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951.
Martin Müller Marizel Rouilly Bruno Rusterholz Magdalena Maj-Żurawska Zhongmin Hu Wilhelm Simon 《Mikrochimica acta》1988,96(1-6):283-290
Magnesium selective ionophores are described which induce a rejection of Na+ and K+ in solvent polymeric membranes by factors of up to 6300 and 5000, respectively. Depending on the membrane composition, ion selective electrodes may be obtained with equal selectivity for Mg2+ and Ca2+ as well as sensors with a discrimination of Ca2+ by a factor up to 8. Sensors of the type described are candidates for water hardness determination as well as for an Mg2+ assay in blood by chemometric procedures.On leave from the Chemistry Department, University of Warsaw, ul. L. Pasteura 1, PL-02-093 Warsaw, PolandOn leave from the Shanghai University of Technology, 149 Yanchang Road, Shanghai, People's Republic of China 相似文献
952.
We present an implementation of the polarizable continuum model for the calculation of solvent effects on electronic circular dichroism spectra. The computational model used is density functional theory in the length-gauge formulation, and gauge-origin independence is ensured through the use of London atomic orbitals. Results of calculations carried out for methyloxirane and bicyclic ketones, camphor, norcamphor, norbornenone, and fenchone are presented, and the theoretically obtained solvent effects are compared with experimental observations. 相似文献
953.
Iwona akomska Magdalena Barwioek Edward Szyk Boenna Golankiewicz 《Transition Metal Chemistry》2007,32(1):70-73
The preparation and spectroscopic study (1H, 13C, 15NNMR, 13CP MAS NMR, IR) of new PdII complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one (6,8-DiMe-4-O-IMT) (1) and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo[1,5-a]-1,3,5-triazin-4(1H)-one (6,8-DiMe-4-O-2-S-IMT) (2) is reported. The spectroscopic data indicate a square planar geometry with two N(7) bonded heterocycles and two cis-chloride anions. The final product of the thermal decomposition of cis-PdCl2(6,8-DiMe-4-O-IMT)2
(3) is metallic Pd, whereas for cis-PdCl2(6,8-DiMe-4-O-2-S-IMT)2
(4) it is metallic Pd plus C. 相似文献
954.
An efficient silylative coupling of trisubstituted vinylsilanes with dialkoxy(vinyl)boranes is described. Under optimum conditions the reaction offers a selective route to 1-(silyl)-1-(boryl)ethenes, which are potentially attractive intermediates in organic synthesis 相似文献
955.
Enzymes may be used to develop an environmentally friendly alternative to the conventional polluting technologies in textile
finishing. The action of the unlabeled and fluorescent labeled proteolytic enzymes subtilisin and trypsin on wool was examined.
Scanning electron micrographs and a diffusion study, based on fluorescence microscopy, localized the enzymatic attack on the
fiber. A kinetic study was carried out by monitoring the amino acid content of the treatment liquor.
Enzymatic action is not confined to the fiber surface. To limit attack to the surface and reduce wool damage new treatment
methods such as enzyme immobilization onto a solid carrier must be investigated. 相似文献
956.
Magdalena Kloskowska Antoni Konitz Wiesaw Wojnowski Barbara Becker 《无机化学与普通化学杂志》2006,632(15):2424-2428
The title compound, [Sn(μ–S){SSi(OtBu)3}2]2 ( 1 ), containing four–coordinated tin(IV), crystallizes in two polymorphic modifications. The orthorhombic 1a –form has been obtained in the reaction of (tBuO)3SiSH and Et3N with SnCl2, whereas the triclinic 1b –form in the reaction with SnCl4 as substrate. The crystal and molecular structures of both polymorphs ( 1a as a redetermination) have been determined by a single–crystal X–ray diffraction study at room temperature. The title compound was shown to react with ammonia and ammonia complexes of some d–block metal cations giving products of Sn–S bond cleavage. 相似文献
957.
Silica particles containing immobilised peptidic templates have been used for the generation of hierarchically imprinted polymers. The pores of the silica mould were filled with a mixture of monomers/initiator and polymerised, followed by dissolution of the silica template. This method leaves behind imprinted polymers with binding sites located at the surface, which are capable of recognising larger molecules with the same immobilised epitope. All the products resulting from solid-phase synthesis of peptides were characterised by elemental analysis, FT-IR spectroscopy and fluorescence microscopy. The hierarchically imprinted polymers generated from these products were characterised by elemental analysis, FT-IR spectroscopy, fluorescence microscopy, scanning electron microscopy (SEM) and nitrogen adsorption, providing evidence concerning the reproducibility of each step. The chromatographic properties of the materials have been investigated and the advantages of the immobilisation method have been proven. The materials exhibit selectivity for their templates and other structurally related dipeptides. Furthermore, the polymers proved to be capable of recognising larger peptides containing the immobilised sequence. 相似文献
958.
Magdalena Maj-Żurawska Werner Buchser Daniel Ammann Dieter H. Welti Brnö Pretsch Walter Keller-Schierlein Wilhelm Simon 《Mikrochimica acta》1987,92(1-3):1-10
Lipophilic bis--diketones have been prepared by covalently linking two-diketone subunits. Potentiometric studies on liquid membrane electrode cell assemblies showed no improvement of the ion selectivities induced by the bridged systems in comparison to unbridged-diketones. The dissociation constants of the enol functions in the bis--diketones indicate that under the conditions of the EMF measurement probably only one-diketone unit is deprotonated in the liquid membrane phase. The complexation of these-diketones with Mg2+ and Ca2+ was studied by13C NMR-monitored titrations in a homogeneous organic phase.On leave from the Chemistry Department, University of Warsaw, Warsaw, Poland 相似文献
959.
Grażyna Janowska Teresa Mikołajczyk Magdalena Olejnik 《Journal of Thermal Analysis and Calorimetry》2007,88(3):843-849
The effects of basic fibre-forming parameters on the thermal properties and flammability of fibres from polyimidoamide (PIA)
nanocomposite have examined. The comparative analysis of the properties of fibres from modified PIA and PIA nanocomposite
has been conducted.
The multi-functional fibres prepared from PIA nanocomposite show increased porosity and sorption properties as well as a high
thermal stability and reduced flammability in comparison with fibres without MMT. 相似文献
960.
Nitric oxide (.NO) has a multitude of physiological roles, including the ability to protect cells against oxidant-induced killing, e.g. by inhibiting caspase-mediated apoptosis or by intercepting damaging free radicals derived from membrane lipids. The purpose of this study was to test the hypothesis that low flux .NO acting in the latter fashion can enhance tumor-cell resistance to photodynamic killing, specifically that sensitized by 5-aminolevulinic acid (ALA)-derived protoporphyrin IX (PpIX). Preliminary model experiments with iron-ascorbate-treated, PpIX-sensitized liposomes showed that spermine NONOate (SPER/NO)-derived .NO had no effect on photoinduced accumulation of primary singlet oxygen adducts, e.g. the cholesterol hydroperoxide 5 alpha-OOH, but dose-dependently inhibited the buildup of free radical-generated oxidation products arising from one-electron turnover of primary peroxides. In subsequent studies, breast tumor COH-BR1 cells in serum-free medium were treated with 1 mM ALA for 15 min and then without ALA for 3.75 h, allowing biogenerated PpIX to diffuse to extramitochondrial sites, including plasma membrane. Cells were irradiated in the absence or presence of SPER/NO and compared for peroxidative damage and Hoechst-assessed viability after 5 h in the dark. Iron-stimulated necrotic photo-killing and accumulation of chain lipid peroxidation products were observed, and this was inhibited strongly by SPER/NO, but not by decomposed SPER/NO, confirming that .NO was the active agent. When introduced after irradiation, .NO became progressively less inhibitory, consistent with ongoing but waning free-radical activity. These findings provide new insights into the possible role of .NO in tumor resistance to ALA-photodynamic therapy and other photo-dynamic treatments. 相似文献