Optimum power from a solar thermal power plant using solar concentrators

In this paper, the optimum temperature of operation of a solar concentrator and thus the maximum power obtained from a solar thermal power plant has been calculated. Results are plotted graphically and discussed.     

Performance and emission characteristics of hydrogen fueled spark ignition engine

A study of alternate fuels leads to hydrogen as a candidate fuel for the future. Its remarkable properties provide the potential of high thermal efficiency at part load by operating the engine unthrottled with lean mixtures. The problems of pre-ignition and backfiring could be overcome at a wide range of operation by providing a cold spark plug with a narrow gap and by keeping combustion chamber walls clean. Hydrogen operation of spark-ignited engines has been found to be very profitable at low equivalence ratios both from the point of view of increased thermal efficiency and reduced nitrogen oxides emissions.     

Improving power conversion efficiency in polythiophene/fullerene-based bulk heterojunction solar cells

In the present work, we have studied photovoltaic devices fabricated from a blend of regioregular poly (3-hexlthiophene) (P3HT) and Buckminster fullerene. The solvent and composite ratio have been selected to obtain best morphology and minimum degradation. Buffer layers of poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate) (PEDOT:PSS) at the anode and of LiF at the cathode were used to improve the device performance. It was further found that post-annealing of the devices for an optimum duration and temperature improves the solar cells, and the power conversion efficiency of the devices increases to 2.1% at AM1.5. Though the efficiency using [6,6]-phenyl C60 butyric acid methyl ester (PCBM) as the composite acceptor instead of C₆₀ can be higher, it was not used because of its very high cost as compared to C₆₀.     

A new colour assay for [URE3] prion in a genetic background used to score for the [PSI⁺] prion

Most scoring assays for yeast prions are dependent on specific genetic markers and constructs that differ for each prion. Here we describe a simple colour assay for the [URE3] prion that works in the 74D-964 strain frequently used to score the [PSI(+)] prion. Although this assay can only be used to score for [URE3] in the [psi(-)] version of the strain, it makes it easier to examine the effects of host mutations or environmental changes on [URE3] or [PSI(+)] using a colour assay in the identical genetic background.     

Experimental investigations on solar chimney for room ventilation

Experimental investigations on a small size solar chimney show that the rate of ventilation increases with increase of the ratio between height of absorber and gap between glass and absorber. This finding is in agreement with results of the steady-state mathematical model developed for analysis of such systems. Nine different combination of absorber height and air gap have been investigated on the experimental set-up. Highest rate of ventilation induced with the help of solar energy was found to be 5.6 air change per hour in a room of 27 m³, at solar radiation 700 W/m² on vertical surface with the stack height-air gap ratio of 2.83 for a 1 m high chimney.     

A combination of IL-10 and direct contact with plasma cell tumors decreases CD23 expression on splenic B cells

We and others have previously found that splenic B cells from plasma cell tumor-bearing mice exhibit decreased CD23 expression. In the present study we further examined the mechanism of CD23 down-regulation by plasma cell tumors. We show here that although direct contact is required between the tumor cells and B cells, it is not sufficient, since fixed tumor cells do not induce the same reduction in CD23 expression. We have identified IL-10, a cytokine produce by the tumors, as the sole soluble factor that contributes to decreased CD23 expression on B cells induced by plasma cell tumors because 1) Abs to IL-10 prevent the loss of CD23 induced by plasma cell tumors both in vitro and in vivo; 2) engineered IL-10 negative variants of these tumors are reduced in their ability to down-regulate CD23 expression; 3) rIL-10 alone induces partial, but significant, decreases in CD23 expression on normal splenic B cells; and 4) the addition of IL-10 and fixed tumor cells to cultures of normal splenocytes decreases CD23 expression to levels similar to those in cocultures with live tumor cells. Collectively, these results demonstrate that plasma cell tumors down-regulate CD23 expression on B cells by a coordinate mechanism of IL-10 plus contact-mediated events and reveal a novel role for IL-10 in the regulation of CD23 expression on B cells that is suggestive of host B cell activation in the presence of the tumor.     

The retarding action of polyacrylamide in acrylic dyeing

Polyacrylamide of different molecular masses was found to act as polycationic retarders in dyeing of acrylic fibres with cationic dyes. The method of retardation is simple and economic, having no adverse effect on final dye exhaustion values. The possible mechanisms involved are discussed.     

A formal model of the software test process

A novel approach to model the system test phase of the software life cycle is presented. This approach is based on concepts and techniques from control theory and is useful in computing the effort required to reduce the number of errors and the schedule slippage under a changing process environment. Results from these computations are used, and possibly revised, at specific checkpoints in a feedback-control structure to meet the schedule and quality objectives. Two case studies were conducted to study the behavior of the proposed model. One study reported here uses data from a commercial project. The outcome from these two studies suggests that the proposed model might well be the first significant milestone along the road to a formal and practical theory of software process control.