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41.
S. Sarkar A. D. Thakur C. V. Tomy G. Balakrishnan D. McK Paul S. Ramakrishnan A. K. Grover 《Pramana》2006,66(1):193-207
New experimental data are presented on the scan rate dependence of the magnetization hysteresis width ΔM(H) (∞ critical current densityJ
c(H)) in isothermalMH scans in a weakly pinned single crystal of Ca3Rh4Sn13, which displays second magnetization peak (SMP) anomaly as distinct from the peak effect (PE). We observe an interesting
modulation in the field dependence of a parameter which purports to measure the dynamical annealing of the disordered bundles
of vortices injected through the sample edges towards the destined equilibrium vortex state at a givenH. These data, in conjunction with the earlier observations made while studying the thermomagnetic history dependence inJ
c(H) in the tracing of the minor hysteresis loops, imply that the partially disordered state heals towards the more ordered state
between the peak field of the SMP anomaly and the onset field of the PE. The vortex phase diagram in the given crystal of
Ca3Rh4Sn13 has been updated in the context of the notion of the phase coexistence of the ordered and disordered regions between the
onset field of the SMP anomaly and the spinodal line located just prior to the irreversibility line. A multi-critical point
and a critical point in the (H,T) region of the Bragg glass phase have been marked in this phase diagram and the observed behavior is discussed in the light
of recent data on multi-critical point in the vortex phase diagram in a single crystal of Nb. 相似文献
42.
Santhi A Umadevi M Ramakrishnan V Radhakrishnan P Nampoori VP 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(5):1077-1083
Nano structured noble metals have very important applications in diverse fields as photovoltaics, catalysis, electronic and magnetic devices, etc. Here, we report the application of dual beam thermal lens technique for the determination of the effect of silver sol on the absolute fluorescence quantum yield (FQY) of the laser dye rhodamine 6G. A 532 nm radiation from a diode pumped solid state laser was used as the excitation source. It has been observed that the presence of silver sol decreases the fluorescence quantum efficiency. This is expected to have a very important consequence in enhancing Raman scattering which is an important spectrochemical tool that provides information on molecular structures. We have also observed that the presence of silver sol can enhance the thermal lens signal which makes the detection of the signal easier at any concentration. 相似文献
43.
Twenty three at‐risk high school female students who had failed mathematics and science in a traditional school setting were the subjects of this study that integrated mathematics and science lessons over a period of four weeks. Using a combination of direct instruction, calculations, graphing, hands‐on projects, and discussion, the topic of mechanical advantage was studied, to find out how well students understood the topic. The study found that these students who initially knew very little about mechanical advantage, and who did not see any need to use mathematics in the study of science, indicated an increased understanding of mechanical advantage, and also seemed to realize that integrating mathematics and science enhanced learning. 相似文献
44.
45.
Percolation-enhanced generation of terahertz pulses by optical rectification on ultrathin gold films
Emission of pulses of electromagnetic radiation in the terahertz range is observed when ultrathin gold films on glass are illuminated with femtosecond near-IR laser pulses. A distinct maximum is observed in the emitted terahertz amplitude from films of average thickness just above the percolation threshold. Our measurements suggest that the emission is through a second-order nonlinear optical rectification process, enhanced by the excitation of localized surface plasmon hot spots on the percolated metal film. 相似文献
46.
In a recent work, S. Cooper (J. Number Theory 103:135–162, [1988]) conjectured a formula for r
2k+1(p
2), the number of ways p
2 can be expressed as a sum of 2k+1 squares. Inspired by this conjecture, we obtain an explicit formula for r
2k+1(n
2),n≥1.
Dedicated to Srinivasa Ramanujan. 相似文献
47.
Natarajan Raman Ramaraj Jeyamurugan Mariyyappan Subbulakshmi Raja Boominathan Chithu Ramakrishnan Yuvarajan 《Chemical Papers》2010,64(3):318-328
A novel series of Co(II), Ni(II), Cu(II), Zn(II), and VO(IV) complexes has been synthesized from the Schiff base derived from
4-[(3,4-dimethoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one and 1,2-diaminobenzene. Structural features
were determined by analytical and spectral techniques. Binding of synthesized complexes with calf thymus DNA (CT DNA) was
studied by spectroscopic methods and viscosity measurements. Experimental results indicate that the complexes are able to
form adducts with DNA and to distort the double helix by changing the base stacking. Lower DNA affinity of the VO(IV) complex
is caused by the change of coordination geometry by the vanadyl ion resulting in a somewhat unfavorable configuration for
the DNA binding. Oxidative DNA cleavage activities of the complexes were studied with supercoiled (SC) pUC19 DNA using gel
electrophoresis; the mechanism studies revealed that the hydroxyl radical is likely to be the reactive species responsible
for the cleavage of pUC19 DNA by the synthesized complexes. The in vitro antimicrobial screening effects of the investigated
compounds were monitored by the disc diffusion method. The synthesized Schiff base complexes exhibit higher antimicrobial
activity than the respective free Schiff base. 相似文献
48.
The design and synthesis of 1,3-dithiol linked acridinedione functionalized gold nanoparticles (ADDDT-GNP) is described. ADDDT-GNP was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV-vis, steady-state and time-resolved fluorescence techniques. Conformational analysis of 1,3-dithiol ligands using density functional theory (DFT) reveals that they can cap on gold clusters through 1,2-capping mode, in which the two sulfur atoms of the dithiol bind covalently with two adjacent gold atoms on the surface of the cluster. The present study shows that three conformers of the ligand can cap in the 1,2-mode of capping. The triexponential fluorescence decay observed in the capped nanogold complex with fluorophore-labeled 1,3-dithiol may originate from the three conformers of the complex in the 1,2-capping mode. 相似文献
49.
P. Senthil Kumar V. SathyaSelvaBala K. Ramakrishnan P. Vijayalakshmi S. Sivanesan 《Russian Chemical Bulletin》2010,59(10):1859-1864
The feasibility of using granulated activated carbon for adsorption removal of copper from aqueous solution was studied. The
influence of pH, amount of the adsorbent, contact time, and copper concentration on adsorption of copper was investigated.
The single-component equilibrium data on copper adsorption were analyzed using the Langmuir, Freundlich, Redlich—Peterson,
Temkin, and Toth adsorption isotherms. The adsorption process was followed by two simplified kinetic models including pseudo-first-
and pseudo-second-order equations. Kinetic parameters, rate constants, equilibrium sorption capacities, and the corresponding
correlation coefficients were calculated and examined for each kinetic model. It was shown that copper adsorption can be described
by the pseudo-second-order equation. 相似文献
50.
Pranay Amruth Maroju Ramakrishnan Ganesan Jayati Ray Dutta 《Macromolecular bioscience》2023,23(12):2300296
Surface derivatization is essential for incorporating unique functionalities into biodegradable polymers. Nonetheless, its precise effects on enzymatic biodegradation still lack comprehensive understanding. In this study, a facile solution-based method is employed to surface derivatize poly(ε-caprolactone) films and electrospun fibers with lysozyme, aiming to impart antimicrobial properties and examine the impact on enzymatic degradation. The derivatized films and fibers have shown high antibacterial efficacy against Escherichia coli and Staphylococcus aureus. Through gravimetric analysis, it is observed that the degradation rate experiences a slight decrease upon lysozyme derivatization. However, this reduction is effectively countered by the inclusion of Tween-20, as affirmed by isothermal titration calorimetry. Comparing films and fibers, the latter undergoes degradation at a more accelerated pace, coupled with a rapid decline in molecular weight. This study provides valuable insights into the factors influencing the degradation of surface-derivatized biopolymers through electrospinning, offering a simple strategy to mitigate biomaterial-associated infections. 相似文献