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Meandering Gate Edges for Breakdown Voltage Enhancement in AlGaN/GaN High Electron Mobility Transistors
No full textHerein, a unique device-design strategy is reported for increasing the breakdown voltage and hence Baliga figure of merit (BFOM) of III-nitride high electron mobility transistors (HEMTs) by engineering the gate edge toward the drain. The breakdown of such devices with meandering gate-drain access region (M-HEMT) are found to be 62 more compared with that of conventional HEMT whereas the on-resistance suffers by 76, leading to an overall improvement in the BFOM for by 28. The 3D technology computer-aided design simulations show that the decrease in the peak electric field at the gate edge was responsible for increased breakdown voltage
Investigation of Recessed Junctionless Double Gate MOSFET for Radio Frequency Applications
No full textJunctionless Metal Oxide Semiconductor Field-Effect Transistor (JL MOSFET) is one of the promising candidate to replace the junction based MOSFET for upcoming technology nodes. Semiconductor industries are continuously urging for large ON current with the low OFF current and low specific on resistance. However, high ON current is achieved in Conventional (Conv.) JL DG MOSFET by using high doping concentration at the cost of high OFF current which leads depletion mode operation. Moreover, low doping, narrow channel thickness and high work function gate materials are using to operate Conv. JL DG MOSFET in enhancement mode (Vth > 0Â V for N-JL DG MOSFET, Vth < 0Â V for P-JL DG MOSFET) but ON current is reduced in all above mentioned solutions. To overcome the above mentioned problems, a new architecture is developed called Recessed JL DG MOSFET. In Recessed JL DG MOSFET silicon region is recessed under the gate region and some gate portion is extended towards source and drain region. Recessed JL DG MOSFET shows the same ON current as achieved in Conv. JL DG MOSFET with very low OFF current (leakage current) by considering high doping concentration. Surface potential, electron density, energy band distribution, drain current have been investigated to proof the enhancement mode operation of Recessed JL DG MOSFET. Figure of Merits (FOMs) for RF performance such as Trans-conductance, capacitance and intrinsic power gain (S21), Trans-conductance frequency product (TFP), Gain frequency product (GFP) and Gain trans-conductance frequency product (GTFP) have also investigated of Recessed JL DG MOSFET
Magnetocaloric effect in molecular spin clusters and their assemblies: Exact and Monte Carlo studies using exact cluster eigenstates
No full textFrustrated magnetic molecules are promising alternatives to refrigerant materials for low temperature magnetic refrigeration. We investigate the magnetocaloric effect (MCE) in un-frustrated and frustrated spin clusters formed from spin chains of six sites, with site spins s=1,3/2 and 2 possessing site diagonal anisotropies and anisotropic exchange interactions, using exact diagonalization method. We also study MCE in spin clusters, on a chain, a 2-D square lattice and a 3-D cubic lattice with spin-dipolar interactions by a Monte Carlo method in spin-1 systems which uses exact eigenstates of a cluster. The magnetocaloric effect is closely related to the magnetic Grüneisen parameter �H. In this paper, we compute the magnetic Grüneisen parameter �H, and study its dependence on exchange anisotropy and spin-dipolar interaction. With increase of exchange anisotropy, the maxima in �H shifts to higher magnetic fields and becomes a sharp singularity. The singularities in �H correlate with cusps in the entropy as a function of magnetic field strength, and with crossover in the magnetization in the ground state in isolated clusters. The first maximum in �H shifts to lower fields as we increase spin-dipolar interaction. The first maximum in �H also shifts to lower magnetic field strength as the magnitude of the site spin increases. We show the dependence of �H on the dimensionality of the lattice for a fixed lattice constant
Advances in liposomal drug delivery to cancer: An overview
No full textLiposomes are biodegradable and biocompatible lipid bilayer vesicles which are widely exploited as preferred carriers for smart delivery of both hydrophobic as well as hydrophilic bioactives. Structural fabrication of liposomes for ligand anchoring, long-circulation and stimuli-responsiveness are advancing features to meet the needs of clinical and industrial demands. Recent studies report newer developments in multipronged liposomes for synchronized theranostic manifestations in cancer treatment. This review gives an insight to advances in ligand targeted liposomes (like folate, mannose, transferrin, hyaluronic acid, antibody, aptamer, and peptide, etc.), stimuli-triggered liposomes (stimuli such as pH, temperature, and hypoxia, etc.) and liposomes mediated autophagy modulation, and theranostic liposomes for the diagnosis and treatment of cancer. It also includes patents, clinical studies and marketed liposomal products. This assemblage of advances would be of great interest to budding scientists and pharmaceutical companies engaged in the development of liposomes
Mesomorphic Sugar-Coated Polydiacetylene Polymers
No full textThe derivatization of a polydiacetylene (PDA) polymer with free hydroxyl groups containing sugars leads to amphiphilicity of the polymer and the emergence of thermotropic liquid crystalline behavior, in addition to the thermochromatic properties. The diacetylene monomers, incorporated with mono- and disaccharides, exhibit mono- and/or enantiotropic phase behavior in a wide temperature range. Structural characterization and modeling studies reveal a lamellar arrangement and interdigitization of the molecules in the mesophase. The importance of the amphiphilicity as a source to induce mesomorphic behavior in PDA polymers is emphasized
Modelling of shaft based processes
No full textShaft based processes are used in many disciplines such as in metallurgical and chemical engineering. However, their performance suffers due to the lack in understanding of solid and gas flow thus the heat and mass transfer inside the shaft. Therefore, in this article the study of solid flow has been carried out in presence of gas flow under counter-current condition. A slow moving packed bed, inside the reactor, has been considered. Particles are discharged from the bottom and gas is injected laterally. Particles have been modelled using Discrete Element Method (DEM) and gas flow has been modelled using continuum based fluid flow equations. The effect of various parameters (like particle size, gas flow rate, solid discharge rate etc.,) on the residence time of solid particles has been studied in detail. It is found that gas flow is not symmetric inside the reactor due to asymmetric distribution of voids
Sensor placement and resource allocation for energy harvesting IoT networks
No full textOptimal sensor selection for source parameter estimation in energy harvesting Internet of Things (IoT) networks is studied in this paper. Specifically, the focus is on the selection of the sensor locations which minimizes the estimation error at a fusion center, and to optimally allocate power and bandwidth for each selected sensor subject to a prescribed spectral and energy budget. To do so, measurement accuracy, communication link quality, and the amount of energy harvested are all taken into account. The sensor selection is studied under both analog and digital transmission schemes from the selected sensors to the fusion center. In the digital transmission case, an information theoretic approach is used to model the transmission rate, observation quantization, and encoding. We numerically prove that with a sufficient system bandwidth, the digital system outperforms the analog system with a possibly different sensor selection. The design problem of interest is a Boolean non convex optimization problem, which is solved by relaxing the Boolean constraints. To efficiently round the obtained relaxed solution, we propose a randomized rounding algorithm which generalizes the existing algorithm
Structural elucidation, theoretical insights and thermal properties of three novel multicomponent molecular forms of gallic acid with hydroxypyridines
No full textDevelopment of novel drug for manipulating the physicochemical properties of the API by obtaining their multicomponent forms is a challenging task in the pharmaceutical industry. Novel multicomponent crystal forms of gallic acid with three hydroxypyridines have been prepared by liquid assisted grinding and slow evaporation of the solvent. Preliminary PXRD and FTIR characterizations were carried out to confirm the interactions between the components, then the three dimensional molecular structures were confirmed through single crystal X-ray diffraction method. Structural studies clearly revealed the three distinct molecular crystal forms of gallic acid with hydroxypyridines. The molecular structures exhibit O�H�O, N�H�O and C�H�O intermolecular hydrogen bond interactions, which results different supramolecular motifs. Further, intermolecular interactions were quantified through Hirshfeld surface analysis, which revealed the dominance of O�H and H�H interactions. Computation of interaction energies between the molecules and analysis of three dimensional energy frameworks quantifies the molecular packing. The density functional theory calculations were employed to optimize the structural coordinates, which substantiate the experimental results. Low value of HOMO-LUMO energy gap signifies the promising electronic properties of the molecules. The chemical reactive sites were further identified on the molecular electrostatic potential surface. Finally, thermal properties of the crystals were studied using thermogravimetric analysis
A universal stress protein in Mycobacterium smegmatis sequesters the cAMP-regulated lysine acyltransferase and is essential for biofilm formation
No full textUniversal stress proteins (USPs) are present in many bacteria, and their expression is enhanced under various environmental stresses.Wehave previously identified a USP in Mycobacterium smegmatis that is a product of the msmeg₄₂₀₇ gene and is a substrate for a cAMP-regulated protein lysine acyltransferase (KATms; MSMEG5458). Here, we explored the role of this USP (USP4207) in M. smegmatis and found that its gene is present in an operon that also contains genes predicted to encode a putative tripartite tricarboxylate transporter (TTT). Transcription of the TTT-USP4207 operon was induced in the presence of citrate and tartrate, perhaps by the activity of a divergent histidine kinase-response regulator gene pair. A USP4207-deleted strain had rough colony morphology and reduced biofilm formation compared with the WT strain; however, both normal colony morphology and biofilm formation were restored in a δUSP4207δkatms strain. We identified several proteins whose acetylation was lost in the δkatms strain, and whose transcript levels increased in M. smegmatis biofilms along with that of USP4207, suggesting that USP4207 insulates KATms from its other substrates in the cell.Wepropose that USP4207 sequesters KATms from diverse substrates whose activities are down-regulated by acylation but are required for biofilm formation, thus providing a defined role for this USP in mycobacterial physiology and stress responses
Influence of the chemical functionalization of carbon nanotubes on low temperature ac conductivity with polyaniline composites
No full textWe report the ac conductivity measurement of polyaniline (PANI) composites with carbon nanotubes (CNT) and functionalized carbon nanotubes (fCNT) with different degrees of functionalization from 300 K-4.2 K in the frequency range 40 Hz-5 MHz. The ac conductivity of PANI follows the universal power law and the charge transport is dominated by small polaron tunneling. In the CNT/PANI composite, metallic behaviour emerges, and ac conductivity does not obey the power law which is explained by the Drude model. Due to the chemical functionalization of CNT, disordered semiconducting behaviour appears in the transport below 50 K and follows the Johnscher's power law. The enhancement of polaron formation due to the polar interaction between fCNT and PANI is reflected in the ac conductivity of the composites. The charge transport is manifested by single electron tunneling for a lower degree of fCNT/PANI (6 h) composite which changes to small polaron tunneling transport for a higher degree of fCNT/PANI (48 h) composite. The dc conductivity behaviour is explained by Mott's VRH model and the characteristic Mott temperature increases with an increasing degree of chemical functionalization