On the Global Integrability of Non-Negative Harmonic Functions

Let ⁺(D) be the set of all non-negative harmonic functions on a domain DR^d. Let q>0 and define L^q(D) to be the set of all Borel functions f such that |f|^q is Lebesgue-integrable on D. Let x₀D. N. Suzuki established the following:

An Analogue of Beurling–Hörmander’s Theorem Associated with Partial Differential Operators

In this paper for a positive real number α we consider two partial differential operators D and D_α on the half–plane We define a generalized Fourier transform associated with the operators D and D_α. We establish an analogue of Beurling–H?rmander’s Theorem for this transform and we give some applications of this theorem.     

The reaction of nitriles with mercaptoacetic acid. A new synthesis of thiazole derivatives

The reaction of mercaptoacetic acid with nitriles was investigated. Whereas 4-hydroxythiazole derivative could be obtained from the reaction of benzoylacetonitrile and of ethyl cyanoacetate with mercaptoacetic acid, a bithiazole derivative was obtained on treatment of benzonitrile with the same reagent. The behaviour of the synthesised thiazole derivatives towards aromatic aldehydes and hydrazines is reported.     

Extraction of some lanthanides by 12-crown-4 and 15-crown-5 from perchlorate media as ion pairs

The extraction of the trivalent lanthanides Eu, Tm and Yb(Ln) by crown ethers (CE) 12-crown-4 (12C4) and 15-crown-5 (15C5) in chloroform from perchlorate aqueous media of constant ionic strength is investigated. The effect of [H⁺], [CE] and [ClO ₄ ^– ] on the respective distribution ratio (D) is elucidated. Slope analysis of these results indicated that the extracted species are of the type Ln(OH) ₂ ⁺ ·ClO ₄ ^– (CE)₂. The extraction constants obtained are in the sequence 15C5>12C4 for the CE's and EuTm<Yb for the elements investigated. Based on the separation factors elucidated, Tm(III) and Yb(III) are separated from Eu(III) with high radiochemical purity; >99.5% by three (or four) successive extraction and strippings.     

Spectrophotometric microdetermination of uranium with m- and p-carboxyphenylazo-chromotropic acid

Summary A simple and rapid method for the spectrophotometric determination of uranium usingm- andp-carboxyphenylazo-chromotropic acid is given. The optimum conditions favouring the formation of the two complexes are reported. The molecular structure was found to be 1 1 and 1 2 of uranium to them- or thep-compound. Beer's law is obeyed for the ranges 2–16 and 2–18 ppm of uranium in the case of them- andp- compound respectively.

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Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Uran mit Hilfe vonm-bzw.p-Carboxyphenylazochromotropsäure wurde beschrieben. Die besten Arbeitsbedingungen für die Bildung der beiden Komplexe wurden angegeben. Die Zusammensetzung entspricht dem Verhältnis 1 1 bzw. 1 2 von Uran zurm-bzw. zurp-Verbindung. Das Beer'sche Gesetz ist für die Bereiche 2–16 bzw. 2–18 ppm Uran im Falle derm-bzw. derp- Verbindung erfüllt.

     

Degenerated nonlinear hyperbolic equation with discontinuous coefficients

The partial differential equations with discontinuous coefficients have been extended in various directions by a number of authors [2], [3], [11], [13], [14], [16]. This paper deals with a mixed problem for a degenerated nonlinear hyperbolic equation with discontinuous coefficients.     

The acid-base properties of Chromotrope 2 B

Summary The acid-base properties of Chromotrope 2 B have been studied, in an attempt to apply it as a metallochromic, a chromophoric or an acid-base indicator. The pK values corresponding to the four steps of ionization of the free acid are evaluated and the modes of dissociation and chelation are elucidated. As an acid-base indicator Chromotrope 2 B has proved to be similar in behaviour to phenol-phthalein with a determined pH interval of 7.5–9.5.

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Zusammenfassung Die Säure-Base-Eigenschaften des Farbstoffs Chromotrop 2 B wurden im Hinblick auf seine Verwendung als pH- oder metallochromer Indicator untersucht. Die pH-Werte der vier Ionisationsstufen wurden ausgewertet und die Dissoziation sowie die Komplexbildung aufgeklärt. Chromotrop 2 B ist als Säure-Base-Indicator dem Phenolphthalein ähnlich (pH-Bereich 7,5–9,5).

     

Electrodeposited metals at conducting polymer electrodes: I—Effect of particle size and film thickness on electrochemical response

Conducting polymers are electrochemically polymerized at platinum electrode substrates. The thickness, porosity and surface morphology of the resulting films are controlled by the charge passing during electropolymerization step and the synthesis conditions. The polymer films are modified by electrochemically depositing platinum particles. The technique of deposition depends on applying a programmed potential pulse at the polymer film from a solution containing platinum complex that resulted in the formation of platinum particles of controlled size and distribution. The effect of changing the size of platinum particles and polymer film thickness on the voltammetric behavior of the resulting hybrid material showed noticeable changes in the electro-catalytic current in acid medium. On the other hand, the electrochemical impedance spectroscopy experiments showed that diffusion and charge-transfer rate increased in the order: unmodified polymer films, thin polymer films containing small size/amount of platinum particles and relatively thick polymer films containing larger size/amount of platinum particles. The morphology of polymer films, size and distribution of platinum particles in the film were studied by scanning electron microscopy. The presence of platinum and its distribution over the film surface was confirmed from the X-ray dispersive analysis and surface mapping. The hybrid materials are good candidates for the application in devices for exchange of hydrogen ions.     

Interaction of hydrogen with InN thin films elaborated on InP(1 0 0)

III-V semiconductor compound structures are widely applied in technology of advanced microelectronics, optoelectronics, and gas sensors. In this paper, we report on the use of XPS to characterize in situ the interaction of thermally activated hydrogen atoms and hydrogen molecules with InP(1 0 0) surfaces covered by thin InN overlayers. XPS spectra were taken with an ESCALAB-210 spectrometer after repeated hydrogenation cycles at temperatures up to 350 °C. The evolution of the In 3d, In 4d, P 2p, N 1s, O 1s and C 1s photoelectron spectra was carefully monitored. The XPS spectra of the hydrogen exposed surface revealed significant differences compared to those from the non-hydrogenated surface. InN films were found to be weakly reactive to hydrogen under experimental conditions explored. The behavior of P atoms at the hydrogenated surface was dependent on the parameters characterizing each hydrogenation (exposure, hydrogen species used, annealing temperature). Moreover, the heavily hydrogenated surface exhibited a phosphorus enrichment.     

Microbial transformation of 5-episinuleptolide

5-episinuleptolide (1) is an abundant norcembranolide diterpene isolated from several species of the soft coral genus Sinularia. Biocatalytic transformation studies of 1 using Streptomyces lavendulea ATCC 8664 resulted in the isolation and characterization of two new metabolites 2 and 3. Compound 2, 6alpha-hydroxy-5-episinuleptolide was produced via a stereoselective reduction of 1 and was further metabolized into compound 3 which has a 3,8-bicylized cembranoid skeleton. The structures and configurations of the metabolites were determined by spectroscopic and X-ray crystallographic analyses.