Preparation of a Completely Oriented Molecular Sieve Membrane

Growth of oriented seed crystals on a substrate led to a completely oriented and continuous membrane of LTA-type zeolite. The seed crystals of cubic morphology were dip-coated onto a tilted substrate (see schematic diagram) with the zeolite channels normal to the surface. The substrate was hydrothermally treated in a reaction mixture containing the organic ligand 2,2-bis(hydroxymethyl)-2,2',2"-nitrilotriethanol, which lowers the degree of supersaturation of [Al(OH)(4)](-) ions and preferentially facilitates the intergrowth of the seed crystals.     

柱切换高效液相色谱法在生物样品中的应用

评述了柱切换高效液相色谱法（ＣＳＨＰＬＣ）在生物样品分析中的应用进展．分别对柱切换装置，血样、尿样提取液中被测组分浓度的测定，在线浓缩样品技术以及ＣＳＨＰＬＣ的联用进行了介绍．     

Capillary electrophoresis of high-molecular chitosan: the natural carbohydrate biopolymer

Due to its high resolving power and diverse application range, capillary electrophoresis (CE) has been successfully applied to the analysis of carbohydrates. In this paper, a method for the determination of high-molecular chitosan (Mr 200,000) using CE is presented. We studied the optimal condition of buffer pH and type, and column type for determination of chitosan. Optimal CE performance was found when employing 100 mM triethylamine (TEA)-phosphate buffer, pH 2.0 and untreated fused-silica capillary (50 microm x 27 cm) for the chitosan analysis. Under optimum conditions, excellent linear responses were obtained in the concentration range of 1.25-20 microM, with a linear correlation coefficient of 0.9983. The standard deviations of the migration time and peak area were found to be 2.5 and 6.4%, respectively. This method could be readily applied to chitosan determination in real biological samples and commercial products.     

A one step synthesis of 1,4-benzodiazepines: synthetic studies on neothramycin

A one step synthesis of 1,4-benzodiazepines from o-haloanilines and amino acids was achieved by use of palladium catalyzed carbonylation, by which application a synthesis of the model compounds(23a and 23b) of Neothramycin (A and B) was described. An efficient chemoselective reduction of the amide was provided.     

Zur Selektivität der Schwefelbestimmung in organischem Material

Zusammenfassung Der störende Einfluß von Chlor-, Brom-, Jod- und Stickstoffverbindungen bei der Verbrennung einer schwefelhaltigen Probe im leeren Quarzrohr und der darauf folgenden spektrophotometrischen Bestimmung von SO₂ als p-Rosanilinmethansulfonsäure wurde studiert. Chlor-, Brom- und Jodverbindungen beeinflussen nur die spektrophotometrische Reaktion. Die störende Wirkung der Stickstoffverbindungen hängt von deren Konstitution ab. Stickstoffverbindungen stören die photometrische Reaktion und verändern auch das Verhältnis zwischen SO₂ und SO₃ in der Gasphase.

---

Selectivity of the determination of sulfur in organic compounds

Summary The disturbing effect of chloro-, bromo-, iodo-, and nitrogen derivatives during the combustion of a sulfur-bearing sample in an empty quartz tube and in the subsequent spectrophotometric determination of SO₂ as p-rosaniline methane sulfonic acid was studied. Chloro-, bromo-, and iodo compounds influence only the spectrophotometric reaction. The interfering action of the nitrogenous compounds depends on their constitution. The nitrogen compounds affect the photometric reaction and also alter the ratio between the SO₂ and SO₃ in the gas phase.

     

Kinetics and Mechanism of the Reduction of Enneamolybdomanganate(IV) by Citric Acid

The kinetics and mechanism of reduction of enneamolybdomanganate(IV) by citric acid in acidic solution was studied by spectrophotometry, and showed that the reaction, with respect to enneamolybdomanganate(IV) and to citric acid, is pseudo-second-order and first-order, respectively. The values of 1/k_obs increase with the values of [H⁺] and reaction rates increase with temperature. The activation parameters of the rate-determining steps were evaluated. A mechanism related to this reaction is proposed.     

Modeling the action of an antitumor drug: a density functional theory study of the mechanism of tirapazamine

Density functional theory methods are employed to investigate experimentally proposed mechanisms by which the antitumor drug tirapazamine may react with a DNA sugar-C(1)' radical to give the sugar derivative deoxyribonolactone, with concomitant DNA strand breakage. For the previously proposed minor pathway, ionization of the sugar-C(1)' radical by tirapazamine, the calculated ionization energy, and the electron affinity of the models of the sugar-C(1)' radical of DNA and tirapazamine suggest that tirapazamine must be protonated to be able to oxidize the sugar-C(1)' radical. The preferred mechanism for reaction of tirapazamine with a sugar-C(1)' radical, in agreement with experimental observations, is found to proceed by direct attack of an N-oxide oxygen of tirapazamine at the sugar-C(1)' position, followed by homolytic cleavage of the N-O bond of the drug moiety. Possible alternative mechanisms are also investigated.     

Exciton transfer in the two-dimensional antiferromagnet (C2H5NH3)2MnCl4

Exciton transfers in the two-dimensional and spin-canted antiferromagnet (C₂H₅NH₃)₂MnCl₄ were studied by investigating the absorption spectra ⁶A_1g → ⁴T_2g(⁴D) of Mn²⁺. A magnon side band (exciton–magnon simultaneous excitation) which has an anomalous shape with the cutoffs at the low-energy as well as the high-energy sides was observed. This anomalous shape could be reproduced in calculation as magnon side band, considering both the intersublattice and intrasublattice exciton transfers. From the analysis of this band shape, the magnitudes of the intersublattice and intrasublattice exciton transfers are estimated to be 10.2 and 6.8 cm^?1, respectively. In the case of simple antiferromagnets without spin canting, the intersublattice exciton transfer process is forbidden because of the spin angular momentum. However, in the case of (C₂H₅NH₃)₂MnCl₄, the prohibition of the intersublattice exciton transfer is removed by the canted-spin arrangement.