Development of pitch-based carbon–copper composites

Carbon–copper composites with varying copper to carbon ratio of 0.66–1.5 (by weight) were developed from coal-tar-pitch-derived green coke (as such or modified with natural graphite) as carbon source and electrolytic grade copper powder at different heat treatment temperatures (HTTs) of 1000–1400 °C. The physical, mechanical, and electrical properties differ depending upon the HTT and also on copper to carbon ratio (Cu/C). The composites prepared at HTT of 1100 °C having Cu/C ratio of 0.66 and 0.9 exhibited a high bending strength of 150 and 140 MPa, bulk density of 2.63 and 2.81 gm/cm³, electrical resistivity of 1.6 and 0.96 m Ω cm and shore hardness of 88 and 84, respectively, in spite of well-known inadequate wettability between copper and carbon. Increasing the temperature from 1100 °C for processing of the composites deteriorated the properties mainly due to the loss of copper through melting above 1100 °C as revealed by X-ray, scanning electron microscopy, thermal analysis and EDAX studies.     

Efficient parallel algorithms for solvent accessible surface areaof proteins

We present faster sequential and parallel algorithms for computing the solvent accessible surface area (ASA) of protein molecules. The ASA is computed by finding the exposed surface areas of the spheres obtained by increasing the van der Waals radii of the atoms with the van der Waals radius of the solvent. Using domain specific knowledge, we show that the number of sphere intersections is only O(n), where n is the number of atoms in the protein molecule. For computing sphere intersections, we present hash-based algorithms that run in O(n) expected sequential time and O(n/p) expected parallel time and sort-based algorithms that run in worst-case O(n log n) sequential time and O(n log n/p) parallel time. These are significant improvements over previously known algorithms which take O(n²) time sequentially and O(n²/p) time in parallel. We present a Monte Carlo algorithm for computing the solvent accessible surface area. The basic idea is to generate points uniformly at random on the surface of spheres obtained by increasing the van der Waals radii of the atoms with the van der Waals radius of the solvent molecule and to test the points for accessibility. We also provide error bounds as a function of the sample size. Experimental verification of the algorithms is carried out using an IBM SP-2     

Glass fibre reinforced composites of triglycidyl-p-aminophenol

Glass fibre reinforced epoxy composites were fabricated from the matrix resins diglycidyl ether of bisphenol A (DGEBA) and triglycidyl-p-aminophenol (TGAP) using diethylene triamine as curing agent. The epoxy laminates were evaluated for their mechanical properties, dielectrical properties and chemical resistance. Significant improvement in fiexural strength but a slight deterioration in dielectrical properties were observed on incorporation of an epoxy fortifier into the resin system before fabricating the composites.     

A numerical study of pulsatile blood flow in an eccentric catheterized artery using a fast algorithm

The pulsatile blood flow in an eccentric catheterized artery is studied numerically by making use of an extended version of the fast algorithm of Borges and Daripa [J. Comp. Phys., 2001]. The mathematical model involves the usual assumptions that the arterial segment is straight, the arterial wall is rigid and impermeable, blood is an incompressible Newtonian fluid, and the flow is fully developed. The flow rate (flux) is considered as a periodic function of time (prescribed). The axial pressure gradient and velocity distribution in the eccentric catheterized artery are obtained as solutions of the problem. Through the computed results on axial pressure gradient, the increases in mean pressure gradient and frictional resistance in the artery due to catheterization are estimated. These estimates can be used to correct the error involved in the measured pressure gradients using catheters.     

Development of Biodegradable Nanocarriers Loaded with a Monoclonal Antibody

Treatments utilizing monoclonal antibody therapeutics against intracellular protein-protein interactions in cancer cells have been hampered by several factors, including poor intracellular uptake and rapid lysosomal degradation. Our current work examines the feasibility of encapsulating monoclonal antibodies within poly(lactic-co-glycolic acid) (PLGA) nanoparticles using a water/oil/water double emulsion solvent evaporation technique. This method can be used to prepare protective polymeric nanoparticles for transporting functional antibodies to the cytoplasmic compartment of cancer cells. Nanoparticles were formulated and then characterized using a number of physical and biological parameters. The average nanoparticle size ranged from 221 to 252 nm with a low polydispersity index. Encapsulation efficiency of 16%–22% and antibody loading of 0.3%–1.12% were observed. The antibody molecules were released from the nanoparticles in a sustained manner and upon release maintained functionality. Our studies achieved successful formulation of antibody loaded polymeric nanoparticles, thus indicating that a PLGA-based antibody nanoformulation is a promising intracellular delivery vehicle for a large number of new intracellular antibody targets in cancer cells.     

A slow wave structure and its application in bandpass filter design

This paper presents a new slow wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of different kind of coupling in this structure is demonstrated. Two and four resonator band pass filters at center frequency 2.15 and 2.30 GHz with different bandwidth are designed. The simulated results are verified with the help of two different software packages (IE3D and Sonnet Lite).     

Biocompatible hyperbranched polyurethane/multi-walled carbon nanotube composites as shape memory materials

Multi-walled carbon nanotube (MWCNT)-based composites have been prepared by in situ technique using Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU) as the matrix. The scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy analyses revealed good dispersion as well as interaction of MWCNT with the matrix. Remarkable recovery of shape to the extent of 98% was obtained after composite formation. More than 300% improvement in tensile strength was observed as compared to the pristine HBPU. Significant enhancement of thermal stability up to 275 °C was found even at low MWCNT loading (1 wt.%). Bacterial degradation of the composite films was tested using two strains of Pseudomonas aeruginosa, MTCC 7814 and MTCC 7815. The composites exhibited enhanced biodegradability as compared to the pristine polymer. The cytocompatibility test based on hemolysis of red blood cells showed that the material lacks cytotoxicity. The investigation indicates that the material has high potential as shape memory biomaterial.     

Multi-User Relaying of High-Rate Space–Time Code in Cooperative Networks

In this paper, we propose high-rate space–time coding for cooperative wireless networks to reduce the overall delay incurred in relaying signals to multiple receivers. The relay structure is optimized in order to achieve maximum SNR at the receiver nodes. The proposed scheme provides a significant reduction in the delay required for the relaying and transmission of the signals to the multiple receivers with a minute loss in performance. We have also shown by simulation that this loss in the performance could be recovered by selecting more number of relays. We propose two relaying strategies for high-rate space–time codes, which are very useful in providing high data-rate in wireless cooperative networks.