Electrical switching studies of lead-doped germanium telluride glasses

Samples of bulk Ge₂₀Te_80-xPb_x(2x8) glasses have been prepared by melt quenching and their electrical switching behavior has been investigated as a function of lead content and sample thickness. The samples are found to exhibit a threshold type of switching. The switching voltages are found to decrease with increase in lead content and they show an anomaly at the composition x=5 and a minimum at the composition x=7.5 respectively. The samples are found to withstand about 28 switching cycles, before latching permanently to the ON state. PACS 61.43.Dq; 61.43.Fs; 72.20.Ht; 72.80.Ng; 73.61.Jc; 84.32.Dd; 85.30.Fg     

Sodium N-chloro-p-nitrobenzenesulfonamide (chloramine-N) as a new redox titrant: I. The status of chloramine-N as a titrimetric reagent

The status of sodium N-chloro-p-nitrobenzenesulfonamide (chloramine-N) as a new redox titrant is examined. Analytical applications of CAN as a potential titrimetric reagent in the direct determination of diverse reducing agents such as glutathione, thioglycolic acid, thiourea, ascorbic acid, methionine, sulfite, and arsenite have been described. CAN has been synthesized and its structure elucidated from the spectral data and elemental analyses. The ultraviolet and infrared spectra and Fourier transform ¹H and ¹³C nuclear magnetic resonance spectral data have been presented.     

Substituted phenothiaziiies as indicators in the ferrocyanide titration of zinc

Chlorpromazine, promethazine and diethazine hydrochlorides and prochlorperazine maleate have been tested as indicators in the ferrocyanide titration of zinc. Only the first and last are useful, giving a sharp reversible colour change in both the direct and reverse titrations, but the results are negatively biased by 0.2-1.3%.     

Kinetics and Thermodynamics of Glycans and Glycoproteins Binding to Holothuria scabra Lectin: A Fluorescence and Surface Plasmon Resonance Spectroscopic Study

Holothuria scabra produces a monomeric lectin (HSL) of 182 kDa. HSL showed strong antibacterial activity and induced bacterial agglutination under in vitro conditions, indicating its role in animals’ innate immune responses. Very few lectins have been reported from echinoderms and none of these lectins have been explored in detail for their sugar-binding kinetics. Affinity, kinetics and thermodynamic analysis of glycans and glycoproteins binding to HSL were studied by fluorescence and surface plasmon resonance spectroscopy. Lectin binds with higher affinity to O-linked than N-linked asialo glycans, and the affinities were relatively higher than that for sialated glycans and glycoproteins. T-antigen α-methyl glycoside was the most potent ligand having the highest affinity (Ka 8.32 ×10⁷ M^?1). Thermodynamic and kinetic analysis indicated that the binding of galactosyl Tn-antigen and asialo glycans is accompanied by an enthalpic contribution in addition to higher association rate coupled by low activation energy for the association process. Presence of sialic acid or protein matrix inhibits binding. Higher affinity of HSL for O-glycans than N-glycans had biological implications; since HSL specifically recognizes bacteria, which have mucin or O-glycan cognate on their cell surfaces and play a major role in animal innate immunity. Since, HSL had higher affinity to T-antigen, makes it a useful tool for cancer diagnostic purpose.