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Overlapping with Girolami's interest in bis(porphryin) complexes that mimic the photosynthetic reaction center, the Girolami group has also studied actinide chemistry. | 1 | Solid-state chemistry |
Tantalum(III) chloride or tantalum trichloride is non-stoichiometric chemical compound with a range of composition from TaCl to TaCl Anionic and neutral clusters containing Ta(III) chloride include [TaCl] and [TaCl](HO). | 1 | Solid-state chemistry |
CMF can replace rolled steel armour with the same protection for one-third the weight. It can block fragments and the shock waves that are responsible for traumatic brain injuries (TBI). CMF was tested against blasts and fragments. The panels were tested against 23 × 152 mm high explosive incendiary rounds (as in anti-aircraft weapons) that release a high-pressure blast wave and metal fragments at speeds up to 1524 m/s. The CMF panels were able to withstand the blast and frag impacts without bowing or cracking. The thicker sample (16.7 mm thick) was able to completely stop various-sized fragments from three separate incendiary ammunition tests. It was shown that CMF is able to locally arrest the fragments and dissipate the energy of the incident blast wave and impede the spread of failure, as opposed to fully solid materials that transfers the energy across the entire plate, damaging the bulk material. In this study, stainless steel CMF blocked blast pressure and fragmentation at 5,000 feet per second from high explosive incendiary (HEI) rounds that detonate at 18 inches away. Steel CMF plates (9.5 mm or 16.75 mm thick) that were placed 18 inches from the strike plate held up against the wave of blast pressure and against the copper and steel fragments created by a 23×152 mm HEI round (as in anti-aircraft weapons) as well as a 2.3mm aluminium strikeplate. The performance of the steel CMF was far better than the same weight aluminium plate against the same type of blast and fragments. | 0 | Colloidal Chemistry |
Roy had no formal medical credentials but was an advocate of integrating science, medicine, and spirituality. In the inaugural issue of the Journal of Ayurveda and Integrative Medicine Roy contributed the article "Integrative medicine to tackle the problem of chronic diseases". He noted that chronic illness debilitates the lives of many seniors, and that medical interventions are often futile. He said "little of nothing is being spent on preventative medicine", and cited the ayurveda concepts of "ahara" concerned with nutrition, and "vihara" with the conduct of life. He noted the exemplary work of Dean Ornish in addressing coronary artery disease as a hopeful innovation.
In 2010, close to the end of his life, Roy co-wrote an article in the Huffington Post called "The Mythology Of Science-Based Medicine" with nonscientists Deepak Chopra and Larry Dossey, which David Gorski characterized as "an exercise that combines cherry-picking, logical fallacies, and whining, raising the last of these almost to an art form." | 1 | Solid-state chemistry |
Natural salt pans or salt flats are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts and are natural formations (unlike salt evaporation ponds, which are artificial).
A salt pan forms by evaporation of a water pool, such as a lake or pond. This happens in climates where the rate of water evaporation exceeds the rate of that is, in a desert. If the water cannot drain into the ground, it remains on the surface until it evaporates, leaving behind minerals precipitated from the salt ions dissolved in the water. Over thousands of years, the minerals (usually salts) accumulate on the surface. These minerals reflect the sun's rays (through radiation) and often appear as white areas.
Salt pans can be dangerous. The crust of salt can conceal a quagmire of mud that can engulf a truck. The Qattara Depression in the eastern Sahara Desert contains many such traps which served as strategic barriers during World War II. | 1 | Solid-state chemistry |
Tetravalent main-group-element hydrides of form AH (A = B, C, N, O, Al, Si, P, and S, where A is a tetravalent atom or ion) are known to distort from the square planar to tetrahedral geometry. For all AH systems in D symmetry, the ground state is a. The exact electronic configuration, however, is dependent on the electronegativity of the main group element. The distortion to tetrahedral geometry has b symmetry. For these AH systems, the a→b and e→e one-electron charge-transfer transitions are most active in the b mode. | 1 | Solid-state chemistry |
*Because optical properties depend on suspended particle size, a stable synthetic material called "Formazin" with uniform particle size is often used as a standard for calibration and reproducibility. The unit is called Formazin Turbidity Unit (FTU).
*Nephelometric Turbidity Units (NTU) specified by United States Environmental Protection Agency is a special case of FTU, where a white light source and certain geometrical properties of the measurement apparatus are specified. (Sometimes the alternate form "nephelos turbidity units" is used)
*Formazin Nephelometric Units (FNU), prescribed for 9 measurements of turbidity in water treatment by ISO 7027, another special case of FTU with near infrared light (NIR) and 90° scatter.
*Formazin Attenuation Units (FAU) specified by ISO 7027 for water treatment standards for turbidity measurements at 0°, also a special case of FTU.
*Formazin Backscatter Units (FBU), not part of a standard, is the unit of optical backscatter detectors (OBS), measured at c. 180°, also a special case of FTU.
*European Brewery Convention (EBC) turbidity units
*Concentration Units (C.U.)
*Optical Density (O.D.)
*Jackson "Candle" Turbidity Units (JTU; an early measure)
*Helms Units
*American Society of Brewing Chemists (ASBC-FTU) turbidity units
*Brantner Haze Scale (BHS) and Brantner Haze Units (BHU) for purposefully hazy beer
*Parts Per Million of standard substance, such as PPM/DE (Kieselguhr)
*"Trübungseinheit/Formazin" (TE/F) a German standard, now replaced by the FNU unit.
*diatomaceous earth ("ppm SiO") an older standard, now obsolete
A more popular term for this instrument in water quality testing is a turbidimeter. However, there can be differences between models of turbidimeters, depending upon the arrangement (geometry) of the source beam and the detector. A nephelometric turbidimeter always monitors light reflected off the particles and not attenuation due to cloudiness. In the United States environmental monitoring the turbidity standard unit is called Nephelometric Turbidity Units (NTU), while the international standard unit is called Formazin Nephelometric Unit (FNU). The most generally applicable unit is Formazin Turbidity Unit (FTU), although different measurement methods can give quite different values as reported in FTU (see below).
Gas-phase nephelometers are also used to study the atmosphere. These can provide information on visibility and atmospheric albedo. | 0 | Colloidal Chemistry |
Iron(II) oxide makes up approximately 9% of the Earths mantle. Within the mantle, it may be electrically conductive, which is a possible explanation for perturbations in Earths rotation not accounted for by accepted models of the mantle's properties. | 1 | Solid-state chemistry |
The Dead Sea's mineral composition varies with season, rainfall, depth of deposit, and ambient temperature. Most oceanic salt is approximately 85 wt.% sodium chloride (the same salt as table salt) while Dead Sea salt is only 30.5 wt.% of this, with the remainder composed of other dried minerals and salts. The concentrations of the major ions present in the Dead Sea water are given in the following table:
The chemical composition of the crystallized Dead Sea salts does not necessarily correspond to the results presented in this table because of composition changes due to the process of fractional crystallization.
The main detritic minerals present in the Dead Sea mud were carried by runoff streams flowing into the Dead Sea. They constituted large mud deposits intermixed with salt layers during the Holocene era. Their elemental composition expressed as equivalent oxides (except for Cl and Br) is given here below:
Except for chloride and bromide, the results of the elemental composition of the Dead Sea mud given here above are presented as equivalent oxides for the sake of convenience. To illustrate this chemical convention, the neutral sodium sulfate (NaSO) is reported here as basic sodium oxide (NaO) and acidic sulfur trioxide (SO), neither of which can naturally occur under these free forms in this mud. However, one will note that the elemental composition given here above is incomplete as a major component is lacking in this table: carbon dioxide (CO) accounting for the significant carbonate fraction present in this mud. | 1 | Solid-state chemistry |
A description of the structure of reticulated foams is still being developed. While Plateau's laws, the rules governing the shape of soap films in foams were developed in the 19th century, a mathematical description of the structure is still debated. The computer-generated Weaire–Phelan structure is the most recent. In a reticulated foam only the edges of the polyhedra remain; the faces are missing. In commercial reticulated foam, up to 98% of the faces are removed. The dodecahedron is sometimes given as the basic unit for these foams, but the most representative shape is a polyhedron with 13 faces. Cell size and cell size distribution are critical parameters for most applications. Porosity is typically 95%, but can be as high as 98%. Reticulation affects many of the physical properties of a foam. Typically resistance to compression is decreased while tensile properties like elongation and resistance to tearing are increased. | 0 | Colloidal Chemistry |
Tin(IV) oxide has long been used as an opacifier and as a white colorant in ceramic glazes.The Glazers Book – 2nd edition. A.B.Searle.The Technical Press Limited.' London. 1935. This has probably led to the discovery of the pigment lead-tin-yellow, which was produced using tin(IV) oxide as a compound. The use of tin(IV) oxide has been particularly common in glazes for earthenware, sanitaryware and wall tiles; see the articles tin-glazing and Tin-glazed pottery. Tin oxide remains in suspension in vitreous matrix of the fired glazes, and, with its high refractive index being sufficiently different from the matrix, light is scattered, and hence increases the opacity of the glaze. The degree of dissolution increases with the firing temperature, and hence the extent of opacity diminishes. Although dependent on the other constituents the solubility of tin oxide in glaze melts is generally low. Its solubility is increased by NaO, KO and BO, and reduced by CaO, BaO, ZnO, AlO, and to a limited extent PbO.
SnO has been used as pigment in the manufacture of glasses, enamels and ceramic glazes. Pure SnO gives a milky white colour; other colours are achieved when mixed with other metallic oxides e.g. VO yellow; CrO pink; and SbO grey blue. | 1 | Solid-state chemistry |
Synthesis: MOBs under reducing conditions using sodium hydroxide (NaOH), can be self-assembled at body temperature (37 degrees Celsius). In the case of copper CuHARS, MOBs can be produced by transforming copper nanoparticles to provide the copper source, or by utilizing copper(II) sulfate. | 0 | Colloidal Chemistry |
CaB has been investigated in the past due to a variety of peculiar physical properties, such as superconductivity, valence fluctuation and Kondo effects. However, the most remarkable property of CaB is its ferromagnetism. It occurs at unexpectedly high temperature (600 K) and with low magnetic moment (below 0.07 per atom). The origin of this high temperature ferromagnetism is the ferromagnetic phase of a dilute electron gas, linkage to the presumed excitonic state in calcium boride, or external impurities on the surface of the sample. The impurities might include iron and nickel, probably coming from impurities in the boron used to prepare the sample.
CaB is insoluble in HO, MeOH (methanol), and EtOH (ethanol) and dissolves slowly in acids. Its microhardness is 27 GPa, Knoop hardness is 2600 kg/mm), Young modulus is 379 GPa, and electrical resistivity is greater than 2·10 Ω·m for pure crystals. CaB is a semiconductor with an energy gap estimated as 1.0 eV. The low, semi-metallic conductivity of many CaB samples can be explained by unintentional doping due to impurities and possible non-stoichiometry. | 1 | Solid-state chemistry |
Polyethylene bead foams (including) EPE can be used to replace both polystyrene foam, and both rigid and flexible polyurethane. Uses include cushioning applications, and impact absorption applications including packaging.
Consumption of polyethylene for PE foam was estimated at 114x10 kg in 2001. The majority was used for non-crosslinked foams, but crosslinked PE foams represented a significant (~ one third) fraction of demand. Use in protective packaging represented the largest use sector for such foams. | 0 | Colloidal Chemistry |
The characteristics of the discharge depend on different factors, such as the desalination technology used, salinity and quality of the water used, environmental and oceanographic characteristics, desalination process carried out, among others. The discharge of desalination plants by seawater reverse osmosis (SWRO), are mainly characterized by presenting a salinity concentration that can, in the worst case, double the salinity of the seawater used, and unlike of thermal desalination plants, have practically the same temperature and dissolved oxygen as the seawater used. | 1 | Solid-state chemistry |
Passivation by a dielectric layer on the top of crystalline silicon (c-Si) wafer, also called "tunnel passivation" is one of the passivation techniques used most widely in PV technology. This technique combines both chemical passivation and field-effect passivation. This strategy is based on the formation of a dielectric layer (mostly silicon dioxide SiO, aluminum oxide AlO, or silicon nitride (SiN) on the top of the c-Si substrate be the mean of thermal oxidation or other deposition techniques such as atomic layer deposition (ALD). In the case of the formation of SiO by thermal oxidation, the process acts as chemical passivation since, on the one hand, the formation of the oxide layer reacts with the dangling bonds on the surface wherein it reduces the defects states at the interface. On the other hand, since there are fixed charges (Q) in the dielectric film, these fixed charges establish an electric field that repels one type of charge carrier and accumulates the other type at the interface. This repletion assures reducing one type of the charge carriers concentration at the interface wherein the recombination decreases. | 1 | Solid-state chemistry |
This rationalization is consistent with valence bond theory and suggests a weakened E-E multiple bond. The electron pair is described as resonating between the two group 13 or 14 atoms, and the resonance is favored by occupation of the empty (but not mandatorily vacant) orbital. | 1 | Solid-state chemistry |
The ionic lattice is modeled as an assembly of hard elastic spheres which are compressed together by the mutual attraction of the electrostatic charges on the ions. They achieve the observed equilibrium distance apart due to a balancing short range repulsion. | 1 | Solid-state chemistry |
In terms of the bonding between face sheets and foam core the processing of AFS is categorised into two ways – ex-situ and in-situ bonding. | 0 | Colloidal Chemistry |
* Amino acid-based surfactants are surfactants derived from an amino acid. Their properties vary and can be either anionic, cationic, or zwitterionic, depending on the amino acid used and which part of the amino acid is condensed with the alkyl/aryl chain.
* Gemini surfactants consist of two surfactant molecules linked together at or near their head groups. Compared to monomeric surfactants, they have much lower critical micelle concentrations. | 0 | Colloidal Chemistry |
Hoppe became famous through his synthesis of the stable noble gas compound XeF (xenon difluoride), reported in November 1962. His work followed the previous synthesis of by xenon hexafluoroplatinate by Neil Bartlett, in an experiment run on March 23, 1962 and reported in June of that year. Until then, everyone had assumed that compounds of such kind would not exist, the reason being, first, unsuccessful experiments attempting to synthesize such noble gas compounds and, second, the concept of the "closed octet of electrons", according to which noble gases would not participate in chemical reactions.
Through the properties of the interhalogen compounds it had become obvious that noble gas fluorides were the only accessible ones. Since 1949/50, a research group in Münster had carried out in-depth discussions on the possibility of the formation and the properties of xenon fluorides. This research group was convinced, already in 1951, that XeF and XeF should be thermodynamically stable against the decomposition into the elements.
For a long time it was planned to occasionally perform synthetic experiments targeted at the xenon fluorides. Technical and conceptional difficulties, however, interfered in Münster. On the one hand, xenon was not accessible in sufficient purity; on the other hand, the researchers believed that only pressure syntheses would be successful, for which steel bottles with compressed F were needed. Since 1961, those F-pressure cylinders had been promised by American friends but the transfer could not take place until 1963 because the valves of non-standard U.S. pressure cylinders were not allowed in Germany and vice versa.
Nevertheless, Hoppe’s research group was able to generate XeF in the form of transparent crystals in early 1962. To do so, they let electric sparks impact on xenon-fluorine mixtures. Neil Bartlett tried a similar experiment for the first time in the USA on August 2, 1962. After a few days, he gained xenon tetrafluoride, XeF. | 1 | Solid-state chemistry |
Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear reactors. A mixture of uranium and plutonium dioxides is used as MOX fuel. Prior to 1960, it was used as yellow and black color in ceramic glazes and glass. | 1 | Solid-state chemistry |
Rupp was born in Germany in 1980 and grew up from her youth years in Vienna Austria. Her mother is a language teacher and her father is a physicist, the family is mixed French-German-Italian. She played competitive piano as a child and struggled to choose between pursuing her love for music and natural sciences. Rupp was active in her teen years in an environmental chemistry group and also an Austrian team member competing internationally at the International Young Physicist Team, where they won 3d place in 1998. | 1 | Solid-state chemistry |
While the superposition approximation is actually exact at larger distances, it is no longer accurate at smaller separations. Solutions of the DH or PB equations in between the plates provide a more accurate picture at these conditions. Let us only discuss the symmetric situation within the DH model here. This discussion will introduce the notion of charge regulation, which suggests that the surface charge (and the surface potential) may vary (or regulate) upon approach.
The DH equation can be solved exactly for two plates. The boundary conditions play an important role, and the surface potential and surface charge density
and become functions of the surface separation h and they may differ from the corresponding quantities ψ and σ for the isolated surface. When the surface charge remains constant upon approach, one refers to the constant charge (CC) boundary conditions. In this case, the diffuse layer potential will increase upon approach. On the other hand, when the surface potential is kept constant, one refers to constant potential (CP) boundary condition. In this case, the surface charge density decreases upon approach. Such decrease of charge can be caused by adsorption of desorption of charged ions from the surface. Such variation of adsorbed species upon approach has also been referred to as proximal adsorption. The ability of the surface to regulate its charge can be quantified by the regulation parameter
where C = ε ε κ is the diffuse layer capacitance and C the inner (or regulation) capacitance. The CC conditions are found when p = 1 while the CP conditions for p = 0. The realistic case will be typically situated in between. By solving the DH equation one can show that diffuse layer potential varies upon approach as
while the surface charged density obey a similar relation
The swelling pressure can be found by inserting the exact solution of the DH equation into the expressions above and one finds
Repulsion is strongest for the CC conditions (p = 1) while it is weaker for the CP conditions (p = 0). The result of the superposition approximation is always recovered at larger distances but also for p = 1/2 at all distances. The latter fact explains why the superposition approximation can be very accurate even at small separations. Surfaces regulate their charge and not infrequently the actual regulation parameter is not far away from 1/2.
The situation is exemplified in the figure below. From stability considerations one can show that p < 1 and that this parameter may also becomes negative. These results can be extended to asymmetric case in a straightforward way.
When surface potentials are replaced by effective potentials, this simple DH picture is applicable for more highly charged surfaces at sufficiently larger distances. At shorter distances, however, one may enter the PB regime and the regulation parameter may not remain constant. In this case, one must solve the PB equation together with an appropriate model of the surface charging process. It was demonstrated experimentally that charge regulation effects can become very important in asymmetric systems. | 0 | Colloidal Chemistry |
Methanides are a subset of carbides distinguished by their tendency to decompose in water producing methane. Three examples are aluminium carbide , magnesium carbide and beryllium carbide .
Transition metal carbides are not saline: their reaction with water is very slow and is usually neglected. For example, depending on surface porosity, 5–30 atomic layers of titanium carbide are hydrolyzed, forming methane within 5 minutes at ambient conditions, following by saturation of the reaction.
Note that methanide in this context is a trivial historical name. According to the IUPAC systematic naming conventions, a compound such as NaCH would be termed a "methanide", although this compound is often called methylsodium. See Methyl group#Methyl anion for more information about the anion. | 1 | Solid-state chemistry |
CsAu is obtained by heating a stoichiometric mixture of caesium and gold. The two metallic-yellow liquids react to give a transparent yellow product. Despite being a compound of two metals, CsAu lacks metallic properties since it is a salt with localized charges; it instead behaves as a semiconductor with band gap 2.6 eV.
The compound hydrolyzes readily, yielding caesium hydroxide, metallic gold, and hydrogen.
:2 CsAu + 2 HO → 2 CsOH + 2 Au + H
The solution in liquid ammonia is brown, and the ammonia adduct is blue; the latter has ammonia molecules intercalated between layers of the CsAu crystal parallel to the (110) plane. Solutions undergo metathesis with tetramethylammonium loaded ion exchange resin to give tetramethylammonium auride. | 1 | Solid-state chemistry |
Human cancellous bone possesses a stiffness ranging from 12 to 23 GPa; careful control and modification of manufacturing parameters to achieve similar strengths is imperative for practicality of integration. Correctly predicting the Youngs modulus for foams is imperative for actual biomedical integration; a mismatch of Youngs moduli between the implant and the bone can result in stress-shielding effects from a disproportional handling of stress. The implant which typically exhibits a higher Young's modulus than the bone will absorb most of the load. As a result of this imbalance, the starting bone density will be reduced, there will be tissue death and, eventually, implant failure.
Natural bone exhibits the ability to adjust local fiber away from the low-stress regions toward high stress regions through the distribution of porosity, thus maximizing overall comfort. Using finite element analysis, researchers examined the effect of filling pores with bone on mechanical properties. They concluded that bone ingrowth significantly improved the mechanical properties, evidenced by decreased localized plasticity and stress concentrations. In effect, the titanium foam in the study allowed the bone to exhibit its natural ability to adjust local fiber away from the low-stress regions toward high stress regions.
Experiments demonstrated that random combinations of pore size and shape result in lower Youngs moduli. Theoretical models for the quantification of Youngs moduli do not account for random pore size and shape distribution, so experimental measurements must be conducted in the presence of heterogeneous pore size and distribution. This is a limitation of the micro-mechanical models discussed above. | 0 | Colloidal Chemistry |
In 1818 Berzelius was ennobled by King Carl XIV Johan. In 1835, he received the title of friherre.
In 1820 he was elected a member of the American Philosophical Society.
The Royal Society of London gave Berzelius the Copley Medal in 1836 with the citation "For his systematic application of the doctrine of definite proportions to the analysis of mineral bodies, as contained in his Nouveau Systeme de Mineralogie, and in other of his works."
In 1840, Berzelius was named Knight of the Order of Leopold. In 1842, he received the honor Pour le Mérite for Sciences and Arts.
The mineral berzelianite, a copper selenide, was discovered in 1850 and named after him by James Dwight Dana.
In 1852, Stockholm, Sweden, built a public park and statue, both to honor Berzelius. Berzeliusskolan, a school situated next to his alma mater, Katedralskolan, is named for him. In 1890, a fairly prominent street in Gothenburg was named Berzeliigatan (Berzelii street) in his honour.
In 1898, the Swedish Academy of Sciences opened the Berzelius Museum in honor of Berzelius. The holdings of the museum included many items from his laboratory. The museum was opened on the occasion of fiftieth anniversary of Berzelius's death. Invitees at the ceremony marking the occasion included scientific dignitaries from eleven European nations and the United States, many of whom gave formal addresses in honor of Berzelius. The Berzelius Museum was later moved to the observatory that is part of the Swedish Academy of Sciences.
In 1939 his portrait appeared on a series of postage stamps commemorating the bicentenary of the founding of the Swedish Academy of Sciences. In addition to Sweden, Grenada likewise honored him.
The Berzelius secret society at Yale University is named in his honor. | 1 | Solid-state chemistry |
The equilibrium geometry of any polyatomic system in nondegenerate states is defined as corresponding to the point of the minimum of the adiabatic potential energy surface (APES), where its first derivatives are zero and the second derivatives are positive. If we denote the energy of the system as a function of normal displacements as , at the minimum point of the APES (), the curvature of in direction ,
is positive, i.e., . Very often the geometry of the system at this point of equilibrium on the APES does not coincide with the highest possible (or even with any high) symmetry expected from general symmetry considerations. For instance, linear molecules are bent at equilibrium, planar molecules are puckered, octahedral complexes are elongated, or compressed, or tilted, cubic crystals are tetragonally polarized (or have several structural phases), etc. The PJTE is the general driving force of all these distortions if they occur in the nondegenerate electronic states of the high-symmetry (reference) geometry. If at the reference configuration the system is structurally unstable with respect to some nuclear displacements , then in this direction. The general formula for the energy is , where is the Hamiltonian and is the wavefunction of the nondegenerate ground state. Substituting in Eq. (1), we get (omitting the index for simplicity)
where are the wavefunctions of the excited states, and the expression, obtained as a second order perturbation correction, is always negative, . Therefore, if , the contribution is the only source of instability. The matrix elements in Eq. (4) are off-diagonal vibronic coupling constants,
These measure the mixing of the ground and excited states under the nuclear displacements , and therefore is termed the vibronic contribution. Together with the value and the energy gap between the mixing states, are the main parameters of the PJTE (see below).
In a series of papers beginning in 1980 (see references in ) it was proved that for any polyatomic system in the high-symmetry configuration
and hence the vibronic contribution is the only source of instability of any polyatomic system in nondegenerate states. If for the high-symmetry configuration of any polyatomic system, then a negative curvature, , can be achieved only due to the negative vibronic coupling component , and only if . It follows that any distortion of the high-symmetry configuration is due to, and only to the mixing of its ground state with excited electronic states by the distortive nuclear displacements realized via the vibronic coupling in Eq. (5). The latter softens the system with respect to certain nuclear displacements (), and if this softening is larger than the original (nonvibronic) hardness in this direction, the system becomes unstable with respect to the distortions under consideration, leading to its equilibrium geometry of lower symmetry, or to dissociation.
There are many cases when neither the ground state is degenerate, nor is there a significant vibronic coupling to the lowest excited states to realize PJTE instability of the high-symmetry configuration of the system, and still there is a ground state equilibrium configuration with lower symmetry. In such cases the symmetry breaking is produced by a hidden PJTE (similar to a hidden JTE); it takes place due to a strong PJTE mixing of two excited states, one of which crosses the ground state to create a new (lower) minimum of the APES with a distorted configuration. | 1 | Solid-state chemistry |
The inclusion of nanoparticles in a solid or liquid medium can substantially change its mechanical properties, such as elasticity, plasticity, viscosity, compressibility. | 0 | Colloidal Chemistry |
Using etching techniques such as focused ion beam milling, micro- or nano-sized pillars can be formed in magnetic materials. However, repeated bending of crystal pillars can cause defect formation and fatigue damage. This damage comes from the nucleation of cracks on the pillars surface, even in the elastic regime, due to localized plasticity. Crack propagation during successive compression and tension cycles can lead to pillar fracture. This is similar to what can be seen in cantilever magnetometry when operating under strong fields. Because of this, it is desirable to link smaller magnetic particles together with tougher, elastic materials, such as a polymer, rather than use a continuous alloy filament. | 0 | Colloidal Chemistry |
RapiGest SF, the brand-name for sodium 3-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propanesulfonate, is an acid-cleavable anionic detergent marketed by Waters Corporation and AOBIOUS INC. | 0 | Colloidal Chemistry |
In 1963, he joined Arizona State University where he is now Regents’ Professor of Chemistry. Early research work was devoted to the study of defects, conductivity and diffusion in solids, particularly solid electrolytes. His more recent research is devoted to the theory of periodic structures (nets (periodic graph (crystallography)), tilings (periodic tessellations, and weavings (a higher dimensional version of Braid theory)) relevant to development of a taxonomy of such structures and its application to materials design and description. In collaboration with Omar Yaghi, O’Keeffe developed reticular chemistry, a new branch of chemistry that links molecular fragments of well-defined shapes with strong bonds to build symmetrical open structures such as metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (ZIFs), and covalent organic frameworks (COFs) Together with Olaf Delgado-Friedrichs, he has developed the Reticular Chemistry Structure Resource (RCSR) a compendium of structures relevant to design of materials on the molecular level. O'Keeffe has published three books, including one of the standard monographs on periodic structures, and more than 300 refereed papers. His work is highly cited (over 100,000 citations and h index over 100), and he was third in the Clarivate#Highly Cited Researchers list of Top 100 Chemists, 2000-2010 | 1 | Solid-state chemistry |
Technologically, colloidal crystals have found application in the world of optics as photonic band gap (PBG) materials (or photonic crystals). Synthetic opals as well as inverse opal configurations are being formed either by natural sedimentation or applied forces, both achieving similar results: long-range ordered structures which provide a natural diffraction grating for lightwaves of wavelength comparable to the particle size.
Novel PBG materials are being formed from opal-semiconductor-polymer composites, typically utilizing the ordered lattice to create an ordered array of holes (or pores) which is left behind after removal or decomposition of the original particles. Residual hollow honeycomb structures provide a relative index of refraction (ratio of matrix to air) sufficient for selective filters. Variable index liquids or liquid crystals injected into the network alter the ratio and band gap.
Such frequency-sensitive devices may be ideal for optical switching and frequency selective filters in the ultraviolet, visible, or infrared portions of the spectrum, as well as higher efficiency antennae at microwave and millimeter wave frequencies. | 0 | Colloidal Chemistry |
Alkali metal halides, or alkali halides, are the family of inorganic compounds with the chemical formula MX, where M is an alkali metal and X is a halogen. These compounds are the often commercially significant sources of these metals and halides. The best known of these compounds is sodium chloride, table salt. | 1 | Solid-state chemistry |
Tin(IV) oxide occurs naturally. Synthetic tin(IV) oxide is produced by burning tin metal in air. Annual production is in the range of 10 kilotons. SnO is reduced industrially to the metal with carbon in a reverberatory furnace at 1200–1300 °C. | 1 | Solid-state chemistry |
Microemulsion domains are usually characterized by constructing ternary-phase diagrams.
Three components are the basic requirement to form a microemulsion: two immiscible liquids and a surfactant. The majority of microemulsions use oil and water as immiscible liquid pairs. If a cosurfactant is used, it may sometimes be represented at a fixed ratio to surfactant as a single component, and treated as a single "pseudo-component". The relative amounts of these three components can be represented in a ternary phase diagram. Gibbs phase diagrams can be used to show the influence of changes in the volume fractions of the different phases on the phase behavior of the system.
The three components composing the system are each found at an apex of the triangle, where their corresponding volume fraction is 100%. Moving away from that corner reduces the volume fraction of that specific component and increases the volume fraction of one or both of the two other components. Each point within the triangle represents a possible composition of a mixture of the three components or pseudo-components, which may consist (ideally, according to the Gibbs' phase rule) of one, two or three phases. These points combine to form regions with boundaries between them, which represent the "phase behavior" of the system at constant temperature and pressure.
The Gibbs phase diagram, however, is an empirical visual observation of the state of the system and may, or may not express the true number of phases within a given composition. Apparently clear single phase formulations can still consist of multiple iso-tropic phases (e.g. the apparently clear heptane/AOT/water microemulsions consist multiple phases). Since these systems can be in equilibrium with other phases, many systems, especially those with high volume fractions of both the two imiscible phases, can be easily destabilised by anything that changes this equilibrium e.g. high or low temperature or addition of surface tension modifying agents.
However, examples of relatively stable microemulsions can be found. It is believed that the mechanism for removing acid build up in car engine oils involves low water phase volume, water-in-oil (w/o) microemulsions. Theoretically, transport of the aqueous acid droplets through the engine oil to microdispersed calcium carbonate particles in the oil should be most efficient when the aqueous droplets are small enough to transport a single hydrogen ion (the smaller the droplets, the greater the number of acid water droplets, the faster the neutralisation). Such microemulsions are probably very stable across a reasonably wide range of elevated temperatures. | 0 | Colloidal Chemistry |
The main uses of nephelometers relate to air quality measurement for pollution monitoring, climate monitoring, and visibility. Airborne particles are commonly either biological contaminants, particulate contaminants, gaseous contaminants, or dust.
The accompanying chart shows the types and sizes of various particulate contaminants. This information helps understand the character of particulate pollution inside a building or in the ambient air, as well as the cleanliness level in a controlled environment.
Biological contaminants include mold, fungus, bacteria, viruses, animal dander, dust mites, pollen, human skin cells, cockroach parts, or anything alive or living at one time. They are the biggest enemy of indoor air quality specialists because they are contaminants that cause health problems. Levels of biological contamination depend on humidity and temperature that supports the livelihood of micro-organisms. The presence of pets, plants, rodents, and insects will raise the level of biological contamination. | 0 | Colloidal Chemistry |
With recent attention toward climate change, global warming, and sustainability, there has been a new wave of research regarding the creation and sustainability of biodegradable products. This research has evolved to include the creation of biodegradable biofoams, with the intention to replace other foams that may be environmentally harmful or whose production may be unsustainable. Following this vein, Gunawan et al. conducted research to developed “commercially-relevant polyurethane products that can biodegrade in the natural environment”. One such product includes flip-flops so as part of the research a flip-flop made from algae derived polyurethane was prototyped (see Figure 7). This research ultimately resulted in the conclusion that in both a compost and soil environment (different microorganisms present in each environment) significant degradation occurs in polyurethane foam formulated from algae oil.
Similarly, research has been done where algae oil (AO) and residual palm oil (RPO) have been formulated into foam polyurethane at different ratios to determine what ratio has the optimum biodegradability. RPO is recovered from the waste of palm oil mill and is a byproduct of that manufacturing process. After undergoing a tests to determine biodegradability as well as a thermogravimetric analysis, the team determined that the material could be utilized in applications such as insulation or fire retardants depending on the AO/RPO ratio.
Another focus of biofoam research is the development of biofoams that are not only biodegradable, but are also cost-effective and require less energy to produce. Luo et al. have conducted research in this area of biofoams and have ultimately developed a biofoam that is produced from a “higher content of nature bioresource materials” and using a “minimal [number of] processing steps”. The processing steps include the one-pot method of foam preparation published by F. Zhang and X. Luo in their paper about developing polyurethane biofoams as an alternative to petroleum based foams for specific applications. | 0 | Colloidal Chemistry |
Protein foams contain natural proteins as the foaming agents. Unlike synthetic foams, protein foams are bio-degradable. They flow and spread slower, but provide a foam blanket that is more heat-resistant and more durable.
Protein foams include regular protein foam (P), fluoroprotein foam (FP) (a mixture of protein foam and fluorinated surfactants), film-forming fluoroprotein (FFFP), alcohol-resistant fluoroprotein foam (AR-FP), and alcohol-resistant film-forming fluoroprotein (AR-FFFP). | 0 | Colloidal Chemistry |
By definition, passivation is a treatment process of the surface of the layers to reduce the effects of the surrounding environment. In photovoltaics (PV) technology, passivation is the surface treatment of the wafer or thin film in order to reduce the surface and some of the bulk recombination of the minority carriers. There are two main ways to passivate the surface of the silicon wafer in order to saturate the dangling bonds: field-effect passivation of the surface with a dielectric layer of SiO, also known as \Atalla passivation", and hydrogen passivation, which is one of the chemical methods used for passivation. | 1 | Solid-state chemistry |
Colloidal crystals are receiving increased attention, largely due to their mechanisms of ordering and self-assembly, cooperative motion, structures similar to those observed in condensed matter by both liquids and solids, and structural phase transitions. Phase equilibrium has been considered within the context of their physical similarities, with appropriate scaling, to elastic solids. Observations of the interparticle separation distance has shown a decrease on ordering. This led to a re-evaluation of Langmuir's beliefs about the existence of a long-range attractive component in the interparticle potential.
Colloidal crystals have found application in optics as photonic crystals. Photonics is the science of generating, controlling, and detecting photons (packets of light), particularly in the visible and near Infrared, but also extending to the Ultraviolet, Infrared and far IR portions of the electromagnetic spectrum. The science of photonics includes the emission, transmission, amplification, detection, modulation, and switching of lightwaves over a broad range of frequencies and wavelengths. Photonic devices include electro-optic components such as lasers (Light Amplification by Stimulated Emission of Radiation) and optical fiber. Applications include telecommunications, information processing, illumination, spectroscopy, holography, medicine (surgery, vision correction, endoscopy), military (guided missile) technology, agriculture and robotics.
Polycrystalline colloidal structures have been identified as the basic elements of submicrometre colloidal materials science.
Molecular self-assembly has been observed in various biological systems and underlies the formation of a wide variety of complex biological structures. This includes an emerging class of mechanically superior biomaterials based on microstructure features and designs found in nature.
The principal mechanical characteristics and structures of biological ceramics, polymer composites, elastomers, and cellular materials are being re-evaluated, with an emphasis on bioinspired materials and structures. Traditional approaches focus on design methods of biological materials using conventional synthetic materials. The uses have been identified in the synthesis of bioinspired materials through processes that are characteristic of biological systems in nature. This includes the nanoscale self-assembly of the components and the development of hierarchical structures. | 0 | Colloidal Chemistry |
Angelica M. Stacy is the associate vice provost for the faculty, and professor of chemistry, at University of California, Berkeley. Stacy was one of the first women to receive tenure in the college of chemistry at UC Berkeley.
At UC Berkeley, Stacy leads a research group that explores topics in materials science and chemistry education. Stacy is particularly well known in the community for her contributions to chemistry education research with a specific focus on strategies to increase diversity in the field and STEM more generally. | 1 | Solid-state chemistry |
Titanium dioxide nanoparticles imparts what is known as the self-cleaning effect, which lend useful water-repellant and antibacterial properties to paints and other products. Zinc oxide nanoparticles have been found to have superior UV blocking properties and are widely used in the preparation of sunscreen lotions, being completely photostable though toxic. | 0 | Colloidal Chemistry |
Solubilization is distinct from dissolution because the resulting fluid is a colloidal dispersion involving an association colloid. This suspension is distinct from a true solution, and the amount of the solubilizate in the micellar system can be different (often higher) than the regular solubility of the solubilizate in the solvent.
In non-chemical literature and in everyday language, the term "solubilization" is sometimes used in a broader meaning as "to bring to a solution or (non-sedimenting) suspension" by any means, e.g., leaching by a reaction with an acid. | 0 | Colloidal Chemistry |
CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure. Upon heating it transforms to the zincblende form and the transition temperature decreases from 1045 °C for x = 0 to 805 °C for x = 1. | 1 | Solid-state chemistry |
Band structure calculations take advantage of the periodic nature of a crystal lattice, exploiting its symmetry. The single-electron Schrödinger equation is solved for an electron in a lattice-periodic potential, giving Bloch electrons as solutions
where is called the wavevector. For each value of , there are multiple solutions to the Schrödinger equation labelled by , the band index, which simply numbers the energy bands.
Each of these energy levels evolves smoothly with changes in , forming a smooth band of states. For each band we can define a function , which is the dispersion relation for electrons in that band.
The wavevector takes on any value inside the Brillouin zone, which is a polyhedron in wavevector (reciprocal lattice) space that is related to the crystal's lattice.
Wavevectors outside the Brillouin zone simply correspond to states that are physically identical to those states within the Brillouin zone.
Special high symmetry points/lines in the Brillouin zone are assigned labels like Γ, Δ, Λ, Σ (see Fig 1).
It is difficult to visualize the shape of a band as a function of wavevector, as it would require a plot in four-dimensional space, vs. , , . In scientific literature it is common to see band structure plots which show the values of for values of along straight lines connecting symmetry points, often labelled Δ, Λ, Σ, or [[Miller index|[100], [111], and [110]]], respectively. Another method for visualizing band structure is to plot a constant-energy isosurface in wavevector space, showing all of the states with energy equal to a particular value. The isosurface of states with energy equal to the Fermi level is known as the Fermi surface.
Energy band gaps can be classified using the wavevectors of the states surrounding the band gap:
* Direct band gap: the lowest-energy state above the band gap has the same as the highest-energy state beneath the band gap.
* Indirect band gap: the closest states above and beneath the band gap do not have the same value. | 1 | Solid-state chemistry |
Dispersing trace amounts of nanoparticles into common base fluids has a significant impact on the optical as well as thermo physical properties of base fluid. This characteristic can be used to effectively capture and transport solar radiation. Enhancement of the solar irradiance absorption capacity leads to a higher heat transfer resulting in more efficient heat transfer as shown in figure 2.
The efficiency of a solar thermal system is reliant on several energy conversion steps, which are in turn governed by the effectiveness of the heat transfer processes. While higher conversion efficiency of solar to thermal energy is possible, the key components that need to be improved are the solar collector. An ideal solar collector will absorb the concentrated solar radiation, convert that incident solar radiation into heat and transfer the heat to the heat transfer fluid. Higher the heat transfer to fluid, higher is the outlet temperature and higher temp lead to improved conversion efficiency in the power cycle.
nanoparticles have several orders of magnitude higher heat transfer coefficient when transferring heat immediately to the surrounding fluid. This is simply due to the small size of nanoparticle. | 0 | Colloidal Chemistry |
In 1977 Rustum Roy proposed that the "science and engineering activity of a university ... [be organized] primarily around a dozen permanent mission-oriented interdisciplinary laboratories." To reach this conclusion he notes that "universities have been forced into new interdisciplinary patterns not only by the dollar sign but also by the inexorable logic that the real problems of society do not come in discipline-shaped blocks."
The daunting structural inertia of the university did not faze him:
:A human being, that is both a naked ape and a fallen angel, can manage perhaps to organize the university with both the ivory tower and service-station character. | 1 | Solid-state chemistry |
Soon after the discovery of quasicrystals it was suggested by Linus Pauling that five-fold cyclic twins such as these were the source of the electron diffraction data observed by Dan Shechtman. While there are similarities, quasicrystals are now considered to be a class of packing which is different from fivelings and the related icosahedral particles. | 1 | Solid-state chemistry |
For hard particles, Pauling's rules are useful in understanding the structure of ionic compounds in the early days, and the later entropy maximization principle shows favor of dense packing in the system. Therefore, finding the densest packing for a given shape is a starting point for predicting the structure of hard nanoparticle superlattices. For spherical particles, the densest packings are face-centered cubic and hexagonal close-packed from the Kepler–Hales theorem.
Different particle shapes / polyhedra create diverse complex packing structures in order to minimize the entropy of the system. By computer simulations, four structure categories are classified for faceted polyhedra nanoparticles according to their long-range order and short-range order, which are liquid crystals, plastic crystals, crystals, and disordered structures. | 0 | Colloidal Chemistry |
During the solidification of synthetic biofoams, fibers may be added as a reinforcement agent for the matrix. This additionally will create a heterogeneous nucleation site for the air pockets of the foam itself during the foaming process. However, as fiber content increases, it can begin to inhibit formation of the cellular structure of the matrix. | 0 | Colloidal Chemistry |
Manthiram was born in Amarapuram, Tamil Nadu, a small village in southern India. He completed his B.S. and M.S. degrees in chemistry at Madurai University. He then received his Ph.D. in chemistry from the Indian Institute of Technology, Madras. | 1 | Solid-state chemistry |
Relatively pure YBCO was first synthesized by heating a mixture of the metal carbonates at temperatures between 1000 and 1300 K.
:4 BaCO + Y(CO) + 6 CuCO + (1/2−x) O → 2 YBaCuO + 13 CO
Modern syntheses of YBCO use the corresponding oxides and nitrates.
The superconducting properties of YBaCuO are sensitive to the value of x, its oxygen content. Only those materials with 0 ≤ x ≤ 0.65 are superconducting below T, and when x ~ 0.07, the material superconducts at the highest temperature of 95 K, or in highest magnetic fields: 120 T for B perpendicular and 250 T for B parallel to the CuO planes.
In addition to being sensitive to the stoichiometry of oxygen, the properties of YBCO are influenced by the crystallization methods used. Care must be taken to sinter YBCO. YBCO is a crystalline material, and the best superconductive properties are obtained when crystal grain boundaries are aligned by careful control of annealing and quenching temperature rates.
Numerous other methods to synthesize YBCO have developed since its discovery by Wu and his co-workers, such as chemical vapor deposition (CVD), sol-gel, and aerosol methods. These alternative methods, however, still require careful sintering to produce a quality product.
However, new possibilities have been opened since the discovery that trifluoroacetic acid (TFA), a source of fluorine, prevents the formation of the undesired barium carbonate (BaCO). Routes such as CSD (chemical solution deposition) have opened a wide range of possibilities, particularly in the preparation of long YBCO tapes. This route lowers the temperature necessary to get the correct phase to around . This, and the lack of dependence on vacuum, makes this method a very promising way to get scalable YBCO tapes. | 1 | Solid-state chemistry |
Surfactants affect a wide array of physical properties in paints. Surfactants affect the behavior of a paint not only during the lifetime of the formed coating but also the initial aggregation and film formation of the paint. Surfactants are also used to stabilize the dispersion of polymer particles during emulsion polymerization in paints and other applications. The mechanical stability, freeze-thaw stability and shelf-life of paints are all improved by the addition of surfactants. The addition of surfactants to paint also allow the paint to coat a surface more easily because surfactants increase the wetting of a solution. | 0 | Colloidal Chemistry |
The formation of stable nanoclusters such as Buckminsterfullerene (C) has been suggested to have occurred during the early universe. The first set of experiments to form nanoclusters can be traced back to 1950s and 1960s. During this period, nanoclusters were produced from intense molecular beams at low temperature by supersonic expansion. The development of laser vaporization technique made it possible to create nanoclusters of a clear majority of the elements in the periodic table. Since 1980s, there has been tremendous work on nanoclusters of semiconductor elements, compound clusters and transition metal nanoclusters. | 0 | Colloidal Chemistry |
The first report of a "molybdenum bronze" was by Alfred Stavenhagen and E. Engels in 1895. They reported that electrolysis of molten and gave indigo-blue needles with metallic sheen, which they analysed by weight as . The first unambiguous synthesis of alkali molybdenum bronzes was reported only in 1964, by Wold and others. They obtained two potassium bronzes, "red" and "blue" , by electrolysis of molten + at 550 °C and 560 °C, respectively. Sodium bronzes were also obtained by the same method. It was observed that at a slightly higher temperature (about 575 °C and above) only is obtained.
Another preparation technique involves crystallization from the melt in a temperature gradient. This report also called attention to the marked anisotropic resistivity of the purple lithium bronze and its metal-to-insulator transition at about 24 K.
Hydrogen bronzes were obtained in 1950 by Glemser and Lutz, by ambient-temperature reactions. The hydrogen in these compounds can be replaced by alkali metals by treatment with solutions of the corresponding halides. Reactions are conducted in an autoclave at about 160 °C. | 1 | Solid-state chemistry |
It is known that the response of the surface plasmon polaritons in nanoparticles depends upon their shape. As a consequence decahedral particles have specific optical responses. One suggested use is to improve light adsorption using their plasmonic properties by adding them to polymer solar cells. | 1 | Solid-state chemistry |
Professor Schmidt is recognized as one of the founders of modern organic solid-state chemistry. At the Weizmann Institute, the work of his group centered around the development of X-ray crystallographic methods for the determination of molecular structures in order to understand the properties and reactivity of organic solids.
In the early 1950s, Schmidt investigated the structure and chemistry of over-crowded molecules and their activity. In other studies, he discovered a correlation between the crystalline structure and the symmetry of photochemical products. This finding helped in understanding chemical reactions in organized systems. He then coined the term “topochemistry” for this kind of reaction.
In his research, Schmidt sought to clarify the way by which the structure of molecules affects their packing mode in the crystal. During these studies, he revealed the occurrence of halogen-halogen interactions. Later, he coined the term “crystal engineering,” suggesting that by understanding the ways in which molecules interact, it should be possible to design packing motifs in crystals for rational planning of solid-state reactions. This approach was implemented successfully in the first “absolute” asymmetric synthesis in crystals.
Schmidt's achievements stemmed from his earlier ideas recognizing the importance of combining chemistry with molecular geometry. He also suggested that an ordered arrangement of reactive units in space was the key to understanding biological processes such as photosynthesis and enzymatic activity. | 1 | Solid-state chemistry |
Estropipate is hydrolyzed into estrone in the body. Estrone can then be transformed into estradiol by 17β-hydroxysteroid dehydrogenase. | 1 | Solid-state chemistry |
Many useful compounds are produced by the reactions of hydrocarbons with oxygen, a conversion that is catalyzed by metal oxides. The process operates via the transfer of "lattice" oxygen to the hydrocarbon substrate, a step that temporarily generates a vacancy (or defect). In a subsequent step, the missing oxygen is replenished by O. Such catalysts rely on the ability of the metal oxide to form phases that are not stoichiometric. An analogous sequence of events describes other kinds of atom-transfer reactions including hydrogenation and hydrodesulfurization catalysed by solid catalysts. These considerations also highlight the fact that stoichiometry is determined by the interior of crystals: the surfaces of crystals often do not follow the stoichiometry of the bulk. The complex structures on surfaces are described by the term "surface reconstruction". | 1 | Solid-state chemistry |
A hyclate () is a pharmaceutical term for hydrochloride hemiethanolate hemihydrate (·HCl·EtOH·HO), e.g. doxycycline hyclate. | 1 | Solid-state chemistry |
As of 2014, the classical nucleation theory explained that the nucleation rate will correspond to the driving force One method for measuring the nucleation rate is through the induction time method. This process uses the stochastic nature of nucleation and determines the rate of nucleation by analysis of the time between constant supersaturation and when crystals are first detected. Another method includes the probability distribution model, analogous to the methods used to study supercooled liquids, where the probability of finding at least one nucleus at a given time is derived.
As of 2019, the early stages of nucleation and the rates associated with nucleation were modelled through multiscale computational modeling. This included exploration into an improved kinetic rate equation model and density function studies using the phase-field crystal model. | 0 | Colloidal Chemistry |
Nanoscale particles are used in biomedical applications as drug carriers or imaging contrast agents in microscopy. Anisotropic nanoparticles are a good candidate in biomolecular detection. Moreover, nanoparticles for nucleic acid delivery offer an unprecedented opportunity to overcome some drawbacks related to the delivery, owing to their tunability with diverse physico-chemical properties, they can readily be functionalized with any type of biomolecules/moieties for selective targeting. | 0 | Colloidal Chemistry |
A simple barrier can be created by separating two conductors with a very thin insulator. These are tunnel junctions, the study of which requires understanding quantum tunnelling. Josephson junctions take advantage of quantum tunnelling and superconductivity to create the Josephson effect. This has applications in precision measurements of voltages and magnetic fields, as well as the multijunction solar cell. | 1 | Solid-state chemistry |
Although SnO is insoluble in water, it is amphoteric, dissolving in base and acid. "Stannic acid" refers to hydrated tin (IV) oxide, SnO, which is also called "stannic oxide."
Tin oxides dissolve in acids. Halogen acids attack SnO to give hexahalostannates, such as [SnI]. One report describes reacting a sample in refluxing HI for many hours.
:SnO + 6 HI → HSnI + 2 HO
Similarly, SnO dissolves in sulfuric acid to give the sulfate:
:SnO + 2 HSO → Sn(SO) + 2 HO
The latter compound can add additional hydrogen sulfate ligands to give hexahydrogensulfatostannic acid.
SnO dissolves in strong bases to give "stannates," with the nominal formula NaSnO. Dissolving the solidified SnO/NaOH melt in water gives Na[Sn(OH)], "preparing salt," which is used in the dye industry. | 1 | Solid-state chemistry |
Berzelius was active in the temperance movement. Along with , , Anders Retzius, Samuel Owen, George Scott, and others, he was one of the founders of the Svenska nykterhetssällskapet (the Swedish Temperance Society) in 1837 and its first chairman. Berzelius wrote the foreword to one of works on the topic, of which 50,000 copies were printed. | 1 | Solid-state chemistry |
Sir Anthony Kevin Cheetham (born 16 November 1946) is a British materials scientist. From 2012 to 2017 he was Vice-President and Treasurer of the Royal Society. | 1 | Solid-state chemistry |
Its layered structure resembles that of the brucite polymorph of nickel(II) hydroxide, but with half as many hydrogens. The oxidation state of nickel is 3+. It can be prepared by the reaction of nickel(II) hydroxide with aqueous potassium hydroxide and bromine as the oxidant:
: 2 Ni(OH) + 2 KOH + Br → 2 KBr + 2 HO + 2 NiOOH | 1 | Solid-state chemistry |
In July 2020 scientists reported that they have observed a voltage-induced transformation of normally diamagnetic pyrite into a ferromagnetic material, which may lead to applications in devices such as solar cells or magnetic data storage.
Researchers at Trinity College Dublin, Ireland have demonstrated that FeS can be exfoliated into few-layers just like other two-dimensional layered materials such as graphene by a simple liquid-phase exfoliation route. This is the first study to demonstrate the production of non-layered 2D-platelets from 3D bulk FeS. Furthermore, they have used these 2D-platelets with 20% single walled carbon-nanotube as an anode material in lithium-ion batteries, reaching a capacity of 1000 mAh/g close to the theoretical capacity of FeS.
In 2021, a natural pyrite stone has been crushed and pre-treated followed by liquid-phase exfoliation into two-dimensional nanosheets, which has shown capacities of 1200 mAh/g as an anode in lithium-ion batteries. | 1 | Solid-state chemistry |
NTA has been used by commercial, academic, and government laboratories working with nanoparticle toxicology, drug delivery, exosomes, microvesicles, bacterial membrane vesicles, and other small biological particles, virology and vaccine production, ecotoxicology, protein aggregation, orthopedic implants, inks and pigments, and nanobubbles. | 0 | Colloidal Chemistry |
Prewitt studied geology at Massachusetts Institute of Technology as an undergraduate and received his PhD in 1962 in crystallography at the same place under the supervision of Martin Buerger, where he worked on the structure determination of wollastonites and pectolites. He moved to DuPont Central Research Laboratory in Wilmington, Delaware, where he worked with Robert D. Shannon to compile the effective ionic radii, which became an important foundation of modern crystal chemistry. Afterwards, Prewitt became a professor at Stony Brook University in 1969. In 1986, he was hired by the Carnegie Institute of Science to head the Geophysics Laboratory until 1998. He later became an adjunt faculty member at University of Arizona. | 1 | Solid-state chemistry |
When placed into solution, salts begin to dissolve and form ions. This is not always in equal proportion, due to the preference of an ion to be dissolved in a given solution. The ability of an ion to preferentially dissolve (as a result of unequal activities) over its counterion is classified as the potential determining ion. The properties of this ion are strongly related to the surface potential present on a corresponding solid.
This unequal property between corresponding ions results in a net surface charge. In some cases this arises because one of the ions freely leaves a corresponding solid and the other does not or it is bound to the solid by some other means. Adsorption of an ion to the solid may result in the solid acting as an electrode. (e.g., H and OH on the surfaces of clays).
In a colloidal dispersed system, ion dissolution arises, where the dispersed particles exist in equilibrium with their saturated counterpart, for example:
:NaCl Na + Cl
The behavior of this system is characterised by the components activity coefficients and solubility product:
:a
In clay-aqueous systems the potential of the surface is determined by the activity of ions which react with the mineral surface. Frequently this is the hydrogen ion H in which case the important activity is determined by pH.
The simultaneous adsorption of protons and hydroxyls as well as other potential determining cations and anions, leads to the concept of point of zero charge or PZC, where the total charge from the cations and anions at the surface is equal to zero.
The charge must be zero, and this does not necessarily mean the number of cations versus anions in the solution are equal. For clay minerals the potential determining ions are H and OH and complex ions formed by bonding with H and OH. | 0 | Colloidal Chemistry |
FeO is thermodynamically unstable below 575 °C, tending to disproportionate to metal and FeO:
:* 4FeO → Fe + FeO | 1 | Solid-state chemistry |
*2020 National Academy of Engineering Charles Stark Draper Prize in Engineering
*2019 King Faisal International Prize in Chemistry
*2013 Japan Prize for the "Development of chemically amplified resist polymer materials for innovative semiconductor manufacturing process"
*2010 Grand Prix de la Maison de la Chimie (Paris)
*2010 Erasmus Medal of the Academia Europaea
*2010 Society of Polymer Science of Japan, International Award for the "Development of functional polymers from fundamentals to application"
*2010 University of California Department of Chemistry Teaching Award
*2010 Fellow of the American Chemical Society
*2009 Elected to the Academy of Europe (Academia Europaea)
*2009 Nagoya Gold Medal
*2009 Arun Guthikonda Memorial Award, Columbia University.
*2009 Society of Polymer Science of Japan, International Award for the "Development of functional polymers from fundamentals to applications".
*2009 Carothers Award for "Outstanding contributions and advances in industrial applications of chemistry".
*2009 Herman Mark Award, American Chemical Society.
*2008 D.Sc. (Honoris Causa), University of Liverpool, UK
*2007 Dickson Prize in Science, Carnegie Mellon University
*2007 Arthur C. Cope Award (American Chemical Society award for outstanding achievement in the field of Organic Chemistry)
*2006 Macro Group UK Medal (joint Royal Society for Chemistry and Society of Chemical Industry) for Outstanding Achievement in the field of Macromolecular Chemistry
*2005 Esselen Award for Chemistry in the Service of the Public
*2005 Chemical Communications 40th Anniversary Award
*2004 Docteur de LUniversité, Université dOttawa, Canada
*2003 Henry Rapoport Chair of Organic Chemistry, University of California, Berkeley
*2002 Docteur (Honoris Causa), Université de Lyon I, France
*2001 American Chemical Society, Salute to Excellence Award
*2001 American Chemical Society, A.C. Cope Scholar Award
*2000 Elected Fellow of the American Academy of Arts and Sciences
*2000 Elected Member of the US National Academy of Engineering
*2000 Elected Fellow of the PMSE Division of the American Chemical Society
*2000 Elected Fellow of the American Association for the Advancement of Science
*2000 Elected Member of the US National Academy of Sciences
*2000 American Chemical Society, ACS Award in Polymer Chemistry
*2000 Myron L. Bender & Muriel S. Bender Distinguished Summer Lectureship
*1999 Society of Imaging Science and Technology, Kosar Memorial Award
*1996 American Chemical Society, ACS Award in Applied Polymer Science
*1995 Peter J. Debye Chair of Chemistry, Cornell University, NY
*1994 American Chemical Society, Cooperative Research Award in Polymer Science
*1987 IBM Professor of Polymer Chemistry
*1986 American Chemical Society, Doolittle Award in Polymer Materials Science & Engineering
*1986 Polymer Society of Japan Lecture Award
*1983 IUPAC Canadian National Committee Award | 1 | Solid-state chemistry |
The total volume available for small spheres increases when the excluded volumes around large spheres overlap. The increased volume allotted for small spheres allows them greater translational freedom which increases their entropy. Because the canonical ensemble is an athermal system at a constant volume the Helmholtz free energy is written
where is the Helmholtz free energy, is the entropy and is the temperature. The system's net gain in entropy is positive from increased volume, thus the Helmholtz free energy is negative and depletion flocculation happens spontaneously.
The free energy of the system is obtained from a statistical definition of Helmholtz free energy
where is the partition function for the canonical ensemble. The partition function contains statistical information that describes the canonical ensemble including its total volume, the total number of small spheres, the volume available for small spheres to occupy, and the de Broglie wavelength. If hard-spheres are assumed, the partition function is
The volume available for small spheres, was calculated above. is the number of small spheres and is the de Broglie wavelength. Substituting into the statistical definition, the Helmholtz free energy now reads
The magnitude of the depletion force, is equal to the change in Helmholtz free energy with distance between two large spheres and is given by
The entropic nature of depletion forces was proven experimentally in some cases. For example, some polymeric crowders induce entropic depletion forces that stabilize proteins in their native state.
Other examples include many systems with hard-core only interactions. | 0 | Colloidal Chemistry |
In chemistry, an adduct (; alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species. Examples include the addition of sodium bisulfite to an aldehyde to give a sulfonate. It can be considered as a single product resulting from the direct combination of different molecules which comprises all atoms of the reactant molecules.
Adducts often form between Lewis acids and Lewis bases. A good example is the formation of adducts between the Lewis acid borane and the oxygen atom in the Lewis bases, tetrahydrofuran (THF): or diethyl ether: . Many Lewis acids and Lewis bases reacting in the gas phase or in non-aqueous solvents to form adducts have been examined in the ECW model. Trimethylborane, trimethyltin chloride and bis(hexafluoroacetylacetonato)copper(II) are examples of Lewis acids that form adducts which exhibit steric effects. For example: trimethyltin chloride, when reacting with diethyl ether, exhibits steric repulsion between the methyl groups on the tin and the ethyl groups on oxygen. But when the Lewis base is tetrahydrofuran, steric repulsion is reduced. The ECW model can provide a measure of these steric effects.
Compounds or mixtures that cannot form an adduct because of steric hindrance are called frustrated Lewis pairs.
Adducts are not necessarily molecular in nature. A good example from solid-state chemistry is the adducts of ethylene or carbon monoxide of . The latter is a solid with an extended lattice structure. Upon formation of the adduct, a new extended phase is formed in which the gas molecules are incorporated (inserted) as ligands of the copper atoms within the structure. This reaction can also be considered a reaction between a base and a Lewis acid with the copper atom in the electron-receiving role and the pi electrons of the gas molecule in the electron-donating role. | 1 | Solid-state chemistry |
Surfaces of silicon, germanium, graphite (carbon) and germanium-silicide are active in EPR measurements.
Mainly group 14 (formerly group IV) elements show EPR signals from a surface after crushing. Crystals of elements from groups 13 to 15 prefer to have the (110) plane exposed as a surface. On this surface, an atom of group 13 has 3/4 dangling bond, and an atom of group 15 has 5/4 dangling bond. Because of dehybridization of surface orbitals (caused by the decreased number of nearest neighbor atoms around the surface atom), a group 13 atom will have a largely unfilled dangling orbital since it has valence 3 and makes three bonds, while a group 15 atom will have a fully occupied dangling orbital at the surface. In that case, there is hardly any unpaired electron density, which results in a weak EPR signal for such materials.
Clean cleaved surfaces of such materials form paired electron localized states on alternate sites resulting in a very weak to no EPR signal. Not well-cleaved surfaces and microcracks obtained from crushing, cleaving, abrading, neutron or high-energy ion irradiation or heating and rapid cooling in vacuum give a measurable EPR signal (a characteristic signal in Si at g = 2,0055). The presence of oxygen and hydrogen gas affects the EPR signal from microcracks by affecting the single electron spin centers. The gas molecules can get trapped and, when staying close to a spin center, affect the EPR signal. When a microcrack is sufficiently small, the wave functions of the dangling bond states extend beyond the surface and can overlap with wave functions from the opposite surface. This can create shear forces in the crystal surface, causing atom layers to realign while creating dangling bonds in the process.
Due to the reactivity of dangling bonds, the semiconductor native oxide will form due to adsorption of gas molecules, the only remaining dangling bonds are located at oxygen vacancies. Dangling bonds form an sp-hybridized bond with the adsorbed molecule, which have a metallic character. They are often the only defect sites present on atomic semiconductors, which provide such "soft centers" for molecules to adsorb to. When no gas adsorption is possible (for example for clean surfaces in vacuum), the surface energy can be reduced by reorganizing bonding electrons, creating lattice strain in the process. In case of the (001) surface plane of silicon, a single dangling bond on each atom will be formed, while pairing the other electron with a neighboring atom.
Removal of dangling bond surface states on the silicon (001) surface from the band gap can be achieved by treatment of the surface with a monolayer of selenium (alternatively, sulfur was proposed). Selenium can attach to the silicon (001) surface and can bind to surface dangling bonds, bridging between silicon atoms. This releases the strain in the silicon surface and terminates the dangling bonds, covering them from the outside environment.
When exposed, dangling bonds can act as surface states in electronic processes. | 1 | Solid-state chemistry |
Michael Faraday provided the first description, in scientific terms, of the optical properties of nanometer-scale metals in his classic 1857 paper. In a subsequent paper, the author (Turner) points out that: "It is well known that when thin leaves of gold or silver are mounted upon glass and heated to a temperature that is well below a red heat (~500 °C), a remarkable change of properties takes place, whereby the continuity of the metallic film is destroyed. The result is that white light is now freely transmitted, reflection is correspondingly diminished, while the electrical resistivity is enormously increased." | 0 | Colloidal Chemistry |
In some jurisdictions, most bitterns are used for other production instead of being directly discarded. In other jurisdictions each tonne of salt produced can create 3+ tonnes of waste bitterns.
Although bittern generally contains the same compounds as seawater, it is much more concentrated than seawater. If bittern is released directly into seawater, the ensuing salinity increase may harm marine life around the point of release. Even small increases in salinity can disrupt marine species' osmotic balances, which may result in the death of the organism in some cases.
In December 1997, 94 corpses of green sea turtles, Chelonia mydas, were found at the Ojo de Liebre Lagoon (OLL) in Mexico, adjacent to the industrial operation of Exportadora de Sal S.A. (ESSA), the largest saltworks in the world. The fluoride ion F content in bitterns was 60.5-fold more than that in seawater. The bitterns osmolality was 11,000 mosm/kg of water, whereas the turtle's plasma osmolality was about 400 mosm/kg of water. Researchers concluded that the dumping of bitterns into the ocean should be avoided.
The lack of adequate disposal methods for bitterns and concerns of local commercial and recreational fishing associations about bitterns’ deleterious impacts upon local fish and prawn hatchery areas led the Western Australian EPA in 2008 to recommend against the proposed 4.2 million tonne per annum Straits Salt project in The Pilbara region of WA. The EPA concluded that: | 1 | Solid-state chemistry |
A coalescer is a device which induces coalescence in a medium. They are primarily used to separate emulsions into their components via various processes, operating in reverse to an emulsifier.
Coalescers are of two main types: mechanical and electrostatic. Mechanical coalescers use filters or baffles to make droplets coalesce, while electrostatic coalescers use DC or AC electric fields (or combinations). | 0 | Colloidal Chemistry |
The so-called flexible polyurethane foam (FPF) is produced from the reaction of polyols and isocyanates, a process pioneered in 1937. FPF allows for some compression and resilience that provides a cushioning effect. Because of this property, it is often used in furniture, bedding, automotive seating, athletic equipment, packaging, footwear and carpets. | 0 | Colloidal Chemistry |
Scientists have devised a large number of nanowire compositions with controlled length, diameter, doping, and surface structure by using vapor and solution phase strategies. These oriented single crystals are being used in semiconductor nanowire devices such as diodes, transistors, logic circuits, lasers, and sensors. Since nanowires have a one-dimensional structure, meaning a large surface-to-volume ratio, the diffusion resistance decreases. In addition, their efficiency in electron transport which is due to the quantum confinement effect, makes their electrical properties be influenced by minor perturbation. Therefore, the use of these nanowires in nanosensor elements increases the sensitivity in electrode response. As mentioned above, the one-dimensionality and chemical flexibility of the semiconductor nanowires make them applicable in nanolasers. Peidong Yang and his co-workers have done some research on the room-temperature ultraviolet nanowires used in nanolasers. They have concluded that using short wavelength nanolasers has applications in different fields such as optical computing, information storage, and microanalysis. | 0 | Colloidal Chemistry |
The early development of this type of complex takes place around the turn of the 19th century. In 1886 Janovski observed an intense violet color when he mixed meta-dinitrobenzene with an alcoholic solution of alkali. In 1895 Cornelis Adriaan Lobry van Troostenburg de Bruyn investigated a red substance formed in the reaction of trinitrobenzene with potassium hydroxide in methanol. In 1900 Jackson and Gazzolo reacted trinitroanisole with sodium methoxide and proposed a quinoid structure for the reaction product.
In 1902 Jakob Meisenheimer observed that by acidifying their reaction product, the starting material was recovered.
With three electron withdrawing groups, the negative charge in the complex is located at one of the nitro groups according to the quinoid model. When less electron poor arenes this charge is delocalized over the entire ring (structure to the right in scheme 1).
In one study a Meisenheimer arene (4,6-dinitrobenzofuroxan) was allowed to react with a strongly electron-releasing arene (1,3,5-tris(N-pyrrolidinyl)benzene) forming a zwitterionic Meisenheimer–Wheland complex. The Wheland intermediate is the name typically given to the cationic reactive intermediate formed in electrophilic aromatic substitution, and can be considered an oppositely charged analog of the negatively charged Meisenheimer complex formed in nucleophilic aromatic substitution. Hence, the simultaneous occurrence of the Wheland and Meisenheimer intermediates in the single zwitterionic complex shown below lead to its description as a Meisenheimer–Wheland complex.
The structure of this complex was confirmed by NMR spectroscopy. | 1 | Solid-state chemistry |
There are 2 main application techniques of applying foam onto a fire, recognized by the European (EN1568) and international (ISO7203) standards:
Sweep (roll-on) method - Use only on a pool of flammable product on open ground. Direct the foam stream onto the ground in front of the product involved. May need to move the hose line or use multiple lines to cover the material. If multiple lines are used, be aware of other firefighters in the area.
Bankshot (bankdown) method - Firefighter uses an object to deflect the foam stream so it flows down the burning surface. Application should be as gentle as possible. Direct the foam at a vertical object. Allow the foam to spread over the material and form a foam blanket.
Raindown method - Used when unable to employ the bankshot method or the roll-on method. Loft the foam stream into the air above the material and let it fall gently onto the surface. Effective as long as the foam stream completely covers the material. Might not be effective if wind conditions are unfavorable | 0 | Colloidal Chemistry |
*Integrated Drug Discovery Technologies. Mei, H.-Y., Czarnik, A.W., Eds.; Marcel Dekker: New York, NY, 2002.
*Optimization of Solid-Phase Combinatorial Synthesis. Yan, B., Czarnik, A.W., Eds.; Wiley: New York, NY, 2002.
*Solid-Phase Organic Syntheses. Volume 1. Czarnik, A.W., Ed.; Wiley: New York, NY, 2001.
*A Practical Guide to Combinatorial Chemistry. DeWitt, S.H., Czarnik, A.W., Eds.; ACS Books: Washington, DC, 1997.
*Combinatorial Chemistry: Synthesis and Application. Wilson, S.H., Czarnik, A.W., Eds.; Wiley & Sons: New York, NY, 1997.
*Chemosensors of Ion and Molecular Recognition. Desvergne, J.-P., Czarnik, A.W., Eds.; NATO ASI Series, Series C: Vol. 492; Kluwer Academic Press: Dordrecht, 1997.
*Fluorescent Chemosensors for Ion and Molecule Recognition. Czarnik, A.W., Ed.; Vol. 538, ACS Books: Washington, DC, 1993 | 1 | Solid-state chemistry |
When applied to organic molecules, NMR crystallography aims at including structural information not only of a single molecule but also on the molecular packing (i.e. crystal structure). Contrary to X-ray, single crystals are not necessary with solid-state NMR and structural information can be obtained from high-resolution spectra of disordered solids. E.g. polymorphism is an area of interest for NMR crystallography since this is encountered occasionally (and may often be previously undiscovered) in organic compounds. In this case a change in the molecular structure and/or in the molecular packing can lead to polymorphism, and this can be investigated by NMR crystallography. | 1 | Solid-state chemistry |
The colored bubble solution uses special dyes called leuco dyes. For instance, the purple bubble uses a chemical called crystal violet lactone. After the bubble pops, the colored splatter disappears with friction, water or exposure to air.
In a normal soap bubble, surfactants reduce the surface tension of the water and allow the bubble to form. To create a colored bubble, dye molecules must bond to the surfactants. Each dye molecule in Zubbles is a structure known as a lactone ring. When the ring is closed, the molecule absorbs all visible light except for the color of the bubble. However, subjecting the lactone ring to air, water, or pressure causes the ring to open. This changes the molecule's structure to a straight chain which absorbs no visible light.
Lactone rings can be produced whenever a long chain molecule contains acid functionality on one end, and alcohol functionality at the other. The two ends of the molecule react in a condensation reaction, ejecting a water molecule. To drive the reaction back towards the long chain, pressure, heat or an excess of water must be added. | 0 | Colloidal Chemistry |
In order to gain enough electrons to fill their valence shells (see also octet rule), many atoms will form covalent bonds with other atoms. In the simplest case, that of a single bond, two atoms each contribute one unpaired electron, and the resulting pair of electrons is shared between them. Atoms that possess too few bonding partners to satisfy their valences and that possess unpaired electrons are termed "free radicals"; so, often, are molecules containing such atoms. When a free radical exists in an immobilized environment (for example, a solid), it is referred to as an "immobilized free radical" or a "dangling bond".
A dangling bond in (bulk) crystalline silicon is often pictured as a single unbound hybrid sp orbital on the silicon atom, with the other three sp orbitals facing away from the unbound orbital. In reality, the dangling bond unbound orbital is better described by having more than half of the dangling bond wave function localized on the silicon nucleus, with delocalized electron density around the three bonding orbitals, comparable to a p-orbital with more electron density localized on the silicon nucleus. The three remaining bonds tend to shift to a more planar configuration. It has also been found in experiments that Electron Paramagnetic Resonance (EPR) spectra of amorphous hydrogenated silicon (a-Si:H) do not differ significantly from the deuterated counterpart, a-Si:D, suggesting that there is hardly any backbonding to the silicon from hydrogen on a dangling bond. It also appeared that the Si-Si and Si-H bonds are about equally strong. | 1 | Solid-state chemistry |
Alivisatos is married to Nicole Alivisatos, a retired chemist, former editor of the journal Nano Letters, and daughter of the noted chemist, Gábor A. Somorjai. They have two daughters. | 1 | Solid-state chemistry |
As the aggregation process continues, larger clusters form. The growth occurs mainly through encounters between different clusters, and therefore one refers to cluster-cluster aggregation process. The resulting clusters are irregular, but statistically self-similar. They are examples of mass fractals, whereby their mass M grows with their typical size characterized by the radius of gyration R as a power-law
where d is the mass fractal dimension. Depending whether the aggregation is fast or slow, one refers to diffusion limited cluster aggregation (DLCA) or reaction limited cluster aggregation (RLCA). The clusters have different characteristics in each regime. DLCA clusters are loose and ramified (d ≈ 1.8), while the RLCA clusters are more compact (d ≈ 2.1). The cluster size distribution is also different in these two regimes. DLCA clusters are relatively monodisperse, while the size distribution of RLCA clusters is very broad.
The larger the cluster size, the faster their settling velocity. Therefore, aggregating particles sediment and this mechanism provides a way for separating them from suspension. At higher particle concentrations, the growing clusters may interlink, and form a particle gel. Such a gel is an elastic solid body, but differs from ordinary solids by having a very low elastic modulus. | 0 | Colloidal Chemistry |
UFPs are both manufactured and naturally occurring. Hot volcanic lava, ocean spray, and smoke are common natural UFPs sources. UFPs can be intentionally fabricated as fine particles to serve a vast range of applications in both medicine and technology. Other UFPs are byproducts, like emissions, from specific processes, combustion reactions, or equipment such as printer toner and automobile exhaust. Anthropogenic sources of UFPs include combustion of gas, coal or hydrocarbons, biomass burning (i.e. agricultural burning, forest fires and waste disposal), vehicular traffic and industrial emissions, tire wear and tear from car brakes, air traffic, seaport, maritime transportation, construction, demolition, restoration and concrete processing, domestic wood stoves, outdoor burning, kitchen, and cigarette smoke. In 2014, an air quality study found harmful ultrafine particles from the takeoffs and landings at Los Angeles International Airport to be of much greater magnitude than previously thought. There are a multitude of indoor sources that include but are not limited to laser printers, fax machines, photocopiers, the peeling of citrus fruits, cooking, tobacco smoke, penetration of contaminated outdoor air, chimney cracks and vacuum cleaners.
UFPs have a variety of applications in the medical and technology fields. They are used in diagnostic imagining, and novel drug delivery systems that include targeting the circulatory system, and or passage of the blood brain barrier to name just a few. Certain UFPs like silver based nanostructures have antimicrobial properties that are exploited in wound healing and internal instrumental coatings among other uses, in order to prevent infections. In the area of technology, carbon based UFPs have a plethora of applications in computers. This includes the use of graphene and carbon nanotubes in electronic as well as other computer and circuitry components. Some UFPs have characteristics similar to gas or liquid and are useful in powders or lubricants. | 0 | Colloidal Chemistry |
Pyrite enjoyed brief popularity in the 16th and 17th centuries as a source of ignition in early firearms, most notably the wheellock, where a sample of pyrite was placed against a circular file to strike the sparks needed to fire the gun.
Pyrite is used with flintstone and a form of tinder made of stringybark by the Kaurna people of South Australia, as a traditional method of starting fires.
Pyrite has been used since classical times to manufacture copperas (ferrous sulfate). Iron pyrite was heaped up and allowed to weather (an example of an early form of heap leaching). The acidic runoff from the heap was then boiled with iron to produce iron sulfate. In the 15th century, new methods of such leaching began to replace the burning of sulfur as a source of sulfuric acid. By the 19th century, it had become the dominant method.
Pyrite remains in commercial use for the production of sulfur dioxide, for use in such applications as the paper industry, and in the manufacture of sulfuric acid. Thermal decomposition of pyrite into FeS (iron(II) sulfide) and elemental sulfur starts at ; at around , p</sub> is about .
A newer commercial use for pyrite is as the cathode material in Energizer brand non-rechargeable lithium metal batteries.
Pyrite is a semiconductor material with a band gap of 0.95 eV. Pure pyrite is naturally n-type, in both crystal and thin-film forms, potentially due to sulfur vacancies in the pyrite crystal structure acting as n-dopants.
During the early years of the 20th century, pyrite was used as a mineral detector in radio receivers, and is still used by crystal radio hobbyists. Until the vacuum tube matured, the crystal detector was the most sensitive and dependable detector available—with considerable variation between mineral types and even individual samples within a particular type of mineral. Pyrite detectors occupied a midway point between galena detectors and the more mechanically complicated perikon mineral pairs. Pyrite detectors can be as sensitive as a modern 1N34A germanium diode detector.
Pyrite has been proposed as an abundant, non-toxic, inexpensive material in low-cost photovoltaic solar panels. Synthetic iron sulfide was used with copper sulfide to create the photovoltaic material. More recent efforts are working toward thin-film solar cells made entirely of pyrite.
Pyrite is used to make marcasite jewelry. Marcasite jewelry, made from small faceted pieces of pyrite, often set in silver, was known since ancient times and was popular in the Victorian era. At the time when the term became common in jewelry making, "marcasite" referred to all iron sulfides including pyrite, and not to the orthorhombic FeS mineral marcasite which is lighter in color, brittle and chemically unstable, and thus not suitable for jewelry making. Marcasite jewelry does not actually contain the mineral marcasite. The specimens of pyrite, when it appears as good quality crystals, are used in decoration. They are also very popular in mineral collecting. Among the sites that provide the best specimens are Soria and La Rioja provinces (Spain).
In value terms, China ($47 million) constitutes the largest market for imported unroasted iron pyrites worldwide, making up 65% of global imports. China is also the fastest growing in terms of the unroasted iron pyrites imports, with a CAGR of +27.8% from 2007 to 2016. | 1 | Solid-state chemistry |
In 1953, Roy wrote a letter to Life magazine in response to the essay "Is Academic Freedom in Danger?" by Whittaker Chambers, stating: | 1 | Solid-state chemistry |
Gallium(II) selenide (GaSe) is a chemical compound. It has a hexagonal layer structure, similar to that of GaS. It is a photoconductor, a second harmonic generation crystal in nonlinear optics, and has been used as a far-infrared conversion material at 14–31 THz and above. | 1 | Solid-state chemistry |
Michael O’Keeffe (born April 3, 1934) is a British-American chemist. He is currently Regents’ Professor Emeritus in the School of Molecular Sciences at Arizona State University. As a scientist, he is particularly known for his contributions to the field of reticular chemistry. In 2019, he received the Gregori Aminoff Prize in Crystallography from the Royal Swedish Academy of Sciences. | 1 | Solid-state chemistry |
There are many possible thermodynamically stable fuel-oxidizer combinations. Some of them are:
* Aluminium-molybdenum(VI) oxide
* Aluminium-copper(II) oxide
* Aluminium-iron(II,III) oxide
* Antimony-potassium permanganate
* Aluminium-potassium permanganate
* Aluminium-bismuth(III) oxide
* Aluminium-tungsten(VI) oxide hydrate
* Aluminium-fluoropolymer (typically Viton)
* Titanium-boron (burns to titanium diboride, which belongs to a class of compounds called intermetallic composites).
In military research, aluminium-molybdenum oxide, aluminium-Teflon and aluminium-copper(II) oxide have received considerable attention. Other compositions tested were based on nanosized RDX and with thermoplastic elastomers. PTFE or other fluoropolymer can be used as a binder for the composition. Its reaction with the aluminium, similar to magnesium/teflon/viton thermite, adds energy to the reaction. Of the listed compositions, that with potassium permanganate has the highest pressurization rate.
The most common method of preparing nanoenergetic materials is by ultrasonification in quantities of less than 2g. Some research has been developed to increase production scales. Due to the very high electrostatic discharge (ESD) sensitivity of these materials, sub 1 gram scales are currently typical. | 0 | Colloidal Chemistry |
Hazen has 289 refereed publications that have been cited a total of over 11,000 times, for an h-index of 58. A selection of articles follows: | 1 | Solid-state chemistry |
Some concerns relating to hydrogels infused with nanoparticles are the chances of either bursting, or of incomplete release of drugs. Although hydrogels infused with nanoparticles are speculated to be quite promising methods of drug, protein, peptide, oligosaccharide, vaccine, and nucleic acid delivery, more studies regarding nanotoxicology and safety are required before clinical applications can be pursued. Further, to avoid accumulation, biodegradable gels and nanoparticles are highly desirable. | 0 | Colloidal Chemistry |
Sodium ethyl xanthate has moderate oral and dermal toxicity in animals and is irritating to eyes and skin. It is especially toxic to aquatic life and therefore its disposal is strictly controlled. Median lethal dose for (male albino mice, oral, 10% solution at pH~11) is 730 mg/kg of body weight, with most deaths occurring in the first day. The most affected organs were the central nervous system, liver and spleen.
Since 1993, sodium ethyl xanthate is classified as a Priority Existing Chemical in Australia, meaning that its manufacture, handling, storage, use or disposal may result in adverse health or environment effects. This decision was justified by the widespread use of the chemical in industry and its decomposition to the toxic and flammable carbon disulfide gas. From two examples of sodium ethyl xanthate spillage in Australia, one resulted in evacuation of 100 people and hospitalization of 6 workers who were exposed to the fumes. In another accident, residents of the spillage area complained of headache, dizziness, and nausea. Consequently, during high-risk sodium ethyl xanthate handling operations, workers are required by the Australian regulations to be equipped with protective clothing, anti-static gloves, boots and full-face respirators or self-contained breathing apparatus. | 1 | Solid-state chemistry |
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