Single-crystal-to-single-crystal transformation of diolefin derivatives in nanocrystals

Topochemical [2 + 2] cycloaddition polymerization of methyl p-phenylenediacrylate and 2,5-distyrylpyridine in nanocrystals, prepared by the reprecipitation method, were investigated in comparison with those in bulk crystals. The bulk single crystals, larger than 1 mum in size, broke into microcrystals with variety of size and shape in the course of polymerization. Interestingly, however, these nanocrystals show single-crystal-to-single-crystal transformation.     

Adsorbate-induced pinning of a charge-density wave in a quasi-1D metallic chains: Na on the In/Si(111)-(4x1) surface

We find that foreign adsorbates acting as local impurities can induce a metal-insulator transition by pinning a charge-density wave (CDW) on the quasi-1D metallic In/Si(111)-(4x1) chain system. Our scanning tunneling microscopy image clearly reveals the presence of a new local 4x2 structure nucleated by Na adatoms at room temperature, which turns out to be insulating with a doubled periodicity along the chains. We directly determine a CDW gap energy Delta = 105+/-8 meV by identifying a characteristic loss peak in our high-resolution electron-energy-loss spectra. We thus report the first observation of a local impurity-derived Peierls-like reconstruction of a quasi-1D system.     

宽角度X射线超反射镜的设计

阐述了一种新的X射线超反射镜的设计方法.该方法将Frensnel反射系数公式和单纯形调优法相结合,可以设计出满足不同要求的X射线超反射镜.依据周期多层膜确定膜层数,给出了一种确定超反射镜膜层数的方法.设计了在铜(Cu)的Kα线下,具有不同掠入射角宽度的多种钨(W)/碳(C)超反射镜.设计中考虑了多层膜结构的界面粗糙度和相互扩散对多层膜反射性能的影响,并做了模拟计算.实验结果表明:用这种方法设计X射线超反射镜优于现有的其他方法.     

Die Wechselwirkung zwischen synthetischen Polymeren und Netzmitteln

Zusammenfassung Die Polyelektrolyten (Polyakryls?ure, Carboxymethylzellulose, K-Polyvinylsulfat) verhalten sich bei Zusatz gleichnamig geladener Netzmittel anders als bei Zusatz des einfachen Salzes, was durch die Analogie der Wechselwirkung zwischen Netzmittel und nichtionischen Polymeren wie Polyvinylalkohol zu erkl?ren ist.     

Determination of beta-carbolines in foodstuffs by high-performance liquid chromatography and high-performance liquid chromatography-mass spectrometry

A high-performance liquid chromatographic method combined with fluorimetric detection is described for the determination of beta-carboline (norharman) and 1-methyl-beta-carboline (harman). The analysis of foodstuffs for the identification of beta-carbolines is facilitated by clean-up samples using Bond Elut PRS cartridges. Recoveries were excellent. Further, a high-performance liquid chromatographic-mass spectrometric method was also developed for their identification. The concentration of beta-carboline among the foodstuffs and alcoholic beverages varied greatly. Also, norharman and harman were observed in uncooked foodstuffs, whereas acetaldehyde was found in most fermented food. The toxicological implication of beta-carbolines in foodstuffs is discussed.     

On interior regularity criteria for weak solutions of the navier-stokes equations

We are concerned with the behavior of weak solutions of the Navier-Stokes equations near possible singularities. We shall show that if a weak solution is in some Lebesgue space or small in some Lorentz space locally, it does not blowup there. Our basic idea is to estimate integral formulas for vorticity which satisfies parabolic equations.     

The intermediate weak boson and weak interactions at high energy

The high-energy pire-leptonic weak interaction is investigated based on the assumption of the existence of a charged vector boson which mediates the weak processes. With the aid of the fixed-t dispersion relation the following relation is obtained: The weak boson mass m_W should satisfy $\text{m}{}_{\mathrm{<mtext>W</mtext>}}\text{? G}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$, with G the Fermi coupling constant, if the asymptotic value of the cross section becomes of the order of the strong interaction in the energy region observable in cosmic rays, etc.The scattering processes $\text{e}\text{+ν→}\text{e}\text{+ν}\text{and}\text{e}\text{+}\text{ν}\text{→}\text{e}\text{+}\text{ν}$ are examined by the aid of the N/D method. For a large vector-boson mass $\text{m}{}_{\mathrm{<mtext>W</mtext>}}\text{?100}\text{GeV}$, an S-wave resonance should exist for the process e+ν→e+ν while for $\text{e}\text{+}\text{ν}\text{→}\text{e}\text{+}\text{ν}$ there should exist a P-wave resonance which corresponds to the intermediate weak boson. The neutral current is then estimated. It is shown that the neutral current produced as a higher-order effect is not inconsistent with the present experiments on the pure-leptonic weak interaction if m_W?1 TeV.