Gravimetric and thermogravimetric studies of zinc and mercury with benzimidazole

Summary Methods are proposed for the gravimetric determination of zinc and mercury with benzimidazole at pH ranges of 8.4–10.0 and 9.0–10.0, respectively. Using suitable masking agents zinc has been separated from a large number of diverse ions. Thermograms of the zinc and mercury complexes reveal that they are extraordinarily stable up to 520° and 340°C.

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Zusammenfassung Zur gravimetrischen Bestimmung von Zink oder Quecksilber wird die Fällung mit Benzimidazol bei pH 8,4–10,0 bzw. 9,0–10,0 empfohlen. Zink kann bei Verwendung geeigneter Maskierungsmittel mit guter Genauigkeit von zahlreichen Fremdionen abgetrennt werden. Durch thermogravimetrische Untersuchungen wurde festgestellt, daß die Zn-bzw. Hg-Komplexe bis zu 520 bzw. 340° C beständig sind.

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The work was carried out at Chemistry Department, Jadavpur University, Calcutta-32, India.     

Integrated GaAs f.e.t. mixer performance at X band

Experiments were performed at X band with GaAs f.e.t.s used as mixer elements. These studies show that an f.e.t. mixer may exhibit a conversion gain approaching that of the corresponding amplifier. Conversion gains as high as 6 dB were measured. Low noise and high signal-handling capabilities were also demonstrated.     

The impact of uniform strain applied via bonding onto plastic substrate on MOSFET performance

For the first time, this letter presents a novel post-backend strain applying technique and the study of its impact on MOSFET device performance. By bonding the Si wafer after transistor fabrication onto a plastic substrate (a conventional packaging material FR-4), a biaxial-tensile strain (/spl sim/0.026%) was achieved globally and uniformly across the wafer due to the shrinkage of the bonded adhesive. A drain-current improvement (average /spl Delta/I/sub d//I/sub d//spl sim/10%) for n-MOSFETs uniformly across the 8-in wafer is observed, independent of the gate dimensions (L/sub g//spl sim/55 nm -0.530 /spl mu/m/W /spl sim/2-20 /spl mu/m). The p-MOSFETs also exhibited I/sub d/-improvement by /spl sim/7% under the same biaxial-tensile strain. The strain impact on overall device characteristics was also studied, including increased gate-induced drain leakage and short-channel effects.     

Effect of P codeposition on the structure and microhardness of Co–W coatings electrodeposited from gluconate bath

Effects of addition of P to Co–W coatings from gluconate bath using direct current (DC) and pulse current (PC) methods have been investigated in this study. Co–W–P coatings with different P concentrations are prepared by varying hypophosphite concentration in the bath. Current efficiency of the Co–W–P electrodeposition is lower than that for Co–W coatings. Increase in NaH₂PO₂ concentration increases the cobalt content significantly and decreases the tungsten content drastically. Co–W–P coatings display ‘cauliflower‐like’ morphology and roughness of the coatings increases with increasing P content. As‐deposited Co–W–P deposits are amorphous while heat treatment at different temperatures has rendered them crystalline with the precipitation of stable species like, Co₃W, Co₂P, etc. Unlike Co–W coatings, Co–W–P shows two‐step crystallization in differential scanning calorimetry (DSC) and on heat treatment, which is similar to the behavior of Co–P electrodeposited from gluconate baths. Moreover, inclusion of phosphorous and heat treatment have led to significant increase in microhardness of the Co–W–P coatings. X‐ray photoelectron spectroscopy (XPS) studies provide a detailed insight into the nature of Co, W and P species in as‐deposited and sputtered coatings. Microhardness of the heat‐treated coatings is higher than the as‐deposited counterparts and is comparable with that of hard chromium. Copyright © 2016 John Wiley & Sons, Ltd.     

Palladium(II)‐Catalyzed meta‐C?H Olefination: Constructing Multisubstituted Arenes through Homo‐Diolefination and Sequential Hetero‐Diolefination

Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium‐catalyzed synthesis of divinylbenzenes by meta‐C H olefination of sulfone‐based arenes. Successful sequential olefinations in a position‐selective manner provided a novel route for the synthesis of hetero‐dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5‐trialkenylated compounds can be generated upon successful removal of the directing group.     

Kinetics and Mechanism of the Ligand Substitution Reaction of the Di-<Emphasis Type="Italic">μ</Emphasis>-hydroxobis(bipyridyl)dipalladium(II) Ion with some Bio-relevant Ligands

The interaction of di-μ-hydroxobis(bipyridyl)dipalladium(II) with the selected bio-relevant ligands: thioglycolic acid (HL¹), glutathione(HL²) and DL-penicillamine(HL³) has been studied spectrophotometrically in aqueous medium as a function of complex and ligand concentrations, pH, and temperature at constant ionic strength. Two consecutive reaction steps are observed: the first step is dependent on the incoming ligand concentration and the second step which is independent, is assigned to ring closure. The activation parameters, conductivity data and IR data obtained also support the proposed mechanism.