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排序方式: 共有146条查询结果,搜索用时 31 毫秒
1.
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
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The low pressure method of determination of carbon in metals and alloys was modified to include certain new techniques. An isopentane slush bath dispensed with the use of liquid oxygen and the usual McLeod gauge was replaced by a differential oil manometer, which increased the sensitivity. As little as 5 μg of carbon in CaCO3-quartz standards could be determined with a coefficient of variation of 16.0% which improved to 3.3% at the 100-μg level. The apparatus was used for the determination of carbon in metals such as uranium, zirconium and iron and in steels and cupronickel alloy. 相似文献
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K. V. Rajagopalan R. Kalyanaraman M. Sundaresan 《Journal of Thermal Analysis and Calorimetry》1988,34(1):329-334
The thermal decompositions of the sulphosalicylates of Mg(II), Ca(II) and Zn(II) have been investigated by means of TG and DTA. The preparation and analysis of these compounds are included. The possible decomposition reactions in the various stages and the final decomposition products are discussed. 相似文献
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K. V. Rajagopalan Ramprasad R. Kalyanaraman M. Sundaresan 《Journal of Thermal Analysis and Calorimetry》1989,35(4):1073-1077
Calcium chromite, CaCr2O4, was prepared and its purity and stoichiometry were ascertained by chemical analysis and X-ray diffraction methods. The thermal diffusivity, specific heat capacity and thermal conductivity of calcium chromite were measured by Laser Flash method using an Ulvac-Sinku Riko TC-3000 series instrument in the temperature range of 298 to 1100 K. The heat capacity data were utilised to calculate the thermodynamic parametersenthalpy increments, entropy increments and free energy increments—in the above temperature range.
Zusammenfassung Kalziumchromit, CaCr2O4, wurde hergestellt und seine Reinheit und stöchiometrische Zusammensetzung mit Hilfe chemischer Analyse und Röntgendiffraktionsmethoden ermittelt. Anhand eines Ulyac-Sinku Riko TC-3000 Gerätes wurde mit Laser Flash Verfahren die Temperaturleitfähigkeit, die spezifische Wärmekapazität und die Wärmeleitfähigkeit von Kalziumchromit im Temperaturbereich 298–1100 K bestimmt. Die Wärmekapazitätsdaten wurden zur Berechnung der thermodynamischen Größen (Enthalpie-, Entropie-, Freie Energieänderung) in obigem Temperaturbereich benutzt.
CaCr2O4, . , - TC-3000, 298–1100K , . , , .相似文献
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We present the results of acid–base experiments performed at the single ion (H+ or OH−) limit in ∼6 aL volume nanopores incorporating electrochemical zero-mode waveguides (E-ZMWs). At pH 3 each E-ZMW nanopore contains ca. 3600H+ ions, and application of a negative electrochemical potential to the gold working electrode/optical cladding layer reduces H+ to H2, thereby depleting H+ and increasing the local pH within the nanopore. The change in pH was quantified by tracking the intensity of fluorescein, a pH-responsive fluorophore whose intensity increases with pH. This behavior was translated to the single ion limit by changing the initial pH of the electrolyte solution to pH 6, at which the average pore occupancy 〈n〉pore ∼3.6H+/nanopore. Application of an electrochemical potential sufficiently negative to change the local pH to pH 7 reduces the proton nanopore occupancy to 〈n〉pore ∼0.36H+/nanopore, demonstrating that the approach is sensitive to single H+ manipulations, as evidenced by clear potential-dependent changes in fluorescein emission intensity. In addition, at high overpotential, the observed fluorescence intensity exceeded the value predicted from the fluorescence intensity-pH calibration, an observation attributed to the nucleation of H2 nanobubbles as confirmed both by calculations and the behavior of non-pH responsive Alexa 488 fluorophore. Apart from enhancing fundamental understanding, the approach described here opens the door to applications requiring ultrasensitive ion sensing, based on the optical detection of H+ population at the single ion limit.Visualizing dynamic change in the number of protons during electroreduction of protons in attoliter volume zero-mode waveguides. 相似文献