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Topic Review
Chemical and Physical Properties of Solid Salt Fluxes
Solid salt fluxes are inorganic compounds that are added during the treatment of molten aluminum to improve the final quality. An understanding of the chemical composition of the flux is essential for the assessment of the physical and chemical behavior of the flux. The chemical composition of the flux can be tailored to adjust properties such as density, viscosity, reactivity, and wettability. Such properties, in turn, will impart different functions to the flux. 
  • 918
  • 05 May 2023
Topic Review
Chemical Bonding of H2O
Water (H2O) is a simple triatomic bent molecule with C2v molecular symmetry and bond angle of 104.5° between the central oxygen atom and the hydrogen atoms. Despite being one of the simplest triatomic molecules, its chemical bonding scheme is nonetheless complex as many of its bonding properties such as bond angle, ionization energy, and electronic state energy cannot be explained by one unified bonding model. Instead, several traditional and advanced bonding models such as simple Lewis and VESPR structure, valence bond theory, molecular orbital theory, isovalent hybridization, and Bent's rule are discussed below to provide a comprehensive bonding model for H2O, explaining and rationalizing the various electronic and physical properties and features manifested by its peculiar bonding arrangements.
  • 5.8K
  • 18 Oct 2022
Topic Review
Chemical Composition of Giant Miscanthus from Different Climatic Regions
Lignocellulosic biomass is of great interest as an alternative energy resource because it has a number of advantages. Miscanthus x gigantis is a lignocellulosic feedstock of particular interest because it combines high biomass productivity with low environmental impact, including control of CO 2 emissions. The chemical composition of lignocellulose determines the possibilities of its use for efficient industrial processing. Here we have collected specimens from a collection of Miscanthus x giganteus, which were grown in different climatic regions between 2019 and 2021. The chemical composition was quantified using traditional wet methods. The results were compared with each other and with known data. It has been shown that already from the first year of vegetation, miscanthus has the following chemical composition: cellulose content 43.2–55.5%, acid-insoluble lignin content 17.1–25.1%, pentosan 17.9–22.9%, ash content 0, 90–2.95%, and 0.3–1.2% extractives. Habitat and environment have been found to influence the chemical composition of miscanthus. It was found that the stem part of miscanthus is richer in fiber than the leaf part (48.4–54.9% versus 47.2–48.9%, respectively), regardless of the age of the plantation and habitat. The data obtained expand the geography of research into the chemical composition of miscanthus and confirm the high value of miscanthus for industrial processing into cellulose products around the world.
  • 291
  • 26 Oct 2023
Topic Review
Chemical Composition on Heating Value of Biomass
Biomass has become an increasingly important resource for energy generation. It is well known that the heating value of lignin is significantly higher (23.26–25.58 MJ/kg) than that of polysaccharides (18.6 MJ/kg), while extractives often have higher heating values (HHVs) over 30 MJ/kg, depending on their oxidation levels. Therefore, the proportions of the chemical components in biomass determine its HHV.
  • 1.1K
  • 31 May 2023
Topic Review
Chemical Depolymerization Methods of Poly(ethylene terephthalate)
The significant amount of waste generated by poly(ethylene terephthalate) (PET) requires the development of a recycling process chain in which chemical recycling plays an important role. On the one hand, it allows the depolymerization of degraded plastics that do not meet the quality requirements to be used in mechanical recycling, and on the other hand, provides an opportunity to process cheap waste and obtain products with greater added value. It can be widely used in the recycling of both packaging plastics and textiles, or other waste generated with PET.
  • 756
  • 12 Oct 2023
Topic Review
Chemical Derivatization in Flow Analysis
Chemical derivatization involves modification of the analyte for improving selectivity and/or sensitivity. It is particularly attractive in flow analysis in view of its highly reproducible reagent addition(s) and controlled timing. Then, measurements without attaining the steady state, kinetic discrimination, exploitation of unstable reagents and/or products, as well as strategies compliant with Green Analytical Chemistry, have been efficiently exploited. Flow-based chemical derivatization has been accomplished by different approaches, involving e.g. flow and manifold programming, solid-phase reagents, and strategies for sample insertion and reagent addition, as well as to increase sample residence time.
  • 720
  • 08 Mar 2022
Topic Review
Chemical Enzymology of Monoamine Oxidase
Monoamine oxidase (E.C. 1.4.3.4) enzymes MAO A and MAO B are FAD-containing proteins located on the outer face of the mitochondrial inner membrane, retained there by hydrophobic interactions and a transmembrane helix. The redox co-factor (FAD) is covalently attached to a cysteine and buried deep inside the protein behind an aromatic cage that aligns substrates towards the flavin. MAO metabolizes neurotransmitters such as dopamine and serotonin in the nervous system so is a target for drugs to modify amine levels. MAO also metabolizes a wide range of biogenic amines in all tissues. Current accumulated evidence, particularly from theoretical modelling, supports hydride transfer as the chemical mechanism. The long active site cavity accommodates a wide chemical variety of small molecules designed as inhibitors, including coumarins, chromones, triazoles, and more. Inactivators that bind covalently to MAO include hydrazines, cyclopropylamines and propargylamines. This entry is an extract adapted from a review outlining the remaining uncertainties in the understanding of this key drug target.
  • 1.1K
  • 19 Oct 2021
Topic Review
Chemical Explosive
The vast majority of explosives are chemical explosives. Explosives usually have less potential energy than fuels, but their high rate of energy release produces a great blast pressure. TNT has a detonation velocity of 6,940 m/s compared to 1,680 m/s for the detonation of a pentane-air mixture, and the 0.34-m/s stoichiometric flame speed of gasoline combustion in air. The properties of the explosive indicate the class into which it falls. In some cases explosives can be made to fall into either class by the conditions under which they are initiated. In sufficiently large quantities, almost all low explosives can undergo a Deflagration to Detonation Transition (DDT). For convenience, low and high explosives may be differentiated by the shipping and storage classes.
  • 787
  • 01 Nov 2022
Topic Review
Chemical Industry in China
The chemical industry in China is one of China's main manufacturing industries. It valued at around $1.44 trillion in 2014, and China is currently the largest chemicals manufacturing economy in the world. The chemical industry is central to modern China's economy. It uses special methods to alter the structure, composition or synthesis of substances to produce new products, such as steel, plastic, and ethyl. Chemical industry provides building materials for China's infrastructure, including subway, high-speed train, and highway. Prior to 1978, most of the product was produced by the state-owned business, and the share in product outputted by state-owned business had decreased in 2002. The Chinese chemical industry is also one of the world's largest producers of both controlled and non-controlled precursor chemicals used in the Global illicit drug trade, particularly in the Golden Triangle as well as Latin America.
  • 1.5K
  • 26 Oct 2022
Topic Review
Chemical looping
Chemical looping technology in general, is the rising star in chemical technologies, which is capable of low CO2 emissions with applications in the production of heat, fuels, chemicals, and electricity. This entry discusses the technology in general, gives an overview of some pilot scale plants and the different chemical looping processes with focus on the production of heat and chemicals, highlights the importance of the development of oxygen carrier materials with suitable properties, 2.11.0.0 2.11.0.0
  • 3.1K
  • 02 Nov 2020
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