Mercury centres in caesium halide crystals

Electronic absorption spectrum of CsBr crystals doped with Hg²⁺ showed three bands at 340, 250 and 217.5 nm at 300 K, which disappeared on ageing and reappeared on quenching the crystals from 700 K. Radiation damage studies indicated the formation of Hg²⁺ centres and on prolonged irradiation Hg²⁺ centres. Similar results have also been obtained in the case of Csl: Hg²⁺.     

Voronoi Projection-Based Fast Nearest-Neighbor Search Algorithms: Box-Search and Mapping Table-Based Search Techniques

In this paper we consider fast nearest-neighbor search techniques based on the projections of Voronoi regions. The Voronoi diagram of a given set of points provides an implicit geometric interpretation of nearest-neighbor search and serves as an important basis for several proximity search algorithms in computational geometry and in developing structure-based fast vector quantization techniques. The Voronoi projections provide an approximate characterization of the Voronoi regions with respect to their locus property of localizing the search to a small subset of codevectors. This can be viewed as a simplified and practically viable equivalent of point location using the Voronoi diagram while circumventing the complexity of the full Voronoi diagram. In this paper, we provide a comprehensive study of two fast search techniques using the Voronoi projections, namely, the box-search and mapping table-based search in the context of vector quantization encoding. We also propose and study the effect and advantage of using the principal component axes for data with high degree of correlation across their components, in reducing the complexity of the search based on Voronoi projections.     

Histopathological and biochemical effects of cyanobacterial cells containing microcystin‐LR on Tilapia fish

Blooms of Microcystis aeruginosa, commonly observed in many lakes of Tamil Nadu, produce the cyanobacterial toxin Microcystin, which has tumor promoting property in fish. Strains of Microcystis aeruginosa species have the same morphology but may vary in their toxicity. In the present study, Microcystin produced by Microcystis aeruginosa from Thenneri lake in Kancheepuram district of Tamil Nadu, was isolated and characterized by high‐performance liquid chromatography and electron spray ionization mass spectroscopy. Based on spectroscopic results the toxin was identified as Microcystin‐LR. Toxicogenicity was evident from the alteration in the activity of antioxidant enzymes [Glutathione S‐transferase and Catalase] and increase of protein and lipid peroxidation contents in Oreochromis niloticus, a fresh water fish species, after controlled exposure to Microcystis aeruginosa cells. Toxicity was further confirmed by histopathological changes in gill, liver and intestine of exposed fish.     

Synthesis, Structure Analysis, and Microwave Dielectric Properties of LnTiSbxTa1−xO6 (Ln=Ce, Pr, and Nd) Ceramics

LnTiSb _x Ta_{1− x} O₆ ceramics were prepared by the conventional solid-state ceramic route for x =0, 0.05, 0.1, 0.15, and 0.2. The structures of the materials were analyzed using X-ray diffraction techniques. The cell parameters and the theoretical densities of the samples were calculated using least square methods. The materials are sintered to >94% of theoretical density at 1480°C. The microwave dielectric properties were measured using the cavity resonator method. The surface morphology of the sintered samples was analyzed using scanning electron microscopy. All the materials have good microwave dielectric properties and are suitable for dielectric resonator applications.     

Synthesis and properties of novel organosoluble bismaleimides and polyaspartimides containing bis(4‐maleimido‐3, 5‐dimethyl phenyl) halo phenyl methane

A series of bismaleimides was synthesized from bis(4‐amino‐3, 5‐dimethylphenyl) (X) phenyl methane (X = 3′chloro, 3′‐bromo, 3′‐benzyloxy, 4′‐chloro, 4′‐fluoro) and maleic anhydride. The bismaleimides were subsequently polymerized with various diamines by Michael addition to yield novel polyaspartimides. All the polymers exhibited good solubility in organic solvents and the inherent viscosity of the polymers were in the range of 0.40–0.56 dL/g, which is good enough to fabricate composites and films. The temperature at which 10% weight loss occurred was in the range of 390–441°C. The polymers had high glass transition temperature in the range of 205–275°C and left about 31.95–84.20% char yield at 800°C indicating that they have good self‐extinguishing property. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The influence of bio additive on the compression ignition engine with diesel and Jatropha methyl ester biodiesel

The present experimental investigation evaluates the effects of using blends of diesel fuel with 20% concentration of Methyl Ester of Jatropha biodiesel blended with bio additive. Both the diesel and biodiesel fuel blend was injected at 23° Before Top Dead Centre to the combustion chamber. The experiment was carried out with three different ratios of bio additive. Biodiesel was extracted from Jatropha oil; 20% (B20) concentration is found to be best blend ratio from the earlier experimental study. The bio additive was added to B20MEOJ at various concentrations of 1?ml, 2?ml and 3?ml, respectively. The main objective is to obtain minimum specific fuel consumption, better efficiency and lesser Emission using bio additive blends. The results concluded that full load shows an increase in efficiency when compared with diesel, and highest efficiency is obtained with B20MEOJBA 3?ml bio additive blend. It is noted that there is an increase in thermal efficiency as the blend ratio increases. Biodiesel blend has a performance closer to that of diesel, but emission is reduced in all blends of B20MEOJBA 3?ml compared to that in diesel. Thus the work marks for the suitability of biodiesel blends as an alternate fuel in diesel engines.     

The Geometric Phase

Abstract

The change in the phase of a beam of light produced by a cyclic change in its state of polarization is an example of the geometric phase that can be verified by interferometric measurements. This paper presents a quantum-field theoretical analysis of the geometric phase interferometer in the limit of a small photon number, as well as some experimental results that confirm that the optical effects due to the geometric phase persist down to the single-photon level.     

Experimental study of effects of wicks and boundary conditions on thermal performance of heat pipes

The inherent two-phase heat transport of heat pipes (HPs) is progressively being examined for potential uses. These thermal devices are affected by many operating factors, prompting this study to investigate the effects of different types of wicks and working conditions on the time-dependent thermal behavior. Primarily, the effects of different wick performances were investigated under various operating conditions. The resulting surface temperatures depicted in the time to steady performance and the dry-out behavior revealed the conditions to improve the HPs design. The thermal resistance decreased from 0.6 K/W (at 25 W) to 0.05 K/W (at 200 W) by increasing the HP diameter from 6 to 10 mm; these values are relative to those of copper rods, which decrease from 2.70 K/W (at 25 W) to 0.40 K/W (at 200 W). Non-linear and linear temperature responses were recorded when the HPs diameter and length were varied. Compared to conventional mesh and groove wicks, the composite groove-sintered, mesh-sintered, and groove-mesh wicks recorded lower thermal resistance with distinctively faster startup times, lower startup temperatures, better temperature uniformity and less dynamic instability. Tilting the HPs relative to the horizontal position lessens failure tendencies. Usually, dynamic responses are typically first-order under the conditions studied. Hence, proper sizing of HPs and correct wick selection can improve their performance.

     

Online 3-D tracking of suspension living cells imaged with phase-contrast microscopy

Neural stem cells/neural progenitors (NSCs/NPs) are cells that give rise to the main cell types of the nervous system: oligodendrocytes, neurons, and astrocytes. Studying NSCs/NPs with time-lapse microscopy is critical to the understanding of the biology of these cells. However, NSCs/NPs are very sensitive to phototoxic damage, and therefore, fluorescent dyes cannot be used to follow these cells. Also, since in most of NSC/NP-related experiments, a large number of cells neesd to be monitored. Consequently, the acquisition of a huge amount of images is required. An additional difficulty is related to our original suspension living, tracking objective, behavior much closer to the natural, in vivo, way of development of the cells. Indeed, unlike adherent cells, suspension cells float freely in a liquid solution, thus, making their dynamics very different from that of adherent cells. As a result, existing visual tracking algorithms that have primarily been developed to track adherent cells are no longer adequate to tackle living cells in suspension. This paper presents a novel automated 3-D visual tracking of suspension living cells for time-lapse image acquisition using phase-contrast microscopy. This new tracking method can potentially strongly impact on current 3-D video microscopy methods, paving the way for innovative analysis of NSCs/NPs and as a result, on the study of neurodegenerative diseases.