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51.
Michaela Kohlov Susana Rocha Clia Gomes Amorim Alberto de Nova Araújo Alice Santos‐Silva Petr Solich Maria Conceio Branco da Silva Montenegro 《Macromolecular bioscience》2020,20(7)
The reduction of free radicals by bioactive membranes used for hemodialysis treatment is an important topic due to the constant rise of oxidative stress‐associated cardiovascular mortality by hemodialysis patients. Therefore, it is urgent to find an effective solution that helps to solve this problem. Polysulfone membranes enriched with α‐lipoic acid, α‐tocopherol, and with both components are fabricated by spin coating. The antioxidant properties of these membranes are evaluated in vitro by determining the lipid‐peroxidation level and the total antioxidant status of the blood plasma. The biocompatibility is assessed by quantifying the protein adsorption, platelet adhesion, complement activation, and hemolytic effect. All types of membranes show in vitro antioxidant activity and a trend to reduce oxidative stress in vivo; the best results show membranes prepared with a combination of both compounds and prove to be nonhemolytic and hemocompatible. Moreover, the membrane specific separation ability for the main waste products is not affected by antioxidants incorporation. 相似文献
52.
Vincent K. W. Cheng Michaela Flock Michael Ramek 《International journal of quantum chemistry》1996,57(5):929-941
The potential energy surfaces of β-hydroxypropionic acid and 3-aminopropionamide have been investigated by means of RHF /4-31G calculations. Structures, reaction paths for internal rotations, and the respective energy barriers are reported. The influence of the various intramolecular interactions on structural and energetical properties is shown and compared to the results previously obtained for β-alanine. © 1996 John Wiley & Sons, Inc. 相似文献
53.
54.
Dr. Mario Leypold Lukas Schuh Prof. Roland Fischer Dr. Ana Torvisco Prof. Michaela Flock Prof. Harald Stueger Dr. Michael Haas 《Angewandte Chemie (International ed. in English)》2017,56(28):8089-8093
Herein, we report on the first sila-aldol reaction, which emphasizes the tight connection between silicon and carbon chemistry. This novel synthetic method provides straightforward access to 2-oxahexasilabicyclo[3.2.1]octan-8-ide, a structurally complex silicon framework, in quantitative yield. Its structure was confirmed by NMR spectroscopy and X-ray crystallography, and it displays a distinctive charge-transfer transition. The complete mechanism of this highly selective rearrangement cascade is outlined and supported by density functional theory (DFT) calculations, which highlight the thermodynamic driving force and the low activation barriers of this powerful silicon–carbon bond-forming strategy. 相似文献
55.
56.
Peter Sieber Bruno Kamber Bernhard Riniker Werner Rittel 《Helvetica chimica acta》1980,63(8):2358-2363
Cystine peptides are conveniently prepared from S-acetamidomethyl- or S-trityl-protected cysteine derivatives by direct oxidation with iodine. Since the reaction proceeds through the formation of sulfenyl iodides, these highly reactive groups may substitute the indole ring of tryptophan residues, resulting in the formation of 2-thioethers. During the synthesis of the peptide hormone somatostatin, we investigated this possible side reaction. By-products of the tryptophan-2-thioether type can be produced under conditions which lead to a marked retardation of the disulfide bond formation. The largest amount of these compounds were formed when the oxidation was carried out in 90% aqueous trifluoroethanol. In model peptides in which tryptophan and cysteine residues were separated by 1 to 4 glycine residues, the ring size of the resulting thioether exerted a strong influence on the yield: in peptides with 1 and 2 glycines, only dimeric disulfides were formed. Incorporation of 3 and 4 glycine residues gave thioethers in yields of about 40% and 70% respectively. Conversely, under normal conditions of iodine oxidation, when disulfides are rapidly formed from the S-acetamidomethyl- or S-tritylcysteine residues, tryptophan-2-thioethers are produced only in insignificant amounts or not at all. 相似文献
57.
58.
Bicyclo[3.1.0]hexane-2.3.4-trione and its 1.5-dimethyl derivative have been synthesized and investigated by means of photoelectron spectroscopy. 相似文献
59.
Niedermaier O Scheit H Bildstein V Boie H Fitting J von Hahn R Köck F Lauer M Pal UK Podlech H Repnow R Schwalm D Alvarez C Ames F Bollen G Emhofer S Habs D Kester O Lutter R Rudolph K Pasini M Thirolf PG Wolf BH Eberth J Gersch G Hess H Reiter P Thelen O Warr N Weisshaar D Aksouh F Van den Bergh P Van Duppen P Huyse M Ivanov O Mayet P Van de Walle J Aystö J Butler PA Cederkäll J Delahaye P Fynbo HO Fraile LM Forstner O Franchoo S Köster U Nilsson T Oinonen M Sieber T Wenander F Pantea M 《Physical review letters》2005,94(17):172501
We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion." 相似文献
60.
Berlinguette CP Dragulescu-Andrasi A Sieber A Galán-Mascarós JR Güdel HU Achim C Dunbar KR 《Journal of the American Chemical Society》2004,126(20):6222-6223
A charge-transfer-induced spin transition (CTIST) is observed in the discrete cyanide-bridged complex, {[Co(tmphen)2]3[Fe(CN)6]2}. Single-crystal X-ray diffraction, 57Fe M?ssbauer spectroscopy, and magnetic susceptibility were used collectively to describe the oxidation states of the Co and Fe ions in this cluster as a function of temperature. This pentanuclear complex represents the first example of a CTIST at the discrete molecular level. 相似文献