Synthetic chemicals

In this report, the solid phase extraction technique combined with the gas chromatographymass spectrometry method (GC-MS) was optimized to determine the contamination of nine phthalic acid esters (PAEs) in the surface sediment samples collected from Rao Cai River in Ha Tinh, Vietnam.

7p vifilm 11-10-2024 0 0   Download

In this review we probe the reaction mechanisms for formation of DNA nucleobases from formamide (FM) following the free radical pathways that have been identified by quantum chemical computations. Formamide is known as a precursor of nucleobases in the prebiotic chemistry of the Early Earth or in the nitrogen-rich atmosphere such as Titan, regardless of whether water is present or absent.

34p viyoko 01-10-2024 3 1   Download

In this research, in an attempt to make use of the kaolin resources in Vietnam, we present a synthetic process of zeolite A via hydrothermal from kaolinite, together with the modification process of zeolite A using different metallic cations. The characteristics of the prepared zeolite LTAs such as chemical composition and crystalline structure, as well as their catalytic activity in the methanation reaction of carbon dioxide (CO2) to methane (CH4) were extensively investigated.

8p dianmotminh02 03-05-2024 7 1   Download

Objectives of the dissertation: Research and synthesize and determine the hybrid compound structure containing Quinazoline frame. Research on carcinogenic activity and inhibition of acetylcholinesterase enzyme of synthetic compounds..

26p extraenglish 24-05-2021 21 3   Download

Presently there is a great demand for the use of natural colours throughout the world due to non-biodegradable and carcinogenic nature associated with synthetic dyes. Natural dyes are non-toxic, non-allergic and non-carcinogenic as these are obtained from animals or vegetable matters without any chemical processing. Natural dyes are mostly used to dye natural fibers like cotton, wool and silk.

9p chauchaungayxua10 19-03-2021 10 2   Download

Study the structural, morphological and physicochemical properties of synthetic materials by modern physical and chemical methods such as XRD, FTIR, SEM, TEM, XPS, EDX, BET, TG-DTA, UV -Vis; evaluation of photochemical catalyst using visible light in the decomposition of dyes RR-195, RY-145 on synthetic materials.

27p capheviahe26 25-01-2021 42 3   Download

The NMR spectra of 15 novel quinolines containing 11 - 34 carbon atoms and bearing substituents such as hydroxyl, sunfo, chloro, bromo, amino, azo and carboxymetoxy groups were recorded in DMSO at 298 - 300 K. For seven quinolines, the 13C-NMR signals were assigned on the basis of an analyzation of the cross peaks in the HSQC and HMBC spectra.

6p tamynhan8 04-11-2020 10 1   Download

DFT calculations indicate that the decomposition reaction of nitroethyl benzoates in the presence of 1,3-dimethylimidazolium cation takes place much faster than in the case of the non-catalyzed process. Additionally, our calculations suggest one-step polar mechanism of title reactions.

8p tocectocec 25-05-2020 13 1   Download

General approaches to the analysis of complex synthetic problems, general approaches to the analysis of complex, synthetic problems,... as the main contents of the document "The logic of chemical synthesis". Invite you to consult for additional documents for the academic needs and research.

5p hdaothi8 11-11-2015 73 5   Download

Venoms from crotalid and viperid snakes contain several peptide inhibitors which regulate the proteolytic activities of their snake-venom metalloproteinases (SVMPs) in a reversible manner under physiological conditions. In this report, we describe the high-resolution crystal structures of a SVMP, TM-3, from Taiwan habu (Trimeresurus mucrosquamatus) cocrystallized with the endogenous inhibitors pyroGlu-Asn-Trp (pENW), pyroGlu-Gln-Trp (pEQW) or pyroGlu-Lys-Trp (pEKW).

10p system191 01-06-2013 29 5   Download

Division of Medicinal and Natural Products Chemistry, Department of Chemistry and Department of Chemical Engineering, University of Iowa, USA; 2Department of Autoimmunology, Statens Serum Institut, Copenhagen, Denmark Synthetic peptides based on amino-acid residues 27–38 of human serum amyloid P component represent a novel type of heparin binders as they do not contain clusters of basic amino acids or other known features associated with protein or peptide heparin binding.

8p system191 01-06-2013 53 4   Download

In addition to kallikrein hK3, a serine protease generally reported as PSA (prostate-speci®c antigen), at least two other enzymes in human seminal plasma also cleave syn-thetic peptidyl substrates derived from the sequence of human semenogelins. We have identi®ed one of these as prostatic acid phosphatase (PAP), a major component of prostatic ¯uid whose physiological function is unclear.

6p research12 29-04-2013 31 4   Download

Semi-synthetic cephalosporin antibiotics belong to the top 10 of most sold drugs, and are produced from 7-aminodes-acetoxycephalosporanic acid (7-ADCA). Recently new routes have been developed which allow for the production of adipyl-7-ADCA by a novel fermentation process. To complete the biosynthesis of 7-ADCAa highly active adipyl acylase is needed for deacylation of the adipyl derivative. Such an adipyl acylase can be generated from known glu-taryl acylases.

10p research12 23-04-2013 33 3   Download

Weak neurotoxins from snake venom are small proteins with five disulfide bonds, which have been shown to be poor bindersof nicotinicacetylcholine receptors.We report on the cloning and sequencing of four cDNAs encoding weak neurotoxins fromNaja sputatrixvenomglands. The protein encoded by one of them, Wntx-5, has been synthesized by solid-phase synthesis and characterized.

10p research12 23-04-2013 43 4   Download

The serotype a-specific polysaccharide antigen ofActinoba-cillus actinomycetemcomitansis an unusual sugar, 6-deoxy-D-talose.Guanosinediphosphate (GDP)-6-deoxy-D-talose is the activated sugar nucleotide form of 6-deoxy-D-talose, which has been identified as a constituent of only a few microbial polysaccharides. In this paper, we identify two genes encoding GDP-6-deoxy-D-talose synthetic enzymes, GDP-a-D-mannose 4,6-dehydratase and GDP-4-keto-6-deoxy-D-mannose reductase, in the gene cluster required for the biosynthesis of serotype a-specific polysaccharide anti-gen from A.

9p tumor12 22-04-2013 31 2   Download

A new human/rat CRH analogue has been synthesized using the Fmoc/tBu solid-phase synthetic protocol. The sequence ofthe new peptide differs from the original in two positions, 12 and 15, at which the native amino acids L-phenylalanine 12 and L-leucine 15 have been replaced by the nonprotein amino acids D-phenylalanine and a-aminoisobutyric acid (Aib), respectively. The high resolution three-dimensional solution structure of [D-Phe12, Aib15]CRH has been determined by 688 dis-tance constraints (656 meaningful NOE and 32 H-bonds distance limits) and 21 angle constraints. ...

11p tumor12 22-04-2013 34 3   Download

Pi4 is a38-residue toxincross-linkedby fourdisulfidebridges that has been isolated from the venom of the Chactidae scorpion Pandinus imperator. Together with maurotoxin, Pi1, Pi7 andHsTx1, Pi4belongs to theaKTX6 subfamilyof short four-disulfide-bridged scorpion toxins acting on K + channels. Due to its very low abundance in venom, Pi4 was chemically synthesized in order to better characterize its pharmacology and structural properties.

10p tumor12 20-04-2013 31 1   Download

We have studied the interaction ofb-17, a potent synthetic antimicrobialb-peptide, with phospholipids. We find that unlikeother antimicrobial peptides suchasmagainin II,b-17 facilitates the formation of nonbilayer phases, indicating that the peptide promotes negative curvature. Studies of liposomal leakage also indicate a different mode of mem-brane interaction relative to magainin II, but both leakage andmembrane binding showthatb-17, likemagainin II, has strongaffinity formembranes containinganionic lipids....

9p tumor12 20-04-2013 47 2   Download

A large number of bioactive peptides have been isolated from amphibian skin secretions. These peptides have a variety of actions including antibiotic and anticancer acti-vities and the inhibition of neuronal nitric oxide synthase. We have investigated the structure–activity relationship of citropin 1.1, a broad-spectrum antibiotic and anticancer agent that also causes inhibition of neuronal nitric oxide synthase, by making a number of synthetically modified analogues.

13p tumor12 20-04-2013 37 3   Download

We report here the isolation of three isoforms of a novel C-terminally amidated peptide from the gills of red sea bream, Chrysophrys (Pagrus) major. Peptide sequences were determined by a combination of Edman degrada-tion, MS and HPLC analysis of native and synthetic peptides. Three peptides, named chrysophsin-1, chryso-phsin-2, and chrysophsin-3, consist of 25, 25, and 20 amino acids, respectively, and are highly cationic, con-taining an unusual C-terminal RRRH sequence.

12p tumor12 20-04-2013 44 3   Download