Waves in generalized thermo-viscoelastic infinite continuum with cylindrical cavity due to three-phase-lag time-nonlocal heat transfer

Abstract

Generalized thermoelastic interactions due to three-phase-lag time-nonlocal heat transfer in a Kelvin-Voigt type infinitely extended visco-thermoelastic continuum with cylindrical cavity has been investigated. The two-temperature generalized thermoelasticity theory has also been taken into account. The problem has been solved in the domain of Laplace on the assumption that the surface of the cavity is free from traction and is subjected to a smooth and time-dependent-heating effect. Laplace inversion of the transformed solutions has been carried out numerically. The obtained numerical data for different considerations are plotted in graphs to study the effects of time-nonlocal parameter, two-temperature parameter and visco-thermoelastic relaxation parameter on different thermoelastic quantities of physical interest.     

Industrial scale synthesis of few-layer graphene nanosheets (FLGNSs): an exploration of electrochemical exfoliation approach

Journal of Applied Electrochemistry - Industrial scale manufacturing with tunable properties of graphene nano-sheets has been a practical concern in many applications. This study focuses on, a...     

Mixed-resolution HEVC based multiview video codec for low bitrate transmission

Multimedia Tools and Applications - There has been increasing demand for multiview video transmission over band limited channel over past years and various techniques have been proposed to fulfil...     

A comparative study of SiAlON ceramics

Two different varieties of Si₃N₄ powders were used to prepare SiAlON ceramics. 100% β-Si₃N₄ was used from refractory grade powders (B1) and another purer 98% α-Si₃N₄ (50A) powder was used to prepare the SiAlON samples. Since SiC + SiAlON composites reportedly perform better, batches were prepared with 15% SiC addition to the refractory powders (B1) and 17.5% SiC was added to the other SiAlON composition (50A). The samples were gas pressure sintered at 1840 °C and at 22 bar with 1 h dwelling time. Thereby, we could achieve 97–98% theoretical density. The hardness was recorded 14–17 GPa while fracture toughness varied from 4.3 to 5 MPa m^1/2. Fretting experiments showed initial running-in period of 300 cycles for all the tribo-couples. After which, the steady state coefficient of frictions (COF) were achieved. Steel ball of 10 mm diameter, fretting against 50A composition, showed 0.6 average steady state COF while the same composition while fretting against alumina ball of the same diameter, showed 0.57 average steady state COF. Results have been compared with SiAlON composition derived from refractory powder (B1) and found that the 50A composition performs better under identical test conditions. Moreover, cytocompatibility study also suggests that the investigated 50A composition can be used as substrate to support cell adhesion and proliferation of L929 mouse fibroblast cell lines whereas B1 composition derived from refractory powders are toxic in nature.     

Thermoelectric Properties of Two-Phase PbTe with Indium Inclusions

The thermoelectric figure of merit (zT) can be increased by introduction of additional interfaces in the bulk to reduce the thermal conductivity. In this work, PbTe with a dispersed indium (In) phase was synthesized by a matrix encapsulation technique for different In concentrations. x-Ray diffraction analysis showed single-phase PbTe with In secondary phase. Rietveld analysis did not show In substitution at either the Pb or Te site, and this was further confirmed by room-temperature Raman data. Low-magnification (~1500×) scanning electron microscopy images showed micrometer-sized In dispersed throughout the PbTe matrix, while at high magnification (150,000×) an agglomeration of PbTe particles in the hot-pressed samples could be seen. The electrical resistivity (ρ) and Seebeck coefficient (S) were measured from 300 K to 723 K. Negative Seebeck values showed all the samples to be n-type. A systematic increase in resistivity and higher Seebeck coefficient values with increasing In content indicated the role of PbTe-In interfaces in the scattering of electrons. This was further confirmed by the thermal conductivity (κ), measured from 423 K to 723 K, where a greater reduction in the electronic as compared with the lattice contribution was found for In-added samples. It was found that, despite the high lattice mismatch at the PbTe-In interface, phonons were not scattered as effectively as electrons. The highest zT obtained was 0.78 at 723 K for the sample with the lowest In content.     

Encapsulated microbubbles and echogenic liposomes for contrast ultrasound imaging and targeted drug delivery

Micron- to nanometer-sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being developed for diagnostic imaging and ultrasound mediated drug/gene delivery. This review provides an overview of the current state of the art of the mathematical models of the acoustic behavior of ultrasound contrast microbubbles. We also present a review of the in vitro experimental characterization of the acoustic properties of microbubble based contrast agents undertaken in our laboratory. The hierarchical two-pronged approach of modeling contrast agents we developed is demonstrated for a lipid coated (Sonazoid $^\mathrm{TM})$ and a polymer shelled (poly D-L-lactic acid) contrast microbubbles. The acoustic and drug release properties of the newly developed echogenic liposomes are discussed for their use as simultaneous imaging and drug/gene delivery agents. Although echogenicity is conclusively demonstrated in experiments, its physical mechanisms remain uncertain. Addressing questions raised here will accelerate further development and eventual clinical approval of these novel technologies.     

High vacuum tribology of polycrystalline diamond coatings

Polycrystalline diamond coatings have been grown on unpolished side of Si(100) wafers by hot filament chemical vapour deposition process. The morphology of the grown coatings has been varied from cauliflower morphology to faceted morphology by manipulation of the growth temperature from 700°C to 900°C and methane gas concentration from 3% to 1·5%. It is found that the coefficient of friction of the coatings under high vacuum of 133·32×10^?7 Pa (10^?7 torr) with nanocrystalline grains can be manipulated to 0·35 to enhance tribological behaviour of bare Si substrates.     

Contribution of shrimp disease research to the development of the shrimp aquaculture industry: an analysis of the research and innovation structure across the countries

Shrimp aquaculture constitutes a major economic activity of some middle- and low-level economies in the world. Though it is practiced by around 70 countries, it is primarily dominated by China, Thailand, Indonesia, Vietnam, Ecuador and India. These six countries account for 80 % of the global shrimp production. The study has highlighted the role of research in the development of the industry by taking the examples of Penaeus vannamei and P. monodon. In case of the former, a seven time rise in quantum of research (studied by the number of publications as a proxy) could induce five time increase in production, whereas, in the latter case similar pattern was not noticed. The study has observed that based on shrimp production and research contribution; the major 30 countries associated with shrimp aquaculture could be categorized as: (i) high production, high-research contribution, (ii) low production, high-research contribution and (iii) high production, low-research contribution. The countries under the third category are at great risk and may suffer huge economic losses in the event of outbreak of any disease. By generating network map of research linkage across different countries the study has highlighted the potential countries for strengthening the existing linkage and fostering new linkage for knowledge consolidation. The study has given some suggestion for policy formulation for achieving a rapid growth of shrimp aquaculture in the world.     

Small amphiphilic organics, coordination extended solids, and constant curvature structures

In this Account, we explore the role constant curvature structures play in amphiphilic small molecule crystals and extended coordination solids. A constant curvature structure is one in which there is a surface or interface that has the same curvature throughout its surface. Simple examples of such structures contain spheres (micelles), columns, or layers. Yet another family are cubic as is found in the gyroid topology. For amphiphilic systems, there are two domains, one generally hydrophobic and the other hydrophilic. We find that the interfaces between these two domains in small molecule structures resemble those in larger scale systems and adopt topologies related to constant curvature structures. The hydrophobic-to-total volume ratio, a molecular parameter, can be used to predict which type of constant curvature structure is adopted. In the case of three coordinate extended solids, constant curvature plays a role both in the extended net topology and in the hydrophobic-to-hydrophilic interface.