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Particle aggregation is a widespread phenomenon, which spontaneously occurs in nature but is also widely explored in manufacturing. Some examples include.
Formation of river delta. When river water carrying suspended sediment particles reaches salty water, particle aggregation may be one of the factors responsible for river delta formation. Charged particles are stable in river's fresh water containing low levels of salt, but they become unstable in sea water containing high levels of salt. In the latter medium, the particles aggregate, the larger aggregates sediment, and thus create the river delta.
Papermaking. Retention aids are added to the pulp to accelerate paper formation. These aids are coagulating aids, which accelerate the aggregation between the cellulose fibers and filler particles. Frequently, cationic polyelectrolytes are being used for that purpose.
Water treatment. Treatment of municipal waste water normally includes a phase where fine solid particles are removed. This separation is achieved by addition of a flocculating or coagulating agent, which induce the aggregation of the suspended solids. The aggregates are normally separated by sedimentation, leading to sewage sludge. Commonly used flocculating agents in water treatment include multivalent metal ions (e.g., Fe or Al), polyelectrolytes, or both.
Cheese making. The key step in cheese production is the separation of the milk into solid curds and liquid whey. This separation is achieved by inducing the aggregation processes between casein micelles by acidifying the milk or adding rennet. The acidification neutralizes the carboxylate groups on the micelles and induces the aggregation. | 0 | Colloidal Chemistry |
Interfacial and surface tension can be characterized by classical methods such as the
-pendant or spinning drop method.
Dynamic surface tensions, i.e. surface tension as a function of time, can be obtained by the maximum bubble pressure apparatus
The structure of surfactant layers can be studied by ellipsometry or X-ray reflectivity.
Surface rheology can be characterized by the oscillating drop method or shear surface rheometers such as double-cone, double-ring or magnetic rod shear surface rheometer. | 0 | Colloidal Chemistry |
He worked in Chiba University as a faculty of science until 2010, later he studied surface chemistry of metal hydroxide oxides and on gas adsorption, nanoporous materials, and nanospaces molecular science. Later, he became the dean of faculty of science and graduate school of science and technology of Chiba University.
He is now a distinguished professor of Shinshu University since 2010. | 1 | Solid-state chemistry |
Metallic nanofoams are a subcategorization of nanofoams; more specifically, there are nanofoams consisting of metals, often pure, that form interconnected networks of ligaments that make up the structure of the foam. A variety of metals are used, including copper, nickel, gold, and platinum. Metallic nanofoams may offer certain advantages over alternative polymer nanofoams; structurally, they retain the electrical conductivity of metals, offer increased ductility, as well as the higher surface area and nano-architecture properties offered by nanofoams. | 0 | Colloidal Chemistry |
EPE foams are low density, semi-rigid, closed cell foam that are generally somewhere in stiffness/compliance between Expanded polystyrene and Polyurethane. Production of EPE foams is similar to that of expanded polystyrene, but starting with PE beads. Typical densities are with the lower figure being common. Densities as low as can be produced.
Base polymer for EPE foams range from Low-density polyethylene (LDPE) to High-density polyethylene (HDPE). | 0 | Colloidal Chemistry |
In the lab, synthetic nanocrystalline bone grafting material in mice has shown in-growth of vascularized fibrous tissue which resulted in improved healing. Furthermore, new blood vessels were observed at day 5 after implantation, and the implant showed a high functional vessel density. In a study examining the femoral epiphyses of rabbits in two to eight weeks of healing, bone-to-implant contact was compared to bone growth inside the chambers for four different implant surfaces. The researchers found that bone substitute materials may improve the bone apposition onto titanium. | 0 | Colloidal Chemistry |
Attfield was awarded the Meldola Medal and Prize by the Royal Society of Chemistry (RSC) in 1991; the Corday-Morgan Medal of the RSC in 1998; and the Peter Day Award in 2013. He was elected a Fellow of the Royal Society (FRS) in 2014 for “substantial contribution to the improvement of natural knowledge”. In 2016, Attield was awarded a Daiwa Adrian Prize, recognizing his work as part of a British-Japanese scientific collaboration. | 1 | Solid-state chemistry |
PtSi can be synthesized in several ways. The standard method involves depositing a thin film of pure platinum onto silicon wafers and heating in a conventional furnace at 450–600 °C for a half an hour in inert ambients. The process cannot be carried out in an oxygenated environment, as this results in the formation of an oxide layer on the silicon, preventing PtSi from forming.
A secondary technique for synthesis requires a sputtered platinum film deposited on a silicon substrate. Due to the ease with which PtSi can become contaminated by oxygen, several variations of the methods have been reported. Rapid thermal processing has been shown to increase the purity of PtSi layers formed. Lower temperatures (200–450 °C) were also found to be successful, higher temperatures produce thicker PtSi layers, though temperatures in excess of 950 °C formed PtSi with increased resistivity due to clusters of large PtSi grains. | 1 | Solid-state chemistry |
Europium phosphide is an inorganic compound of europium and phosphorus with the chemical formula EuP. Other phosphides are also known. | 1 | Solid-state chemistry |
A nanolattice is a synthetic porous material consisting of nanometer-size members patterned into an ordered lattice structure, like a space frame. The nanolattice is a newly emerged material class that has been rapidly developed over the last decade. Nanolattices redefine the limits of the material property space. Despite being composed of 50-99% of air, nanolattices are very mechanically robust because they take advantage of size-dependent properties that we generally see in nanoparticles, nanowires, and thin films. The most typical mechanical properties of nanolattices include ultrahigh strength, damage tolerance, and high stiffness. Thus, nanolattices have a wide range of applications.
Driven by the evolution of 3D printing techniques, nanolattices aiming to exploit beneficial material size effects through miniaturized lattice designs were first developed in the mid-2010s,. Nanolattices are the smallest man-made lattice truss structures and a class of metamaterials that derive their properties from both their geometry (general metamaterial definition) and the small size of their elements. Therefore, they can possess effective properties not found in nature, and that may not be achieved with larger-scale lattices of the same geometry. | 0 | Colloidal Chemistry |
The enthalpy of formation of lithium fluoride (LiF) from its elements in their standard states (Li(s) and F(g)) is modeled in five steps in the diagram:
# Atomization enthalpy of lithium
# Ionization enthalpy of lithium
# Atomization enthalpy of fluorine
# Electron affinity of fluorine
# Lattice enthalpy
The sum of the energies for each step of the process must equal the enthalpy of formation of lithium fluoride, .
* is the enthalpy of sublimation for metal atoms (lithium)
* is the bond enthalpy (of F). The coefficient 1/2 is used because the formation reaction is Li + 1/2 F → LiF.
* is the ionization energy of the metal atom:
* is the electron affinity of non-metal atom X (fluorine)
* is the lattice enthalpy (defined as exothermic here)
The net enthalpy of formation and the first four of the five energies can be determined experimentally, but the lattice enthalpy cannot be measured directly. Instead, the lattice enthalpy is calculated by subtracting the other four energies in the Born–Haber cycle from the net enthalpy of formation.
A similar calculation applies for any metal other than lithium and/or any non-metal other than fluorine.
The word cycle refers to the fact that one can also equate to zero the total enthalpy change for a cyclic process, starting and ending with LiF(s) in the example. This leads to
which is equivalent to the previous equation. | 1 | Solid-state chemistry |
The wood-ash industry declined in the late 19th century when large-scale production of potash from mineral salts was established in Germany. In 1943, potash was discovered in Saskatchewan, Canada, during oil drilling. Active exploration began in 1951. In 1958, the Potash Company of America became the first potash producer in Canada with the commissioning of an underground potash mine at Patience Lake. Due to water seepage, production stopped late in 1959. Following extensive grouting and repairs, production resumed in 1965. The underground mine was flooded in 1987, and was reactivated for commercial production as a solution mine in 1989.
In 1964 Canadian company Kalium Chemicals established the first potash mine using the solution process. The discovery was made during oil reserve exploration. The mine was developed near Regina, Saskatchewan. The mine reached depths greater than 1500 meters. It is now the Mosaic Corporation's Belle Plaine unit.
In the beginning of the 20th century, potash deposits were found in the Dallol Depression in Musely and Crescent localities near the Ethiopean-Eritrean border. The estimated reserves are 173 and 12 million tonnes for the Musely and Crescent, respectively. The latter is particularly suitable for surface mining. It was explored in the 1960s but the works stopped due to flood in 1967. Attempts to continue mining in the 1990s were halted by the Eritrean–Ethiopian War and have not resumed as of 2009. | 1 | Solid-state chemistry |
Sodium ethyl xanthate (SEX) is an organosulfur compound with the chemical formula . It is a pale yellow powder, which is usually obtained as the dihydrate. Sodium ethyl xanthate is used in the mining industry as a flotation agent. A closely related potassium ethyl xanthate (KEX) is obtained as the anhydrous salt. | 1 | Solid-state chemistry |
Bittern can be used instead of aluminum-based coagulants in the treatment of wastewater produced during the fabric-dyeing process. The wastewater pH is basic, which is favorable for the use of bittern. After the addition of bittern, precipitated magnesium hydroxide works as the coagulant to collect dye, solids, organic matter, and heavy metals from the wastewater before settling out of solution. The sludge produced from this wastewater treatment is also easier to dispose of than sludge produced by aluminum-based coagulants because there are less restrictions surrounding the disposal of magnesium, and it may be possible to recycle the sludge as fertilizer.
Bittern can also be used as a source of magnesium ions (Mg) for the precipitation of struvite, a useful fertilizer, from wastewater containing nitrogen and phosphorus. One source of useful wastewater is landfill leachate. Bittern is just as good as other sources of magnesium ions at removing phosphorus from wastewater streams, but it lags behind other magnesium ion sources in terms of the removal of ammonia (a nitrogen compound). | 1 | Solid-state chemistry |
Foam, in this case meaning "bubbly liquid", is also produced as an often-unwanted by-product in the manufacture of various substances. For example, foam is a serious problem in the chemical industry, especially for biochemical processes. Many biological substances, for example proteins, easily create foam on agitation or aeration. Foam is a problem because it alters the liquid flow and blocks oxygen transfer from air (thereby preventing microbial respiration in aerobic fermentation processes). For this reason, anti-foaming agents, like silicone oils, are added to prevent these problems. Chemical methods of foam control are not always desired with respect to the problems (i.e., contamination, reduction of mass transfer) they may cause especially in food and pharmaceutical industries, where the product quality is of great importance. Mechanical methods to prevent foam formation are more common than chemical ones. | 0 | Colloidal Chemistry |
Solid foams, both open-cell and closed-cell, are considered as a sub-class of cellular structures. They often have lower nodal connectivity as compared to other cellular structures like honeycombs and truss lattices, and thus, their failure mechanism is dominated by bending of members. Low nodal connectivity and the resulting failure mechanism ultimately lead to their lower mechanical strength and stiffness compared to honeycombs and truss lattices.
The strength of foams can be impacted by the density, the material used, and the arrangement of the cellular structure (open vs closed and pore isotropy). To characterize the mechanical properties of foams, compressive stress-strain curves are used to measure their strength and ability to absorb energy since this is an important factor in foam based technologies. | 0 | Colloidal Chemistry |
Nanoparticle deposition refers to the process of attaching nanoparticles to solid surfaces called substrates to create coatings of nanoparticles. The coatings can have a monolayer or a multilayer and organized or unorganized structure based on the coating method used. Nanoparticles are typically difficult to deposit due to their physical properties. | 0 | Colloidal Chemistry |
Lead tetroxide ("red lead"), a valence-mixed oxide with formula (red), may be thought of as lead(II) orthoplumbate(IV), . Lead sesquioxide, , is also known (reddish yellow), and has the structure of lead(II) metaplumbate(IV), . | 1 | Solid-state chemistry |
At high temperatures (1000 °C), titanium sulfides present a series of non-stoichiometric compounds.
The coordination polymer Prussian blue, nominally and their analogs are well known to form in non-stoichiometric proportions. The non-stoichiometric phases exhibit useful properties vis-à-vis their ability to bind caesium and thallium ions. | 1 | Solid-state chemistry |
Further advances in aquasome research require additional investigation of their in vivo drug release and targeting. Applications such as delivery of dithranol for the treatment of psoriasis and oral delivery of bromelain for the treatment of inflammatory diseases such as cancer show promising results in vitro and ex vivo. However, such applications have been unexplored in vivo, limiting their clinical use. Applications using aquasomes as carriers of hemoglobin, vaccines, and insulin have been tested in vivo in small animal models such as rats, mice, and rabbits, but current literature lacks in vivo testing in more advanced animal models, preventing their use as treatments for human conditions. Aquasomes are promising drug delivery mechanisms due to their ability to stabilize and transport a variety of substrates while allowing for controlled drug release. Prior to expanding the clinical applications of aquasomes, the gap existing in current literature will need to be filled by further investigating immune clearance of aquasomes, exploring additional surface modifications such as PEGylation, and expanding in vivo drug testing. | 0 | Colloidal Chemistry |
Alkyl polyacrylates are suitable for use as defoamers in non-aqueous systems where air release is more important than the breakdown of surface foam. These defoamers are often delivered in a solvent carrier like petroleum distillates. | 0 | Colloidal Chemistry |
Selenosulfide groups can be found in almost all living organisms as part of various peroxidase enzymes, such as glutathione peroxidase and thioredoxin reductase. They are formed by the oxidative coupling of selenocysteine and cysteine residues. This reaction is powered by the decomposition of cellular peroxides, which can be highly damaging and a source of oxidative stress. Selenocysteine has a lower reduction potential than cysteine, making it very suitable for proteins that are involved in antioxidant activity.
Selenosulfides have been identified in some species of Allium and in roasted coffee. The mammalian version of the protein thioredoxin reductase contains a selenocysteine residue which forms a thioselenide (analogous to a disulfide) upon oxidation. | 1 | Solid-state chemistry |
Foam, entrained and dissolved air that are present in coolants and processing liquids, may cause various kinds of problems, including:
* Reduction of pump efficiency (cavitation)
* Reduced capacity of pumps and storage tanks
* Bacterial growth
* Dirt flotation / deposit formation
* Reduced effectiveness of the fluid solution(s)
* Eventual downtime to clean tanks
* Drainage problems in sieves and filters
* Formation problems (i.e. in a paper mill it may cause the fibers to form an inhomogeneous sheet)
* Cost of replenishing the liquid
* Cost of entire material rejection due to imperfections | 0 | Colloidal Chemistry |
The isotropy of the cellular structure and the absorption of fluids can also have an impact on the mechanical properties of a foam. If there is anisotropy present, then the materials response to stress will be directionally dependent, and thus the stress-strain curve, modulus, and energy absorption will vary depending on the direction of applied force. Also, open-cell structures which have connected pores can allow water or other liquids to flow through the structure, which can also affect the rigidity and energy absorption capabilities. | 0 | Colloidal Chemistry |
Nanofluids are primarily used for their enhanced thermal properties as coolants in heat transfer equipment such as heat exchangers, electronic cooling system(such as flat plate) and radiators. Heat transfer over flat plate has been analyzed by many researchers. However, they are also useful for their controlled optical properties. Graphene based nanofluid has been found to enhance Polymerase chain reaction efficiency. Nanofluids in solar collectors is another application where nanofluids are employed for their tunable optical properties. Nanofluids have also been explored to enhance thermal desalination technologies, by altering thermal conductivity and absorbing sunlight, but surface fouling of the nanofluids poses a major risk to those approaches. Researchers proposed nanofluids for electronics cooling. Nanofluids also can be used in machining. | 0 | Colloidal Chemistry |
As of 1 April 1933, Klemm became a full professor and head of the Department of Inorganic Chemistry at the Technische Hochschule Danzig. Klemm replaced Hans Joachim von Wartenberg, who had taught at the Technische Hochschule Danzig from 1913 to 1932 and served in several senior positions including head of the Department of Inorganic Chemistry. Von Wartenberg left in August 1932 to become director of the Institute of Inorganic Chemistry at the University of Göttingen.
The Technische Hochschule Danzig was at that time located in the Free City of Danzig (1920-1939). The population of the city was predominantly German and faculty and staff tended to align with National Socialism even before 1933. The attitudes of scientists at the university have been described in terms of "shades of gray".
Klemm had some involvement with the National Socialists but his motives are not known.
Klemm was not a signatory of the Bekenntnis der Professoren an den deutschen Universitäten (1933).
He did sign the later Aufstellung zu den Unterzeichnern des Appells „An die Gebildeten der Welt“ (11. November 1933), a list of academics who professed support for Adolf Hitler and National Socialism. Klemm became a member of the NSDAP (Nazi Party) in 1938, rather later than contemporaries like Adolf Butenandt.
Following the Invasion of Poland which began 1 September 1939, the Free City of Danzig was annexed by Germany, and anti-Jewish measures escalated.
In a letter to the editorial staff of Chemische Berichte in June 1942 Klemm argued that contributions from chemist Georg-Maria Schwab and other "non-Aryan" authors should not appear in German chemical journals.
Klemm served as head of the Inorganic Chemistry department of the Technische Hochschule Danzig from 1933 to 1945, and was its last vice-rector. He was responsible for the evacuation of equipment, books, files, and people in 1944–1945, in advance of Soviet troops. Approximately 500 books and pieces of equipment and 300 staff and family members sailed on the ship Deutschland on 27 January 1945 bound for Kiel.
Much of the university including the chemistry building was destroyed in subsequent months. Following the war Gdańsk became part of Poland. On 24 March 1945, the university was re-established as a Polish institution. | 1 | Solid-state chemistry |
* Wilfried Umbach (Hrsg.), Kosmetik und Hygiene von Kopf bis Fuß, Wiley-VCH Verlag GmbH & Co. KGaA, 3. vollst. überarb. u. erw. Auflage (2012), . | 0 | Colloidal Chemistry |
An estimated 26,000 U.S. sites are contaminated with PFASs. At least six million Americans are estimated to have drinking water containing PFASs above the safe limit published prior to 2022 by the U.S. Environmental Protection Agency (EPA). More than 200 million Americans are estimated to live in places where the tap water PFAS level (a combination of PFOA and PFOS levels) exceeds the 1 ppt (part per trillion) limit set in 2022 by the EPA.
, the states of California, Connecticut, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Vermont, and Wisconsin had enforceable drinking water standards for between two and six types of PFAS. The six chemicals (termed by the Massachusetts Department of Environmental Protection as PFAS6) are measured either individually or summed as a group depending on the standard; they are:
* Perfluorooctanesulfonic acid (PFOS)
* Perfluorooctanoic acid (PFOA)
* Perfluorohexanesulfonic acid (PFHxS)
* Perfluorononanoic acid (PFNA)
* Perfluoroheptanoic acid (PFHpA)
* Perfluorodecanoic acid (PFDA)
EPA published non-enforceable drinking water health advisories for PFOA and PFOS in 2016. In March 2021 EPA announced that it would develop national drinking water standards for PFOA and PFOS. On December 27, 2021, EPA published a regulation requiring drinking water utilities to conduct monitoring for 29 compounds. The data are to be collected during 2023 to 2025. EPA will pay for the monitoring costs for small drinking water systems (those serving a population of 10,000 or fewer). The agency may use the monitoring data to develop additional regulations.
In mid-2021 EPA announced plans to revise federal wastewater regulations (effluent guidelines) for several industries that manufacture PFASs or use PFASs in fabricating various products.
In October 2021 EPA announced the PFAS Strategic Roadmap. It is a "whole-of-EPA" strategy and considers the full lifecycle of PFAS—including drinking water monitoring and risk assessment for PFOA and PFOS in biosolids (processed wastewater sludge used as fertilizer).
The EPA issued health advisories for four specific PFASs in June 2022, significantly lowering their safe threshold levels for drinking water. PFOA was reduced from 70 ppt to 0.004 ppt, while PFOS was reduced from 70 ppt to 0.02 ppt. GenX's safe levels were set at 10 ppt, while PFBS were set to 2000 ppt. While not enforceable, these health advisories are intended to be acted on by states in setting their own drinking water standards.
A formal EPA rule to add PFOA and PFAS as hazardous chemicals was first issued for comment in August 2022, which would require anyone discharging waste to monitor and restrict the release of these PFAS to set levels, and report when the wastewater exceeds it. It would also make grounds affected by high levels of PFIA or PFAS to be considered Superfund cleanup sites. The EPA formally established rules for these two chemicals.
EPA has listed recommended steps that consumers may take to reduce possible exposure to PFAS chemicals.
On 14 March 2023, EPA announced the proposed National Primary Drinking Water Regulation (NPDWR). This proposal includes new maximum contaminant levels (MCLs) in drinking water for six well-known PFAS: PFOA, PFOS, GenX, PFBS, PFNA, and PFHxS. While the proposal does not require any actions until its finalization, the EPA believes it will be implemented by late 2023. If these new restrictions are put into place, the EPA expects that they will prevent thousands of deaths and tens of thousands of PFAS-attributable illnesses. Along with legally enforceable MCLs, the EPA proposal will also require public water systems to actively monitor for the 6 PFAS, notify the public about the level of PFAS in the water supply, and take measures to reduce the level of PFAS in drinking water if they exceed the MCLs.
Between 2016 and 2021 the U.S. Geological Survey (USGS) tested tap water from 716 locations across the United States, and reported in 2023 that the PFAS levels exceeded the EPA advisories in approximately 75% of the samples from urban areas and in approximately 25% of the rural area samples.
In 2023, the American multinational 3M reached a US$10.3 billion settlement with a host of US public water systems to resolve water pollution claims tied to PFAS. Three other major chemicals companies – Chemours, DuPont and Corteva – have reached an agreement in principle for US$1.19 bn to settle claims they contaminated US public water systems with PFAS. | 0 | Colloidal Chemistry |
He was awarded the Literaturpreis des Fonds der chemischen Industrie for his textbook "Anorganische Strukturchemie" (engl. Inorganic Structural Chemistry). | 1 | Solid-state chemistry |
Following his PhD, Fichtner spent two years as a young researcher at the former Karlsruhe Nuclear Research Center (KfK) and developed his method further so that it could be applied to organic materials also. In 1994 he became assistant to the board of directors of the Karlsruhe Research Center (FZK), in the area Basic Research and New Technologies, with Herbert Gleiter as director. In 1997 he left to build up a new activity on microprocess engineering, with a focus on heterogeneous catalysis in microchannels, for fuel processing (methanol steam reforming, partial oxidation of methane) and synthesis of chemicals. The group was eventually integrated in the new Institute for Microprocess Engineering in 2001. In 2000 he was offered a position at the new Institute of Nanotechnology, INT (Founding directors: Herbert Gleiter, Jean-Marie-Lehn, Dieter Fenske) to build up a new activity on nanoscale materials for energy storage. Since then he is group leader there. In 2012 he received a call by the Ulm University to become a professor (W3) in Solid State Chemistry, which he accepted in 2013. The position is connected to a function as group leader at the new Helmholtz Institute Ulm. Since 2015 he has been executive director of the institute.
Fichtner has co-ordinated several EU projects and collaborative projects from the German ministries of Economy and Research and Education. He has been organizer of various symposia at MRS and GRC conferences, and he was Chair of the GORDON Research Conference on Metal-Hydrogen Systems in 2013 and of the 1st International Symposium on Magnesium Batteries (MagBatt) in 2016. | 1 | Solid-state chemistry |
Titanium foams exhibiting auxetic pore structures are of interest for incorporation in sandwich panel cores due to their enhanced shear performance.
Foams with this pore structure exhibit negative Poissons ratio in one or more dimensions. Poissons ratio is defined as the ratio of the lateral contractile strain to the longitudinal tensile strain for the foam undergoing uniaxial tension in the loading direction. Auxetic materials are typically able to resist indentations through their response to compression; upon compression, the auxetic material contracts. In addition to indentation resistance, research has shown that auxetic foams offer better absorption of sound and vibration, enhanced shear resistance and facture toughness. These structures also exhibit synclastic bending, which results lends itself to integration within curved sandwich panels. | 0 | Colloidal Chemistry |
Isethionates are esters of long-chain aliphatic carboxylic acids (C – C) with isethionic acid (2-hydroxyethanesulfonic acid) or salts thereof, such as ammonium isethionate or sodium isethionate. They are also referred to as acyl isethionates or acyloxyethanesulfonates.
Like the taurides, isethionates are a class of particularly mild anionic surfactants which, unlike ordinary soaps, retain their washing-active properties even in hard water. Isethionates are obtained on an industrial scale reacting mixtures of carboxylic acids with salts of isethionic acid under acidic catalysis e. g. with methanesulfonic acid. The mixtures of carboxylic acids are obtained from the hydrolysis of animal fats (tallow) or vegetable oils, preferably coconut oil, but also palm oil, soybean oil or castor oil.
Isethionates are solids which are often mixed with fatty acids (up to 30% by weight) to lower their freezing point. Despite its low water solubility (100ppm at 25 °C), the lower-priced sodium cocoylisethionate has found more widespread use than its well water-soluble ammonium salt (> 25 wt.% at 25 °C). To solubilize the sparsely soluble isethionates and taurides, the formation of mixtures with amphoteric surfactants (such as cocamidopropyl betaine) are proposed. From such mixtures, it is possible to prepare liquid, clear and transparent aqueous concentrates which are liquid at room temperature.
Isethionates are characterized by excellent skin compatibility, excellent foaming (even in hard water), good cleansing properties and a pleasant skin feel. They are non-toxic and readily biodegradable. However, in contrast to the taurides, they are not long-term stable outside a pH range of 5 to 8. Isethionates are used in solid soaps (so-called syndet bars) and in other personal care products such as lotions, washing and shower gels, shampoos, liquid soaps, shaving creams, and other cosmetic and dermatological preparations. | 0 | Colloidal Chemistry |
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.
Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum.
Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. | 0 | Colloidal Chemistry |
In 1987, shortly after it was discovered, physicist and science author Paul Grant published in the U.K. Journal New Scientist a straightforward guide for synthesizing YBCO superconductors using widely-available equipment. Thanks in part to this article and similar publications at the time, YBCO has become a popular high-temperature superconductor for use by hobbyists and in education, as the magnetic levitation effect can be easily demonstrated using liquid nitrogen as coolant.
In 2021, SuperOx, a Russian and Japanese company, developed a new manufacturing process for making YBCO wire for fusion reactors. This new wire was shown to conduct between 700 and 2000 Amps per square millimeter. The company was able to produce 186 miles of wire in 9 months, between 2019 and 2021, dramatically improving the production capacity. The company used a plasma-laser deposition process, on a electropolished substrate to make 12-mm width tape and then slit it into 3-mm tape. | 1 | Solid-state chemistry |
Most alkali metal halides crystallize with the face-centered cubic lattices. In this structure both the metals and halides feature octahedral coordination geometry, in which each ion has a coordination number of six. Caesium chloride, bromide, and iodide crystallize in a body-centered cubic lattice that accommodates coordination number of eight for the larger metal cation (and the anion also). | 1 | Solid-state chemistry |
Cold emission of electrons is relevant to semiconductors and superconductor physics. It is similar to thermionic emission, where electrons randomly jump from the surface of a metal to follow a voltage bias because they statistically end up with more energy than the barrier, through random collisions with other particles. When the electric field is very large, the barrier becomes thin enough for electrons to tunnel out of the atomic state, leading to a current that varies approximately exponentially with the electric field. These materials are important for flash memory, vacuum tubes, and some electron microscopes. | 1 | Solid-state chemistry |
The optical properties of materials are determined by their electronic structure and band gap. The energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO/LUMO) varies with the size and composition of a nanocluster. Thus, the optical properties of nanoclusters change. Furthermore, the gaps can be modified by coating the nanoclusters with different ligands or surfactants. It is also possible to design nanoclusters with tailored band gaps and thus tailor optical properties by simply tuning the size and coating layer of the nanocluster. | 0 | Colloidal Chemistry |
Although the phenomenon we now call dielectrophoresis was described in passing as far back as the early 20th century, it was only subject to serious study, named and first understood by Herbert Pohl in the 1950s. Recently, dielectrophoresis has been revived due to its potential in the manipulation of microparticles, nanoparticles and cells.
Dielectrophoresis occurs when a polarizable particle is suspended in a non-uniform electric field. The electric field polarizes the particle, and the poles then experience a force along the field lines, which can be either attractive or repulsive according to the orientation on the dipole. Since the field is non-uniform, the pole experiencing the greatest electric field will dominate over the other, and the particle will move. The orientation of the dipole is dependent on the relative polarizability of the particle and medium, in accordance with Maxwell–Wagner–Sillars polarization. Since the direction of the force is dependent on field gradient rather than field direction, DEP will occur in AC as well as DC electric fields; polarization (and hence the direction of the force) will depend on the relative polarizabilities of particle and medium. If the particle moves in the direction of increasing electric field, the behavior is referred to as positive DEP (sometime pDEP), if acting to move the particle away from high field regions, it is known as negative DEP (or nDEP). As the relative polarizabilities of the particle and medium are frequency-dependent, varying the energizing signal and measuring the way in which the force changes can be used to determine the electrical properties of particles; this also allows the elimination of electrophoretic motion of particles due to inherent particle charge.
Phenomena associated with dielectrophoresis are electrorotation and traveling wave dielectrophoresis (TWDEP). These require complex signal generation equipment in order to create the required rotating or traveling electric fields, and as a result of this complexity have found less favor among researchers than conventional dielectrophoresis. | 0 | Colloidal Chemistry |
Properties depend greatly on composition and fabrication process. Many properties are anisotropic due to the layered structure. Dirty samples, e.g., with oxides at the crystal boundaries, are different from clean samples.
*The highest superconducting transition temperature T is 39 K.
*MgB is a type-II superconductor, i.e. increasing magnetic field gradually penetrates into it.
*Maximum critical current (J) is: 10 A/m at 20 T, 10 A/m at 18 T, 10 A/m at 15 T, 10 A/m at 10 T, 10 A/m at 5 T.
*As of 2008 : Upper critical field (H): (parallel to ab planes) is ~14 T, (perpendicular to ab planes) ~3 T, in thin films up to 74 T, in fibers up to 55 T. | 1 | Solid-state chemistry |
The reaction of alkali metal chalcogenides (S, Se, Te) and pnictides (N, P, As) with other metal halides produce the corresponding metal chalcogenides and pnictides. The synthesis of gallium nitride from gallium triiodide and lithium nitride is illustrative:
:GaI + LiN → GaN + 3 LiI
The process is so exothermic (ΔH = -515 kJ/mol) that the LiI evaporates, leaving a residue of GaN. With GaCl in place of GaI, the reaction is so exothermic that the product GaN decomposes. Thus, the selection of the metal halide affects the success of the method.
Other compounds prepared by this method include metal dichalcogenides such as MoS. The reaction is conducted in a stainless steel reactor with excess NaS.
Self-propagating high-temperature synthesis can also be conducted in an artificial high gravity environment to control the phase composition of products.
SHS has been used to vitrify various nuclear waste streams including ashes from incineration, spent inorganic ion exchangers such as clinoptilolite and contaminated soils. | 1 | Solid-state chemistry |
Approximately 2–3% of the world's energy budget is allocated to the Haber process for ammonia () production, which relies on wüstite-derived catalysts. The industrial catalyst is derived from finely ground iron powder, which is usually obtained by reduction of high-purity magnetite (FeO). The pulverized iron metal is burnt (oxidized) to give magnetite or wüstite of a defined particle size. The magnetite (or wüstite) particles are then partially reduced, removing some of the oxygen in the process. The resulting catalyst particles consist of a core of magnetite, encased in a shell of wüstite, which in turn is surrounded by an outer shell of iron metal. The catalyst maintains most of its bulk volume during the reduction, resulting in a highly porous high-surface-area material, which enhances its effectiveness as a catalyst. | 1 | Solid-state chemistry |
As more dust enters the atmosphere due to the consequences of human activity (from direct effects, such as clearing of land and desertification, versus indirect effects, such as global warming), it becomes more important to understand the effects of mineral dust on the gaseous composition of the atmosphere, cloud formation conditions, and global-mean radiative forcing (i.e., heating or cooling effects). | 0 | Colloidal Chemistry |
Charles Thompson Prewitt (March 3, 1933 – April 28, 2022) was an American mineralogist and solid state chemist known for his work on structural chemistry of minerals and high-pressure chemistry. | 1 | Solid-state chemistry |
Lee attended the International School of Geneva, Switzerland and Yale University, from which he graduated with a BA in 1978. He later received his PhD from the University of Chicago in 1985. | 1 | Solid-state chemistry |
At thermodynamic equilibrium, the likelihood of a state of energy being filled with an electron is given by the Fermi–Dirac distribution, a thermodynamic distribution that takes into account the Pauli exclusion principle:
where:
* is the product of Boltzmann's constant and temperature, and
* is the total chemical potential of electrons, or Fermi level (in semiconductor physics, this quantity is more often denoted ). The Fermi level of a solid is directly related to the voltage on that solid, as measured with a voltmeter. Conventionally, in band structure plots the Fermi level is taken to be the zero of energy (an arbitrary choice).
The density of electrons in the material is simply the integral of the Fermi–Dirac distribution times the density of states:
Although there are an infinite number of bands and thus an infinite number of states, there are only a finite number of electrons to place in these bands.
The preferred value for the number of electrons is a consequence of electrostatics: even though the surface of a material can be charged, the internal bulk of a material prefers to be charge neutral.
The condition of charge neutrality means that must match the density of protons in the material. For this to occur, the material electrostatically adjusts itself, shifting its band structure up or down in energy (thereby shifting ), until it is at the correct equilibrium with respect to the Fermi level. | 1 | Solid-state chemistry |
Scott Blair was born 23 July 1902, in Weybridge and went to Winchester College. He studied chemistry at Trinity College, Oxford receiving a BA in 1923.
He began work as a colloid chemist, studying flour suspensions which led to a series of papers on baker's dough. In 1926 he joined the Rothamsted Experimental Station, where the focus was on soil science. In 1928 he married Rita, a child psychologist, who survived him.
In December 1929 Scott Blair attended (and chaired) the founding meeting of the Society of Rheology in Washington, D.C. Chemist Eugene C. Bingham led the new society concerned with the problems of flow. Scott Blair held a Rockefeller Fellowship at the time. In 1931 Markus Reiner visited Scott Blair in England beginning a long friendship.
In 1936 he submitted his PhD thesis to the University of London.
In 1940, along with Vernon Harrison, he founded the British Rheologists' Club, later to become the British Society of Rheology.
In 1937 he became Head of the Chemistry Department (and later headed the Physics Department as well) at the National Institute for Research in Dairying, at Shinfield near Reading until his retirement in 1967. He died on 30 September 1987, at Iffley, Oxfordshire. | 0 | Colloidal Chemistry |
One of the largest applications of detergents is for household and shop cleaning including dish washing and washing laundry. These detergents are commonly available as powders or concentrated solutions, and the formulations of these detergents are often complex mixtures of a variety of chemicals aside from surfactants, reflecting the diverse demands of the application and the highly competitive consumer market. These detergents may contain the following components:
* surfactants
* foam regulators
* builders
* bleach
* bleach activators
* enzymes
* dyes
* fragrances
* other additives | 0 | Colloidal Chemistry |
Viologens, in their dicationic form, typically undergo two one-electron reductions. The first reduction affords the deeply colored radical cation:
: [V] + e [V]
The radical cations are blue for 4,4-viologens and green for 2,2-derivatives. The second reduction yields a yellow quinoid compounds:
: [V] + e [V]
The electron transfer is fast because the redox process induces little structural change. The redox is highly reversible. These reagents are relatively inexpensive among redox-active organic compounds. They are convenient colorimetric reagents for biochemical redox reactions. | 1 | Solid-state chemistry |
Nanocrystals are aggregates of anywhere from a few hundred to tens of thousands of atoms that combine into a crystalline form of matter known as a "cluster." Typically a few nanometers in diameter, nanocrystals are larger than molecules but smaller than bulk solids and therefore often exhibit physical and chemical properties somewhere in between. Given that a nanocrystal is virtually all surface and no interior, its properties can vary considerably as the crystal grows in size.
Prior to Alivisatos' research, all non-metal nanocrystals were dot-shaped, meaning they were essentially one-dimensional. No techniques had been reported for making two-dimensional or rod-shaped semiconductor nanocrystals that would also be of uniform size. However, in a landmark paper that appeared in the March 2, 2000 issue of the journal Nature, Alivisatos reported on techniques used to select the size but vary the shapes of the nanocrystals produced. This was hailed as a major breakthrough in nanocrystal fabrication because rod-shaped semiconductor nanocrystals can be stacked to create nano-sized electronic devices.
The rod-shaped nanocrystal research, coupled with earlier work led by Alivisatos in which it was shown that quantum dots or "qdots"–nanometer-sized crystal dots (spheres a few billionths of a meter in size)– made from semiconductors such as cadmium selenide can emit multiple colors of light depending upon the size of the crystal, opened the door to using nanocrystals as fluorescent probes for the study of biological materials, biomedical research tools and aids to diagnosis, and as light-emitting diodes (LEDs). Alivisatos went on to use his techniques to create an entirely new generation of hybrid solar cells that combined nanotechnology with plastic electronics. | 1 | Solid-state chemistry |
The wave function is expressed as the exponential of a function:
where
is then separated into real and imaginary parts:
where A(x) and B(x') are real-valued functions.
Substituting the second equation into the first and using the fact that the real part needs to be 0 results in:
To solve this equation using the semiclassical approximation, each function must be expanded as a power series in . From the equations, the power series must start with at least an order of to satisfy the real part of the equation; for a good classical limit starting with the highest power of Planck's constant possible is preferable, which leads to
and
with the following constraints on the lowest order terms,
and
At this point two extreme cases can be considered.
Case 1
If the amplitude varies slowly as compared to the phase and
which corresponds to classical motion. Resolving the next order of expansion yields
Case 2
If the phase varies slowly as compared to the amplitude, and
which corresponds to tunneling. Resolving the next order of the expansion yields
In both cases it is apparent from the denominator that both these approximate solutions are bad near the classical turning points . Away from the potential hill, the particle acts similar to a free and oscillating wave; beneath the potential hill, the particle undergoes exponential changes in amplitude. By considering the behaviour at these limits and classical turning points a global solution can be made.
To start, a classical turning point, is chosen and is expanded in a power series about :
Keeping only the first order term ensures linearity:
Using this approximation, the equation near becomes a differential equation:
This can be solved using Airy functions as solutions.
Taking these solutions for all classical turning points, a global solution can be formed that links the limiting solutions. Given the two coefficients on one side of a classical turning point, the two coefficients on the other side of a classical turning point can be determined by using this local solution to connect them.
Hence, the Airy function solutions will asymptote into sine, cosine and exponential functions in the proper limits. The relationships between and are
and
With the coefficients found, the global solution can be found. Therefore, the transmission coefficient for a particle tunneling through a single potential barrier is
where are the two classical turning points for the potential barrier.
For a rectangular barrier, this expression simplifies to: | 1 | Solid-state chemistry |
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the hal- syllable in halide and halite reflects this correlation. All Group 1 metals form halides that are white solids at room temperature.
A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (), chloride (), bromide (), iodide () and astatide (). Such ions are present in all ionic halide salts. Halide minerals contain halides.
All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. | 1 | Solid-state chemistry |
Memory foam derives its viscoelastic properties from several effects, due to the materials internal structure. The network effect is the force working to restore the foams structure when it is deformed. This effect is generated by the deformed porous material pushing outwards to restore its structure against an applied pressure. Three effects work against the network effect, slowing the regeneration of the foam's original structure:
* The pneumatic effect, caused by the time it takes air to flow into the foam's porous structure.
* The adhesive effect, or adhesion, caused by the stickiness of the surfaces within the foam, which work against decompression as the internal pores within the foam are pressed together
* The relaxation effect (the strongest of the three forces working against expansion), caused by the foam's material being near its glass transition temperature—limiting its mobility, forcing any change to be gradual, and slowing the expansion of the foam once the applied pressure has been removed
The effects are temperature-dependent, so the temperature range at which memory foam retains its properties is limited. If it is too cold, it hardens. If it is too hot, it acts like conventional foams, quickly springing back to its original shape. The underlying physics of this process can be described by polymeric creep.
The pneumatic and adhesive effects are strongly correlated with the size of the pores within memory foam. Smaller pores lead to higher internal surface area and reduced air flow, increasing the adhesion and pneumatic effects. Thus the foams properties can be controlled by changing its cell structure and porosity. Its glass transition temperature can also be modulated by using additives in the foams material.
Memory foam's mechanical properties can affect the comfort of mattresses produced with it. There is also a trade-off between comfort and durability. Certain memory foams may have a more rigid cell structure, leading to a weaker distribution of weight, but better recovery of the original structure, leading to improved cyclability and durability. Denser cell structure can also resist the penetration of water vapor, leading to reduced weathering and better durability and overall appearance. | 0 | Colloidal Chemistry |
Keszler received his BS at Southwestern Oklahoma State University in 1979. He worked on his PhD in Northwestern University under the supervision of Prof. James A. Ibers and received his degree in 1984. He continued his career as a postdoctoral fellow at Cornell University under the supervision of Prof. Roald Hoffmann in 1984–1985.
Keszler joined the faculty of Oregon State University in 1985 as an assistant professor. He became an associate professor in 1990, professor in 1995 and distinguished professor in 2006. | 1 | Solid-state chemistry |
There is tentative evidence that saline nasal irrigation may help with long term cases of rhinosinusitis. Evidence for use in cases of rhinosinusitis of short duration is unclear. | 1 | Solid-state chemistry |
When the depositing particles attract each other, they will deposit and aggregate at the same time. This situation will result in a porous layer made of particle aggregates at the surface, and is referred to as ripening. The porosity of this layer will depend whether the particle aggregation process is fast or slow. Slow aggregation will lead to a more compact layer, while fast aggregation to a more porous one. The structure of the layer will resemble the structure of the aggregates formed in the later stages of the aggregation process. | 0 | Colloidal Chemistry |
Nanoparticles can be made from different materials such as metals, ceramics and polymers. The stability of the nanoparticles can be an issue as nanoparticles have a tendency to lower their very high surface energy, which originates from their high surface-to-bulk ratio. Bare nanoparticles tend to stabilize themselves either by sorption of molecules from the surroundings or by lowering the surface area through coagulation and agglomeration. Usually the formation of these aggregates is unwanted. The tendency of a nanoparticle to coagulate can be controlled by modifying the surface layer. In a liquid medium, suitable ligand molecules are commonly attached to the nanoparticle surface, as they provide solubility in suitable solvents and prevent coagulation. | 0 | Colloidal Chemistry |
Synthesis of phosphorene is a significant challenge. Currently, there are two main ways of phosphorene production: scotch-tape-based microcleavage and liquid exfoliation, while several other methods are being developed as well. Phosphorene production from plasma etching has also been reported.
In scotch-tape-based microcleavage, phosphorene is mechanically exfoliated from a bulk of black phosphorus crystal using scotch-tape. Phosphorene is then transferred on a Si/SiO substrate, where it is then cleaned with acetone, isopropyl alcohol and methanol to remove any scotch tape residue. The sample is then heated to 180 °C to remove solvent residue.
In the liquid exfoliation method, first reported by Brent et al. in 2014 and modified by others, bulk black phosphorus is first ground in a mortar and pestle and then sonicated in deoxygenated, anhydrous organic liquids such as NMP under an inert atmosphere using low-power bath sonication. Suspensions are then centrifuged for 30 minutes to filter out the unexfoliated black phosphorus. Resulting 2D monolayer and few-layer phosphorene unoxidized and crystalline structure, while exposure to air oxidizes the phosphorene and produces acid.
Another variation of liquid exfoliation is "basic N-methyl-2-pyrrolidone (NMP) liquid exfoliation". Bulk black phosphorene is added to a saturated NaOH/NMP solution, which is further sonicated for 4 hours to conduct liquid exfoliation. The solution is then centrifuged twice, first for 10 minutes to remove any unexfoliated black phosphorus and then for 20 minutes at a higher speed to separate thick layers of phosphorene (5–12 layers) from NMP. The supernatant then is centrifuged again at higher speed for another 20 minutes to separate thinner layers of phosphorene (1–7 layers). The precipitate from centrifugation is then redispersed in water and washed several times by deionized water. Phosphorene/water solution is dropped onto silicon with a 280-nm SiO surface, where it is further dried under vacuum. NMP liquid exfoliation method was shown to yield phosphorene with controllable size and layer number, excellent water stability and in high yield.
The disadvantage of the current methods includes long sonication time, high boiling point solvents, and low efficiency. Therefore, other physical methods for liquid exfoliation are still under development. A laser-assisted method developed by Zheng and co-workers showed a promising yield of up to 90% within 5 minutes. The laser photon interacts with the surface of bulk black phosphorus crystal, causing a plasma and solvent bubbles to weaken the interlayer interaction. Depending on the laser energy, solvent (ethanol, methanol, hexane, etc.) and irradiation time, the layer number and lateral size of the phosphorene were controlled.
The high yield production of phosphorene has been demonstrated by many groups in solvents, but to realize the potential applications of this material, it is crucial to deposit these free-standing nanosheets in solvents systematically on substrates. H. Kaur et al. demonstrated the synthesis, interface-driven alignment and subsequent functional properties of few layer semiconducting phosphorene using Langmuir-Blodgett assembly. This is the first study which provides a straightforward and versatile solution towards the challenge of assembling nanosheets of phosphorene onto various supports and subsequently use these sheets in an electronic device. Therefore, wet assemblies techniques like Langmuir-Blodgett serves as a very valuable new entry point for the exploration of electronic as well as opto-electronic properties of phosphorene as well as other 2D layered inorganic materials.
It is still a challenge to directly epitaxially grow 2D phosphorene because the stability of black phosphorene is highly sensitive to substrate, which is understanding by theoretical simulations. | 1 | Solid-state chemistry |
Dielectrics are used in radio frequency (RF) transmission lines. In a coaxial cable, polyethylene can be used between the center conductor and outside shield. It can also be placed inside waveguides to form filters. Optical fibers are examples of dielectric waveguides. They consist of dielectric materials that are purposely doped with impurities so as to control the precise value of ε within the cross-section. This controls the refractive index of the material and therefore also the optical modes of transmission. However, in these cases it is technically the relative permittivity that matters, as they are not operated in the electrostatic limit. | 0 | Colloidal Chemistry |
There are many synthetic strategies that are available to prepare cocrystals. However, it may be difficult to prepare single cocrystals for X-ray diffraction, as it has been known to take up to 6 months to prepare these materials.
Cocrystals are typically generated through slow evaporation of solutions of the two components. This approach has been successful with molecules of complementary hydrogen bonding properties, in which case cocrystallization is likely to be thermodynamically favored.
Many other methods exist in order to produce cocrystals. Crystallizing with a molar excess of one cocrystal former may produce a cocrystal by a decrease in solubility of that one component. Another method to synthesize cocrystals is to conduct the crystallization in a slurry. As with any crystallization, solvent considerations are important. Changing the solvent will change the intermolecular interactions and possibly lead to cocrystal formation. Also, by changing the solvent, phase considerations may be utilized. The role of a solvent in nucleation of cocrystals remains poorly understood but critical in order to obtain a cocrystal from solution.
Cooling molten mixture of cocrystal formers often affords cocrystals. Seeding can be useful. Another approach that exploits phase change is sublimation which often forms hydrates.
Grinding, both heat and liquid-assisted, is employed to produce cocrystal, e.g., using a mortar and pestle, using a ball mill, or using a vibratory mill. In liquid-assisted grinding, or kneading, a small or substoichiometric amount of liquid (solvent) is added to the grinding mixture. This method was developed in order to increase the rate of cocrystal formation, but has advantages over neat grinding such as increased yield, ability to control polymorph production, better product crystallinity, and applies to a significantly larger scope of cocrystal formers. and nucleation through seeding.
Supercritical fluids (SCFs) serve as a medium for growing cocrystals. Crystal growth is achieved due to unique properties of SCFs by using different supercritical fluid properties: supercritical solvent power, anti-solvent effect and its atomization enhancement.
Using intermediate phases to synthesize solid-state compounds is also employed. The use of a hydrate or an amorphous phase as an intermediate during synthesis in a solid-state route has proven successful in forming a cocrystal. Also, the use of a metastable polymorphic form of one cocrystal former can be employed. In this method, the metastable form acts as an unstable intermediate on the nucleation pathway to a cocrystal. As always, a clear connection between pairwise components of the cocrystal is needed in addition to the thermodynamic requirements in order to form these compounds.
Importantly, the phase that is obtained is independent of the synthetic methodology used. It may seem facile to synthesize these materials, but on the contrary the synthesis is far from routine. | 1 | Solid-state chemistry |
Müller studied chemistry at the University of Stuttgart from 1959 to 1963. He worked on his dissertation at the Purdue University and the University of Stuttgart. He finished it in 1966 in the group of Kurt Dehnicke. From 1967 to 1970, he worked in the group of Hartmut Bärnighausen at the University of Marburg. In 1972, he finished his habilitation. From 1972 to 1975, Müller was a professor for inorganic chemistry at the University of Marburg. From 1975 to 1977, he was a guest professor at the University of Costa Rica. Then, several professorships for inorganic chemistry followed: University of Marburg from 1977 to 1992, University of Kassel from 1992 to 1999, and University of Marburg from 2000 to 2005. Since 2005, he has been an emeritus professor. | 1 | Solid-state chemistry |
PJTE versus Renner–Teller effect in bending distortions. Linear molecules are exceptions from the JTE, and for a long time it was assumed that their bending distortions in degenerate states (observed in many molecules) is produced by the Renner–Teller effect (RTE) (the splitting of the generate state by the quadratic terms of the vibronic coupling). However, recently it was proved that the RTE, by splitting the degenerate electronic state, just softens the lower branch of the APES, but this lowering of the energy is not enough to overcome the rigidity of the linear configuration and to produce bending distortions. It follows that the bending distortion of linear molecular systems is due to, and only to the PJTE that mixes the electronic state under consideration with higher in energy (excited) states. This statement is enhanced by the fact that many linear molecules in nondegenerate states (and hence with no RTE) are, too, bent in the equilibrium configuration. The physical reason for the difference between the PJTE and the RTE in influencing the degenerate term is that while in the former case the vibronic coupling with the excited state produces additional covalent bonding that makes the distorted configuration preferable (see above, section 2.3), the RTE has no such influence; the splitting of the degenerate term in the RTE takes place just because the charge distribution in the two states becomes nonequivalent under the bending distortion.
Peierls distortion in linear chains. In linear molecules with three or more atoms there may be PJTE distortions that do not violate the linearity but change the interatomic distances. For instance, as a result of the PJTE a centrosymmetric linear system may become non-centrosymmetric in the equilibrium configurations, as, for example, in the BNB molecule (see in ). An interesting extension of such distortions in sufficiently long (infinite) linear chains was first considered by Peierls. In this case the electronic states, combinations of atomic states, are in fact band states, and it was shown that if the chain is composed by atoms with unpaired electrons, the valence band is only half filled, and the PJTE interaction between the occupied and unoccupied band states leads to the doubling of the period of the linear chain (see also in the books ).
Broken cylindrical symmetry. It was shown also that the PJTE not only produces the bending instability of linear molecules, but if the mixing electronic states involve a Δ state (a state with a nonzero momentum with respect to the axis of the molecule, its projection quantum number being Λ=2), the APES, simultaneously with the bending, becomes warped along the coordinate of rotations around the molecular axis, thus violating both the linear and cylindrical symmetry. It happens because the PJTE, by mixing the wavefunctions of the two interacting states, transfers the high momentum of the electrons from states with Λ=2 to states with lower momentum, and this may alter significantly their expected rovibronic spectra. | 1 | Solid-state chemistry |
In order to provide optimal performance, pigment particles must act independently of each other in the coating film and thus must remain well dispersed throughout manufacture, storage, application, and film formation. Unfortunately, colloidal dispersions such as the pigment dispersions in liquid coatings are inherently unstable, and they must be stabilized against the flocculation that might occur. | 0 | Colloidal Chemistry |
Nano particles of FeO are used as contrast agents in MRI scanning.
Ferumoxytol, sold under the brand names Feraheme and Rienso, is an intravenous FeO preparation for treatment of anemia resulting from chronic kidney disease. Ferumoxytol is manufactured and globally distributed by AMAG Pharmaceuticals. | 1 | Solid-state chemistry |
Yaghi was born in Amman, Jordan in 1965, to a refugee family originally from Mandatory Palestine. He grew up in a household with many children, had limited access to clean water and without electricity.
At the age of 15, he moved to the United States at the encouragement of his father. Although he knew little English, he began classes at Hudson Valley Community College, and later transferred to the University at Albany, SUNY to finish his college degree. He began his graduate studies at University of Illinois, Urbana-Champaign and received his PhD in 1990 under the guidance of Walter G. Klemperer. He was a National Science Foundation Postdoctoral Fellow at Harvard University (1990–1992) with Professor Richard H. Holm. In 2021, Yaghi was granted Saudi citizenship. | 1 | Solid-state chemistry |
Allpress and Sanders proposed an alternative approach to energy minimization to understanding these particles called "successive twinning". Here one starts with a single tetrahedral unit, which then forms a twin either by accident during growth or by collision with another tetrahedron. It was proposed that this could continue to eventually have five units join.
The term "successive twinning" has now come to mean a related concept: motion of the disclination either to or from a symmetric position as sketched in the atomistic simulation in the figure; see also Haiqiang Zhao et al for very similar experimental images. While in many cases experimental images show symmetric structures, sometimes they are less so and the five-fold center is quite asymmetric. There are asymmetric cases which can be metastable, and asymmetry can also be a strain relief process or involved in how the particle convert to single crystals or from single crystals. During growth there may be changes, as directly observed by Katsumichi Yagi et al for growth inside an electron microscope, and migration of the disclination from the outside has been observed in liquid-cell studies in electron microscopes. Extensive details about the atomic processes involved in motion of the disclination have been given using molecular dynamics calculations supported by density functional theory as shown in the figure. | 1 | Solid-state chemistry |
Mercouri Kanatzidis (; born 1957) is a Charles E. and Emma H. Morrison Professor of chemistry and professor of materials science and engineering at Northwestern University and Senior Scientist at Argonne National Laboratory.
Kanatzidis was listed as one of the most cited researchers in Materials Science and Engineering in 2016 based on Elsevier Scopus data. He has published over 1,635 manuscripts (ISI h-index =176 Google h-index =194]) and has over 45 patents. Kanatzidis has mentored over 90 Ph.D. students and nearly 130 postdoctoral fellows. More than 90 of these alumni hold academic positions worldwide. | 1 | Solid-state chemistry |
At the nanoscale, size effects and different dimensional constraints, like grain boundaries, dislocations, and distribution of voids, can tremendously change the properties of a material. Nanolattices possess unparalleled mechanical properties. Nanolattices are the strongest existing cellular materials despite being extremely light-weight. Though consisting of 50%-99% air, nanolattice can be as strong as steel. Its effective strength can reach up to 1 GPa. On the order of 50nm, the extremely small volume of their individual members, such as walls, nodes, and trusses, thereby statistically nearly eliminates the material flaw population and the base material of nanolattices can reach mechanical strengths on the order of the theoretical strength of an ideal, perfect crystal. While such effects are typically limited to individual, geometrically primitive structures like nanowires, the specific architecture allows nanolattices to exploit them in complex, three-dimensional structures of notably larger overall size. Nanolattices can be designed highly deformable and recoverable, even with ceramic base materials. Nanolattices are able to undergo 80% compressive strain without catastrophic failure and then still recover to 100% original shape. Nanolattices can possess mechanical metamaterial properties like auxetic (negative Poisson's ratio) or meta-fluidic behavior (large Bulk modulus). Nanolattices can combine mechanical resilience and ultra-low thermal conductivity and can have electromagnetic metamaterial characteristics like optical cloaking. However, one of the challenges in nanolattices research is figure how to retain the robust properties while scaling up. It is inherently difficult to keep nanoscale size effects in bulk structure. The straightforward workaround to overcome this challenge is to combine bulk processes with thin film deposition techniques to retain the frame space hollow structure. | 0 | Colloidal Chemistry |
Nazeeruddin received a PhD in chemistry from the Osmania University in Hyderabad, Indiaserved as a lecturer at Osmania University for two years. He then joined the Central Salt and Marine Chemicals Research Institute in Bhavnagar, India. In 1987 he joined EPFL first as a postdoctoral fellow and then held several positions as research fellow for seven years. In 2012, he was promoted to "Maître d’ Enseignement et de Recherche" (senior lecturer). Since 2014 he has served as full professor at EPFL (École Polytechnique Fédérale de Lausanne) and head of the Laboratory for Molecular Engineering of Functional Materials at School of Basic Sciences based at EPFL's Valais campus.
He has also had several affiliated and voluntary positions while working and employed at EPFL, such as World Class University Professor (2009–2014) and as BKPLUS 21 (2014–2019) at the Department of Advanced Materials, Chemistry of the Korea University, and as Visiting Professor at King Abdulaziz University in Jeddah, Saudi Arabia (2014–2021) and at the North China Electric Power University (2014–2021), and as an eminent professor at Brunei. | 1 | Solid-state chemistry |
When alternating current is passed through a thin conductor, that conductor periodically heats up and cools down following the variations in current strength. This periodic heating and cooling creates temperature waves which the conductor propagates into the surroundings. As the temperature waves propagate away from the conductor, the thermal expansion and contraction of the transmission medium (e.g. air) produces corresponding sound waves.
An ideal thermophone is made of a conductor which is very thin and has a small heat capacity. | 1 | Solid-state chemistry |
When x = 1, sodium tungsten bronze adopts a cubic phase: the perovskite crystal structure. In this form, the structure consists of corner-sharing WO octahedra with sodium ions in the interstitial gaps. For x values between 0.9 and 0.3, the structure remains similar but with an increasing deficiency of sodium ions and a smaller lattice parameter.
A number of other structure types can also be adopted, with varying electrical properties: cubic, tetragonal I and hexagonal phases are metallic, whereas orthorhombic and tetragonal II structures are semiconducting. | 1 | Solid-state chemistry |
In the nearly free electron approximation, interactions between electrons are completely ignored. This approximation allows use of Blochs Theorem which states that electrons in a periodic potential have wavefunctions and energies which are periodic in wavevector up to a constant phase shift between neighboring reciprocal lattice vectors. The consequences of periodicity are described mathematically by the Blochs theorem, which states that the eigenstate wavefunctions have the form
where the Bloch function is periodic over the crystal lattice, that is,
Here index refers to the -th energy band, wavevector is related to the direction of motion of the electron, is the position in the crystal, and is the location of an atomic site.
The NFE model works particularly well in materials like metals where distances between neighbouring atoms are small. In such materials the overlap of atomic orbitals and potentials on neighbouring atoms is relatively large. In that case the wave function of the electron can be approximated by a (modified) plane wave. The band structure of a metal like aluminium even gets close to the empty lattice approximation. | 1 | Solid-state chemistry |
It is possible to use solvents to prepare solids by precipitation or by evaporation. At times, the solvent is a hydrothermal that is under pressure at temperatures higher than the normal boiling point. A variation on this theme is the use of flux methods, which use a salt with a relatively low melting point as the solvent. | 1 | Solid-state chemistry |
Surfactants are used with quantum dots in order to manipulate their growth, assembly, and electrical properties, in addition to mediating reactions on their surfaces. Research is ongoing in how surfactants arrange themselves on the surface of the quantum dots. | 0 | Colloidal Chemistry |
Other methods include dissolution mining and evaporation methods from brines. In the evaporation method, hot water is injected into the potash, which is dissolved and then pumped to the surface where it is concentrated by solar induced evaporation. Amine reagents are then added to either the mined or evaporated solutions. The amine coats the KCl but not NaCl. Air bubbles cling to the amine + KCl and float it to the surface while the NaCl and clay sink to the bottom. The surface is skimmed for the amine + KCl, which is then dried and packaged for use as a K rich fertilizer—KCl dissolves readily in water and is available quickly for plant nutrition.
Recovery of potassium fertilizer salts from sea water has been studied in India. During extraction of salt from seawater by evaporation, potassium salts get concentrated in bittern, an effluent from the salt industry. | 1 | Solid-state chemistry |
Limnologists and chemists often define salinity in terms of mass of salt per unit volume, expressed in units of mg/L or g/L. It is implied, although often not stated, that this value applies accurately only at some reference temperature because solution volume varies with temperature. Values presented in this way are typically accurate to the order of 1%. Limnologists also use electrical conductivity, or "reference conductivity", as a proxy for salinity. This measurement may be corrected for temperature effects, and is usually expressed in units of μS/cm.
A river or lake water with a salinity of around 70 mg/L will typically have a specific conductivity at 25 °C of between 80 and 130 μS/cm. The actual ratio depends on the ions present. The actual conductivity usually changes by about 2% per degree Celsius, so the measured conductivity at 5 °C might only be in the range of 50–80 μS/cm.
Direct density measurements are also used to estimate salinities, particularly in highly saline lakes. Sometimes density at a specific temperature is used as a proxy for salinity. At other times an empirical salinity/density relationship developed for a particular body of water is used to estimate the salinity of samples from a measured density. | 1 | Solid-state chemistry |
Research in the Odom group focus on controlling materials at 100 nm scale and investigating their size and shape-dependent properties. Odom group has developed parallel, multi-scale pattering tools to generate hierarchical, anisotropic, and 3D hard and soft materials with applications in imaging, sensing, wetting and cancer therapeutics. As a result of Odom's nanofabrication tools, she has developed flat optics that can manipulate light at the nanoscale and beat the diffraction limit and tunable plasmon-based lasers. Odom also conducts research into nanoparticle-cell interactions using new biological nanoconstructs that offer imaging and therapeutic functions due to their shape (gold nanostar). | 1 | Solid-state chemistry |
In many cases, new solid compounds are further characterized by a variety of techniques that straddle the fine line that separates solid-state chemistry from solid-state physics. See Characterisation in material science for additional information. | 1 | Solid-state chemistry |
The time-independent Schrödinger equation for one particle in one dimension can be written as
or
where
* is the reduced Planck's constant,
* m is the particle mass,
* x represents distance measured in the direction of motion of the particle,
* Ψ is the Schrödinger wave function,
* V is the potential energy of the particle (measured relative to any convenient reference level),
* E is the energy of the particle that is associated with motion in the x-axis (measured relative to V),
* M(x) is a quantity defined by V(x) − E which has no accepted name in physics.
The solutions of the Schrödinger equation take different forms for different values of x, depending on whether M(x) is positive or negative. When M(x) is constant and negative, then the Schrödinger equation can be written in the form
The solutions of this equation represent travelling waves, with phase-constant +k or -k. Alternatively, if M(x) is constant and positive, then the Schrödinger equation can be written in the form
The solutions of this equation are rising and falling exponentials in the form of evanescent waves. When M(x) varies with position, the same difference in behaviour occurs, depending on whether M(x) is negative or positive. It follows that the sign of M(x) determines the nature of the medium, with negative M(x) corresponding to medium A and positive M(x) corresponding to medium B. It thus follows that evanescent wave coupling can occur if a region of positive M(x) is sandwiched between two regions of negative M(x), hence creating a potential barrier.
The mathematics of dealing with the situation where M(x) varies with x is difficult, except in special cases that usually do not correspond to physical reality. A full mathematical treatment appears in the 1965 monograph by Fröman and Fröman. Their ideas have not been incorporated into physics textbooks, but their corrections have little quantitative effect. | 1 | Solid-state chemistry |
The concept of dynamical tunnelling is particularly suited to address the problem of quantum tunnelling in high dimensions (d>1). In the case of an integrable system, where bounded classical trajectories are confined onto tori in phase space, tunnelling can be understood as the quantum transport between semi-classical states built on two distinct but symmetric tori. | 1 | Solid-state chemistry |
Magnetically assisted slip casting is a manufacturing technique that uses anisotropic stiff nanoparticle platelets in a ceramic, metal or polymer functional matrix to produce layered objects that can mimic natural objects such as nacre. Each layer of platelets is oriented in a different direction, giving the resulting object greater strength. The inventors claimed that the process is 10x faster than commercial 3D printing. The magnetisation and orientation of the ceramic platelets has been patented. | 0 | Colloidal Chemistry |
Another route to the synthesis of cobalt oxide nanoparticles is the thermal decomposition of organometallic compounds. For example, heating the metal salen complex bis(salicylaldehyde)ethylenediiminecobalt(II) ("Co-salen") in air to 500 °C. The precursor Co-salen can be obtained by reacting cobalt(II) acetate tetrahydrate in propanol at 50 °C under nitrogen atmosphere with the salen ligand (bis(salicylaldehyde)ethylenediimine). | 1 | Solid-state chemistry |
Radioactive decay is the process of emission of particles and energy from the unstable nucleus of an atom to form a stable product. This is done via the tunnelling of a particle out of the nucleus (an electron tunneling into the nucleus is electron capture). This was the first application of quantum tunnelling. Radioactive decay is a relevant issue for astrobiology as this consequence of quantum tunnelling creates a constant energy source over a large time interval for environments outside the circumstellar habitable zone where insolation would not be possible (subsurface oceans) or effective.
Quantum tunnelling may be one of the mechanisms of hypothetical proton decay. | 1 | Solid-state chemistry |
It is best known as the material for CIGS solar cells a thin-film technology used in the photovoltaic industry. In this role, CIGS has the advantage of being able to be deposited on flexible substrate materials, producing highly flexible, lightweight solar panels. Improvements in efficiency have made CIGS an established technology among alternative cell materials. | 1 | Solid-state chemistry |
Iron phosphide is a hazardous substance.
Proper eye protection such as goggles should always be used when handling iron phosphide. It can be very harmful to the eyes, especially for individuals wearing contact lenses. Contact lenses have been known to react poorly with iron phosphide due to its corrosive properties, but the scientific world does not all agree on the use of contact lenses in association with iron phosphide.
In case of inhalation, the person should be moved to fresh air or given artificial respiration if not breathing. In case of ingestion, the person's mouth should be rinsed with water unless unconscious. In case of eye contact, immediate eye flushing is necessary. | 1 | Solid-state chemistry |
Water-in-water (W/W) emulsion is a system that consists of droplets of water-solvated molecules in another continuous aqueous solution; both the droplet and continuous phases contain different molecules that are entirely water-soluble. As such, when two entirely aqueous solutions containing different water-soluble molecules are mixed, water droplets containing predominantly one component are dispersed in water solution containing another component. Recently, such a water-in-water emulsion was demonstrated to exist and be stable from coalescence by the separation of different types of non-amphiphilic, but water-soluble molecular interactions. These molecular interactions include hydrogen bonding, pi stacking, and salt bridging. This w/w emulsion was generated when the different water-solvated molecular functional groups get segregated in an aqueous mixture consisting of polymer and liquid crystal molecules.
This water-in-water emulsion consists of liquid crystals suspended as water-solvated droplets dispersed in a solution of polymer whose solvent is also water. The liquid crystal component of the emulsion is disodium cromolyn glycate (DSCG). This molecule is an anti-asthmatic drug, but also exists as a special type of liquid crystal when the concentration of DSCG is ~9-21 wt%. Unlike conventional lyotropic liquid crystals which consist of oily molecules such as 5CB, DSCG molecules are not amphiphilic, but entirely water-soluble. Thus, the separation of hydrophobic/hydrophilic groups cannot be applied to DSCG. The polymer solution serves as the medium or continuous phase of the w/w emulsion. Apart from being water-soluble, one important criterion for the generation of this w/w emulsion system is that the polymer cannot bear functional groups that interact strongly with DSCG. As such, ionic polymer when mixed with DSCG does not form w/w emulsion, but gives rise to a homogeneous solution or a precipitate solution. Consequently, the known polymers that afford w/w emulsion include polyacrylic amides and polyols. Surprisingly, some of these water-in-water emulsions can be exceptionally stable from coalescence for up to 30 days.
Because molecules of liquid crystal assume a preferred common orientation among themselves, the overall orientation of liquid crystals in a droplet is only stable in certain configurations (Fig. 3). As water solvated droplets in a w/w emulsion, DSCG molecules would align in a preferred direction on the surface of the droplet. To minimize the overall energy of the system, the DSCG molecules in the droplet prefer to align either parallel or perpendicular to the surfaces of the droplets.(Fig. 4A,B).
The stability of this water-in-water emulsion from coalescence is attributed to three molecular forces:
1. The separation of different molecular forces at the beginning of the droplet formation. Similar forces tend to stay together: pi-stacking and salt bridging are the two dominant forces in the liquid crystal droplet phase, while hydrogen bonding governs in the continuous polymer phase.
2. As the droplet size increases, the molecular interactions at the interface of the droplet phase and the continuous phase become stronger through multivalent interactions. The strengthening of interfacial molecular interactions in w/w emulsions results in the formation of a layer of polymer that coats the surface of the droplet which consequently prevents droplets from clumping together.
3. In addition, it is also proposed that when two liquid crystal droplets merge (coalescence), the orientation of the liquid crystal molecules in the two merging droplets must change to “adapt” to each other, and thus incur an energy penalty which prevent the occurrence of coalescence.
This w/w emulsion also represents a new class of polymer dispersed liquid crystals(PDLC). Traditionally known PDLC consists of oil-in-water emulsion where the oily droplet is a thermotropic liquid crystal such as 4-pentyl-4'-cyanobiphenyl (5CB), and the water phase contains certain polymers. In comparison, this water-in-water emulsion consists of Polymer-Dispersed Lyotropic Liquid Crystals, where the lyotropic liquid crystal is DSCG molecules solvated in water. Traditional PDLCs have found application, from switchable windows to projection displays. The water-in-water emulsion of polymer-dispersed lyotropic liquid crystals has the potential for building highly bio-functional materials because of its compatibility with protein structure.
Other known types of water-in-water emulsions involve the separation of different biopolymers in aqueous solution. | 0 | Colloidal Chemistry |
The structure of , as determined by X-ray powder diffraction, is primarily hexagonal close-packed system with alternating between layers of lead atoms and iodide atoms, with largely ionic bonding. Weak van der Waals interactions have been observed between lead–iodide layers. The most common stacking forms are 2H and 4H. The 4H polymorph is most common in samples grown from the melt, by precipitation, or by sublimation, whereas the 2H polymorph is usually formed by sol-gel synthesis. The solid can also take an R6 rhombohedral structure. | 1 | Solid-state chemistry |
Honeycomb refers to bioinspired patterns that provide a lightweight design for energy absorbing structures. Honeycomb design can be found in different structural biological components such as spongy bone and plant vasculature. Biologically inspired honeycomb structures include Kelvin, Weaire and Floret honeycomb (see Figure 2); each with a slightly different structure in comparison to the natural hexagonal honeycomb. These variations on the biological design have yielded significantly improved energy absorption results in comparison to traditional hexagonal honeycomb biofoam.
Due to these increased energy absorption performances, honeycomb inspired structures are being researched for use inside vehicle crumple zones. By using honeycomb structures as the inner core and surrounding the structure with a more rigid structural shell, these components can absorb impact energy during a crash and reduce the amount of energy the driver experiences. | 0 | Colloidal Chemistry |
In many applications of diffusiophoresis, the motion is driven by gradients in the concentration of a salt (electrolyte) concentration, such as sodium chloride in water. Colloidal particles in water are typically charged, and there is an electrostatic potential, called a zeta potential at their surface. This charged surface of the colloidal particle interacts with a gradient in salt concentration, and this gives rise to diffusiophoretic velocity given by
where is the permittivity of water, is the viscosity of water, is the zeta potential of the colloidal particle in the salt solution, is the reduced difference between the diffusion constant of the positively charged ion, , and the diffusion constant of the negatively charged ion, , and is the salt concentration. is the gradient, i.e., rate of change with position, of the logarithm of the salt concentration, which is equivalent to the rate of change of the salt concentration, divided by the salt concentration – it is effectively one over the distance over which the concentration decreases by a factor of e. The above equation is approximate, and only valid for 1:1 electrolytes such as sodium chloride.
Note that there are two contributions to diffusiophoresis of a charged particle in a salt gradient, which give rise to the two terms in the above equation for . The first is due to the fact that whenever there is a salt concentration gradient, then unless the diffusion constants of the positive and negative ions are exactly equal to each other, there is an electric field, i.e., the gradient acts a little like a capacitor. This electric filed generated by the salt gradient drives electrophoresis of the charged particle, just as an externally applied electric field does. This gives rise to the first term in the equation above, i.e., diffusiophoresis at a velocity .
The second part is due to the surface free energy of the surface of a charged particle, decreasing with increasing salt concentration, this is a similar mechanism to that found in diffusiophoresis in gradients of neutrial substances. This gives rise to the second part of the diffusiophoretic velocity . Note that this simple theory predicts that this contribution to the diffusiophoretic motion is always up a salt concentration gradient, it always moves particles towards higher salt concentration. By contrast, the sign of the electric-field contribution to diffusiophoresis depends on the sign of . So for example, for a negatively charged particle, , and if the positively charged ions diffuse faster than the negatively charged ones, then this term will push particles down a salt gradient, but if it is the negatively charged ions that diffuse faster, then this term pushes the particles up the salt gradient. | 0 | Colloidal Chemistry |
After studying at the David high school in Angers and at the faculties of science at University of Rennes and University of Bordeaux, Michel Pouchard specializes in the physico-chemistry of inorganic solids: oxides of transition metals, electronic properties (magnetism, insulation-to-metal transition) and electrochemistry (materials for energy, membranes, electrodes for SOFC fuel cells in particular), nanocrystalline silicon) and in the science of functional materials.
Trainee then research associate at the CNRS from 1960 to 1967 (director of the materials technology dissemination department at the CNRS from 1975 to 1984), he was a lecturer at the Faculty of Sciences, University of Bordeaux from 1967 to 1970, then professor at the University of Bordeaux I from 1970 to 1992 (professor emeritus from 2004). From 1992 to 2002, he was a professor at the Institut universitaire de France (of which he was a director from 1993 to 1997).
He was elected a member of the French Academy of sciences on 16 November 1992. He is also a member of the Academy of Technologies, the French Society of Chemistry, the Academia europaea (1998) and the Leopoldina Academy (Germany) (2000). | 1 | Solid-state chemistry |
The possibility to measure forces involving particles and surfaces directly is essential since such forces are relevant in a variety of processes involving colloidal and polymeric systems. Examples include particle aggregation, suspension rheology, particle deposition, and adhesion processes. One can equally study similar biological phenomena, such as deposition of bacteria or the infection of cells by viruses. Forces are equally most informative to investigate the mechanical properties of interfaces, bubbles, capsules, membranes, or cell walls. Such measurements permit to make conclusions about the elastic or plastic deformation or eventual rupture in such systems.
The colloidal probe technique provides a versatile tool to measure such forces between a colloidal particle and a planar substrate or between two colloidal particles (see figure above). The particles used in such experiments have typically a diameter between 1–10 μm. Typical applications involve measurements of electrical double layer forces and the corresponding surface potentials or surface charge, van der Waals forces, or forces induced by adsorbed polymers. | 0 | Colloidal Chemistry |
The consequences of salinity are
* Detrimental effects on plant growth and yield
* Damage to infrastructure (roads, bricks, corrosion of pipes and cables)
* Reduction of water quality for users, sedimentation problems, increased leaching of metals, especially copper, cadmium, manganese and zinc.
* Soil erosion ultimately, when crops are too strongly affected by the amounts of salts.
* More energy required to desalinate
Salinity is an important land degradation problem. Soil salinity can be reduced by leaching soluble salts out of soil with excess irrigation water. Soil salinity control involves watertable control and flushing in combination with tile drainage or another form of subsurface drainage. A comprehensive treatment of soil salinity is available from the United Nations Food and Agriculture Organization. | 1 | Solid-state chemistry |
Such ordering can be studied by observing the magnetic susceptibility as a function of temperature and/or the size of the applied magnetic field, but a truly three-dimensional picture of the arrangement of the spins is best obtained by means of neutron diffraction. Neutrons are primarily scattered by the nuclei of the atoms in the structure. At a temperature above the ordering point of the magnetic moments, where the material behaves as a paramagnetic one, neutron diffraction will therefore give a picture of the crystallographic structure only. Below the ordering point, e.g. the Néel temperature of an antiferromagnet or the Curie-point of a ferromagnet the neutrons will also experience scattering from the magnetic moments because they themselves possess spin. The intensities of the Bragg reflections will therefore change. In fact in some cases entirely new Bragg-reflections will occur if the unit cell of the ordering is larger than that of the crystallographic structure. This is a form of superstructure formation. Thus the symmetry of the total structure may well differ from the crystallographic substructure. It needs to be described by one of the 1651 magnetic (Shubnikov) groups rather than one of the non-magnetic space groups.
Although ordinary X-ray diffraction is blind to the arrangement of the spins, it has become possible to use a special form of X-ray diffraction to study magnetic structure. If a wavelength is selected that is close to an absorption edge of one of elements contained in the materials the scattering becomes anomalous and this component to the scattering is (somewhat) sensitive to the non-spherical shape of the outer electrons of an atom with an unpaired spin. This means that this type of anomalous X-ray diffraction does contain information of the desired type.
More recently, table-top techniques are being developed which allow magnetic structures to be studied without recourse to neutron or synchrotron sources. | 1 | Solid-state chemistry |
On the Orkney islands, kelp ash provided potash and soda ash, production starting "possibly as early as 1719" and lasting for a century. The products were "eagerly sought after by the glass and soap industries of the time." | 1 | Solid-state chemistry |
His contribution to food science was celebrated in a special edition of the Journal of Texture Studies He also initiated what he called psycho-rheology: the effect of food texture on the consumer. However he promoted and was a major contributor to the study of the rheological effects in blood flow to the genitalia, as well as biological systems in general. The journal Biorheology, which he co-founded, published an obituary. His contribution to medical science was recognised in his obituary in the journal Thrombosis Research. | 0 | Colloidal Chemistry |
For nanoparticles dispersed in a medium of different composition, the interfacial layer — formed by ions and molecules from the medium that are within a few atomic diameters of the surface of each particle — can mask or change its chemical and physical properties. Indeed, that layer can be considered an integral part of each nanoparticle. | 0 | Colloidal Chemistry |
The relative static permittivity, ε, can be measured for static electric fields as follows: first the capacitance of a test capacitor, C, is measured with vacuum between its plates. Then, using the same capacitor and distance between its plates, the capacitance C with a dielectric between the plates is measured. The relative permittivity can be then calculated as
For time-variant electromagnetic fields, this quantity becomes frequency-dependent. An indirect technique to calculate ε is conversion of radio frequency S-parameter measurement results. A description of frequently used S-parameter conversions for determination of the frequency-dependent ε of dielectrics can be found in this bibliographic source. Alternatively, resonance based effects may be employed at fixed frequencies. | 0 | Colloidal Chemistry |
In France, by the second half of the 15th century, the semi-industrialized professional manufacture of soap was concentrated in a few centers of Provence—Toulon, Hyères, and Marseille—which supplied the rest of France. In Marseilles, by 1525, production was concentrated in at least two factories, and soap production at Marseille tended to eclipse the other Provençal centers. English manufacture tended to concentrate in London.
Finer soaps were later produced in Europe from the 16th century, using vegetable oils (such as olive oil) as opposed to animal fats. Many of these soaps are still produced, both industrially and by small-scale artisans. Castile soap is a popular example of the vegetable-only soaps derived from the oldest "white soap" of Italy. In 1634 Charles I granted the newly formed Society of Soapmakers a monopoly in soap production who produced certificates from foure Countesses, and five Viscountesses, and divers other Ladies and Gentlewomen of great credite and quality, besides common Laundresses and others, testifying that the New White Soap washeth whiter and sweeter than the Old Soap.
During the Restoration era (February 1665 – August 1714) a soap tax was introduced in England, which meant that until the mid-1800s, soap was a luxury, used regularly only by the well-to-do. The soap manufacturing process was closely supervised by revenue officials who made sure that soapmakers' equipment was kept under lock and key when not being supervised. Moreover, soap could not be produced by small makers because of a law that stipulated that soap boilers must manufacture a minimum quantity of one imperial ton at each boiling, which placed the process beyond the reach of the average person. The soap trade was boosted and deregulated when the tax was repealed in 1853.
Industrially manufactured bar soaps became available in the late 18th century, as advertising campaigns in Europe and America promoted popular awareness of the relationship between cleanliness and health. In modern times, the use of soap has become commonplace in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. | 1 | Solid-state chemistry |
Coral calcium is a salt of calcium derived from fossilized coral reefs (primarily from limestone and coastal deposits). It has been promoted as an alternative, but unsubstantiated, treatment or cure for a number of health conditions. | 1 | Solid-state chemistry |
Researchers have fabricated transistors of phosphorene to examine its performance in actual devices. Phosphorene-based transistor consists of a channel of 1.0 μm and uses few layered phosphorene with a thickness varying from 2.1 to over 20 nm. Reduction of the total resistance with decreasing gate voltage is observed, indicating the p-type characteristic of phosphorene. Linear I-V relationship of transistor at low drain bias suggests good contact properties at the phosphorene/metal interface. Good current saturation at high drain bias values was observed. However, it was seen that the mobility is reduced in few-layer phosphorene when compared to bulk black phosphorus. Field-effect mobility of phosphorene-based transistor shows a strong thickness dependence, peaking at around 5 nm and decrease steadily with further increase of crystal thickness.
Atomic layer deposition (ALD) dielectric layer and/or hydrophobic polymer is used as encapsulation layers in order to prevent device degradation and failure. Phosphorene devices are reported to maintain their function for weeks with encapsulation layer, whereas experience device failure within a week when exposed to ambient condition. | 1 | Solid-state chemistry |
Settleable solids are the particulates that settle out of a still fluid. Settleable solids can be quantified for a suspension using an Imhoff cone. The standard Imhoff cone of transparent glass or plastic holds one liter of liquid and has calibrated markings to measure the volume of solids accumulated in the bottom of the conical container after settling for one hour. A standardized Imhoff cone procedure is commonly used to measure suspended solids in wastewater or stormwater runoff. The simplicity of the method makes it popular for estimating water quality. To numerically gauge the stability of suspended solids and predict agglomeration and sedimentation events, zeta potential is commonly analyzed. This parameter indicates the electrostatic repulsion between solid particles and can be used to predict whether aggregation and settling will occur over time.
The water sample to be measured should be representative of the total stream. Samples are best collected from the discharge falling from a pipe or over a weir, because samples skimmed from the top of a flowing channel may fail to capture larger, high-density solids moving along the bottom of the channel. The sampling bucket is vigorously stirred to uniformly re-suspend all collected solids immediately before pouring the volume required to fill the cone. The filled cone is immediately placed in a stationary holding rack to allow quiescent settling. The rack should be located away from heating sources, including direct sunlight, which might cause currents within the cone from thermal density changes of the liquid contents. After 45 minutes of settling, the cone is partially rotated about its axis of symmetry just enough to dislodge any settled material adhering to the side of the cone. Accumulated sediment is observed and measured fifteen minutes later, after one hour of total settling time. | 0 | Colloidal Chemistry |
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