Cationic metalloporphyrins for synthesis of conducting,water-soluble polyaniline

Catalytic oxidative polymerization of aniline was performed using the tetrapyridylporphyrin (TPyP) complexes of iron (III), manganese (III) and cobalt (III). It was found that the cationic metalloporphyrin catalyzed the polymerization of aniline more efficiently than the anionic metalloporphyrins, when using aqueous H₂O₂. The reaction was carried out in the presence of sulfonated polystyrene (SPS) as a template at different pHs, ranging from 1 to 5, and the best results were obtained at pH 2. Formation of water-soluble polyaniline (PANI) was characterized by UV–vis, FT-IR spectroscopy and cyclic voltammetry (CV). FT-IR and UV–vis spectra confirm the formation of the conducting form of PANI. Cyclic voltammetry measurements demonstrate that the polymer has convenient electroactivity.     

A structural equation model of expertise in college physics.

A model of expertise in physics was tested on a sample of 374 college students in 2 different level physics courses. Structural equation modeling was used to test hypothesized relationships among variables linked to expert performance in physics including strategy use, pictorial representation, categorization skills, and motivation, and these variables were examined for their influence on physics achievement. Gender was included in the model to examine how it influenced achievement indirectly through its influence on the other variables in the model. Two levels of expertise were examined by testing the model on trigonometry-based physics students and on more advanced, calculus-based physics students. Results were similar across both levels of expertise: For both courses, student motivation had a significant influence on students’ strategy use and categorization skills. Categorization skills, in turn, influenced student achievement directly, and indirectly, through strategy use. Strategy use had a significant influence on achievement. Pictorial representation played little role in the model. Gender contributed primarily through motivation, but for the more advanced level course it also directly predicted strategy use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in skilled reaching for food related to increased number of gestures: Evidence for goal and habit learning of skilled reaching.

Skilled reaching in rodents and primate is motorically similar, but success in reaching by rodents is distinctively variable. The source of this variability has not been examined previously. Long–Evans rats were videotaped as they reached for food in 2 different reaching tasks, and endpoint measures of performance were examined in relation to variables previously associated with individual differences, including testing procedures, rehabilitation, movement ability, general locomotor activity, and cortical anatomy. There were individual differences in performance, but these were not related to the dependent measures related to training, movement ability, locomotor activity, or anatomy (e.g., brain with cortical thickness, acetylcholinesterase and neuron density, pyramidal tract size). Success was negatively related to numbers of gestures (non–weight-bearing movements of the reaching limb) used on a reach, however. The results are discussed in relation to the idea that individual differences in response strategy bias some rats to use a more successful goal strategy and others to use a less successful habit strategy for skilled reaching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Metric for the Temporal Characterization of Parallel Programs

We consider the time-dependent demands for data movement that a parallel program makes on the architecture that executes it. The result is an architecture-independent metric that represents the temporal behavior of data-movement requirements. Programs are described as series of computations and data movements, and while message passing is not ruled out, we focus on explicit parallel programs using a fixed number of processes in a distributed shared-memory environment. Operations are assumed to be explicitly allocated to processors when the metric is applied, which might correspond to intermediate code in a parallelizing compiler. The metric is called the interprocess read (IR) temporal metric. A key to developing an architecture-independent temporal metric is modeling program execution time in an architecture-independent way. This is possible because well-synchronized parallel programs make coordinated progress above a certain level of granularity. Our execution time characterization takes into account barrier synchronization and critical sections. We illustrate the metric using instruction count on simple code fragments and then from multiprocessor program traces (Splash benchmarks). Results of running the benchmarks on simulated network architectures show that the IR metric for the time scale of network response predicts performance better than whole program measures.     

The influence of heat treatment on the microstructure,flux pinning and magnetic properties of bulk BSCCO samples prepared by sol-gel route

We study the combined influence of calcination and sintering temperature on the microstructure, superconducting and pinning properties of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_10+θ (Bi-2223) prepared by the sol-gel route. Using several characterization techniques, including X-rays diffractometry and electrical transport measurements, we find that the powders calcined at 820 °C often result in a crystal higher critical current density (J_c) compared those calcined at 830 °C. The powder calcined at 820 °C and sintered at 850 °C (Bi-2223 ₈₂₀⁸⁵⁰) showed the best grain morphology and the largest magnetic hysteresis loop and a J_c equal to 12.94 $\times$ 10⁵ A/cm², comparable to the best results found in the literature for Bi-2223. The enhancement in J_c for Bi-2223 ₈₂₀⁸⁵⁰ seems to be due to improved grain structure rather than creation of effective pinning centers, because the scaling behavior of flux pinning force densities indicates that the main pinning mechanism for all samples is normal point pinning.     

Household energy needs of a village in the Rayalaseema area of Andhra Pradesh, India

Energy shortages in rural areas have several far-reaching ill-consequences. The scarcity of fuelwood forces people to use animal dung and crop residue as fuel, reducing the soil fertility and productivity. Progressive deforestation adversely affects the environment. Women and children in villages walk long distances and spend more time in searching for fuel. For effective energy planning, it is necessary to understand the energy-use patterns of different categories of farmers in village ecosystems and the influence of income and family size on it. This paper reports such a study conducted in a village in the State of Andhra Pradesh in India where dryland agriculture is pursued. The household energy-use patterns observed in the village clearly show that most energy is utilized for basic survival tasks such as cooking, cleaning, fetching fuel, water and other necessities of life. Commercial energy, which accounts for 6.5% of the total energy consumption of households, is used exclusively for lighting. A number of measures have been suggested for enhancing the efficiency of energy use in rural household systems, which include the design and installation of a fuel-efficient improved chulha, with dampers, baffle and a grate in the combustion chamber, installation of family size biogas plants, planting of hardwood trees on field bunds, energy plantation on marginal and waste lands, utilization of solar photovoltaics for power generation, installation of windmills for lifting water, and briquetting and pelletization of groundnut shell, and farm and forest residues. A well-knit and coordinated infrastructure has to be developed for successful implementation of the above measures. Local skill and participation, especially of artisans and women, should be encouraged and should be supplemented by appropriate training and monitoring. An energy utilization system based on local resources can improve productivity and standards in all spheres of rural living.     

Dual-Band Antenna Fed with CPW Technology Using Modified Mirrored L-Shaped Conductor-Back Plane

This paper describes a novel configuration of a CPW-fed printed monopole antenna that depicts dual-band operations of WLAN and X-bands. The proposed antenna consists of a simple rectangular-shaped patch as the main radiator, the modified mirrored L-shaped conductor back plane element, and the partial rectangular CPW-ground surface. Dual-band performances can be obtained by embedding and adjusting dimensions of strips on mirrored L-Shaped conductor back plane element. The impedance bandwidth with \(\hbox {s}_{11} < -10\)  dB is about 2.2 GHz (5.05–7.25 GHz) or 36 % for 5 GHz band and 5.2 GHz (7.6–12.8 GHz) or 51 % for X-band. The measured peak gains are about 1.8 dBi at WLAN-band and 4.3 dBi at X-band. The Experimental results indicate that the fabricated antenna with proper dimensions, good radiation characteristics, and reasonable measured gains can be a good candidate for various applications of the future multi-band wireless communication systems and mobile device.     

The Hydra Parallel Programming System

The Hydra Parallel Programming System, a new parallel language extension to Java, and its supporting software are described. It is a fairly simple yet powerful language designed to address a number of areas that have not received much attention. One of these areas is the recompilation of parallel programs at runtime to allow a parallel program to adapt to the architecture it is executing on. The first version of this software system focuses on smaller Symmetric Multiprocessing and compatible architectures which are becoming more common. This particular class of machines has a great need for more options in the area of parallel programming among the vastly popular Java language programmers. Hydra programs will run as sequential Java on machines that do not have the parallel support or do not have an implemented Hydra runtime system without requirement of any modifications to the program. This paper describes the language, compares it with other languages (specifically with JOMP, an OpenMP implementation for Java), presents a brief discussion on compiling and executing Hydra programs, presents some sample benchmarks and their performance on three platforms, and concludes with a discussion of issues and future directions for Hydra. Copyright © 2007 John Wiley & Sons, Ltd.     

Residual Interactions of LL-37 with POPC and POPE:POPG Bilayer Model Studied by All-Atom Molecular Dynamics Simulation

LL-37 is a membrane-active antimicrobial peptide (AMP) that could disrupt the integrity of bacterial membranes due to its inherent cationic and amphipathic nature. Developing a shorter derivative of a long peptide such as LL-37 is of great interest, as it can reduce production costs and cytotoxicity. However, more detailed information about the residual interaction between LL-37 and the membrane is required for further optimization. Previously, molecular dynamics simulation using mixed all-atom and united-atom force fields showed that LL-37 could penetrate the bilayer membrane. This study aimed to perform all-atom molecular dynamics simulations, highlighting the residual interaction of LL-37 with the simplest model of the bacterial membrane, POPE:POPG (2:1), and compare its interaction with the POPC, which represents the eukaryotic membrane. The result showed leucine–leucine as the leading residues of LL-37 that first contact the membrane surface. Then, the cationic peptide of LL-37 started to penetrate the membrane by developing salt bridges between positively charged amino acids, Lys–Arg, and the exposed phosphate group of POPE:POPG, which is shielded in POPC. Residues 18 to 29 are suggested as the core region of LL-37, as they actively interact with the POPE:POPG membrane, not POPC. These results could provide a basis for modifying the amino acid sequence of LL-37 and developing a more efficient design for LL-37 derivatives.