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In chemistry, the lattice energy is the energy change upon formation of one mole of a crystalline ionic compound from its constituent ions, which are assumed to initially be in the gaseous state. It is a measure of the cohesive forces that bind ionic solids. The size of the lattice energy is connected to many other physical properties including solubility, hardness, and volatility. Since it generally cannot be measured directly, the lattice energy is usually deduced from experimental data via the Born–Haber cycle. | 1 | Solid-state chemistry |
Foamed biopolymers have multiple purported applications in the biomedical and pharmaceuticals industry due to their modified surface properties. Gelatine films with curcumin dropped upon the surface, for instance, displayed a higher tolerance for ablation following its foaming; this tolerance is suspected to arise from curcumin's binding to proteins to protect from free radicals, as well as its anti-oxidant properties. These findings present implications for greater cellular surgery, as well as the manufacturing of biopolymers as a whole, due to these modifications from plasma irradiation. | 0 | Colloidal Chemistry |
Gas-phase nephelometers are also used in the detection of smoke and other particles of combustion. In such use, the apparatus is referred to as an aspirated smoke detector. These have the capability to detect extremely low particle concentrations (to 0.005%) and are therefore highly suitable to protecting sensitive or valuable electronic equipment, such as mainframe computers and telephone switches. | 0 | Colloidal Chemistry |
A nanoparticle sizer, also known as a nanoparticle analyzer, is a device used to measure the size, size distribution, and concentration of nanoparticles in a sample. The size of nanoparticles is typically in the range of 1 to 100 nanometers (nm), and they are much smaller than the particles that can be measured with conventional particle size analyzers. | 0 | Colloidal Chemistry |
Hazen worked on his B.S. and S.M. (Master of Science) in Earth Science at the Massachusetts Institute of Technology 1971. He started with the intention of going into chemical engineering, but he was captivated by the enthusiasm of David Wones and converted to mineralogy. With Wones as advisor, he completed a masters thesis on cation substitution in trioctahedral micas; his publication in American Mineralogist was his first to be highly cited. He completed a Ph.D. in Mineralogy & Crystallography at Harvard University in 1975. His thesis, with Charles Burnham as advisor, involved learning how to use a 4-circle diffractometer to do high-pressure X-ray crystallography and applying it to olivine. This became a focus of his early career.
While a NATO Postdoctoral Fellow at Cambridge University in England, Hazen worked with Charles Prewitt to determine empirical relations for the effect of temperature and pressure on interatomic distances in oxides and silicates. | 1 | Solid-state chemistry |
The discharge could contain trace chemical products used during the industrial treatments applies,such as antiscalants, coagulants, flocculants, which are discarded together with the discharge, and which could affect the physical-chemical quality of the effluent. However, these are practically consumed during the process and the concentrations in the discharge are very low, which are practically diluted during the discharge, without affecting marine ecosystems. | 1 | Solid-state chemistry |
Structures may form during continued sedimentary loading, without any external tectonic influence, due to gravitational instability. Pure halite has a density of 2160 kg/m. When initially deposited, sediments generally have a lower density of 2000 kg/m, but with loading and compaction their density increases to 2500 kg/m, which is greater than that of salt. Once the overlying layers have become denser, the weak salt layer will tend to deform into a characteristic series of ridges and depressions, due to a form of Rayleigh–Taylor instability. Further sedimentation will be concentrated in the depressions and the salt will continue to move away from them into the ridges. At a late stage, diapirs tend to initiate at the junctions between ridges, their growth fed by movement of salt along the ridge system, continuing until the salt supply is exhausted. During the later stages of this process the top of the diapir remains at or near the surface, with further burial being matched by diapir rise, and is sometimes referred to as downbuilding. The Schacht Asse II and Gorleben salt domes in Germany are an example of a purely passive salt structure.
Such structures do not always form when a salt layer is buried beneath a sedimentary overburden. This can be due to a relatively high strength overburden or to the presence of sedimentary layers interbedded within the salt unit that increase both its density and strength. | 1 | Solid-state chemistry |
NiO is useful for illustrating the failure of density functional theory (using functionals based on the local-density approximation) and Hartree–Fock theory to account for the strong correlation. The term strong correlation refers to behavior of electrons in solids that is not well described (often not even in a qualitatively correct manner) by simple one-electron theories such as the local-density approximation (LDA) or Hartree–Fock theory. For instance, the seemingly simple material NiO has a partially filled 3d-band (the Ni atom has 8 of 10 possible 3d-electrons) and therefore would be expected to be a good conductor. However, strong Coulomb repulsion (a correlation effect) between d-electrons makes NiO instead a wide band gap Mott insulator. Thus, NiO has an electronic structure that is neither simply free-electron-like nor completely ionic, but a mixture of both. | 1 | Solid-state chemistry |
Molten flux synthesis can be an efficient method for obtaining single crystals. In this method, the starting reagent are combined with flux, an inert material with a melting point lower than that of the starting materials. The flux serves as a solvent. After the reaction, the excess flux can be washed away using an appropriate solvent or it can be heat again to remove the flux by sublimation if it is a volatile compound.
Crucible materials have a great role to play in molten flux synthesis. The crucible should not react with the flux or the starting reagent. If any of the material is volatile, it is recommended to conduct the reaction in a sealed ampule. If the target phase is sensitive to oxygen, a carbon- coated fused silica tube or a carbon crucible inside a fused silica tube is often used which prevents the direct contact between the tube wall and reagents. | 1 | Solid-state chemistry |
To modify the performance of lecithin to make it suitable for the product to which it is added, it may be hydrolysed enzymatically. In hydrolysed lecithins, a portion of the phospholipids have one fatty acid removed by phospholipase. Such phospholipids are called lysophospholipids. The most commonly used phospholipase is phospholipase A2, which removes the fatty acid at the C2 position of glycerol. Lecithins may also be modified by a process called fractionation. During this process, lecithin is mixed with an alcohol, usually ethanol. Some phospholipids, such as phosphatidylcholine, have good solubility in ethanol, whereas most other phospholipids do not dissolve well in ethanol. The ethanol is separated from the lecithin sludge, after which the ethanol is removed by evaporation to obtain a phosphatidylcholine-enriched lecithin fraction. | 0 | Colloidal Chemistry |
Saiful is a Fellow of the Royal Society of Chemistry (FRSC) since 2008 and the Institute of Materials, Minerals and Mining (FIMMM), as well as Honorary Fellow of the British Science Association.
Saiful has received several RSC research awards including 2008 Francis Bacon Medal for Fuel Cell Science, 2011 Materials Chemistry Division Lecturer Award, 2013 Sustainable Energy Award, 2013 Wolfson Research Merit Award from the Royal Society, 2017 Peter Day Award for Materials Chemistry, 2020 Storch Award in Energy Chemistry from the American Chemical Society, 2022 Hughes Medal from the Royal society, and the Robert Perrin Award from Institute of Materials, Minerals and Mining.
In 2019, he declined a New Year Honours Award of an Order of the British Empire, because he is "never been comfortable with the words ‘British Empire’ in this award and the links to empire, colonialism, and slavery". | 1 | Solid-state chemistry |
The early studies indicating anomalous increases in nanofluid thermal properties over those of the base fluid, particularly the heat transfer coefficient, have been largely discredited. One of the main conclusions taken from a study involving over thirty labs throughout the world was that "no anomalous enhancement of thermal conductivity was observed in the limited set of nanofluids tested in this exercise". The COST funded research programme, Nanouptake (COST Action CA15119)[http://www.nanouptake.eu/] was founded with the intention "to develop and foster the use of nanofluids as advanced heat transfer/thermal storage materials to increase the efficiency of heat exchange and storage systems". One of the final outcomes, involving an experimental study in five different labs, concluded that "there are no anomalous or unexplainable effects".
Despite these apparently conclusive experimental investigations theoretical papers continue to follow the claim of anomalous enhancement, see, particularly via Brownian and thermophoretic mechanisms, as suggested by Buongiorno. Brownian diffusion is due to the random drifting of suspended nanoparticles in the base fluid which originates from collisions between the nanoparticles and liquid molecules. Thermophoresis induces nanoparticle migration from warmer to colder regions, again due to collisions with liquid molecules. The mismatch between experimental and theoretical results is explained in Myers et al. In particular it is shown that Brownian motion and thermophoresis effects are too small to have any significant effect: their role is often amplified in theoretical studies due to the use of incorrect parameter values. Experimental validation of the assertions of are provided in Alkasmoul et al. Brownian diffusion as a cause for enhanced heat transfer is dismissed in the discussion of the use of nanofluids in solar collectors. | 0 | Colloidal Chemistry |
Once the unit cell of a new phase is known, the next step is to establish the stoichiometry of the phase. This can be done in several ways. Sometimes the composition of the original mixture will give a clue, under the circumstances that only a product with a single powder pattern is found or a phase of a certain composition is made by analogy to known material, but this is rare.
Often, considerable effort in refining the synthetic procedures is required to obtain a pure sample of the new material. If it is possible to separate the product from the rest of the reaction mixture, elemental analysis methods such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM) can be used. The detection of scattered and transmitted electrons from the surface of the sample provides information about the surface topography and composition of the material. Energy dispersive X-ray spectroscopy (EDX) is a technique that uses electron beam excitation. Exciting the inner shell of an atom with incident electrons emits characteristic X-rays with specific energy to each element. The peak energy can identify the chemical composition of a sample, including the distribution and concentration.Similar to EDX, X-ray diffraction analysis (XRD) involves the generation of characteristic X-rays upon interaction with the sample. The intensity of diffracted rays scattered at different angles is used to analyze the physical properties of a material such as phase composition and crystallographic structure. These techniques can also be coupled to achieve a better effect. For example, SEM is a useful complement to EDX due to its focused electron beam, it produces a high-magnification image that provides information on the surface topography. Once the area of interest has been identified, EDX can be used to determine the elements present in that specific spot. Selected area electron diffraction can be coupled with TEM or SEM to investigate the level of crystallinity and the lattice parameters of a sample. | 1 | Solid-state chemistry |
West was educated at The Harvey Grammar School and then University College Swansea where he gained a Bachelor of Science in chemistry in 1968. He then moved to the University of Aberdeen where he completed a PhD in 1971 under the supervision of Fredrik P. Glasser.
He was appointed lecturer at the University of Aberdeen in 1971 and gained his Doctor of Science (DSc) from the university in 1984. He became professor in chemistry in 1989. He then moved to the University of Sheffield in 1999 to become Head of the Department of Engineering Materials. | 1 | Solid-state chemistry |
In Korean folk medicine, trace elements in the yellow clay and bamboo are thought to make this form of salt more healthy. Historically, has been used as a digestive aid, styptic, disinfectant or dentifrice.
Oriental medicinalist Insan Kim Il-hoon (1909–1992), was (according to his institution) the first to claim that could be used to treat cancer. His other claims are that can be used to treat intestinal inflammation, peptic ulcer disease, dyspepsia, esophageal tumours and more. | 1 | Solid-state chemistry |
The moving-boundary electrophoresis apparatus includes a U-shaped cell filled with buffer solution and electrodes immersed at its ends. The sample applied could be any mixture of charged components such as a protein mixture. On applying voltage, the compounds will migrate to the anode or cathode depending on their charges. The change in the refractive index at the boundary of the separated compounds is detected using schlieren optics at both ends of the solution in the cell. | 0 | Colloidal Chemistry |
Albert Ernest Alexander (1914–1970) was a British-Australian chemist known for his pioneering work with colloids. | 0 | Colloidal Chemistry |
Baron Jöns Jacob Berzelius ( (20 August 1779 – 7 August 1848) was a Swedish chemist. In general, he is considered the last person to know the whole field of chemistry. Berzelius is considered, along with Robert Boyle, John Dalton, and Antoine Lavoisier, to be one of the founders of modern chemistry. Berzelius became a member of the Royal Swedish Academy of Sciences in 1808 and served from 1818 as its principal functionary. He is known in Sweden as the "Father of Swedish Chemistry". During his lifetime he did not customarily use his first given name, and was universally known simply as Jacob Berzelius.
Although Berzelius began his career as a physician, his enduring contributions were in the fields of electrochemistry, chemical bonding and stoichiometry. In particular, he is noted for his determination of atomic weights and his experiments that led to a more complete understanding of the principles of stoichiometry, which is the branch of chemistry pertaining to the quantitative relationships between elements in chemical compounds and chemical reactions and that these occur in definite proportions. This understanding came to be known as the "Law of Constant Proportions".
Berzelius was a strict empiricist, expecting that any new theory must be consistent with the sum of contemporary chemical knowledge. He developed improved methods of chemical analysis, which were required to develop the basic data in support of his work on stoichiometry. He investigated isomerism, allotropy, and catalysis, phenomena that owe their names to him. Berzelius was among the first to articulate the differences between inorganic compounds and organic compounds. Among the many minerals and elements he studied, he is credited with discovering cerium and selenium, and with being the first to isolate silicon and thorium. Following on his interest in mineralogy, Berzelius synthesized and chemically characterized new compounds of these and other elements.
Berzelius demonstrated the use of an electrochemical cell to decompose certain chemical compounds into pairs of electrically opposite constituents. From this research, he articulated a theory that came to be known as electrochemical dualism, contending that chemical compounds are oxide salts, bonded together by electrostatic interactions. This theory, while useful in some contexts, came to be seen as insufficient. Berzelius's work with atomic weights and his theory of electrochemical dualism led to his development of a modern system of chemical formula notation that showed the composition of any compound both qualitatively and quantitatively. His system abbreviated the Latin names of the elements with one or two letters and applied superscripts to designate the number of atoms of each element present in the compound. Later, chemists changed to use of subscripts rather than superscripts. | 1 | Solid-state chemistry |
The spin and dip coating methods are simple methods for nanoparticle deposition. They are useful tools especially in creating self-assembled layers and films where the packing density isn't critical. Accurate and vibration-free sample withdrawal speeds can be used to have control over the film thickness. Creating high density monolayers is typically very difficult since the methods are lacking the packing density control. Also, the volume of nanoparticle suspension required for both spin coating and dip coating is rather big which may be an issue when using expensive nanoparticle materials. | 0 | Colloidal Chemistry |
A wide variety of techniques can be used to analyze the interfacial layer, often SAXS, NMR, AFM, STM are used, but other methods, like measuring the refractive index can reveal information as well.
Small-angle X-ray diffraction provides data about the size and dispersion of the nanoparticles, and gives information about the density of the interfacial layer. Because the amount of scattering is proportionate with the density. On top of this the thickness of the layer can be estimated. However a disadvantage is that SAXS is destructive.
AFM and STM measurements can reveal information at atomic resolution about the structure and shape of the interfacial layer. This information is limited to the surface of the nanoparticle, as you can only probe the surface. Another drawback of STM is that it's only applicable if the interfacial layer is conducting.
(Solid-state) NMR can be used to study the composition, short range ordering and dynamics in the interfacial layer. The dynamics can be studied over a wide range of timescales, which allows the intermolecular interactions, chemical reactions and transport phenomena to be analyzed. | 0 | Colloidal Chemistry |
Stephen Lee (; born 25 October 1955) is an American chemist. He is the son of Tsung-Dao Lee, the winner of the 1957 Nobel Prize in Physics. He is currently a professor at Cornell University. | 1 | Solid-state chemistry |
In a vacuum, the PAC probe can be evaporated onto the sample. The radioactive probe is applied to a hot plate or filament, where it is brought to the evaporation temperature and condensed on the opposite sample material. With this method, e.g. surfaces are examined. Furthermore, by vapor deposition of other materials, interfaces can be produced. They can be studied during tempering with PAC and their changes can be observed. Similarly, the PAC probe can be transferred to sputtering using a plasma. | 1 | Solid-state chemistry |
In his career, he has published over 500 peer-reviewed papers, 36 of them in Nature and 8 of them in Science. These papers have been cited over 30,000 times, including his seminal work on BaYCuO (YBCO), which has been cited almost 1500 times. He holds 15 patents.
His former doctoral students include Leslie Schoop. | 1 | Solid-state chemistry |
He has received honorary degrees from universities around the world. Visveswaraya Technological University and The Assam Royal Global University, Guwahati 2022. | 1 | Solid-state chemistry |
Surfactin has non-specific cytotoxicity, causing lysis through disruption to the phospholipid bilayer present in all cells. When injected into humans as an intravascular antibiotic at concentrations at or above the of 40-60 μM, surfactin has hemolytic effects. | 0 | Colloidal Chemistry |
Pyrite is distinguishable from native gold by its hardness, brittleness and crystal form. Pyrite fractures are very uneven, sometimes conchoidal because it does not cleave along a preferential plane. Native gold nuggets, or glitters, do not break but deform in a ductile way. Pyrite is brittle, gold is malleable.
Natural gold tends to be anhedral (irregularly shaped without well defined faces), whereas pyrite comes as either cubes or multifaceted crystals with well developed and sharp faces easy to recognise. Well crystallised pyrite crystals are euhedral (i.e., with nice faces). Pyrite can often be distinguished by the striations which, in many cases, can be seen on its surface. Chalcopyrite () is brighter yellow with a greenish hue when wet and is softer (3.5–4 on Mohs' scale). Arsenopyrite (FeAsS) is silver white and does not become more yellow when wet. | 1 | Solid-state chemistry |
Karl Andreas Hofmann (2 April 1870 – 15 October 1940) was a German inorganic chemist. He is best known for his discovery of a family of clathrates which consist of a 2-D metal cyanide sheet, with every second metal also bound axially to two other ligands. These materials have been named Hofmann clathrates in his honour. | 1 | Solid-state chemistry |
Matthew Jonathan Rosseinsky FRS is Professor of Inorganic Chemistry at the University of Liverpool. He was awarded the Hughes Medal in 2011 "for his influential discoveries in the synthetic chemistry of solid state electronic materials and novel microporous structures."
He has been awarded the Harrison Memorial Prize (1991), Corday-Morgan Medal and Prize (2000) and Tilden Lectureship (2006) of the Royal Society of Chemistry (RSC). In 2009, he was awarded the inaugural De Gennes Prize by the RSC, a lifetime achievement award in materials chemistry, open internationally. In 2013, he became a Royal Society Research Professor.
In 2017, he was awarded the Davy Medal of the Royal Society for “his advances in the design and discovery of functional materials, integrating the development of new experimental and computational techniques.” He gave the Muetterties Lectures at UC Berkeley and the Lee Lectures at the University of Chicago in 2017. In 2019, he gave the Flack Memorial Lectures of the Swiss Crystallographic Society and was awarded the Frankland Lectureship by Imperial College London. In 2020, he was made an Honorary Fellow of the Chemical Research Society of India. In 2022, he gave the Davison Lectures at the Massachusetts Institute of Technology, and received the Basolo Award of the Chicago Section of the American Chemical Society.
He was a member of the Science Minister’s Advanced Materials Leadership Council from 2014-2016, and of the governing Council of the Engineering and Physical Sciences Research Council from 2015-2019.
In 2023, he received the Eni Energy Frontiers Award for the digital design and discovery of next-generation energy materials from the President of Italy. | 1 | Solid-state chemistry |
# J. Lyklema, Fundamentals of Interface and Colloid Science
# F.H.J. van der Heyden et al., Phys. Rev. Lett. 95, 116104 (2005)
# C. Werner et al., J. Colloid Interface Sci. 208, 329 (1998)
# Mansouri et al. The Journal of Physical Chemistry C, 112(42), 16192 (2008) | 0 | Colloidal Chemistry |
Lanthanum strontium cobalt ferrite (LSCF), also called lanthanum strontium cobaltite ferrite is a specific ceramic oxide derived from lanthanum cobaltite of the ferrite group. It is a phase containing lanthanum(III) oxide, strontium oxide, cobalt oxide and iron oxide with the formula , where 0.1≤x≤0.4 and 0.2≤y≤0.8.
It is black in color and crystallizes in a distorted hexagonal perovskite structure. LSCF undergoes phase transformations at various temperatures depending on the composition. This material is a mixed ionic electronic conductor with comparatively high electronic conductivity (200+ S/cm) and good ionic conductivity (0.2 S/cm). It is typically non-stoichiometric and can be reduced further at high temperature in low oxygen partial pressures or in the presence of a reducing agent such as carbon.
LSCF is being investigated as a material for intermediate temperature solid oxide fuel cell cathodes and, potentially as a direct carbon fuel cell anode.
LSCF is also investigated as a membrane material for separation of oxygen from air, for use in e.g. cleaner burning power plants. | 1 | Solid-state chemistry |
Alivisatos is an internationally recognized authority on nano chemistry in the synthesis of semiconductor quantum dots and multi-shaped artificial nanostructures. Further, he is a world expert on the chemistry of nanoscale crystals; one of his papers (Science, 271: 933–937, 1996) has been cited over 13,800 times. He is also an expert on how these can be applied, for example as biological markers (e.g., Science, 281: 2013–16, 1998; a paper cited over 10,900 times). In addition, his use of DNA in this area (DNA nanotechnology) has shown the surprising versatility of this molecule. He has used it to direct crystal growth and create new materials, as in Nature, 382: 609–11, 1996, and even to measure nanoscale distances (see Nature Nanotechnology, 1: 47–52, 2006).
He is widely recognized as being the first to demonstrate that semiconductor nanocrystals can be grown into complex two-dimensional shapes, as opposed to simple one-dimensional spheres. Alivisatos proved that controlling the growth of nanocrystals is the key to controlling both their size and shape. This achievement altered the nanoscience landscape and paved the way for a slew of new potential applications, including biomedical diagnostics, revolutionary photovoltaic cells, and LED materials. | 1 | Solid-state chemistry |
Monodisperse, nanometer-size clusters (also known as nanoclusters) are synthetically grown crystals whose size and structure influence their properties through the effects of quantum confinement. One method of growing these crystals is through inverse micellar cages in non-aqueous solvents. Research conducted on the optical properties of MoS nanoclusters compared them to their bulk crystal counterparts and analyzed their absorbance spectra. The analysis reveals that size dependence of the absorbance spectrum by bulk crystals is continuous, whereas the absorbance spectrum of nanoclusters takes on discrete energy levels. This indicates a shift from solid-like to molecular-like behavior which occurs at a reported cluster the size of 4.5 – 3.0 nm.
Interest in the magnetic properties of nanoclusters exists due to their potential use in magnetic recording, magnetic fluids, permanent magnets, and catalysis. Analysis of Fe clusters shows behavior consistent with ferromagnetic or superparamagnetic behavior due to strong magnetic interactions within clusters.
Dielectric properties of nanoclusters are also a subject of interest due to their possible applications in catalysis, photocatalysis, micro capacitors, microelectronics, and nonlinear optics. | 0 | Colloidal Chemistry |
The lattice energy of an ionic compound depends strongly upon the charges of the ions that comprise the solid, which must attract or repel one another via Coulomb's Law. More subtly, the relative and absolute sizes of the ions influence . London dispersion forces also exist between ions and contribute to the lattice energy via polarization effects. For ionic compounds made of molecular cations and/or anions, there may also be ion-dipole and dipole-dipole interactions if either molecule has a molecular dipole moment. The theoretical treatments described below are focused on compounds made of atomic cations and anions, and neglect contributions to the internal energy of the lattice from thermalized lattice vibrations. | 1 | Solid-state chemistry |
As a researcher, Sadoway has focused on environmental ways to extract metals from their ores, as well as producing more efficient batteries. His research has often been driven by the desire to reduce greenhouse gas emissions while improving quality and lowering costs. He is the co-inventor of a solid polymer electrolyte. This material, used in his "sLimcell" has the capability of allowing batteries to offer twice as much power per kilogram as is possible in current lithium ion batteries.
In August 2006, a team that he led demonstrated the feasibility of extracting iron from its ore through molten oxide electrolysis. When powered exclusively by renewable electricity, this technique has the potential to eliminate the carbon dioxide emissions that are generated through traditional methods.
In 2009, Sadoway disclosed the liquid metal battery comprising liquid layers of magnesium and antimony separated by a layer of molten salt that could be used for stationary energy storage. Research on this concept was being funded by ARPA-E and the French energy company Total Experimental data showed a 69% DC-to-DC storage efficiency with good storage capacity and relatively low leakage current (self discharge). In 2010, with funding from Bill Gates and Total, Sadoway and two others, David Bradwell and Luis Ortiz, co-founded a company called the Liquid Metal Battery Corporation (later, Ambri) in order to scale up and commercialize the technology. | 1 | Solid-state chemistry |
Fatty acid ethoxylates are a class of very versatile surfactants, which combine in a single molecule the characteristic of a weakly anionic, pH-responsive head group with the presence of stabilizing and temperature responsive ethyleneoxide units. | 0 | Colloidal Chemistry |
In hydrogenated silicon, dangling bonds can be induced by (long) exposure to light. This causes a decrease in the photoconductivity of the material. (This is the most named explanation for the so-called Staebler-Wronski effect.) The mechanism of this is thought to be as follows: The photon energy is transferred to the system which causes the weak Si-Si bonds to break, leading to the formation of two bound radicals. The free electrons being localized and being very close together is an unstable state, so hydrogen atoms “move” to the site of the breakage. This causes the electrons to be delocalized further apart which is a more stable state. For a hydrogen content of around 10%, the dangling bonds from only a very small fraction of displaced hydrogen atoms can lead to observable EPR signal increases. The diffusion of hydrogen plays a key role in the process and explains why long illumination is required. It has been found that illumination under increased temperatures increases the rate at which light-induced dangling bonds form. This can be explained by the increased hydrogen diffusion.
It is thought that the formation mechanism of intrinsic dangling bonds (in hydrogenated silicon) is very similar to that of light induced dangling bonds, except that the energy source is heat rather than photons. This explains why the intrinsic dangling bond density is negligible at room temperature.
Light can also induce dangling bond formation in materials with intimately related valence alternation pairs (IVAP), such as a-AsS. These IVAP defects consist of a dangling bond containing two electrons (D) and a dangling bond containing no electrons (D). When one of these pairs is illuminated, it can capture an electron or an electron hole resulting in the following reactions:
DD + e → DD
DD + h → DD
Here, D is an uncharged dangling bond. | 1 | Solid-state chemistry |
*Infant respiratory distress syndrome (IRDS) is caused by lack of surfactant, commonly seen in premature babies born before 28–32 weeks of gestation.
*Congenital surfactant deficiency
*Pulmonary alveolar proteinosis
*Surfactant metabolism dysfunction | 0 | Colloidal Chemistry |
Hydrogels also possess a degree of flexibility very similar to natural tissue due to their significant water content. As responsive "smart materials", hydrogels can encapsulate chemical systems which upon stimulation by external factors such as a change of pH may cause specific compounds such as glucose to be liberated to the environment, in most cases by a gel–sol transition to the liquid state. Chemomechanical polymers are mostly also hydrogels, which upon stimulation change their volume and can serve as actuators or sensors. | 0 | Colloidal Chemistry |
At the beginning of 2008, potash prices started a meteoric climb from less than US$200 a tonne to a high of US$875 in February 2009. These subsequently dropped dramatically to an April 2010 low of US$310 level, before recovering in 2011–12, and relapsing again in 2013. For reference, prices in November 2011 were about US$470 per tonne, but as of May 2013 were stable at US$393. After the surprise breakup of the world's largest potash cartel at the end of July 2013, potash prices were poised to drop some 20 percent. At the end of Dec 2015, potash traded for US$295 a tonne. In April 2016 its price was US$269. In May 2017, prices had stabilised at around US$216 a tonne down 18% from the previous year. By January 2018, prices have been recovering to around US$225 a tonne. World potash demand tends to be price inelastic in the short-run and even in the long run. | 1 | Solid-state chemistry |
In 2008, Hazen was an outgoing member of the AAAS Committee on Public Understanding of Science and Technology. He and his wife Margee, noting that it is important for scientists to engage with the public but actually doing so does not help them get tenure, proposed a new award, The Early Career Award for Public Engagement with Science, and established a fund for it. The first award, with a monetary prize of $5,000, was announced in 2010. | 1 | Solid-state chemistry |
Europium(II) oxide (EuO) is a chemical compound which is one of the oxides of europium. In addition to europium(II) oxide, there is also europium(III) oxide and the mixed valence europium(II,III) oxide. | 1 | Solid-state chemistry |
Layered electrides or electrenes are single-layer materials consisting of alternating atomically thin two-dimensional layers of electrons and ionized atoms. The first example was CaN, in which the charge (+4) of two calcium ions is balanced by the charge of a nitride ion (-3) in the ion layer plus a charge (-1) in the electron layer. | 1 | Solid-state chemistry |
Originally, an alcoholate was the crystalline form of a salt in which alcohol took the place of water of crystallization, such as [SnCl(OCH)·CHOH] and CHNO·CHOH. However this denomination should not be used anymore for the ending -ate often occurs in names for anions.
The second meaning of the word is that of a tincture, or alcoholic extract of plant material.
The third, and more usual meaning of the word is as a synonym for alkoxide— is the conjugate base of an alcohol. | 1 | Solid-state chemistry |
Kê was born in Penglai, Shandong province. He was admitted to Tsinghua University in 1930 but suffered pulmonary disease which required him to rest for two years where he earned a B.S. in physics in 1937. He obtained an M.S. in physics at Yenching University in 1940. In July 1941, Kê married He Yizhen in Shanghai and the following month they traveled together to California. Kê received his Ph.D. in physics after only pursuing it for two years at the University of California at Berkeley in 1943. In the years 1943–1945 and 1945–1949, respectively, he worked as a staff member at the Massachusetts Institute of Technology and research associate at the University of Chicago.
In 1949, Kê returned to China and became a professor in physics at Tsinghua University and a research associate at the Applied Physics Laboratory of the Chinese Academy of Sciences (CAS). In October 1952, he relocated to Shenyang to participate in the establishment of the Institute of Metal Research of CAS as a research associate where he became deputy director from 1961 to 1981. In 1955, Kê was elected academician of CAS and became a member of the Mathematics and Physics Committee of CAS. In 1980, he was transferred to Hefei for the establishment of the Hefei branch of CAS where he served as its deputy director and later jointly became the first head of the Institute of Solid State Physics incepted in March 1982.
In 1979 he was a visiting professor at the Max-Planck Institut für Metallforschung in Germany, and in 1980, a guest professor at the INSA de Lyon in France. | 1 | Solid-state chemistry |
Wüstite forms a solid solution with periclase (MgO), and iron substitutes for magnesium. Periclase, when hydrated, forms brucite (Mg(OH)), a common product of serpentinite metamorphic reactions.
Oxidation and hydration of wüstite forms goethite and limonite.
Zinc, aluminium, and other metals may substitute for iron in wüstite.
Wüstite in dolomite skarns may be related to siderite (iron(II) carbonate), wollastonite, enstatite, diopside, and magnesite. | 1 | Solid-state chemistry |
Copper(II) chloride is used in pyrotechnics as a blue/green coloring agent. In a flame test, copper chlorides, like all copper compounds, emit green-blue light.
In humidity indicator cards (HICs), cobalt-free brown to azure (copper(II) chloride base) HICs can be found on the market. In 1998, the European Community classified items containing cobalt(II) chloride of 0.01 to 1% w/w as T (Toxic), with the corresponding R phrase of R49 (may cause cancer if inhaled). Consequently, new cobalt-free humidity indicator cards containing copper have been developed.
Copper(II) chloride is used as a mordant in the textile industry, petroleum sweetener, wood preservative, and water cleaner. | 1 | Solid-state chemistry |
Berzelius was born in the parish of Väversunda in Östergötland in Sweden. His father Samuel Berzelius was a school teacher in the nearby city of Linköping, and his mother Elizabeth Dorothea Sjösteen was a homemaker. His parents were both from families of church pastors. Berzelius lost both his parents at an early age. His father died in 1779, after which his mother married a pastor named Anders Eckmarck, who gave Berzelius a basic education including knowledge of the natural world. Following the death of his mother in 1787, relatives in Linköping took care of him. There he attended the school today known as Katedralskolan. As a teenager, he took a position as a tutor at a farm near his home, during which time he became interested in collecting flowers and insects and their classification.
Berzelius later enrolled as a medical student at Uppsala University, from 1796 to 1801. Anders Gustaf Ekeberg, the discoverer of tantalum, taught him chemistry during this time. He worked as an apprentice in a pharmacy, during which time he also learned practical matters in the laboratory such as glassblowing. On his own during his studies, he successfully repeated the experimentation conducted by Swedish chemist Carl William Scheele which led to Scheeles discovery of oxygen. He also worked with a physician in the Medevi mineral springs. During this time, he conducted an analysis of the water from this source. Additionally as part of his studies, in 1800, Berzelius learned about Alessandro Voltas electric pile, the first device that could provide a constant electric current (i.e., the first battery). He constructed a similar battery for himself, consisting of alternating disks of copper and zinc, and this was his initial work in the field of electrochemistry.
As thesis research in his medical studies, he examined the influence of galvanic current on several diseases. This line of experimentation produced no clear-cut evidence for such influence. Berzelius graduated as a medical doctor in 1802. He worked as a physician near Stockholm until the chemist and mine-owner Wilhelm Hisinger recognized his abilities as an analytical chemist and provided him with a laboratory. | 1 | Solid-state chemistry |
Like conventional thermite, super thermite reacts at very high temperature and is difficult to extinguish. The reaction produces dangerous ultra-violet (UV) light, requiring that the reaction not be viewed directly or that special eye protection (for example, a welder's mask) be worn.
In addition, super thermites are very sensitive to electrostatic discharge (ESD). Surrounding the metal oxide particles with carbon nanofibers may make nanothermites safer to handle. | 0 | Colloidal Chemistry |
The Jahn–Teller effect is most often encountered in octahedral complexes of the transition metals. The phenomenon is very common in six-coordinate copper(II) complexes. The d electronic configuration of this ion gives three electrons in the two degenerate e orbitals, leading to a doubly degenerate electronic ground state. Such complexes distort along one of the molecular fourfold axes (always labelled the z axis), which has the effect of removing the orbital and electronic degeneracies and lowering the overall energy. The distortion normally takes the form of elongating the bonds to the ligands lying along the z axis, but occasionally occurs as a shortening of these bonds instead (the Jahn–Teller theorem does not predict the direction of the distortion, only the presence of an unstable geometry). When such an elongation occurs, the effect is to lower the electrostatic repulsion between the electron-pair on the Lewis basic ligand and any electrons in orbitals with a z component, thus lowering the energy of the complex. The inversion centre is preserved after the distortion.
In octahedral complexes, the Jahn–Teller effect is most pronounced when an odd number of electrons occupy the e orbitals. This situation arises in complexes with the configurations d, low-spin d or high-spin d complexes, all of which have doubly degenerate ground states. In such compounds the e orbitals involved in the degeneracy point directly at the ligands, so distortion can result in a large energetic stabilisation. Strictly speaking, the effect also occurs when there is a degeneracy due to the electrons in the t orbitals (i.e. configurations such as d or d, both of which are triply degenerate). In such cases, however, the effect is much less noticeable, because there is a much smaller lowering of repulsion on taking ligands further away from the t orbitals, which do not point directly at the ligands (see the table below). The same is true in tetrahedral complexes (e.g. manganate: distortion is very subtle because there is less stabilisation to be gained because the ligands are not pointing directly at the orbitals.
The expected effects for octahedral coordination are given in the following table:
w: weak Jahn–Teller effect (t orbitals unevenly occupied)
s: strong Jahn–Teller effect expected (e orbitals unevenly occupied)
blank: no Jahn–Teller effect expected.
The Jahn–Teller effect is manifested in the UV-VIS absorbance spectra of some compounds, where it often causes splitting of bands. It is readily apparent in the structures of many copper(II) complexes. Additional, detailed information about the anisotropy of such complexes and the nature of the ligand binding can be however obtained from the fine structure of the low-temperature electron spin resonance spectra. | 1 | Solid-state chemistry |
The nickel organic acid salts are organic acid salts of nickel. In many of these the ionised organic acid acts as a ligand.
Nickel acetate has the formula (CHCOO)Ni·4HO. It has monodentate acetate and hydrogen bonding. A dihydrate also exists. Nickel acetate is used to seal anodised aluminium.
Nickel formate decomposes when heated to yield carbon dioxide, carbon monoxide, hydrogen, water and finely divided porous nickel. All the nickel atoms are six coordinated, but half have four water molecules and two formate oxygens close to the atom, and the other half are coordinated by six oxygens of formate groups.
Aspergillus niger is able to dispose of otherwise toxic levels of nickel in its environment by forming nickel oxalate dihydrate crystals. nickel oxalate can also be formed in to various nanorods and nanofibres by use of surfacants. When heated nickel oxalate dihydrate dehydrates at 258° and decomposes to Ni metal over 316 °C. Double oxalate salts where oxalate is a ligand on the nickel atom may be called oxalatonickelates.
Other organic acid salts of nickel include nickel oleate, nickel propionate, nickel butyrate, nickel caprylate, nickel lactate, nickel benzoate, nickel bis(acetyl acetonate), nickel salicylate, nickel alkyl phenyl salicylate. Nickel stearate forms a green solution, however when precipitated with alcohol a gel is produced, that also contains a mixture of basic salts, and free stearic acid.
Nickel malonate, and nickel hydrogen malonate both crystallise with two molecules of water. They decomposes when heated to yield gaseous water, carbon dioxide, carbon monoxide, ethanol, acetic acid, methyl formate and ethyl formate. Nickel acetate exists as an intermediate and the final result is that solid nickel, nickel oxide, NiC and carbon remain. With malonate nickel can form a bis-malonato-nickelate anion, which can form double salts. Nickel maleate can be made from maleic acid and nickel carbonate in boiling water. A dihydrate crystallises from the water solution. Nickel fumarate prepared from fumaric acid and nickel carbonate is pale green as a tetrahydrate, and mustard coloured as an anhydride. It decomposes when heated to 300° to 340° in vacuum. Decomposition mostly produces nickel carbide, carbon dioxide, carbon monoxide and methane. But also produced were butanes, benzene, toluene, and organic acid.
Nickel succinate can form metal organic framework compounds.
Nickel citrate complexes are found in leaves of some nickel accumulating plant species in New Caledonia such as Pycnandra acuminata. Citrate complexes include NiHcit, NiHcit, Nicit, Nicit, and NiHcit. (ordered from low to high pH). Also there is NiHcit. Nickel citrate is important in nickel plating. When precipitation of nickel citrate is attempted a gel forms. This apparently consists of tangled fibres of [(CHO)Ni], which can be reduced to nickel metal fibres less than a micron thick, and meters long. Double nickel citrates exist, including tetraanion citrate when pH is over 9.5. An amorphous nickel iron citrate NiFeO(CHO)·6HO produces carbon monoxide, carbon dioxide and acetone when heated over 200 °C leaving Trevorite, NiFeO a nickel ferrite. A green crystalline nickel citrate with formula Ni(CHO)·10HO melts at 529K and decomposition starts at 333K.
Nickel glutarate in the form called Mil-77, [Ni{(CHO)(HO)}]⋅40HO is pale green. It crystallises in a porous structure containing twenty member rings. The 40 water molecules "occluded" in the porous channels come out when it is heated to 150 °C retaining the crystal framework. At 240 °C the crystal form changes and over 255° the remaining water is lost. Between 330° and 360° the organic components burn and it is destroyed.
Cyclopropane carboxylic acid forms two basic salts with nickel, a hydrate with density 1.554 Mg/m and an anhydrous form Ni(OH)(CHO) with density 2.172 mg/m.
Nickel trifluoroacetate tetrahydrate exists, as well as two emerald green acid trifluoroacetates, a bridged trinuclear form [Ni(CFCOO)(CFCOOH)](CFCOOH) and a hydrated acid form [Ni(CFCOO)(CFCOOH)(HO)](CFCOOH) both with triclinic crystal form. The first has density 2.205 and the second 2.124. They are made by dissolving the nickel trifluoroacetate tetrahydrate in trifluoroacetic acid either anhydrous or 1% hydrated.
Nickel naphthenate is used as a fuel additive to suppress smoke, as a rubber catalyst and as an oil additive.
When Nickel benzoate is heated in a vacuum, carbon dioxide, carbon monoxide, benzene, benzoic acid, phenol, biphenyl, nickel, nickel oxide, and nickel carbide are formed. It can crystallise as anhydrous, a trihydrate or a tetrahydrate.
Nickel terephthalate can be made by a double decomposition of sodium terephthalate and nickel nitrate. Nickel terephthalate precipitates. Its solubility is 0.38 g/100g water at 25 °C. In ammonium hydroxide a violet solution forms. Boiling acetic acid converts the nickel to nickel acetate. The terephthalate converts to a basic salt when boiled in water. Understating this compound is important when reducing coloured contaminants in polymers made from terephthalate. | 1 | Solid-state chemistry |
Potash refers to potassium compounds and potassium-bearing materials, most commonly potassium carbonate. The word "potash" originates from the Middle Dutch "potaschen", denoting "pot ashes" in 1477.
The old method of making potassium carbonate () was by collecting or producing wood ash (the occupation of ash burners), leaching the ashes, and then evaporating the resulting solution in large iron pots, which left a white residue denominated "pot ash". Approximately 10% by weight of common wood ash can be recovered as potash. Later, "potash" became widely applied to naturally occurring minerals that contained potassium salts and the commercial product derived from them,.
The following table lists a number of potassium compounds that have "potash" in their traditional names: | 1 | Solid-state chemistry |
Double layer forces occur between charged objects across liquids, typically water. This force acts over distances that are comparable to the Debye length, which is on the order of one to a few tenths of nanometers. The strength of these forces increases with the magnitude of the surface charge density (or the electrical surface potential). For two similarly charged objects, this force is repulsive and decays exponentially at larger distances, see figure. For unequally charged objects and eventually at shorted distances, these forces may also be attractive. The theory due to Derjaguin, Landau, Verwey, and Overbeek (DLVO) combines such double layer forces together with Van der Waals forces in order to estimate the actual interaction potential between colloidal particles.
An electrical double layer develops near charged surfaces (or another charged objects) in aqueous solutions. Within this double layer, the first layer corresponds to the charged surface. These charges may originate from tightly adsorbed ions, dissociated surface groups, or substituted ions within the crystal lattice. The second layer corresponds to the diffuse layer, which contains the neutralizing charge consisting of accumulated counterions and depleted coions. The resulting potential profile between these two objects leads to differences in the ionic concentrations within the gap between these objects with respect to the bulk solution. These differences generate an osmotic pressure, which generates a force between these objects.
These forces are easily experienced when hands are washed with soap. Adsorbing soap molecules make the skin negatively charged, and the slippery feeling is caused by the strongly repulsive double layer forces. These forces are further relevant in many colloidal or biological systems, and may be responsible for their stability, formation of colloidal crystals, or their rheological properties. | 0 | Colloidal Chemistry |
Hard toilet soap with a pleasant smell was produced in the Middle East during the Islamic Golden Age, when soap-making became an established industry. Recipes for soap-making are described by Muhammad ibn Zakariya al-Razi (c. 865–925), who also gave a recipe for producing glycerine from olive oil. In the Middle East, soap was produced from the interaction of fatty oils and fats with alkali. In Syria, soap was produced using olive oil together with alkali and lime. Soap was exported from Syria to other parts of the Muslim world and to Europe.
A 12th-century document describes the process of soap production. It mentions the key ingredient, alkali, which later became crucial to modern chemistry, derived from al-qaly or "ashes".
By the 13th century, the manufacture of soap in the Middle East had become a major cottage industry, with sources in Nablus, Fes, Damascus, and Aleppo. | 1 | Solid-state chemistry |
Every type of foam has its application. High-expansion foams are used when an enclosed space, such as a basement or hangar, must be quickly filled. Low-expansion foams are used on burning spills. AFFF is the best for spills of jet fuels, FFFP is better for cases where the burning fuel can form deeper pools, and AR-AFFF is suitable for burning alcohols. High-performing FFF are viable alternatives to AFFF and AFFF-AR for various applications. The most flexibility is achieved by AR-AFFF or AR-FFFP. AR-AFFF must be used in areas where gasoline is blended with oxygenates, since the alcohols prevent the formation of the film between the FFFP foam and the gasoline, breaking down the foam, and rendering the FFFP foam virtually useless. | 0 | Colloidal Chemistry |
Given the diversity of solid-state compounds, an equally diverse array of methods are used for their preparation. Synthesis can range from high-temperature methods, like the ceramic method, to gas methods, like chemical vapour deposition. Often, the methods prevent defect formation or produce high-purity products. | 1 | Solid-state chemistry |
Hydrotropes are in use industrially and commercially in cleaning and personal care product formulations to allow more concentrated formulations of surfactants. About 29,000 metric tons are produced (i.e., manufactured and imported) annually in the US. Annual production (plus importation) in Europe and Australia is approximately 17,000 and 1,100 metric tons, respectively.
Common products containing hydrotropes include laundry detergents, surface cleaners, dishwashing detergents, liquid soaps, shampoos and conditioners. They are coupling agents, used at concentrations from 0.1 to 15% to stabilize the formula, modify viscosity and cloud-point, reduce phase separation in low temperatures, and limit foaming.
Adenosine triphosphate (ATP) has been shown to prevent aggregation of proteins at normal physiologic concentrations and to be approximately an order of magnitude more effective than sodium xylene sulfonate in a classic hydrotrope assay. The hydrotrope activity of ATP was shown to be independent of its activity as an "energy currency" in cells. Additionally, ATP function as biological hydrotope has been shown proteome-wide under near native conditions. In a recent study, however, the hydrotropic capabilities of ATP have been questioned as it has severe salting-out characteristics due to its triphosphate moiety. | 0 | Colloidal Chemistry |
In 2018 the New Jersey Department of Environmental Protection (NJDEP) published a drinking water standard for PFNA. Public water systems in New Jersey are required to meet an MCL standard of 13 ppt. In 2020 the state set a PFOA standard at 14 ppt and a PFOS standard at 13 ppt.
In 2019 NJDEP filed lawsuits against the owners of two plants that had manufactured PFASs, and two plants that were cited for water pollution from other chemicals. The companies cited are DuPont, Chemours and 3M. NJDEP also declared five companies to be financially responsible for statewide remediation of the chemicals. Among the companies accused were Arkema and Solvay regarding a West Deptford Facility in Gloucester County, where Arkema manufactured PFASs, but Solvay claims to have never manufactured but only handled PFASs. The companies denied liability and contested the directive. In June 2020, the U.S. Environmental Protection Agency and New Jersey Department of Environmental Protection published a paper reporting that a unique family of PFAS used by Solvay, chloroperfluoropolyether carboxylates (ClPFPECAs), were contaminating the soils of New Jersey as far from the Solvay facility as 150 km. and the ClPFPECAs were found in water as well.
Later in 2020, the New Jersey state attorney general filed suit in the New Jersey Superior Court against Solvay regarding PFAS contamination of the state's environment. In May 2021, Solvay issued a press release that the company is "discontinuing the use of fluorosurfactants in the U.S.". | 0 | Colloidal Chemistry |
Professor Mukherjee proposed the idea of making the Indian Agricultural Research Institute,(IARI) a regular University. In 1958, on the recommendation of
the Indo-American Team on Agricultural Research and Education and with the generous aid of the Rockefeller Foundation, the Post-Graduate School was established
at this Institute by the Governmental of India. The Institute now enjoys the status of a University under the University Grants Commission Act of 1956. | 0 | Colloidal Chemistry |
Nanofluids are produced by several techniques:
# Direct Evaporation (1 step)
# Gas condensation/dispersion (2 step)
# Chemical vapour condensation (1 step)
# Chemical precipitation (1 step)
# Bio-based (2 step)
Several liquids including water, ethylene glycol, and oils have been used as base fluids. Although stabilization can be a challenge, on-going research indicates that it is possible. Nano-materials used so far in nanofluid synthesis include metallic particles, oxide particles, carbon nanotubes, graphene nano-flakes and ceramic particles.
A bio-based, environmentally friendly approach for the covalent functionalization of multi-walled carbon nanotubes (MWCNTs) using clove buds was developed. There are no any toxic and hazardous acids which are typically used in common carbon nanomaterial functionalization procedures, employed in this synthesis. The MWCNTs are functionalized in one pot using a free radical grafting reaction. The clove-functionalized MWCNTs are then dispersed in distilled water (DI water), producing a highly stable MWCNT aqueous suspension (MWCNTs Nanofluid). | 0 | Colloidal Chemistry |
Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride, magnesium sulfate, potassium nitrate, and sodium bicarbonate which dissolve into ions. The concentration of dissolved chloride ions is sometimes referred to as chlorinity. Operationally, dissolved matter is defined as that which can pass through a very fine filter (historically a filter with a pore size of 0.45 μm, but nowadays usually 0.2 μm). Salinity can be expressed in the form of a mass fraction, i.e. the mass of the dissolved material in a unit mass of solution.
Seawater typically has a mass salinity of around 35 g/kg, although lower values are typical near coasts where rivers enter the ocean. Rivers and lakes can have a wide range of salinities, from less than 0.01 g/kg to a few g/kg, although there are many places where higher salinities are found. The Dead Sea has a salinity of more than 200 g/kg. Precipitation typically has a TDS of 20 mg/kg or less.
Whatever pore size is used in the definition, the resulting salinity value of a given sample of natural water will not vary by more than a few percent (%). Physical oceanographers working in the abyssal ocean, however, are often concerned with precision and intercomparability of measurements by different researchers, at different times, to almost five significant digits. A bottled seawater product known as IAPSO Standard Seawater is used by oceanographers to standardize their measurements with enough precision to meet this requirement. | 1 | Solid-state chemistry |
The system was originally conceived as building blocks for solid-state hard-wired programmed logic controllers (the predecessors of programmable logic controllers (PLC)) to replace electro-mechanical relay logic in industrial control systems for process control and automation applications, similar to early Telefunken/AEG Logistat, Siemens Simatic, Brown, Boveri & C, ACEC Logacec or Estacord systems.
Each available logical function was recognizable by the color of its plastic container, black, blue, red, green, violet, etc. The most important circuit block contained a NOR gate (hence the name), but there were also blocks containing drivers, and a timer circuit similar to the later 555 timer IC.
The original Norbit modules of the YL 6000 series introduced in 1960 had potted single in-line packages with up to ten long flying leads arranged in two groups of up to five leads in a row. These modules were specified for frequencies of less than 1 kHz at ±24 V supply.
Also available in 1960 were so called Combi-Element modules in single-in line packages with ten evenly spaced stiff leads in a row (5.08 mm / 0.2-inch pitch) for mounting on a PCB. They were grouped in the 1-series (aka "100 kHz series") with ±6 V supply. The newer 10-series and 20-series had similarly sized packages, but came with an additional parallel row of nine staggered leads for a total of 19 leads. The 10-series uses germanium alloy transistors, whereas in the 20-series silicon planar transistors are used for a higher cut-off frequency of up to 1 MHz (vs. 30 kHz) and a higher allowed temperature range of +85 °C (vs. +55 °C).
In 1967, the Philips/Mullard NORBIT 2 aka Valvo NORBIT-S family of modules was introduced, first consisting of the 60-series for frequencies up to 10 kHz at a single supply voltage of 24 V, only. Later, the 61-series, containing thyristor trigger and control modules, was added. A 90-series became available in the mid-1970s as well. There were three basic types contained in a large (one by two inch-sized) 17 pins dual in-line package, with nine pins spaced 5.08 mm (0.2-inch) on one side and eight staggered pins on the other side. | 1 | Solid-state chemistry |
Magnetic material synthesis and characterization technology continue to improve, allowing for the production of various shapes, sizes, and compositions of magnetic material to be studied and tuned for improved properties. One of the places which has seen great advancement is in the synthesis of magnetic materials at nanometer length scales. Nanoparticle research has seen a great deal of interest in a number of fields as many phenomena can be explained by what is occurring on the nanoscale, which can be probed more effectively using nanometer sized materials. One unique type of materials which have seen a recent surge in research interest have been known as "nanoflakes" where they resemble flakes or discs of nanometer thickness and micrometer dimensions. Nanomaterials of this shape have seen use in a number of fields including energy storage, as [electrodes] of electrochemical cells, and in cancer therapy to kill cancer cells. | 0 | Colloidal Chemistry |
As described above, lecithin is highly processed. Therefore, genetically modified (GM) protein or DNA from the original GM crop from which it is derived often is undetectable – in other words, it is not substantially different from lecithin derived from non-GM crops. Nonetheless, consumer concerns about genetically modified food have extended to highly purified derivatives from GM food, such as lecithin. This concern led to policy and regulatory changes in the EU in 2000, when Commission Regulation (EC) 50/2000 was passed which required labelling of food containing additives derived from GMOs, including lecithin. Because it is nearly impossible to detect the origin of derivatives such as lecithin, the European regulations require those who wish to sell lecithin in Europe to use a meticulous, but essential system of identity preservation (IP). | 0 | Colloidal Chemistry |
The trans-pyramidalization distortion is taken as an example. The frontier molecular orbitals of the undistorted alkene possessing D symmetry have symmetries a (HOMO-1), b (HOMO), b (LUMO), and b (LUMO+1). The symmetry of the trans-pyramidalization vibration is b. A triple product of ground state, vibrational mode, and excited state that can be taken is b (HOMO) x b (trans-pyramidalizing vibrational mode) x b (LUMO+1) = a. Since a is the totally symmetric representation, the b and b molecular orbitals participate in an allowed interaction through the trans-pyramidalizing vibrational mode. The molecule will distort in a trans-pyramidal fashion (into C symmetry) in order to enable this interaction, which produces a more stabilized HOMO and more destabilized LUMO.
This treatment can be repeated for all other combinations of HOMO-1, HOMO and LUMO, LUMO+1. Notably, it is found that the HOMO and LUMO are symmetry-disallowed to mix. | 1 | Solid-state chemistry |
Institute of Solid State Chemistry and Mechanochemistry of the Siberian Branch of the RAS () is a research institute in Novosibirsk, Russia. It was founded in 1944. | 1 | Solid-state chemistry |
Mycosubtilin is a heptapeptide, cyclized in a ring with a β-amino fatty acid. The peptide sequence is composed of -Asn--Tyr--Asn--Gln--Pro--Ser--Asn. | 0 | Colloidal Chemistry |
Reutzel-Edens was a doctoral researcher at the University of Minnesota, where she studied the design and characterization of hydrogen-bonded imide aggregates. She worked in the laboratory of crystallographer Margaret C. Etter, and made use of solid state NMR. During her doctorate, she investigated how hydrogen bonds could be used as design elements that guided the solid-state self assembly of organic molecules. She made use of the Cambridge Structural Database to unravel the complicated relationships between hydrate formation and crystal polymorphism. | 1 | Solid-state chemistry |
Li joined the Rutgers Faculty as an assistant professor in 1991, where she was promoted to associate professor in 1996, full professor in 1999, and distinguished professor in 2006. Her current research group consists of postdoc associates, graduate students, visiting scientists, exchange graduate students and undergraduate students.
Li has developed and taught 17 different undergraduate and graduate courses since her first appointment with the university. | 1 | Solid-state chemistry |
Cobalt oxide nanoparticles have been observed to readily enter cells, a property that conceivably could lead to applications in hyperthermic treatment, gene therapy and drug delivery. However, their toxicity is an obstacle that would have to be overcome. | 1 | Solid-state chemistry |
The Bancroft rule in colloidal chemistry states: "The phase in which an emulsifier is more soluble constitutes the continuous phase." This means that water-soluble surfactants tend to give oil-in-water emulsions and oil-soluble surfactants give water-in-oil emulsions. It is a general rule of thumb, still used, but regarded as inferior to HLD theory (Hydrophilic Lipophilic Difference), which takes many more factors into consideration.
It was named after Wilder Dwight Bancroft, an American physical chemist, who proposed the rule in the 1910s. | 0 | Colloidal Chemistry |
The original betaine, N,N,N-trimethylglycine, was named after its discovery in sugar beet (Beta vulgaris subsp. vulgaris) in the nineteenth century. It is a small N-trimethylated amino acid. It is a zwitterion, which cannot isomerize because there is no labile hydrogen atom attached to the nitrogen atom. This substance may be called glycine betaine to distinguish it from other betaines. | 0 | Colloidal Chemistry |
Hazen was born in Rockville Centre, New York, on November 1, 1948. His parents were Peggy Hazen (née Dorothy Ellen Chapin; 1918–2002) and Dan Hazen (né Daniel Francis Hazen, Jr.; 1918–2016). He spent his early childhood in Cleveland, near a fossil quarry where he collected his first trilobite at the age of about 9.
The Hazen family moved to New Jersey, where Roberts eight-grade teacher, Bill Welsh, observed Roberts interest in his collection of minerals. Hazen later recalled "He gave me a starter collection of 100 specimens, mineral field guides, and mimeographed directions to Paterson and Franklin, New Jersey." Hazen also had an early interest in music, starting with the piano at age 5, the violin at 6 and the trumpet at age 9. | 1 | Solid-state chemistry |
A European research project demonstrated field effect transistors in which the gate (channel) is controlled via quantum tunnelling rather than by thermal injection, reducing gate voltage from ≈1 volt to 0.2 volts and reducing power consumption by up to 100×. If these transistors can be scaled up into VLSI chips, they would improve the performance per power of integrated circuits. | 1 | Solid-state chemistry |
Metal foams are popular support for electrocatalysts due to the high surface area and stable structure. The interconnected pores also benefit the mass transport of reactants and products. However, the benchmark of electrocatalysts can be difficult due to the undetermined surface area, different foam properties, and capillary effect. | 0 | Colloidal Chemistry |
Salinity in drylands can occur when the water table is between two and three metres from the surface of the soil. The salts from the groundwater are raised by capillary action to the surface of the soil. This occurs when groundwater is saline (which is true in many areas), and is favored by land use practices allowing more rainwater to enter the aquifer than it could accommodate. For example, the clearing of trees for agriculture is a major reason for dryland salinity in some areas, since deep rooting of trees has been replaced by shallow rooting of annual crops. | 1 | Solid-state chemistry |
N-Oleoylsarcosine is a clear, yellow to brown, viscous liquid, which is sparsely soluble in water and acts acidic. As long-chain N-acylamino acid, the surfactant is soluble in many organic solvents and in mineral oil. In the alkaline it dissolves well in water. Because of its carboxamide structure, Sarkosyl O is chemically stable even at high pH values and strongly foaming as an anionic surfactant. N-oleyl sarcosine is only slightly toxic and easily biodegradable. | 0 | Colloidal Chemistry |
Salt lakes form when the water flowing into the lake, containing salt or minerals, cannot leave because the lake is endorheic (terminal). The water then evaporates, leaving behind any dissolved salts and thus increasing its salinity, making a salt lake an excellent place for salt production. High salinity can also lead to halophilic flora and fauna in and around the lake; sometimes, in fact, the result may be an absence or near absence of multicellular life in the salt lake.
If the amount of water flowing into a lake is less than the amount evaporated, the lake will eventually disappear and leave a dry lake (also called playa or salt flat).
Brine lakes consist of water that has reached salt saturation or near saturation (brine), and may also be heavily saturated with other materials.
Most brine lakes develop as a result of high evaporation rates in an arid climate with a lack of an outlet to the ocean. The high salt content in these bodies of water may come from minerals deposited from the surrounding land. Another source for the salt may be that the body of water was formerly connected to the ocean. While the water evaporates from the lake, the salt remains. Eventually, the body of water will become brine.
Because of the density of brine, swimmers are more buoyant in brine than in fresh or ordinary salt water. Examples of such brine lakes are the Dead Sea and the Great Salt Lake.
Bodies of brine may also form on the ocean floor at cold seeps. These are sometimes called brine lakes, but are more frequently referred to as brine pools. It is possible to observe waves on the surface of these bodies.
Man-made bodies of brine are created for edible salt production. These can be referred to as brine ponds. | 1 | Solid-state chemistry |
Agents that increase surface tension are "surface active" in the literal sense but are not called surfactants as their effect is opposite to the common meaning. A common example of surface tension increase is salting out: adding an inorganic salt to an aqueous solution of a weakly polar substance will cause the substance to precipitate. The substance may itself be a surfactant, which is one of the reasons why many surfactants are ineffective in sea water. | 0 | Colloidal Chemistry |
To illustrate the functionality of polaritonic devices, consider the hypothetical circuit in Fig. 2 (right). The optical excitation pulses that generate phonon-polaritons, in the top left and bottom right of the crystal, enter normal to the crystal face (into the page). The resulting phonon-polaritons will travel laterally away from the excitation regions. Entrance into the waveguides is facilitated by reflective and focusing structures. Phonon-polaritons are guided through the circuit by terahertz waveguides carved into the crystal. Circuit functionality resides in the interferometer structure at the top and the coupled waveguide structure at the bottom of the circuit. The latter employs a photonic bandgap structure with a defect (yellow) that could provide bistability for the coupled waveguide. | 1 | Solid-state chemistry |
Polyurethane foam is a specialist material used for thermal insulation and other applications. It is a solid polymeric foam based on polyurethane chemistry. | 0 | Colloidal Chemistry |
In solution, detergents help solubilize a variety of chemical species by dissociating aggregates and unfolding proteins. Popular surfactants in the biochemistry laboratory are sodium lauryl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB). Detergents are key reagents to extract protein by lysis of the cells and tissues: They disorganize the membrane's lipid bilayer (SDS, Triton X-100, X-114, CHAPS, DOC, and NP-40), and solubilize proteins. Milder detergents such as octyl thioglucoside, octyl glucoside or dodecyl maltoside are used to solubilize membrane proteins such as enzymes and receptors without denaturing them. Non-solubilized material is harvested by centrifugation or other means. For electrophoresis, for example, proteins are classically treated with SDS to denature the native tertiary and quaternary structures, allowing the separation of proteins according to their molecular weight.
Detergents have also been used to decellularise organs. This process maintains a matrix of proteins that preserves the structure of the organ and often the microvascular network. The process has been successfully used to prepare organs such as the liver and heart for transplant in rats. Pulmonary surfactants are also naturally secreted by type II cells of the lung alveoli in mammals. | 0 | Colloidal Chemistry |
The dynamics of surfactant adsorption is of great importance for practical applications such as in foaming, emulsifying or coating processes, where bubbles or drops are rapidly generated and need to be stabilized. The dynamics of absorption depend on the diffusion coefficient of the surfactant. As the interface is created, the adsorption is limited by the diffusion of the surfactant to the interface. In some cases, there can exist an energetic barrier to adsorption or desorption of the surfactant. If such a barrier limits the adsorption rate, the dynamics are said to be ‘kinetically limited'. Such energy barriers can be due to steric or electrostatic repulsions.
The surface rheology of surfactant layers, including the elasticity and viscosity of the layer, play an important role in the stability of foams and emulsions. | 0 | Colloidal Chemistry |
Kanishk Biswas was born on 25 October 1982. Biswas obtained his MS degree in chemical science from Indian Institute of Science, Bangalore in 2006 and PhD degree from the same institute in 2009 both under the supervision of C. N. R. Rao. He had spent three years (June 2006 - May 2009) as Postdoctoral Fellow under the supervision of Mercouri Kanatzidis at Northwestern University, Evanston, IL, USA | 1 | Solid-state chemistry |
reacts with HCl or other chloride sources to form complex ions: the red (found in potassium trichloridocuprate(II) ) (it is a dimer in reality, , a couple of tetrahedrons that share an edge), and the green or yellow (found in potassium tetrachloridocuprate(II) ).
Some of these complexes can be crystallized from aqueous solution, and they adopt a wide variety of structures.
Copper(II) chloride also forms a variety of coordination complexes with ligands such as ammonia, pyridine and triphenylphosphine oxide:
: (tetragonal)
: (tetrahedral)
However "soft" ligands such as phosphines (e.g., triphenylphosphine), iodide, and cyanide as well as some tertiary amines induce reduction to give copper(I) complexes. | 1 | Solid-state chemistry |
Metal complexes containing C are known as metal carbido complexes. Most common are carbon-centered octahedral clusters, such as (where "Ph" represents a phenyl group) and [FeC(CO)]. Similar species are known for the metal carbonyls and the early metal halides. A few terminal carbides have been isolated, such as .
Metallocarbohedrynes (or "met-cars") are stable clusters with the general formula where M is a transition metal (Ti, Zr, V, etc.). | 1 | Solid-state chemistry |
In 1962 he was named the first director of the Materials Research Laboratory at Penn State. He edited the Proceedings of a 1968 Conference on the chemistry of silicon carbide. The next year a national colloquy was held on materials science in the United States for which Roy edited the Proceedings. In 1973 he edited the Proceedings of a conference on phase transitions and their applications.
In 1974 Roy and Olaf Müller published The Major Ternary Structural Families with Springer-Verlag, which described the principal crystal structures of ternary compounds. The book received two brief reviews in materials trade journals. A cement journal reviewer said it would be "Useful to the practicing materials researcher, whether in industry or university, as well as the non-specialist who needs to become informed about particular materials."
A chemist writing for mineral processing readers, described its depth:
:The structural descriptions are at times too brief but the chapters contain valuable information such as compositional structure field maps (radius A vs. radius B), figures of unit cells or the polyhedral arrangements in some common structures, phase diagrams (P vs. T , or P vs. ionic radius), structural relationships, and phase transition data.
By 1991 he was a spokesperson for the movement and his lecture "New Materials: Fountainhead for New Technologies and New Science" was published by National Academy Press. Roy presented the lecture to learned audiences in Washington, D.C.; Tokyo, Japan; New Delhi, Stockholm, Copenhagen, and London in 1991 and 92. He made the case for linking a technical need to investigative effort, which he terms "technology traction", noting that the method is productive and cost-effective in comparison to science conducted with other purposes.
Rustum Roy was referred to as "[o]ne of the legends of materials science" at the time of his death.
Roy was elected as a member of the U.S. National Academy of Engineering in 1973. | 1 | Solid-state chemistry |
Utilizing powder metallurgy routes for titanium foam fabrication allows for production at lower temperatures than those required through a melt process and reduces overall risks for contamination. In loose-powder sintering (also known as gravity sintering), pores are created through diffusion bonding arising from the voids existing between packed powder particles. Axial compaction followed by sintering follows the same procedure as above, but pressures is applied for compaction of the precursor material. For both compaction methods, the resulting pore morphology is dependent upon the morphology of the metallic powder, making it difficult to control the size, shape, and distribution of the pores. Another disadvantage includes the relatively high probability of pore collapse and limited achievable porosity levels. | 0 | Colloidal Chemistry |
In the Asakura–Oosawa model for depletion forces, the change in free-energy imposed by an excluded cosolute, , is:
where is the osmotic pressure, and is the change in excluded volume (which is related to molecular size and shape). The very same result can be derived using the Kirkwood-Buff solution theory. | 0 | Colloidal Chemistry |
Fichtner was educated in Food Chemistry and Chemistry at the University Karlsruhe, now Karlsruhe Institute of Technology where he was awarded by the Diploma in Chemistry. In 1992 he received the Ph.D. in Chemistry/Surface Science with distinction and the Hermann Billing Award for his thesis. In the thesis he developed a novel method for a spatially resolved speciation of beam-sensitive salts by SIMS. With the method he analysed the surface composition of atmospheric salt aerosol particles and contributed to the current climate model. | 1 | Solid-state chemistry |
Depletion forces in colloid-polymer mixtures drive colloids to form aggregates that are densely packed locally. This local dense packing is also observed in colloidal systems without polymer depletants. Without polymer depletants the mechanism is similar, because the particles in dense colloidal suspension act, effectively, as depletants for one another This effect is particularly striking for anisotropically shaped colloidal particles, where the anisotropy of the shape leads to the emergence of directional entropic forces that are responsible for the ordering of hard anisotropic colloids into a wide range of crystal structures. | 0 | Colloidal Chemistry |
GraphExeter is a material consisting of a few graphene sheets with a layer of ferric chloride molecules in between each graphene sheet. It was created by The Centre for Graphene Science at the University of Exeter in collaboration with the University of Bath. | 1 | Solid-state chemistry |
Zubbles is a commercial name for colored soap bubbles. Zubbles claim to fame is that they are the first colored soap bubbles that do not leave stains. Instead they fade away with exposure to air, pressure, and water.
Popular Science named Zubbles the "Innovation of the Year" for 2005. Readers Digest' agreed, saying they were one of the "Best Innovations" of the year in 2006. | 0 | Colloidal Chemistry |
There are several methods reported to reduce silver ion into zero-valent silver atoms:
*Chemical Reduction. Chemical reductants can reduce silver ions into silver nanoclusters. Some examples of chemical reductants are sodium borohydride (NaBH) and sodium hypophosphite (NaPOH.HO). For instance, Dickson and his research team have synthesized silver nanoclusters in DNA using sodium borohydride.
*Electrochemical Reduction. Silver nanoclusters can also be reduced electrochemically using reductants in the presence of stabilizing agents such as and tetrabutylammonium.
*Photoreduction. Silver nanoclusters can be produced using ultraviolet light, visible or infrared light. The photoreduction process has several advantages such as avoiding the introduction of impurities, fast synthesis, and controlled reduction. For example Diaz and his co-workers have used visible light to reduce silver ions into nanoclusters in the presence of a PMAA polymer. Kunwar et al produced silver nanoclusters using infrared light.
*Other reduction methods. Silver nanoclusters are also formed by reducing silver ions with gamma rays, microwaves, or ultrasound. For example silver nanoclusters formed by gamma reduction technique in aqueous solutions that contain sodium polyacrylate or partly carboxylated polyacrylamide or glutaric acids. By irradiating microwaves Linja Li prepared fluorescent silver nanoclusters in PMAA, which typically possess a red color emission. Similarly Suslick et al. have synthesized silver nanoclusters using high ultrasound in the presence of PMAA polymer. | 0 | Colloidal Chemistry |
Skin disorders such as acne and psoriasis may be relieved by regularly soaking the affected area in water with added Dead Sea salt. The National Psoriasis Foundation recommends Dead Sea and Dead Sea salts as effective treatments for psoriasis. High concentration of magnesium in Dead Sea salt may be helpful in improving skin hydration and reducing inflammation, although Epsom salt is a much less expensive salt that also contains high amounts of magnesium and therefore may be equally as useful for this purpose. | 1 | Solid-state chemistry |
Many possible applications of this and related high temperature superconducting materials have been discussed. For example, superconducting materials are finding use as magnets in magnetic resonance imaging, magnetic levitation, and Josephson junctions. (The most used material for power cables and magnets is BSCCO.)
YBCO has yet to be used in many applications involving superconductors for two primary reasons:
*First, although single crystals of YBCO have a very high critical current density, polycrystals have a very low critical current density: only a small current can be passed while maintaining superconductivity. This problem is due to crystal grain boundaries in the material. When the grain boundary angle is greater than about 5°, the supercurrent cannot cross the boundary. The grain boundary problem can be controlled to some extent by preparing thin films via CVD or by texturing the material to align the grain boundaries.
*A second problem limiting the use of this material in technological applications is associated with processing of the material. Oxide materials such as this are brittle, and forming them into superconducting wires by any conventional process does not produce a useful superconductor. (Unlike BSCCO, the powder-in-tube process does not give good results with YBCO.)
The most promising method developed to utilize this material involves deposition of YBCO on flexible metal tapes coated with buffering metal oxides. This is known as . Texture (crystal plane alignment) can be introduced into the metal tape (the RABiTS process) or a textured ceramic buffer layer can be deposited, with the aid of an ion beam, on an untextured alloy substrate (the IBAD process). Subsequent oxide layers prevent diffusion of the metal from the tape into the superconductor while transferring the template for texturing the superconducting layer. Novel variants on CVD, PVD, and solution deposition techniques are used to produce long lengths of the final YBCO layer at high rates. Companies pursuing these processes include American Superconductor, Superpower (a division of Furukawa Electric), Sumitomo, Fujikura, Nexans Superconductors, Commonwealth Fusion Systems, and European Advanced Superconductors. A much larger number of research institutes have also produced YBCO tape by these methods.
The superconducting tape may be the key to a tokamak fusion reactor design that can achieve breakeven energy production. YBCO is often categorized as a rare-earth barium copper oxide (REBCO). | 1 | Solid-state chemistry |
FeO has a cubic inverse spinel group structure which consists of a cubic close packed array of oxide ions where all of the Fe ions occupy half of the octahedral sites and the Fe are split evenly across the remaining octahedral sites and the tetrahedral sites.
Both FeO and γ-FeO have a similar cubic close packed array of oxide ions and this accounts for the ready interchangeability between the three compounds on oxidation and reduction as these reactions entail a relatively small change to the overall structure. FeO samples can be non-stoichiometric.
The ferrimagnetism of FeO arises because the electron spins of the Fe and Fe ions in the octahedral sites are coupled and the spins of the Fe ions in the tetrahedral sites are coupled but anti-parallel to the former. The net effect is that the magnetic contributions of both sets are not balanced and there is a permanent magnetism.
In the molten state, experimentally constrained models show that the iron ions are coordinated to 5 oxygen ions on average. There is a distribution of coordination sites in the liquid state, with the majority of both Fe and Fe being 5-coordinated to oxygen and minority populations of both 4- and 6-fold coordinated iron. | 1 | Solid-state chemistry |
Nanoparticles are naturally produced by many cosmological, geological, meteorological, and biological processes. A significant fraction (by number, if not by mass) of interplanetary dust, that is still falling on the Earth at the rate of thousands of tons per year, is in the nanoparticle range; and the same is true of atmospheric dust particles. Many viruses have diameters in the nanoparticle range. | 0 | Colloidal Chemistry |
In mathematical terms, the APESs characterising the JT distortion arise as the eigenvalues of the potential energy matrix. Generally, the APESs take the characteristic appearance of a double cone, circular or elliptic, where the point of contact, i.e. degeneracy, denotes the high-symmetry configuration for which the JT theorem applies. For the above case of the linear E ⊗ e JT effect the situation is illustrated by the APES
displayed in the figure, with part cut away to reveal its shape, which is known as a Mexican Hat potential. Here, is the frequency of the vibrational e mode, is its mass and is a measure of the strength of the JT coupling.
The conical shape near the degeneracy at the origin makes it immediately clear that this point cannot be stationary, that is, the system is unstable against asymmetric distortions, which leads to a symmetry lowering. In this particular case there are infinitely many isoenergetic JT distortions. The giving these distortions are arranged in a circle, as shown by the red curve in the figure. Quadratic coupling or cubic elastic terms lead to a warping along this "minimum energy path", replacing this infinite manifold by three equivalent potential minima and three equivalent saddle points. In other JT systems, linear coupling results in discrete minima. | 1 | Solid-state chemistry |
Emulsions are thermodynamically unstable liquid/liquid dispersions that are stabilized.
Emulsion dispersion is not about reactor blends for which one polymer is polymerized from its monomer in the presence of the other polymers; emulsion dispersion is a novel method of choice for the preparation of homogeneous blends of thermoplastic and elastomer. In emulsion dispersion system the preparation of well-fined polymers droplets may be acquired by the use of water as dispersing medium. The surfactant molecules adsorb on the surface of emulsion by creating a dispersion of droplets, which reduces interfacial tension and retards particle flocculation during mixing. The molecules of surfactant have polar and non-polar parts which act as an intermediary to combine polar and non-polar polymers; the intermolecular interactions between the polar and the non-polar polymer segments resemble the macroscopic hydrocarbon-water interface. The idea of the emulsion dispersion inspired by emulsification of liquid natural rubber (LNR), from particle size analysis and optical microscopy results showed that the droplet size of emulsion of LNR with higher molecular weight is greater than that of the lower molecular weight. Emulsion dispersion was able to produce homogeneous low-density polyethylene (LDPE)/LNR blends and nylon 6/LNR blends. Results of differential scanning calorimetry (DSC) thermogram indicated a single glass transition temperature (Tg) showed that the blends were compatible and scanning electron microscopy (SEM) micrograph showed no phase separation between blend components. In addition, exfoliated HDPE/LNR/montmorillonite nanocomposites were successfully achieved by using emulsion dispersion technique as well. | 0 | Colloidal Chemistry |
The alkali metal thioxanthates are produced by treating a thiol with a base in the presence of carbon disulfide, as illustrated by the preparation of sodium ethyl thioxanthate:.
:EtSH + NaOH + CS → EtSCSNa + HO
Sodium ethyl thioxanthate is similar structurally to sodium ethyl xanthate.
Alkylation of such thioxanthate anions gives thioxanthate esters, as illustrated by the preparation of ethyl methyl thioxanthate:
:EtSCSNa + MeI → EtSCSMe + NaI
Thioxanthate esters are also called esters of trithiocarbonate. | 1 | Solid-state chemistry |