Thermopower Study of GaN-Based Materials for Next-Generation Thermoelectric Devices and Applications

III-nitride InGaN-based solar cells have gained importance because their band gap can potentially cover most of the solar spectrum, spanning 0.7 eV to 3.4 eV. However, to use these materials to harvest additional energy, other properties such as their thermoelectric properties should be exploited. In this work, the Seebeck coefficient and the electrical conductivity of three InGaN alloys with various indium concentrations and Gd-doped GaN (GaN:Gd) were measured, and the power factor was calculated. We report a Seebeck value of ∼209 μV/K for Gd-doped GaN.     

Growth performance, variability in yield traits and oil content of selected accessions of Jatropha curcas L. growing in a large scale plantation site

Jatropha curcas L. (JCL) is gaining global popularity as a potential feed stock of biodiesel and a candidate species for waste land reclamation. Although the oil yield of this species is better than any other non-edible oil yielding plants, the lack of agronomic practices defame this species for further exploitation. Furthermore, there is paucity of data on the growth performances and yield of JCL plantations. In this context, a systematic study on passport data and yield performance of JCL germplasms (including their indigenous collection number (IC No.), morphological characterization of seeds and seed oil content) growing in a large scale plantation site at Solar Energy Center, Gurgaon, India were carried out during 2007–2008. Ten elite accessions of JCL were screened from this site based on their growth performance and biomass characterization and were deposited at National Bureau of Plant Genetic Resources, New Delhi for registration. The oil content of the 10 registered accessions was ranged from 17% to 34%. Cluster analysis was performed to find out promising germplasms. Cluster analysis formed two prominent groups, each one with two sub-clusters. The promising accessions can be further explored for crop improvement programs. Furthermore, multi-locational trials are essential for optimizing the agropractices for maximum yield for a sustainable biodiesel production.     

Optimization of preparation conditions and improvement of stability of Cu/ZnO-based multicomponent catalysts for methanol synthesis from CO2 and H2

The operation conditions for preparing a Cu/ZnO-based multicomponent catalyst by a coprecipitation method were optimized. The temperature during coprecipitation should be less than 313 K, and the removal of Na from the catalyst by washing the precipitates is most important. Furthermore, a small amount of silica added to the catalyst greatly improved its long-term stability in methanol synthesis from CO₂ and H₂.     

Characterization of polystyrene‐b‐poly(ethylene oxide) diblock copolymer and investigation of its micellization behavior in water

The recent studies deal with a diblock copolymer, polystyrene–poly(ethylene oxide). Infrared spectroscopy, proton resonance spectroscopy (¹H‐NMR), and laser light scattering techniques have been used to characterize the polymer. It has been concluded that the sample investigated is diblock copolymer polystyrene–poly(ethylene oxide) having molecular mass 1.656 × 10⁴ g/mol and blocks ratio 1 : 2. The micellization behavior is explored through ¹H‐NMR, laser light scattering, light absorption, surface tension, and conductance and viscosity measurements. The results conclude that the critical micelles concentration of copolymer is 0.0951 g/dL at 25°C. It has been observed that the surface tension of solution decreases with the temperature and its impact is maxima in dilute concentration region. In addition, new methodologies have been introduced to get accurate critical micelles concentration and critical micelles temperature. © 2010 Wiley Periodicals, Inc., J Appl Polym Sci, 2010     

The Effect of Rice Husk Powder on Standard Malaysian Natural Rubber Grade L (SMR L) and Epoxidized Natural Rubber (ENR 50) Composites

The effects of rice husk powder (RHP) loading and two types of natural rubber matrix (SMR L and ENR 50) on curing characteristics and mechanical properties were studied. The scorch time and cure time decreased with increasing RHP loading whereas maximum torque showed an increasing trend. SMR L composites possessed longer scorch time and cure time than ENR 50 composites. Incorporation of RHP into both rubbers improved tensile modulus significantly but decreased tensile strength and elongation at break. SMR L composites exhibited the lower tensile modulus and higher tensile strength and elongation at break than ENR 50 composites.     

Removal of viable bacteria in lake water by denim filtration

A series of experiments were performed to investigate the removal of viable bacteria [Escherichia coli, total coliforms and standard plate count (SPC) bacteria] in lake water by denim filtration. Filtration with indigo reagent‐dyed denim physically removed E. coli (up to 95%) and total coliforms (up to 92%) from lake water. The removal efficiencies of SPC bacteria (up to 85%) were generally lower than those of E. coli and total coliforms. The adsorption of bacteria to particulate matter larger than the effective pore size of the denim (ca. 48 μm) and the subsequent physical sieving of the large particulate matter seemed to be the dominant disinfection mechanism.     

Temperature‐Insensitive High Strain in Lead‐Free Bi0.5(Na0.84K0.16)0.5TiO3–0.04SrTiO3 Ceramics for Actuator Applications

Lead‐free piezoelectric ceramics, 0.96[{Bi_0.5 (Na_0.84K_0.16)_0.5}_1?xLi_x(Ti_1?yNb_y)O₃]–0.04SrTiO₃ (BNKLiTN–ST) with x, y = 0–0.030, were synthesized by solid‐state reaction method. X‐ray diffraction patterns indicated that Li and Nb successfully diffused into the BNKT–ST lattice and formed a pure perovskite structure with x, y ≤ 0.025. Increasing the Li and Nb contents (x, y = 0.020) induced a phase transformation from the coexistent rhombohedral–tetragonal phases for pure BNKT–ST ceramics to a pseudocubic phase, resulting in degradation of the remnant polarization and coercive field. However, the field‐induced strain was markedly enhanced at x, y = 0.020, giving rise to a giant dynamic piezoelectric constant (d₃₃* = S_max/E_max = 800 pm/V). Furthermore, the temperature dependence of the field‐induced strain response showed temperature‐insensitivity up to 120°C. To explore its potential for device applications, a 10‐layered stack‐type multilayer actuator was fabricated from the optimal composition (x, y = 0.020). This actuator showed a large S_max/E_max of 600 pm/V at a relatively low driving field of 4.5 kV/mm suggesting highly promising results in lead‐free BNT‐based ceramics.     

Activity Concentration of 137Cs in soil samples from Punjab province (Pakistan) and estimation of gamma-ray dose rate for external exposure

Punjab is one of the most populated provinces of Pakistan having 34 districts. There is always a need to have baseline background level information about 137Cs and the corresponding gamma-ray doses to the population. In this respect, soil samples were collected to a depth of 30-50 cm from all 34 district headquarters of the Punjab province of Pakistan and 137Cs activity concentrations were measured. 137Cs activity concentration was found to be in the range from 1.1 +/- 1.0 to 5.3 +/- 2.5 Bq kg(-1). The average value of estimated external gamma-ray dose rate from all 34 districts of Punjab province was computed to be 0.18 +/- 0.07 nSv h(-1) from 137Cs in soil samples. The measured 137Cs activity concentration range was compared with the reported ranges in the literature from some of the other locations in the world. Results obtained in this study show that 137Cs concentration is of a lower level in the investigated area. The average value of estimated external effective dose rate is found far below the dose rate limit of 1.0 mSv y(-1) for members of the general public recommended by the International Commission on Radiological Protection (ICRP) as well as the external gamma radiation dose of 0.48 mSv y(-1) received per head from the natural sources of radiation assessed by UNSCEAR (2000). It is concluded that 137Cs soil contamination does not pose radiation hazards to the population in the investigated areas.     

Petri Net modelling approach for analysing the behaviour of Wnt/ β ‐catenin and Wnt/ Ca2+ signalling pathways in arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease that may result in arrhythmia, heart failure and sudden death. The hallmark pathological findings are progressive myocyte loss and fibro fatty replacement, with a predilection for the right ventricle. This study focuses on the adipose tissue formation in cardiomyocyte by considering the signal transduction pathways including Wnt/ β ‐catenin and Wnt/Ca²⁺ regulation system. These pathways are modelled and analysed using stochastic petri nets (SPN) in order to increase our comprehension of ARVC and in turn its treatment regimen. The Wnt/ β ‐catenin model predicts that the dysregulation or absence of Wnt signalling, inhibition of dishevelled and elevation of glycogen synthase kinase 3 along with casein kinase I are key cytotoxic events resulting in apoptosis. Moreover, the Wnt/Ca²⁺ SPN model demonstrates that the Bcl2 gene inhibited by c‐Jun N‐terminal kinase protein in the event of endoplasmic reticulum stress due to action potential and increased amount of intracellular Ca²⁺ which recovers the Ca²⁺ homeostasis by phospholipase C, this event positively regulates the Bcl2 to suppress the mitochondrial apoptosis which causes ARVC.Inspec keywords: molecular biophysics, enzymes, cancer, muscle, Petri nets, cellular biophysics, bioelectric potentials, biomembranes, tumours, cardiology, genetics, biochemistry, calciumOther keywords: heart failure, sudden death, hallmark pathological findings, progressive myocyte loss, fibro fatty replacement, adipose tissue formation, signal transduction pathways, Ca²⁺ regulation system, stochastic petri nets, ARVC, $β‐catenin model, Wnt signalling, glycogen synthase kinase 3, Bcl2 gene, c‐Jun N‐terminal kinase protein, petri Net modelling approach, Ca²⁺ signalling pathways, arrhythmogenic right ventricular cardiomyopathy, inherited heart muscle disease, Ca²⁺ SPN model, Ca