紫外光催化氧化消解-氢化物发生-原子荧光光谱法测定人发中Se

采用紫外光催化氧化消解试样,氢化物发生-原子荧光光谱法测定人发中Se含量的方法.探讨了消解条件、原子荧光光度计工作条件及氢化物发生反应条件,对比沸水浴加热和紫外光加热2种将Se (Ⅵ)还原为Se (Ⅳ)的方法,研究氨基磺酸消除氮氧化物干扰的最佳条件.在最佳实验条件下测定人发标准参考物质和人发试样中Se的含量,方法的检出限为0.08 μg/L (相对标准偏差为2.1%),荧光强度与Se (Ⅳ)的质量浓度在0～10 μg/L范围内呈线性关系.研究结果表明,人发标准参考物质中Se的测定值与标示值相吻合.人发试样中Se的质量分数与文献值(0.4～0.9 μg/g)一致.     

电化学氢化物发生-原子荧光法测定环境样品中的Se(Ⅳ)和Se(Ⅵ)

设计了一种新的电化学氢化物发生装置, 用于测定不同价态的硒. 通过对传统的平板电解池的改进, 设计了全新的圆盘电解池并采用螺纹密封的方式, 极大地缩短了电解池的装配时间, 提高了电解池的使用寿命和密封性能. 结合热水浴在线还原技术, 将 Se(Ⅵ)在高浓度HCl介质中120 s内还原成Se(Ⅳ), 通过电化学氢化物发生技术生成氢化物, 成功的进行硒的在线价态分析. 对各种实验参数进行了详细的研究, Se(Ⅳ) 和Se(Ⅵ)的相对标准偏差分别为2.6% 和 3.1% (n=11);Se(Ⅳ)和总硒的检出限分别为0.32和0.27 μg/L (3σ).     

硒对大蒜根尖细胞有丝分裂影响的初探

用不同浓度的亚硒酸钠溶液分别处理大蒜根尖6小时,18小时和24小时,发现硒对大蒜根尖细胞的毒害作用与其浓度和作用时间有关:当处理时间≤18小时、硒的浓度≤1μg/ml时,促进大蒜根尖细胞的有丝分裂;反之则抑制,说明硒具有二重性.同时还观察到染色体畸变现象.     

Hemilability and regioselectivity in palladium and platinum complexes of dppm(E) [E = O, S, Se] ligands

Hemilability and nonrigidity in a series of mixed P^PE donor ligands where E = O, S, or Se have been studied in palladium and platinum complexes of the type [M{κ²-(dimethylamino)ethylnaphthyl-C,N)}(P^PE)][SbF₆] where P^PE = Ph₂PCH₂P(E)Ph₂.The role of the donor in hemilability, regioselectivity and the binding preferences of particular donors trans to the metallated carbon atom were also investigated. NMR parameters including couplings to ¹⁹⁵Pt and ⁷⁷Se were investigated for cis and trans isomers. The magnitude of ²J¹³C-⁷⁷Se couplings can readily distinguish the cis and trans isomers. A large through-space ¹³C-⁷⁷Se ³J coupling was observed in one of the amino methyl groups of the dppm(Se) complexes.     

ICP－AES法同时测定电解金属锰中的硅、铁、硒和磷

本文研究了用ＩＣＰ－ＡＥＳ直接测定电解金属锰中的Ｓｅ、Ｐ、Ｓｉ、Ｆｅ等元素的方法，方法简便、快速，精密度和准确度均能满足对出口电解金属锰的检验要求。     

Isochronous Mass Measurements of Hot Exotic Nuclei

A novel method for mass measurements of short-lived exotic nuclides is presented. Exotic nuclides were produced and separated in flight at relativistic energies with the fragment separator (FRS) and were injected into the experimental storage ring (ESR). Operating the ESR in the isochronous mode we performed mass measurements of neutron deficient fragments of ⁸⁴Kr with half-lives larger than 50 ms. However, this experimental technique is applicable in a half-life range down to a few μs. A mass resolving power of 110000 (FWHM) has been achieved. Results are presented for the masses of ⁶⁸As, ^70,71Se and ⁷³Br. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cross-sections for the formation of isomeric pair Ge through (n, 2n), (n, p) and (n, α) reactions measured over 13.73 MeV to 14.77 MeV and calculated from near threshold to 20 MeV neutron energies

The cross-sections for formation of isomeric pair, ⁷⁵Ge^m(σ_m) and ⁷⁵Ge^g(σ_g), through ⁷⁶Ge(n, 2n), ⁷⁵As(n, p) and ⁷⁸Se(n, α) reactions were measured at 13.73 MeV, 14.42 MeV and 14.77 MeV neutrons and also estimated using EMPIRE-II and TALYS codes over neutron energies from near threshold to 20 MeV. For each (n, 2n), (n, p) and (n, α) reaction, the cross-section initially increases with neutron energy, but starts decreasing as the neutron energy exceeds the respective threshold of (n, 3n), (n, pn) and (n, αn) reactions. The higher values of σ_m relative to σ_g reveal that the transitions of the excited ⁷⁵Ge from higher energy levels to metastable state (7⁺/2) are favored as compared to unstable ground state (1⁻/2). The present values of cross sections for formation of ⁷⁵Ge^m,g through (n, 2n) and (n, α) reactions are lower, and that of (n, p) reaction are higher compared to most of the corresponding literature cross-sections.     

硒与免疫功能——硒对大吞噬细胞吞噬活性影响的研究

本研究探讨了硒和V_E对家禽外周血中大吞噬细胞的吞噬活性的影响,结果表明,吞噬细胞的吞噬活性与补硒和V_E有关.补硒和补硒+V_E的鸡,吞噬细胞的吞噬活性都明显的高于试验前及对照组,且硒和V_E对吞噬活性的增强有一定的协同作用.     

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.