Electronic detection of the enzymatic degradation of starch

[reaction: see text] The enzymatic degradation of starch can be monitored electronically using single-walled carbon nanotubes (SWNTs) as semiconducting probes in field-effect transistors (FETs). Incubation of these devices in aqueous buffer solutions of amyloglucosidase (AMG) results in the removal of the starch from both the silicon surfaces and the side walls of the SWNTs in the FETs, as evidenced by direct imaging and electronic measurements.     

Structure and properties of plasma-polymerized thin films of polyaniline

Plasma polymerization of aniline and in-situ doping of polvaniline with iodine was carried out using radio frequency glow discharge. Thin films of polyaniline were deposited on platinum and glass. The infrared spectrum shows that the aromatic ring is retained under the plasma conditions. The electrical conductivity measurements indicate that the conductivity increases by more than seven orders of magnitude when the polyaniline is doped by iodine. The scanning electron microscopic studies reveal the formation of irregular pentagons on glass substrate while on platinum, polvaniline forms a fibrillar network. In both the cases a continuous film is obtained.     

Kinetics of the Effect of Some Bidentate Amino Acid Ligands in the Oxidation of Lactic Acid by Chromium(VI)1

The oxidation of lactic acid by Cr(VI) under acidic conditions is catalyzed by bidentate amino acid ligands such as glycine, alanine, aspartic acid and hydroxyproline. Catalysis is a function of [L]/[Cr(VI)] ratio and acidity. Pyruvic acid and acetaldehyde in a ratio of 2 : 1 are obtained as oxidation products in both uncatalyzed and catalyzed oxidation. This supports the previous understanding of the oxidation of -substituted carboxylic acids. Cromium(V) and chromium(VI) behave similarly in a C–H bond rupture (Rocek, J. and Radkowsky, A.E., J. Am. Chem. Soc., 1973, vol. 95, p. 7123), whereas Cr(IV) is responsible for C–C bond cleavage products (Wiberg, K.B. and Schafer, H., J. Am. Chem. Soc., 1969, vol. 91, p. 927).     

Nonradiative energy transfer from Tb3+ → Er3+ in calibo glass

Energy transfer studies have been made in a terbium-erbium coactivated calibo-glass system at room temperature and at liquid-air temperature. A study of the emission and decay of ⁵D₄ level of Tb³⁺ has been made by varying the acceptor (Er³⁺) concentration. Probabilities and efficiencies of energy transfer as well as donor-acceptor distances have been calculated. At low acceptor concentration the decay of the donor (Tb³⁺) emission has been found to be diffusion limited. At high acceptor concentration the mechanism governing the transfer is found to be dipole-dipole.     

Coulometric determination of uranium and iron or plutonium in a single aliquot using platinum working electrode

A controlled potential coulometric method developed earlier for the determination of uranium in the presence of iron or plutonium using platinum working electrode was extended for individual determination of uranium and iron or plutonium in single aliquot. After uranium determination, Fe(III) or Pu(IV) in the aliquot is reduced electrolytically to Fe(II) or Pu(III) and subsequently determined by electrolytic oxidation to Fe(III) or Pu(IV), respectively. Analysis of synthetic solutions indicated that the values for uranium, iron and plutonium obtained by this method are reproducible within±0.2% and are in good agreement with values obtained using conventional redox methods 1, 2.     

Synthesis of some new fluorine containing 3-dialkylaminomethyl indoles, 3-indolylglyoxamides and tryptamines

Several new 2-(fluoroaryl)-3-dialkylaminomethylindoles, 3-acetyl-2-(fluoroaryl)-indoles, 2-(fluoroaryl)-3-indolylglyoxamides and corresponding tryptamines have been prepared as possible psychopharmacological agents. 2-(Fluoroaryl)-indoles have been synthesized by theFischer indole synthesis. 2-(Fluoroaryl)-indoles on treatment with oxalyl chloride and subsequent reaction with amines, gave 2-(fluoroaryl)-3-indolylglyoxamides. Some of these indolylglyoxamides were reducted with lithium aluminium hydride, to the corresponding tryptamines. 2-(Fluoroaryl)-indoles when subjected toMannich reaction afforded 3-dialkylaminomethyl-2-(fluoroaryl)-indoles. All these new compounds have been characterized by IR spectral studies.Possible Psychopharmacological Agents, Part XII, Part XI, J. Indian. Chem. Soc.57, 423 (1980).     

2,4,6-Trichloro-1,3,5-triazine catalyzed synthesis of thiiranes from oxiranes under solvent-free and mild conditions

A simple, mild and efficient method has been developed for the synthesis of thiiranes from epoxides using a catalytic amount of 2,4,6-trichloro-1,3,5-triazine under solvent-free conditions.     

Spectrographic estimation of Ga, In and Tl in semiconductor grade selenium

Summary An emission spectrographic method for the estimation of Ga, In and Tl in semiconductor grade selenium at less than a ppm concentration has been developed. The impurities were separated from 1 g of selenium by volatilizing it from its solution in nitric acid and sulphuric acid. The residue containing the impurities was dissolved in small amounts of 6 M HCl and was loaded along with the washings on 10 mg mixture containing graphite (90%) and sodium chloride carrier (10%) in the electrode crater. The spectra were excited in a d.c. arc carrying 13 A current. The detection limits lie in the range of 0.0025–0.005 ppm. The precision of the method ranges from 7–12% for these elements. The recoveries of impurities from selenium were confirmed using radioactive tracers.

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Spektrographische Bestimmung von Gallium, Indium und Thallium in Halbleiterselen

Zusammenfassung Eine 1 g-Probe wird in Salpeter- und Schwefelsäure gelöst und die Verunreinigungen durch Verflüchtigung des Selens isoliert. Sie werden in 6 M HCl gelöst und zusammen mit einem Graphit/NaCl-Gemisch (91) in die Elektrode eingebracht. Zur Anregung dient ein Gleichstrombogen (13 A). Die Nachweisgrenzen liegen im Bereich von 0.0025–0.005 ppm, der Variationskoeffizient bei 7–12%. Die Wiedergewinnung der Verunreinigungen wurde mit Hilfe von Radioindicatoren geprüft.