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Recent advancements in SPR technology have given rise to novel formats increasing the scope and applicability of SPR sensing. Fiber optic SPR involves the integration of SPR sensors onto the ends of optical fibers, enabling the direct coupling of light with the surface plasmons as the analytes are passed through a hollow SPR core. This format offers enhanced sensitivity and allows for the development of compact sensing devices, making it particularly valuable for applications requiring remote sensing in the field. It also offers an increased surface area for analytes to bind to the inner lining of the fiber optic. | 0 | Theoretical and Fundamental Chemistry |
Guliyev was elected as a member of the Supreme Soviet of Azerbaijan SSR in VIII and IX convocations. He received two Stalin Prizes and an Azerbaijan SSR State Prize. He was awarded two Orders of the Red Banner of Labour, three Orders of the Badge of Honour and medals, six honorary diplomas of the Supreme Soviet of Azerbaijan SSR, two golden and four silver medals of VDNKh of USSR. The Institute of Chemistry of Additives of AS of Azerbaijan was named after him. | 0 | Theoretical and Fundamental Chemistry |
*Coriolis effect
*Circulation
*Kelvin's circulation theorem
*Vorticity equation
*Thermal wind
*Geostrophic current
*Geostrophic wind
*Taylor–Proudman theorem
*Hydrostatic equilibrium
*Ekman spiral
*Ekman layer | 1 | Applied and Interdisciplinary Chemistry |
The API gravity of a crude oil is a measurement of purity - i.e., amount of impurities, such as sulphur, nitrogen, or oxygen. Impurities increase the density of the crude. | 0 | Theoretical and Fundamental Chemistry |
In the sulfite process for paper-making, lignin is removed from the lignocellulose by treating wood chips with solutions of sulfite and bisulfite ions. These reagents cleave the bonds between the cellulose and lignin components and especially within the lignin itself. The lignin is converted to lignosulfonates, useful ionomers, which are soluble and can be separated from the cellulose fibers. | 0 | Theoretical and Fundamental Chemistry |
Jean Beguin (1550–1620) was an iatrochemist noted for his 1610 Tyrocinium Chymicum (Begin Chemistry) ([http://nbn-resolving.de/urn:nbn:de:hbz:061:2-27843 Digital edition]), which many consider to be one of the first chemistry textbooks. In the 1615 edition of his textbook, Beguin made the first-ever chemical equation or rudimentary reaction diagrams, showing the results of reactions in which there are two or more reagents. Modern rendering of this famous diagram, detailing the reaction of corrosive sublimate (HgCl) with sulfide of antimony (SbS), is shown below: | 1 | Applied and Interdisciplinary Chemistry |
Gene knockout by mutation is commonly carried out in bacteria. An early instance of the use of this technique in Escherichia coli was published in 1989 by Hamilton, et al. In this experiment, two sequential recombinations were used to delete the gene. This work established the feasibility of removing or replacing a functional gene in bacteria. That method has since been developed for other organisms, particularly research animals, like mice. Knockout mice are commonly used to study genes with human equivalents that may have significance for disease. An example of a study using knockout mice is an investigation of the roles of Xirp proteins in Sudden Unexplained Nocturnal Death Syndrome (SUNDS) and Brugada Syndrome in the Chinese Han Population. | 1 | Applied and Interdisciplinary Chemistry |
The goal of the TB Structural Genomics Consortium is to determine the structures of potential drug targets in Mycobacterium tuberculosis, the bacterium that causes tuberculosis. The development of novel drug therapies against tuberculosis are particularly important given the growing problem of multi-drug-resistant tuberculosis.
The fully sequenced genome of M. tuberculosis has allowed scientists to clone many of these protein targets into expression vectors for purification and structure determination by X-ray crystallography. Studies have identified a number of target proteins for structure determination, including extracellular proteins that may be involved in pathogenesis, iron-regulatory proteins, current drug targets, and proteins predicted to have novel folds. So far, structures have been determined for 708 of the proteins encoded by M. tuberculosis. | 1 | Applied and Interdisciplinary Chemistry |
On the basis of interfacial energies, the profile of a surface droplet or a liquid bridge between two surfaces can be described by the Young–Laplace equation. This equation is applicable for three-dimensional axisymmetric conditions and is highly non-linear. This is due to the mean curvature term which includes products of first- and second-order derivatives of the drop shape function :
Solving this elliptic partial differential equation that governs the shape of a three-dimensional drop, in conjunction with appropriate boundary conditions, is complicated, and an alternate energy minimization approach to this is generally adopted. The shapes of three-dimensional sessile and pendant drops have been successfully predicted using this energy minimisation method. | 0 | Theoretical and Fundamental Chemistry |
After postdoctoral studies with Orville L. Chapman at the University of California, Los Angeles (UCLA) and habilitation at the Max Planck Institute for Medical Research in Heidelberg, he became Full Professor of Organic and Bioorganic Chemistry at UCLA in 1989. In 1992 he was appointed Professor of Organic Chemistry at ETH Zurich. He retired on 31 July 2017, and remained a research-active professor at ETH Zurich. On 16 March 2019, the German Chemical Society (Gesellschaft Deutscher Chemiker, GDCh) bestowed him with their highest recognition, Honorary Membership.
Diederich died on 23 September 2020 after a battle with cancer.
His research interests cover a wide range of topics:
* Molecular recognition in chemistry and biology.
* Modern medicinal chemistry: molecular recognition studies with biological receptors and X-ray structure-based design of nonpeptidic enzyme inhibitors. Examples of targets: plasmepsin II, IspE and IspF in the non-mevalonate pathway of isoprenoid biosynthesis (malaria); t-RNA guanine transglycosylase (shigellosis); trypanothione reductase (African sleeping sickness).
* Supramolecular nanosystems and nano-patterned surfaces.
* Advanced materials based on carbon-rich acetylenic molecular architecture: new organic super-acceptors and their inter- and intramolecular charge-transfer complexes, opto-electronic materials for molecular electronic circuitry, chiral macrocyclic and acyclic alleno-acetylenes, amplification of chirality and its transfer from the molecular to the macroscopic scale. | 0 | Theoretical and Fundamental Chemistry |
Glomalin is a hypothetical glycoprotein produced abundantly on hyphae and spores of arbuscular mycorrhizal (AM) fungi in soil and in roots. Glomalin was proposed in 1996 by Sara F. Wright, a scientist at the USDA Agricultural Research Service, but it was not isolated and described yet. The name comes from Glomerales, an order of fungi. Most AM fungi are of the division Glomeromycota. An elusive substance, it is mostly assumed to have a glue-like effect on soil, but it has not been isolated yet. | 0 | Theoretical and Fundamental Chemistry |
Generally the conductivity of a solution increases with temperature, as the mobility of the ions increases. For comparison purposes reference values are reported at an agreed temperature, usually 298 K (≈ 25 °C or 77 °F), although occasionally 20 °C (68 °F) is used. So called compensated measurements are made at a convenient temperature but the value reported is a calculated value of the expected value of conductivity of the solution, as if it had been measured at the reference temperature. Basic compensation is normally done by assuming a linear increase of conductivity versus temperature of typically 2% per kelvin. This value is broadly applicable for most salts at room temperature. Determination of the precise temperature coefficient for a specific solution is simple and instruments are typically capable of applying the derived coefficient (i.e. other than 2%).
Measurements of conductivity versus temperature can be used to determine the activation energy , using the Arrhenius equation:
where is the exponential prefactor, the gas constant, and the absolute temperature in Kelvin. | 0 | Theoretical and Fundamental Chemistry |
The precise function of the central domain has not been fully elucidated, but it is thought to be important in aiding catalysis. | 1 | Applied and Interdisciplinary Chemistry |
The effect of the interfacial layer is clearly seen in the interactions between nanoparticles. These interactions can be modelled using the DLVO theory. Classically this theory states that the potential of a particle is the sum of the electrostatic and van der Waals interaction. This is theory has proven to be very accurate for almost all Colloidal particles, but cannot describe all the interactions measured for nanoparticles. Therefore this theory has been extended with the so called non-DLVO terms. In this extension the hydration force, hydrofobic force, steric force and bridging force are also considered, resulting in a total potential as follows:
These last terms are mostly determined by the interfacial layer as this is the outermost part of the particle, thereby determining the surface interactions. For example, the bridging term only plays a role when the molecules in the interfacial layer tend to polymerize.
In the case of nanoparticles made of a crystal, quantum mechanical interactions would be expected, but due to the interfacial layer the cores cannot get close enough to each other, and therefore these interactions are neglectable.
An illustrative limit-case are non-charged semiconducting quantum dots (QD) in an ideal fluid. Due to the ideal fluid there is no difference between the QD–QD interaction and the QD–fluid interaction. For only the VDW interaction is of importance in the interaction between the interfacial layers, which are made of the superfluid, and other interfacial layers or the solvent. This means there is no attraction between the particles, so they can be accurately described using the Hard Sphere model. | 0 | Theoretical and Fundamental Chemistry |
* Narrow-range ethoxylate
* Octaethylene glycol monododecyl ether
* Pentaethylene glycol monododecyl ether | 0 | Theoretical and Fundamental Chemistry |
An important microstructural feature of a polymer is its architecture and shape, which relates to the way branch points lead to a deviation from a simple linear chain. A branched polymer molecule is composed of a main chain with one or more substituent side chains or branches. Types of branched polymers include star polymers, comb polymers, polymer brushes, dendronized polymers, ladder polymers, and dendrimers. There exist also two-dimensional polymers (2DP) which are composed of topologically planar repeat units. A polymer's architecture affects many of its physical properties including solution viscosity, melt viscosity, solubility in various solvents, glass-transition temperature and the size of individual polymer coils in solution. A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, for example living polymerization. | 0 | Theoretical and Fundamental Chemistry |
The binding energy of helium is the energy source of the Sun and of most stars. The sun is composed of 74 percent hydrogen (measured by mass), an element having a nucleus consisting of a single proton. Energy is released in the Sun when 4 protons combine into a helium nucleus, a process in which two of them are also converted to neutrons.
The conversion of protons to neutrons is the result of another nuclear force, known as the weak (nuclear) force. The weak force, like the strong force, has a short range, but is much weaker than the strong force. The weak force tries to make the number of neutrons and protons into the most energetically stable configuration. For nuclei containing less than 40 particles, these numbers are usually about equal. Protons and neutrons are closely related and are collectively known as nucleons. As the number of particles increases toward a maximum of about 209, the number of neutrons to maintain stability begins to outstrip the number of protons, until the ratio of neutrons to protons is about three to two.
The protons of hydrogen combine to helium only if they have enough velocity to overcome each others mutual repulsion sufficiently to get within range of the strong nuclear attraction. This means that fusion only occurs within a very hot gas. Hydrogen hot enough for combining to helium requires an enormous pressure to keep it confined, but suitable conditions exist in the central regions of the Sun, where such pressure is provided by the enormous weight of the layers above the core, pressed inwards by the Suns strong gravity. The process of combining protons to form helium is an example of nuclear fusion.
Producing helium from normal hydrogen would be practically impossible on earth because of the difficulty in creating deuterium. Research is being undertaken on developing a process using deuterium and tritium. The Earths oceans contain a large amount of deuterium that could be used and tritium can be made in the reactor itself from lithium, and furthermore the helium product does not harm the environment, so some consider nuclear fusion a good alternative to supply our energy needs. Experiments to carry out this form of fusion have so far only partially succeeded. Sufficiently hot deuterium and tritium must be confined. One technique is to use very strong magnetic fields, because charged particles (like those trapped in the Earths radiation belt) are guided by magnetic field lines. | 0 | Theoretical and Fundamental Chemistry |
Martin Schoell attended University of Munich for his undergraduate career in 1961 and in 1964 attended the University Clausthal, Germany for graduate school where he obtained a PhD in geochemistry. While at the University Clausthal, in 1966 Schoell delivered his Diplomarbeit (Masters Thesis) on the geochemistry of strontium in a deposit of barite. Later, in 1981, Schoell continued his education in Germany by obtaining his Habilitation (the highest possible academic degree offered in German academia). Schoell was mentored by Wolfgang Stahl, who inspired Schoells interest in hydrogen isotope geochemistry with respect to natural gas research. | 0 | Theoretical and Fundamental Chemistry |
Plastocyanin is a copper-containing protein that mediates electron-transfer. It is found in a variety of plants, where it participates in photosynthesis. The protein is a prototype of the blue copper proteins, a family of intensely blue-colored metalloproteins. Specifically, it falls into the group of small type I blue copper proteins called "cupredoxins". | 0 | Theoretical and Fundamental Chemistry |
Quantitative RT-PCR assay is considered to be the gold standard for measuring the number of copies of specific cDNA targets in a sample but it is poorly standardized. As a result, while there are numerous publications utilizing the technique, many provide inadequate experimental detail and use unsuitable data analysis to draw inappropriate conclusions. Due to the inherent variability in the quality of any quantitative PCR data, not only do reviewers have a difficult time evaluating these manuscripts, but the studies also become impossible to replicate. Recognizing the need for the standardization of the reporting of experimental conditions, the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE, pronounced mykee) guidelines have been published by an international consortium of academic scientists. The MIQE guidelines describe the minimum information necessary for evaluating quantitative PCR experiments that should be required for publication for encouraging better experimental practice and ensuring the relevance, accuracy, correct interpretation, and repeatability of quantitative PCR data.
Besides reporting guidelines, the MIQE stresses the need to standardize the nomenclature associated with quantitative PCR to avoid confusion; for example, the abbreviation qPCR should be used for quantitative real-time PCR, while RT-qPCR should be used for reverse transcription-qPCR, and genes used for normalisation should be referred to as reference genes instead of housekeeping genes. It also proposes that commercially derived terms like TaqMan probes should not be used, but instead referred to as hydrolysis probes. Additionally, it is proposed that quantification cycle (Cq) be used to describe the PCR cycle used for quantification instead of threshold cycle (Ct), crossing point (Cp), and takeoff point (TOP), which refer to the same value but were coined by different manufacturers of real-time instruments.
The guideline consists of the following elements: 1) experimental design, 2) sample, 3) nucleic acid extraction, 4) reverse transcription, 5) qPCR target information, 6) oligonucleotides, 7) protocol, 8) validation, and 9) data analysis. Specific items within each element carry a label of either E (essential) or D (desirable). Those labelled E are considered critical and indispensable while those labelled D are considered peripheral yet important for best-practices. | 1 | Applied and Interdisciplinary Chemistry |
The bicinchoninic acid assay (BCA assay), also known as the Smith assay, after its inventor, Paul K. Smith at the Pierce Chemical Company, now part of Thermo Fisher Scientific, is a biochemical assay for determining the total concentration of protein in a solution (0.5 μg/mL to 1.5 mg/mL), similar to Lowry protein assay, Bradford protein assay or biuret reagent. The total protein concentration is exhibited by a color change of the sample solution from blue to purple in proportion to protein concentration, which can then be measured using colorimetric techniques. The BCA assay was patented by Pierce Chemical Company in 1989 & the patent expired in 2006. | 1 | Applied and Interdisciplinary Chemistry |
Lichens grow in a wide range of shapes and forms; this external appearance is known as their morphology. The shape of a lichen is usually determined by the organization of the fungal filaments. The nonreproductive tissues, or vegetative body parts, are called the thallus. Lichens are grouped by thallus type, since the thallus is usually the most visually prominent part of the lichen. Thallus growth forms typically correspond to a few basic internal structure types. Common names for lichens often come from a growth form or color that is typical of a lichen genus.
Common groupings of lichen thallus growth forms are:
# fruticose – growing like a tuft or multiple-branched leafless mini-shrub, upright or hanging down, 3-dimensional branches with nearly round cross section (terete) or flattened
# foliose – growing in 2-dimensional, flat, leaf-like lobes
# crustose – crust-like, adhering tightly to a surface (substrate) like a thick coat of paint
# squamulose – formed of small leaf-like scales crustose below but free at the tips
# leprose – powdery
# gelatinous – jelly-like
# filamentous – stringy or like matted hair
# byssoid – wispy, like teased wool
# structureless
There are variations in growth types in a single lichen species, grey areas between the growth type descriptions, and overlapping between growth types, so some authors might describe lichens using different growth type descriptions.
When a crustose lichen gets old, the center may start to crack up like old-dried paint, old-broken asphalt paving, or like the polygonal "islands" of cracked-up mud in a dried lakebed. This is called being rimose or areolate, and the "island" pieces separated by the cracks are called areolas. The areolas appear separated, but are (or were) connected by an underlying prothallus or hypothallus. When a crustose lichen grows from a center and appears to radiate out, it is called crustose placodioid. When the edges of the areolas lift up from the substrate, it is called squamulose.
These growth form groups are not precisely defined. Foliose lichens may sometimes branch and appear to be fruticose. Fruticose lichens may have flattened branching parts and appear leafy. Squamulose lichens may appear where the edges lift up. Gelatinous lichens may appear leafy when dry.
The thallus is not always the part of the lichen that is most visually noticeable. Some lichens can grow inside solid rock between the grains (endolithic lichens), with only the sexual fruiting part visible growing outside the rock. These may be dramatic in color or appearance. Forms of these sexual parts are not in the above growth form categories. The most visually noticeable reproductive parts are often circular, raised, plate-like or disc-like outgrowths, with crinkly edges, and are described in sections below. | 1 | Applied and Interdisciplinary Chemistry |
Born to Instructor Commodore M. G. S. Perera (1 June 1917 – 10 August 1999), Founder and the First Commandant Naval & Maritime Academy Trincomalee, the First and Foremost Director of Naval Training, Royal Ceylon Navy, and former Senior Staff Captain / Nautical Instructor (Training of Deck Officer Cadets) Ceylon Shipping Corporation (1977–1983) and Maureen Johanna Perera (19 February 1924 - 22 October 2019), he has one sister, Deepthi C. J. Guneratne BSc (Botany), MSc (Soil Chemistry). | 0 | Theoretical and Fundamental Chemistry |
Cycling probe technology makes use of a chimeric nucleic acid probe to detect the presence of a particular DNA sequence. The chimeric probe consists of an RNA segment sandwiched between two DNA segments. The RNA segment contains 4 contiguous purine nucleotides. The probes should be less than 30 nucleotides in length and designed to minimize intra-probe and inter-probe interactions. | 1 | Applied and Interdisciplinary Chemistry |
The Catskill-Delaware Water Ultraviolet Disinfection Facility is a ultraviolet (UV) water disinfection plant built in Westchester County, New York to disinfect water for the New York City water supply system. The compound is the largest ultraviolet germicidal irradiation plant in the world.
The UV facility treats water delivered by two of the citys aqueduct systems, the Catskill Aqueduct and the Delaware Aqueduct, via the Kensico Reservoir. (The citys third supply system, the New Croton Aqueduct, has a separate treatment plant.)
The plant has 56 energy-efficient UV reactors, and cost the city $1.6 billion. Mayor Michael Bloomberg created research groups between 2004-2006 to decide the best and most cost-effective ways to modernize the citys water filtration process, as a secondary stage following the existing chlorination and fluoridation facilities. The UV technology effectively controls microorganisms such as giardia and cryptosporidium' which are resistant to chlorine treatment. The city staff determined that the cheapest alternatives to a UV system would cost over $3 billion. In response to this finding, Bloomberg decided to set up a public competitive contract auction. Ontario based Trojan Technologies won the contract.
The facility treats of water per day. The new facility was originally set to be in operation by the end of 2012. The facility opened on October 8, 2013. | 0 | Theoretical and Fundamental Chemistry |
In chemistry, the Chinese lantern structure is a coordination complex where two metal atoms are bridged by four bidentate ligands. This structure type is also known as a paddlewheel complex. Examples include chromium(II) acetate, molybdenum(II) acetate, and rhodium(II) acetate, copper(II) acetate dihydrate. The name is derived from the resemblance between the structure and a Chinese paper lantern. Often additional ligands are bound to the metal centers along the M---M vector. The degree of metal-metal bonding varies according to the d-electron configuration. | 0 | Theoretical and Fundamental Chemistry |
The (nondimensional) shape, r(z) of an axisymmetric surface can be found by substituting general expressions for principal curvatures to give the hydrostatic Young–Laplace equations: | 1 | Applied and Interdisciplinary Chemistry |
Aerobic glycolysis in cancer cells, also known as the “Warburg effect”, is driven by hyperactivity of lactate dehydrogenase-A (LDHA). Mollapour’s team has identified the human tumor suppressor folliculin (FLCN) as a binding partner and uncompetitive inhibitor of LDHA. Their work has provided a new paradigm for the regulation of glycolysis. Cancer cells that experience the Warburg effect show FLCN dissociation from LDHA. Mollapour’s lab has shown that treatment of these cancer cells with a decapeptide derived from the FLCN loop region caused cell death, therefore providing a new avenue for targeted therapy in these cancers. | 1 | Applied and Interdisciplinary Chemistry |
On 28 January 2021, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Vazkepa, intended to reduce the risk of cardiovascular events in people at high cardiovascular risk. The applicant for this medicinal product is Amarin Pharmaceuticals Ireland Limited. It was approved for medical use in the European Union in March 2021. | 1 | Applied and Interdisciplinary Chemistry |
The area is rich in fossil fuels. Oil wells were being dug in the region as early as the 10th century to reach oil "for use in everyday life, both for medicinal purposes and for heating and lighting in homes". By the 16th century, Europeans were aware of the rich oil and gas deposits locally. English traders Thomas Bannister and Jeffrey Duckett described the area around Baku as "a strange thing to behold, for there issueth out of the ground a marvelous quantity of oil, which serveth all the country to burn in their houses. This oil is black and is called nefte. There is also by the town of Baku, another kind of oil which is white and very precious [i.e., petroleum]."
Today, oil and gas platforms abound along the edges of the sea. | 1 | Applied and Interdisciplinary Chemistry |
El-Shall was the first to apply the Resonant Enhanced Multiphoton Ionization (REMPI) technique to selectively generate molecular ions within supersaturated host vapors and study the phenomena of ion-induced nucleation on well-defined ions. He also focused his study on the formation mechanisms of gold–zinc oxide hexagonal nanopyramids through heterogeneous nucleation using microwave synthesis. In 2018, he demonstrated nucleation and growth process of gold nanoparticles initiated by nanosecond and femtosecond laser irradiation of aqueous solutions of [AuCl4]−. | 0 | Theoretical and Fundamental Chemistry |
An essential trace element is a dietary element, a mineral that is only needed in minute quantities for the proper growth, development, and physiology of the organism. The essential trace elements are those that are required to perform vital metabolic activities in organisms. Essential trace elements in human nutrition, and other animals include iron (Fe) (hemoglobin), copper (Cu) (respiratory pigments), cobalt (Co) (Vitamin B12), iodine (I), manganese (Mn), chlorine (Cl), molybdenum (Mo), selenium (Se) and zinc (Zn) (enzymes). Although they are essential, they become toxic at high concentrations. | 0 | Theoretical and Fundamental Chemistry |
Bacteria become highly tolerant to antibiotics when nutrients are limited. Starvation contributes to antibiotic tolerance during infection, as nutrients become limited when they are sequestered by host defenses and consumed by proliferating bacteria. One of the most important causes of starvation induced tolerance in vivo is biofilm growth, which occurs in many chronic infections. Starvation in biofilms is due to nutrient consumption by cells located on the periphery of biofilm clusters and by reduced diffusion of substrates through the biofilm. Biofilm bacteria shows extreme tolerance to almost all antibiotic classes, and supplying limiting substrates can restore sensitivity. | 1 | Applied and Interdisciplinary Chemistry |
Due to their high surface roughness, conventional white nitrocellulose films scatter and reflect large amounts of excitation and emission light during the fluorescence detection in the microarray scanner. In addition, nitrocellulose exhibits a natural autofluorescence at the detection wavelengths commonly used. Both these factors lead to a high background fluorescent signal from these membrane slides. To overcome this problem, a new process has been developed to generate black membranes that absorb the scattered light, significantly reducing the background auto-fluorescence and thus offering a very low and homogenous auto-fluorescence to achieve a significantly improved dynamic range. These slides are commercially available through Schott AG. Nevertheless, conventional white nitrocellulose films continue to be the dominant surface for many protein microarray applications because the claims above have not proved relevant to end user requirements. Regardless, nitrocellulose slide manufacturers like Grace Bio-Labs continue to develop new nitrocellulose surfaces to further optimize their use in protein microarrays.
A method for protein quantitation on nitrocellulose coated glass slides uses near-IR fluorescent detection with quantum dots. Traditional porous nitrocellulose signal to noise is limited by auto-fluorescence of the nitrocellulose at the respective required wavelengths of excitation and emission for standard organic fluorescent detection probes. Near IR detection probes are excited and read at emission wavelengths outside the range of nitrocellulose fluorescence. | 1 | Applied and Interdisciplinary Chemistry |
Selective deprotection of silyl groups is possible in many instances. For example, in the synthesis of taxol:
Silyl ethers are mainly differentiated on the basis of sterics or electronics. In general, acidic deprotections deprotect less hindered silyl groups faster, with the steric bulk on silicon being more significant than the steric bulk on oxygen. Fluoride-based deprotections deprotect electron-poor silyl groups faster than electron-rich silyl groups. There is some evidence that some silyl deprotections proceed via hypervalent silicon species.
The selective deprotection of silyl ethers has been extensively reviewed. Although selective deprotections have been achieved under many different conditions, some procedures, outlined below, are more reliable. A selective deprotection will likely be successful if there is a substantial difference in sterics (e.g., primary TBS vs. secondary TBS or primary TES vs primary TBS) or electronics (e.g. primary TBDPS vs. primary TBS). Unfortunately, some optimization is inevitably required and it is often necessary to run deprotections partway and recycle material.
;Some common acidic conditions:
* 100 mol% 10-CSA (camphorsulfonic acid) in MeOH, room temperature; a "blast" of acid, deprotects primary TBS groups within ten minutes.
* 10 mol% 10-CSA, 1:1 MeOH:DCM, −20 or 0 °C; deprotects a primary TBS group within two hours at 0; if CSA is replaced by PPTS, the rate is approximately ten times slower; with p-TsOH, approximately ten times faster; solvent mixture is crucial.
* 4:1:1 v/v/v AcOH:THF:water, room temp.; this is very slow, but can be very selective.
;Some common basic conditions:
* HF-pyridine, 10:1 THF:pyridine, 0 °C; an excellent deprotection; removes primary TBS groups within eight hours; reactions using HF must be run in plastic containers.
* TBAF, THF or 1:1 TBAF/AcOH, THF; TBDPS and TBS groups can be deprotected in the presence of one another under different conditions. | 0 | Theoretical and Fundamental Chemistry |
A variety of different instruments can be used to perform position-specific isotope analysis, and each have distinct advantages and drawbacks. Many of them require comparison the sample of interest to a standard of known isotopic composition; fractionation within the instrument and variation of instrumental conditions over time can affect accuracy of individual measurements if not standardized. | 0 | Theoretical and Fundamental Chemistry |
Lorentz force velocimetry (LFV) is a noncontact electromagnetic flow measurement technique. LFV is particularly suited for the measurement of velocities in liquid metals like steel or aluminium and is currently under development for metallurgical applications. The measurement of flow velocities in hot and aggressive liquids such as liquid aluminium and molten glass constitutes one of the grand challenges of industrial fluid mechanics. Apart from liquids, LFV can also be used to measure the velocity of solid materials as well as for detection of micro-defects in their structures.
A Lorentz force velocimetry system is called Lorentz force flowmeter (LFF). A LFF measures the integrated or bulk Lorentz force resulting from the interaction between a liquid metal in motion and an applied magnetic field. In this case the characteristic length of the magnetic field is of the same order of magnitude as the dimensions of the channel. It must be addressed that in the case where localized magnetic fields are used, it is possible to perform local velocity measurements and thus the term Lorentz force velocimeter is used. | 1 | Applied and Interdisciplinary Chemistry |
There are three distinct groups of Complex III inhibitors.
* Antimycin A binds to the Q site and inhibits the transfer of electrons in Complex III from heme b to oxidized Q (Qi site inhibitor).
* Myxothiazol and stigmatellin binds to the Q site and inhibits the transfer of electrons from reduced QH to the Rieske Iron sulfur protein. Myxothiazol and stigmatellin bind to distinct but overlapping pockets within the Q site.
** Myxothiazol binds nearer to cytochrome bL (hence termed a "proximal" inhibitor).
** Stigmatellin binds farther from heme bL and nearer the Rieske Iron sulfur protein, with which it strongly interacts.
Some have been commercialized as fungicides (the strobilurin derivatives, best known of which is azoxystrobin; QoI inhibitors) and as anti-malaria agents (atovaquone).
Also propylhexedrine inhibits cytochrome c reductase. | 1 | Applied and Interdisciplinary Chemistry |
ABCC11 is a gene encoding an apical ATP-driven efflux transporter that has been found to transport a variety of lipophilic anions including cyclic nucleotides, estradiol glucuronide, steroid sulfates such as DHEA-S, and monoanionic bile acids. It is expressed and localized in apocrine glands, including in the axilla, the ceruminous glands in the auditory canal, and in the mammary gland. A single-nucleotide polymorphism (SNP) 538G→A in ABCC11 that leads to a G180R substitution in the encoded protein has been found to result in loss-of-function via affecting N-linked glycosylation and in turn causing proteasomal degradation of the protein. This polymorphism has been found to be responsible for the dry and white earwax phenotype, and is considered to be unique as it has been described as the only human SNP that has been found to determine a visible genetic trait. In addition to earwax phenotype, the ABCC11 genotype has been found to be associated with colostrum secretion from the breasts as well as normal axillary odor and osmidrosis (excessive axillary malodor).
A functional ABCC11 protein has been found to be essential for the presence of the characteristic strong axillary odor, with the 538G→A SNP leading to a loss of secretion of axillary malodorous precursors and a nearly complete loss of axillary odor in those who are homozygous for the polymorphism. Specifically, the secretion of the amino-acid conjugates 3M2H-Gln, HMHA-Gln, and Cys-Gly-(S) 3M3SH, which are precursors of key axillary malodorous compounds including the unsaturated or hydroxylated branched-chain fatty acids 3M2H and HMHA and the sulfanylalkanol 3M3SH, has been found to be abolished in homozygotic carriers of the SNP, and the odoriferous androstane steroids androstenone and androstenol and their precursors DHEA and DHEA-S have been found to be significantly reduced as well. Patients with axillary osmidrosis (538G/G or 538G/A genotype) were found to have significantly more numerous and relatively large axillary apocrine glands compared to controls with the A/A genotype. | 1 | Applied and Interdisciplinary Chemistry |
Gene knock-in originated as a slight modification of the original knockout technique developed by Martin Evans, Oliver Smithies, and Mario Capecchi. Traditionally, knock-in techniques have relied on homologous recombination to drive targeted gene replacement, although other methods using a transposon-mediated system to insert the target gene have been developed. The use of loxP flanking sites that become excised upon expression of Cre recombinase with gene vectors is an example of this. Embryonic stem cells with the modification of interest are then implanted into a viable blastocyst, which will grow into a mature chimeric mouse with some cells having the original blastocyst cell genetic information and other cells having the modifications introduced to the embryonic stem cells. Subsequent offspring of the chimeric mouse will then have the gene knock-in.
Gene knock-in has allowed, for the first time, hypothesis-driven studies on gene modifications and resultant phenotypes. Mutations in the human p53 gene, for example, can be induced by exposure to benzo(a)pyrene (BaP) and the mutated copy of the p53 gene can be inserted into mouse genomes. Lung tumors observed in the knock-in mice offer support for the hypothesis of BaP’s carcinogenicity. More recent developments in knock-in technique have allowed for pigs to have a gene for green fluorescent protein inserted with a CRISPR/Cas9 system, which allows for much more accurate and successful gene insertions. The speed of CRISPR/Cas9-mediated gene knock-in also allows for biallelic modifications to some genes to be generated and the phenotype in mice observed in a single generation, an unprecedented timeframe. | 1 | Applied and Interdisciplinary Chemistry |
Organic reactions can be categorized based on the type of functional group involved in the reaction as a reactant and the functional group that is formed as a result of this reaction. For example, in the Fries rearrangement the reactant is an ester and the reaction product an alcohol.
An overview of functional groups with their preparation and reactivity is presented below: | 0 | Theoretical and Fundamental Chemistry |
In 1971, the natural-gas-fired U-25 plant was completed near Moscow, with a designed capacity of 25 megawatts. By 1974 it delivered 6 megawatts of power. By 1994, Russia had developed and operated the coal-operated facility U-25, at the High-Temperature Institute of the Russian Academy of Science in Moscow. U-25s bottoming plant was actually operated under contract with the Moscow utility, and fed power into Moscows grid. There was substantial interest in Russia in developing a coal-powered disc generator. In 1986 the first industrial power plant with MHD generator was built, but in 1989 the project was cancelled before MHD launch and this power plant later joined to Ryazan Power Station as a 7th unit with ordinary construction. | 1 | Applied and Interdisciplinary Chemistry |
The fundamental thesis Jung is advancing about the relationship between Alchemy and Psychology is that for pre-scientific humans there is not a sharp distinction between subject and object and thus this leads them to unconsciously project their own inner states onto external objects (especially objects that are mostly unknown to them), so a reflective analysis of alchemical symbols becomes revelatory about the unconscious psychic life of this time period. Prior to this rational segregation of experience the world was a totally different one, phenomenologically, as people did not distinguish between the qualities of the object they were perceiving and their own values, emotions, and beliefs. It is partly for this reason that the alchemists cannot say aloud exactly what the philosophers stone really is' and why there are so many different symbols for the work.
For the alchemist trying to understand matter and develop base metals into their purest form, gold, substances are grouped as being alike based on their perceived value. Jung documents as these alchemists collectively come to understand that they themselves must embody the change they hope to effect within their materials: for instance, if they hope to achieve the philosophers stone that can redeem base or vulgar metals, then the alchemist too must become a redeemer figure. It became apparent to the alchemists that they were trying to redeem nature as Christ had redeemed man, hence the identification of the Lapis Philosophorum with Christ the Redeemer. The Opus (work) of alchemy, viewed through this interpretation, becomes a symbolic account of the fundamental process the human psyche undergoes as it re-orients its value system and creates meaning out of chaos. The opus beginning with the nigredo (blackening, akin to depression or nihilistic loss of value) in order to descend back into the manipulable prima materia' and proceeding through a process of spiritual purification that must unite seemingly irreconcilable opposites (the coniunctio) to achieve new levels of consciousness. | 1 | Applied and Interdisciplinary Chemistry |
Non-stop decay (NSD) is a cellular pathway that identifies and degrades aberrant mRNA transcripts that do not contain a proper stop codon. Stop codons are signals in messenger RNA that signal for synthesis of proteins to end. Aberrant transcripts are identified during translation when the ribosome translates into the poly A tail at the 3' end of mRNA. A non-stop transcript can occur when point mutations damage the normal stop codon. Moreover, some transcriptional events are more likely to preserve gene expression on a lower scale in particular states.
The NSD pathway discharges ribosomes that have stalled at the 3' end of mRNA and directs the mRNA to the exosome complex in eukaryotes or RNase R in bacteria. Once directed to their appropriate sites, the transcripts are then degraded. The NSD mechanism requires the interaction of RNA exosome with the Ski complex, a multi-protein structure that includes the Ski2p helicase and (notably) Ski7p. The combination of these proteins and subsequent complex formation activates the degradation of aberrant mRNAs. Ski7p is thought to bind the ribosome stalled at the 3’ end of the mRNA poly(A) tail and recruit the exosome to degrade the aberrant mRNA. However in mammalian cells, Ski7p is not found, and even the presence of the NSD mechanism itself has remained relatively unclear. The short splicing isoform of HBS1L (HBS1LV3) was found to be the long-sought after human homologue of Ski7p, linking the exosome and SKI complexes. Recently, it has been reported that NSD also occurs in mammalian cells, albeit through a slightly different system. In mammals, due to the absence of Ski7, the GTPase Hbs1, as well as its binding partner Dom34, were identified as potential regulators of decay. Together, Hbs1/Dom34 are capable of binding to the 3’ end of an mis-regulated mRNA, facilitating the dissociation of malfunctioning or inactive ribosomes in order to restart the process of translation. In addition, once the Hbs1/Dom34 complex has dissociated and recycled a ribosome, it has also been shown to recruit the exosome/Ski complex. | 1 | Applied and Interdisciplinary Chemistry |
Ruthenium-iridium nanosized corals (RuIr-NC) are electrodes consisting of nanosized anisotropic ruthenium-iridium sheets for efficient electrolysis of water in acid discovered in the Kyoto University.
The RuIr-NC were discovered unintentionally at the Kyoto University, but then investigated and refined for the purpose of efficient electrolysis of water in acid and found to have very promising qualities in terms of performance and durability.
As of 2021 the researchers at Kyoto University report their RuIr-NC are composed of 94% ruthenium and 6% iridium with the exposed hexagonal atomic arrangement corresponding to a hexagonal closed-packed (HCP) crystalline lattice plane crystal structure. The nanosheets take the form of 3 nm thick sheets with a mean diameter of 57 ± 7 nm. The researchers found them suitable for use as both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrodes.
Their water splitting cell using RuIr-NC as both OER and HER electrodes is able to achieve 10 mA cm at 1.485 V for 120 h without noticeable degradation. They report that, of the electrodes they evaluated for water electrolysis in acid, the RuIr-NC shows the highest intrinsic activity and stability.
The RuIr-NC is obtained by adding a mixture of RuCl3·nH2O and H2IrCl6 aqueous solutions to triethylene glycol solution containing polyvinylpyrrolidone at 230 °C.
The research team at Kyoto University published their work in February 2021 and presented it at the Chemical Society of Japan 101. General Meeting in March 2021. | 0 | Theoretical and Fundamental Chemistry |
Praseodymium(III) oxalate is an inorganic compound, a salt of praseodymium metal and oxalic acid, with the chemical formula COPr. The compound forms light green crystals that are insoluble in water. It also forms crystalline hydrates. | 0 | Theoretical and Fundamental Chemistry |
Thermite () is a pyrotechnic composition of metal powder and metal oxide. When ignited by heat or chemical reaction, thermite undergoes an exothermic reduction-oxidation (redox) reaction. Most varieties are not explosive, but can create brief bursts of heat and high temperature in a small area. Its form of action is similar to that of other fuel-oxidizer mixtures, such as black powder.
Thermites have diverse compositions. Fuels include aluminium, magnesium, titanium, zinc, silicon, and boron. Aluminium is common because of its high boiling point and low cost. Oxidizers include bismuth(III) oxide, boron(III) oxide, silicon(IV) oxide, chromium(III) oxide, manganese(IV) oxide, iron(III) oxide, iron(II,III) oxide, copper(II) oxide, and lead(II,IV) oxide. In a thermochemical survey comprising twenty-five metals and thirty-two metal oxides, 288 out of 800 binary combinations were characterized by adiabatic temperatures greater than 2000 K. Combinations like these, which possess the thermodynamic potential to produce very high temperatures, are either already known to be reactive or are plausible thermitic systems.
The reaction, also called the Goldschmidt process, is used for thermite welding, often used to join railway tracks. Thermites have also been used in metal refining, disabling munitions, and in incendiary weapons. Some thermite-like mixtures are used as pyrotechnic initiators in fireworks. | 0 | Theoretical and Fundamental Chemistry |
To stop the corrosion from continuing the object just needs to be aired out to remove any moisture and allow the normal layer of protection to form. Washing and a wire brush will remove most of the corrosion. For complete removal, 10% acetic acid or a mixture of polishing chalk and 20–40% NaOH can be used. Both require a thorough water rinsing afterward and do not restore lustrous surface finish if one was previously present. | 1 | Applied and Interdisciplinary Chemistry |
Reactions in chemical processes are either unimolecular or bimolecular. The rate of a unimolecular reaction is an average over a vast ensemble of the rate coefficients for the microscopic events of collisional energy transfer and of reaction of a completely isolated molecule. Gilberts work in the field of unimolecular processes started with the development of theorems for this relationship. These theorems are elegant developments in matrix algebra, proving relations that had been previously known only for particular cases. His theorems also became the basis for numerical methods that he developed to perform the requisite calculations. For this purpose, he created a computer code, UNIMOL', which is widely used by researchers.
He developed, with Prof J Troe, easily used approximate solutions for the pressure dependence of the rate coefficient. He provided the first solutions for cases where angular momentum conservation needs to be incorporated. His methods are used by experimentalists to fit data and extrapolate to different pressure regimes, supplanting previous tools which were of dubious validity and accuracy. His coworkers and he obtained data on the collisional energy transfer process and used them to prove the conjecture that each collision involves only a small exchange of energy. He then developed the first rigorous means to calculate these quantities from basic theory, and the first physical model for the process. His work is widely used, both for basic understanding of the transition states and by atmospheric and combustion modellers. Predicting climate change and effects on the ozone layer rely critically on this modelling. | 0 | Theoretical and Fundamental Chemistry |
In meteorology, mixing ratio usually refers to the mass ratio of water , which is defined as the mass of water divided by the mass of dry air () in a given air parcel:
The unit is typically given in . The definition is similar to that of specific humidity. | 0 | Theoretical and Fundamental Chemistry |
In friction stir processing (FSP), a rotating tool is used with a pin and a shoulder to a single piece of material to make specific property enhancement, such as improving the materials toughness or flexibility, in a specific area in the micro-structure of the material via fine grain of a second material with properties that improve the first.(Ma) Friction between the tool and workpieces results in localized heating that softens and plasticizes the workpiece. A volume of processed material is produced by movement of materials from the front of the pin to the back of the pin. During this process, the material undergoes intense plastic deformation and this results in significant grain refinement. (Mishra) FSP changes physical properties without changing physical state which helps engineers create things such as “high-strain-rate superplasticity”. The grain refinement occurs on the base material improving properties of the first material, while mixing with the second material. This allows for a variety of materials to be altered to be changed for things that may require other difficult to acquire conditions. The processes branches off of friction stir welding (FSW) which uses the same process to weld two pieces of different materials together without heating, melting, or having to change the materials physical state. | 1 | Applied and Interdisciplinary Chemistry |
ASM International, formerly known as the American Society for Metals, is an association of materials-centric engineers and scientists.
As the charitable arm of ASM, the ASM Materials Education Foundation also operates ASM Materials Camp in the summers for high school students and teachers. These camps are intended to educate the public about the materials field, and encourage young people to pursue careers in materials science and engineering. | 1 | Applied and Interdisciplinary Chemistry |
The phenomenon of electroluminescence was discovered in 1907 using silicon carbide and the first commercial LEDs were based on SiC. Yellow LEDs made from 3C-SiC were manufactured in the Soviet Union in the 1970s and blue LEDs (6H-SiC) worldwide in the 1980s.
Carbide LED production soon stopped when a different material, gallium nitride, showed 10–100 times brighter emission. This difference in efficiency is due to the unfavorable indirect bandgap of SiC, whereas GaN has a direct bandgap which favors light emission. However, SiC is still one of the important LED components: It is a popular substrate for growing GaN devices, and it also serves as a heat spreader in high-power LEDs. | 1 | Applied and Interdisciplinary Chemistry |
A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph. P waves may be transmitted through gases, liquids, or solids. | 1 | Applied and Interdisciplinary Chemistry |
In order to avoid leakage at the packing or seal particularly when a liquid is dangerous, toxic, or noxious, diaphragm pumps are used for metering. Diaphragm pumps have a diaphragm through which repeated compression/decompression motion is transmitted. The liquid does not penetrate through the diaphragm, so the liquid inside the pump is sealed off from the outside. Such motion changes the volume of a chamber in the pump head so that liquid enters through an inlet check valve during decompression and exits through an outlet check valve during compression, in a manner similar to piston pumps. Diaphragm pumps can also be made which discharge at fairly high pressure. Diaphragm metering pumps are commonly hydraulically driven.
Peristaltic pumps use motor-driven rollers to roll along flexible tubing, compressing it to push forward a liquid inside. Although peristaltic pumps can be used to meter at lower pressures, the flexible tubing is limited in the level of pressure it can withstand. | 1 | Applied and Interdisciplinary Chemistry |
Ammonium metavanadate is the inorganic compound with the formula NHVO. It is a white salt, although samples are often yellow owing to impurities of VO. It is an important intermediate in the purification of vanadium. | 0 | Theoretical and Fundamental Chemistry |
Assemblies of solar cells are used to make solar modules that generate electrical power from sunlight, as distinguished from a "solar thermal module" or "solar hot water panel". A solar array generates solar power using solar energy. | 0 | Theoretical and Fundamental Chemistry |
The history of cosmetics spans at least 7,000 years and is present in almost every society on earth. Cosmetic body art is argued to have been the earliest form of a ritual in human culture. The evidence for this comes in the form of utilised red mineral pigments (red ochre) including crayons associated with the emergence of Homo sapiens in Africa. Cosmetics are mentioned in the Old Testament—2 Kings 9:30 where Jezebel painted her eyelids—approximately 840 BC—and the book of Esther describes various beauty treatments as well.
Cosmetics were also used in ancient Rome, although much of Roman literature suggests that it was frowned upon. It is known that some women in ancient Rome invented make up including lead-based formulas, to whiten the skin, and kohl to line the eyes. | 1 | Applied and Interdisciplinary Chemistry |
The kilogram per cubic metre (symbol: kg·m, or kg/m) is the unit of density in the International System of Units (SI). It is defined by dividing the SI unit of mass, the kilogram, by the SI unit of volume, the cubic metre. | 0 | Theoretical and Fundamental Chemistry |
Allophanic acid is the organic compound with the formula HNC(O)NHCOH. It is a carbamic acid, the carboxylated derivative of urea. Biuret can be viewed as the amide of allophanic acid. The compound can be prepared by treating urea with sodium bicarbonate:
:HNC(O)NH + NaHCO → HNC(O)NHCOH + NaOH
The anionicconjugate base, HNC(O)NHCO, is called allophanate. Salts of this anion have been characterized by X-ray crystallography. The allophanate anion is the substrate for the enzyme allophanate hydrolase.
Allophanate esters arise from the condensation of carbamates. | 0 | Theoretical and Fundamental Chemistry |
Studies indicate creatinine can be effective at killing bacteria of many species in both the Gram positive and Gram negative as well as diverse antibiotic resistant bacterial strains. Creatinine appears not to affect growth of fungi and yeast; this can be used to isolate slower growing fungi free from the normal bacterial populations found in most environmental samples. The mechanism by which creatinine kills bacteria is not presently known. A recent report also suggests that creatinine may have immunosuppressive properties. | 1 | Applied and Interdisciplinary Chemistry |
Following selection from DNA-encoded chemical libraries, the decoding strategy for the fast and efficient identification of the specific binding compounds is crucial for the further development of the DEL technology. So far, Sanger-sequencing-based decoding, microarray-based methodology and high-throughput sequencing techniques represented the main methodologies for the decoding of DNA-encoded library selections. | 1 | Applied and Interdisciplinary Chemistry |
Van de Flierdt is interested in the marine-terminating sector of the East Antarctic Ice Sheet during past warm periods. Her research looks to develop new geochemical and isotopic tracers in marine geochemistry, paleoceanography and paleoclimate, with particular focus on radiogenic isotopes. She is co-lead of the MAGIC Isotope group in the Department of Earth Sciences at Imperial College London. She is also a research at the Lamont–Doherty Earth Observatory at Columbia University.
She is part of the international Geotraces program. Part of the Geotraces program is to ensure results for trace elements and isotopes collected on different cruises by different laboratories can be compared in a meaningful way. Van de Flierdt is building a global database of neodymium in the oceans and researching the implications for paleoceanography research.
In 2012 she won a Leverhulme Trust grant to research deep sea corals. She was part of the Natural Environment Research Council project SWEET, Super-Warm Early Eocene Temperatures and climate. She has led several major NERC grants, totalling well over a £1,000,000 as principal investigator. Van de Flierdt is a member of the Royal Societys International Exchange Committee. She is an editor of Geochimica et Cosmochimica Acta. She has appeared on the podcast Forecast: Climate Conversations'. | 0 | Theoretical and Fundamental Chemistry |
A disaccharide (also called a double sugar or biose) is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lactose, and maltose.
Disaccharides are one of the four chemical groupings of carbohydrates (monosaccharides, disaccharides, oligosaccharides, and polysaccharides). The most common types of disaccharides—sucrose, lactose, and maltose—have 12 carbon atoms, with the general formula CHO. The differences in these disaccharides are due to atomic arrangements within the molecule.
The joining of monosaccharides into a double sugar happens by a condensation reaction, which involves the elimination of a water molecule from the functional groups only. Breaking apart a double sugar into its two monosaccharides is accomplished by hydrolysis with the help of a type of enzyme called a disaccharidase. As building the larger sugar ejects a water molecule, breaking it down consumes a water molecule. These reactions are vital in metabolism. Each disaccharide is broken down with the help of a corresponding disaccharidase (sucrase, lactase, and maltase). | 0 | Theoretical and Fundamental Chemistry |
, also known as Persian gum, is a shrub or tree from Persia historically famed for its balsam, which was used to create ancient and medieval paint and in traditional medicines. Although its identity was uncertain to Europeans after it fell from use in the medieval period, it has since been identified with a species of (Papilionaceae). | 1 | Applied and Interdisciplinary Chemistry |
The mechanism of PICUP require the tris(bipyridyl)Ru(II) complex, an electron acceptor, ammonium persulfate (APS), and reactive amino acid side chains. Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate, a tris(bipyridyl)Ru(II) complex, initially contains a Ru. Upon visible light irradiation and in the presence of ammonium persulfate (APS), Ru enters its excited state and is oxidized to Ru. Ru is now an extremely reactive oxidizer that only wants to accept one electron instead of the standard two. The reaction can proceed in the absence of an electron acceptor, but it will have a much lower efficiency, producing byproducts resulting from the excited Ru(Bpy) reacting with oxygen. As an effective single electron oxidizer, Ru will pick up a single electron from amino acids of the neighboring proteins, most commonly Tryptophan and Tyrosine. This produces a radical that is highly unstable on the amino acid side chains, which proceeds through reactions to reach a more stable state.
The unpaired single electron on the side chain reacts with another amino acid side chain of a polypeptide in the vicinity, resulting in a dimer with a covalent bond. With the regeneration of Ru when Ru picks up an electron from the amino acids allows for continuous formation of radicals with Ru being oxidized by APS.
In the PCR tube that the reaction takes place in, numerous unstable protein radicals come in contact with each other through simple diffusion and react both intra- and intermolecularly to achieve a more stable state. The monomeric protein radicals are able to achieve a lower energy state through forming a covalent bond to produce a dimer and releasing a hydrogen atom. PLEASE NOTE: The image mistakenly shows the release of a proton and should not be used in this form (See also ref. 4). The creator has been contacted. This newly formed dimer is also able to react with numerous other monomers or dimers through the same mechanism, creating higher numbers of cross-linked oligomers. This allows for a distribution of variety of oligomers to be present in the mixture. | 1 | Applied and Interdisciplinary Chemistry |
The method is proposed as an assay that employs both cfDNA whole genome methylation sequencing and fragmentomic feature information for multicancer classification. Copy number ratios calculated for healthy and cancerous tissues are used as a cancer type and cancer existence identifier. As done in EPIC-seq, the method also utilizes fragment lengths. Short fragment over long fragment ratio is used in the method as an identifier score. Using the single base or region level methylation percentages on detected cancer methylation markers for each cancer type, copy number ratios, and short/long fragment ratios; the method employs a custom Support Vector Machines algorithm to classify the cancer type if there exists one. This method reports the cancer detection and tissue-of-origin of 4 cancer types. However, it requires detection of specific methylation sites/regions of interest for cancer types | 1 | Applied and Interdisciplinary Chemistry |
Establishing body axes is a critical step in animal development. During mouse embryonic development, Nodal, a transforming growth factor-beta superfamily ligand, is a key gene involved in patterning both the anterior-posterior axis and the left-right axis of the early embryo. The Nodal gene contains two enhancers: the Proximal Epiblast Enhancer (PEE) and the Asymmetric Enhancer (ASE). The PEE is upstream of the Nodal gene and drives Nodal expression in the portion of the primitive streak that will differentiate into the node (also referred to as the primitive node). The PEE turns on Nodal expression in response to a combination of Wnt signaling plus a second, unknown signal; thus, a member of the LEF/TCF transcription factor family likely binds to a TCF binding site in the cells in the node. Diffusion of Nodal away from the node forms a gradient which then patterns the extending anterior-posterior axis of the embryo. The ASE is an intronic enhancer bound by the fork head domain transcription factor Fox1. Early in development, Fox1-driven Nodal expression establishes the visceral endoderm. Later in development, Fox1 binding to the ASE drives Nodal expression on the left side of the lateral plate mesoderm, thus establishing left-right asymmetry necessary for asymmetric organ development in the mesoderm.
Establishing three germ layers during gastrulation is another critical step in animal development. Each of the three germ layers has unique patterns of gene expression that promote their differentiation and development. The endoderm is specified early in development by Gata4 expression, and Gata4 goes on to direct gut morphogenesis later. Gata4 expression is controlled in the early embryo by an intronic enhancer that binds another forkhead domain transcription factor, FoxA2. Initially the enhancer drives broad gene expression throughout the embryo, but the expression quickly becomes restricted to the endoderm, suggesting that other repressors may be involved in its restriction. Late in development, the same enhancer restricts expression to the tissues that will become the stomach and pancreas. An additional enhancer is responsible for maintaining Gata4 expression in the endoderm during the intermediate stages of gut development. | 1 | Applied and Interdisciplinary Chemistry |
SCV roofs confront a magnitude of challenges due to the adverse weather conditions of the Southeastern United States. High humidity levels, excessive rain amounts, prolonged heat, mold, mildew, insects, disease, weeds, soil borne disease, maintenance concerns, and sloped roofs are the major challenges faced in designing a SCV roof. High humidity levels, excessive rain amounts, prolonged heat lead to decreased plant health on CAM plants that are standard in green roof design. The decreased plant health causes diseases, insects, root rot, and plant fatality.
Soil-borne diseases occur more frequently due to warm, rainy, humid environment rhythm of the humid, subtropical region. SCV roof plants are researched and tested at several different universities throughout the southeast to avoid system failure and economic loses. Mold and mildew can form on areas of the roof and building when proper ventilation is not taken into consideration and are also repercussions of high humidity levels and prolonged heat.
One of the greatest challenges to SCV roofs can be hurricanes. The strong hurricane winds can cause uplifting of the roofs. High winds can scour the growth media where the plants are established. Scouring is the blowing of the particles in the growth media from the surface of the vegetated roof, thereby reducing the volume and weight of growth media and its ability to ballast the green roof.
Sloped roofs that are prevalent in the southeastern United States also pose a significant challenge for SCV roofs. Soil media erosion and poor plant establishment are the most common problems and can occur on any angle of sloped roof if not designed properly. Erosion blankets and green roof soil media stabilization products are used to mitigate the effects of sloped roofs. Flat roofs and low sloped roofs are conventional roof slopes by the building industry in the southeastern United States and allow for successful implementation of SCV roofs. | 1 | Applied and Interdisciplinary Chemistry |
The main components of a UV curing solution includes resins, monomers, and photoinitiators. Resin is an oligomer that imparts specific properties to the final polymer. A monomer is used as a cross-linking agent and regulates the viscosity of the mixture to suit the application. The photoinitiator is responsible for absorbing the light and kickstarting the reaction, which helps control the cure rate and depth of cure. Each of these elements has a role to play in the crosslinking process and is linked to the composition of the final polymer. | 0 | Theoretical and Fundamental Chemistry |
Capillary penetration in porous media shares its dynamic mechanism with flow in hollow tubes, as both processes are resisted by viscous forces. Consequently, a common apparatus used to demonstrate the phenomenon is the capillary tube. When the lower end of a glass tube is placed in a liquid, such as water, a concave meniscus forms. Adhesion occurs between the fluid and the solid inner wall pulling the liquid column along until there is a sufficient mass of liquid for gravitational forces to overcome these intermolecular forces. The contact length (around the edge) between the top of the liquid column and the tube is proportional to the radius of the tube, while the weight of the liquid column is proportional to the square of the tube's radius. So, a narrow tube will draw a liquid column along further than a wider tube will, given that the inner water molecules cohere sufficiently to the outer ones. | 0 | Theoretical and Fundamental Chemistry |
Koded membranes are described by the construct and the concentration of FSL (in μg/mL) used to create them. For example, kodecytes created with a 100 μg/mL solution of FSL-A would be termed A100 kodecytes. If multiple FSL constructs were used then the definition is expanded accordingly, e.g. A100+B300 kodecytes are created with a solution containing 100 μg/mL solution of FSL-A and 300 μg/mL solution of FSL-B. The "+" symbol is used to separate the construct mixes, e.g. A100+B300. If FSL concentrations are constant then the μg/mL component of the terminology can be dropped, e.g. A kodecytes. Alternatively unrelated constructs such as FSL-A and FSL-biotin will create A+biotin kodecytes, etc. If different cells are used in the same study then inclusion of the cell type into the name is recommended, e.g. RBC A100 kodecytes vs WBC A100 kodecytes, or platelet A100 kodecytes, etc. | 1 | Applied and Interdisciplinary Chemistry |
Sigma-2 receptors are highly expressed in breast, ovarian, lung cancers, brain, bladder, colon cancers, and melanoma. This novelty makes them a valuable biomarker for identifying cancerous tissues. Furthermore, studies have shown that they are more highly expressed in malignant tumors than dormant tumors.
Exogenous sigma-2 receptor ligands have been altered to be neuronal-tracers, used to map cells and their connections. These tracers have high selectivity and affinity for sigma-2 receptors, and high lipophilicity, making them ideal for usage in the brain. Because sigma-2 receptors are highly expressed in tumor cells and are part of the cell proliferation mechanism, PET scans using sigma-2 targeted tracers can reveal if a tumor is proliferating and what its growth rate is. | 1 | Applied and Interdisciplinary Chemistry |
In attempts to raise the chemical and quantum yields of nitrobenzyl-based PPGs, several beneficial modifications have been identified. The largest increase in quantum yield and reaction rate can be achieved through substitution at the benzylic carbon. However, potential substitutions must leave one hydrogen atom so the photodegradation can proceeded uninhibited.
Additional modifications have targeted the aromatic chromophore. Specifically, multiple studies have confirmed that the use of a 2,6-dinitrobenzyl PPG increases reaction yield. Additionally, depending on the leaving group, the presence of a second nitro-group may nearly quadruple the quantum yield (e.g. Φ = 0.033 to Φ = 0.12 when releasing a carbonate at 365 nm). While one may credit the increase in efficiency to the electronic effects of the second nitro group, this is not the case. Analogous systems with a 2-cyano-6-nitrobenzyl PPG exhibit similar electron-withdrawing effects, but do not provide such a large increase in efficiency. Therefore, the increase in efficiency is likely due to the increased probability of achieving the aci-nitro state; with two nitro groups, an incoming photon will be twice as likely to promote the compound into an excited state.
Finally, changing the excitation wavelength of the PPG may be advantageous. For example, if two PPGs have different excitation wavelengths one group may be removed while the other is left in place. To this end, several nitrobenzyl based PPGs display additional functionality. Common modifications include the use of 2-nitroveratryl (NV) or 6-nitropiperonulmethyl (NP). Both of these modifications induced red-shifting in the compounds' absorption spectra. | 0 | Theoretical and Fundamental Chemistry |
Hydrogen for the reduction of C=N double bond can either be provided by hydrogen gas (H) or transferred from sources of H, such as alcohols and formic acid. The process is usually catalyzed by transition metal complexes. For metal catalyzed reactions, the transfer of H to the imine can proceed by either inner sphere or outer sphere mechanisms. | 0 | Theoretical and Fundamental Chemistry |
In rolling element bearings fretting may occur when the bearings are operating in an oscillating motion. Examples of applications are blade bearings in wind turbines, helicopter rotor pitch bearings, and bearings in robots. If the bearing movement is limited to small motions the damage caused may be called fretting or false brinelling depending on mechanism encountered. The main difference is that false brinelling occurs under lubricated and fretting under dry contact conditions. Between false brinelling and fretting corrosion, a time-dependent relation has been proposed. | 1 | Applied and Interdisciplinary Chemistry |
Sonication is the act of applying sound energy to agitate particles in a sample, for various purposes such as the extraction of multiple compounds from plants, microalgae and seaweeds. Ultrasonic frequencies (> 20 kHz) are usually used, leading to the process also being known as ultrasonication or ultra-sonication.
In the laboratory, it is usually applied using an ultrasonic bath or an ultrasonic probe, colloquially known as a sonicator. In a paper machine, an ultrasonic foil can distribute cellulose fibres more uniformly and strengthen the paper. | 1 | Applied and Interdisciplinary Chemistry |
Considerable research effort continues to be directed toward the purpose and ramifications of alarm-calling behaviour, because, to the extent that this research has the ability to comment on the occurrence or non-occurrence of altruistic behaviour, these findings can be applied to the understanding of altruism in human behaviour. | 1 | Applied and Interdisciplinary Chemistry |
It has been studies that a type of cerein 8A is very effective in inhibiting the effects of the pathogenic bacteria Salmonella enterica subsp. enterica that causes diarrhea, stomach aches, and fever. In clinical research, it was discovered that cerein 8A in combination with combination with sodium lactate killed Salmonella enterica in a dose-dependent fashion. Cerein 8A was also found to inhibit growth of Listeria monocytogenes, a pathogenic bacteria commonly found in dairy products such as milk. | 1 | Applied and Interdisciplinary Chemistry |
Electrofusion welding is a form of resistive implant welding used to join pipes. A fitting with implanted metal coils is placed around two ends of pipes to be joined, and current is passed through the coils. Resistive heating of the coils melts small amounts of the pipe and fitting, and upon solidification, a joint is formed. It is most commonly used to join polyethylene (PE) and polypropylene (PP) pipes. Electrofusion welding is the most common welding technique for joining PE pipes. Because of the consistency of the electrofusion welding process in creating strong joints, it is commonly employed for the construction and repair of gas-carrying pipelines. The development of the joint strength is affected by several process parameters, and a consistent joining procedure is necessary for the creation of strong joints. | 0 | Theoretical and Fundamental Chemistry |
Commonly used protein production systems include those derived from bacteria, yeast, baculovirus/insect, mammalian cells, and more recently filamentous fungi such as Myceliophthora thermophila. When biopharmaceuticals are produced with one of these systems, process-related impurities termed host cell proteins also arrive in the final product in trace amounts. | 1 | Applied and Interdisciplinary Chemistry |
In the 1950s, a series of epidemiological studies were done in the US to determine the relationship between water quality of natural waters and the health of bathers. The results indicated that swimmers were more likely to have gastrointestinal symptoms, eye infections, skin complaints, ear, nose, and throat infections and respiratory illness than non-swimmers and in some cases, higher coliform levels correlated to higher incidence of gastrointestinal illness, although the sample sizes in these studies were small. Since then, studies have been done to confirm causative relations between swimming and certain health outcomes. A review of 22 studies in 1998 confirmed that the health risks for swimmers increased as the number of indicator bacteria increased in recreational waters and that E. coli and enterococci concentrations correlated best with health outcomes among all the indicators studied. The relative risk (RR) of illness for swimmers in polluted freshwater versus swimmers in unpolluted water was between 1–2 for the majority of the data sets reviewed. The same study concluded that bacterial indicators were not well correlated to virus concentrations. | 0 | Theoretical and Fundamental Chemistry |
RegulonDB is a database of the regulatory network of gene expression in Escherichia coli K-12. RegulonDB also models the organization of the genes in transcription units, operons and regulons. A total of 120 sRNAs with 231 total interactions which all together regulate 192 genes are also included. RegulonDB was founded in 1998 and also contributes data to the EcoCyc database. | 1 | Applied and Interdisciplinary Chemistry |
A molecular logic gate is a molecule that performs a logical operation based on one or more physical or chemical inputs and a single output. The field has advanced from simple logic systems based on a single chemical or physical input to molecules capable of combinatorial and sequential operations such as arithmetic operations (i.e. moleculators and memory storage algorithms). Molecular logic gates work with input signals based on chemical processes and with output signals based on spectroscopic phenomena.
Logic gates are the fundamental building blocks of electrical circuits. They can be used to construct digital architectures with varying degrees of complexity by a cascade of a few to several million logic gates. Logic gates are essentially physical devices that produce a singular binary output after performing logical operations based on Boolean functions on one or more binary inputs. The concept of molecular logic gates, extending the applicability of logic gates to molecules, aims to convert chemical systems into computational units. Over the past three decades, the field has evolved to realize several practical applications in molecular electronics, biosensing, DNA computing, nanorobotics, and cell imaging, among others. | 0 | Theoretical and Fundamental Chemistry |
In the analysis of the molecular formula of organic molecules, the degree of unsaturation (DU) (also known as the index of hydrogen deficiency (IHD), double bond equivalents (DBE), or unsaturation index) is a calculation that determines the total number of rings and π bonds. A formula is used in organic chemistry to help draw chemical structures. It does not give any information about those components individually—the specific number of rings, or of double bonds (one π bond each), or of triple bonds (two π bonds each). The final structure is verified with use of NMR, mass spectrometry and IR spectroscopy, as well as qualitative inspection. It is based on comparing the actual molecular formula to what would be a possible formula if the structure were saturated—having no rings and containing only σ bonds—with all atoms having their standard valence. | 0 | Theoretical and Fundamental Chemistry |
The reverse Krebs cycle is proposed to be a major role in the pathophysiology of melanoma. Melanoma tumors are known to alter normal metabolic pathways in order to utilize waste products. These metabolic adaptations help the tumor adapt to its metabolic needs. The most well known adaptation is the Warburg effect where tumors increase their uptake and utilization of glucose. Glutamine is one of the known substances to be utilized in the reverse Krebs cycle in order to produce acetyl-CoA. This type of mitochondrial activity could provide a new way to identify and target cancer causing cells. | 1 | Applied and Interdisciplinary Chemistry |
Deviations from ideality can be described by the use of Margules functions or activity coefficients. A single Margules parameter may be sufficient to describe the properties of the solution if the deviations from ideality are modest; such solutions are termed regular.
In contrast to ideal solutions, where volumes are strictly additive and mixing is always complete, the volume of a non-ideal solution is not, in general, the simple sum of the volumes of the component pure liquids and solubility is not guaranteed over the whole composition range. By measurement of densities, thermodynamic activity of components can be determined. | 0 | Theoretical and Fundamental Chemistry |
†The value is exact but not expressible as a finite decimal; approximated to 9 decimal places only.
Since is a proportionality factor between temperature and energy, its numerical value depends on the choice of units for energy and temperature. The small numerical value of the Boltzmann constant in SI units means a change in temperature by 1 K only changes a particle's energy by a small amount. A change of is defined to be the same as a change of . The characteristic energy is a term encountered in many physical relationships.
The Boltzmann constant sets up a relationship between wavelength and temperature (dividing hc/k by a wavelength gives a temperature) with one micrometer being related to , and also a relationship between voltage and temperature (kT in units of eV corresponds to a voltage) with one volt being related to . The ratio of these two temperatures, / ≈ 1.239842, is the numerical value of hc in units of eV⋅μm. | 0 | Theoretical and Fundamental Chemistry |
Although polyrotaxanes are formed from components, their solubilities are different from the host or guest molecules. For examples, in the cyclodextrin-based polyrotaxanes, due to the hydrophilicity or high polarity of exterior structure of the cyclodextrins, some polyrotaxanes are able to be dissolved in water or other polar solvents though the guest molecules are hydrophobic or nonpolar. These water-soluble can be applied into drug or gene carriers.
There are two main advantages for polyrotaxanes applied to drug/gene delivery: | 0 | Theoretical and Fundamental Chemistry |
In 1996, the ISCRE Board of Directors established the Neal R. Amundson Award for Excellence in Chemical Reaction Engineering. This award recognizes a pioneer in the field of Chemical Reaction Engineering who has exerted a major influence on the theory or practice of the field, through originality, creativity, and novelty of concept or application. The award is made every three years at an ISCRE meeting, and consists of a Plaque and a check in the amount of $5000. The Amundson Award is generously supported by a grant from the ExxonMobil Corporation. Winners of the award include:
* 1996: Neal Amundson, Professor - University of Minnesota, University of Houston
* 1998: Rutherford Aris, Professor - University of Minnesota
* 2001: Octave Levenspiel, Professor - Oregon State University
* 2004: Vern Weekman, Mobil
* 2007: Gilbert Froment, Professor - Ghent University, Texas A&M University
* 2010: Dan Luss, Professor - University of Houston
* 2013: Lanny Schmidt, Professor - University of Minnesota
* 2016: Milorad P. Dudukovic, Professor - Washington University
* 2019: W. Harmon Ray, Professor - University of Wisconsin
* 2022: Announced at NASCRE-5 | 1 | Applied and Interdisciplinary Chemistry |
The sodium carbonate test (not to be confused with sodium carbonate extract test) is used to distinguish between some common metal ions, which are precipitated as their respective carbonates. The test can distinguish between copper (Cu), iron (Fe), and calcium (Ca), zinc (Zn) or lead (Pb). Sodium carbonate solution is added to the salt of the metal. A blue precipitate indicates Cu ion. A dirty green precipitate indicates Fe ion. A yellow-brown precipitate indicates Fe ion. A white precipitate indicates Ca, Zn, or Pb ion. The compounds formed are, respectively, basic copper carbonate, iron(II) carbonate, iron(III) oxide, calcium carbonate, zinc carbonate, and lead(II) carbonate. This test is used to precipitate the ion present as almost all carbonates are insoluble. While this test is useful for telling these cations apart, it fails if other ions are present, because most metal carbonates are insoluble and will precipitate. In addition, calcium, zinc, and lead ions all produce white precipitates with carbonate, making it difficult to distinguish between them. Instead of sodium carbonate, sodium hydroxide may be added, this gives nearly the same colours, except that lead and zinc hydroxides are soluble in excess alkali, and can hence be distinguished from calcium. See qualitative inorganic analysis for the complete sequence of tests used for qualitative cation analysis. | 0 | Theoretical and Fundamental Chemistry |
Zearalenone has two major phase I metabolites: α-zearalenol and β-zearalenol. When exposed orally ZEN is absorbed by the intestinal lining and metabolized there as well as in the liver. Research into the metabolism of ZEN has been difficult because of the significant difference in biotransformation between species making comparison challenging. | 1 | Applied and Interdisciplinary Chemistry |
Watt's Expansion Engine is generally considered as of historic interest only. There are however some recent developments which may lead to a renaissance of the technology. Today, there is an enormous amount of waste steam and waste heat with temperatures between 100 and 150 °C generated by industry. In addition, solarthermal collectors, geothermal energy sources and biomass reactors produce heat in this temperature range. There are technologies to utilise this energy, in particular the Organic Rankine Cycle. In principle, these are steam turbines which do not use water but a fluid (a refrigerant) which evaporates at temperatures below 100 °C. Such systems are however fairly complex. They work with pressures of 6 to 20 bars, so that the whole system has to be completely sealed.
The Expansion Engine can offer significant advantages here, in particular for lower power ratings of 2 to 100 kW: with expansion ratios of 1:5, the theoretical efficiency reaches 15%, which is in the range of ORC systems. The Expansion Engine uses water as working fluid which is simple, cheap, non-toxic, non-flammable and non-corrosive. It works at pressure near and below atmospheric, so that sealing is not a problem. And it is a simple machine, implying cost effectiveness. Researchers from the University of Southampton / UK are currently developing a modern version of Watt's engine in order to generate energy from waste steam and waste heat. They improved the theory, demonstrating that theoretical efficiencies of up to 17.4% (and actual efficiencies of 11%) are possible.
In order to demonstrate the principle, a 25 watt experimental model engine was built and tested. The engine incorporates steam expansion as well as new features such as electronic control. The picture shows the model built and tested in 2016. Currently, a project to build and test a scaled-up 2 kW engine is under preparation. | 0 | Theoretical and Fundamental Chemistry |
The application of DC electric fields is known to reduce the flow stress of metals and metal alloys while increasing the fracture strain. Several mechanisms have been put forth to explain this effect including Joule heating, electron wind force, dissolution of metallic bonds, and unpinning of dislocations due the induction of magnetic fields. None of these mechanisms on their own can sufficiently explain the full extent of electroplasticity in metals. The application of electric fields has been shown to enhance the effect of superplasticity which occurs in polycrystalline metals at high homologous temperatures (T>0.5Tm). This is likely due to the electric field reducing cavitation, which can lead to premature fracture, and grain growth, which can prevent superplastic flow due to grain boundary sliding, in addition to reducing the activation energy for grain boundary sliding. The strength of the electroplastic effect scales with the magnitude of the applied electric field past some threshold value. While the application of an electric field typically augments the plasticity of metals there are alloy systems that show a reduction in plasticity. Conrad and Li found that the activation energy for grain boundary sliding in Zn-5 wt.% Al increased by nearly 20% under the application of a 2 DC electric field, resulting in more difficult deformation. | 0 | Theoretical and Fundamental Chemistry |
Analysis and design of marine structures or systems necessitates integration of hydrodynamics and structural mechanics; i.e. hydroelasticity plays the key role. There has been significant recent progress in research into the hydroelastic phenomena, and the topic of hydroelasticity is of considerable current interest. | 1 | Applied and Interdisciplinary Chemistry |
Protein skimming removes certain organic compounds, including proteins and amino acids found in food particles and fish waste, by using the polarity of the protein itself. Due to their intrinsic charge, water-borne proteins are either repelled or attracted by the air/water interface and these molecules can be described as hydrophobic (such as fats or oils) or hydrophilic (such as salt, sugar, ammonia, most amino acids, and most inorganic compounds). However, some larger organic molecules can have both hydrophobic and hydrophilic portions. These molecules are called amphipathic or amphiphilic. Commercial protein skimmers work by generating a large air/water interface, specifically by injecting large numbers of bubbles into the water column. In general, the smaller the bubbles the more effective the protein skimming is because the surface area of small bubbles occupying the same volume is much greater than the same volume of larger bubbles. Large numbers of small bubbles present an enormous air/water interface for hydrophobic organic molecules and amphipathic organic molecules to collect on the bubble surface (the air/water interface). Water movement hastens diffusion of organic molecules, which effectively brings more organic molecules to the air/water interface and lets the organic molecules accumulate on the surface of the air bubbles. This process continues until the interface is saturated, unless the bubble is removed from the water or it bursts, in which case the accumulated molecules release back into the water column. However, it is important to note that further exposure of a saturated air bubble to organic molecules may continue to result in changes as compounds that bind more strongly may replace those molecules with a weaker binding that have already accumulated on the interface. Although some aquarists believe that increasing the contact time (or dwell time as it is sometimes called) is always good, it is incorrect to claim that it is always better to increase the contact time between bubbles and the aquarium water. As the bubbles increase near the top of the protein skimmer water column, they become denser and the water begins to drain and create the foam that will carry the organic molecules to the skimmate collection cup or to a separate skimmate waste collector and the organic molecules, and any inorganic molecules that may have become bound to the organic molecules, will be exported from the water system.
In addition to the proteins removed by skimming, there are a number of other organic and inorganic molecules that are typically removed. These include a variety of fats, fatty acids, carbohydrates, metals such as copper, and trace elements such as iodine. Particulates, phytoplankton, bacteria, and detritus are also removed; this is desired by some aquarists, and is often enhanced by placement of the skimmer before other forms of filtration, lessening the burden on the filtration system as a whole. There is at least one published study that provides a detailed list of the export products removed by the skimmer. Aquarists who keep filter-feeding invertebrates, however, sometimes prefer to keep these particulates in the water to serve as natural food.
Protein skimmers are used to harvest algae and phytoplankton gently enough to maintain viability for culturing or commercial sale as live cultures.
Alternative forms of water filtration have recently come into use, including the algae scrubber, which leaves food particles in the water for corals and small fish to consume, but removes the noxious compounds including ammonia, nitrite, nitrate, and phosphate that protein skimmers do not remove. | 0 | Theoretical and Fundamental Chemistry |
Many commercial and subsistence fisheries in arctic and subarctic regions fish for cod, salmon, crab, groundfish, and pollock depend on this energy-rich zooplankton as food. In 2017, the highest value of commercial fish species for the US was salmon ($688 million), crabs ($610 million), shrimp ($531 million), scallops ($512 million), and pollock ($413 million). Pollock alone is the largest fishery in the US based on volume, but is also the second largest fishery in the world supporting 2–5% of the global fishery production. Not only do millions of people rely on fish for subsistence, but recreational fishing is one of the most popular activities in the US. Recreational fishing contributes about $202 million to the US economy. Changes in the abundance and distribution of copepods could drastically affect the economic livelihoods of millions of people connected to the fishing industry or who rely on fishing as a primary source of protein. | 0 | Theoretical and Fundamental Chemistry |
The prolemuris (Syaksyuk in Navi) are blue, hexapodal creatures based on Earths lemurs. They have two eyes, small nostrils, and their two upper arms on each side are partially fused. Like most Pandoran creatures, they have a queue on the back of their heads. They have lateral skin membranes on each side of the body. They have large eyes and grow 1.5 meters tall. | 1 | Applied and Interdisciplinary Chemistry |
Severyn Marcel Sternhell (30 May 1930 – 18 November 2022) was a Polish-born Australian academic and organic chemist. He was professor of Chemistry at the University of Sydney and a Fellow of the Australian Academy of Science. His research focused on the induction of chirality into mesophases, aspects of steric hindrance and the mechanochemistry of organic compounds. | 0 | Theoretical and Fundamental Chemistry |
The current knowledge of the molecular mechanisms for Mg transport in plants is very limited, with only three publications reporting a molecular basis for Mg transport in plants. However, the importance of Mg to plants has been well described, and physiological and ecophysiological studies about the effects of Mg are numerous. This section will summarise the knowledge of a gene family identified in plants that is distantly related to CorA. Another gene, a Mg/H exchanger (AtMHX), unrelated to this gene family and to CorA has also been identified, is localised to the vacuolar membrane, and will be described last. | 1 | Applied and Interdisciplinary Chemistry |
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