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21.
Heider Nasser ákos Rédey Tatiana Yuzhakova Zsolt Németh Tóth Tamás Ollár 《Reaction Kinetics and Catalysis Letters》2007,92(2):329-335
CO adsorption at low temperature has been used to probe Lewis acid sites created upon dehydroxylation of γ-Al2O3 and reduction of Mo/Al2O3 catalysts, using Fourier Transform Infrared spectroscopy (FTIR).
Carbon-monoxide adsorption on γ-Al2O3 and Mo/Al2O3 catalysts dehydroxylated and reduced at different temperatures was studied at 78 K by IR spectroscopy. However, our results
indicate that there is an approximately linear correlation between the increase either of dehydroxylation or the extent of
reduction of the catalysts and the increasing absorbance of CO due to CO adsorption on Lewis acid sites created upon dehydroxylation
of γ-Al2O3 and reduction of Mo/Al2O3. 相似文献
22.
The regio- and stereoselective addition of chlorosulfonyl isocyanate to (+)-3-carene 1 resulted in β-lactam 2, which was converted to N-Boc-β-amino acid 4, β-amino ester 7, and carboxamide derivatives 18 and 20 via N-Boc activation and mild ring opening. The corresponding β-amino ester 7 was transformed to 2-thioxopyrimidin-4-one 11 and 2,4-pyrimidinedione 13. LAH reduction of 5 and 7 resulted in amino alcohols 6 and 8. The reaction of 8 with phenyl isothiocyanate, followed by cyclisation, furnished 1,3-oxazine 15. 相似文献
23.
Our goal is to identify the type and number of static equilibrium points of solids arising from fine, equidistant n-discretizations of smooth, convex surfaces. We assume uniform gravity and a frictionless, horizontal, planar support. We show that as n approaches infinity these numbers fluctuate around specific values which we call the imaginary equilibrium indices associated with the approximated smooth surface. We derive simple formulae for these numbers in terms of the principal curvatures and the radial distances of the equilibrium points of the solid from its center of gravity. Our results are illustrated on a discretized ellipsoid and match well the observations on natural pebble surfaces. 相似文献
24.
Dr. Giuseppe Ferrauto Dr. Daniela Delli Castelli Dr. Loredana Leone Prof. Mauro Botta Prof. Silvio Aime Dr. Zsolt Baranyai Prof. Lorenzo Tei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(16):4184-4193
The new ligand HPDO3MA [(R,R,R,R)-10-(2-hydroxypropyl)-α,α′,α′′-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid] was designed to combine and optimize the chemical properties of the macrocyclic ligands HPDO3A and DOTMA. The presence of the methyl groups on the acetic pendant arms of HPDO3A is expected to rigidify the structure of the ligand and favor an increase of the kinetic inertness of the Ln complexes. 1H NMR spectra of Eu(HPDO3MA) displayed the presence of two pairs of diastereoisomers: SAP (square antiprismatic) and TSAP (twisted square antiprismatic) isomers (56 and 44 %, respectively). In addition, 1H and 17O relaxometric NMR studies of Gd(HPDO3MA) showed approximately a 10 % increase in relaxivity and a faster water exchange rate with respect to Gd(HPDO3A). Moreover, a detailed chemical exchange saturation transfer (CEST) characterization of Yb(HPDO3MA) displayed a sensitivity about two times larger than that of Yb(HPDO3A) both in phantom and in cell labeling experiments. Finally, the kinetic inertness of Yb(HPDO3MA) was measured to be twice as high as that of Yb(HPDO3A), with a dissociation half-life at physiological pH of about 2500 years. 相似文献
25.
26.
An ordinary differential equation perturbed by a null-recurrent diffusion will be considered in the case where the averaging type perturbation is strong only when a fast motion is close to the origin. The normal deviations of these solutions from the averaged motion are studied, and a central limit type theorem is proved. The limit process satisfies a linear equation driven by a Brownian motion time changed by the local time of the fast motion. 相似文献
27.
A new, continuous-flow consecutive reduction method was developed for the C-N bond formation in the synthesis of the key intermediate of the antipsychotic drug cariprazine. The two-step procedure consists of a DIBAL-H mediated selective ester reduction conducted in a novel, miniature alternating diameter reactor, followed by reductive amination using catalytic hydrogenation on 5% Pt/C. The connection of the optimized modules was accomplished using an at-line extraction to prevent precipitation of the aluminum salt byproducts. 相似文献
28.
29.
Stieghorst Christian Hampel Gabriele Karches Barbara Krenckel Patricia Kudějová Petra Plonka Christian Révay Zsolt Riepe Stephan Welter Katharina Wiehl Norbert 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(1):307-313
Journal of Radioanalytical and Nuclear Chemistry - For the optimization of the manufacturing process of multicrystalline silicon (mc-Si) for solar cells in order to reduce energy consumption and... 相似文献
30.
Abstract Polystyrene-polyisobutylene-polystyrene triblock copolymer thermoplastic elastomers have been synthesized by living carbocationic sequential copolymerization using the tert-butyl dicumyl chloride/TiCl4/methylcyclohexane:methyl chloride (60:40 v:v)/ ?80°C system in the presence of the proton trap 2,6-di-tert-butylpyridine. Structure-property relationships have been examined by varying the Mn of the PIB middle block (39,000 to 156,000) and that of the PSt end-segment (1,000 to 19,000). The tensile strength is controlled by the molecular weight of the PSt segment and independent of the PIB middle block length in the studied range. Phase separation starts when the Mn of the PSt segment reaches ~ 5,000, and it is complete when the Mn reaches ~ 15,000. These triblocks exhibited 23-25 MPa tensile strength, similar to that of styrenic thermoplastic elastomers obtained by anionic polymerization. 相似文献