偏振分束器对光学电流传感器稳定性的影响

采用偏振光学理论,详细分析了光学电流传感器中偏振分束器消光比的变化对传感器性能的影响,得到了偏振分束器消光比与传感器输出的关系式,并用系统实验进行了验证.理论及实验结果的吻合证明了光学电流传感器稳定性直接受偏振分束器两路消光比影响的结论.     

Ph(SiMe_2)_nPh体系π→π~*UV谱的研究

本文依据Spin-Free理论,使用Gelfand基构造多电子波函数,采用四轨道模型,对Ph(SiMe_2)_nPh体系(n=1～6)的π→π*跃迁进行了EHMO-CI计算,所得第一及第二跃迁能与UV谱的实验结果基本一致。当体系硅链原子数增加时,第一吸收带红移的现象起因于LUMO中d轨道成份增加,导致电子排斥作用变化。在LUMO中,硅链上的d轨道以πd的形式与苯环π~*轨道进行πd—π~*共轭互相作用,这种作用很可能与第一吸收带的强度有内在的联系。     

库仑滴定法测定有机硅样品中的氮含量

本文利用库仑滴定法研究了高分子和低分子硅氮化合物及含氮有机硅样品中氮含量的测定,并研究和讨论了影响测定结果准确性的因素。     

Imaging cellular distribution of fluorescent supramolecular nanofibers

In this study, we used the 4-nitro-2,1,3-benzoxadiazole (NBD) as an aromatic capping group for a peptide to construct the supramolecular nanofibers. Taking the advantage of the fluorescence property of NBD, we could directly observe the cellular distribution of the self-assembled nanofibers. We found that the distributions of the nanofibers of NBD-FFETIGGY are different in four mammalian cells and two plant cells. The nanofibers are mainly located at the surface of two mammalian cells and one plant cell, while in the intracellular space of other cells. Different distributions of nanofibers lead to different protein binding patterns of the nanofibers in two different cell lines. We believe that a useful and versatile platform has been offered to the image cellular distribution of nanofibers, which can provide useful information to the biological functions of the self-assembled nanostructures.     

Solubilization of organic compounds by arginine-derived polymers

Poor aqueous solubility of drugs is one of the major challenges in the pharmaceutical science. In this study, a guanidinium-containing polymer based on arginine was designed and synthesized, and was evaluated as a solubility enhancing additive for three model organic compounds (coumarin, pyrene and doxorubicin). At a guanidinium group concentration of 100 mmol/L, the polymer could significantly increase the solubility of pyrene and doxorubicin by 6-and 11-fold respectively, much more effective than arginine (2-and 3-fold, respectively). In contrast, its effect on the solubility of coumarin was less effective than arginine. The solubilizing effect may be explained by the enhanced interaction between the guanidinium group in the polymer and the aromatic compounds.     

Facile Synthesis of Manganese Tellurite Nanoparticles for Magnetic Resonance Imaging-Guided Photothermal Therapy

In this study, manganese tellurite (MnTeO₃) nanoparticles are developed as theranostic agents for magnetic resonance imaging (MRI)-guided photothermal therapy of tumor. MnTeO₃ nanoparticles are synthesized via a simple one-step method. The as-synthesized MnTeO₃ nanoparticles with uniform size show good biocompatibility. In particular, MnTeO₃ nanoparticles exhibit a high photothermal conversion efficiency (η = 26.3%), which is higher than that of gold nanorods. Moreover, MnTeO₃ nanoparticles also have high MRI performance. The longitudinal relaxivity (r₁) value of MnTeO₃ nanoparticles is determined to be 8.08 ± 0.2 mm ⁻¹ s⁻¹, which is higher than that of clinically approved T₁-contrast agents Gd-DTPA (4.49 ± 0.1 mm ⁻¹ s⁻¹). The subsequent MnTeO₃ nanoparticles-mediated photothermal therapy displays a highly efficient ablation of tumor cells both in vitro and in vivo with negligible toxicity. It is demonstrated that MnTeO₃ nanoparticles can serve as promising theranostic agents with great potentials for MRI-guided photothermal therapy.     

Preparation of Iminoacetic Acid-type Composite Chelating Material IAA-PEI/SiO2 and Preliminary Studies on Chelating Adsorption Property towards Heavy Metal Ions

Polyamine polyethyleneimine (PEI) was first grafted on the surfaces of micro-sized silica gel particles in the manner of the coupling graft (the manner of “grafting to”), forming the grafting particles PEI/SiO₂. Subsequently, via a polymer reaction, the nucleophilic substitution reaction between the primary and secondary amino groups of the grafted PEI macromolecule and chloroactic acid (CAA), iminoacetic acid groups were bonded onto the grafted PEI chains, and an iminoacetic acid (IAA)-type composite chelating material, IAA-PEI/SiO₂, was formed. In this work, the preparation process of IAA-PEI/SiO₂ particles was mainly researched, and the effects of the main factors on the polymer reaction, i.e., the nucleophilic substitution reaction, were examined emphatically. The adsorption behavior of IAA-PEI/SiO₂ particles towards several kinds of heavy metal ions was preliminarily evaluated. The experiments results show that it is feasible to introduce IAA groups onto PEI/SiO₂ particles via the substitution reaction between CAA and the amino groups of the grafted PEI. The reaction rate is affected greatly by the feed ratio of the amino group of PEI to CAA, so the substitution reaction between CAA and the amino groups of the grafted PEI is a bimolecular nucleophilic substitution reaction (S_N2). The reaction temperature and the used amount of acid-acceptor NaHCO₃ affect the bonding rate of IAA groups greatly. The fitting temperature was 60°C, and 1:1 of the molar ratio of NaHCO₃ to CAA was an appropriate amount of acid-acceptor NaHCO₃. Under the above optimal reaction conditions and with 3:1 molar ratio of amino group of PEI to CAA, 72% of the IAA group bonding rate (it is based on the hydrogen atoms in the primary and secondary amino groups of the grafted PEI) in 8 h can be reached. The composite chelating material IAA-PEI/SiO₂ possesses a strong chelating adsorption ability for heavy metal ions because of the increase of the ligands and formation of stable five-membered chelate rings.     

柱前衍生-高效液相色谱法测定2,3-吡嗪二羧酸酐有关物质的含量北大核心CSCD

由于原料药2,3-吡嗪二羧酸酐易水解为有关物质2,3-吡嗪二羧酸,不能直接用高效液相色谱法测定.基于此,以甲醇衍生化2,3-吡嗪二羧酸酐后再采用高效液相色谱法测定2,3-吡嗪二羧酸酐中主成分和杂质2,3-吡嗪二羧酸、2-吡嗪甲酸的含量.按照质量体积比(mg∶mL)10∶7加入供试品和甲醇,超声衍生20 min,稀释后用高效液相色谱法分析.以YMC Triart C_(18)色谱柱为固定相,以不同体积比的0.5%(体积分数)三氟乙酸溶液和甲醇的混合溶液进行梯度洗脱,在270 nm处检测.结果显示:2,3-吡嗪二羧酸、2-吡嗪甲酸、2,3-吡嗪二羧酸酐之间的分离度均大于1.5,其质量浓度均在一定范围内与其对应的峰面积呈线性关系,检出限分别为0.0575,0.0548,0.0102 mg·L^(-1);对混合对照品溶液和供试品溶液连续分析6次,测定值的相对标准偏差均小于2.0%;2,3-吡嗪二羧酸、2-吡嗪甲酸的加标回收率分别为95.2%,98.3%;方法用于3批实际样品的分析,检出的2,3-吡嗪二羧酸酐的质量分数为97.83%~97.93%,2,3-吡嗪二羧酸的质量分数为2.07%~2.17%,而2-吡嗪甲酸未检出.     

The Comparative Study of Reaction Mechanisms and Catalytic Performances of Cu–SSZ-13 and Fe–SSZ-13 for the NH3-SCR Reaction

Catalysis Surveys from Asia - The catalytic performances and mechanism differences of model catalysts Cu–SSZ-13 and Fe–SSZ-13 with similar metal content and Si/Al ratio were compared....