配体能级分布对稀土配合物荧光性能的影响

通过研究稀土配合物Eu(BA)3phen,Eu(SA)3phen和Eu(TBA)3phen的紫外可见吸收光谱和荧光光谱,分析了三种不同的有机配体的能级分布情况以及这些能级与Eu3+的最低激发态能级的匹配程度。紫外可见吸收光谱表明,三种稀土配合物具有不同的吸收峰。荧光光谱表明三种稀土配合物的荧光发射强度有很大差异。根据分析结果,解释了三种稀土配合物荧光强度的差别主要来源于三种不同的第一配体能级的吸收紫外光能力,以及与Eu3+的最低激发态能级的匹配程度。这种分析方法使用配体能级分布的理论探讨了稀土配合物内部能量传递过程的问题,为深入研究稀土配合物荧光材料提供了新的思路。     

Insights into Nitrogen-doped Carbon for Oxygen Reduction: The Role of Graphitic and Pyridinic Nitrogen Species

Nitrogen-doped carbons (N/Cs) manifest good catalytic performance for oxygen reduction reaction (ORR) for fuel cell systems. However, to date, controversies remain on the role of active sites in N/Cs. In the present study, ORR test was conducted on three N/Cs in O₂-saturated 0.1 M KOH aqueous solution, where apparent linear correlation between graphitic N contents and ORR activity was observed. Theoretical calculations demonstrated that graphitic N doping is energetically more favorable than that of pyridinic N doping for ORR and the pyridinic N leads to more preferential with 2 e^– ORR pathway. These results reveal that graphitic N plays a key role in N/Cs mediated ORR activity. This work lays a solid foundation on identifying the active sites in heteroatom-doped carbons and can be exploited for rational design and engineering of effective carbon-based ORR catalysts.     

镧、铈对酸雨胁迫下龙眼(Dimocarpus longana Lour.)花粉萌发和坐果的影响

研究了La3+和Ce3+对酸雨胁迫下龙眼花粉萌发和坐果的影响.结果表明,酸雨胁迫下,低浓度(0.1～1 μmol·L-1)的La(NO3)3或Ce(NO3)3可以减轻酸雨对花粉的伤害,提高花粉萌发率,高浓度(10 μmol·L-1)则加重了酸雨的伤害作用;0.1～10 mmol·L-1的La(NO3)3和Ce(NO3)3均可以提高龙眼的坐果率,减轻酸雨对龙眼果实的伤害.     

Koch曲线的Hausdorff测度上界的研究

研究了 Koch曲线的Hausdorff测度的上界估计,通过在Koch曲线上构造分形级更高的新覆盖,得到新覆盖与Koch曲线的交集对应的连通弧,并利用相关定理计算出了 Koch曲线的Hausdorff测度,得到了更好的上界估计值Hs(K)≤0.58764947.这是迄今所知的Koch曲线的Hausdorff测度的最好上...     

激光熔覆FeCrNiMnMoxB0.5高熵合金涂层组织与耐蚀性能

为了获得性能优异的涂层材料,采用激光熔覆的方法在Q235钢基体上制备了不同Mo含量的FeCrNiMnMoB0.5系高熵合金涂层,着重探究Mo对高熵合金组织与性能的影响。通过金相、X射线衍射、扫描电镜、硬度计、电化学工作站分别研究了高熵合金涂层的显微组织、相结构、显微硬度及耐蚀性能。结果表明：FeCrNiMnMoB0.5系高熵合金组织为树枝晶,主要由fcc相和少量金属间化合物构成。当添加少量Mo时,涂层的硬度较低,为290 HV,随着Mo的增加,晶格畸变加剧,出现少量金属化合物,涂层硬度最大增加到658 HV。在模拟饱和盐水泥浆溶液中FeCrNiMnMo0.4B0.5表现出较好的耐腐蚀性。     

19芯Fe/Cu复合包套二硼化镁超导线制备及其超导性能研究

采用In-Situ PIT方法,以工业级低纯度B粉(92%)和镁粉(99%)为原料制备了19芯Fe/Cu复合包套MgB2超导线。断面扫描电镜观测表明,超导线内部超导芯分布排列均匀,Fe层都能完好包围MgB2芯体,Fe与Cu层结合紧密,填充因子0.17。750℃热处理1h后,样品超导转变温度Tc(onset)=33.5K,转变宽度ΔTc=4.8K。X光衍射检测发现,MgB2超导相中不存在其它Mg-B化合物杂项,但含有少量MgO和FeB2。多芯化后,超导芯中FeB2略有增加。四引线Ic测试发现,19芯样品在4.2K,4T时,临界电流密度为5622A/cm2,比单芯样品14400 A/cm2降低约2/3。     

Global Structure of Positive Solutions of Fourth-Order Problems with Clamped Beam Boundary Conditions

Mathematical Notes - In this paper, we investigate the global structure of positive solutions of $$\begin{cases} u''''(x)=\lambda h(x)f(u(x)), & 0<1, \\...     

Solvation studies of electrospray ions—method and early results

Experiments are described in which bare (completely desolvated) ions are separated from their source gas and mixed with a bath gas of any desired temperature and precisely controlled composition. The resulting mixture of ions and bath gas is transported by free jet expansion into a vacuum system for mass analysis to reveal the extent to which the ions have formed adducts with other species in the bath gas. Because the ions are separated from their source gas or vapor before they are mixed with the bath gas, the compositions of the bath gas and source gas are completely independent. Thus, one can examine solvation or adduction by any desired species contained in the bath gas without any interference from other species that might be present in the source gas. Reported here are results obtained on the solvation of electrospray ions of a small peptide, leucine-enkephalin, by water and several alkanols. One provocative finding is that a substantial fraction of ions thought to be singly charged monomers turned out to be doubly charged dimers.     

Synthesis of backbone thermo and pH dual‐responsive hyperbranched poly(amine‐ether)s through proton‐transfer polymerization

Stimuli‐responsive hyperbranched polymers have attracted great attention in recent years because of their wide applications in biomedicine. Through proton‐transfer polymerization of triethanolamine and 1,2,7,8‐diepoxyoctane with the help of potassium hydride, a series of novel backbone thermo and pH dual‐responsive hyperbranched poly(amine‐ether)s were prepared successfully in one‐pot. The degrees of branching of the resulting polymers were at 0.40–0.49. Turbidity measurements revealed that hyperbranched poly(amine‐ether)s exhibited thermo and pH dual‐responsive properties in water. Importantly, these responsivities could be readily adjusted by changing the polymer composition as well as the polymer concentration in aqueous solution. Moreover, in vitro evaluation demonstrated that hyperbranched poly(amine‐ether)s showed low cytotoxicity and efficient cell internalization against NIH 3T3 cell lines. These results suggest that these backbone thermo and pH dual‐responsive hyperbranched poly(amine‐ether)s are promising materials for biomedicine. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

试论高校技术开发系统内部运行机制的构建与完善

本文论述了技术开发工作在高校自我发展中的地位与作用，进而确定了高校开展技术开发活动的要素条件，在分析阻碍高校开展技术开发工作内部症结问题的基础上，初步建立了由整合机制、动力机制、导向机制、调控机制和发展机制等五部分构成的良性高校技术开发系统内部运行机制。