Coumarin-glycoside and Ferulate from Peucedanum decursivum

The root of Peucedanum decursivum (Miq.) Maxim (umbelliferae) is known as a famoustraditional Chinese medicine. In our Studies on the chemical constituents, compounds Iand 2 were isolated from the extract of the roots by combination of silica gel columnchromatography and preparative HPLC.Compound l, yellow powder, C,.H,,O., (HRFAB-MS (M-H) - m/z. cafed. 475. 1604.ohs. 475.1594), UV spectrum (X max 334 and 203 "m), IH and 13C NMR spectra werequite similar to those of furocoumarin gl…     

磷化氢与烯烃反应的原位NMR谱研究

本文应用加压原位(in-situ)核磁共振技术,在反应温度70～75℃,压力1.0～2.0MPa,氘代苯为溶剂,偶氮二异丁腈(AIBN)为引发剂的条件下探索了磷化氢与丙烯腈,4-乙烯基吡啶,烯丙基胺,丙烯酰胺,氨基吡啉和N-乙烯基咔唑的自由基加成反应,结果表明除氨基吡啉之外的其它五种含氮化合物均能与磷化氢发生反应,从而找到合成含氮有机膦的良好路线。     

A unique reaction pathway of fluorine-substituted ethyl groups on Cu(111): successive alpha,alpha-fluoride elimination

Fluorine-substituted ethyl groups on Cu(111) were generated by thermal scission of the C-I bond in the adsorbed C2F5I. Temperature-programmed reaction spectrometry observed a novel pathway resulting in the evolution of C4F6 above 400 K. Among the various isomers, this product was identified as hexafluro-2-butyne. Although abstraction of two fluorine atoms from the starting Cu-CF2CF3 was required, Cu-CCF3 (trifluoroethylidyne) was favored over Cu-CF=CF2 (trifluorovinyl) as the intermediate because this ethyl-ethylidyne-butyne pathway was suppressed on a Cu(100) surface devoid of the key threefold hollow binding sites for ethylidyne. Once formed, perfluoroethylidyne readily coupled to afford a tightly surface-bound hexafluoro-2-butyne up to 400 K. Therefore, the C-F bonds adjacent to the metal were found to be more susceptible to the bond activation, leading the chemisorbed perfluoroethyl to eliminate two F atoms successively from the alpha-carbon. This preference for alpha-elimination rather than beta-elimination (the most favorable route in hydrocarbons) may be quite general for metal surface-mediated reactions involving fluorinated alkyl groups.     

Rule for structures of open metal surfaces

We present a clear and simple rule for determining the relaxation sequences on open (stepped, vicinal, or high-Miller-index) metal surfaces. At the bulk-truncated configuration of a surface, a surface slab is defined where the coordination of atoms is reduced from the bulk. The rule predicts that the interlayer spacings within this slab contract, while the interlayer spacing between this slab and the substrate expands. By first-principles calculations, we show that this rule is obeyed on all open Cu surfaces with interlayer spacings down to about 0.5 A. We also illustrate a direct relation of the relaxation sequences to the charge redistribution on these surfaces, which is demonstrated to be driving the multilayer relaxations. The applicability of the rule can be extended to other fcc and bcc metals, including unreconstructed and missing-row surfaces.     

Multifunctional gold nanoparticle-peptide complexes for nuclear targeting

The ability of peptide-modified gold nanoparticles to target the nucleus of HepG2 cells was explored. Five peptide/nanoparticle complexes were investigated, particles modified with (1) the nuclear localization signal (NLS) from the SV 40 virus; (2) the adenovirus NLS; (3) the adenovirus receptor-mediated endocytosis (RME) peptide; (4) one long peptide containing the adenovirus RME and NLS; and (5) the adenovirus RME and NLS peptides attached to the nanoparticle as separate pieces. Gold nanoparticles were used because they are easy to identify using video-enhanced color differential interference contrast microscopy, and they are excellent scaffolds from which to build multifunctional nuclear targeting vectors. For example, particles modified solely with NLS peptides were not able to target the nucleus of HepG2 cells from outside the plasma membrane, because they either could not enter the cell or were trapped in endosomes. The combination of NLS/RME particles (4) and (5) did reach the nucleus; however, nuclear targeting was more efficient when the two signals were attached to nanoparticles as separate short pieces versus one long peptide. These studies highlight the challenges associated with nuclear targeting and the potential advantages of designing multifunctional nanostructured materials as tools for intracellular diagnostics and therapeutic delivery.     

Gain Measurement and Anomalous Decrease of Peak Gain at Long Wavelength for InAs/GaAs Quantum-Dot Lasers

Mode gain spectrum is measured by the Fourier series expansion method for InAs/GaAs quantum-dot （QD） lasers with seven stacks of QDs at different injection currents. Gain spectra with distinctive peaks are observed at the short and long wavelengths of about 1210nm and 1300nm. For a QD laser with the cavity length of 1060μm, the peak gain of the long wavelength first increases slowly or even decreases with the injection current as the peak gain of the short wavelength increases quickly, and finally increases quickly before approaching the saturated values as the injection current further increases.     

Mechanisms of the pancake vortex and vortex line movement in the high Tc superconductors Bi2Sr2CaCu2O8+δand La1.93Sr0.07CuO4+δ

In the strict sense, it is not very clear why with magnetic field increasing, the normal-superconductive (NS) transition becomes broad for Bi2Sr2CaCu2O8+δ(Bi2212) while the NS transitions are almost parallel for La1.93Sr0.07CuO4+δ(La214). In this paper, R-T relations are measured by the six-probe method. We propose a moving mechanism of the pancake vortex and vortex line for Bi2212. The theoretical curves fit the experiment data well.