FeBr_3-catalyzed dibromination of alkenes and alkynes

The dibromination of alkenes and alkynes with bromosuccinimide and sodium bromide catalyzed by FeBr₃ under mild conditions has been developed.The trans-dibromo compounds were exclusively obtained with excellent yields.     

Synthesis and characterization of novel conjugated polymers based on 3-cyclobutene-1,2-dione moiety

Three novel conjugated polymers bearing 3,4-bis（4-hexylthiophen-2-yl）-3-cyclobutene-1,2-dione unit in their main chain have been synthesized successfully in good yields through Suzuki or Stille coupling reaction.Their molecular structures have been confirmed by FT-IR,¹H NMR and ¹³C NMR.All these copolymers exhibit broad and strong absorption bands in UV-vis region,and their optical band gaps are calculated to be 1.6-2.0 eV.suggesting that they have good coverage with the solar spectrum.These polymers have good thermostability and solubility in common organic solvents.Moreover,all these objective macromolecules possess high electron affinity of～3.8 eV determined from cyclic voltammetry measurement,implying that they are potential n-type polymeric photovoltaic materials.     

Determination of metoprolol in rabbit blood using capillary electrophoresis with laser-induced fluorescence detection

This work described a sensitive method for determination of metoprolol in rabbit plasma.The method involved purification by ultrafiltration,derivatization with fluorescein isothiocyanate,determination by capillary electrophoresis(CE) coupled with laser-induced fluorescence(LIF) detector.Other components in plasma including a variety of amino acids and proteins did not interfere with the determination of metoprolol in experimental condition.The assay had a wide range(2.0-500 ng/mL) of linearity and a detection limit of 0.8 ng/mL.The intra- and inter-day precisions were satisfactory with relative standard deviation(RSD) less than 10.0%and accuracy within 10.0%.This method was successfully applied to pharmacokinetic study of metoprolol in rabbit blood.     

Two new diterpenoids from Suregada glomerulata(Blume) Baill

Two new diterpenoids,3,4,18β-cyclopropa-ent-abieta-8(14),13(15)-dien-16,12-olide(1) and 3-oxojolkinolide B(2),were isolated from the roots of Suregada glomerulata(Blume) Baill.Their structures were determined by spectroscopic evidences. Compound 2 showed moderate cytotoxicity.     

Shrinking Projection Methods for a Family of Quasi-φ-Strict Asymptotically Pseudo-Contractions in Banach Spaces

The purpose of this article is to propose a shrinking projection method and prove a strong convergence theorem for a family of quasi-φ-strict asymptotically pseudo-contractions. Its results hold in reflexive, strictly convex, smooth Banach spaces with the property (K). The results of this paper improve and extend the results of Matsushita and Takahashi, Marino and Xu, Zhou and Gao and others.     

Effect of Al-doping on the structure and optical properties of electrospun zinc oxide nanofiber films

Electrospun ZnO precursor nanofibers of average diameters 122±64 nm, 117±44 nm and 110±39 nm were fabricated by controlling the Al concentration of a polymeric solution. The resulting nanofibers were characterized by the XRD, SEM, EDS, TEM, XPS and PL. The electrospun Al-doped ZnO nanofiber films were polycrystalline and composed of densely packed grains, with crystallite size ranging from 28.7 nm, 25.7 nm, 25.4 nm to 20.4 nm corresponding to the atomic concentration of aluminum from 0, 1.6, 2.5 to 5.8 at.%. The incorporation of aluminum resulted in a decrease trend in the grain size and lattice parameter of the ZnO nanofiber films. The room temperature PL spectra of all samples show three different emissions, including UV (ultraviolet) emission with an obvious blue shift, Vis (visible) emission and NIR (near infrared) emission, the intensity of which decreases monotonically as the doping concentration is increased except for the highest doping level. The impurity content correlates with changes in the PL spectra, and the appropriate Al doping can improve the optical properties of ZnO nanofibers. The small size effect and Al-doping or the impurity incorporation should be responsible for the blue shift observation in Al-doped ZnO nanofiber films.     

Selectivity control in alkylidene carbene-mediated C-H insertion and allene formation

Regioselectivity of alkylidene carbene-mediated C-H insertion was explored utilizing electronic, conformational, steric, and stereoelectronic effects. Relying on these factors, highly regio- and chemoselective carbene insertion reaction of C-H bonds in different environments could be obtained. The observed selectivity clearly indicates that an electronic effect plays a more important role than steric effect. In general, C-H bonds in conformationally rigid cyclic environments are less reactive than those in acyclic systems toward carbene insertion, and in this situation, a competing intermolecular reaction between alkylidene carbene and trimethylsilyldiazomethane led to the formation of allenylsilanes. The formation of allenylsilane becomes more favorable as the concentration of reaction becomes higher, as well as the C-H bonds undergoing insertion becomes electronically and conformationally deactivated.     

Photoreversible cellular imaging using photochrome-conjugated fullerene silica nanoparticles

Photochromic compound-conjugated fluorescent fullerene-silica nanoparticles prepared by the reverse-microemulsion method was utilized for photoswitchable cellular imaging by repeatable irradiation of ultraviolet and visible light.     

Wrapping the walls of n-TiO2 nanotubes with p-CuInS2 nanoparticles using pulsed-electrodeposition for improved heterojunction photoelectrodes

The CuInS(2) (CIS) nanoparticles were wrapped uniformly throughout the inner and outer walls of TNTs (TNT) by using square wave pulsed-electrodeposition. This structure enables the CuInS(2)-TiO(2) (CIS-TNT) to exhibit p-n junction diode behavior and enhanced photoelectrochemical properties.     

Kinetic resolution of aromatic β-amino acids by ω-transaminase

Racemic aromatic β-amino acids have been kinetically resolved into (R)-β-amino acids with high enantiomeric excess (>99%) by a novel ω-TA with ca. 50% conversion.