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771.
K. Meera R. Muralidharan A. K. Tripathi R. Dhanasekaran P. Ramasamy 《Journal of Crystal Growth》2004,260(3-4):414-421
Thiourea-doped Triglycine sulphate (ThTGS) crystal with three different concentrations of thiourea was grown from aqueous solution by slow cooling technique. The cell parameters were determined from powder X-ray diffraction analysis. A qualitative analysis of the presence of thiourea in doped crystals was estimated by FTIR analysis. Microhardness studies were carried out using Leitz Weitzler hardness tester at room temperature. Dielectric properties of the crystals were studied which showed a shift in the Tc when compared to pure TGS crystal. Pyroelectric studies were carried out and the pyroelectric coefficient was found. Piezoelectric studies (d33 coefficient) has also been carried out. 相似文献
772.
Tiwari U Tripathi SM Thyagarajan K Shenoy MR Mishra V Jain SC Singh N Kapur P 《Optics letters》2011,36(19):3747-3749
We propose and demonstrate a wavelength tunable wavelength division multiplexing channel isolation filter based on two concatenated chirped long-period fiber gratings (LPGs). An intergrating space (IGS), deliberately introduced between the two gratings, provides an extra phase difference between the core and cladding modes. Changing this phase by heating the IGS without affecting the gratings tunes the channels. A theoretical account of the filter action is also presented and the results are found to be in excellent agreement with the experiments. Unlike the filters based on normal concatenated chirped LPGs without an IGS, the current filter shows a linear tuning over an increased spectral range. 相似文献
773.
Xue Liu Shih C. Tseng Renu Tripathi Alexander Heifetz Subramanian Krishnamurthy M.S. Shahriar 《Optics Communications》2011,284(14):3497-3503
Optical coherence tomography (OCT) relies on interference between a polarized reference and the target reflection. Thus, it has generally been impossible to detect any unpolarized part in the signal. Here, we demonstrate a scheme that overcomes this limitation. Using a combination of heterodyning and filtering, we realize a polarization-sensitive OCT system capable of measuring the full Stokes vector, including the depolarized part. Based on such a system, we perform full Stokesmetric imaging of different layers in a porcine tendon sample. The complete 4 × 4 backscattering Muellermetric images of one layer are acquired and investigated. 相似文献
774.
ZnSe thin films have been prepared by inert gas condensation method at different gas pressures. The influence of deposition pressure, on structural, optical and electrical properties of polycrystalline ZnSe films have been investigated using X-ray diffraction (XRD), optical transmission and conductivity measurements. The X-ray diffraction study reveals the sphalerite cubic structure of the ZnSe films oriented along the (1 1 1) direction. The structural parameters such as particle size [6.65-22.24 nm], strain [4.01-46.6×10−3 lin−2 m−4] and dislocation density [4.762-18.57×1015 lin m−2] have been evaluated. Optical transmittance measurements indicate the existence of direct allowed optical transition with a corresponding energy gap in the range 2.60-3.00 eV. The dark conductivity (σd) and photoconductivity (σph) measurements, in the temperature range 253-358 K, indicate that the conduction in these materials is through an activated process having two activation energies. σd and σph values decrease with the decrease in the crystallite size. The values of carrier life time have been calculated and are found to decrease with the reduction in the particle size. The conduction mechanism in present samples has been explained, and the density of surface states [9.84-21.4×1013 cm−2] and impurity concentration [4.66-31.80×1019 cm−3] have also been calculated. 相似文献
775.
Field emission, morphological and mechanical properties of variety of diamond-like carbon thin films
Neeraj Dwivedi Sushil Kumar R. K. Tripathi H. K. Malik O. S. Panwar 《Applied Physics A: Materials Science & Processing》2011,105(2):417-425
The effect of nitrogen incorporation and sandwich titanium and copper layers, on field emission, morphological and mechanical
properties of diamond-like carbon (DLC) thin films is explored. The introduction of foreign element (N2) and sandwich Cu and Ti layers changed the amorphous morphology to nanostructured, reduced the stress, enhanced the hardness
(except N2 incorporated DLC film) and improved the field emission (except Ti/DLC bilayer) of modified DLC films. The associated versatile
electrical and mechanical properties of modified DLC film made it a material of great utility in the development of field
emission display panels and also lead to its application as a hard and protective coating on cutting tools, automobile parts
etc. It is important to mention that DLC-based electronic materials may replace currently used soft electronic materials (such
as Si) due to their enhanced stability under high energy radiation. 相似文献
776.
The study of simple stochastic games (SSGs) was initiated by Condon for analyzing the computational power of randomized space-bounded alternating Turing machines. The game is played by two players, MAX and MIN, on a directed multigraph, and when the play terminates at a sink vertex s, MAX wins from MIN a payoff p(s)∈[0,1]. Condon proved that the problem SSG-VALUE—given a SSG, determine whether the expected payoff won by MAX is greater than 1/2 when both players use their optimal strategies—is in NP∩coNP. However, the exact complexity of this problem remains open, as it is not known whether the problem is in P or is hard for some natural complexity class. In this paper, we study the computational complexity of a strategy improvement algorithm by Hoffman and Karp for this problem. The Hoffman–Karp algorithm converges to optimal strategies of a given SSG, but no non-trivial bounds were previously known on its running time. We prove a bound of O(n2/n) on the convergence time of the Hoffman–Karp algorithm, and a bound of O(20.78n) on a randomized variant. These are the first non-trivial upper bounds on the convergence time of these strategy improvement algorithms. 相似文献
777.
An isomer-divergent synthesis of naturally occurring pericosines A and B is described starting from a known D-ribose derived ene-diol in 35% and 41% overall yields respectively of which the latter is the best synthetic method reported for pericosine B. The key features of this synthesis include the stereoselective NHK vinylation of the terminal aldehyde to the versatile diolefinic chiral intermediate and elegant conversions of the same to the corresponding final products via RCM (Ring Closing Metathesis). 相似文献
778.
Complexity of a problem of energy efficient real‐time task scheduling on a multicore processor 下载免费PDF全文
The problem of scheduling independent tasks with a common deadline for a multicore processor is investigated. The speed of cores can be varied (from a finite set of core speeds) using software controlled Dynamic Voltage Scaling. The energy consumption is to be minimized. This problem was called the Energy Efficient Task Scheduling Problem (EETSP) in a previous work in which a Monte Carlo algorithm was proposed for solving it. This work investigates the complexity of the EETSP problem. The EETSP problem is proved to be NP‐Complete. Under the assumption of , the EETSP problem is also proved to be inapproximable. © 2014 Wiley Periodicals, Inc. Complexity 21: 259–267, 2015 相似文献
779.
Ajai K. Tripathi Umed V. Ramani Amrutlal K. Patel Dharamshibhai N. Rank Chaitanya G. Joshi 《Applied biochemistry and biotechnology》2013,169(2):688-694
Myostatin (MSTN) belongs to the transforming growth factor (TGF)-β superfamily and is a potent negative regulator of skeletal muscle development and growth. Dysfunction of MSTN gene either by natural mutation or induced through genetic manipulation (knockout or knockdown) has been reported to increase the remarkable muscle mass in mammalian species. RNA interference (RNAi) is the most promising method for inhibition of gene expression that can be utilized for MSTN gene knockdown by developing short hairpin RNA (shRNA) construct against it. We utilized three antisense RNA expressing vectors with six constructs to knockdown MSTN gene in in vitro caprine myoblast cell culture system. We observed that all six shRNA constructs were successful in MSTN silencing with efficiency ranging from 7 to 46 % by quantitative real-time PCR and up to 19 % by western blotting. The significant upregulation of interferon response gene OAS1 (5- to 11-fold) in cells transfected with shRNA constructs were indicative of induction of interferon response. This RNAi-based method of increasing muscle mass could provide an alternative strategy to gene knockout methods for improving the production traits and economic properties of livestock. 相似文献
780.
M. Nasim S. K. Tripathi S. B. Mishra B. L. Khandelwal 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):1019-1034
Abstract A series of phenol-substituted acyclic Schiff bases, 2,6-{RE(CH2) n N═C(CH3)}2-C6H2(4-CH3)(OH), (E = Te: R = C6H5, n = 2(L a), 3(L b); R = C6H4-4-OCH3, n = 2(L c), 3(L d); E = Se: R = C6H5, n = 2(L e), 3(L f)), of the type E2N2O have been synthesized by condensation of 2,6-diacetyl-4-methylphenol with arylchalcogenoalkylamines. This ligand framework is useful for designing molecular complexes with a variety of coordination modes depending upon the nature of the central metal atom. The reactivity of the tellurium-bearing macroacyclics ligands towards Zn(II), Cd(II), and Hg(II) has been examined. The ligands L a?L d with Zn(II) and Cd(II), and only L a and L b with Hg(II) form complexes of composition M2X4L, (X = Cl or Br), whereas L c and L d with Hg(II) give products of composition HgBr2L. The modes of ligand interaction with Zn(II) and Cd(II) are different than that with Hg(II). Following a multistep reaction involving abstraction of bridged Br atoms and subsequent addition of more ligand, the mercury complex, Hg2Br4L has been used for developing metallocyclic system of the type [Hg2Br2L2]2+. The latter has been found to encapsulate Zn(II) and Cd(II) to give multimetallic systems. 相似文献