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461.
Shashwati Sen DK Aswal Ajay Singh TV Chandrasekhar Rao KP Muthe JC Vyas LC Gupta SK Gupta VC Sahni 《Pramana》2002,58(5-6):867-870
The MgB2 superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties.
The upper critical field, irreversibility line and critical current density have been determined using magnetization data.
The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition.
The surface analysis using X-ray photoelectron spectroscopy shows that MgB2 is sensitive to atmospheric degradation. 相似文献
462.
We examine nonlocal effects between normal-metal gold probes connected by superconducting aluminum. For highly transparent Au/Al interfaces, we find nonlocal voltages that obey a spatial and temperature evolution distinct from the nonequilibrium charge imbalance signals usually found in such systems. These voltages are consistent with the predicted effects of crossed Andreev reflection and elastic cotunneling, effects that involve coherent correlations between spatially separated electrons. 相似文献
463.
We report magnetization, dielectric and dc transport properties of La(2)NiMnO(6) nanoparticles. Both dc and ac magnetization measurements indicated a metastable magnetic behaviour with random ferromagnetic and antiferromagnetic interactions below 110 K; critical slow-down, memory and rejuvenation properties signify the spin glass nature. The dc resistivity shows a semiconducting nature but the temperature dependent magnetoresistance (MR) shows a peak at the spin glass transition. The colossal dielectric property and its frequency dependence were interpreted using the Maxwell-Wagner (MW) interfacial polarization model. Impedance analysis along with magnetodielectric (MD) and magnetoresistance (MR) indicates that the observed MD originates from the combined effect of MR and MW interfacial polarization. 相似文献
464.
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467.
Chandrasekhar V Azhakar R Bickley JF Steiner A 《Chemical communications (Cambridge, England)》2005,(4):459-461
A novel linear trinuclear magnesium complex (P(S)[N(CH3)N=CHC6H4-o-O]3)2Mg3 was prepared by the reaction of P(S)[N(CH3))N=CHC6H4-o-OH]3 with MgCl2 x 6H2O in the presence of triethylamine. The trinuclear magnesium complex is fluorescent in solution as well as in the solid-state. 相似文献
468.
Sudha R Panda M Chandrasekhar J Balaram P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(21):4980-4991
Apolar, neutral peptides have been shown to ionize extremely well under the conditions used for electrospray ionization mass spectrometry (ESIMS). Peptides for which the conformations have been independently determined in solution and in crystals have been examined by ESIMS. Studies of peptide helices ranging from 7 to 18 residues reveal that shorter helices yield exclusively singly charged ions, while in larger helices multiply charged species are detectable. Multiple sites for protonation/metallation are introduced in the helix by proline insertion or by changing the chirality in the residue. The preferred site of cation binding to helices may be the C-terminus end, where three free CO groups are available for chelation. Ab initio and DFT calculations at several levels have been carried out for the binding of H+, Li+, Na+, and K+ to CHO-(Gly)3)-OMe. The results reveal that metallation in helices is favoured by chelation to carbonyl groups at the C-terminus, while protonation involved two carbonyl groups and thus favour a 10-membered cyclic hydrogen-bonded structure. In -strands, metallation/protonation occurs at isolated carbonyl groups. Collision induced fragmentation of hydrophobic peptides under ESI conditions reveals that helix fragmentation occurs predominantly from the C-terminus, while in -hairpins cleavage occurs simultaneously at multiple sites. 相似文献
469.
Rotation-free transmission measurements governed by ground-state recovery of coumarin 102, coumarin 138 and coumarin 339 dyes
in ethanol solutions were performed for the first time by pump-probe technique using 35 ps pulses of Nd:YAG laser at 355 nm.
Recovery of absorption is characterized by simple exponential behaviour with relaxation times of 4.0, 3.7 and 3.0 ns respectively
for C 102, C 138 and C 339. These values are comparable to the lifetimes of the first excited singlet states. 相似文献
470.
The thermal conductivity of thin films of superconducting Pb-3 at. % In alloy is measured in the normal and the superconducting states. The ratio of the electronic thermal conductivity in the superconducting state Kes to that in the normal state Ken is found to be in good agreement with the Bardeen, Rickayzen and Tewordt theory with 2?O = 4.36 kTc. 相似文献