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SP-D is a type of lectin, more specifically they are a collagen-containing C-type (calcium dependent) lectin which are named collectins. The collectins are responsible for immune and inflammatory control. They have a very basic structure,
* triple-helical collagen region
* C-terminal homotrimeric lectin or carbohydrate recognition domain (CRD).
SP-D is actually a monomer, these monomers assist in high affinity saccharide binding. Three of the same type of monomers associate to form a homotrimer.
SP-D has a complex quaternary structure in which monomers (43 kDa) are assembled into tetramers of trimers thus forming dodecamers. Dodecamers are further assembled into large multimeric structures. The oligomerization of SP-D results in the burial of the tail domains while the head domains are exposed. Oligomerization is dependent upon the cysteine residues at positions 15 and 20 within the N-terminal tail region. | 0 | Colloidal Chemistry |
In December, 2023, as part of a four-year legal battle, the EPA banned Inhance -- a Houston, Texas-based manufacturer that produces an estimated 200m containers annually with a process that creates, among other chemicals, PFOA -- from using the manufacturing process. In March, 2024, the Fifth Circuit federal appeals court overturned the ban. While the court did not deny the containers’ health risks, it said that the EPA could not regulate the manufactured containers under the statute it used. | 0 | Colloidal Chemistry |
Copper(II) chloride is prepared commercially by the action of chlorination of copper. Copper at red heat (300-400°C) combines directly with chlorine gas, giving (molten) copper(II) chloride. The reaction is very exothermic.
A solution of copper(II) chloride is commercially produced by adding chlorine gas to a circulating mixture of hydrochloric acid and copper. From this solution, the dihydrate can be produced by evaporation.
Although copper metal itself cannot be oxidized by hydrochloric acid, copper-containing bases such as the hydroxide, oxide, or copper(II) carbonate can react to form in an acid-base reaction which can subsequently be heated above to produce the anhydrous derivative.
Once prepared, a solution of may be purified by crystallization. A standard method takes the solution mixed in hot dilute hydrochloric acid, and causes the crystals to form by cooling in a calcium chloride () ice bath.
There are indirect and rarely used means of using copper ions in solution to form copper(II) chloride. Electrolysis of aqueous sodium chloride with copper electrodes produces (among other things) a blue-green foam that can be collected and converted to the hydrate. While this is not usually done due to the emission of toxic chlorine gas, and the prevalence of the more general chloralkali process, the electrolysis will convert the copper metal to copper ions in solution forming the compound. Indeed, any solution of copper ions can be mixed with hydrochloric acid and made into a copper chloride by removing any other ions. | 1 | Solid-state chemistry |
A. P. B. Sinha, born on 27 December 1928, joined the University of London from where he secured a PhD in 1954; his thesis was based on solid state chemistry. Later, he served the National Chemical Laboratory, Pune as a directors grade scientist and headed the Physical Chemistry division of the institution. Continuing his researches on solid state chemistry, Sinha studied low mobility semiconductors with respect to its electron transport and crystal distortions caused by electron lattice transitions, switching, magnetic ordering and memory effects. He is known to have synthesized new manganites and reportedly developed a number of solid state products such as thermistors, photocells, magnets and photovoltaic products. Based on his studies on electron lattice interaction, Sinha proposed support theories for the ferroelectricity theory and developed new theories on the thermoelectrical power and mobility in semiconductors. His researches are reported to have widened the understanding of conduction in semiconductors. The body of his literary work is composed of one book, Spectroscopy in inorganic chemistry, chapters to the book, A study of the growth and structure of layers of oxides, sulphides and related compounds, with special reference to the effect of temperature', edited by C. N. R. Rao, and several articles published in peer reviewed journals. His work has been cited by several authors.
Sinha was associated with journals such as Bulletin Materials Science and Indian Journal of Pure Applied Physics as a member of their editorial boards. The Council of Scientific and Industrial Research awarded him the Shanti Swarup Bhatnagar Prize, one of the highest Indian science awards, in 1972. Sinha was elected by the Indian Academy of Sciences as their fellow in 1974 before he became an elected fellow of the Indian National Science Academy in 1978. He is also an elected fellow of the Maharashtra Academy of Sciences and a recipient of the Meritorious Invention Award of the National Research Development Corporation which he received in 1978. After his stint at NCL, Sinha migrated to the US and is associated with the Morris Innovative Research.
Sinha died in the United States on 4 July 2021, at the age of 93. | 1 | Solid-state chemistry |
Composite metal foam is made from a combination of homogeneous hollow metal spheres with a metallic matrix surrounding the spheres. This closed-cell metal foam isolates the pockets of air within and can be made out of nearly any metal, alloy, or combination. The sphere sizes can be varied and fine-tuned per application. The mixture of air-filled hollow metal spheres and a metallic matrix provides both light weight and strength. The spheres are randomly arranged inside the material but most often resembles a simple cubic or body-centered cubic structure. CMF is made out of about 70% air and thus, weighs 70% less than an equal volume of the solid parent material. Composite metal foam is the strongest metal foam available with a 5-6 times greater strength to density ratio and over 7 times greater energy absorption capability than previous metal foams. CMF was developed at North Carolina State University by the inventor Afsaneh Rabiei with four patents in her name, all entitled "Composite Metal Foam and Method of Preparation Thereof" (US Utility Patents 9208912, 8110143, 8105696, 7641984), and CMF is currently proprietary technology owned by the company Advanced Materials Manufacturing. | 0 | Colloidal Chemistry |
The system of colloids and depletants in solution is typically modeled by treating the large colloids and small depletants as dissimilarly sized hard spheres. Hard spheres are characterized as non-interacting and impenetrable spheres. These two fundamental properties of hard spheres are described mathematically by the hard-sphere potential. The hard-sphere potential imposes steric constraint around large spheres which in turn gives rise to excluded volume, that is, volume that is unavailable for small spheres to occupy. | 0 | Colloidal Chemistry |
Magnetoelastic filaments are one-dimensional composite structures that exhibit both magnetic and elastic properties. Interest in these materials tends to focus on the ability to precisely control mechanical events using an external magnetic field. Like piezoelectricity materials, they can be used as actuators, but do not need to be physically connected to a power source. The conformations adopted by magnetoelastic filaments are dictated by the competition between its elastic and magnetic properties. | 0 | Colloidal Chemistry |
Estropipate is a prodrug of estrone and estradiol. Hence, it is an estrogen, or an agonist of the estrogen receptors. | 1 | Solid-state chemistry |
Some inorganic selenide sulfide compounds are also known. Simplest is the material selenium sulfide, which has medicinal properties. It adopt the diverse structures of elemental sulfur but with some S atoms replaced by Se.
Other inorganic selenide sulfide compounds occur as minerals and as pigments. One example is antimony selenosulfide.
The pigment cadmium red consists of cadmium sulfoselenide. It is a solid solution of cadmium sulfide, which is yellow, and cadmium selenide, which is dark brown. It is used as an artist's pigment. Unlike the organic selenosulfides and unlike selenide sulfide itself, no S-Se bond exists in CdSSe or in SbSSe. | 1 | Solid-state chemistry |
In all of the typical emulsions, there are tiny particles (discrete phase) suspended in a liquid (continuous phase). In an oil-in-water emulsion, oil is the discrete phase, while water is the continuous phase.
What the Bancroft rule states is that contrary to common sense, what makes an emulsion oil-in-water or water-in-oil is not the relative percentages of oil or water, but which phase the emulsifier is more soluble in. So even though there may be a formula that's 60% oil and 40% water, if the emulsifier chosen is more soluble in water, it will create an oil-in-water system.
There are some exceptions to Bancrofts rule, but its a very useful rule of thumb for most systems.
The hydrophilic-lipophilic balance (HLB) of a surfactant can be used in order to determine whether it's a good choice for the desired emulsion or not.
*In oil-in-water emulsions – use emulsifying agents that are more soluble in water than in oil (High HLB surfactants).
*In water-in-oil emulsions – use emulsifying agents that are more soluble in oil than in water (Low HLB surfactants).
Bancroft's rule suggests that the type of emulsion is dictated by the emulsifier and that the emulsifier should be soluble in the continuous phase. This empirical observation can be rationalized by considering the interfacial tension at the oil-surfactant and water-surfactant interfaces. | 0 | Colloidal Chemistry |
He was born in Durban, South Africa, although his parents returned to England soon afterwards. He was educated at Thetford Grammar School and Ipswich School and went on to study chemistry at Lincoln College, Oxford, gaining a doctorate at the university's Engineering Laboratory. | 0 | Colloidal Chemistry |
Until recently, clinical uses for aquasomes were primarily for targeted drug delivery of general treatment drugs. Additional applications have been since explored, including delivery of antigen, insulin, hemoglobin, and vaccines. | 0 | Colloidal Chemistry |
There are a number of types of pulmonary surfactants available. Ex-situ measurements of surface tension and interfacial rheology can help to understand the functionality of pulmonary surfactants.
Synthetic pulmonary surfactants
# Colfosceril palmitate (Exosurf) - a mixture of DPPC with hexadecanol and tyloxapol added as spreading agents
# Pumactant (Artificial Lung Expanding Compound or ALEC) - a mixture of DPPC and PG
# KL-4 - composed of DPPC, palmitoyl-oleoyl phosphatidylglycerol, and palmitic acid, combined with a 21 amino acid synthetic peptide that mimics the structural characteristics of SP-B.
# Venticute - DPPC, PG, palmitic acid and recombinant SP-C
# Lucinactant - DPPC, POPG, and palmitic acid.
Animal derived surfactants
# Beractant
## (Alveofact) - extracted from cow lung lavage fluid
## (Survanta) - extracted from minced cow lung with additional DPPC, palmitic acid, and tripalmitin
##(Beraksurf) -extracted from minced calf lung with additional DPPC, palmitic acid, and tripalmitin
# Calfactant (Infasurf) - extracted from calf lung lavage fluid
# Poractant alfa (Curosurf) - extracted from material derived from minced pig lung
# Ovinactant (Varasurf) - extracted from material derived from minced sheep lung | 0 | Colloidal Chemistry |
Cocrystal engineering has become of such great importance in the field of pharmaceuticals that a particular subdivision of multicomponent cocrystals has been given the term pharmaceutical cocrystals to refer to a solid cocrystal former component and a molecular or ionic API (active pharmaceutical ingredient). However, other classifications also exist when one or more of the components are not in solid form under ambient conditions. For example, if one component is a liquid under ambient conditions, the cocrystal might actually be deemed a cocrystal solvate as discussed previously. The physical states of the individual components under ambient conditions is the only source of division among these classifications. The classification naming scheme of the cocrystals might seem to be of little importance to the cocrystal itself, but in the categorization lies significant information regarding the physical properties, such as solubility and melting point, and the stability of APIs.
The objective for pharmaceutical cocrystals is to have properties that differ from that expected of the pure APIs without making and/or breaking covalent bonds.
Among the earliest pharmaceutical cocrystals reported are of sulfonamides. The area of pharmaceutical cocrystals has thus increased on the basis of interactions between APIs and cocrystal formers. Most commonly, APIs have hydrogen-bonding capability at their exterior which makes them more susceptible to polymorphism, especially in the case of cocrystal solvates which can be known to have different polymorphic forms. Such a case is in the drug sulfathiazole, a common oral and topical antimicrobial, which has over a hundred different solvates. It is thus important in the field of pharmaceuticals to screen for every polymorphic form of a cocrystal before it is considered as a realistic improvement to the existing API. Pharmaceutical cocrystal formation can also be driven by multiple functional groups on the API, which introduces the possibility of binary, ternary, and higher ordered cocrystal forms. Nevertheless, the cocrystal former is used to optimize the properties of the API but can also be used solely in the isolation and/or purification of the API, such as a separating enantiomers from each other, as well and removed preceding the production of the drug.
It is with reasoning that the physical properties of pharmaceutical cocrystals could then ultimately change with varying amounts and concentrations of the individual components. One of the most important properties to change with varying the concentrations of the components is solubility. It has been shown that if the stability of the components is less than the cocrystal formed between them, then the solubility of the cocrystal will be lower than the pure combination of the individual constituents. If the solubility of the cocrystal is lower, this means that there exists a driving force for the cocrystallization to occur. Even more important for pharmaceutical applications is the ability to alter the stability to hydration and bioavailability of the API with cocrystal formation, which has huge implications on drug development. The cocrystal can increase or decrease such properties as melting point and stability to relative humidity compared to the pure API and therefore, must be studied on a case to case basis for their utilization in improving a pharmaceutical on the market.
A screening procedure has been developed to help determine the formation of cocrystals from two components and the ability to improve the properties of the pure API. First, the solubilities of the individual compounds are determined. Secondly, the cocrystallization of the two components is evaluated. Finally, phase diagram screening and powder X-ray diffraction (PXRD) are further investigated to optimize conditions for cocrystallization of the components. This procedure is still done to discover cocrystals of pharmaceutical interest including simple APIs, such as carbamazepine (CBZ), a common treatment for epilepsy, trigeminal neuralgia, and bipolar disorder. CBZ has only one primary functional group involved in hydrogen bonding, which simplifies the possibilities of cocrystal formation that can greatly improve its low dissolution bioavailability.
Another example of an API being studied would be that of Piracetam, or (2-oxo-1-pyrrolidinyl)acetamide, which is used to stimulate the central nervous system and thus, enhance learning and memory. Four polymorphs of Piracetam exist that involve hydrogen bonding of the carbonyl and primary amide. It is these same hydrogen bonding functional groups that interact with and enhance the cocrystallization of Piracetam with gentisic acid, a non-steroidal anti-inflammatory drug (NSAID), and with p-hydroxybenzoic acid, an isomer of the aspirin precursor salicylic acid. No matter what the API is that is being researched, it is quite evident of the wide applicability and possibility for constant improvement in the realm of drug development, thus making it clear that the driving force of cocrystallization continues to consist of attempting to improve on the physical properties in which the existing cocrystals are lacking. | 1 | Solid-state chemistry |
Bulk samples can be prepared by heating indium(III) hydroxide or the nitrate, carbonate or sulfate.
Thin films of indium oxide can be prepared by sputtering of indium targets in an argon/oxygen atmosphere. They can be used as diffusion barriers ("barrier metals") in semiconductors, e.g. to inhibit diffusion between aluminium and silicon.
Monocrystalline nanowires can be synthesized from indium oxide by laser ablation, allowing precise diameter control down to 10 nm. Field effect transistors were fabricated from those. Indium oxide nanowires can serve as sensitive and specific redox protein sensors. The sol–gel method is another way to prepare nanowires.
Indium oxide can serve as a semiconductor material, forming heterojunctions with p-InP, n-GaAs, n-Si, and other materials. A layer of indium oxide on a silicon substrate can be deposited from an indium trichloride solution, a method useful for manufacture of solar cells. | 1 | Solid-state chemistry |
The degree of homogeneity in pore distribution of the final product is primarily dependent on the adequacy of mixing of the precursor. The difference in particle size between the titanium powders and the spacers directly impacts the ability to adequately mix the preform. The greater the size difference, the more difficult it is to control this process. Nonhomogeneous mixing resulting from the use of spacers considerably larger than the titanium particles employed and has shown adverse effects in the stability of the precursor after removal of spacer and in the distribution of porosity.
Spacer size has been investigated. It was shown that the use of a coarse spacer results in thicker pore walls while the use of finer spacers results in enhanced compaction, leading to increased densification. Increased densification is evidenced by a monomodal pore distribution with the employment of fine spacers and a bimodal distribution using coarse spacers. Further, finer spacers result in a more homogeneous pore distribution. Sharma et al. utilized acicular spacers and achieved porosities up to 60% where pores were undistorted. In samples employing fine particles, porosities up to 70% were achievable before noting distortion in the pores. However, the bimodal pore distribution observed in coarse-spacer samples showed to be beneficial in terms of mechanical properties in that higher compressive strengths were observed, beyond those that might exist due to the inverse relationship of porosity and compressive strength alone. | 0 | Colloidal Chemistry |
Dr Mukherjee was able to foresee how basic soil colloid studies could be of help in understanding many of the soil properties and problems. He brought to use in
the study of the soil all the tools and techniques he had been developing and improving through years of patient research. In 1942, with N.C. Sen Gupta, he developed a
simple rotary viscometer for the study of anomalous viscous properties. In 1944, he developed the method of differentiation of crude oils based on chromatography capillary analysis and fluorescence in UV light. | 0 | Colloidal Chemistry |
A very unusual situation occurs in a compound dubbed "inverse sodium hydride", which contains H and Na ions. Na is an alkalide, and this compound differs from ordinary sodium hydride in having a much higher energy content due to the net displacement of two electrons from hydrogen to sodium. A derivative of this "inverse sodium hydride" arises in the presence of the base [[adamanzane|[3]adamanzane]]. This molecule irreversibly encapsulates the H and shields it from interaction with the alkalide Na. Theoretical work has suggested that even an unprotected protonated tertiary amine complexed with the sodium alkalide might be metastable under certain solvent conditions, though the barrier to reaction would be small and finding a suitable solvent might be difficult. | 1 | Solid-state chemistry |
Indian Salt Service is a Central Engineering Service of the Government of India. Under the administrative control of the Ministry of Commerce and Industry, it is one of the smallest Central services under the Government of India. | 1 | Solid-state chemistry |
In chemistry, molybdenum bronze is a generic name for certain mixed oxides of molybdenum with the generic formula where A may be hydrogen, an alkali metal cation (such as Li, Na, K), and Tl. These compounds form deeply coloured plate-like crystals with a metallic sheen, hence their name. These bronzes derive their metallic character from partially occupied 4d bands. The oxidation states in KMoO are K, O, and Mo. MoO is an insulator, with an unfilled 4d band.
These compounds have been much studied since the 1980s due to their markedly anisotropic electrical properties, reflecting their layered structure. The electrical resistivity can vary considerably depending on the direction, in some cases by 200:1 or more. They are generally non-stoichiometric compounds. Some are metals and some are semiconductors. | 1 | Solid-state chemistry |
In chemistry, a selenosulfide refers to distinct classes of inorganic and organic compounds containing sulfur and selenium. The organic derivatives contain Se-S bonds, whereas the inorganic derivatives are more variable. | 1 | Solid-state chemistry |
Gibson & Ashby micromechanical models for porous materials provide mathematical equations for the prediction of mechanical parameters based on experimentally determined geometric constants. The constants of proportionality are determined by fitting experimental data to various mathematical models for structures consisting of cubes and solid struts and are dependent upon cell geometry. A limitation of the Gibson & Ashby model is that it is most accurate for foams exhibiting porosities higher than 70%, although experimental comparisons for lower porosity foams have shown agreement with this model. Ye & Dunand found reasonable agreement to the Gibson & Ashby model for titanium foams exhibiting 42% porosity. Ultrasonic measurements provided an average Young's modulus value of 39 GPa, which is in relatively good agreement with the Gibson & Ashby prediction of 35 GPa.
The Gibson & Ashby models assume ideal structures; microstructural irregularities (e.g. inhomogeneous pore distribution; defects) are not considered. Additionally, experimental results from which the predetermined proportionality constants were based on experimental values that were obtained from simple compression tests. Consequently, they may not be applicable for multiaxial loads. | 0 | Colloidal Chemistry |
Biomedical implants should have low density for patient comfort and high porosity and surface area to facilitate vascularization and the ingrowth of new bone. Ideally, the implant will allow sufficiently easy fluid flow for cell nutrition and osteoblast multiplication as well as migration for cellular colonization of the implant to become uniform. The pores contained within the foam's cellular matrix mimic the extracellular matrix of bone, allowing the body to fixate with the implant. The porosity of the implant also promotes apposition and facilitates vascularization−as cells are able to attach, reproduce and form basic functions. It has been shown that a macropore size of 200–500 µm is preferred for ingrowths of new bone tissues and transportation of body fluids. The lower bound is controlled by the size of cells (~20 µm), and the upper bound is related to the specific surface area through the availability of binding sites. Finer pores further help in tissue growth and biofluid movement. Anisotropic, elongated pores (such as those attainable via the freeze-casting technique) may be beneficial in bone implants in that they can further mimic the structure of bone.
The porous surface geometry of the foam promotes bone in-growth, provides anchorage for fixation, and ensures stresses are transferred from the implant to the bone. Surface roughness in the pore can enhance bone in-growth, and coarser cell size facilitates faster tissue growth.
To optimize the implants functionality and ability to successfully fuse with bone, it may be necessary to manipulate the materials manufacturing methods in order to modify the foam's pore structure. Changes in pore structure can directly influence implant strength as well as other key properties. | 0 | Colloidal Chemistry |
Richard B. Kaner is an American synthetic inorganic chemist. He is a distinguished professor and the Dr. Myung Ki Hong Endowed Chair in Materials Innovation at the University of California, Los Angeles, where he holds a joint appointment in the Department of Chemistry and Biochemistry and the Department of Material Science and Engineering. Kaner conducts research on conductive polymers (polyaniline), superhard materials and carbon compounds, such as fullerenes and graphene.
He has served on the board of directors for California NanoSystems Institute. Kaner serves as Chief Scientific Adviser to [https://hydrophilix.com/ Hydrophilix], [https://nanotechenergy.com/ Nanotech Energy], and [https://www.supermetalix.com/ Supermetalix], university spin-off companies. | 1 | Solid-state chemistry |
The Bonneville Salt Flats in Utah, where many land speed records have been set, are a well-known salt pan in the arid regions of the western United States.
The Etosha pan, in the Etosha National Park in Namibia, is another prominent example of a salt pan.
The Salar de Uyuni in Bolivia is the largest salt pan in the world. It contains 50% to 70% of the world's known lithium reserves. The large area, clear skies, and exceptional flatness of the surface make the Salar an ideal object for calibrating the altimeters of Earth observation satellites.
Parts of Rann of Kutch (India) are salt marsh in the wet season and salt pan in the dry season. | 1 | Solid-state chemistry |
Copper indium gallium (di)selenide (CIGS) is a I-III-VI semiconductor material composed of copper, indium, gallium, and selenium. The material is a solid solution of copper indium selenide (often abbreviated "CIS") and copper gallium selenide. It has a chemical formula of CuInGaSe, where the value of x can vary from 0 (pure copper indium selenide) to 1 (pure copper gallium selenide). CIGS is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure, and a bandgap varying continuously with x from about 1.0 eV (for copper indium selenide) to about 1.7 eV (for copper gallium selenide). | 1 | Solid-state chemistry |
Salts of , , , etc. are labeled as iodoplumbates. Lead perovskite semiconductors are often described as plumbates. | 1 | Solid-state chemistry |
Soon after arriving in Stockholm, Berzelius wrote a chemistry textbook for his medical students, Lärbok i Kemien, which was his first significant scientific publication. He had conducted experimentation, in preparation for writing this textbook, on the compositions of inorganic compounds, which was his earliest work on definite proportions. In 1813–4, he submitted a lengthy essay (published in five separate articles) on the proportions of elements in compounds. The essay commenced with a general description, introduced his new symbolism, and examined all the known elements. The essay ended with a table of the "specific weights" (relative atomic masses) of the elements, where oxygen was set to 100, and a selection of compounds written in his new formalism. This work provided evidence in favour of the atomic theory proposed by John Dalton: that inorganic chemical compounds are composed of atoms of different elements combined in whole number amounts. In discovering that atomic weights are not integer multiples of the atomic weight of hydrogen, Berzelius also disproved Prouts hypothesis that elements are built up from atoms of hydrogen. Berzeliuss last revised version of his atomic weight tables was first published in a German translation of his Textbook of Chemistry in 1826. | 1 | Solid-state chemistry |
After graduating from Yakima High School, serving in the United States Navy until the end of World War II, and attending the North Dakota Teachers College, the University of Wisconsin–Madison, and the University of Washington, Corbett remained at Washington to complete his Ph.D. in 1952. He joined the chemistry faculty of Iowa State University and the scientific staff of Ames Laboratory in 1953. He was affiliated with both institutions for his entire career, and served as chair of the Department of Chemistry between 1968 and 1973. He was elected a Fellow of the American Association for the Advancement of Science. He was awarded two DOE Awards for Outstanding Scientific Accomplishments and Sustained Research in Materials Chemistry, the Humboldt Prize (1985), the 2005 Spedding Award from the Rare Earth Research Conference, the 2008 Monie A. Ferst Award from Sigma Xi, and several ACS Awards for both Inorganic Chemistry and Distinguished Service in the Advancement of Inorganic Chemistry. He was elected to the United States National Academy of Sciences in 1992. | 1 | Solid-state chemistry |
Foams are commonly made by injecting a gas or mixing a foaming agent into molten metal. Molten metal can be foamed by creating gas bubbles in the material. Normally, bubbles in molten metal are highly buoyant in the high-density liquid and rise quickly to the surface. This rise can be slowed by increasing the viscosity of the molten metal by adding ceramic powders or alloying elements to form stabilizing particles in the molten metal, or by other means. Molten metal can be foamed in one of three ways:
* by injecting gas into the liquid metal from an external source;
* by causing gas formation in the liquid by admixing gas-releasing blowing agents with the molten metal;
* by causing the precipitation of gas that was previously dissolved in the molten metal.
To stabilize the molten metal bubbles, high temperature foaming agents (nano- or micrometer- sized solid particles) are required. The size of the pores, or cells, is usually 1 to 8 mm. When foaming or blowing agents are used, they are mixed with the powdered metal before it is melted. This is the so-called "powder route" of foaming, and it is probably the most established (from an industrial standpoint). After metal (e.g. aluminium) powders and foaming agent (e.g. TiH) have been mixed, they are compressed into a compact, solid precursor, which can be available in the form of a billet, a sheet, or a wire. Production of precursors can be done by a combination of materials forming processes, such as powder pressing, extrusion (direct or conform) and flat rolling. | 0 | Colloidal Chemistry |
The plasmon resonant frequency is highly sensitive to the refractive index of the environment; a change in refractive index results in a shift in the resonant frequency. As the resonant frequency is easy to measure, this allows LSP nanoparticles to be used for nanoscale sensing applications. Also, nanoparticles exhibiting strong LSP properties, such as gold nanorods, could enhance the signal in surface plasmon resonance sensing. Nanostructures exhibiting LSP resonances are used to enhance signals in modern analytical techniques based on spectroscopy. Other applications that rely on efficient light to heat generation in the nanoscale are heat-assisted magnetic recording (HAMR), photothermal cancer therapy, and thermophotovoltaics. So far, high efficiency applications using plasmonics have not been realized due to the high ohmic losses inside metals especially in the optical spectral range (visible and NIR)., Additionally surface plasmons have been used to create super lenses, invisibility cloaks, and to improve quantum computing. Another interesting area of research in plasmonics is the ability to turn plasmons "on" and "off" via modification of another molecule. The ability to turn plasmons on and off has important consequences for increasing sensitivity in detection methods. Recently, a supramolecular chromophore was coupled with a metal nanostructure. This interaction changed the localized surface plasmon resonance properties of the silver nanostructure by increasing the absorption intensity. | 0 | Colloidal Chemistry |
Molybdenum disulfide is a host for formation of intercalation compounds. This behavior is relevant to its use as a cathode material in batteries. One example is a lithiated material, . With butyl lithium, the product is . | 1 | Solid-state chemistry |
Most observations of fivelings have been for isolated particles. Similar structures can occur in thin films when particles merge to form a continuous coating, but do not recrystallize immediately. They can also form during annealing of films, which molecular dynamics simulations have indicated correlates to the motion of twin boundaries and a disclination, similar to the case of isolated nanoparticles described earlier. There is experimental evidence in thin films for interactions between partial dislocations and disclinations, as discussed in 1971 by de Wit. They can also be formed by mechanical deformation. The formation of a local fiveling structure by annealing or deformation has been attributed to a combination of stress relief and twin motion, which is different from the surface energy driven formation of isolated particles described above. | 1 | Solid-state chemistry |
When heated to 700 °C, indium(III) oxide forms InO, (called indium(I) oxide or indium suboxide), at 2000 °C it decomposes.
It is soluble in acids but not in alkali.
With ammonia at high temperature indium nitride is formed:
: InO + 2 NH → 2 InN + 3 HO
With KO and indium metal the compound KInO containing tetrahedral InO ions was prepared.
Reacting with a range of metal trioxides produces perovskites for example:
:InO + CrO → 2InCrO | 1 | Solid-state chemistry |
The electrical conductivity of dielectrics and semiconductors in presence of high electric fields (more than for insulators and up to for semiconductors) increases approximately as described by the Poole's law (eventually leading to electrical breakdown):
where
: is the zero-field electrical conductivity
: is a constant
:E is the applied electric field.
In this model the conduction is supposed to be carried by a free electron system moving in a self-consistent periodic potential.
On the contrary, Frenkel derived his formula describing the dielectric (or the semiconductor) as simply composed by neutral atoms acting as positively charged trap states (when empty, i.e. when the atoms are ionized).
For localized trap states with Coulomb potentials, the barrier height that an electron must cross to move from one atom to another is the depth of the trap potential well. Without any externally applied electric field, the maximum value of the potential is zero and is located at infinite distance from the trap center. When an external electric field is applied, the height of the potential barrier is reduced on one side of the trap by the amount
where:
:q is the elementary charge
: is the dynamic permittivity.
The first contribution is due to the applied electric field, the second is due to the electrostatic attraction between the ionic trap site and the conduction electron.
The potential has now a maximum at a distance from the Coulomb trap center, given by
Therefore and
This expression is similar to that obtained for the Schottky effect.
The factor 2 in the exponent, that makes the barrier reduction in the Poole–Frenkel effect twice larger than that experienced in the Schottky effect, is due to the interaction of the thermally excited electron with the immobile positive charge of the ion acting as a trap center, rather than with its mobile image charge induced in the metal at the Schottky interface.
Now if, without any applied electric field, the number of thermally ionized electrons is proportional to
where:
: is the voltage barrier (in zero applied electric field) that an electron must cross to move from one atom to another in the material
: is Boltzmann's constant
:T is the temperature
then, in presence of an external electric field the electrical conductivity will be proportional to
thus obtaining
differing from Poole's law in the dependence on .
Taking everything into account (both the frequency with which electrons are excited into the conduction band, and their motion once they're there), and assuming a field-independent mobility of electrons, the standard quantitative expression for the Poole–Frenkel current is:
where J is the current density.
Making the dependences from the applied voltage and the temperature explicit, the expression reads:
where d is the dielectric thickness.
For a given dielectric, different conduction processes may dominate in different voltage and temperature ranges.
For materials such as SiN, AlO, and SiO, at high temperature and high field regimes, the current J is likely due to Poole-Frenkel emission.
The detection of Poole-Frenkel emission as the limiting conduction process in a dielectric is usually made studying the slope in the so-called Poole-Frenkel plot, where the logarithm of the current density divided by the field () versus the square root of the field () is depicted. The idea of such a plot originates from the expression of the Poole-Frenkel current density, which contains this proportionality ( vs ), and would thus result in a straight line in this plot. For a fixed value of the voltage barrier in absence of any applied electric field, the slope is influenced by just one parameter: the dielectric permittivity.
Despite the same functional dependence of the current density upon the electric field intensity, one could differentiate between Poole-Frenkel conduction upon Schottky conduction as they would result in straight lines with different slopes in a Poole-Frenkel plot. The theoretical slopes can be evaluated knowing the high frequency dielectric constant of the material (, where is the vacuum permittivity), and comparing these with the slopes detected experimentally. As an alternative, one can evaluate the value for equating the theoretical slopes to the experimental detected ones, provided that it is known if the conductivity is electrode-limited or bulk-limited. Such a value of the high frequency dielectric constant should then conform the relation , where is the refractive index of the material. | 1 | Solid-state chemistry |
Brine (or briny water) is water with a high-concentration solution of salt (typically sodium chloride or calcium chloride). In diverse contexts, brine may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for brining foods) up to about 26% (a typical saturated solution, depending on temperature). Brine forms naturally due to evaporation of ground saline water but it is also generated in the mining of sodium chloride. Brine is used for food processing and cooking (pickling and brining), for de-icing of roads and other structures, and in a number of technological processes. It is also a by-product of many industrial processes, such as desalination, so it requires wastewater treatment for proper disposal or further utilization (fresh water recovery). | 1 | Solid-state chemistry |
The U.S. government eventually terminated Goodenough's research funding, so during the late 1970s and early 1980s, he left the United States and continued his career as head of the Inorganic Chemistry Laboratory at the University of Oxford. Among the highlights of his work at Oxford, Goodenough is credited with significant research essential to the development of commercial lithium-ion rechargeable batteries. Goodenough was able to expand upon previous work from M. Stanley Whittingham on battery materials, and found in 1980 that by using LiCoO as a lightweight, high energy density cathode material, he could double the capacity of lithium-ion batteries.
Although Goodenough saw a commercial potential of batteries with his LiCoO2 and LiNiO2 cathodes and approached Oxford University with a request to patent this invention, Oxford refused. Unable to afford the patenting expenses with his academic salary, Goodenough turned to UKs Atomic Energy Research Establishment in Harwell, which accepted his offer, but under the terms, which provided zero royalty payment to the inventors John B. Goodenough and Koichi Mizushima. In 1990, the AERE licensed Goodenoughs patents to Sony Corporation, which was followed by other battery manufacturers. It was estimated, that the AERE made over 10 mln. British pounds from this licensing.
The work at Sony on further improvements to Goodenough's invention was led by Akira Yoshino, who had developed a scaled up design of the battery and manufacturing process. Goodenough received the Japan Prize in 2001 for his discoveries of the materials critical to the development of lightweight high energy density rechargeable lithium batteries, and he, Whittingham, and Yoshino shared the 2019 Nobel Prize in Chemistry for their research in lithium-ion batteries. | 1 | Solid-state chemistry |
Nanoparticles occur in a great variety of shapes, which have been given many informal names such as nanospheres, nanorods, nanochains, decagedral nanoparticles, nanostars, nanoflowers, nanoreefs, nanowhiskers, nanofibers, and nanoboxes.
The shapes of nanoparticles may be determined by the intrinsic crystal habit of the material, or by the influence of the environment around their creation, such as the inhibition of crystal growth on certain faces by coating additives, the shape of emulsion droplets and micelles in the precursor preparation, or the shape of pores in a surrounding solid matrix. Some applications of nanoparticles may require specific shapes, as well as specific sizes or size ranges.
Amorphous particles typically adopt a spherical shape (due to their microstructural isotropy).
The study of fine particles is called micromeritics. | 0 | Colloidal Chemistry |
Keblinski et al. had named four main possible mechanisms for the anomalous increase in nanofluids heat transfer which are : | 0 | Colloidal Chemistry |
Research efforts have been put into using natural components in the creation of potentially biodegradable foam products. Mycelium (Figure 8), chitosan (Figure 9), wheat gluten (Figure 10), and cellulose (Figure 11) have all been used to create biofoams for different purposes. The wheat gluten example was used in combination with graphene to attempt to make a conductive biofoam. The mycelium-based, chitosan-based, and cellulose-based biofoam examples are intended to become cost effective and low density material options. | 0 | Colloidal Chemistry |
Tapioca starch can be burnt off easily through the sintering process and is insoluble in titanium. Titanium foams consisting of a bimodal pore distribution (macropores ranging from 100 to 300 μm) and 64–79% porosity, exhibited yield strengths of 23–41 MPa and Young's moduli of 1.6–3.7 GPa. | 0 | Colloidal Chemistry |
The kingdom of Benin existed in the southwestern region of Nigeria in modern Edo state, Nigeria. According to scholars the kingdom of Benin (also known as the Edo Kingdom, or the Benin Empire) originated around the year 900 by the Ogiso kings, it is said between the eleventh and the thirteenth a member from the Oba dynasty would take control of the state. This dynasty would rule until 1897 when the British occupied the kingdom of Benin in February 9. The kingdom reached its peak during the rule of Ewuare the Great, he ruled from 1440 to 1473. King Ewuare expanded its natural borders and introduced wood and ivory carving to the kingdom. One of the first recorded visits to Benin City was made by Portuguese explorer, João Afonso de Aveiro in 1486. After contact with the Portuguese the Benin Kingdom established a strong mercantile relationship with Portugal and later other European states. They traded slaves and Beninese products such as ivory, pepper, gold and palm oil for European goods such as manillas, metals and guns. In addition they established diplomatic relations in the late 15th century, the Oba sent an ambassador to Lisbon, and the king of Portugal sent Christian missionaries to Benin City in 1486. | 1 | Solid-state chemistry |
Armand Paul Alivisatos (born November 12, 1959) is an American chemist and academic administrator who has served as the 14th president of the University of Chicago since September 2021. He is a pioneer in nanomaterials development and an authority on the fabrication of nanocrystals and their use in biomedical and renewable energy applications. He was ranked fifth among the world's top 100 chemists for the period 2000–2010 in the list released by Thomson Reuters.
On September 1, 2021, Alivisatos became the 14th president of the University of Chicago, where he also holds a faculty appointment as the John D. MacArthur Distinguished Service Professor in the Department of Chemistry, the Pritzker School of Molecular Engineering, and the College; and serves as the Chair of the Board of Governors of Argonne National Laboratory and Chair of the Board of Directors of Fermi Research Alliance LLC, the operator of Fermi National Accelerator Laboratory.
Prior to joining the University of Chicago, Alivisatos was the Executive Vice Chancellor and Provost (2017–2021) of the University of California, Berkeley, where he had taught since 1988. He previously served as the Director of the Lawrence Berkeley National Laboratory (2009–2016), and as Berkeley’s interim Vice Chancellor for Research (2016–2017). He held a number of faculty appointments at Berkeley, including the Samsung Distinguished Professor in Nanoscience and Nanotechnology Research and Professor of Chemistry and Materials Science & Engineering. Alivisatos was also the Founding Director of the Kavli Energy Nanosciences Institute (ENSI), an institute on the Berkeley campus launched by the Kavli Foundation to explore the application of nanoscience to sustainable energy technologies. | 1 | Solid-state chemistry |
Open cell foams are manufactured by foundry or powder metallurgy. In the powder method, "space holders" are used; as their name suggests, they occupy the pore spaces and channels. In casting processes, foam is cast with an open-celled polyurethane foam skeleton. | 0 | Colloidal Chemistry |
β-FeSe is the simplest iron-based superconductor but with diverse properties. It starts to superconduct at 8 K at normal pressure but its critical temperature (T) is dramatically increased to 38 K under pressure, by means of intercalation, or after quenching at high pressures. The combination of both intercalation and pressure results in re-emerging superconductivity at 48 K.
In 2013 it was reported that a single atomic layer of FeSe epitaxially grown on SrTiO is superconductive with a then-record transition temperature for iron-based superconductors of 70 K. This discovery has attracted significant attention and in 2014 a superconducting transition temperature of over 100K was reported for this system. | 1 | Solid-state chemistry |
In chemistry, a thioxanthate is an organosulfur compound with the formula RSCSX. When X is an alkali metal, the thioxanthate is a salt. When X is a transition metal, the thioxanthate is a ligand, and when X is an organic group, the compounds are called thioxanthate esters. They are usually yellow colored compounds that often dissolve in organic solvents. They are used as precursors to some catalysts, froth flotation agents, and additives for lubricants. | 1 | Solid-state chemistry |
The materials used in SWRO plants are dominated by non-metallic components and stainless steels, since lower operating temperatures allow the construction of desalination plants with more corrosion-resistant coatings. Therefore, the concentration values of heavy metals in the discharge of SWRO plants are much lower than the acute toxicity levels to generate environmental impacts on marine ecosystems. | 1 | Solid-state chemistry |
The porous network of clay particles enable nanocomposite hydrogels to swell in the presence of water. Swelling (and de-swelling) distinguishes NC gels from conventionally-made hydrogels (OR gels) as it is a property that OR gels lack. The swelling property of NC gels allows them to collect the surrounding aqueous solution instead of being dissolved by it, which helps make them good candidates for drug delivery carriers. | 0 | Colloidal Chemistry |
The shape of a micelle is directly dependent on the packing parameter of the surfactant. Surfactants with a packing parameter of ≤ 1/3 appear to have a cone-like shape which will pack together to form spherical micelles when in an aqueous environment (top in figure). Surfactants with a packing parameter of 1/3 ≤ 1/2 appear to have a wedge-like shape and will aggregate together in an aqueous environment to form cylindrical micelles (bottom in figure). Surfactants with a packing parameter of > 1/2 appear to have a cylindrical shape and pack together to form a bilayer in an aqueous environment (middle in figure). | 0 | Colloidal Chemistry |
Uranium dioxide is oxidized in contact with oxygen to the triuranium octaoxide.
:3 UO + O → UO at 700 °C (970 K)
The electrochemistry of uranium dioxide has been investigated in detail as the galvanic corrosion of uranium dioxide controls the rate at which used nuclear fuel dissolves. See spent nuclear fuel for further details. Water increases the oxidation rate of plutonium and uranium metals. | 1 | Solid-state chemistry |
Exposure to PFAS is a risk factor for various hypertensive disorders in pregnancy, including preeclampsia and high blood pressure. It is not clear whether PFAS exposure is associated with wider cardiovascular disorders during pregnancy. Human breast milk has the capability to harbor PFAs as well as be transferred from mother to infant through breastfeeding. | 0 | Colloidal Chemistry |
Polyaniline nanofibers have been used in the creation of monolithic actuators. They can be used in this application due to their ability to be flash-welded. When exposed to light, polyaniline converts the absorbed energy directly into heat. In a polyaniline film, the heat is dispersed throughout the polymer. In polyaniline nanofibers, however, the heat is trapped within the individual fibers. Therefore, if the intensity of the light is great enough, it will cause the temperature of the nanofibers to rise rapidly, which causes them to weld together or burn. With a moderate flash intensity, the nanofibers will melt rapidly to form a smooth film. Using mask, welds in specific patterns can be made using this technique. In a thick enough sample of nanofibers, only the side exposed to the flash will be welded, creating an asymmetric film where one side remains intact as nanofibers while the other side is effectively crosslinked due to welding. These asymmetric films demonstrate rapid reversible actuation in the presence of acids and bases, in the form of bending and curling. The advantages polyaniline nanofiber asymmetric films have over other actuators include the ease of synthesis, large degree of bending, patternability, and no delamination. These actuators could be used in the development of microtweezers, microvalves, artificial muscles, chemical sensors, and patterned actuator structures. | 0 | Colloidal Chemistry |
Polymeric nanoparticles are synthetic polymers with a size ranging from 10 to 100 nm. Common synthetic polymeric nanoparticles include polyacrylamide, polyacrylate, and chitosan. Drug molecules can be incorporated either during or after polymerization. Depending on the polymerization chemistry, the drug can be covalently bonded, encapsulated in a hydrophobic core, or conjugated electrostatically. Common synthetic strategies for polymeric nanoparticles include microfluidic approaches, electrodropping, high pressure homogenization, and emulsion-based interfacial polymerization.
Polymer biodegradability is an important aspect to consider when choosing the appropriate nanoparticle chemistry. Nanocarriers composed of biodegradable polymers undergo hydrolysis in the body, producing biocompatible small molecules such as lactic acid and glycolic acid.
Polymeric nanoparticles can be created via self assembly or other methods such as particle replication in nonwetting templates (PRINT) which allows customization of composition, size, and shape of the nanoparticle using tiny molds. | 0 | Colloidal Chemistry |
Current applications for syntactic foam include buoyancy modules for marine riser tensioners, remotely operated underwater vehicles (ROVs), autonomous underwater vehicles (AUVs), deep-sea exploration, boat hulls, and helicopter and airplane components.
Cementitious syntactic foams have also been investigated as a potential lightweight structural composite material. These materials include glass microspheres dispersed in a cement paste matrix to achieve a closed cell foam structure, instead of a metallic or a polymeric matrix. Cementitious syntactic foams have also been tested for their mechanical performance under high strain rate loading conditions to evaluate their energy dissipation capacity in crash cushions, blast walls, etc. Under these loading conditions, the glass microspheres of the cementitious syntactic foams did not show progressive crushing. Ultimately, unlike the polymeric and metallic syntactic foams, they did not emerge as suitable materials for energy dissipation applications. Structural applications of syntactic foams include use as the intermediate layer (that is, the core) of sandwich panels.
Though the cementitious syntactic foams demonstrate superior specific strength values in comparison to most conventional cementitious materials, it is challenging to manufacture them. Generally, the hollow inclusions tend to buoy and segregate in the low shear strength and high-density fresh cement paste. Therefore, maintaining a uniform microstructure across the material must be achieved through a strict control of the composite rheology. In addition, certain glass types of microspheres may lead to an alkali silica reaction. Therefore, the adverse effects of this reaction must be considered and addressed to ensure the long-term durability of these composites.
Other applications include;
*Deep-sea buoyancy foams. A method of creating submarine hulls by 3D printing was developed in 2018.
*Thermoforming plug assist
*Radar transparent materials
*Acoustically attenuating materials
*Cores for sandwich composites
*Blast mitigating materials
*Sporting goods such as bowling balls, tennis rackets, and soccer balls. | 0 | Colloidal Chemistry |
Literature distinguishes two major mechanisms of solubilization process of oil by surfactant micelles, affecting the kinetics of solubilization: surface reaction, i.e., by transient adsorption of micelles at the water-oil interface, and bulk reaction, whereby the surfactant micelles capture dissolved oil molecules. | 0 | Colloidal Chemistry |
Generally a defoamer is insoluble in the foaming medium and has surface active properties. An essential feature of a defoamer product is a low viscosity and a facility to spread rapidly on foamy surfaces. It has affinity to the air-liquid surface where it destabilizes the foam lamellas. This causes rupture of the air bubbles and breakdown of surface foam. Entrained air bubbles are agglomerated, and the larger bubbles rise to the surface of the bulk liquid more quickly. | 0 | Colloidal Chemistry |
Current nanoparticle drug delivery systems can be cataloged based on their platform composition into several groups: polymeric nanoparticles, inorganic nanoparticles, viral nanoparticles, lipid-based nanoparticles, and nanoparticle albumin-bound (nab) technology. Each family has its unique characteristics. | 0 | Colloidal Chemistry |
Particle deposition occurs in numerous natural and industrial systems. Few examples are given below.
* Coatings and surface functionalization. Paints and adhesives often are concentrated suspensions of colloidal particles, and in order to adhere well to the surface the particles must deposit to the surface in question. Deposits of a monolayer of colloidal particles can be used to pattern the surface on a μm or nm scale, a process referred to as colloidal lithography.
* Filters and filtration membranes. When particle deposit to filters or filtration membranes, they lead to pore clogging a membrane fouling. When designing well functioning membranes, particle deposition must be avoided, and proper functionalization of the membranes is essential.
* Deposition of microorganisms. Microorganisms may deposit similarly to colloidal particles. This deposition is a desired phenomenon in subsurface waters, as the aquifer filters out eventually injected microorganisms during the recharge of aquifers. On the other hand, such deposition is highly undesired at the surface of human teeth as it represent the origin of dental plaques. Deposition of microorganisms is also relevant in the formation of biofilms. | 0 | Colloidal Chemistry |
Diffusiophoresis is the spontaneous motion of colloidal particles or molecules in a fluid, induced by a concentration gradient of a different substance. In other words, it is motion of one species, A, in response to a concentration gradient in another species, B. Typically, A is colloidal particles which are in aqueous solution in which B is a dissolved salt such as sodium chloride, and so the particles of A are much larger than the ions of B. But both A and B could be polymer molecules, and B could be a small molecule. For example, concentration gradients in ethanol solutions in water move 1 μm diameter colloidal particles with diffusiophoretic velocities of order 0.1 to 1 μm/s, the movement is towards regions of the solution with lower ethanol concentration (and so higher water concentration). Both species A and B will typically be diffusing but diffusiophoresis is distinct from simple diffusion: in simple diffusion a species A moves down a gradient in its own concentration.
Diffusioosmosis, also referred to as capillary osmosis, is flow of a solution relative to a fixed wall or pore surface, where the flow is driven by a concentration gradient in the solution. This is distinct from flow relative to a surface driven by a gradient in the hydrostatic pressure in the fluid. In diffusioosmosis the hydrostatic pressure is uniform and the flow is due to a concentration gradient.
Diffusioosmosis and diffusiophoresis are essentially the same phenomenon. They are both relative motion of a surface and a solution, driven by a concentration gradient in the solution. This motion is called diffusiophoresis when the solution is considered static with particles moving in it due to relative motion of the fluid at the surface of these particles. The term diffusioosmosis is used when the surface is viewed as static, and the solution flows.
A well studied example of diffusiophoresis is the motion of colloidal particles in an aqueous solution of an electrolyte solution, where a gradient in the concentration of the electrolyte causes motion of the colloidal particles. Colloidal particles may be hundred of nanometres or larger in diameter, while the interfacial double layer region at the surface of the colloidal particle will be of order the Debye length wide, and this is typically only nanometres. So here, the interfacial width is much smaller than the size of the particle, and then the gradient in the smaller species drives diffusiophoretic motion of the colloidal particles largely through motion in the interfacial double layer.
Diffusiophoresis was first studied by Derjaguin and coworkers in 1947. | 0 | Colloidal Chemistry |
Amphipols (a portmanteau of amphiphilic polymers) are a class of amphiphilic polymers designed to keep membrane proteins soluble in water without the need for detergents, which are traditionally used to this end but tend to be denaturing. Amphipols adsorb onto the hydrophobic transmembrane surface of membrane proteins thanks to their hydrophobic moieties and keep the complexes thus formed water-soluble thanks to the hydrophilic ones. Amphipol-trapped membrane proteins are, as a rule, much more stable than detergent-solubilized ones, which facilitates their study by most biochemical and biophysical approaches. Amphipols can be used to fold denatured membrane proteins to their native form and have proven particularly precious in the field of single-particle electron cryo-microscopy (cryo-EM; see e.g. ).The properties and uses of amphipols and other non-conventional surfactants are the subject of a book by Jean-Luc Popot. | 0 | Colloidal Chemistry |
A typical setup to measure streaming currents consists of two reversible electrodes placed on either side of a fluidic geometry across which a known pressure difference is applied. When both electrodes are held at the same potential, the streaming current is measured directly as the electric current flowing through the electrodes. Alternatively, the electrodes can be left floating, allowing a streaming potential to build up between the two ends of the channel.
A streaming potential is defined as positive when the electric potential is higher on the high pressure end of the flow system than on the low pressure end.
The value of streaming current observed in a capillary is usually related to the zeta potential through the relation:
The conduction current, which is equal in magnitude to the streaming current at steady state, is:
At steady state, the streaming potential built up across the flow system is given by:
Symbols:
*I - streaming current under short-circuit conditions, A
*U - streaming potential at zero net current conditions, V
*I - conduction current, A
*ε - relative permittivity of the liquid, dimensionless
*ε - electrical permittivity of vacuum, F·m
*η - dynamic viscosity of the liquid, kg·m·s
*ζ - zeta potential, V
*ΔP - pressure difference, Pa
*L - capillary length, m
*a - capillary radius, m
*K - specific conductivity of the bulk liquid, S·m
The equation above is usually referred to as the Helmholtz–Smoluchowski equation.
The above equations assume that:
* the double layer is not too large compared to the pores or capillaries (i.e., ), where κ is the reciprocal of the Debye length
* there is no surface conduction (which typically may become important when the zeta potential is large, e.g., |ζ| > 50 mV)
* there is no electrical double layer polarization
* the surface is homogeneous in properties
* there is no axial concentration gradient
* the geometry is that of a capillary/tube. | 0 | Colloidal Chemistry |
Berzelius was the first person to make the distinction between organic compounds (those containing carbon), and inorganic compounds. In particular, he advised Gerardus Johannes Mulder in his elemental analyses of organic compounds such as coffee, tea, and various proteins. The term protein itself was coined by Berzelius, in 1838, after Mulder observed that all proteins seemed to have the same empirical formula and came to the erroneous conclusion that they might be composed of a single type of very large molecule. The term is derived from the Greek, meaning "of the first rank", and Berzelius proposed the name because proteins were so fundamental to living organisms.
In 1808, Berzelius discovered that lactic acid occurs in muscle tissue, not just in milk.
The term biliverdin was coined by Berzelius in 1840, although he preferred "bilifulvin" (yellow/red) over "bilirubin" (red). | 1 | Solid-state chemistry |
Nazar studied chemistry at the University of British Columbia, where she earned a bachelor's degree in 1978. She was inspired to study chemistry after being inspired by her first year professor. Her father had trained as a scientist and ran his own jewellery making business. Nazar joined the University of Toronto for her graduate studies, and completed a PhD under the supervision of Geoffrey Ozin in 1984. After obtaining her degree, she worked as a postdoctoral researcher working with Allan Jacobson at Exxon Research and Engineering Company, before joining the University of Waterloo in the late 1980s, when she became interested in electrochemistry and Inorganic chemistry. | 1 | Solid-state chemistry |
* Bennigsen-Foerder Prize in 1997
* Prize of the Working Group of German University Professors of Chemistry (ADUC) in 2000
* Member of the Berlin-Brandenburg Academy of Sciences since 2016 | 1 | Solid-state chemistry |
Measurement and definition difficulties arise because natural waters contain a complex mixture of many different elements from different sources (not all from dissolved salts) in different molecular forms. The chemical properties of some of these forms depend on temperature and pressure. Many of these forms are difficult to measure with high accuracy, and in any case complete chemical analysis is not practical when analyzing multiple samples. Different practical definitions of salinity result from different attempts to account for these problems, to different levels of precision, while still remaining reasonably easy to use.
For practical reasons salinity is usually related to the sum of masses of a subset of these dissolved chemical constituents (so-called solution salinity), rather than to the unknown mass of salts that gave rise to this composition (an exception is when artificial seawater is created). For many purposes this sum can be limited to a set of eight major ions in natural waters, although for seawater at highest precision an additional seven minor ions are also included. The major ions dominate the inorganic composition of most (but by no means all) natural waters. Exceptions include some pit lakes and waters from some hydrothermal springs.
The concentrations of dissolved gases like oxygen and nitrogen are not usually included in descriptions of salinity. However, carbon dioxide gas, which when dissolved is partially converted into carbonates and bicarbonates, is often included. Silicon in the form of silicic acid, which usually appears as a neutral molecule in the pH range of most natural waters, may also be included for some purposes (e.g., when salinity/density relationships are being investigated). | 1 | Solid-state chemistry |
Arumugam Manthiram (; born March 15, 1951) is an Indian-American materials scientist and engineer, best known for his identification of the polyanion class of lithium ion battery cathodes, understanding of how chemical instability limits the capacity of layered oxide cathodes, and technological advances in lithium sulfur batteries. He is a Cockrell Family Regents Chair in engineering, Director of the Texas Materials Institute, the Director of the Materials Science and Engineering Program at the University of Texas at Austin, and a former lecturer of Madurai Kamaraj University. Manthiram delivered the 2019 Nobel Lecture in Chemistry on behalf of Chemistry Laureate John B. Goodenough. | 1 | Solid-state chemistry |
Polyurethane foam has been widely used to insulate fuel tanks on Space Shuttles. However, it requires a perfect application, as any air pocket, dirt or an uncovered tiny spot can knock it off due to extreme conditions of liftoff. Those conditions include violent vibrations, air friction and abrupt changes in temperature and pressure. For a perfect application of the foam there have been two obstacles: limitations related to wearing protective suits and masks by workers and inability to test for cracks before launch, such testing is done only by naked eye. The loss of foam caused the Space Shuttle Columbia disaster. According to the Columbia accident report, NASA officials found foam loss in over 80% of the 79 missions for which they have pictures.
By 2009 researchers created a superior polyimide foam to insulate the reusable cryogenic propellant tanks of Space Shuttles. | 0 | Colloidal Chemistry |
Many solids react vigorously with gas species like chlorine, iodine, and oxygen. Other solids form adducts, such as CO or ethylene. Such reactions are conducted in open-ended tubes, which the gasses are passed through. Also, these reactions can take place inside a measuring device such as a TGA. In that case, stoichiometric information can be obtained during the reaction, which helps identify the products. | 1 | Solid-state chemistry |
Transport reactions are classified according to the thermodynamics of the reaction between the solid and the transporting agent. When the reaction is exothermic, then the solid of interest is transported from the cooler end (which can be quite hot) of the reactor to a hot end, where the equilibrium constant is less favorable and the crystals grow. The reaction of molybdenum dioxide with the transporting agent iodine is an exothermic process, thus the MoO migrates from the cooler end (700 °C) to the hotter end (900 °C):
:MoO + I MoOI ΔH < 0 (exothermic)
Using 10 milligrams of iodine for 4 grams of the solid, the process requires several days.
Alternatively, when the reaction of the solid and the transport agent is endothermic, the solid is transported from a hot zone to a cooler one. For example:
:FeO + 6 HCl FeCl+ 3 HO ΔH > 0 (endothermic)
The sample of iron(III) oxide is maintained at 1000 °C, and the product is grown at 750 °C. HCl is the transport agent. Crystals of hematite are reportedly observed at the mouths of volcanoes because of chemical transport reactions whereby volcanic hydrogen chloride volatilizes iron(III) oxides. | 1 | Solid-state chemistry |
Xanthate salts of alkali metals are produced by the treatment of an alcohol, alkali, and carbon disulfide. The process is called xanthation. In chemical terminology, the alkali reacts with the alcohol to produce an alkoxide, which is the nucleophile that adds to the electrophilic carbon atom in CS. Often the alkoxide is generated in situ by treating the alcohol with sodium hydroxide or potassium hydroxide:
:ROH + CS + KOH → ROCSK + HO
For example, sodium ethoxide gives sodium ethyl xanthate. Many alcohols can be used in this reaction. Technical grade xanthate salts are usually of 90–95% purity. Impurities include alkali metal sulfides, sulfates, trithiocarbonates, thiosulfates, sulfites, or carbonates as well as residual raw material such as alcohol and alkali hydroxide. These salts are available commercially as powder, granules, flakes, sticks, and solutions are available.
Some commercially or otherwise useful xanthate salts include:
* sodium ethyl xanthate CHCHOCSNa
* potassium ethyl xanthate, CHCHOCSK
* potassium isopropyl xanthate, (CH)CHOCSK
* sodium isobutyl xanthate, (CH)CHCHOCSNa
* potassium amyl xanthate, CH(CH)OCSK
The OCS core of xanthate salts, like that of the carbonates and the esters has trigonal planar molecular geometry. The central carbon atom is sp-hybridized. | 1 | Solid-state chemistry |
As nanoparticle interactions take place on a nanoscale, the particle interactions must be scaled similarly. Hamaker interactions take into account the polarization characteristics of a large number of nearby particles and the effects they have on each other. Hamaker interactions sum all of the forces between all particles and the solvent(s) involved in the system. While Hamaker theory generally describes a macroscopic system, the vast number of nanoparticles in a self-assembling system allows the term to be applicable. Hamaker constants for nanoparticles are calculated using Lifshitz theory, and can often be found in literature. | 0 | Colloidal Chemistry |
Copper(I) thiocyanate (or cuprous thiocyanate) is a coordination polymer with formula CuSCN. It is an air-stable, white solid used as a precursor for the preparation of other thiocyanate salts. | 1 | Solid-state chemistry |