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Ceramic matrix composites (CMCs) consist of ceramic fibers embedded in a ceramic matrix. The matrix and fibers can consist of any ceramic material, including carbon and carbon fibers. The ceramic occupying most of the volume is often from the group of oxides, such as nitrides, borides, silicides, whereas the second component is often a metal. Ideally both components are finely dispersed in each other in order to elicit particular optical, electrical and magnetic properties as well as tribological, corrosion-resistance and other protective properties.
The binary phase diagram of the mixture should be considered in designing ceramic-metal nanocomposites and measures have to be taken to avoid a chemical reaction between both components. The last point mainly is of importance for the metallic component that may easily react with the ceramic and thereby lose its metallic character. This is not an easily obeyed constraint because the preparation of the ceramic component generally requires high process temperatures. The safest measure thus is to carefully choose immiscible metal and ceramic phases. A good example of such a combination is represented by the ceramic-metal composite of TiO and Cu, the mixtures of which were found immiscible over large areas in the Gibbs’ triangle of ' Cu-O-Ti.
The concept of ceramic-matrix nanocomposites was also applied to thin films that are solid layers of a few nm to some tens of µm thickness deposited upon an underlying substrate and that play an important role in the functionalization of technical surfaces. Gas flow sputtering by the hollow cathode technique turned out as a rather effective technique for the preparation of nanocomposite layers. The process operates as a vacuum-based deposition technique and is associated with high deposition rates up to some µm/s and the growth of nanoparticles in the gas phase. Nanocomposite layers in the ceramics range of composition were prepared from TiO and Cu by the hollow cathode technique that showed a high mechanical hardness, small coefficients of friction and a high resistance to corrosion. | 1 | Solid-state chemistry |
The head group classification of a surfactant is determined by the head group ion type. Ionic surfactants derive their amphiphilicity from a charged hydrophilic head group and tend to be small, low molecular weight molecules. Ionic surfactants will stabilize particles suspended in a paint by electrostatic repulsion and are easily adsorbed and desorbed from a surface due to their small size.
Anionic head groups are negatively charged, and commonly used in cleaning products. Anionic surfactants can be found in products such as shampoos, laundry detergents, and soaps because of their ability to remove dirt from soft mediums such as fabric. Anionic surfactants are easily suspended in water due to the polarity of the charged head group. However, hard water can deactivate the molecule. Some of the more commonly used anionic head groups are sulfates and ethoxylates.
Cationic head groups have a positive charge and cationic surfactants are used in several different applications. One common use for cationic surfactants is in fabric softeners. Cationic head groups are also added to laundry detergent in conjunction with anionic surfactants because they help to improve the dirt removal properties of the anionic surfactants. Cationic head groups also increase the disinfecting properties of household cleaners. Some common cationic surfactants head groups include amines and quaternary ammonium ions.
Among the many types of surfactants, cationic surfactants are very useful corrosion inhibitors due of their protective effectiveness in neutral and acidic media.
Nonionic head groups have no charge and they function very well as grease removers. Nonionic surfactants are commonly used in detergents, soaps, and household cleaners. In solutions of hard water, nonionic surfactants are used to help limit the deactivation of ionic surfactants caused by the calcium and magnesium ions. Some common nonionic surfactant head groups include fatty acids and glycols. | 0 | Colloidal Chemistry |
Maximilian Fichtner (born 1961 in Heidelberg, Germany) is professor for Solid State Chemistry at the Ulm University and executive director of the Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU). | 1 | Solid-state chemistry |
Taurates are used as mild, well-foaming surfactants in body cleansing and personal care products (shampoos, liquid soaps and cleansers, face lotions, skin creams, bubble baths, syndet soaps), textile processing (wetting agents and detergents, dye dispersants), in crop protection formulations and in other industrial applications. | 0 | Colloidal Chemistry |
In chemistry, perxenates are salts of the yellow xenon-containing anion . This anion has octahedral molecular geometry, as determined by Raman spectroscopy, having O–Xe–O bond angles varying between 87° and 93°. The Xe–O bond length was determined by X-ray crystallography to be 1.875 Å. | 1 | Solid-state chemistry |
Rundle was born in Orleans, Nebraska in 1915. He attended University of Nebraska where he completed a bachelor of science in 1937 and a master's degree in 1938. He completed a Ph.D. in 1941 at the California Institute of Technology. His advisors were Linus Pauling and J. Holmes Sturdivant. | 1 | Solid-state chemistry |
Cobalt oxide is often obtained by hydrothermal synthesis in an autoclave.
One-pot hydrothermal synthesis of metal oxide hollow spheres starts with carbohydrates and metal salts dissolved in water at 100-200 °C. The reaction produces carbon spheres, with metal ions integrated into the hydrophobic shell. The carbon cores are removed by calcination, leaving hollow metal oxide spheres. Surface area and thickness of the shell can be manipulated by varying the carbohydrate to metal salt concentration, as well as the temperature, pressure, and pH of the reaction medium, and the cations of the starting salts. The completion time for the procedure varies from hours to days.
A drawback of this approach is its smaller yield compared to other methods. | 1 | Solid-state chemistry |
Berzelius is credited with originating the chemical terms "catalysis", "polymer," "isomer," "protein" and "allotrope," although his original definitions in some cases differ significantly from modern usage. As an example, he coined the term "polymer" in 1833 to describe organic compounds which shared identical empirical formulas but which differed in overall molecular weight, the larger of the compounds being described as "polymers" of the smallest. At this time the concept of chemical structure had not yet been developed so that he considered only the numbers of atoms of each element. In this way, he viewed for example glucose (CHO) as a polymer of formaldehyde (CHO), even though we now know that glucose is not a polymer of the monomer formaldehyde. | 1 | Solid-state chemistry |
The following table presents a list of lattice energies for some common compounds as well as their structure type. | 1 | Solid-state chemistry |
On 29 February 2012, Sadoway gave a TED talk on his invention of the liquid metal battery for grid-scale storage. The talk is as much about the inventive process as it is about the technology.
Sadoway was named one of Time magazine's 100 Most Influential People in the World in 2012 for accomplishments in energy storage as well as his approach to mentoring students (hire the novice instead of the expert).
On 22 October 2012, Sadoway appeared as a guest on The Colbert Report to discuss his liquid metal battery technology and his view that electrochemistry is the key to world peace (batteries usher in the electric age reducing the dependence on petroleum dropping its price thereby destabilizing dictatorships).
Sadoway appeared in "MIT Gangnam Style". | 1 | Solid-state chemistry |
For dilute suspensions, Stokes law predicts the settling velocity of small spheres in fluid, either air or water. This originates due to the strength of viscous forces at the surface of the particle providing the majority of the retarding force. Stokes law finds many applications in the natural sciences, and is given by:
where w is the settling velocity, ρ is density (the subscripts p and f indicate particle and fluid respectively), g is the acceleration due to gravity, r is the radius of the particle and μ is the dynamic viscosity of the fluid.
Stokes law applies when the Reynolds number, Re, of the particle is less than 0.1. Experimentally Stokes law is found to hold within 1% for , within 3% for and within 9% . With increasing Reynolds numbers, Stokes law begins to break down due to the increasing importance of fluid inertia, requiring the use of empirical solutions to calculate drag forces. | 0 | Colloidal Chemistry |
Counterions are the mobile ions in ion exchange polymers and colloids. Ion-exchange resins are polymers with a net negative or positive charge. Cation-exchange resins consist of an anionic polymer with countercations, typically Na (sodium). The resin has a higher affinity for highly charged countercations, for example by Ca (calcium) in the case of water softening. Correspondingly, anion-exchange resins are typically provided in the form of chloride Cl, which is a highly mobile counteranion.
Counterions are used in phase-transfer catalysis. In a typical application lipophilic countercation such as benzalkonium solubilizes reagents in organic solvents. | 1 | Solid-state chemistry |
Some new instrumentations techniques exist that allow zeta potential to be measured. The Zeta Potential Analyzer can measure solid, fibers, or powdered material. The motor found in the instrument creates an oscillating flow of electrolyte solution through the sample. Several sensors in the instrument monitor other factors, so the software attached is able to do calculations to find the zeta potential. Temperature, pH, conductivity, pressure, and streaming potential are all measured in the instrument for this reason.
Zeta potential can also be calculated using theoretical models, and an experimentally-determined electrophoretic mobility or dynamic electrophoretic mobility.
Electrokinetic phenomena and electroacoustic phenomena are the usual sources of data for calculation of zeta potential. (See Zeta potential titration.) | 0 | Colloidal Chemistry |
The use of depletion forces to initiate flocculation is a common process in water treatment. The relatively small size of dispersed particles in waste water renders typical filtration methods ineffective. However, if the dispersion was to be destabilized and flocculation occur, particles can then be filtered out to produce pure water. Therefore, coagulants and flocculants are typically introduced to waste water which create these depletion forces between the dispersed particles. | 0 | Colloidal Chemistry |
Studies have shown that PFOS is a persistent, bioaccumulative, and toxic pollutant. It was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009. Regulations in the United States, Canada, European Union, Australia, and Japan have banned the new production of PFOS-based products, including firefighting foams. 3M phased out production of PFOS in 2002 due to toxicity concerns.
One study, published in 2015, found that firefighters were more likely to have fluorinated surfactants in their bloodstream. In 2016, the United States Air Force paid $4.3 million for a water treatment system for residents downstream of Peterson Air Force Base in Colorado.
In the United States, discharges of AFFF by vessels to surface waters are regulated by the United States Environmental Protection Agency (EPA) and Department of Defense, pursuant to the Clean Water Act.
In Australia, in 2015 a public safety announcement was issued by the New South Wales Environment Protection Authority following a water source contamination near RAAF Base Williamtown. Surface water, groundwater and fish were reported to contain chemicals from firefighting foams that had been released by the local Royal Australian Air Force base prior to training protocol changes in 2008. The residents of the area were advised to not consume any bore water, in addition to eggs and seafood from fauna exposed to the contaminated water. The discovery led to the banning of all forms of fishing in the waters of Fullerton Cove until the beginning of October 2016.
As of 2017, the Australian Department of Defence was dealing with two class action suits brought by those affected by contamination at Williamtown and at Army Aviation Centre Oakey. Along with many airports and fire services, the Department of Defence is investigating possible contamination at 18 military sites across Australia. At Williamtown, it is also conducting studies on the uptake and residual contamination in plants, chickens and eggs.
In December 2017, New Zealand's Minister for the Environment announced that higher than acceptable levels of PFOS and PFOA were found in groundwater at two Royal New Zealand Air Force bases, thought to be from historic use of firefighting foam containing the substances. Residents residing near the airbases were told to drink bottled water until more extensive testing could be carried out.
In 2020, state government agencies in the US are planning to dispose of firefighting foam, either by incineration or landfilling. Nearly of foam will be disposed by the US. The potential health risks of incinerating AFFF are still being investigated by EPA and state agencies. | 0 | Colloidal Chemistry |
The emergence of nanocomposite hydrogels allow for more site-specific and time-controlled delivery of drugs of different sizes at improved safety and specificity. Depending on the method of inserting drugs into the material, for example, dissolved, encased, or attached, the drug carrier will be named differently: nanoparticles, nanospheres (where the drug is evenly dispersed throughout the polymeric network), or nanocapsules (where the drug is surrounded by a polymer shell structure). The elastomeric nature of this material allows the hydrogels to obtain the shape of the targeted site and thus the hydrogels can be manufactured identically and used on all patients.
Hydrogels are controlled drug delivery agents that can be engineered to have desired properties. Specifically, hydrogels can be designed to release drugs or other agents in response to physical characteristics of the environment like temperature and pH. The responsiveness of hydrogels is a result of their molecular structure and polymer networks.
Hydrogel nanoparticles have a promising future in the drug delivery field. Ideally, drug delivery systems should, “…maximize the efficacy and the safety of the therapeutic agent, delivering an appropriate amount at a suitable rate and to the most appropriate site in the body”. Nanotechnology incorporated within hydrogels has the potential to meet all the requirements of an ideal drug delivery system. Hydrogels have been studied with a variety of nanocomposites including: clay, gold, silver, iron oxide, carbon nanotubes, hydroxyapatite, and tricalcium phosphate.
Nanoparticles, largely due to their size related physical properties, are highly useful as drug delivery agents. They can overcome physiological barriers and reach specific targets. Nanoparticles’ size, surface charge and properties enable them to penetrate biological barriers that most other drug carriers cannot. To become even more specified, nanoparticles can be coated with targeting ligands. The ability of nanoparticles to deliver drugs to specific targets suggests the potential to limit systemic side-effects and immune responses.
The ability of nanoparticles to carry and release drugs is also largely dependent on characteristics which result from the small size and unique surface area to volume ratio of nanoparticles. Nanoparticles can generally carry drugs in two ways: drugs can either be bound to the outside of the nanoparticles or packed within the polymeric matrix of the nanoparticles. Smaller nanoparticles have higher surface area ratios and can thus bind a high quantity of drug, while larger nanoparticles can encapsulate more of the drug within its core. The best method of drug loading is dependent on the structures of the drug to be bound. Also, drug loading can occur as the nanoparticles are produced, or the drugs can be added to pre-existing nanoparticles. The release of drugs, depends largely on the size of the nanoparticle carrying it. Because nanoparticles can be bound to the surface of nanoparticles, which is large relative to the volume of the particles, drugs can be released quickly. In contrast, drugs that are loaded within nanoparticles are released more slowly. | 0 | Colloidal Chemistry |
Dendrimers are unique hyper-branched synthetic polymers with monodispersed size, well-defined structure, and a highly functionalized terminal surface. They are typically composed of synthetic or natural amino acid, nucleic acids, and carbohydrates. Therapeutics can be loaded with relative ease onto the interior of the dendrimers or the terminal surface of the branches via electrostatic interaction, hydrophobic interactions, hydrogen bonds, chemical linkages, or covalent conjugation. Drug-dendrimer conjugation can elongate the half-life of drugs. Currently, dendrimer use in biological systems is limited due to dendrimer toxicity and limitations in their synthesis methods. Dendrimers are also confined within a narrow size range (<15 nm) and current synthesis methods are subject to low yield. The surface groups will reach the de Gennes dense packing limit at high generation level, which seals the interior from the bulk solution – this can be useful for encapsulation of hydrophobic, poorly soluble drug molecules. The seal can be tuned by intramolecular interactions between adjacent surface groups, which can be varied by the condition of the solution, such as pH, polarity, and temperature, a property which can be utilized to tailor encapsulation and controlled release properties. | 0 | Colloidal Chemistry |
In interfacial synthesis, the polymerization happens at the interface between an aqueous and an organic layer. A typical reaction involves an aqueous solution of acid and oxidant and an organic layer of aniline together. This creates the reactive interface for polymerization to occur. As polymerization proceeds, the polyaniline nanofibers will diffuse into the water layer, leaving the reactive interface. This prevents overgrowth onto the existing wires, allowing for homogeneous nucleation to continue occurring. Conditions in the interfacial synthesis can be tuned, such as the type of acid used as well as the oxidant used. | 0 | Colloidal Chemistry |
A dangling bond adds an extra energy level between the valence band and conduction band of a lattice. This allows for absorption and emission at longer wavelengths, because electrons can take smaller energy steps by moving to and from this extra level. The energy of the photons absorbed by or emitted from this level is not exactly equal to the energy difference between the bottom of the conduction band and the dangling bond or the top of the valence band and the dangling bond. This is due to lattice relaxation which causes a Franck-Condon shift in the energy. This shift accounts for the difference between a tight-binding calculation of these energy differences and the experimentally measured energies.
Another way in which the presence of dangling bonds affects the optical properties of a material is via polarization. For a material with dangling bonds, the absorption intensity depends on the polarization of the absorbed light. This is an effect of the symmetry in which the dangling bonds are distributed over the surface of the material. The dependence only occurs up to the energy at which an electron can be excited to the level of the gap but not to the valence band. This effect along with the polarization dependence disappearing after the dangling bonds have been annealed, shows that it is an effect of the dangling bonds and not just of the general symmetry of the material. | 1 | Solid-state chemistry |
Surlyn is the brand name of an ionomer resin created by DuPont, a copolymer of ethylene and methacrylic acid used as a coating and packaging material.
DuPont neutralizes the acid with NaOH, yielding the sodium salt.
Crystals of ethylene-methacrylic acid ionomers exhibit dual melting behavior. | 1 | Solid-state chemistry |
In real life, most systems are not integrable and display various degrees of chaos. Classical dynamics is then said to be mixed and the system phase space is typically composed of islands of regular orbits surrounded by a large sea of chaotic orbits. The existence of the chaotic sea, where transport is classically allowed, between the two symmetric tori then assists the quantum tunnelling between them. This phenomenon is referred as chaos-assisted tunnelling. and is characterized by sharp resonances of the tunnelling rate when varying any system parameter. | 1 | Solid-state chemistry |
Indium oxide is used in some types of batteries, thin film infrared reflectors transparent for visible light (hot mirrors), some optical coatings, and some antistatic coatings. In combination with tin dioxide, indium oxide forms indium tin oxide (also called tin doped indium oxide or ITO), a material used for transparent conductive coatings.
In semiconductors, indium oxide can be used as an n-type semiconductor used as a resistive element in integrated circuits.
In histology, indium oxide is used as a part of some stain formulations. | 1 | Solid-state chemistry |
Open-celled metal foam, also called metal sponge, can be used in heat exchangers (compact electronics cooling, cryogen tanks, PCM heat exchangers), energy absorption, flow diffusion, scrubbers, flame arrestors, and lightweight optics. The high cost of the material generally limits its use to advanced technology, aerospace, and manufacturing.
Fine-scale open-cell foams, with cells smaller than can be seen unaided, are used as high-temperature filters in the chemical industry.
Metal foams are used in compact heat exchangers to increase heat transfer at the cost of reduced pressure. However, their use permits substantial reduction in physical size and fabrication costs. Most models of these materials use idealized and periodic structures or averaged macroscopic properties.
Metal sponge has very large surface area per unit weight and catalysts are often formed into metal sponge, such as palladium black, platinum sponge, and spongy nickel. Metals such as osmium and palladium hydride are metaphorically called "metal sponges", but this term is in reference to their property of binding to hydrogen, rather than the physical structure. | 0 | Colloidal Chemistry |
Hysteresis is used to measure the compression properties of nanocomposite hydrogels, which shows that this material can withstand around 90% compression. This data shows that nanocomposite hydrogels exhibit superior strength relative to conventionally-made hydrogels, which would have broken down under less compression. | 0 | Colloidal Chemistry |
Aluminium foam sandwich (AFS) is a sandwich panel product which is made of two metallic dense face sheets and a metal foam core made of an aluminium alloy. AFS is an engineering structural material owing to its stiffness-to-mass ratio and energy absorption capacity ideal for application such as the shell of a high-speed train. | 0 | Colloidal Chemistry |
A drawback of NMR crystallography is that the method is typically more time-consuming and more expensive (due to spectrometer costs and isotope labelling) than X-ray crystallography, it often elucidates only part of the structure, and isotope labelling and experiments may have to be tailored to obtain key structural information. Also a given molecular structure may not always be suitable for a pure NMR-based NMR crystallographic approach, but it can still play an important role in a multimodality (NMR+diffraction) study.
Unlike in the case of diffraction methods, it appears that NMR crystallography needs to work on a case-by-case basis. The reason is that different molecular systems will exhibit different spin physics and different observables which can be probed. The method may therefore not find widespread use as different systems will require tailored experimental designs to study them. | 1 | Solid-state chemistry |
Biosurfactants are usually categorized by their molecular structure. Like synthetic surfactants, they are composed of a hydrophilic moiety made up of amino acids, peptides, (poly)saccharides, or sugar alcohols and a hydrophobic moiety consisting of fatty acids. Correspondingly, the significant classes of biosurfactants include glycolipids, lipopeptides and lipoproteins, and polymeric surfactants as well as particulate surfactants. | 0 | Colloidal Chemistry |
Estropipate was marketed under the brand names Genoral, Harmogen, Improvera, Ogen, Ortho-Est, and Sulestrex among others. | 1 | Solid-state chemistry |
CuHARS have been shown to completely degrade under physiological conditions (cell culture media at 37 °C), even in the absence of cells; this is possibly due to the metal chelating properties of typical cell culture medias. These may include the copper-binding properties of cerulosplasmin and of albumin. Additionally, CuHARS have been shown to polarize light using inverted microscopy. Cobalt-containing MOBs (CoMOBs) have been shown to be susceptible to an externally applied magnetic field as shown in Figure 2. | 0 | Colloidal Chemistry |
In physics, quantum tunnelling, barrier penetration, or simply tunnelling is a quantum mechanical phenomenon in which an object such as an electron or atom passes through a potential energy barrier that, according to classical mechanics, should not be passable due to the object not having sufficient energy to pass or surmount the barrier.
Tunneling is a consequence of the wave nature of matter, where the quantum wave function describes the state of a particle or other physical system, and wave equations such as the Schrödinger equation describe their behavior. The probability of transmission of a wave packet through a barrier decreases exponentially with the barrier height, the barrier width, and the tunneling particle's mass, so tunneling is seen most prominently in low-mass particles such as electrons or protons tunneling through microscopically narrow barriers. Tunneling is readily detectable with barriers of thickness about 1–3 nm or smaller for electrons, and about 0.1 nm or smaller for heavier particles such as protons or hydrogen atoms. Some sources describe the mere penetration of a wave function into the barrier, without transmission on the other side, as a tunneling effect, such as in tunneling into the walls of a finite potential well.
Tunneling plays an essential role in physical phenomena such as nuclear fusion and alpha radioactive decay of atomic nuclei. Tunneling applications include the tunnel diode, quantum computing, flash memory, and the scanning tunneling microscope. Tunneling limits the minimum size of devices used in microelectronics because electrons tunnel readily through insulating layers and transistors that are thinner than about 1 nm.
The effect was predicted in the early 20th century. Its acceptance as a general physical phenomenon came mid-century. | 1 | Solid-state chemistry |
Cheetham was educated at Stockport Grammar School and read chemistry at St Catherines College, Oxford, matriculating in 1965, and graduated with first class honours in 1969. He started his doctorate at Wadham College, Oxford in the same year, with a thesis on The Structures of some Non-stoichiometric Compounds'; his doctorate was awarded in 1972. | 1 | Solid-state chemistry |
The mechanical properties of hydrogels can be fine-tuned in many ways beginning with attention to their hydrophobic properties. Another method of modifying the strength or elasticity of hydrogels is to graft or surface coat them onto a stronger/stiffer support, or by making superporous hydrogel (SPH) composites, in which a cross-linkable matrix swelling additive is added. Other additives, such as nanoparticles and microparticles, have been shown to significantly modify the stiffness and gelation temperature of certain hydrogels used in biomedical applications. | 0 | Colloidal Chemistry |
Shannon received his B.S. and M.S. degrees in Ceramic Engineering from the University of Illinois in 1957 and 1959. He then went on to receive his Ph.D. in Ceramic Engineering from the University of California at Berkeley in 1960. He then joined the DuPont Company as a research chemist from 1964 to 1971 where he concentrated on high-pressure synthesis and precious metal oxide chemistry. He then spent 1971 conducting post-doctorate studies at McMaster University in Hamilton, Ontario, working with Chris Calvo on the crystal structures of a number of vanadates and with David Brown on bond strength-bond length relationships useful in determining H locations in hydroxides and hydrates. Next, he took a sabbatical leave from DuPont and spent 1972 at the CNRS and teaching at the University of Grenoble, France as a visiting professor, where he presented a course on solid state chemistry and conducted research on high-pressure chemistry of vanadates. He returned to DuPont in 1973 to do research on new ionic conductors and precious metal oxide chemistry.
In 1982, he was granted another sabbatical leave from DuPont and worked on catalysis with zeolites at the Institute de Catalyse in Lyon, France. Upon completion of the sabbatical, he returned to DuPont and worked for another ten years before retiring in 1992.
After retirement, he received a grant from the Alexander von Humboldt Foundation to continue his research on ion polarizabilities in collaboration with Reinhard Fischer in 1994 at the Universities of Mainz and Bremen in Germany and with Olaf Medenbach at the Ruhr-Universität in Bochum, Germany. There, he prepared three papers on refractive indices and electronic polarizabilities in oxides, and other compounds. He has since moved to Colorado where he has been associated with the University of Colorado Boulder · Cooperative Institute for Research in Environmental Sciences (CIRES).
Shannon was a member of the American Chemical Society and the American Crystallographic Association. He was elected a Fellow of the Mineralogical Society of America. He has served on the Evaluation Panel for Materials Science at the National Bureau of Standards, and on the National Science Foundation Subcommittee for Oversight Review of Solid State Chemistry. | 1 | Solid-state chemistry |
NbCl has a hexagonal close packed array of chloride ions. Triangles of niobium occur in octahedral spaces in the chloride array. The compositions with higher chloride have some niobium atoms missing from the structure, creating vacancies and giving rise to nonstoichiometric compounds. NbCl has this pattern of vacancies stretched until the niobium atoms are in pairs rather than triangles. So NbCl can be considered as a solid solution of NbCl and NbCl.
The colour of niobium trichloride varies depending on the niobium:chloride ratio. NbCl is green, while NbCl is brown. | 1 | Solid-state chemistry |
Surfactants play an important role as cleaning, wetting, dispersing, emulsifying, foaming and anti-foaming agents in many practical applications and products, including detergents, fabric softeners, motor oils, emulsions, soaps, paints, adhesives, inks, anti-fogs, ski waxes, snowboard wax, deinking of recycled papers, in flotation, washing and enzymatic processes, and laxatives. Also agrochemical formulations such as herbicides (some), insecticides, biocides (sanitizers), and spermicides (nonoxynol-9). Personal care products such as cosmetics, shampoos, shower gel, hair conditioners, and toothpastes. Surfactants are used in firefighting (to make "wet water" that more quickly soaks into flammable materials) and pipelines (liquid drag reducing agents). Alkali surfactant polymers are used to mobilize oil in oil wells.
Surfactants act to cause the displacement of air from the matrix of cotton pads and bandages so that medicinal solutions can be absorbed for application to various body areas. They also act to displace dirt and debris by the use of detergents in the washing of wounds and via the application of medicinal lotions and sprays to surface of skin and mucous membranes. Surfactants enhance remediation via soil washing, bioremediation, and phytoremediation. | 0 | Colloidal Chemistry |
Mixed conductors, also known as mixed ion-electron conductors (MIEC), are a single-phase material that has significant conduction ionically and electronically. Due to the mixed conduction, a formally neutral species can transport in a solid and therefore mass storage and redistribution are enabled. Mixed conductors are well known in conjugation with high-temperature superconductivity and are able to capacitate rapid solid-state reactions.
They are used as catalysts (for oxidation), permeation membranes, sensors, and electrodes in batteries and fuel cells, because they allow for rapidly transducing chemical signals and permeating chemical components.
Strontium titanate (), titanium dioxide (), , cerium(IV) oxide (), lithium iron phosphate (), and are examples of mixed conductors. | 1 | Solid-state chemistry |
Brine is used as a secondary fluid in large refrigeration installations for the transport of thermal energy. Most commonly used brines are based on inexpensive calcium chloride and sodium chloride. It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine is at the concentration of 23.3% NaCl by weight. This is called the eutectic point.
Because of their corrosive properties salt-based brines have been replaced by organic liquids such as ethylene glycol.
Sodium chloride brine spray is used on some fishing vessels to freeze fish. The brine temperature is generally . Air blast freezing temperatures are or lower. Given the higher temperature of brine, the system efficiency over air blast freezing can be higher. High-value fish usually are frozen at much lower temperatures, below the practical temperature limit for brine. | 1 | Solid-state chemistry |
The primary functions of metallic foams in vehicles are to increase sound damping, reduce weight, increase energy absorption in case of crashes, and (in military applications) to combat the concussive force of IEDs. As an example, foam filled tubes could be used as anti-intrusion bars. Because of their low density (0.4–0.9 g/cm), aluminium and aluminium alloy foams are under particular consideration. These foams are stiff, fire resistant, nontoxic, recyclable, energy absorbent, less thermally conductive, less magnetically permeable, and more efficiently sound dampening, especially when compared to hollow parts. Metallic foams in hollow car parts decrease weakness points usually associated with car crashes and vibration. These foams are inexpensive to cast with powder metallurgy, compared to casting other hollow parts.
Compared to polymer foams in vehicles, metallic foams are stiffer, stronger, more energy absorbent, and resistant to fire and the weather adversities of UV light, humidity, and temperature variation. However, they are heavier, more expensive, and non-insulating.
Metal foam technology has been applied to automotive exhaust gas. Compared to traditional catalytic converters that use cordierite ceramic as substrate, metal foam substrate offers better heat transfer and exhibits excellent mass-transport properties (high turbulence) and may reduce the quantity of platinum catalyst required. | 0 | Colloidal Chemistry |
Bismuth telluride () is a gray powder that is a compound of bismuth and tellurium also known as bismuth(III) telluride. It is a semiconductor, which, when alloyed with antimony or selenium, is an efficient thermoelectric material for refrigeration or portable power generation. is a topological insulator, and thus exhibits thickness-dependent physical properties. | 1 | Solid-state chemistry |
Indium(III) selenide is a compound of indium and selenium. It has potential for use in photovoltaic devices and has been the subject of extensive research. The two most common phases, α and β, have a layered structure, while γ has a "defect wurtzite structure." In all, five polymorphs are known: α, β, γ, δ, κ. The α-β phase transition is accompanied by a change in electrical conductivity. The band gap of γ-InSe is approximately 1.9 eV. | 1 | Solid-state chemistry |
Samarium arsenide forms crystals of a cubic system, space group Fm3m, cell parameters a = 0.5921 nm, Z = 4, of NaCl-structure.
The compound melts congruently at 2257 °C. | 1 | Solid-state chemistry |
Bittern (pl. bitterns), or nigari, is the salt solution formed when halite (table salt) precipitates from seawater or brines. Bitterns contain magnesium, calcium, and potassium ions as well as chloride, sulfate, iodide, and other ions.
Bittern is commonly formed in salt ponds where the evaporation of water prompts the precipitation of halite. These salt ponds can be part of a salt-producing industrial facility, or they can be used as a waste storage location for brines produced in desalination processes.
Bittern is a source of many useful salts. It is used as a natural source of Mg, and it can be used as a coagulant both in the production of tofu and in the treatment of industrial wastewater. | 1 | Solid-state chemistry |
In the Langmuir-Blodgett method, the nanoparticles are injected at air-water interphase in a special Langmuir-Blodgett Trough. The floating particles are compressed closer to each other with motorized barriers which allow to control the packing density of the particles. After compressing the particles to the desired packing density, they are transferred on a solid substrate using vertical (Langmuir-Blodgett) or horizontal (Langmuir-Schaefer) dipping to create a monolayer coating. Controlled multilayer coatings can be made repeating the dipping procedure multiple times.
The benefits of the Langmuir-Blodgett method include a firm control over the packing density and the layer thickness achieved that have been shown to be better than with other methods, the ability to use different shapes and materials of substrates and particles and the possibility to characterize the particle layer during deposition for example a Brewster Angle Microscope. As a disadvantage, a successful Langmuir-Blodgett deposition requires optimization of multiple measurement parameters such as dipping speed, temperature and dipping packing density. | 0 | Colloidal Chemistry |
There are case reports of adverse effects associated with excessive consumption of BVO-containing products. One case reported that a man who consumed two to four liters of a soda containing BVO on a daily basis experienced memory loss, tremors, fatigue, loss of muscle coordination, headache, and ptosis of the right eyelid, as well as elevated serum chloride. In the two months it took to correctly diagnose the problem, the patient also lost the ability to walk. Eventually, bromism was diagnosed and hemodialysis was prescribed which resulted in a reversal of the disorder. | 0 | Colloidal Chemistry |
Water-based defoamers are different types of oils and waxes dispersed in a water base. The oils are often mineral oil or vegetable oils and the waxes are long chain fatty alcohol, fatty acid soaps or esters. These are normally best as deaerators, which means they are best at releasing entrained air. | 0 | Colloidal Chemistry |
In charge trap flash memories, charge is stored in a trapping material, typically a silicon-nitride layer, as current flows through a dielectric. In the programming process, electrons are emitted from the substrate towards the trapping layer due to a large positive bias applied to the gate. The current transport is the result of two different conduction mechanisms, to be considered in series: the current through the oxide is by tunneling, the conduction mechanism through the nitride is a Poole–Frenkel transport. The tunneling current is described by a modified Fowler-Nordheim tunneling equation, i.e. a tunneling equation that takes into account that the shape of the tunneling barrier is not triangular (as assumed for the Fowler-Nordheim formula derivation), but composed of the series of a trapezoidal barrier in the oxide, and a triangular barrier in the nitride. The Poole-Frenkel process is the limiting mechanism of conduction at the beginning of the memory programming regime due to the higher current provided by tunneling. As the trapped electron charge raises, beginning to screen the field, the modified Fowler-Nordheim tunneling becomes the limiting process. The trapped charge density at the oxide-nitride interface is proportional to the integral of the Poole-Frenkel current flowed across it.
With an increasing number of memory write and erase cycles, retention characteristics worsen due to the increasing bulk conductivity in the nitride. | 1 | Solid-state chemistry |
The basic components needed for the exploding wire method are a thin conductive wire and a capacitor. The wire is typically gold, aluminum, iron or platinum, and is usually less than 0.5 mm in diameter. The capacitor has an energy consumption of about 25 kWh/kg and discharges a pulse of current density 10 - 10 A/mm, leading to temperatures up to 100,000 K. The phenomenon occurs over a time period of only 10 - 10 seconds.
The process is as follows:
# A rising current, supplied by the capacitor, is carried across the wire.
# The current heats up the wire through ohmic heating until the metal begins to melt. The metal melts to form a broken series of imperfect spheres called unduloids. The current rises so fast that the liquid metal has no time to move out of the way.
# The unduloids vaporize. The metal vapor creates a lower resistance path, allowing an even higher current to flow.
# An electric arc is formed, which turns the vapor into plasma. A bright flash of light is also produced.
# The plasma is allowed to expand freely, creating a shock wave.
# Electromagnetic radiation is released in tandem with the shock wave.
# The shock wave pushes liquid, gaseous and plasmatic metal outwards, breaking the circuit and ending the process. | 0 | Colloidal Chemistry |
The use of the second order perturbation correction, Eq. (4), for the calculation of the value in the case of PJTE instability is incorrect because in this case , meaning the first perturbation correction is larger than the main term, and hence the criterion of applicability of the perturbation theory in its simplest form does not hold. In this case, we should consider the contribution of the lowest excited states (that make the total curvature negative) in a pseudo degenerate problem of perturbation theory. For the simplest case when only one excited state creates the main instability of the ground state, we can treat the problem via a pseudo degenerate two-level problem, including the contribution of the higher, weaker-influencing states as a second order correction.
In the PJTE two-level problem we have two electronic states of the high-symmetry configuration, ground and excited , separated by an energy interval of , that become mixed under nuclear displacements of certain symmetry ; the denotations , , and indicate, respectively, the irreducible representations to which the symmetry coordinate and the two states belong. In essence, this is the original formulation of the PJTE. Assuming that the excited state is sufficiently close to the ground one, the vibronic coupling between them should be treated as a perturbation problem for two near-degenerate states. With both interacting states non-degenerate the vibronic coupling constant in Eq. (5) (omitting indices) is non-zero for only one coordinate with . This gives us directly the symmetry of the direction of softening and possible distortion of the ground state. Assuming that the primary force constants in the two states are the same (for different see [1]), we get a 2×2 secular equation with the following solution for the energies of the two states interacting under the linear vibronic coupling (energy is referred to the middle of the gap between the levels at the undistorted geometry):
It is seen from these expressions that, on taking into account the vibronic coupling, , the two APES curves change in different ways: in the upper sheet the curvature (the coefficient at in the expansion on ) increases, whereas in the lower one it decreases. But until the minima of both states correspond to the point , as in the absence of vibronic mixing. However, if
the curvature of the lower curve of the APES becomes negative, and the system is unstable with respect to the displacements (Fig. 1). Under condition (8), the minima points on the APES are given by
From these expressions and Fig. 1 it is seen that while the ground state is softened (destabilized) by the PJTE, the excited state is hardened (stabilized), and this effect is the larger, the smaller and the larger F. It takes place in any polyatomic system and influences many molecular properties, including the existence of stable excited states of molecular systems that are unstable in the ground state (e.g., excited states of intermediates of chemical reactions); in general, even in the absence of instability the PJTE softens the ground state and increases the vibrational frequencies in the excited state. | 1 | Solid-state chemistry |
Cells are very sensitive to nanotopographical features, so optimization of surfaces in tissue engineering has pushed towards implantation. Under appropriate conditions, a carefully crafted 3-dimensional scaffold is used to direct cell seeds toward artificial organ growth. The 3-D scaffold incorporates various nanoscale factors that control the environment for optimal and appropriate functionality. The scaffold is an analog of the in vivo extracellular matrix in vitro, allowing for successful artificial organ growth by providing the necessary, complex biological factors in vitro. | 0 | Colloidal Chemistry |
In their early 1957 paper on what is now called pseudo Jahn–Teller effect (PJTE), Öpik and Pryce showed that a small splitting of the degenerate electronic term does not necessarily remove the instability and distortion of a polyatomic system induced by the Jahn–Teller effect (JTE), provided that the splitting is sufficiently small (the two split states remain "pseudo degenerate"), and the vibronic coupling between them is strong enough. From another perspective, the idea of a "mix" of different electronic states induced by low-symmetry vibrations was introduced in 1933 by Herzberg and Teller to explore forbidden electronic transitions, and extended in the late 1950s by Murrell and Pople and by Liehr.<br>
The role of excited states in softening the ground state with respect to distortions in benzene was demonstrated qualitatively by Longuet-Higgins and Salem by analyzing the π electron levels in the Hückel approximation, while a general second-order perturbation formula for such vibronic softening was derived by Bader in 1960. In 1961 Fulton and Gouterman presented a symmetry analysis of the two-level case in dimers and introduced the term "pseudo Jahn–Teller effect". The first application of the PJTE to solving a major solid-state structural problem with regard to the origin of ferroelectricity was published in 1966 by Isaac Bersuker, and the first book on the JTE covering the PJTE was published in 1972 by Englman. The second-order perturbation approach was employed by Pearson in 1975 to predict instabilities and distortions in molecular systems; he called it "second-order JTE" (SOJTE). The first explanation of PJT origin of puckering distortion as due to the vibronic coupling to the excited state, was given for the NH radical by Borden, Davidson, and Feller in 1980 (they called it "pyramidalization"). <br>
Methods of numerical calculation of the PJT vibronic coupling effect with applications to spectroscopic problems were developed in the early 1980s
A significant step forward in this field was achieved in 1984 when it was shown by numerical calculations that the energy gap to the active excited state may not be the ultimate limiting factor in the PJTE, as there are two other compensating parameters in the condition of instability. It was also shown that, in extension of the initial definition, the PJT interacting electronic states are not necessarily components emerging from the same symmetry type (as in the split degenerate term). As a result, the applicability of the PJTE became a priory unlimited. Moreover, it was shown by Bersuker that the PJTE is the only source of instability of high-symmetry configurations of polyatomic systems in nondegenerate states (works cited in Refs.), and degeneracy and pseudo degeneracy are the only source of spontaneous symmetry breaking in matter in all its forms. The many applications of the PJTE to the study of a variety of properties of molecular systems and solids are reflected in a number of reviews and books ), as well as in proceedings of conferences on the JTE. | 1 | Solid-state chemistry |
All commercial potash deposits come originally from evaporite deposits and are often buried deep below the earth's surface. Potash ores are typically rich in potassium chloride (KCl), sodium chloride (NaCl) and other salts and clays, and are typically obtained by conventional shaft mining with the extracted ore ground into a powder. Most potash mines today are deep shaft mines as much as 4,400 feet (1,400 m) underground. Others are mined as strip mines, having been laid down in horizontal layers as sedimentary rock. In above-ground processing plants, the KCl is separated from the mixture to produce a high-analysis potassium fertilizer. Other potassium salts can be separated by various procedures, resulting in potassium sulfate and potassium-magnesium sulfate. | 1 | Solid-state chemistry |
Tunnelling is a source of current leakage in very-large-scale integration (VLSI) electronics and results in a substantial power drain and heating effects that plague such devices. It is considered the lower limit on how microelectronic device elements can be made. Tunnelling is a fundamental technique used to program the floating gates of flash memory. | 1 | Solid-state chemistry |
Saiful Islam (born 14 August 1963) is a British chemist and professor of materials modelling at the Department of Materials, University of Oxford. Saiful is a Fellow of the Royal Society of Chemistry (FRSC), and received the Royal Society's Wolfson Research Merit Award and Hughes Medal, and the American Chemical Society Award for Energy Chemistry for his major contributions to the fundamental atomistic understanding of new materials for lithium batteries and perovskite solar cells.
Saiful is an atheist who refused the Order of the British Empire citing discomfort with the phrase "British Empire" and its link to colonialism. | 1 | Solid-state chemistry |
ELS is useful for characterizing information about the surface of proteins. Ware and Flygare (1971) demonstrated that electrophoretic techniques can be combined with laser beat spectroscopy in order to simultaneously determine the electrophoretic mobility and diffusion coefficient of bovine serum albumin. The width of a Doppler shifted spectrum of light that is scattered from a solution of macromolecules is proportional to the diffusion coefficient. The Doppler shift is proportional to the electrophoretic mobility of a macromolecule. From studies that have applied this method to poly (L-lysine), ELS is believed to monitor fluctuation mobilities in the presence of solvents with varying salt concentrations. It has also been shown that electrophoretic mobility data can be converted to zeta potential values, which enables the determination of the isoelectric point of proteins and the number of electrokinetic charges on the surface.
Other biological macromolecules that can be analyzed with ELS include polysaccharides. pKa values of chitosans can be calculated from the dependency of electrophoretic mobility values on pH and charge density. Like proteins, the size and zeta potential of chitosans can be determined through ELS.
ELS has also been applied to nucleic acids and viruses. The technique can be extended to measure electrophoretic mobilities of large bacteria molecules at low ionic strengths. | 0 | Colloidal Chemistry |
Macroscopic viscous flow fields can direct self-assembly of a random solution of particles into ordered crystals. However, the assembled particles tend to disassemble when the flow is stopped or removed. Shear flows are useful for jammed suspensions or random close packing. As these systems begin in nonequilibrium, flow fields are useful in that they help the system relax towards ordered equilibrium. Flow fields are also useful when dealing with complex matrices that themselves have rheological behavior. Flow can induce anisotropic viseoelastic stresses, which helps to overcome the matrix and cause self-assembly. | 0 | Colloidal Chemistry |
By the mid-1990s, Hazen felt that his research had reached a "respectable plateau" where the main principles of how crystals compress were known. The questions he was asking were increasingly narrow and the answers rarely surprising. So he changed research directions to study life's chemical origins. This opportunity came when a colleague at George Mason University, Harold Morowitz, realized that the temperature and pressure at a hydrothermal vent might change the properties of water, allowing chemical reactions that ordinarily require the help of an enzyme. Enlisting the help of Hatten Yoder, a specialist in high pressure mineralogy, they tried subjecting pyruvate in water to high pressure, hoping for a simple reaction that would return oxaloacetate. Instead, an analysis by an organic geochemist, George Cody, found that they obtained tens of thousands of molecules.
The publication of their results, which seemed to support the deep sea vent hypothesis, met with heavy criticism, especially from Stanley Miller and colleagues who believe that life emerged on the surface. Along with the general criticism that organic compounds would not survive long in hot, high pressure conditions, they pointed out several flaws in the experiment. In his book, Genesis, Hazen acknowledges that Stanley Miller "was basically right" about the experiments, but argues that "the art of science isn't necessarily to avoid mistakes; rather, progress is often made by making mistakes as fast as possible, while avoiding making the same mistake twice." In subsequent work, the group formed biomolecules from carbon dioxide and water and catalyzed the formation of amino acids using oxides and sulfides of transition metals; and different transition elements catalyze different organic reactions. | 1 | Solid-state chemistry |
The first -quantum () will be emitted isotropically. Detecting this quantum in a detector selects a subset with an orientation of the many possible directions that has a given. The second -quantum () has an anisotropic emission and shows the effect of the angle correlation. The goal is to measure the relative probability with the detection of at the fixed angle in relation to . The probability is given with the angle correlation (perturbation theory):
For a --cascade, is due to the preservation of parity:
Where is the spin of the intermediate state and with the multipolarity of the two transitions. For pure multipole transitions, is .
is the anisotropy coefficient that depends on the angular momentum of the intermediate state and the multipolarities of the transition.
The radioactive nucleus is built into the sample material and emits two -quanta upon decay. During the lifetime of the intermediate state, i.e. the time between and , the core experiences a disturbance due to the hyperfine interaction through its electrical and magnetic environment. This disturbance changes the angular correlation to:
is the perturbation factor. Due to the electrical and magnetic interaction, the angular momentum of the intermediate state experiences a torque about its axis of symmetry. Quantum-mechanically, this means that the interaction leads to transitions between the M states. The second -quantum () is then sent from the intermediate level. This population change is the reason for the attenuation of the correlation.
The interaction occurs between the magnetic core dipole moment and the intermediate state or/and an external magnetic field . The interaction also takes place between nuclear quadrupole moment and the off-core electric field gradient . | 1 | Solid-state chemistry |
Phosphatidylcholine molecules form ~85% of the lipid in surfactant and have saturated acyl chains. Phosphatidylglycerol (PG) forms about 11% of the lipids in the surfactant, it has unsaturated fatty acid chains that fluidize the lipid monolayer at the interface. Neutral lipids and cholesterol are also present. The components for these lipids diffuse from the blood into type II alveolar cells where they are assembled and packaged for secretion into secretory organelles called lamellar bodies. | 0 | Colloidal Chemistry |
In Gießen, Hoppe continued his extensive research in the field of solid state chemistry with a focus on the synthesis and characterization of oxo- and fluorometalates of the alkali metals. During his research he published over 650 articles in international and national peer-review journals. In addition, he had been the scientific editor for the German Journal of Inorganic and General Chemistry (Zeitschrift für Anorganische und Allgemeine Chemie). | 1 | Solid-state chemistry |
The kinetic process of destabilisation can be rather long (up to several months or even years for some products) and it is often required for the formulator to use further accelerating methods in order to reach reasonable development time for new product design. Thermal methods are the most commonly used and consists in increasing temperature to accelerate destabilisation (below critical temperatures of phase and degradation). Temperature affects not only the viscosity, but also interfacial tension in the case of non-ionic surfactants or more generally interactions forces inside the system. Storing a dispersion at high temperatures enables simulation of real life conditions for a product (e.g. tube of sunscreen cream in a car in the summer), but also to accelerate destabilisation processes up to 200 times including vibration, centrifugation and agitation are sometimes used. They subject the product to different forces that pushes the particles / film drainage. However, some emulsions would never coalesce in normal gravity, while they do under artificial gravity. Moreover, segregation of different populations of particles have been highlighted when using centrifugation and vibration. | 0 | Colloidal Chemistry |
John Dudley Corbett (March 23, 1926 – September 2, 2013) was an American chemist who specialized in inorganic solid-state chemistry. At Iowa State and Ames Lab, Corbett lead a research group that focused on the synthesis and characterization of two broad classes of materials, notably Zintl phases and condensed transition metal halide clusters. Both classes of materials are important for their uses, for instance thermoelectrics, and for the theoretical advances they made possible by working to understand their complex bonding and electronic properties. | 1 | Solid-state chemistry |
Julia Y. Chan is a professor of chemistry and biochemistry at Baylor University. Chan is an expert in the area of intermetallic crystal growth with a focus on new quantum materials. | 1 | Solid-state chemistry |
Femtosecond laser micromachining is used for device fabrication by milling air holes and/or troughs into ferroelectric crystals by directing them through the focus region of a femtosecond laser beam. . The advantages of femtosecond laser micromachining for a wide range of materials have been well documented. In brief, free electrons are created within the beam focus through multiphoton excitation. Because the peak intensity of a femtosecond laser pulse is many orders of magnitude higher than that from longer pulse or continuous wave lasers, the electrons are rapidly excited, heated to form a quantum plasma. Particularly in dielectric materials, the electrostatic instability, induced by the plasma, of the remaining lattice ions results in ejection of these ions and hence ablation of the material, leaving a material void in the laser focus region. Also, since the pulse duration and ablation time scales are much faster than the thermalization time, femtosecond laser micromachining does not suffer from the adverse effects of a heat-affected-zone, like cracking and melting in regions neighboring the intended damage region. | 1 | Solid-state chemistry |
It is possible to manufacture a complicated 3D shape from in-situ bonded AFS. In case of the second type, i.e. integral foam moulding, the desired geometry of the foamed part is achieved by designing the mould inside which the foam is cast.
In the case of the third type the three-layer composite precursor is reshaped prior to foaming. Heating of such part yields in a 3D shaped foam part. The three-layer composite AFS panels are also reshaped after foaming by forging. If an AFS is made of heat treatable alloys, the strength is further enhanced by age hardening. In order to join two AFS parts or to join an AFS part with a metallic part several joining technologies are employed, such as laser welding, TIG welding, MIG welding, riveting, etc. | 0 | Colloidal Chemistry |
A conventional route entails heating the elements in a seal-tube:
Indium(III) telluride reacts with strong acids to produce hydrogen telluride. | 1 | Solid-state chemistry |
Salt that pierces to the surface, either on land or beneath the sea, tends to spread laterally away and such salt is said to be "allochthonous". Salt glaciers are formed on land where this happens in an arid environment, such as in the Zagros Mountains. Offshore tongues of salt are generated that may join together with others from neighbouring piercements to form canopies. | 1 | Solid-state chemistry |
His research focused on the following topics:
* application of crystallographic group theory in crystal chemistry to investigate structural relationships of crystalline solids and to predict possible structure types for inorganic compounds
* synthesis of thio, polysulfido, and polyselenido complexes
* structural analysis of crystalline solids with X-ray diffraction | 1 | Solid-state chemistry |
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite. One of several iron oxides, it is a black-colored powder that is sometimes confused with rust, the latter of which consists of hydrated iron(III) oxide (ferric oxide). Iron(II) oxide also refers to a family of related non-stoichiometric compounds, which are typically iron deficient with compositions ranging from FeO to FeO. | 1 | Solid-state chemistry |
# Selection of ingredients: The first step in creating a nanoemulsion is to select the ingredients, which include the oil, water, and emulsifying agent. The type and proportions of these ingredients will affect the stability and properties of the final emulsion.
# Preparation of oil and aqueous phases: The oil and water phases are separately prepared, with any desired ingredients, such as surfactants or flavoring agents, added at this step.
# Mixing oil and emulsifier with stirrer: Next, the oil and water phases are mixed in the presence of an emulsifying agent, typically using a high-shear mixing device such as a homogenizer or a high-pressure homogenizer.
# Aging and stabilization: The emulsion is typically aged at room temperature to allow the droplets to stabilize, after which it can be cooled or heated as required.
# Optimizing and characterization: The droplet size and stability are then optimized by adjusting the ingredients and process parameters, such as temperature, pH, and mixing conditions. The nanoemulsion is also sterilized by filtration with 0.22μm. Several methods, such as DLS, TEM, and SEM, can characterize the final nanoemulsion's properties.
# Analyzing the quality of the particle sizer | 0 | Colloidal Chemistry |
Smith was born on September 25, 1916, in Long Beach, California, and he grew up in Long Beach and Fontana, California. He attended Pomona College, graduating in 1938, and was a member of the Phi Beta Kappa honors society. While as a student at Pomona, Smith authored two papers with his chemistry professor, Wesley G. Leighton. After leaving Pomona, Smith went to Stanford University to work under Leighton's brother Philip A. Leighton and was awarded an M.A. and Ph.D. in 1940 and 1942 respectively. | 0 | Colloidal Chemistry |
After his studies in chemistry at the University of Göttingen from 1958 to 1963 and after his diploma in chemistry in 1963, Bernt Krebs received his Dr. rer.nat. degree in 1965. In 1965 and 1966 he worked as a postdoctoral research fellow at Brookhaven National Laboratory with Walter Hamilton and Don Koenig. After his habilitation in the field of inorganic chemistry at the University of Göttingen he got tenure as a Professor of Inorganic Chemistry at the University of Kiel in 1971. In 1973 he followed a call as a Professor at the newly founded University of Bielefeld where he was successful in establishing a new chemistry department and new chemistry curricula.
During his full professorship of inorganic chemistry at the University of Münster since 1977, he established his group as an internationally recognized research centre in the field of coordination chemistry, bioinorganic chemistry and structural chemistry. His research covers a broad range of fields ranging from inorganic solid state chemistry, synthetic main group chemistry, biomimetic transition metal complex chemistry for modelling active sites in metalloproteins to metalloenzyme studies, including the isolation and structural characterization by X-ray diffraction analysis. During the 1960s and 1970s he was one of the pioneers in the field of chemical crystallography in Germany. His work in synthesis and spectroscopy involved close cooperation with Achim Müller. He has held guest professorships at the Universities of Stony Brook (US), Strasbourg (France), La Plata (Argentina), Copenhagen/Lyngby (Denmark), and Nagoya (Japan).
Krebs has published more than 750 scientific peer-reviewed papers in international journals; besides a number of review articles, he was editor and co-editor of three books, and he is co-author of 13 patents. He served for several years in leading positions of German and European science organizations, e.g., as a chief referee (IC) for the Deutsche Forschungsgemeinschaft (DFG). Bernt Krebs is an elected member of several academies such as Academia Europaea London, German National Academy of Sciences Leopoldina, Akademie der Wissenschaften und der Literatur Mainz, New York Academy of Sciences, and Academia Nacional de Sciencias Exactas, Fisicas y Naturales, Buenos Aires. Among his several scientific honours are the Max Planck Research Award (1992), the Wilhelm Klemm Award of the German Chemical Society GDCh (1997), the Egon Wiberg Lecture Award (2003), and the honorary doctor degree of the University of Mainz (2006). | 1 | Solid-state chemistry |
Certain PFASs are no longer manufactured in the United States as a result of phase-outs including the PFOA Stewardship Program (2010-2015), in which eight major chemical manufacturers agreed to eliminate the use of PFOA and PFOA-related chemicals in their products and emissions from their facilities. Although PFOA and PFOS are no longer manufactured in the United States, they are still produced internationally and are imported into the U.S. in consumer goods such as carpet, leather and apparel, textiles, paper and packaging, coatings, rubber, and plastics.
In 2020, manufacturers and the Food and Drug Administration announced an agreement to phase out some types of PFAS that are used in food packaging by 2024.
PFASs are also used by major companies of the cosmetics industry in a wide range of cosmetics, including lipstick, eye liner, mascara, foundation, concealer, lip balm, blush, and nail polish. A 2021 study tested 231 makeup and personal care products and found organic fluorine, an indicator of PFASs, in more than half of the samples. High levels of fluorine were most commonly identified in waterproof mascara (82% of brands tested), foundations (63%), and liquid lipstick (62%). As many as 13 types of individual PFAS compounds were found in each product. Since PFAS compounds are highly mobile, they are readily absorbed through human skin and through tear ducts, and such products on lips are often unwittingly ingested. Manufacturers often fail to label their products as containing PFASs, which makes it difficult for cosmetics consumers to avoid products containing PFASs. In response, Senators Susan Collins of Maine and Richard Blumenthal of Connecticut proposed the No PFAS in Cosmetics Act in the United States Senate. It was also introduced in the United States House of Representatives by Michigan Representative Debbie Dingell, but the U.S. chemical industry lobby has killed efforts to regulate this.
In 2021, Maine became the first U.S. state to ban these compounds in all products by 2030, except for instances deemed "currently unavoidable". | 0 | Colloidal Chemistry |
By complexing metal ions into the polymer matrix, the strength and toughness of the ionomer system is increased. Some applications where ionomers were used to increase the toughness of the overall system include coatings, adhesives, impact modification, and thermoplastics, one of the most known examples being the use of Surlyn in the outer layer of golf balls. The ionomer coating improves the toughness, aerodynamics, and durability of the golf balls, increasing their lifetime. Ionomers can also be blended with resins to increase the cohesive strength without diminishing the overall tackiness of the resin, creating pressure sensitive adhesives for a variety of applications, including water or solvent-based adhesives. Ionomers using poly(ethylene-methacrylic acid) chains can also be used in film packaging due to their transparency, toughness, flexibility, resistance to staining, high gas permeability, and low sealing temperature. These qualities also translate to a high demand for using the ionomers in food-packing materials.
With the addition of the ion to a certain percentage of the polymer chain, the viscosity of the ionomer increases. This behavior can make ionomers a good viscosification material for drilling fluid applications where the system is under a low shear rate. Using the ionomer to increase the viscosity of the system helps prevent shear thinning behaviors within the drilling fluid, especially at higher temperatures of operation.
Another application includes the ability of an ionomer to increase the compatibility of polymer blends. This phenomenon is driven by thermodynamics and is achieved through the introduction of specific interactions between functional groups that are increasingly favorable in the presence of a metal ion. The miscibility can be driven not only by the increasingly favorable reaction between functional groups on two different polymers but also by having a strong repulsive interaction between the neutral and ionic species present within an ionomer, which can drive one of these species to be more miscible with the species of the other polymer within the blend. Some ionomers have been used for shape memory applications, meaning the material has a fixed shape that can be reformed using external stresses above a critical temperature and cooled, then regains the original shape when brought above the critical temperature and allowed to cool under no external stresses. Ionomers can form both chemical and physical crosslinks that can be modified easily at moderate processing temperatures, are less dense than shape memory alloys, and have a higher chance of being biocompatible for biomedical devices.
Some more recent applications for ionomers include being used as ion-selective membranes in a variety of electrical and energy applications. Examples include the cation exchange membrane for fuel cells, which allow only protons or specific ions to cross the membrane, a polymer electrolyte membrane (PEM) water electrolyzer to optimize the uniform coating of the catalyst on membrane surfaces, a redox flow battery separator, electrodialysis, where ions are transported between solutions using the ionomer membrane, and electrochemical hydrogen compressors to increase the strength of the membrane against the pressure differentials that can occur within the compressor. | 1 | Solid-state chemistry |
As proposed originally by Landau
free electrons in a solid, introduced for example by doping or irradiation, can interact with the vibrations of the lattice to form a localized quasi-particle known as a polaron. Strongly localized polarons (also called Holstein polarons) can condensate around high-symmetry sites of the lattice with electrons or holes occupying local degenerate orbitals that experience the JTE. These Jahn–Teller polarons break both translational and point group symmetries of the lattice where they are found and have been attributed important roles in effects like colossal magnetoresistance and superconductivity.
Paramagnetic impurities in semiconducting, dielectric, diamagnetic and ferrimagnetic hosts can all be described using a JT model. For example, these models were used extensively in the 1980s and 1990s to describe ions of Cr, V and Ti substituting for Ga in GaAs and GaP.
The fullerene C can form solid compounds with alkali metals known as fullerides. CsC can be superconducting at temperatures up to 38K under applied pressure, whereas compounds of the form AC are insulating (as reviewed by Gunnarsson). JT effects both within the C molecules (intramolecular) and between C molecules (intermolecular) play a part in the mechanisms behind various observed properties in these systems. For example, they could mean that the Migdal–Eliashberg treatment of superconductivity breaks down. Also, the fullerides can form a so-called new state of matter known as a Jahn–Teller metal, where localised electrons coexist with metallicity and JT distortions on the C molecules persist. | 1 | Solid-state chemistry |
Berzelius was a prolific correspondent with leading scientists of his time, such as Gerardus Johannes Mulder, Claude Louis Berthollet, Humphry Davy, Friedrich Wöhler, Eilhard Mitscherlich and Christian Friedrich Schönbein.
In 1812, Berzelius traveled to London, England, including Greenwich to meet with prominent British scientists of the time. These included Humphry Davy, chemist William Wollaston, physician-scientist Thomas Young, astronomer William Herschel, chemist Smithson Tennant, and inventor James Watt, among others. Berzelius also visited Davys laboratory. After his visit to Davys laboratory, Berzelius remarked, "A tidy laboratory is a sign of a lazy chemist."
Humphry Davy in 1810 proposed that chlorine is an element. Berzelius rejected this claim because of his belief that all acids were based on oxygen. Since chlorine forms a strong acid (muriatic acid, modern HCl), chlorine must contain oxygen and thus cannot be an element. However, in 1812, Bernard Courtois proved that iodine is an element. Then in 1816 Joseph-Louis Gay-Lussac demonstrated that prussic acid (hydrogen cyanide) contains only hydrogen, carbon, and nitrogen, and no oxygen. These findings persuaded Berzelius that not all acids contain oxygen, and that Davy and Gay-Lussac were correct: chlorine and iodine are indeed elements. | 1 | Solid-state chemistry |
Specific temperature at a specific pressure at which large groups of micelles begin to precipitate out into a quasi-separate phase. As temperature is raised above the cloud point this causes the distinct surfactant phase to form densely packed micelle groups known as aggregates. The phase separation is a reversible separation controlled by enthalpy (promotes aggregation/separation) above the cloud point, and entropy (promotes miscibility of micelles in water) below the cloud point. The cloud point is the equilibrium between the two free energies. | 0 | Colloidal Chemistry |
Barium stannate is an oxide of barium and tin with the chemical formula BaSnO. It is a wide band gap semiconductor with a perovskite crystal structure. | 1 | Solid-state chemistry |
Nanoparticles can also be formed using radiation chemistry. Radiolysis from gamma rays can create strongly active free radicals in solution. This relatively simple technique uses a minimum number of chemicals. These including water, a soluble metallic salt, a radical scavenger (often a secondary alcohol), and a surfactant (organic capping agent). High gamma doses on the order of 10 gray are required. In this process, reducing radicals will drop metallic ions down to the zero-valence state. A scavenger chemical will preferentially interact with oxidizing radicals to prevent the re-oxidation of the metal. Once in the zero-valence state, metal atoms begin to coalesce into particles. A chemical surfactant surrounds the particle during formation and regulates its growth. In sufficient concentrations, the surfactant molecules stay attached to the particle. This prevents it from dissociating or forming clusters with other particles. Formation of nanoparticles using the radiolysis method allows for tailoring of particle size and shape by adjusting precursor concentrations and gamma dose. | 0 | Colloidal Chemistry |
Beyond arranging lipids in a way that reduces surface tension, SP-B actually directly interferes with attractive forces between water molecules. This disruption in the cohesion of water minimizes further the surface tension at the gas/fluid interface. | 0 | Colloidal Chemistry |
Coral calcium is a salt of calcium derived from fossilized coral reefs. Coral calcium is composed of calcium carbonate and trace minerals. Claims for health benefits unique to coral calcium have been discredited. Coral calcium, marketed as a cure for various diseases and linked to Okinawan longevity, is merely calcium carbonate and can be considered a calcium supplement, and it supposed superiority to regular calcium carbonate has not been proven. The Okinawa Centenarian Study (OCS) in 2003 clarified that Okinawan longevity is due to a healthy lifestyle, not coral calcium. The OCS did not endorse coral calcium due to its cost, lack of scientific evidence supporting health claims, and environmental concerns about coral reefs. In 2004, the US Federal Trade Commission prohibited the marketers from making unsupported health claims about coral calcium. | 1 | Solid-state chemistry |
A suspension is a heterogeneous mixture in which the solid particles do not dissolve, but get suspended throughout the bulk of the solvent, left floating around freely in the medium. The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending agents.
An example of a suspension would be sand in water. The suspended particles are visible under a microscope and will settle over time if left undisturbed. This distinguishes a suspension from a colloid, in which the colloid particles are smaller and do not settle. Colloids and suspensions are different from solution, in which the dissolved substance (solute) does not exist as a solid, and solvent and solute are homogeneously mixed.
A suspension of liquid droplets or fine solid particles in a gas is called an aerosol. In the atmosphere, the suspended particles are called particulates and consist of fine dust and soot particles, sea salt, biogenic and volcanogenic sulfates, nitrates, and cloud droplets.
Suspensions are classified on the basis of the dispersed phase and the dispersion medium, where the former is essentially solid while the latter may either be a solid, a liquid, or a gas.
In modern chemical process industries, high-shear mixing technology has been used to create many novel suspensions.
Suspensions are unstable from a thermodynamic point of view but can be kinetically stable over a longer period of time, which in turn can determine a suspension's shelf life. This time span needs to be measured in order to provide accurate information to the consumer and ensure the best product quality.
"Dispersion stability refers to the ability of a dispersion to resist change in its properties over time." | 0 | Colloidal Chemistry |
There are several techniques used to map out which phase is present during perturbations done on the lipid. These perturbations include pH changes, temperature changes, pressure changes, volume changes, etc.
The most common technique used to study phospholipid phase presence is phosphorus nuclear magnetic resonance (31P NMR). In this technique, different and unique powder diffraction patterns are observed for lamellar, hexagonal, and isotropic phases. Other techniques that are used and do offer definitive evidence of existence of lamellar and hexagonal phases include freeze-fracture electron microscopy, X-ray diffraction, differential scanning calorimetry (DSC), and deuterium nuclear magnetic resonance (2H NMR).
Additionally, negative staining transmission electron microscopy has been shown as a useful tool to study lipid bilayer phase behavior and polymorphism into lamellar phase, micellar, unilamellar liposome, and hexagonal aqueous-lipid structures, in aqueous dispersions of membrane lipids. As water-soluble negative stain is excluded from the hydrophobic part (fatty acyl chains) of lipid aggregates, the hydrophilic headgroup portions of the lipid aggregates stain dark and clearly mark the outlines of the lipid aggregates (see figure). | 0 | Colloidal Chemistry |
For polymeric nanoparticles, the induction of stimuli-responsiveness has usually relied heavily upon well-known polymers that possess an inherent stimuli-responsiveness. Certain polymers that can undergo reversible phase transitions due to changes in temperature or pH have aroused interest.
Arguably the most utilized polymer for activation-modulated delivery is the thermo-responsive polymer poly(N-isopropylacrylamide). It is readily soluble in water at room temperature but precipitates reversibly from when the temperature is raised above its lower critical solution temperature (LCST), changing from an extended chain conformation to a collapsed chain. This feature presents a way to change the hydrophilicity of a polymer via temperature.
Efforts also focus on dual stimuli-responsive drug delivery systems, which can be harnessed to control the release of the encapsulated drug. For example, the triblock copolymer of poly(ethylene glycol)-b-poly(3-aminopropyl-methacrylamide)-b-poly(N-isopropylacrylamide) (PEG-b-PAPMA-b-PNIPAm) can self-assemble to form micelles, possessing a core–shell–corona architecture above the lower critical solution temperature. It is also pH responsive. Therefore, drug release can be tuned by changing either temperature or pH conditions. | 0 | Colloidal Chemistry |
A variety of methods are available for hobbyists to make soap. Most soapmakers use processes where the glycerol remains in the product, and the saponification continues for many days after the soap is poured into molds. The glycerol is left during the hot process method, but at the high temperature employed, the reaction is practically completed in the kettle, before the soap is poured into molds. This simple and quick process is employed in small factories all over the world.
Handmade soap from the cold process also differs from industrially made soap in that an excess of fat or (Coconut Oil, Cazumbal Process) are used, beyond that needed to consume the alkali (in a cold-pour process, this excess fat is called "superfatting"), and the glycerol left in acts as a moisturizing agent. However, the glycerine also makes the soap softer. The addition of glycerol and processing of this soap produces glycerin soap. Superfatted soap is more skin-friendly than one without extra fat, although it can leave a "greasy" feel. Sometimes, an emollient is added, such as jojoba oil or shea butter. Sand or pumice may be added to produce a scouring soap. The scouring agents serve to remove dead cells from the skin surface being cleaned. This process is called exfoliation.
To make antibacterial soap, compounds such as triclosan or triclocarban can be added. There is some concern that use of antibacterial soaps and other products might encourage antimicrobial resistance in microorganisms. | 1 | Solid-state chemistry |
Under Alivisatos’ leadership, the Lawrence Berkeley National Lab shifted its priorities to the more interdisciplinary areas of renewable energy and climate-change research. During his tenure, the Lab began construction on new buildings for computational research, building efficiencies, solar energy research, and biological science.
Alivisatos focused on integrating the Lab into the nation's innovation ecosystem, especially in the areas of energy and the environment. While some of the groundwork for this integration was laid by former Director Steve Chu, Alivisatos led efforts to leverage the wide range of scientific capabilities at Berkeley Lab with a variety of industry partners and entrepreneurs. These public/private sector collaborations resulted in technology transfer for industries as diverse as automobiles and medicine, and contributed to an increased speed of development in manufacturing and renewable energy. On March 23, 2015 Alvisatos announced that he would step down as Director when a replacement was identified.
Alivisatos has also been outspoken on the issue of basic science funding at the federal level and America's ability to stay competitive in the areas global scientific research and development. | 1 | Solid-state chemistry |
MoS@Fe-N-C core/shell nanosphere with atomic Fe-doped surface and interface (MoS/Fe-N-C) can be used as a used an electrocatalyst for oxygen reduction and evolution reactions (ORR and OER) bifunctionally because of reduced energy barrier due to Fe-N dopants and unique nature of MoS/Fe-N-C interface. | 1 | Solid-state chemistry |
A laser beam passes through the electrophoresis cell, irradiates the particles dispersed in it, and is scattered by the particles. The scattered light is detected by a photo-multiplier after passing through two pinholes. There are two types of optical systems: heterodyne and fringe.
Ware and Flygare developed a heterodyne-type ELS instrument, that was the first instrument of this type. In a fringe optics ELS instrument, a laser beam is divided into two beams. Those cross inside the electrophresis cell at a fixed angle to produce a fringe pattern. The scattered light from the particles, which migrates inside the fringe, is intensity-modulated. The frequency shifts from both types of optics obey the same equations. The observed spectra resemble each other.
Oka et al. developed an ELS instrument of heterodyne-type optics that is now available commercially. Its optics is shown in Fig. 3.
If the frequencies of the intersecting laser beams are the same then it is not possible to resolve the direction of the motion of the migrating particles. Instead, only the magnitude of the velocity (i.e., the speed) can be determined. Hence, the sign of the zeta potential cannot be ascertained. This limitation can be overcome by shifting the frequency of one of the beams relative to the other. Such shifting may be referred to as frequency modulation or, more colloquially, just modulation. Modulators used in ELS may include piezo-actuated mirrors or acousto-optic modulators. This modulation scheme is employed by the heterodyne light scattering method, too.
Phase-analysis light scattering (PALS) is a method for evaluating zeta potential, in which the rate of phase change of the interference between light scattered by the sample and the modulated reference beam is analyzed. This rate is compared with a mathematically generated sine wave predetermined by the modulator frequency. The application of large fields, which can lead to sample heating and breakdown of the colloids is no longer required. But any non-linearity of the modulator or any change in the characteristics of the modulator with time will mean that the generated sine wave will no longer reflect the real conditions, and the resulting zeta-potential measurements become less reliable.
A further development of the PALS technique is the so-called "continuously monitored PALS" (cmPALS) technique, which addresses the non-linearity of the modulators. An extra modulator detects the interference between the modulated and unmodulated laser light. Thus, its beat frequency is solely the modulation frequency and is therefore independent of the electrophoretic motion of the particles. This results in faster measurements, higher reproducibility even at low applied electric fields as well as higher sensitivity of the measurement. | 0 | Colloidal Chemistry |
A 2008 study explored the usage of femtosecond laser irradiation to create permanent spatial arrangements in transparent materials, particularly in its usage to form a singular foamed layer upon biopolymers such as collagen or curcumin. Foaming these surfaces results in a variety of surface modifications that may improve the material's ability for cell adhesion, permeability of fluids due to cell structure, and the formation of nanoscopic fibers.
Additionally, an iron-nitrogen co-doped carbon nanofoam was purposed to be fabricated through the acile salt-assisted pyrolysis process of chitooligosaccharides. | 0 | Colloidal Chemistry |
He was on the faculties of Arizona State University (1992–1998) as an assistant professor, the University of Michigan (1999–2006) as the Robert W. Parry Professor of Chemistry, and the University of California, Los Angeles (2007–2012) as the Christopher S. Foote Professor of Chemistry as well as holding the Irving and Jean Stone Chair in Physical Sciences.
In 2012, he moved to the University of California, Berkeley where he is now the James and Neeltje Tretter Professor of Chemistry. He was the director of the Molecular Foundry at Lawrence Berkeley National Laboratory from 2012 through 2013. He is the Founding Director of the Berkeley Global Science Institute. He is also a co-director of the Kavli Energy NanoSciences Institute of the University of California, Berkeley and the Lawrence Berkeley National Laboratory, the California Research Alliance by BASF, as well as the Bakar Institute of Digital Materials for the Planet. | 1 | Solid-state chemistry |
TRPS was developed by Izon Science Limited, producer of commercially available nanopore-based particle characterization systems. Izon Science Limited currently sell one TRPS device, known as the "Exoid". Previous devices include the "qNano", the "qNano Gold" and the "qViron". These systems have been applied to measure a wide range of biological and synthetic particle types including viruses and nanoparticles. TRPS has been applied in both academic and industrial research fields, including:
*Drug delivery research (e.g. lipid nanoparticles and liposomes)
*Extracellular vesicles such as exosomes
*Virology and vaccine production
*Biomedical diagnostics
*Microfluidics | 0 | Colloidal Chemistry |
Proton tunneling is a type of quantum tunneling involving the instantaneous disappearance of a proton in one site and the appearance of the same proton at an adjacent site separated by a potential barrier. The two available sites are bounded by a double well potential of which its shape, width and height are determined by a set of boundary conditions. According to the WKB approximation, the probability for a particle to tunnel is inversely proportional to its mass and the width of the potential barrier. Electron tunneling is well-known. A proton is about 2000 times more massive than an electron, so it has a much lower probability of tunneling; nevertheless, proton tunneling still occurs especially at low temperatures and high pressures where the width of the potential barrier is decreased.
Proton tunneling is usually associated with hydrogen bonds. In many molecules that contain hydrogen, the hydrogen atoms are linked to two non-hydrogen atoms via a hydrogen bond at one end and a covalent bond at the other. A hydrogen atom without its electron is reduced to being a proton. Since the electron is no longer bound to the hydrogen atom in a hydrogen bond, this is equivalent to a proton resting in one of the wells of a double well potential as described above. When proton tunneling occurs, the hydrogen bond and covalent bonds are switched. Once proton tunneling occurs, the same proton has the same probability of tunneling back to its original site provided the double well potential is symmetrical.
The base pairs of a DNA strand are connected by hydrogen bonds. In essence, the genetic code is contained by a unique arrangement of hydrogen bonds. It is believed that upon the replication of a DNA strand there is a probability for proton tunneling to occur which changes the hydrogen bond configuration; this leads to a slight alteration of the hereditary code which is the basis of mutations. Likewise, proton tunneling is also believed to be responsible for the occurrence of the dysfunction of cells (tumors and cancer) and ageing.
Proton tunneling occurs in many hydrogen based molecular crystals such as ice. It is believed that the phase transition between the hexagonal (ice Ih) and orthorhombic (ice XI) phases of ice is enabled by proton tunneling. The occurrence of correlated proton tunneling in clusters of ice has also been reported recently. | 1 | Solid-state chemistry |
Rüdorff was born in Berlin in 1909. He studied chemistry as an undergraduate at Technical University of Berlin and graduated in 1925. His graduate study was carried out under the supervision of Ulrich Hofmann at the same university, where he graduated with a PhD thesis titled Über die Kristallstruktur der Hexacarbonyle von Chrom, Molybdän und Wolfram. He then moved to the University of Rostock along with Ulrich Hofmann and achieved his habilitation status with the thesis titled Neuartige Verbindungen mit Graphit in 1941. In 1942, Rüdorff moved to Technical University of Vienna following Ulrich Hofmann. He later took up a faculty position at University of Tübingen in 1947. He stayed in Tübingen until his retirement.
Along with his supervisor Ulrich Hofmann and his father Karl Andreas Hofmann, Rüdorff cowrote the famous textbook on inorganic chemistry that are referred to as Rüdorff-Hofmann. | 1 | Solid-state chemistry |
Klemm was reportedly a Professor for inorganic chemistry in Düsseldorf at some time between 1929 and 1933. | 1 | Solid-state chemistry |
In the mid-1990s, Girolami began an investigation of the synthesis of new magnetic solids via a building block approach, publishing in Science in 1995. Girolami also reported metal-substituted analogs of Prussian blue that have magnetic ordering temperatures above 100 °C. | 1 | Solid-state chemistry |
Elemental chlorine can be produced by electrolysis of brine (NaCl solution). This process also produces sodium hydroxide (NaOH) and Hydrogen gas (H). The reaction equations are as follows:
* Cathode:
* Anode:
* Overall process: | 1 | Solid-state chemistry |
The electrostatic potential energy, E, between a pair of ions of equal and opposite charge is:
where
:z = magnitude of charge on one ion
:e = elementary charge, 1.6022 C
:ε = permittivity of free space
::4ε = 1.112 C/(J·m)
:r = distance separating the ion centers
For a simple lattice consisting ions with equal and opposite charge in a 1:1 ratio, interactions between one ion and all other lattice ions need to be summed to calculate E, sometimes called the Madelung or lattice energy:
where
:M = Madelung constant, which is related to the geometry of the crystal
:r = closest distance between two ions of opposite charge | 1 | Solid-state chemistry |
The Salt Service is one of the smallest services under the Government of India with a sanctioned strength of only 11 posts. As a central engineering service, recruitment to the Indian Salt Service is conducted by the Union Public Service Commission. | 1 | Solid-state chemistry |
Nanocomposite hydrogels are observed to be temperature sensitive and will change temperature when their surrounding is altered. Inorganic salts, when absorbed, will result in changing the hydrogels to a lower temperature whereas cat-ionic surfactant will shift the temperature the other way. The temperature of these hydrogels are around 40 degrees Celsius, making it a possible candidate for use as biomaterial. The stimulus-sensitivity of hydrogels allow for a responsive release system where the hydrogels can be designed to deliver the drug in response to changes in condition of the body. | 0 | Colloidal Chemistry |
Nickel (III) oxide is the inorganic compound with the formula NiO. It is not well characterized, and is sometimes referred to as black nickel oxide. Traces of NiO on nickel surfaces have been mentioned.
Nickel (III) oxide has been studied theoretically since the early thirties, supporting its unstable nature at standard temperatures. A nanostructured pure phase of the material was synthesized and stabilized for the first time in 2015 from the reaction of nickel(II) nitrate with sodium hypochlorite and characterized using powder X-ray diffraction and electron microscopy. | 1 | Solid-state chemistry |
Miedema's approach has been applied to the classification of miscible and immiscible systems of binary alloys. These are relevant in the design of multicomponent alloys. A comprehensive classification of alloying behavior for 813 binary alloy systems consisting of transition and lanthanide metals. "Impressively, the classification by the miscibility map yields a robust validation on the capability of the well-known Miedema’s theory (95% agreement) and shows good agreement with the HTFP method (90% agreement)." These 2017 results demonstrate that "a state-of-the art physics-guided data mining can provide an efficient pathway for knowledge discovery in the next generation of materials design". | 1 | Solid-state chemistry |
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