原子荧光光谱法测定皮革中9种重金属元素的含量

皮革样品经硝酸-高氯酸（4+1）混合酸湿法消解后,用氢化物发生-原子荧光光谱法测定其中砷、锑、汞、铅和镉的含量;样品经干法灰化后,用火焰原子荧光光谱法测定其中铬、钴、铜和镍的含量。对各元素的稀释介质、还原剂和仪器工作条件作了详细的叙述。9种元素的质量浓度与吸光度分别在一定的范围内呈线性关系;砷、锑、铅、钴和镍的检出限（3S/N）为0.5 mg·kg^-1,汞、镉和铜的检出限（3S/N）为0.05 mg·kg^-1,铬的检出限（3S/N）为5.0 mg·kg^-1。应用此法分析了皮革样品,以标准加入法做回收试验,回收率在89.2%～106%之间。     

三苯胺基取代的吡啶基二氟化硼配合物力致荧光变色及无墨书写测试

为了探究二氟化硼配合物的光学性能及实际应用,设计合成了一种以三苯胺为电子供体、二氟化硼为电子受体的D-π-A型二氟化硼配合物4′-(1,1-二氟-1H-1λ4, 9λ4-吡啶[1,2-c][1,3,5,2]氧二氮杂硼啉-3-基)-N,N-二苯基-[1,1′-联苯基]-4-胺(Py-TPA BF2).光学性能测试结果表明,该配合物具有分子内电荷转移特性和聚集诱导发光活性.进一步的研究结果表明,在外力刺激下,配合物Py-TPA BF2的固体荧光发射光谱从530 nm红移至550 nm,发光颜色由绿色转变为稻草黄色,且在二氯甲烷蒸气熏蒸后颜色恢复至绿色. X射线衍射测试结果表明,研磨和溶剂熏蒸过程可使配合物固体有序的晶相与无序的非晶相之间的相变转换,导致配合物Py-TPA BF2具有可逆的力致荧光变色性能.此外,该配合物还可应用于无墨书写的数据安全保护,这将有助于智能发光材料的合理设计.     

3~A’ and 3~A” Energy Surfaces for the VS~ CO_2 →VO~ COS Reaction

The title reaction proceeds via a one- and two-step mechanism along the 3A" and 3A’ surfaces, respectively. The 3A’ excited state surface has a lower barrier than the 3A" ground state surface (11.6 and 16.0 kcal/mol, respectively). We suggest that, at low energies, the reaction proceeds along the A’ surface and then makes an intersystem crossing to the A" surface and yields the ground state product VO (3∑-), which may explain the small VO cross-section at low energies observed in the experiment     

QSAR Studies on 7-Substituted Fluoroquinolones

1 INTRODUCTION Fluoroquionlones are potent antibacterials with a broad spectrum of activities against gram-positive and gram-negative organisims and mycobacteria by inhibiting bacterial topoisomerase II(DNA gyra- se)[1].These compounds have been successfully used in clinic for a decade and its market has risen in recent years only a little less than that of penicillins and macrolides[2]. The fluoroquinolones constitute a class of extremely potent and orally active broad spectrum antibact…