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41.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
42.
43.
Krishnan Thiyagarajan Thangavelu Kesavamurthy Gattu Bharathkumar 《Applied magnetic resonance》2014,45(3):255-268
Magnetic resonance imaging (MRI) technique is widely used to capture the images of the liquid items inside the human body. The radio-frequency (RF) coil is one of the important modules present inside an MRI system, which plays a major role in image quality. In this work, a microstrip-based high-pass RF birdcage coil is proposed for 1.5 T MRI. The cylindrical-shaped birdcage coil consists of 12 microstrip radiating elements and tuning capacitors to achieve a resonance at 63.85 MHz. The coil is made up of 10 mm polytetrafluoroethylene substrate coated by a conducting transmission line of desired length and width. A finite difference time domain simulation is carried out to analyze the return loss (S11), magnetic field homogeneity and Specific Absorption Rate (SAR) parameters of the RF coil. The SAR values of the proposed microstrip-based 1.5 T birdcage coil was compared with 3 T RF birdcage coil. The simulation results indicate the proposed birdcage coil structure gives optimal values of S11, magnetic field homogeneity and SAR. 相似文献
44.
PENG Yan-Ze E.V. Krishnan 《理论物理通讯》2005,44(11)
The singular manifold method is used to obtain two general solutions to a (2 1)-dimensional breaking soliton equation, each of which contains two arbitrary functions. Then the new periodic wave solutions in terms of the Jacobi elliptic functions are generated from the general solutions. The long wave limit yields the new types of dromion and solitary structures. 相似文献
45.
D. Banerjee S.V. Thakare R. Menon K. Krishnan 《Journal of Physics and Chemistry of Solids》2010,71(7):983-987
Phase transition from anatase to rutile for the 70 nm TiO2 crystallite has been investigated by the time differential perturbed angular correlation (TDPAC) technique. The study involved the annealing of the TiO2 nanocrystals, adsorbed with the nuclear probe (181Hf/181Ta) at trace level, at different temperatures for different durations. The TDPAC measurement was also supported by XRD measurement where the width of the peaks increases with the increase in annealing temperature indicating a crystal growth. The samples annealed up to 823 K for 4 h showed no phase transition, except for the growth of the crystallites. However, it showed phase transition at the same temperature (823 K), when annealed for longer duration, indicating the slower kinetics of the phase transition process. Further the sample, when annealed at 1123 K for 4 h, showed phase transition. It has also been observed that the 181Hf tracer, adsorbed on 70 nm anatase TiO2, diffuses from surface to bulk during the phase transition process and the extent of diffusion in anatase differs from that in rutile phase. However, surface to bulk mass-transfer is found to play a significant role in the phase transition process. 相似文献
46.
47.
Krishnan R. Anandha Pounraj P. Govindaraj R. Pandian Muthu Senthil Ramasamy P. 《Research on Chemical Intermediates》2022,48(5):1877-1906
Research on Chemical Intermediates - Triphenylamine and methoxy substituted triphenylamine-based dyes are examined by density-functional theory and time-dependent density-functional theory. The... 相似文献
48.
Dr. Kyung-Seok Kang Dr. Krishnan A. Iyer Prof. Dr. Jeffrey Pyun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(35):e202200115
In this concept review, the fundamental and polymerization chemistry of inverse vulcanization for the preparation of statistical and segmented sulfur copolymers, which have been actively developed and advanced in various applications over the past decade is discussed. This concept review delves into a discussion of step-growth polymerization constructs to describe the inverse vulcanization process and discuss prepolymer approaches for the synthesis of segmented sulfur polyurethanes. Furthermore, this concept review discusses the advantages of inverse vulcanization in conjunction with dynamic covalent polymerization and post-polymerization modifications to prepare segmented block copolymers with enhanced thermomechanical and flame retardant properties of these materials. 相似文献
49.
K. D. Singh Mudher K. Krishnan R. R. Khandekar M. B. Yadav N. C. Jayadevan D. D. Sood 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):183-191
Rubidium uranium trisulphate [Rb2U(SO4)3] was prepared as a high purity compound of uranium in different lots of 250 g each. The compound was characterised and evaluated
by chemical, atomic spectrosopic, infrared, X-ray diffraction and thermogravimetric methods for its use as a chemical assay
standard for uranium. The compound is stoichiometric, pure, homogeneous and stable in atmospheric conditions. The solubility
studies showed that Rb2U(SO4)3 is easily soluble in mineral acids. An experiment based on Randomised Block Design was carried out to assign a value to the
uranium content in Rb2U(SO4)3 from the statistically analysed chemical data. The assigned value of [34.167±0.042]% to the uranium content is in close agreement
with the theoretical value of 34.152%. Based on these studies, Rb2U(SO4)3 is recommended as a chemical assay standard for uranium. 相似文献
50.
Quantum chemical insights into Alzheimer's disease: Curcumin's chelation with Cu(II), Zn(II), and Pd(II) as a mechanism for its prevention 下载免费PDF全文
Krishnan Balasubramanian 《International journal of quantum chemistry》2016,116(14):1107-1119
We provide quantum chemical insights into curcumin's prevention of Alzheimer' disease through curcumin's scavenging of neurotoxic Cu(II), Zn(II), and Pd(II) transition metal ions that catalyze polymerization of amyloid‐β and promote misfolding of amyloid into neurotoxic conformations. We have employed high level quantum chemical computations to study the chelate complexes of curcumin with Cu(II), Zn(II), and Pd(II). Quantum chemically derived structures, IR spectra, and UV‐visible spectra of these complexes corroborate with the observed spectra, confirming that the primary site of chelation is the β‐diketone bridge through the loss of an enolic proton of curcumin. We have also obtained the various structural parameters such as the Mulliken charges on various centers, highest occupied, lowest unoccupied molecular orbitals—all of which confirm that curcumin forms chelate complexes and thus acts as a scavenger of these neurotoxic metal ions preventing Alzheimer's disease. We find that the open‐d‐shell Cu(II) and Pd(II) form nearly square planar complexes while the closed‐d‐shell Zn(II) forms a tetrahedral complex with curcumin. © 2016 Wiley Periodicals, Inc. 相似文献