobalt. Both Na-carbonate and hydroxide were used as titrants, and a geochemical equilibrium reaction path model was employed to predict aqueous species and mineral precipitation during titration. Although the model appeared to be adequate to describe the concentration profiles of some metal cations, solution pH, and mineral precipitates, it failed to describe the concentrations of U during titration and its precipitation. Most U (as uranyl, UO 22+) as well as Tc (as pertechnetate, TcO 4-) were found to be sorbed and coprecipitated with amorphous Al and Fe oxyhydroxides at pH below ś5.5, but slow desorption or dissolution of U and Tc occurred at higher pH values when Na 2CO 3 was used as the titrant. In general, the precipitation of major cationic species followed the order of Fe(OH) 3 and/or FeCo 0.1(OH) 3.2, Al 4(OH) 10SO 4, MnCO 3, CaCO 3, conversion of Al 4(OH) 10SO 4 to Al(OH) 3,am, Mn(OH) 2, Mg(OH) 2, MgCO 3, and Ca(OH) 2. The formation of mixed or double hydroxide phases of Ni and Co with Al and Fe oxyhydroxides was thought to be responsible for the removal of Ni and Co in solution. Results of this study indicate that, although the hydrolysis and precipitation of a single cation are known, complex reactions such as sorption/desorption, coprecipitation of mixed mineral phases, and their dissolution could occur simultaneously. These processes as well as the kinetic constraints must be considered in the design of the remediation strategies and modeling to better predict the activities of various metal species and solid precipitates during pre- and post-groundwater treatment practices.
Gu, Baohua; Brooks, Scott C.; Roh, Yul; Jardine, Philip M.
Calcium-aluminum-silicate-hydrate "cement" phases and rare Ca-zeolite association at Colle Fabbri, Central Italy
Very high temperature, Ca-rich alkaline magma intruded an argillite formation at Colle Fabbri, Central Italy, producing cordierite-tridymite metamorphism in the country rocks. An intense Ba-rich sulphate-carbonate-alkaline hydrothermal plume produced a zone of mineralization several meters thick around the igneous body. Reaction of hydrothermal fluids with country rocks formed calcium-silicate-hydrate (CSH), i.e., tobermorite-afwillite-jennite; calcium-aluminum-silicate-hydrate (CASH) Ś "cement" phases - i.e., thaumasite, strõtlingite and an ettringite-like phase and several different species of zeolites: chabazite-Ca, willhendersonite, gismon-dine, three phases bearing Ca with the same or perhaps lower symmetry of phillipsite-Ca, levyne-Ca and the Ca-rich analogue of merlinoite. In addition, apophyllite-(KF) and/or apophyllite-(KOH), Ca-Ba-carbonates, portlandite and sulphates were present. A new polymorph from the pyrrhotite group, containing three layers of sphalerite-type structure in the unit cell, is reported for the first time. Such a complex association is unique. Most of these minerals are specifically related to hydration processes of: (1) pyrometamorphic metacarbonate/metapelitic rocks (natural analogues of cement clinkers); (2) mineralization between intrusive stocks and slates; and (3) high-calcium, alkaline igneous rocks such as melilitites and foidites as well as carbonatites. The Colle Fabbri outcrop offers an opportunity to study in situ complex crystalline overgrowth and specific crystal chemistry in mineral phases formed in igneous to hydrothermal conditions.
Stoppa, F.; Scordari, F.; Mesto, E.; Sharygin, V. V.; Bortolozzi, G.
Physiological and toxicological effects of long-term exposure to acid, aluminum, and low calcium on adult brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri)
Although the toxic effects of these three parameters were highly interactive, survival and growth of adult brook trout were reduced at elevated aluminum concentrations. Only 40 ug/L aluminum was necessary to produce similar responses in rainbow trout. Neither species was sensitive to pH alone in the range 4.5-6.5 except at very low calcium concentrations. Reductions in fecundity were observed, but only as a result of decreased growth. Progeny spawned from brook trout that had been exposed to 0.5 mg/L calcium were more sensitive to continued exposure to acid, aluminum and low calcium than were progeny of control fish. Physiologically, brook and rainbow trout responded similarly to sublethal acid, aluminum and low calcium stress. All fish exposed to depressed pH showed reductions in plasma sodium, but in most cases they were able to maintain normal plasma osmolality. But those fish stressed most severely displayed an entire suite of disturbances, including decreased survival, growth and feeding, as well as abnormal vitellogenesis and ionoregulatory failure.
Mount, D.R.
Investigation of Acid Deposition Effects on Southern Appalachian Red Spruce (Picea rubens) by Determination of Calcium, Magnesium, and Aluminum in Foliage and Surrounding Soil Using Icp-Oes
Red spruce (Picea rubens) are conifers found at high elevations (above 1370Ām) sites in the Southern Appalachian Mountains. A decline of red spruce forests in the Southern Appalachian Mountains caused by atmospheric acid deposition has been reported since the 1970s. Acid deposition leaches essential nutrients (calcium and magnesium) out of the soil and increases the availability of toxic metals (aluminum)
Matthew B. Rosenberg; David J. Butcher
Electrical and chemical analysis of zinc oxide interfaces with high dielectric constant barium tantalate and aluminum oxide in metal-insulator-semiconductor structures fabricated at Low temperatures
Zinc oxide (ZnO) was incorporated into metal-insulator-semiconductor (MIS) structures featuring high dielectric constant (high-?) barium tantalate (BaTa2O6)or alumina (Al2O3)as the insulator, and the structures were electrically evaluated for potential applications in transparent thin film transistors. The ZnO films were deposited by radio-frequency magnetron sputtering at 100░C whereas the dielectric films were deposited by the same method at room temperature. The
Fang-Ling Kuo; Mohammad H. Maneshian; Nigel D. Shepherd
Microstructure characterization and micro- and nanoscale mechanical behaviour of magnesium-aluminum and magnesium-aluminum-calcium alloys
The application in the automotive industry of the as-cast AM50 alloy (Mg-5.0 wt.%%Al-0.3 wt.%Mn) has been limited by its low creep resistance at elevated temperatures. Permanent mold cast (PM) Mg-Al-Ca alloys with calcium additions (0 ś 2.0 wt.%) were investigated in this study due to their potential for improving the high temperature creep strength. The microstructures of the die cast (DC) or PM AM50 alloys consisted of an intergranular beta-Mg17Al12 phase surrounded by a region of Al-rich eutectic alpha-Mg phase, sometimes with attached Al8Mn5 particles. In this study, significant grain refinement was observed in the PM Mg-Al-Ca alloys with Ca addition to the AM50 alloy. The grain refining effect was confirmed by quantitative image analysis through measurement of the secondary dendrite arm spacing (SDAS). The intergranular phases in Mg-Al-Ca alloys with 0.5 or 1.0 wt.% Ca were beta-Mg17Al 12 and (Al, Mg)2Ca phases. As the Ca addition was increased to 1.5 wt.% Ca, the (beta-Mg17Al12 phase was completely replaced by a (Al, Mg)2Ca phase. Differential scanning calorimetry (DSC) results showed that the (Al, Mg)2Ca phase was thermally more stable than the beta-Mg 17Al12 phase, which contributed to the better creep strength of the Mg-Al-Ca alloys. The change in heating/cooling rates played an important role in the redistribution of alloying elements and the dissolution or precipitation of the eutectic phases in the as-cast Mg alloys during DSC runs. The micro- and nano-scale hardness and composite modulus of the PM Mg-Al-Ca alloys increased with increasing Ca content, and the indentation size effect (ISE) was also observed in the as-cast Mg-Al and Mg-Al-Ca alloys. PM AC52 alloy (Mg-5.0wt.%Al-2.0wt.%Ca) was a much more creep resistant alloy than other Mg-Al-Ca alloys with lower Ca contents because of the higher solute content in the primary alpha-Mg in the as-cast state and also because of the presence of nano precipitates within the primary alpha-Mg. The size and volume fraction of the precipitates and the solute content within the primary alpha-Mg of the AC52 alloys were related to the different solidification rates, which directly influence the nano indentation creep strength of the alloys.
Han, Lihong
Neonatal Parenteral Nutrition Containing Calcium Chloride and Sodium Phosphate: Mineral Intake and Aluminum Content
Objective. The authorsÆ objectives were to determine mineral as well as Al intakes for ?1000 g birth weight (ELBW) infants supported with parenteral nutrition (PN) solutions containing calcium chloride (CaCl) and sodium phosphate (NaPhos). Study design. This study was a prospective cohort study of 32 ELBW infants. Nutrient and Al intakes were recorded based on actual fluid intakes and concentrations
Robert K. Huston; Elizabeth A. McCulley; Andrea M. Markell; Carl F. Heisel; Patrick K. Lewallen
Associations of calcium and aluminum with the growth and health of sugar maple trees in Vermont
We compared tree growth and crown condition with soil and foliar elemental composition in 14 sugar maple (Acer saccharum Marsh.) stands in VT, USA, to evaluate if deficiencies or imbalances in cation nutrition were associated with growth and health reductions in native stands. The Till Source Model (TSM) was used to select study sites potentially high or low in calcium
Paul G. Schaberg; James W. Tilley; Gary J. Hawley; Donald H. DeHayes; Scott W. Bailey
Development of calcium zirconate-based hydrogen sensors with oxide reference electrodes for molten aluminum
Hydrogen is a major cause of gas porosity in aluminum and is frequently removed from the melt prior to casting. The degassing process can be better controlled if the hydrogen content in the melt is known. Thus, gas sensors which can make continuous in situ measurements in molten aluminum are needed. Current online hydrogen sensing systems are complex designs which are prohibitively expensive. Solid electrolyte based potentiometric sensors have been developed as an attractive alternate. These sensors have traditionally used a gas phase as the reference electrode. The present design has a condensed-phase reference electrode to avoid the need for transport of the reference gas into and out of the melt. The use of an oxide rather than a hydride phase reference is expected to considerably lower device cost and improve shelf life and reliability. The sensor element consists of a solid electrolyte tube based on 10 mol% Indoped CaZrO3, which was synthesized using both solid oxide and oxalate co-precipitation techniques. Precursor oxalate powders prepared using polymeric surfactants (PEG) were characterized using SEM, XRD, FTIR and particle size analysis. PEG was found to reduce particle size and also influence the process of perovskite formation. The oxalate co-precipitation technique enabled powder synthesis at reduced processing time and temperature. Closed-one-end tubes were slip cast and densified for use as solid electrolytes. Impedance spectroscopy and D.C. resistance measurements were made at temperatures between 650 and 900░C. Undoped CaZrO3 was found to be a p-type conductor in air. Indoped CaZrO3 acted as a proton conductor in air and argon+H2O, whereas the material was found to be a p-type conductor in pure argon. While bulk conduction was found to be homogenous with activation energies matching those from D.C. measurements, conduction across the grain boundary was found to be heterogeneous. Potentiometric sensors using In-doped CaZrO3 as the electrolyte, and metal/metal oxides, metal/metal hydrides as the reference electrodes were fabricated. Sensors with Mg-MgO reference electrodes, on exposure to argon and aluminum environments, generated a potential matching the Nernstian voltage. Sensors with Ca-CaH2 reference electrodes measured the Nernstian potential when exposed to 5%H2. Laboratory tests conducted using gas mixtures also showed sensors with Mg-MgO reference electrodes to measure changes in hydrogen concentration. Pilot plant testing of sensor prototypes was carried out in commercial aluminum alloy melts and the sensors were found to respond to hydrogen degassing. The response of these sensors to changes in the gas content of the melt correlated reasonably well with that of a commercially available system for measuring hydrogen content in molten aluminum (AlScan(TM)).
Krishnan, Vivek
The Case for Rarity of Chondrules and Calcium?Aluminum¢rich Inclusions in the Early Solar System and Some Implications for Astrophysical Models
The high-temperature materials in chondritic meteorites, the chondrules (silicate spherules produced by čash heating) and refractory inclusions (the CAI, or calcium-aluminum╚rich inclusions), have been used to place major constraints on astrophysical models for the early solar system. Among the meteor- ites falling to Earth, the CAI are rare, being only 15% by volume of a class that constitutes 0.84% of
Derek W. G. Sears
The simultaneous removal of calcium, magnesium and chloride ions from industrial wastewater using magnesium-aluminum oxide.
In this article, a method for simultaneous removal of calcium, magnesium and chloride by using Mg0.80Al0.20O1.10 as a Magnesium-Aluminum oxide (Mg?Al oxide) was investigated. Mg?Al oxide obtained by thermal decomposition of the Mg-Al layered double hydroxide (Mg-Al LDH). The synthesized Mg?Al oxide were characterized with respect to nitrogen physicosorption, X-ray diffraction (XRD) and field emission scan electron microscopy (FESEM) morphology. Due to high anion-exchange capacity of Mg?Al oxide, it was employed in simultaneously removal of Cl(-), Mg(+2) and Ca(+2) from distiller waste of a sodium carbonate production factory. For this purpose, experiments were designed to evaluate the effects of quantity of Mg?Al oxide, temperature and time on the removal process. The removal of Cl(-), Mg(+2) and Ca(+2) from wastewater was found 93.9%, 93.74% and 93.25% at 60░C after 0.5Āh, respectively. Results showed that the removal of Cl(-), Mg(+2) and Ca(+2) by Mg?Al oxide increased with increasing temperature, time and Mg?Al oxide quantity. PMID:23647113
Hamidi, Roya; Kahforoushan, Davood; Fatehifar, Esmaeil
Emission spectrographic determination of barium in sea water using a cation exchange concentration procedure
USGS Publications Warehouse
A concentration technique employing Dowex 50W cation exchange resin is described for the determination of barium in sea water. The separated barium is precipitated as fluoride together with calcium and strontium and measured by emission spectrographic analysis. The vertical distribution of barium in sea water has been measured in the Caribbean Sea and the Atlantic Ocean. The barium content varied between 7 and 23 ??g. per liter; in two profiles, the lowest concentrations were at a depth of about 1000 meters.
Szabo, B. J.; Joensuu, O.
High-calcium flue gas desulfurization products reduce aluminum toxicity in an Appalachian soil
An acid Appalachian soil was amended with two flue gas desulfurization (FGD) by-products, one consisting of wallboard-quality gypsum (CaSO{sub 4}{center_dot}2H{sub 2}) and the other containing CaSO{sub 3}{center_dot}0.5H{sub 2}O as a major component. Soil columns treated with FGD by-products were leached with deionized H{sub 2}O under unsaturated conditions. Aluminum amounts leached increased 25-fold over the control when CaSO{sub 4}{center_dot}2H{sub 2}O FGD by-product was incorporated into the soil. Leachate pH decreased with FGD product treatment, but bulk soil pH increased, and exchangeable Al and total soil acidity decreased. Mean 4-d root lengths of sudangrass (Sorghum bicolor L. Moench) seedlings grown in the leached soils were as much as 440 and 310% the value of the control for CaSO{sub 3}{center_dot}0.5H{sub 2}O and CaSO{sub 4}{center_dot}2H{sub 2}O treatments, respectively. Mechanisms by which mitigation of Al toxicity occurs with addition of high-Ca FGD by-products to acid soils are discussed. 48 refs., 8 figs., 6 tabs.
Wendell, R.R.; Ritchey, K.D. [USDA-ARS, Beaver, WV (United States)
Binding and Leakage of Barium in Alginate Microbeads
Microbeads of alginate cross-linked with Ca2+ and/or Ba2+ are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared to high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. In order to reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation.
M?rch, Yrr A.; Qi, Meirigeng; Gundersen, Per Ole M.; Formo, Kjetil; Lacik, Igor; Skjak-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L.
Barium enema (image)
A barium enema is performed to examine the walls of the colon. During the procedure, a well lubricated enema tube is inserted gently into the rectum. The barium, a radiopaque (shows up on X-ray) contrast ...
Calcium ?-Hydroxy-?-Methylbutyrate
The binding capacity of calcium ?-hydroxy-?-methylbutyrate (calcium HMB), compared to other binders, was investigated in an in vitro study. Fifty milli-equivalents of either calcium HMB, calcium acetate, calcium carbonate, aluminum hydroxide gel or non-gel aluminum hydroxide was added to a phosphate solution, titrated (HC1 or NaOH), shaken and centrifuged to four different pH levels at 37 ░C (simulating the gastrointestinal
Mauri F. Sousa; Naji N. Abumrad; Cristina Martins; Steven Nissen; Miguel C. Riella
Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores
Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author
Meeker, G. P.
Isotopically uniform, 16O-depleted calcium, aluminum-rich inclusions in CH and CB carbonaceous chondrites
In situ oxygen-isotope measurements of calcium-aluminum-rich inclusions (CAIs) from the metal-rich carbonaceous chondrites Isheyevo (CH/CB-like), Acfer 214 paired with Acfer 182 (CH), QUE 94411 paired with QUE 94627 (CBb), and Hammadah al Hamra 237 (CBb) revealed the presence of a common population of igneous, isotopically uniform, 16O-depleted inclusions: ?17O (average ▒ 2 standard deviations) = -7 ▒ 4ē, -6 ▒ 5ē, and -8 ▒ 3ē, respectively. All CAIs from CBs and a significant fraction of those from CHs and Isheyevo are 16O-depleted. Most of the 16O-depleted CAIs consist of Ti-poor Al-diopside, spinel, melilite, and forsterite and surrounded by a single- and double-layered rim of forsterite ▒ diopside. The 16O-depleted CAIs composed of hibonite, grossite, melilite, and spinel, and surrounded by the multilayered melilite + diopside ▒ forsterite rims are less common. Some of the 16O-depleted refractory igneous inclusions composed of Al-diopside, forsterite, and ▒spinel have chondrule-like textures (skeletal or barred). They are mineralogically most similar to Al-diopside-rich chondrules found in metal-rich carbonaceous chondrites and composed of Al-diopside, forsterite, Al-rich low-Ca pyroxene, ▒glassy mesostasis, and ▒spinel, suggesting there is a continuum between these objects. We suggest that (i) most of the isotopically uniform and 16O-depleted CAIs resulted from remelting of pre-existing, possibly 16O-rich refractory inclusions. The remelting may have occurred during formation of the magnesian, non-porphyritic (cryptocrystalline and skeletal) chondrules in CHs, CBs, and Isheyevo either by an unspecified, late, single-stage, highly-energetic event or in an impact-generated plume previously hypothesized for their origin; both mechanisms probably occurred in the solar nebula (i.e., in the presence of the nebula gas). The forsterite ▒ pyroxene rims around 16O-depleted CAIs may have resulted from evaporation-recondensation of silicon and magnesium during this event. Some of the Al-diopside-rich CAIs may have formed by evaporation of the Al-rich chondrule melts. (ii) In addition to these components, the CHs and Isheyevo contain a high abundance of chondrules and refractory inclusions formed by the commonly inferred nebular processes - evaporation, condensation, and incomplete melting of dust aggregates during multiple transient heating events. These include 16O-rich CAIs, amoeboid olivine aggregates, and ferromagnesian and aluminum-rich chondrules with porphyritic textures. Such components are also present in CB chondrites, but they are exceptionally rare. These observations indicate that there are multiple generations of CAIs in metal-rich carbonaceous chondrites. (iii) Because the isotopically uniform, 16O-depleted, igneous CAIs and the magnesian cryptocrystalline and skeletal olivine-pyroxene chondrules are found almost exclusively in metal-rich carbonaceous chondrites, the hypothesized impact-plume mechanism of chondrule formation and recycling of CAIs are not common processes.
Krot, Alexander N.; Nagashima, Kazuhide; Petaev, Michail I.
Barium titanium glycolate: A new barium titanate powder precursor
This paper describes the synthesis and structure of a barium titanium glycolate complex and the calcination into barium titanate preceramic powders that sinter into polycrystalline, tetragonal barium titanate having good dielectric properties.
Day, V.W.; Klemperer, W.G.; Payne, D.A. [Univ. of Nebraska, Lincoln, NE (United States)] [and others] [Univ. of Nebraska, Lincoln, NE (United States); and others
Victor W. Day; W. G. Klemperer; D. A. Payne; Shurong Liang
Molecular Structure of Barium Chloride
NSDL National Science Digital Library
Barium Chloride was the byproduct of the discovery of radium by Madame Curie. When refining radium, the final separation resulted in barium chloride and radium chloride. Electrophoresis of barium chloride produces small-scale amounts of barium atom. This can be used for obtaining barium for commercial uses. Applications of barium chloride include stimulating the heart and other muscles for medicinal purposes, and also for softening water. Other uses of barium chloride include the manufacturing of barium salts, as pesticide, pigments, boiler detergent, in purifying sugar, as mordant in dyeing and printing textiles, and in the manufacture of caustic soda, polymers, and stabilizers.
Beta barium borate (BBO)
The paper contains a review of crystallographic, optical and nonlinear optical properties of beta barium borate (▀-BaB2O4 or BBO) crystal and presents a description of its typical applications in nonlinear optics and quantum electronics.
D. N. Nikogosyan
Controlling barium sulfate
Even though for several years success has been realized in controlling barium sulfate scale deposition in relatively shallow, low pressure oil wells--by squeezing an organic phosphonate scale inhibitor into the producing zone--barium sulfate scale depositon in deep, high pressure\\/high temperature wells usually meant an expensive workover operation. A case history of a deep (16,000 ft) well in St. Mary Parish,
Removal of arsenic(III) and arsenic(IV) ions from aqueous solutions with lanthanum(III) salt and comparison with aluminum(III), calcium(II), and iron(III) salts
Interactions of arsenic(III) and arsenic(V) ions with a lanthanum salt were studied with the aim of developing a new precipitation method for removal of arsenic from aqueous solutions. Performance was compared to those of aluminum, polyaluminum chloride (PAC), calcium, and iron(III) salts. Arsenic(III) was removed by iron(III) and lanthanum in a narrow pH range with less than 605 removal. Arsenic(V) was removed more efficiently by aluminum, PAC, iron(III), and lanthanum. Lanthanum was most effective, meeting Japanese effluent and drinking water standards by adding three times as much lanthanum as arsenic(V).
Tokunaga, S.; Yokoyama, S.; Wasay, S.A.
Observed Barium Emission Rates
The barium releases from the CRRES satellite have provided an opportunity for verifying theoretically calculated barium ion and neutral emission rates. Spectra of the five Caribbean releases in the summer of 1991 were taken with a spectrograph on board a U.S. Air Force jet aircraft. Because the line of sight release densities are not known, only relative rates could be obtained. The observed relative rates agree well with the theoretically calculated rates and, together with other observations, confirm the earlier detailed theoretical emission rates. The calculated emission rates can thus with good accuracy be used with photometric observations. It has been postulated that charge exchange between neutral barium and oxygen ions represents a significant source for ionization. If so. it should be associated with emissions at 4957.15 A and 5013.00 A, but these emissions were not detected.
Stenbaek-Nielsen, H. C.; Wescott, E. M.; Hallinan, T. J.
Ultra-low temperature processing of barium tellurate dielectrics
Ceramics, metals and polymers have unique electrical properties that are combined for electronic devices and systems. It necessitates lower processing temperatures for ceramics to be compatible with metal and polymer systems. In this thesis, the synthesis, crystal structure, and dielectric properties of barium tellurate are studied for temperatures between 500 and 900░C. Barium tellurate dielectric ceramics (BaTe4O9, BaTe 2O5, BaTe2O6, BaTeO3, BaTeO 4, and Ba2TeO5) are extensively investigated as new LTCC (Low-Temperature Cofired Ceramics) dielectric systems integrated with low resistivity metal electrodes such as silver and aluminum for microwave application. Studies on the phase formation and crystal structure through thermal analyses (Differential Scanning Calorimetry and Thermogravimetric Analysis, DSC-TGA) and X-ray diffraction phase analysis attest that barium tellurates are formed in the temperature range of 500 ś 900░C, through the sequential phase formations from Te-rich to Ba-rich phases. The oxygen coordination of the tellurium ion progresses from TeO4 to TeO6 via TeO 3+1 and TeO3 with increasing barium content as confirmed by structural analysis using infrared spectroscopy. High density barium tellurate ceramics are achieved at temperatures as low as 550░C, which provides the potential to be co-fired with low-melting aluminum metal electrodes in LTCC processing. Dielectric permittivity, loss, and temperature stability of barium tellurate dielectric ceramics were measured from 100 Hz to 13 GHz. Barium tellurate ceramics exhibit excellent microwave dielectric properties with intermediate dielectric permittivities and high quality factors (Q). The dielectric properties at microwave frequencies are epsilonr = 17.5, Qxf = 54700 GHz, TCf = -90 ppm/░C for BaTe4O9, epsilonr = 21, Qxf = 50300 GHz, TCf = -51 ppm/░C for BaTe2O6, epsilonr = 10, Qxf = 34000 GHz, TCf = -54 ppm/░C for BaTeO3, and epsilonr = 17, Qx f = 49600 GHz, TCf = -124 ppm/░C for Ba 2TeO5. Co-firing studies of barium tellurate ceramics with metal electrodes establish new LTCC systems for microwave devices. Chemical compatibility of barium tellurates with silver electrodes was achieved in the barium rich compositions. Ba2TeO5 was found to be covetable with silver electrodes at 850░C by adding CuO and B2O3 as fluxing agents. During the co-firing, a thin interfacial layer of AgTe is metastable according to the thermodynamic equilibrium between the Ba2TeO5-Ag/Ag 2O pseudo-binary system. A breakthrough LTCC technology with aluminum is based upon the ultra-low processing temperature and chemical compatibility of BaTe4O 9, which enables co-firing and fabrication of multilayer ceramic capacitors (MLCCs) with aluminum inner electrodes. The aluminum base metal electrode (BME) BaTe4O9 MLCCs provide good dielectric properties of epsilonr = 17.5, TCepsilon = 100 ppm/░C, and tan delta = 2.1 x 10-3 (Q ? 500) at 1 MHz, which are suitable for the class-1 MLCCs. Aluminum microstrip ring resonators on the BaTe4O9 substrates realized good electromagnetic performance of the new materials at microwave frequency exhibiting resonant frequency of 2.97 GHz and Q factor of 278.
Kwon, Do-Kyun
Superconductivity in barium fulleride
The intercalation of fulleride with barium is reported. A pure body-centered cubic phase with a lattice constant of 11.171 A is realized near a stoichiometry of Ba6C60. This phase is also superconducting, suggesting that the mechanism of superconductivity is related to an intrinsic property of the C60 molecules, rather than the external coordination number.
Kortan, A. R.; Kopylov, N.; Glarum, S.; Gyorgy, E. M.; Ramirez, A. P.; Fleming, R. M.; Zhou, O.; Thiel, F. A.; Trevor, P. L.; Haddon, R. C.
Semiconducting barium titanate
Barium titanate, which is well known as a basic ferroelectric material, is also of interest when doped because of the interaction between semiconductivity and ferroelectricity. The resistance of blocking layers at surfaces and grain-boundaries is governed mainly by the ferroelectric properties, so that a resistance jump of four decades is observed on heating above the Curie temperature. A survey of
W. Heywang
Factors controlling soil water and stream water aluminum concentrations after a clearcut in a forested watershed with calcium-poor soils
The 24 ha Dry Creek watershed in the Catskill Mountains of southeastern New York State USA was clearcut during the winter of 1996-1997. The interactions among acidity, nitrate (NO3- ), aluminum (Al), and calcium (Ca2+) in streamwater, soil water, and groundwater were evaluated to determine how they affected the speciation, solubility, and concentrations of Al after the harvest. Watershed soils were characterized by low base saturation, high exchangeable Al concentrations, and low exchangeable base cation concentrations prior to the harvest. Mean streamwater NO3- concentration was about 20 ??mol l-1 for the 3 years before the harvest, increased sharply after the harvest, and peaked at 1,309 ??mol l -1 about 5 months after the harvest. Nitrate and inorganic monomeric aluminum (Alim) export increased by 4-fold during the first year after the harvest. Alim mobilization is of concern because it is toxic to some fish species and can inhibit the uptake of Ca2+ by tree roots. Organic complexation appeared to control Al solubility in the O horizon while ion exchange and possibly equilibrium with imogolite appeared to control Al solubility in the B horizon. Alim and NO3- concentrations were strongly correlated in B-horizon soil water after the clearcut (r2 = 0.96), especially at NO3- concentrations greater than 100 ??mol l-1. Groundwater entering the stream from perennial springs contained high concentrations of base cations and low concentrations of NO3- which mixed with acidic, high Alim soil water and decreased the concentration of Alim in streamwater after the harvest. Five years after the harvest soil water NO 3- concentrations had dropped below preharvest levels as the demand for nitrogen by regenerating vegetation increased, but groundwater NO3- concentrations remained elevated because groundwater has a longer residence time. As a result streamwater NO3- concentrations had not fallen below preharvest levels, even during the growing season, 5 years after the harvest because of the contribution of groundwater to the stream. Streamwater NO3- and Alim concentrations increased more than reported in previous forest harvesting studies and the recovery was slower likely because the watershed has experienced several decades of acid deposition that has depleted initially base-poor soils of exchangeable base cations and caused long-term acidification of the soil. ?? 2007 Springer Science+Business Media B.V.
McHale, M. R.; Burns, D. A.; Lawrence, G. B.; Murdoch, P. S.
Fluorescence and FT-IR spectroscopic studies of Suwannee River fulvic acid complexation with aluminum, terbium and calcium.
In this study fluorescence emission and IR spectroscopy have been used to investigate the interaction of the class A (oxygen seeking "hard acid") metal Al(3+), with Suwannee River fulvic acid. Addition of Al(3+) ion results in a significant enhancement in fulvic acid fluorescence emission (at lambda(em)=424 nm) and significant red shift of the excitation wavelength (from lambda(ex)=324 nm to lambda(ex)=344 nm) at low pH values (pH approximately 4.0-5.0). At pH 4.0 (0.1 M ionic strength), where the predominant aluminum ion species is the "free" (aquo) ion, the fulvic acid fluorescence reaches 142% of the value in the absence of added metal ion. Analysis of the pH 4.0 and pH 5.0 fluorescence enhancement data with the nonlinear (single site) model of Ryan and Weber indicated binding constants in the range of 4.67.10(4)-2.87.10(6) M(-1) and concentrations of ligand sites in the range of 18.6.10(-6)-24.0.10(-6) M, both consistent with previous studies performed on both aquatic and soil fulvic acids. Companion fluorescence experiments performed on two other class A metal ions, Ca(2+) and Tb(3+), indicated no significant enhancement or quenching with Ca(2+) and only slight quenching with Tb(3+). Comparison of FT-IR spectra collected on fulvic acid alone and fulvic acid in the presence of the three class A metals (Al(3+), Ca(2+) and Tb(3+)) provides strong evidence for the involvement of carboxyl carbonyl functions in the binding of all three metal ions, which is not unexpected. The spectra also reveal, however, a very pronounced difference in the 4000-2000 cm(-1) IR spectral region between the Al(3+) spectrum and the Ca(2+) and Tb(3+) spectra. The -OH stretch spectral region in the Al(3+) spectrum has a major component shifted to higher energy (compared to fulvic acid alone or to fulvic acid in the presence of Ca(2+) or Tb(3+)). Even more striking is the emergence of a pronounced IR band at 2407 cm(-1), which is present only in the Al(3+) spectrum. The results of fluorescence and IR experiments with the model compounds salicylic acid and phthalic acid further confirm that both salicylic acid-like sites and phthalic acid-like sites are likely complexation sites for Al(3+) in fulvic acid and are major contributors to the observed spectroscopic changes associated with Al(3+) ion complexation. From a comparison of both the fluorescence and IR spectral results for all three class A metals, differing most strongly in the value of their ionic index, it seems clear that major sources of the deviation in spectral properties between Al(3+) and Ca(2+)/Tb(3+) is the unusually high value of its charge density and relatively low propensity for involvement in covalent bonding interactions (very high ionic index and relatively low covalent index in the Nieboer and Richardson classification of environmental metals), as well as affinity for certain functional groups. PMID:11709217
Elkins, K M; Nelson, D J
75 FR 33824 - Barium Chloride From China
Federal Register 2010, 2011, 2012, 2013
...No. 731-TA-149 (Third Review)] Barium Chloride From China Determination On the...revocation of the antidumping duty order on barium chloride from China would be likely to...Publication 4157 (June 2010), entitled Barium Chloride from China: Investigation...
75 FR 19657 - Barium Chloride From China
...No. 731-TA-149 (Third Review)] Barium Chloride From China AGENCY: United States...concerning the antidumping duty order on barium chloride from China...revocation of the antidumping duty order on barium chloride from China would be likely...
Properties of Semiconductive Barium Titanates
The resistivity of barium titanate which is usually of the order of 109ś1012 ohm-cm, may be remarkably reduced with suitable control in valency. The valency-controlled barium titanate, whose resistivity is of the order of 10ś104 ohm-cm at room temperature, shows anomalous positive character in the temperature dependency of the resistivity. For example, the resistivity of barium titanate containing 0.1 mol.
Osamu Saburi
Optimized photorefractive barium titanate
The goal of this research program was to investigate new and modified crystal-growth techniques that would lead to high-optical-quality BaTiO3 with increased photorefractive speed and sensitivity. The research program consisted of four parts: (1) feed material purification; (2) crystal growth by the top-seeded-solution technique as well as by a barium borate flux technique; (3) new furnace design studies; and (4)
Cardinal Warde; Hans P. Jenssen
An Improved Qualitative Analysis Procedure for Aluminum Subgroup Cations.
ERIC Educational Resources Information Center
Describes a procedure for the qualitative analysis of aluminum subgroup cations designed to avoid failure to obtain lead or barium chromate precipitates or failure to report aluminum hydroxide when present (due to staining). Provides a flow chart and step-by-step explanation for the new procedure, indicating significantly improved student results.ģ
Kistner, C. R.; Robinson, Patricia J.
Lack of effect of drinking water barium on cardiovascular risk factors
Higher cardiovascular mortality has been associated in a single epidemiological study with higher levels of barium in drinking water. The purpose of this study was to determine whether drinking water barium at levels found in some U.S. communities-alters the known risk factors for cardiovascular disease. Eleven healthy men completed a 10-week dose-response protocol in which diet was controlled. Other aspects of the subjects' lifestyles known to affect cardiac risk factors were controlled, and the barium content (as barium chloride) of the drinking water was varied from 0, to 5 ppm, to 10 ppm. Multiple blood and urine samples, morning and evening blood pressure measurements, and 48-hr electrocardiographic monitoring were performed at each dose of barium. There were no changes in morning or evening systolic or diastolic blood pressures, plasma cholesterol or lipoprotein or apolipoprotein levels, serum potassium or glucose levels, or urine catecholamine levels. There were no arrythmias related to barium exposure detected on continuous electrocardiographic monitoring. A trend was seen toward increased total serum calcium levels with exposure to barium, which was of borderline statistical significance and of doubtful clinical significance. In summary, drinking water barium at levels of 5 and 10 ppm did not appear to affect any of the known modifiable cardiovascular risk factors.
Wones, R.G.; Stadler, B.L.; Frohman, L.A. (Univ. of Cincinnati College of Medicine, OH (USA))
Plagioclase-rich chondrules in the reduced CV chondrites: Evidence for complex formation history and genetic links between calcium-aluminum-rich inclusions and ferromagnesian chondrules
Plagioclase-rich chondrules (PRCs) in the reduced CV chondrites Efremovka, Leoville, Vigarano and Grosvenor Mountains (GRO) 94329 consist of magnesian low-Ca pyroxene, Al-Ti-Cr-rich pigeonite and augite, forsterite, anorthitic plagioclase, FeNi-metal-sulfide nodules, and crystalline mesostasis composed of silica, anorthitic plagioclase and Al-Ti-Cr-rich augite. The silica grains in the mesostases of the CV PRCs are typically replaced by hedenbergitic pyroxenes, whereas anorthitic plagioclase is replaced by feldspathoids (nepheline and minor sodalite). Some of the PRCs contain regions that are texturally and mineralogically similar to type I chondrules and consist of forsterite, low-Ca pyroxene and abundant FeNi-metal nodules. Several PRCs are surrounded by igneous rims or form independent compound objects. Twelve PRCs contain relic calcium-aluminum-rich inclusions (CAIs) composed of anorthite, spinel, high-Ca pyroxene, ?forsterite, and ?Al-rich low-Ca pyroxene. Anorthite of these CAIs is generally more heavily replaced by feldspathoids than anorthitic plagioclase of the host chondrules. This suggests that either the alteration predated formation of the PRCs or that anorthite of the relic CAIs was more susceptible to the alteration than anorthitic plagioclase of the host chondrules. These observations and the presence of igneous rims around PRCs and independent compound PRCs suggest that the CV PRCs may have had a complex, multistage formation history compared to a more simple formation history of the CR PRCs. Relatively high abundances of moderately-volatile elements such as Cr, Mn and Si in the PRCs suggests that these chondrules could not have been produced by volatilization of ferromagnesian chondrule precursors or by melting of refractory materials only. We infer instead that PRCs in carbonaceous chondrites formed by melting of the reduced chondrule precursors (magnesian olivine and pyroxene, FeNi-metal) mixed with refractory materials (relic CAIs) composed of anorthite, spinel, high-Ca pyroxene, and forsterite. The mineralogical, chemical and textural similarities of the PRCs in several carbonaceous chondrite groups (CV, CO, CH, CR) and common presence of relic CAIs in these chondrules suggest that PRCs may have formed in the region(s) intermediate between the regions where CAIs and ferromagnesian chondrules originated.
Krot, A. N.; Hutcheon, I. D.; Keil, K.
Barium peritonitis in small animals.
Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions. PMID:24430662
Ko, Jae Jin; Mann, F A Tony
Barium Peritonitis in Small Animals
ABSTRACT Barium peritonitis is extremely rare, but is difficult to treat and may be life-threatening. Barium suspension leakage from the gastrointestinal tract into the abdominal cavity has a time-dependent and synergistically deleterious effect in patients who have generalized bacterial peritonitis. The severity of barium peritonitis is dependent on the quantity of barium in the abdominal cavity. Barium sulfate leakage results in hypovolemia and hypoproteinemia by worsening the exudation of extracellular fluid and albumin. Abdominal fluid analysis is a useful and efficient method to diagnose barium peritonitis. Serial radiographs may not be a reliable or timely diagnostic technique. Initial aggressive fluid resuscitation and empirical broad-spectrum antibiotic treatment should be instituted promptly, followed quickly by celiotomy. During exploratory surgical intervention, copious irrigation and direct wiping with gauze are employed to remove as much barium as possible. Omentectomy should be considered when needed to expedite barium removal. Despite aggressive medical and surgical treatments, postoperative prognosis is guarded to poor due to complications, such as acute vascular shock, sepsis, diffuse peritonitis, hypoproteninemia, electrolyte imbalance, cardiac arrest, small bowel obstruction related to progression of granulomas and adhesions in the abdominal cavity. Therefore, intensive postoperative monitoring and prompt intervention are necessary to maximize chances for a positive outcome. For those that do survive, small bowel obstruction is a potential consequence due to progression of abdominal adhesions.
KO, Jae Jin; MANN, F. A. (Tony)
Barium uranyl diphosphonates
Three Ba2+/UO22+ methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200 ░C. These compounds, Ba[UO2[CH2(PO3)2]Ę1.4H2O (Ba-1), Ba3[(UO2)4(CH2(PO3)2)2F6]Ę6H2O (Ba-2), and Ba2[(UO2)2(CH2(PO3)2)F4]Ę5.75H2O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO5F2 pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO2[CH2(PO3)2]2- sheets. The interlayer space of the structures is occupied by Ba2+, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance.
Nelson, Anna-Gay D.; Alekseev, Evgeny V.; Ewing, Rodney C.; Albrecht-Schmitt, Thomas E.
Bidirectional regulation of neuronal potassium currents by the G-protein activator aluminum fluoride as a function of intracellular calcium concentration
Hydrolysis-resistant activation of G-proteins by extracellular perfusion of fluoride ions was examined in Type B cells isolated from the cerebral ganglion of the marine mollusc Hermissenda. Under single-electrode voltage-clamp, modulation by aluminum fluoride ions of several classes of outward K+ currents as well as an inward Ca2+ current was observed. Following injection of the Ca2+ chelator EGTA, aluminum fluoride ions
L. D. Matzel; R. F. Rogers; A. C. Talk
Biogenic cements from rice hull ash doped with aluminum and iron.
This work describes the use of rice hull as starting material for the synthesis of cements doped with iron and aluminum. Rice hull contains about 10-20% of silica along with organic material. In many countries rice hull represents an environmental problem since this material is merely burned at rice fields, rendering suspended silica particles in the air. Dicalcium silicate (beta-Ca(2)SiO(4)) is the second most important component of Portland cement and presents many environmental advantages over commercial cement. It can be prepared at lower temperatures saving energy and raw-materials. In this work we describe the synthesis beta-Ca(2)SiO(4) using silica derived from rice hull ash. Silica was obtained from heating rice hull at 600 degrees C. Starting materials (silica, calcium oxide, barium chloride, iron or aluminum oxide) were weighed in stoichiometric proportions and aqueous dispersions having water:solid ratio of approximately 20:1 were prepared and treated in an ultrasonic bath for 60 min. After this, an intermediate silicate and the excess of calcium hydroxide were obtained. Finally solids were dried, grounded and heated up to 800 degrees C. It was observed that beta-Ca(2)SiO(4) was obtained when dopant concentration was limited to 1%. PMID:18722641
Mahfouz, M; Miranda, M S; Oliveira, M B R; Cassiola, F; Rodrigues, F A
Removal of barium and radium from groundwater. Environmental research brief
A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium removal processes were also characterized, and processes suitable for treatment of ion-exchange brines were evaluated. The report discusses two ion-exchange processes that can be used for barium and radium removal accompanied by either partial or no hardness removal. The calcium-form, strong-acid ion-exchange resin can be used for barium and radium removal without significant change in hardness or the concentration of other salts. This resin can be regenerated with CaC1/sub 2/ brine. The radium-selective complexer (RSC) will remove radium without altering hardness or other salt concentration. The capacity of this resin for waters with low total dissolved solids (TDS) (<1000 to 2000 mg/L TDS) is in excess of 30,000 pCi/dry g; however, if the TDS is increased to about 40,000 mg/L, the capacity drops to 200 to 300 pCi/dry g. Thus using this resin to remove radium from spent brine does not appear feasible.
Snoeyink, V.L.; Chambers, C.C.; Schmidt, C.K.; Manner, R.F.; Myers, A.G.
Aluminum hemotoxicity mechanisms.
Both aluminum and its salts are commonly used by people. Aluminum salts are components of drugs. Such a widespread use of aluminum was enhanced by the belief that it is not toxic and is quickly excreted from the body with urine. It turned out, however, that this element has a negative impact on human health. Post-dialysis encephalopathy of patients with kidney malfunctioning was ascribed to the presence of aluminum in dialysis fluid. Aluminum cumulating in brain tissue is claimed to play a role in developing neurological disorders. This element affects bones as well as it causes disturbances in phosphorus and calcium levels, which is demonstrated chiefly by osteomalatia. Aluminium accumulation in the liver leads to cholestasis. This element causes numerous changes in peripheral blood and hemogenic system. It also causes normo- or microcytary anemia as it disturbs maturing of erythroblastic series cells and heme biosynthesis; it decreases osmotic resistance of red blood cells. Aluminum inhibits defensive mechanisms connected with white blood cells and macrophages. A number of processes, namely aluminum's hemolytic activity, blood cells' shorter lifetime or disturbed erythropoiesis process, are responsible for hematological changes. PMID:16146022
Osi?ska, Elzbieta; Kanoniuk, Dorota; Kusiak, Anna
Discovery of the barium isotopes
Thirty-eight barium isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
Shore, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Schuh, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M., E-mail: email@example.com [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
Determination of barium in sulphide ores, concentrates and other geological samples by flame atomic-absorption spectrometry.
A rapid, precise and selective analytical method has been developed for estimation of barium in geological samples by flame atomic-absorption spectrometry. The method consists of precipitation of barium sulphate with ammonium sulphate, followed by dissolution of the sulphates in EDTA at pH 10. The barium in this solution is measured by AAS with a nitrous oxide-acetylene flame. Appreciable amounts of lead, calcium and strontium can be tolerated in the method, which has been applied for estimation of barium in sulphide ores and concentrates of lead, zinc and copper, and is feasible for estimation of barium from 20.0 ppm to the per cent level in such geological samples. PMID:18963404
Sharma, K D
Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum
Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as ōbathö in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.
Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi
21 CFR 82.3 - Definitions.
...precipitated aluminum hydroxide. (h) The term blanc...co-precipitated aluminum hydroxide and barium sulfate. (j) The term mixed oxides means the sum of the quantities of aluminum, iron, calcium, and magnesium...aluminum trioxide, ferric oxide, calcium oxide,...
Formation of ettringite, Ca 6Al 2(SO 4) 3(OH) 12Ę26H 2O, AFt, and monosulfate, Ca 4Al 2O 6(SO 4)Ę14H 2O, AFm-14, in hydrothermal hydration of Portland cement and of calcium aluminum oxideŚcalcium sulfate dihydrate mixtures studied by in situ synchrotron X-ray powder diffraction
In the hydration of calcium aluminum oxide-gypsum mixtures, i.e., Ca 3Al 2O 6, Ca 12Al 14O 33 and CaSO 4Ę2H 2O, the reaction products can be ettringite, Ca 6Al 2(SO 4) 3(OH) 12Ę26H 2O, monosulfate, Ca 4Al 2O 6(SO 4)Ę14H 2O, or the calcium aluminum oxide hydrate, Ca 4Al 2O 7Ę19H 2O. Ettringite is formed if sufficient CaSO 4Ę2H 2O is present in the mixture. Ettringite is converted to monosulfate when all CaSO 4Ę2H 2O is consumed in the synthesis of ettringite. The reactions were investigated in the temperature range 25-170░C using in situ synchrotron X-ray powder diffraction. This technique allows the study of very fast chemical reactions that are observed here under hydrothermal conditions. A new experimental approach was developed to perform in situ mixing of the reactants during X-ray data collection.
Christensen, Axel N°rlund; Jensen, Torben R.; Hanson, Jonathan C.
Uranium Sequestration by Aluminum Phosphate Minerals in Unsaturated Soils
A mineralogical and geochemical study of soils developed from the unmined Coles Hill uranium deposit (Virginia) was undertaken to determine how phosphorous influences the speciation of uranium in an oxidizing soil/saprolite system typical of the eastern United States. This paper presents mineralogical and geochemical results that identify and quantify the processes by which uranium has been sequestered in these soils. It was found that uranium is not leached from the saturated soil zone (saprolites) overlying the deposit due to the formation of a sparingly soluble uranyl phosphate mineral of the meta-autunite group. The concentration of uranium in the saprolites is approximately 1000 mg uranium per kg of saprolite. It was also found that a significant amount of uranium was retained in the unsaturated soil zone overlying uranium-rich saprolites. The uranium concentration in the unsaturated soils is approximately 200 mg uranium per kg of soil (20 times higher than uranium concentrations in similar soils adjacent to the deposit). Mineralogical evidence indicates that uranium in this zone is sequestered by a barium-strontium-calcium aluminum phosphate mineral of the crandallite group (gorceixite). This mineral is intimately inter-grown with iron and manganese oxides that also contain uranium. The amount of uranium associated with both the aluminum phosphates (as much as 1.4 weight percent) has been measured by electron microprobe micro-analyses and the geochemical conditions under which these minerals formed has been studied using thermodynamic reaction path modeling. The geochemical data and modeling results suggest the meta-autunite group minerals present in the saprolites overlying the deposit are unstable in the unsaturated zone soils overlying the deposit due to a decrease in soil pH (down to a pH of 4.5) at depths less than 5 meters below the surface. Mineralogical observations suggest that, once exposed to the unsaturated environment, the meta-autunite group minerals react to form U(VI)- bearing aluminum phosphates. (author)
Jerden, James L. Jr. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439 (United States)
Analysis of Barium Clouds. Volume I.
Several aspects of the analysis of barium ion clouds are presented including ion cloud modeling, comparison of radar and optical data, and correlation of data with theory. A quantitative model has been developed from which various properties of barium ion...
B. Kivel L. F. Cianciolo L. M. Linson S. Powers
Solid-state barium-vapor detector
The need for electrical switching devices for use in high-temperature radioactive environments in space nuclear power systems has led to the development of the cesium-barium tacitron. Effective evaluation of electrically insulating joints for the barium-cesium tacitron requires a method for the in situ detection of barium vapor which may leak through the joint. A solid-state barium-vapor detector has been developed
Jeffrey W. Fergus; S. Hui
Aluminum Hydroxide
Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...
Synthesis and characterization of highly-ordered barium-strontium titanate nanotube arrays fabricated by solŚgel method
Highly uniformed barium-strontium titanate nanotube arrays were fabricated using a porous anodic aluminum oxide template from a barium-strontium titanate solŚgel solution. Electron microscope results showed that nanotubes with uniform length and diameter were obtained. The diameters and lengths of these nanotubes were dependent on the pore diameter and the thickness of the applied anodic aluminum oxide template. High resolution transmission electron microscopy and the selected-area electron diffraction pattern investigations demonstrated the perovskite structure and the polycrystalline of the fabricated barium-strontium titanate nanotubes. The characterization of the electrical and dielectric properties had also been made. Compared to thin film material, the intrinsic leakage current density is almost the same. Besides, at 30 ?C, the dielectric constant and dielectric loss of the fabricated nanotube is 80 and 0.027 at 1 MHz respectively.
Chen, Yu; Chen, Wei; Guo, Feng; Li, Mei-Ya; Liu, Wei; Zhao, Xing-Zhong
Determination of barium and strontium peroxides (active oxygen) in igniters in small-arms tracer ammunition.
A method is proposed for the determination of barium and strontium peroxides (active oxygen) in igniters in small-arms tracer ammunition. The sample is treated with dilute hydrochloric acid (1 + 9) which dissolves the magnesium powder almost instantaneously and then dissolves the barium or strontium peroxides within 10-30 min. The solution is then filtered to remove the organic substances (calcium resinate, "Parlon". Toluidine Red toner, and zinc stearate) and the peroxide is determined by means of the colour of the titanium-peroxide complex. It is shown that igniter mixes and igniters used in small-arms tracer ammunition deteriorate on storage. PMID:18961958
Norwitz, G; Galan, M
New solutions to an old problem: calcium sulfate deposition in the Permian Basin
Scale deposits in producing oil wells and equipment are a serious problem in many areas of the country. There are 3 principal types of scale that are particularly troublesome--calcium carbonate, calcium sulfate, and barium sulfate. Calcium sulfate scale is predominant in many areas, particularly in the Permian basin of West Texas. Some operators in the West Texas area report growth
Computer modelling of barium titanate
Barium titanate is an important material for both scientific and industrial applications. Much of the interest centres around its ferroelectric properties, since it is structurally the most simple in this class. In addition rare-earth doped ceramics are found to exhibit a very steep positive temperature coefficient of resistance (PTCR) above the Curie point. The theory of this PTCR effect is
G. V. Lewis; C. R. A. Catlow
Recent Developments in Barium Borate,
The nonlinear optical properties of Beta-BaB2O4(beta barium borate) are demonstrated in the generation of second through fifth harmonics of 1.06-micrometer neodymium laser radiation, and in optical parametric oscillation pumped by 532-nm radiation. Beta-B...
C. Chen Y. X. Fan R. C. Eckardt R. L. Byer
Calcium Acetate versus Calcium Carbonate as Phosphate Binders in Hemodialysis Patients
We conducted a randomized unblinded parallel clinical trial to compare the effectiveness, side effects and tolerance between calcium acetate (CA) and calcium carbonate (CC) in 80 stable chronic hemodialysis patients selected on the basis of their acceptable control of serum phosphorus (P) levels with aluminum hydroxide (AH). All patients were dialyzed against the same calcium dialyzate (1.62 mmol\\/l). The serum
F. Caravaca; I. Santos; J. J. Cubero; J. F. Esparrago; M. Arrobas; J. L. Pizarro; R. Robles; E. Sanchez-Casado
Fictive Temperature Effects on Non-Bridging Oxygen and Five-Coordinated Aluminum in Calcium Aluminosilicate Glasses: High Resolution 17O and 27Al NMR Spectroscopy
Despite the importance of aluminosilicate melts to both the geological and technological communities, the configurational changes with temperature remain poorly understood. However, configurational changes with temperature play an important role in changes in thermodynamic and transport properties, as well as offering insight into potential relationships between minor structural species such as non-bridging oxygen (NBO) and VAl (AlO5). A previous study indicated changes in VAl with temperature in multiple calcium aluminosilicate glasses, while changes in NBO were only observed on the metaluminous join (Stebbins et al., 2008). Here we have expanded this to look at two series of calcium aluminosilicate glasses crossing the metaluminous join on a constant SiO2 isopleth at multiple fictive temperatures. In all cases, the amount of VAl present increased with increasing fictive temperature, although the magnitude of the increase varied with larger increases in the peraluminous regions versus the peralkaline earth regions. Increases in NBO are also observed with increasing fictive temperature in the metaluminous and peraluminous regions. Comparison of these results with those from the earlier study suggests that the changes may be most pronounced in the regions where the deviation from conventional wisdom are at their peak (e.g., in the metaluminous region of alkaline earth aluminosilicate glasses). Comparison of the increases in VAl and NBO with increasing fictive temperature support previous suggestions (Thompson and Stebbins 2011; Thompson and Stebbins 2012) that multiple mechanisms must exist to produce excess VAl and NBO and that at least some of these mechanisms must be decoupled from each other.
Thompson, L. M.; Stebbins, J. F.
75 FR 20625 - Barium Chloride From China
...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-149 (Third Review)] Barium Chloride From China AGENCY: United States International Trade Commission. ACTION: Revised schedule for the subject...
Aluminum Boats
Test the buoyancy of an aluminum foil boat and an aluminum foil ball. Why does the same material in different shapes sink or float? This activity explores the fact that the amount of water pushed aside by an object equals the force of water pushing upward on the object.
Center, Reuben H.
Fabrication of aluminum nitride crucibles for molten salt and plutonium compatibility studies
The overall objective of this research was to fabricate a calcium oxide sinter-aided aluminum nitride crucible and determine the compatibility of this crucible with molten chloride salts and plutonium metal in the DOR process. Calcium oxide sinter-aided aluminum nitride was preferred over yttrium oxide sinter-aided aluminum nitride because of (1) the presence of calcium chloride, calcium oxide, and calcium metal in the molten salts utilized in the DOR process, and (2) the higher volatility of the secondary phases formed compared with phases resulting from the addition of yttrium oxide during the aluminum nitride sintering process. The calcium oxide system may yield a higher purity crystal structure with fewer secondary phases present than in the yttrium oxide system. The secondary phases that are present in the grain boundaries may be unreactive with the calcium chloride salt due to the presence of calcium in the secondary phases.
Phillips, J.A.
Heavy ion Rutherford backscattering spectrometry (HIRBS) study of barium diffusion in borosilicate glass
Diffusion of barium in borosilicate glasses containing sodium and calcium has been studied using heavy ion Rutherford backscattering spectrometry (HIRBS) using 30MeV 19F beam. A thin layer (25?g\\/cm2) of BaCl2 was vacuum evaporated on the polished surface of the glass samples which were then annealed at different temperatures (573¢723K) and subsequently subjected to HIRBS measurements. It was observed that introduction
Sumit Kumar; R. K. Mishra; B. S. Tomar; A. K. Tyagi; C. P. Kaushik; Kanwar Raj; V. K. Manchanda
Diffusion of barium in borosilicate glasses containing sodium and calcium has been studied using heavy ion Rutherford backscattering spectrometry (HIRBS) using 30 MeV 19F beam. A thin layer (25 mug\\/cm2) of BaCl2 was vacuum evaporated on the polished surface of the glass samples which were then annealed at different temperatures (573 723 K) and subsequently subjected to HIRBS measurements. It
Calcite/barium fluoride ultraviolet polarizing prism
A calcite/barium fluoride polarizing prism gives improved ultraviolet transmittance compared with a calcite/calcite ultraviolet polarizing prism. Beam spatial distortion is transmitted because of variations in absorption (and path length) in the calcite half of the calcite/barium fluoride prism.
Wu, Fuquan; Li, Guohua; Huang, Jiayin; Yu, Dehong
Barium granuloma of the transverse colon.
A case of barium sulphate granuloma of the transverse colon following gunshot wounds to the abdomen has been described. Scanning electron microscopy with electron probe microanalysis was used to confirm the presence of barium sulphate and the absence of lead or other elements related to the gunshot wounds. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4
McKee, P. H.; Cameron, C. H.
A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium remo...
A comparison of the calcium-free phosphate binder sevelamer hydrochloride with calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients
Current phosphate binders used in hemodialysis patients include calcium-based binders that result in frequent hypercalcemia and aluminum-based binders that result in total body aluminum accumulation over time. This investigation describes the use of a calcium- and aluminum-free phosphate-binding polymer in hemodialysis patients and compares it with a standard calcium-based phosphate binder. An open-label, randomized, crossover study was performed to evaluate
Anthony J. Bleyer; Steven K. Burke; Maureen Dillon; Bruce Garrett; K. Shashi Kant; David Lynch; S. Noor Rahman; Patricia Schoenfeld; Isaac Teitelbaum; Steven Zeig; Eduardo Slatopolsky
Fluorescence Resonance Energy Transfer-Sensitized Emission of Yellow Cameleon 3.60 Reveals Root Zone-Specific Calcium Signatures in Arabidopsis in Response to Aluminum and Other Trivalent Cations1[W][OA
Fluorescence resonance energy transfer-sensitized emission of the yellow cameleon 3.60 was used to study the dynamics of cytoplasmic calcium ([Ca2+]cyt) in different zones of living Arabidopsis (Arabidopsis thaliana) roots. Transient elevations of [Ca2+]cyt were observed in response to glutamic acid (Glu), ATP, and aluminum (Al3+). Each chemical induced a [Ca2+]cyt signature that differed among the three treatments in regard to the onset, duration, and shape of the response. Glu and ATP triggered patterns of [Ca2+]cyt increases that were similar among the different root zones, whereas Al3+ evoked [Ca2+]cyt transients that had monophasic and biphasic shapes, most notably in the root transition zone. The Al3+-induced [Ca2+]cyt increases generally started in the maturation zone and propagated toward the cap, while the earliest [Ca2+]cyt response after Glu or ATP treatment occurred in an area that encompassed the meristem and elongation zone. The biphasic [Ca2+]cyt signature resulting from Al3+ treatment originated mostly from cortical cells located at 300 to 500 ? m from the root tip, which could be triggered in part through ligand-gated Glu receptors. Lanthanum and gadolinium, cations commonly used as Ca2+ channel blockers, elicited [Ca2+]cyt responses similar to those induced by Al3+. The trivalent ion-induced [Ca2+]cyt signatures in roots of an Al3+-resistant and an Al3+-sensitive mutant were similar to those of wild-type plants, indicating that the early [Ca2+]cyt changes we report here may not be tightly linked to Al3+ toxicity but rather to a general response to trivalent cations.
Rincon-Zachary, Magaly; Teaster, Neal D.; Sparks, J. Alan; Valster, Aline H.; Motes, Christy M.; Blancaflor, Elison B.
Aluminum Analysis.
Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)
Sumrall, William J.
Dielectric and pyroelectric properties of barium strontium calcium titanate ceramics
(Ba0.6Sr0.3Ca0.1)TiO3 powders were prepared by the sol-gel method using a solution of Ba, Sr and Ca acetate and Ti isopropoxide, and the specimens doped with MnCO3 (0.1 mol%) and Y2O3 (0.5 mol%) were fabricated by the cold isostatic press method. The urethane pot and zirconia ball were used in the mixing and grinding process, and the green pellets were sintered
Dae-Seok Kang; Myung-Soo Han; Sung-Gap Lee; Seong-Hae Song
New barium ferrite particles: Spherical shape
Pure and ZnTi-doped spherical barium ferrite particles were prepared using two different methods: semicoprecipitation and ultrasonic spray pyrolysis. The ultrasonic spray pyrolysis method was more effective in controlling particle shape. Particle size was in between 0.27 and 0.3 ?m. Coercivity and saturation magnetization were in the range of 1000 to 5000 Oe and 49 to 53 emu/g, respectively. Crystallization of amorphous Ba-Fe-O spherical precursors occurs at a lower temperature than Ba-Fe-Zn-Ti-O precursors. ?M measurement shows that magnetic interaction in spherical barium ferrite tape is weaker than hexagonal platelet barium ferrite.
Hong, Y. K.; Jung, H. S.
Distribution and source of barium in ground water at Cattaraugus Indian Reservation, southwestern New York
High concentrations of dissolved barium have been found in ground water from bedrock wells on the Seneca Nation of Indians Reservation on Cattaraugus Creek in southwestern New York. Concentrations in 1982 were as high as 23.0 milligrams per liter , the highest found reported from any natural ground-water system in the world. The highest concentrations are in a bedrock aquifer and in small lenses of saturated gravel between bedrock and the overlying till. The bedrock aquifer is partly confined by silt, clay, and till. The high barium concentrations are attributed to dissolution of the mineral barite (BaSO4), which is present in the bedrock and possibly in overlying silt, clay, or till. The dissolution of barite seems to be controlled by action of sulfate-reducing bacteria, which alter the BaSO4 equilibrium by removing sulfate ions and permitting additional barite to dissolve. Ground water from the surficial, unconsolidated deposits and surface water in streams contain little or no barium. Because barium is chemically similar to calcium, it probably could be removed by cation exchange or treatments similar to those used for water softening. (USGS)
Moore, R. B.; Staubitz, W. W.
Photorefractive and Photochromic Effects in Barium Titanate.
Nominally undoped p-type Barium titanate was grown that exhibits interesting intensity dependent photorefractive and photochromic properties. When its photochromism is activated the absorption increases at the activating wavelength and there is a concurre...
C. Warde H. P. Jenssen J. Y. Chang M. H. Garrett T. M. Pollak
Barium Isotopes in Single Presolar Grains
Barium isotopic compositions of single presolar grains were measured by laser ablation laser resonant ionization mass spectrometry and the implications of the data for stellar processes are discussed. Additional information is contained in the original extended abstract.
Pellin, M. J.; Davis, A. M.; Savina, M. R.; Kashiv, Y.; Clayton, R. N.; Lewis, R. S.; Amari, S.
Aluminum alloy
This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.
Blackburn, Linda B. (inventor); Starke, Edgar A., Jr. (inventor)
The effects of fumed silica and barite on the aluminum resistance of alumina castables
A study of the effects of microsilica and barium sulfate as additives in high-tabular alumina castables on cold and hot modulus of rupture, porosity, thermal shock, and corrosion resistance to aluminum attack is reported in this article. This investigation underlined the importance of the quality of fumed silica on the physical and mechanical properties of refractory castables, and also confirmed the importance of celsian formation during firing in the protection of refractory against aluminum attack.
Afshar, Saied; Gaubert, Christophe; Allaire, Claude
Aluminum Cans
In this data analysis activity students investigate data in connection with recyclable materials and develop plans to help the environment. Students collect data about aluminum can usage and graph that data in a line plot. The lesson includes student worksheet and extension suggestions.
Effect of dendroaspis natriuretic peptide (DNP) on L-type calcium channel current and its pathway
Dendroaspis natriuretic peptide (DNP), a newly-described natriuretic peptide, relaxes gastrointestinal smooth muscle. L-type calcium channel currents play an important role in regulating smooth muscle contraction. The effect of DNP on L-type calcium channel currents in gastrointestinal tract is still unclear. This study was designed to investigate the effect of DNP on barium current (IBa) through the L-type calcium channel in
Shu-Ying Zhang; Zheng-Xu Cai; Ping Li; Chun-Yu Cai; Cheng-Long Qu; Hui-Shu Guo
Cytotoxicity of synthetic barium hydroxyapatite.
Barium hydroxyapatite (Ba10(PO4)6(OH)2, Ba-HAp) was synthesized by a wet method using Ba(OH)2.8H2O and (NH4)2HPO4 as starting materials. The Ba-HAp obtained had a Ba/P atomic ratio of 1.76 and contained CO3 groups. The Ba-HAp was sintered at 1073 K for 12 hours. The sintered Ba-HAp had a three point bending strength of 29 MPa and Young's modulus of 27 GPa. Cytotoxicity of the sintered bodies and particles was tested using L-cells. The sintered Ba-HAp showed no cytotoxicity, and the cells were closely in contact with the surfaces of sintered Ba-HAp. Morphological observation of the cell around the Ba-HAp particles also showed no cytotoxicity. However, cell growth was inhibited by Ca adsorption on the Ba-HAp particles. These results suggested that the Ba-HAp had no cytotoxicity and can be applied as a bioactive X-ray opaque material. PMID:9138651
Kikuchi, M; Yamazaki, A; Akao, M; Aoki, H
Research on Thermionic Converters Using Barium and Cesium Vapor.
Investigations of thermionic converter operations were conducted utilizing a dual vapor system of barium and cesium. Barium and cesium vapors were introduced into two differently designed converters. The first converter developed an internal short circuit...
J. D. Long
Drinking Water Criteria Document for Barium (Final Draft), December 1987.
The Office of Drinking Water, Environmental Protection Agency has prepared a Drinking Water Criteria Document on barium. The Criteria Document is an extensive review of the following topics: Physical chemical properties of Barium; Toxicokinetics and human...
Drinking Water Criteria Document for Barium (Final Draft).
The Office of Drinking Water (ODW), U.S. Environmental Protection Agency has prepared a Drinking Water Criteria Document on barium. This Criteria Document is an extensive review of the following topics: Physical and chemical properties of barium; Toxicoki...
Placement of Radium/Barium Sludges in Tailings Areas.
Currently radium is removed from uranium mining and milling effluents by the addition of barium chloride to precipitate the radium as radium/barium sulphate. The precipitate is allowed to settle in sedimentation basins prior to discharge of the effluent. ...
K. L. Murphy G. E. Multamaki
Preparation and Properties of Barium Titanate Nanopowder\\/Epoxy Composites
This article is focused on the preparation of barium titanate nanopowder\\/epoxy composites and studying the effect of barium titanate nanopowder on improving mechanical and thermal characteristics of the epoxy polymer. Composites are prepared by dispersing barium titanate nanopowder in epoxy resin and, subsequently, cross-linking by using diamino diphenyl methane (DDM) curing agents. Synthesis of barium titanate nanopowder\\/epoxy composites is carried
J. Chandradass; Dong-sik Bae
Recycling of automotive aluminum
With the global warming of concern, the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits. In this work, recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling, use of aluminum alloys in automotive applications, automotive recycling process, and new technologies in
Jirang CUI; Hans J. ROVEN
Synthesis of barium titanate nanopowder using polymeric precursor method
Barium titanate powder was prepared by a polymerized complex method based on the Pechini type reaction route, where barium and titanium ions were polymerized in mixed solution of citric acid, ethylene glycol, to form a transparent resin, which was used as a precursor. Barium titanate powder was formed by heat treating the polymeric precursor in air at 500¢900░C. The thermal
V. Vinothini; Paramanand Singh; M. Balasubramanian
Calcium - urine
... from the kidneys, which causes calcium kidney stones Sarcoidosis Takiong too much calcium Too much production of ... metabolism. In: Goldman L, Ausiello D, eds. Cecil Medicine . 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap ...
Barium iodide single-crystal scintillator detectors
We find that the high-Z crystal Barium Iodide is readily growable by the Bridgman growth technique and is less prone to crack compared to Lanthanum Halides. We have grown Barium Iodide crystals: undoped, doped with Ce{sup 3+}, and doped with Eu{sup 2+}. Radioluminescence spectra and time-resolved decay were measured. BaI{sub 2}(Eu) exhibits luminescence from both Eu{sup 2+} at 420 nm ({approx}450 ns decay), and a broad band at 550 nm ({approx}3 {micro}s decay) that we assign to a trapped exciton. The 550 nm luminescence decreases relative to the Eu{sup 2+} luminescence when the Barium Iodide is zone refined prior to crystal growth. We also describe the performance of BaI{sub 2}(Eu) crystals in experimental scintillator detectors.
Cherepy, N
Improved spectrophotometric analysis of barium styphnate
A spectrophotometric procedure to determine the purity of barium styphnate monohydrate based upon the absorbance of the styphnate ion at 326 and 413.3 nm has been developed. The purity is determined by comparing the absorbance of the styphnate ion in barium styphnate and in styphnic acid. Our investigation has shown that the molar absorptivity and lambda maxima of the styphnate ion are quite pH dependent; therefore, the pH is buffered to 6.8 to 7.0 with ammonium acetate. Under these conditions the molar absorptivity is 1.6 x 10/sup 4/ L/mol-cm. Analyses following the procedure in the Navy specification WS13444A using water were found to give low molar absorptivities (1.3 x 10/sup 4/ L/mol-cm) for the styphnic acid calibration resulting in erroneous values for barium styphnate purity.
Brown, N E; Blasi, J A
Biocompatibility Testing of Aluminium-Calcium-Phosphorus Oxide (ALCAP) Ceramics.
Ceramic implants composed of aluminum oxide, calcium oxide, and phosphorus pentoxide have given excellent results in terms of compatibility and gradual replacement of the ceramic material with endogenous bone. Experiments conducted so far suggest that bio...
The solubility and thermodynamic properties of ettringite, its chromium analogs, and calcium aluminum monochromate (3CaO*Al(2)O(3)*CaCrO(4)*nH(2)O)
Ettringite (Ca6[(Al(OH)6)]2(SO 4)3Ę26H2O) is a naturally-occurring mineral and an important product of the hydration of Portland cements and fly ash. Substitution of Cr(III) for Al(III) and CrO4 for SO4 in the ettringite structure has been demonstrated and may be important with respect to the fate and transport of chromium in alkaline environments. Ettringite and its chromium analogs were synthesized and their solubilities measured via dissolution and precipitation experiments over a range of temperatures between 5 and 75░C and pH values between 10 and 13. The log KSP,298 for the reaction Ca6AlOH 62SO 43?26H2O =6Ca2++2AlOH -4 +3SO 2-4 +4OH-+26H2O is -44.9 +/- 0.3. The enthalpy and entropy of reaction are 205 +/- 12 kJ mol-1 and 170 +/- 38 J mol -1 K-1, respectively. The free energy, enthalpy, and entropy of formation are -15211 +/- 20, -17550 +/- 16 kJ mol-1, and 1870 +/- 59 J mol -1 K-1, respectively, based on the reaction parameters and partial molar properties for the dissolved ions. The log KSP, free energy, and enthalpy of reaction for the Cr(III) ettringite analog, bentorite, are KSP,298 = -52.9 +/- 0.8, DeltaG░r,298 = 302 +/- 10 and DeltaH░r = 320 +/- 76 kJ mol-1 based on an equivalent dissolution reaction. Dissolution of bentorite is incongruent due to precipitation of another phase tentatively identified as Ca2Cr2O5Ę8H 2O. The log KSP, free energy and enthalpy of reaction for the dissolution of Ca6[(Al(OH)6)]2(CrO4 )3Ę26H2O are KSP,298 = -41.46 +/- 0.30, DeltaG░r,298 = 236.6 +/- 3.9 and DeltaH░r = 77.5 +/- 9.6 kJ mol-1. The log KSP varies with pH unless a CaCrO4(aq) complex is included in the speciation model. A log formation constant of K = 2.77 +/- 0.16 was obtained for the reaction Ca2+ + CrO42- = CaCrO 4(aq) by minimizing the variance of the IAP for Ca6[(Al(OH) 6)]2(CrO4)3Ę26H2O. A secondary precipitate, identified as calcium aluminum monochromate or (3CaOĘAl2O3ĘCaCrO4ĘnH 2O) was present in Cr(VI)-analog experimental residues. The log K SP for the reaction 3CaO?Al2O3?CaCrO4 ?15H2O=4Ca2++2AlOH -4 + CrO42-+4OH-+ 9H2O is -30.38 +/- 0.28. Ca6[(Al(OH)6)]2(SO4(1-x) , CrO4x)3Ę26H2O solids were synthesized and solid-solution aqueous-solution interactions were investigated through dissolution pathway studies. Although thermodynamic equilibrium was not achieved, dissolution pathways approximated stoichiometric saturation curves when plotted on Lippman diagrams.
Perkins, Robert Benjamin
Kinetic analysis of barium currents in chick cochlear hair cells.
Inward barium current (IBa) through voltage-gated calcium channels was recorded from chick cochlear hair cells using the whole-cell clamp technique. IBa was sensitive to dihydropyridines and insensitive to the peptide toxins omega-agatoxin IVa, omega-conotoxin GVIa, and omega-conotoxin MVIIC. Changing the holding potential over a -40 to -80 mV range had no effect on the time course or magnitude of IBa nor did it reveal any inactivating inward currents. The activation of IBa was modeled with Hodgkin-Huxley m2 kinetics. The time constant of activation, tau m, was 550 microseconds at -30 mV and gradually decreased to 100 microseconds at +50 mV. A Boltzmann fit to the activation curve, m infinity, yielded a half activation voltage of -15 mV and a steepness factor of 7.8 mV. Opening and closing rate constants, alpha m and beta m, were calculated from tau m and m infinity, then fit with modified exponential functions. The H-H model derived by evaluating the exponential functions for alpha m and beta m not only provided an excellent fit to the time course of IBa activation, but was predictive of the time course and magnitude of the IBa tail current. No differences in kinetics or voltage dependence of activation of IBa were found between tall and short hair cells. We conclude that both tall and short hair cells of the chick cochlea predominantly, if not exclusively, express noninactivating L-type calcium channels. These channels are therefore responsible for processes requiring voltage-dependent calcium entry through the basolateral cell membrane, such as transmitter release and activation of Ca(2+)-dependent K+ channels.
Zidanic, M; Fuchs, P A
Brazing dissimilar aluminum alloys
Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.
Dalalian, H.
Organic-template-directed nucleation of strontium fluoride and barium fluoride: Epitaxy and strain
In situ synchrotron x-ray diffraction studies show that barium and strontium fluoride grow preferentially oriented at a fatty-acid monolayer template, with the unit cell spacings initially contracted by ś1.6% (SrF2) to ś4% (BaF2). In addition to this macroscopic strain, peak width analysis shows the presence of local strain that relaxes as the crystals grow. In contrast, the diffraction pattern from calcium carbonate grown at the same template shows no preferred crystallographic orientation.
Kmetko, Jan; Yu, Chungjong; Evmenenko, Guennadi; Kewalramani, Sumit; Dutta, Pulak
Spectroscopic (multi-energy) CT distinguishes iodine and barium contrast material in MICE
ObjectiveĀĀSpectral CT differs from dual-energy CT by using a conventional X-ray tube and a photon-counting detector. We wished to produce\\u000a 3D spectroscopic images of mice that distinguished calcium, iodine and barium.\\u000a \\u000a \\u000a \\u000a \\u000a MethodsĀĀWe developed a desktop spectral CT, dubbed MARS, based around the Medipix2 photon-counting energy-discriminating detector.\\u000a The single conventional X-ray tube operated at constant voltage (75ĀkVp) and constant current (150ĀĄA).
N. G. Anderson; A. P. Butler; N. J. A. Scott; N. J. Cook; J. S. Butzer; N. Schleich; M. Firsching; R. Grasset; N. de Ruiter; M. Campbell; P. H. Butler
Production and isolation of endohedral strontium- and barium-based mono-metallofullerenes: Sr/Ba@C 82 and Sr/Ba@C 84
We report the first isolation of strontium- and barium-based metallofullerenes and their characterisation by UV-vis-NIR absorption spectroscopy. The absorption spectra of the present samples (Sr/Ba@C 82 and Sr/Ba@C 84) show some similarity to their calcium-based analogues and are very different from those of yttrium- and lanthanum-based metallofullerenes. Assuming the barium atom to be in the 2 + state, which has an ionic radius of 1.34┼, the Ba-containing species represent the largest ionic radii-containing metallofullerenes so far isolated.
John, T.; Dennis, S.; Shinohara, Hisanori
Synthesis of thin films of barium titanate and barium strontium titanate nanotubes on titanium substrates
In this study, well-ordered nanotubes of titania were fabricated by anodic oxidation of pure titanium foils in HF aqueous solution. Fe-SEM images indicate the average nanotubes diameter is ?100 nm with a thickness of about 200 nm. Nanotube arrays of barium titanate and barium strontium titanate were synthesized under hydrothermal condition at 200 ░C taking above-oxidized titania nanotubes as templates.
Jianling Zhao; Xiaohui Wang; Renzheng Chen; Longtu Li
Electric Tuning of Ferromagnetic Resonances in Hexagonal-Barium-Ferrite\\/Barium-Strontium-Titanate Heterostructures
This letter reports the first demonstration of a monolithic heterostructure with a large electric tuning of the ferromagnetic resonance (FMR) at millimeter-wave frequencies. The structure is composed of a barium-strontium-titanate (BST) film and two thin platinum electrodes, all grown on a barium ferrite slab with in-plane uniaxial anisotropy. The electric tuning of the FMR responses around 60 GHz was obtained
Young-Yeal Song; Jaydip Das; Pavol Krivosik; Hyung-Kee Seo; Mingzhong Wu
Microstructure and magnetism in barium strontium titanate (BSTO)¢barium hexaferrite (BaM) multilayers
High quality multilayers of barium ferrite (BaM) and barium strontium titanate (BSTO) were grown in optimized conditions on thermally oxidized Si(100) and Al2O3 substrates using magnetron sputtering. As-grown films were amorphous and different annealing procedures were explored to stabilize crystalline phases. BSTO and BaM phases were identified using X-ray diffraction and cross-sectional scanning electron micrographs showed sharp interfaces between BSTO
N. A. Frey; R. Heindl; S. Srinath; H. Srikanth; Nancy J Dudney
Sputtered barium titanate and barium strontium titanate films for capacitor applications
Thin barium titanate and barium strontium titanate films are being developed as dielectric film for use in dc-dc converters. Thin BaTiO3 (BT) and (BaSr)TiO3 (BST) film capacitor devices were fabricated using RF magnetron sputtering techniques. The typical dielectric constant of these film capacitors was in the range of 300 to 690. These film capacitors had dissipation factors between 0.2% to
Bang-Hung Tsao; Susan Heidger; Joseph A. Weimer
Aluminum extraction from aluminum industrial wastes
Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al2(SO4)3Ę12H2O) and ammonium aluminum alum {(NH4)2SO4AL2 (SO4)3Ę24H2O}. This was carried out in two processes. The first involves leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.
Amer, A. M.
Are There Any Stars Lacking Neutron-capture Elements? Evidence from Strontium and Barium
The cosmic dispersion in the abundances of the heavy elements strontium and barium in halo stars is well known. Strontium and barium are detected in most cool, metal-poor giants, but are these elements always detectable? To identify stars that could be considered probable candidates for lacking these elements, I examine the stellar abundance data available in the literature for 1148 field stars and 226 stars in dwarf galaxies, 776 of which have metallicities lower than [Fe/H] <-2.0. Strontium or barium have been detected in all field, globular cluster, and dwarf galaxy environments studied. All upper limits are consistent with the lowest detected ratios of [Sr/H] and [Ba/H]. The frequent appearance of these elements raises the intriguing prospect that at least one kind of neutron-capture reaction operates as often as the nucleosynthesis mechanisms that produce lighter elements, such as magnesium, calcium, or iron, although the yields of heavy elements may be more variable.
Roederer, Ian U.
Roederer, Ian U., E-mail: firstname.lastname@example.com [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
Low Temperature Thermal Expansion of Barium Ferrite.
The linear thermal expansion of polycrystalline barium ferrite, BaFe12O19, was measured from 76 to 293 K both parallel and perpendicular to the magnetization direction. An anisotropy of about 15-20% was observed. The results match well the available data ...
A. F. Clark W. M. Haynes V. A. Deason R. J. Trapani
The effects of additions of LaŌOŌ and LaŌOŌ--; 3TiOŌ on the electronic properties of barium titanate were investigated. ; It was found that small additions of the components markedly increase the ; lifetime of the material subjected to d-c fields of 50 v per mil at 200 l ; C. (auth);
J. B. MacChesney; P. K. Gallagher; F. V. DiMarcello
Beta-Barium Borate Optical Parametric Oscillator.
A Beta-Barium Borate Optical Parametric Oscillator (BBO OPO) has been constructed and shipped to the Army laboratory at White Sands. This OPO is a truly continuously tunable source with a very large spectral coverage. It is pumped at the third harmonic of...
C. L. Tang
Calcium-dependent inactivation of the dihydropyridine-sensitive calcium channels in GH3 cells
The inactivation of calcium channels in mammalian pituitary tumor cells (GH3) was studied with patch electrodes under voltage clamp in cell- free membrane patches and in dialyzed cells. The calcium current elicited by depolarization from a holding potential of -40 mV passed predominantly through one class of channels previously shown to be modulated by dihydropyridines and cAMP-dependent phosphorylation (Armstrong and Eckert, 1987). When exogenous calcium buffers were omitted from the pipette solution, the macroscopic calcium current through those channels inactivated with a half time of approximately 10 ms to a steady state level 40-75% smaller than the peak. Inactivation was also measured as the reduction in peak current during a test pulse that closely followed a prepulse. Inactivation was largely reduced or eliminated by (a) buffering free calcium in the pipette solution to less than 10(-8) M; (b) replacing extracellular calcium with barium; (c) increasing the prepulse voltage from +10 to +60 mV; or (d) increasing the intracellular concentration of cAMP, either 'directly' with dibutyryl-cAMP or indirectly by activating adenylate cyclase with forskolin or vasoactive intestinal peptide. Thus, inactivation of the dihydropyridine-sensitive calcium channels in GH3 cells only occurs when membrane depolarization leads to calcium ion entry and intracellular accumulation.
Hydrothermal Transformation of the Calcium Aluminum Oxide Hydrates CaAl2O4 . 10H2O and Ca2Al2O. 8H2O to Ca3Al2(OH)12 Investigated by In Situ Synchrotron X-ray Powder Diffraction
The hydrothermal transformation of calcium aluminate hydrates were investigated by in situ synchrotron X-ray powder diffraction in the temperature range 25 to 170 C. This technique allowed the study of the detailed reaction mechanism and identification of intermediate phases. The material CaAl{sub 2}O{sub 4}{center_dot}10H{sub 2}O converted to Ca{sub 3}Al{sub 2}(OH){sub 12} and amorphous aluminum hydroxide. Ca{sub 2}Al{sub 2}O{sub 5}{center_dot}8H{sub 2}O transformed via the intermediate phase Ca{sub 4}Al{sub 2}O{sub 7}{center_dot}13H{sub 2}O to Ca{sub 3}Al{sub 2}(OH){sub 12} and gibbsite, Al(OH){sub 3}. The phase Ca{sub 4}Al{sub 2}O{sub 7}{center_dot}19H{sub 2}O reacted via the same intermediate phase to Ca{sub 3}Al{sub 2}(OH){sub 12} and mainly amorphous aluminum hydroxide. The powder pattern of the intermediate phase is reported.
Jensen,T.; Christensen, A.; Hanson, J.
Hydrolysis of aluminum dross material to achieve zero hazardous waste.
A simple method with high efficiency for generating high pure hydrogen by hydrolysis in tap water of highly activated aluminum dross is established. Aluminum dross is activated by mechanically milling to particles of about 45 ?m. This leads to removal of surface layer of the aluminum particles and creation of a fresh chemically active metal surface. In contact with water the hydrolysis reaction takes place and hydrogen is released. In this process a Zero Waste concept is achieved because the other product of reaction is aluminum oxide hydroxide (AlOOH), which is nature-friendly and can be used to make high quality refractory or calcium aluminate cement. For comparison we also used pure aluminum powder and alkaline tap water solution (NaOH, KOH) at a ratio similar to that of aluminum dross content. The rates of hydrogen generated in hydrolysis reaction of pure aluminum and aluminum dross have been found to be similar. As a result of the experimental setup, a hydrogen generator was designed and assembled. Hydrogen volume generated by hydrolysis reaction was measured. The experimental results obtained reveal that aluminum dross could be economically recycled by hydrolysis process with achieving zero hazardous aluminum dross waste and hydrogen generation. PMID:22326245
David, E; Kopac, J
Long-term effects of calcium carbonate and 2.5 mEq\\/liter calcium dialysate on mineral metabolism
Long-term effects of calcium carbonate and 2.5 mEq\\/liter calcium dialysate on mineral metabolism. Many investigators have shown that calcium carbonate (CaCO3) is an effective phosphate binder which also prevents the potential disabling effects of aluminum (Al) accumulation. However, hypercalcemia may develop in a substantial numbers of patients. Thus, to control serum phosphate (PO4) and prevent hypercalcemia, we performed studies in
Eduardo Slatopolsky; Carol Weerts; Kathryn Norwood; Karla Giles; Patricia Fryer; Jane Finch; David Windus; James Delmez
Barium uptake and adsorption in diatoms
Using trace metal-defined culture conditions, we measured the cellular barium concentration in cultures of the diatom Thalassiosira weissflogii. In cultures with low Fe concentration, at a typical surface seawater Ba concentration of 35 to 40 nmol\\/L, the cellular Ba was 0.5 ?mol\\/mol P (?0.04 ?g\\/g dw), much below all previously published values for phytoplankton. When the Fe concentration in the
Erika Sternberg; Degui Tang; Tung-Yuan Ho; Catherine Jeandel; Franńois M. M. Morel
Leachability of barium-radium sulphate sludges
This paper presents results from the first phase of a research program designed to examine the leachability of radium-226 from barium-radium sulphate sludges. Batch leaching tests were performed. Results showed that liquid:solid contact time was relatively unimportant; radium in the sludge was stable in the presence of deionized water with a slight increase in the amount leached per gram of
P. M. Huck; B. Anderson
Formation of barium-tantalum oxynitrides
Oxynitride powders suitable for sintering to form dielectric ABO3-type perovskites have been prepared by nitriding barium carbonate and tantalum oxide. Both heat treatment in air and reaction in flowing ammonia yield isostructural oxynitride phases, but the amount and electronic state of the oxynitrides depend on the nitriding gas conditions. A red-brown oxynitride of high nitrogen content is described as Ba2Ta2O3N2
A. Hellwig; A. Hendry
Interaction between Calcium Ions and Bacillus thuringiensis Toxin Activity against Sf9 Cells (Spodoptera frugiperda, Lepidoptera)
The effects of calcium ions and modulators of calcium movement on Bacillus thuringiensis insecticidal protein toxicity were investigated with Sf9 cells (Spodoptera frugiperda, fall armyworm) by a new B. thuringiensis toxicity assay based on measurement of fluorescence of ethidium homodimer, a high-affinity DNA stain. CryIC toxicity was substantially stimulated by extracellular calcium in a dose-dependent way (in the millimolar range), while toxicity enhancement could not be replicated when calcium was replaced by barium. This incremental toxicity was reduced by cobalt and lanthanum ions, two inorganic-calcium transport inhibitors. Methoxyverapamil, a voltage-dependent calcium channel blocker, and nifedipine, an inhibitor of dihydropyridine-sensitive L-type calcium channels, had no effect on CryIC toxin activity, but BAY K 8644, an L-type calcium channel activator, increased CryIC activity at high concentrations of extracellular calcium. While A23187, a calcium ionophore, and TMB-8, an inhibitor of intracellular-calcium mobilization, did not change CryIC-induced mortality, thapsigargin, an inhibitor of calcium uptake in intracellular stores, and more particularly trifluoperazine, which inhibits calcium-calmodulin-dependent processes, increased CryIC-mediated toxicity. The incremental effect of extracellular calcium on CryIC-induced toxicity was consistent with an increased concentration of intracellular calcium.
Monette, R.; Potvin, L.; Baines, D.; Laprade, R.; Schwartz, J. L.
Rapid barium removal in the Delaware estuary
Six profiles of dissolved barium covering the entire salinity range of the Delaware River and Bay estuary from March through September 1996 were collected and analyzed. The profiles are similar to one another in both shape and magnitude except for one attribute. A sudden ({le} 24 days), nearly complete (>90%) removal of dissolved Ba in midestuary occurs in mid-May followed by an 80% recovery in early June. This removal appears to be temporally and spatially coupled to the end of the spring bloom. Based on such episodic behavior, and on recent work with flocculation of diatom exudates, the authors conclude that the Ba depletion is caused by barite precipitation in the estuary during the late stages of the bloom. This would imply that lower estuary and inner coastal margin sediments associated with eutrophic estuaries receive a seasonal pulse of barite. The suddenness of this event also implies that sedimentary barite is strongly influenced by high productivity events. Comparison of the riverine Ba concentration with the effective riverine end member after desorptive barium release yields an estimated 30--40 nM Ba available from the suspended sediments as they enter the estuary. This estimate is supported by excess barium in unfiltered samples over filtered samples taken from the river and also by calculations done elsewhere.
Stecher, H.A. III [Univ. of Delaware, Lewes, DE (United States). College of Marine Studies] [Univ. of Delaware, Lewes, DE (United States). College of Marine Studies; [Univ. of Delaware, Newark, DE (United States). Dept. of Geology; Kogut, M.B. [Univ. of Washington, Seattle, WA (United States). School of Oceanography] [Univ. of Washington, Seattle, WA (United States). School of Oceanography
Physicochemical characteristics of Ba 2+ mixed calcium tartrate crystals
Non-linear optical single crystals of barium mixed calcium tartrate tetrahydrate with molecular formula Ca0.8Ba0.2C4H4O6Ę4H2O (CBT) have been grown in gels using a chemical reaction method at ambient temperature. The physical and chemical characteristics of gel grown CBT crystals have been investigated by employing Vickers micro hardness, etching, and thermal techniques. The single crystalline habit of CBT is deviated from that
K Suryanarayana; S. M Dharmaprakash
The properties and uses of fluxes in molten aluminum processing
Gaseous and solid fluxes play an important role in the degassing, demagging, and fluxing of aluminum and its alloys. Inert as well as reactive gases, or hexachloroethane, may be used to remove dissolved hydrogen and sodium. Magnesium may be removed by chlorine or an aluminum-fluoride-containing flux. Fluxes based on a KCl-NaCl mixture may be used to cover and protect the metal from oxidation. To recover aluminum from drosses, a more reactive flux containing cryolite or some other fluoride may be used. In this article, the thermodynamics of aluminum melting and refining are analyzed in terms of the behavior of sodium, magnesium, and calcium. The coalescence of aluminum drops in salt fluxes improves with fluoride additions. With increasing MgCl2 contents in the flux, the effects of NaF and KF additions become much less pronounced.
Utigard, T. A.
Aluminum hydroxide production
A method is described for the production of aluminum hydroxide, comprising reacting water in the liquid phase and aluminum of surface area of at least 20 mm/sup 2/ per gram at a pH above about 12.4 for producing a reaction mixture containing aluminum hydroxide, and collecting solid aluminum hydroxide from the reaction mixture, the reaction being carried out in the presence of choline at a concentration of about 0.05 to 2 mols per liter.
Martin, E.S.; Weaver, M.L.
Biocompatibility of Intracanal Medications Based on Calcium Hydroxide
Objective. The aim of this study was to evaluate the rat subcutaneous tissue reaction to calcium hydroxide-based intracanal medicaments, UltraCal XS (calcium hydroxide, barium sulphate, aqueous matrix), Hydropast (calcium hydroxide, barium sulphate, and propyleneglycol), and Calen (Calcium hydroxide, zinc oxide, colophony, and polyethyleneglycol), used as a control. Methods. Forty-eight rats (Rattus Norvegicus Holtzman) were distributed in three groups: Calen, UltraCal XS, and Hydropast. Polyethylene tubes filled with one of the medicaments were implanted in the dorsal subcutaneous. After 7 and 30 days, the implants were removed and the specimens were fixed and embedded in paraffin. Morphological and quantitative analyses were carried out in the HE-stained sections. The numerical density of inflammatory cells in the capsule was evaluated and statistical analyses were performed (P ? 0.05). Results. At 7 days, all materials induced an inflammatory reaction in the subcutaneous tissue adjacent to the implants. In all groups, a significant reduction in the number of inflammatory cells and giant cells was verified in the period of 30 days. Conclusion. These results indicate that the calcium hydroxide-based medicaments evaluated present biocompatibility similar to Calen.
Andolfatto, Carolina; da Silva, Guilherme Ferreira; Cornelio, Ana Livia Gomes; Guerreiro-Tanomaru, Juliane Maria; Tanomaru-Filho, Mario; Faria, Gisele; Bonetti-Filho, Idomeo; Cerri, Paulo Sergio
Biocompatibility of intracanal medications based on calcium hydroxide.
Objective. The aim of this study was to evaluate the rat subcutaneous tissue reaction to calcium hydroxide-based intracanal medicaments, UltraCal XS (calcium hydroxide, barium sulphate, aqueous matrix), Hydropast (calcium hydroxide, barium sulphate, and propyleneglycol), and Calen (Calcium hydroxide, zinc oxide, colophony, and polyethyleneglycol), used as a control. Methods. Forty-eight rats (Rattus Norvegicus Holtzman) were distributed in three groups: Calen, UltraCal XS, and Hydropast. Polyethylene tubes filled with one of the medicaments were implanted in the dorsal subcutaneous. After 7 and 30 days, the implants were removed and the specimens were fixed and embedded in paraffin. Morphological and quantitative analyses were carried out in the HE-stained sections. The numerical density of inflammatory cells in the capsule was evaluated and statistical analyses were performed (P ? 0.05). Results. At 7 days, all materials induced an inflammatory reaction in the subcutaneous tissue adjacent to the implants. In all groups, a significant reduction in the number of inflammatory cells and giant cells was verified in the period of 30 days. Conclusion. These results indicate that the calcium hydroxide-based medicaments evaluated present biocompatibility similar to Calen. PMID:23320187
Andolfatto, Carolina; da Silva, Guilherme Ferreira; Cornķlio, Ana Livia Gomes; Guerreiro-Tanomaru, Juliane Maria; Tanomaru-Filho, Mario; Faria, Gisele; Bonetti-Filho, Idomeo; Cerri, Paulo Sķrgio
Aluminum and Young Artists.
The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)
Anderson, Thomas
A study was conducted to determine the biological availability of naturally occurring barium in a municipal drinking water by the analysis of barium in deciduous teeth of children. The grade school children of two Illinois towns were chosen for the study. The towns were chosen ba...
Toward a more environmentally benign synthesis of doped barium titanate
Barium titanate is one of the most thoroughly studied members of the perovskite family due to its prominent place in the electroceramic industry. To be used as a capacitor at room temperature, a high-dielectric constant is needed which is achieved through doping. The focus of this research was to develop a more environmentally benign alternative to the doping of barium
Anne Marteel-Parrish; Samantha DeCarlo; Danielle Harlan; Jonathan Martin; Heather Sheridan
Large electrostrictive actuation of barium titanate single crystals
An experimental investigation of the electromechanical behavior of single crystals of the ferroelectric perovskite barium titanate is presented. An experimental setup has been designed to investigate large strain actuation in single crystal ferroelectrics subjected to combined electrical and mechanical loading. Experiments have been performed on initially single domain crystals of barium titanate with (100) and (001) orientation at compressive stresses
E. Burcsu; G. Ravichandran; K. Bhattacharya
Composition and structure measurements in an ionospheric barium cloud
A 48 kg barium payload was launched from Eglin Air Force Base, Florida on 12 December 1980 at 2311 GMT and detonated at 183.7 km. At 2342:50.25 GMT, a second rocket, instrumented with an ion mass spectrometer and pulsed plasma probes, was fired to traverse the barium cloud. Composition, ion density, and structure measurements were acquired up to 241.2 km in both the natural and disturbed ionosphere. The rocket penetrated the barium cloud between 147 and 184 km. In addition to the Ba+, Ba++ produced by H Lyman alpha ionization, and Ca+, an impurity in the barium were detected in the cloud. A peak barium ion concentration of about 6,000,000 ions cu cm was measured at 161 km where the ionospheric NO+ and O2+ ions were essentially eliminated by large recombination loss. The bottom side of the barium cloud had a relatively smooth structure while the top side showed significant density fluctuations. The first experimental evidence of a theoretically predicted E region 'image cloud' was found in the form of an enhanced NO+ layer just below the barium cloud. Unexplained wave-like density variations in O+, NO+, and O2(+) also were seen above the barium cloud to 195 km. A quantitative estimate of the outgassing water vapor concentrations near the payload's surface was made using the fast change transfer rate coefficient for O+ + H2O yields H2O+ + O that created the observed water vapor ions.
Narcisi, R.; Tracinski, E.; Federico, G.; Wlodyka, L.; Bench, P.
A research project was undertaken to investigate processes for removing barium and radium from drinking water. Special emphasis was placed on ion exchange processes that can be used without adding large concentrations of sodium to the water. The wastes from radium and barium removal processes were also characterized, and processes suitable for treatment of ion-exchange brines were evaluated. The report
V. L. Snoeyink; C. C. Chambers; C. K. Schmidt; R. F. Manner; A. G. Myers
Barium strontium titanate powder obtained by polymeric precursor method
Pure barium strontium titanate powder, with Ba\\/Sr ratio of 80\\/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 ░C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.
A. Ries; A. Z. Sim§es; M. Cilense; M. A. Zaghete; J. A. Varela
Pure barium strontium titanate powder, with Ba/Sr ratio of 80/20 was prepared by the polymeric precursor method (also called Pechini process). The powder was obtained after a calcination at 800 deg. C for 8 h and characterized by XRD, IR, BET and SEM. The requirements to avoid barium carbonate as a secondary phase are presented and discussed in detail.
Ries, A.; Simoes, A.Z.; Cilense, M.; Zaghete, M.A.; Varela, J.A
Thermal decomposition of (BaTi) citrates into barium titanate
From aqueous solutions of barium and titanium citrates two different (BaTi) citrate salts can be precipitated, depending on the pH of the solution. The ratio of barium to titanium in the salts is either 1 : 1 or 2 : 1. The thermal decomposition of the salts was investigated by means of DTA, TGA, infrared spectroscopy, and X-ray diffraction. At
D. Hennings; W. Mayr
A study of the effects of microsilica and barium sulfate as additives in high-tabular alumina castables on cold and hot modulus\\u000a of rupture, porosity, thermal shock, and corrosion resistance to aluminum attack is reported in this article. This investigation\\u000a underlined the importance of the quality of fumed silica on the physical and mechanical properties of refractory castables,\\u000a and also confirmed
Saied Afshar; Christophe Gaubert; Claude Allaire
Current-voltage characteristics of barium polymethacrylate
In this paper current-voltage characteristics of Barium Polymethacrylate (BaPMA) in the form of Al-BaPMA-Al structures are studied. The currents are measured in the voltage range 10 V-1 kV. At low voltages an ohmic relation is observed and at higher voltages the Poole-Frenkel mechanism is proposed. The mechanism of conduction has been explained on the basis of different current-voltage and current-temperature curves. The activation energy values calculated using Arrhenius relation fall in the range 0.25-2 eV, suggesting a sequence of trapping levels.
Chohan, M.H. (Lab. for Electrical Characterization of Polymers, Dept. of Electronics, Quaid-i-Azam Univ., Islamabad (PK)); Zulfiqar, M.; Sapra, Z.H.; Husain, R.; Zulfiqar, S. (Dept. of Chemistry, Quaid-i-Azam Univ., Islamabad (PK))
Dielectric properties of barium titanate supramolecular nanocomposites
Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (?r) as high as 15 and a relatively low dielectric loss of ~0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures.
Lee, Keun Hyung; Kao, Joseph; Parizi, Saman Salemizadeh; Caruntu, Gabriel; Xu, Ting
Dielectric properties of barium titanate supramolecular nanocomposites.
Nanostructured dielectric composites can be obtained by dispersing high permittivity fillers, barium titanate (BTO) nanocubes, within a supramolecular framework. Thin films of BTO supramolecular nanocomposites exhibit a dielectric permittivity (?r) as high as 15 and a relatively low dielectric loss of ?0.1 at 1 kHz. These results demonstrate a new route to control the dispersion of high permittivity fillers toward high permittivity dielectric nanocomposites with low loss. Furthermore, the present study shows that the size distribution of nanofillers plays a key role in their spatial distribution and local ordering and alignment within supramolecular nanostructures. PMID:24584569
Short-cavity squeezing in barium
Broadband phase sensitive noise and squeezing were experimentally observed in a system of barium atoms interacting with a single mode of a short optical cavity. Squeezing of 13 +/- 3 percent was observed. A maximum possible squeezing of 45 +/- 8 percent could be inferred for out experimental conditions, after correction for measured loss factors. Noise reductions below the quantum limit were found over a range of detection frequencies 60-170 MHz and were best for high cavity transmission and large optical depths. The amount of squeezing observed is consistent with theoretical predictions from a full quantum statistical model of the system.
Hope, D. M.; Bachor, H-A.; Manson, P. J.; Mcclelland, D. E.
Europium-doped barium bromide iodide
Single crystals of Ba0.96Eu0.04BrI (barium europium bromide iodide) were grown by the Bridgman technique. The title compound adopts the ordered PbCl2 structure [Braekken (1932). Z. Kristallogr. 83, 222-282]. All atoms occupy the fourfold special positions (4c, site symmetry m) of the space group Pnma with a statistical distribution of Ba and Eu. They lie on the mirror planes, perpendicular to the b axis at y = +-0.25. Each cation is coordinated by nine anions in a tricapped trigonal prismatic arrangement.
Gundiah, Gautam; Hanrahan, Stephen M.; Hollander, Fredrick J.; Bourret-Courchesne, Edith D.
Modifier cation (Ba, Ca, La, Y) field strength effects on aluminum and boron coordination in aluminoborosilicate glasses: the roles of fictive temperature and boron content
The field strength of modifier cations has long been known to have important effects on oxide glass properties, but effects on network structure can be complex. For two series of barium, calcium, lanthanum and yttrium aluminoborosilicates with two different B/Si ratios, we report systematic variations in boron and aluminum coordination determined by NMR, and glass transition and heat capacities from differential scanning calorimetry. Data on glasses with different fictive temperatures allow B and Al speciation to be compared on an isothermal basis, rather than as conventionally done for as-quenched structures. Temperature and compositional effects can thus be isolated. These data and comparison to previous studies on glasses with lower B/Si ratios clearly show that higher modifier cation field strength increases the fraction of five- and six-coordinated Al in all compositions. In contrast, the previously documented trend towards more three-coordinated boron (and hence more non-bridging oxygens, NBO) in low B/Si glasses with higher field strength cations reverses in high B/Si and in high NBO compositions. Al and B coordination numbers both decrease with higher fictive temperature in the glasses studied here, suggesting a simple mechanism of coupled structural change.
Morin, Elizabeth I.; Wu, Jingshi; Stebbins, Jonathan F.
Minerals Yearbook 1991: Calcium and Calcium Compounds.
Calcium, is chemically very active and is found in a host of minerals that occur in nearly every geologic environment. Calcium fluoride is sold as fluorspar; calcium sulfate as gypsum or anhydrite; calcium oxide and hydroxide as lime; calcium phosphate as...
M. M. Miller
Aluminum reference electrode
A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.
Sadoway, D.R.
A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.
Sadoway, Donald R. (Belmont, MA)
Idiopathic calcinosis cutis in fingertip treated with occlusive dressing using aluminum foil: a case report.
Calcium deposition in the skin, known as calcinosis cutis, is an uncommon disorder caused by an abnormal deposit of calcium phosphate in the skin. We report a case of idiopathic calcinosis cutis in fingertip treated with surgical excision followed by the occlusive dressing using aluminum foil, and obtained significant pain relief and round-shaped fingertip which looked normal. PMID:18360918
Sato, Kazuki; Nakamura, Toshiyasu; Toyama, Yoshiaki; Ikegami, Hiroyasu; Kameyama, Kaori; Takayama, Shinichiro
Barium in Deep-Sea Sediment: A Geochemical Proxy for Paleoproductivity
We used sediment traps to define the particulate fluxes of barium and organic carbon and investigate the use of barium as a proxy for ocean fertility. Strong correlations between Corg and Ba fluxes indicate a link between upper ocean biological processes and barium flux to the seafloor. The ratio of organic carbon to barium decreases systematically with water depth. Data
Jack Dymond; Erwin Suess; Mitch Lyle
Effect of Barium on Growth and Macronutrient Nutrition in Tanzania Guineagrass Grown in Nutrient Solution
Barium has been identified as a toxic element to most plants, although for grasses the toxicity has not been determined. A greenhouse experiment was performed to evaluate the effect of barium on growth parameters, barium accumulation, and macronutrient concentration in Tanzania guineagrass (Panicum maximum Jacq.), cultivated in nutrient solution. Five barium rates and a control were set in a complete
Francisco Antonio Monteiro; Roberta CorrĻa Nogueirol; Le¶nidas Carrijo Azevedo Melo; Adriana Guirado Artur; Fabiana da Rocha
Particulate barium fluxes and their relationships to biological productivity
To understand better the processes that control the transport of particulate barium through the water column and its preservation in marine sediments, we measured particulate barium fluxes along an equatorial transect at 140░W using moored sediment traps. The fluxes of barium correlate strongly with the fluxes of organic carbon; however, this relationship is non-linearŚhigher carbon fluxes have proportionately less associated barium. As a result we observe spatial and temporal variations of roughly a factor of three in the barium-to-organic carbon ratio. Understanding this variability may help to define the processes that determine the geochemical behavior of Ba in the oceans. Several hypotheses that could influence the flux of Ba and its relationship to organic carbon flux have been proposed: barite formation in barium- and sulfate-enriched microenvironments formed during particle settling; lateral advection of carbon and barium from continental margins; the influence of seawater barium concentration; and Ba scavenging by aluminosilicates. Our study reveals temporal variability in the Ba/C org values that occurs over timescales of less than one month. Also, depth profiles of carbon and Ba fluxes show that the variability originates at depths less than 1200 m and is conveyed throughout the water column. Both the rapid changes and the upper water column origin of the signals point to upper-ocean biological processes as the predominant cause of the variability in the barium-to-organic carbon ratios. We also observe, however, a 25% increase in Ba flux below 1200 m. The deep sources of Ba could result from barite formation linked to continued organic carbon degradation or from lateral sources of particulate barium. Because the spatial and temporal changes in Ba/C org values correlated to changes in particulate opal and organic carbon fluxes, ocean ecology appears to have an important influence on barium fluxes. A better understanding of the processes that contribute to the particulate barium flux is needed before the accumulation of barium in marine sediments can be used as a quantitative proxy for ocean productivity.
Dymond, Jack; Collier, Robert
Project Calcium
Fouling problems in utility boilers have been classified into two principal types: high-temperature and low-temperature fouling. A multiclient-sponsored program was initiated at the Energy and Environmental Research Center (EERC) to better understand the causes of low-temperature fouling when burning high-calcium western US coals. The goals of Project Calcium were to define the low-temperature deposition problem, identify the calcium-based components that are responsible for the formation of the deposits, develop ways to predict their formation, and identify possible methods to mitigate the formation of these deposits. To achieve the goals of Project Calcium, detailed sampling of utility boilers and laboratory-scale studies coupled with state-of-the-art methods to determine the inorganic components in coals and coal ash-derived materials were conducted. Boiler Sampling was also performed. The work involved sampling coal, entrained ash, deposits and slags from five full-scale utility boilers combined with detailed advanced characterization of the materials. The results of this work aided in identifying the key phenomena to focus the laboratory studies and in model verification. Field testing was conducted at three utilities.
Hurley, J.P.; Benson, S.A.; Erickson, T.A.; Allan, S.E.; Bieber, J.
Microstructure and magnetism in barium strontium titanate (BSTO)-barium hexaferrite (BaM) multilayers
High quality multilayers of barium ferrite (BaM) and barium strontium titanate (BSTO) were grown in optimized conditions on thermally oxidized Si(1 0 0) and Al{sub 2}O{sub 3} substrates using magnetron sputtering. As-grown films were amorphous and different annealing procedures were explored to stabilize crystalline phases. BSTO and BaM phases were identified using X-ray diffraction and cross-sectional scanning electron micrographs showed sharp interfaces between BSTO and BaM layers. Magnetic hysteresis loops obtained at various temperatures and field orientations showed a large coercivity ({approx}2500 Oe) consistent with the hard magnetic hexaferrite component. Hysteresis loops also revealed the distinct influence of magnetocrystalline and shape anisotropies at different temperature ranges.
Frey, N.A. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Heindl, R. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Srinath, S. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States); Srikanth, H. [Materials Physics Laboratory, Physics Department, University of South Florida, 4202 East Fowler Avenue, Tampa, FL 33620 (United States)]. E-mail: email@example.com; Dudney, N.J. [Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
Fabrication of Lotus-Type Porous Aluminum through Thermal Decomposition Method
Lotus-type porous aluminum with cylindrical pores was fabricated by unidirectional solidification through thermal decomposition of calcium hydroxide, sodium bicarbonate, or titanium hydride. The pore-forming gas decomposed from calcium hydroxide, sodium bicarbonate, and titanium hydride is identified as hydrogen. The elongated pores are evolved due to the solubility gap between liquid and solid when the melt dissolving hydrogen is solidified unidirectionally. The porosity of lotus aluminum is as high as 20 pct despite the type of the compounds. The pore size decreases and the pore density increases with increasing amount of calcium hydroxide, which is explained by an increase in the number of pore nucleation sites. The porosity and pore size in lotus aluminum fabricated using calcium hydroxide decrease with increasing argon pressure, which is explained by BoyleÆs law. It is suggested that this fabrication method is simple and safe, which makes it superior to the conventional technique using high-pressure hydrogen gas.
Kim, S. Y.; Park, J. S.; Nakajima, H.
Electroplating with aluminum
Electrodeposited aluminum has a broad range of potential applications in many industries because it offers the possibility of combining the surface properties of aluminum with the bulk properties of the substrate. Aluminum provides excellent corrosion protection and can withstand high temperatures. Plated aluminum can be anodized over virtually any substrate, including steel, copper, and titanium. However, because of its negative standard potential, aluminum can be electrodeposited only out of an absolutely water-free electrolyte. Otherwise the water is electrolyzed, generating hydrogen and oxygen. In response to the technical demand for an electrochemical aluminum deposition process, Siemens AG in Germany has developed and patented a process based on a water-free electrolyte. This proprietary technology, known in Germany as the Sigal process, has been licensed to AlumiPlate for worldwide commercialization. This article describes the process, coating properties, and applications.
Froemberg, W.; Donaldson, F.A.S. [AlumiPlate, Inc., Coon Rapids, MN (United States)
Aspects of aluminum toxicity
Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.
Hewitt, C.D.; Savory, J.; Wills, M.R. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))
Proton conductivity of potassium doped barium zirconates
Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10%. Introducing extra potassium leads to the formation of second phase or YSZ impurities. The water uptake of barium zirconates was increased even with 5% doping of potassium at the A-site. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. The maximum solubility for yttrium at B-sites is around 15 at% after introducing 1 wt% zinc. The conductivity of Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} at 600 deg. C is 2.2x10{sup -3} S/cm in wet 5% H{sub 2}. The activation energies for bulk and grain boundary are 0.29(2), 0.79(2) eV in wet 5% H{sub 2} and 0.31(1), 0.74(3) eV in dry 5% H{sub 2}. A power density of 7.7 mW/cm{sup 2} at 718 deg. C was observed when a 1 mm thick Ba{sub 0.95}K{sub 0.05}Zr{sub 0.85}Y{sub 0.11}Zn{sub 0.04}O{sub 3-{delta}} pellet was used as electrolyte and platinum electrodes. - Graphical abstract: Potassium doped barium zirconates have been synthesized by solid state reactions. It was found that the solubility limit of potassium on A-sites is between 5% and 10 %. The sintering conditions and conductivity can be improved significantly by adding 1 wt% ZnO during material synthesis. Five percent doping of potassium at A-site can double the total conductivity.
Xu Xiaoxiang [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom); Tao Shanwen, E-mail: firstname.lastname@example.com [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom); Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Irvine, John T.S. [School of Chemistry, University of St. Andrews, Fife KY16 9ST (United Kingdom)
Mechanism of action of nitric oxide donors on voltage-activated calcium channels in vascular smooth muscle cells
The effects of nitric oxide (NO) donors on inward barium current (IBa) in freshly isolated smooth muscle cells (SMC) of the guinea pig mesenteric artery and on inward calcium current (ICa) in SMC of the canine coronary artery were studied using a patch-clamp recording technique in whole-cell configuration. The inward current in SMC of the guinea pig artery was shown
A. V. Zima; A. ╔. Belevich; A. V. Povstyan; M. I. Kharkhun; Ya. D. Tsitsyura; M. F. Shuba
Magnetic properties of substituted barium ferrite powders
Hexagonal barium ferrites were prepared using the citrate method. Cobalt and titanium were added in the amounts x from 0.2 to 1.1 ion/f.u. related to the formula BaCo{sub x}Ti{sub x}Fe{sub 12{minus}2x}O{sub 19}. The heat treatment has been applied in three steps of 550 C/5 hrs, 850 C/2 hrs and 1,100 C/2 hrs. The following magnetic properties have been achieved: H{sub c} {approximately} 80 kA/m, J{sub s} {approximately} 120 {times} 10{sup {minus}6} Tkg{sup {minus}1} m{sup 3}, and J{sub r} {approximately} 60 {times} 10{sup {minus}6} Tkg{sup {minus}1} m{sup 3} in the composition for which x is equal to 0.5 ion/f.u. The magnetic parameters have been measured by the vibration magnetometer.
Gruskova, A. [Slovak Univ. of Technology, Bratislava (Slovakia). Dept. of Electrotechnology] [Slovak Univ. of Technology, Bratislava (Slovakia). Dept. of Electrotechnology
Barium hexaferrite ferrofluids - preparation and physical properties
Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared for the first time using oleic acid as surfactant and Isopar M « as carrier liquid. The initial susceptibility versus temperature for zero-field cooling of the ferrofluid was obtained by a vibrating sample magnetometer. TEM pictures of the fluid show isolated particles and only small agglomerates and a mean particle diameter of approx. 8 nm. Numerical calculations of the magneto-viscous effect, based on the local-equilibrium magnetic state model, clearly show the benefit for Ba-ferrite ferrofluids resulting from the high uniaxial anisotropy compared to magnetite ferrofluids. Rheological measurements were performed with a rotational-type viscometer with magnetic field perpendicular to the hydrodynamic vortex axis.
M³ller, R.; Hiergeist, R.; Steinmetz, H.; Ayoub, N.; Fujisaki, M.; Sch³ppel, W.
Synthesis of barium fluoride nanoparticles from microemulsion
The cetyltrimethylammonium bromide (CTAB)/2-octanol/water microemulsion system was used to synthesize barium fluoride nanoparticles. X-ray powder diffraction (XRD) analysis showed that the products were single phase. The results of scanning electron microscopy and calculations using the Scherrer equation from the line widths of the XRD have been used to estimate the average particle sizes of the powder products. The results showed that the nanoparticle size was affected by water content and surfactant (CTAB) concentration. As water content decreases from 14.2 to 9.47% (w/w), the particle size decreases from 75 to 40 nm. In addition, increasing the reaction times from 5 to 120 min increases the particle size from 75 to 150 nm, and increasing the amount of surfactant decreases the size of the particle. Luminescence spectra of the BaF2:Ce nanoparticles are also discussed.
Hua, Ruinian; Zang, Chunyu; Shao, Chen; Xie, Demin; Shi, Chunshan
Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant
A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.
LaCamera, Alfred F. (Trafford, PA)
Effects of light exposure on irradiated barium fluoride crystals.
Small barium fluoride crystals have been irradiated using cobalt-60 gamma rays under various illumination conditions to establish the effect of photo-bleaching of the radiation-induced color centers. This paper describes results of a few different experim...
C. R. Wuest G. J. Mauger
Study of the photovoltaic effect in thin film barium titanate
The feasibility of making non-volatile digital memory devices of barium titanate, BaTiO3, that are integrated onto a silicon substrate with the required ferroelectric film produced by processing, compatible with silicon technology was examined.
Grannemann, W. W.; Dharmadhikari, V. S.
Barium and Radium in Water Treatment Plant Wastes.
Water treatment plants at nine locations (10 plants) in Illinois and Iowa were studied to determine the characteristics and disposal practices for the sludge, brine, and backwash water containing radium (Ra) and/or barium (Ba). The treatment processes in ...
A. G. Myers C. K. Jongeward S. K. Richter V. L. Snoeyink
Calculated emission rates for barium releases in space
The optical emissions from barium releases in space are caused by resonance and fluorescent scattering of sunlight. Emission rates for the dominant ion and neutral lines are calculated assuming the release to be optically thin and the barium to be in radiative equilibrium with the solar radiation. The solar spectrum has deep Fraunhofer absorption lines at the primary barium ion resonances. A velocity component toward or away from the sun will Doppler shift the emission lines relative to the absorption lines and the emission rates will increase many-fold over the rest value. The Doppler brightening is important in shaped charge or satellite releases where the barium is injected at high velocities. Emission rates as a function of velocity are calculated for the 4554, 4934, 5854, 6142 and 6497 A ion emission lines and the dominant neutral line at 5535 A. Results are presented for injection parallel to the ambient magnetic field, B, and for injection at an angle to B.
Stenbaek-Nielsen, H. C.
Dielectrics of lead zirconate bonded with barium borate glass
Dielectric constant variation with temperature and frequency is reported for barium-borate glass-bonded lead zirconate. Lowering\\u000a of the relative permittivity of the ceramic is attributed to the presence of the glass.
K Singh; Aruna Indurkar
Influence of addition of rare earth metals to aluminum on the effectiveness of absorption of impurity oxygen from argon in a closed system
Removal of oxygen from closed systems plays a significant part in increasing the life of devices operating in absence of oxygen and other harmful impurities (e.g., in incandescent lamps, electronic tubes, etc.). Harmful gases are removed with the aid of gas absorbents. Magnesium, barium, aluminum, zirconium, titanium, rare earth metals (r.e.m.), and their compounds are used as gas absorbents. However, because of their high activity these substances are generally unsuitable for use in electric lamp production. Some of them, such as barium and magnesium, form deposits in the bulb dome which lower the luminous flux of the lamp, while others, e.g., zirconium, aluminum, and r.e.m., lose their initial activity during the technological assembly operations. In this communication results are reported of an investigation of the influence of rare earth metals added to aluminum on oxygen absorption in a closed space (incandescent lamp) when the oxygen content in the main gas is very low.
Glavatskii, Y.F.; Kozik, V.V.; Leshchev, S.V.; Serebrennikov, V.V.
Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...
Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers
Graphical abstract: The flower-shaped barium vanadate was obtained for the first time. The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. Research highlights: {yields} In the paper, the flower-shaped barium vanadate were obtained for the first time. The CHM method used here is new and simple for preparation of barium vanadate. {yields} The photoluminescence and magnetic properties of the barium vanadate nanoflowers were investigated at room temperature. The strong bluish-green emission was observed. {yields} The ferromagnetic behavior of the barium vanadate nanoflowers was found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g. {yields} The mechanisms of PL and magnetic property of barium vanadate nanoflowers have been discussed. -- Abstract: The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V{sub 2}O{sub 5} and BaCl{sub 2} at 200 {sup o}C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba{sub 3}V{sub 2}O{sub 8} with small amount of Ba{sub 3}VO{sub 4.8} coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of {approx}20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO{sub 4} tetrahedron with T{sub d} symmetry in Ba{sub 3}V{sub 2}O{sub 8}. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 x 10{sup -3} emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 x 10{sup -3} emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.
Xu, Jing [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China) [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Chongqing University of Science and Technology, Chongqing 401331 (China); Hu, Chenguo, E-mail: firstname.lastname@example.com [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Xi, Yi [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China); Peng, Chen [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China)] [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Wan, Buyong; He, Xiaoshan [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)] [Department of Applied Physics, Chongqing University, 174 Shapingba Street, Chongqing 400044 (China)
Neutron source, neutron density and the origin of barium stars
The authors present new high resolution spectra of the MgH profiles in nine barium stars, and determine, by spectral synthesis techniques, the magnesium isotopic ratios in each star. When compared with recent AGB nucleosynthesis calculations, they can emphatically rule out the operation of the 22Ne(alpha, n)25Mg reaction as the neutron source responsible for the s-process enhancements observed in these barium
Robert A. Malaney; David L. Lambert
White-dwarf kicks and implications for barium stars
The formation mechanism of the barium stars is thought to be well understood. Barium-rich material, lost in a stellar wind from a thermally-pulsing asymptotic-giant branch star in a binary system, is accreted by its companion main-sequence star. Now, many millions of years later, the primary is an unseen white dwarf and the secondary has itself evolved into a giant which displays absorption lines of barium in its spectrum and is what we call a barium star. A similar wind-accretion mechanism is also thought to form the low-metallicity CH and carbon-enhanced metal-poor stars. Qualitatively the picture seems clear but quantitatively it is decidedly murky: several key outstanding problems remain which challenge our basic understanding of binary-star physics. Barium stars with orbital periods less than about 4000 days should - according to theory - be in circular orbits because of tidal dissipation, yet they are often observed to be eccentric. Only one barium-star period longer than 104 days has been published although such stars are predicted to exist in large numbers. In this paper we attempt to shed light on these problems. First, we consider the impact of kicking the white dwarf at its birth, a notion which is supported by independent evidence from studies of globular clusters. Second, we increase the amount of orbital angular momentum loss during wind mass transfer, which shrinks barium-star binaries to the required period range. We conclude with a discussion of possible physical mechanisms and implications of a kick, such as the break up of wide barium-star binaries and the limits imposed on our models by observations.
Izzard, R. G.; Dermine, T.; Church, R. P.
The properties of barium titanate RF sputtered in argon
The structural, optical and dielectric properties of barium titanate thin films deposited on water-cooled substrates by RF sputtering in Ar (99.99%) were investigated. Optically thin and thick films for the visible spectral region were studied.From the investigations it is concluded that there are at least two crystalline phases in addition to amorphous barium titanate in the deposited coatings, and the
T Pencheva; M Nenkov
'Skidding' of the CRRES G-9 barium release
A simulation study and experimental data of the CRRES G-9 ionospheric barium release are presented. The simulation study is based on a 2D electrostatic code that incorporates time-dependent coupling to the background plasma. It is shown that the densest portion of the barium ion cloud 'skids' about 15 km within the first three seconds following the release, consistent with the optical data analyses.
Huba, J. D.; Mitchell, H. G.; Fedder, J. A.; Bernhardt, P. A.
Origin of dynamical heterogeneities in calcium aluminosilicate liquids.
We investigate the heterogeneous dynamics of calcium aluminosilicate liquids across both the peraluminous and peralkaline regimes. Using the isoconfigurational ensemble method we find a clear correlation between dynamical heterogeneities and concentration fluctuations. Regions of high dynamic propensity have higher concentrations of both calcium and aluminum, whereas low propensity regions are silica rich. The isoconfigurational ensemble is found to be a powerful tool for studying the origin of heterogeneous dynamics of industrially relevant glass-forming liquids. PMID:20499973
Vargheese, K Deenamma; Tandia, Adama; Mauro, John C
Aluminum: Reducing chloride emissions from aluminum production
Reynolds Metals Company (RMC), with assistance from a NICE{sup 3} grant, is developing for commercialization a closed-loop control process that greatly reduces chlorine emissions and increases plant efficiency while maintaining metal quality. The process still utilizes chlorine to remove impurities during aluminum processing, but is more effective than current methods. With the new technology chlorine in the stack is monitored and input chlorine is adjusted continuously. This optimization of chlorine use results in substantially less waste because less chlorine has to be bought or produced by aluminum manufacturers. This innovation is a significant improvement over conventional aluminum treatments, in which chlorine is injected in a more costly and wasteful manner. By the year 2010, the new technology has the potential to reduce the energy it takes to create chlorine by 8.4 billion Btu per year and to cut greenhouse gas emissions by 1,377 tons per year.
Simon, P.
Releasing effects in flame photometry: Determination of calcium
Strontium, lanthanum, neodymium, samarium, and yttrium completely release the flame emission of calcium from the depressive effects of sulfate, phosphate, and aluminate. Magnesium, beryllium, barium, and scandium release most of the calcium emission. These cations, when present in high concentration, preferentially form compounds with the depressing anions when the solution is evaporated rapidly in the flame. The mechanism of the interference and releasing effects is explained on the basis of the chemical equilibria in the evaporating droplets of solution and is shown to depend upon the nature of the compounds present in the aqueous phase of the solution. The need for background correction techniques is stressed. The releasing effect is used in the determination of calcium in silicate rocks without the need for separations.
Dinnin, J. I.
Correlating Aluminum Burning Times
Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed,
M. W. Beckstead
Anodizing Aluminum with Frills.
"Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are alsoģ
Doeltz, Anne E.; And Others
The aluminum smelting process.
This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722
Kvande, Halvor
Polymerized complex route to barium titanate powders using barium-titanium mixed-metal citric acid complex
Barium titanate (BaTiOŌ) powders were prepared by a polymerized complex method based on the Pechini-type reaction route, wherein a mixed solution of citric acid (CA), ethylene glycol (EG), and barium and titanium ions, with a molar ratio of CA:EG:Ba:Ti = 10:40:1:1, was polymerized to form a transparent resin, which was used as a precursor for BaTiOŌ. Characterization of the initial
Momoko Arima; Masato Kakihana; Yoshiyuki Nakamura; Masatomo Yashima; Masahiro Yoshimura
Sol-gel synthesis of ultrafine barium titanate using butyl titanate monomer and barium nitrate and its characterization
Barium titanate is a well-known ferroelectric material (Tc ? 120░C) dominating the dielectric ceramics field for the last five decades and is very widely used in multi-layer capacitors. It is usually prepared via the classical solid state reaction between barium carbonate and titanium dioxide around 1100¢1300░C. On the other hand, chemical routes with new precursors are being developed to improve
P. D. Godbole; S. B. Deshpande; S. K. Date; Rashmi Nawathey; S. B. Ogale
Preparation of crystalline beta barium borate thin films on Sr 2+-doped alpha barium borate substrates by liquid phase epitaxy
Thin films of beta barium borate have been prepared by liquid phase epitaxy on Sr2+-doped ?-BaB2O4 (?-BBO, the high temperature phase of barium borate) (001) and (110) substrates. The results of X-ray diffraction indicate that the films show highly (00l) preferred orientation on (001)-oriented substrates while the films grown on (110) substrates are textured with (140) orientation. The crystallinity of
Junfang Liu; Xiaoming He; Changtai Xia; Guoqing Zhou; Shengming Zhou; Jun Xu; W. Yao; Liejia Qian
Calcium and osteoporosis
Calcium is an essential nutrient that is involved in most metabolic processes and the phosphate salts of which provide mechanical rigidity to the bones and teeth, where 99% of the body's calcium resides. The calcium in the skeleton has the additional role of acting as a reserve supply of calcium to meet the body's metabolic needs in states of calcium
B. E. Christopher Nordin
Barium determination in gastric contents, blood and urine by inductively coupled plasma mass spectrometry in the case of oral barium chloride poisoning.
A serious case of barium intoxication from suicidal ingestion is reported. Oral barium chloride poisoning with hypokalemia, neuromuscular and cardiac toxicity, treated with intravenous potassium supplementation and hemodialysis, was confirmed by the determination of barium concentrations in gastric contents, blood, serum and urine using the inductively coupled plasma mass spectrometry method. Barium concentrations in the analyzed specimens were 20.45 Ąg/L in serum, 150 Ąg/L in blood, 10,500 Ąg/L in urine and 63,500 Ąg/L in gastric contents. Results were compared with barium levels obtained from a non-intoxicated person. PMID:24794066
Lukasik-G??bocka, Magdalena; Sommerfeld, Karina; Han?, Anetta; Grzegorowski, Adam; Bara?kiewicz, Danuta; Gaca, Micha?; Zieli?ska-Psuja, Barbara
Environmental deterioration of aluminum-aluminum connections
Wire splice connections are investigated for deterioration due to environmental factors. The tested splices of solid aluminum and copper wires are made using twist-on connectors. Some specimen groups are exposed in a chamber at 35░C and 90% relative humidity. Additional groups are exposed for ten years to a normal application environment. There is no current flow except when potential drop
Jesse Aronstein
Calcium Collage
In this activity (on pages 11-14 of PDF), learners cut out pictures from magazines of foods that help make bones strong and glue the pictures to a paper bone. The lesson plan includes information about various activities - including physical exercise as well as diet - that lead to healthy bones. It also includes a list of foods that provide calcium to strengthen bones, including dairy products, spinach, and tofu. The paper bones can be cut out of construction paper prior to the activity.
Electrooptic and piezoelectric measurements in photorefractive barium titanate and strontium barium niobate
The authors measured the low-frequency (''unclamped'') electrooptic and piezoelectric coefficients in undoped BaTiO/sub 3/ and Sr/sub x/Ba/sub 1-x/Nb/sub 2/O/sub 6/ (chi - 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurement is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of of the applied field and independent of its frequency in the range of 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO/sub 3/ single crystals are r/sub 13/ = 19.5 +- 1 pm/V and r/sub 33/ = 97 +- 7 pm/V, and for strontium barium niobate are r/sub 13/ = 47 +- 5 pm/V and r/sub 33/ = 235 +- 21 pm/V, all measured at a wavelength of 514.5 nm and at T = 23/sup 0/C. For the barium titanate samples the measured Pockels coefficient r/sub c/ identical to r/sub 33/ - (n/sub 1//n/sub 3/)/sup 3/r/sub 13/ = 79 +- 6 pm/V in good agreement with the value r/sub c/ = 76 +- 7 pm/V computed from the above values of r/sub 13/ and r/sub 33/, where n/sub 1/ and n/sub 3/ are the ordinary and extraordinary indexes of refraction, respectively. The measured piezoelectric coefficient is d/sub 23/ = +28.7 +- 2 pm/V for barium titanate, and is d/sub 23/ = +24.6 +- 2 pm/V for strontium barium niobate. They also measured the photoreflective coupling of two optical beams in the crystals, and they show that the dependence of the coupling strength on beam polarization is in fair agreement with the measured values of the Pockels coefficients.
Ducharme, S.; Feinberg, J.; Neurgaonkar, R.R.
Hydrothermal transformation of the calcium aluminum oxide hydrates CaAl{sub 2}O{sub 4}.10H{sub 2}O and Ca{sub 2}Al{sub 2}O{sub 5}.8H{sub 2}O to Ca{sub 3}Al{sub 2}(OH){sub 12} investigated by in situ synchrotron X-ray powder diffraction
The hydrothermal transformation of calcium aluminate hydrates were investigated by in situ synchrotron X-ray powder diffraction in the temperature range 25 to 170 deg. C. This technique allowed the study of the detailed reaction mechanism and identification of intermediate phases. The material CaAl{sub 2}O{sub 4}.10H{sub 2}O converted to Ca{sub 3}Al{sub 2}(OH){sub 12} and amorphous aluminum hydroxide. Ca{sub 2}Al{sub 2}O{sub 5}.8H{sub 2}O transformed via the intermediate phase Ca{sub 4}Al{sub 2}O{sub 7}.13H{sub 2}O to Ca{sub 3}Al{sub 2}(OH){sub 12} and gibbsite, Al(OH){sub 3}. The phase Ca{sub 4}Al{sub 2}O{sub 7}.19H{sub 2}O reacted via the same intermediate phase to Ca{sub 3}Al{sub 2}(OH){sub 12} and mainly amorphous aluminum hydroxide. The powder pattern of the intermediate phase is reported.
Jensen, Torben R. [Interdisciplinary Nanoscience Center, Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus C (Denmark)]. E-mail: firstname.lastname@example.com; Christensen, Axel Norlund [Hojkolvej 7, DK-8210 Arhus V (Denmark); Hanson, Jonathan C. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA (United States)
Preparation of thick M-type barium hexaferrite films on double side of substrates by liquid-phase epitaxy deposition technique
Liquid-phase epitaxy deposition has been investigated to obtain thick and high quality of barium hexaferrite films on (111) gadolinium gallium garnet (GGG) and m-plane (11»00) aluminum oxide (Al2O3) substrates. For films deposited on (111) GGG substrate the c-axis was aligned perpendicular to the film plane, but in the plane for films deposited on Al2O3. The films were deposited on both sides of the substrates, where the total thickness of the films ranged between 70 and 190?m. The thickness and quality of these films meet the requirement for applications at high frequencies.
Yoon, S. D.; Vittoria, C.
Clinical biochemistry of aluminum
Aluminum toxicity has been implicated in the pathogenesis of a number of clinical disorders in patients with chronic renal failure on long-term intermittent hemodialysis treatment. The predominant disorders have been those involving either bone (osteomalacic dialysis osteodystrophy) or brain (dialysis encephalopathy). In nonuremic patients, an increased brain aluminum concentration has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer's disease and was associated with experimental neurofibrillary degeneration in animals. The brain aluminum concentrations of patients dying with the syndrome of dialysis encephalopathy (dialysis dementia) are significantly higher than in dialyzed patients without the syndrome and in nondialyzed patients. Two potential sources for the increased tissue content of aluminum in patients on hemodialysis have been proposed: (1) intestinal absorption from aluminum containing phosphate-binding gels, and (2) transfer across the dialysis membrane from aluminum in the water used to prepare the dialysate. These findings, coupled with our everyday exposure to the ubiquitous occurrence of aluminum in nature, have created concerns over the potential toxicity of this metal.
King, S.W.; Savory, J.; Wills, M.R.
Calcium source (image)
Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...
Coronary Calcium Scan
... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...
Calcium and bones (image)
Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...
Purifying Aluminum by Vacuum Distillation
Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.
Du Fresne, E. R.
Transient Inclusion Evolution During Modification of Alumina Inclusions by Calcium in Liquid Steel: Part II. Results and Discussion
The formation of intermediate reaction products after calcium addition to aluminum-killed steel was studied. Steel samples were taken from laboratory and industrial heats before and at various times after calcium treatment. Inclusions were characterized by automated and manual scanning electron microscopy and X-ray microanalysis of polished cross sections and inclusions extracted by dissolution of the steel. Industrial and laboratory melts containing more than 40 parts per million (by mass) of dissolved sulfur showed calcium sulfide as the main reaction product after calcium injection, with calcium aluminates appearing later. It is proposed that the calcium aluminates are formed by reaction between the calcium sulfide and the alumina. A laboratory heat containing 7 parts per million of sulfur showed calcium oxide as the main initial calcium reaction product. A simple mechanism is proposed for the modification of alumina inclusions by calcium, considering transient CaO and CaS formation.
Verma, N.; Pistorius, Petrus C.; Fruehan, Richard J.; Potter, Michael; Lind, Minna; Story, Scott R.
This paper presents results from the first phase of a research program designed to examine the leachability of radium-226 from barium-radium sulphate sludges. Batch leaching tests were performed. Results showed that liquid:solid contact time was relatively unimportant; radium in the sludge was stable in the presence of deionized water with a slight increase in the amount leached per gram of sludge occurring at higher liquid:solid ratios. Not unexpectedly, low and high values of leachant pH increased radium leaching. Both monovalent and divalent salt solutions also increased leaching; however, dissolved radium-226 activity levels in the leachate decreased as leachant molarity increased. For divalent salts this can be explained by the common ion effect; for monovalent salts it is opposite to results expected from solubility considerations. The interpretation of all results is complicated by the fact that in most tests, the amount of radium-226 present in the leachate was lower than the calculated contribution from the mother liquour present with the sludge. This apparent ability of the sludge to absorb radium from solution may be related to dissolution and reprecipitation of the sludge during the leaching tests.
Huck, P.M.; Anderson, B.
Acceleration of osteogenesis by using barium titanate piezoelectric ceramic as an implant material
As bone has piezoelectric properties, it is expected that activity of bone cells and bone formation can be accelerated by applying piezoelectric ceramics to implants. Since lead ions, included in ordinary piezoelectric ceramics, are harmful, a barium titanate (BTO) ceramic, which is a lead-free piezoelectric ceramic, was used in this study. The purpose of this study was to investigate piezoelectric effects of surface charge of BTO on cell differentiation under dynamic loading in vitro. Rat bone marrow cells seeded on surfaces of BTO ceramics were cultured in culture medium supplemented with dexamethasone, ?-glycerophosphate and ascorbic acid while a dynamic load was applied to the BTO ceramics. After 10 days of cultivation, the cell layer and synthesized matrix on the BTO surfaces were scraped off, and then DNA content, alkaline phosphtase (ALP) activity and calcium content were measured, to evaluate osteogenic differentiation. ALP activity on the charged BTO surface was slightly higher than that on the non-charged BTO surface. The amount of calcium on the charged BTO surface was also higher than that on the non-charged BTO surface. These results showed that the electric charged BTO surface accelerated osteogenesis.
Furuya, K.; Morita, Y.; Tanaka, K.; Katayama, T.; Nakamachi, E.
Mononuclear barium diketonate polyamine adducts. Synthesis, structures, and use in MOCVD of barium titanate
Mononuclear barium {beta}-diketonate Lewis base adducts have been synthesized by reaction of Ba(thd){sub 2} (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) with polyamines 1,1,4,7,7-pentamethyldiethylenetriamine (pmdt) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (hmtt). The adducts [Ba(thd){sub 2}(pmdt)] (I) and [Ba(thd){sub 2}(hmtt)] (II) have been characterized by NMR spectroscopy, elemental analyses and single-crystal X-ray diffraction. Compound I crystallizes in the space group P2{sub 1}/c with a = 10.577(3) {angstrom}, b = 23.547(7) {angstrom}, c = 15.963(5) {angstrom}, {beta} = 105.21(2){degrees}, and Z = 4. Compound II crystallizes in the space group P2{sub 1}/c with a = 10.833(6) {angstrom}, b = 20.442(12) {angstrom}, c = 19.404(9) {angstrom}, {beta} = 104.35(4){degrees}, and Z = 4. The adducts are seven- and eight-coordinate, respectively, with all nitrogen atoms of the polyamine bound to a single barium center. Compound I has been used for thin-film growth of BaTiO{sub 3} which has revealed that, compared to Ba(thd){sub 2}(tetraglyme), the polyamine adduct allows a larger temperature window for effective vapor transport. 10 refs., 2 figs., 2 tabs.
Gardiner, R.A.; Gordon, D.C.; Stauf, G.T.; Vaartstra, B.A. [Advanced Technology Materials Inc., Danbury, CT (United States); Ostrander, R.L.; Rheingold, A.L. [Univ. of Delaware, Newark, DE (United States)
59 FR- Barium Sulfate; Toxic Chemical Release Reporting; Community Right-To-Know
...members of the section 313 metal compound categories...toxicity, neurotoxicity, gene mutations, or chronic toxicity...barium is not a heavy metal (page 32626, column...barium is not a heavy metal, and it is not...
21 CFR 201.304 - Tannic acid and barium enema preparations.
...widespread practice for tannic acid to be added to barium enemas...X-ray pictures. Tannic acid is capable of causing diminished...medical literature reports a number of deaths associated with the addition of tannic acid to barium enemas....
Barium partitioning in coccoliths of Emiliania huxleyi
The coccolithophore Emiliania huxleyi was grown in seawater under different Ba concentrations. The relationship of coccolith Ba/Ca ratio and seawater Ba/Ca ratio was found to be linear. The linear regression yields the apparent Ba exchange coefficient of 0.10. Our data support a recently proposed generic model (Langer G., Gussone N., Nehrke G., Riebesell U., Eisenhauer A., Kuhnert H., Rost B., Trimborn S., and Thoms S. (2006) Coccolith strontium to calcium ratios in Emiliania huxleyi: the dependence on seawater strontium and calcium concentrations. Limnol. Oceanogr.51, 310-320.) developed for explaining apparent exchange coefficients of metabolically inert divalent trace metals, such as Sr, in E. huxleyi. This model represents the first approach combining cell physiological processes and data from inorganic precipitation experiments, which quantitatively explains coccolith apparent Sr and Ba exchange coefficients.
Langer, Gerald; Nehrke, Gernot; Thoms, Silke; Stoll, Heather
Creating unstable velocity-space distributions with barium injections
Large Debye lengths relative to detector dimensions and the absence of confining walls makes space an attractive laboratory for studying fundamental theories of plasma instabilities. However, natural space plasmas are rarely found displaced from equilibrium enough to permit isolation and diagnosis of the controlling parameters and driving conditions. Furthermore, any plasma or field response to the departure from equilibrium can be masked by noise in the natural system. Active experiments provide a technique for addressing the chicken or egg dilemma. Early thermite barium releases were generally conducted at low altitudes from sounding rockets to trace electric fields passively or to study configuration-space instabilities. One can also study velocity-space instabilities with barium releases. Neutral barium vapor releases wherein a typical speed greatly exceeds the thermal speed can be used to produce barium ion velocity-space distributions that should be subject to a number of microinstabilities. We examine the ion velocity-space distributions resulting from barium injections from orbiting spacecraft and shaped-charges.
Pongratz, M.B.
Acceleration of barium ions near 8000 km above an aurora
A barium shaped charge, named Limerick, was released from a rocket launched from Poker Flat Research Range, Alaska, on March 30, 1982, at 1033 UT. The release took place in a small auroral breakup. The jet of ionized barium reached an altitude of 8100 km 14.5 min after release, indicating that there were no parallel electric fields below this altitude. At 8100 km the jet appeared to stop. Analysis shows that the barium at this altitude was effectively removed from the tip. It is concluded that the barium was actually accelerated upward, resulting in a large decrease in the line-of-sight density and hence the optical intensity. The parallel electric potential in the acceleration region must have been greater than 1 kV over an altitude interval of less than 200 km. The acceleration region, although presumably auroral in origin, did not seem to be related to individual auroral structures, but appeared to be a large-scale horizontal structure. The perpendicular electric field below, as deduced from the drift of the barium, was temporally and spatially very uniform and showed no variation related to individual auroral structures passing through.
Stenbaek-Nielsen, H. C.; Hallinan, T. J.; Wescott, E. M.; Foeppl, H.
Advances in aluminum anodizing
White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.
Dale, K. H.
Corrosion Inhibitors for Aluminum.
Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)
Muller, Bodo
Filiform Corrosion of Aluminum.
Generally, filiform corrosion occurs on aluminum when it is coated with an organic coating and the system is exposed to relatively high humidities. This type of corrosion is initiated or activated by the presence of electrolytes, particularly chloride, an...
W. H. Slabaugh W. Dejager S. E. Hoover L. L. Hutchinson
Aluminum Permanganate Battery.
A battery is provided comprising an aluminum anode, an aqueous solution of permanganate as the cathodic species and a second electrode capable of reducing permanganate. Such a battery system is characterized by its high energy density and low polarization...
C. Marsh S. L. Licht
Minerals Yearbook, 1990. Calcium and Calcium Compounds.
The U.S. Bureau of Mines publishes reports for a variety of calcium-containing minerals and compounds because of their commercial significance and contribution to the quality of human life. The 'Calcium and Calcium Compounds Annual Report' includes calciu...
Minerals Yearbook, 1989. Calcium and Calcium Compounds.
The Bureau of Mines publishes reports for a variety of calcium-containing minerals and compounds because of their commercial significance and contribution to the quality of human life. Calcium fluoride is sold as fluorspar; calcium sulfate as gypsum or an...
Phenotypic and Behavioral Defects Caused by Barium Exposure in Nematode Caenorhabditis elegans
To examine the possible phenotypic defects from barium exposure, a model organism, Caenorhabditis elegans, was chosen to analyze the multiple toxicities in barium-exposed animals. Endpoints of life span, body size, brood size,\\u000a generation time, head thrash, and body bend were selected for the assessment of barium toxicity. High concentrations (75Ā?M\\u000a and 200Ā?M) of barium exposure caused severe life-span defects. Body
D.-Y. Wang; Y. Wang
Barium Aspiration in an Infant: A Case Report and Review of Management
We describe a case of bilateral inhalation of barium in an infant following a barium swallow for investigation of dusky spells associated with feeds. A bronchoscopy subsequently revealed the presence of a mid-tracheal tracheo-esophageal cleft. To date, little has been reported on barium aspiration in children and there is no consensus for management. We review the literature on barium aspiration, its consequences, and make recommendations for management.
Jackson, M.; Kapur, N.; Goyal, V.; Choo, K.; Sarikwal, A.; Masters, I. B.; Isles, Alan F.
Aluminum-air battery
Aluminum alloyed with small amounts (less than 0.1%) of In, Ga, and Tl in an aluminum air battery with 2M NaCl as the electrolyte is reported. The tested laboratory model of the battery with a total weight of about 500 g operated at a total current of 8 A (j = 30 mA\\/cu cm) and a voltage of about 1
A. R. Despic; D. Drazic; S. Zecevic
Light weight aluminum optics
Light weight mirror blanks were fabricated by dip-brazing a core of low mass aluminum foam material to thin face sheets of solid aluminum. The blanks weigh 40% of an equivalent size solid mirror and were diamond turned to provide reflective surfaces. Optical interferometry was used to assess their dimensional stability over 7 months. No changes in flatness are observed (to the sensitivity of the measurements of a half wavelength of red light).
Catura, R. C.; Vieira, J. R.
Radiation dose in mass screening for gastric cancer with high-concentration barium sulfate compared with moderate-concentration barium sulfate.
Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer. PMID:19623859
Yamamoto, K; Azuma, M; Kuroda, C; Kubo, T; Yabunaka, K; Yamazaki, H; Katsuda, T; Takeda, Y
49 CFR 173.182 - Barium azide-50 percent or more water wet.
...2009-10-01 2009-10-01 false Barium azide-50 percent or more water wet. 173.182...Than Class 1 and Class 7 ┬¦ 173.182 Barium azideŌ50 percent or more water wet. Barium azideŌ50 percent or more water wet, must be...
...2010-10-01 2010-10-01 false Barium azide-50 percent or more water wet. 173.182...Than Class 1 and Class 7 ┬¦ 173.182 Barium azideŌ50 percent or more water wet. Barium azideŌ50 percent or more water wet, must be...
Discrete barite particles and barium as tracers of paleoproductivity in South Atlantic sediments
Geochemical analyses as well as X ray diffraction measurements were carried out on five sediment cores from the eastern Angola Basin and the equatorial divergence of the South Atlantic. Barite concentrations were calculated from total barium concentrations by subtracting the estimated barium background supplied by ``nonbarite'' barium carriers. Barite concentrations assessed by this geochemical method show a good correspondence to
Franz Gingele; Andreas Dahmke
The biological production of marine suspended barite and the barium cycle in the Western Mediterranean Sea
Suspended particulate barium was measured in the Western Mediterranean along 4 profiles sampled during the PHYCEMED 1 cruise in 1981. The non-terrigenous fraction of particulate barium (i.e. excess Ba; Baxs) can account for up to 96% of total barium. This fraction follows the barite settling and dissolution rate model we described earlier for the Atlantic Ocean, confirming barite as the
F. DEHAIRSI; C. E. Lambert; R. Chesselet; N. Risler
Atomic force microscopy studies of twins in yttrium-doped barium titanate
Barium titanate is the main constituent of PTC materials and their electric properties are sensitive to microstructure and defects, in atomic scale, that are significantly affected by processing parameters. The microstructure of barium titanate doped with yttrium was investigated using topographic images obtained by AFM in contact mode. The AFM images of barium titanate doped with yttrium showed the effect
Simoni Maria Gheno; Haroldo Lhou Hasegawa; Pedro Iris Paulin Filho
40 CFR 721.10010 - Barium manganese oxide (BaMnO3).
...2009-07-01 2009-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances ┬¦ 721.10010 Barium manganese oxide (BaMnO3 ). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...
...2010-07-01 2010-07-01 false Barium manganese oxide (BaMnO3). 721.10010...Chemical Substances ┬¦ 721.10010 Barium manganese oxide (BaMnO3). (a...The chemical substance identified as barium manganese oxide (BaMnO3 )...
Fluid seepage along the San Clemente Fault scarp: basin-wide impact on barium cycling
Material fluxes associated with fluid expulsion at cold seeps and their contribution to oceanographic budgets have not been accurately constrained. Here we present evidence that the barium released at cold seeps along the San Clemente Fault zone may significantly impact the geochemical budget of barium within the basin. Barium fluxes at seep localities on the fault scarp, measured with benthic
Marta E. Torres; James McManus; Chih-An Huh
Spectroscopy and dynamics of barium-doped helium nanodroplets
Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with respect to the gas phase. This has been attributed to the repulsive interaction of the excited atom with the helium at the Franck-Condon region. In contrast, for states with high principal quantum number the resonances are narrower and shifted towards lower energies. Photoelectron and ZEKE spectroscopy reveal that the redshift results from a lowering of the ionization threshold due to polarization of the helium by the barium ionic core. As a result of the repulsive interaction with the helium, excited barium atoms desorb from the surface of the droplets. Only when excited to the 6s6p 1P1 state, which reveals an attractive interaction with the helium, the atoms remain attached to the droplets.
Loginov, Evgeniy; Drabbels, Marcel
Solubilization of hardly soluble iron and aluminum phosphates by the fungus Aspergillus niger in the soil
Some Brazilian soils present high contents of hardly soluble iron and aluminum phosphates and a high capacity for fixation\\u000a of soluble phosphates. This study evaluated the ability of the fungus Aspergillus niger F111 isolated from soil to solubilize Fe and Al phosphates. Iron, aluminum or calcium phosphate were added to soil samples and\\u000a inoculated with the A. niger F111. Sugar-cane
C. B. Barroso; E. Nahas
Determination of micro amounts of iron, aluminum, and alkaline earth metals in silicon carbide
A colorimetric method for analysis of micro components in silicon carbide used as the raw material for varistors is described. The microcomponents analyzed included iron soluble in hydrochloric acid, iron, aluminum, calcium and magnesium. Samples were analyzed by the method, and the results for iron and aluminum agreed well with the N.B.S. standard values and the values obtained by the other company. The method can therefore be applied to the analysis of actual samples.
Hirata, H.; Arai, M.
Using trace metal-defined culture conditions, we measured the cellular barium concentration in cultures of the diatom Thalassiosira weissflogii. In cultures with low Fe concentration, at a typical surface seawater Ba concentration of 35 to 40 nmol/L, the cellular Ba was 0.5 ?mol/mol P (ś0.04 ?g/g dw), much below all previously published values for phytoplankton. When the Fe concentration in the growth medium was increased, the measured "cellular" Ba increased proportionally to the particulate Fe. Under conditions of ferric hydroxide precipitation, similar particulate Ba concentrations were measured in the absence and the presence of cells for a given concentration of particulate Fe. Thus, the bulk of the particulate Ba in such experiments was not truly intracellular but adsorbed on precipitated Fe hydroxides associated with the cell surface. A similar mechanism likely explains the high cellular Ba concentrations reported by previous investigators who utilized relatively high ratios of Fe to EDTA concentrations in the growth medium, resulting in Fe precipitation. On the basis of our results, it seems highly unlikely that intracellular uptake by living phytoplankton explains the vertical flux of Ba in oceanic waters. But the adsorption of Ba on Fe hydroxides that is seen in laboratory experiments must also occur in the oceans and contribute to Ba transport in the upper part of the water column. To be significant, however, such a mechanism would require that the particles that transport Ba out of the surface have a markedly lower Ba/Fe ratio than is measured in the average suspended material.
Sternberg, Erika; Tang, Degui; Ho, Tung-Yuan; Jeandel, Catherine; Morel, Franńois M. M.
Compact pulse forming line using barium titanate ceramic material.
Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008
Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A
Compact pulse forming line using barium titanate ceramic material
Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 ? load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.
Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.
Ionization and expansion of barium clouds in the ionosphere
A recently envelope 3D model is used here to study the motion of the barium clouds released in the ionosphere, including the ionization stage. The ionization and the expansion of the barium clouds and the interaction between the clouds and the background ions are investigated using three simulations: a cloud without a directional velocity, a cloud with an initial velocity of 5 km/s across the B field, and a cloud with initial velocity components of 2 km/s both along and across the B field.
Ma, T.-Z.; Schunk, R. W.
Barium bismuth oxides with ?-, ?-, and ?-Bi 2 O 3 structures
Three new barium bismuth oxides have been synthesized containing 2.15¢2.72 mol % BaO with the integer composition BaBi39O59.5, BaBi46O70, and BaBi40O61 and a monoclinic, cubic, and triclinic structure, respectively. These double oxides are, likely, derivatives of ?-, ?-, and\\u000a ?-Bi2O3 phases. The effects of the crucible material and surrounding atmosphere on the course of the synthesis of these new barium
L. A. Klinkova; V. I. Nikolaichik; N. V. Barkovskii; V. K. Fedotov
Calcium Depletion in Forest Soils of the Eastern US
This week's In the News focuses on calcium depletion in the forest soils of ten states in the Eastern US. Calcium depletion decreases the ability of trees to "ward off stresses such as temperature changes and insect defoliation". Scientists have noted that sugar maples and red spruce trees in ten different sites now have reduced resistance to "defoliation by insects and low winter temperatures". In a recent report, scientists Gregory Lawrence and Thomas Huntington of the US Geological Survey (USGS) claim that a cause of calcium depletion is acid rain. Lawrence and Huntington describe a mechanism whereby acid rain decreases calcium soil content: ". . . sulfuric and nitric acids from acid deposition . . . tend to remain in solution within the mineral soil where they lower the pH, thereby releasing aluminum to soil water and causing the leaching of calcium". In addition, timber harvesting may also contribute to the depletion of calcium in forest soils because, as trees are removed from the site, the calcium within them is removed as well. Due to the combined effects of acid rain and timber harvest, some areas have low calcium soil content and consequently low forest growth. The nine resources listed provide background information on acid rain and articles and research efforts on the relationship between calcium soil content and acid rain.
Nannapaneni, Sujani.
Occurrence of aluminum in chloride cells of Perla marginata (Plecoptera) after exposure to low pH and elevated aluminum concentration
As a consequence of acid depositions on poorly buffered catchments underlain by hard rocks, aluminum is mobilized and transported from terrestrial systems to the aquatic environment. Loss of fishes has been related to low pH and elevated aluminum concentrations in surface waters which present a low ionic content especially during acid stress such as snowmelt and heavy rainfalls. Among the causes of fish population decline in acid waters, aluminum is considered a toxic cofactor. Different studies have clearly shown that aluminum is accumulated in different organs such as kidneys, liver and gills. Research on fish has demonstrated that aluminum may be toxic, but the toxicity is markedly influenced by the pH, organic compounds and calcium content of the water. Field surveys have shown clearly that macroinvertebrates are also affected by surface-water acidification. However, little is know about the possible effects of aluminum on aquatic invertebrates and, particularly, on aquatic insects exposed to acidic conditions. Hall et al. have shown that the whole-body concentration of aluminum decreases in blackflies and mayflies transplated from neutral water to acid water. Similar results have been reported for Daphnia and chironomid. On the contrary, Ormerod et al. demonstrated the absence of relationship between water pH and insect aluminum concentrations. When aluminum occurs in aquatic insects, it has been shown that it is primarily adsorbed on the external surface and/or accumulates in gut contents. To our knowledge, the subcellular location as well as the toxicity of aluminum to acid-sensitive aquatic insects remains unclear and existing hypotheses are often based on research on fish. In this content the purpose of this study was to investigate the presence of aluminum at a subcellular level in the acid-sensitive species of stonefly, Perla marginata, after exposure to low pH and elevated aluminum concentrations. 18 refs., 1 fig., 1 tab.
Guerold, F.; Giamberini, L.; Pihan, J.C. [Universite de Metz (France); Tourmann, J.L.; Kaufmann, R. [Heinrich Heine Universitaet Duesseldorf (Germany)
Aluminum, parathyroid hormone, and osteomalacia
Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.
Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.
A case of recurrent renal aluminum hydroxide stone.
Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca). The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics. PMID:25013740
Cak?roglu, Basri; Dogan, Akif Nuri; Tas, Tuncay; Gozukucuk, Ramazan; Uyanik, Bekir Sami
A Case of Recurrent Renal Aluminum Hydroxide Stone
Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca). The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics.
Aluminum automotive space frames
Design of aluminum structures is to a new topic. Aircraft makers have successfully solved difficult structural problems with a high degree of understanding and reliability. Other transportation modes such as trucks, trailers, and railcars have faced structural problems with some emphasis on high- and low-cycle fatigue of welded aluminum structures. However, the automotive market places stringent engineering demands on materials and superimposes demanding cost constraints. A project was instituted at Reynolds Metals Co. to investigate the opportunities for the cost-effective application of aluminum to automotive spaceframes. Several areas were recognized as key to the success of this application. They were: equivalent or superior structural stiffness of the assembly to existing steel unibody and/or steel spaceframe vehicles; effective joining of spaceframe members; equivalent or superior crashworthiness of the assembly; weight savings; flexibility; and low-cost approach aimed at effective manufacturing. To gain experience with the key aspects in a practical environment, the experience of current builders of steel tube frame chassis was explored. These chassis are typically used in low-volume vehicles requiring torsional stiffness, excellent crashworthiness, and exterior body-style flexibility. A model was developed using finite element methods that accurately predicts mass and stiffness of frames. An effective aluminum space frame was generated which was 7.5% stiffer and more than 20% lighter than the steel frame, with stresses kept below the fatigue limit for aluminum welds.
Aluminum Reclamation by Acidic Extraction of Aluminum-Anodizing Sludges.
Extraction of aluminum-anodizing sludges with sulfuric acid was examined to determine the potential for production of commercial-strength solutions of aluminum sulfate, that is liquid alum. The research established kinetic and stoichiometric relationships...
F. M. Saunders R. C. Shaw
Extraction of aluminum-anodizing sludges with sulfuric acid was examined to determine the potential for production of commercial-strength solutions of aluminum sulfate, that is liquid alum. The research established kinetic and stoichiometric relationships and evaluates product qu...
Synthesis and Properties of Barium Titanate Nanocomposites.
Electrical properties of BaTiO_3 /liquid composites were investigated. The main thesis objectives were as follows: (1) synthesis of high purity, nanometer-sized BaTiO_3; (2) characterization of the room temperature BaTiO _3 phase as a function of temperature; (3) to evaluate the possibilities of using BaTiO_3 in electrorheological (ER) fluids with both AC and DC fields; and (4) to determine the effects of AC and DC fields on agglomerate fibril formation by using optical microscopy. Powders produced by coprecipitation methods (TAM HPB) and hydrothermal techniques were evaluated in this research. Hydrothermal synthesis in the barium hydroxide octahydrate (BHO) and titanium isopropoxide (TI) system was extensively examined. It was determined that feedstock pH 12 was required for hydrothermal synthesis to ensure proper crystallinity of the resultant powder. The specific surface area increased linearly from 6.7m^2 /g to 14.3m^2/g with increased feedstock concentrations from 0.15M to 1.0M. This change in feedstock concentration also resulted in a drastic change in particle morphology. Particles produced at low feedstock concentrations were large, textured aggregates (5.0 ?m) produced from small crystallites (0.1 ?m). Particles produced at high feedstock concentrations (designated as BTH8) possessed a hexagonal platelet structure which grew slowly along < 111> and rapidly along < 211>. Particle size effects on the room temperature phase were successfully evaluated, as a function of temperature, with X-ray diffraction and dielectric measurements. It was found that the particle possessed the tetragonal phase at room temperature for 700A particles. The phase transition from cubic to tetragonal appeared at 120^ circC for this particle size. TAM HPB and BTH8 both showed an ER response (AC and DC fields) when suspended in silicone oil. The TAM HPB suspension showed a greater ER effect due to the larger particle size. All suspensions were frequency dependent with an optimal range of 20-100Hz. The viscosity of the BTH8 suspension dropped off rapidly above an applied field DC of 6.25kV/cm due to turbulent overturn.
Miller, David Vernon
Abundances of 12 metal-rich barium stars (Pereira+, 2011)
The table contains equivalent width measurements for each individual line of the adopted line list, and the corresponding line parameters. The data analysed consist of firstname.lastname@example.com spectra of 12 barium stars. The resolution is of about R=45 000, which covers the range from 4500 to 9500┼, which include all the lines analysed. (3 data files).
Pereira, C. B.; Sales Silva, J. V.; Chavero, C.; Roig, F.; Jilinkski, E.
The overall objective of this study was to examine by epidemiologic and supportive laboratory studies, the human health effects associated with ingestion of barium in drinking water exceeding the U.S. drinking water standard of 1.0 mg/l. The incidence of cardiovascular mortality ...
Synthesis and surface properties of submicron barium sulfate particles
Barium sulfate particles were synthesized in the presence of EDTA at room temperature. X-ray diffractometry (XRD), Fourier transform infrared resonance (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of BaSO 4 particles. The effect of the preparation parameters on the particle size distribution and morphology was investigated. The conditional formation constants of Ba-EDTA at different pH values were calculated. The results show that the size and morphology of BaSO 4 particles can be effectively controlled by adding EDTA in the precipitation process. Among all the operation conditions, the pH value has significant effect on the particle size. The obtained barium sulfate particles are spherical and well dispersed at pH = 9-10. Zeta potentials of BaSO 4 were measured at different pH. The isoelectric point (IEP) of barium sulfate colloid appears at pH 6.92. The model of the solid-solution interface at a particle of BaSO 4 was presented. The FTIR result indicates that the surface of the prepared BaSO 4 absorbs the functional groups of EDTA, which lower the IEP of the barium sulfate particles.
Zhang, Ming; Zhang, Bao; Li, Xinhai; Yin, Zhoulan; Guo, Xueyi
The Integrated Risk Information System (IRIS) is a database of EPA's consensus opinion of the human health effects that may result from exposure to various substances found in the environment. A Toxicological Review and IRIS Summary were prepared for barium and compounds in 1998 ...
Emission Fluctuations of Tungsten-Based Barium Dispenser Cathodes
Emission fluctuations in five different types of tungsten-based barium dispenser cathodes have been measured as functions of both frequency and current density. Two of the cathodes were of the L variety and the remainder of the ``impregnated'' variety. The L cathode spectra show that the emission fluctuations are caused by fluctuations in the number of adsorbed atoms on the tungsten
I. Brodie
Effects of energetic ions on barium strontium titanate crystals
The effects of energetic ions on barium strontium titanate (BST) single crystals have been studied using low-energy He and high-energy Si ions. This investigation indicates that energetic ions significantly change the ferroelectric properties of BST single crystals. While He ion causes sharp increase in dielectric constant, Curie temperature (Tc) and spontaneous polarization (Ps), the Si ions cause slight change in
R. Varatharajan; P. Jayavel; J. Kumar; R. Jayavel; K. Asokan
Measurement of carbon contamination in barium strontium titanate films
Ferroelectric films are being developed for use in DRAMs. The films are often manufactured using spin-on techniques making contamination with residual carbon inevitable. The concentration of carbon is rarely known and its effect not understood. This paper describes the analysis of barium strontium titanate (BST) films for carbon content using both Mass and Energy Dispersive Recoil Spectrometry (RS) with 77
Warren B. Stannard; Peter N. Johnston; James F. Scott; Ian F. Bubb; R. Walker; David D. Cohen; Nick Dytlewski; Jarrod W. Martin
Barium strontium titanate powders prepared by spray pyrolysis
Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders
G. Brankovi?; Z. Brankovi?; M. S. G¾es; C. O. Paiva-Santos; M. Cilense; J. A. Varela; E. Longo
The primary objective of this study was to determine the applicability of weak acid exchange resin in the hydrogen form for removal of hardness, barium and radium from groundwater. Weak acid resin in the hydrogen form eliminates the addition of sodium to drinking water. The capac...
Water treatment plants at nine locations (10 plants) in Illinois and Iowa were studied to determine the characteristics and disposal practices for the sludge, brine, and backwash water containing radium (Ra) and/or barium (Ba). The treatment processes in these ten plants include ...
Dynamics of a barium release in the magnetospheric tail
The late time behavior of the May 13, 1985 magnetotail barium cloud is examined. The bulk dynamics of the cloud are studied based on triangulated data and data from Fabry-Perot Doppler velocity measurements. The changes in cloud morphology in relation to the in situ measurements made by the Ion Release Module satellite are discussed.
Mende, S. B.; Swenson, G. R.; Geller, S. P.; Doolittle, J. H.; Haerendel, G.
Optical, mechanical, and thermal properties of barium borate
We report measurements of all the material constants necessary to fully characterize barium borate as a nonlinear optical material. All data was taken on crystals supplied by Professor Chuangtien Chen, Fuzhou, PeopleÆs Republic of China. We have determined the crystal structure, the optical absorption, the refractive indices from the UV to the near IR, the thermo-optic coefficients, the nonlinear optical
D. Eimerl; L. Davis; S. Velsko; E. K. Graham; A. Zalkin
Aluminum Hydroxide and Magnesium Hydroxide
Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They may be used to ... with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription.This medication ...
Rabbit Neurobehavioral Toxicity from Aluminum.
A model for the production of neurobehavioral toxicity induced by systemic aluminum exposure was developed. Nictitating membrane extension conditioning was used to assess the influence of the aluminum treatment on learning (acquisition and conditioned res...
R. A. Yokel
Chrome - Free Aluminum Coating System.
This slide presentation concerns the program to qualify a chrome free coating for aluminum. The program was required due to findings by OSHA and EPA, that hexavalent chromium, used to mitigate corrosion in aerospace aluminum alloys, poses hazards for pers...
J. D. Gugel J. H. Bailey
Recycled Aluminum Ornaments
This lesson plan from ATEEC will explain the principles of recycling. The activity would be most appropriate for technology studies or high school science classes. In all, it would require 2-5 hours of class time to complete. The purpose of the lesson is to demonstrate how aluminum is recycled. This laboratory activity does require some special equipment including a heat source capable of melting aluminum and an outdoor work area. Extension activities are also provided. The lesson plan is available for download as a PDF; users must create a free, quick login with ATEEC to access the materials.
Wishart, Ray
Regeneration of aluminum hydride
The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.
Graetz, Jason Allan (Mastic, NY); Reilly, James J. (Bellport, NY)
The objective of this report is to document laboratory testing of blended calcium aluminate - calcium hemihydrate grouts for P-Reactor vessel in-situ decommissioning. Blended calcium aluminate - calcium hemihydrate cement-based grout was identified as candidate material for filling (physically stabilizing) the 105-P Reactor vessel (RV) because it is less alkaline than portland cement-based grout which has a pH greater than 12.4. In addition, blended calcium aluminate - calcium hemihydrate cement compositions can be formulated such that the primary cementitious phase is a stable crystalline material. A less alkaline material (pH {<=} 10.5) was desired to address a potential materials compatibility issue caused by corrosion of aluminum metal in highly alkaline environments such as that encountered in portland cement grouts [Wiersma, 2009a and b, Wiersma, 2010, and Serrato and Langton, 2010]. Information concerning access points into the P-Reactor vessel and amount of aluminum metal in the vessel is provided elsewhere [Griffin, 2010, Stefanko, 2009 and Wiersma, 2009 and 2010, Bobbitt, 2010, respectively]. Radiolysis calculations are also provided in a separate document [Reyes-Jimenez, 2010].
Langton, C.; Stefanko, D.
Crystal structure of complex natural aluminum magnesium calcium iron oxide
The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) ┼, b = 17.1823(4) ┼, c = 23.5718(5) ┼, ? = 90░, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with | F| > 7?( F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula ( Z = 4) is Ca2Mg{2/IV}Fe{2/(2+)IV}[Al{14/VI}O31(OH)][Al{2/IV}O][AlIV]ALIV(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe2+ tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.
Rastsvetaeva, R. K.; Aksenov, S. M.; Verin, I. A.
Membrane Purification Cell for Aluminum Recycling
Recycling mixed aluminum scrap usually requires adding primary aluminum to the scrap stream as a diluent to reduce the concentration of non-aluminum constituents used in aluminum alloys. Since primary aluminum production requires approximately 10 times more energy than melting scrap, the bulk of the energy and carbon dioxide emissions for recycling are associated with using primary aluminum as a diluent.
David DeYoung; James Wiswall; Cong Wang
Reclamation of Aluminum Finishing Sludges.
The research study of the reclamation of aluminum-anodizing sludges was conducted in two sequential phases focused on enhanced dewatering of aluminum-anodizing sludges to produce commercial-strength solutions of aluminum sulfate, i.e., liquid alum. The us...
F. M. Saunders
Deformation and Imperfections in Aluminum.
The occurrence of twinning in aluminum and the part played by twinning in the plastic deformation of aluminum has not been adequately interpreted. The structure of aluminum has been determined only by the DeBye-Scherrer powder method which does not reveal...
R. H. Randall
Electrically conductive anodized aluminum coatings
A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.
Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)
The research study of the reclamation of aluminum-anodizing sludges was conducted in two sequential phases focused on enhanced dewatering of aluminum-anodizing sludges to produce commercial-strength solutions of aluminum sulfate, i.e., liquid alum. The use of high-pressure (14 to...
Ca(2+) released from calcium alginate gels can promote inflammatory responses in vitro and in vivo.
In general, alginate hydrogels are considered to be biologically inert and are commonly used for biomedical purposes that require minimum inflammation. However, Ca(2+), which is commonly used to crosslink alginate, is a critical second messenger in immune cell signaling, and little has been done to understand its effect on immune cell fate when delivered as a component of alginate gels. We found that dendritic cells (DCs) encapsulated in Ca(2+)-crosslinked alginate (calcium alginate) secreted at least fivefold more of the inflammatory cytokine IL-1? when compared to DCs encapsulated in agarose and collagen gels, as well as DCs plated on tissue-culture polystyrene (TCPS). Plating cells on TCPS with the alginate polymer could not reproduce these results, whereas culturing DCs on TCPS with increasing concentrations of Ca(2+) increased IL-1?, MHC class II and CD86 expression in a dose-dependent manner. In agreement with these findings, calcium alginate gels induced greater maturation of encapsulated DCs compared to barium alginate gels. When injected subcutaneously in mice, calcium alginate gels significantly upregulated IL-1? secretion from surrounding tissue relative to barium alginate gels, and similarly, the inflammatory effects of LPS were enhanced when it was delivered from calcium alginate gels rather than barium alginate gels. These results confirm that the Ca(2+) used to crosslink alginate gels can be immunostimulatory and suggest that it is important to take into account Ca(2+)'s bioactive effects on all exposed cells (both immune and non-immune) when using calcium alginate gels for biomedical purposes. This work may strongly impact the way people use alginate gels in the future as well as provide insights into past work utilizing alginate gels. PMID:23938198
Chan, Gail; Mooney, David J
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY
In Situ Emission Microscopy of Scandium\\/Scandium-Oxide and Barium\\/Barium-Oxide Thin Films on Tungsten
The effect of a thin Sc\\/Sc-oxide base layer on Ba\\/Ba-oxide electron emission, surface diffusion, adsorption, and desorption on W is studied using photoelectron emission microscopy and thermionic emission microscopy. A barium-on-scandium structure enhances both photo- and thermionic electron emission.
Joel M. Vaughn; Keith D. Jamison; Martin E. Kordesch
Aluminum Sulfate 18 Hydrate
A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.
Young, Jay A.
Aluminum battery alloys
Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.
Thompson, D.S.; Scott, D.H.
Hugoniot of 5083 Aluminum.
The Hugoniot of 5083H131 aluminum has been experimentally determined in the pressure range from 161 to 472 kilobars. Over this pressure range the shock velocity-particle velocity relationship was found to be linear. The optical and electrical techniques u...
A. Melani G. Hauver
Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.
Thompson, David S. (Richmond, VA); Scott, Darwin H. (Mechanicsville, VA)
Stratospheric aluminum oxide.
Balloons and U-2 aircraft were used to collect micrometer-sized strato-spheric aerosols. It was discovered that for the past 6 years at least, aluminum oxide spheres have been the major stratospheric particulate in the size range 3 to 8 micrometers. The most probable source of the spheres is the exhaust from solid-fuel rockets. PMID:17737717
Brownlee, D E; Ferry, G V; Tomandl, D
Experiments on Annealed Aluminum.
This investigation is a study of the quasi-static stress-strain relation for the case of biaxial stress in annealed commercially pure aluminum, and its implications with respect to the speed of propagation of disturbances caused by incremental stresses. T...
M. J. Kenig
Aluminum powder applications
Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the
Pitting corrosion of aluminum
This review describes the experiments performed during the last few decades which enhance knowledge of the pitting of aluminum. Specifically, metastable and stable pits, pit chemistry and the effect of intermetallics on pitting are discussed. The properties of metastable alloys and inhibition of Al are also discussed.
Z Szklarska-Smialowska
Aluminum Corrosion and Turbidity
Aluminum corrosion and turbidity formation in reactors correlate with fuel sheath temperature. To further substantiate this correlation, discharged fuel elements from R-3, P-2 and K-2 cycles were examined for extent of corrosion and evidence of breaking off of the oxide film. This report discusses this study.
Longtin, F.B.
Aluminum Coatings for Steel
Aluminum coated steel possesses excellent oxidation and corrosion resistance in sulfur and marine: environments and can substitute for expensive alloy of steels. Hot dip aluminizing (HAD) and pack cementation calorizing (CAL) are dealt with in detail. IN HDA coats, some alloying action takes place, when the substrate is dipped in molten Al at 973 K for 1-2 minutes. The coat
Aruna Bahadur
Advanced Cast Aluminum Alloys.
A recent advancement in cast aluminum alloys has demonstrated that complex shapes can be cast from a microalloyed Al-Cu alloy in dry sand molds with chills and that these castings can be heat treated to produce mechanical and physical properties nearly co...
A. P. Druschitz J. Griffin
Contribution of calcium oxalate to soil-exchangeable calcium
Acid deposition and repeated biomass harvest have decreased soil calcium (Ca) availability in many temperate forests worldwide, yet existing methods for assessing available soil Ca do not fully characterize soil Ca forms. To account for discrepancies in ecosystem Ca budgets, it has been hypothesized that the highly insoluble biomineral Ca oxalate might represent an additional soil Ca pool that is not detected in standard measures of soil-exchangeable Ca. We asked whether several standard method extractants for soil-exchangeable Ca could also access Ca held in Ca oxalate crystals using spike recovery tests in both pure solutions and soil extractions. In solutions of the extractants ammonium chloride, ammonium acetate, and barium chloride, we observed 2% to 104% dissolution of Ca oxalate crystals, with dissolution increasing with both solution molarity and ionic potential of cation extractant. In spike recovery tests using a low-Ca soil, we estimate that 1 M ammonium acetate extraction dissolved sufficient Ca oxalate to contribute an additional 52% to standard measurements of soil-exchangeable Ca. However, in a high-Ca soil, the amount of Ca oxalate spike that would dissolve in 1 M ammonium acetate extraction was difficult to detect against the large pool of exchangeable Ca. We conclude that Ca oxalate can contribute substantially to standard estimates of soil-exchangeable Ca in acid forest soils with low soil-exchangeable Ca. Consequently, measures of exchangeable Ca are unlikely to fully resolve discrepancies in ecosystem Ca mass balance unless the contribution of Ca oxalate to exchangeable Ca is also assessed.
Dauer, Jenny M.; Perakis, Steven S.
Barium toxicity and the role of the potassium inward rectifier current.
Abstract Introduction. Barium is a stable divalent earth metal and highly toxic upon acute and chronic exposure. Barium is present in many products and involved in a number of industrial processes. Barium targets the potassium inward rectifier channels (IRCs) of the KCNJx gene family. Extracellular barium enters and strongly binds the potassium selectivity filter region resulting in blockade of the potassium conducting pore. IRCs are involved in numerous physiological processes of the human body and the most barium sensitive IRCs are highly expressed in all muscle types. Objective. Our purpose was correlate to the clinical outcome of acute barium poisoning in man to current knowledge on IRC function. Methodology. The primary literature search was performed using Medline, Scopus and Google Scholar using search terms "barium AND poisoning"; "barium AND intoxication"; "barium AND case report" and retrieved publications from 1945 through 2012. Additional case reports were retrieved based on the reference lists of the primary hits. Duplicate publications, or publications presenting identical cases were omitted. A total of 39 case reports on acute barium poisoning containing 226 human subjects were identified for review. Results. BaCO3 was the most frequent source and food the most frequent mode of poisoning. Patients suffered from gastrointestinal (vomiting, diarrhea), cardiovascular (arrhythmias, hypertension), neuromuscular (abnormal reflexes, paralysis), respiratory (respiratory arrest/failure) and metabolic (hypokalemia) symptoms. Severe hypokalemia (< 2.5 mM) was observed from barium serum concentrations greater than or equal to 0.0025 mM. Review of the ECG outcomes demonstrated ventricular extrasystoles, ST changes and profound U-waves to be associated strongly with poisoning. Most common treatment modalities were gastric lavage, oral sulfates, potassium i.v. and cardiorespiratory support. 27 patients (12%) died from barium poisoning. Conclusions. Barium is a potent, non-specific inhibitor of the potassium IRC current and affects all types of muscle at micromolar concentrations. Gastrointestinal symptoms frequently occur early in the course of barium poisoning. Hypokalemia resulting from an intracellular shift of potassium and the direct effect of barium at the potassium channels explain the cardiac arrhythmias and muscle weakness which commonly occur in barium poisoning. Treatment of barium poisoning is mainly supportive. Orally administered sulfate salts to form insoluble barium sulfate in the intestinal tract and potassium supplementation have potential but unproven benefit. PMID:24905573
Bhoelan, B S; Stevering, C H; van der Boog, A T J; van der Heyden, M A G
Transient Inclusion Evolution During Modification of Alumina Inclusions by Calcium in Liquid Steel: Part I. Background, Experimental Techniques and Analysis Methods
In aluminum-killed steels, modification of solid alumina inclusions is often carried out by calcium treatment, converting the alumina to liquid calcium aluminates. When calcium treatment is performed, calcium can either react with sulfur in the melt or with solid alumina. Calcium sulfide inclusions are solid at steel casting temperatures and thus would be detrimental to castability if they remained in the steel after calcium treatment. The aim was to study the transient evolution of inclusions after calcium treatment, testing the hypothesis that calcium sulfide may form as an intermediate reaction product, which can subsequently react with alumina to form modified calcium aluminates. The first part gives the project background and describes the experimental and quantification techniques adopted, including the effect of sampler size in laboratory melts. Results of the formation of intermediate calcium reaction products in laboratory and industrial heats are presented in the second part.
Verma, Neerav; Pistorius, Petrus C.; Fruehan, Richard J.; Potter, Michael; Lind, Minna; Story, Scott
Straczekite, a new calcium barium potassium vanadate mineral from Wilson Springs, Arkansas.
Straczekite occurs as a rare secondary mineral in fibrous seams, along with other V minerals (A.M. 64-713), in ore from the vanadium mine in Wilson Springs (formerly Potash Sulfur Springs), Garland County, Arkansas. It forms soft, thin laths of dark greenish black crystals up to 0.5 mm in length. Indexed XRD data are tabulated; strongest lines 3.486(100), 10.449(50), 1.8306(50), 1.9437(15) A; a 11.679, b 3.6608, c 10.636 A, beta 100.53o; space group C2/m, C2 or Cm. Chemical analysis gave V2O5 66.4, V2O4 15.3, Fe2O3 0.9, Na2O 0.4, K2O 1.8, CaO 2.5, BaO 5.5, H2O 7.2, = 100.0, leading to the formula (Ca0.39Ba0.31K0.33Na0.11)- 196(V4+1.59V5+6.31Fe3+0.10)O20.02(H2O)2.9; Dcalc. 3.21 g/cm3. A possible layer structure is discussed. The name is for J. A. Straczek, Chief Geologist at Union Carbide Corp.-R.A.H.
Evans, Jr, H. T.; Nord, G.; Marinenko, J.; Milton, C.
Voltage dependence of two inward currents carried by calcium and barium in the ciliate Stylonychia mytilus.
Two voltage-dependent inward currents in the fresh-water hypotrichous ciliate Stylonychia mytilus have been investigated, using two intracellular micro-electrodes, when either Ca ions or Ba ions are the charge carriers. In cells bathed in Ca-free Ba solution the two inward currents, named current I and current II, could be identified and studied in the absence of outward currents. The two inward currents could also be separated by addition of the plant lectin concanavalin A (0.5 microgram/ml) to the external medium, which resulted in the selective inhibition of current I. When the holding potential was set at values between -45 and -65 mV (normal resting potential is -50 mV), current I was shifted parallel to the holding potential along the voltage axis. This shift was 7.6 mV per 10 mV change in holding potential. The amplitude and voltage relationship of current II was not affected by these changes in the holding potential. The amplitude of current I in Ba solution was maximal when the membrane potential was held at -55 mV; it decreased with higher and lower holding potentials. The rate of activation of current I remained virtually unaffected at holding potentials between -45 and -60 mV, and was somewhat reduced at a holding potential of -65 mV. When the extracellular Ca concentration was varied between 0.1 and 5.0 mM, or when the cells were loaded with EGTA to reduce the intracellular level of ionized Ca, the resting membrane potential and the voltage relationships of both current I and II and of the outward current were shifted along the voltage axis according to the expected changes in membrane surface potential. Double-pulse experiments with varying interval potentials suggested voltage-dependent inactivation of current I and Ca-dependent inactivation of current II. Pre-hyperpolarizing steps of only 1 mV amplitude and 30 ms duration could result in the activation of current I, indicating that the activation voltage of current I closely followed the actual membrane potential. Hence, the same voltage steps elicited similar current I amplitudes with holding potentials between -45 and -60 mV. The results indicate that current II displays voltage properties described for Ca channels in other ciliates and many multicellular preparations, while current I shows an unusual voltage behaviour, which might be regarded as an 'adaptive type of excitation'.(ABSTRACT TRUNCATED AT 400 WORDS)
Deitmer, J W
Two voltage-dependent inward currents in the fresh-water hypotrichous ciliate Stylonychia mytilus have been investigated, using two intracellular micro-electrodes, when either Ca ions or Ba ions are the charge carriers. In cells bathed in Ca-free Ba solution the two inward currents, named current I and current II, could be identified and studied in the absence of outward currents. The two inward currents could also be separated by addition of the plant lectin concanavalin A (0.5 microgram/ml) to the external medium, which resulted in the selective inhibition of current I. When the holding potential was set at values between -45 and -65 mV (normal resting potential is -50 mV), current I was shifted parallel to the holding potential along the voltage axis. This shift was 7.6 mV per 10 mV change in holding potential. The amplitude and voltage relationship of current II was not affected by these changes in the holding potential. The amplitude of current I in Ba solution was maximal when the membrane potential was held at -55 mV; it decreased with higher and lower holding potentials. The rate of activation of current I remained virtually unaffected at holding potentials between -45 and -60 mV, and was somewhat reduced at a holding potential of -65 mV. When the extracellular Ca concentration was varied between 0.1 and 5.0 mM, or when the cells were loaded with EGTA to reduce the intracellular level of ionized Ca, the resting membrane potential and the voltage relationships of both current I and II and of the outward current were shifted along the voltage axis according to the expected changes in membrane surface potential. Double-pulse experiments with varying interval potentials suggested voltage-dependent inactivation of current I and Ca-dependent inactivation of current II. Pre-hyperpolarizing steps of only 1 mV amplitude and 30 ms duration could result in the activation of current I, indicating that the activation voltage of current I closely followed the actual membrane potential. Hence, the same voltage steps elicited similar current I amplitudes with holding potentials between -45 and -60 mV. The results indicate that current II displays voltage properties described for Ca channels in other ciliates and many multicellular preparations, while current I shows an unusual voltage behaviour, which might be regarded as an 'adaptive type of excitation'.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2441038
A novel barium-sensitive calcium influx into rat astrocytes at low external potassium
Cultured rat cerebellar astrocytes, loaded with the Ca2+-sensitive fluorescent dyes Fura-2 or Fluo-3, responded with cytoplasmic Ca2+transients, when the external K+concentration was reduced from 5mM to below 1mM. Ca2+transients were generated after changing to a saline containing 0.2mM K+in 82% of the cells (n =303) with a delay of up to 4min. Cultured rat cortical neurones, which responded in high-K+saline
R. Dallwig; H. Vitten; J. W. Deitmer
Results of critical velocity experiments with barium, strontium, and calcium releases from CRRES satellite
As part of the NASA CRRES chemical release program in September 1990, two Ba and also one each Sr and Ca canisters of a boron-titanium thermite mixture, which vaporizes the element on ignition, were released near perigee after dusk in the South Pacific to study the critical velocity effect proposed by Alfven. The critical velocities of these three elements are 2.7, 3.5, and 5.4 km/s respectively, all well below the orbital velocity of 9.4 km/s. On September 10, 1990 a Sr and Ba pair (G-13, or critical ionization velocity (CIV) I) was released near Rarotonga at {approximately} 515 km altitude in a background electron density of 3.4 x 10{sup 6} cm{sup {minus}3}. On September 14, 1990, G-14 or CIV II released a Ca and Ba pair west of New Caledonia near 595 km at an electron density of 1.5 x 10{sup 6} cm{sup {minus}3}. Ions of all three elements were observed with low-light level imagers from two aircraft after they had transited up the magnetic field lines into the sunlight. Inventories of the observed ions indicate yields of 0.15% and 1.84% for Ba in the first and second experiments, 0.02% for Sr and 0.27% for Ca. Ionization from all the releases continued along the satellite trajectory much longer (>45 s) than expected for a CIV process. The ion production along the satellite track versus time typically shows a rapid rise to a peak in a few seconds followed by an exponential decrease to a level essentially constant rate. The characteristic distances for CIV I and II are 47 and 62 km, respectively. The authors interpret the early time rise and exponential fall to be due to CIV ionization, of 0.014% (CIV I) and 0.40% (CIV II) for the Ba releases. The later ions produced at a constant rate probably have origins from other such processes as stripping and associative ionization collisions with atmospheric constituents primarily O, and charge exchange with O{sup +}, He{sup +}, and H{sup +}. 44 refs., 9 figs., 1 tab.
Wescott, E.M.; Stenbaek-Nielsen, H.C.; Hampton, D.L.; Delamere, P.A. [Univ. of Alaska, Fairbanks, AK (United States)] [Univ. of Alaska, Fairbanks, AK (United States)
Correlation between 19F environment and isotropic chemical shift in barium and calcium fluoroaluminates.
High-speed MAS (19)F NMR spectra are recorded and reconstructed for 10 compounds from BaF(2)-AlF(3) and CaF(2)-AlF(3) binary systems which leads to the determination of 77 isotropic (19)F chemical shifts in various environments. A first attribution of NMR lines is performed for 8 compounds using a superposition model as initially proposed by B. Bureau et al. The phenomenological parameters of this model are then refined to improve the NMR line assignment. A satisfactory reliability is reached with a root-mean-square (RMS) deviation between calculated and measured values equal to 6 ppm. The refined parameters are then successfully tested on alpha-BaCaAlF(7) whose structure was recently determined. Finally, the isotropic chemical shift ranges are defined for shared, unshared, and "free" fluorine atoms encountered in the investigated binary systems. So, the fluorine surroundings can be deduced from the NMR line positions in compounds whose structure is unknown. Such an approach can also be applied to fluoride glasses. PMID:15074964
Body, M; Silly, G; Legein, C; Buzarķ, J-Y
Paramagnetic Resonance and Charge Compensation of Tetravalent Uranium (U4+) in Calcium, Strontium, and Barium Fluorides
A new electron spin paramagnetic resonance spectrum in CaF2 doped with uranium is attributed to U4+. The spectrum possesses axial symmetry about the directions and is describable by a spin Hamiltonian with g?=0+\\/-0.15 and gII=3.238+\\/-0.005 at 4.2░K. The trigonal symmetry is due to the presence of charge compensating O2- ions along the directions. The spectrum is absent in crystals grown
Amnon Yariv
Potassium blocks barium permeation through a calcium-activated potassium channel
Single high-conductance Ca2+-activated K + channels from rat skeletal muscle were inserted into planar lipid bilayers, and discrete blocking by the Ba 2+ ion was studied. Specifically, the ability of external K ¦ to reduce the Ba ~+ dissocia- tion rate was investigated. In the presence of 150 mM internal K +, 1-5 #M inter- nal Ba z+, and 150
As part of the NASA Combined Release and Radiation Effects Satellite (CRRES) chemical release program in September 1990, two Ba and also one each Sr and Ca canisters of a boron-titanium thermite mixture, which vaporizes the element on ignition, were released near perigee after dusk in the South Pacific to study the critical velocity effect proposed by Alfven. The critical velocities of these three elements are 2.7, 3.5, and 5.4 km/s respectively, all well below the orbital velocity of 9.4 km/s. On September 10, 1990, a Sr and Ba pair (G-13, or critical ionization velocity (CIV) I) was released near Rarotonga at approximately 515 km altitude in a background electron density of 3.4 x 10(exp 6)/cu cm. On September 14, 1990, G-14 or CIV II released a Ca and Ba pair west of New Caledonia near 595 km at an electron density of 1.5 x 10(exp 6)/cu cm. Ions of all three elements were observed with low-light level imagers from two aircraft after they had transited up the magnetic field lines into the sunlight. Emissions from the spherically expanding neutral gas shells below the solar terminator, observed with cameras filtered for the Ba(+) ion line at 4554 A and also in unfiltered imagers for approximately 15 s after release, are probably due to excitation by hot electrons created in the CIV process. The ions created clearly lost much of their energy, which we now show can be explained by elastic collisions: Ba(+) + O. Inventories of the observed ions indicate yields of 0.15% and 1.84% for Ba in the first and second experiments, 0.02% for Sr and 0.27% for Ca. Ionization from all the releases continued along the satellite trajectory much longer (greater than 45 s) than expected for a CIV process. The ion production along the satellite track versus time typically shows a rapid rise to a peak in a few seconds followed by an exponential decrease to a level essentially constant rate. The characteristic distances for CIV I and II are 47 and 62 km, respectively. We interpret the early time rise and exponential fall to be due to CIV ionization, of 0.014% (CIV I) and 0.40% (CIV II) for the Ba releases. The later ions produced at a constant rate probably have origins from other such processes as stripping and associative ionization collisions with atmospheric constituents primarily O, and charge exchange with O(+), He(+), and H(+). We suggest that the much larger Ba ionization rate in CIV II than CIV I is due to the fact that the release occurred in the peak Ca density where hot electrons were already present.
Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hampton, D. L.; Delamere, P. A.
Intracellular Ionized Calcium.
Measurement of intracellular ionized calcium concentration (Ca2+) in living cells is of considerable interest to investigators over a broad range of cell biology. Calcium has an important role in a number of cellular functions and, perhaps most interestin...
C. H. June P. S. Rabinovitch
Calcium absorption and achlorhydria
Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium
Robert R. Recker
Calcium and bones
... body gets the calcium it needs through the food you eat. If you do not get enough calcium in your diet or if your body does not absorb enough, your bones can get weak or not grow properly. Bone density refers to how much calcium and other types ...
Pharmacology of Calcium Antagonists
Although the calcium antagonists verapamil, ni\\\\~{} fedipine, diltiazem and bepridil are structurally diverse, they share, to a variable extent, several pharmacologic properties. These effects are preQ sumably the result of dose-related inhibition of transmembrane calcium ion flux through the slow channel. In diseased tissue, other routes of calcium entry may also be inhibited, and intracellular sites of action also are
Arnold Schwartz; M. Abdul Matus; Joseph Balwierczak; David A. Lathrop
Hyperuricosuric calcium oxalate nephrolithiasis
Many investigators have observed that renal calcium stones may be associated with uric acid disorders. Prien and Prien [1] noted that patients with gout who had stone disease frequently passed stones which contained or were composed of calcium oxalate. Gutman [2] also observed a high frequency of calcium oxalate stones in patients who had gout; and he called attention to
Fredric L Coe
Castable Calcium Aluminate Refractory.
A castable calcium aluminate refractory having a lower Al2O3 content, which is highly resistant to hot reducing atmospheres, is disclosed. It consists of 15-30% of approximately 85%-325 Tyler mesh calcium aluminate admixed with 85-70% of coarser calcium a...
L. Y. Sadler
Study on industrial synthesis of poly aluminum chloride and coagulation effect with different basicities
In this experimental study, the industrial technique of the one-step method of dissolving the calcium aluminate with the hydrochloric acid to synthesize Poly Aluminum Chloride (PAC) was simulated. And effects of technical conditions were also researched. On these bases, the effects of different basicities on PAC coagulation were studied for the water treatment of Mopanshan reservoir.
Zhen Zhang; Di Guan; Hui Liu; Xing Li
Mechanism and kinetics of aluminum and iron leaching from coal fly ash by sulfuric acid
The mechanism and kinetics of leaching of aluminum and iron from Coal Fly Ash (CFA), by sulfuric acid, involves a rate controlling step of mass transfer. It is shown that, in the leaching process, particles follow the shrinking core model with respect to formation of unreacted core that is encapsulated by a leached, porous, layer. Formation of diffusion resistant calcium
A. Seidel; Y. Zimmels
Barium and strontium uptake into larval protoconchs and statoliths of the marine neogastropod Kelletia kelletii
The trace elemental composition of calcified larval hard parts may serve as useful tags of natal origin for invertebrate population studies. We examine whether the trace metal barium (Ba) deposits into the calcium carbonate matrix of molluscan larval statolith and protoconch in proportion to seawater Ba concentration at two temperatures (11.5 and 17░C). We also examine strontium (Sr) uptake as a function of temperature. Using encapsulated larvae of the marine gastropod, Kelletia kelletii, reared in the laboratory under controlled conditions, we demonstrate a significant inverse effect of temperature and a positive effect of seawater Ba/Ca ratio on Ba incorporation into larval carbonates. Ba/Ca partition coefficients ( D Ba) in protoconch were 1.13 at 11.4░C and 0.88 at 17.1░C, while D Ba in larval statolith measured 1.58 at 11.4░C and 1.29 at 17.1░C. Strontium incorporation into statoliths is also inversely affected by temperature, but there was a significant positive effect of temperature on Sr incorporation into protoconch. These data suggest larval statoliths and protoconchs can meaningfully record variation in seawater physical and chemical properties, and, hence, have potential as natural tags of natal origin.
Zacherl, Danielle C.; Paradis, Georges; Lea, David W.
The crystal growth of barium flouride in aqueous solution
The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25░C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (? ? 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.
Barone, J. P.; Svrjcek, D.; Nancollas, G. H.
Ferroelectric films of barium titanate were synthesized on silicon and quartz substrates, and the photoelectric effect in the structure consisting of metal deposited ferroelectric barium titanate film silicon was studied. A photovoltage with polarity that depends on the direction of the remanent polarization was observed. The deposition of BaTiO3 on silicon and fused quartz substrates was accomplished by an rf sputtering technique. A series of experiments to study the growth of ferroelectric BaTiO3 films on single crystal silicon and fused quartz substrates were conducted. The ferroelectric character in these films was found on the basis of evidence from the polarization electric field hysteresis loops, capacitance voltage and capacitance temperature techniques and from X-ray diffraction studies.
Nature of the semiconducting properties of ceramic barium titanate
The compound BaTiO/sub 3/ is a dielectric but can be put into the semiconducting state by means of heat treatment in a reducing atmosphere or by doping with a small (0.1-0.5 mole %) amount of oxides of group-III or group-V elements (so-called donor dopants). The effect of dopants on the properties of barium titanate cannot be explained by means of quasi-chemical reactions. The chemical and crystal-chemical properties of dopant oxides and the phase relations in multicomponent BaTiO/sub 3/-dopant oxides systems make it possible correctly to estimate and predict the dependence of the properties of barium titantate on the dopant oxides.
Kvantov, M.A.; Kostikov, Yu.P.; Leikina, B.B.
The Skylab barium plasma injection experiments. I - Convection observations
Two barium-plasma injection experiments were carried out during magnetically active periods in conjunction with the Skylab 3 mission. The high-explosive shaped charges were launched near dawn on November 27 and December 4, 1973, UT. In both cases, the AE index was near 400 gammas, and extensive pulsating auroras covered the sky. The first experiment, Skylab Alpha, occurred in the waning phase of a 1000-gamma substorm, and the second, Skylab Beta, occurred in the expansive phase of an 800-gamma substorm. In both, the convection was generally magnetically eastward, with 100-km-level electric fields near 40 mV/m. However, in the Alpha experiment the observed orientation of the barium flux tube fit theoretical field lines having no parallel current, but the Beta flux-tube orientation indicated a substantial upward parallel sheet current.
Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Peek, H. M.
Observations and theory of the AMPTE magnetotail barium releases
The barium releases in the magnetotail during the Active Magnetospheric Particle Tracer Explorers (AMPTE) operation were monitored by ground-based imagers and by instruments on the Ion Release Module. After each release, the data show the formation of a structured diamagnetic cavity. The cavity grows until the dynamic pressure of the expanding ions balances the magnetic pressure on its surface. The magnetic field inside the cavity is zero. The barium ions collect on the surface of the cavity, producing a shell. Plasma irregularities form along magnetic field lines draped over the surface of the cavity. The scale size of the irregularities is nearly equal to the thickness of the shell. The evolution and structuring of the diamagnetic cavity are modeled using magnetohydrodynamics theory.
Bernhardt, P. A.; Roussel-Dupre, R. A.; Pongratz, M. B.; Haerendel, G.; Valenzuela, A.
Aluminum microstructures on anodic alumina for aluminum wiring boards.
The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide film of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices. PMID:20356280
Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki
Mechanisms of Aluminum Tolerance
\\u000a Aluminum (Al) toxicity limits agricultural productivity over much of the worldÆs arable land by inhibiting root growth and\\u000a development. Affected plants have difficulty in acquiring adequate water and nutrition from their soil environments and thus\\u000a have stunted shoot development and diminished yield. Al toxicity is due to soil acidity and is largely a natural problem;\\u000a however, it can also result
Owen A. Hoekenga; Jurandir V. Magalhaes
X?ray photoelectron and FTIR spectroscopic investigation of cement doped with barium nitrate
The chemical environment of barium in Portland cement which is doped with barium nitrate was investigated using x?ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). The barium doped cement showed tremendous increases in carbonate content over the undoped cement. An XPS sulfate signal was observed in the cement doped with 20% w\\/w Ba(NO3)2 but not in the 0
H. G. McWhinney; M. W. Rowe; D. L. Cocke; J. D. Ortego
Preparation of barium\\/strontium titanate by solution route
As compared to the conventional solid-state route, solution routes have been reported to produce powders with better homogeneity and controlled morphology. A new solution-based method has been developed to produce fine powders of BaTiO3 and SrTiO3 of high reactivity. In this method an equimolar mixture of solutions of barium nitrate or strontium nitrate and titanium nitrate is heated with suitable
T. V. Vittal Rao; R. V. Kamat; V. N. Vaidya; D. D. Sood
Glycothermal synthesis and characterization of tetragonal barium titanate
Tetragonal barium titanate (BaTiO3) particles were synthesized at temperature as low as 220░C through glycothermal reaction by using Ba(OH)2Ę8H2O and amorphous titanium hydrous gel as precursors and 1,4-butanediol and water as solvent. XRD, DSC and Raman data support that glycothermal processing method provides a simple low-temperature route for producing tetragonal BaTiO3 nanoparticles without alkaline mineralizers. It is also demonstrated that
Yong-Jin Jung; Dae-Young Lim; Jun-Seok Nho; Seung-Beom Cho; Richard E. Riman; Byeong Woo Lee
Efficiency and mechanism of barium getters at low pressures
The gettering rates of barium getters for oxygen, nitrogen, hydrogen, carbon-monoxide, carbon-dioxide and water vapour are measured in the pressure range between 5 ū 10-8 and 5 ū 10-5 mm of mercury. Values for the decay in gettering rate during use of the getter are given. It is shown that the gettering effect at these low pressures is almost entirely
S. Wagener
Radium and barium in the Amazon River system
Data for ┬▓┬▓ŌüČRa and ┬▓┬▓ŌüĖRa in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon
Willard S. Moore; John M. Edmond
Barium-strontium-titanate etching characteristics in chlorinated discharges
The etching characteristics of barium-strontium-titanate (BST) were investigated using a high-density plasma sustained by surface waves at 190 MHz in Ar\\/Cl2 gas mixtures. The etch rate was examined as a function of both the total gas pressure and the Cl2 fraction in Ar\\/Cl2 using a wafer temperature of 10 ░C. The results were correlated to positive ion density and plasma
Luc Stafford; Joļlle Margot; Olivier Langlois; Mohamed Chaker
Sol-Gel Derived Barium-Strontium Titanate Films
Sol-gel techniques for the preparation of barium-strontium titanate (BST) films are discussed. The evolution of film microstructure during heat treatment, and the dielectric properties of BST films prepared from alkoxide solutions and from alkoxide solutions modified by 2-ethylhexanoic acid were studied. It is shown that the extent of the modification of the precursors by 2-ethylhexanoic acid changes the precursor molecular
V. A. Vasiljev; K. A. Vorotilov; M. I. Yanovskaya; L. I. Solovjeva; A. S. Sigov
Sol-gel preparation of barium strontium titanate thin films
Barium strontium titanate, ((BaxSr1-x)TiO 3), thin films of various compositions were prepared by a spin coating technique. Processing parameters were optimized to develop stable solutions which yielded crack-free films with relatively low crystallization temperatures. XRD and thermal analysis techniques were used to characterize the films and gels. The dielectric constant and dissipation factor of the films were measured as a
D. Tahan; A. Safari; L. C. Klein
Nonlinear dielectric properties of barium strontium titanate ceramics
In barium strontium titanate (BaxSr1?xTiO3) ceramics, obvious tunabilities of both dielectric permittivity and loss tangent under external DC bias field were observed. The temperature and frequency dependences of nonlinear dielectric properties were studied. Polarizing process was carried out to evaluate the influence of domain reorientation on dielectric nonlinearity in the ferroelectric polycrystalline samples. The nonlinear variation of dielectric properties under
Xiaoyong Wei; Xi Yao
Texture and Microstructural Development in Gelcast Barium Hexaferrite
The development of texture in barium hexaferrite by templated grain growth was studied as a function of the Fe2O3/BaCO3 ratio, B2O3 additions in the starting materials, and sintering temperature. A magnetic field was used to orient the template particles during the gelcasting process. Excess BaCO3 resulted in abnormal grain growth and maximized texture, while B2O3 additions promoted coarsening, but no abnormal grain growth.
Hovis, David B. [Northwestern University, Evanston; Faber, Katherine T. [Northwestern University, Evanston; Kenik, Edward A [ORNL
The positive temperature coefficient of resistivity in barium titanate
Positive temperature coefficient of resistivity (PTCR) materials have become very important components, and among these materials\\u000a barium titanate compounds make up the most important group. When properly processed these compounds show a high PTCR at the\\u000a Curie temperature (the transition temperature from the ferroelectric tetragonal phase to the paraelectric cube phase). In\\u000a the first half of this paper literature related
B. Huybrechts; K. Ishizaki; M. Takata
Elastic and Piezoelectric Coefficients of Single-Crystal Barium Titanate
Mechanical resonance and antiresonance frequencies were measured on barium titanate single-crystal elements maintained under electric dc bias from -50░C to +150░C. A complete set of elastic, piezoelectric, and dielectric constants of the tetragonal modification at 25░C is obtained. The elastic compliances show substantial deviation from cubic symmetry. Measurements in the orthorhombic state show longitudinal compliance four times higher than in
Don Berlincourt; Hans Jaffe
Barium¢borate¢flyash glasses: As radiation shielding materials
The attenuation coefficients of barium¢borate¢flyash glasses have been measured for ?-ray photon energies of 356, 662, 1173 and 1332keV using narrow beam transmission geometry. The photon beam was highly collimated and overall scatter acceptance angle was less than 3░. Our results have an uncertainty of less than 3%. These coefficients were then used to obtain the values of mean free
Sukhpal Singh; Ashok Kumar; Devinder Singh; Kulwant Singh Thind; Gurmel S. Mudahar
Adequacy of preparation for barium enema among elderly outpatients.
OBJECTIVE: To determine whether outpatients 75 years of age or older have a higher rate of inadequate bowel preparation for barium enema and of complications associated with the preparation and the test than patients aged 55 to 74 years. DESIGN: Cross-sectional survey. SETTING: Radiology department in a teaching hospital. PATIENTS: Patients 55 years or older referred for a barium enema from March to August 1988. OUTCOME MEASURES: All films were reviewed independently by a study radiologist blind to the staff radiologist's report. Patients were interviewed by telephone within several days after the test to assess the occurrence of problems during the preparation or the test. MAIN RESULTS: Of the 213 patients assessed 72 were excluded: 43 refused to participate or could not be contacted, 16 had previously undergone colonic surgery, and 13 were excluded for other reasons. The remaining 141 patients were separated into three age groups: those 55 to 64 years (46 patients), those 65 to 74 (47) and those 75 or older (48). In 104 cases (74%) the bowel had been prepared adequately; there was no significant difference between the three groups with regard to the adequacy of preparation. The incidence of problems reported by the patients did not differ significantly between the groups. CONCLUSIONS: Outpatients aged 75 years or more are no more likely than those aged 55 to 74 to have problems with bowel preparation or the barium enema itself. Age should not be a criterion for exclusion from barium enema. To try to lower the rate of poor bowel preparation clinicians and radiologists should consider counselling patients more carefully about the importance of proper preparation. Also, the current method of preparation could be examined to determine whether simple changes would significantly improve colon cleanliness.
Grad, R M; Clarfield, A M; Rosenbloom, M; Perrone, M
Isotopic Masses of Hydrogen, Chlorine, Barium, Cerium, and Neodymium
The 16-in. double-focusing mass spectrometer at the University of Minnesota has been employed to measure the atomic mass of H1 and the atomic masses and isotopic mass differences of chlorine, barium, cerium, and neodymium. Recent improvements in instrumentation have increased the precision of both narrow and wide doublet measurements. The doublet C11H22-C12H10 was used to relate the H1 mass directly
Jay L. Benson; Walter H. Johnson
We report measurements of all the material constants necessary to fully characterize barium borate as a nonlinear optical material. All data was taken on crystals supplied by Professor Chuangtien Chen, Fuzhou, People's Republic of China. We have determined the crystal structure, the optical absorption, the refractive indices from the UV to the near IR, the thermo-optic coefficients, the nonlinear optical or coefficients, the resistance to laser damage, the elastic constants, the thermal expansion, thermal conductivity and dielectric constants, and the fracture toughness. This data is used to evaluate barium borate for a variety of applications. We find that, in general, barium borate has a low acceptance angle, and that despite its higher optical nonlinearity, it is therefore not significantly more efficient than other commonly available materials, except in the UV below 250 nm. On the other hand, it has a high damage threshold, it is physically robust, it has good UV and IR transparency, and it has excellent average power capability. It permits deep UV generation, and has great potential for generating tunable visible and IR light as an optical parametric amplifier.
Eimerl, D.; Davis, L.; Velsko, S.; Graham, E.K.; Zalkin, A.
Structure and multiferroic properties of barium hexaferrite ceramics
Simultaneous occurrence of large ferroelectricity and strong ferromagnetism have been observed in barium hexaferrite ceramics. Barium hexaferrite (BaFe12O19) powders with hexagonal crystal structure were successfully synthesized in a polymer precursor method using barium acetate and ferric acetylacetonate as the precursors. The powders were pressed into pellets which were sintered into ceramics at 1200 ░C and 1300 ░C for 1 h. The structure and morphology of the ceramics were examined using X-ray diffraction and field emission scanning electron microscopy. Large spontaneous polarization was observed in the BaFe12O19 ceramics at room temperature, revealing a clear ferroelectric hysteresis loop. The maximum remanent polarization of the BaFe12O19 ceramic was estimated approximately 11.8 ?C cm-2. The FeO6 octahedron in its perovskite-like hexagonal unit cell and the shift of Fe3+ off the center of octahedron are suggested to be the origin of the polarization in BaFe12O19. The BaFe12O19 ceramics also showed strong ferromagnetism at room temperature.
Tan, Guolong; Chen, Xiuna
Aluminum Carbothermic Technology
This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major accomplishments for the program include definition of the system thermo-chemistry, demonstration of reactor stage 1, development of reactor stage 2 critical components in a 500 kW module, experimental determination of the vapor recovery reactor fundamentals, detailed design and installation of an advanced stage 1/vapor recovery reactor, feasibility of efficient separation of Al-C metal alloy product, updated capital and operating cost estimates, and development of computer models for all steps of the Advanced Reactor Process.
Bruno, Marshall J.
Extracting aluminum from dross tailings
Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.
Molecular aspects of aluminum toxicity
The focus in this review is directed to molecular aspects of aluminum toxicity in animal and plant cells. Unique thermodynamic features of Al(lII) ions impart biological specificity which may form the biochemical basis of aluminum interactions with cellular constituents. Current knowledge about aluminum?specific, molecular interactions is rather scanty. Al(III) ions may coordinate with nucleotides or complex to phospholipids resulting in
Alfred Haug; Charles E. Foy
Quasicrystalline particulate reinforced aluminum composite
Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.
Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.
Stretch-activated calcium channels relay fast calcium waves propagated by calcium-induced calcium influx.
For nearly 30 years, fast calcium waves have been attributed to a regenerative process propagated by CICR (calcium-induced calcium release) from the endoplasmic reticulum. Here, I propose a model containing a new subclass of fast calcium waves which is propagated by CICI (calcium-induced calcium influx) through the plasma membrane. They are called fast CICI waves. These move at the order of 100 to 1000 microm/s (at 20 degrees C), rather than the order of 3 to 30 microm/s found for CICR. Moreover, in this proposed subclass, the calcium influx which drives calcium waves is relayed by stretch-activated calcium channels. This model is based upon reports from approx. 60 various systems. In seven of these reports, calcium waves were imaged, and, in five of these, evidence was presented that these waves were regenerated by CICI. Much of this model involves waves that move along functioning flagella and cilia. In these systems, waves of local calcium influx are thought to cause waves of local contraction by inducing the sliding of dynein or of kinesin past tubulin microtubules. Other cells which are reported to exhibit waves, which move at speeds in the fast CICI range, include ones from a dozen protozoa, three polychaete worms, three molluscs, a bryozoan, two sea urchins, one arthropod, four insects, Amphioxus, frogs, two fish and a vascular plant (Equisetum), together with numerous healthy, as well as cancerous, mammalian cells, including ones from human. In two of these systems, very gentle local mechanical stimulation is reported to initiate waves. In these non-flagellar systems, the calcium influxes are thought to speed the sliding of actinomyosin filaments past each other. Finally, I propose that this mechanochemical model could be tested by seeing if gentle mechanical stimulation induces waves in more of these systems and, more importantly, by imaging the predicted calcium waves in more of them. PMID:17302561
Jaffe, Lionel F
Aluminum-lithium for aerospace
Aluminum-lithium alloys were developed primarily to reduce the weight of aircraft and aerospace structures. Lithium is the lightest metallic element, and each 1% of lithium added to aluminum reduces alloy density by about 3% and increases modulus by about 5%. Though lithium has a solubility limit of 4.2% in aluminum, the amount of lithium ranges between 1 and 3% in commercial alloys. Aluminum-lithium alloys are most often selected for aerospace components because of their low density, high strength, and high specific modulus. However, other applications now exploit their excellent fatigue resistance and cryogenic toughness.
Fielding, P.S.; Wolf, G.J. [Reynolds Metals Co., Richmond, VA (United States)
Laser welding of aluminum alloys
Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.
Leong, K.H.; Sabo, K.R.; Sanders, P.G. [Argonne National Lab., IL (United States). Technology Development Div.; Spawr, W.J.
Interactions between chloride and sulfate or silica removals from wastewater using an advanced lime-aluminum softening process: equilibrium modeling.
Interactions among chloride, sulfate, and silica removals from recycled industrial wastewater using an ultra-high lime with aluminum process (UHLA) were studied. An equilibrium model that is able to accurately predict the chemical behavior and interactions between chloride and sulfate or silica with UHLA at various initial conditions and chemical reagents was developed. X-ray diffraction (XRD) analysis was conducted to identify the precipitated solids formed in the UHLA process. Model predictions indicated that simultaneous removal of sulfate and chloride can be best described by the formation of a solid solution containing calcium chloroaluminate, calcium sulfoaluminate (ettringite), calcium monosulfate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. However, simultaneous removal of silica and chloride can be best described by precipitation of calcium silicate and calcium aluminosilicate in addition to a solid solution containing calcium chloroaluminate, tricalcium hydroxyaluminate, and tetracalcium hydroxyaluminate. The XRD results indicated the presence of the same solids assumed by the equilibrium model. PMID:17571843
Abdel-Wahab, Ahmed; Batchelor, Bill
Calcium current in molluscan neurones: measurement under conditions which maximize its visibility.
1. Membrane currents were studied in isolated somata of molluscan neurones from Archidoris monteryensis and Anisodoris nobilis. Under voltage clamp, inward current displayed a two phase time course, and in some cases a clear reversal potential difference could be shown for the fast and slow phases. The slower phase was carried predominantly by calcium ions. 2. The apparent magnitude of the slower phase was greatly influenced by conditions which altered potassium current flow. Blocking voltage-dependent potassium conductances, either by appropriate conditioning polarizations or by tetraethyl-ammonium (TEA) ion, enhanced the magnitude, while conditions which augmented potassium current made the slow phase disappear. 3. A fraction of the membrane potassium conductance was TEA insensitive. This fraction could be blocked by procedures which prevented internal levels of calcium from increasing during the voltage clamp pulse. Three such procedures were demonstrated; replacement of external calcium by magnesium, internal buffering by EGTA, and replacement of calcium by permeant barium. 4. Internal EGTA buffering or external barium in combination with external TEA produced an extreme change in membrane current as compared with the normal time course. Membrane current, when activated by pulses up to +50 mV, was net inward and showed only fractional inactivation over time courses running to several seconds. Pulses to voltages greater than +60 mV resulted in outward current. 5. It is concluded that under normal conditions the calcium conductance has the extended time course clearly evident under the modified conditions of paragraph 4 but that the calcium flux component is easily missed. 6. In agreement with several prior studies it is also concluded that a rise in internal calcium is causally related to a rise in potassium conductance. A transmembrane flux of calcium can be uncoupled from the gK increase by appropriate buffering of internal calcium. 7. The transient potassium current, IA, which bears a resemblance to calcium-dependent potassium transients in some muscle cells did not depend upon internal calcium but instead is a voltage-activated mechanism.
Connor, J A
A review of the health impacts of barium from natural and anthropogenic exposure.
There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food. PMID:24844320
Kravchenko, Julia; Darrah, Thomas H; Miller, Richard K; Lyerly, H Kim; Vengosh, Avner
Production of aluminum metal by electrolysis of aluminum sulfide
A method is disclosed for production of metallic aluminum by the electrolysis of A1/sub 2/S/sub 3/ at 700/sup 0/-800/sup 0/ C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.
Minh, N.Q.; Loutfy, R.O.; Yao, N.P.
Production of metallic aluminum by the electrolysis of Al.sub.2 S.sub.3 at 700.degree.-800.degree. C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.
Minh, Nguyen Q. (Woodridge, IL); Loutfy, Raouf O. (Tucson, AZ); Yao, Neng-Ping (Clarendon Hills, IL)
Metallic aluminum may be produced by the electrolysis of Al/sub 2/S/sub 3/ at 700 to 800/sup 0/C in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.
Helium Trapping in Aluminum and Sintered Aluminum Powders.
The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV exp 4 He exp + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was ...
S. K. Das M. Kaminsky T. Rossing
21 CFR 172.310 - Aluminum nicotinate.
... 3 2013-04-01 2013-04-01 false Aluminum nicotinate. 172.310 Section 172.310 ...Dietary and Nutritional Additives ┬¦ 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely used as a source of...
21 CFR 73.2645 - Aluminum powder.
... 2013-04-01 false Aluminum powder. 73.2645 Section 73.2645 ...Cosmetics ┬¦ 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and...
Unintentional poisoning by phosphine released from aluminum phosphide.
Aluminum phosphide as a releaser of phosphine gas is used as a grain preservative. In this case report, we describe an accidental severe poisoning in a 35-year-old woman, her 18-year-old daughter, and 6-year-old son caused by inhalation of phosphine gas released from 20 tablets of aluminum phosphide stored in 15 rice bags. The boy died 2 days after exposure before admission to hospital and any special treatment, but the others were admitted 48 h after exposure. They had signs and symptoms of severe toxicity, and their clinical course included metabolic acidosis, electrocardiographic changes, and hypotension. They were treated by intravenous administration of sodium bicarbonate, magnesium sulfate, and calcium gluconate. The patients were discharged after 3 days and followed up for 1 week after discharge. Rapid absorption of phosphine by inhalation, induction of hyperglycemia, and surviving of patients are interesting issues of this case report. PMID:18480154
Shadnia, S; Mehrpour, O; Abdollahi, M
Aluminum alloy development
Development of an aluminum alloy which has higher strength than previous alloys while still showing acceptable levels of corrosion resistance and fracture is presented. Two different approaches to this goal are described; a final thermomechanical treatment method employed deformation and aging, while the second method depended solely on thermal practices to enhance the strength/corrosion resistance combination. Attention is given to a 7055 alloy that offers significant weight savings potential for applications requiring high compression strength combined with good corrosion resistance. It is indicated that structures including keel beams, horizontal tails, upper wings, cargo rails, and seat tracks on commercial transports are all candidate applications for this alloy.
Not Available
Characterization of ultradispersed aluminum
Samples of ultradispersed Al were received, which were produced by electrically exploding Al wires in argon. These samples comprised very small particles that were not significantly oxidized and that were stable in air. Particle morphology were studied with SE, micropycnometry, and gas adsorption surface area. Composition were determined using various techniques, as were thermal stability and reaction exotherms. The inexplicable reports of an Al-Ar compound and of an exothermic reaction were not confirmed. The material is a stable, nonoxidized, small-particle, highly reactive form of aluminum that is of interest in energetic materials formulations.
Simpson, R.L.; Maienschein, J.L.; Swansiger, R.W.; Garcia, F.; Darling, D.H.
A comparison of the calcium-free phosphate binder sevelamer hydrochloride with calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients.
Current phosphate binders used in hemodialysis patients include calcium-based binders that result in frequent hypercalcemia and aluminum-based binders that result in total body aluminum accumulation over time. This investigation describes the use of a calcium- and aluminum-free phosphate-binding polymer in hemodialysis patients and compares it with a standard calcium-based phosphate binder. An open-label, randomized, crossover study was performed to evaluate the safety and effectiveness of sevelamer hydrochloride in controlling hyperphosphatemia in hemodialysis patients. After a 2-week phosphate binder washout period, stable hemodialysis patients were administered either sevelamer or calcium acetate, and the dosages were titrated upward to achieve improved phosphate control over an 8-week period. After a 2-week washout period, patients crossed over to the alternate agent for 8 weeks. Eighty-four patients from eight centers participated in the study. There was a similar decrease in serum phosphate values over the course of the study with both sevelamer (-2.0 +/- 2.3 mg/dL) and calcium acetate (-2.1 +/- 1.9 mg/dL). Twenty-two percent of patients developed a serum calcium greater than 11.0 mg/dL while receiving calcium acetate, versus 5% of patients receiving sevelamer (P < 0.01). The incidence of hypercalcemia for sevelamer was not different from the incidence of hypercalcemia during the washout period. Patients treated with sevelamer also sustained a 24% mean decrease in serum low-density lipoprotein cholesterol levels. Sevelamer was effective in controlling hyperphosphatemia without resulting in an increase in the incidence of hypercalcemia seen with calcium acetate. This agent appears quite effective in the treatment of hyperphosphatemia in hemodialysis patients, and its usage may be advantageous in the treatment of dialysis patients. PMID:10196011
Bleyer, A J; Burke, S K; Dillon, M; Garrett, B; Kant, K S; Lynch, D; Rahman, S N; Schoenfeld, P; Teitelbaum, I; Zeig, S; Slatopolsky, E
In vitro adsorption of aluminum by an edible biopolymer poly(?-glutamic acid).
Accumulation of aluminum in human has been reported to be associated with dementia, Parkinson's disease, and Alzheimer's disease. The objectives of this study were to evaluate an edible biopolymer poly(?-glutamic acid) (?-PGA) for aluminum removal efficiency under in vitro conditions as affected by pH, contact time, aluminum concentration, temperature, ionic strength, and essential metals in both aqueous aluminum solution and simulated gastrointestinal fluid (GIF). A low aluminum adsorption occurred at pH 1.5-2.5, followed by a maximum adsorption at pH 3.0-4.0 and precipitating thereafter as aluminum hydroxide at pH > 4. Adsorption was extremely fast with 81-96% of total adsorption being attained within 1 min, reaching equilibrium in 5-10 min. Kinetic data at low (10 mg/L) and high (50 mg/L) concentrations were well described by pseudo-first-order and pseudo-second-order models, respectively. Equilibrium adsorption isotherms at different temperatures were precisely fitted by both Langmuir and Redlich-Peterson models with the maximum adsorption capacities at 25, 37, and 50 ░C being 35.85, 38.68, and 44.23 mg/g, respectively. Thermodynamic calculations suggested endothermic and spontaneous nature of aluminum adsorption by ?-PGA with increased randomness at the solid/solution interface. Variation in ionic strengths did not alter the adsorption capacity, however, the incorporation of essential metals significantly reduced the aluminum adsorption by following the order copper > iron > zinc > calcium > potassium. Compared to aqueous solution, the aluminum adsorption from simulated GIF was high at all studied pH (1-4) with Langmuir monolayer adsorption capacity being 49.43 mg/g at 37 ░C and pH 4. The outcome of this study suggests that ?-PGA could be used as a safe detoxifying agent for aluminum. PMID:24799126
Rajan, Yesudoss Christu; Inbaraj, Baskaran Stephen; Chen, Bing Huei
Target-Cell Contact Activates a Highly Selective Capacitative Calcium Entry Pathway in Cytotoxic T Lymphocytes
Calcium influx is critical for T cell activation. Evidence has been presented that T cell receptor¢stimulated calcium influx in helper T lymphocytes occurs via channels activated as a consequence of depletion of intracellular calcium stores, a mechanism known as capacitative Ca2+ entry (CCE). However, two key questions have not been addressed. First, the mechanism of calcium influx in cytotoxic T cells has not been examined. While the T cell receptor¢mediated early signals in helper and cytotoxic T cells are similar, the physiology of the cells is strikingly different, raising the possibility that the mechanism of calcium influx is also different. Second, contact of T cells with antigen-presenting cells or targets involves a host of intercellular interactions in addition to those between antigen¢MHC and the T cell receptor. The possibility that calcium influx pathways in addition to those activated via the T cell receptor may be activated by contact with relevant cells has not been addressed. We have used imaging techniques to show that target-cell¢stimulated calcium influx in CTLs occurs primarily through CCE. We investigated the permeability of the CTL influx pathway for divalent cations, and compared it to the permeability of CCE in Jurkat human leukemic T cells. CCE in CTLs shows a similar ability to discriminate between calcium, barium, and strontium as CCE in Jurkat human leukemic T lymphocytes, where CCE is likely to mediated by Ca2+ release¢activated Ca2+ current (CRAC) channels, suggesting that CRAC channels also underlie CCE in CTLs. These results are the first determination of the mechanism of calcium influx in cytotoxic T cells and the first demonstration that cell contact¢mediated calcium signals in T cells occur via depletion-activated channels.
Zweifach, Adam
The Benefits of Aluminum Windows.
Discusses benefits of aluminum windows for college construction and renovation projects, including that aluminum is the most successfully recycled material, that it meets architectural glass deflection standards, that it has positive thermal energy performance, and that it is a preferred exterior surface. (EV)
Goyal, R. C.
Lost-Soap Aluminum Casting.
Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)
Mihalow, Paula
Boron carbide-aluminum cermets
We have developed boron carbide-aluminum cermets by means of thermodynamic, kinetic, and processing studies. Our research indicates that boron carbide-aluminum cermets offer ''tailorable'' microstructures with designable properties through process control. This new class of cermets has the potential to become a very important material with wide industrial applications.
Halverson, D.C.
Residual Aluminum in Potable Water.
The behavior of aluminum in water treatment facilities using alum coagulation was studied with laboratory jar tests as well as actual plant monitoring. For surface waters with pH > 6, the amount of dissolved aluminum is usually less than 40 ppb. Particula...
W. Sung
Modeling dissolution in aluminum alloys
Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working,
Tracie Lee Durbin
Primary Aluminum Plants Worldwide - 1998
The 1990 U.S. Bureau of Mines publication, Primary Aluminum Plants Worldwide, has been updated and is now available. The 1998 USGS edition of Primary Aluminum Plants Worldwide is published in two parts. Part IŚDetail contains information on individual primary smelter capacity, location, ownership, sources of energy, and other miscellaneous information. Part IIŚSummary summarizes the capacity data by country
Development of a Fluorescence-Based in-situ Barium Sensor.
Biogeochemical characteristics render barium a useful tracer of riverine inputs on 10-100 kms spatial scales. Ultimately we seek to determine of barium in seawaters by an in-situ technique. An intermediate step toward achieving that goal is the developmen...
K. K. Falkner
Synthesis and crystal structure of a barium complex with pyruvic acid isonicotinoyl hydrazone
A barium complex with pyruvic acid isonicotinoyl hydrazone (H2L) has been synthesized and its crystal structure was determined by X-ray diffraction analyses. There is one complex unit, Ba(HL)2(H2O), with eight lattice water molecules in the asymmetric unit. The nine-coordinated barium has a distorted, monocapped square antiprism configuration.
Kaibei Yu
ined by x-ray diffraction and density- measurements. The tetrafluoride ; dissolves in difluoride to the extent of about 25 M%, the unit-cell constant ; decreasing in the former and increasing in the latter system. Barium and ; strontium fluorides dissolve in barium uranium hexafluoride and strontium thorium ; hexafluoride respectively to the extent of about 20 M % with the
R. W. M. DEye; I. F. Ferguson
Obtaining Monocrystals of Solid Solutions of Barium and Strontium Titanates and Their Dielectric and Optical Properties.
In this paper monocrystals of solid solutions of barium and strontium titanates are described. The growing of the monocrystals was done in a platinum crucible from a solution of a mixture of barium and strontium titanates in potassium fluoride. The potass...
A. L. Khodakov M. L. Sholokhovich E. G. Fesenko O. P. Kramarov
Investigations of Indium Tin OxideŚBarium Strontium Titanate¢Indium Tin Oxide Heterostructure for Tunability
This letter reports for the first time the interesting behavior of the interface between indium tin oxide (ITO) as a high resistive electrode and barium strontium titanate tunable paraelectric thin film material. The interface is consisting of barium strontium titanate (BST) thin film dielectric material sandwiched between two ITO high resistive layers, all are integrated above glass substrate. When dc
Mahmoud Al Ahmad; Ludovic Salvagnac; Dominique Michau; Mario Maglione; Robert Plana
The effect of barium on perceptions of taste intensity and palatability.
Barium may affect the perception of taste intensity and palatability. Such differences are important considerations in the selection of dysphagia assessment strategies and interpretation of results. Eighty healthy women grouped by age (younger, older) and genetic taste status (supertaster, nontaster) rated intensity and palatability for seven tastants prepared in deionized water with and without 40Ā% w/v barium: noncarbonated and carbonated water, diluted ethanol, and high concentrations of citric acid (sour), sodium chloride (salty), caffeine (bitter), and sucrose (sweet). Mixed-model analyses explored the effects of barium, taster status, and age on perceived taste intensity and acceptability of stimuli. Barium was associated with lower taste intensity ratings for sweet, salty, and bitter tastants, higher taste intensity in carbonated water, and lower palatability in water, sweet, sour, and carbonated water. Older subjects reported lower palatability (all barium samples, sour) and higher taste intensity scores (ethanol, sweet, sour) compared to younger subjects. Supertasters reported higher taste intensity (ethanol, sweet, sour, salty, bitter) and lower palatability (ethanol, salty, bitter) than nontasters. Refusal rates were highest for younger subjects and supertasters, and for barium (regardless of tastant), bitter, and ethanol. Barium suppressed the perceived intensity of some tastes and reduced palatability. These effects are more pronounced in older subjects and supertasters, but younger supertasters are least likely to tolerate trials of barium and strong tastant solutions. PMID:24037100
Dietsch, Angela M; Solomon, Nancy Pearl; Steele, Catriona M; Pelletier, Cathy A
Synthesis, characterization and microwave absorption properties of titania-coated barium ferrite composites
Anatase titania-coated barium ferrite composites were prepared by a heterogeneous precipitation method in the presence of barium ferrite particles. The obtained samples were characterized by ?-pH, TEM, EDX and XRD. The complex permittivity and permeability were studied in the frequency range of 2 12 GHz. The structure and microwave response properties are investigated. The results show that the coverage of titania has a great influence on microwave response of barium ferrite. The formation of an anatase titania nano-layer on the surface of a barium ferrite particle changes the character of the frequency dispersion of the complex permittivity. Comparing the anatase titania-coated barium ferrite composites with the uncoated barium ferrite, the complex permittivity of the anatase titania-coated barium ferrite composites is higher than that of uncoated barium ferrite. The complex permeability of composites was found to decrease with an increase in frequency as well as with the molar ratio of Ti:Ba. The enhancement of the complex permittivity may be due to dipolar polarization and interfacial polarization. The maximum reflection loss was obtained at the Ti:Ba ratio of 1:10, and the peak of the maximum reflection loss shifts to a lower frequency value with increasing titania fraction. By changing the thickness of titania coverage, the frequency dependence of the complex permittivity could be adjusted, which provides us an opportunity for the synthesis of tailored particles.
Tang, X.; Zhao, B. Y.; Tian, Q.; Hu, K. A.
Study of Second Harmonic Generation Coefficients and Ultraviolet Absorption Edge of Barium Borate Crystal.
Barium borate (beta-BaB2O4) is a new type of non-linear optical crystal. In this paper the authors report one-electron energies and wave functions of barium borate by use of EHMO theory. Both the calculated values of SHG coefficient and ultraviolet absorp...
J. K. Zhu B. Zhang S. H. Liu
Growth and characterization of a new non-linear optical barium strontium borate (BSB) single crystal
The growth of a new inorganic mixed borate of barium strontium borate (BSB) is reported by solution growth technique for the first time. The structure of the grown crystal has been identified by single crystal X-ray diffraction method. The exact percentage of barium and strontium present in the mixed borate crystal system is quantified by atomic absorption spectroscopic analysis. The
K. Prabha; T. Rajesh Kumar; Shi Feng Du; M. Vimalan; A. Dayalan; P. Sagayaraj
Synthesis and properties of barium titanate solid solution thin films deposited on copper substrates
Barium titanate thin films were deposited via chemical solution deposition using a hybrid-chelate chemistry directly on copper foil substrates. A process was developed to crystallize and densify the ferroelectric films at 900░C by using a reductive atmosphere containing nitrogen, hydrogen, water vapor, and oxygen impurities such that film constituents were oxidized to form barium titanate and the foil substrate remained
Jon Fredrick Ihlefeld
Photoemission study of the reactivity of barium towards SiO x thermal films
Barium was deposited at room temperature on a thermal silicon oxide layer and the interfacial reaction was monitored by synchrotron induced photoemission (both core level and valence band). The first step of the growth consists of an interfacial reaction which leads to the formation of an interfacial silicate layer. The next step consists in formation of barium oxide while metallic
T. GenevĶs; B. Domenichini; L. Imhoff; V. Potin; Z. Li; S. Bourgeois
To assess adverse effects that might be caused by an event resulting in high levels of barium in drinking water, rats were gavaged with barium chloride (BaCl2 at dosage levels of 30,100, and 300 rng/kg in a 1-day study and at 100,145,209, and 300 rng/kg for 10 days, and the effec...
Relative sensitivity of colonoscopy and barium enema for detection of colorectal cancer in clinical practice
BACKGROUND & AIMS: The relative sensitivities of barium enema and colonoscopy for colorectal cancer are still debated. The aim of this study was to determine the relative sensitivity of barium enema and colonoscopy in general clinical practice. METHODS: Medical records of 2193 consecutive colorectal cancer cases identified in 20 central Indiana hospitals were reviewed. All procedures performed within 3 years
DK Rex; EY Rahmani; JH Haseman; GT Lemmel; S Kaster; JS Buckley
Aluminum alloys for aerostructures
Demands on the airframe industry have shifted over the years, but they have always moved in the direction of lower weight, higher damage tolerance, and longer-term durability. Up to the 1960s, the greatest need was for high strength to reduce weight. In the 1970s, higher fracture toughness and corrosion resistance were sought for enhanced damage tolerance and durability. In the early 1980s, the requirement for reduced weight was renewed, but by the late 1980s and early 1990s, durability became a concern again. Today`s focus is on materials that can help achieve low-cost manufacturing without sacrificing performance; future needs are likely to include both affordability and higher performance. This article describes the development of high-strength aluminum alloy materials that have satisfied past and current requirements, and identifies possible aluminum-intensive approaches that combine alternate design concepts and emerging materials technologies for low-cost, low-weight, damage-tolerant, and durable airframe structures of the future.
Staley, J.T.; Liu, J. [Alcoa Technical Center, Alcoa Center, PA (United States); Hunt, W.H. Jr. [Aluminum Consultants Group Inc., Murrysville, PA (United States)
Evidence against Barium in the Mushroom Trogia venenata as a Cause of Sudden Unexpected Deaths in Yunnan, China
This study examined barium concentrations in the mushroom Trogia venenata, the leading culprit for sudden unexpected deaths in Yunnan, southwest China. We found that barium concentrations in T. venenata from Yunnan were low and comparable to other foods, inconsistent with barium concentrations in this mushroom as a significant contributor to these deaths.
Zhang, Ying; Li, Yanchun; Wu, Gang; Feng, Bang; Yoell, Shanze; Yu, Zefen; Zhang, Keqin
Environmental monitoring of offshore oil and gas drilling dischargesŚA caution on the use of barium as a tracer
Commonly used methods for extracting barium from marine sediments are inefficient when high concentrations of barium sulphate are present in samples. Comparative data on sea-bed barium concentrations around a single exploration well are presented to highlight the influence of different extraction methods which can result in 2¢3 order of magnitude differences in levels recorded. This suggests that in many monitoring
John P. Hartley
Wettability of Aluminum on Alumina
The wettability of molten aluminum on solid alumina substrate has been investigated by the sessile drop technique in a 10-8 bar vacuum or under argon atmosphere in the temperature range from 1273 K to 1673 K (1000 ░C to 1400 ░C). It is shown that the reduction of oxide skin on molten aluminum is slow under normal pressures even with ultralow oxygen potential, but it is enhanced in high vacuum. To describe the wetting behavior of the Al-Al2O3 system at lower temperatures, a semiempirical calculation was employed. The calculated contact angle at 973 K (700 ░C) is approximately 97 deg, which indicates that aluminum does not wet alumina at aluminum casting temperatures. Thus, a priming height is required for aluminum to infiltrate a filter. Wetting in the Al-Al2O3 system increases with temperature.
Bao, Sarina; Tang, Kai; Kvithyld, Anne; Tangstad, Merete; Engh, Thorvald Abel
Aluminum inhibits erythropoiesis in vitro.
Anemia has been associated with aluminum intoxication in patients on chronic dialysis and in animals. In studies presented here, in vitro human erythroid culture was used to delineate the effects of aluminum on normal hematopoiesis. Aluminum by itself in routine culture, even at very high levels (1,035 ng/ml), did not significantly affect erythroid colony growth. The addition of human transferrin to the culture, however, resulted in a marked dose-dependent inhibition of erythroid, but not myeloid colony growth. At all doses, CFU-E progenitors showed greater inhibition than burst-forming units (BFU-E). Aluminum inhibition was not overcome by increasing the dose of erythropoietin or adding additional burst-promoting activity to the culture. Inhibition by aluminum was directly related to the number of binding sites on transferrin in the culture, and was not observed in the presence of fully iron-saturated transferrin. Images
Mladenovic, J
Temperature dependence dielectric properties of modified barium titanate-PVB composites
In this work, attempts are made to prepare ceramic polymer-composite followed by characterization of dielectric properties. The Barium Titanate ceramic powders are synthesized using the hydrothermal process. Silane treatment is carried out on Barium Titanate powder to increase its compatibility with polymer, followed with preparation of ceramic-polymer composite. Polyvinyl Butyral (PVB) is used as matrix for preparation of the composites and the concentration of Barium Titanate is increased from 60 to 90 wt%. Dielectric properties such as volume resistivity, dielectric constant, dissipation factor are evaluated. Results indicate that the dielectric constant and dissipation factor vary between 52 to 120 and 0.01 to 0.07; respectively as the relative ratio of polymer and silane modified Barium Titanate is varied. Specifically, at 90 wt% of silane modified Barium Titanate, the highest dielectric constant of 123 along with dissipation factor of 0.07 is obtained.
Joshi, N. J.; Rakshit, P. B.; Grewal, G. S.; Shrinet, V.; Pratap, A.
Hydration of Portland cement with additions of calcium sulfoaluminates
The effect of mineral additions based on calcium aluminates on the hydration mechanism of ordinary Portland cement (OPC) was investigated using isothermal calorimetry, thermal analysis, X-ray diffraction, scanning electron microscopy, solid state nuclear magnetic resonance and pore solution analysis. Results show that the addition of a calcium sulfoaluminate cement (CSA) to the OPC does not affect the hydration mechanism of alite but controls the aluminate dissolution. In the second blend investigated, a rapid setting cement, the amorphous calcium aluminate reacts very fast to ettringite. The release of aluminum ions strongly retards the hydration of alite but the C-S-H has a similar composition as in OPC with no additional Al to Si substitution. As in CSA-OPC, the aluminate hydration is controlled by the availability of sulfates. The coupling of thermodynamic modeling with the kinetic equations predicts the amount of hydrates and pore solution compositions as a function of time and validates the model in these systems.
Le Saout, Gwenn, E-mail: email@example.com [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Lothenbach, Barbara [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)] [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Hori, Akihiro [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany)] [DENKA Chemicals GmbH, Wehrhahn-Center, Cantadorstr. 3, D-40211 Duesseldorf (Germany); Higuchi, Takayuki [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan)] [Denki Kagaku Kogyo Kabushiki Kaisha (DENKA), Omi, Itoigawa, Niigata, 949-0393 (Japan); Winnefeld, Frank [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)] [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland)
Contribution of 43Ca MAS NMR for probing the structural configuration of calcium in glass
The 43Ca MAS NMR spectra obtained for three calcium silicate glasses containing aluminum and/or sodium are analyzed. The 43Ca NMR parameters are shown to be highly sensitive to variations in its chemical environment. The transition from a charge-compensating role of [AlO 4] - groups to a network-modifying role near nonbridging oxygen atoms results in an increase of both the isotropic chemical shift and the quadrupolar coupling constant of 43Ca. This effect can be related to the first coordination shell of calcium (through the Ca-O bond distance) which is affected by the chemical environment beyond the first neighbors of calcium.
Angeli, Frķdķric; Gaillard, Marina; Jollivet, Patrick; Charpentier, Thibault
A soluble alkoxide of barium with a cubane structure
There has been recent interest in alkaline earth metal alkoxides and aryloxides in an effort to make volatile precursors for the preparation of superconducting thin films using organometallic chemical vapor deposition (OMCVD). This has been especially true of barium, as it is an important metal in may of the high-temperature superconductors (YBa[sub 2]Cu[sub 3]O[sub 7], HgBa[sub 2]CuO[sub 4], HgBa[sub 2]Ca[sub 2]Cu[sub 3]O[sub 8]). A problem in the attempted synthesis of a well-defined [Ba(OR)[sub 2
Borup, B.; Samuels, J.A.; Streib, W.E.; Caulton, K.G. (Indiana Univ., Bloomington, IN (United States))
Deterioration Mode of Barium-Containing NO x Storage Catalyst
Barium-containing NOx storage catalyst showed serious deactivation under thermal exposure at high temperatures. To elucidate the thermal deterioration of the NOx storage catalyst, four types of model catalyst, Pt\\/Al2O3, Ba\\/Al2O3, Pt¢Ba\\/Al2O3, and a physical mixture of Pt\\/Al2O3 + Ba\\/Al2O3 were prepared and their physicochemical properties such as BET, NO TPD, TGA\\/DSC, XRD, and XPS were evaluated while the thermal aging
Bo-Hyuk Jang; Tae-Hun Yeon; Hyun-Sik Han; Yong-Ki Park; Jae-Eui Yie
The title compound, [BaCl2(C2H6SO)], forms a Ba6Cl9 cluster in which the BaCl2 units are connected via dimethylŁsulfoxide (DMSO) and chloride bridges. The central Cl atom of the Ba6Cl9 cluster is located on a threefold inversion axis and is coordinated octaŁhedrally to six barium cations. In the crystal, the clusters are arranged in rows, which are interŁconnected by the DMSO molŁecules, forming a three-dimensional network.
Gschwind, Fabienne; Jansen, Martin
Strain engineered barium strontium titanate for tunable thin film resonators
Piezoelectric properties of epitaxial (001) barium strontium titanate (BST) films are computed as functions of composition, misfit strain, and temperature using a non-linear thermodynamic model. Results show that through adjusting in-plane strains, a highly adaptive rhombohedral ferroelectric phase can be stabilized at room temperature with outstanding piezoelectric response exceeding those of lead based piezoceramics. Furthermore, by adjusting the composition and the in-plane misfit, an electrically tunable piezoelectric response can be obtained in the paraelectric state. These findings indicate that strain engineered BST films can be utilized in the development of electrically tunable and switchable surface and bulk acoustic wave resonators.
Khassaf, H.; Khakpash, N.; Sun, F.; Sbrockey, N. M.; Tompa, G. S.; Kalkur, T. S.; Alpay, S. P.
Selective laser sintering of barium titanate¢polymer composite films
A selective laser sintering process has been used to consolidate electro-ceramic thin films on silicon substrates. Methods\\u000a of forming pre-positioned layers of barium titanate were investigated by spin-coating the feedstock powder mixed with a commercial\\u000a polymer photo-resist. The ceramic¢polymer composite was deposited directly onto a nickel film which was evaporated onto a\\u000a silicon substrate, pre-oxidised to form an electrically insulating
A. T. Clare; P. R. Chalker; S. Davies; C. J. Sutcliffe; S. Tsopanos
The title compound, [BaCl(2)(C(2)H(6)SO)], forms a Ba(6)Cl(9) cluster in which the BaCl(2) units are connected via dimethyl-sulfoxide (DMSO) and chloride bridges. The central Cl atom of the Ba(6)Cl(9) cluster is located on a threefold inversion axis and is coordinated octa-hedrally to six barium cations. In the crystal, the clusters are arranged in rows, which are inter-connected by the DMSO mol-ecules, forming a three-dimensional network. PMID:23284316
Aspiration of barium-impregnated polyethylene spheres by a dog.
This case report describes an 11-year-old Belgian Malinois dog with acute onset of cough caused by aspiration of barium-impregnated polyethylene spheres (BIPS) and pneumonia following an episode of suspected gastric dilation. Although bronchoscopic retrieval of the BIPS was largely unsuccessful, the dog recovered uneventfully, with most of the BIPS being coughed out and swallowed over a 1-month period. Aspiration of BIPS should be considered a potential complication of their administration. Furthermore, endoscopic removal of aspirated BIPS is challenging and may not be indicated because of their inert nature and possible self-clearance. PMID:20529021
Greci, V; Bissett, S A; Copple, C N; Hawkins, E C
Data for /sup 226/Ra and /sup 228/Ra in the Amazon River system show that the activity of each radium isotope is strongly correlated with barium concentrations. Two trends are apparent, one for rivers which drain shield areas and another for all other rivers. These data suggest that there has been extensive fractionation of U, Th, and Ba during weathering in the Amazon basin. The /sup 226/Ra data fit a flux model for the major ions indicating that /sup 226/Ra behaves conservatively along the main channel of the Amazon River.
Moore, W.S.; Edmond, J.M.
Magnetic and structural investigations on barium hexaferrite ferrofluids
Barium hexaferrite BaFe 12-2 xTi xCo xO 19 ferrofluids have been prepared using oleic acid as surfactant and Isopar M « or dodecane as carrier liquid. The ferrite particles were prepared by glass crystallization. Hysteresis parameters, the initial susceptibility versus temperature and the magnetic particle size were obtained by VSM. Ferrofluids with a partly deuterated carrier liquid were investigated by small angle neutron scattering (SANS). SANS curves lead to a bimodal size distribution consisting of single magnetic particles with an organic shell and aggregated particles with an incomplete organic layer.
M³ller, R.; Hiergeist, R.; Gawalek, W.; Hoell, A.; Wiedenmann, A.
Dielectric behavior of barium modified strontium bismuth titanate ceramic
Barium Modified Strontium Bismuth Titanate(SBT) ceramic with general formula Sr1-xBaxBi4Ti4O15 is prepared by solid state reaction route. The structural analysis of the ceramics was done by X-ray diffraction technique. The X-ray patterns show that all the compositions are of single phase with orthorhombic structure. The temperature dependent dielectric behavior shows that the transition temperature decreases with Ba content but the maximum dielectric constant increases. The decreases of the transition with increase in Ba2+ ion, may be due to the decrease of orthorhombicity by the incorporation of Ba2+ ion in SBT lattice.
Nayak, P.; Badapanda, T.; Anwar, S.; Panigrahi, S.
Magnetic properties of NiZr substituted barium ferrite
Single-domain fine particles of NiZr substituted barium ferrite has been synthesized by citrate gel route. The magnetization value obtained are comparable with those observed in Co-Ti substitution. This has been attributed to strong preference of Ni2+ for octahedral coordination, and no particular preference for Zr4+ ion. Phase formation at lower temperature permits easy control over the microstructure and hence, a large variation in coercivity (180-4500 Oe) has been possible as a function of x and heat treatment temperature.
Rane, Manisha V.; Bahadur, D.; Kulkarni, S. D.; Date, S. K.
Single-domain fine particles of NiZr substituted barium ferrite has been synthesized by citrate gel route. The magnetization value obtained are comparable with those observed in Co-Ti substitution. This has been attributed to strong preference of Ni 2+ for octahedral coordination, and no particular preference for Zr 4+ ion. Phase formation at lower temperature permits easy control over the microstructure and hence, a large variation in coercivity (180-4500 Oe) has been possible as a function of x and heat treatment temperature.
Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol
In the current study the focus is on dielectric properties (as a function of frequency and temperature) of a polymeric composite system composed of polyvinyl alcohol and barium titanate nano powder. In the investigations, the temperature range is between 50-295 K, and the frequency range is between $20\\ \\hertz-1\\ \\mega\\hertz$. Polarization and conduction processes are investigated in the linear regime. Dielectric breakdown strengths of samples are also reported. The materials presented have potential to be implemented in cryogenic capacitor or field grading applications.
Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Duckworth, Robert C [ORNL
Electric tunable behavior of sputtered lead barium zirconate thin films
Lead barium zirconate (PBZ) films were grown on Pt/Ti/SiO2/Si substrates by rf-magnetron sputtering. The sputtered PBZ films possess pure perovskite phase, uniform microstructure, and excellent tunable behaviors. The tunability and loss tangent of sputtered PBZ films depend greatly on the oxygen mixing ratio (OMR). The optimal dielectric tunable behavior occurs in the PBZ films sputtered at 10% OMR. The sputtered PBZ film (10% OMR) possesses a value of figure of merit of 60, promising for frequency-agile applications. Bulk acoustic waves induced by electromechanical coupling occur at 2.72 GHz, which is useful in fabricating filters and related devices in the microwave range.
Wu, Lin-Jung; Wu, Jenn-Ming; Huang, Hsin-Erh; Bor, Hui-Yun
Calcium fluoride window mounting
A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.
Berger, D.D.
Calcium Nutrition in Adolescence
Adolescence is an important period of nutritional vulnerability due to increased dietary requirements for growth and development and special dietary habits. Calcium needs are elevated as a result of the intensive bone and muscular development and thus adequate calcium intake during growth is extremely important to reach the optimum peak bone mass and to protect against osteoporosis in the adult
Marta MesĒas; Isabel Seiquer; M. Pilar Navarro
Calcium signaling in neurodegeneration
Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.
Marambaud, Philippe; Dreses-Werringloer, Ute; Vingtdeux, Valerie
Calcium hydroxyapatite fillers.
Calcium hydroxyapatite fillers have unique advantages over other fillers in regards to duration of action and volume of product required for augmentation, especially in the midface and lower face. In this article, we describe our experience with calcium hydroxyapatite fillers and compare them with other available filler products. PMID:22205523
Tansavatdi, Kristina; Mangat, Devinder S
High Blood Calcium (Hypercalcemia)
... glands in your neck) secrete a hormone called parathyroid hormone (Pth). Pth helps your bones release calcium into ... together, Pth and vitamin D, along with other hormones and minerals, help move calcium in or ... or more of the parathyroid glands produces too much Pth. this, in turn, ...
Dissolution of Barium from Barite in Sewage Sludges and Cultures of Desulfovibrio desulfuricans
High concentrations of total barium, ranging from 0.42 to 1.58 mg(middot)g(sup-1) (dry weight) were found in sludges of two sewage treatment plants near Florence, Italy. Barium concentrations in the suspended matter decreased as redox potential values changed from negative to positive. An anoxic sewage sludge sample was aerated, and 30% of the total barium was removed in 24 h. To demonstrate that barium was solubilized from barite by sulfate-reducing bacteria, a strain of Desulfovibrio desulfuricans was used to study the solubilization of barium from barite under laboratory conditions. During cell growth with different concentrations of barite from 0.01 to 0.3 g(middot)liter(sup-1) (the latter is the MIC) as the only source of sulfates in the cultures, the D. desulfuricans strain accumulated barium up to 0.58 (mu)g(middot)mg(sup-1) (dry weight). Three times the quantity of barium was dissolved by bacteria than in the uninoculated medium (control). The unexpectedly low concentration of soluble barium (1.2 mg of Ba(middot)liter(sup-1)) with respect to the quantity expected (109 mg of Ba(middot)liter(sup-1)), calculated on the basis of the free H(inf2)S evolved from the dissimilatory reduction of sulfate from barite, was probably due to the formation of other barium compounds, such as witherite (BaCO(inf3)) and the transient species barium sulfide (BaS). The D. desulfuricans strain, growing on barite, formed visible aggregates. Confocal microscopy analysis showed that aggregates consisted of bacteria and barite. After 3 days of incubation, several autofluorescent crystals surrounded by a dissolution halo were observed. The crystals were identified as BaS by comparison with the commercial compound.
Baldi, F.; Pepi, M.; Burrini, D.; Kniewald, G.; Scali, D.; Lanciotti, E.
Releasing-addition method for the flame-photometric determination of calcium in thermal waters
Study of the interferences of silica and sulfate in the flame-photometric determination of calcium in thermal waters has led to the development of a method requiring no prior chemical separations. The interference effects of silica, sulfate, potassium, sodium, aluminum, and phosphate are overcome by an addition technique coupled with the use of magnesium as a releasing agent. ?? 1963.
Rowe, J. J.
First principles pseudopotential calculations on aluminum and aluminum alloys
Recent advances in computational techniques have led to the possibility of performing first principles calculations of the energetics of alloy formation on systems involving several hundred atoms. This includes impurity concentrations in the 1% range as well as realistic models of disordered materials (including liquids), vacancies, and grain boundaries. The new techniques involve the use of soft, fully nonlocal pseudopotentials, iterative diagonalization, and parallel computing algorithms. This approach has been pioneered by Car and Parrinello. Here the authors give a review of recent results using parallel and serial algorithms on metallic systems including liquid aluminum and liquid sodium, and also new results on vacancies in aluminum and on aluminum-magnesium alloys.
Davenport, J.W.; Chetty, N.; Marr, R.B.; Narasimhan, S.; Pasciak, J.E.; Peierls, R.F.; Weinert, M.
Aluminum Zintl anion moieties within sodium aluminum clusters
Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium-aluminum cluster anions, NamAln-, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.
Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Gantef÷r, Gerd; Schn÷ckel, Hansgeorg; Eichhorn, Bryan W.; Lee, Mal-Soon; Jena, P.; Kandalam, Anil K.; Kiran, Boggavarapu; Bowen, Kit H.
Aluminum Zintl anion moieties within sodium aluminum clusters.
Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium-aluminum cluster anions, Na(m)Al(n)(-), were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams. PMID:24511934
Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Gantef÷r, Gerd; Schn÷ckel, Hansgeorg; Eichhorn, Bryan W; Lee, Mal-Soon; Jena, P; Kandalam, Anil K; Kiran, Boggavarapu; Bowen, Kit H
Calcium stone disease: a multiform reality
In calcium renal stones, calcium oxalate and calcium phosphate in various crystal forms and states of hydration can be identified. Calcium oxalate monohydrate (COM) or whewellite and calcium oxalate dihydrate (COD) or weddellite are the commonest constituents of calcium stones. Calcium oxalate stones may be pure or mixed, usually with calcium phosphate or sometimes with uric acid or ammonium urate.
Alberto Trinchieri; Chiara Castelnuovo; Renata Lizzano; Giampaolo Zanetti
The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer
A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mĄ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ▒ 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.
Kramer, Henry
21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.
Code of Federal Regulations, 2012 CFR
...Calcium pantothenate, calcium chloride double salt. 172.330 Section 172.330 Food and...Calcium pantothenate, calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may be safely...
Code of Federal Regulations, 2011 CFR
Aluminum Plasmonic Nanoantennas
We have explored the plasmonic properties of individual Al nanorod antennas fabricated by planar lithography on lightly doped n-type silicon. Energy-resolved cathodoluminescence was used to image the local density of optical states with a spatial resolution of ś 20 nm and thereby identify the radiative modes of these nanostructures. Al nanoantenna emission exhibited highly tunable plasmonic resonances from the deep UV through the visible region of the spectrum. The dependence of the radiative dipolar and quadrupolar plasmon modes on antenna length and photon energy agreed well with finite difference time domain-based analysis of these nanostructures. The results herald nano-structured aluminum as a practical and highly promising material system for the design and implementation of UV and visible frequency plasmonics, broadening the range of potential applications of plasmonics into areas where complementary metal-oxide-semiconductor (CMOS) compatibility or low-cost, mass producibility are desired.
Everitt, Henry; Knight, Mark; Liu, Lifei; Yang, Yumin; Brown, Lisa; Mukherjee, Shaunak; King, Nicholas; Nordlander, Peter; Halas, Naomi
Aluminum: Industry of the future
For over a century, the US aluminum industry has led the global market with advances in technology, product development, and marketing. Industry leaders recognize both the opportunities and challenges they face as they head into the 21st century, and that cooperative R and D is key to their success. In a unique partnership, aluminum industry leaders have teamed with the US Department of Energy`s Office of Industrial Technologies (OIT) to focus on innovative technologies that will help to strengthen the competitive position of the US aluminum industry and, at the same time, further important national goals. This industry-led partnership, the Aluminum Industry of the Future, promotes technologies that optimize the use of energy and materials in operations and reduce wastes and energy-related emissions. Led by The Aluminum Association, industry leaders began by developing a unified vision of future market, business, energy, and environmental goals. Their vision document, Partnerships for the Future, articulates a compelling vision for the next 20 years: to maintain and grow the aluminum industry through the manufacture and sale of competitively priced, socially desirable, and ecologically sustainable products. Continued global leadership in materials markets will require the combined resources of industry, universities, and government laboratories. By developing a unified vision, the aluminum industry has provided a framework for the next step in the Industries of the Future process, the development of a technology roadmap designed to facilitate cooperative R and D.
Oxidation of aluminum nanoclusters
The dynamics of oxidation of aluminum nanoclusters (20 nm diameter) is investigated using a parallel molecular dynamics approach based on variable charge interatomic interactions due to Streitz and Mintmire that include both ionic and covalent effects. Simulations are performed for both canonical ensembles for molecular oxygen (O{sub 2}) environments and microcanonical ensembles for molecular (O{sub 2}) and atomic (O{sub 1}) oxygen environments. Structural and dynamic correlations in the oxide region are calculated, as well as the evolution of charges, surface oxide thickness, diffusivities of atoms, and local stresses. In the microcanonical ensemble, the oxidizing reaction becomes explosive in both molecular and atomic oxygen environments due to the enormous energy release associated with Al-O bonding. Local stresses in the oxide scale cause rapid diffusion of aluminum and oxygen atoms. Analyses of the oxide scale reveal significant charge transfer and a variation of local structures from the metal-oxide interface to the oxide-environment interface. In the canonical ensemble, oxide depth grows linearly in time until {approx}30 ps, followed by saturation of oxide depth as a function of time. An amorphous oxide layer of thickness {approx}40 A is formed after 466 ps, in good agreement with experiments. The average mass density in the oxide scale is 75% of the bulk alumina density. Evolution of structural correlation in the oxide is analyzed through radial distribution and bond angles. Through detailed analyses of the trajectories of O atoms and their formation of OAl{sub n} structures, we propose a three-step process of oxidative percolation that explains deceleration of oxide growth in the canonical ensemble.
Campbell, Timothy J. [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Mississippi State University, Stennis Space Center, Mississippi 39529 (United States); Aral, Gurcan; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya [Collaboratory for Advanced Computing and Simulations, Department of Materials Science and Engineering, Department of Physics and Astronomy, Department of Computer Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Ogata, Shuji [Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
Spray Rolling Aluminum Strip
Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.
Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.
Proton trapping in yttrium-doped barium zirconate
The environmental benefits of fuel cells have been increasingly appreciated in recent years. Among candidate electrolytes for solid-oxide fuel cells, yttrium-doped barium zirconate has garnered attention because of its high proton conductivity, particularly in the intermediate-temperature region targeted for cost-effective solid-oxide fuel cell operation, and its excellent chemical stability. However, fundamental questions surrounding the defect chemistry and macroscopic proton transport mechanism of this material remain, especially in regard to the possible role of proton trapping. Here we show, through a combined thermogravimetric and a.c. impedance study, that macroscopic proton transport in yttrium-doped barium zirconate is limited by proton-dopant association (proton trapping). Protons must overcome the association energy, 29?kJ?mol-1, as well as the general activation energy, 16?kJ?mol-1, to achieve long-range transport. Proton nuclear magnetic resonance studies show the presence of two types of proton environment above room temperature, reflecting differences in proton-dopant configurations. This insight motivates efforts to identify suitable alternative dopants with reduced association energies as a route to higher conductivities.
Yamazaki, Yoshihiro; Blanc, Frķdķric; Okuyama, Yuji; Buannic, Lucienne; Lucio-Vega, Juan C.; Grey, Clare P.; Haile, Sossina M.
Indentation size effect in barium titanate with spherical tipped nanoindenters
Nanoindentation tests in an 90░-ac-domain area of an {001} orientated barium titanate single crystal were performed using four different indenters (two with cube corner and two with spherical shape) with tip radii from 61 nm to 1.9 ?m. Extensive calibrations of the tips on fused quartz and sapphire defined the penetration depth range for approximately spherical contact prior to indentation of barium titanate (BaTiO3). The measured elastic modulus is independent of the different indenters. The measurements showed plastic deformation after ``pop-in''. The calculated mean pressure remained constant for each indenter, but clearly depends upon the indenter radius. The indenter radius dependence of the hardness support the concept of ``geometrically necessary dislocations'', proposed by W. D. Nix and H. Gao [J. Mech. Phys. Sol., 46, 411 (1998)] and its extension to spherical tipped indenters [J. G. Swadener, E. P. George, G. M. Pharr, J. Mech. Phys. Solids, 50, 681 (2002)]. The results show this concept fits the data generated with indenter radii which are at least an order of magnitude lower than investigated by Swadener. Furthermore, the results agree with estimates of the statistically stored dislocation density determined for BaTiO3.
Scholz, T.; Mu±oz-Salda±a, J.; Swain, M. V.; Schneider, G. A.
Redox processes in highly yttrium-doped barium titanate
The changes of microstructure occurring during oxidation of the reduced form of yttrium-doped barium titanate (Ba{sub 1-x}Y{sub x}{sup ?}Ti{sub 1-x}{sup 4+}Ti{sub x}{sup 3+}O{sub 3}) have been studied. Samples were sintered under reduction conditions at P{sub O{sub 2}}=10{sup -4}Pa and oxidized by annealing at high temperatures (1150 and 1350 deg. C) in air. Depending on yttrium concentration, the oxidation of the reduced form of the yttrium-doped BaTiO{sub 3} caused precipitation of the phase Ba{sub 6}Ti{sub 17}O{sub 40} or the phases Ba{sub 6}Ti{sub 17}O{sub 40} and Y{sub 2}Ti{sub 2}O{sub 7}. The precipitates had well-defined orientational relationships with the perovskite matrix. Oxidation of the reduced form of doped barium titanate results in formation of the phase Ba{sub 1-x}Y{sub x}{sup ?}Ti{sub 1-x/4}{sup 4+}(V{sub Ti}{sup -}bar ){sub x/4}O{sub 3} responsible for increase in the resistance of outer grain layers, which lie between grain boundaries and grain.
Belous, Anatolii [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine); V'yunov, Oleg [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine)]. E-mail: firstname.lastname@example.com; Kovalenko, Leonid [Department of Solid State Chemistry, V.I. Vernadskii Institute of General and Inorganic Chemistry, Ukrainian National Academy of Sciences, Institute of General and Inorganic Chemistry, 32/42, Palladin Ave, 03680 Kyiv 142 (Ukraine); Makovec, Darko [Jozef Stefan Institute, Ljubljana (Slovenia)
Barium titanate core - gold shell nanoparticles for hyperthermia treatments
The development of new tools and devices to aid in treating cancer is a hot topic in biomedical research. The practice of using heat (hyperthermia) to treat cancerous lesions has a long history dating back to ancient Greece. With deeper knowledge of the factors that cause cancer and the transmissive window of cells and tissues in the near-infrared region of the electromagnetic spectrum, hyperthermia applications have been able to incorporate the use of lasers. Photothermal therapy has been introduced as a selective and noninvasive treatment for cancer, in which exogenous photothermal agents are exploited to achieve the selective destruction of cancer cells. In this manuscript, we propose applications of barium titanate core¢gold shell nanoparticles for hyperthermia treatment against cancer cells. We explored the effect of increasing concentrations of these nanoshells (0¢100 ?g/mL) on human neuroblastoma SH-SY5Y cells, testing the internalization and intrinsic toxicity and validating the hyperthermic functionality of the particles through near infrared (NIR) laser-induced thermoablation experiments. No significant changes were observed in cell viability up to nanoparticle concentrations of 50 ?g/mL. Experiments upon stimulation with an NIR laser revealed the ability of the nanoshells to destroy human neuroblastoma cells. On the basis of these findings, barium titanate core¢gold shell nanoparticles resulted in being suitable for hyperthermia treatment, and our results represent a promising first step for subsequent investigations on their applicability in clinical practice.
FarrokhTakin, Elmira; Ciofani, Gianni; Puleo, Gian Luigi; de Vito, Giuseppe; Filippeschi, Carlo; Mazzolai, Barbara; Piazza, Vincenzo; Mattoli, Virgilio
Results of magnetospheric barium ion cloud experiment of 1971
The barium ion cloud experiment involved the release of about 2 kg of barium at an altitude of 31 482 km, a latitude of 6.926 N., and a longitude of 74.395 W. Significant erosion of plasma from the main ion core occurred during the initial phase of the ion cloud expansion. From the motion of the outermost striational filaments, the electric field components were determined to be 0.19 mV/m in the westerly direction and 0.68 mV/m in the inward direction. The differences between these components and those measured from balloons flown in the proximity of the extremity of the field line through the release point implied the existence of potential gradients along the magnetic field lines. The deceleration of the main core was greater than theoretically predicted. This was attributed to the formation of a polarization wake, resulting in an increase of the area of interaction and resistive dissipation at ionospheric levels. The actual orientation of the magnetic field line through the release point differed by about 10.5 deg from that predicted by magnetic field models that did not include the effect of ring current.
Adamson, D.; Fricke, C. L.; Long, S. A. T.