Mobility activation in thermally deposited CdSe thin films

Effect of illumination on mobility has been studied from the photocurrent decay characteristics of thermally evaporated CdSe thin films deposited on suitably cleaned glass substrate held at elevated substrate temperatures. The study indicates that the mobilities of the carriers of different trap levels are activated due to the energy of incident illumination, which results in the existence of two distinct trap levels. In each trap depth the energy of the trap increases linearly. It infers that there is a linear distribution of traps of different energies below the conduction band.     

Optimal Ecological Management Practices (EMPs) for Minimizing the Impact of Climate Change and Watershed Degradation Due to Urbanization

Massive deforestation induced by unplanned urbanization in the hilly watersheds of Brahmaputra basin, India, has led to ecological imbalance and is gradually transforming this basin into a multi-hazard zone. Removal of green cover is also becoming a matter of global concern, as it can accelerate the adverse impacts of climate change. People coming in search of work generally reside in the hills, as they cannot afford the high cost of land in plains. This has led to deforestation of the hilly area and has resulted in increased surface erosion from the upper catchments. Though sediment and water yield from these degraded watersheds could have been minimized by implementing ecologically sustainable management practices (EMPs), such as grass land, forest land and detention pond, poor economic conditions of the people stands in the way of field implementation. On the other hand, major industries, which can be held responsible for emission of greenhouse gases, can be asked to finance greenery development in these hilly watersheds through implementation of selected EMPs to earn carbon credit for them. To convert this concept into reality, the EMP combination must be selected in such a way that it restricts sediment and water yield from the watershed within the permissible limit and maximizes its carbon sequestration capacity at minimum possible cost. Such optimal planning is a prerequisite for preparing an acceptable logical agreement between Government and private companies. Keeping this in mind, an optimization model was developed and applied to a micro watershed of Guwahati to explore its applicability in actual field. The model developed in this study provides most logical carbon credit negotiation, subject to the availability of reliable value of CO₂ sequestration for different EMPs.     

Modeling the pre-breakdown V-I characteristics of an electrostaticprecipitator

A novel mathematical model for determining the electrical characteristics in a dc energized duct type electrostatic precipitator is described. The method is a quasi-analytical one, based on solving the current continuity equation by finite-difference method and Poisson's equation by variational principle with the help of Rvachev functions (R-functions). The methodology described represents a valuable design tool for simulating and comparing the voltage-current characteristics of different wire-plate precipitator configurations before optimizing the geometric parameters namely shape of the corona wire, shape of the collection electrodes, wire cross-section, wire-wire and wire-plate spacing. The proposed method will be useful in trying innovative ideas in the design aspect of a wire-duct precipitator. Other significant features of this method are reduced problem domain, less memory space, and faster convergence. The proposed method has been validated with published experimental results and the agreement is excellent. A comparison of electrical characteristics has been made for different sizes and shapes of corona wire and also for various configurations of the wire-plate precipitators     

Synthesis and biological activity of novel thiazolidinediones

Novel compounds having a dual pharmacophore were synthesised and evaluated for their insulin sensitiser and anti-inflammatory properties in different animal models.     

Electrical Properties of 6H-BaTi0.95M0.05O3−δ Ceramics where M = Mn, Fe, Co and Ni

Hexagonal BaTiO₃ materials have been stabilised at room temperature according to the formula BaTi_0.95M_0.05 O_3– where M = Mn, Fe, Co and Ni. Dense ceramics (> 96% of the theoretical X-ray density) were sintered at 1450C in flowing O₂ gas from calcined powders prepared by the mixed oxide route at 1300C. All samples were single-phase and the bulk conductivity, _b, measured by Impedance Spectroscopy and Q.f measured by microwave dielectric resonance methods showed a strong dependence on the type of dopant. _b at 300C was 10^–7, 10^–5.5, 10^–5.5 and 10^–4 Scm^–1 for M = Mn, Fe, Ni and Co, respectively and Q.f at 5 GHz was 7790, 6670, 2442 and 1291 GHz, for M = Mn, Fe, Ni and Co, respectively. The correlation between _b and Q.f is attributed to the presence of oxygen vacancies and/or mixed valency of the dopant ions.     

Precipitation hardening of Cu-4Ti-1Cd alloy

Precipitation hardening of Cu-4Ti-1Cd alloy has been studied using hardness measurements and transmission electron microscopy. This alloy exhibited hardness of 238 Hv in solution treated (ST) condition and attained peak hardness of 318 Hv after ageing at 450°C for 40 h. Electrical conductivity of Cu-4Ti-1Cd alloy increased from 5.7 %IACS (International Annealed Copper standard) in ST condition to 8.9 %IACS on ageing at 450°C for 16 h. This alloy exhibited markedly higher yield strength (751 MPa in the peak-aged condition) compared to Cu-4.5Ti alloy but the increase in UTS due to cadmium addition was less significant. The higher yield strength of ternary alloy in peak aged condition is due to the solid solution strengthening of cadmium as well as the presence of -Cu₄Ti precipitate. On over-ageing the alloy showed a decrease in hardness as a result of formation of equilibrium precipitate, -Cu₃Ti. Optical microscopy reveals single phase with equiaxed grains in solution treated condition. A coherent, metastable phase -Cu₄Ti is responsible for high strength and hardness in peak aged condition. The over-ageing in this alloy shows the formation of cellular structure at the grain boundaries of the matrix phase.     

Rolling and recrystallisation textures in Cu–Al,Cu–Mn and Cu–Ni alloys

The development of strongly cube textured Cu based substrates is important in the cost effective production of long lengths of high temperature superconducting cables. The present paper reports textures (deformation and recrystallisation) development in pure Cu, Cu–Al, Cu–Mn (with a solute content of 1–3 at.%) and Cu–35 at.% Ni alloys.