Endothermic quasicrystalline-to-crystalline phase transition in Al6CuMg4

Electron microscopic and differential scanning calorimetric (DSC) studies have been performed to investigate the phase transitions in the rapidly solidified Al₆CuMg₄ alloy system. We present evidence, for the first time, that anendothermic quasicrystalline to crystalline transition occurs in this system around 340°C. This is an unexpected feature—for conventional wisdom would lead one to expect exothermic behaviour as was seen in Al₈₆Mn₁₄—and points to the fact that stability of certain quasicrystalline phases may be much larger than hitherto expected. Some comments on the recently reported large quasicrystal for the Al₆CuLi₃ system are also made in the light of our observation.     

Energy deposition of fast α particles in a fully ionized deuterium-tritium plasma

An α particle transport equation has been solved analytically in one-dimensional spherical geometry when the plasma properties are uniform in space and time. The results agree well with earlier results.     

Chemical and biotechnological developments in organotin cancer chemotherapy

This review provides a substantial knowledge on the action mode of organotins in cancer chemotherapy. The coordinating ability of organotin compounds towards DNA and cancer cells is discussed. Most of the organotins tested are DNA-targeted and mitotic, the action mode occurring via a gene-mediated pathway. These potential anti-cancer drugs are actually being studied widely, and whilst they are efficacious and perhaps curative against a select number of neoplasias, suffer from a variety of deficiencies, notably severe systemic toxicity and a tendency to elicit drug resistance.     

Designing,antifungal and structure activity relationship studies of Azomethines and β-lactam derivatives of aza heterocyclic amines

The present investigation deals with the synthesis of seven azomethine derivatives 1–7 of aza heterocyclic amines by carrying out condensation reaction of them with veratraldehyde followed by cyclizing the CHN moiety in synthesized azomethines of 4-amino-1,2,4-triazole and 4-amino antipyrine to yield β lactam derivatives 8–9. The chemical constituents in the synthesized compounds were confirmed by UV, IR, 1H NMR, ¹³C NMR, and elemental analysis. In vitro antifungal activity of all the synthesized products was done against four pathogenic maize fungal strains i.e. Fusarium verticillioides, Macrophomina phaseolina, Rhizoctonia solani, and Dreschlera maydis. It was found that azomethine derivative having 4-amino-1,2,4-triazole ring was as effective as standard carbendazim 50 WP against R. solani and may be considered as promising antifungal agent; therefore further modifications may be done in its structure to get better drug candidate in future.     

Simultaneous monitoring of the decay of density and average energy of electrons in the early afterglow of pulsed N2 discharges

Temporal decay of both the density and the average energy of electrons is simultaneously monitored in the early afterglow of pulsed N₂ discharges. Results show the ambiguities associated with the interpretation of electron density decay curves under the possible influence of ionizing metastable-metastable collisions.     

The master-slave paradigm in parallel computer and industrial settings

The master-slave paradigm finds important applications in parallel computer scheduling, semiconductor testing, machine scheduling, transportation, maintenance management and other industrial settings. In the master-slave model considered in this paper a set of jobs is to be processed by a system of processors. Each job consists of a preprocessing task, a slave task and a postprocessing task that must be executed in this order. The pre- and post-processing tasks are to be processed by a master processor while the slave task is processed by a slave processor. In this paper, we motivate the master-slave model and develop bounded performance approximation algorithms for the unconstrained makespan minimization problem as well as for multiple master systems.This work was supported in part by the National Science Foundation under grant MIP-9103379 and the Army Research Office under grant DAA H04-95-1-0111.     

Accurate and easy method for work function calculations

The applicability and accuracy of the “displaced-profile change-in-self-consistent-field” (DPΔSCF) formalism for the work function are demonstrated by calculations for the jellium metal surface. The DPΔSCF expression is as easy to evaluate as the usual Koopmans' theorem expression for the work function, but is much more accurate when the electron density is obtained from Rayleigh-Ritz variational calculations of the surface energy. Use of the method in calculations for real metals is indicated.     

Characterization of pure and doped potassium hydrogen tartrate single crystals grown in silica gel

Growth of pure‐, sodium‐ and lithium‐ doped potassium hydrogen tartrate single crystals by gel technique is reported. Growth conditions conducive for the growth of single crystals are worked out. The crystals are characterized by using powder XRD, SEM, FTIR, AES, EDAX, CH analysis and thermoanalytical techniques. The stoichiometric composition for the grown crystals are established as KHC₄H₄O₆.H₂O, (K)_0.98(Na)_0.02.H₂O and (K)_0.94(Li)_0.06HC₄H₄O₆.H₂O. Doping of sodium and lithium in the pure potassium hydrogen tartrate single crystals is found to influence the size, perfection, morphology, crystal structure and the thermal stability of crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)