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111.
Prof. Dr. Christian Brückner Dr. Nivedita Chaudhri Dustin E. Nevonen Dr. Sayantan Bhattacharya Arthur Graf Elizabeth Kaesmann Dr. Ruoshi Li Dr. Matthew J. Guberman-Pfeffer Prof. Dr. Tomoyasu Mani Dr. Arunpatcha Nimthong-Roldán Dr. Matthias Zeller Dr. Adrien A. P. Chauvet Prof. Dr. Victor Nemykin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(65):16189-16203
112.
The paper deals with the effect of different stress states on damage and failure behavior of ductile materials. To be able to model these effects a continuum damage model has been proposed taking into account the dependence of the stress intensity, the stress triaxiality and the Lode parameter on the constitutive equations. The model is based on the introduction of damaged and fictitious undamaged configurations. Only experiments are not adequate enough to determine all constitutive parameters. Therefore, additional three-dimensional micro-mechanical simulations of representative volume elements have been performed to get more insight in the complex damage mechanisms. These simulations cover a wide range of different void sizes, void shapes and void distributions. After all, the results from the micro-mechanical simulations are used to propose the damage equations and to identify corresponding parameters. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
113.
Blanka Wladislaw Liliana Marzorati Jonas Gruber 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):185-188
Abstract Some new norbornene thioester derivatives of endo configuration are sinthesized. Proofs are provided that thioester group has more preference for endo configuration than the ester group. 相似文献
114.
Claudio L. Donnici Elaine Henriques Teixeira Pereira Júlio C. Dias Lopes Liliana Marzorati Blanka Wladislaw 《合成通讯》2013,43(3):342-350
The study on reactivity of several α-substituted α-sulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the α-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity of α-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2? and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any α-substituted α-sulfonyl malonate. 相似文献
115.
Peptides bearing an acryloyl residue at their N‐terminus were coupled with various C‐glycosides in an equimolar ratio via cross‐metathesis. The newly formed olefin was obtained with high E/Z selectivity in satisfying to high yields with low homodimerization of the starting materials. The posttranslational cross‐metathesis approach was shown to be suitable for the combinatorial synthesis of a small library of C‐glycopeptides. 相似文献
116.
Stéphanie Miquet Dr. Nicolas Vanthuyne Dr. Paul Brémond Prof. Gérard Audran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10632-10642
The first total syntheses of the proposed structures of kopeolin ( 1 ) and kopeolone ( 3 ) have been achieved from a common enantiopure chiral building block obtained by a chemoenzymatic enantioconvergent methodology. The syntheses feature two key steps: a one‐pot reduction/diastereoselective protonation followed by a highly diastereoselective addition of an organocerate. The synthetic structures were fully characterized and all stereocenters were confirmed. The results show that the two previously reported structures were not assigned correctly, and suggest an initial structural misassignment during the isolation of the natural products. Thus, two revised structures, 1′ for kopeolin and 3′ for kopeolone, are proposed. 相似文献
117.
Prof. Pierre D. Harvey Dr. Frédérique Brégier Prof. Shawkat M. Aly Prof. Jędrzej Szmytkowski Prof. Matthew F. Paige Prof. Ronald P. Steer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(13):4352-4368
Two dendrimers consisting of a cofacial free‐base bisporphyrin held by a biphenylene spacer and functionalized with 4‐benzeneoxomethane (5‐(4‐benzene)tri‐10,15,20‐(4‐n‐octylbenzene)zinc(II)porphyrin) using either five or six of the six available meso‐positions, have been synthesized and characterized as models for the antenna effect in Photosystems I and II. The presence of the short linkers, ‐CH2O‐, and long C8H17 soluble side chains substantially reduces the number of conformers (foldamers) compared with classic dendrimers built with longer flexible chains. This simplification assists in their spectroscopic and photophysical analysis, notably with respect to fluorescence resonance energy transfer (FRET). Both steady‐state and time‐resolved spectroscopic measurements indicate that the cofacial free bases and the flanking zinc(II)–porphyrin antennas act as energy acceptor and donor, respectively, following excitation in either the Q or Soret bands of the dendrimers. The rate constants for singlet electronic energy transfer (kEET) extracted from the S1 and S2 fluorescence lifetimes of the donor in the presence and absence of the acceptor are ≤ (0.1–0.3)×109 and ~2×109 s?1 for S1→S1 (range from a bi‐exponential decay model) and about 1.5×1012 s?1 for S2→Sn (n>1). Comparisons of these experimental data with those calculated from Förster theory using orientation factors and donor–acceptor distances extracted from computer modeling suggest that a highly restricted number of the many foldamers facilitate energy transfer. These foldamers have the lowest energy by molecular modeling and consist of one or at most two of the flanking zinc porphyrin antennas folded so they lie near the central artificial special pair core with the remaining antennas located almost parallel to and far from it. 相似文献
118.
119.
Petr Tůma Martin Jaček Blanka Sommerová Pavel Dlouhý Radka Jarošíková Jitka Husáková Veronika Wosková Vladimíra Fejfarová 《Electrophoresis》2022,43(11):1129-1139
Determination of the broad-spectrum antibiotics amoxicilline (AMX) and ceftazidime (CTZ) in blood serum and microdialysates of the subcutaneous tissue of the lower limbs is performed using CE with contactless conductivity detection (C4D). Baseline separation of AMX is achieved in 0.5 M acetic acid as the background electrolyte and separation of CTZ in 3.2 M acetic acid with addition of 13% v/v methanol. The CE-C4D determination is performed in a 25 µm capillary with suppression of the EOF using INST-coating on an effective length of 18 cm and the attained migration time is 4.2 min for AMX and 4.4 min for CTZ. The analysis was performed using 20 µl of serum and 15 µl of microdialysate, treated by the addition of acetonitrile in a ratio of 1/3 v/v and the sample is injected into the capillary using the large volume sample stacking technique. The LOQ attained in the microdialysate is 148 ng/ml for AMX and 339 ng/ml for CTZ, and in serum 143 ng/ml for AMX and 318 ng/ml for CTZ. The CE-C4D method is employed for monitoring the passage of AMX and CTZ from the blood circulatory system into the subcutaneous tissue at the sites of diabetic ulceration in patients suffering from diabetic foot syndrome and also for measuring the pharmacokinetics following intravenous application of bolus antibiotic doses. 相似文献
120.
Dr. Thi Minh Thi Le Dr. Thibaud Brégent Prof. Dr. Philippe Jubault Prof. Dr. Thomas Poisson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(52):e202201514
Herein, we disclosed the contra-thermodynamic E→Z isomerization of alkenyl silanes, according to the in situ formation of a chromophoric species, in the presence of rac-BINAP as the catalyst. The reaction carried out in DMSO or CH3CN under irradiation at 405 nm allowed the interconversion of the E-isomers into the Z-congeners in good to excellent yields and outstanding Z/E selectivities, on 18 examples. Finally, the mechanism of this E→Z isomerization was studied to get insight into the reaction mechanism. 相似文献