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排序方式: 共有145条查询结果,搜索用时 15 毫秒
1.
皮秒扫描相机在半导体激光管输出特性研究中的应用 总被引:1,自引:1,他引:0
本工作用Picotron 200型扫描相机和液态氮冷却的CCD摄相机系统对半导体激光二极管LTO22 MC的输出特性进行了测量,其最短输出脉冲宽度为2.1ps。这种半导体激光二极管的发射波长为780nm,连续工作条件下,其输出功率为3mW到5mW。 相似文献
2.
Bhavesh Khatri Puja Majumder Jayashree Nagesh Aravind Penmatsa Jayanta Chatterjee 《Chemical science》2020,11(35):9480
Abundant n → π* interactions between adjacent backbone carbonyl groups, identified by statistical analysis of protein structures, are predicted to play an important role in dictating the structure of proteins. However, experimentally testing the prediction in proteins has been challenging due to the weak nature of this interaction. By amplifying the strength of the n → π* interaction via amino acid substitution and thioamide incorporation at a solvent exposed β-turn within the GB1 proteins and Pin 1 WW domain, we demonstrate that an n → π* interaction increases the structural stability of proteins by restricting the ϕ torsion angle. Our results also suggest that amino acid side-chain identity and its rotameric conformation play an important and decisive role in dictating the strength of an n → π* interaction.Amino acid residues adopt a right-handed α-helical conformation with increasing strength of the n → π* interaction. We also demonstrate a direct consequence of n → π* interactions on enhancing the structural stability of proteins. 相似文献
3.
Appu Aravind 《Tetrahedron letters》2005,46(17):2965-2968
A highly regioselective oxidative cleavage of 1,3:4,6-di-O-benzylidene-d-mannitol was carried out using NBS and the resultant product was readily converted to the C2-symmetric chiral ligand, (R,R)-3,4-dihydroxy-1,5-hexadiene. On the other hand, reductive cleavage of 1,3:4,6-di-O-benzylidene-d-mannitol was achieved in a highly regioselective manner using BF3·OEt2 and Et3SiH to give a highly functionalized benzyl ether, which was converted to a synthetically useful C2-symmetric bis-amino alcohol derivative. 相似文献
4.
5.
Parakkulam Ramaswamy Aravind Lorenz Ratke Matthias Kolbe Gian Domenico Soraru 《Journal of Sol-Gel Science and Technology》2013,67(3):592-600
In present work, we have prepared gels with various compositions of methyltrimethoxysilane—3-(2,3-epoxypropoxy) propyltrimethoxysilane (MTMS-GPTMS) using a two-step acid base sol–gel process. To make a comparative study between the two common drying routes, we prepared gels under supercritical and also under ambient conditions. The density of the supercritically dried hybrid aerogels lies between 0.18 and 0.31 gcm?3, while the density of the ambient dried ones ranges between 0.35 and 0.42 gcm?3. The surface area of MTMS-0.25 GPTMS aerogel dried under supercritical conditions, has been found to be 464 m2 g?1 with a pore volume and average pore diameter of 1.24 cm3 g?1 and 11 nm respectively. The same composition dried under ambient conditions is found to have similar properties i.e. a BET surface area of 439 m2 g?1, pore volume of 1.22 cm3 g?1 and average pore diameter of 11 nm. The aerogels were later pyrolyzed yielding silica/carbon composite aerogels. The pyrolized aerogels possessed a surface area as high as 207 m2 g?1 with a total pore volume of 0.98 cm3 g?1. The pyrolysed aerogels were also calcined to yield carbon free materials. 相似文献
6.
Scalable bottom‐up assembly of suspended carbon nanotube and graphene devices by dielectrophoresis
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Antonios Oikonomou Nick Clark Sebastian Heeg Andrey Kretinin Sarah Varey Geliang Yu Aravind Vijayaraghavan 《固体物理学:研究快报》2015,9(9):539-543
Bottom‐up assembly by dielectrophoresis (DEP) has emerged in recent years as a viable alternative to conventional top–down fabrication of electronic devices from nanomaterials, particularly carbon nanotubes and graphene. Here, we demonstrate how this technique can be extended to fabricate devices containing carbon nanotubes and graphene suspended between two electrodes over a back‐gate electrode. The suspended device geometry is critical for the development of nano‐electromechanical devices and to extract maximum performance out of electronic and optoelectronic devices. This technique allows for parallel assembly of devices over large scale. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
7.
A novel approach to the development of a code for the solution of the time-dependent two-dimensional Navier–Stokes equations is described. The code involves coupling between the method of lines (MOL) for the solution of partial differential equations and a parabolic algorithm which removes the necessity of iterative solution on pressure and solution of a Poisson-type equation for the pressure. The code is applied to a test problem involving the solution of transient laminar flow in a short pipe for an incompressible Newtonian fluid. Comparisons show that the MOL solutions are in good agreement with the previously reported values. The proposed method described in this paper demonstrates the ease with which the Navier–Stokes equations can be solved in an accurate manner using sophisticated numerical algorithms for the solution of ordinary differential equations (ODEs). 相似文献
8.
The aim of this work was to establish optimal conditions for the maximum production of endo-β-1,4 mannanases using cheaper
sources. Eight thermotolerant fungal strains were isolated from garden soil and compost samples collected in and around the
Gulbarga University campus, India. Two strains were selected based on their ability to produce considerable endo-β-1,4 mannanases
activity while growing in liquid medium at 37 °C with locust bean gum (LBG) as the only carbon source. They were identified
as Aspergillus niger gr and Aspergillus flavus gr. The experiment to evaluate the effect of different carbon sources, nitrogen sources, temperatures and initial pH of the
medium on maximal enzyme production was studied. Enzyme productivity was influenced by the type of polysaccharide used as
the carbon source. Copra meal defatted with n-hexane showed to be a better substrate than LBG and guar gum for endo-β-1,4 mannanases production by A. niger gr (40.011 U/ml), but for A. flavus gr (33.532 U/ml), the difference was not significant. Endo-β-1,4 mannanases produced from A. niger gr and A. flavus gr have high optimum temperature (65 and 60 °C) and good thermostability in the absence of any stabilizers (maintaining 50%
of residual activity for 8 and 6 h, respectively, at 60 °C) and are stable over in a wide pH range. These new strains offer
an attractive alternative source of enzymes for the food and feed processing industries. 相似文献
9.
Aravind Reddy Dorigundla Raju Gurrapu Venkateswara Rao Batchu 《Tetrahedron letters》2017,58(6):563-565
A simple and an efficient strategy have been developed for the stereoselective synthesis of peracetylated (?)-gloeosporiol by acid catalysed cyclisation from the commercially available starting materials. 相似文献
10.
P. K. Aravind 《Foundations of Physics Letters》2000,13(6):499-519
It is shown that the 24 quantum states or rays used by Peres (J. Phys. A
24, 174-8 (1991)) to give a proof of the Bell–Kochen–Specker (BKS) theorem have a close connection with Reye's configuration, a system of twelve points and sixteen lines known to projective geometers for over a century. The interest of this observation stems from the fact that it provides a ready explanation for many of the regularities exhibited by the Peres rays and also permits a systematic construction of all possible non-coloring proofs of the BKS theorem based on these rays. An elementary exposition of the connection between the Peres rays and Reye's configuration is given, following which its applications to the BKS theorem are discussed. 相似文献