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91.
Sungchil Kang Alexander Efremov Sun Jin Yun Jinyoung Son Kwang-Ho Kwon 《Plasma Chemistry and Plasma Processing》2013,33(2):527-538
An investigation of etching behaviors for Mo and Al2O3 thin films in O2/Cl2/Ar inductively coupled plasmas at constant gas pressure (6 mTorr), input power (700 W) and bias power (200 W) was carried out. It was found that an increase in Ar mixing ratio for Cl2/Ar plasma results in non-monotonic etching rates with the maximums of 160 nm/min at 60 % Ar for Mo and 27 nm/min at 20 % Ar for Al2O3. The addition of O2 in the Cl2/Ar plasma causes the non-monotonic Mo etching rate (max. 320 nm/min at 40–45 % O2) while the Al2O3 etching rate decreases monotonically. The model-based analysis of etching kinetics allows one to relate the non-monotonic etching rates in Cl2/Ar plasma to the change in the etching regime from the ion-flux-limited mode (at low Ar mixing ratios) to the neutral-flux-limited mode (for high Ar mixing ratios). In the Cl2/O2/Ar plasma, the non-monotonic Mo etching rate is probably due to the change in reaction probability. 相似文献
92.
Kongkai Zhu Junyan Lu Zhongjie Liang Xiangqian Kong Fei Ye Lu Jin Heji Geng Yong Chen Mingyue Zheng Hualiang Jiang Jun-Qian Li Cheng Luo 《Journal of computer-aided molecular design》2013,27(3):247-256
New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C–N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies. 相似文献
93.
Caffeine (1,3,7-trimethylxanthine) is a chemical substance associated with everyday human life. In order to recognize caffeine in water, six water-soluble acyclic phane compounds composed of three aromatic rings were examined as artificial receptors. 1H NMR titration experiments revealed that 6,6′-[1,3-phenylenebis(carbonylimino)]bis-1,3-naphthalenedisulfonate had the highest binding ability for caffeine, with a binding constant (Kb) of 127±5 M−1 at 300 K. While this phane compound also formed a complex with theophylline (1,3-dimethylxanthine) at around half the value of the binding constant for caffeine (Kb=64±4 M−1), it showed weak or little complexation for adenosine, guanosine, inosine, and their 5′-phosphates (sodium salts of adenylic acid, guanylic acid, and inosinic acid). 相似文献
94.
Fang Sheng Bangyan Hu Qiang Jin Jiangbo Wang Cuiyun Wu Zhengrong Luo 《Molecules (Basel, Switzerland)》2021,26(10)
Husk and pellicle as the agri-food waste in the walnut-product industry are in soaring demand because of their rich polyphenol content. This study investigated the differential compounds related to walnut polyphenol between husk and pellicle during fruit development stage. By using ultra-high performance liquid chromatography-quadrupole-orbitrap (UHPLC-Q-Orbitrap), a total of 110 bioactive components, including hydrolysable tannins, flavonoids, phenolic acids and quinones, were tentatively identified, 33 of which were different between husk and pellicle. The trend of dynamic content of 16 polyphenols was clarified during walnut development stage by high-performance liquid chromatography (HPLC). This is the first time to comprehensive identification of phenolic compounds in walnut husk and pellicle, and our results indicated that the pellicle is a rich resource of polyphenols. The dynamic trend of some polyphenols was consistent with total phenols. The comprehensive characterization of walnut polyphenol and quantification of main phenolic compounds will be beneficial for understanding the potential application value of walnut and for exploiting its metabolism pathway. 相似文献
95.
We find type I critical collapses of compact objects modeled by a polytropic equation of state (EOS) with a polytropic index Gamma=2 without the ultrarelativistic assumption. The object is formed in head-on collisions of neutron stars. Further, we show that the critical collapse can occur due to a change of the EOS, without fine-tuning of initial data. This opens the possibility that a neutron-star-like compact object, not just those formed in a collision, may undergo a critical collapse in processes which slowly change the EOS, such as cooling. 相似文献
96.
Guohai Deng Dr. Sudip Pan Dr. Jiaye Jin Prof. Dr. Guanjun Wang Prof. Lili Zhao Prof. Dr. Mingfei Zhou Prof. Gernot Frenking 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):412-418
Two structural isomers containing five second-row element atoms with 24 valence electrons were generated and identified by matrix-isolation IR spectroscopy and quantum chemical calculations. The OCBNO complex, which is produced by the reaction of boron atoms with mixtures of carbon monoxide and nitric oxide in solid neon, rearranges to the more stable OBNCO isomer on UV excitation. Bonding analysis indicates that the OCBNO complex is best described by the bonding interactions between a triplet-state boron cation with an electron configuration of (2s)0(2pσ)0(2pπ)2 and the CO/NO− ligands in the triplet state forming two degenerate electron-sharing π bonds and two ligand-to-boron dative σ bonds. 相似文献
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100.
Yan Guan Dayu Zhou Jin Xu Xiaohua Liu Fei Cao Xianlin Dong Johannes Müller Tony Schenk Uwe Schroeder 《固体物理学:研究快报》2015,9(10):589-593
A wealth of studies have confirmed that the low‐field hysteresis behaviour of ferroelectric bulk ceramics and thin films can be described using Rayleigh relations, and irreversible domain wall motion across the array of pining defects has been commonly accepted as the underlying micro‐mechanism. Recently, HfO2 thin films incorporated with various dopants were reported to show pronounced ferroelectricity, however, their microscopic domain structure remains unclear till now. In this work, the effects of the applied electric field amplitude, frequency and temperature on the sub‐coercive polarization reversal properties were investigated for 10 nm thick Si‐doped HfO2 thin films. The applicability of the Rayleigh law to ultra‐thin ferroelectric films was first confirmed, indicating the existence of a multi‐domain structure. Since the grain size is about 20–30 nm, a direct observation of domain walls within the grains is rather challenging and this indirect method is a feasible approach to resolve the domain structure. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献