Suzuki–Miyaura cross-coupling reaction of 1,2-oxaborol-2(5H)-ols with carboxylic anhydrides: a new method to furans

An efficient one-step method has been developed to construct furans via a Suzuki–Miyaura cross-coupling reaction of 1,2-oxaborol-2(5H)-ols with carboxylic anhydrides. In the presence of Pd(OAc)₂/PCy₃, the multi-substituted alkenylboron compounds could couple with anhydrides to obtain furans in moderate-to-good yields. The addition of bases promoted the coupling reaction, and the plausible reaction mechanism was proposed.     

Insulated π-conjugated metallopolymers

Recently, there has been a progressive development of insulated π-conjugated metallopolymers with accumulated features of π-conjugated bridging units, transition metal complexes, and encapsulating moieties, as higher-order functionalized materials. A number of insulated conjugated metallopolymers have been successfully synthesized and their fascinating properties have been reported. In addition to the conventional features derived from π-conjugation and transition metals, their insulated structures can compensate for solubility, a disadvantage in conventional metallopolymers, and enhance their functionalities, such as sensing, luminescence, and conduction. In this review, we summarize the synthetic methodologies, structural characteristics, and functionalities of one-dimensional insulated π-conjugated metallopolymers, while focusing on the effect of transition metals and insulation on their properties.     

Electrophile-driven copper-catalyzed one-pot synthesis of 3-halogen quinoline derivatives

A convenient and regioselective one-pot synthesis of 3-chloride or 3-bromide quinoline derivatives was achieved through a Grignard addition reaction by alkynyl Grignard regent to o-trifluoroacetyl aniline and a Cu(II)-catalyzed cyclization–halogenation tandem reaction with aqueous HCl or HBr as electrophilic reagent.     

Study of Cl−(H2O)n (n = 1–4) using basin‐hopping method coupled with density functional theory

Cl^?(H₂O)_n (n = 1–4) clusters were investigated using a basin‐hopping (BH) algorithm coupled with density functional theory (DFT). Structures, energetics, thermodynamics, vertical detachment energies, and vibrational frequencies were obtained from high‐level ab initio calculations. Through comparisons with previous theoretical and experimental data, it was demonstrated that the combination of the BH method and DFT could accurately predict the global and local minima of Cl^?(H₂O)_n (n = 1–4). Additionally, to optimize larger Cl^?(H₂O)_n (n > 4) clusters, several popular density functionals as well as DF‐LMP2 (Schütz et al., J. Chem. Phys. 2004, 121, 737) (second‐order Møller‐Plesset perturbation theory using local and density fitting approximations) were tested with appropriate basis sets through comparisons with MP2 optimized results. DF‐LMP2 will be used in future studies because its overall performance in describing the relative binding energies and the geometrical parameters of Cl^?(H₂O)_n (n = 1–4) was outstanding in this study. © 2013 Wiley Periodicals, Inc.     

Removal of uranium from aqueous solution by using activated palm kernel shell carbon: adsorption equilibrium and kinetics

Activated palm kernel shell carbon (APKSC) was used to remove U(VI) from aqueous solutions in a batch system. The adsorption kinetics, isotherms, and effects of various parameters, such as temperature, contact time, solution pH, adsorbent dosage, and initial U(VI) concentration on the U(VI) adsorption process were studied. Equilibrium was reached after 120 min in the range of studied U(VI) concentrations and temperatures. U(VI) uptake was insignificantly affected by temperature, but was highly pH dependent, and the optimum pH for removal was 5.5. U(VI) removal efficiency increased with the increasing adsorbent dosage. U(VI) sorption capacity increased with increasing initial U(VI) concentration; any further increases in initial U(VI) concentration above a certain point caused insignificant changes in U(VI) sorption capacity. Isotherm data could be described by the Langmuir isotherm model with a maximum U(VI) adsorption capacity of 51.81 mg/g. Kinetic data were fitted to pseudo-first-order and pseudo-second-order equations, which suggested that the U(VI) adsorption onto APKSC was better reproduced by the pseudo-second-order model rather than pseudo-first-order model. Our results indicated that APKSC might be used as a cheap adsorbent in the treatment of uranium-containing wastewater.     

Extraction kinetics of Uranium(VI) and Thorium(IV) with Tri-iso-amyl phosphate from nitric acid using a Lewis Cell

The extraction kinetics of uranium(VI) and thorium(IV) with Tri-iso-amyl phosphate (TiAP) from nitric acid medium has been investigated using a Lewis Cell. Especially, dependences of the extraction rate on stirring speed, temperature, interfacial area were firstly measured to elucidate the extraction kinetics regimes. The experimental results demonstrated that extraction kinetic of U(VI) is governed by chemical reactions at interface with an activation energy, E_a, of 43.41 kJ/mol, while the rate of Th(IV) extraction is proved to be intermediate controlled, of which the E_a is 23.20 kJ/mol. Reaction orders with respect to the influencing parameters of the extraction rate are determined, and the rate equations of U(VI) and Th(IV) at 293 K have been proposed as $$ {\text{r}} = - {\text{dcUO}}_{ 2} \left( {{\text{NO}}_{ 3} } \right)_{ 2} /{\text{dt}} = 1. 80 \times 10^{ - 3} \left[ {{\text{UO}}_{ 2} \left( {{\text{NO}}_{ 3} } \right)_{ 2} } \right]^{ 1.0 1} \left[ {\text{TiAP}} \right]^{0. 5 5} , $$ $$ {\text{r}} = - {\text{dcTh }}\left( {{\text{NO}}_{ 3} } \right)_{ 4} /{\text{dt}} = 1. 8 8\times 10^{ - 3} \left[ {{\text{Th }}\left( {{\text{NO}}_{ 3} } \right)_{ 4} } \right]^{ 1.0 4} \left[ {\text{TiAP}} \right]^{ 1. 7 7} \left[ {{\text{HNO}}_{ 3} } \right]^{0. 3 8} , $$ respectively.     

Self-calibration method for cerium-doped lanthanum bromide scintillator detector in the 0.1–2.0 MeV energy range

In recent years, the cerium-doped lanthanum bromide, LaBr₃ (Ce = 5 %) detector is increasingly playing an important role in radiation measurements because of its higher energy resolution (~3 % at 662 keV), faster luminescence decay time (~35 ns) and higher detection efficiency compared to 7.65 cm × 7.65 cm NaI(Tl) detector. Intrinsic spectra between 1,800 and 3,000 keV derived from internal radioactivity within LaBr₃(Ce) scintillators have been investigated in some literatures, and these results are confirmed by the experiments in this work. In this paper, a new method for LaBr₃(Ce) detector energy calibration from 100 to 2,000 keV is proposed using the intrinsic spectra (self-calibration) instead of the standard gamma sources. Proof-of-concept experiment results show that self-calibration can guarantee energy accuracy of better than 0.815 % and can be applied outside the laboratory. The stability and applicability of this method are also investigated systematically.     

CuInS2纳米纸阵列薄膜的制备及生长机理

采用溶剂热合成技术,以氯化铜、硝酸铟和硫脲为反应物,十六烷基三甲基溴化铵(CTAB)为阳离子表面活性剂,草酸为还原剂,无水乙醇为溶剂,直接在掺氟的SnO2透明导电玻璃(FTO)衬底上合成CuInS2(CIS)薄膜.采用扫描电子显微镜(SEM)、高分辨率透射电子显微镜(HRTEM)、X射线衍射(XRD)、拉曼光谱、能量色散谱(EDS)、紫外-可见(UV-Vis)反射光谱和透射光谱对样品的形貌、结构、成分和光学性能进行分析.结果表明,在适当的反应物浓度下,在FTO衬底上形成了垂直衬底生长的、具有良好结晶性能的黄铜矿结构的CIS纳米纸阵列薄膜.CIS薄膜中Cu,In,S的原子比为1.1∶1∶2.09,在紫外-可见和近红外波段具有良好的光吸收特性,禁带宽度约1.51 eV.结合不同反应时间制备的CIS薄膜的形貌、结构和成分分析,讨论了CIS纳米纸阵列薄膜的生长机理.     

铁酸镍用于热化学循环反应CO2分解制CO的研究

采用共沉淀法制备了NiFe₂O₄和NiFe₂O₄/ZrO₂催化剂,用TGA考察了其热化学法,CO₂高温分解反应性能。通过对反应前后催化剂的表征发现,反应高温使两种催化剂都发生了明显的烧结,导致在热还原反应中形成的还原态氧化物不能完全被CO₂氧化从而降低了催化剂的反应性能;ZrO₂的加入对于提高催化剂的热稳定性以及循环反应稳定性具有重要的作用。在高温反应炉中考察了NiFe₂O₄/ZrO₂的CO₂分解实验,结果表明,提高热还原温度可以提高CO产量,然而,随着循环次数的增加CO的产量降低得更明显。     

Fitting formula for the injection volume of a gas chromatograph for radio‐xenon sampling in the lower troposphere

GC is usually used for xenon concentration and radon removal in the International Monitoring System of the Comprehensive Nuclear‐Test‐Ban Treaty. In a gas chromatograph, the injection volume is defined to calculate the column capacity. In this paper, the injection volume was investigated and a fitting formula for the injection volume was derived and discussed subsequently. As a consequence, the xenon injection volume exponentially decreased with the column temperature increased, but exponentially increased as the flow rate increased.