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91.
B. Lorenz R. Kirmse M. Findeisen K. Schmidt 《Isotopes in environmental and health studies》2013,49(1):125-130
Abstract The reaction of 2-pyridine carboxylic acid (Hpic) with (n-Bu4N)[TcNCl4] and (n-Bu4N)[TcOCl4] in ethanol and methanol, respectively, yields the dinuclear μ-oxo complex [(pic)2NTc-O-TcN(pic)(Hpic)Cl] and the monomeric complex [TcO(pic)2Cl]. Visible and infrared spectroscopy, ESR, 1H-NMR and 99Tc-NMR have been used to characterize the new compounds. The most important field of application for the new compounds synthesized is radiodiagnostics. 相似文献
92.
93.
Gary Shambat Albert Deberardinis Petra Reinke Lin Pu John Bean 《Applied Surface Science》2009,255(20):8533-8538
Studies were performed to determine the chemical addition of a metal complex molecule, chlorotris(triphenylphosphine)iridium(I), on hydrogen passivated Si(1 1 1) surfaces to form a self-assembled monolayer (SAM). The iridium complex was synthesized prior to chemical addition, for which modified reaction conditions were chosen. Following addition, the silicon surfaces were characterized with X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The XPS results revealed that the surfaces consisted of the expected elemental percentages and that the iridium has a slightly higher success rate at attaching to oxide-free surfaces. XPS data also strongly indicate that the iridium complex remained intact upon chemisorption and did not decompose during the addition reaction. CV data show a difference between iridium treated surfaces and control samples. Hydrogen passivated wafers with iridium complex were much more conductive than those which were terminated with just an oxide or with an oxide and iridium complex. Furthermore, no free iridium reagent was detected as an additional feature in the current profile, indicating there was no physisorbed layer. 相似文献
94.
Dr. Ruth Hielscher Prof. Dr. Thorsten Friedrich Prof. Dr. Petra Hellwig 《Chemphyschem》2011,12(1):217-224
The catalytic activity of the respiratory NADH:ubiquinone oxidoreductase (complex I) is based on conformational reorganizations. Herein we probe the effect of substrates on the conformational flexibility of complex I by means of 1H/2H exchange kinetics at the level of the amide proton in the mid‐infrared spectral range (1700–1500 cm?1). Slow, medium, and fast exchanging domains are distinguished that reveal different accessibilities to the solvent. Whereas amide hydrogens undergo rapid exchange with the solvent in an open structure, hydrogens experience much slower exchange when they are involved in H‐bonded structures or when they are sterically inaccessible for the solvent. The results indicate a structure that is more open in the presence of both NADH and quinon. Complementary information on the overall internal hydrogen bonding of the protein was probed in the far infrared (300–30 cm?1), a spectral range that includes a continuum mode of the hydrogen bonding signature. 相似文献
95.
Vera A. Schulte Dora F. Alves Paul P. Dalton Martin Moeller Marga C. Lensen Petra Mela 《Macromolecular bioscience》2013,13(5):562-572
Designing three‐dimensional (3D) scaffolds for selective manipulation of cell growth is of high relevance for applications in regenerative medicine. Especially, scaffolds with oriented morphologies bear high potential to guide the restoration of specific tissues. The fabrication of hydrogel scaffolds that support long‐term survival, proliferation, and unidirectional growth of embedded cells is presented here. Parallel channel structures are introduced into the bulk hydrogels by uniaxial freezing, providing stable, and uniform porosity suitable for cell invasion (pore diameters of 5–15 µm). In vitro assessment of the scaffolds with murine fibroblasts (NIH L929) shows a remarkable unidirectional movement along the channels, with the cells traveling several millimeters through the hydrogel.
96.
Michaela Mačková Michal Himl Jan Budka Michaela Pojarová Ivana Císařová Václav Eigner Petra Cuřínová Hana Dvořáková Pavel Lhoták 《Tetrahedron》2013,69(4):1397-1402
Methylation of 5,11,17,23-tetranitrothiacalix[4]arene with diazomethane leads to the tetramethoxy derivative, which was studied using single-crystal X-ray crystallography. It revealed that this compound, albeit in the 1,3-alternate conformation, can form the inclusion complexes with various solvent molecules possessing acidic methyl groups (ethyl acetate, nitromethane, acetone, acetonitrile) and creates interesting infinite channels filled with solvent molecules. The subsequent transformation of nitro groups into the ureido moieties gave receptors capable of anion recognition even in a highly HB-competitive solvent like DMSO. 相似文献
97.
98.
Parakkulam Ramaswamy Aravind Lorenz Ratke Matthias Kolbe Gian Domenico Soraru 《Journal of Sol-Gel Science and Technology》2013,67(3):592-600
In present work, we have prepared gels with various compositions of methyltrimethoxysilane—3-(2,3-epoxypropoxy) propyltrimethoxysilane (MTMS-GPTMS) using a two-step acid base sol–gel process. To make a comparative study between the two common drying routes, we prepared gels under supercritical and also under ambient conditions. The density of the supercritically dried hybrid aerogels lies between 0.18 and 0.31 gcm?3, while the density of the ambient dried ones ranges between 0.35 and 0.42 gcm?3. The surface area of MTMS-0.25 GPTMS aerogel dried under supercritical conditions, has been found to be 464 m2 g?1 with a pore volume and average pore diameter of 1.24 cm3 g?1 and 11 nm respectively. The same composition dried under ambient conditions is found to have similar properties i.e. a BET surface area of 439 m2 g?1, pore volume of 1.22 cm3 g?1 and average pore diameter of 11 nm. The aerogels were later pyrolyzed yielding silica/carbon composite aerogels. The pyrolized aerogels possessed a surface area as high as 207 m2 g?1 with a total pore volume of 0.98 cm3 g?1. The pyrolysed aerogels were also calcined to yield carbon free materials. 相似文献
99.
100.
Natallia Torapava Henrik Ramebäck Enzo Curti Petra Lagerkvist Christian Ekberg 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):545-553
In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm?3 sodium sulfate solution using 223Ra and 133Ba tracers at very low total radium concentration, i.e. less than 10?13 mol dm?3. It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of 223Ra and 133Ba in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate—a mineral present in the deep underground repository. 相似文献