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131.
132.
B. Karmakar M. R. Gokhale A. P. Shah B. M. Arora D. T. N. de Lang A. de Visser L. A. Ponomarenko A. M. M. Pruisken 《Physica E: Low-dimensional Systems and Nanostructures》2004,24(3-4):187-210
In experiments on electron transport, the macroscopic inhomogeneities in the sample play a fundamental role. In this paper and a subsequent one, we introduce and develop a general formalism that captures the principal features of sample inhomogeneities (density gradients, contact misalignments) in the magnetoresistance data taken from low-mobility heterostructures. We present detailed assessments and experimental investigations of the different regimes of physical interest, notably the regime of semiclassical transport at weak magnetic fields, the plateau–plateau transitions as well as the plateau–insulator transition that generally occurs at much stronger values of the external field only.It is shown that the semiclassical regime at weak fields plays an integral role in the general understanding of the experiments on the quantum Hall regime. The results of this paper clearly indicate that the plateau–plateau transitions, unlike the plateau–insulator transition, are fundamentally affected by the presence of sample inhomogeneities. We propose a universal scaling result for the magnetoresistance parameters. This result facilitates, amongst many other things, a detailed understanding of the difficulties associated with the experimental methodology of H.P. Wei et al. in extracting the quantum critical behavior of the electron gas from the transport measurements conducted on the plateau–plateau transitions. 相似文献
133.
F. C. Jain S. K. Islam M. Gokhale 《Journal of Infrared, Millimeter and Terahertz Waves》1992,13(10):1459-1469
A novel metal-SiO2-InP MISFET (metal-insulator-semiconductor field effect transistor) structure is proposed. This device incorporates a modulation doped channel and the self-aligned gate feature of Si MOSFETs. The modulation doping provides very high electron mobility and the self-alignment of gate, source and drain provides high packing density. Analytical results on current-voltage and transconductance characteristics are presented. Significant enhancement in high frequency performance over conventional MISFETs, employing SiO2 as an insulator, is reported. 相似文献
134.
A kinematical model is necessary for understanding the gross structure of the coronal magnetic field and its slow evolution
in consistency with the small scale structure of the photospheric fields. Here we have developed a preliminary phenomenological
model in terms of flux tubes of flux amounts ≈ 1017 − 1018.5 Mx rising across the inner corona in the form of arches and opening out in the outer corona. In contrast to Parker’s estimate,
this model is consistent with the observed spans of the chromospheric fibrils and x-ray arches. It is also consistent with
the number of flux tubes present above the photosphere as estimated from the observed abundance of spicules. 相似文献
135.
Santosh Kumar Patnaik Swapna Banerjee 《Analog Integrated Circuits and Signal Processing》2012,70(3):293-302
This paper presents the symbolic noise modeling, analysis and optimization of an Input Buffer designed using RFCMOS technology,
intended to be used in a high speed Track and Hold Amplifier (THA). The symbolic noise modeling and analysis are carried out
by modeling each RF-MOSFET present in the Input Buffer by its nullor equivalent noise model. This helps in better understanding
the noise involvement with the circuit and its optimization. All the extrinsic and intrinsic components associated with the
RF-MOSFET used for the symbolic noise analysis are obtained using parameter extraction technique. The parameter extraction
and symbolic noise analysis are done using MATLAB. The results obtained through MATLAB simulation are in good agreement with
the results obtained from SPICE. 相似文献
136.
Byrne N Rodoni B Constable F Varghese S Davis JH 《Physical chemistry chemical physics : PCCP》2012,14(29):10119-10121
We report on the use of protic ionic liquids, pILs, as solvents for the solubilisation and stabilization of viruses. We show that the shelf life of the pIL stabilized tobacco mosaic virus is significantly enhanced when compared to traditional phosphate buffer. This has new opportunities for the preparation, characterization and storage of viruses and virus based technologies. 相似文献
137.
Swaroop PS Raut GN Gonnade RG Verma P Gokhale RS Reddy DS 《Organic & biomolecular chemistry》2012,10(28):5385-5394
First synthesis of diaportheone B, an antituberculosis agent isolated from endophytic fungus Diaporthe sp. P133 is reported using two complementary routes, a one step and a three-step sequence. The absolute configuration of diaportheone B was determined by using X-ray crystal structure analysis of its dibromo derivative. In addition, we have prepared several close analogues of diaportheone B and determined their anti-TB potential using Alamar-blue assay (H(37)Rv). 相似文献
138.
Yu Z Gaerig V Cui Y Kang H Gokhale V Zhao Y Hurley LH Mao H 《Journal of the American Chemical Society》2012,134(11):5157-5164
The discovery of G-quadruplexes and other DNA secondary elements has increased the structural diversity of DNA well beyond the ubiquitous double helix. However, it remains to be determined whether tertiary interactions can take place in a DNA complex that contains more than one secondary structure. Using a new data analysis strategy that exploits the hysteresis region between the mechanical unfolding and refolding traces obtained by a laser-tweezers instrument, we now provide the first convincing kinetic and thermodynamic evidence that a higher order interaction takes place between a hairpin and a G-quadruplex in a single-stranded DNA fragment that is found in the promoter region of human telomerase. During the hierarchical unfolding or refolding of the DNA complex, a 15-nucleotide hairpin serves as a common species among three intermediates. Moreover, either a mutant that prevents this hairpin formation or the addition of a DNA fragment complementary to the hairpin destroys the cooperative kinetic events by removing the tertiary interaction mediated by the hairpin. The coexistence of the sequential and the cooperative refolding events provides direct evidence for a unifying kinetic partition mechanism previously observed only in large proteins and complex RNA structures. Not only does this result rationalize the current controversial observations for the long-range interaction in complex single-stranded DNA structures, but also this unexpected complexity in a promoter element provides additional justification for the biological function of these structures in cells. 相似文献
139.
Amarendra Patra Alok K. Mitra Swapna Biswas Chitra Das Gupta Tapan K. Chatterjee K. Basu A. K. Barua 《Magnetic resonance in chemistry : MRC》1981,17(4):301-302
Carbon-13 signal assignments of the labdane diterpenoids phlogantholide-A, its diacetate and isophlogantholide-A are reported. The assignments of the 13C NMR signals of 14-deoxyandrographolide and its diacetate, made earlier, have now been confirmed by lanthanide shift studies on the former and also by 13C spectral studies on anhydroandrographolide diacetate and 14-deoxy-11,12-didehydroandrographolide diacetate. 相似文献
140.
P.D. Gokhale A.P. Joshi R. Sahni V.G. Naik N.P. Damodaran U.R. Nayak S. Dev 《Tetrahedron》1976,32(12):1391-1393
Photo-irradiation of longibornyl iodide in n-heptane containing some triethylamine as scavenger for hydrogen iodide, furnished rearranged hydrocarbons (longifolene, longicyclene and longiborn-8-ene). Citronellyl iodide, under similar conditions, led to simple elimination (to furnish 2,6-dimethylocta-2,7-diene) and π-participation (to yield trans-p-menth-8-ene) to almost equal extent. A possible mechanism for these reactions is discussed. 相似文献