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The reduced vacancy concentration in nanocrystals can negatively affect the motion of dislocations, since dislocation climb requires vacancy migration. In addition, there exists a very high internal pressure due to the surface stress present in small nanoparticles with high radii of curvature. This causes a lattice strain that is inversely proportional to the size of the particle, also well known to impede dislocation motion, in the same way as it does in the work hardening of materials. For example, gold nanoparticles are significantly harder than the bulk material. Furthermore, the high surface-to-volume ratio in nanoparticles makes dislocations more likely to interact with the particle surface. In particular, this affects the nature of the dislocation source and allows the dislocations to escape the particle before they can multiply, reducing the dislocation density and thus the extent of plastic deformation.
There are unique challenges associated with the measurement of mechanical properties on the nanoscale, as conventional means such as the universal testing machine cannot be employed. As a result, new techniques such as nanoindentation have been developed that complement existing electron microscope and scanning probe methods. Atomic force microscopy (AFM) can be used to perform nanoindentation to measure hardness, elastic modulus, and adhesion between nanoparticle and substrate. The particle deformation can be measured by the deflection of the cantilever tip over the sample. The resulting force-displacement curves can be used to calculate elastic modulus. However, it is unclear whether particle size and indentation depth affect the measured elastic modulus of nanoparticles by AFM.
Adhesion and friction forces are important considerations in nanofabrication, lubrication, device design, colloidal stabilization, and drug delivery. The capillary force is the main contributor to the adhesive force under ambient conditions. The adhesion and friction force can be obtained from the cantilever deflection if the AFM tip is regarded as a nanoparticle. However, this method is limited by tip material and geometric shape. The colloidal probe technique overcomes these issues by attaching a nanoparticle to the AFM tip, allowing control oversize, shape, and material. While the colloidal probe technique is an effective method for measuring adhesion force, it remains difficult to attach a single nanoparticle smaller than 1 micron onto the AFM force sensor.
Another technique is in situ TEM, which provides real-time, high resolution imaging of nanostructure response to a stimulus. For example, an in situ force probe holder in TEM was used to compress twinned nanoparticles and characterize yield strength. In general, the measurement of the mechanical properties of nanoparticles is influenced by many factors including uniform dispersion of nanoparticles, precise application of load, minimum particle deformation, calibration, and calculation model.
Like bulk materials, the properties of nanoparticles are materials dependent. For spherical polymer nanoparticles, glass transition temperature and crystallinity may affect deformation and change the elastic modulus when compared to the bulk material. However, size-dependent behavior of elastic moduli could not be generalized across polymers. As for crystalline metal nanoparticles, dislocations were found to influence the mechanical properties of nanoparticles, contradicting the conventional view that dislocations are absent in crystalline nanoparticles. | 0 | Colloidal Chemistry |
Albert Ernest Alexander was born on 5 January 1914 in Ringwood, Hampshire, the sixth of seven children of William Albert Alexander, a master builder, and Beatrice (née Daw), formerly a teacher. He attended Brockenhurst County School, from where he gained a place in 1931 at the University of Reading. He graduated in 1934 with First Class Honours in Chemistry and an Open Scholarship to King's College, Cambridge. He was awarded a First Class in the Tripos Examination.
With the benefit of a King's College Senior Scholarship, a DSIR grant for research, and a Ramsay Memorial Fellowship, Alexander joined the Department of Colloid Science to work under Professor E K Rideal (later Sir Eric Keightley Rideal, MBE, FRS). He began with work on the orientation in films of long-chain esters and continued by examining porphyrins, chlorophylls and other molecules, with and without metals.
Alexander was awarded his PhD in 1938, and then went hitch-hiking in Scandinavia with his friend from Cambridge F S Dainton. During their holiday they visited Theodor Svedberg's laboratory in Uppsala in August 1938, after which Alexander decided he would like to spend as much time as he could working with Torsten Teorell in Uppsala. He started at the Institute of Medical Chemistry in December 1938, but had to return to England at the outbreak of war in September 1939. His work in that nine-month period was published that year.
He returned to Cambridge, where he was elected a Fellow of King's College. In the Department of Colloid Science work continued on a wide range of topics including the role of hydrogen bonding in condensed monomolecular films and the effects of soaps and synthetic wetting agents on the biological activities of phenols. Fourteen publications appeared in the war years.
In 1944 Alexander became one of two Assistant Directors of Research in the Colloid Science Department; Gordon Sutherland was the other. On 6 February 1947 he delivered the Tilden Lecture in recognition of the prize he had been awarded by the Chemical Society of London.
In October 1947 the Société de Chimie Physique and the Faraday Society held a joint discussion meeting at Bordeaux on Surface Chemistry, at which Alexander and colleagues gave five papers. In 1949 Alexander and Johnson published Colloid Science which an anonymous reviewer praised as a broad, modern, and authoritative treatment of the subject of colloid physics and chemistry from the fundamental rather than from the phenomenological viewpoint.
In Australia, the government of New South Wales created an Institute of Technology as part of its plan to expand its technical education system at the tertiary level. They advertised for applications for a Chair in Applied Chemistry, to which Alexander was appointed. On 1 October 1949 he and his family sailed from London to Sydney on the RMS Maloja. They lived at 178 Raglan Street, Mosman, a suburb of Sydney, and only a short drive from the Sydney Technical College. During Alexander's seven years there he authored or co-authored some 40 papers. Many involved systems of practical importance, such as efforts to reduce evaporation from dams, and the cattle tick problem in NSW.
But, disillusioned with the lack of progress with the status of the Technical College to an autonomous university, Alexander moved to the University of Sydney in 1956. Work was quickly restarted on topics that may be catalogued under four headings: (a) monolayer studies, (b) micellar solutions, (c) the roles of surfactants in heterogeneous polymerisations, and (d) the effects of polyelectrolytes on the crystallisations of sparingly soluble salts. Fifty or more papers appeared from Alexander and his group. Their work is described in detail in Le Fèvre’s memoir. | 0 | Colloidal Chemistry |
Alkaline salts are often the major component of alkaline dishwasher detergent powders.
These salts may include:
*alkali metasilicates
*alkali metal hydroxides
*Sodium carbonate
*Sodium Bicarbonate
Examples of other strongly alkaline salts, include:
*Sodium percarbonate
*Sodium persilicate (?)
*Potassium metabisulfite | 1 | Solid-state chemistry |
Traditional plasticizers are lignosulphonates as their sodium salts. Superplasticizers are synthetic polymers. Compounds used as superplasticizers include (1) sulfonated naphthalene formaldehyde condensate, sulfonated melamine formaldehyde condensate, acetone formaldehyde condensate and (2) polycarboxylates ethers. Cross-linked melamine- or naphthalene-sulfonates, referred to as PMS (polymelamine sulfonate) and PNS (polynaphthalene sulfonate), respectively, are illustrative. They are prepared by cross-linking of the sulfonated monomers using formaldehyde or by sulfonating the corresponding crosslinked polymer.
The polymers used as plasticizers exhibit surfactant properties. They are often ionomers bearing negatively charged groups (sulfonates, carboxylates, or phosphonates...). They function as dispersants to minimize particles segregation in fresh concrete (separation of the cement slurry and water from the coarse and fine aggregates such as gravels and sand respectively). The negatively charged polymer backbone adsorbs onto the positively charged colloidal particles of unreacted cement, especially onto the tricalcium aluminate () mineral phase of cement.
Melaminesulfonate (PMS) and naphthalenesulfonate (PNS) mainly act by electrostatic interactions with cement particles favoring their electrostatic repulsion while polycarboxylate-ether (PCE) superplasticizers sorb and coat large agglomerates of cement particles, and thanks to their lateral chains, sterically favor the dispersion of large cement agglomerates into smaller ones.
However, as their working mechanisms are not fully understood, cement-superplasticizer incompatibilities can be observed in certain cases. | 0 | Colloidal Chemistry |
Indium sulfide is usually prepared by direct combination of the elements.
Production from volatile complexes of indium and sulfur, for example dithiocarbamates (e.g. EtInSCNEt), has been explored for vapor deposition techniques.
Thin films of the beta complex can be grown by chemical spray pyrolysis. Solutions of In(III) salts and organic sulfur compounds (often thiourea) are sprayed onto preheated glass plates, where the chemicals react to form thin films of indium sulfide. Changing the temperature at which the chemicals are deposited and the In:S ratio can affect the optical band gap of the film.
Single-walled indium sulfide nanotubes can be formed in the laboratory, by the use of two solvents (one in which the compound dissolves poorly and one in which it dissolves well). There is partial replacement of the sulfido ligands with O, and the compound forms thin nanocoils, which self-assemble into arrays of nanotubes with diameters on the order of 10 nm, and walls approximately 0.6 nm thick. The process mimics protein crystallization. | 1 | Solid-state chemistry |
In 1941, Kê married He Yizhen, a physicist who would specialize in amorphous physics was metallic glass, and was a founder of the Institute of Metal Research and Institute of Solid State Physics. They developed a competitive relationship with one another due to their studies in the same field.
The couple met at Yenching University, where he had been a lecturer and was three years older than Kê. Because He came from a wealthy and influential family, she had a number of admirers; her family did not approve of her relationship with Kê became he came from a poor family and also suffered from pulmonary tuberculosis, for which a valid treatment was not available at the time. Furthermore, Kês political beliefs clashed with Hes father, who disagreed with Ges support of the political activism of students. In opposition to her familys wishes, she married Kê; their marriage became a much-told tale in Chinese academia and their love letters are still preserved in their biographies.
After their marriage, Kê obtained the opportunity to study in the United States with He, where they remained from 1941 to 1949. Their two children were born in the United States and eventually became scientists: their daughter Ge Yunpei (1942-2013) was a professor in Shenyang Jianzhu University, while their son Ge Yunjian (born 1947), is an expert in robotics. The couple returned to China in 1949, where they both worked for the Chinese Academy of Science for decades. When Kê was dispatched to work in Hefei in 1980, Kê and their children persuaded He to stop her research to join him in Hefei. | 1 | Solid-state chemistry |
Albert studied Chemistry at the University of Bonn from 1985 to 1990. She worked on her dissertation in the group of until 1995. With the help of the Feodor Lynen Fellowship of the Alexander von Humboldt Foundation, she worked as a postdoctoral fellow at the Materials Research Laboratory of the University of California, Santa Barbara in the group of Anthony Cheetham. In 2000 she habilitated at the University of Bonn, where she became a Privatdozent in 2001. In the same year she became a professor at the University of Hamburg, where she was also Managing Director of the Institute for Inorganic and Applied Chemistry from 2003 to 2005. From 2005 to 2022 she was a professor at the Technische Universität Darmstadt. From 2012 to 2013 she was the president of the German Chemical Society. She has been a member of the supervisory board of Evonik Industries since 2014 and of the supervisory board of the Schunk Group since 2016. Since April 2022, she is rector of the University of Duisburg-Essen. | 1 | Solid-state chemistry |
Kanatzidis was born in Thessaloniki, Greece. He received his B.S. degree from Aristotle University in 1979 and his Ph.D. from the University of Iowa in 1984 (with Dimitri Coucouvanis). He spent two years at the University of Iowa from 1980 to 1982 and then moved to the University of Michigan when Coucouvanis moved there in 1982.
He was a postdoctoral research fellow at the University of Michigan (1985) and Northwestern University (1986–1987) where he worked with Professor Tobin J. Marks on conductive polymers and intercalation compounds.
He became assistant professor at Michigan State University in 1987. He was promoted to full Professor in 1994. He moved to Northwestern University in 2006. | 1 | Solid-state chemistry |
Class B foams are designed for class B fires—flammable liquids. The use of class A foam on a class B fire may yield unexpected results, as class A foams are not designed to contain the explosive vapours produced by flammable liquids. Class B foams have two major subtypes. | 0 | Colloidal Chemistry |
Cocrystals may be characterized in a wide variety of ways. Powder X-Ray diffraction proves to be the most commonly used method in order to characterize cocrystals. It is easily seen that a unique compound is formed and if it could possibly be a cocrystal or not owing to each compound having its own distinct powder diffractogram. Single-crystal X-ray diffraction may prove difficult on some cocrystals, especially those formed through grinding, as this method more often than not provides powders. However, these forms may be formed often through other methodologies in order to afford single crystals.
Aside from common spectroscopic methods such as FT-IR and Raman spectroscopy, solid state NMR spectroscopy allows differentiation of chiral and racemic cocrystals of similar structure.
Other physical methods of characterization may be employed. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are two commonly used methods in order to determine melting points, phase transitions, and enthalpic factors which can be compared to each individual cocrystal former. | 1 | Solid-state chemistry |
After synthesizing and purifying the core, the carbohydrate layer is added to its surface. Common coating materials are typically polyhydroxy oligomers such as cellobiose, citrate, lactose, and sucrose. This layer seems to be important for the properties of aquasomes, as it influences several drug characteristics including adsorption, molecular stability, and conformation, and acts as a dehydroprotectant. The addition of the carbohydrate layer to the surface of the nanocrystalline core is commonly carried out by passive adsorption through incubation and sonication. Similar to the processing of the core, the carbohydrate layer is subjected to centrifugation, washing, and further sonification followed by heated air drying. | 0 | Colloidal Chemistry |
Due to Brownian motion particles randomly move through the liquid. And hence better transport of heat.
Although it was originally believed that the fluid motions resulting from Brownian motion of the nanoparticles could explain the enhancement in heat transfer properties, this hypothesis was later rejected. | 0 | Colloidal Chemistry |
When the Na (sodium) predominates, soils can become sodic. The pH of sodic soils may be acidic, neutral or alkaline.
Sodic soils present particular challenges because they tend to have very poor structure which limits or prevents water infiltration and drainage. They tend to accumulate certain elements like boron and molybdenum in the root zone at levels that may be toxic for plants. The most common compound used for reclamation of sodic soil is gypsum, and some plants that are tolerant to salt and ion toxicity may present strategies for improvement.
The term "sodic soil" is sometimes used imprecisely in scholarship. It's been used interchangeably with the term alkali soil, which is used in two meanings: 1) a soil with a pH greater than 8.2, 2) soil with an exchangeable sodium content above 15% of exchange capacity. The term "alkali soil" is often, but not always, used for soils that meet both of these characteristics. | 1 | Solid-state chemistry |
Rainer Waser (born September 16, 1955, in Frankfurt) is a German professor of Electrical Engineering at RWTH Aachen University. He is also director of the section Electronic Materials at the Peter Grünberg Institute which is located on the campus of Jülich Research Center (Forschungszentrum Jülich). His research and teaching is on solid-state chemistry and defect chemistry to electronic properties and modelling, the technology of new materials and the physical properties of construction components.
Important findings include insights in the functioning of the so-called memristors.
Waser grew up in Heusenstamm near Frankfurt. He studied Physical Chemistry at Darmstadt University of Technology where he received a diploma degree in 1979. Then he went to the University of Southampton to conduct research at the Institute of Electrochemistry. After that he turned to Darmstadt and worked as scientific assistant until he completed his PhD. | 1 | Solid-state chemistry |
Paul Francis McMillan (3 June 1956 – 2 February 2022) was a British chemist who held the Sir William Ramsay Chair of Chemistry at University College London. His research considered the study of matter under extreme conditions of temperature and pressure, with a focus on phase transitions, amorphisation, and the study of glassy states. He has also investigated the survival of bacteria and larger organisms (tardigrades) under extreme compression, studies of amyloid fibrils, the synthesis and characterisation of carbonitride nanocrystals and the study of water motion in confined environments. He has made extensive use of Raman spectroscopy together with X-ray diffraction and neutron scattering techniques. | 1 | Solid-state chemistry |
Permittivity is typically associated with dielectric materials, however metals are described as having an effective permittivity, with real relative permittivity equal to one. In the high-frequency region, which extends from radio frequencies to the far infrared and terahertz region, the plasma frequency of the electron gas is much greater than the electromagnetic propagation frequency, so the refractive index n of a metal is very nearly a purely imaginary number. In the low frequency regime, the effective relative permittivity is also almost purely imaginary: It has a very large imaginary value related to the conductivity and a comparatively insignificant real-value. | 0 | Colloidal Chemistry |
Cava was educated at the Massachusetts Institute of Technology (MIT) where he was awarded Bachelor of Science and Master of Science degrees in Materials Science and Engineering in 1974 followed by a PhD in ceramics in 1978. His PhD was supervised by Bernhardt J. Wuensch and investigated the electrical mobility of ions in fast ion conductors. | 1 | Solid-state chemistry |
*1944 H.G. Smith Medal, Royal Australian Chemical Institute
*1945 Syme Research Prize, University of Melbourne
*1953 Elected FRS
*1954 Elected FAA
*1965 Matthew Flinders Medal and Lecture
*1973 Davy Medal, Royal Society of London
*1974–1976 President of the Dalton Division of the Chemical Society
*1975 Award for Solid State Chemistry, Royal Society of Chemistry
*1975 Longstaff Medal, Royal Society of Chemistry
*1978 Honorary Fellow, Indian Academy of Sciences
*1979 Hon. DSc, University of Bath
*1980 Hugo Muller Medal/Lecture, Royal Society of Chemistry
Source | 1 | Solid-state chemistry |
Latex paints (emulsion paints British English, not to be confused with latex rubber) are an emulsion of polymer particles dispersed in water. Macroemulsions in latex paint are inherently unstable and phase separate, so surfactants are added to lower interfacial tension and stabilize polymer particles to prevent demulsification.
Anionic surfactants such as sodium dodecyl sulfate are most commonly used for stabilizing emulsions because of their affinity for hydrogen bonding with the aqueous medium. Nonionic surfactants are rarely used alone due to their inferior efficiency in creating stable emulsions in comparison to anionic surfactants. Because of this, non-ionic surfactants are usually used in tandem with anionic surfactants and impart a second method of colloidal stabilization through steric interference of the van der Waals forces amid polymer and pigment particles. Latexes that require stability over large pH ranges use larger nonionic to anionic surfactant ratios. Cationic surfactants are least commonly used because of their high cost, inefficient emulsifying capability, and undesirable effects on initiator decomposition. High speed application, low temperature storage, shear stresses from pumping, and other extreme storage or application conditions can cause the failure of a surfactant to adequately stabilize a paint dispersion.
The thermodynamic explanation for demulsification is the gain in Gibbs Free Energy resulting from lowering the total area of high energy surface interactions.
The energy gained from demulsification is dependent on the total area of interface and the surface tension of that interface. Surfactants lower the surface tension (γ) and thus gibbs energy is gained from demulsification. This slows the process of demulsification and stabilizes the latex paint.
The size of the droplets of dispersed polymer in a latex paint can be modeled with the following equation:
The radius of a droplet in the emulsion is dependent on surfactant length, L, volume fraction of dispersed phase, φ, and volume fraction of surfactant, φ. | 0 | Colloidal Chemistry |
Tunable resistive pulse sensing (TRPS) is a single-particle technique used to measure the size, concentration and zeta potential of particles as they pass through a size-tunable nanopore.
The technique adapts the principle of resistive pulse sensing, which monitors current flow through an aperture, combined with the use of tunable nanopore technology, allowing the passage of ionic current and particles to be regulated by adjusting the pore size. The addition of the tunable nanopore allows for the measurement of a wider range of particle sizes and improves accuracy. | 0 | Colloidal Chemistry |
Highly contaminated drinking water has been detected at several locations in Sweden. Such locations include Arvidsjaur, Lulnäset, Uppsala and Visby. In 2013, PFAS were detected at high concentrations in one of the two municipality drinking water treatment plants in the town of Ronneby, in southern Sweden. Concentrations of PFHxS and PFOS were found at 1700 ng/L and 8000 ng/L, respectively. The source of contamination was later found to be a military fire-fighting exercise site in which PFAS containing fire-fighting foam had been used since the mid-1980s.
Additionally, low-level contaminated drinking water has also been shown to be a significant exposure source of PFOA, PFNA, PFHxS and PFOS for Swedish adolescents (ages 10–21). Even though the median concentrations in the municipality drinking water were below <1 ng individual PFAS/L, positive associations were found between adolescent serum PFAS concentrations and PFAS concentrations in drinking water. | 0 | Colloidal Chemistry |
*Padma Bhushan (1964)
*Commander of the Order of the British Empire (CBE) (1943 Birthday Honours)
*Fellow of Indian Academy of Science, Bangalore, Indian Chemical Association and Royal Society of Chemistry (London)
*Founder Secretary, Indian Chemical Society, President (1935–36), Indian Society of Soil Science
*Member, Council (1935–38) and as Vice-President (1941–42)
*Foreign Secretary, INSA (1943–44) and (1947–51)
*General President, Indian Science Congress Association (1952). | 0 | Colloidal Chemistry |
Silver nanoparticles are inserted into the 3D polymeric networks of nanocomposite hydrogels for applications in antibacterial activity and improvement in electrical conductance. The presence of silver ions either stop the respiratory enzyme from transferring electrons to oxygen molecules during respiration or prevent proteins from reacting with thiol groups (-SH) on bacteria membrane, both result in the death of bacteria and microorganism without damaging mammal cells. The size of these silver nanoparticles need to be small enough to pass through the cell membrane and thus further research is required to manufacture them into appropriate sizes. | 0 | Colloidal Chemistry |
Magnesium diboride is the inorganic compound with the formula MgB. It is a dark gray, water-insoluble solid. The compound has attracted attention because it becomes superconducting at 39 K (−234 °C). In terms of its composition, MgB differs strikingly from most low-temperature superconductors, which feature mainly transition metals. Its superconducting mechanism is primarily described by BCS theory. | 1 | Solid-state chemistry |
The carbides of the group 4, 5 and 6 transition metals (with the exception of chromium) are often described as interstitial compounds. These carbides have metallic properties and are refractory. Some exhibit a range of stoichiometries, being a non-stoichiometric mixture of various carbides arising due to crystal defects. Some of them, including titanium carbide and tungsten carbide, are important industrially and are used to coat metals in cutting tools.
The long-held view is that the carbon atoms fit into octahedral interstices in a close-packed metal lattice when the metal atom radius is greater than approximately 135 pm:
*When the metal atoms are cubic close-packed, (ccp), then filling all of the octahedral interstices with carbon achieves 1:1 stoichiometry with the rock salt structure.
*When the metal atoms are hexagonal close-packed, (hcp), as the octahedral interstices lie directly opposite each other on either side of the layer of metal atoms, filling only one of these with carbon achieves 2:1 stoichiometry with the CdI structure.
The following table shows structures of the metals and their carbides. (N.B. the body centered cubic structure adopted by vanadium, niobium, tantalum, chromium, molybdenum and tungsten is not a close-packed lattice.) The notation "h/2" refers to the MC type structure described above, which is only an approximate description of the actual structures. The simple view that the lattice of the pure metal "absorbs" carbon atoms can be seen to be untrue as the packing of the metal atom lattice in the carbides is different from the packing in the pure metal, although it is technically correct that the carbon atoms fit into the octahedral interstices of a close-packed metal lattice.
For a long time the non-stoichiometric phases were believed to be disordered with a random filling of the interstices, however short and longer range ordering has been detected.
Iron forms a number of carbides, , and . The best known is cementite, FeC, which is present in steels. These carbides are more reactive than the interstitial carbides; for example, the carbides of Cr, Mn, Fe, Co and Ni are all hydrolysed by dilute acids and sometimes by water, to give a mixture of hydrogen and hydrocarbons. These compounds share features with both the inert interstitials and the more reactive salt-like carbides.
Some metals, such as lead and tin, are believed not to form carbides under any circumstances. There exists however a mixed titanium-tin carbide, which is a two-dimensional conductor. | 1 | Solid-state chemistry |
Used as moderate blue coloring agent in blue flame compositions with additional chlorine donors and oxidizers such as chlorates and perchlorates. Providing oxygen it can be used as flash powder oxidizer with metal fuels such as magnesium, aluminium, or magnalium powder. Sometimes it is used in strobe effects and thermite compositions as crackling stars effect. | 1 | Solid-state chemistry |
Laser ablation synthesis in solution (LASiS) is a commonly used method for obtaining colloidal solution of nanoparticles in a variety of solvents. Nanoparticles (NPs,), are useful in chemistry, engineering and biochemistry due to their large surface-to-volume ratio that causes them to have unique physical properties. LASiS is considered a "green" method due to its lack of use for toxic chemical precursors to synthesize nanoparticles.
In the LASiS method, nanoparticles are produced by a laser beam hitting a solid target in a liquid and during the condensation of the plasma plume, the nanoparticles are formed. Since the ablation is occurring in a liquid, versus air/vacuum/gas/, the environment allows for plume expansion, cooling and condensation with a higher temperature, pressure and density to create a plume with stronger confinement. These environmental conditions allow for more refined and smaller nanoparticles LASiS is usually considered a top-down physical approach. LASiS emerged as a reliable alternative to traditional chemical reduction methods for obtaining [https://www.sciencedirect.com/user/identity/landing?code=bd7tbF8lFbqx9BEvKTxF_HL2dPmM5rwtt_cGp2js&state=retryCounter%3D0%26csrfToken%3D0f77d85c-37ec-4ad2-b84c-387cc048fef3%26idpPolicy%3Durn%253Acom%253Aelsevier%253Aidp%253Apolicy%253Aproduct%253Ainst_assoc%26returnUrl%3Dhttps%253A%252F%252Fwww.sciencedirect.com%252Ftopics%252Fengineering%252Fnoble-metal-nanoparticles%26prompt%3Dnone%26cid%3Dtpp-4a9ab2b7-cc28-4088-9767-db2160553575 noble metal] nanoparticles (NMNp). LASiS is also used for synthesis of silver nanoparticles AgNPs, which are known for their antimicrobial effects. Production of AgNPs via LASiS causes nanoparticles with varying antimicrobial characteristics due to different properties achieved via the fine tuning of NPs size in liquid ablation. | 0 | Colloidal Chemistry |
FeO is ferrimagnetic with a Curie temperature of . There is a phase transition at , called Verwey transition where there is a discontinuity in the structure, conductivity and magnetic properties. This effect has been extensively investigated and whilst various explanations have been proposed, it does not appear to be fully understood.
While it has much higher electrical resistivity than iron metal (96.1 nΩ m), FeO's electrical resistivity (0.3 mΩ m ) is significantly lower than that of FeO (approx kΩ m). This is ascribed to electron exchange between the Fe and Fe centres in FeO. | 1 | Solid-state chemistry |
As a significant product of copper mining, copper(II) oxide is the starting point for the production of other copper salts. For example, many wood preservatives are produced from copper oxide.
Cupric oxide is used as a pigment in ceramics to produce blue, red, and green, and sometimes gray, pink, or black glazes.
It is incorrectly used as a dietary supplement in animal feed. Due to low bioactivity, negligible copper is absorbed.
It is used when welding with copper alloys.
A copper oxide electrode formed part of the early battery type known as the Edison–Lalande cell. Copper oxide was also used in a lithium battery type (IEC 60086 code "G"). | 1 | Solid-state chemistry |
Fogbank (stylized as FOGBANK) is a code name given to a secret material used in the W76, W78 and W88 nuclear warheads that are part of the United States nuclear arsenal. The process to create Fogbank was lost by 2000, when it was needed for the refurbishment of old warheads. Fogbank was then reverse engineered by the National Nuclear Security Administration (NNSA) over five years and at the cost of tens of millions of dollars.
Fogbank's precise nature is classified; in the words of former Oak Ridge general manager Dennis Ruddy, "The material is classified. Its composition is classified. Its use in the weapon is classified, and the process itself is classified." Department of Energy Nuclear Explosive Safety documents simply describe it as a material "used in nuclear weapons and nuclear explosives" along with lithium hydride (LiH) and lithium deuteride (LiD), beryllium (Be), uranium hydride (UH), and plutonium hydride.
However, NNSA Administrator Tom DAgostino disclosed the role of Fogbank in the weapon: "Theres another material in the—its called interstage material, also known as Fogbank", and arms experts believe that Fogbank is an aerogel material which acts as an interstage material in a nuclear warhead; i.e., a material designed to become a superheated plasma following the detonation of the weapons fission stage, the plasma then triggering the fusion-stage detonation. | 0 | Colloidal Chemistry |
Despite the synthesis method employed, PtSi forms in the same way. When pure platinum is first heated with silicon, is formed. Once all the available Pt and Si are used and the only available surfaces are , the silicide will begin the slower reaction of converting into PtSi. The activation energy for the reaction is around 1.38 eV, while it is 1.67 eV for PtSi.
Oxygen is extremely detrimental to the reaction, as it will bind preferably to Pt, limiting the sites available for Pt–Si bonding and preventing the silicide formation. A partial pressure of as low at 10 has been found to be sufficient to slow the formation of the silicide. To avoid this issue inert ambients are used, as well as small annealing chambers to minimize amount of potential contamination. The cleanliness of the metal film is also extremely important, and unclean conditions result in poor PtSi synthesis.
In certain cases an oxide layer can be beneficial. When PtSi is used as a Schottky barrier, an oxide layer prevents wear of the PtSi. | 1 | Solid-state chemistry |
This rationalization is simple and preserves the double-bond nature of the group 13 or 14 atom interaction. The multiple bond is not exactly a typical σ+π interaction; rather the two halves of the alkyne analogue are treated as singlet bent monomers and the multiple bond is treated as an aggregation between them, with the spp-hybridized filled orbital on one group 13 or 14 atom donating to the vacant p of the other. | 1 | Solid-state chemistry |
Long-range order has been observed in thin films of colloidal liquids under oil—with the faceted edge of an emerging single crystal in alignment with the diffuse streaking pattern in the liquid phase. Structural defects have been directly observed in the ordered solid phase as well as at the interface of the solid and liquid phases. Mobile lattice defects have been observed via Bragg reflections, due to the modulation of the light waves in the strain field of the defect and its stored elastic strain energy. | 0 | Colloidal Chemistry |
Water has long been a universal agent for suppressing fires, but is not best in all cases. For example, water is typically ineffective on oil fires, and can be dangerous. Fire-fighting foams were developed for extinguishing oil fires.
In 1902, a method of extinguishing flammable liquid fires by blanketing them with foam was introduced by Russian engineer and chemist Aleksandr Loran. Loran was a teacher in a school in Baku, the center of the Russian oil industry at that time. Impressed by large, difficult-to-extinguish oil fires that he had seen there, Loran tried to find a liquid substance that could deal effectively with them. He invented fire-fighting foam, which was successfully tested in experiments in 1902 and 1903. In 1904 Loran patented his invention, and developed the first foam extinguisher the same year.
The original foam was a mixture of two powders and water produced in a foam generator. It was called chemical foam because of the chemical action to create it. In general, the powders used were sodium bicarbonate and aluminium sulfate, with small amounts of saponin or liquorice added to stabilise the bubbles. Hand-held foam extinguishers used the same two chemicals in solution. To actuate the extinguisher, a seal was broken and the unit inverted, allowing the liquids to mix and react. Chemical foam is a stable solution of small bubbles containing carbon dioxide with lower density than oil or water, and exhibits persistence for covering flat surfaces. Because it is lighter than the burning liquid, it flows freely over the liquid surface and extinguishes the fire by a smothering (removal/prevention of oxygen) action. Chemical foam is considered obsolete today because of the many containers of powder required, even for small fires.
In the 1940s, Percy Lavon Julian developed an improved type of foam called Aerofoam. Using mechanical action, a liquid protein-based concentrate, made from soy protein, was mixed with water in either a proportioner or an aerating nozzle to form air bubbles with the free-flowing action. Its expansion ratio and ease of handling made it popular. Protein foam is easily contaminated by some flammable liquids, so care should be used so that the foam is applied only above the burning liquid. Protein foam has slow knockdown characteristics, but it is economical for post-fire security.
In the early 1950s, high-expansion foam was conceived by Herbert Eisner in England at the Safety in Mines Research Establishment (now the Health & Safety Laboratory) to fight coal mine fires. Will B. Jamison, a Pennsylvania Mining Engineer, read about the proposed foam in 1952, requested more information about the idea. He proceeded to work with the US Bureau of Mines on the idea, testing 400 formulas until a suitable compound was found. In 1964, Walter Kidde & Company (now Kidde) bought the patents for high expansion foam.
In the 1960s, National Foam, Inc. developed fluoroprotein foam. Its active agent is a fluorinated surfactant that provides an oil-rejecting property to prevent contamination. In general, it is better than protein foam because its longer blanket life provides better safety when entry is required for rescue. Fluoroprotein foam has fast knockdown characteristics and it can also be used together with dry chemicals that destroy protein foam.
In the mid-1960s, the US Navy developed aqueous film-forming foam (AFFF). This synthetic foam has a low viscosity and spreads rapidly across the surface of most hydrocarbon fuels. A water film forms beneath the foam, which cools the liquid fuel, stopping the formation of flammable vapors. This provides dramatic fire knockdown, an important factor in crash rescue firefighting.
In the early 1970s, National Foam, Inc. invented alcohol-resistant AFFF technology. AR-AFFF is a synthetic foam developed for both hydrocarbon and polar-solvent materials. Polar solvents are combustible liquids that destroy conventional fire-fighting foam. These solvents extract the water contained in the foam, breaking down the foam blanket. Hence, these fuels require an alcohol- or polar-solvent-resistant foam. Alcohol-resistant foam must be bounced off of a surface and allowed to flow down and over the liquid to form its membrane, compared to standard AFFF that can be sprayed directly onto the fire.
In 1993, Pyrocool Technologies Inc. acquired the patent rights to a wetting agent with superior cooling properties that is effective on Class A, Class B, Class D as well as pressurized and 3-dimensional fires involving both hydro carbon based fuels and polar solvents such as alcohol and ethanol. The wetting agent is marketed under the name of Pyrocool. Pyrocool Technologies Inc. was awarded the 1998 Presidential Green Chemistry Award by the USEPA. Carol Browner, the USEPA Administrator in 1998, described Pyrocool as the "Technology for the Third Millennium: The Development and Commercial Introduction of an Environmentally Responsible Fire Extinguishment and Cooling Agent". A dispute with the manufacturer, Baums Castorine, resulted in Baums rebranding this formula under the name Novacool UEF and has been selling this product under that name since 2008.
In 2002, BIOEX a French manufacturer of firefighting foam, pioneer in environmentally friendly foams, launched the first fluorine-free foam (ECOPOL) into the market. The foam concentrate is highly efficient on class B hydrocarbon and polar solvent fires, as well as on class A fires. Their environmental challenge has been to convince their customers to choose their new generation of green products, which are 100% fluorine free, and have proven to be effective.
In 2010, Orchidee International of France developed the first FFHPF, the highest performing fluorine-free foam. The foam has achieved a 97% degradability rating and is currently marketed by Orchidee International under the brand name "BluFoam". The foam is used at 3% both on hydrocarbon and polar solvent fires. | 0 | Colloidal Chemistry |
The high symmetry of the double-cone topology of the linear E ⊗ e JT system directly reflects the high underlying symmetry. It is one of the earliest (if not the earliest) examples in the literature of a conical intersection of potential energy surfaces. Conical intersections have received wide attention in the literature starting in the 1990s and are now considered paradigms of nonadiabatic excited-state dynamics, with far-reaching consequences in molecular spectroscopy, photochemistry and photophysics. Some of these will be commented upon further below. In general, conical intersections are far less symmetric than depicted in the figure. They can be tilted and elliptical in shape etc., and also peaked and sloped intersections have been distinguished in the literature. Furthermore, for more than two degrees of freedom, they are not point-like structures but instead they are seams and complicated, curved hypersurfaces, also known as intersection space. The coordinate sub-space displayed in the figure is also known as a branching plane. | 1 | Solid-state chemistry |
Examples of halide compounds are:
* Sodium chloride (NaCl)
* Potassium chloride (KCl)
* Potassium iodide (KI)
* Lithium chloride (LiCl)
* Copper(II) chloride ()
* Silver chloride (AgCl)
* Calcium chloride ()
* Chlorine fluoride (ClF)
* Organohalides
** Bromomethane ()
** Iodoform ()
* Hydrogen chloride (HCl)
*Hydrogen bromide (HBr) | 1 | Solid-state chemistry |
Trimethylglycine, a betaine, is used as a dietary supplement, although there is no evidence that it is effective or safe. Common side effects of taking oral betaine include nausea and stomach upset. | 0 | Colloidal Chemistry |
"Nanoscale" is usually understood to be the range from 1 to 100 nm because the novel properties that differentiate particles from the bulk material typically develop at that range of sizes.
For some properties, like transparency or turbidity, ultrafiltration, stable dispersion, etc., substantial changes characteristic of nanoparticles are observed for particles as large as 500 nm. Therefore, the term is sometimes extended to that size range. | 0 | Colloidal Chemistry |
The desalination process consists of the separation of salts from an aqueous solution to obtain fresh water from a source of seawater or brackish water; and in turn, a discharge is generated, commonly called brine. | 1 | Solid-state chemistry |
A miniemulsion (also known as nanoemulsion) is a particular type of emulsion. A miniemulsion is obtained by shearing a mixture comprising two immiscible liquid phases (for example, oil and water), one or more surfactants and, possibly, one or more co-surfactants (typical examples are hexadecane or cetyl alcohol). They usually have nanodroplets with uniform size distribution (20–500 nm) and are also known as sub-micron, mini-, and ultra-fine grain emulsions. | 0 | Colloidal Chemistry |
Micellar solubilization is widely utilized, e.g. in laundry washing using detergents, in the pharmaceutical industry, for formulations of poorly soluble drugs in solution form, and in cleanup of oil spills using dispersants. | 0 | Colloidal Chemistry |
Due to their properties (primarily large, tuneable band gaps and efficient intercalation of salts) graphitic carbon nitrides are under research for a variety of applications:
* Photocatalysts
** Decomposition of water to H and O
** Degradation of pollutants
* Large band gap semiconductor
* Heterogeneous catalyst and support
** The significant resilience of carbon nitrides combined with surface and intralayer reactivities make them potentially useful catalysts relying on their labile protons and Lewis base functionalities. Modifications such as doping, protonation and molecular functionalisation can be exploited to improve selectivity and performance.
** Nanoparticle catalysts supported on gCN are under development for both proton exchange membrane fuel cells and water electrolyzers.
** Despite graphitic carbon nitride having some advantages, such as mild band gap (2.7 eV), absorption of visible light and flexibility, it still has limitations for practical applications due to low efficiency of visible light utilization, high recombination rate of the photo generated charge carriers, low electrical conductivity and small specific surface area (g). To modify these shortages, one of the most attractive approaches is doping graphitic carbon nitride with carbon nanomaterials, such as carbon nanotubes. First, carbon nanotubes have large specific surface area, so they can provide more sites to separate the charge carriers, then decrease the recombination rate of the charge carriers and further increase the activity of reduction reaction. Second, carbon nanotubes show high electron conducting ability, which means they can improve graphitic carbon nitride with visible light response, efficient charge carrier separation and transfer, thereby improving its electronic properties. Third, carbon nanotubes can be regarded as a kind of narrow band semiconductor material, also known as a photosensitizer, which can extend the range of the light absorption of semiconductor photocatalytic material, thereby enhancing its utilization of visible light.
* Energy Storage materials
** Due to the intercalation of Li being able to occur to more sites than for graphite due to intra layer voids in addition to intercalation between layers, gCN can store a large amount of Li making them potentially useful for rechargeable batteries. | 1 | Solid-state chemistry |
The historical term for the relative permittivity is dielectric constant. It is still commonly used, but has been deprecated by standards organizations, because of its ambiguity, as some older reports used it for the absolute permittivity ε. The permittivity may be quoted either as a static property or as a frequency-dependent variant, in which case it is also known as the dielectric function. It has also been used to refer to only the real component ε′ of the complex-valued relative permittivity. | 0 | Colloidal Chemistry |
Particles crossing a nanopore are detected one at a time as a transient change in the ionic current flow, which is denoted as a blockade event with its amplitude denoted as the blockade magnitude. As blockade magnitude is proportional to particle size, accurate particle sizing can be achieved after calibration with a known standard. This standard is composed of particles of a known size and concentration. For TRPS, carboxylated polystyrene particles are often used.
Nanopore-based detection allows particle-by-particle assessment of complex mixtures. By selecting an appropriately sized nanopore and adjusting its stretch, the nanopore size can be optimized for particle size and improve measurement accuracy.
Adjustments to nanopore stretch, in combination with a fine-control of pressure and voltage allow TRPS to determine sample concentration and to accurately derive individual particle zeta potential in addition to particle size information. | 0 | Colloidal Chemistry |
In the first case, two solid plates are placed in a solution of rigid spherical macromolecules. If the distance between two plates, , is smaller than the diameter of solute molecules, , then no solute can enter between the plates. This results in pure solvent existing between the plates. The difference in concentration of macromolecules in the solution between the plates and the bulk solution causes a force equal to the osmotic pressure to act on the plates. In a very dilute and monodisperse solution the force is defined by
where is the force, and is the total number of solute molecules. The force causes the entropy of the macromolecules to increase and is attractive when | 0 | Colloidal Chemistry |
Carl Wilhelm Wagner (25 May 1901 – 10 December 1977) was a German physical chemist. He is best known for his pioneering work on solid-state chemistry, where his work on oxidation rate theory, counter diffusion of ions and defect chemistry led to a better understanding of how reactions take place at the atomic level. His life and achievements were honoured in a Solid State Ionics symposium commemorating his 100th birthday in 2001, where he was described as the father of solid-state chemistry. | 1 | Solid-state chemistry |
Nanoparticles are created by EWM when the ambient gas of the system cools the recently produced vaporous metal. EWM can be used to cheaply and efficiently produce nanoparticles at a rate of 50 – 300 grams per hour and at a purity of above 99%. The process requires a relatively low energy consumption as little energy is lost in an electric to thermal energy conversion. Environmental effects are minimal due to the process taking place in a closed system. The Particles can be as small as 10 nm but are most commonly below 100 nm in diameter. Physical attributes of the nanopowder can be altered depending on the parameters of the explosion. For example, as the voltage of the capacitor is raised, the particle diameter decreases. Also, the pressure of the gas environment can change the dispersiveness of the nanoparticles. Through such manipulations the functionality of the nanopowder may be altered.
When EWM is performed in a standard atmosphere containing oxygen, metal oxides are formed. Pure metal nanoparticles can also be produced with EWM in an inert environment, usually argon gas or distilled water. Pure metal nanopowders must be kept in their inert environment because they ignite when exposed to oxygen in air. Often, the metal vapor is contained by operating the mechanism within a steel box or similar container.
Nanoparticles are a relatively new material used in medicine, manufacturing, environmental cleanup and circuitry. Metal oxide and pure metal nanoparticles are used in Catalysis, sensors, oxygen antioxident, self repairing metal, ceramics, UV ray protection, odor proofing, improved batteries, printable circuits, optoelectronic materials, and Environmental remediation. The demand for metal nanoparticles, and therefore production methods, has increased as interest in nanotechnology continues to rise. Despite its overwhelming simplicity and efficiency, it is difficult to modify the experimental apparatus to be used on an industrial scale. As such, EWM has not seen widespread utilization in material production industry due to issues in manufacturing quantity. Still, for some time, Argonide offered metal nanopowders made by the exploding wire method that that were manufactured in Russia. | 0 | Colloidal Chemistry |
As of March 2024, 11 U.S. states and two territories have passed statewide legislation to explicitly ban polystyrene foam:
* In 2019, Maryland was the first state to enact a ban, which went into effect on October 1, 2020. Bans were also passed that year in Maine and Vermont, with both states' laws taking effect on July 1, 2021.
* In 2020, New York passed a ban that took effect on January 1, 2022, while New Jersey passed a ban that took effect on May 4, 2022.
* In 2021, Colorado passed a ban that took effect on January 1, 2024. Virginia passed a ban on polystyrene foam takeout containers that will come into force for large businesses by July 2028 and for small businesses by July 2030. Washington also passed a polystyrene ban, effective starting in June 2023, with food serviceware prohibited starting June 1, 2024.
* In 2023, Delaware, Oregon and Rhode Island all signed bans into law, with provisions set to take effect in each state in 2025.
* Washington, D.C. banned polystyrene foam takeout containers on January 1, 2016. The ban was expanded on January 1, 2021, to include the retail sale of polystyrene foam.
* American Samoa banned the import, sale, and distribution of polystyrene foam containers on February 6, 2024, taking effect 60 days later.
In Hawaii, a de facto ban is in effect after every county enacted polystyrene bans except state-administered Kalawao County. Bans in Hawaii County took effect July 2019, followed by Kauai County, Maui County, and Honolulu County in 2022. Maui separately banned polystyrene foam coolers, and the sale or rental of disposable bodyboards in 2022.
In California, the legislature passed SB54 in June 2022 as the Plastic Pollution Prevention and Packaging Producer Responsibility Act. The law codifies extended producer responsibility (EPR) requirements for plastics, including a requirement that polystyrene be banned if recycling rates do not reach 25% by 2025. Recycling rates averaged 6% at passage, leading some to call the law a de facto ban, anticipating an inability to comply within three years. | 0 | Colloidal Chemistry |
A hydrotrope is a compound that solubilizes hydrophobic compounds in aqueous solutions by means other than micellar solubilization. Typically, hydrotropes consist of a hydrophilic part and a hydrophobic part (similar to surfactants), but the hydrophobic part is generally too small to cause spontaneous self-aggregation. Hydrotropes do not have a critical concentration above which self-aggregation spontaneously starts to occur (as found for micelle- and vesicle-forming surfactants, which have a critical micelle concentration (cmc) and a critical vesicle concentration (cvc)). Instead, some hydrotropes aggregate in a step-wise self-aggregation process, gradually increasing aggregation size. However, many hydrotropes do not seem to self-aggregate at all, unless a solubilizate has been added. Examples of hydrotropes include urea, tosylate, cumenesulfonate and xylenesulfonate.
The term hydrotropy was originally put forward by Carl Neuberg to describe the increase in the solubility of a solute by the addition of fairly high concentrations of alkali metal salts of various organic acids. However, the term has been used in the literature to designate non-micelle-forming substances, either liquids or solids, capable of solubilizing insoluble compounds.
The chemical structure of the conventional Neuberg's hydrotropic salts (proto-type, sodium benzoate) consists generally of two essential parts, an anionic group and a hydrophobic aromatic ring or ring system. The anionic group is involved in bringing about high aqueous solubility, which is a prerequisite for a hydrotropic substance. The type of anion or metal ion appeared to have a minor effect on the phenomenon. On the other hand, planarity of the hydrophobic part has been emphasized as an important factor in the mechanism of hydrotropic solubilization
To form a hydrotrope, an aromatic hydrocarbon solvent is sulfonated, creating an aromatic sulfonic acid. It is then neutralized with a base.
Additives may either increase or decrease the solubility of a solute in a given solvent. These salts that increase solubility are said to "salt in" the solute and those salts that decrease the solubility "salt out" the solute. The effect of an additive depends very much on the influence it has on the structure of water or its ability to compete with the solvent water molecules.
A convenient quantitation of the effect of a solute additive on the solubility of another solute may be obtained by the Setschetow equation:
where
: S is the solubility in the absence of the additive
: S is the solubility in the presence of the additive
: C is the concentration of the additive
: K is the salting coefficient, which is a measure of the sensitivity of the activity coefficient of the solute towards the salt. | 0 | Colloidal Chemistry |
In 1968, Vinograd was elected to the National Academy of Sciences. In 1970 he received the Kendall Award from the American Chemical Society. In 1972, the Helen Hay Whitney Foundation gave him the T. Duckett Jones Award. He was invited to give a number of honorary lectures, including the Burroughs Wellcome Lecture at Harvard in 1970, the Jesse W. Beams Lecture at the University of Virginia in 1972, and the Falk-Plaut Lecture at Columbia University in 1972. | 0 | Colloidal Chemistry |
The most popular model to describe the electrical double layer is the Poisson-Boltzmann (PB) model. This model can be equally used to evaluate double layer forces. Let us discuss this model in the case of planar geometry as shown in the figure on the right. In this case, the electrical potential profile ψ(z) near a charged interface will only depend on the position z. The corresponding Poisson's equation reads in SI units
where ρ is the charge density per unit volume, ε the dielectric permittivity of the vacuum, and ε the dielectric constant of the liquid. For a symmetric electrolyte consisting of cations and anions having a charge ±q, the charge density can be expressed as
where c = N/V are the concentrations of the cations and anions, where N are their numbers and V the sample volume. These profiles can be related to the electrical potential by considering the fact that the chemical potential of the ions is constant. For both ions, this relation can be written as
where is the reference chemical potential, T the absolute temperature, and k the Boltzmann constant. The reference chemical potential can be eliminated by applying the same equation far away from the surface where the potential is assumed to vanish and concentrations attain the bulk concentration c. The concentration profiles thus become
where β = 1/(kT). This relation reflects the Boltzmann distribution of the ions with the energy ±qψ. Inserting these relations into the Poisson equation one obtains the PB equation
The potential profile between two plates is normally obtained by solving this equation numerically.
Once the potential profile is known, the force per unit area between the plates expressed as the disjoining pressure Π can be obtained as follows. The starting point is the Gibbs–Duhem relation for a two component system at constant temperature
Introducing the concentrations c and using the expressions of the chemical potentials μ given above one finds
The concentration difference can be eliminated with the Poisson equation and the resulting equation can be integrated from infinite separation of the plates to the actual separation h by realizing that
Expressing the concentration profiles in terms of the potential profiles one obtains
From a known electrical potential profile ψ(z) one can calculate the disjoining pressure from this equation at any suitable position z. Alternative derivation of the same relation for disjoining pressure involves the stress tensor. | 0 | Colloidal Chemistry |
The alkali metal halides exist as colourless crystalline solids, although as finely ground powders appear white. They melt at high temperature, usually several hundred degrees to colorless liquids. Their high melting point reflects their high lattice energies. At still higher temperatures, these liquids evaporate to give gases composed of diatomic molecules.
These compounds dissolve in polar solvents to give ionic solutions that contain highly solvated anions and cations. Alkali halides dissolve large amounts of the corresponding alkali metal: caesium is completely miscible at all temperatures above the melting point.
The table below provides links to each of the individual articles for these compounds. The numbers beside the compounds show the electronegativity difference between the elements based on the Pauling scale. The higher the number is, the more ionic the solid is. | 1 | Solid-state chemistry |
Molecular wires can be incorporated into polymers, enhancing their mechanical and/or conducting properties. The enhancement of these properties relies on uniform dispersion of the wires into the host polymer. MoSI wires have been made in such composites, relying on their superior solubility within the polymer host compared to other nanowires or nanotubes. Bundles of wires can be used to enhance tribological properties of polymers, with applications in actuators and potentiometers. It has been recently proposed that twisted nanowires could work as electromechanical nanodevices (or torsion nanobalances) to measure forces and torques at nanoscale with great precision. | 1 | Solid-state chemistry |
As tissue replacements, nanocomposite hydrogels need to interact with cells and form functional tissues. With the incorporated nanoparticles and nanomaterials, these hydrogels can mimic the physical, chemical, electrical, and biological properties of most native tissue. Each type of nanocomposite hydrogels has its own unique properties that let it mimic certain types of animal tissue. | 0 | Colloidal Chemistry |
Palladium hydride is a nonstoichiometric material of the approximate composition (0.02 < x < 0.58). This solid conducts hydrogen by virtue of the mobility of the hydrogen atoms within the solid. | 1 | Solid-state chemistry |
Thermoacoustics is the study of the interaction between heat and sound. It a basis of the thermophone. Byron Higgins in 1802 reported "singing flames" which occurred when the necks of jars were put over a hydrogen gas flame. Sondhauss (1850) and Rijke (1859) performed further experiments. A theory of thermoacoustics was produced by Lord Rayleigh in 1878.
The theory and practice of creating sound with electric heat emerged in the late 19th century. In 1880, William Henry Preece observed that, upon connecting a microphone transmitter to a platinum wire, sounds were produced:
In 1917, Harold D. Arnold and of Bell Labs developed a quantitative theory for the thermophone. Since then, thermophones have been used as a precision device for microphone calibration. However, they did not see widespread use elsewhere due to their poor efficiency. | 1 | Solid-state chemistry |
For in-situ bonded face sheets the core is closed-cell foam. The goal of in-situ bonding is to create a metallic bonding between the foam core and face sheets. This is achieved in three ways. A foamable precursor is expanded between two face sheets. When the liquid foam comes in contact with the solid face sheets a metallic bond is established. This is difficult to realize as the oxidation of both aluminium face sheets and foam prevent forming a sound bonding. There is also a risk of melting the face sheets. This procedure is successful when steel is used as face sheets instead of aluminium, while the foam core is aluminium.
Another strategy is to rapidly solidify the surface of a foamable molten metal before it can foam into a dense skin while the interior of the metal evolves to a foam structure. This process yields in an integral-type foam structure. Integral foam sandwich is made of aluminium alloys (AlCu4, AlSi9Cu3) and magnesium alloys (AZ91, AM60). In this process the material for the core and face sheet is the same.
The third way to achieve in-situ bonding consists of compaction of metal powders together with face sheets. This sandwich-compact assembly goes through several rolling steps to attain desired precursor and face sheet thickness. After which this three-layer composite is heated to transform the core layer into foam. The melting point of the face sheet material is above the melting point of the foamable precursor material. The precursor composition is usually Al-Si, Al-Si-Cu or Al-Si-Mg alloys while the face sheets are 3xxx, 5xxx and 6xxx series aluminium alloys. | 0 | Colloidal Chemistry |
Solid-state electronics are semiconductor electronics: electronic equipment that use semiconductor devices such as transistors, diodes and integrated circuits (ICs). The term is also used as an adjective for devices in which semiconductor electronics that have no moving parts replace devices with moving parts, such as the solid-state relay in which transistor switches are used in place of a moving-arm electromechanical relay, or the solid-state drive (SSD) a type of semiconductor memory used in computers to replace hard disk drives, which store data on a rotating disk. | 1 | Solid-state chemistry |
To ensure durability of PCs, mechanical properties are important to study. Elaborate efforts have been made for studying compressive brittleness of porous carbon materials. In 1999, Iizuka, et al. studied the mechanical properties of wood ceramics, a type of porous carbon material. Stable medium-density fiber was used as the base material of wood ceramics and phenol resin was impregnated into the board. Starting at 300 °C, Youngs modulus and the compressive strength first decreased with increasing temperature, but at 500 °C the strength increases sharply until it reaches 800 °C and plateaus. The effects of temperature were due to microstructural changes in the resin during carbonization. Effects of impregnates phenol resin at 800 °C were also investigated. Results showed that Youngs modulus increased with phenol resin impregnation (Figure 1). The maximum Youngs modulus was 5 MPa and the maximum compressive strength was 80 MPa. Wall-bending mechanical test were also performed and it was found that cell wall is breakage was correlated to relative density on compressive strength and Youngs modulus.
Another type of compressive porous carbon consisting of cellulose and graphene aerogels was studied by Mi, et al. Modified cellulose/graphene aerogels (MCGA) was synthesized via bidirectional freeze drying and grafting of long carbon chains through chemical vapor deposition (Figure 2). The final product had a bulk density of 5.9 mg/cm and surface area of 47.3 m/g with flexible cellulose nanofibril and stiff graphene components. After optimizing the concentration of graphene oxide concentration and anisotropic porous structure, tensile tests were performed. It was found that MGCA could recover 99.8% and 96.3% when compressed to 60% and 90% strain, respectively. SEM images showed that due to its unique structure, MCGA pore walls were able to wrinkle and fold during compression. Another unique characteristic of this material is its absorption capacity of 80-197 times its weight towards hydrophobic compounds, such as oils and chemical solvents.
On the contrary, less effort has been made to study the stretchability of porous carbons. Gao, et al. synthesized a long-range lamellar scaffold composed of chitosan and graphene oxide via bidirectional freezing, freeze drying, and annealing. The result is a material with density of 11 mg cm and porosity of about 99.4%. Various tensile tests were conducted, and it was found that carbon spring could revert to its original shape upon 80% compression strain and -60% stretching strain with a Poisson's ratio between 0.05 and 0.1. The narrow hysteresis loop of the stress-strain curve indicates a low energy dissipation (energy loss coefficient of about 0.2) because of its negligible interior friction, localized buckling, or cracks during deformation processes. The stretchable mechanical properties of this material allow for great candidates for vibrational and magnetism sensors. | 0 | Colloidal Chemistry |
Surfactant production in humans begins in type II cells during the alveolar sac stage of lung development. Lamellar bodies appear in the cytoplasm at about 20 weeks gestation. These lamellar bodies are secreted by exocytosis into the alveolar lining fluid, where the surfactant forms a meshwork of tubular myelin Full term infants are estimated to have an alveolar storage pool of approximately 100 mg/kg of surfactant, while preterm infants have an estimated 4–5 mg/kg at birth.
Club cells also produce a component of lung surfactant.
Alveolar surfactant has a half-life of 5 to 10 hours once secreted. It can be both broken down by macrophages and/or reabsorbed into the lamellar structures of type II pneumocytes. Up to 90% of surfactant DPPC (dipalmitoylphosphatidylcholine) is recycled from the alveolar space back into the type II pneumocyte. This process is believed to occur through SP-A stimulating receptor-mediated, clathrin dependent endocytosis. The other 10% is taken up by alveolar macrophages and digested. | 0 | Colloidal Chemistry |
Like other magnetic semiconductors, is formed by doping a standard semiconductor with magnetic elements. This is done using the growth technique molecular beam epitaxy, whereby crystal structures can be grown with atom layer precision. In the manganese substitute into gallium sites in the GaAs crystal and provide a magnetic moment. Because manganese has a low solubility in GaAs, incorporating a sufficiently high concentration for ferromagnetism to be achieved proves challenging. In standard molecular beam epitaxy growth, to ensure that a good structural quality is obtained, the temperature the substrate is heated to, known as the growth temperature, is normally high, typically ~600 °C. However, if a large flux of manganese is used in these conditions, instead of being incorporated, segregation occurs where the manganese accumulate on the surface and form complexes with elemental arsenic atoms.
This problem was overcome using the technique of low-temperature molecular beam epitaxy. It was found, first in
and then later used for ,
that by utilising non-equilibrium crystal growth techniques larger dopant concentrations could be successfully incorporated. At lower temperatures, around 250 °C, there is insufficient thermal energy for surface segregation to occur but still sufficient for a good quality single crystal alloy to form.
In addition to the substitutional incorporation of manganese, low-temperature molecular beam epitaxy also causes the inclusion of other impurities. The two other common impurities are interstitial manganese
and arsenic antisites.
The former is where the manganese atom sits between the other atoms in the zinc-blende lattice structure and the latter is where an arsenic atom occupies a gallium site. Both impurities act as double donors, removing the holes provided by the substitutional manganese, and as such they are known as compensating defects. The interstitial manganese also bond antiferromagnetically to substitutional manganese, removing the magnetic moment. Both these defects are detrimental to the ferromagnetic properties of the , and so are undesired.
The temperature below which the transition from paramagnetism to ferromagnetism occurs is known as the Curie temperature, T. Theoretical predictions based on the Zener model suggest that the Curie temperature scales with the quantity of manganese, so T above 300K is possible if manganese doping levels as high as 10% can be achieved.
After its discovery by Ohno et al., the highest reported Curie temperatures in rose from 60K to 110K. However, despite the predictions of room-temperature ferromagnetism, no improvements in T were made for several years.
As a result of this lack of progress, predictions started to be made that 110K was a fundamental limit for . The self-compensating nature of the defects would limit the possible hole concentrations, preventing further gains in T.
The major breakthrough came from improvements in post-growth annealing. By using annealing temperatures comparable to the growth temperature it was possible to pass the 110K barrier.
These improvements have been attributed to the removal of the highly mobile interstitial manganese.
Currently, the highest reported values of T in are around 173K,
still well below the much sought room-temperature. As a result, measurements on this material must be done at cryogenic temperatures, currently precluding any application outside of the laboratory. Naturally, considerable effort is being spent in the search for an alternative magnetic semiconductors that does not share this limitation.
In addition to this, as molecular beam epitaxy techniques and equipment are refined and improved it is hoped that greater control over growth conditions will allow further incremental advances in the Curie temperature of . | 1 | Solid-state chemistry |
A particle may diffuse to a surface in quiescent conditions, but this process is inefficient as a thick depletion layer develops, which leads to a progressive slowing down of the deposition. When particle deposition is efficient, it proceeds almost exclusively in a system under flow. In such conditions, the hydrodynamic flow will transport the particles close to the surface. Once a particle is situated close to the surface, it will attach spontaneously, when the particle-surface interactions are attractive. In this situation, one refers to favorable deposition conditions. When the interaction is repulsive at larger distances, but attractive at shorter distances, deposition will still occur but it will be slowed down. One refers to unfavorable deposition conditions here. The initial stages of the deposition process can be described with the rate equation
where ; is the number density of deposited particles, is the time, the particle number concentration, and the deposition rate coefficient. The rate coefficient depends on the flow velocity, flow geometry, and the interaction potential of the depositing particle with the substrate. In many situations, this potential can be approximated by a superposition of attractive van der Waals forces and repulsive electrical double layer forces and can be described by DLVO theory. When the charge of the particles is of the same sign as the substrate, deposition will be favorable at high salt levels, while it will be unfavorable at lower salt levels. When the charge of the particles is of the opposite sign as the substrate, deposition is favorable for all salt levels, and one observes a small enhancement of the deposition rate with decreasing salt level due to attractive electrostatic double layer forces. Initial stages of the deposition process are relatively similar to the early stages of particle heteroaggregation, whereby one of the particles is much larger than the other. | 0 | Colloidal Chemistry |
Drug delivery strategies of inorganic nanoparticles are dependent on material properties. The active targeting of inorganic nanoparticle drug carriers is often achieved by surface functionalization with specific ligands of nanoparticles. For example, the inorganic multifunctional nanovehicle (5-FU/Fe3O4/αZrP@CHI-FA-R6G) is able to accomplish tumor optical imaging and therapy simultaneously. It can be directed to the location of cancer cells with sustained release behavior.
Studies have also been done on gold nanoparticle responses to local near-infrared (NIR) light as a stimuli for drug release. In one study, gold nanoparticles functionalized with double-stranded DNA encapsulated with drug molecules, were irradiated with NIR light. The particles generated heat and denatured the double-stranded DNA, which triggered the release of drugs at the target site.
Studies also suggest that a porous structure is beneficial to attain a sustained or pulsatile release. Porous inorganic materials demonstrate high mechanical and chemical stability within a range of physiological conditions. The well-defined surface properties, such as high pore volume, narrow pore diameter distribution, and high surface area allow the entrapment of drugs, proteins and other biogenic molecules with predictable and reproducible release patterns. | 0 | Colloidal Chemistry |
Salt tectonics, or halokinesis, or halotectonics, is concerned with the geometries and processes associated with the presence of significant thicknesses of evaporites containing rock salt within a stratigraphic sequence of rocks. This is due both to the low density of salt, which does not increase with burial, and its low strength.
Salt structures (excluding undeformed layers of salt) have been found in more than 120 sedimentary basins around the world. | 1 | Solid-state chemistry |
The usual preparation of Krogmann's salt involves the evaporation of a 5:1 molar ratio mixture of the salts K[Pt(CN)] and K[Pt(CN)Br] in water to give copper-colored needles of K[Pt(CN)]Br·2.6 HO.
::5K[Pt(CN)] + K[Pt(CN)Br] + 15.6 HO → 6K[Pt(CN)]Br·2.6 HO
Because excess Pt or Pt complex crystallizes out with the product when the reactant ratio is changed, the product is therefore well defined, although non-stoichiometric. | 1 | Solid-state chemistry |
Reagent grade detergents are employed for the isolation and purification of integral membrane proteins found in biological cells. Solubilization of cell membrane bilayers requires a detergent that can enter the inner membrane monolayer. Advancements in the purity and sophistication of detergents have facilitated structural and biophysical characterization of important membrane proteins such as ion channels also the disrupt membrane by binding lipopolysaccharide, transporters, signaling receptors, and photosystem II. | 0 | Colloidal Chemistry |
In the field of "nano" spray drying a new heating system is used to provide the drying gas to produce the particles. The gas flow in the system is laminar and not turbulent as in common spray drying. The advantage of a laminar flow is that the particles fall straight down from the spray head and do not stick to the glass wall.
The laminar flow is produced by pressing the air through a porous metal foam. | 0 | Colloidal Chemistry |
Nucleation in microcellular plastic is an important stage which decides the final cell size, cell density and cell morphology of the foam. In the recent past, numerous researchers have studied the cell nucleation phenomenon in microcellular polymers.
Studies were performed with ultrasound induced nucleation during microcellular foaming of Acrylonitrile butadiene styrene polymers. M.C.Guo studied nucleation under the shear action. As the shear enhanced, the cell size diminished and thereby increased the cell density in the foam. | 0 | Colloidal Chemistry |
Current state-of-the-art solid oxide fuel cells (SOFCs) and electrolysis cells (SOECs) frequently incorporate electrodes made of MIEC materials. SOFCs are unique among fuel cells in that negatively charged ions (O) are transported from the cathode to the anode across the electrolyte, making MIEC cathode materials critical to achieving high performance. These fuel cells operate with the following oxidation-reduction reaction:
: Anode Reaction: 2H + 2O → 2HO + 4e
: Cathode Reaction: O + 4e → 2O
: Overall Cell Reaction: 2H + O → 2HO
MIECs like lanthanum strontium cobalt ferrite (LSCF) are frequently the subject of modern fuel cell research, as they enable the reduction reaction to occur over the entire cathode surface area instead of only at the cathode/electrolyte interface.
One of the most commonly used oxygen electrode (cathode) materials is the H-MIEC LSM-YSZ, consisting of lanthanum strontium manganite (LSM) infiltrated onto a YO-doped ZrO scaffold. The LSM nanoparticles are deposited on the walls of the porous YSZ scaffold to provide an electronically conductive pathway and a high density of TPBs for the reduction reaction to occur. | 1 | Solid-state chemistry |
The compressibility of an ionic compound is strongly determined by its structure, and in particular the coordination number. For example, halides with the caesium chloride structure (coordination number 8) are less compressible than those with the sodium chloride structure (coordination number 6), and less again than those with a coordination number of 4. | 1 | Solid-state chemistry |
The CMC generally depends on the method of measuring the samples, since A and B depend on the properties of the solution such as conductance, photochemical characteristics, or surface tension. When the degree of aggregation is monodisperse, then the CMC is not related to the method of measurement. On the other hand, when the degree of aggregation is polydisperse, then CMC is related to both the method of measurement and the dispersion.
The common procedure to determine the CMC from experimental data is to look for the intersection (inflection point) of two straight lines traced through plots of the measured property versus the surfactant concentration. This visual data analysis method is highly subjective and can lead to very different CMC values depending on the type of representation, the quality of the data and the chosen interval around the CMC. A preferred method is the fit of the experimental data with a model of the measured property. Fit functions for properties such as electrical conductivity, surface tension, NMR chemical shifts, absorption, self-diffusion coefficients, fluorescence intensity and mean translational diffusion coefficient of fluorescent dyes in surfactant solutions have been presented. These fit functions are based on a model for the concentrations of monomeric and micellised surfactants in solution, which establishes a well-defined analytical definition of the CMC, independent from the technique.
The CMC is the concentration of surfactants in the bulk at which micelles start forming. The word bulk is important because surfactants partition between the bulk and interface and CMC is independent of interface and is therefore a characteristic of the surfactant molecule. In most situations, such as surface tension measurements or conductivity measurements, the amount of surfactant at the interface is negligible compared to that in the bulk and CMC can be approximated by the total concentration. In practice, CMC data is usually collected using laboratory instruments which allow the process to be partially automated, for instance by using specialised tensiometers. | 0 | Colloidal Chemistry |
Dincă completed his postdoc studies at MIT, where he was promoted to associate professor in 2010 and, in 2017, tenured. | 1 | Solid-state chemistry |
The meaning of the term cocrystal is subject of disagreement. One definition states that a cocrystal is a crystalline structure composed of at least two components, where the components may be atoms, ions or molecules. This definition is sometimes extended to specify that the components be solid in their pure forms at ambient conditions. However, it has been argued that this separation based on ambient phase is arbitrary. A more inclusive definition is that cocrystals "consist of two or more components that form a unique crystalline structure having unique properties." Due to variation in the use of the term, structures such as solvates and clathrates may or may not be considered cocrystals in a given situation. The difference between a crystalline salt and a cocrystal lies merely in the transfer of a proton. The transfer of protons from one component to another in a crystal is dependent on the environment. For this reason, crystalline salts and cocrystals may be thought of as two ends of a proton transfer spectrum, where the salt has completed the proton transfer at one end and an absence of proton transfer exists for cocrystals at the other end. | 1 | Solid-state chemistry |
In nonlinear optics it is possible to reverse the destructive interference of so-called inhomogeneously broadened systems which contain a distribution of uncoupled subsystems with different resonance frequencies.
For example, consider a four-wave-mixing experiment in which the first short laser pulse excites all transitions at .
As a result of the destructive interference between the different frequencies the overall polarization decays to zero.
A second pulse arriving at is able to conjugate the phases of the individual microscopic polarizations, i.e., , of the inhomogeneously broadened system.
The subsequent unperturbed dynamical evolution of the polarizations leads to rephasing such that all polarization are in phase at which results in a measurable macroscopic signal.
Thus, this so-called photon echo occurs since all individual polarizations are in phase and add up constructively at .
Since the rephasing is only possible if the polarizations remain coherent, the loss of coherence can be determined by measuring the decay of the photon echo amplitude with increasing time delay.
When photon echo experiments are performed in semiconductors with exciton resonances, it is essential to include many-body effects in the theoretical analysis since they may qualitatively alter the dynamics. For example, numerical solutions of the SBEs have demonstrated that the dynamical reduction of the band gap which originates from the Coulomb interaction among the photoexcited electrons and holes is able to generate a photon echo even for resonant excitation of a single discrete exciton resonance with a pulse of sufficient intensity.
Besides the rather simple effect of inhomogeneous broadening, spatial fluctuations of the energy, i.e., disorder, which in semiconductor nanostructure may, e.g., arise from imperfection of the interfaces between different materials, can also lead to a decay of the photon echo amplitude with increasing time delay. To consistently treat this phenomenon of disorder induced dephasing the SBEs need to be solved including biexciton correlations.
As shown in Ref. such a microscopic theoretical approach is able to describe disorder induced dephasing in good agreement with experimental results. | 1 | Solid-state chemistry |
Another property of nanoparticles that is heavily influenced by the surfactants is the solubility of the nanoparticle. One can imagine that a metallic nanoparticle would not dissolve well in organic solvents. By adding the surfactants the nanoparticles will stay more evenly dispersed throughout the solvent. This is due to the, often, amphiphilic nature of the surfactants. The interfacial layer can be used to essentially tune the solubility of nanoparticles in different media, which can range from extremely hydrophilic to hydrophobic. | 0 | Colloidal Chemistry |
Copper(I) thiocyanate forms one double salt with the group 1 elements, CsCu(SCN). The double salt only forms from concentrated solutions of CsSCN, into which CuSCN dissolves. From less concentrated solutions, solid CuSCN separates reflecting its low solubility. When brought together with potassium, sodium or barium thiocyanate, and brought to crystallisation by concentrating the solution, mixed salts will crystallise out. These are not considered true double salts. As with CsCu (SNC), copper(I) thiocyanate separates out when these mixed salts are redissolved or their solutions diluted. | 1 | Solid-state chemistry |
His biography at the Gdańsk University of Technology describes him as a New Yorker, dedicated supporter of the New York Yankees, passionate astronomer and amateur brewer. | 1 | Solid-state chemistry |
Phosphonium betaines are intermediates in the Wittig reaction. The addition of betaine to polymerase chain reactions improves the amplification of DNA by reducing the formation of secondary structure in GC-rich regions. The addition of betaine may enhance the specificity of the polymerase chain reaction by eliminating the base pair composition dependence of DNA melting. | 0 | Colloidal Chemistry |
A sol is a colloidal suspension made out of tiny solid particles in a continuous liquid medium. Sols are stable and exhibit the Tyndall effect, which is the scattering of light by the particles in the colloid. Examples include amongst others blood, pigmented ink, cell fluids, paint, antacids and mud.
Artificial sols can be prepared by two main methods: dispersion and condensation. In the dispersion method, solid particles are reduced to colloidal dimensions through techniques such as ball milling and Bredig's arc method. In the condensation method, small particles are formed from larger molecules through a chemical reaction.
The stability of sols can be maintained through the use of dispersing agents, which prevent the particles from clumping together or settling out of the suspension. Sols are often used in the sol-gel process, in which a sol is converted into a gel through the addition of a crosslinking agent.
In a sol, solid particles are dispersed in a liquid continuous phase, while in an emulsion, liquid droplets are dispersed in a liquid or semi-solid continuous phase.
Properties of a Colloid (applicable to sols)
* Heterogeneous Mixture
* Size of colloid varies from 1 nm - 100 nm
* They show the Tyndall effect
* They are quite stable and hence they do not settle down when left undisturbed | 0 | Colloidal Chemistry |
Stokes, transitional and Newtonian settling describe the behaviour of a single spherical particle in an infinite fluid, known as free settling. However this model has limitations in practical application. Alternate considerations, such as the interaction of particles in the fluid, or the interaction of the particles with the container walls can modify the settling behaviour. Settling that has these forces in appreciable magnitude is known as hindered settling. Subsequently, semi-analytic or empirical solutions may be used to perform meaningful hindered settling calculations. | 0 | Colloidal Chemistry |
From the Municipal high School, Burdwan, Mukherjee appeared in March 1909 at the last Entrance Examination of the Calcutta University and got a District Scholarship. Jnanendra Nath was a student of Presidency College (1909–1915) and received his BSc (1913) and MSc (1915) degrees from the Rajabazar Science College, Calcutta University.
Based on his thesis for MSc Degree a paper on Electric Synthesis of Colloids was published in the Journal of the American Chemical Society (1915,39,292). | 0 | Colloidal Chemistry |
The colloidal probe technique is commonly used to measure interaction forces acting between colloidal particles and/or planar surfaces in air or in solution. This technique relies on the use of an atomic force microscope (AFM). However, instead of a cantilever with a sharp AFM tip, one uses the colloidal probe. The colloidal probe consists of a colloidal particle of few micrometers in diameter that is attached to an AFM cantilever. The colloidal probe technique can be used in the sphere-plane or sphere-sphere geometries (see figure). One typically achieves a force resolution between 1 and 100 pN and a distance resolution between 0.5 and 2 nm.
The colloidal probe technique has been developed in 1991 independently by Ducker and Butt. Since its development this tool has gained wide popularity in numerous research laboratories, and numerous reviews are available in the scientific literature.
Alternative techniques to measure force between surfaces involve the surface forces apparatus, total internal reflection microscopy, and optical tweezers techniques to with video microscopy. | 0 | Colloidal Chemistry |
Electrophoresis is used for estimating zeta potential of particulates, whereas streaming potential/current is used for porous bodies and flat surfaces.
In practice, the zeta potential of dispersion is measured by applying an electric field across the dispersion. Particles within the dispersion with a zeta potential will migrate toward the electrode of opposite charge with a velocity proportional to the magnitude of the zeta potential.
This velocity is measured using the technique of the laser Doppler anemometer. The frequency shift or phase shift of an incident laser beam caused by these moving particles is measured as the particle mobility, and this mobility is converted to the zeta potential by inputting the dispersant viscosity and dielectric permittivity, and the application of the Smoluchowski theories. | 0 | Colloidal Chemistry |
The term microemulsion was first used by T. P. Hoar and J. H. Shulman, professors of chemistry at Cambridge University, in 1943. Alternative names for these systems are often used, such as transparent emulsion, swollen micelle, micellar solution, and solubilized oil. More confusingly still, the term microemulsion can refer to the single isotropic phase that is a mixture of oil, water and surfactant, or to one that is in equilibrium with coexisting predominantly oil and/or aqueous phases, or even to other non-isotropic phases. As in the binary systems (water/surfactant or oil/surfactant), self-assembled structures of different types can be formed, ranging, for example, from (inverted) spherical and cylindrical micelles to lamellar phases and bicontinuous microemulsions, which may coexist with predominantly oil or aqueous phases. | 0 | Colloidal Chemistry |
By the 18th century, higher quality American potash was increasingly exported to Britain. In the late 18th and early 19th centuries, potash production provided settlers in North America badly needed cash and credit as they cleared wooded land for crops. To make full use of their land, settlers needed to dispose of excess wood. The easiest way to accomplish this was to burn any wood not needed for fuel or construction. Ashes from hardwood trees could then be used to make lye, which could either be used to make soap or boiled down to produce valuable potash. Hardwood could generate ashes at the rate of 60 to 100 bushels per acre (500 to 900 m/km). In 1790, the sale of ashes could generate $3.25 to $6.25 per acre ($800 to $1,500/km) in rural New York State – nearly the same rate as hiring a laborer to clear the same area. Potash making became a major industry in British North America. Great Britain was always the most important market. The American potash industry followed the woodsman's ax across the country. | 1 | Solid-state chemistry |
Fluorescent properties in nanodiamonds arise from the presence of nitrogen-vacancy (NV) centers, nitrogen atoms next to a vacancy. Fluorescent nanodiamond (FND) was invented in 2005 and has since been used in various fields of study. The invention received a US patent in 2008 , and a subsequent patent in 2012 . NV centers can be created by irradiating nanodiamonds with high-energy particles (electrons, protons, helium ions), followed by vacuum-annealing at 600–800°C. Irradiation forms vaccines in the diamond structure while vacuum-annealing migrates these vacancies, which will get trapped by nitrogen atoms within the nanodiamond. This process produces two types of NV centers. Two types of NV centers are formed—neutral (NV0) and negatively charged (NV–)—and these have different emission spectra. The NV– the center is of particular interest because it has an S = 1 spin ground state that can be spin-polarized by optical pumping and manipulated using electron paramagnetic resonance. Fluorescent nanodiamonds combine the advantages of semiconductor quantum dots (small size, high photostability, bright multicolor fluorescence) with biocompatibility, non-toxicity, and rich surface chemistry, which means that they have the potential to revolutionize Vivo imaging applications. | 0 | Colloidal Chemistry |
Potassium is the third major plant and crop nutrient after nitrogen and phosphorus. It has been used since antiquity as a soil fertilizer (about 90% of current use). Elemental potassium does not occur in nature because it reacts violently with water. As part of various compounds, potassium makes up about 2.6% of the Earths crust by mass and is the seventh most abundant element, similar in abundance to sodium at approximately 1.8% of the crust. Potash is important for agriculture because it improves water retention, yield, nutrient value, taste, color, texture and disease resistance of food crops. It has wide application to fruit and vegetables, rice, wheat and other grains, sugar, corn, soybeans, palm oil and cotton, all of which benefit from the nutrients quality-enhancing properties.
Demand for food and animal feed has been on the rise since 2000. The United States Department of Agriculture's Economic Research Service (ERS) attributes the trend to average annual population increases of 75 million people around the world. Geographically, economic growth in Asia and Latin America greatly contributed to the increased use of potash-based fertilizer. Rising incomes in developing countries also were a factor in the growing potash and fertilizer use. With more money in the household budget, consumers added more meat and dairy products to their diets. This shift in eating patterns required more acres to be planted, more fertilizer to be applied and more animals to be fed—all requiring more potash.
After years of trending upward, fertilizer use slowed in 2008. The worldwide economic downturn is the primary reason for the declining fertilizer use, dropping prices, and mounting inventories.
The world's largest consumers of potash are China, the United States, Brazil, and India. Brazil imports 90% of the potash it needs. Potash consumption for fertilizers is expected to increase to about 37.8 million tonnes by 2022.
Potash imports and exports are often reported in KO equivalent, although fertilizer never contains potassium oxide, per se, because potassium oxide is caustic and hygroscopic. | 1 | Solid-state chemistry |
Nickel oxide hydroxide is the inorganic compound with the chemical formula NiO(OH). It is a black solid that is insoluble in all solvents but attacked by base and acid. It is a component of the nickel–metal hydride battery and of the nickel–iron battery. | 1 | Solid-state chemistry |
Although the exact mechanism is not well understood, DATEM appears to interact with the hydrophobic parts of gluten, helping its proteins unfold and form cross-linked structures. DATEM is composed of mixed esters of glycerin in which one or more of the hydroxyl groups of glycerin have been esterified by diacetyl tartaric acid and by fatty acids. The ingredient is prepared by the reaction of diacetyl tartaric anhydride with mono- and diglycerides that are derived from edible sources. The major components are a glycerol molecule with a stearic acid residue, a diacetyltartaric acid residue, and a free secondary hydroxyl group.
Unlike other commercially used dough emulsifiers, DATEM does not form starch complexes. Its main function is as a strengthener. Typically, DATEM is 0.375 to 0.5% of the total flour weight in most commercial baking. | 0 | Colloidal Chemistry |
Frank was elected Fellow of the Royal Society in 1954, delivering the Bakerian Lecture in 1973. He was knighted in 1977. He was also awarded honorary degrees by seven universities.
In 1963 he won the Fernand Holweck Medal and Prize.
In 1967 he was awarded the A. A. Griffith Medal and Prize. He was also a member of the Materials Science Club Awards Sub-Committee which selected the Griffith medallist for 1972 (L. R. G. Treloar).
In 1994 he was awarded the Royal Societys Copley Medal, its highest honour, "in recognition of his fundamental contribution to the theory of crystal morphology, in particular to the source of dislocations and their consequences in interfaces and crystal growth; to fundamental understanding of liquid crystals and the concept of disclination; and to the extension of crystallinity concepts to aperiodic crystals."' | 0 | Colloidal Chemistry |
Making the connections stiffer and stronger than the strut members means that stress response is governed by the struts. Extending dimensional scaling methods to include the connections shows that the mass density cost of robust connections – which scale with the strut's cross-sectional area – is low for ultralight materials, where strut diameter dominates mass density scaling. The relative density (ρ/ρs) of these materials is the sum of the relative density contribution of the strut members (ρm/ρs) and the relative density contribution of the connections (ρc/ρs). The strut members have a thickness t and length L. The connections transfer forces through load-bearing surface contacts, requiring that the characteristic dimensions of the connections scale with the cross section of the attached strut members, t2, because this dimension determines the maximum stress transferable through the joint.
These definitions give a cubic scaling relation between the relative mass contribution of the joints and the struts thickness-to-length ratio (ρc/ρs ∝ Cc(t/L)3, where Cc is the connection contribution constant determined by the lattice geometry). The struts relative density contribution scales quadratically with the thickness-to-length ratio of the struts (ρm/ρs ∝ Cm (t/L)2), which agrees with the literature on classical cellular materials. Mechanical properties (such as modulus and strength) scale with overall relative density, which in turn scales primarily with the strut and not the connection, considering only open cell lattices with slender struts [t/L < 0.1 (7)], given that the geometric constants Cc and Cm are of the same order of magnitude [ρ/ρs ∝ Cc (t/L)3 + Cm (t/L)2]. The density cost of the mechanical joints decreases with increasing strut member slenderness (decreasing t/L) and decreasing relative density.
Tiling the cross-shaped parts forms the lattice structure. Each part contributes four conjoined strut members to one locally central node and one strut to four peripheral nodes. A shear clip inserted through the four coincident connection holes links the cells.
Each cell includes aligned fiber composite beams and looped fiber load-bearing holes that reversibly chain together to form volume-filling lattices. Mass-produced cells can be assembled to fill arbitrary structural shapes, with a resolution prescribed by the part scale that matches the variability of an application's boundary stress. The periodic nature of assemblies simplifies behavior analysis and prediction. | 0 | Colloidal Chemistry |
Brine is an auxiliary agent in water softening and water purification systems involving ion exchange technology. The most common example are household dishwashers, utilizing sodium chloride in form of dishwasher salt. Brine is not involved in the purification process itself, but used for regeneration of ion-exchange resin on cyclical basis. The water being treated flows through the resin container until the resin is considered exhausted and water is purified to a desired level. Resin is then regenerated by sequentially backwashing the resin bed to remove accumulated solids, flushing removed ions from the resin with a concentrated solution of replacement ions, and rinsing the flushing solution from the resin. After treatment, ion-exchange resin beads saturated with calcium and magnesium ions from the treated water, are regenerated by soaking in brine containing 6–12% NaCl. The sodium ions from brine replace the calcium and magnesium ions on the beads. | 1 | Solid-state chemistry |
Quick clay, also known as Leda clay and Champlain Sea clay in Canada, is any of several distinctively sensitive glaciomarine clays found in Canada, Norway, Russia, Sweden, Finland, the United States and other locations around the world. The clay is so unstable that when a mass of quick clay is subjected to sufficient stress, the material behavior may drastically change from that of a particulate material to that of a watery fluid. Landslides occur because of the sudden soil liquefaction caused by external sollicitations such as vibrations induced by an earthquake, or massive rainfalls. | 0 | Colloidal Chemistry |
Nanoparticles of certain materials can be created by "wet" chemical processes, in which solutions of suitable compounds are mixed or otherwise treated to form an insoluble precipitate of the desired material. The size of the particles of the latter is adjusted by choosing the concentration of the reagents and the temperature of the solutions, and through the addition of suitable inert agents that affect the viscosity and diffusion rate of the liquid. With different parameters, the same general process may yield other nanoscale structures of the same material, such as aerogels and other porous networks.
The nanoparticles formed by this method are then separated from the solvent and soluble byproducts of the reaction by a combination of evaporation, sedimentation, centrifugation, washing, and filtration.Alternatively, if the particles are meant to be deposited on the surface of some solid substrate, the starting solutions can be by coated on that surface by dipping or spin-coating, and the reaction can be carried out in place.
Electroless deposition provides a unique opportunity for growing nanoparticles onto surface without the need for costly spin coating, electrodeposition, or physical vapor deposition. Electroless deposition processes can form colloid suspensions catalytic metal or metal oxide deposition. The suspension of nanoparticles that result from this process is an example of colloid. Typical instances of this method are the production of metal oxide or hydroxide nanoparticles by hydrolysis of metal alkoxides and chlorides.
Besides being cheap and convenient, the wet chemical approach allows fine control of the particle's chemical composition. Even small quantities of dopants, such as organic dyes and rare earth metals, can be introduced in the reagent solutions end up uniformly dispersed in the final product. | 0 | Colloidal Chemistry |
Kauzlarichs research focuses on synthesis and characterization of novel solid state materials. Some of Kauzlarichs publications from her independent research career are listed below:
Kauzlarich has also been a longstanding global expert on the preparation of colloidal nanoclusters and most particularly the preparation of challenging to access Group IV derivatives. These materials hold promise in the areas of biomedicine alongside, importantly, next-generation devices with novel optical and transport properties. Listed below are some of her research team's publications in this research area to-date: | 1 | Solid-state chemistry |
An ionomer () (iono- + -mer) is a polymer composed of repeat units of both electrically neutral repeating units and ionized units covalently bonded to the polymer backbone as pendant group moieties. Usually no more than 15 mole percent are ionized. The ionized units are often carboxylic acid groups.
The classification of a polymer as an ionomer depends on the level of substitution of ionic groups as well as how the ionic groups are incorporated into the polymer structure. For example, polyelectrolytes also have ionic groups covalently bonded to the polymer backbone, but have a much higher ionic group molar substitution level (usually greater than 80%); ionenes are polymers where ionic groups are part of the actual polymer backbone. These two classes of ionic-group-containing polymers have vastly different morphological and physical properties and are therefore not considered ionomers.
Ionomers have unique physical properties including electrical conductivity and viscosity—increase in ionomer solution viscosity with increasing temperatures (see conducting polymer). Ionomers also have unique morphological properties as the non-polar polymer backbone is energetically incompatible with the polar ionic groups. As a result, the ionic groups in most ionomers will undergo microphase separation to form ionic-rich domains.
Commercial applications for ionomers include golf ball covers, semipermeable membranes, sealing tape and thermoplastic elastomers. Common examples of ionomers include polystyrene sulfonate, Nafion and Hycar. | 1 | Solid-state chemistry |
A solid has an infinite number of allowed bands, just as an atom has infinitely many energy levels. However, most of the bands simply have too high energy, and are usually disregarded under ordinary circumstances.
Conversely, there are very low energy bands associated with the core orbitals (such as 1s electrons). These low-energy core bands are also usually disregarded since they remain filled with electrons at all times, and are therefore inert.
Likewise, materials have several band gaps throughout their band structure.
The most important bands and band gaps—those relevant for electronics and optoelectronics—are those with energies near the Fermi level.
The bands and band gaps near the Fermi level are given special names, depending on the material:
* In a semiconductor or band insulator, the Fermi level is surrounded by a band gap, referred to as the band gap (to distinguish it from the other band gaps in the band structure). The closest band above the band gap is called the conduction band, and the closest band beneath the band gap is called the valence band. The name "valence band" was coined by analogy to chemistry, since in semiconductors (and insulators) the valence band is built out of the valence orbitals.
* In a metal or semimetal, the Fermi level is inside of one or more allowed bands. In semimetals the bands are usually referred to as "conduction band" or "valence band" depending on whether the charge transport is more electron-like or hole-like, by analogy to semiconductors. In many metals, however, the bands are neither electron-like nor hole-like, and often just called "valence band" as they are made of valence orbitals. The band gaps in a metal's band structure are not important for low energy physics, since they are too far from the Fermi level. | 1 | Solid-state chemistry |
The most known and widely used theory for calculating zeta potential from experimental data is that developed by Marian Smoluchowski in 1903. This theory was originally developed for electrophoresis; however, an extension to electroacoustics is now also available. Smoluchowski's theory is powerful because it is valid for dispersed particles of any shape and any concentration. However, it has its limitations:
*Detailed theoretical analysis proved that Smoluchowski's theory is valid only for a sufficiently thin double layer, when the Debye length, , is much smaller than the particle radius, :
:The model of the "thin double layer" offers tremendous simplifications not only for electrophoresis theory but for many other electrokinetic and electroacoustic theories. This model is valid for most aqueous systems because the Debye length is typically only a few nanometers in water. The model breaks only for nano-colloids in a solution with ionic strength approaching that of pure water.
*Smoluchowski's theory neglects the contribution of surface conductivity. This is expressed in modern theories as the condition of a small Dukhin number:
The development of electrophoretic and electroacoustic theories with a wider range of validity was a purpose of many studies during the 20th century. There are several analytical theories that incorporate surface conductivity and eliminate the restriction of the small Dukhin number for both the electrokinetic and electroacoustic applications.
Early pioneering work in that direction dates back to Overbeek and Booth.
Modern, rigorous electrokinetic theories that are valid for any zeta potential, and often any , stem mostly from Soviet Ukrainian (Dukhin, Shilov, and others) and Australian (OBrien, White, Hunter, and others) schools. Historically, the first one was Dukhin–Semenikhin theory. A similar theory was created ten years later by OBrien and Hunter. Assuming a thin double layer, these theories would yield results that are very close to the numerical solution provided by O'Brien and White. There are also general electroacoustic theories that are valid for any values of Debye length and Dukhin number. | 0 | Colloidal Chemistry |
Until the Industrial Revolution, soapmaking was conducted on a small scale and the product was rough. In 1780, James Keir established a chemical works at Tipton, for the manufacture of alkali from the sulfates of potash and soda, to which he afterwards added a soap manufactory. The method of extraction proceeded on a discovery of Keir's. In 1790, Nicolas Leblanc discovered how to make alkali from common salt. Andrew Pears started making a high-quality, transparent soap, Pears soap, in 1807 in London. His son-in-law, Thomas J. Barratt, became the brand manager (the first of its kind) for Pears in 1865. In 1882, Barratt recruited English actress and socialite Lillie Langtry to become the poster-girl for Pears soap, making her the first celebrity to endorse a commercial product.
William Gossage produced low-priced, good-quality soap from the 1850s. Robert Spear Hudson began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestle. American manufacturer Benjamin T. Babbitt introduced marketing innovations that included the sale of bar soap and distribution of product samples. William Hesketh Lever and his brother, James, bought a small soap works in Warrington in 1886 and founded what is still one of the largest soap businesses, formerly called Lever Brothers and now called Unilever. These soap businesses were among the first to employ large-scale advertising campaigns. | 1 | Solid-state chemistry |
There are several researchers in nanochemistry that have been credited with the development of the field. Geoffrey A. Ozin, from the University of Toronto, is known as one of the "founding fathers of Nanochemistry" due to his four and a half decades of research on this subject. This research includes the study of matrix isolation laser Raman spectroscopy, naked metal clusters chemistry and photochemistry, nanoporous materials, hybrid nanomaterials, mesoscopic materials, and ultrathin inorganic nanowires.
Another chemist who is also viewed as one of the nanochemistry's pioneers is Charles M. Lieber at Harvard University. He is known for his contributions to the development of nano-scale technologies, particularly in the field of biology and medicine. The technologies include nanowires, a new class of quasi-one-dimensional materials that have demonstrated superior electrical, optical, mechanical, and thermal properties and can be used potentially as biological sensors. Research under Lieber has delved into the use of nanowires mapping brain activity.
Shimon Weiss, a professor at the University of California, Los Angeles, is known for his research of fluorescent semiconductor nanocrystals, a subclass of quantum dots, for biological labeling.
Paul Alivisatos, from the University of California, Berkeley, is also notable for his research on the fabrication and use of nanocrystals. This research has the potential to develop insight into the mechanisms of small-scale particles such as the process of nucleation, cation exchange, and branching. A notable application of these crystals is the development of quantum dots.
Peidong Yang, another researcher from the University of California, Berkeley, is also notable for his contributions to the development of 1-dimensional nanostructures. The Yang group has active research projects in the areas of nanowire photonics, nanowire-based solar cells, nanowires for solar to fuel conversion, nanowire thermoelectrics, nanowire-cell interface, nanocrystal catalysis, nanotube nanofluidics, and plasmonics. | 0 | Colloidal Chemistry |