木根黄芩中-新黄酮的光谱特征

从木根黄芩(Scutellaria planipes Nakai et Kitag.)中分离得到一新黄酮类化合物. 该化合物被鉴定为5,7,3′,6′-tetrahydroxy-6,8,2′-trimethoxyflavone. 它有很强的抑制5-酯氧合酶活性. 由于该化合物的A环全部被取代，因此，应用一般的光谱技术很难准确归属各碳的化学位移. 我们应用¹³C-¹³C相关谱和酰化位移方法，明确归属了各碳的信号，并订正了文献中对部分信号的错误归属.     

Mizoroki-Heck type arylation of alkenes using aroyl chlorides under base-free conditions

The Mizoroki-Heck type arylation of alkenes with aroyl chlorides accompanied by decarbonylation efficiently proceeds in the presence of a palladium catalyst system, PdCl₂(PhCN)₂/(PhCH₂)Bu₃NCl, even without adding any base. The products can be isolated by a very simple procedure.     

Depinning line of granular YBa2Cu3O7?δ measured with vibrating-reed method

The depinning temperatures in YBa₂Cu₃O_7−δ ceramics and grains have been studied at magnetic field up to 4 T and various amplitudes of vibration. For ceramics sample, large amplitude dependence of depinning temperature T_D was observed, which indicate the decoupling of grains. In the case of a suspension sample (grain), T_D was much lower than that of ceramics.     

Alpha-activation analysis of boron on Si surface and in Si and SiO2 films

Brazil has become the largest producer of biomass ethanol derived from sugar cane. The industrial production is based on the fermentation of sugar cane juice by yeast, inside of large volume vats, in a fed-batch process that recycles yeast cells. To study the dynamics of chemical elements in each operating cycle, five stages of the fementation process were considered: must, yeast suspension, wine, non-yeast wine and yeast cream. For this, a mass balance of the terrigenous elements, Ce, Co, Cs, Eu, Fe, Hf, La, Na, Sc, Sm, and Th, and the sugar cane plant elements, Br, K, Rb, and Zn, were established in fementation vats of an industrial scale unit, with sampling undertaken during different climatic conditions (dry and rainy periods). A similar distribution of the sugar cane characteristics elements was found for the stages analysed, while for the terrigenous elements a trend of accumulation in the yeast cream was observed. Preferential absorption of Br, K, Rb, and Zn by yeast cells was indicated by the smaller concentrations observed in yeast suspension than in yeast cream.     

Nylon 6 structure in solid state as studied by high-resolution 13C-NMR spectroscopy

High resolution ¹³C-NMR spectra of nylon 6 samples crystallized under various conditions and of a drawn sample were measured at room temperature by the cross polarization/magic angle spinning (CP/MAS) and pulse saturation transfer/magic angle spinning techniques. Additionally, ¹³C-NMR spectra of the drawn sample were measured at temperatures from 20 to 100°C by the CP/MAS technique and at 20 and 100°C by the low-power decoupling/magic angle spinning technique. The nylon 6 structure in the solid-state is discussed on the basis of these results. The solid-state ¹³C chemical shift data are used for reference in a study of conformation in solution.     

Two-Dimensionally Self-Holding Deflection Mirror Using Surface Acoustic Wave Motor

We have developed a two-dimensionally deflecting mirror actuating system with a deflection angle of 20°, which takes full advantage of the characteristics of a two-dimensional surface acoustic wave (SAW) motor. A magnetic slider moves with frictional drive by the Rayleigh mode of the SAW and deflects the mirror by the force of magnetic attraction. For the actuation of a 20° deflection angle, only a 10 ms duration of driving voltage is required owing to the high-speed characteristic of the motor, followed by an additional 10 ms for damping of the mirror structure produced in order to complete holding of the angle. No power supply is necessary to hold the angle. Furthermore, the resolution of the angle is 0.0015° because of the high-resolution capability of the motor. The mirror deflection system showed a 10⁴ dynamic range of angle positioning ability.     

Addition of S-benzoyl phenylselenosulfide to olefins: selenothiocarboxylation

Heating of S-benzoyl phenylselenosulfide and olefins with AIBN afforded selenothiocarboxylated products generated by a free radical process with high regiospecificity but lack of stereoselectivity.