间位苯基桥联的锰（Ⅲ）双咔咯的合成、表征及催化氧化性质

通过间苯二甲醛与5-氟苯基二吡咯甲烷反应合成了一种新的间位苯基桥联的双咔咯1,并利用锰盐与自由咔咯反应制备了其锰的金属配合物2。采用紫外、质谱、核磁、XPS等手段对化合物进行了表征。以苯乙烯为底物考察了锰双咔咯2的催化氧化性质,探讨了时间、溶剂、氧源、轴向配体对催化反应的影响。结果表明以亚碘酰苯和间氯过氧苯甲酸为氧源时催化的主要产物为环氧苯乙烷,而以双氧水和叔丁基过氧化氢为氧源时则主要产物为苯甲醛;在极性溶剂中的催化氧化产率较高。轴向配体对催化氧化有促进作用,不同轴向配体对催化反应产率提高的顺序是：1-甲基咪唑 >吡啶 >咪唑。     

间位苯基桥联的锰(Ⅲ)双咔咯的合成、表征及催化氧化性质(英文)

通过间苯二甲醛与5-氟苯基二吡咯甲烷反应合成了一种新的间位苯基桥联的双咔咯1,并利用锰盐与自由咔咯反应制备了其锰的金属配合物2。采用紫外、质谱、核磁、XPS等手段对化合物进行了表征。以苯乙烯为底物考察了锰双咔咯2的催化氧化性质,探讨了时间、溶剂、氧源、轴向配体对催化反应的影响。结果表明以亚碘酰苯和间氯过氧苯甲酸为氧源时催化的主要产物为环氧苯乙烷,而以双氧水和叔丁基过氧化氢为氧源时则主要产物为苯甲醛;在极性溶剂中的催化氧化产率较高。轴向配体对催化氧化有促进作用,不同轴向配体对催化反应产率提高的顺序是:1-甲基咪唑吡啶咪唑。     

The effect of phosphorylation of the histidyl residue in the tetrapeptide Gly-Gly-His-Ala. Changes of chemical shift and pK values in 1H- and 31P-NMR spectra

Phosphorylation of the tetrapeptide Gly-Gly-His-Ala by phosphoamidate provides a model peptide for proteins which, in the course of their reaction, bind a phosphoryl group to an imidazole ring. ³¹P- and ¹H-NMR data, including chemical shift and pK values, for this peptide and its three phospho-derivatives are presented. These data show that it is possible, by NMR studies, to decide whether or not a peptide or a protein is phosphorylated at the N-1 or at the N-3 position of an imidazole ring, and how this information can be achieved.     

On the insulating properties of the interfacial layer between ion bombarded-amorphous and crystalline silicon

After bombarding silicon single crystals with heavy neon ion doses, the resulting amorphous surface layer has been found to be electrically insulated from the underlying bulk material. Current-voltage characteristics indicate the formation of a junction between the crystalline and the damaged layer. As a consequence, the electrical properties of the amorphous layer can be measured at low temperatures up to about 230 K and considerably beyond room temperature, if thick crystal wafers and silicon-on-sapphire (SOS) samples, respectively, are used.     

Improved synthesis of sterically encumbered multibrominated corroles

Efficient and easily reproducible synthesis of sterically hindered multibrominated corroles is achieved via dipyrromethane-aldehyde condensation reaction in good yields.Boron trifluoride dietherate（BF_3-Et_2O） is found to be the effective catalyst for cyclization reaction,giving corrole as the major product.     

A simple universal fit formula to experimental nuclear stopping power data

Recent experimental data was fitted by using a simple universal relation between nuclear stopping power and particle energy in the range of about 10^?4≦?≦10². Comparison with previous and recent theoretical predictions is made.     

A chemical-bond approach to doping,compensation and photo-induced degradation in amorphous silicon

We propose that during deposition of a-Si:H films a chemical equilibrium is established that relates the density of dangling-bond defects near mid-gap to the densities of electrons and holes in the conduction and valence band states. We develop the appropriate chemical reaction formalism and show that our model allows doping, compensation and photo-induced degradation to be treated within a single and unifying approach.     

Current-voltage characteristics of a gas field ion source

Current-voltage characteristics of a gas field ion source (GFIS) have been measured for hydrogen and all rare gases. The parameter set included tip temperature, tip radius and gas temperature and pressure. This investigation has been made to get a complete overview of the field ion currents (FIC) and to estimate the maximum currents in a GFIS, which have been found to a few 100 nA. This estimate allows also a feasibility study of a GFIS, modified by a supertip, a small protuberance on the emitter surface.     

NMR spectroscopic study of noble gas binding into the engineered cavity of HPr(I14A) from Staphylococcus carnosus

Xenon binding into preexisting cavities in proteins is a well-known phenomenon. Here we investigate the interaction of helium, neon, and argon with hydrophobic cavities in proteins by NMR spectroscopy. 1H and 15N chemical shifts of the I14A mutant of the histidine-containing phosphocarrier protein (HPr(I14A)) from Staphylococcus carnosus are analyzed by chemical shift mapping. Total noble gas induced chemical shifts, Delta, are calculated and compared with the corresponding values obtained using xenon as a probe atom. This comparison reveals that the same cavity is detected with both argon and xenon. Measurements using the smaller noble gases helium and neon as probe atoms do not result in comparable effects. The dependence of amide proton and nitrogen chemical shifts on the argon concentration is investigated in the range from 10 mM up to 158 mM. The average dissociation constant for argon binding into the engineered cavity is determined to be about 90 mM.     

On the variation of hopping transport in amorphous silicon with preparation conditions

Thedc conductivity of amorphous silicon prepared by two successive ion bombardments at different temperatures has been measured as a function of temperature. The results may be expressed in terms of a generalized hopping formula =₀ exp [–(T ₀/T) ⁿ where the parameter set {n,T ₀, ₀} varies with the irradiation conditions. In particular, the hopping exponent has been found to assume the limiting values ofn1/4 at irradiation temperatures ofT _i100 K and ofn1/2 atT _i500 K, whereas intermediate values ofn have been observed for temperatures inbetween. It is concluded that thermally activated redistribution processes of radiation defects control the final state of disorder in the irradiated samples, which in turn determines the particular hopping characteristics. Within the framework of existing theories the two limiting cases can be explained to be due to a disordered solid of homogeneous and granular structure, respectively.