Nuclear data for the cyclotron production of ~（117）Sb and ~（90）Nb

This presented study is to make comparison of cross sections to produce ¹¹⁷Sb and ⁹⁰Nb via different reactions with particle incident energy up to 70 MeV as a part of systematic studies on particle-induced activations on enriched Sn, Y₂O₃ and ZrO₂ targets, theoretical calculation of production yield, calculation of required thickness of target and suggestion of optimum reaction to produce Antimony-117 and Niobium-90.     

Ternary Eutectic Growth in a Highly Undercooled Liquid Alloy

The crystal nucleation and growth mechanism during the formation of Ag42.4 Cu21.6 Sb36 ternary eutectic are investigated under substantial undercoo]ing conditions. The x-ray diffraction analysis shows that the solidified eutectic phases are not invo]ved (Ag) within a wide undercooling range of 6-114 K. This indicates that under high undercooling condition, the phase constitution of Ag-Cu-Sb eutectic is different from that in the equilibrium phase diagram. With the increase of undercoo]ing, the crystalline morpho]ogy of Ag42.4 Cu21.6 Sb36 alloy transforms from the mixed structure of primary θ(Cu2Sb), two pseudobinary eutectics and (ε θ Sb) ternary eutectic into a unique (ε θ Sb) ternary eutectic. The calculated results indicate that θ(Cu2Sb) is the leading nucleating phase among the three eutectic phases. In addition, the growth morpho]ogy of primary ε(Ag3Sb) compound in Ag60Cu6Sb34 alloy exhibits the characteristics of solid solution and its orthorhombic dendrite grows along the (111) directions.     

退火温度对a-Se0.70Ge0.15Sb0.15薄膜的结构和光学性质的影响

研究了退火温度对Se0.70Ge0.15Sb0.15薄膜的影响.通过热蒸发技术,在300K温度下将大块无定形Se0.70Ge0.15Sb0.1s沉积在石英和玻璃衬底上.研究发现,未经过退火处理的薄膜结构和在300K,1.33×10-5Pa下退火1小时后的薄膜结构都是无定形结构,而在同样气压470K温度下退火1小时的薄膜有结晶现象.通过在300 2 500nm范围内垂直入射光方向上透射率和反射率的测试,研究了薄膜的一些光学参数,如消光系数(k),折射系数(n)和吸收系数(a).研究发现,n和k同热处理温度有关.通过光学数据的分析,得到了不同条件下薄膜的间接带隙宽度(Enong),未经过热处理薄膜的Enong是1.715±0.021eV,300K下退火薄膜的Enong是1.643±0.021eV,470K下退火的Enong是1.527±0.021eV.退火温度降低了带隙宽度Enong,但增加了带尾eo这种效应可以根据Mott和Davis提出的多晶体系中态密度来解释.     

氢化物发生–原子吸收光谱法测定铅粉中痕量砷、锑

建立氢化物发生–原子吸收光谱法联用测定铅粉中痕量砷、锑的方法。试样用稀硝酸溶解,用5%抗坏血酸溶液作为砷(Ⅴ)、锑(Ⅴ)的预还原剂,5%的硫脲溶液作为其它元素的掩蔽剂,选用1%硼氢化钠溶液作为还原剂,氢化物反应在10%盐酸介质中进行。在优化的试验条件下,砷、锑的质量浓度在0~20 ng/m L范围内与吸光度线性相关,相关系数r2分别为砷0.999 6,锑0.993 8,方法的检出限分别为砷0.40 ng/m L,锑0.75 ng/m L。砷、锑测定结果的相对标准偏差分别为4.96%,6.27%(n=6),铅粉样品加标回收率分别为砷87.6%,锑79.3%。该方法准确可靠,可用于测定铅粉中痕量砷、锑。     

新黄酮类化合物的脱甲基反应及其抗氧化活性

以3,4-二甲氧基苯甲醛(1)为起始原料,使用文献已报道的三氟乙酸法合成了3个含两个甲氧基取代基的新黄酮类化合物4a-4c,在新制碘化铝的催化下发生脱甲基反应,合成了3个含多个羟基取代基的新黄酮类化合物5a-5c,产率均高于90%.所有目标化合物均经过IR,~1H NMR,ESI-MS对其进行了结构确认.通过测定羟基自由基和DPPH自由基清除活性两个方面评价其抗氧化活性,结果发现,脱甲基后产物活性均增强.