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排序方式: 共有134条查询结果,搜索用时 186 毫秒
81.
Dr. Amandine Cadiau Nikita Kolobov Dr. Sivaranjani Srinivasan Dr. Maarten G. Goesten Dr. Henrik Haspel Dr. Anastasiya V. Bavykina Dr. Mohamed R. Tchalala Dr. Partha Maity Dr. Andrey Goryachev Artem S. Poryvaev Prof. Dr. Mohamed Eddaoudi Dr. Matvey V. Fedin Prof. Dr. Omar F. Mohammed Prof. Dr. Jorge Gascon 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13570-13574
The one-step synthesis and characterization of a new and robust titanium-based metal–organic framework, ACM-1 , is reported. In this structure, which is based on infinite Ti−O chains and 4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayl) tetrabenzoic acid as a photosensitizer ligand, the combination of highly mobile photogenerated electrons and a strong hole localization at the organic linker results in large charge-separation lifetimes. The suitable energies for band gap and conduction band minimum (CBM) offer great potential for a wide range of photocatalytic reactions, from hydrogen evolution to the selective oxidation of organic substrates. 相似文献
82.
Gunther W Leugner D Becker E Flesch F Heinrich W Huntrup G Reitz G Rocher H Streibel T 《Radiation measurements》1999,31(1-6):585-590
We have exposed stacks of CR-39 plastic nuclear track detectors inside the MIR space craft during the EUROMIR95 space mission for almost 6 months. Over this long period a large number of tracks of high LET events was accumulated in the detector foils. The etching and measuring conditions for this experiment were optimized to detect tracks of stopping iron nuclei. We found 185 stopping iron nuclei inside the stack and identified their trajectories through the material of the experiment. Based on the energy-range relation the energy at the surface of the stack was determined. These particles allow the determination of the low energy part of the spectrum of iron nuclei behind shielding material inside the MIR station. 相似文献
83.
We study the qualitative properties of sign changing solutions of the Dirichlet problem in Ω, on ?Ω, where Ω is a ball or an annulus and f is a function with . We prove that any radial sign changing solution has a Morse index bigger or equal to and give sufficient conditions for the nodal surface of a solution to intersect the boundary. In particular, we prove that any least energy nodal solution is non radial and its nodal surface touches the boundary. To cite this article: A. Aftalion, F. Pacella, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
84.
Morgane De Tollenaere Clo Boira Emilie Chapuis Laura Lapierre Cyrille Jarrin Patrick Robe Catherine Zanchetta David Vilanova Bndicte Sennelier-Portet Jessy Martinez Amandine Scandolera Daniel Auriol Romain Reynaud 《Molecules (Basel, Switzerland)》2022,27(15)
(1) Background: Preclinical studies report that the ethanolic fraction from Mangifera indica leaves is a potential anti-acne agent. Nevertheless, the biological activity of Mangifera indica leaves has scarcely been investigated, and additional data are needed, especially in a clinical setting, for establishing the actual effectiveness of Mangifera indica extract as an active component of anti-acne therapy. (2) Methods: The evaluation of the biological activity of Mangifera indica extract was carried out through different experimental phases, which comprised in silico, in vitro, ex vivo and clinical evaluations. (3) Results: In silico and in vitro studies allowed us to identify the phytomarkers carrying the activity of seboregulation and acne management. Results showed that Mangifera indica extract reduced lipid production by 40% in sebocytes, and an improvement of the sebum quality was reported after the treatment in analyses performed on sebaceous glands from skin explants. The evaluation of the sebum quantity and quality using triglyceride/free fatty acid analysis conducted on Caucasian volunteers evidenced a strong improvement and a reduction of porphyrins expression. The C. acnes lipase activity from a severe acne phylotype was evaluated in the presence of Mangifera indica, and a reduction by 29% was reported. In addition, the analysis of the skin microbiota documented that Mangifera indica protected the microbiota equilibrium while the placebo induced dysbiosis. (4) Conclusions: Our results showed that Mangifera indica is microbiota friendly and efficient against lipase activity of C. acnes and supports a role for Mangifera indica in the therapeutic strategy for prevention and treatment of acne. 相似文献
85.
Mégane Debiais Amandine Lelievre Dr. Jean-Jacques Vasseur Prof. Dr. Sabine Müller Prof. Dr. Michael Smietana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):1138-1144
The 10–23 DNAzyme is an artificially developed Mg2+-dependent catalytic oligonucleotide that can cleave an RNA substrate in a sequence-specific fashion. In this study, new split 10–23 DNAzymes made of two nonfunctional fragments, one of which carries a boronic acid group at its 5′ end, while the other has a ribonucleotide at its 3′ end, were designed. Herein it is demonstrated that the addition of Mg2+ ions leads to assembly of the fragments, which in turn induces the formation of a new boronate internucleoside linkage that restores the DNAzyme activity. A systematic evaluation identified the best-performing system. The results highlight key features for efficient control of DNAzyme activity through the formation of boronate linkages. 相似文献
86.
Dr. Amandine Boulmier Dr. Mohamed Haouas Somia Tomane Laurent Michely Dr. Anne Dolbecq Dr. Anne Vallée Prof. Vlasta Brezová Dr. Davy-Louis Versace Prof. Pierre Mialane Dr. Olivier Oms 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14349-14357
The synthesis of TBA-DASA-POM-DASA , the first photoactive covalent hybrid polyoxometalate (POM) incorporating a donor–acceptor Stenhouse adduct (DASA) reverse photochrome, is presented. It has been evidenced that in solution the equilibrium between the colorless cyclopentenone and the highly colored triene conformers is strongly dependent not only on the nature of the solvent but also the countercations, allowing to tune its optical properties. This complex has been further associated to photochromic spironaphtoxazine cations, resulting in a material which can be activated by two distinct optical stimuli. Moreover, when combined with N-methyldiethanolamine, TBA-DASA-POM-DASA constitutes a performing photoinitiating system for polyethylene glycol diacrylate polymerization and under visible light irradiation, a promising result in a domain scarcely developed in POM chemistry. 相似文献
87.
The paper investigates the properties of a class of resource allocation algorithms for communication networks: if a node of this network has requests to transmit and is idle, it tries to access the channel at a rate proportional to . A stochastic model of such an algorithm is investigated in the case of the star network, in which nodes can transmit simultaneously, but interfere with a central node 0 in such a way that node 0 cannot transmit while one of the other nodes does. One studies the impact of the log policy on these interacting communication nodes. A fluid scaling analysis of the network is derived with the scaling parameter being the norm of the initial state. It is shown that the asymptotic fluid behavior of the system is a consequence of the evolution of the state of the network on a specific time scale . The main result is that, on this time scale and under appropriate conditions, the state of a node with index is of the order of , with , where is a piecewise linear function. Convergence results on the fluid time scale and a stability property are derived as a consequence of this study. 相似文献
88.
89.
Infrared and Raman spectroscopy were used to study hydrogen-bonding interactions and the cation coordination effect in solutions of N,N-dimethylethylenediamine (DMEDA) with lithium triflate (LiTf) and sodium triflate (NaTf). A comparison of pure DMEDA with DMEDA dissolved in carbon tetrachloride enabled the separation of the relative contributions of intermolecular and intramolecular hydrogen-bonding interactions to the N-H stretching frequencies. The addition of LiTf and NaTf to DMEDA shifts the N-H stretching frequencies through two competing effects: the cation coordination effect lowers the frequencies, while the disruption of the hydrogen-bonding interactions increases the frequencies. These two effects were distinguished in a study of the concentration dependence of both salts dissolved in DMEDA; the differentiation was based on the difference in the spectral sensitivities of the symmetric and the antisymmetric stretch in both the Raman and infrared spectra. During this study, DMEDA-LiTf and DMEDA-NaTf crystals were discovered, and their structures were solved by X-ray diffraction techniques. The analysis of the vibrational spectra of these crystals was greatly enhanced by unambiguous knowledge of the structural details of cation-molecule and anion-cation interactions. These structure-spectra correlations were used to complement analogous spectroscopic studies in the solution phases. Analysis of spectral regions in both crystalline and solution phases particularly sensitive to the nature and strength of cation-molecule interactions clearly established that the interaction of the lithium ion with the nitrogen atoms of DMEDA was stronger than the sodium ion-DMEDA interaction, as expected from charge density arguments. 相似文献
90.