Advances in the chemical leaching (inorgano-leaching), bio-leaching and desulphurisation of coals

International Journal of Coal Science & Technology - Coal still remains an important source of power generation world over. Along with its usage, comes unwanted generation of noxious gas...     

Effect of defects on the electronic properties of WS2 armchair nanoribbon

We have studied the WS₂ armchair nanoribbon with various defects like vacancy, edge roughness, twist, turn and ripple and compared how the bandgap changes due to such defects with the bandgap of a nanoribbon with no defects. Materials like WS₂ and other transition metal dichalcogenides (MX₂) have a graphene like layered structure with hexagonal rings and have properties that have attracted a lot of interest. Hence it is essential to study the changes in the band structure of the nanoribbon of WS₂ due to the inclusion of defects like vacancy, rough edge, wrap, ripple and twist for making any device based on WS₂.     

Interaction of SH-waves by a Griffith crack in an infinite transversely isotropic medium

As a follow-on to a previous problem involving imposed P-waves, the diffraction of SH-waves by a finite Griffith crack located on a symmetric surface of an infinite transversely-isotropic medium is considered. A Fredholm integral equation is derived for the determination of diffracted field. From the integral equation length symptotic development of the solution is obtained which is valid for wavelength compared to the crack length. For wavelengths comparable with the size of the crack, the integral equation is solved numerically. The stress-intensity factor and displacement field in the vicinity of the crack are compared for a range of values of frequency. The approximate solution is compared with the exact solution.

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Résumé Comme suite à l'étude d'un problème précédent, dans lequel on imposait un régime d'ondes de type P, on a considéré la diffraction d'ondes SH par une fissure finie de Griffith située sur la surface symétrique d'un milieu transversalement isotrope. On a déduit une équation intégrale de Fredholm pour déterminer le champ de diffraction. On en a tiré une solution en développement asymptotique qui est valable lorsque la longueur d'onde est grande par rapport à la longueur de la fissure. Pour des longueurs d'onde comparables à la longueur de la fissure, on résoud l'équation intégrale par voie numérique. On compare le facteur d'intensité d'entaille et le champ de déplacement dans le voisinage de la fissure pour diverses valeurs de fréquence.La solution approchée est comparée à la solution exacte.

     

Adriamycin induces apoptosis in rat thymocytes

Apoptosis is a controlled form of cell death accompanied by distinct morphological and biochemical changes. In this study the nature of cytotoxicity induced by adriamycin (ADM) in rat thymocytes was evaluated. Morphological and biochemical changes characteristic of apoptosis were found to precede adriamycin-induced cell death. Our findings demonstrate the involvement of c-Myc, c-Jun, antioxidant enzymes CuZn superoxide dismutase and catalase, and perhaps poly ADP ribosylation in ADM-induced cell death.     

Andrographolide protects rat hepatocytes against paracetamol-induced damage

The authors' objective was to determine if, in the absence of known coronary artery disease, ST-T changes suggestive of silent ischemia on the admission electrocardiogram (ECG) identify a group of patients at high risk for cardiac event or death. A prospective cohort study was undertaken at the university hospital of a tertiary care center. All patients admitted to the hospital during the 5-month study period were screened. The authors found 54 patients with risk factors but no symptoms of coronary artery disease whose admission ECGs showed silent ischemia (ischemia group), and 71 patients with similar risk of coronary artery disease but without admission ECGs showing silent ischemia (control group). Three-week and 6-month incidences of angina, myocardial infarction, and death among patients in the silent ischemia and control groups were compared. Seven (13%) patients in the silent ischemia group had cardiac events or noncardiac death in the subsequent 3 weeks versus one (1%) noncardiac death in the control group (p < 0.02). At 6 months, eight (15%) patients in the silent ischemia group versus two (3%) in the control group had cardiac events (p = 0.02). It is concluded that among patients with risk factors but no symptoms of coronary artery disease, silent ischemia on the admission ECG is associated with an increased likelihood of short-term death or cardiac event.     

A new approach to the measurement of resolution and sampling on apositron emission tomograph

Two technical difficulties underlie the accurate determination of spatial resolution in positron emission tomography (PET): (1) measuring the full-width half-maximum (FWHM) and full-width tenth-maximum (FWTM) from undersampled profiles; (2) measuring axial resolution from multiple reconstructed data sets. To address the first problem, a technique that involves a quadratic estimation of the peak of the profile distribution was developed. This method was compared with the standard technique of Gaussian fitting and was found to be as accurate for constant background distributions. For axial resolution, a second method involving a single scan and imaging of line sources oriented 45 degrees to the axis of the scanner was proposed. Axial FWHM estimations were achieved by deconvolving the values obtained with line spread functions from sources placed parallel to the axis of the scanner. This technique was validated by comparing the results with those obtained by others using a multiple-scan technique on a similar machine