Cp2TiCl2/n-BuLi催化体系在烯烃加氢反应中的催化活性和稳定性

研究了Ｃｐ２ＴｉＣｌ２／ｎ－ＢｕＬｉ催化体系和构成和Ｔｉ浓度与其催化烯烃加氢反应活性和稳定性的关系。考察了不同结构的烯烃，反应温度和度物浓度对该体系催化性能的影响。结果表明，在高的ｎ（Ｌｉ）／ｎ（Ｔｉ）值和低催化剂浓度时，可得到很高的催化活性。     

Single-to-Multiple Channel Wavelength Conversions and Tuning of Picosecond Pulses in Quasi-Phase-Matched Waveguides

We report the single-to-multiple channel wavelength conversions of 1.57-ps pulses based on cascaded secondharmonic generation and difference frequency generation in quasi-phase-matched periodically poled lithium hiebate waveguides. For single-to-single channel wavelength conversion, no external cavity laser is required with use of a fibre ring laser. The conversion efficiency is about -21.44 dB. The converted idler wavelength can be tuned from 1526.4nm to 1537.5nm as the lasing pump wavelength is varied from 1566.1 nm to 1555.0nm. By employing several input pumps, tunable single-to-dual and single-to-triple channel wavelength conversions are experimentally demonstrated.     

酸处理活性炭催化水合肼还原硝基苯(英文)

以水合肼为还原剂,采用硝酸、盐酸、硫酸及氮气或氢气氛处理的活性炭为催化剂,考察了其催化硝基苯还原反应性能.结果表明,经化学处理后,活性炭表面形成了各种含氧官能团,它们可引发水合肼分解,并影响硝基苯的吸附.活性炭表面形成的含氧官能团越多,其催化硝基苯还原速率越快.其中经盐酸处理的活性炭表面形成的含氧官能团最多,因而表现出最高的硝基苯还原活性.     

ZnO或K_2O助剂对Cu/SiO_2-Al_2O_3催化剂上丙三醇和苯胺气相催化合成3-甲基吲哚反应的促进作用

研究了ZnO或K2O助剂对Cu/SiO2-Al2O3上丙三醇和苯胺气相催化合成3-甲基吲哚反应的促进作用,采用X射线衍射、透射电子显微镜、H2程序升温还原、NH3程序升温脱附以及热重-差热分析等技术对催化剂进行了表征.结果表明,适量ZnO或K2O的加入可明显提高催化剂的活性、选择性和稳定性,其中以ZnO的促进作用更强.ZnO不仅能增强活性组分Cu与SiO2-Al2O3载体之间的相互作用、提高Cu在载体表面的分散度,而且可有效抑制反应过程中Cu粒子的烧结;而K2O的加入却降低了Cu分散度,但也对反应过程中Cu粒子的烧结有所抑制.ZnO或K2O的加入均不同程度地增加了Cu/SiO2-Al2O3催化剂的弱酸中心数量,从而促进3-甲基吲哚的生成.     

400~1500 MeV质子轰击铅靶和钨靶的出射中子能谱的FLUKA和Geant4模拟研究

在ADS散裂靶系统的优化设计中,蒙特卡罗方法结合可靠的散裂反应理论模型进行中子学计算具有重要的作用。本工作利用Geant4程序中的INCLXX模型、BIC模型以及BERT模型和FLUKA程序分别模拟了597 MeV和1 500 MeV质子轰击薄铅靶不同出射角度的中子双微分截面,500,1 500 MeV质子轰击厚铅靶不同出射角度的中子双微分产额,以及400,600,800,1 000和1 200 MeV质子轰击厚钨靶在反角方向（175 °）的中子双微分产额,并与实验数据进行比较。研究表明,对于薄铅靶,Geant4程序的INCLXX模型和FLUKA程序模拟结果与实验符合得更好。能量在10～40 MeV范围内,BIC模型模拟结果明显高于实验数据,而BERT模型模拟结果略微低于实验数据。对于厚铅靶,在40 MeV左右所有的模拟结果都低于实验数据。对于厚钨靶,Geant4程序的BIC模型和FLUKA程序与实验数据符合得较好,INCLXX模型在能量高于60 MeV时模拟结果低于实验数据,BERT模型与实验数据差异较大。总体来看,Geant4程序的INCLXX模型和FLUKA程序进行ADS散裂靶相关的中子学的计算是合理和可靠的。The reliable Monte Carlo simulation codes coupled with nuclear reaction models play an important role in the neutronic calculation for the design and optimization of the ADS spallation target. In this work, the double differential cross sections at different angles produced from a thin lead target bombarded with 597 and 1 500 MeV protons, the neutron energy spectra at different angles produced from a thick lead target bombarded with 500 and 1 500 MeV protons, and the neutron energy spectra in the backward direction(175°) produced from a thick tungsten target bombarded with 400, 600, 800, 1 000 and 1 200 MeV protons are calculated with the Geant4 code coupled INCLXX, BIC and BERT models and the FLUKA code. The calculations are compared with the available experimental data. The results show that, for the thin lead target, the calculations with the Geant4 coupled INCLXX model and FLUKA code well reproduce the experimental results. In a energy range from 10 to 40 MeV, BIC model obviously overestimates the experimental results, and BERT model slightly underestimates the experimental results. For the thick lead target, all of the calculations underestimate the experimental results around 40MeV. For the thick tungsten target, the Geant4 coupled BIC model and FLUKA code well reproduce the experimental results. INCLXX model underestimates the experimental results above 60 MeV. BERT model bad reproduces the experimental results. Overall, the neutronic calculations with the Geant4 code coupled INCLXX model and FLUKA code for the ADS spallation target is reasonable and reliable.     

近红外聚乙烯醇荧光高分子材料的制备及性能

以一种方酸菁染料、水溶性石墨烯和聚乙烯醇为原料,设计合成了在近红外区具有强荧光(660~665 nm)特性及良好的光热稳定性的方酸菁/聚乙烯醇二元和方酸菁/石墨烯/聚乙烯醇三元高分子材料;与在水中相比,方酸菁染料在聚乙烯醇中的最大紫外-可见吸收和荧光波长红移,荧光强度和光稳定性大幅提高;石墨烯的存在增强了材料的光稳定性。     

Unified entropy entanglement with tighter constraints on multipartite systems

Monogamy and polygamy relations characterize the distributions of entanglement in multipartite systems. We provide a characterization of multiqubit entanglement constraints in terms of unified-(q, s) entropy. A class of tighter monogamy inequalities of multiqubit entanglement based on the α-th power of unified-(q, s) entanglement for α ≥ 1 and a class of polygamy inequalities in terms of the β-th power of unified-(q, s) entanglement of assistance are established in this paper.Our results present...     

以三乙酸甘油酯为底物制备光学活性戊醇的探索

1前言(S)-2-甲基-1-丁醇在手性精细化学品及药物合成中有重要的作用[1]。从20世纪90年代起,国外的(R,S)-2-甲基-1-丁醇拆分方面做了一些有益的尝试。Ayter Sagiroglu等人利用固定化脂肪酶催化三丁酸甘油酯与(R,S)-2-甲基-1-丁醇发生不对称酯交换反应,可制备e.e.为98%的(S)-2-甲基-1-丁醇[2]。同时我们的研究表明,无溶剂体系中,以猪胰脂肪酶或酵母脂肪酶为催化剂,三丁酸甘油酯为底物,拆分(R,S)-2-甲基-1-丁醇,可制备e.e.值大于90%的(S)-2-甲基-1-丁醇[3]。采用三丁酸甘油酯,虽然所得产品e.e.较高,但其价格昂贵(1000元/kg)、反应周期较长…