On oscillation and asymptotic property of a class of third order differential equations

In this paper, oscillation and asymptotic behaviour of solutions of have been studied under suitable assumptions on the coefficient functions such that a(t 0, b(t) 0 and c(t) < 0.     

Synthesis of New Heterocyclic Ring Systems via [1,3,5]Triazino[1,2‐a]benzimidazole Derivatives

Three new heterocyclic ring systems were synthesized from [1,3,5]triazino[l,2‐a]benzimidazole derivatives, which in turn were obtained by condensation of 2‐guanidinobenzimidazole with o‐substituted ben‐zaldehydes.     

An approach to novel fused triazole or tetrazole derivatives starting from benzimidazo[1,2‐a]quinazoline‐5(7H)‐one and 5,7‐dihydro‐5‐oxopyrido[3′,2′:5,6]pyrimido[1,2‐a]benzimidazole

The synthetic potential of the title compounds benzimidazo[1,2‐a]quinazoline‐5(7H)‐one 2a and 5,7‐dihydro‐5‐oxopyrido[3′,2′:5,6]pyrimido[1,2‐a]benzimidazole 2b for the construction of novel polyhetero‐cyclic frameworks is reported. Compounds 2a,b , by conversion into their thio analogues 3a,b , were used for the synthesis of tetrazole ( 5a,b ) and triazole ( 7a,b ) derivatives, as well as for an unexpected synthesis of tri‐azoles 8a,b , isomers of 7a,b , resulting from the occurrence of a Dimroth rearrangement.     

氢原子在过渡金属修饰的Mg(0001)面扩散的第一性原理研究

基于密度泛函理论(DFY)的第一性原理计算方法,对氢原子在过渡金属(Sc、Ti、Cr、Mn、Fe、Co、Ni、Cu、V、Zn)修饰的Mg(0001)表面扩散性能进行了研究.研究发现过渡金属元素Sc、Ti、V、Cr、Mn、Fe、Co、Ni和Cu选择替代在镁表面第二层稳定,而Zn则选择替代在第一层稳定.当镁表面掺杂Zn和Cu时,氢原子选择停留在表面稳定;当掺杂Sc、Ti、V、Cr、Mn、Fe、Co和Ni时,氢原子选择进入镁块体内部.值得一提的是氢原子通过从过渡金属顶部通道扩散进入镁块体内部的势垒大大降低,笔者用差分电荷密度分析后发现氢原子与过渡金属原子成键使扩散势垒降低.当氢原子进入镁块体内部后靠近Sc、Ti、V、Cu和Zn原子时,将与这些过渡金属原子成键,从而阻碍了氢原子继续向内部扩散;而氢原子靠近Cr、Mn、Fe、Co、Ni原子时,选择离开过渡金属从而促进了氢原子向块体内扩散,可以大幅改善镁基储氢材料的吸氢动力性能.     

A wide-band Whispering Gallery Mode dielectric resonator having multiple high-Q cavities for high-field ESR spectroscopy

The behaviour of a disc-shaped dielectric resonator made of sintered alumina and working in the Whispering Gallery Mode (WGM) has been studied in the frequency interval from about 8 up to about 26 GHz. Many equidistant resonances have been detected in this frequency interval each of which being characterized by a satisfactoryQ-value due to the very good self-confinement of the microwave field which is typical of WGM propagation. Particular care has been devoted to the optimization of the coupling between the resonating disc and the microwave source. Examples of ESR spectra obtained on each of the detected resonances are reported which show the variation of the lineshape with the increase of the frequency. The obtained results allow one to foresee that the same dielectric disc can be used for ESR spectroscopy also at frequencies much higher than those up to now exploited.     

Prenatal stress and subsequent exposure to chronic mild stress influence dendritic spine density and morphology in the rat medial prefrontal cortex

Background  

Both prenatal stress (PS) and postnatal chronic mild stress (CMS) are associated with behavioral and mood disturbances in humans and rodents. The aim of this study was to reveal putative PS- and/or CMS-related changes in basal spine morphology and density of pyramidal neurons in the rat medial prefrontal cortex (mPFC).     

青海省唐古特铁线莲质量控制标准的研究

目的对青海省唐古特铁线莲质量控制标准进行研究。方法采用薄层色谱法对唐古特铁线莲进行定性鉴定,展开剂为氯仿与丙酮（95：5）,显色剂为10％硫酸甲醇;采用HPLC（Lc-2010HT）法测定唐古特铁线莲中齐墩果酸的含量,色谱柱为PhenomenexLunaCt8（250mm×4．6mm,5Ixm）,流动相为y（乙腈）＋V（0．2％磷酸水溶液）=35＋65,流量为1mL／min,柱温为室温（25℃）,检测波长为205nm。结果薄层色谱鉴定中,供试品色谱与对照品色谱相应的位置上,显示出相同颜色的荧光斑点;齐墩果酸在0．0233—0,7000mg／mL范围内呈良好的线性关系,线性回归方程为Y=2×10-6＋360803,r。=0．9917,RSD为1．61％,并对青海省野生和栽培唐古特铁线莲中齐墩果酸进行了定量分析,结果显示前者平均值为0．1184％、RSD为2．5113％,后者平均值为0．0651％、RSD为2．92％。结论该法操作简单、快速、准确、灵敏、重现性好,可有效控制青海省唐古特铁线莲的质量。