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排序方式: 共有225条查询结果,搜索用时 15 毫秒
41.
Bahadur J Sen D Mazumder S Paul B Bhatt H Singh SG 《Langmuir : the ACS journal of surfaces and colloids》2012,28(3):1914-1923
Micrometric grains of anisotropic morphology have been achieved by evaporation-induced self-assembly of silica nanoparticles. The roles of polymer concentration and its molecular weight in controlling the buckling behavior of drying droplets during assembly have been investigated. Buckled doughnut grains have been observed in the case of only silica colloid. Such buckling of the drying droplet could be arrested by attaching poly(ethylene glycol) on the silica surface. The nature of buckling in the case of only silica as well as modified silica colloids has been explained in terms of theory of homogeneous elastic shell under capillary pressure. However, it has been observed that colloids, modified by polymer with relatively large molecular weight, gives rise to buckyball-type grains at higher concentration and could not be explained by the above theory. It has been demonstrated that the shell formed during drying of colloidal droplet in the presence of polymer becomes inhomogeneous due to the presence of soft polymer rich zones on the shell that act as buckling centers, resulting in buckyball-type grains. 相似文献
42.
Subhajit Saha Bhaskar Das Nilesh Mazumder Anurag Bharati Kalyan Kumar Chattopadhyay 《Journal of Sol-Gel Science and Technology》2012,61(3):518-526
Magnesium aluminate nanoparticles with different chromium concentration (0–12%) have been synthesized by a citrate–nitrate
sol–gel route. X-ray diffraction studies confirmed the formation of single-phase cubic spinel structure excluding the presence
of any secondary phase. Crystallite size of the synthesized nanoparticles was found to increase from 8.5 to 19.8 nm with the
increase in Cr concentration. Fourier transformed infrared spectroscopic studies confirmed the presence of AlO6 group which led to the formation of MgAl2O4 spinel structure. Surface morphology of the sintered pellets was investigated with the help of a field emission scanning
electron microscope which revealed the existence of both grain and grain boundary along with their aggregates. The dielectric
constant, dielectric loss and ac conductivity were studied as a function of frequency of the applied electric field for different
composition and their nature of variation with frequency has been elucidated on the basis of Maxwell–Wagner interfacial model.
Impedance spectroscopy technique has been used to study the effect of grain and grain boundary on the electrical properties
of this spinel oxide. All the electrical parameters showed strong dependence on the nanostructural properties and were found
to vary consistently with the increase of doping concentration. 相似文献
43.
44.
Debnath Sanjoy Arif Wasim Roy Sourav Baishya Srimanta Sen Debarati 《Wireless Personal Communications》2022,124(2):1375-1421
Wireless Personal Communications - The performance of wireless communication network is important in emergency rescue operations while ensuring optimum usage of limited wireless resources. Due to... 相似文献
45.
Dr. Shaikh A. Ali Dr. Hasan A. Al-Muallem Dr. Mohammad A. J. Mazumder 《Chemical record (New York, N.Y.)》2023,23(2):e202200235
This article reviews the synthesis of polyzwitterions (PZs) (poly-carboxybetaines, -phosphonobetaines, and -sulfobetaines) having multiple pH-responsive centers. The synthesis follows the Butler cyclopolymerization protocol involving a multitude of diallylammonium salts and their copolymerization with SO2 and maleic acid. The PZs have been transformed into cationic-, anionic-polyelectrolytes, and polyampholytes under the influence of pH. Particular attention is given to the application of these polymers as antiscalants, mild steel corrosion inhibitors, components in constructing Aqueous Two-Phase Systems (ATPSs), and membrane modifiers. The ATPSs could be used to separate various biomolecules, including proteins. Many amphiphilic polymers incorporating a few mol % hydrophobic monomers have shown enhanced viscosities and could be suitable for applications in oil fields. The progress of applying Butler cyclopolymerization in reversible addition-fragmentation chain transfer (RAFT) chemistry has been discussed. Future works are expected to focus on RAFT cyclopolymerization to construct block copolymers. 相似文献
46.
Li Ding Mazumder P. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2004,12(9):910-925
Dynamic CMOS logic circuits are widely employed in high-performance VLSI chips in pursuing very high system performance. However, dynamic CMOS gates are inherently less resistant to noises than static CMOS gates. With the increasing stringent noise requirement due to aggressive technology scaling, the noise tolerance of dynamic circuits has to be first improved for the overall reliable operation of VLSI chips designed using deep submicron process technology. In the literature, a number of design techniques have been proposed to enhance the noise tolerance of dynamic logic gates. An overview and classification of these techniques are first presented in this paper. Then, we introduce a novel noise-tolerant design technique using circuitry exhibiting a negative differential resistance effect. We have demonstrated through analysis and simulation that using the proposed method the noise tolerance of dynamic logic gates can be improved beyond the level of static CMOS logic gates while the performance advantage of dynamic circuits is still retained. Simulation results on large fan-in dynamic CMOS logic gates have shown that, at a supply voltage of 1.6 V, the input noise immunity level can be increased to 0.8 V for about 10% delay overhead and to 1.0 V for only about 20% delay overhead. 相似文献
47.
Subham Ghosh Nabadyuti Barman Eliovardo Gonzalez-Correa Madhulika Mazumder Aryan Zaveri Raynald Giovine Alexis Manche Swapan K. Pati Raphaële J. Clément Premkumar Senguttuvan 《Advanced functional materials》2021,31(48):2105463
Vanadium multiredox-based NASICON-NazV2−yMy(PO4)3 (3 ≤ z ≤ 4; M = Al3+, Cr3+, and Mn2+) cathodes are particularly attractive for Na-ion battery applications due to their high Na insertion voltage (>3.5 V vs Na+/Na0), reversible storage capacity (≈150 mA h g−1), and rate performance. However, their practical application is hindered by rapid capacity fade due to bulk structural rearrangements at high potentials involving complex redox and local structural changes. To decouple these factors, a series of Mg2+-substituted Na3+yV2−yMgy(PO4)3 (0 ≤ y ≤ 1) cathodes is studied for which the only redox-active species is vanadium. While X-ray diffraction (XRD) confirms the formation of solid solutions between the y = 0 and 1 end members, X-ray absorption spectroscopy and solid-state nuclear magnetic resonance reveal a complex evolution of the local structure upon progressive Mg2+ substitution for V3+. Concurrently, the intercalation voltage rises from 3.35 to 3.45 V, due to increasingly more ionic V O bonds, and the sodium (de)intercalation mechanism transitions from a two-phase for y ≤ 0.5 to a solid solution process for y ≥ 0.5, as confirmed by in operando XRD, while Na-ion diffusion kinetics follow a nonlinear trend across the compositional series. 相似文献
48.
The main aim of this study is to select the optimal set of genes from microarray cancer datasets that contribute to the prediction of specific cancer types. This study proposes the enhancement of the feature selection filter algorithm based on Joe's normalized mutual information and its use for gene selection. The proposed algorithm is implemented and evaluated on seven benchmark microarray cancer datasets, namely, central nervous system, leukemia (binary), leukemia (3 class), leukemia (4 class), lymphoma, mixed lineage leukemia, and small round blue cell tumor, using five well‐known classifiers, including the naive Bayes, radial basis function network, instance‐based classifier, decision‐based table, and decision tree. An average increase in the prediction accuracy of 5.1% is observed on all seven datasets averaged over all five classifiers. The average reduction in training time is 2.86 seconds. The performance of the proposed method is also compared with those of three other popular mutual information–based feature selection filters, namely, information gain, gain ratio, and symmetric uncertainty. The results are impressive when all five classifiers are used on all the datasets. 相似文献
49.
D. K. Sengupta S. L Jackson A. P. Curtis W. Fang J. I. Malin T. U. Horton Q. Hartman H. C. Kuo S. Thomas J. Miller K. C. Hsieh I. Adesida S. L. Chuang M. Feng G. E. Stillman Y. C. Chang W. Wu J. Tucker H. Chen J. M. Gibson J. Mazumder L. Li H. C. Liu 《Journal of Electronic Materials》1997,26(12):1376-1381
We present experimental results on the growth and characterization of n-type InGaAs/InP quantum-well intersubband photodetectors
for use at 8.93 μm. High-quality InGaAs/InP multiple quantum wells were grown by gas source molecular beam expitaxy, and then
characterized by double-crystal x-ray diffraction and cross-sectional transmission electron microscopy. Based upon the structural
parameters determined by these methods, the photocurrent response spectra were simulated using a six-band effective bond-orbital
model. The theoretical results are in excellent agreement with experimental data. Additional important device characteristics
such as dark current, spectral response, and absolute responsivity are also presented. 相似文献
50.
Srikanta Bose Sudip K. Mazumder 《Solid-state electronics》2011,62(1):5-13
In this paper, a comprehensive simulation study is conducted to investigate the switching characteristics, gain, and breakdown voltage of a GaN-AlN-(4H)SiC based optically-triggered (OT) heterostructure vertical power semiconductor device (PSD). It comprises a 1 nm AlN buffer layer between the GaN and SiC heterointerface to achieve a reasonable compromise between lattice mismatch and lower forward drop. The results are compared with an all-(4H)SiC OT PSD. The all-(4H)SiC homostructure PSD is based completely on SiC and has no buffer layer. Further, it has the same structure, dimensions, and doping densities as that of the GaN-AlN-(4H)SiC based heterostructure PSD. While there have been studies on GaN-AlN-SiC lateral heterostructures, their primary focus has been on lateral conduction in the GaN structure with a thick (typically >300 nm) AlN buffer layer residing on top of a SiC substrate. Such an approach will not be useful for our vertical PSD because of the thick AlN layer. As such, first, a scaled molecular dynamics simulation (MDS) is carried out in DMol3 emulating the GaN-AlN-(4H)SiC heterointerface pn junction of the vertical PSD (with 1 nm AlN buffer) to assess the possibility of vertical conduction and stability of the heterointerface by calculating the density of states (DOS) at the Fermi level and the potential energy, respectively. Subsequently, detailed electrical simulations of the GaN-AlN-(4H)SiC and all-(4H)SiC vertical PSDs are carried out in Silvaco to assess their switching performances, gain, on-state drop, and blocking capabilities. The overall results indicate that, the GaN-AlN-(4H)SiC vertical PSD provides superior switching performance and optical absorption compared to the all-(4H)SiC vertical PSD, while the latter provides better gain. The blocking capabilities and forward drops are found to be comparable for both the PSDs from a practical standpoint. 相似文献