Total photoionization cross-sections of Ar and Xe in the energy range of 2.1–6.0 keV

Total photoionization cross-sections of Ar and Xe have been accurately measured in the photon energy region of 2.1–6.0 keV, using a four-electrode ion chamber with monochromatized synchrotron radiation. Experimental data are presented in both graphical and tabular forms and compared with previous data reported in the literatures.     

液晶聚氨酯的研究进展

概括了液晶聚氨酯的研究及发展状况，总结了液晶聚氨酯的合成、性能和影响因素，并简单介绍了作者的工作内容，提出了液晶聚氨酯的发展趋势。     

Exchange coupling and remanence enhancement in nanocomposite Nd–Fe–B/FeCo multilayer films

Nd–Fe–B-type hard phase single layer films and nanocomposite Nd₂₈Fe₆₆B₆/Fe₅₀Co₅₀ multilayer films with Mo underlayers and overlayers have been fabricated on Si substrates by rf sputtering. The hysteresis loops of all films indicated simple single loops for fixed Nd–Fe–B layer thickness (10 nm) and different FeCo layer thickness (d_FeCo=1–50 nm). The remanence of these films is found to increase with increasing d_FeCo and the coercivity decrease with increasing d_FeCo. It is shown that high remanence is achieved in the nanocomposite multilayer films consisting of the hard magnetic Nd–Fe–B-type phase and soft magnetic phase FeCo with 20 nm?d_FeCo?3 nm. The sample of maximum energy product is 27 MG Oe for d_FeCo=5 nm at room temperature. The enhancement of the remanence and energy products in nanocomposite multilayer films is attributed to the exchange coupling between the magnetically soft and hard phases.     

A simple route for the preparation of Eu, N-codoped TiO2 nanoparticles with enhanced visible light-induced photocatalytic activity

A simple route has been developed for the synthesis of europium, nitrogen-codoped titania photocatalysts under mild conditions (i.e., low temperature, < or = 348 K, and ambient pressure). The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectra (DRS) analyses. The results showed that the codoped photocatalyst with a spheroidal shape exhibited a smaller size than the undoped titania. The transformation from anatase to rutile was suppressed by doping with Eu and N atoms. Furthermore, the absorbance spectra of Eu, N-codoped TiO(2) exhibited a significant red shift to the visible region. The photocatalytic activity of Eu, N-codoped TiO(2) was evaluated by photodegradation of the dye reactive brilliant red X-3B under visible light. This codoped sample exhibited enhanced photocatalytic activity compared to N-doped TiO(2), pure TiO(2), and P25.     

Two syntheses of (-)-kainic acid via highly stereoselective zinc-ene cyclizations

Two concise, high-yielding syntheses of enantioenriched (-)-kainic acid are presented. Both routes feature a Pd-catalyzed Zn-ene cyclization that proceeds with complete diastereoselectivity. The key step can be carried out on a multigram scale, and the overall yields are among the highest to date for this marine alkaloid.     

Pseudoclimb and dislocation dynamics in superplastic nanotubes

Plastic relaxation of carbon nanotubes under tension and at high temperature is described in terms of dislocation theory and with atomistic computer simulations. It is shown how the glide of pentagon-heptagon defects and a particular type of their pseudoclimb, with the atoms directly breaking out of the lattice, work concurrently to maintain the tube perfection. Derived force diagram quantifies the balance between these mechanisms, while simulations show both helical and longitudinal movement of the kinks, in agreement with the forces and with experimental observations.     

硫代磷(膦)酰基脲类衍生物的合成及其生物活性

通过O,O-二乙基硫代磷酰基异氰酸酯或O-乙基-苯基硫代膦酰基异氰酸酯与不同胺的加成反应,合成了一系列新型硫代磷(膦)酰基脲类化合物,其结构经元素分析、¹HNMR及MS确证。初步的生物活性测定表明,这类化合物具有一定的除草、抗肿瘤及抑制几丁质形成活性。     

Estimation of the desorption energy of dichloromethane and water in MIL-53 by DSC and ab-initio calculations

Desorption energies of dichloromethane(CH_2Cl_2) and water(H_2O) in a metal-organic framework, MIL-53(Al), were investigated by the combination of experimental(differential scanning calorimeter, DSC) and computational(ab-initio calculations) methods. The differences of desorption energy and natural log of the frequency factor of CH_2Cl_2 and H_2O in MIL-53(Al) were analyzed by a thermo active process using DSC measurements. The interaction energy of guest molecules with MIL-53(Al), which corresponds to the desorption in the thermal active process, was explored using ab-initio calculation. As a result of the difference in the interaction energies of H_2O and CH_2Cl_2 in MIL-53(Al), the site near the μ_2-OH groups has two potential wells. Both experimentally and computationally, MIL-53 presents the preferential adsorption of CH_2Cl_2 than H_2O.     

Synthesis of Sub-100 nm and Narrow Particle Size Distribution Cationic Latex by One-Step Emulsion Polymerization

A novel approach to synthesize narrow particle size distribution cationic latex particles based on styrene and butyl acrylate was proposed. The effect of monomer/water ratios, surfactant (cetyltrimethylammonium chloride) concentrations, and monomer compositions on the evolution of particle size, distribution, number, and morphology as a function of monomer conversion was concerned in order to confirm the optimum polymerization condition. As expected, the particle size of the ultima latex increased with monomer/water ratios and styrene contents decreased with increasing surfactant concentrations. Continuous nucleation phenomena occurred when monomer/water ratio was lesser than 30/70, resulting in a gradual increase in the number of particles in the whole polymerization process. Combined with the previous work (Colloid and Polymer Science, 2014, 292: 519–525), it was concluded that particle coagulation easily took place in cationic emulsion polymerization of styrene. Thus, the narrow particle size distribution cationic latexes with particle scale between 50 nm and 80 nm, 30 wt% solid content could be prepared in a short reaction time.