Xem 1-20 trên 262 kết quả Chemical form
  • Primary chemically formed lead dioxide (PbO2 ) was used as positive electrode in preparation of lead–acid bipolar batteries. Chemical oxidation was carried out by both mixing and dipping methods using an optimized amount of ammonium persulfate as a suitable oxidizing agent. Xray diffraction studies showed that the weight ratio of -PbO2 to -PbO2 is more for mixing method before electrochemical forming.

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  • Permanganate may be applied to sites as either potassium permanganate (KMnO4) or sodium permanganate (NaMnO4). Where cost dominates over engineering factors at a site, potassium permanganate is the preferred chemical form because it is more widely available, less costly, and is available in solid form, which facilitates transport and handling. Where other factors are more important, the liquid form of sodium permangante is preferable.

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  • “Cyanide” is a chemical with a long and fascinating history of respectful and productive use by mankind. The fundamental cyanide species, the cyanide ion CN−, is a highly versatile and strong binder of metals in aqueous solution, a property that has been exploited in ingenious ways for commercial processes that have benefited society. The best known and largest volume uses of cyanide are in the gold mining and electroplating industries.

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  • Preparations derived from Lentinula edodes (Berk.) Pegl. mycelium are worldwide used as dietary supplements containing compounds active as immune system enhancers, demonstrating chemopreventive and anticancer activity. L. edodes mycelium enriched with organic forms of selenium like selenized yeast possess putative, higher cancer preventive properties. The objective of this study was to test the effect of enrichment in selenium on antioxidant, reducing and free radical scavenging activity of water and alcohol extracts from mycelium of L. edodes (Berk.).

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  • Chemical substances (also called pure substances) may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[2] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[3] The chemical substance index published by CAS also includes several alloys of uncertain composition.

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  • Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, table salt (sodium chloride) and refined sugar (sucrose). However, simple or seemingly pure substances found in nature can in fact be mixtures of chemical substances.

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  • Proteins of the B-cell lymphoma protein 2 (Bcl2) family are key regulators of the apoptotic cascade, controlling the release of apoptotic factors from the mitochondrial intermembrane space. A helical hairpin found in the core of water-soluble folds of these proteins has been reported to be the pore-forming domain.

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  • Butterworth-Heinemann An imprint of Elsevier Science Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 First published 1994 Second edition 2002 Copyright © 1994, 2002, Phillip Carson, Clive Mumford.

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  • Bovine seminal ribonuclease (BS-RNase), a homodimeric protein displaying selective cytotoxicity towards tumor cells, is isolated as a mixture of two isoforms, a dimeric form in which the chains swap their N-termini, and an unswapped dimer.

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  • The crystal structures ofThermoactinomyces vulgariscyclo⁄maltodextrin-binding protein (TvuCMBP) complexed with a-cyclodextrin (a-CD), b-cyclodextrin (b-CD) and maltotetraose (G4) have been determined. A common functional conformational change among all solute-binding pro-teins involves switching from an open form to a closed form, which facili-tates transporter binding.

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  • The crystal structure of glycerol kinase from the hyperthermophilic archa-eon Thermococcus kodakaraensis(Tk-GK) in a dimeric form was deter-mined at a resolution of 2.4 A˚ . This is the first crystal structure of a hyperthermophilic glycerol kinase.

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  • 2-Amino-5-carboxymuconic 6-semialdehyde is an unstable intermediate in the meta-cleavage pathway of 4-amino-3-hydroxybenzoic acid inBordetellasp. strain 10d.In vitro, this compound is nonenzymatically converted to 2,5-pyrid-inedicarboxylic acid. Crude extracts of strain 10d grown on 4-amino-3-hydroxybenzoic acid converted 2-amino-5-car-boxymuconic 6-semialdehyde formed from 4-amino-3-hydroxybenzoic acid by the first enzyme in the pathway, 4-amino-3-hydroxybenzoate 2,3-dioxygenase, to a yellow compound (emax¼375 nm).

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  • The electrophoretic deposition (EPD) method was adopted for a fabrication of nanocomposite layers composed of ZnO particles covered by the polythiopene shell in a reduced state. This composite was prepared by oxidative polymerization of thiophene monomer with iron (III) chloride as a catalyst in the presence of ZnO particles. After polymerization, polythiophene in oxidized form was reduced by the extraction in methanol. Electrochemical properties of the obtained composite were measured by cyclic voltammetry and electrochemical impedance spectroscopy.

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  • Pro-forms of growth factors have received increasing attention since it was shown that they can affect both the maturation and functions of mature growth factors. Here, we assessed the biological function of the pro-form of bone morphogenetic protein-2 (BMP-2), a member of the transforming growth factorb(TGFb)⁄BLP superfamily.

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  • Highly-purified peroxisomes from the yeastSaccharomyces cerevisiaegrown on oleic acid were investigated for the presence of channel (pore)-forming proteins in the membrane of these organelles. Solubilized membrane pro-teins were reconstituted in planar lipid bilayers and their pore-forming activity was studied by means of multiple-channel monitoring or single-channel analysis.

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  • Many organelle enzymes coded for by nuclear genes have N-terminal sequences, which directs them into the organelle (precursor) and are removed upon import (mature). The experiments described below charac-terize the differences between the precursor and mature forms of water-melon glyoxysomal malate dehydrogenase. Using recombinant protein methods, the precursor (p-gMDH) and mature (gMDH) forms were puri-fied to homogeneity using Ni 2+ –NTA affinity chromatography.

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  • The active form of the oxygen sensor fumarate nitrate reductase regulator (FNR) of Escherichia colicontains a [4Fe-4S] cluster which is converted to a [2Fe-2S] cluster after reaction with air, resulting in inactivation of FNR. Reaction of reconstituted [4Fe-4S]ÆFNR with air resulted within 5 min in conversion to apoFNR. The rate was comparable to the rate known for [4Fe-4S]ÆFNR⁄[2Fe-2S]ÆFNR cluster conversion, suggesting that apoFNR is a product of [2Fe-2S]ÆFNR decomposition and a final form of air-inacti-vated FNR in vitro. ...

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  • The heat-stable enterotoxin peptides (ST) produced by enterotoxigenicEscherichia coliare one of the major causes of transitory diarrhea in the developing world. Toxin bind-ing to its receptor, guanylyl cyclase C (GC-C), results in receptor activation and the production of high intracellular levels of cGMP. GC-C is expressed in two differentially glycosylated forms in intestinal epithelial cells. Prolonged exposure of human colonic cell lines to ST peptides induces cellular refractoriness to the ST peptide, in terms of intra-cellular cGMP accumulation....

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  • Lecture Biology - Chapter 7: Pathways that harvest chemical energy. The topics discussed in this chapter are: How does glucose oxidation release chemical energy? What are the aerobic pathways of glucose metabolism? How is energy harvested from glucose in the absence of oxygen? How does the oxidation of glucose form ATP? Why does cellular respiration yield so much more energy than fermentation? How are metabolic pathways interrelated and controlled?

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  • Petroleum products are everywhere around us. They appear in visible forms, such as gasoline, diesel, kerosene, and aircraft fuels, and in less visible forms over the entire spectrum of industry, such as automobile lubricants, greases, carbon black for truck tires, bitumen for road building, the waterproofing in house roofs, feedstock for petrochemicals, synthetic fibers, and plastics. Petroleum feedstock is used in the manufacture of white mineral oils in eye ointment, hair oils, cosmetics, petroleum solvents, and pest control sprays....

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