尖晶石铁氧体TixNi1-xFe2O4中阳离子分布和Ti离子磁矩的实验研究

采用固相反应法制备了系列样品Ti_xNi_1-xFe₂O₄ (x=0.0, 0.1, 0.2, 0.3, 0.4). 室温下的X射线衍射谱表明样品全部为(A)[B]₂O₄型单相立方尖晶石结构, 属于空间群Fd3m. 样品的晶格常数随Ti掺杂量的增加而增大. 样品在10 K温度下的比饱和磁化强度σ_S随着Ti掺杂量x的增加逐渐减小. 研究发现, 当Ti掺杂量x≥ 0.2时, 磁化强度σ随温度T的变化曲线出现两个转变温度T_L和T_N. 当温度低于T_N时, 磁化强度明显减小; 当温度达到T_N时, dσ/dT具有最大值. σ-T曲线的这些特征表明, 由于Ti掺杂在样品中出现了附加的反铁磁结构. 这说明样品中的Ti离子不是无磁性的+4价离子, 而是以+2和+3价态存在, 其离子磁矩的方向与Fe和Ni离子的磁矩方向相反. 利用本课题组提出的量子力学方势垒模型拟合样品在10 K温度下的磁矩, 得到了Ti, Fe和Ni三种阳离子在(A)位和[B]位的分布情况, 并发现在所有掺杂样品中, 80%的Ti离子以+2价态占据尖晶石结构的[B]位.     

HOMOCLINIC ORBITS FOR A CLASS OF THE SECOND ORDER HAMILTONIAN SYSTEMS

The existence of homoclinic orbits is obtained by the variational approach for a class of second order Hamiltonian systems q(t)+▽V(t,q(t))=0,where V(t,x)=-K(t,x)+W(t,x),K(t,x) is neither a quadratic form in x nor periodic in t and W(t,x) is superquadratic in x.     

Theoretical Study of the Low-Lying Excited States of Butoxy Radicals and Non-Radiative Decay Routes

The potential energy surfaces for the butoxy radical dissociation into R·＋O on the six low-lying electronic states have been determined with the combined CASSCF and MR-CI methods. The isomerization reactions between the different conformers of 1- and 2-butoxy radicals at the X and B states have been also investigated with the MP2, B3LYP, and CASSCF methods. The non-radiative decay mechanisms of butoxy radicals at the B state have been characterized with the computed potential energy surfaces and intersections. Supported by recent LIF experimental results, it was predicted that the t-butoxy radical would predissociate via the B/C intersection. As to 1- and 2-butoxy radicals, the relative energies of the transition states for the isomerization reactions between conformers at the B state are much lower than those of the B/C intersections, resulting in the predominance of the isomerization in the decay of the B state for 1- and 2-butoxy radicals.     

水溶性稠杂环均三唑并噻二唑体系的合成及生物活性(I): 哌嗪取代衍生物

4-氨基-5-吡啶-4-基-均三唑硫醇(1)在复合催化剂DMAP和TBAB作用下与对卤代苯甲酸经环缩合反应以高收率得到中间体6-(5-氯-3-甲基-1-取代苯基-1H-吡唑-4-基)-3-吡啶-3-基-均三唑并[3,4-b][1,3,4]噻二唑(2a～2c), 接着苯环卤原子与取代哌嗪在聚乙二醇催化作用下发生亲核取代反应得到相应的哌嗪游离碱(3a～3c). 其中, 单取代哌嗪游离碱3a与含功能基的卤代物缩合得到功能基取代的哌嗪衍生物(4a～4g). 这些产生的游离碱与盐酸反应得到相应的水溶性盐酸盐. 所合成新化合物的结构经元素分析和光谱数据表征, 并评价了它们的体外抗菌活性及构效关系.     

分散液液微萃取-高效液相色谱法同时测定烟用接装纸中Cr^(3+)和Cr^(6+)的含量北大核心CSCD

用20 mL水超声提取2 g剪碎后的烟用接装纸样品30 min,分取8 mL提取液,加入200 mmol·L^(-1)二乙基二硫代氨基甲酸钠(螯合剂)溶液100μL,在体系酸度为pH 6.0条件下,于45℃反应10 min。反应结束后,加入正十二醇(萃取剂)60μL和甲醇(分散剂)100μL,涡旋,离心,取上层有机相,用甲醇定容至0.5 mL,过滤至色谱瓶中待测。以ZORBAX SB-C_(18)色谱柱为固定相,以不同体积比的甲醇-水混合液为流动相进行梯度洗脱,分离后的目标物用二极管阵列检测器于258 nm进行检测。结果显示:Cr^(3+) 、Cr^(6+)标准曲线的线性范围均为2.00~100.00μg·L^(-1),检出限(3S/N)分别为3,6μg·kg^(-1);对实际样品进行加标回收试验,Cr^(3+) 的回收率为90.7%~105%,测定值的相对标准偏差(RSD,n=7)为4.2%~7.3%,Cr^(6+)的回收率为84.1%~106%,测定值的RSD(n=7)为4.5%~7.6%;Cr^(3+) 、Cr^(6+)的富集因子分别为25.6和9.5;方法用于5份实际样品分析,其中4份样品中均检出Cr^(3+) 和Cr^(6+),并且Cr^(6+)检出量均比Cr^(3+) 检出量高。     

基于多目标优化的改航策略研究

随着我国航空运输的快速发展,由恶劣天气等原因导致的航班延误日益增多.传统的改航策略选取总延误损失最小为单一目标,不仅难以满足流量管理不同对象、不同阶段的需求,而且易造成空域利用率偏低.首先将改航策略与地面等待和空中等待相结合,然后综合考虑航空公司的利益,建立多目标优化模型,并采用稳定性和健壮性较强的多目标进化算法求解.最后选取全国典型繁忙日的实际飞行计划,进行了仿真验证.仿真结果表明,策略不仅可为航班动态地选择航路以避开容量限制区域,还可供流量管理部门参考不同目标来确定改航方案.     

EXISTENCE OF SOLUTIONS FOR NON-PERIODIC SUPERLINEAR SCHRODINGER EQUATIONS WITHOUT （AR） CONDITION

The existence of solutions is obtained for a class of the non-periodic Schrdinger equation -Δu + V (x)u = f (x, u), x ∈ R N , by the generalized mountain pass theorem, where V is large at infinity and f is superlinear as |u| →∞.     

孢子丝菌分子生物学DNA多态性分型研究

目的研究孢子丝菌DNA分型,并探讨DNA分型技术在临床菌钟鉴定以及流行病学中的应用.方法本实验采用氯化苯法提取DNA,以NS5、NS6为引物用随机扩增DNA多态性(DAPD)方法对临床分离的30株孢子丝菌进行DNA分型.结果30株孢子丝菌的DNA带型不完全相同,具有一定的遗传变异性.30株临床分离的孢子丝菌可进一步分为4型.不同部位取材的菌株间及临床型不同的患者的菌株间DNA型基本相同.结论随机扩增DNA多态性研究发现孢子丝菌具有一定的种内差异.该方法可将临床分离的孢子丝菌分为4型.本研究对病原学诊断探讨感染来源,传播途径等流行病学研究奠定了基础.     

水溶性稠杂环均三唑并噻二唑体系的合成及生物活性(I): 哌嗪取代衍生物

4-氨基-5-吡啶-4-基-均三唑硫醇(1)在复合催化剂DMAP和TBAB作用下与对卤代苯甲酸经环缩合反应以高收率得到中间体6-(5-氯-3-甲基-1-取代苯基-1H-吡唑-4-基)-3-吡啶-3-基-均三唑并[3,4-b][1,3,4]噻二唑(2a～2c), 接着苯环卤原子与取代哌嗪在聚乙二醇催化作用下发生亲核取代反应得到相应的哌嗪游离碱(3a～3c). 其中, 单取代哌嗪游离碱3a与含功能基的卤代物缩合得到功能基取代的哌嗪衍生物(4a～4g). 这些产生的游离碱与盐酸反应得到相应的水溶性盐酸盐. 所合成新化合物的结构经元素分析和光谱数据表征, 并评价了它们的体外抗菌活性及构效关系.     

Molecular Modeling of Interactions of the Benzolactam-V8 Modulators with the Cys2 Domain of Protein Kinase Cδ

Molecular modeling of interactions of four 7- or 8-substituted benzolactam-V8 （BLV） molecules with the cys2 activator-binding domain of protein kinase C （PKCδ） was carried out using molecular docking program Autodock. The docked models reveal that the hydroxymethyl group at the C（5） atom of the eight-membered ring of each BLV is bound at the bottom of the binding groove of the cys2 domain of PKCδ The BLV molecules make hydrogen bonds and hydrophobic interactions with PKCδ, which are similar to those in the crystal structure of the cys2 domain of PKCδ in complex with phorbol 13-acetate. BLV-1 does not contain a long side chain that is hydrophobic and necessary for membrane insertion, so that it would not be a potent modulator of PKCδ. The other three BLV molecules have long side chains substituted at C（7） or C（8） atoms, and it was predicted, based on the docking results, that they had the PKCδ-binding affinity in the order of BLV-2〉BLV-4〉BLV-3, and BLV-2 would be a potent activator of PKCδ.