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In solid-state physics, the Hill limit is a critical distance defined in a lattice of actinide or rare-earth atoms. These atoms own partially filled or levels in their valence shell and are therefore responsible for the main interaction between each atom and its environment. In this context, the hill limit is defined as twice the radius of the -orbital. Therefore, if two atoms of the lattice are separate by a distance greater than the Hill limit, the overlap of their -orbital becomes negligible. A direct consequence is the absence of hopping for the f electrons, ie their localization on the ion sites of the lattice.
Localized f electrons lead to paramagnetic materials since the remaining unpaired spins are stuck in their orbitals. However, when the rare-earth lattice (or a single atom) is embedded in a metallic one (intermetallic compound), interactions with the conduction band allow the f electrons to move through the lattice even for interatomic distances above the Hill limit. | 1 | Solid-state chemistry |
Copper(II) chloride is used as a catalyst in a variety of processes that produce chlorine by oxychlorination. The Deacon process takes place at about 400 to 450 °C in the presence of a copper chloride:
Copper(II) chloride catalyzes the chlorination in the production of vinyl chloride and dichloromethane.
Copper(II) chloride is used in the copper–chlorine cycle where it reacts with steam into copper(II) oxide dichloride and hydrogen chloride and is later recovered in the cycle from the electrolysis of copper(I) chloride. | 1 | Solid-state chemistry |
Semi-solid and soft nanoparticles have been produced. A prototype nanoparticle of semi-solid nature is the liposome. Various types of liposome nanoparticles are currently used clinically as delivery systems for anticancer drugs and vaccines.
The breakdown of biopolymers into their nanoscale building blocks is considered a potential route to produce nanoparticles with enhanced biocompatibility and biodegradability. The most common example is the production of nanocellulose from wood pulp. Other examples are nanolignin, nanochitin, or nanostarches.
Nanoparticles with one half hydrophilic and the other half hydrophobic are termed Janus particles and are particularly effective for stabilizing emulsions. They can self-assemble at water/oil interfaces and act as pickering stabilizers.
Hydrogel nanoparticles made of N-isopropylacrylamide hydrogel core shell can be dyed with affinity baits, internally. These affinity baits allow the nanoparticles to isolate and remove undesirable proteins while enhancing the target analytes. | 0 | Colloidal Chemistry |
The room temperature form of NbO has a tetragonal, rutile-like structure with short Nb-Nb distances, indicating Nb-Nb bonding. The high temperature form also has a rutile-like structure with short Nb-Nb distances. Two high-pressure phases have been reported: one with a rutile-like structure (again, with short Nb-Nb distances); and a higher pressure with baddeleyite-related structure.
NbO is insoluble in water and is a powerful reducing agent, reducing carbon dioxide to carbon and sulfur dioxide to sulfur. In an industrial process for the production of niobium metal, NbO is produced as an intermediate, by the hydrogen reduction of NbO. The NbO is subsequently reacted with magnesium vapor to produce niobium metal. | 1 | Solid-state chemistry |
Detergents are a group of compounds with an amphiphilic structure, where each molecule has a hydrophilic (polar) head and a long hydrophobic (non-polar) tail. The hydrophobic portion of these molecules may be straight- or branched-chain hydrocarbons, or it may have a steroid structure. The hydrophilic portion is more varied, they may be ionic or non-ionic, and can range from a simple or a relatively elaborate structure. Detergents are surfactants since they can decrease the surface tension of water. Their dual nature facilitates the mixture of hydrophobic compounds (like oil and grease) with water. Because air is not hydrophilic, detergents are also foaming agents to varying degrees.
Detergent molecules aggregate to form micelles, which makes them soluble in water. The hydrophobic group of the detergent is the main driving force of micelle formation, its aggregation forms the hydrophobic core of the micelles. The micelle can remove grease, protein or soiling particles. The concentration at which micelles start to form is the critical micelle concentration (CMC), and the temperature at which the micelles further aggregate to separate the solution into two phases is the cloud point when the solution becomes cloudy and detergency is optimal.
Detergents work better in an alkaline pH. The properties of detergents are dependent on the molecular structure of the monomer. The ability to foam may be determined by the head group, for example anionic surfactants are high-foaming, while nonionic surfactants may be non-foaming or low-foaming. | 0 | Colloidal Chemistry |
It is sometimes difficult to determine if a material is non-stoichiometric or if the formula is best represented by large numbers. The oxides of tungsten illustrate this situation. Starting from the idealized material tungsten trioxide, one can generate a series of related materials that are slightly deficient in oxygen. These oxygen-deficient species can be described as , but in fact they are stoichiometric species with large unit cells with the formulas , where n = 20, 24, 25, 40. Thus, the last species can be described with the stoichiometric formula , whereas the non-stoichiometric description implies a more random distribution of oxide vacancies. | 1 | Solid-state chemistry |
A similar reaction like that of MoO is used in halogen lamps. The tungsten is evaporated from the tungsten filament and converted with traces of oxygen and iodine into the WOI, at the high temperatures near the filament the compound decomposes back to tungsten, oxygen and iodine.
:WO + I WOI, ΔH < 0 (exothermic) | 1 | Solid-state chemistry |
Ulrich Müller (born 6 July 1940 in Bogotá) is a German chemist that is known for his works on solid-state chemistry and the application of crystallographic group theory to crystal chemistry. He is the author of several textbooks on chemistry, solid-state chemistry, and crystallography. | 1 | Solid-state chemistry |
Dead Sea salt was used by the peoples of Ancient Egypt and it has been utilized in various unguents, skin creams, and soaps since then. | 1 | Solid-state chemistry |
Douglas Keszler has received a number of awards and honors, including the following:
* Exxon Solid-state Chemistry Award (1988)
* Alfred P. Sloan Research Fellow (1990)
* T. T. Sugihara Young Faculty Research Award (1994)
* F.A. Gilfillan Award (2001)
* OSU Researcher of the Year Award (2003)
* SWOSU Alumni Fellow (2005)
* ACS Award in the Chemistry of Materials (2017) | 1 | Solid-state chemistry |
In chemistry, a carbide usually describes a compound composed of carbon and a metal. In metallurgy, carbiding or carburizing is the process for producing carbide coatings on a metal piece. | 1 | Solid-state chemistry |
When κa is between large values where simple analytical models are available, and low values where numerical calculations are valid, Henrys equation can be used when the zeta potential is low. For a nonconducting sphere, Henrys equation is , where f is the Henry function, one of a collection of functions which vary smoothly from 1.0 to 1.5 as κa approaches infinity. | 0 | Colloidal Chemistry |
Using BCS theory and the known energy gaps of the pi and sigma bands of electrons (2.2 and 7.1 meV, respectively), the pi and sigma bands of electrons have been found to have two different coherence lengths (51 nm and 13 nm, respectively). The corresponding London penetration depths are 33.6 nm and 47.8 nm. This implies that the Ginzburg-Landau parameters are 0.66±0.02 and 3.68, respectively. The first is less than 1/ and the second is greater, therefore the first seems to indicate marginal type I superconductivity and the second type II superconductivity.
It has been predicted that when two different bands of electrons yield two quasiparticles, one of which has a coherence length that would indicate type I superconductivity and one of which would indicate type II, then in certain cases, vortices attract at long distances and repel at short distances. In particular, the potential energy between vortices is minimized at a critical distance. As a consequence there is a conjectured new phase called the semi-Meissner state, in which vortices are separated by the critical distance. When the applied flux is too small for the entire superconductor to be filled with a lattice of vortices separated by the critical distance, then there are large regions of type I superconductivity, a Meissner state, separating these domains.
Experimental confirmation for this conjecture has arrived recently in MgB experiments at 4.2 Kelvin. The authors found that there are indeed regimes with a much greater density of vortices. Whereas the typical variation in the spacing between Abrikosov vortices in a type II superconductor is of order 1%, they found a variation of order 50%, in line with the idea that vortices assemble into domains where they may be separated by the critical distance. The term type-1.5 superconductivity was coined for this state. | 1 | Solid-state chemistry |
The spin interaction that is usually employed for structural analyses via solid state NMR spectroscopy is the magnetic dipolar interaction.
Additional knowledge about other interactions within the studied system like the chemical shift or the electric quadrupole interaction can be helpful as well, and in some cases solely the chemical shift has been employed as e.g. for zeolites.
The “dipole coupling”-based approach parallels protein NMR spectroscopy to some extent in that e.g. multiple residual dipolar couplings are measured for proteins in solution, and these couplings are used as constraints in the protein structure calculation.
In NMR crystallography the observed spins in case of organic molecules would often be spin-1/2 nuclei of moderate frequency (, , , etc.). I.e. is excluded due to its large magnetogyric ratio and high spin concentration leading to a network of strong homonuclear dipolar couplings. There are two solutions with respect to H: spin diffusion experiments (see below) and specific labelling with spins (spin = 1). The latter is also popular e.g. in NMR spectroscopic investigations of hydrogen bonds in solution and the solid state.
Both intra- and intermolecular structural elements can be investigated e.g. via deuterium REDOR (an established solid state NMR pulse sequence to measure dipolar couplings between deuterons and other spins).
This can provide an additional constraint for an NMR crystallographic structural investigation in that it can be used to find and characterize e.g. intermolecular hydrogen bonds. | 1 | Solid-state chemistry |
Researchers produced an artificial tooth whose microstructure mimicked that of a real tooth. The outer layers, corresponding to enamel, were hard and structurally complex. The outer layers contained glass nanoparticles and aluminium oxide plates were aligned perpendicular to the surface. After the outer layers hardened, a second suspension was poured. It contained no glass, and the plates were aligned horizontally to the surface of the tooth. These deeper layers were tougher, resembling dentine. The tooth was then cooked at 1,600 degrees to compact and harden the material — a process known as sintering. The last step involved filling remaining pores with a synthetic monomer used in dentistry, which polymerizes after treatment. Hardness and durability approximated that of both the enamel and dentine of a tooth. | 0 | Colloidal Chemistry |
Pure bismuth is a semimetal, containing a small band gap, which leads to it having a relatively high conductivity ( at 20 °C). When the bismuth is doped with antimony, the conduction band decreases in energy and the valence band increases in energy. At an antimony concentration of 4%, the two bands intersect, forming a Dirac point (which is defined as a point where the conduction and valence bands intersect). Further increases in the concentration of antimony result in a band inversion, in which the energy of the valence band becomes greater than that of the conduction band at specific momenta. Between Sb concentrations of 7 and 22%, the bands no longer intersect, and the BiSb becomes an inverted-band insulator. It is at these higher concentrations of Sb that the band gap in the surface states vanishes, and the material thus conducts at its surface. | 1 | Solid-state chemistry |
Solid foams are a class of lightweight cellular engineering materials. These foams are typically classified into two types based on their pore structure: open-cell-structured foams (also known as reticulated foams) and closed-cell foams. At high enough cell resolutions, any type can be treated as continuous or "continuum" materials and are referred to as cellular solids, with predictable mechanical properties.
Open-cell foams can be used to filter air. For example, a foam embedded with catalyst has been shown to catalytically convert formaldehyde to benign substances when formaldehyde polluted air passes through the open cell structure.
Open-cell-structured foams contain pores that are connected to each other and form an interconnected network that is relatively soft. Open-cell foams fill with whatever gas surrounds them. If filled with air, a relatively good insulator results, but, if the open cells fill with water, insulation properties would be reduced. Recent studies have put the focus on studying the properties of open-cell foams as an insulator material. Wheat gluten/TEOS bio-foams have been produced, showing similar insulator properties as for those foams obtained from oil-based resources. Foam rubber is a type of open-cell foam.
Closed-cell foams do not have interconnected pores. The closed-cell foams normally have higher compressive strength due to their structures. However, closed-cell foams are also, in general more dense, require more material, and as a consequence are more expensive to produce. The closed cells can be filled with a specialized gas to provide improved insulation. The closed-cell structure foams have higher dimensional stability, low moisture absorption coefficients, and higher strength compared to open-cell-structured foams. All types of foam are widely used as core material in sandwich-structured composite materials.
The earliest known engineering use of cellular solids is with wood, which in its dry form is a closed-cell foam composed of lignin, cellulose, and air. From the early 20th century, various types of specially manufactured solid foams came into use. The low density of these foams makes them excellent as thermal insulators and flotation devices and their lightness and compressibility make them ideal as packing materials and stuffings.
An example of the use of azodicarbonamide as a blowing agent is found in the manufacture of vinyl (PVC) and EVA-PE foams, where it plays a role in the formation of air bubbles by breaking down into gas at high temperature.
The random or "stochastic" geometry of these foams makes them good for energy absorption, as well. In the late 20th century to early 21st century, new manufacturing techniques have allowed for geometry that results in excellent strength and stiffness per weight. These new materials are typically referred to as engineered cellular solids. | 0 | Colloidal Chemistry |
Copper(II) chloride is a mild oxidant. It starts to decompose to copper(I) chloride and chlorine gas around and is completely decomposed near :
The reported melting point of copper(II) chloride of is a melt of a mixture of copper(I) chloride and copper(II) chloride. The true melting point of can be extrapolated by using the melting points of the mixtures of CuCl and . Copper(II) chloride reacts with several metals to produce copper metal or copper(I) chloride (CuCl) with oxidation of the other metal. To convert copper(II) chloride to copper(I) chloride, it can be convenient to reduce an aqueous solution with sulfur dioxide as the reductant: | 1 | Solid-state chemistry |
The energy of the hyperfine electrical interaction between the charge distribution of the core and the extranuclear static electric field can be extended to multipoles. The monopole term only causes an energy shift and the dipole term disappears, so that the first relevant expansion term is the quadrupole term:
: ij=1;2;3
This can be written as a product of the quadrupole moment and the electric field gradient . Both [tensor]s are of second order. Higher orders have too small effect to be measured with PAC.
The electric field gradient is the second derivative of the electric potential at the core:
becomes diagonalized, that:
The matrix is free of traces in the main axis system (Laplace equation)
Typically, the electric field gradient is defined with the largest proportion and :
The energy difference between two substates, and , is given by:
The quadrupole frequency is introduced.
The formulas in the colored frames are important for the evaluation:
The publications mostly list . as elementary charge and as Planck constant are well known or well defined.
The nuclear quadrupole moment is often determined only very inaccurately (often only with 2-3 digits).
Because can be determined much more accurately than , it is not useful to specify only because of the error propagation.
In addition, is independent of spin! This means that measurements of two different isotopes of the same element can be compared, such as Hg(5/2−), Hg(5/2−) and Hg(9/2−). Further, can be used as finger print method.
For the energy difference then follows:
If , then:
with:
For integer spins applies:
: und
For half integer spins applies:
: und
The perturbation factor is given by:
With the factor for the probabilities of the observed frequencies:
As far as the magnetic dipole interaction is concerned, the electrical quadrupole interaction also induces a precision of the angular correlation in time and this modulates the quadrupole interaction frequency. This frequency is an overlap of the different transition frequencies . The relative amplitudes of the various components depend on the orientation of the electric field gradient relative to the detectors (symmetry axis) and the asymmetry parameter . For a probe with different probe nuclei, one needs a parameter that allows a direct comparison: Therefore, the quadrupole coupling constant independent of the nuclear spin is introduced. | 1 | Solid-state chemistry |
George Blasse (28 August 1934 – 30 December 2020) was a Dutch chemist. He was a professor of solid-state chemistry at Utrecht University for most of his career.
Blasse was born on 28 August 1934 in Amsterdam. He studied chemistry at the University of Amsterdam. In 1964 he obtained his PhD under E.W. Gorter at Leiden University with a dissertation titled: Chrystal chemistry and some magnetic properties of mixed metal oxides with spinel structure. From 1960 to 1970 Blasse was employed by the Philips Natuurkundig Laboratorium. In 1970 he was appointed as professor of solid-state chemistry at Utrecht University. He retired in 1996.
During his career he performed research into luminescent materials. He discovered the phosphor that made white light LEDs possible.
Blasse was elected a member of the Royal Netherlands Academy of Arts and Sciences in 1982. In 1992 he was awarded the Academy's Gilles Holst Medal. Blasse was elected a member of the Academia Europaea in 1993. In 1996 he was made a Knight in the Order of the Netherlands Lion.
After his retirement he moved to Munich, Germany. He died there on 30 December 2020, aged 86. After his death the ECS Journal of Solid State Science and Technology had a focus issue in his honor. | 1 | Solid-state chemistry |
Aquasomes form a three-layered structure, made of a polyhydroxy oligomer coated core upon which the drug is loaded. The biochemically active molecules are able to interact with the coated core through different Van der Waal forces, entropic forces, and ionic and non-covalent bonds. The structure of aquasomes enables them to carry a variety of substrates, facilitating applications such as protein and peptide delivery and protection, and the delivery of nucleic acids for gene therapy applications. The tri-layer formulation is attributed to several drug delivery properties of the aquasome.
Aquasomes’ solid core, made of ceramic or polymeric material, is attributed to the structural stability of the nanoparticle itself, and can result in improved solubility and biocompatibility of the drug. Different core designs have also been shown to affect the controlled release properties of the drug molecule. A commonly used core material is the ceramic calcium phosphate, which naturally occurs in the body. Hydroxyapatite, which is found in bone, is another commonly used core material. Hydroxyapatite cores have been shown to contribute to targeted delivery of encapsulated hepatitis B antigens intracellularly. However, the ability to target aquasomes to specific cells or tissues has not been explored beyond intracellular delivery of aquasome payloads.
The second layer of aquasomes is the carbohydrate coat, onto which the drug is adsorbed. Due to carbohydrate’s action as a dehydroprotectant, it has been shown to function as a natural stabilizer to preserve the conformation and shape of soft drugs. The dehydroprotectant property of the carbohydrate coat also enables protection of the biochemically active molecule from dehydration and protein degradation.
The size of aquasomes ranges from 60 to 300 nanometers, hence their characterization as a nanoparticle drug carrier. The nanoscale of aquasomes gives them a high surface area to volume ratio. The smaller the core, the higher the surface area to volume ratio, which increases the drug loading capacity of the aquasome. Aquasomes possess water-like properties due to the presence of the carbohydrate coating, enabling them to protect and preserve fragile biological molecules. The size of aquasome particles increases as a function of the ratio between the concentration of the core to the coat due to the availability of free surface core particles for the coating material.
The self-assembly process of aquasomes into their tri-layer structure is achieved by non-covalent and ionic bonds, along with physicochemical properties of their components. Calcium phosphate nanoparticles are formed before the carbohydrate coat is adsorbed onto the surface of the core through electrostatic interactions. Layers are then added to the structure to achieve desired size, while crosslinked polymers aid in further stabilization. The sonication process during the reaction of disodium hydrogen phosphate and calcium chloride to prepare calcium phosphate impacts the self-assembly process of aquasomes by increasing surface free energy of the core prepared. This assembly process allows the design of aquasomes for specific drug delivery applications.
The structure of aquasomes can contribute to controlled drug release, drug stability, and intracellular targeting of the drug. Other commonly used nanoparticle drug delivery systems include niosomes, liposomes, and vesosomes, the compositions of which contribute to different properties of the resulting nanoparticle compared to aquasomes. Niosomes are composed of non-ionic surfactants and bilayer structures, allowing them to encapsulate hydrophilic and hydrophobic drugs. Liposomes are composed of phospholipids and a similar bilayer structure to niosomes, and can deliver toxic or poorly soluble drugs. Vesosomes have a core-shell structure similar to aquasomes, but contain a lipid bilayer core and a polymer shell, while aquasomes consist of a ceramic or polymeric core and a carbohydrate coat. Vesosomes are used for encapsulating imaging agents and aiding in imaging techniques such as MRI. | 0 | Colloidal Chemistry |
Kauzlarich received a Bachelor of Science in chemistry from the College of William & Mary in 1980. Although originally planning to become a high school chemistry teacher, her collegiate mentors encouraged her to pursue graduate studies in chemistry. She did her graduate studies with Bruce A. Averill at Michigan State University, receiving a chemistry PhD in 1985. During her graduate studies, Kauzlarich primarily worked on the synthesis, development and study of low-dimensional conducting materials derived from the layered material FeOCl. Her characterization methods of these new materials included x-ray absorption spectroscopy and neutron diffraction. From 1985 to 1987, Kauzlarich was a postdoctoral fellow with John Corbett at Iowa State University where she explored the synthesis and bonding characteristics of novel extended condensed metal chain compounds built on [R6IZ] (R=Ln, Y, Sc; Z=B,C,N, C) clusters.
Kauzlarich joined the department of Chemistry at the University of California, Davis in 1987. She was promoted to associate professor in 1992, promoted to full professor in 1996, and in 2014, distinguished professor. She was the Maria Goeppert Mayer Distinguished Scholar at Argonne National Laboratory from 1997 to 1998, Faculty Assistant to the Dean of Mathematical and Physical Sciences from 2010 to 2013, and chair of the chemistry department from 2013 to 2016.
Kauzlarich served as an associate editor for the journal Chemistry of Materials from 2006 to 2021 and is a deputy editor for Science Advances (2022-). She has been a member of the editorial advisory board for the handbook Physics and Chemistry of the Rare Earths since 2002. She was an associate editor for the Journal of Solid State Chemistry from 2000 to 2005, and as a member of the advisory review board of the Research Corporation for Science Advancement from 2004 to 2010. Kauzlarich is the editor of the book Chemistry, structure, and bonding of Zintl phases and ions.
Kauzlarich is an advocate for diversity in the chemistry community and is well known for her personal commitment to mentorship. Throughout her career she has built and continues to support a pipeline of women and underrepresented students in the field of chemistry from high school through graduate study. During her career, Kauzlarichs mentorship strategies have expanded to help support a culture shift in her community through discussions, workshops, and development of new initiatives. One of her initiatives has been the development of the American Chemical Society Summer Educational Experience for the Economically Disadvantaged Program (SEED) program which she established at UC Davis in 1988. For her mentorship of students, Kauzlarich was recognized by Barack Obama with the 2009 Presidential Award for Excellence in Science, Mathematics, and Engineering Mentoring. At UC Davis, she serves as committee member for the Center for the Advancement of Multicultural Perspectives on Science, part of the UC Davis "ADVANCE" initiative. She is also an active member of the steering committees at UC Davis including the Womens Research and Resource Center and Women in Science and Engineering. | 1 | Solid-state chemistry |
Keszler’s research group focuses on the synthesis and study of inorganic molecules and materials related to next-generation electronic and energy devices. Their discovery and development on water-based chemistries for high-quality films demonstrates the leading results in the field of ultra small-scale dense nanopatterning and tunneling electronic devices. One of their recent publication in 2014 focuses on amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) which are widely used in active-matrix organic light-emitting diode (AMOLED) applications, as well as active-matrix liquid crystal display (AMLCD) backplane applications. AMOLED is a display technology used in smartwatches, mobile devices, laptops, and televisions. OLED describes a specific type of think-film-display technology. TFT is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer as well as the dielectric layer and metallic contacts over a supporting but non-conducting substrate. Keszler's group discovered that indium gallium zinc oxide (IGZO) is a material-of choice for the replacement of hydrogenated silicon (a-Si:H) that is currently used in switching TFTs. IGZO comparing to hydrogenated silicon material has incredible advantages in the cost of synthesis.
Another aspect of Keszler's research demonstrates synthesis of functional inorganic materials such as high-quality inorganic films and ordered nanostructures with single-digit nanometer resolution in solution. In 2013, they came up with successful aqueous-based synthesis of ultrathin films of TiO and aqueous-derived AlO(PO)(AlPO) films and were able to assemble these materials into nanolaminates. Keszler group’s successful synthesis of flat cluster [Al(μ-OH)(μ-OH)(HO)] using an electrochemical method and treating aqueous aluminum nitrate solution with a zinc metal powder at room temperature demonstrate the importance of his work to the field of water-based material synthesis. From that, they focused more on developing aqueous-based synthesis of couple other compounds such as [Sc(μ-OH)(HO)(NO)](NO)] from an aqueous scandium nitrate solution. | 1 | Solid-state chemistry |
* HWK-Fellowship, Hanse-Wissenschaftskolleg, Delmenhorst, Germany (2021)
* Research Excellence in Materials Chemistry, Chemical Institute of Canada (2021)
* Parex Innovation Fellow, University of Calgary (2020)
* Peak Scholar, University of Calgary (2019)
* Keith Laidler Award, Canadian Society for Chemistry, The Chemical Institute of Canada (2016)
* Outstanding Invention of 2013, University of Maryland College Park, USA (2013)
* German Academic Exchange Service (DAAD) Guest Professor, Faculty of Engineering, University of Kiel, Germany (2005)
* Alexander von Humboldt (AvH) PDF scholarship, Chair for Sensors and Solid-State Ionics, Faculty of Engineering, University of Kiel, Germany (2002) | 1 | Solid-state chemistry |
Other possible deposition methods include methods utilizing particle self-assembly by solvent evaporation, doctor blade, chemical vapor deposition and transfer printing. Some of these methods like solvent evaporation are extremely simple but produce low-quality films. Other methods such as the chemical vapor deposition are effective for certain types of particles and substrates but are limited in particle types that can be used and require heavier instrumentation investments. Also hybrid methods such as combining self-assembly to Langmuir-Blodgett have been used. | 0 | Colloidal Chemistry |
Arthur W. Thomas, then an instructor in Food Chemistry at Columbia University, volunteered for military service in the spring of 1917 and was mustered in as a First Lieutenant in the newly formed Sanitary Corps in the U.S. National Army in September 1917. He was assigned to the Food and Nutrition Section or Division of the Sanitary Corps under the command of the Surgeon General. Thomas took part in food surveys at army cantonments in the Northeast and also served in the Office of the Surgeon General in Washington. The officers in the Food and Nutrition Section included those who in civilian life were professors in chemistry and biochemistry.
In January 1918 Thomas was promoted to captain; In March 1918 he was sent to England where he participated in food surveys at US Army cantonments in southern England.
From April 1918 to June 1919 Thomas served in France where he was stationed in Base Section No. 1 in the northwest, in the front lines with the 26th (Yankee) and 89th (Middle West) Divisions in the Toul sector, and at the Sanitary Corps laboratory station at Dijon where he worked with other offices in the updating of army food rations. In the summer of 1918 he also gave instruction at the Second Army Corps school. In June 1919 he was involved in inspections of the adequacies of ship bakeries and galleys of three dozen Army and Navy troop transports returning thousands of men to America. | 0 | Colloidal Chemistry |
Titanium's propensity to form an oxide layer on its surface prevents corrosion of surfaces that are in contact with human tissues because the surface oxides minimize diffusion of metal ions from the bulk material to the surface. When titanium gains a coating to make it more bioactive, it can turn the already biocompatible titanium surface into an interface able to enhance osteoblast adhesion and able to promote osseointegration. Today, research is heavily focused on improving the success rate of integration and uses an understanding of the natural process of bone growth and repair to create coatings that will enhance the surface finish and surface properties of the implant. These adjustments allow the artificial structure to mimic biological materials and to gain acceptance into the body with fewer negative side effects.
A 3-year clinical and radiographic study found implants in humans coated by nanocrystalline hydroxylapatite (HA) to support osseointegration. The nanocrystalline HA was developed with a large rough surface of interconnecting pores between 10 and 20 nm of the silica matrix gel, resulting in a porous bone structure. Mean rates of marginal bone loss were insignificant and the periotest values were indicative of a solid osseointegration.
In effect, the pores are structured in such a way that they are able hold onto the proteins on the biomaterial's surface. Ideally, this allows the body to engage in self-repair in that the synthetic HA is recognized as a like-nanomaterial in which live tissues may develop
Titanium foams can be coated with HA through various methods including plasma spraying, sol-gel and electrophoretic deposition. It has been shown that HA-coated titanium exhibits increased interfacial strength in comparison to titanium foams without the coating. In an effort to enhance bone in-growth, Spoerke et al. developed a method for growing organoapatites on titanium implants. Organoapatites may assist in-bone in-growth at the implant interface. The foams were manufactured using a modified HIP process, which exploits the allotropic nature of titanium to create higher porosity foams. Previous in vitro experimentation with the organoapatite-titanium foam held promising results including the possibility that ingrown tissue within these coated pores will improve the lifetime use of the foam through reduction of stress-shielding effects. | 0 | Colloidal Chemistry |
Turbidity is commonly treated using a settling or filtration process, or both settling and filtration. Depending on the application, flocculants may be dosed into the water stream to increase the effectiveness of the settling or filtration process. Potable water treatment and municipal wastewater plants often remove turbidity with a combination of settling tanks, granular media filtration, and clarifiers.
In-situ water treatment or direct dosing for the treatment of turbidity is common when the affected water bodies are dispersed (i.e. there are numerous water bodies spread out over a geographical area, such as small drinking water reservoirs), when the problem is not consistent (i.e. when there is turbidity in a water body only during and after the wet season) or when a low cost solution is required. In-situ treatment of turbidity involves the addition of a reagent, generally a flocculant, evenly dispensed over the surface of the body of water. The flocs then settle at the bottom of the water body where they remain or are removed when the water body is drained. This method is commonly used at coal mines and coal loading facilities where stormwater collection ponds have seasonal issues with turbidity. A number of companies offer portable treatment systems for in-situ water treatment or direct dosing of reagents. | 0 | Colloidal Chemistry |
There are two general types of methods for preparing miniemulsions:
* High-energy methods - For the high-energy methods, the shearing proceeds usually via exposure to high power ultrasound of the mixture or with a high-pressure homogenizer, which are high-shearing processes.
* Low-energy methods - For the low-energy methods, the water-in-oil emulsion is usually prepared and then transformed into an oil-in-water miniemulsion by changing either composition or temperature. The water-in-oil emulsion is diluted dropwise with water to an inversion point or gradually cooled to a phase inversion temperature. The emulsion inversion point and phase inversion temperature cause a significant decrease in the interfacial tension between two liquids, thereby generating very tiny oil droplets dispersed in the water.
Miniemulsions are kinetically stable but thermodynamically unstable. Oil and water are incompatible in nature, and the interface between them is not favored. Therefore, given a sufficient amount of time, the oil and water in miniemulsions separate again. Various mechanisms such as gravitational separation, flocculation, coalescence, and Ostwald ripening result in instability. In an ideal miniemulsion system, coalescence and Ostwald ripening are suppressed thanks to the presence of the surfactant and co-surfactant. With the addition of surfactants, stable droplets are then obtained, which have typically a size between 50 and 500 nm. | 0 | Colloidal Chemistry |
;YL 6000 series:
* YL6000 - NOR gate (red) ("NOR")
* YL6001 - Emitter follower (yellow) ("EF")
* YL6004 - High power output (Double-sized module) ("HP")
* YL6005, YL6005/00 - Counter unit (triple binary) ("3C") (violet)
* YL6005/05 - Single divide by 2 counter (violet) ("1C")
* YL6006 - Timer (brown) ("TU")
* YL6007 - Chassis ("CU")
* YL6008 - Medium power output (orange) ("MP")
* YL6009 - Low power output (white) ("LP")
* YL6010 - Photo-electric detector head ("PD")
* YL6011 - Photo-electric lamp head ("PL")
* YL6012 - Twin 2-input NOR gate (black) ("2.2 NOR")
;YL 6100 series:
* YL6101 - Rectifier unit, 3…39V 1A
* YL6102 - Rectifier unit, 3…39V 5A
* YL6103/00 - Regulator unit, 6…30V 250mA
* YL6103/01 - Regulator unit, 1…6V 250mA
* YL6104 - Longitudinal link for regulator unit
* YL6105 - Regulator unit, 6V 150mA
;88930 Relay series:
Used to control relays using variable-length pulse sequences (as with telephone pulse dialing).
* 88930/30 - Input/Output unit<br>Filters an input pulse string and can drive two command circuits and two relay units<br>Contains 1×/48, 2×/51, and 2×/57.
* 88930/33 - Primary pulse counting unit (dual command)<br>Can trigger two different signals via two different pulse sequences. The number of pulses that will trigger each command is configurable.
* 88930/36 - Dual command unit<br>Adds two additional commands to the /33.
* 88930/37 - Quad command unit<br>Adds four additional commands to the /33.
* 88930/39 - Output unit<br>Can drive two command circuits (in /36 or /37 command units) plus two /60 relay units.<br>Contains 2×/51 and 2×/57.
* 88930/42 - Empty unit<br>For adding custom circuitry. Comprises an empty housing, connector, and blank circuit board.
* 88930/48 - Pulse shaper unit for /33 (no housing)
* 88930/51 - Command preparation unit (no housing)<br>For providing input to command units.
* 88930/54 - Reset unit
* 88930/57 - Relay amplifier unit (no housing)<br>For driving a low-impedance relay such as the /60 relay block unit.
* 88930/60 - Relay block unit<br>Double-pole, double throw 250V 2A relay. Accepts a /57 relay amplifier unit.
* 88930/64 - Power supply unit<br>Provides 280V 45mA, 150V 2mA, 24V 750mA, and 15V 120mA. | 1 | Solid-state chemistry |
Gérard Férey (14 July 1941 – 19 August 2017) was a French chemist who was a member of the French Academy of Sciences and a professor at the University of Versailles Saint-Quentin-en-Yvelines. He specialized in the physical chemistry of solids and materials. He focused on the crystal chemistry of inorganic fluorides and on porous solids.
In September 2010, he received the CNRS Gold medal, the highest French scientific distinction. | 1 | Solid-state chemistry |
The original theory from 1927 of nucleation in nanoparticle formation was Classical Nucleation Theory (CNT). It was believed that the changes in particle size could be described by burst nucleation alone. In 1950, Viktor LaMer used CNT as the nucleation basis for his model of nanoparticle growth. There are three portions to the LaMer model: 1. Rapid increase in the concentration of free monomers in solution, 2. fast nucleation of the monomer characterized by explosive growth of particles, 3. Growth of particles controlled by diffusion of the monomer. This model describes that the growth on the nucleus is spontaneous but limited by diffusion of the precursor to the nuclei surface. The LaMer model has not been able to explain the kinetics of nucleation in any modern system. | 0 | Colloidal Chemistry |
Bismuth antimonides, Bismuth-antimonys, or Bismuth-antimony alloys, (BiSb) are binary alloys of bismuth and antimony in various ratios.
Some, in particular BiSb, were the first experimentally-observed three-dimensional topological insulators, materials that have conducting surface states but have an insulating interior.
Various BiSb alloys also superconduct at low temperatures, are semiconductors, and are used in thermoelectric devices.
Bismuth antimonide itself (see box to right) is sometimes described as BiSb. | 1 | Solid-state chemistry |
Nanocomposites that can respond to an external stimulus are of increased interest due to the fact that, because of the large amount of interaction between the phase interfaces, the stimulus response can have a larger effect on the composite as a whole. The external stimulus can take many forms, such as a magnetic, electrical, or mechanical field. Specifically, magnetic nanocomposites are useful for use in these applications due to the nature of magnetic material's ability to respond both to electrical and magnetic stimuli. The penetration depth of a magnetic field is also high, leading to an increased area that the nanocomposite is affected by and therefore an increased response. In order to respond to a magnetic field, a matrix can be easily loaded with nanoparticles or nanorods The different morphologies for magnetic nanocomposite materials are vast, including matrix dispersed nanoparticles, core-shell nanoparticles,
colloidal crystals, macroscale spheres, or Janus-type nanostructures.
Magnetic nanocomposites can be utilized in a vast number of applications, including catalytic, medical, and technical. For example, palladium is a common transition metal used in catalysis reactions. Magnetic nanoparticle-supported palladium complexes can be used in catalysis to increase the efficiency of the palladium in the reaction.
Magnetic nanocomposites can also be utilized in the medical field, with magnetic nanorods embedded in a polymer matrix can aid in more precise drug delivery and release. Finally, magnetic nanocomposites can be used in high frequency/high-temperature applications. For example, multi-layer structures can be fabricated for use in electronic applications. An electrodeposited Fe/Fe oxide multi-layered sample can be an example of this application of magnetic nanocomposites.
In applications such as power micro-inductors where high magnetic permeability is desired at high operating frequencies. The traditional micro-fabricated magnetic core materials see both decrease in permeability and high losses at high operating frequency. In this case, magnetic nano composites have great potential for improving the efficiency of power electronic devices by providing relatively high permeability and low losses. For example, As Iron oxide nano particles embedded in Ni matrix enables us to mitigate those losses at high frequency. The high resistive iron oxide nanoparticles helps to reduce the eddy current losses where as the Ni metal helps in attaining high permeability. DC magnetic properties such as Saturation magnetization lies between each of its constituent parts indicating that the physical properties of the materials can be altered by creating these nanocomposites. | 1 | Solid-state chemistry |
Salt-concrete (or salzbeton) is a building material that is used to reduce the water inflow in mining shafts in salt mines. It is composed of 16% cement, 39% halite, 16% limestone powder, 14% water and 15% sand. | 1 | Solid-state chemistry |
Surfactants are composed of a polar head group that is hydrophilic and a nonpolar tail group that is hydrophobic. The head groups can be anionic, cationic, zwitterionic, or nonionic. The tail group can be a hydrocarbon, fluorocarbon, or a siloxane. Extensive variation in the surfactant’s solution and interfacial properties is allowed through different molecular structures of surfactants.
Hydrophobic coagulation occurs when a positively charged solution is added with a sodium alkyl sulfate. The coagulation value is smaller when the alkyl chain length of the coagulator is longer. Hydrophobic coagulation occurs when a negatively charged solution contains a cationic surfactant. The coulomb attraction between the head groups and surface competes with the hydrophobic attraction for the entire tail in a favorable manner. | 0 | Colloidal Chemistry |
The stabilization of a foam is caused by van der Waals forces between the molecules in the foam, electrical double layers created by dipolar surfactants, and the Marangoni effect, which acts as a restoring force to the lamellae.
The Marangoni effect depends on the liquid that is foaming being impure. Generally, surfactants in the solution decrease the surface tension. The surfactants also clump together on the surface and form a layer as shown below.
For the Marangoni effect to occur, the foam must be indented as shown in the first picture. This indentation increases local surface area. Surfactants have a larger diffusion time than the bulk of the solution—so the surfactants are less concentrated in the indentation.
Also, surface stretching makes the surface tension of the indented spot greater than the surrounding area. Consequentially—since diffusion time for the surfactants is large—the Marangoni effect has time to take place. The difference in surface tension creates a gradient, which instigates fluid flow from areas of lower surface tension to areas of higher surface tension. The second picture shows the film at equilibrium after the Marangoni effect has taken place.
Curing a foam solidifies it, making it indefinitely stable at STP. | 0 | Colloidal Chemistry |
PPS, available as PPS Silent Surfactant from Expedeon, is the abbreviation for sodium 3-(4-(1,1-bis(hexyloxy)ethyl)pyridinium-1-yl)propane-1-sulfonate. This acetalic detergent is split under acidic conditions into hexanol and the zwitterionic 3-acetyl-1-(3-sulfopropyl)pyridinium. | 0 | Colloidal Chemistry |
Uranium dioxide is produced by reducing uranium trioxide with hydrogen.
:UO + H → UO + HO at 700 °C (973 K)
This reaction plays an important part in the creation of nuclear fuel through nuclear reprocessing and uranium enrichment. | 1 | Solid-state chemistry |
Aggregate exposures to consumers (direct and indirect dermal contact, ingestion, and inhalation) have been estimated to be 1.42 ug/Kg bw/day.
Calcium xylene sulfonate and sodium cumene sulfonate have been shown to cause temporary, slight eye irritation in animals. Studies have not found hydrotropes to be mutagenic, carcinogenic or have reproductive toxicity. | 0 | Colloidal Chemistry |
Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made during partial neutralization of diprotic or polyprotic acids. A half-neutralization occurs due to the remaining of replaceable hydrogen atoms from the partial dissociation of weak acids that have not been reacted with hydroxide ions () to create water molecules. | 1 | Solid-state chemistry |
Aggregation in colloidal dispersions (or stable suspensions) has been characterized by the degree of interparticle attraction. For attractions strong relative to the thermal energy (given by kT), Brownian motion produces irreversibly flocculated structures with growth rates limited by the rate of particle diffusion. This leads to a description using such parameters as the degree of branching, ramification or fractal dimensionality. A reversible growth model has been constructed by modifying the cluster-cluster aggregation model with a finite inter-particle attraction energy.
In systems where forces of attraction forces are buffered to some degree, a balance of forces leads to an equilibrium phase separation, that is particles coexist with equal chemical potential in two distinct structural phases. The role of the ordered phase as an elastic colloidal solid has been evidenced by the elastic (or reversible) deformation due to the force of gravity. This deformation can be quantified by the distortion of the lattice parameter, or inter-particle spacing. | 0 | Colloidal Chemistry |
The above-mentioned dipolar interaction can be measured directly, e.g. between pairs of heteronuclear spins like C/N in many organic compounds. Furthermore, the strength of the dipolar interaction modulates parameters like the longitudinal relaxation time or the spin diffusion rate which therefore can be examined to obtain structural information. E.g. H spin diffusion has been measured providing rich structural information. | 1 | Solid-state chemistry |
Microelectrophoresis is a method of studying electrophoresis of various dispersed particles using optical microscopy. This method provides image of moving particles, which is its unique advantage. e.g. observation of RBCs, neutrophiles and bacteria. This type of electrophoresis is carried out in a closed medium with critical observations made by focusing and adjusting the lens of the microscope.
Complexity of this method is associated with electro-osmosis generated by electric field influence on the double layers of the sample cell walls. In the usually used closed cells, this creates Poiseuille type back flow, leading to parabolic velocity profile. There are two stationary layers, where fluid does not move. Position of these stationary layer regarding cell walls depends on the cell geometry. It is possible to focus microscope on this stationary layers and observe particles motion not affected with electro-osmosis.
The second complexity comes from necessity of diluting sample, if it was initially concentrated. Concentration must be sufficiently low for observing individual particles.
Measurement in the low polar fluids present additional problems. These systems have low electrical conductivity and low dielectric permittivity. Electrophoretic mobility is low and this requires high electric field, by factor 10 and higher.
Details of this method are presented in IUPAC Technical Report prepared by a group of most known world experts on the electrokinetic phenomena. | 0 | Colloidal Chemistry |
The ratio of Fe to Fe within a rock determines, in part, the silicate mineral assemblage of the rock. Within a rock of a given chemical composition, iron enters minerals based on the bulk chemical composition and the mineral phases which are stable at that temperature and pressure. Iron may only enter minerals such as pyroxene and olivine if it is present as Fe; Fe cannot enter the lattice of fayalite olivine and thus for every two Fe ions, one Fe is used and one molecule of magnetite is created.
In chemically reduced rocks, magnetite may be absent due to the propensity of iron to enter olivine, and wüstite may only be present if there is an excess of iron above what can be used by silica. Thus, wüstite may only be found in silica-undersaturated compositions which are also heavily chemically reduced, satisfying both the need to remove all Fe and to maintain iron outside of silicate minerals.
In nature, carbonate rocks, potentially carbonatite, kimberlites, carbonate-bearing melilitic rocks, and other rare alkaline rocks may satisfy these criteria. However, wüstite is not reported in most of these rocks in nature, potentially because the redox state necessary to drive magnetite to wüstite is so rare. | 1 | Solid-state chemistry |
Because of the properties of europium(II) oxide, thin layers of the oxide deposited on silicon are being studied for use as spin filters. Spin filter materials only allow electrons of a certain spin to pass, blocking electrons of the opposite spin. | 1 | Solid-state chemistry |
In experiments by Yunteng Qu et al., dangling bonds on graphene oxide were used to bind single metal atoms (Fe, Co, Ni, Cu) for applications in catalysis. Metal atoms were adsorbed by oxidizing metal from a foam and coordinating the metal ions to the dangling bonds on the oxygen of the graphene oxide. The resulting catalyst had a high density of catalytic centers and showed high activity, comparable to other non-noble metal catalysts in oxygen reduction reactions while maintaining stability in a wide range of electrochemical potential, comparable to Pt/C electrodes. | 1 | Solid-state chemistry |
This Table, reports the three main Miedema parameters for the elements of the Periodic table for whom the model is applicable.
These are original parameters which are after page 24 of the book after F.R. De Boer, R. Boom, W.C.M. Mattens, A.R. Miedema and A.K. Niessen Cohesion in Metals. Transition Metal Alloys (1988),
The above list of parameters should be considered as a starting point, which could yield such data (results after Fortran program made available by Emre Sururi Tasci
improved data may be found in more recent publications; possibly, in the near future, improvement or insisight of these data could be provided by the extended Calphad databases open collections available at NIMS For instance for Fe-X binary phase diagrams, a list of available databases is as presented in this link [https://cpddb.nims.go.jp/cpddb/fe-elem/fe_index.htm] and more specifically in this table: | 1 | Solid-state chemistry |
Michael O’Keeffe was born in Bury St Edmunds, Suffolk, England, on the 3rd April, 1934. He was one of four children born to Dr. E. Joseph O’Keeffe, an immigrant from Ireland, and his mother Marjorie G. O’Keeffe (née Marten). From 1942 to 1951 he attended Prior Park College (Bath) and then from 1951 to 1957 the University of Bristol: B.Sc. in chemistry (1954), Ph.D. (1958, mentor Frank S. Stone). He spent 1958-1959 at Philips Natuurkundig Laboratorium (group of Evert W. Gorter) then did postdoctoral research at Indiana University (mentor Walter J. Moore). 1960-62. He subsequently became a U. S. citizen. | 1 | Solid-state chemistry |
Using a single body-centered cubic colloidal crystal, the occurrence of Kossel lines in diffraction patterns were used to monitor the initial nucleation and subsequent motion caused distortion of the crystal. Continuous or homogeneous deformations occurring beyond the elastic limit produce a flowing crystal, where the nucleation site density increases significantly with increasing particle concentration. Lattice dynamics have been investigated for longitudinal as well as transverse modes. The same technique was used to evaluate the crystallization process near the edge of a glass tube. The former might be considered analogous to a homogeneous nucleation event—whereas the latter would clearly be considered a heterogeneous nucleation event, being catalyzed by the surface of the glass tube. | 0 | Colloidal Chemistry |
There are suggestions that depletion forces may be a significant contributor in some biological systems, specifically in membrane interactions between cells or any membranous structure. With concentrations of large molecules such as proteins or carbohydrates in the extracellular matrix, it is likely some depletion force effects are observed between cells or vesicles that are very close. However, due to the complexity of most biological systems, it is difficult to determine how much these depletion forces influence membrane interactions. Models of vesicle interactions with depletion forces have been developed, but these are greatly simplified and their applicability to real biological systems is questionable. | 0 | Colloidal Chemistry |
While biodegradable, this class of chemicals may be toxic to life in water at concentrations of less than 1 mg/L. Water downstream of mining operations is often contaminated with xanthates. | 1 | Solid-state chemistry |
In Canada, BVO is currently permitted as a food additive, but only in beverages containing citrus or spruce oils.
In the European Union, BVO is banned from use as a food additive; it was originally banned in the UK and several other European countries in 1970; and any BVO-containing products that may slip through the regulations are pulled from shelves upon discovery. In the EU, beverage companies commonly use glycerol ester of wood rosin or locust bean gum as an alternative to BVO.
In India, standards for soft drinks have prohibited the use of BVO since 1990.
In Japan, the use of BVO as a food additive has been banned since 2010. | 0 | Colloidal Chemistry |
The term magnetic structure of a material pertains to the ordered arrangement of magnetic spins, typically within an ordered crystallographic lattice. Its study is a branch of solid-state physics. | 1 | Solid-state chemistry |
Synthesis of metallic nanofoams may be accomplished through a variety of methods. In 2006, researchers produced metal nanofoams by igniting pellets of energetic metal bis(tetrazolato)amine complexes. Nanofoams of iron, cobalt, nickel, copper, silver, and palladium have been prepared through this technique. These materials exhibit densities as low as 11 mg/cm, and surface areas as high as 258 m/g. These foams are effective catalysts and electrocatalyst supports. Also, metal nanofoams can be made by electrodeposition of metals inside templates with interconnected pores, such as 3D-porous anodic aluminum oxide (AAO). Such method gives nanofoams with an organized structure and allows to control the surface area and porosity of the fabricated material.
A 2016 study discussed a low temperature/pressure microwave solvothermal method for fabricating pure copper, silver, and nickel metal nanofoams. The process claims to be non-hazardous, novel, as well as facile, with an emphasis on its low-waste and low-cost method of manufacturing.
Additionally, a 2020 publication discussed successful synthesis of nanofoam films from silver, gold, copper, and palladium through the use of a modified vacuum thermal evaporation method. | 0 | Colloidal Chemistry |
Ionic micelles are typically very affected by the salt concentration. In ionic micelles the monomers are typically fully ionized, but the high electric field strength at the surface of the micelles will cause adsorption of some proportion of the free counter-ions. In this case a chemical equilibrium process can be assumed between the charged micelles and its constituents, the bile salt monomers, and bound counter-ions :
where is the average aggregation number and is the average degree of counter-ion binding to the micelle. In this case, the Gibbs free energy is given by:
where is the Gibbs energy of micellization and is the free counter-ion concentration at CMC. For large , that is in the limit when then the micelles becomes a true macroscopic phase, the Gibbs free energy is usually approximated by: | 0 | Colloidal Chemistry |
PTC rubber is a silicone rubber which conducts electricity with a resistivity that increases exponentially with increasing temperature for all temperatures up to a temperature where the resistivity grows to infinity. Above this temperature the PTC rubber is an electrical insulator. PTC rubber is made from polydimethylsiloxane (PDMS) loaded with carbon nanoparticles. PTC stands for Positive temperature coefficient. | 1 | Solid-state chemistry |
Alivisatos became president of the University of Chicago on September 1, 2021. He is the 14th president of the University of Chicago, succeeding Robert J. Zimmer who was president from 2006 to 2021. Alivisatos also serves as a John D. MacArthur Distinguished Service Professor in the Department of Chemistry, Pritzker School of Molecular Engineering, and the College. | 1 | Solid-state chemistry |
People who work at fluorochemical production plants and in manufacturing industries that use PFASs in the industrial process can be exposed to PFASs in the workplace. Much of what we know about PFASs exposure and health effects began with medical surveillance studies of workers exposed to PFASs at fluorochemical production facilities. These studies began in the 1940s and were conducted primarily at U.S. and European manufacturing sites. Between the 1940s and 2000s, thousands of workers exposed to PFASs participated in research studies that advanced scientific understanding of exposure pathways, toxicokinetic properties, and adverse health effects associated with exposure.
The first research study to report elevated organic fluorine levels in the blood of fluorochemical workers was published in 1980. It established inhalation as a potential route of occupational PFAS exposure by reporting measurable levels of organic fluorine in air samples at the facility. Workers at fluorochemical production facilities have higher levels of PFOA and PFOS in their blood than the general population. Serum PFOA levels in fluorochemical workers are generally below 20,000 ng/mL but have been reported as high as 100,000 ng/mL, whereas the mean PFOA concentration among non-occupationally exposed cohorts in the same time frame was 4.9 ng/mL. Among fluorochemical workers, those with direct contact with PFASs have higher PFAS concentrations in their blood than those with intermittent contact or no direct PFAS contact. Blood PFAS levels have been shown to decline when direct contact ceases. PFOA and PFOS levels have declined in U.S. and European fluorochemical workers due to improved facilities, increased usage of personal protective equipment, and the discontinuation of these chemicals from production. Occupational exposure to PFASs in manufacturing continues to be an active area of study in China with numerous investigations linking worker exposure to various PFASs. | 0 | Colloidal Chemistry |
Minimum solid area models assume that the load bearing area (cross-sectional area normal to the stress) is the logical basis for modeling mechanical behavior. MSA models assume pore interaction results in reduction of stress. Therefore, the minimum solid areas are the carriers of stress. As a result, predicted mechanical properties fluctuate based on the quantification of the solid area of the foam. For titanium foams consisting of partially sintered powders, the minimum solid area consists of the neck area between powders through the cross-section of cell walls between macropores.
The mathematical relationships in MSA models
are relatively consistent with the Gibson & Ashby model.
However, the MSA models are designed to predict mechanical property parameters over a broader range of porosity levels. Like the Gibson & Ashby models, MSA models were derived assuming idealized (defect-free) structures containing uniform pore shapes, size and distribution. | 0 | Colloidal Chemistry |
A depletion force is an effective attractive force that arises between large colloidal particles that are suspended in a dilute solution of depletants, which are smaller solutes that are preferentially excluded from the vicinity of the large particles. One of the earliest reports of depletion forces that lead to particle coagulation is that of Bondy, who observed the separation or "creaming" of rubber latex upon addition of polymer depletant molecules (sodium alginate) to solution. More generally, depletants can include polymers, micelles, osmolytes, ink, mud, or paint dispersed in a continuous phase.
Depletion forces are often regarded as entropic forces, as was first explained by the established Asakura–Oosawa model. In this theory the depletion force arises from an increase in osmotic pressure of the surrounding solution when colloidal particles get close enough such that the excluded cosolutes (depletants) cannot fit in between them.
Because the particles were considered as hard-core (completely rigid) particles, the emerging picture of the underlying mechanism inducing the force was necessarily entropic. | 0 | Colloidal Chemistry |
* Prix de chimie du solide de la Société chimique de France (Solid State Chemistry award of the Chemical Society of France) (1983)
* Prix Paul Pascal de l’Académie des sciences (Paul Pascal award of the French Academy of Sciences) (1992)
* Prix de l’Institut français du pétrole de l’Académie des sciences (French Institute of Petroleum award of the French Academy of Sciences) (2000)
* Prix Gay-Lussac-Humboldt de la Fondation Alexander von Humboldt (Gay-Lussac-Humboldt award of the Alexander von Humboldt foundation) (2004)
* Prix C.N.R. RAO de l’Académie nationale des sciences de l’Inde ( C.N.R. RAO award of the Indian Academy of Sciences) (2005)
* Grand prix de la Société chimique du Japon (Japan chemical society award) (2008)
* Prix Catalan-Sabatier de la Société royale de chimie espagnole (Catalan-Sabatier award of the Spanish Royal Society of Chemistry) (2008)
* Prix ENI (ENI award) (2009) - for his work on the massive sequestration of CO2 and the explanation of this phenomenon. It develops the Mil-101, a solid which can store CO2.
* CNRS Gold medal (2010)
* Knight of the Legion of Honour
* Officer of the Ordre des Palmes Académiques
* Officer of the National Order of Merit | 1 | Solid-state chemistry |
Self-assembly of nanoscale structures from functional nanoparticles has provided a powerful path to developing small and powerful electronic components. Nanoscale objects have always been difficult to manipulate because they cannot be characterized by molecular techniques and they are too small to observe optically. But with advances in science and technology, there are now many instruments for observing nanostructures. Imaging methods span electron, optical and scanning probe microscopy, including combined electron-scanning probe and near-field opticalscanning probe instruments. Nanostructure characterization tools include advanced optical spectro-microscopy (linear, non-linear, tipenhanced and pump-probe) and Auger and x-ray photoemission for surface analysis. 2D self-assembly monodisperse particle colloids has a strong potential in dense magnetic storage media. Each colloid particle has the ability to store information as known as binary number 0 and 1 after applying it to a strong magnetic field. In the meantime, it requires a nanoscale sensor or detector in order to selectively choose the colloid particle. The microphase separation of block copolymers shows a great deal of promise as a means of generating regular nanopatterns at surfaces. They may, therefore, find application as a means to novel nanomaterials and nanoelectronics device structures. | 0 | Colloidal Chemistry |
Aquasomes can be characterized by a variety of techniques that analyze the properties of their three functional units: the ceramic core, carbohydrate coating, and bioactive drug. Characterization of aquasomes after synthesis is done to gain a better understanding of each of the facets that provide or contribute to their functionality. Analyzing characteristics of aquasomes such as size distribution, the carbohydrate coat-to-core ratio, and electrical potential between the nanoparticles can be important in understanding an aquasome’s function.
Solution precipitation as a core synthesis technique produces homogenous-sized nanoparticles, which can be advantageous in controlling specific physical properties such as surface tension and packing density of the atoms in a crystalline lattice structure. The most common methods of characterizing nanoparticle size distribution and morphology of the core in aquasomes include scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In a study by Kommimeni et al. in 2012, researchers employed TEM to verify that the ceramic particles were spherical and also in the acceptable nano-range for aquasomes. The carbohydrate coating size can also be characterized using SEM and TEM, but a Fourier Transform Infrared Spectroscopy (FTIR) is commonly utilized to check for the presence of the coat. In a study by Kommimeni et al. in 2020, FTIR was used to confirm the presence of the coating by analyzing the IR spectra bands that correspond to the functional groups of either the core or the sugar coat.
The bioactive drug loaded onto the aquasome can be characterized in a variety of ways depending on the molecular classification of the drug. In Kossovsky et al. in 1996, which studied the effect of insulin as the bioactive drug of interest, immunogold labeling was employed. Through this technique, the different binding efficiencies of carbohydrate coatings for insulin were able to be observed.
To characterize the loading of the bioactive drug, it is common to employ mathematical equations that use theoretical estimations for drug concentrations entrapped in the aquasome. One such parameter is entrapment efficiency, which is the amount of drug added that was adsorbed onto aquasomes. Another parameter of interest is drug loading, which is the percentage of the aquasome’s weight that is composed of the drug. In a study done by Kutlehria et al. in 2018, the following equations were used to quantify the entrapment efficiency and drug loading::
Finally, measuring the mechanism of action of the formulated aquasomes is important for understanding their potential therapeutic effect. Several studies have carried out in vitro drug release studies that place the aquasomes in a dissolution media and measure the subsequent release of drug into the solution. By obtaining these values, a release profile of the aquasome can be postulated and further optimizations can be determined for aquasomes to meet specific therapeutic indices or pharmacological outcomes. | 0 | Colloidal Chemistry |
The components interact via non-covalent interactions such as hydrogen bonding, ionic interactions, van der Waals interactions and Π-interactions. These interactions lead to a cocrystal lattice energy that is generally more stable than the crystal structures of the individual components. The intermolecular interactions and resulting crystal structures can generate physical and chemical properties that differ from the properties of the individual components. Such properties include melting point, solubility, chemical stability, and mechanical properties. Some cocrystals have been observed to exist as polymorphs, which may display different physical properties depending on the form of the crystal.
Phase diagrams determined from the "contact method" of thermal microscopy is valuable in the detection of cocrystals. The construction of these phase diagrams is made possible due to the change in melting point upon cocrystallization. Two crystalline substances are deposited on either side of a microscope slide and are sequentially melted and resolidified. This process creates thin films of each substance with a contact zone in the middle. A melting point phase diagram may be constructed by slow heating of the slide under a microscope and observation of the melting points of the various portions of the slide. For a simple binary phase diagram, if one eutectic point is observed then the substances do not form a cocrystal. If two eutectic points are observed, then the composition between these two points corresponds to the cocrystal. | 1 | Solid-state chemistry |
Dincăs research primarily focuses on electrical conductivity of MOFs, which was previously unknown and resulted in a new categorization of such materials with "charge mobility values". His focus is on the exploration of increasing electrical conductivity capacities through the marriage of organic and inorganic materials to assemble hybrid MOF's.
Research includes exploring electrochemical cycling through strongly adhering, electroactive metal–organic framework thin films to vary results, such as multicolored electrochromic responses and transparent to dark behavior. | 1 | Solid-state chemistry |
In the recent years nanocomposites have been designed to withstand high temperatures by the addition of Carbon Dots (CDs) in the polymer matrix. Such nanocomposites can be utilized in environments wherein high temperature resistance is a prime criterion. | 1 | Solid-state chemistry |
*S. Sarkar, B. Chen, C. Zhou, S.N. Shirazi, F. Langer, J. Schwenzel, and V. Thangadurai,* “Synergistic Approach toward Developing Highly Compatible Garnet-Liquid Electrolyte Interphase in Hybrid Solid-State Lithium-Metal Batteries,” Adv. Energy Mater., 13 (8), 2203897 (14 pages) (2023) (cover page)
*T. Boteju, A. M. Abraham, S. Ponnurangam* and V. Thangadurai,* “Theoretical Study on the Role of Solvents in Lithium Polysulfide Anchoring on Vanadium Disulfide Facets for Lithium-Sulfur Batteries,” J. J. Phys. Chem. C. 127 (9), 4416 – 4424 (2023).
*A. Sivakumaran, A.J. Samson, and. V. Thangadurai,* “Progress in Sodium Silicates for All-Solid-State Sodium Batteries — a Review,” Energy Technol. 11, 2201323 (18 pages) (2023).
*A. M. Abraham, T. Boteju, S. Ponnurangam* and V. Thangadurai,* “A Global Design Principle for Polysulfide Electrocatalysis in Lithium-Sulfur Batteries – A Computational Perspective,” Battery Energy, 20220003 (11 pages), (2022).
*V. Thangadurai,* and B. Chen, “Solid Li- and Na-Ion Electrolytes for Next Generation Rechargeable Batteries,” Chem. Mater., 34, 6637–6658 (2022) (Invited John Goodenough at 100 issue).
*A. Ndubuisi, S. Abouali, K. Singh, V. Thangadurai,* “Recent Advances, Practical Challenges and Perspectives of Intermediate Temperature Solid Oxide Fuel Cell Cathodes,” J. Mater. Chem. A, 10, 2196-2227 (2022) (Invited). | 1 | Solid-state chemistry |
Anthony Roy West FRSE, FRSC, FInstP, FIMMM (born 21 January 1947) is a British chemist and materials scientist, and Professor of Electroceramics and Solid State Chemistry at the Department of Materials Science and Engineering at the University of Sheffield. | 1 | Solid-state chemistry |
Xanthate anions also undergo alkylation to give xanthate esters, which are generally stable:
:ROCSK + R′X → ROC(S)SR′ + KX
The C-O bond in these compounds are susceptible to cleavage by the Barton–McCombie deoxygenation, which provides a means for deoxygenation of alcohols.
They can be oxidized to dixanthogen disulfides:
:2 ROCSNa + I → ROC(S)SC(S)OR + 2 NaI
Acylation of xanthates gives alkyl xanthogen esters (ROC(S)SC(O)R') and related anhydrides.
Xanthates bind to transition metal cations as bidentate ligands. The charge-neutral complexes are soluble in organic solvents.
Xanthates are intermediates in the Chugaev elimination process. They can be used to control radical polymerisation under the RAFT process, also termed MADIX (macromolecular design via interchange of xanthates). | 1 | Solid-state chemistry |
Due to its high price and special properties, the use of PVK is limited to special areas. It is used in insulation technology, electrophotography (e.g. in copiers and laser printers), for the fabrication of polymer photonic crystals, for organic light-emitting diodes and photovoltaic devices. In addition, PVK is a well researched component in photorefractive polymers and therefore plays an important role in holography. Another application is the production of cooking-proof copolymers with styrene. | 1 | Solid-state chemistry |
Over his career, Goodenough authored more than 550 articles, 85 book chapters and reviews, and five books, including two seminal works, Magnetism and the Chemical Bond (1963) and Les oxydes des metaux de transition (1973). | 1 | Solid-state chemistry |
For a realistic description of optical processes in solid materials, it is essential to go beyond the simple picture of the optical Bloch equations and to treat many-body interactions that describe the coupling among the elementary material excitations by, e.g., the see article Coulomb interaction between the electrons and the coupling to other degrees of freedom, such as lattice vibrations, i.e., the electron-phonon coupling.
Within a semiclassical approach, where the light field is treated as a classical electromagnetic field and the material excitations are described quantum mechanically, all above mentioned effects can be treated microscopically on the basis of a many-body quantum theory.
For semiconductors the resulting system of equations are known as the semiconductor Bloch equations.
For the simplest case of a two-band model of a semiconductor, the SBEs can be written schematically as
Here is the microscopic polarization and and are the electron occupations in the conduction and valence bands ( and ), respectively, and denotes the crystal momentum.
As a result of the many-body Coulomb interaction and possibly further interaction processes, the transition energy and the Rabi energy both depend on the state of the excited system, i.e., they are functions of the time-dependent polarizations and occupations and , respectively, at all crystal momenta .
Due to this coupling among the excitations for all values of the crystal momentum , the optical excitations in semiconductor cannot be described on the level of isolated optical transitions but have to be treated as an interacting many-body quantum system.
A prominent and important result of the Coulomb interaction among the photoexcitations
is the appearance of strongly absorbing discrete excitonic resonances which show up in the absorption spectra of semiconductors spectrally below the fundamental band gap frequency.
Since an exciton consists of a negatively charged conduction band electron and a positively charged valence band hole (i.e., an electron missing in the valence band) which attract each other via the Coulomb interaction, excitons have a hydrogenic series of discrete absorption lines.
Due to the optical selection rules of typical III-V semiconductors such as Galliumarsenide (GaAs) only the s-states, i.e., 1s, 2s, etc., can be optically excited and detected, see article on Wannier equation.
The many-body Coulomb interaction leads to significant complications since it results in an infinite hierarchy of dynamic equations for the microscopic correlation functions that describe the nonlinear optical response.
The terms given explicitly in the SBEs above arise from a treatment of the Coulomb interaction in the time-dependent Hartree–Fock approximation.
Whereas this level is sufficient to describe excitonic resonances, there are several further effects, e.g., excitation-induced dephasing, contributions from higher-order correlations like excitonic populations and biexcitonic resonances, which require one to treat so-called many-body correlation effects that are by definition beyond the Hartree–Fock level.
These contributions are formally included in the SBEs given above in the terms denoted by .
The systematic truncation of the many-body hierarchy and the development and the analysis of controlled approximations schemes is an important topic in the microscopic theory of the optical processes in condensed matter systems.
Depending on the particular system and the excitation conditions several approximations schemes have been developed and applied.
For highly excited systems, it is often sufficient to describe many-body Coulomb correlations using the second order Born approximation.
Such calculations were, in particular, able to successfully describe the spectra of semiconductor lasers, see article on semiconductor laser theory.
In the limit of weak light intensities, signature of exciton complexes, in particular, biexcitons, in the coherent nonlinear response have been analyzed using the dynamics controlled truncation scheme.
These two approaches and several other approximation schemes can be viewed as special cases of the so-called cluster expansion in which the nonlinear optical response is classified by correlation functions which explicitly take into account interactions between a certain maximum number of particles and factorize larger correlation functions into products of lower order ones. | 1 | Solid-state chemistry |
Mercury(II) iodide displays thermochromism; when heated above 126 °C (400 K) it undergoes a phase transition, from the red alpha crystalline form to a pale yellow beta form. As the sample cools, it gradually reacquires its original colour. It has often been used for thermochromism demonstrations. A third form, which is orange, is also known; this can be formed by recrystallisation and is also metastable, eventually converting back to the red alpha form. The various forms can exist in a diverse range of crystal structures and as a result mercury(II) iodide possesses a surprisingly complex phase diagram. | 1 | Solid-state chemistry |
N-Oleoylsarcosine is a mild surfactant which irritates skin and eyes comparatively little and is therefore used in personal care products such as skin cleansing agents because of its antimicrobial and virucidal properties.
The sarcosine head group of the long-chain amphiphilic N-acylamino acid is responsible for the formation of chelate-like structures in the adsorption on polar and charged surfaces, e.g. on metals.
The molecules form oriented monomolecular films that protect the metal surface from corrosive attack.
N-Oleoylsarcosine possesses already at low concentrations very good rust protection properties (in particularly in combination with the imidazoline derivative 2-(2-heptadec-8-enyl-2-imidazolin-1-yl)ethanol which also acts emulsifying and anticorrosive), also against non-ferrous metals such as aluminum and copper. Therefore, N-oleoylsarcosine is added as a corrosion inhibitor and emulsifier to rust protection fluids and lubricating greases, fuels and lubricants and refrigerating lubricants such as drilling and cutting oils. | 0 | Colloidal Chemistry |
Colloidal nanocrystals are a new class of optical materials that essentially constitute a new form of matter that can be considered as "artificial atoms." Like atoms, they have discrete optical energy spectra that are tunable over a wide range of wavelengths. The desired behavior and transmission directly correlates to their size. To change the emitted wavelength, the crystal is grown larger or smaller. Their electronic and optical properties can be controlled by this method. For example, to change the emission from one visible wavelength to another simply use a larger or smaller grown crystal. However, this process would not be effective in conventional semiconductors such as gallium arsenide.
The nanocrystal size controls a widely tunable absorption band resulting in widely tunable emission spectra. This tunability combined with the optical stability of nanocrystals and the great chemical flexibility in the nanocrystal growth have resulted in the widespread nanocrystal applications in use today. Practical device applications range from low-threshold lasers to solar cells and biological imaging and tracking. | 0 | Colloidal Chemistry |
Methods have been developed for the synthesis of diverse types of molecular wires (e.g. organic molecular wires and inorganic molecular wires). The basic principle is to assemble repeating modules. Organic molecular wires are usually synthesized via transition metal-mediated cross-coupling reactions. | 1 | Solid-state chemistry |
Polyaniline nanofibers can also be synthesized through "rapid mixing" reactions. This method attempts to prevent overgrowth that would compromise the nanofiber nature of the polymer by stopping the polymerization immediately after nanofibers have been formed. This is achieved by the rapid mixing of the monomer, aniline, and an initiator solution. At the start of the reaction, the initiator is consumed rapidly and completely depleted when the nanofibers are formed. Without initiator remaining, the synthesis of polyaniline is halted. | 0 | Colloidal Chemistry |
Miriam M. Unterlass (* 22. October 1986 in Erlangen) is a German chemist and full professor of solid state chemistry at the University of Konstanz. | 1 | Solid-state chemistry |
The KKR method, also called "multiple scattering theory" or Greens function method, finds the stationary values of the inverse transition matrix T rather than the Hamiltonian. A variational implementation was suggested by Korringa, Kohn and Rostocker, and is often referred to as the Korringa–Kohn–Rostoker method. The most important features of the KKR or Greens function formulation are (1) it separates the two aspects of the problem: structure (positions of the atoms) from the scattering (chemical identity of the atoms); and (2) Greens functions provide a natural approach to a localized description of electronic properties that can be adapted to alloys and other disordered system. The simplest form of this approximation centers non-overlapping spheres (referred to as muffin tins') on the atomic positions. Within these regions, the potential experienced by an electron is approximated to be spherically symmetric about the given nucleus. In the remaining interstitial region, the screened potential is approximated as a constant. Continuity of the potential between the atom-centered spheres and interstitial region is enforced. | 1 | Solid-state chemistry |
As bipyridinium derivatives, the viologens are related to 4,4'-bipyridyl. The basic nitrogen centers in these compounds are alkylated to give viologens:
:(CHN) + 2 RX → [(CHNR)](X)
The alkylation is a form of quaternization. When the alkylating agent is a small alkyl halide, such as methyl chloride or methyl bromide, the viologen salt is often water-soluble. A wide variety of alkyl substituents have been investigated. Common derivatives are methyl (see paraquat), long chain alkyl, and benzyl. | 1 | Solid-state chemistry |
Molecular wires (or sometimes called molecular nanowires) are molecular chains that conduct electric current. They are the proposed building blocks for molecular
electronic devices. Their typical diameters are less than three nanometers, while their lengths may be macroscopic, extending to centimeters or more. | 1 | Solid-state chemistry |
The crystal structure of calcium hexaboride is a cubic lattice with calcium at the cell centre and compact, regular octahedra of boron atoms linked at the vertices by B-B bonds to give a three-dimensional boron network. Each calcium has 24 nearest-neighbor boron atoms The calcium atoms are arranged in simple cubic packing so that there are holes between groups of eight calcium atoms situated at the vertices of a cube. The simple cubic structure is expanded by the introduction of the octahedral B groups and the structure is a CsCl-like packing of the calcium and hexaboride groups. Another way of describing calcium hexaboride is as having a metal and a B octahedral polymeric anions in a CsCl-type structure where the Calcium atoms occupy the Cs sites and the B octahedra in the Cl sites. The Ca-B bond length is 3.05 Å and the B-B bond length is 1.7 Å.
Ca NMR data contains δ at -56.0 ppm and δ at -41.3 ppm where δ is taken as peak max +0.85 width, the negative shift is due to the high coordination number.
Raman Data: Calcium hexaboride has three Raman peaks at 754.3, 1121.8, and 1246.9 cm due to the active modes A, E, and T respectively.
Observed Vibrational Frequencies cm : 1270(strong) from A stretch, 1154 (med.) and 1125(shoulder) from E stretch, 526, 520, 485, and 470 from F rotation, 775 (strong) and 762 (shoulder) from F bend, 1125 (strong) and 1095 (weak) from F bend, 330 and 250 from F translation, and 880 (med.) and 779 from F bend. | 1 | Solid-state chemistry |
In 1807, Berzelius was appointed professor in chemistry and pharmacy at the Karolinska Institute. Between 1808 and 1836, Berzelius worked together with Anna Sundström, who acted as his assistant and was the first female chemist in Sweden.
In 1808, he was elected a member of the Royal Swedish Academy of Sciences. At this time, the Academy had been stagnating for several years, since the era of romanticism in Sweden had led to less interest in the sciences. In 1818, Berzelius was elected the Academys secretary and held the post until 1848. During Berzelius tenure, he is credited with revitalising the Academy and bringing it into a second golden era (the first being the astronomer Pehr Wilhelm Wargentin's period as secretary from 1749 to 1783). He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1822. In 1827, he became correspondent of the Royal Institute of the Netherlands, and in 1830 associate member.
In 1837, he was elected a member of the Swedish Academy, on chair number 5. | 1 | Solid-state chemistry |
Anti-foams are added in certain types of detergents to reduce foaming that might decrease the action of the detergent. For example, dishwasher detergents have to be low foaming for the dishwasher to work properly.
Defoamer is added into the recovery tank of carpet extractors to prevent too much-foaming damage to the vac motor. | 0 | Colloidal Chemistry |
Housed in a plastic container, the bomb has a metal partition that separates two liquid reagents. Once the partition is removed, the liquids mix and react, causing them to rapidly expand and then solidify, creating a physical barrier blocking the tunnel. The device is either set at its target by an individual or thrown.
In 2021, testing of sponge bombs was reportedly conducted by IDF in simulated tunnels.
During initial testing of these bombs, the liquid emulsion was found to be hazardous to work with when mishandled – some Israeli soldiers lost their eyesight. | 0 | Colloidal Chemistry |
By including quantum tunnelling, the astrochemical syntheses of various molecules in interstellar clouds can be explained, such as the synthesis of molecular hydrogen, water (ice) and the prebiotic important formaldehyde. Tunnelling of molecular hydrogen has been observed in the lab. | 1 | Solid-state chemistry |
Pyrite is the most common of sulfide minerals and is widespread in igneous, metamorphic, and sedimentary rocks. It is a common accessory mineral in igneous rocks, where it also occasionally occurs as larger masses arising from an immiscible sulfide phase in the original magma. It is found in metamorphic rocks as a product of contact metamorphism. It also forms as a high-temperature hydrothermal mineral, though it occasionally forms at lower temperatures.
Pyrite occurs both as a primary mineral, present in the original sediments, and as a secondary mineral, deposited during diagenesis. Pyrite and marcasite commonly occur as replacement pseudomorphs after fossils in black shale and other sedimentary rocks formed under reducing environmental conditions. Pyrite is common as an accessory mineral in shale, where it is formed by precipitation from anoxic seawater, and coal beds often contain significant pyrite.
Notable deposits are found as lenticular masses in Virginia, U.S., and in smaller quantities in many other locations. Large deposits are mined at Rio Tinto in Spain and elsewhere in the Iberian Peninsula. | 1 | Solid-state chemistry |
To make , sea salt is packed into bamboo canisters and sealed with yellow clay. The mixture is baked in an iron oven and roasted in a pine fire.
A bamboo stem is filled with bay salt produced from Korea's west coast, sealed with red clay, and baked in a kiln with pine tree firewood. The baked salt lumps harden after baking. It is taken out, crushed, and repacked in the bamboo stem for the next cycle. During baking the salt absorbs the bamboo constituents that bring a distinctive sweetness, which is called Gamrojung flavor. Baking darkens the salt. The ninth baking process uses the highest temperature, over . Afterwards, the bamboo salt contains blue, yellow, red, white and black crystals.
Well-baked bamboo salt, with a temperature above , is called “purple bamboo salt” because of its unique purple color, which indicates the best quality. While the quality of bamboo salt cannot be solely determined by color, its crystal structure and hardiness is definitive. | 1 | Solid-state chemistry |
The table below lists common flocculants along with their chemical formulas, net electrical charge, molecular weight and current applications. | 0 | Colloidal Chemistry |
Diquat is an isomer of viologens, being derived from 2,2-bipyridine (instead of the 4,4-isomer). It also is a potent herbicide that functions by disrupting electron-transfer.
Extended viologens have been developed based on conjugated oligomers such as based on aryl, ethylene, and thiophene units are inserted between the pyridine units. The bipolaron di-octyl bis(4-pyridyl)biphenyl viologen 2 in scheme 2 can be reduced by sodium amalgam in DMF to the neutral viologen 3.
The resonance structures of the quinoid 3a and the biradical 3b contribute equally to the hybrid structure. The driving force for the contributing 3b is the restoration of aromaticity with the biphenyl unit. It has been established using X-ray crystallography that the molecule is, in effect, coplanar with slight nitrogen pyramidalization, and that the central carbon bonds are longer (144 pm) than what would be expected for a double bond (136 pm). Further research shows that the diradical exists as a mixture of triplets and singlets, although an ESR signal is absent. In this sense, the molecule resembles Tschischibabin's hydrocarbon, discovered during 1907. It also shares with this molecule a blue color in solution, and a metallic-green color as crystals.
Compound 3 is a very strong reducing agent, with a redox potential of −1.48 V. | 1 | Solid-state chemistry |
MoS excels as a lubricating material (see below) due to its layered structure and low coefficient of friction. Interlayer sliding dissipates energy when a shear stress is applied to the material. Extensive work has been performed to characterize the coefficient of friction and shear strength of MoS in various atmospheres. The shear strength of MoS increases as the coefficient of friction increases. This property is called superlubricity. At ambient conditions, the coefficient of friction for MoS was determined to be 0.150, with a corresponding estimated shear strength of 56.0 MPa (megapascals). Direct methods of measuring the shear strength indicate that the value is closer to 25.3 MPa.
The wear resistance of MoS in lubricating applications can be increased by doping MoS with Cr. Microindentation experiments on nanopillars of Cr-doped MoS found that the yield strength increased from an average of 821 MPa for pure MoS (at 0% Cr) to 1017 MPa at 50% Cr. The increase in yield strength is accompanied by a change in the failure mode of the material. While the pure MoS nanopillar fails through a plastic bending mechanism, brittle fracture modes become apparent as the material is loaded with increasing amounts of dopant.
The widely used method of micromechanical exfoliation has been carefully studied in MoS to understand the mechanism of delamination in few-layer to multi-layer flakes. The exact mechanism of cleavage was found to be layer dependent. Flakes thinner than 5 layers undergo homogenous bending and rippling, while flakes around 10 layers thick delaminated through interlayer sliding. Flakes with more than 20 layers exhibited a kinking mechanism during micromechanical cleavage. The cleavage of these flakes was also determined to be reversible due to the nature of van der Waals bonding.
In recent years, MoS has been utilized in flexible electronic applications, promoting more investigation into the elastic properties of this material. Nanoscopic bending tests using AFM cantilever tips were performed on micromechanically exfoliated MoS flakes that were deposited on a holey substrate. The yield strength of monolayer flakes was 270 GPa, while the thicker flakes were also stiffer, with a yield strength of 330 GPa. Molecular dynamic simulations found the in-plane yield strength of MoS to be 229 GPa, which matches the experimental results within error.
Bertolazzi and coworkers also characterized the failure modes of the suspended monolayer flakes. The strain at failure ranges from 6 to 11%. The average yield strength of monolayer MoS is 23 GPa, which is close to the theoretical fracture strength for defect-free MoS.
The band structure of MoS is sensitive to strain. | 1 | Solid-state chemistry |
Michael Stanley Whittingham (born 22 December 1941) is a British-American chemist. He is a professor of chemistry and director of both the Institute for Materials Research and the Materials Science and Engineering program at Binghamton University, State University of New York. He also serves as director of the Northeastern Center for Chemical Energy Storage (NECCES) of the U.S. Department of Energy at Binghamton. He was awarded the Nobel Prize in Chemistry in 2019 alongside Akira Yoshino and John B. Goodenough.
Whittingham is a key figure in the history of lithium-ion batteries, which are used in everything from mobile phones to electric vehicles. He discovered intercalation electrodes and thoroughly described intercalation reactions in rechargeable batteries in the 1970s. He holds the patents on the concept of using intercalation chemistry in high power-density, highly reversible lithium-ion batteries. He also invented the first rechargeable lithium metal battery (LMB), patented in 1977 and assigned to Exxon for commercialization in small devices and electric vehicles. Whittinghams rechargeable lithium metal battery is based on a LiAl anode and an intercalation-type TiS cathode. His work on lithium batteries laid the foundation for others developments, so he is called the founding father of lithium-ion batteries. | 1 | Solid-state chemistry |
Gregory S. Girolami (born October 16, 1956) is the William H. and Janet G. Lycan Professor of Chemistry at the University of Illinois Urbana-Champaign. His research focuses on the synthesis, properties, and reactivity of new inorganic, organometallic, and solid state species. Girolami has been elected a fellow of the American Association for the Advancement of Science, the Royal Society of Chemistry, and the American Chemical Society. | 1 | Solid-state chemistry |
Both dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) measure the Brownian motion of nanoparticles whose speed of motion, or diffusion constant, Dt, is related to particle size through the Stokes–Einstein equation.
where
*Dt is the diffusion constant, a product of diffusion coefficient D and time t
* is Boltzmann's constant,
*T is the absolute temperature,
*η is viscosity
*d is the diameter of the spherical particle.
In NTA this motion is analyzed by video – individual particle positional changes are tracked in two dimensions from which the particle diffusion is determined. Knowing Dt, the particle hydrodynamic diameter can be then determined.
In contrast, DLS does not visualize the particles individually but analyzes, using a digital correlator, the time dependent scattering intensity fluctuations. These fluctuations are caused by interference effects arising from the relative Brownian movements of an ensemble of a large number of particles within a sample. Through analysis of the resultant exponential autocorrelation function, average particle size can be calculated as well as a polydispersity index. For multi-exponential autocorrelation functions arising from polydisperse samples, deconvolution can give limited information about the particle size distribution profile. | 0 | Colloidal Chemistry |
Because of its direct relevance to products of commerce, solid state inorganic chemistry has been strongly driven by technology. Progress in the field has often been fueled by the demands of industry, sometimes in collaboration with academia. Applications discovered in the 20th century include zeolite and platinum-based catalysts for petroleum processing in the 1950s, high-purity silicon as a core component of microelectronic devices in the 1960s, and “high temperature” superconductivity in the 1980s. The invention of X-ray crystallography in the early 1900s by William Lawrence Bragg was an enabling innovation. Our understanding of how reactions proceed at the atomic level in the solid state was advanced considerably by Carl Wagners work on oxidation rate theory, counter diffusion of ions, and defect chemistry. Because of his contributions, he has sometimes been referred to as the father of solid state chemistry'. | 1 | Solid-state chemistry |
In a domestic setting, "soap" usually refers to what is technically called a toilet soap, used for household and personal cleaning. When used for cleaning, soap solubilizes particles and fats/oils, which can then be separated from the article being cleaned.
The insoluble oil/fat molecules become associated inside micelles, tiny spheres formed from soap molecules with polar hydrophilic (water-attracting) groups on the outside and encasing a lipophilic (fat-attracting) pocket, which shields the oil/fat molecules from the water making them soluble. Anything that is soluble will be washed away with the water. | 1 | Solid-state chemistry |
Odom attended Stanford University, where she earned a BS in chemistry, was elected to Phi Beta Kappa, and received the Standford's Marsden Memorial Prize for Chemistry Research (1996). She obtained her PhD in chemical physics from Harvard University in 2001 under the guidance of Charles M. Lieber, then conducted post-doctoral research at Harvard with George M. Whitesides from 2001 to 2002. | 1 | Solid-state chemistry |
Although ammonium bicarbonate has been utilized in the manufacturing of titanium foams, it is not an ideal spacer in that it has a low melting/dissociation point and some solubility in titanium. This results in considerable shrinkage which makes control of pore shape difficult. Furthermore, the decomposition releases environmentally harmful gases. | 0 | Colloidal Chemistry |
Ballistic foam is a foam that sets hard. It is widely used in the manufacture and repair of aircraft to form a light but strong filler for aircraft wings. The foam is used to surround aircraft fuel tanks to reduce the chance of fires caused by the penetration of incendiary projectiles.
Ballistic foam is a type of polyurethane foam placed in the dry bays of aircraft. Ballistic foam prevents fires, adds strength to the structure, slows down the speed of shrapnel during attacks, and offers cost-effective protection.
Ballistic foam is placed in the dry bays to provide a barrier between the spark and the fuel. As bullets or shrapnel penetrate the mold line skin surrounding the outermost portions of the dry bay, the ballistic foam deprives sparks of oxygen. Thus when the article punctures the fuel tank, a fire is not started. Not only does the foam displace oxygen, but all gases, including explosive vapors which could magnify the destructive effects of ballistic attack. Dry bays, voids, may also contain “onboard ignition sources” like hot surfaces and electrical sparks which benefit both from a lack of gases and the fire-retardant nature of the foam.
Ballistic foam strengthens aircraft by protecting it from fire as well as fluid while adding very little weight. The protection from fluid involves resisting damage by “moisture, hydrocarbon fuels, hydraulic fluids, and most common solvents”. The density of the foam varies with the type being used; Type 2.5 is a white to light amber foam weighing 2.5 pounds per cubic foot, while Type 1.8 is a pale blue to green foam weighing 1.8 pounds per cubic foot.
Chopped fiberglass strands embedded in the foam add to the structural integrity through physical support and shrapnel mitigation. The layer that strengthens the foam in turn strengthens the airframe. The layer of fiberglass also prevents shrapnel and bullets from rupturing the foam. The fiber glass then allows the damage caused by projectile penetration to heal more effectively.
The passive protection afforded by ballistic foam is very simple and inexpensive compared to active protection. One method of active protection is done by filling large dry bays with inert gases which will not sustain a flame. This process is very expensive and complex. Active protection only offers a “one time” chance for ballistic protection while the ballistic foam is always available. | 0 | Colloidal Chemistry |
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