Effects of Calcination on the Physical and Photocatalytic Properties of TiO<Subscript>2</Subscript> Powders Prepared by Sol–Gel Template Method

TiO₂ powders were prepared by sol–gel template method and calcined under different conditions. XRD, BET and TEM were used to characterize the TiO₂ powders obtained. The photocatalytic activity of TiO₂ was investigated by the degradation of methyl orange. It was found that TiO₂ powder has the highest photocatalytic activity at a calcination temperature of 673 K. The effects of physical properties such as surface area, crystallinity and crystal phase on the photocatalytic activity of TiO₂ were discussed.     

Asymmetric synthesis of 2-substituted-3-aminocarbonyl propionic acid

An asymmetric synthetic route to 2-substituted-3-aminocarbonyl propionic acid, which is the significant component of low-molecular-weight renin inhibitors, is described. The key step of this synthesis is diastereoselective alkylation by using chiral oxazolidinone and benzyl bromoacetate.     

Isothermal titration calorimetric studies of surfactant interactions with negatively charged, ‘hairy’ latex nanoparticles

Isothermal titration calorimetry (ITC) measurements of the mixture of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) with negatively charged, hairy copolymer latices (poly-(2,3-epoxypropylmethacrylate-co-methacrylic acid) in different ratio) at high water excess indicate a monomer adsorption mechanism of CTAB by the polymer particles. The number of adsorbed CTAB molecules at saturation corresponds approximately to the number of negative elementary charges bound at the surface of the latices. The mixing enthalpy is the sum of demicellization and sorption enthalpies. At 25 °C for CTAB the demicellization enthalpy amounts to 10 kJ/mol, whereas the adsorption enthalpy varies from –7 kJ/mol (surface charge density of the latices =–0.37 C/m²) to +3 kJ/mol (=–0.085 C/m²). The hydrodynamic radius R_H of the latex particles upon titration of cationic detergent and salt (NaBr) decreases by about 2 nm until the onset of aggregation near the isoelectric point. Titration of nonionic or anionic detergents has much less influence on the hydrodynamic radius and produces no measurable adsorption heat. The results are consistent within a model of latex particles with extended negatively charged polymer chains interacting predominantly via Coulombic forces with detergents.     

The Influence of Cobalt (II) in Carboxymethyl Cellulose Processing

Controlling the reduction in molecular weight of the cellulose chains is essential in the production of carboxymethyl cellulose (CMC). Such a reduction can be achieved by the addition of cobalt during the process of cobalt(II) ions, which act as a catalyst for oxidative cleavage, and the influence thereof has been studied under a variety of conditions. This study has resulted in a model that summarises the effects of the added amount of cobalt, the time for the cobalt reaction, the temperature in the mercerisation stage of the CMC-manufacturing process and finally the effect of the temperature in the etherification stage. It is shown that it is important for cobalt to be present during the mercerisation stage in order to achieve the desired viscosity.     

A new series of antiallergic agents. I. Synthesis and activity of 11-(2-aminoethyl)thio-6,11-dihydrodibenz[b,e]oxepin derivatives.

A new series of 11-substituted 6,11-dihydrodibenz[b,e]oxepin derivatives was synthesized and evaluated for antiallergic activity. Convenient methods for the preparation of sulfides from alcohols were developed. Structure-activity relationships are described. Compound 7, 11-[2-(dimethylamin)ethyl]thio-6,11-dihydrodibenz[b,e] oxepin-2-carboxylic acid hydrochloride, was the most potent in the rat passive cutaneous anaphylaxis test (ED50 = 0.92 mg/kg p.o.). It had a potent inhibitory effect on anaphylactic bronchoconstriction in guinea pigs (ED50 = 0.029 mg/kg p.o.) and H1 receptor antagonistic effect (Ki = 14 nM) with few central nervous system side effects. Additionally, an antagonistic effect against prostaglandin D2-induced contraction of isolated guinea pig trachea (pA2 = 5.73) was an attractive mechanism of action of the new antiallergic agent. Compound 7 was selected for further evaluation as KW-4994.     

Influence of boric acid on the determination of iron in reactor coolant water by graphite furnace atomic absorption spectrometry

Summary The matric effect of boric acid was investigated in the determination of iron in the primary circuit coolant water of nuclear power plants by furnace atomic absorption spectrometry. The effect of boric acid was of particular interest. The method was applied during refuelling and maintenance periods and the results were used to interpret the chemical changes in the water.

---

Einfluß von Borsäure auf die Bestimmung von Eisen in Reaktorkühlwasser durch GF-AAS

     

Theoretical and Experimental Studies on a Metallorganic Complex of (Isopropylxanthato)(Phenyl)Mercury(I) [Hg(I)(C<Subscript>6</Subscript>H<Subscript>5</Subscript>)(C<Subscript>4</Subscript>H<Subscript>7</Subscript>OS<Subscript>2</Subscript>)]

The title compound, (isopropylxanthato)(phenyl)mercury(I), was synthesized and characterized by elemental analysis, IR and thermogravimetric analysis. Density functional theory (DFT) method calculations were performed at B3LYP/CEP-121G and B3LYP/CEP-31G levels of theory, respectively. Vibrational frequencies were predicted, assigned, compared with the experimental values, and they are supported each other. The calculated results show that the strength of bond Hg—C is stronger than that of Hg—S, which is good agreement with the experimental data. The calculations of the second order optical nonlinearity and electronic absorption spectra are also performed.