Effect of Pd and Pt additives on the activity of Ni?Cr catalysts in reaction of CO with H2

Introduction of small amounts of Pt or Pd into Ni–Cr catalysts decreases temperature of their reduction with H₂, and enhances their methanation activity and stability to carbonization. These phenomena are interpreted in terms of spillover of extra hydrogen from Pt or Pd which participates in hydrogenation of active carbon species on Ni surface.

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Pt Pd Ni–Cr H₂, . Pt Pd, Ni.

     

Temperature effect on the composition and activity of iron(III) stearate based organometallic catalysts in hydrogenation reactions

The observed temperature dependence of the composition of FeSt₃–AlEt₃ catalytic system indicates that with increasing temperature the maximum catalytic activity and the content of the associated polynuclear complex change in parallel. This complex probably plays a decisive role in catalytic processes.

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FeSt₃–AlEt₃ . . , .

     

Synthesis and properties of peptide fragments of the S-region of the surface protein of the heptatitis B virus

A peptide fragment with the 140–146 sequence of the main component of the surrace protein of the hepatitis B virus (HBsAG) and a number of its structural analogues have been synthesized by the classical method in solution. Conjugates of the peptides synthesized with bovine serum albumin and with a synthetic polypeptide analogue of polytuftsin have been obtained. The ability of the preparations to bind antibodies from the blood sera of hepatitis B patients has been studied. The possibility has been shown of their use for revealing antibodies to the heptatitis B virus in solid-phase enzyme-mediated immunoassay.Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 406–413, May–August, 1992.     

Hydrochloride method for the determination of monomer in the polycondensation of esters of α-amino acids

Summary A method is proposed for determining the monomer in the polycondensation of esters of-amino acids. The accuracy of the method was to within 1–1.5%.     

The study of Ziegler-Natta type organometallic catalysts in hydrogenation

The system, Fe(C₁₇H₃₅COO)₃-Al(C₂H₅)₃, has been studied directly in the process of cyclohexane and phenylacetylene hydrogenation. It is shown that the system composition can vary in the course of the catalytic process. The effect of unsaturated compounds on the system composition depends on their ability to serve as ligands.     

Gold microelectrode ensembles: cheap,reusable and stable electrodes for the determination of arsenic (V) under aerobic conditions

The determination of total arsenic through As(V) anodic stripping voltammetry (ASV) is, in some cases, preferable over As(III) ASV. The As(V) ASV procedure has no chemical reduction step from As(V) into As(III), which results in decreased analysis time and no contamination from reducting reagents. A simple and reliable procedure of As(V) determination is proposed. Anodic stripping determination of trace As(V) at gold microelectrode ensembles in diluted HCl solution in the presence of dissolved oxygen is shown. The electrode is based on a carbon black (30%)–polyethylene composite. The sensor was prepared by gold electrodeposition on the surface of the composite electrode. The given sensor is cheap, reliable and stable, especially when electrochemical activation is employed. The experimental parameters for the electrochemical determination were optimized, namely 0.005?M HCl as the background electrolyte, the deposition potential ?2.2?V (versus Ag/AgCl in 1?M KCl) and 180?mV?s^?1 linear scan rate. Calibration curves were obtained and were linear in [As(V)] over the 1.5–45?µg?L^?1 range, with a LOD of 0.5?µg?L^?1. The effect of common interfering species is studied. The electrochemical behaviour of As(III) form is studied in the same experimental conditions. It was found that As(III) is deposited at lower potentials (starting at ?0.6?V) and the sensitivity of As(III) detection is higher, but dependant on the presence of dissolved oxygen. The speciation of inorganic forms of arsenic is discussed.