Pump-probe measurements of CMOS detector rise time in the blue

This paper proposes the use of shorter wavelengths and monolithic integration for chip-to-chip and on-chip optical communication. The promise of monolithic detectors for high-speed interconnection is demonstrated through experimental measurements and matching simulations. Responsivities >0.06 A/W and transit-time-limited response can be expected in the blue from planar p-i-n silicon-on-insulator (SOI) detectors.     

Thermal degradation studies of cellulose phosphates and cellulose thiophosphates

The thermal degradation of cellulose, cellulose phosphates, and cellulose thiophosphates was studied by differential thermal analysis, dynamic thermogravimetry, and derivative thermogravimetry from ambient temperature up to 750°C. Various thermodynamic parameters for different stages of thermal degradation of cellulose and its derivatives have been obtained following the methods of Broido, and Freeman and Carroll. Infrared spectra of thermally degraded samples were obtained. The data were analyzed in an effort to obtain more information concerning the flame-retardant mechanisms of cellulose phosphates and cellulose thiophosphates. Lower values of decomposition temperatures and activation energies of decomposition and higher char yields of cellulose phosphates as compared to cellulose lead to the conclusion that cellulose phosphorus esters are good flame retardants, and this property is retained even when these esters were subjected to ion exchange by Na⁺ and K⁺ ions. However, with the introduction of sulphur atoms, there was some decrease in this property.     

Effect of surface inhomogeneities on the electrical characteristicsof SiC Schottky contacts

This paper reports analysis of the role of defects on the electrical characteristics of high-voltage 6H-SiC Schottky rectifiers. The measured reverse leakage current of high-voltage Ti and Pt rectifiers was found to be much higher than that predicted by thermionic emission theory and using a barrier height extracted from the C-V measurements. In this paper, a model based upon the presence of defects at the 6H-SiC/metal interface is used to explains this behavior. It is proposed that these defects result in lowering of the barrier height in the localized regions and thus, significantly affect the reverse I-V characteristics of the Schottky contacts. The presence of electrically active defects in the Schottky barrier area has been verified by EBIC studies     

Multiple urethral calculi in children: report of two cases

Multiple urethral calculi are rarely found in children. We report herein two unusual cases of children found to have multiple urethral calculi. In one, the calculi formed proximal to a stricture and in the other they formed within a diverticulum. Both patients required urethrotomy for removal of the calculi. A unique cause of urethral stricture is also described in case 1.     

Removal of bromophenols from water using industrial wastes as low cost adsorbents

A comparative study of the adsorbents prepared from several industrial wastes for the removal of 2-bromophenol, 4-bromophenol and 2,4-dibromophenol has been carried out. The results show that maximum adsorption on carbonaceous adsorbent prepared from fertilizer industry waste has been found to be 40.7, 170.4 and 190.2 mg g(-1) for 4-bromophenol 2-bromophenol and 2,4-dibromophenol, respectively. As compared to carbonaceous adsorbent, the other three adsorbents (viz., blast furnace sludge, dust, and slag) adsorb bromophenols to a much smaller extent. This has been attributed to the carbonaceous adsorbent having a larger porosity and consequently higher surface area. The adsorption of bromophenols on this adsorbent has been studied as a function of contact time, concentration and temperature. The adsorption has been found to be endothermic, and the data conform to the Langmuir equation. The further analysis of data indicates that adsorption is a first order process. A comparative study of adsorption results with those obtained on standard activated charcoal sample shows that prepared carbonaceous adsorbent is about 45% as efficient as standard activated charcoal in removing bromophenols. To test the practical utility of this adsorbent, column operations were also carried out. The results were found satisfactory in removing bromophenols by column operations. Therefore, the present investigations recommend the use of carbon slurry waste as inexpensive adsorbent for small scale industries of developing/poor countries where disposal of solid waste of various industries and proper treatment of polluted wastewater is a serious problem.     

Bulk heterojunction formation with induced concentration gradient from a bilayer structure of P3HT:CdSe/ZnS quantum dots using inter-diffusion process for developing high efficiency solar cell

Bulk heterojunction (BHJ) solar cells consisting of poly(3-hexylthiophene) (P3HT) as donor and cadmium selenide/zinc sulphide (CdSe/ZnS) core shell quantum dots (QDs) as acceptor have been developed. Starting from the bilayer of P3HT/QD structure a BHJ is induced using the process of thermal inter-diffusion. The absorption measurements on the bilayer structure show that the absorption coefficient increases and the absorption spectrum becomes broader in the annealed device. Also, the photoluminescence of the annealed device is found to decrease by an order of magnitude showing a significant transfer of electrons to the QDs. With this approach and under broadband white light with an irradiance of 8.19 mW/cm², we have been able to achieve a power conversion efficiency of 5.1% and fill factor 0.45 for this solar cell.     

Antioxidant potential and radioprotective effect of soy isoflavone against gamma irradiation induced oxidative stress

The in vitro antioxidant potential and in vivo radioprotective ability of soy isoflavones was studied. Male Wistar rats were orally administered with soybean isoflavones (60 mg/kg) for 21 days followed by gamma irradiation exposure. Survival studies in rats exposed at 10 Gy and endogenous spleen colony forming unit assay (CFU) at 6.0 Gy were performed in order to find radioprotective and immunomodulatory nature of the compound. The rat liver post mitochondrial supernatant and erythrocytes were used to measure lipid peroxidation (LPO) and glutathione (GSH) content along with various antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) after gamma irradiation exposure at 2.0 Gy. Pretreatment with soy isoflavone, prior to gamma irradiation resulted in the increased survival rate of the animals as compared to irradiated group. CFU counts in the isoflavone treated group followed by gamma irradiation at 6 Gy were significantly high as compared to control and the irradiated group, showing immunomodulatory nature of the isoflavones. Pretreatment with isoflavones also significantly reduced the LPO, enhanced the activity of antioxidant enzymes and improved haematological and histological parameters. The present study suggests that supplementation with isoflavone has potent antioxidant activity and act as probable radioprotector against gamma radiation induced oxidative damage.     

Development and characterization of an efficient bio-white polymer light-emitting diode with red and green phosphorescent dyes as dopants

An efficient white polymer light-emitting diode (WPLED) with stable Commission Internationale de l’éclairage (CIE) coordinates is fabricated. A blue electroluminescence (EL)-emitting conducting polymer [poly(9,9-di-n-hexyl-fluorenyl-2,7-diyl)] is used as a host for red [Bis(1-phenyl-isoquinoline)(acetylacetonate)iridium(III)] and green [iridium(III)tris(2-(4-tolyl)pyridinato-N,C²)] phosphorescent dyes. Although efficient triplet energy transfer is not possible in the green phosphorescent dye, the self-trapping mechanism is utilized for the emission of EL in the green region while an efficient triplet exciton energy transfer from the host to the red dye is utilized for EL in the red wavelength region. Concentrations of the three constituents are optimized to obtain pure white light of appropriate CIE coordinates. An efficient electron-blocking layer based on a biomaterial (salmon-DNA) is also incorporated in the WPLED to improve the device performance. The WPLED shows three distinguished peaks for the primary colors and achieved a maximum luminance and luminous efficiency of 350 cd/m² and 0.86 cd/A, respectively.