COMPLETE SUBMANIFOLDS IN E~(n+p)WITH PARALLEL MEAN CURVATURE

This paper gives a pinching condition by which complete submanifolds in aEuclidean space can be classified completely.In particular,a characterization for acomplete submanifold in a Euclidean space to be totally umbilical is shown.     

Optical spectra of CsI,CsBr, ZuGeP2, and SbSI

We report here the study of the normal reflectivity spectra R and the corresponding derivative spectra (1/R) dR/dE of SbSI between 2 and 6 eV. The spectra show very strong anisotropy. We have also tried to use the change of the wavelength modulation spectrum to monitor the change in the band structure of SbSI due to the phase transition at 292 °C (D_2h¹⁶→C_2v⁹). Careful examination of the spectra at various temperatures around T_c shows no observable change. We report also the wavelength-modulated reflectivity spectra of the chalcopyrite crystal ZnGeP₂ at 5 K between 2 and 6 eV, for E∥ C and E⊥ C. The experimental results are compared with the theoretical band structure calculation by de Alvarez and Cohen. We also present measurements on CsBr, CsI in the vacuum uv (between 5 and 8 eV) at 1.8K, showing noticeable difference with previous reflectivity measurements at 77 K.     

In vacuo photocurrent measurements of plasma polymerized styrene films

Photoconductivity measurements were carried out on plasma polymerized styrene (PPS) in vacuo, in air, and in subsequently re-evacuated conditions. Samples with two gold electrodes (Au-PPS-Au) and gold-aluminum electrodes (Au-PPS-Al) were used. Positive short circuit photocurrents in the direction of illumination were observed in both types of specimens. In the case of Au-PPS-Au, photocurrent threshold was about 1.6 eV in vacuo for the virgin film, which is attributed to the energy of hole generation in bulk. Residual free radicals were assumed to be the acceptors in this mechanism. In the case of Au-PPS-Al, electron injection from aluminum was thought to be a more likely mechanism, with an estimated barrier height of approximately 2.6 eV.     

Aromatic ring synthesis by N-aminopyrrole diels-alder reaction. Total synthesis of juncusol

A total synthesis of the cytotoxic phytoalexin juncusol ($\text{1}$) is described.     

一种具有Goldbach性质的可换环上的二次同余

[1]—[3] 用模型论与数论方法讨论了整数环的某些扩环的数论性质,说明一些数论命题间的和谐性与相对独立性。[4]进一步研究了一种具有Golabach性质的可换环R,分析了R与整数环I的异同。[4]证明了R上有与I极不相同的二次同余性质。如R上存在8k±3形素元以2为平方剩余,也存在8k±1形素元不以2为平方剩余,等等。一个自然的问题是对任意非平方数a∈I,任意b,c∈I,若(b,c)=1,是否总存在bk+c形素元以a为     

Thermoelastizit?t und Kettenkonformation in alternierenden Conolvmeren von Butadien

Ohne Zusammenfassung     

D-Proline capped gold nanoclusters for turn-on detection of serum Raltitrexed

Using D-proline (D-Pro) as the reducing agent and capper, D-Pro@AuNCs was rapidly constructed. Its fluorescence could be quenched by AuNPs. Due to the electrostatic interaction between anticancer drug Raltitrexed (RTX) and AuNPs induced fluorescence "turn-on" principle, the resultant fluorescent probe exhibited good selectivity and sensitivity for detecting RTX in rat serums.     

B0 ? ffB^0 \to \phi\phi decay in perturbative QCD approach

The rare decay can occur only via the penguin annihilation topology in the standard model. We calculate this channel in the perturbative QCD approach. The predicted branching ratio is very small: around 10^-8. We also give the polarization fractions, which show that the transverse polarization contribution is comparable to the longitudinal one, due to a big transverse contribution from factorizable diagrams. The small branching ratio in SM makes it sensitive to any new physics contributions.Received: 29 January 2005, Published online: 28 April 2005     

Growth of Cu2S ultrathin nanowires in a binary surfactant solvent

We demonstrate a facile solution-phase method for the synthesis of single-crystal, high aspect ratio, and ultrathin nanowires of hexagonal-phase Cu2S by thermal decomposition of CuS2CNEt2 in a mixed surfactant solvent of dodecanethiol and oleic acid at 160 degrees C. Cu2S nanowires can be controllably synthesized with a diameter as thin as 1.7 nm and length up to tens of micrometers; they are usually aligned in the form of bundles with a thickness of hundreds of nanometers. Based on the experimental results, the formation mechanism of the ultrathin nanowires has been properly proposed. Some key synthetic parameters, which have a significant effect on the sizes and shapes of the products, have also been investigated in detail. UV-vis spectroscopy measurement reveals that the resultant ultrathin nanowires show a strong quantum size effect.