Enhanced Hole Mobility in Regioregular Polythiophene Infiltrated in Straight Nanopores

We demonstrate that the hole mobility in regioregular poly(3‐hexylthiophene) can be enhanced by a factor of 20 by infiltrating it into straight nanopores of anodic alumina. Optical characterization shows that the polymer chains are partially aligned in the charge‐transport direction.     

Polyaniline–maleicacid–dodecylhydrogensulfate salt as sensor material for toxic gases

This article reports the results of novel polyaniline material as gas sensor, capable of operating at room temperature for toxic gases. Polyaniline–maleicacid–dodecylhydrogensulfate salt (PANI‐MA‐DHS) was prepared by emulsion polymerization pathway, which is soluble in N, N‐dimethyl formamide. PANI‐MA‐DHS was coated on a ceramic bead by simple brush coating method and used as sensor material. The resistance change of PANI‐MA‐DHS material for NH₃, CO₂, SO₂, and H₂S gases at different concentrations (10, 100, 1000, and 10,000 ppm level) was monitored for sensor characteristics. The stability of the polyaniline material under continuous exposure of gas level from 10 to 10,000 ppm was also studied. This novel gas sensor material has advantages such as excellent sensing ability, low cost, fast regeneration time (～ 1–2 min), simple experimental setup, and operable at room temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

An evaluation of the macro-homogeneous and agglomerate model for oxygen reduction in PEMFCs

The kinetics of oxygen reduction reaction on platinum/carbon powders in a Nafion film were evaluated with rotating disk electrode and gas diffusion electrode. The effects of the activation, mass transport and ohmic overpotentials were simulated via an “effectiveness factor” approach. The macro-homogeneous model was suitable to simulate the ORR kinetics at the RDE. On the other hand, it was found that the macro-homogeneous model does not simulate the operation of a porous gas diffusion cathode in PEMFC. With this model, the diffusion overpotential in the cathode is considerably overestimated. Conversely, the good agreement between calculated and experimental Tafel plots demonstrates the validity of the agglomerate model, even though the active layers of the PEMFC electrodes were thin and contained no PTFE. These results provided evidence for a two step transport process in the active layer of PEMFC electrodes.     

Plant foods in the management of Diabetes mellitus: Vegetables as potential hypoglycaemic agents

Vegetables are among the numerous plant adjuncts tried for the treatment of diabetes mellitus. A few vegetables that are commonly consumed in India have been claimed to possess antidiabetic potency. In recent years, there has been a renewed interest to screen such plant food materials, for a possible beneficial use. Considerable amount of work has been carried out in this regard with bitter gourd (Momordica charantia) and ivy gourd (Coccinia indica) both in experimental animals and human diabetic subjects. Majority of these studies have documented the beneficial effect of the fruit of bitter gourd and leaf of ivy gourd when administered orally as a single dose. The hypoglycaemic influence is claimed to be mediated through an insulin secretagogue effect or through an influence on enzymes involved in glucose metabolism. The limited number of studies on other vegetables such as cabbage (Brassica oleracia), green leafy vegetables, beans and tubers have shown the beneficial hypoglycaemic influence in both experimental animals and humans. There is scope for more extensive research in this area, especially to examine the long term beneficial effect of dietary vegetables, to identify the active principle, and to understand the mechanism of action, which is at present unclear. Since diet forms the mainstay in the management of diabetes mellitus, there is scope for exploiting the anti-diabetic potency of vegetables to the maximum extent. Such plant food adjuncts possessing hypoglycaemic activity appear to hold promise as potential antidiabetic agents.     

Improved performance in the multi-unit optimization method with non-identical units

In the multi-unit optimization method, the gradient is estimated using finite difference of the outputs of multiple identical units driven with inputs that are offset by a design parameter. For processes with non-identical units, it is shown that stability is not always guaranteed and that the scheme does not necessarily converge to the desired optimum. Correctors are proposed to compensate for the differences between the units. It is shown that the scheme with correctors is locally asymptotically stable and converges to the respective optimum of each units. The multi-unit optimization method with correctors is applied as an example to bioreactors producing green fluorescent protein.     

Electroless nickel deposition from methane sulfonate bath

Electroless plating is a controlled autocatalytic chemical reduction process for depositing metals. The process involves a continuous build up of a nickel coating on a substrate by immersion of the substrate in a suitable nickel plating under appropriate conditions. In this paper the authors have studied the effect of pH and temperature on the rate of deposition and phosphorous content from nickel methane sulfonate bath. Effect of phosphorous content on hardness, wear resistance and corrosion resistance were also studied. SEM and XRD measurements show nodular and amorphous character of the deposits. As the bath is free from sulfate ions the bath can be operated for more number of turn overs and orthophosphite formed during the process can be removed easily.     

Linear-programming-based techniques for synthesis of network-on-chip architectures

Application-specific system-on-chip (SoC) design offers the opportunity for incorporating custom network-on-chip (NoC) architectures that are more suitable for a particular application, and do not necessarily conform to regular topologies. This paper presents novel mixed integer linear programming (MILP) formulations for synthesis of custom NoC architectures. The optimization objective of the techniques is to minimize the power consumption subject to the performance constraints. We present a two-stage approach for solving the custom NoC synthesis problem. The power consumption of the NoC architecture is determined by both the physical links and routers. The power consumption of a physical link is dependent upon the length of the link, which in turn, is governed by the layout of the SoC. Therefore, in the first stage, we address the floorplanning problem that determines the locations of the various cores and the routers. In the second stage, we utilize the floorplan from the first stage to generate topology of the NoC and the routes for the various traffic traces. We also present a clustering-based heuristic technique for the second stage to reduce the run times of the MILP formulation. We analyze the quality of the results and solution times of the proposed techniques by extensive experimentation with realistic benchmarks and comparisons with regular mesh-based NoC architectures.     

Modeling and performance analysis of cluster tools using Petri nets

The performance of cluster tools is gaining ever-increasing importance as the semiconductor industry migrates to larger wafer sizes, and smaller device geometries. Customers demand higher throughput-to-footprint ratios for semiconductor equipment. Cluster tool throughput is the outcome of complex interactions of various subsystems, and there is a critical need for appropriate tools that aid in understanding these interactions, and their effects on throughput. Current methods for throughput analysis are not very well oriented toward understanding the dynamics in cluster tool processing. In this paper we present a procedure to model cluster tools using Petri nets. These models help designers to comprehend the flow of wafers during processing. While Petri nets have been used extensively in the modeling and analysis of diverse manufacturing processes/systems, this to the best of our knowledge is the first attempt to specifically model cluster tools. A state cycle analysis is discussed next; this method enables equipment designers to extract steady state throughput information, as well as understand the interplay of subsystems during the wafer Row. Two example configurations are used to illustrate Petri net-based model building and analysts. These two examples encompass a variety of design features found in the industry today, e.g., sequential and parallel processing, single and dual end effector robots, anticipatory and simple scheduling     

Full band structure calculation of minority carrier lifetimes in HgCdTe and thallium-based alloys

We have calculated the full band structures-based minority carrier lifetimes in small-gap semiconductor alloys. The contribution from first-order Coulomb interactions and second-order electron-electron interactions coupled through optical phonons are included. Our results agree reasonably well with experiments in Hg_0.78Cd_0.22Te. Similar calculations were carried out for lifetimes in In_0.67Tl_0.33P, In_0.85Tl_0.15As, and In_0.92Tl_0.08Sb. The minority carrier lifetimes in In_0.67Tl_0.33P and In_0.92Tl_0.08Sb are shorter than that in Hg_0.78Cd_0.22Te at all temperatures. However, the low-temperature minority carrier lifetime in In_0.85Tl_0.15 As is an order of magnitude longer than that in Hg_0.78Cd_0.22Te. Our calculations further suggest the possibility of increasing the lifetimes of minority carriers either by decreasing the density of states inside a critical energy and momentum region or by increasing the total hole population outside that critical region. Experimental observations that substantiate this suggestion are discussed.     

Giant magnetoelectric effect in composite materials in the region of electromechanical resonance

The magnetoelectric effect in multilayer ferrite-piezoelectric composites has been theoretically and experimentally studied. Using the method of effective parameters, an expression for the magnetoelectric coefficient is determined and its frequency dependence is analyzed. It is shown that, in the region of electromechanical resonance, the magnitude of the effect exceeds a low-frequency value by more than an order of magnitude. The results of calculations obtained for a nickel ferrite spinel-PZT composite are in good agreement with the experimental data.