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41.
Diwakar K. Rajkumar P. Subadevi R. Arjunan P. Sivakumar M. 《Journal of Solid State Electrochemistry》2021,25(4):1231-1236
Journal of Solid State Electrochemistry - In order to eliminate the short fall due to PO4 group results in an intrinsic conductivity of the material, an attempt has been made to prepare... 相似文献
42.
Machado E Kaczmarski M Ordejón P Garg D Norman J Cheng H 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7608-7614
We present theoretical studies based on first-principles density functional theory calculations on the mechanisms of chemical vapor deposition of Cu-hexafluoracetylacetonato-trimethylvinylsilane (Cu(hfac)(tmvs)) on tantalum surfaces. This process has been used in the past to grow copper films via a disproportionation reaction and was found to exhibit adhesion problems. We show that the Ta surfaces are highly reactive and that the organic ligands in a copper precursor would undergo spontaneous decomposition upon contact with the Ta substrates. This may lead to contamination of the metal surfaces caused by the formation of carbide, fluoride, oxide species, or other fragments of the copper precursor on the barrier layer. We propose a practical solution for these adhesion problems caused by the CVD process by passivating the metal surfaces with N(2) to reduce their activity toward the precursor. Our extensive first-principles molecular dynamics simulations under typical deposition conditions predict that, for properly passivated TaN surfaces, only the copper atoms are firmly adsorbed on the surface, with loose Cu-ligand bonds. The ligands are sufficiently stable on these passivated surfaces, remaining slightly above the surface due to the repulsion between the electron-rich N-layer and the electron-rich ligand groups, and subsequently liberated upon the disproportionation reaction. 相似文献
43.
Malviya N Srivastava M Diwakar SK Mishra SK 《Applied biochemistry and biotechnology》2011,165(2):397-405
Polyphenol oxidases (PPOs) are widely distributed enzymes among animals, plants, bacteria, and fungi. PPOs often have significant
role in many biologically essential functions including pigmentation, sclerotization, primary immune response, and host defense
mechanisms. In the present study, forty-seven full-length amino acid sequences of PPO from bacteria, fungi, and plants were
collected and subjected to multiple sequence alignment (MSA), domain identification, and phylogenetic tree construction. MSA
revealed that six histidine, two phenylalanine, two arginine, and two aspartic acid residues were highly conserved in all
the analyzed species, while a single cysteine residue was conserved in all the plant and fungal PPOs. Two major sequence clusters
were constructed by phylogenetic analysis. One cluster was of the plant origin, whereas the other one was of the fungal and
bacterial origin. Motif GGGMMGDVPTANDPIFWLHHCNVDRLWAVWQ was found in all the species of bacterial and fungus sources. In addition,
seven new motifs which were unique for their group were also identified. 相似文献
44.
45.
MM. D. Letouz J. Duflos G. Queguiner P. Pastour 《Journal of heterocyclic chemistry》1973,10(6):1075-1076
This communication describes the synthesis of 7-one (7H) cyclohepta[b]pyridine and some derivatives (6,8-dimethyl; 8-methyl; 8-ethyl….). These compounds have been obtained by condensation of ketones with 2,3-diformylpyridine. 相似文献
46.
Pawar DM Cain D Gill G Bain AD Sullivan RH Noe EA 《The Journal of organic chemistry》2007,72(1):25-29
Interconversion of carbon sites in boat-chair-boat (BCB) cyclodecane occurs by way of the twist-boat-chair (TBC) conformation, which predicts that C-1 exchanges with C-4, etc. The previously obtained low-temperature 13C spectra could be matched by assuming (1,4) or (1,3) exchange, but not (1,2) exchange. A free-energy barrier of 5.54 kcal/mol was obtained for conversion of BCB to TBC at -137.4 degrees C. The major conformation of chlorocyclodecane and cyclodecyl acetate is assigned to the IIIe BCB. 相似文献
47.
Sans résumé 相似文献
48.
S. S. Harilal N. Farid J. R. Freeman P. K. Diwakar N. L. LaHaye A. Hassanein 《Applied Physics A: Materials Science & Processing》2014,117(1):319-326
The collisional effects of a background gas on expanding ultrafast and short pulse laser ablation plumes were investigated by varying background pressure from vacuum to atmospheric pressure levels. For producing Cu ablation plumes, either 40 fs, 800 nm pulses from a Ti: Sapphire laser or 6 ns, 1,064 nm pulses from a Nd:YAG laser were used. The role of background pressure on plume hydrodynamics, spectral emission features, absolute line intensities, signal to background ratios and ablation craters was studied. Though the signal intensities were found to be maximum near to atmospheric pressure levels, the optimum signal to background ratios are observed ~20–50 Torr for both ns and fs laser ablation plumes. The differences in laser–target and laser–plasma couplings between ns and fs lasers were found to be more engraved in the crater morphologies and plasma hydrodynamic expansion features. 相似文献
49.
Dr. Balaji Selvam Zahra Shamsi Prof. Diwakar Shukla 《Angewandte Chemie (International ed. in English)》2018,57(12):3048-3053
The allosteric modulation of G‐protein‐coupled receptors (GPCRs) by sodium ions has received significant attention as crystal structures of several receptors show Na+ ions bound to the inactive conformations at the conserved Asp2.50. To date, structures from 24 families of GPCRs have been determined, though mechanistic insights into Na+ binding to the allosteric site are limited. We performed hundreds‐of‐microsecond long simulations of 18 GPCRs and elucidated their Na+ binding mechanism. In class A GPCRs, the Na+ ion binds to the conserved residue 2.50 whereas in class B receptors, it binds at 3.43b, 6.53b, and 7.49b. Using Markov state models, we obtained the free energy profiles and kinetics of Na+ binding to the allosteric site, which reveal a conserved mechanism of Na+ binding for GPCRs and show the residues that act as major barriers for ion diffusion. Furthermore, we also show that the Na+ ion can bind to GPCRs from the intracellular side when the allosteric site is inaccessible from the extracellular side. 相似文献
50.
The objective of this study was to determine if topical anesthesia to the larynx and pharynx affects vocal fold motion during dynamic voice evaluation with transnasal flexible endoscopy. Transnasal dynamic laryngeal examinations of 10 patients with no voice complaints were evaluated by five blinded fellowship-trained laryngologists. Each patient was examined before and after application of topical anesthetic. Reviewers rated briskness of right and left vocal fold movement and longitudinal tension on a visual analogue scale. Statistical comparisons were made between individual subject scores before and after anesthetic application. Inter-rater reliability was also assessed. No statistical difference was observed between subject scores before and after anesthetic application. Average intraclass correlation coefficients were 0.643 and 0.591 for pre- and postanesthesia scores, respectively. Application of topical anesthesia to the larynx and pharynx does not affect vocal fold motion. 相似文献