BEPCII新加速管的高功率测试和老练

BEPCⅡ(北京正负电子对撞机重大改进工程)要求其直线注入器提供更高的能量和流强,为此必须改进正电子产生靶前后的加速管,以提高加速梯度,并消除原有加速管因长期运行后性能有所下降的隐患.本文叙述了新加速管的高功率测试,包括测试装置的设计、建立,微波功率源(速调管)的调试和加速管高功率测试结果及其分析.     

苯丙酮酸催化氢化合成β-苯基乳酸

以甲醇为溶剂，在70℃，3．0MPa苯丙酮酸经Raney—Ni催化氢化反应1h得到了β-苯基乳酸的白色针状结晶，收率91％，转化率91%。并解析了β-苯基乳酸的IR及MS谱图。     

含有不同配体的钴配合物/EAO催化乙烯齐聚

考察了（bipy)CoCl2,(C6H5N=C-C6H4-o-O)2Co和（acac)2CO 3种配合物与EAO组成的二元催化体系A，B和C，在不同的反应温度，铝钴比以及不同反应时间对乙烯齐聚催化活性和选择性的影响，结果表明，3种催化体系都对催化乙烯齐聚反应有活性，在相同的反应条件下，3种催化体系对乙烯齐聚的催化活性顺序为：A＞B＞C，在反应温度为180摄氏度时，催化体系（bipy)CoCl2/EAO的活性为2441g/(gCo.H)，产物中低碳烯烃的选择性为95．9％。     

以PVA为分散介质制备纳米氧化铁颗粒及其ESR特征(英文)

利用金属离子在高分子配合物中独特的离子簇结构以及PVA对所制样品颗粒的良好保护和分散作用,通过配位转换的方法,在PVA介质中制备出超微氧化铁颗粒,并通过高温煅烧高分子金属氧化物复合体获得红褐色纳米氧化铁颗粒.XRD测试表明此氧化物为α Fe2O3和Fe3O4的混合物,粒径为40～65nm;样品的ESR结果表明该法制备的氧化铁颗粒具有较强的磁性.同时,还初步研究了PVA中氧浓度与Fe离子浓度的比及氨水浓度对产物粒径的影响.     

一种用于大容量逆流色谱制备的立式多层螺旋管行星式离心机

Owing to no complications caused by solid supports, such as adsorptive sample loss and deactivation, tailing of solute peaks, and contamination, countercurrent chromatography (CCC) has been an area of intense research since the first introduction of CCC in 1970,[1] and various apparatus and broad applications have been advanced[2,3]. For these developments, the type-J synchronous planet centrifuge has received considerable attention, which relies not only on its relatively simple mechanic design, but also on its high partition efficiency and short elution time caused by mixing and settling for the efficient chromatographic separations. In the past, however, almost all of type-J centrifuges rotated slowly were disposed horizontally due to the original design and some experiments that gravis plays an important role at a low rotary speed as similar to type-V rotating multilayer helical tube in unit gravity[4-9]. In fact,we discovered that the upright apparatus holds more retention of stationary phase than the horiziontal aparatus when large standard tubings were used as mutilayer coil column and the aparatus was operated under same contions. We report here a new coil planet centrifuge with four upright cylindrical columns for large scale countercurrent chromatographic preparation. The design principle and apparatus of UCCC is as samilar to type-J multilayer coil planet centrifuge. Four uptight cylindrical column holders are symmetrically arranged around the centrifuge axis as similar to the type-J HSCCC with three horizontal multilayer coils connected in series[8] . A series of experiments indicat that upright CCC has many advantages over the horizontal CCC when using a large-bore tube as multilayer coil column for large scale countercurrent chromatographic separation.Upright CCC provide a versatile countercurrent chromatographic method for large-scale preparation from very crude sample. It has good preparative capacity and flexible suitability to various sample and two-phase system.The present apparatus not only can be operated at a high speed as similar as commonly used HSCCC for the system having short settling time and but also can be run at a low speed for the system having relative long settling time. Because of automatical control and seal-free flow through device, the uptight CCC apparatus may be readily scaled up to industrial preparation.     

丰中子轻核新幻数N=16的解释(英文)

基于中子分离能的分析 ,Ozawa等提出丰中子轻核存在新幻数 N=1 6.对 N=1 6同中子素进行了形变和球形的相对论平均场计算 .相对论平均场的数值结果表明N=1 6同中子素有形状相变.这是一些丰中子核新幻数出现的可能原因. Based on the analysis of neutron-separation energies, Ozawa et al proposed a new magic number N =16 in light neutron-rich nuclei. The deformed and spherical relativistic mean-field(RMF) calculations have been carried out for N =16 isotones. The numerical relativistic mean-field results show there is a shape transition in N =16 isotones. This is the possible cause of the appearance of the new magic number in someneutron-rich nuclei.     

石墨表面吸附钾系统电子性质的理论研究

基于集团模型电荷自洽的EHT(Extended Hückel Tneory)方法对K在石墨(0001)表面吸附态进行了优化计算.在3种不同的覆盖度(Θ)下,对k-石墨系统的电荷转移量△Q、吸附能△E、态密度PDOS和TDOS、Mulliken集居数和成键性质进行了比较.认同K/石墨吸附系统是石墨插层化合物(GIC)的雏型.并用LMTO方法对KC₈完成电子结构的第一性原理研究,得到与EHT完全一致的结果:K4s-Ca杂化态主要位于低能区域远离费米能级,构成反键轨道其电子转移到费米能级附近K3d-Cπ成键的杂化轨道上.空的3d轨道在目前EHT方法和LMTO方法计算中扮演了关键角色.这与其他文献K-4s态处在EF能级的结果不同,但与早期Fischer(1984),Johnson(1986)XPS,ARUPS的实验结果吻合.     

一种检测十二指肠胃返流光纤传感器的研制

设计了可检测十二指肠胃返流的光纤传感器,该传感器由470 nm的信号光、595 nm参考光和光纤束构成,主要检测十二指肠返流物中的胆红素在470 nm与595 nm的吸光度,本文还对影响传感器检测的因素,诸如波长、pH、胃液中悬浮颗粒造成的散射作用以及其他的因素,做了详细评价.传感器可以达到10 mg/dl优良的动态响应范围,离体实验结果表明,该传感器可以作为临床动态检测手段.     

采用选择激发研究光系统Ⅱ反应中心β-Car的物理特性

光系统Ⅱ反应中心包含有2个去镁叶绿素分子(Pheo),2个β胡萝卜素分子(β-Car)和6个叶绿素a分子(Chla).对反应中心的时间分辨荧光光谱表明,两个β-Car具有不同的吸收光谱,吸收峰分别为489 nm(Car489)和507 nm(Car507),Car489靠近吸收峰为667 nm和675 nm的叶绿素a(Chl a),它的主要功能是保护反应中心免受单态氧的破坏,而不能将激发能传递给光化学反应活性的色素分子P680;Car507靠近吸收峰为669 nm的Chl a分子;能够将激发能传递给P680,进行电荷分离.采用全局优化拟合的方法对荧光光谱进行处理,Car489在61 ps时间内将能量传递给Chl a672, 随后传给Chl a677,处于激发态的Chl a677在3 ns衰减到基态;Car507在274 ps时间内将能量传递给P680,P680＋Pheo-的电荷重组发生在3.8 ns和16 ns.     

氘核极化结构函数的核效应

极化深度非弹性散射是研究质子、氘核内部部分子精细结构的有利工具.利用基于微扰QCD模型得到的6夸克集团内部自旋夸克的分布函数,研究了氘核极化结构函数的核效应.发现考虑了核效应后的氘核极化结构函数比没有考虑核效应的结果能更好地符合SLAC E155的实验数据.