Structure and phase stability of hydrogenated first-stage alkali- and alkaline-earth metal–graphite intercalation compounds

We report the hydrogenation temperature and pressure dependence of hydrogen absorption capacity in CaC₆. In addition, the structure and phase stability of hydrogenated CaC₆, LiC₆ and KC₈ has been investigated using X-ray diffraction and Raman spectroscopy. It is found that the hydrogen chemisorption in both CaC₆ and LiC₆ leads to either metastable or higher stage intermediate compounds but eventually leaves completely deintercalated graphite by forming stable metal hydrides. In contrast hydrogenation of KC₈ generates a restaged ternary hydride compound. The phase stability of hydrogenated compounds is discussed in the text based on the observed experimental results and correlated to the thermodynamic and kinetic aspects of intercalated metal.     

Isolation and purification of a novel antioxidant protein from the water extract of Sundakai (Solanum torvum) seeds

Reactive oxygen species (ROS) at physiological concentrations may be required for normal cell function. Excessive production of ROS can be detrimental to cells, because ROS can cause oxidative damage to lipids, proteins, and DNA. Herein, we describe the isolation and purification of a novel antioxidant protein the water extract of dried, powdered Sundakai (Solanum torvum [Solanaceae]) seeds. Sundakai belongs to the Solanaceae family, a small shrub, which is distributed widely in India, Malaya, China, Phillipines and tropical America. Fifty percent of ammonium sulphate-precipitated crude water extract was fractionated on a Sephadex G100 column, which yielded two peaks, PI and PII. Peaks PI and PII inhibited lipid peroxidation up to 40% and 89%, respectively in linolenic acid micelles. Rechromatographing of peak PII on Sephadex G100 yielded a single peak, indicating the homogeneity of the purified protein. SDS–PAGE analysis indicated the molecular weight of the purified protein to be ∼28 kDa. The purified protein, at 0.8 μM, inhibited deoxyribose degradation induced by generation of hydroxyl radicals by 90% and scavenged DPPH (1,1-diphenyl-2-picrylhydrazyl) radicals by 76%. The reducing power and chelating power of the purified protein, at 0.8 μM, were found to be 72% and 85%, respectively. The protein, at 0.8 μM, also offered significant protection to calf thymus DNA damage induced by H₂O₂ (1 mM). Therefore, the present study demonstrates, for the first time, a novel protein from the water extract of Sundakai seeds as an excellent antioxidant.     

Quantitative image quality analysis of a nonlinear spatio-temporalfilter

Digital temporal and spatial filtering of fluoroscopic image sequences can be used to improve the quality of images acquired at low X-ray exposure. In this study, we characterized a nonlinear edge preserving, spatio-temporal noise reduction filter, the bidirectional multistage (BMS) median filter of Arce (1991). To assess image quality, signal detection and discrimination experiments were performed on stationary targets using a four-alternative forced-choice paradigm. A measure of detectability, d', was obtained for filtered and unfiltered noisy image sequences at different signal amplitudes. Filtering gave statistically significant, average d' improvements of 20% (detection) and 31% (discrimination). A nonprewhitening detection model modified to include the human spatio-temporal visual system contrast-sensitivity underestimated enhancement, predicting an improvement of 6%. Pixel noise standard deviation, a commonly applied image quality measure, greatly overestimated effectiveness giving 67% improvement in d'. We conclude that human testing is required to evaluate the filter effectiveness and that human perception models must be improved to account for the spatio-temporal filtering of image sequences.     

Curcumin–amino acid conjugates: Synthesis,antioxidant and antimutagenic attributes

Curcumin, a natural yellow colourant from turmeric, is insoluble in water. It has been rendered water-soluble by preparation of suitable amino acid derivatives. Several amino acid conjugates of curcumin were synthesised in high yields (45–76%). These curcumin derivatives were soluble in water at 1–10 mg/ml concentrations. Derivatives of curcumin with alkyl-substituted amino acids, such as alanine, valine, serine and cysteine, exhibited smaller IC₅₀ values (∼50%) than did curcumin in antioxidant assays. With respect to antimutagenicity against Salmonella typhimurium TA 98 and TA 1531, the derivatives showed an effect stronger than or, in a few cases, similar to curcumin. These results clearly demonstrated that the conjugation of curcumin at the phenolic position with amino acids, while rendering the molecule water-soluble, led to the improvement of several of its in vitro biological attributes, the effect being more pronounced in the case of specific alkyl-substituted amino acids.     

Preparation and characterization of non-random YBa2Cu3O7-Ag composite

Silver addition to the highT _c superconductor, YBa₂Cu₃O₇ (YBCO) is known to improve its mechanical properties and critical current (J _c) characteristics. We have synthesized the superconductor-metal composite YBCO-Ag by an electroless process at room temperature (using sucrose or hydrazine hydrate in an alkaline medium). The latter method produces a non-random coating whereby each grain of YBCO is coated uniformly by silver. The intrinsic highT _c of 90 K of YBCO can be recovered by compaction of the composite and subsequent heat treatment (900°C and 600°C) in oxygen.     

Do vision and haptics share common representations? Implicit and explicit memory within and between modalities.

Previous assessments of verbal cross-modal priming have typically been conducted with the visual and auditory modalities. Within-modal priming is always found to be substantially larger than cross-modal priming, a finding that could reflect modality modularity, or alternatively, differences between the coding of visual and auditory verbal information (i.e., geometric vs phonological). The present experiments assessed implicit and explicit memory within and between vision and haptics, where verbal information could be coded in geometric terms. Because haptic perception of words is sequential or letter-by-letter, experiments were also conducted to isolate the effects of simultaneous versus sequential processing from the manipulation of modality. Together, the results reveal no effects of modality change on implicit or explicit tests. The authors discuss representational similarities between vision and haptics as well as image mediation as possible explanations for the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhythms of Life: Antecedents and Outcomes of Work-Family Balance in Employed Parents.

This study examined antecedents and outcomes of a fourfold taxonomy of work-family balance in terms of the direction of influence (work-family vs. family-work) and type of effect (conflict vs. facilitation). Respondents were full-time employed parents in India. Confirmatory factor analysis results provided evidence for the discriminant validity of M. R. Frone's (2003) fourfold taxonomy of work-family balance. Results of moderated regression analysis revealed that different processes underlie the conflict and facilitation components. Furthermore, gender had only a limited moderating influence on the relationships between the antecedents and the components of work-family balance. Last, work-family facilitation was related to the work outcomes of job satisfaction and organizational commitment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DSP based inverter control for alternate energy systems

This paper presents a DSP based algorithm to control inverters used in interfacing alternate energy systems with the electric utility. Since a constant and ripple free dc bus voltage is not ensured at the output of alternate energy sources, the main aim of the proposed algorithm is to make the output of the inverter immune to the fluctuations in the dc input voltage. In this paper a modified space vector pulse width modulation (SVPWM) technique is proposed which will maintain the quality of the ac output of the inverter, regardless of the ripple present at the inverter input. The principle is explained qualitatively and extensive experiments have been carried out to verify and validate the proposed algorithm. A 16-bit fixed-point C2000 family DSP from Texas Instruments was used as the controller to implement the proposed control algorithm.