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101.
Pushkar Dasika Debadarshini Samantaray Krishna Murali Nithin Abraham Kenji Watanbe Takashi Taniguchi N Ravishankar Kausik Majumdar 《Advanced functional materials》2021,31(13):2006278
The gate-all-around nanowire transistor, due to its extremely tight electrostatic control and vertical integration capability, is a highly promising candidate for sub-5 nm technology nodes. In particular, the junctionless nanowire transistors are highly scalable with reduced variability due to avoidance of steep source/drain junction formation by ion implantation. Here a dual-gated junctionless nanowire p-type field effect transistor is demonstrated using tellurium nanowire as the channel. The dangling-bond-free surface due to the unique helical crystal structure of the nanowire, coupled with an integration of dangling-bond-free, high quality hBN gate dielectric, allows for a phonon-limited field effect hole mobility of 570 cm2 V−1 s−1 at 270 K, which is well above state-of-the-art strained Si hole mobility. By lowering the temperature, the mobility increases to 1390 cm2 V−1 s−1 and becomes primarily limited by Coulomb scattering. The combination of an electron affinity of ≈ 4 eV and a small bandgap of tellurium provides zero Schottky barrier height for hole injection at the metal-contact interface, which is remarkable for reduction of contact resistance in a highly scaled transistor. Exploiting these properties, coupled with the dual-gated operation, we achieve a high drive current of 216 μA μm−1 while maintaining an on-off ratio in excess of 2 × 104. The findings have intriguing prospects for alternate channel material based next-generation electronics. 相似文献
102.
B.C. Majumdar 《Wear》1973,24(1):15-22
Theoretical studies of rotating externally pressurized gas bearings with multiple pressure sources have been made. The solution is obtained for finite bearings by using pressure perturbation theory. Theoretical results are compared with experimental data. The theory allows good prediction of bearing load capacity, stiffness and attitude angle. 相似文献
103.
Cu-(Sn37Pb) and Cu-(Sn3.5Ag0.5Cu) solder joints were prepared at the same reflow temperature of 230 °C. The microstructural observation of the solder assemblies in scanning and transmission electron microscopes confirmed the presence of η-Cu6Sn5 in case of the former, and Cu3Sn + η-Cu6Sn5 for the latter in the reaction zone. The findings are correlated with the electrical and mechanical properties of the joints. Lead free solder-Cu joint exhibited lower reaction zone thickness and improved electrical conductivity (0.28 × 106Ω− 1 cm− 1) and shear strength ∼ 68MPa compared to conventional lead-tin solder-Cu joint. The latter showed electrical conductivity and shear strength of 0.22 × 106Ω− 1 cm− 1 and ∼ 55 MPa, respectively. The difference in reaction zone thickness is explained on the basis of melt superheat, with Sn being the primary diffusing species in the intermetallic layer. 相似文献
104.
We demonstrate two-dimensional multiplexed real-time, label-free antibody-antigen binding assays by optically detecting nanoscale motions of two-dimensional arrays of microcantilever beams. Prostate specific antigen (PSA) was assayed using antibodies covalently bound to one surface of the cantilevers by two different surface chemistries, while the nonreaction surfaces were passivated by poly(ethylene glycol)-silane. PSA as low as 1 ng/mL was detected while 2 mg/microl of bovine serum albumin induced only negligible deflection on the cantilevers. 相似文献
105.
106.
107.
Pal K Banthia AK Majumdar DK 《Journal of materials science. Materials in medicine》2007,18(9):1889-1894
The wound is a biosynthetic environment in which numerous cellular processes are interlinked in the process of repair. Modern
dressings are designed to facilitate wound healing rather than just to cover it. Hydrogel dressing can protect injured skin
and keep it appropriately moist to speed the healing process by absorbing exudates while maintaining the products of tissue
repair, including growth factor and lysosomes, in contact with the wound. The design and development of novel membrane of
hydrogels prepared by esterification of polyvinyl alcohol with gelatin were attempted. Contact angle of goat blood was determined.
The hydrogel was characterized by hemolysis test and water vapor transmission rate. Diffusion coefficient of salicylic acid
(SA) and gatifloxacin, a fourth generation fluoroquinolone, through the membrane was determined. Both the drugs were used
as model drug. Methyl tetrazolium dye assay of the membrane was done using L929 fibroblast cell line and mice splenocytes
to establish the biocompatibility of the membrane. The equilibrium goat blood-in-air contact angles of measured ester films
ranged from 56 to 60°. The hydrogel was found to be hemocompatible and moisture retentive indicating its possible use in moist
wound care. The diffusion coefficient of SA and gatifloxacin through the membrane was found to be 1.49 × 10−5 and 3.97 × 10−6 cm2/s respectively. The membrane was found to be compatible with the L929 fibroblast cell line and mice splenocytes. 相似文献
108.
Two approaches to the improvement of the performance of client–server systems, multithreading and scheduling of servers, are investigated. Both of these approaches are observed to have a significant impact on system performance. The use of multithreading improves throughput characteristics of systems, whereas the deployment of appropriate scheduling strategies at servers can produce a significant improvement in mean client response times. Based on a simulation model a number of basic questions that are important in the context of scheduling on nonmultithreaded, as well as multithreaded, systems are analyzed. Two important factors, monopolization of servers by large requests and software bottlenecks, are observed to be important in the context of scheduling on client–server systems. Both server scheduling, as well as multithreading, can be used to control these effects and lead to a higher system performance. Scheduling policies based on request characteristics are observed to perform well. A new request characteristic that is useful in the scheduling of client–server systems in the presence of software bottlenecks is proposed. Selection of both the server process, as well as the thread within the server, is required when multiple server, are co-located on the same CPU. A comparison between two scheduling approaches, single level and two level is presented in the paper. The results of this research are useful primarily in the design of operating systems for client–server systems and are also of interest to system designers and users. 相似文献
109.
The role of elastic shielding in reducing the local stress intensity factor (SIF) range during fatigue crack growth (FCG)
has been investigated using several single-ply composites with significantly different interfacial characteristics. The specimen
geometry necessitated the fatigue crack to initially grow through a monolithic matrix region before impinging on a set of
longitudinally oriented fibers. This facilitated the assessment of the crack shielding phenomenon from two regions: the region
where the crack interacted with the first fiber, and at high stress levels when nonbridging conditions prevailed in the fibrous
region. The extent of shielding was nearly identical in the two measurements for a given composite system. However, the shielding
contribution was found to depend on the interface bond strength; the interface with the highest bond strength provided the
largest degree of crack retardation in both cases. A preliminary assessment of this dependency has been provided. The implications
of using the correct shielding factor on both fiber strength and life prediction are also discussed.
This article is based on a presentation made in the symposium “Fatigue and Creep of Composite Materials” presented at the
TMS Fall Meeting in Indianapolis, Indiana, September 14–18, 1997, under the auspices of the TMS/ASM Composite Materials Committee. 相似文献
110.
The transverse creep response of an 8-ply SiC (SCS-6)/Ti-6Al-4V composite was measured at 482 °C from 69 to 276 MPa. Creep
samples with fibers exposed at the edges as well as specimens with fully embedded fibers were tested under stepped loading
conditions with increasing load. The response of each sample geometry was compared with creep data from the unreinforced matrix
(‘neat’ material). The samples with exposed fiber ends exhibited minimum creep rates that were higher than those of the neat
material at all stresses, and the stress exponent was slightly large than the neat material. The embedded fiber samples possessed
minimum creep rates that were smaller than the neat material at low stresses (<115 MPa), but became equivalent to the exposed
fiber data at the highest stress (276 MPa). The apparent stress exponent for the embedded fiber composite was significantly
larger than the neat material. The exposed fiber test data were well represented by a standard Crossman analysis, where the
fibers were considered to have completely debonded. A stress singularity in the interfacial region at the sample edge is responsible
for this behavior. The Crossman model was modified to incorporate the effect of a finite interface strength (120 MPa), and
this was used to describe the response of the samples with embedded fibers. A reasonable fit to this representation was obtained.
However, the measured minimum creep rate at the lowest stress was significantly lower than that predicted by the Crossman
analysis for fully bonded fibers.
This article is based on a presentation made in the symposium “Fatigue and Creep of Composite Materials” presented at the
TMS Fall Meeting in Indianapolis, Indiana, September 14–18, 1997, under the auspices of the TMS/ASM Composite Materials Committee. 相似文献