微生物法分析天然抗氧化剂性能

建立了微生物抑菌活性纸片试验法，对葛根黄酮、诃子提取物、丹皮酚、竹叶黄酮等4种天然抗氧化剂的抗氧化性能进行了研究。竹叶黄酮、诃子、葛根具有较强的抗单线态氧能力，而丹皮酚抗单线态氧的能力较差。在不同的氧化还原微环境下，天然抗氧化剂可能表现出抗氧化能力，亦可能表现出促氧化能力，二者有着不同的反应机理。微生物抑菌活性纸片法可作为研究较复杂生物环境中抗氧化剂性能的一种简便方法。     

Fluorimetric determination of boron with resacetophenone as a reagent

Summary A method has been developed for the fluorimetric determination of boric acid, which gives a blue fluorescence with resacetophenone in sulphuric acid or phosphoric acid medium. The method has the advantage that the reaction does not require much time, because the fluorescence intensity reaches its maximum immediately after mixing the reagents and does not also decrease with time. The intensity of fluorescence can be measured with a fluorimeter and the amount of boric acid determined from a calibration curve.     

气相色谱法测定三聚氰氯的研究

气相色谱法测定三聚氰氯的研究李秀梅赵树岚＊田锦霞＊孙维星（东北师范大学化学系长春１３００２４）关键词气相色谱法三聚氰氯三聚氰氯（ＣＮＣｌ）３是活性染料的重要中间体及合成树脂、橡胶、塑料等的防老剂，也常用于除草剂、增白剂、药物、炸药等的生产中。传统的分...     

Temperature-programmed desorption and adsorption of hydrogen on Mo2N

Hydrogen adsorption-desorption over Mo₂N has been studied using a temperature-programmed technique. It is revealed that hydrogen on Mo₂N exhibits very high mobility leading to migration of the surface hydrogen into the sublayer and bulk of the sample or the reverse. The surface hydrogen species are preferentially formed when adsorption is carried out below 573 K. On increasing the adsorption temperature to above 573 K, the quantity of hydrogen species located in the sublayer or/and bulk of the Mo₂N sample increases significantly.     

High pressure Raman studies of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and CuTCNQ

The high-pressure Raman studies of 7,7,8,8-tetracyanoquinodimethane (TCNQ) single crystals and polycrystalline CuTCNQ are presented in this paper. TCNQ shows a phase transition at 22 kbar, a pressure higher than reported earlier. CuTCNQ undergoes a first order phase transition at 30 kbar, which is characterized by the abrupt disappearance of all the Raman bands.     

Temperature-induced changes in the composition of floatglass surfaces

Floatglass is an important kind of commercial glass, comprising the main body of modern flat glass used in buildings and vehicles. The stoichiometry of the surface layer differs from that of the bulk and will usually change due to subsequent high-temperature process steps or attack by water or humidity. Glass samples have been investigated by means of ion beam analysis. Using resonant nuclear reaction analysis (¹⁵N technique), hydrogen concentration profiles have been determined. Profiles of the heavier glass constituents, especially sodium and tin, have been obtained by RBS. Changes in the composition of the floatglass surfaces caused by subsequent temperature treatment (up to 700^°C) and by controlled hydration treatment are reported. Possible mechanisms of hydrogen uptake and release are discussed.     

Detection of DNA fragments separated by capillary electrophoresis based on their native fluorescence inside a sheath flow

A scheme for the separation and detection of native DNA fragments in capillary electrophoresis is presented. A UV laser at 275 nm excites the intrinsic fluorescence of the fragments, which is greatly enhanced at pH 2.8. To provide a compatible system, methylcellulose-based size separation is performed at the identical pH. A sheath-flow arrangement isolates the detection region from the linear polymer for a reduced background level. The performance is an order-of-magnitude enhancement in detectability over absorption detection. We also uncovered a selective degradation/ligation process at these pH conditions that may be useful as additional selectivity for DNA characterization.     

Hydroformylation and hydrocarbethoxylation of 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine

The unsaturated compounds 1,2-dicarbethoxy-1,2,3,6-tetrahydropyridazine 1 and 1,2-dicarbethoxy-1,2,3,4-tetrahydropyridazine 2 have been hydroformylated and hydrocarbethoxylated in the presence of some well known cobalt, rhodium, palladium and platinum catalysts. The hydroformylation reaction can be tuned by a suitable choice of the catalyst precursor and reaction conditions, thus allowing the synthesis with high selectivity of one of the two possible isomeric aldehydes. The carbonylation reaction is less synthetically useful, since it shows low activity and unsatisfactory chemo- and regio-selectivity. However, the ester 1,2,4-tricarbethoxyhexahydropyridazine 10 can be prepared in good yield from olefin 1 by using the complex [PdCl₂(PPh₃)₂] as the catalyst precursor.     

Enthalpimetric and thermometric determination of some nitrogen containing bases and some physiologically active alkaloids

Summary The enthalpimetric determination of a series of bases by using the reaction of the bases and sodium tetraphenylboron is described. The accuracy of the method is analytically acceptable, over the range 3×10^–5 moles to 7.5×10^–4 moles. The upper limit is determined by the bulk of the precipitate.Dosage forms of some physiologically active alkaloids contain more than the upper limit of analyte. Yet, preliminary investigations using silicotungstic acid indicate that this is suitable for thermometric titrations.

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Enthalpimetrische und thermometrische Bestimmung stickstoffhaltiger Basen und physiologisch aktiver Alkaloide

Zusammenfassung Die enthalpimetrische Bestimmung einiger N-haltiger Basen erfolgte aufgrund der Reaktion mit Natriumtetraphenyloborat. Die Genauigkeit ist im Bereich von 3 · 10^–5-7,5 · 10^–4 Mol befriedigend. Eine obere Grenze der Anwendbarkeit ergibt sich aus der Menge des anfallenden Niederschlags. Diese wird bei der Bestimmung von Formulierungen einiger physiologisch aktiver Alkaloide überschritten. Jedoch ist in diesem Fall eine thermometrische Titration mit Hilfe von Silicowolframsäure möglich.

Lecture presented at Euroanalysis I Conference, 28. 8.–1. 9. 1972 in Heidelberg, Germany.     

Redox behavior of V/MgO catalyst in H2S wet oxidation at room temperature

The room temperature wet catalytic oxidation was conducted in a batch reactor with V/MgO catalyst. The XRD study of the catalyst used indicated that V/MgO could not only oxidize H2S to sulfur selectively, but also prevent the sulfidation of metal oxide effectively at the room temperature. The XPS study indicated that the H2S oxidation with V/MgO could proceed by a redox mechanism (V⁵⁺↔ V⁴⁺) and that V³⁺ formation (V⁴⁺→ V³⁺), was responsible for the deactivation of V/MgO. This revised version was published online in June 2006 with corrections to the Cover Date.