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The crosslinks which bond the polymers of a hydrogel fall under two general categories: physical hydrogels and chemical hydrogels. Chemical hydrogels have covalent cross-linking bonds, whereas physical hydrogels have non-covalent bonds. Chemical hydrogels can result in strong reversible or irreversible gels due to the covalent bonding. Chemical hydrogels that contain reversible covalent cross-linking bonds such as hydrogels of thiomers being cross-linked via disulfide bonds are non-toxic and are used in numerous medicinal products. Physical hydrogels usually have high biocompatibility, are not toxic, and are also easily reversible by simply changing an external stimulus such as pH, ion concentration (alginate) or temperature (gelatine); they are also used for medical applications. Physical crosslinks consist of hydrogen bonds, hydrophobic interactions, and chain entanglements (among others). A hydrogel generated through the use of physical crosslinks is sometimes called a reversible hydrogel. Chemical crosslinks consist of covalent bonds between polymer strands. Hydrogels generated in this manner are sometimes called permanent hydrogels.
Hydrogels are prepared using a variety of polymeric materials, which can be divided broadly into two categories according to their origin: natural or synthetic polymers. Natural polymers for hydrogel preparation include hyaluronic acid, chitosan, heparin, alginate, gelatin and fibrin. Common synthetic polymers include polyvinyl alcohol, polyethylene glycol, sodium polyacrylate, acrylate polymers and copolymers thereof. Whereas natural hydrogels are usually non-toxic, and often provides other advantages for medical use, such as biocompatibility, biodegradability, antibiotic/antifungal effect and improve regeneration of nearby tissue, their stability and strength is usually much lower than synthetic hydrogels. There are also synthetic hydrogels than can be used for medical applications, such as polyethylene glycol (PEG), polyacrylate, and polyvinylpyrrolidone (PVP). | 0 | Colloidal Chemistry |
* Kemerovo Division of Institute of Solid State Chemistry and Mechanochemistry of the Siberian Branch of the RAS | 1 | Solid-state chemistry |
Streaming currents in well-defined geometries are a sensitive method to characterize the zeta potential of surfaces, which is important in the fields of colloid and interface science. In geology, measurements of related spontaneous potential are used for evaluations of formations. Streaming potential has to be considered in design for flow of poorly conductive fluids (e.g., gasoline lines) because of the danger of buildup of high voltages. The streaming current monitor (SCM) is a fundamental tool for monitoring coagulation in wastewater treatment plants. The degree of coagulation of raw water may be monitored by the use of an SCM to provide a positive feedback control of coagulant injection. As the streaming current of the wastewater increases, more coagulant agent is injected into the stream. The higher levels of coagulant agent cause the small colloidal particles to coagulate and sediment out of the stream. Since less colloid particles are in the wastewater stream, the streaming potential decreases. The SCM recognizes this and subsequently reduces the amount of coagulant agent injected into the wastewater stream. The implementation of SCM feedback control has led to a significant materials cost reduction, one that was not realized until the early 1980s. In addition to monitoring capabilities, the streaming current could, in theory, generate usable electrical power. This process, however, has yet to be applied as typical streaming potential mechanical to electrical efficiencies are around 1%. | 0 | Colloidal Chemistry |
Strong salts or strong electrolyte salts are chemical salts composed of strong electrolytes. These salts dissociate completely or almost completely in water. They are generally odorless and nonvolatile.
Strong salts start with Na__, K__, NH__, or they end with __NO, __ClO, or __CHCOO. Most group 1 and 2 metals form strong salts. Strong salts are especially useful when creating conductive compounds as their constituent ions allow for greater conductivity.
Weak salts or weak electrolyte salts are composed of weak electrolytes. These salts do not dissociate well in water. They are generally more volatile than strong salts. They may be similar in odor to the acid or base they are derived from. For example, sodium acetate, CHCOONa, smells similar to acetic acid CHCOOH. | 1 | Solid-state chemistry |
Pyrite oxidation by atmospheric in the presence of moisture () initially produces ferrous ions () and sulfuric acid which dissociates into sulfate ions and protons, leading to acid mine drainage (AMD). An example of acid rock drainage caused by pyrite is the 2015 Gold King Mine waste water spill. | 1 | Solid-state chemistry |
Carbon Nanofoams have been shown to have great application as solar steam generators. They possess excellent light absorption, good thermal stability, low density, and low thermal conductivity, all factors important to solar generators. In experiments done, carbon nanofoams showed superior solar photo-thermal performance with an evaporation rate of 1.68 kg m−2 h−1 achieved under 1 sun irradiation.
Additionally, carbon nanofoams have also been used to create extremely efficient aerosol filters. Using cellulose nanofibers collected from recycled milk jugs, researchers were able to develop a carbon nanofoam that achieved a very high filtration efficacy (>99.5%) in tests run with 0.7 wt% nanofoam sample for particles smaller than 360 nm. This efficiency value even meets the standard requirements of the N95 respirator face masks. The structure of the nanofoam filter gives it an advantage in performance over normal filters when dealing with high particle bearing | 0 | Colloidal Chemistry |
Liquid molecules can form a layer around the solid particles and there by enhance the local ordering of the atomic structure at the interface region.hence, the atomic structure of such liquid layer is more ordered than that of the bulk liquid. | 0 | Colloidal Chemistry |
* 2001 National Science Foundation CAREER Award
* 2014 Elected Fellow of the American Chemical Society
* 2012 Elected Fellow of the American Association for the Advancement of Science
* 2013 Wayne State University Gershenson Distinguished Faculty Fellowship Award
* 2019 Wayne State University Outstanding Graduate Mentor Award
* 2020 Inducted into the Wayne State University Academy of Scholars | 1 | Solid-state chemistry |
If there is a magnetic and electrical interaction at the same time on the radioactive nucleus as described above, combined interactions result. This leads to the splitting of the respectively observed frequencies. The analysis may not be trivial due to the higher number of frequencies that must be allocated. These then depend in each case on the direction of the electric and magnetic field to each other in the crystal. PAC is one of the few ways in which these directions can be determined. | 1 | Solid-state chemistry |
Ions in ionic compounds are primarily held together by the electrostatic forces between the charge distribution of these bodies, and in particular, the ionic bond resulting from the long-ranged Coulomb attraction between the net negative charge of the anions and net positive charge of the cations. There is also a small additional attractive force from van der Waals interactions which contributes only around 1–2% of the cohesive energy for small ions. When a pair of ions comes close enough for their outer electron shells (most simple ions have closed shells) to overlap, a short-ranged repulsive force occurs, due to the Pauli exclusion principle. The balance between these forces leads to a potential energy well with minimum energy when the nuclei are separated by a specific equilibrium distance.
If the electronic structure of the two interacting bodies is affected by the presence of one another, covalent interactions (non-ionic) also contribute to the overall energy of the compound formed. Ionic compounds are rarely purely ionic, i.e. held together only by electrostatic forces. The bonds between even the most electronegative/electropositive pairs such as those in caesium fluoride exhibit a small degree of covalency. Conversely, covalent bonds between unlike atoms often exhibit some charge separation and can be considered to have a partial ionic character. The circumstances under which a compound will have ionic or covalent character can typically be understood using Fajans' rules, which use only charges and the sizes of each ion. According to these rules, compounds with the most ionic character will have large positive ions with a low charge, bonded to a small negative ion with a high charge. More generally HSAB theory can be applied, whereby the compounds with the most ionic character are those consisting of hard acids and hard bases: small, highly charged ions with a high difference in electronegativities between the anion and cation. This difference in electronegativities means that the charge separation, and resulting dipole moment, is maintained even when the ions are in contact (the excess electrons on the anions are not transferred or polarized to neutralize the cations).
Although chemists classify idealized bond types as being ionic or covalent, the existence of additional types such as hydrogen bonds and metallic bonds, for example, has led some philosophers of science to suggest that alternative approaches to understanding bonding are required. This could be by applying quantum mechanics to calculate binding energies. | 1 | Solid-state chemistry |
Composite metal foam panels, manufactured using 2 mm steel hollow spheres embedded in a stainless steel matrix and processed using a powder metallurgy technique, were used together with boron carbide ceramic and aluminium 7075 or Kevlar back panels to fabricate a new composite armour system. This composite armour was tested against NIJ-Type III and Type IV threats using NIJ 0101.06 ballistic test standard. The highly functional layer-based design allowed the composite metal foam to absorb the ballistic kinetic energy effectively, where the CMF layer accounted for 60–70% of the total energy absorbed by the armour system and allowed the composite armour system to show superior ballistic performance for both Type III and IV threats. The results of this testing program suggests that CMF can be used to reduce the weight and increase the performance of armour for Type III and Type IV threats. | 0 | Colloidal Chemistry |
Phosphorene 2D materials are composed of individual layers held together by van der Waals forces in lieu of covalent or ionic bonds that are found in most materials. There are five electrons on 3p orbitals of phosphorus atom, thus, giving rise to sp hybridization of phosphorus atom within phosphorene structure. Monolayered phosphorene exhibits the structure of a quadrangular pyramid because three electrons of P atom bond with three other P atoms covalently at 2.18 Å leaving one lone pair. Two of the phosphorus atoms are in the plane of the layer at 99° from one another, and the third phosphorus is between the layers at 103°, yielding an average angle of 102°.
According to density functional theory (DFT) calculations, phosphorene forms in a honeycomb lattice structure with notable nonplanarity in the shape of structural ridges. It is predicted that crystal structure of black phosphorus can be discriminated under high pressure. This is mostly due to the anisotropic compressibility of black phosphorus because of the asymmetrical crystal structures. Subsequently, the van der Waals bond can be greatly compressed in the z-direction. However, there is a great variation in compressibility across the orthogonal x-y plane.
It is reported that controlling the centrifugal speed of production may aid in regulating the thickness of a material. For example, centrifuging at 18000 rpm during synthesis produced phosphorene with an average diameter of 210 nm and a thickness of 2.8 ± 1.5 nm (2–7 layers). | 1 | Solid-state chemistry |
*Lightfoot, P.; Pei, S. Y.; Jorgensen, J. D.; Manthiram, A.; Tang, X. X. & J. B. Goodenough. [https://www.osti.gov/servlets/purl/6614880 "Excess Oxygen Defects in Layered Cuprates"], Argonne National Laboratory, The University of Texas-Austin, Materials Science Laboratory United States Department of Energy, National Science Foundation, (September 1990).
*Argyriou, D. N.; Mitchell, J. F.; Chmaissem, O.; Short, S.; Jorgensen, J. D. & J. B. Goodenough. [https://www.osti.gov/servlets/purl/521660 "Sign Reversal of the Mn-O Bond Compressibility in LaSrMnO Below T: Exchange Striction in the Ferromagnetic State"], Argonne National Laboratory, The University of Texas-Austin, Center for Material Science and Engineering United States Department of Energy, National Science Foundation, Welch Foundation, (March 1997).
*Goodenough, J. B.; Abruna, H. D. & M. V. Buchanan. [https://www.osti.gov/biblio/935429-basic-research-needs-electrical-energy-storage-report-basic-energy-sciences-workshop-electrical-energy-storage-april "Basic Research Needs for Electrical Energy Storage. Report of the Basic Energy Sciences Workshop on Electrical Energy Storage, April 2–4, 2007"], United States Department of Energy, (April 4, 2007). | 1 | Solid-state chemistry |
As of November 2023, the International Agency for Research on Cancer (IARC) has classified PFOA as carcinogenic to humans (Group 1) based on “sufficient” evidence for cancer in animals and “strong” mechanistic evidence in exposed humans. IARC also classified PFOS as possibly carcinogenic to humans (Group 2b) based on “strong” mechanistic evidence. There is a lack of high-quality epidemiological data on the associations between many specific PFAS chemicals and specific cancer types, and research is ongoing. | 0 | Colloidal Chemistry |
and related molybdenum sulfides are efficient catalysts for hydrogen evolution, including the electrolysis of water; thus, are possibly useful to produce hydrogen for use in fuel cells. | 1 | Solid-state chemistry |
After receiving his PhD in 1942, Smith began teaching in the Chemistry Department at the Missouri School of Mines in Rolla. While teaching at Missouri, Smith became a mentor to a brilliant 15-year old high student and future National Medal of Science winner named M. Frederick Hawthorne who would eventually follow him to Pomona.
During World War II, Smith worked on the Manhattan Project at the Hanford Site in Richland, Washington. During the 1951–1952 academic year, he did a Guggenheim Fellowship in England on surface chemistry.
Smith joined the faculty at Pomona in 1945. His research focus was colloids. In 1956, he was promoted to the rank of full professor, and he later became the chair of the colleges chemistry department. During the 1958–1959 academic year, he did another fellowship in England sponsored by the American Chemical Societys Petroleum Research Fund.
In 1958, he co-authored with colleague W. Conway Pierce the textbook General Chemistry Problems. He and Pierce published several later editions of the book under the title Solving General Chemistry Problems.
Smith was an early adopter of computer technology, which he used in his courses. | 0 | Colloidal Chemistry |
The formation of electronic bands and band gaps can be illustrated with two complementary models for electrons in solids. The first one is the nearly free electron model, in which the electrons are assumed to move almost freely within the material. In this model, the electronic states resemble free electron plane waves, and are only slightly perturbed by the crystal lattice. This model explains the origin of the electronic dispersion relation, but the explanation for the band gaps is subtle in this model.
The second model starts from the opposite limit, in which the electrons are tightly bound to individual atoms. The electrons of a single, isolated atom occupy atomic orbitals with discrete energy levels. If two atoms come close enough so that their atomic orbitals overlap, the electrons can tunnel between the atoms. This tunneling splits (hybridizes) the atomic orbitals into molecular orbitals with different energies.
Similarly, if a large number of identical atoms come together to form a solid, such as a crystal lattice, the atoms' atomic orbitals overlap with the nearby orbitals. Each discrete energy level splits into levels, each with a different energy. Since the number of atoms in a macroscopic piece of solid is a very large number (~10) the number of orbitals is very large and thus they are very closely spaced in energy (of the order of ). The energy of the adjacent levels is so close together that they can be considered as a continuum, an energy band.
This formation of bands is mostly a feature of the outermost electrons (valence electrons) in the atom, which are the ones involved in chemical bonding and electrical conductivity. The inner electron orbitals do not overlap to a significant degree, so their bands are very narrow.
Band gaps are essentially leftover ranges of energy not covered by any band, a result of the finite widths of the energy bands. The bands have different widths, with the widths depending upon the degree of overlap in the atomic orbitals from which they arise. Two adjacent bands may simply not be wide enough to fully cover the range of energy. For example, the bands associated with core orbitals (such as 1s electrons) are extremely narrow due to the small overlap between adjacent atoms. As a result, there tend to be large band gaps between the core bands. Higher bands involve comparatively larger orbitals with more overlap, becoming progressively wider at higher energies so that there are no band gaps at higher energies. | 1 | Solid-state chemistry |
From 1941 to 1951, Vinograd worked for the Shell Development Company in Emeryville, California. During this period, his wife Sherna gave birth to their two daughters, Julia and Deborah. In 1951 he became a senior research fellow at the California Institute of Technology, in Pasadena, California, where he remained for the rest of his career. In 1956 he became a research associate, and in 1965 he was promoted to professor of chemistry and biology. He pioneered the use of ultracentrifugation for the analysis of complex molecules, in particular DNA. | 0 | Colloidal Chemistry |
Hollow nanospheres of cobalt oxide have been investigated as materials for gas sensor electrodes, for the detection of toluene, acetone, and other organic vapors.
Cobalt oxide nanoparticles anchored on single-walled carbon nanotubes have been investigated for sensing nitrogen oxides and hydrogen. This application takes advantage of the reactivity between the gas and the oxide, as well as the electrical connection with the substrate (both being p-type semiconductors). Nitrogen oxides react with the oxide as electron acceptors, reducing the electrode's resistance; whereas hydrogen acts as an electron donor, increasing the resistance. | 1 | Solid-state chemistry |
Cationic detergents are similar to anionic ones, but quaternary ammonium replaces the hydrophilic anionic sulfonate group. The ammonium sulfate center is positively charged. Cationic surfactants generally have poor detergency. | 0 | Colloidal Chemistry |
Tarascon was elected a Foreign Member of the Royal Society (ForMemRS) in 2014. His nomination reads:
Tarascon was honoured by the New Jersey Inventors Hall of Fame in 2002. He was nominated to the Académie des Sciences in 2005, and was the University of Picardie Jules Verne (UPJV) gold medalist in 2008. He won the ENI Protection of the Environment award in 2011. In 2015 he was awarded the Royal Society of Chemistrys Centenary Prize. In 2016, he received an honorary doctorate doctor honoris causa from Hasselt University. In 2017, he was one of the two winners of the Eric and Sheila Samson Prime Ministers Prize for Innovation in Alternative Fuels for Transportation. He was one of the five nominated for the CNRS Innovation Medals. In 2020 he received the Balzan Prize for Environmental Challenges: Materials Science for Renewable Energy. | 1 | Solid-state chemistry |
Salinity is an ecological factor of considerable importance, influencing the types of organisms that live in a body of water. As well, salinity influences the kinds of plants that will grow either in a water body, or on land fed by a water (or by a groundwater). A plant adapted to saline conditions is called a halophyte. A halophyte which is tolerant to residual sodium carbonate salinity are called glasswort or saltwort or barilla plants. Organisms (mostly bacteria) that can live in very salty conditions are classified as extremophiles, or halophiles specifically. An organism that can withstand a wide range of salinities is euryhaline.
Salts are expensive to remove from water, and salt content is an important factor in water use, factoring into potability and suitability for irrigation. Increases in salinity have been observed in lakes and rivers in the United States, due to common road salt and other salt de-icers in runoff.
The degree of salinity in oceans is a driver of the world's ocean circulation, where density changes due to both salinity changes and temperature changes at the surface of the ocean produce changes in buoyancy, which cause the sinking and rising of water masses. Changes in the salinity of the oceans are thought to contribute to global changes in carbon dioxide as more saline waters are less soluble to carbon dioxide. In addition, during glacial periods, the hydrography is such that a possible cause of reduced circulation is the production of stratified oceans. In such cases, it is more difficult to subduct water through the thermohaline circulation.
Not only is salinity a driver of ocean circulation, but changes in ocean circulation also affect salinity, particularly in the subpolar North Atlantic where from 1990 to 2010 increased contributions of Greenland meltwater were counteracted by increased northward transport of salty Atlantic waters. However, North Atlantic waters have become fresher since the mid-2010s due to increased Greenland meltwater flux. | 1 | Solid-state chemistry |
In the United States, DATEM is generally recognized as safe by the Food and Drug Administration (FDA) as specified in the Code of Federal Regulations (21CFR184.1101).
DATEM is approved by the European Food Safety Authority for use as food additive with the E number E472e. | 0 | Colloidal Chemistry |
Although not commercially significant sodium hydride has been proposed for hydrogen storage for use in fuel cell vehicles. In one experimental implementation, plastic pellets containing NaH are crushed in the presence of water to release the hydrogen. One challenge with this technology is the regeneration of NaH from the NaOH formed by hydrolysis. | 1 | Solid-state chemistry |
Non-ionic surfactants have covalently bonded oxygen-containing hydrophilic groups, which are bonded to hydrophobic parent structures. The water-solubility of the oxygen groups is the result of hydrogen bonding. Hydrogen bonding decreases with increasing temperature, and the water solubility of non-ionic surfactants therefore decreases with increasing temperature.
Non-ionic surfactants are less sensitive to water hardness than anionic surfactants, and they foam less strongly. The differences between the individual types of non-ionic surfactants are slight, and the choice is primarily governed having regard to the costs of special properties (e.g., effectiveness and efficiency, toxicity, dermatological compatibility, biodegradability) or permission for use in food. | 0 | Colloidal Chemistry |
A boy chasing a chicken and pouring salt over it is an icon that has become synonymous with the brand.
The Cerebos salt company invented Bisto gravy powder product (a mixture of salt, flavourings and colourings), at its salt factory in Middlewich, Cheshire in the United Kingdom. It was acquired by RHM in 1968, which later sold its stake in Cerebos South Africa in the 1980s and Cerebos Pacific to Suntory in 1990. | 1 | Solid-state chemistry |
The organized and uniform collection of tax revenue on salt in British India began under the British Raj. Both before and after that, various native rulers of the Indian Princely states (outside British India proper) collected such revenue in accordance with their own revenue and administrative requirements and resources. In 1856, the government appointed the young William Chichele Plowden, Secretary of the Board of Revenue of the North West Provinces, to report on the establishment of a uniform system of revenue realisation from salt within the British Provinces, and he recommended the extension of the excise system, the reduction of duty, and the introduction of a system of licensing as the measures to achieve this goal.
In 1876, separate departments under a Salt Commissioner were set up, and these operated at the level of each British Province and Presidency. It was with the passing of the Government of India Act 1935, that within British India (which then included much of present-day Pakistan) salt came under the exclusive control of the central government, with the Government of India taking over the task of collecting salt revenue and transferring it from the provincial salt agencies to the Central Excise and Revenue Department. In 1944, the Government of India passed the Central Excises and Salt Act which unified and amended all laws dealing with duties on excise and salt.
The Salt Department was originally a part of the Central Board of Revenue under the Ministry of Finance, but since a reorganisation of the ministries of India in 1957 it has come under the authority of the Ministry of Commerce and Industry.
According to the Union List of subjects under the Seventh Schedule of the Indian Constitution, the "manufacture, supply and distribution of salt by Union agencies; regulation and control of manufacture, supply and distribution of salt by other agencies", is the responsibility of the Government of India. The posts of Salt Controller, Deputy Salt Controller and Assistant Salt Controller were re-categorized as Salt Commissioner, Deputy Salt Commissioner and Assistant Salt Commissioner in 1952 and the Indian Salt Services were created in 1954 for the realisation of the entry under the Union List. The Salt Service has both Group A and Group B wings. | 1 | Solid-state chemistry |
Depletion forces were first described by Sho Asakura and Fumio Oosawa in 1954. In their model, the force is always considered to be attractive. Additionally, the force is considered to be proportional to the osmotic pressure. The Asakura–Oosawa model assumes low macromolecule densities and that the density distribution, , of the macromolecules is constant. Asakura and Oosawa described four cases in which depletion forces would occur. They first described the most general case as two solid plates in a solution of macromolecules. The principles for the first case were then extended to three additional cases. | 0 | Colloidal Chemistry |
In chemistry, a chemical transport reaction describes a process for purification and crystallization of non-volatile solids. The process is also responsible for certain aspects of mineral growth from the effluent of volcanoes. The technique is distinct from chemical vapor deposition, which usually entails decomposition of molecular precursors and which gives conformal coatings.
The technique, which was popularized by Harald Schäfer, entails the reversible conversion of nonvolatile elements and chemical compounds into volatile derivatives. The volatile derivative migrates throughout a sealed reactor, typically a sealed and evacuated glass tube heated in a tube furnace. Because the tube is under a temperature gradient, the volatile derivative reverts to the parent solid and the transport agent is released at the end opposite to which it originated (see next section). The transport agent is thus catalytic. The technique requires that the two ends of the tube (which contains the sample to be crystallized) be maintained at different temperatures. So-called two-zone tube furnaces are employed for this purpose. The method derives from the Van Arkel de Boer process which was used for the purification of titanium and vanadium and uses iodine as the transport agent. | 1 | Solid-state chemistry |
In the dressed micelle model, the total Gibbs energy is broken down into several components accounting for the hydrophobic tail, the electrostatic repulsion of the head groups, and the interfacial energy on the surface of the micelle.
where the components of the total Gibbs micellization energy are hydrophobic, electrostatic, and interfacial. | 0 | Colloidal Chemistry |
Surfactant protein B is an essential lipid-associated protein found in pulmonary surfactant. Without it, the lung would not be able to inflate after a deep breath out. It rearranges lipid molecules in the fluid lining the lung so that tiny air sacs in the lung, called alveoli, can more easily inflate. | 0 | Colloidal Chemistry |
The Salt Service is tasked with several functions including monitoring and quality updation of salt, setting production targets, providing technical guidance to salt manufacturers and leasing and managing department lands for the same, collection of cess, fees and rents and the implementation of various schemes aimed at combating iodine deficiency and programs for promoting the growth of the salt industry in India. | 1 | Solid-state chemistry |
Potential applications include herbicides and pesticides formulations, detergents, healthcare and cosmetics, pulp and paper, coal, textiles, ceramic processing and food industries, uranium ore-processing, and mechanical dewatering of peat. | 0 | Colloidal Chemistry |
Dipalmitoylphosphatidylcholine (DPPC) is a phospholipid with two 16-carbon saturated chains and a phosphate group with quaternary amine group attached. The DPPC is the strongest surfactant molecule in the pulmonary surfactant mixture. It also has a higher compaction capacity than the other phospholipids, because the apolar tail is less bent. Nevertheless, without the other substances of the pulmonary surfactant mixture, the DPPCs adsorption kinetics is very slow. This happens primarily because the phase transition temperature between gel to liquid crystal of pure DPPC is 41.5 °C, which is higher than the human bodys temperature of 37 °C. | 0 | Colloidal Chemistry |
Krogmann's salt was first synthesized by Klaus Krogmann in the late 1960s.
Krogmann's salt most commonly refers to a platinum metal complex of the formula K[Pt(CN)X] where X is usually bromine (or sometimes chlorine). Many other non-stoichiometric metal salts containing the anionic complex [Pt(CN)] can also be characterized. | 1 | Solid-state chemistry |
There is political dispute between China and South Korea on ultrafine dust. South Korea claims that about 80% of ultrafine dust comes from China, and China and South Korea should cooperate to reduce the level of fine dust. China, however, argues that the Chinese government have already implemented its policy regarding ecological environment. According to China's government, its quality of air has been improved more than 40% since 2013. However, the air pollution in South Korea got worse. Therefore, the dispute between China and South Korea has become political. In March 2019, Seoul Research Institute of Public Health and Environment said that 50% to 70% of the fine dust is from China, therefore China is responsible for the air pollution in South Korea. This dispute provokes dispute among citizens as well.
In July 2014, China's paramount leader Xi Jinping and the South Korean government agreed to enforce Korea-China Cooperative Project, regarding Sharing of observation data on air pollutions, joint research on an air pollution forecast model and air pollution source identification, and human resources exchanges, etc. Followed by this agreement, in 2018, China and South Korea signed China-Korea Environmental Cooperation Plan to resolute environmental issues. China Research Academy of Environmental Studies (CRAES) in Beijing is developing a building for China-Korea Environmental Cooperation Center including office building and laboratory building. Based on this cooperation, South Korea already sent 10 experts on environments to China for research, and China will also send more experts for long-term research. By this bilateral relations, China and Republic of Korea are seeking resolution on air pollution in North East Asia region, and seeks international security. | 0 | Colloidal Chemistry |
* Narrow-range ethoxylate
* Octaethylene glycol monododecyl ether
* Pentaethylene glycol monododecyl ether | 0 | Colloidal Chemistry |
A material may have lower melting point in nanoparticle form than in the bulk form. For example, 2.5 nm gold nanoparticles melt at about 300 °C, whereas bulk gold melts at 1064 °C. | 0 | Colloidal Chemistry |
Susan M. Kauzlarich is an American chemist and is presently a distinguished professor of chemistry at the University of California, Davis (UC Davis). At UC Davis, Kauzlarich leads a research group focused on the synthesis and characterization of Zintl phases and nanoclusters with applications in the fields of thermoelectric materials, magnetic resonance imaging, energy storage, opto-electronics, and drug delivery. Kauzlarich has published over 250 peer-reviewed publications and has been awarded several patents. In 2009, Kauzlarich received the annual Presidential Award for Excellence in Science, Mathematics and Engineering Mentoring, which is administered by the National Science Foundation to acknowledge faculty members who raise the membership of minorities, women and disabled students in the science and engineering fields. In January 2022 she became Deputy Editor for the scientific journal, Science Advances. She gave the Edward Herbert Boomer Memorial Lecture of the University of Alberta in 2023. | 1 | Solid-state chemistry |
Lead(II) iodide (or lead iodide) is a chemical compound with the formula . At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.
The compound currently has a few specialized applications, such as the manufacture of solar cells, X-rays and gamma-ray detectors. Its preparation is an entertaining and popular demonstration in chemistry education, to teach topics such as precipitation reactions and stoichiometry. It is decomposed by light at temperatures above , and this effect has been used in a patented photographic process.
Lead iodide was formerly employed as a yellow pigment in some paints, with the name iodide yellow. However, that use has been largely discontinued due to its toxicity and poor stability. | 1 | Solid-state chemistry |
Organic nanocrystals consist of pure drugs and surface active agents required for stabilization. They are defined as carrier-free submicron colloidal drug delivery systems with a mean particle size in the nanometer range. The primary importance of the formulation of drugs into nanocrystals is the increase in particle surface area in contact with the dissolution medium, therefore increasing bioavailability. A number of drug products formulated in this way are on the market. | 0 | Colloidal Chemistry |
The wave function of a physical system of particles specifies everything that can be known about the system. Therefore, problems in quantum mechanics analyze the system's wave function. Using mathematical formulations, such as the Schrödinger equation, the time evolution of a known wave function can be deduced. The square of the absolute value of this wave function is directly related to the probability distribution of the particle positions, which describes the probability that the particles would be measured at those positions.
As shown in the animation, a wave packet impinges on the barrier, most of it is reflected and some is transmitted through the barrier. The wave packet becomes more de-localized: it is now on both sides of the barrier and lower in maximum amplitude, but equal in integrated square-magnitude, meaning that the probability the particle is somewhere remains unity. The wider the barrier and the higher the barrier energy, the lower the probability of tunneling.
Some models of a tunneling barrier, such as the rectangular barriers shown, can be analysed and solved algebraically. Most problems do not have an algebraic solution, so numerical solutions are used. "Semiclassical methods" offer approximate solutions that are easier to compute, such as the WKB approximation. | 1 | Solid-state chemistry |
These species are classified as both organosulfur and organoselenium compounds. They are hybrids of organic disulfides and organic diselenides. | 1 | Solid-state chemistry |
Biopolymers like cellulose, lignin, chitin, or starch may be broken down into their individual nanoscale building blocks, obtaining anisotropic fiber- or needle-like nanoparticles. The biopolymers are disintegrated mechanically in combination with chemical oxidation or enzymatic treatment to promote breakup, or hydrolysed using acid. | 0 | Colloidal Chemistry |
Molybdenite is a mineral of molybdenum disulfide, MoS. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms. The Mo-S bonds are strong, but the interaction between the sulfur atoms at the top and bottom of separate sandwich-like tri-layers is weak, resulting in easy slippage as well as cleavage planes.
Molybdenite crystallizes in the hexagonal crystal system as the common polytype 2H and also in the trigonal system as the 3R polytype. | 1 | Solid-state chemistry |
Hazen and his colleagues started the Carbon Mineral Challenge, a citizen science project dedicated to accelerating the discovery of "missing" carbon-bearing minerals. | 1 | Solid-state chemistry |
The Born–Landé equation is a means of calculating the lattice energy of a crystalline ionic compound. In 1918 Max Born and Alfred Landé proposed that the lattice energy could be derived from the electrostatic potential of the ionic lattice and a repulsive potential energy term.
where:
*N = Avogadro constant;
*M = Madelung constant, relating to the geometry of the crystal;
*z = numeric charge number of cation
*z = numeric charge number of anion
*e = elementary charge, 1.6022 C
*ε = permittivity of free space
*:4πε = 1.112 C/(J·m)
*r = distance between closest cation [ +ve ] & anion [ -ve ].
*n = Born exponent, typically a number between 5 and 12, determined experimentally by measuring the compressibility of the solid, or derived theoretically.
*E = Lattice energy is expressed by E . | 1 | Solid-state chemistry |
Thermal conductivity, viscosity, density, specific heat, and surface tension are considered some main thermophysical properties of nanofluids. Various parameters like nanoparticle type, size, and shape, volume concentration, fluid temperature, and nanofluid preparation method have effect on thermophysical properties of nanofluids.
*Viscosity of nanofluids
*Density of nanofluids
*Thermal conductivity of nanofluids | 0 | Colloidal Chemistry |
NbCl(dimethoxyethane) has received significant attention as a reagent for reductive coupling of carbonyls and imines. It is sold as a 1,2-dimethoxyethane complex. Nb(III) adducts are also known for 1,4-dioxane and diethyl ether.
Niobium(III) chloride forms a series of compounds with the formula NbClL with Nb=Nb double bond. With tertiary phosphines and arsines, the complexes are edge-share bioctahedra, e.g., NbCl(PPhMe).
Thioethers form adducts with one bridging thioether (RS). These face-sharing bioctahedra have the formula NbX(RS) (X = Cl, Br). | 1 | Solid-state chemistry |
While the Drude-Lorentz model of electrical conductivity makes excellent predictions about the nature of electrons conducting in metals, it can be furthered by using quantum tunnelling to explain the nature of the electron's collisions. When a free electron wave packet encounters a long array of uniformly spaced barriers, the reflected part of the wave packet interferes uniformly with the transmitted one between all barriers so that 100% transmission becomes possible. The theory predicts that if positively charged nuclei form a perfectly rectangular array, electrons will tunnel through the metal as free electrons, leading to extremely high conductance, and that impurities in the metal will disrupt it. | 1 | Solid-state chemistry |
* 1951 - Palladium Medal of the Electrochemical Society
* 1957 - Willis R. Whitney Award, NACE
* 1959 - Wilhelm Exner Medal of the
* 1961 - Bunsen Medal of the German Bunsen Society
* 1964 - of the
* 1972 - Honorary member of the German Bunsen Society
* 1972 - Heyn Medal of the German Society of Metallurgy
* 1973 - Cavallaro Medal, European Federation of Corrosion
* Honorary member of American Institute of Mining, Metallurgical and Petroleum Engineers
* 1973 - Honorary member of the Mathematics and Natural Sciences of the Austrian Academy of Sciences in Vienna
* 1973 - Gold Medal of the American Society for Metals
* 1975 - Honorary Membership of the Japan Institute of Metals
* 1975 - Corresponding member of the | 1 | Solid-state chemistry |
A similar but denser material, consisting of an electrodeposited nanocrystalline nickel layer over a polymeric rapid-prototyped truss, was created by researchers at the University of Toronto in 2008. In 2012, German researchers created a carbon foam known as aerographite, with an even lower density than a metallic microlattice. In 2013, Chinese scientists developed a carbon-based aerogel which was claimed to be lighter still.
Nanolattices like tube-based nanostructures are similar structures on a smaller scale. | 0 | Colloidal Chemistry |
The surfactant group of the taurates was developed by I.G. Farben in Germany (just like the isethionates) and produced under the trade name Igepon at the Hoechst plant. Taurates rapidly spread due to their lime resistance and their oil-removing effect in textile treatment, as detergent raw material and in cosmetics applications. They had a breakthrough in particular because they do not felt wool during washing (as opposed to soap). The production of taurates decreased after the outbreak of the World War II, since only poor quality fatty acids were available due to the fat management. | 0 | Colloidal Chemistry |
A foaming agent is a material such as a surfactant or a blowing agent that facilitates the formation of foam. A surfactant, when present in small amounts, reduces surface tension of a liquid (reduces the work needed to create the foam) or increases its colloidal stability by inhibiting coalescence of bubbles. A blowing agent is a gas that forms the gaseous part of the foam. | 0 | Colloidal Chemistry |
Chintamani Nagesa Ramachandra Rao, (born 30 June 1934), is an Indian chemist who has worked mainly in solid-state and structural chemistry. He has honorary doctorates from 86 universities from around the world and has authored around 1,800 research publications and 56 books. He is described as a scientist who had won all possible awards in his field except the Nobel Prize.
A precocious child, Rao completed BSc from Mysore University at age seventeen, and MSc from Banaras Hindu University at age nineteen. He earned a PhD from Purdue University at the age of twenty-four. He was the youngest lecturer when he joined the Indian Institute of Science in 1959. After a transfer to Indian Institute of Technology Kanpur, he returned to IISc, eventually becoming its Director from 1984 to 1994. He was chair of the Scientific Advisory Council to the Prime Minister of India from 1985 to 1989 and from 2005 to 2014. He founded and works in Jawaharlal Nehru Centre for Advanced Scientific Research and International Centre for Materials Science.
Rao received most important scientific awards and honours including the Marlow Medal, Shanti Swarup Bhatnagar Prize for Science and Technology, Hughes Medal, India Science Award, Dan David Prize, Royal Medal, Von Hippel Award, and ENI award. He also received Padma Shri and Padma Vibhushan from the Government of India. On 16 November 2013, the Government of India selected him for Bharat Ratna, the highest civilian award in India, making him the third scientist after C.V. Raman and A. P. J. Abdul Kalam to receive the award. He received the award on 4 February 2014 from President Pranab Mukherjee at the Rashtrapati Bhavan. | 1 | Solid-state chemistry |
To produce nanolattice materials, polymer templates are manufactured by high-resolution 3D printing processes, such as multiphoton lithography, self-assembly, self-propagating photopolymer waveguides, and direct laser writing techniques. Those methods can synthesize the structure with a unit cell size down to the order of 50 nanometers. Genetic engineering also has the potential in synthesizing nanolattice. Ceramic, metal or composite material nanolattices are formed by post-treatment of the polymer templates with techniques including pyrolysis, atomic layer deposition, electroplating and electroless plating. Pyrolysis, which additionally shrinks the lattices by up to 90%, creates the smallest-size structures, whereby the polymeric template material transforms into carbon, or other ceramics and metals, through thermal decomposition in inert atmosphere or vacuum. | 0 | Colloidal Chemistry |
Metal foams are used for stiffening a structure without increasing its mass. For this application, metal foams are generally closed pore and made of aluminium. Foam panels are glued to the aluminium plate to obtain a resistant composite sandwich locally (in the sheet thickness) and rigid along the length depending on the foam's thickness.
The advantage of metal foams is that the reaction is constant, regardless of the direction of the force. Foams have a plateau of stress after deformation that is constant for as much as 80% of the crushing. | 0 | Colloidal Chemistry |
Czarnik reported the first synthesis of Hexaazatriphenylene Hexanitrile, a hydrogen-free polyfunctional heterocycle with D3h symmetry, in 1986. Because of the properties of this compound, it has found application in the preparation of OLEDs for TV screens and is being investigated for use in improving lithium-ion batteries. | 1 | Solid-state chemistry |
Over the course of his career, Klemm wrote and co-wrote a number of textbooks on inorganic chemistry which became standard textbooks in the field, repeatedly reprinted and translated. These include:
* Klemm, Wilhelm, Anorganische chemie (c1935). Berlin, Leipzig, W. de Gruyter & co.
* Klemm, Wilhelm, Magnetochemie (c1936) Leipzig, Akademische Verlagsgesellschaft m.b.H. Considered a foundational text in magnetochemistry.
* Biltz, Heinrich, Klemm, Wilhelm and Fischer, Werner. Experimentelle Einführung in die anorganische Chemie (1937), Berlin, Leipzig, Walter de Gruyter & Co. An introduction to inorganic chemistry using experimental methods. Beginning with the 21st edition in 1937, Heinrich Biltz was joined by co-authors Wilhelm Klemm and Werner Fischer. Their new version of the textbook became so well known that it was referred to as "BKF". At least 73 editions were published.
* Klemm, Wilhelm, and Hoppe, Rudolf. Anorganische Chemie (c1979). Berlin ; Boston : De Gruyter, c1979. Anorganische Chemie by Klemm and Rudolf Hoppe has been described as a legendary work by two titans of solid state chemistry. | 1 | Solid-state chemistry |
Choy received his B.S. (1971) and M.S. degrees (1973) in chemical engineering from Yonsei University in Seoul. Afterwards he received a diploma in 1975 from the UNESCO postgraduate course in chemistry and chemical engineering, research laboratory of engineering materials, Tokyo Institute of Technology, Japan. He then moved to Germany, where he earned his PhD (1979) in inorganic chemistry at the Ludwig Maximilian University of Munich. | 1 | Solid-state chemistry |
Vinograd obtained his undergraduate degree in chemistry from the University of Minnesota. From 1931 to 1933 he studied colloid chemistry with Professor Herbert Freundlich at the University of Berlin, and from 1933 to 1935 continued his studies with Freundlich at University College, London. In 1936 he went to the University of California, Los Angeles and obtained a Master of Arts degree in organic chemistry with Professor William G. Young. In 1937 he married Sherna Shalett. He obtained his Ph.D. in chemistry in 1940 with Professor James W. McBain at Stanford University with research on physical and colloid chemistry. | 0 | Colloidal Chemistry |
* [https://libserv.aip.org/ipac20/ipac.jsp?session=1668O33395J5H.322504&profile=rev-all&source=~!horizon&view=subscriptionsummary&uri=full=3100006~!44240~!0&ri=32&aspect=subtab232&menu=search&ipp=20&spp=20&staffonly=&term=L%C3%A4rbok+i+Kemien&index=.GW&uindex=&aspect=subtab232&menu=search&ri=32 Lärbok i kemien] (in Swedish). Stockholm, Nordström, 1808-1830.
* [https://libserv.aip.org/ipac20/ipac.jsp?session=1668O33395J5H.322504&menu=search&aspect=power&npp=10&ipp=20&spp=20&profile=rev-all&ri=26&source=%7E%21horizon&index=.GW&term=Tabell%2C+som+utvisar+vigten&x=8&y=8&aspect=power Tabell, som utvisar vigten af större delen vid den oorganiska Kemiens studium märkvärdiga enkla och sammansatta kroppars atomer, jemte deras sammansättning, räknad i procent] (in Swedish). Stockholm : H.A. Nordström, 1818. | 1 | Solid-state chemistry |
*One of the main reactions for industrial production is:
:CaO + 3 BO + 10 Mg → CaB + 10 MgO
Other methods of producing CaB powder include:
*Direct reaction of calcium or calcium oxide and boron at 1000 °C;
:Ca + 6B → CaB
*Reacting Ca(OH) with boron in vacuum at about 1700 °C (carbothermal reduction);
:Ca(OH) +7B → CaB + BO(g) + HO(g)
*Reacting calcium carbonate with boron carbide in vacuum at above 1400 °C (carbothermal reduction)
*Reacting of CaO and HBO and Mg to 1100 °C.
*Low-temperature (500 °C) synthesis
:CaCl + 6NaBH → CaB + 2NaCl + 12H + 4Na
results in relatively poor quality material.
* To produce pure CaB single crystals, e.g., for use as cathode material, the thus obtained CaB powder is further recrystallized and purified with the zone melting technique. The typical growth rate is 30 cm/h and crystal size ~1x10 cm.
*Single-crystal CaB Nanowires (diameter 15–40 nm, length 1–10 micrometres) can be obtained by pyrolysis of diborane (BH) over calcium oxide (CaO) powders at 860–900 °C, in presence of Ni catalyst. | 1 | Solid-state chemistry |
Ex-situ bonding is achieved by gluing face sheets with an aluminium foam by adhesive bonding, brazing or diffusion bonding. Foams used in this method are either closed-cell or open-cell. When a closed-cell foam is used then it is produced from aluminium alloys either by liquid metal route (e.g. Alporas, Cymat) or by powder metallurgy route. Open-cell foam core is made of aluminium and other metals as well. Face sheets are chosen from a variety of aluminium alloy, and other metals such as steel. | 0 | Colloidal Chemistry |
Molecular wires conduct electricity. They typically have non-linear current-voltage characteristics, and do not behave as simple ohmic conductors. The conductance follows typical power law behavior as a function of temperature or electric field, whichever is the greater, arising from their strong one-dimensional character. Numerous theoretical ideas have been used in an attempt to understand the conductivity of one-dimensional systems, where strong interactions between electrons lead to departures from normal metallic (Fermi liquid) behavior. Important concepts are those introduced by Tomonaga, Luttinger and Wigner. Effects caused by classical Coulomb repulsion (called Coulomb blockade), interactions with vibrational degrees of freedom (called phonons) and Quantum Decoherence have also been found to be important in determining the properties of molecular wires. | 1 | Solid-state chemistry |
There are two main types of blowing agents: gases at the temperature that the foam is formed, and gases generated by chemical reaction. Carbon dioxide, pentane, and chlorofluorocarbons are examples of the former. Blowing agents that produce gas via chemical reactions include baking powder, azodicarbonamide, titanium hydride, and isocyanates (when they react with water). | 0 | Colloidal Chemistry |
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxylate (of soap) to bind to calcium and other ions found in hard water. | 0 | Colloidal Chemistry |
Jennifer L. M. Rupp FRSC (born January 27, 1980) is a material scientist and professor at the Technical University of Munich, visiting professor at the Massachusetts Institute of Technology and the CTO for battery research at TUM International Energy Research. Rupp has published more than 130 papers in peer reviewed journals, co-authored 7 book chapters and holds more than 25 patents. Rupp research broadly encompasses solid state materials and cell designs for sustainable batteries, energy conversion and neuromorphic memory and computing. | 1 | Solid-state chemistry |
In rheology, the Farris Effect describes the decrease of the viscosity of a suspension upon increasing the dispersity of the solid additive, at constant volume fraction of the solid additive. That is, that a broader particle size distribution yields a lower viscosity than a narrow particle size distribution, for the same concentration of particles. The phenomenon is names after Richard J. Farris, who modeled the effect. The effect is relevant whenever suspensions are flowing, particularly for suspensions with high loading fractions. Examples include hydraulic fracturing fluids, metal injection molding feedstocks, cosmetics, and various geological processes including sedimentation and lava flows. | 0 | Colloidal Chemistry |
Goodwin won the 2010 Harrison-Meldola Memorial Prize for his work in materials with "negative thermal expansion and in the field of total scattering methods." In 2013, Goodwin won the Marlow Award for his "innovative studies of the physical chemistry and chemical physics of amorphous materials." He won the 2017 Corday-Morgan Prize for his "innovative studies of correlated disorder and its role in functional materials." Goodwin is a 2018 United Kingdom winner of the Blavatnik Award for Young Scientists.
Goodwin received two five-year grants from the European Research Council: an ERC Starting Grant through the 2011 call of the Seventh Framework Program and an ERC Advanced Grant through the 2017 call of the Eighth Framework Program (Horizon 2020).
Goodwin was elected a Fellow of the Royal Society (FRS) in 2023. | 1 | Solid-state chemistry |
can be prepared by multiple methods. Upon heating above 400 °C, nickel powder reacts with oxygen to give . In some commercial processes, green nickel oxide is made by heating a mixture of nickel powder and water at 1000 °C, the rate for this reaction can be increased by the addition of . The simplest and most successful method of preparation is through pyrolysis of nickel(II) compounds such as the hydroxide, nitrate, and carbonate, which yield a light green powder. Synthesis from the elements by heating the metal in oxygen can yield grey to black powders which indicates nonstoichiometry. | 1 | Solid-state chemistry |
Sadoway was born in Toronto, Ontario, Canada. He did both his undergraduate and graduate studies at the University of Toronto, receiving his PhD in 1977. There he focused his studies on chemical metallurgy. He also served on the National Executive of the Ukrainian Canadian Students' Union (SUSK) from 1972 to 1974. In 1977, he received a NATO postdoctoral fellowship from the National Research Council of Canada and came to MIT to conduct his postdoctoral research under Julian Szekely. Sadoway joined the MIT faculty in 1978. On 19 June 2013, Sadoway was awarded an honorary Doctorate of Engineering by the University of Toronto in recognition of his contributions to sustainable energy and sustainable metal production as well as to higher education both in curriculum and in teaching style. In 2014, Sadoway received an honorary doctorate from NTNU, the Norwegian University of Science and Technology. | 1 | Solid-state chemistry |
Soy-derived lecithin is considered by some to be kitniyot and prohibited on Passover for Ashkenazi Jews when many grain-based foods are forbidden, but not at other times. This does not necessarily affect Sephardi Jews, who do not have the same restrictions on rice and kitniyot during Passover.
Muslims are not forbidden to eat lecithin per se; however, since it may be derived from animal as well as plant sources, care must be taken to ensure this source is halal. Lecithin derived from plants and egg yolks is permissible, as is that derived from animals slaughtered according to the rules of dhabihah.
Sunflower lecithin, sourced from the seeds of sunflowers, is entirely plant-based and may be an option for those with religious or cultural concerns regarding food intake. | 0 | Colloidal Chemistry |
FeO is used as a black pigment and is known as C.I pigment black 11 (C.I. No.77499) or Mars Black.
FeO is used as a catalyst in the Haber process and in the water-gas shift reaction. The latter uses an HTS (high temperature shift catalyst) of iron oxide stabilised by chromium oxide. This iron–chrome catalyst is reduced at reactor start up to generate FeO from α-FeO and CrO to CrO.
Bluing is a passivation process that produces a layer of FeO on the surface of steel to protect it from rust. Along with sulfur and aluminium, it is an ingredient in steel-cutting thermite. | 1 | Solid-state chemistry |
The relative permittivity is an essential piece of information when designing capacitors, and in other circumstances where a material might be expected to introduce capacitance into a circuit. If a material with a high relative permittivity is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is commonly used to increase the capacitance of a particular capacitor design. The layers beneath etched conductors in printed circuit boards (PCBs) also act as dielectrics. | 0 | Colloidal Chemistry |
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter). Regulations do not exist for this size class of ambient air pollution particles, which are far smaller than the regulated PM and PM particle classes and are believed to have several more aggressive health implications than those classes of larger particulates.
Although they remain largely unregulated, the World Health Organization has published good practice statements regarding measuring UFPs.
There are two main divisions that categorize types of UFPs. UFPs can either be carbon-based or metallic, and then can be further subdivided by their magnetic properties. Electron microscopy and special physical lab conditions allow scientists to observe UFP morphology. Airborne UFPs can be measured using a condensation particle counter, in which particles are mixed with alcohol vapor and then cooled, allowing the vapor to condense around them, after which they are counted using a light scanner. UFPs are both manufactured and naturally occurring. UFPs are the main constituent of airborne particulate matter. Owing to their large quantity and ability to penetrate deep within the lung, UFPs are a major concern for respiratory exposure and health. | 0 | Colloidal Chemistry |
Titanium foams are characterized structurally by their pore topology (relative percentage of open vs. closed pores), porosity (the multiplicative inverse of relative density), pore size and shape, and anisotropy. Microstructures are most often examined by optical microscopy, scanning electron microscopy and X-ray tomography.
Categorizing titanium foams in terms of pore structure (as either open- or close-celled) is the most basic form of differentiation. In close-celled foams, pores are composed of bubbles entrapped in the metallic solid. These foams consist of a continuous network of sealed pores wherein interconnections between the pores are virtually non-existent. Alternatively, in open-celled foams, the pores are interconnected and solid struts allow fluid to pass through.
Most manufactured foams contain both types of pores, although in many cases the subtype is minimal.
According to the IUPAC, pore sizes are classified into three categories: micro (less than 2 nm), meso (between 2 and 50 nm) and macro (larger than 50 nm) pores. | 0 | Colloidal Chemistry |
Kendrick studied chemistry at the University of Manchester, later moving to University of Aberdeen in Scotland where she earned a master's degree in solid state chemistry. For her doctoral thesis, Kendrick went to Keele University to study low temperature synthetic routes to inorganic pigments. She later did postdoctoral research with Sandra Dann at the Loughborough University, as well as Peter Slater and Saiful Islam at the University of Surrey. | 1 | Solid-state chemistry |
A nearly pure source of calcium carbonate is necessary to refine sugar. It must contain at least 95% calcium carbonate (CaCO) and have a low magnesium content. In addition, the material must meet certain physical requirements so it does not break down when burned. Although caliche does not generally meet all of the requirements for sugar refining, it is used in areas where another source of calcium carbonate, such as limestone, is not present. While caliche requires beneficiation to meet the requirements, its use can still be significantly cheaper than shipping in limestone. | 1 | Solid-state chemistry |
There are two kinds of defects: Equilibrium defects, and Non-Equilibrium defects. Self-assembled structures contain defects. Dislocations caused during the assembling of nanomaterials can majorly affect the final structure and in general defects are never completely avoidable. Current research on defects is focused on controlling defect density.[23] In most cases, the thermodynamic driving force for self-assembly is provided by weak intermolecular interactions and is usually of the same order of magnitude as the entropy term. In order for a self-assembling system to reach the minimum free energy configuration, there has to be enough thermal energy to allow the mass transport of the self-assembling molecules. For defect formation, the free energy of single defect formation is given by:
The enthalpy term, does not necessarily reflect the intermolecular forces between the molecules, it is the energy cost associated with disrupting the pattern and may be thought of as a region where optimum arrangement does not occur and the reduction of enthalpy associated with ideal self-assembly did not occur. An example of this can be seen in a system of hexagonally packed cylinders where defect regions of lamellar structure exist.
If is negative, there will be a finite number of defects in the system and the concentration will be given by:
N is the number of defects in a matrix of N self-assembled particles or features and is the activation energy of defect formation. The activation energy, , should not be confused with . The activation energy represents the energy difference between the initial ideally arranges state and a transition state towards the defective structure. At low defect concentrations, defect formation is entropy driven until a critical concentration of defects allows the activation energy term to compensate for entropy. There is usually an equilibrium defect density indicated at the minimum free energy. The activation energy for defect formation increases this equilibrium defect density. | 0 | Colloidal Chemistry |
A well dispersed colloidal suspension consists of individual, separated particles and is stabilized by repulsive inter-particle forces. When the repulsive forces weaken or become attractive through the addition of a coagulant, particles start to aggregate. Initially, particle doublets A will form from singlets A according to the scheme
In the early stage of the aggregation process, the suspension mainly contains individual particles. The rate of this phenomenon is characterized by the aggregation rate coefficient . Since doublet formation is a second order rate process, the units of this coefficients are ms since particle concentrations are expressed as particle number per unit volume (m). Since absolute aggregation rates are difficult to measure, one often refers to the dimensionless stability ratio , defined as where is the aggregation rate coefficient in the fast regime, and the coefficient at the conditions of interest. The stability ratio is close to unity in the fast regime, increases in the slow regime, and becomes very large when the suspension is stable.
Often, colloidal particles are suspended in water. In this case, they accumulate a surface charge and an electrical double layer forms around each particle. The overlap between the diffuse layers of two approaching particles results in a repulsive double layer interaction potential, which leads to particle stabilization. When salt is added to the suspension, the electrical double layer repulsion is screened, and van der Waals attraction become dominant and induce fast aggregation. The figure on the right shows the typical dependence of the stability ratio versus the electrolyte concentration, whereby the regimes of slow and fast aggregation are indicated.
The table below summarizes the critical coagulation concentration (CCC) ranges for different net charge of the counter ion.
The charge is expressed in units of elementary charge. This dependence reflects the Schulze–Hardy rule, which states that the CCC varies as the inverse sixth power of the counter ion charge. The CCC also depends on the type of ion somewhat, even if they carry the same charge. This dependence may reflect different particle properties or different ion affinities to the particle surface. Since particles are frequently negatively charged, multivalent metal cations thus represent highly effective coagulants.
Adsorption of oppositely charged species (e.g., protons, specifically adsorbing ions, surfactants, or polyelectrolytes) may destabilize a particle suspension by charge neutralization or stabilize it by buildup of charge, leading to a fast aggregation near the charge neutralization point, and slow aggregation away from it.
Quantitative interpretation of colloidal stability was first formulated within the DLVO theory. This theory confirms the existence slow and fast aggregation regimes, even though in the slow regime the dependence on the salt concentration is often predicted to be much stronger than observed experimentally. The Schulze–Hardy rule can be derived from DLVO theory as well.
Other mechanisms of colloid stabilization are equally possible, particularly, involving polymers. Adsorbed or grafted polymers may form a protective layer around the particles, induce steric repulsive forces, and lead to steric stabilization at it is the case with polycarboxylate ether (PCE), the last generation of chemically tailored superplasticizer specifically designed to increase the workability of concrete while reducing its water content to improve its properties and durability. When polymers chains adsorb to particles loosely, a polymer chain may bridge two particles, and induce bridging forces. This situation is referred to as bridging flocculation.
When particle aggregation is solely driven by diffusion, one refers to perikinetic aggregation. Aggregation can be enhanced through shear stress (e.g., stirring). The latter case is called orthokinetic aggregation. | 0 | Colloidal Chemistry |
Quick clay is found only in countries close to the north pole, such as Russia; Canada; Norway; Sweden; and Finland; and in Alaska, United States; since they were glaciated during the Pleistocene epoch. In Canada, the clay is associated primarily with the Pleistocene-era Champlain Sea, in the modern Ottawa Valley, the St. Lawrence Valley, and the Saguenay River regions.
Quick clay has been the underlying cause of many deadly landslides. In Canada alone, it has been associated with more than 250 mapped landslides. Some of these are ancient, and may have been triggered by earthquakes. | 0 | Colloidal Chemistry |
She graduated from Bronx High School of Science in New York. She received B.S. (1963), M.S. (1964), and Ph.D. (1967) in physical chemistry from University of Chicago, where she studied with Ole J. Kleppa. | 1 | Solid-state chemistry |
From spectra with rotational resolution, moments of inertia and hence bond lengths and angles can be determined "directly" (at least in principle). From less well-resolved spectra one can still determine important quantities like JT stabilization energies and energy barriers (e.g. to pseudorotation). However, in the whole spectral intensity distribution of an electronic transition more information is encoded. It has been used to decide on the presence (or absence) of the geometric phase which is accumulated during the pseudorotational motion around the JT (or other type of) conical intersection. Prominent examples of either type are the ground (X) or an excited (B) state of Na. The Fourier transform of , the so-called autocorrelation function reflects the motion of the wavepacket after an optical (= vertical) transition to the APES of the final electronic state. Typically it will move on the timescale of a vibrational period which is (for small molecules) of the order of 5–50 fs, i.e. ultrafast. Besides a nearly periodic motion, mode–mode interactions with very irregular (also chaotic) behaviour and spreading of the wavepacket may also occur. Near a conical intersection this will be accompanied/complemented by nonradiative transitions (termed internal conversion) to other APESs occurring on the same ultrafast time scale.
For the JT case the situation is somewhat special, as compared to a general conical intersection, because the different JT potential sheets are symmetry-related to each other and have (exactly or nearly) the same energy minimum. The "transition" between them is thus more oscillatory than one would normally expect, and their time-averaged populations are close to 1/2. For a more typical scenario a more general conical intersection is "required".
The JT effect still comes into play, namely in combination with a different nearby, in general non-degenerate electronic state. The result is a pseudo Jahn–Teller effect, for example, of an E state interacting with an A state. This situation is common in JT systems, just as interactions between two nondegenerate electronic states are common for non-JT systems. Examples are excited electronic states of NH and the benzene radical cation. Here, crossings between the E and A state APESs amount to triple intersections, which are associated with very complex spectral features (dense line structures and diffuse spectral envelopes under low resolution). The population transfer between the states is also ultrafast, so fast that fluorescence (proceeding on a nanosecond time scale) cannot compete. This helps to understand why the benzene cation, like many other organic radical cation, does not fluoresce.
To be sure, photochemical reactivity emerges when the internal conversion makes the system explore the nuclear configuration space such that new chemical species are formed. There is a plethora of femtosecond pump-probe spectroscopic techniques to reveal details of these processes occurring, for example, in the process of vision. | 1 | Solid-state chemistry |
Tripotassium phosphate has few industrial applications.
It is used as an inert, easily removed proton acceptor in organic synthesis. Some of the reactions are listed below:
# The hydrate () has been used to catalyze the deprotection of BOC amines. Microwave radiation is used to aid the reaction.
# As a catalyst for the synthesis of unsymmetrical diaryl ethers using [Bmim] as the solvent. Aryl methane-sulfonates are deprotected and then followed by a nucleophilic aromatic substitution (SAr) with activated aryl halides.
# As a base in the cross-coupling reaction of aryl halides with terminal alkynes. It also plays a role in the deacetonation of 4-aryl-2-methylbut-3-yn-2-ol intermediates.
# As the base in the cross-coupling reaction between aryl halides and phenols or aliphatic alcohols. | 0 | Colloidal Chemistry |
On passive margins where salt is present, such as the Gulf of Mexico, salt tectonics largely control the evolution of deep-water sedimentary systems; for example submarine channels, as modern and ancient case studies show. | 1 | Solid-state chemistry |
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
Nanoparticles are distinguished from microparticles (1-1000 µm), "fine particles" (sized between 100 and 2500 nm), and "coarse particles" (ranging from 2500 to 10,000 nm), because their smaller size drives very different physical or chemical properties, like colloidal properties and ultrafast optical effects or electric properties.
Being more subject to the Brownian motion, they usually do not sediment, like colloidal particles that conversely are usually understood to range from 1 to 1000 nm.
Being much smaller than the wavelengths of visible light (400-700 nm), nanoparticles cannot be seen with ordinary optical microscopes, requiring the use of electron microscopes or microscopes with laser. For the same reason, dispersions of nanoparticles in transparent media can be transparent, whereas suspensions of larger particles usually scatter some or all visible light incident on them. Nanoparticles also easily pass through common filters, such as common ceramic candles, so that separation from liquids requires special nanofiltration techniques.
The properties of nanoparticles often differ markedly from those of larger particles of the same substance. Since the typical diameter of an atom is between 0.15 and 0.6 nm, a large fraction of the nanoparticle's material lies within a few atomic diameters of its surface. Therefore, the properties of that surface layer may dominate over those of the bulk material. This effect is particularly strong for nanoparticles dispersed in a medium of different composition since the interactions between the two materials at their interface also becomes significant.
Nanoparticles occur widely in nature and are objects of study in many sciences such as chemistry, physics, geology, and biology. Being at the transition between bulk materials and atomic or molecular structures, they often exhibit phenomena that are not observed at either scale. They are an important component of atmospheric pollution, and key ingredients in many industrialized products such as paints, plastics, metals, ceramics, and magnetic products. The production of nanoparticles with specific properties is a branch of nanotechnology.
In general, the small size of nanoparticles leads to a lower concentration of point defects compared to their bulk counterparts, but they do support a variety of dislocations that can be visualized using high-resolution electron microscopes. However, nanoparticles exhibit different dislocation mechanics, which, together with their unique surface structures, results in mechanical properties that are different from the bulk material.
Non-spherical nanoparticles (e.g., prisms, cubes, rods etc.) exhibit shape-dependent and size-dependent (both chemical and physical) properties (anisotropy). Non-spherical nanoparticles of gold (Au), silver (Ag), and platinum (Pt) due to their fascinating optical properties are finding diverse applications. Non-spherical geometries of nanoprisms give rise to high effective cross-sections and deeper colors of the colloidal solutions. The possibility of shifting the resonance wavelengths by tuning the particle geometry allows using them in the fields of molecular labeling, biomolecular assays, trace metal detection, or nanotechnical applications. Anisotropic nanoparticles display a specific absorption behavior and stochastic particle orientation under unpolarized light, showing a distinct resonance mode for each excitable axis. | 0 | Colloidal Chemistry |
Schmalzried received his diploma (with a diploma thesis on the fluorescence of benzopyrene) from Theodor Förster at the University of Stuttgart and received his doctorate in 1958 at the Roentgen Institute of the University of Stuttgart with Richard Glocker (1890-1978) and was a postdoc with Carl Wagner at the Max Planck Institute for Biophysical Chemistry in Göttingen, a pioneer in solid state chemistry. He habilitated in 1966 at the Leibniz University Hannover on the topic of disorder in ternary ionic crystals. In 1966, he became a full professor at the Technical University of Clausthal and in 1975 at the Leibniz University Hannover. He was Courtesy Professor at Cornell University and Schottky Professor at Stanford University.
He wrote two textbooks on chemical reactions in solids, which were internationally standard works. He also dealt with thermodynamics of solids and electrochemistry. His group worked closely with Alan Lidiard's group in England. | 1 | Solid-state chemistry |
Particle size is a notion introduced for comparing dimensions of solid particles (flecks), liquid particles (droplets), or gaseous particles (bubbles). The notion of particle size applies to particles in colloids, in ecology, in granular material (whether airborne or not), and to particles that form a granular material (see also grain size). | 0 | Colloidal Chemistry |
Two explosives HMX and CL-20 cocrystallized in a ratio 1:2 to form a hybrid explosive. This explosive had the same low sensitivity of HMX and nearly the same explosive power of CL-20. Physically mixing explosives creates a mixture that has the same sensitivity as the most sensitive component, which cocrystallisation overcomes. | 1 | Solid-state chemistry |
Nanogeoscience is the study of nanoscale phenomena related to geological systems. Predominantly, this is investigated by studying environmental nanoparticles between 1–100 nanometers in size. Other applicable fields of study include studying materials with at least one dimension restricted to the nanoscale (e.g. thin films, confined fluids) and the transfer of energy, electrons, protons, and matter across environmental interfaces. | 0 | Colloidal Chemistry |
Depletion forces have been observed and measured using a variety of instrumentation including atomic force microscopy, optical tweezers, and hydrodynamic force balance machines. | 0 | Colloidal Chemistry |
Air or other gas dissolved in the fluid it can come out of solution as small bubbles (entrained air). If these small bubbles have sufficient buoyancy, they can rise to the surface and together form foam. Mechanical factors that may generate entrapped air:
* Leaky seals on pumps
* High pressure pumps
* Poor system design (tank, pump inlet, outlet and manifold design)
* Pressure release | 0 | Colloidal Chemistry |
The compressive properties of syntactic foams, in most cases, strongly depend on the properties of the filler particle material. In general, the compressive strength of the material is proportional to its density. Cementitious syntactic foams are reported to achieve compressive strength values greater than while maintaining densities lower than .
The matrix material has more influence on the tensile properties. Tensile strength may be highly improved by a chemical surface treatment of the particles, such as silanization, which allows the formation of strong bonds between glass particles and epoxy matrix. Addition of fibrous materials can also increase the tensile strength. | 0 | Colloidal Chemistry |
Omar M. Yaghi (; born February 9, 1965) is the James and Neeltje Tretter Chair Professor of Chemistry at the University of California, Berkeley, an affiliate scientist at Lawrence Berkeley National Laboratory, the Founding Director of the Berkeley Global Science Institute, and an elected member of the US National Academy of Sciences as well as the German National Academy of Sciences Leopoldina. | 1 | Solid-state chemistry |
Gerard Férey was a lecturer at the University of Maine. In 1968, he founded the Department of Chemistry at the University Institutes of Technology of Le Mans. He argued his doctoral thesis at the Pierre-and-Marie-Curie University in 1977.
He was a teacher at the University of Maine from 1981 to 1996 and then at the Versailles Saint-Quentin-en-Yvelines University since that date, where he founded the Lavoisier Institute. From 1988 to 1992 he was deputy director of the Department of Chemistry at the French National Centre for Scientific Research.
He was elected to the French Academy of Sciences 18 November 2003. In 2007, he was Vice-President of the Société Chimique de France. He was a member of the Institut Universitaire de France. He was also at the initiative of the Chemistry Ambition, a group that includes seven players in chemistry of France aimed at enhancing the image of the discipline to the public. | 1 | Solid-state chemistry |
In 2017, the European Food Safety Authority concluded that betaine was safe "as a novel food to be used at a maximum intake level of 6 mg/kg body weight per day in addition to the intake from the background diet." | 0 | Colloidal Chemistry |
The total intensive potential energy of an ion in the lattice can therefore be expressed as the sum of the Madelung and repulsive potentials:
Minimizing this energy with respect to r yields the equilibrium separation r in terms of the unknown constant B:
Evaluating the minimum intensive potential energy and substituting the expression for B in terms of r yields the Born–Landé equation: | 1 | Solid-state chemistry |
After graduation, Ibers accepted a staff scientist position at Shell Development Company and later Brookhaven National Laboratory. Starting in 1965 until his retirement, Ibers was a professor of chemistry at Northwestern University. His broad research interests included many aspects of organometallic, bioinorganic, and solid state chemistry,. Ibers was a noted pioneer in the applications of X-Ray Crystallography to chemical problems and issues associated with inorganic bonding. | 1 | Solid-state chemistry |
Magnesium diborides superconducting properties were discovered in 2001. Its critical temperature (T') of is the highest amongst conventional superconductors. Among conventional (phonon-mediated) superconductors, it is unusual. Its electronic structure is such that there exist two types of electrons at the Fermi level with widely differing behaviours, one of them (sigma-bonding) being much more strongly superconducting than the other (pi-bonding). This is at odds with usual theories of phonon-mediated superconductivity which assume that all electrons behave in the same manner. Theoretical understanding of the properties of MgB has nearly been achieved by modelling two energy gaps. In 2001 it was regarded as behaving more like a metallic than a cuprate superconductor. | 1 | Solid-state chemistry |