X射线荧光光谱法测定萤石中CaF2、CaCO3、S、Fe及SiO2

X射线荧光光谱法分析是目前快速分析方法之一,精密度受基体效应、均匀性、元素间干扰等影响。采用粉末压片法制备样品,用X射线荧光光谱法直接测定F、Ca元素,得出CaF_2及CaCO_3含量,并同时分析萤石中S、Fe、SiO_2的含量。精密度实验表明,待测元素的相对标准偏差均低于0.66%(RSD,n=10),能满足萤石中各元素的检测要求。     

火花放电原子发射光谱法测定钛及钛合金中主要元素

采用火花放电原子发射光谱法测定了钛及钛合金中碳、铁、铝和钒的含量。通过对钛合金样品的表面处理方式、氩气流量和压力、类型标准化等参数的摸索,确立了一套系统的分析方法。结果表明,4种元素测定的相对标准偏差在0.40%～6.8%,测定结果和化学湿法分析结果相比基本一致,比较适合批量检测。     

Investigation of copper-azamacrocyclic complexes by high-performance liquid chromatography

The use of copper radioisotopes in imaging and therapy has prompted an increased interest in chelators which form stable copper complexes, such as Cu(II)-azamacrocyclic complexes. The effects of charge, stability and the size of the macrocyclic backbone of the Cu(II)-azamacrocyclic complexes on biological behavior have been evaluated. Here we report a reversed-phase high-performance liquid chromatography (HPLC) method to separate several Cu(II)-azamacrocyclic complexes, including Cu(II) complexes of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA), 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (CB-TE2A) and 4,10-bis(carboxymethyl)-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (CB-DO2A). Absorbance at 280 nm was used to monitor the complexes as they eluted from the reversed-phase column. The effects of the concentration of the buffer, the pH of the buffered mobile phase and the concentration of the organic modifier, methanol, on the separation were investigated. Separation of these copper complexes by ion-pair HPLC with the use of a mass spectrometry-compatible ion-pair reagent, triethylammonium acetate, in the mobile phase at pH 6.3 is also presented. The reversed-phase chromatographic conditions utilized also allow the pK(a)s of Cu-TETA and the log(k'w) values of Cu-CB-TE2A, Cu-TETA and Cu-CB-DO2A to be estimated.     

土木工程专业创新模型试验课程教学探索1）

本文介绍本校土木工程专业新设立的创新性课程结构模型概念与实验的设立及教学探索体会. 首先简介了大学生结构设计竞赛的优点及不足,阐述了课程设立的必要性;接着通过学生课外科研活动,考察了课程开设的可行性及具体措施;并在此基础上正式设立了本门课程. 介绍了课程开设两年来的具体教学情况,说明了本课程的教学目标、任务及效果. 最后对课程提出了建议及展望. 本文对其他相似的创新试验课程具有较好的参考借鉴意义.     

Pyrrolic nitrogen-doped carbon sandwiched monolayer MoS<Subscript>2</Subscript> vertically anchored on graphene oxide for high-performance sodium-ion battery anodes

In this work, a novel pyrrolic nitrogen-doped carbon sandwiched monolayer MoS₂ hybrid was prepared. This sandwiched hybrid vertically anchors on graphene oxide as anode materials for sodium-ion batteries. Such electrode was fabricated by facile ionic liquid-assisted reflux and annealing methods. Owing to rational structure and enhancement from pyrrolic nitrogen dopant, this unique MoS₂/C-graphene hybrid exhibits reversible specific capacity of 486 mAh g^?1 after 1000 cycles with a low average fading capacity of 0.15 mAh g^?1 (fading cyclic rate of ca. 0.03% per cycle). A capacity of 330 mAh g^?1 is remained at the current densities of 10.0 A g^?1. The proposed strategy provides a convenient way to create new pyrrolic nitrogen-doped hybrids for energy field and other related applications.     

光化学合成快速响应聚(N,N-二甲基丙烯酰胺-co-N-异丙基丙烯酰胺)水凝胶

通过光化学合成方法分别在高温(50℃)和室温(28℃)下实现了N,N-二甲基丙烯酰胺(DMAA)和N-异丙基丙烯酰胺(NIPAm)的交联共聚,制备了两种不同结构的P(DMAA-co-NIPAm)共聚物水凝胶.对两种温度下制备的P(DMAA-co-NIPAm)共聚物水凝胶的网络结构、溶胀与消溶胀速率和温度敏感性等方面进行了比较研究.结果发现,50℃下制备的P(DMAA-co-NIPAm)共聚物凝胶具有较为疏松的网络结构和相对较快的溶胀速率及温度响应特性.光化学合成方法较传统的热聚合制备方法具有简便、快捷的特点,合成过程仅需2 min.     

纳米SiO_2锚固光敏基团引发MMA光接枝聚合研究

对纳米SiO2进行了锚固光引发剂的表面修饰,进而引发甲基丙烯酸甲脂(MMA)光接枝聚合制备有机/无机复合粒子.纳米SiO2粒子首先用氯化亚砜进行表面氯化,再与光引发剂2-羟基-4-(2-羟基乙氧基)-2-甲基苯丙酮(Irgacure2959)反应从而锚固上光引发剂.通过紫外光引发MMA在经过修饰过的纳米SiO2表面上进行表面光接枝聚合.采用IR、TGA和TEM等方法表征了接枝前后纳米粒子的变化,证明了表面接枝物的存在,并研究了不同反应条件对单体转化率、接枝率和接枝效率的影响.研究结果表明,搅拌对接枝过程的影响比较显著.TGA结果显示未搅拌聚合时接枝率只能达到比较小的程度,而在搅拌条件下180min内MMA的接枝率可达到110%.     

Soft X-ray spectromicroscopy studies of pitting corrosion of reinforcing steel bar

Pitting corrosion of reinforcing steel bar (rebar) imbedded in concrete by chloride ions can cause concrete degradation. It is thus necessary to develop methods to mitigate concrete corrosion which could include using a protective polymer rebar coating. Corrosion studies of polyvinyl butyral-carbon black polymer-coated rebar using soft X-ray fluorescence (XRF) microprobe and micro-X-ray absorption near edge spectroscopy (μ-XANES) are reported in this study. After removal of the polyvinyl butyral-carbon black polymer coating, Fe Lα₁, Mn Lα₁, and O Kα₁ XRF maps were collected as well as Fe and Mn L₃-edge μ-XANES spectra from different regions across the whole rebar surface by collection of total electron yield (TEY) and partial XRF yield (PFY) spectra. The distribution of metallic Fe and Fe corrosion products was determined by analysis of the Fe XRF map. The μ-XANES spectra indicated a higher fraction of Fe (III) phases on the corroded rebar surface, while Fe (II/III) phases were the major corrosion products beneath the surface region. In addition, Mn (II) and Mn (III) were determined as the valence states of the manganese corrosion products.     

阳离子化松香的研究(Ⅰ)

松香作为一种丰富廉价的可再生资源已成为重要的基本化工原料,其应用涉及到300多个行业.我国是松香的主产国,80年代产量已跃居世界首位,但每年60%的松香都是以低附加值的初级产品出口,松香的再加工率仅7%,而发达国家松香的再加工率却高达100%,因此开发松香的深加工改性产品对于充分利用资源,改进松香产品的性能,扩展其应用领域都十分重要.     

Cooperative binding and self-assembling behavior of cationic low molecular-weight dendrons with RNA molecules

Tri(ethylene glycol) derived, low molecular-weight dendrons with various amine end groups were synthesized and characterized for their properties of binding and self-assembling with RNA using the Candida ribozyme as a model RNA molecule. These dendritic compounds form stable complexes and well-defined nanoscale particles with RNA molecules via electrostatic interactions and self-assembly process, while leaving the other terminal of the tri(ethylene glycol) chain accessible for targeting. This suggests that dendrimers of this type hold great promise for specific RNA targeting and RNA delivery.