Search results for "structures"
showing 10 items of 4815 documents
Tenascin in denervated human muscle
1996
Tenascin is a large oligomeric glycoprotein of the extracellular matrix. Its location is limited in innervated muscle tissues. We investigated immunohistologically, using two monoclonal antibodies (mab) against Tenascin, biopsied denervated human muscle of children and adults. Tenascin was present in the interstitial space among denervated muscle fibres. Accumulation of Tenascin in denervated adult muscle tissue was frequent, accumulation in denervated muscle tissue of children was sparse and weak. The two antibodies reacted correspondingly. Tenascin was not only found in the vicinity of atrophic muscle fibres, but also close to normally sized fibres, suggesting an early stage of denervatio…
Functionalization of aliphatic polyesters by nitroxide radical coupling
2014
Functionalized poly(butylene succinate) (PBS) samples were prepared by a post-polymerization method based on the coupling reaction between TEMPO derivatives bearing different functionalities and PBS macroradicals generated by H-abstraction using a peroxide. 4-Benzoyloxy-2,2,6,6-tetramethylpiperidine-1- oxyl (BzO-TEMPO) and 4-(1-naphthoate)-2,2,6,6-tetramethylpiperidine-1-oxyl (NfO-TEMPO), a pro-fluorescent nitroxide, were successfully grafted on PBS, as revealed by MALDI TOF MS and UV-Vis spectroscopy. The functionalization degrees were accurately determined by UV-Vis analysis and confirmed by 1H-NMR spectroscopy. The grafting site was identified by combining theoretical calculations with e…
Spectroscopic and structural characterization of pure and FeCl3-containing tri-n-butyl phosphate
2014
The spectroscopic properties and liquid structure of pure tri-n-butyl phosphate (TBP) and FeCl3/TBP solutions have been investigated by Uv–Vis and Raman spectroscopies, X-ray diffraction and conductometry. Uv–Vis and Raman spectra, supported by conductometric measurements, consistently indicate that the solubilized salt is present mostly as TBP n [FeCl3 − n ] n+ and FeCl4 − complex ions due to specific interaction with the TBP phosphate group. Thanks to this interaction, a high amount of salt (up to 13 % w/w) can be dissolved despite the relatively low dielectric constant of TBP. The X-ray diffractogram of pure TBP has been interpreted in terms of three main contributions which can be attri…
Manganese(III)-mediated oxidative carbon-carbon bond cleavage of the 1,10-phenanthroline-5,6-dione ligand
1999
[EN] A new manganese(III)-1,10-phenanthroline-5,6-dione (phendione) complex possessing a putative Mn-2(mu-O) (mu-O2CMe)(2) core has been found to undergo a Ligand-based oxidative cleavage of the C(5)-C(6) bond in weak acid aqueous MeOH under aerobic conditions at room temperature to yield 2,2'-bipyridyl-3,3'-dicarboxylate with co-reduction to the corresponding Mn-II-phendione species.
Racemic and Optically Pure Heptahelicene-2-carboxylic Acid: Its Synthesis and Self-Assembly into Nanowire-Like Aggregates
2010
Heptahelicene-2-carboxylic acid was effectively synthesised from suitably functionalised naphthalene building blocks. Methoxy-substituted 1,1'-ethyne-1,2-diylbis(2-but-3-yn-1-ylnaphthalene) was cyclised in the presence of CpCo(CO)(2)/PPh(3) to 2-methoxy-7,8,11,12-tetrahydroheptahelicene, which was converted into heptahelicen-2-yl trifluoromethanesulfonate. This reactive intermediate underwent Pd(OAc)(2)/dppp-catalysed methoxycarbonylation reaction to provide, after hydrolysis, heptahelicene-2-carboxylic acid. The racemate was resolved into enantiomers by semipreparative HPLC on a chiral column. The helicity of (+)-(P)-heptahelicene-2-carboxylic acid was assigned by correlating its CD spectr…
B-DNA Structure and Stability as Function of Nucleic Acid Composition. Dispersion-Corrected DFT Study of Dinucleoside-Monophosphate Single and Double…
2013
actions of the sugar-phosphate skeleton with water; (6) hydrophobic interactions of the DNA cylindrical core, made up by the hydrogen-bonded and stacked nitrogen bases, with the water solvent. Recently, there has been increasing effort in developing and applying quantum chemical methods able to reproduce the structure of native B-DNA and to correctly describe the energy involved in the intrastrand and interstrand noncovalent interactions between the nucleotide monomers. This topic has been approached by both wave function methods and density functional theory. [2] Water solvent and sodium counterions also play an important role in the formation and relative stabilization of the double-helic…
Eye Cataract Simulation Using Polymer Dispersed Liquid Crystal Scattering Obstacles
2004
Polymer dispersed liquid crystals with electrically induced variations of light scattering extent similar to that of transparent PLZT ceramics are used for simulation of different development stages of eye cataract. Wavelength dependencies of scattering are determined in the visible spectral range, and human visual response looking through the scattering obstacle to the onset of various spatial frequency stimuli is determined psychophysically and electrophysiologically in order to find correlation between the scattering extent, visual acuity and visual evoked potential VEP chromatic characteristics.
Interaction of Dimethyltin(IV)2+ Cation with Gly-Gly, Gly-His, and Some Related Ligands. A New Case of a Metal Ion Able To Promote Peptide Nitrogen D…
1999
Equilibrium (pH-metric) and spectroscopic (1H,13C, and 119Sn NMR and 119Sn Mossbauer) studies were performed to characterize the interaction of the dimethyltin(IV) cation with glycine, glycyl-glycine (Gly-Gly), imidazole-4-acetic acid, histamine, histidine, glycyl-histamine, glycyl-histidine (Gly-His), and β-alanyl-histidine (carnosine). For histamine and glycyl-histamine (having only nitrogen donor atoms) no complex formation was detected. The hydrolyzed species of the dimethyltin(IV) cation are always dominant over the complexes formed with the other ligands, except with Gly-Gly and Gly-His. For these two ligands, {COO-,N-,NH2} coordinated complexes are dominant in the neutral pH range wi…
ChemInform Abstract: Convenient High Yielding Gram Scale Solution Synthesis of Methionine-Enkephalin.
2010
A simple, large-scale synthesis of a cytokine, methionine-enkephalin, Tyr-Gly-Gly-Phe-Met, has been elaborated. Classical solution peptide chemistry methods without protection of amino acid side-chain functions and 1+(2+2) segment condensation were used. A nine-step synthesis from commercial amino acid derivatives was developed with yields ranging from 86% to 99%, averaging 92%. The purity of all intermediates was found to be 99.0-100% by HPLC. The process has been used to prepare greater than 150 g quantities of the pentapeptide as a monohydrate of 100% purity. Hydantoin formation was observed during saponification of Boc-Tyr-Gly-Gly-Phe-Met-OMe and minimised.
ChemInform Abstract: Oligosaccharide Synthesis via Electrophile-Induced Activation of Glycosyl-N-allylcarbamates.
2010
Abstract Glycosyl-N-allyl carbamates, obtained by reaction of anomerically unprotected saccharides with allyl isocyanate, can be activated by an electrophile-induced cyclisation and reacted with glycosyl acceptors to form the corresponding oligosaccharides By this method the mucin core 2 trisaccharide2 has successfully been synthesized. Due to the mild glycosylation conditions even 1-O-acetyl protected glycosyl acceptors can be used. This was demonstrated in the synthesis of a 1,6-linked glucosyl trisaccharide whereby a reptitious glycosylation strategy could be applied. 1. Dedicated to the memory of Professor Akira Hasegawa.