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Process for producing stereospecific polymers - Patent 5807800   (Site not responding. Last check: 2007-10-08) Stereospecific catalysts and processes for the stereotactic polymerization of ethylenically unsaturated monomers, specifically C.sub.3 -C.sub.4 alpha olefins involving a molecular sieve supported metallocene catalyst comprising a stereospecific metallocene catalyst component and a co-catalyst component. Stereospecific propagation may be applied in the polymerization of ethylenically unsaturated monomers such as C.sub.3 + alpha olefins, 1-dienes such as 1,3-butadiene, substituted vinyl compounds such as vinyl aromatics, e.g., styrene or vinyl chloride, vinyl chloride, vinyl ethers such as alkyl vinyl ethers, e.g., isobutyl vinyl ether, or even aryl vinyl ethers. The preferred application of the present invention is in the stereospecific propagation of C.sub.3 -C.sub.4 alpha olefins, particularly the polymerization of propylene to produce syndiotactic polypropylene. www.freepatentsonline.com /5807800.html   (7788 words)

Literature Survey - Stereospecific analysis of triacyl-sn-glycerols Christie,W.W. and Hunter,M.L. Stereospecific distribution of palmitic acid in the triacylglycerols of rat adipocytes. Damiani,P., Cossignani,L., Simonetti,M.S., Campisi,B., Favretto,L. and Favretto,L.G. Stereospecific analysis of the triacylglycerol fraction and linear discriminant analysis in a climatic differentiation of Umbrian extra-virgin olive oils. Pan,W.P. and Hammond,E.G. Stereospecific analysis of TG of Glycine max, Glycine soya, Avena sativa and Avena sterilis strains. www.lipidlibrary.co.uk /lit_surv/general/stereotg.htm   (1810 words)

Static and dynamic x-ray diffraction recordings from living mammalian and amphibian skeletal muscles Biophysical ... Stereospecific (rigorlike) actomyosin species were not significantly populated in either muscle, as was evidenced by the 6th actin layer line (ALL), which was substantially enhanced but without a shift in its peak position or a concomitant rise of lower order ALL's. Their quick rise after the onset of stimulation indicates that this stereospecific complex is generated in the process of normal contraction. Here the stereospecific interaction refers to a fashion of protein-protein interaction in which the spatial relation among the constituent proteins or subunits is defined by the three-dimensional complementarity of numerous contacts (numerous van der Waals contacts and fewer hydrogen bonds and salt bridges) (e.g., Perutz et al., 1968). www.findarticles.com /p/articles/mi_qa3938/is_200310/ai_n9335761   (1122 words)

Stereospecific Pharmacokinetics and Pharmacodynamics of Beta-Adrenergic Blockers in Humans This stereoselectivity was suggested to be due to a stereoselective first pass metabolism in favor of the R (+)-enantiomer (46), as reflected in a slightly higher oral clearance of this enantiomer (Table 3). Stereospecific pharmacokinetics of some beta blockers in humans after single oral doses of the racemates. Stereospecific pharmacokinetics (mean ± SD) of propranolol in humans after single or multiple oral doses of the racemate (±) or pure enantiomers (— or +) www.ualberta.ca /~csps/JPPS4(2)/R.Mehvar/betablockers.htm   (2615 words)

Stereospecific analysis of triacylglycerols Position 2 is of course distinctive in that it is a secondary hydroxyl group, but it is not always recognised that the two primary positions are different stereochemically since there is a centre of asymmetry. These methods have been used to determine the structures of many natural triacyl-sn-glycerols, and some surprisingly asymmetric fats have been found, with first prize going to milk fat in which all the short-chain fatty acids (butyric and hexanoic acids) are concentrated in position sn-3 with none in position sn-1 or 2. In the last year or so, two alternative approaches to stereospecific analysis have been described that use simple chemical degradative and derivatization steps and the methodology of chiral chromatography described in a previous article [1]. www.lipidlibrary.co.uk /topics/stereotg/index.htm   (1351 words)

Stereospecific synthesis and optical resolution of Norpseudoephedrine - [www.rhodium.ws] Stereospecific synthesis of the racemic threo isomers of 2-nitro-1-phenylpropanols by reacting a benzaldehyde derivative with nitroalkane in the presence of a tertiary amine and reducing 2-nitro-1-phenylpropanols with, for example, lithium aluminum hydride to 2-amino-1-phenylpropanols is described. Also described are phase transfer resolution of racemic mixtures of 2-amino-1-phenylpropanol and its derivatives into their optically pure isomers by reacting a racemic mixture with the mono alkali metal salt of a tartaric acid ester in a two phase system of a hydrocarbon and water. As a result, heretofore, the only practical stereospecific synthesis of 2-amino-1-phenylpropanols involves the reduction of propiophenone derivatives to the racemic erythro diastereoisomers and fractional crystallization of the amine salt of an optically active acid. www.erowid.org /archive/rhodium/chemistry/norpseudoephedrine.html   (1379 words)

Iron complexes for bleach activation and stereospecific oxidation - Patent 5850086   (Site not responding. Last check: 2007-10-08) The Fe-complex of claim 1 which is capable of stereospecifically oxidizing an organic substrate in the presence of a peroxy compound or precursor thereof. The composition of claim 15 wherein the peroxy compound or precursor thereof is selected from the group consisting of dioxygen, hydrogen peroxide, hydrogen peroxide-liberating or -generating compounds, peroxyacids and their salts, peroxyacid precursors, and mixtures thereof. The stereospecific functionalization of aliphatic C--H bonds is important in chemistry and biochemistry for drug synthesis, perfume synthesis, etc. Such transformations have been carried out by organic peroxides in a stoichiometric fashion using oxidants such as (CF.sub.3).sub.2 -dioxirane, p-NO.sub.2 -perbenzoic acid, and perfluorodialkyloxaziridines, on substrates such as 1,2-dimethylcyclohexane and decalin. www.freepatentsonline.com /5850086.html   (7450 words)

synth2 Stereospecific Synthesis of (Z) - Tamoxifen via carbometalation of Alkynylsilanes. Purification of the crude product was achieved via it's hydrochloride salt (via a reaction with HCl (g)) then F was regenerated by treatment with dilute base this produced the stereospecific (Z)- Trans isomer in an overall yield of 60%. The key step which developed the stereospecific nature of the final product was included early in the synthesis. www.ch.ic.ac.uk /local/projects/h_tanner/synth2.html   (441 words)

Peptide structure - Stereospecific assignments and angle restraints It is important to obtain stereospecific assignments, because the use of pseudoatoms always entails a loss of NOE information as detailed in the previous section. Stereospecifically assigned methylene hydrogens need to have their numbers replaced by R or S, whichever is appropriate. It may be possible to deduce the assignments manually from NOE and J coupling data alone, or it may be possible to analyze the situation in the context of preliminary structures and update the.rstrnt and. www.oci.unizh.ch /group.pages/robinson/felixman/habas.html   (1125 words)

The Yamamoto Group - The University of Chicago Modification of the Wittig reaction to permit the stereospecific synthesis of certain trisubstituted olefins. A highly stereospecific isomerization of oxiranes into allylic alcohols by means of organoaluminum amides, A. Yasuda, H. Yamamoto, H. Nozaki, Bull. Regioselective and stereospecific synthesis of β, γ-unsaturated carboxylic acids using allylbariums,A. Yanagisawa, K. Yasue, H. Yamamoto, Synlett, 593 (1992). yamamotogroup.uchicago.edu /work.html   (9185 words)

Stereospecific and nonstereospecific effects of (+)- and (-)-morphine: evidence for a new class of receptors? -- ... Stereospecific and nonstereospecific effects of (+)- and (-)-morphine: evidence for a new class of receptors? The unnatural (+) enantiomer of morphine had minimal activity in three opiate assays in vitro: the rat brain homogenate binding assay, the electrically stimulated guinea pig ileum assay, and the inhibition of adenylate cyclase in neuroblastoma X glioma hybrid cell homogenates. These observations suggest that there are at least two classes of receptors, one stereospecific and blocked by naloxone and the other only weakly stereospecific and not blocked by naloxone, and that precipitated abstinence may be due, in part, to a selective blockade of receptors of the former class but not of the latter. www.sciencemag.org /cgi/content/abstract/198/4319/842   (440 words)

A stereospecific cyclization catalyzed by an antibody -- Napper et al. 237 (4818): 1041 -- Science A stereospecific cyclization catalyzed by an antibody -- Napper et al. A monoclonal antibody elicited by a transition-state analog that is representative of an intramolecular six-membered ring cyclization reaction acted as a stereospecific, enzyme-like catalyst for the appropriate substrate. Formation of a single enantiomer of a delta-lactone from the corresponding racemic delta-hydroxyester was accelerated by the antibody by about a factor of 170, which permitted isolation of the lactone in an enantiomeric excess of about 94 percent. www.sciencemag.org /cgi/content/abstract/237/4818/1041   (410 words)

ARS | Publication request: GOSSYPOL PATHWAY IN COTTON: STEREOSPECIFIC BIOSYNTHESIS OF (+)-GOSSYPOL IN MOCO COTTON Our present objective is to elucidate the biochemical process governing the stereospecific coupling of hemigossypol for the formation (+)-gossypol in moco cotton, which involves currently poorly understood stereospecific coupling of high energy free radicals. One involves a stereospecific oxidase, which generates hemigossypol free radical as well as steers the stereospecific coupling of the free radicals. We have demonstrated that this second mechanism is responsible for the (+)-gossypol formation in moco cotton. www.ars.usda.gov /research/publications/Publications.htm?seq_no_115=176726&pf=1   (464 words)

Stereospecific Activation of Cardiac ATP-Sensitive K+ Channels by Epoxyeicosatrienoic Acids: A Structural Determinant ... A, action potentials were elicited from a single ventricular myocyte at 37°C using current clamp techniques with 5 mM ATP in the pipette. Kang JX and Leaf A (2000) Prevention of fatal cardiac arrhythmias by polyunsaturated fatty acids. Katoh T, Takahashi K, Capdevila J, Karara A, Falck JR, Jacobson HR and Badr KF (1991) Glomerular stereospecific synthesis and hemodynamic actions of 8,9-epoxyeicosatrienoic acid in rat kidney. molpharm.aspetjournals.org /cgi/content/full/62/5/1076   (4089 words)

Sequence-Specific and/or Stereospecific Constraints of the U3 Enhancer Elements of MCF 247-W Are Important for ... Sequence-Specific and/or Stereospecific Constraints of the U3 Enhancer Elements of MCF 247-W Are Important for Pathogenicity -- DiFronzo and Holland 73 (1): 234 -- The Journal of Virology Sequence-Specific and/or Stereospecific Constraints of the U3 Enhancer Elements of MCF 247-W Are Important for Pathogenicity It is possible that the number of enhancers, or the novel junction sequence, affects the ability of these MCF viruses to replicate jvi.asm.org /cgi/content/full/73/1/234   (5617 words)

Stereospecific analysis of triglycerides: an alternative method -- Brockerhoff 8 (3): 167 -- Journal of Lipid Research Stereospecific analysis of triglycerides: an alternative method -- Brockerhoff 8 (3): 167 -- Journal of Lipid Research A new method for the stereospecific analysis of triglycerides Supplementary key words stereospecific analysis • triglycerides • 1,3-diglyceride • www.jlr.org /cgi/content/abstract/8/3/167   (187 words)

JCE 2006 (83) 1055 [Jul] Stereospecific Synthesis of the Geometrical Isomers of a Natural Product Stereospecific Synthesis of the Geometrical Isomers of a Natural Product Stereospecific synthesis of a geometrical isomer is not a common topic for the introductory organic chemistry laboratory. We have developed and tested an experiment for the synthesis of (Z) and (E) isomers that has been performed successfully by undergraduate students. jchemed.chem.wisc.edu /Journal/Issues/2006/Jul/abs1055.html   (373 words)

Static and Dynamic X-Ray Diffraction Recordings from Living Mammalian and Amphibian Skeletal Muscles -- Iwamoto et al. ... heads bound in a stereospecific manner is consistent with the Muscle force is generated by myosin heads stereospecifically attached to actin. X-ray diffraction evidence for the lack of stereospecific protein interactions in highly activated actomyosin complex. www.biophysj.org /cgi/content/full/85/4/2492   (7420 words)

St to Sy and sigma According to this definition, a stereospecific process is necessarily stereoselective but not all stereoselective processes are stereospecific. For example the exclusive formation of trans-1,2-dibromocyclohexane upon bromination of cyclohexene is a stereospecific process, although the analogous reaction with (E)-cyclohexene has not been performed. Control of stereoselectivity of a reaction by steric hindrance towards attack of the reagent, which is directed to the less hindered face of the molecule. www.chem.qmul.ac.uk /iupac/gtpoc/StSy.html   (2239 words)

Stereospecific synthesis of amphetamines - Publication - RTI International   (Site not responding. Last check: 2007-10-08) Stereospecific synthesis of amphetamines - Publication - RTI International Wagner, J.M., McElhinny, C.J., Lewin, A.H., and Carroll, F.I. Stereospecific synthesis of amphetamines. RTI International is a trade name of Research Triangle Institute. www.rti.org /abstract.cfm?pubid=456   (90 words)

Stereospecific Analysis and Enantiomeric Disposition of 3,4-Methylenedioxymethamphetamine (Ecstasy) in Humans -- Fallon ... Stereospecific Analysis and Enantiomeric Disposition of 3,4-Methylenedioxymethamphetamine (Ecstasy) in Humans -- Fallon et al. Stereospecific Analysis and Enantiomeric Disposition of 3,4-Methylenedioxymethamphetamine (Ecstasy) in Humans Several stereospecific methods have been reported for MDMA analysis (14)(15)(16)(18)(19)(20)(21)(22), www.clinchem.org /cgi/content/full/45/7/1058   (5834 words)

Stereospecific Regulation of Tyrosine Hydroxylase and Proenkephalin Genes by Short-Chain Fatty Acids in Rat PC12 Cells ...   (Site not responding. Last check: 2007-10-08) Stereospecific Regulation of Tyrosine Hydroxylase and Proenkephalin Genes by Short-Chain Fatty Acids in Rat PC12 Cells -- MALLY et al. Stereospecific Regulation of Tyrosine Hydroxylase and Proenkephalin Genes by Short-Chain Fatty Acids in Rat PC12 Cells Copyright © 2004 by the International Pediatric Research Foundation. www.pedresearch.org /cgi/content/abstract/55/5/847   (292 words)

CYP2C44, a New Murine CYP2C That Metabolizes Arachidonic Acid to Unique Stereospecific Products -- DeLozier et al. 310 ... stereospecificity of its arachidonic acid metabolites are consistent The stereospecificity of these metabolites is unique from those Karara A, Makita K, Jacobson HR, Falck JR, Guengerich FP, DuBois RN, and Capdevila JH (1993) Molecular cloning, expression and enzymatic characterization of the rat kidney cytochrome P-450 arachidonic acid epoxygenase. jpet.aspetjournals.org /cgi/content/full/310/3/845   (5791 words)

Stereospecific deaminations...   (Site not responding. Last check: 2007-10-08) The deamination reaction and the work-up of the reaction mixture must be carried out in the dark to avoid isomerization of the trans-ethylene to the cis-isomer. The stereospecific course of the reaction suggests a concerted mechanism for the deamination. The authors thank the donors of the Petroleum Research Fund administered by the American Chemical Society for partial support of this work. www.mbari.org /staff/etp3/peerart/stereo.html   (93 words)

STNews Mar/Apr 00 - Ask REGgie   (Site not responding. Last check: 2007-10-08) A substructure search retrieves all substances containing the structure query, including all stereoisomers and all non-stereospecific substances. With StereoSearch, you can create and search your stereospecific structure and locate only the isomers you want in the broad answer set you have already created. Use the answer set from the search of the flat structure as the subset definition. www.cas.org /STNEWS/MARAPR00/askreg.html   (217 words)

Different Pathways of Cell Killing by Gossypol Enantiomers -- Qiu et al. 227 (6): 398 -- Experimental Biology and ... It showed stereospecific resistance to killing by (-) gossypol Racemic gossypol is a polyphenolic constituent of cotton seed Shelley MD, Hartley L, Fish RG, Groundwater P, Morgan JJ, Mort D, Mason M, Evans A. Stereospecific cytotoxic effects of gossypol enantiomers and gossypolone in tumour cell lines. www.ebmonline.org /cgi/content/full/227/6/398   (1959 words)

Transcriptional Scaffold: CIITA Interacts with NF-Y, RFX, and CREB To Cause Stereospecific Regulation of the Class II ... Transcriptional Scaffold: CIITA Interacts with NF-Y, RFX, and CREB To Cause Stereospecific Regulation of the Class II Major Histocompatibility Complex Promoter -- Zhu et al. Transcriptional Scaffold: CIITA Interacts with NF-Y, RFX, and CREB To Cause Stereospecific Regulation of the Class II Major Histocompatibility Complex Promoter Stereospecific alignment of the X and Y elements is required for major histocompatibility complex class II DRA promoter function. mcb.asm.org /cgi/content/full/20/16/6051   (8372 words)

Estrogen Receptor Residues Required for Stereospecific Ligand Recognition and Activation -- Bocchinfuso and Korach 11 ... Estrogen Receptor Residues Required for Stereospecific Ligand Recognition and Activation -- Bocchinfuso and Korach 11 (5): 587 -- Molecular Endocrinology Estrogen Receptor Residues Required for Stereospecific Ligand Recognition and Activation H528G mER displayed a gross change in stereospecific ligand mend.endojournals.org /cgi/content/abstract/11/5/587   (501 words)

Dow SE BR-1202D Stereospecific high cis-1,4 Polybutadiene (BR) Dow SE BR-1202D Stereospecific high cis-1,4 Polybutadiene (BR) SE BR-1202D is manufactured by a solution process using cobalt catalyst which produces polymers with a very light color and low level of impurities. The contents of this web site, the MatWeb logo, and "MatWeb" are Copyright 1996-2006 by Automation Creations, Inc. MatWeb is intended for personal, non-commercial use. The contents, results, and technical data from this site may not be reproduced either electronically, photographically or substantively without permission from Automation Creations, Inc. www.matweb.com /search/SpecificMaterialText.asp?bassnum=PDOW1096   (231 words)

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