Lanthanide doping-facilitated growth of ultrasmall monodisperse Ba2LaF7 nanocrystals with excellent photoluminescence

Lanthanide doping not only works as sensitizer and activator, but also plays an important role to facilitate the growth of nanocrystal and to control the size, shape, and property of nanocrystals. Here, reported was the synthesis of monodisperse Ba(2)LaF(7) nanocrystals with the size of sub-10nm through a solvothermal method. We found the dopants of Ho(3+), Er(3+), or Yb(3+) facilitated the growth of Ba(2)LaF(7) nanocrystals obviously to a certain size within a shorter reaction time. Similar phenomenon can also be observed in the synthesis of LaF(3) nanocrystals. We find that Ln(3+) (e.g., Ho(3+), Er(3+), or Yb(3+)) with smaller radius can reduce the nucleation energy and lead to heterogeneous nucleation, which favors the growth of Ba(2)LaF(7) nanocrystals obviously. In addition, intense upconversion emission can be observed from Ln(3+)-doped Ba(2)LaF(7) nanocrystals under the 980 nm laser excitation, providing great potential application in biological imaging. Especially, Ba(2)LaF(7):Yb/Er (20/1 mol%) nanocrystals present more intense upconversion emission than α-NaYF(4):Yb/Er (20/1 mol%) nanocrystals under the same conditions.     

高密度聚乙烯与乙烯丙烯辛烯－1共聚物共混体系的相容性

用ＤＳＣ和ＷＡＸＤ方法研究了高密度聚乙烯／聚（乙烯丙烯辛烯－１）（ＨＤＰＥ／ＥＰＯ）共混体系的结晶性能。共混物的ＤＳＣ曲线皆呈单峰，表明共混体系形成了共晶。晶胞参数ａ及结晶度随共混物组成而变，进一步证明ＨＤＰＥ／ＥＰＯ共混体系的相容性．     

PEO／EVA共混物的结构研究

ＰＥＯ以分散相形式存在于ＰＥＯ／ＥＶＡ共混物中，且具有部分相容性。Ｘ－射线衍射谱表明ＥＶＡ含有较强的ＰＥ衍射峰；ＰＥＯ／ＥＶＡ共混物既表现出ＰＥ的衍射峰也含有ＰＥＯ的晶面反射。随着ＰＥＯ的Ｍｎ的增加，ＰＥＯ／ＥＶＡ的Ｗｃ、ｘ增大且于时获得最大值：ＰＥ０／ＥＶＡ的Ｗｃ、ｘ值比纯ＰＥＯ的Ｗｃ、ｘ明显降低。     

螯合型二甘醇钛酸酯的合成及其催化性能研究

报导了两种新的螯合型二甘醇钛酸酯的合成方法，进行了ＩＲ和ＵＶ鉴定，并作为酯化反应催化剂催化合成了邻苯二甲酸二辛酯。研究了酯化反应转化率与反应时间、反应温度及催化剂用量的关系，探讨了催化剂结构与催化性能的关系。     

一种新的乙酰胆碱酶电极的研究

本文制备了一种以溶剂聚合膜ＰＨ电极作原电极，经高碘酸钠活化的醋酸纤维膜固定乙酰胆碱酯酶的乙酰胆碱生物电极。研究了酶固定化条件的影响，测得静态和动力学条件下的线性中响应范围分别为２４０－１３００μｇ／ｍＬ和３００－１７００μｇ／ｍＬ将电极用于实际样品的回收率试验中，获得了满意的结果。     

人工神经网络及其在分析化学中的应用

人工神经网络是一种新兴的计算方法，有着广阔的发展前途，目前在分析化学领域已经有了多方面的应用。本文简要介绍了人工神经网络的原理及其在分析化学中的应用。     

The Jahn-Teller effect in CH3Cl+(X̃2E): a combined high-resolution experimental measurement and ab initio theoretical study

The energy levels of CH(3)Cl(+)X?(2)E showing strong spin-vibronic coupling effect (Jahn-Teller effect) have been measured up to 3500 cm(-1) above the ground vibrational state using one-photon zero-kinetic energy photoelectron and mass-analyzed threshold ionization spectroscopic method. Theoretical calculations have been also performed to calculate the spin-vibronic energy levels using a diabatic model and ab initio adiabatic potential energy surfaces (PESs). In the theoretical calculations the diabatic potential energy surfaces are expanded by the Taylor expansions up to the fourth-order including the multimode vibronic interactions. The calculated spin-orbit energy splitting (224.6 cm(-1)) for the ground vibrational state is in good agreement with the experimental data (219 ± 3 cm(-1)), which indicates that the Jahn-Teller and the spin-orbit coupling have been properly described in the theoretical model near the zero-point energy level. Based on the assignments predicted by the theoretical calculations, the experimentally measured energy levels were fitted to those from the diabatic model by optimizing the main spectroscopic parameters. The PESs from the ab initio calculations at the level of CASPT2/vq(t)z were thus compared with those calculated from the experimentally determined spectroscopic parameters. The theoretical diagonal elements in the diabatic potential matrix are in good agreement with those determined using the experimental data, however, the theoretical off-diagonal elements appreciably deviate from those determined using the experimental data for geometric points far away from the conical intersections. It is also concluded that the JT effect in CH(3)Cl(+) mainly arises from the linear coupling and the mode coupling between the CH(3) deform (υ(5)) and CH(3) rock (υ(6)) vibrations. The mode couplings between the symmetric C-Cl stretching vibration υ(3) with υ(5) and υ(6) are also important to understand the spin-vibronic structure of the molecule.     

Photochemically inactivated hepatitis B virus promotes upregulation of Th1-type cytokines

Photochemical virus inactivation technology is widely used to improve the safety of blood products. However, the process by which this inactivation occurs and the resulting immunogenicity of treated viruses remain to be elucidated. This study aimed to explore the effects of two photochemical inactivation methods (methylene and riboflavin, MP and RP) on hepatitis B virus (HBV) immunogenicity. Inactivated HBV were incubated with PBMC from six healthy donors. Culture supernatants were collected at 0, 24 and 72 h for the analysis of HBsAg and HBeAg expression using ELISA. Cytokine expression was analyzed at 72 h using ELISA. Costimulatory and cell adhesion molecule mRNA expression was analyzed at 24 h by RT–PCR. No significant changes in HBsAg and HBeAg were detected following MP. However, the secretion of TNF‐α and IFN‐γ was upregulated. Expression of CD80, CD86, ICAM2 and LFA3 mRNA was also upregulated. In contrast, although RP did not significantly alter HBsAg expression, a reduction in HBeAg expression was observed. Furthermore, no upregulation of cytokines and intracellular molecule expression was observed following RP. These data indicate that the immunogenicity of HBV is retained following MP, and the inactivation of HBV could upregulate the Th1‐type cellular immune responses, which may play significant roles in the antiviral process.     

Molecular engineering and solvent dependence of excitation energy hopping in self-assembled porphyrin boxes

It has been demonstrated that the direction and magnitude of transition dipole moments, and hence rates in the excitation energy hopping in the self-assembled porphyrin boxes can be tuned by insertion of ethynyl groups as well as the dielectric constant of solvent.