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91.
M. Mondal S. Bhattacharya K. P. Ghatak 《Applied Physics A: Materials Science & Processing》1987,42(4):331-336
An attempt is made to formulate the gate capacitance of MOS structures of Kane-type semiconductors under magnetic quantization, without any approximations of weak or strong electric field limits, on the basis of the fourth-order effective mass theory and taking into account the interactions of the conduction, light-hole, heavy-hole, and split-off bands. It is found, taking n-channel Hg1–x
Cd
x
Te as an example, that the gate capacitance exhibits spiky oscillations with changing magnetic field, which is in qualitative agreement with experimental observations, reported elsewhere, in MOS structures of the same semiconductor. The corresponding results for n-channel inversion layers on parabolic semiconductors are also obtained from the expressions derived. 相似文献
92.
Aishik Bhattacharya Arnab Kumar Nath Arnab Ghatak Abhijit Nayek Souvik Dinda Rajat Saha Somdatta Ghosh Dey Abhishek Dey 《Angewandte Chemie (International ed. in English)》2023,62(10):e202215235
The reduction of SO2 to fixed forms of sulfur can address the growing concerns regarding its detrimental effect on health and the environment as well as enable its valorization into valuable chemicals. The naturally occurring heme enzyme sulfite reductase (SiR) is known to reduce SO2 to H2S and is an integral part of the global sulfur cycle. However, its action has not yet been mimicked in artificial systems outside of the protein matrix even after several decades of structural elucidation of the enzyme. While the coordination of SO2 to transition metals is documented, its reduction using molecular catalysts has remained elusive. Herein reduction of SO2 by iron(II) tetraphenylporphyrin is demonstrated. A combination of spectroscopic data backed up by theoretical calculations indicate that FeIITPP reduces SO2 by 2e−/2H+ to form an intermediate [FeIII−SO]+ species, also proposed for SiR, which releases SO. The SO obtained from the chemical reduction of SO2 could be evidenced in the form of a cheletropic adduct of butadiene resulting in an organic sulfoxide. 相似文献
93.
Verma MK Ganneboyina SR R VR Ghatak A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):2248-2251
Rapid mixing of liquids is important for most microfluidic applications. However, mixing is slow in conventional micromixers, because, in the absence of turbulence, mixing here occurs by molecular diffusion. Recent experiments show that mixing can be enhanced by generating transient flow resulting in chaotic advection. While these are planar microchannels, here we show that three-dimensional orientations of fluidic vessels and channels can enhance significantly mixing of liquids. In particular, we present a novel, multihelical microchannel system built in soft gels, for which the helix angle, helix radius, axial length, and even the asymmetry of the channel cross section are easily tailored to achieve the desired mixing. Mixing efficiency increases with helix angle and asymmetry of channel cross section, which leads to orders of magnitude reduction in mixing length over conventional mixers. This new scheme of generating 3D microchannels will help in miniaturization of devices, process intensification, and generation of multifunctional process units for microfluidic applications. 相似文献
94.
In this paper, we present two approximations for the fundamental mode of graded-index fibres. The first is a one-parameter analysis which involves computational effort comparable to that involved in the Gaussian approximation and yet gives much better results. The second is a two-parameter analysis which gives much better results than other existing approximations for all values ofV for most graded-index fibres.Visiting from Physics Department, Ravenshaw College, Cuttack 753003, India. 相似文献
95.
96.
Patil S Malasi A Majumder A Ghatak A Sharma A 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):42-46
Although the viscoelasticity or tackiness of a pressure-sensitive adhesive gives it strength owing to energy dissipation during peeling, it also renders it nonreusable because of structural changes such as the formation of fibrils, cohesive failure, and fouling. However, an elastic layer has good structural integrity and cohesive strength but low adhesive energy. We demonstrate an effective composite adhesive in which a soft viscoelastic bulk layer is imbedded in a largely elastic thin skin layer. The composite layer is able to meet the conflicting demands of the high peel strength comparable to the viscoelastic core and the structural integrity, reusability, and antifouling properties of the elastic skin. Our model adhesive is made of poly(dimethylsiloxane), where its core and skin are created by varying the cross-linking percentage from 2 to 10%. 相似文献
97.
Saheli Ganguly Kausik Dana Sankar Ghatak 《Journal of Thermal Analysis and Calorimetry》2010,100(1):71-78
Three n-alkylammonium salts of varying alkyl chain length were ion exchanged with montmorillonites (MMT) of different cation exchange
capacity (CEC). The intercalated MMTs were characterized by thermogravimetry (TG), XRD, FTIR to acquire an insight into the
intergallery structural arrangement of the organic alkylammonium cations (AAC). The increment in the intergallery spacing
from XRD pattern was correlated with chain length and interlayer arrangement of AAC. Multiple organic mass-loss stages in
thermogravimetric analysis indicate two types of anchorage of AAC in intercalated clay. CEC of MMT was found to influence
the intergallery confinement and excess adsorption of AAC. 相似文献
98.
An expeditious total synthesis of (±)-sempervirol (7) (±)-sugiol (8), and (±)-xanthopherol methyl ether (9) by extension of a simple general route is described. The stereochemical results of the cyclialkylation of 2-(2-p) and (2-m-isopropylphenylethyl)-1,3,3-trimethylcyclohexanols (1e) and (1f) follow the general pattern observed earlier. 相似文献
99.
A number of total syntheses of (±) - podocarpic acid (i) have been described1 King, King and Topliss2 first identified one of the products from nonstereo-selective cyclization of (4) with polyphosphoric acid as (±)- ethyl-O-methylpodocarpate (2) and correlated that with the corresponding acid (3), prepared in an extremly poor yield (ca 0.4%)3 by Bhattacharyya3, and Haworth and Moore4 by cyclization of (5) with a mixture of sulfuric acid and acetic acid. More recently Mancini, Fringuelli and Taticchi5 prepared (3) (in 4.8% yield) by repeating Howorth1 s cyclization of (4). In continuation of our studies on cyclialky- 相似文献
100.
Summary We have studied the Einstein relation of the diffusivity-mobility ratio of the carriers in Bi in accordance with the McClure
and Choi, the hybrid, the Cohen, the Lax and the ellipsoidal parabolic energy band models under magnetic quantization, cross-field
configuration, quantum wells, electric-field-aided quantum wells, quantum wells under cross-field configuration, quantumwell
wires, electrifield-aided quantum well wires and quantum well wires under cross-field configurations, respectively. The Einstein
relation varies with various physical variables in different manners which are totally band structure dependent. We have also
suggested an experimental method of determining the diffusivity-to-mobility ratio in degenerate materials having arbitrary
dispersion laws. 相似文献