液态丙烯腈低聚物修复聚丙烯腈基碳纤维微孔缺陷

提出一种全新的缺陷修复的方法,即将聚丙烯腈基(PAN)碳纤维T300在液态丙烯腈低聚物(LAN)中浸渍后,再进行预氧化和碳化热处理,可以将T300的拉伸强度提高25%.应用二维小角X射线散射(SAXS)法可以计算出LAN修复缺陷前后T300微孔缺陷的长度(L)、横截面尺寸(lp)、取向角(Beq)、相对体积(Vrel)的变化,结果表明碳纤维的拉伸性能越好,微孔的长度、取向角、相对体积含量越小.T300拉伸性能的提高是由于缺陷修复的结果.应用BET比表面积法、扫描电子显微镜(SEM)表征LAN修复缺陷前后T300的比表面积以及表面形貌的变化,结果表明,T300在LAN中浸渍并经过预氧化和碳化热处理,比表面积变小,表面缺陷明显减少.进一步验证LAN对碳纤维中的微孔缺陷具有修复作用.应用X射线光电子能谱(XPS)法表征LAN修复前后T300表面化学成分的变化,结果表明,LAN修复后含氧官能团(C―OH,C=O,HO―C=O)显著增加,有利于增强碳纤维与树脂基体之间的相互作用,从而提高碳纤维的力学性能.     

Determination of silver ion based on the redshift of emission wavelength of quantum dots functionalized with rhodanine

A simple and selective method for the determination of silver ions was developed by utilizing the red- shift in emission wavelength of the core-shell CdSe/Cd5 quantum dots （QDs） functionalized with rhodanine upon the addition of Ag＋. A linear relationship was observed between the shift and the increase in concentration of Ag＋ in the range of 0.0125-12.5 μmol/L. The mechanism of the red-shift was investigated and suggested that the coordination between Ag＋ and rhodanine on the QDs surface caused an increase of particle size, which resulted in the red-shift of the QDs＇ emission wavelength. A detection limit of 2 nmol/L was achieved. The developed method showed superior selectivity and was successfully applied to the determination of silver in environmental samples.     

Bioconversion of Corncob Acid Hydrolysate into Microbial Oil by the Oleaginous Yeast Lipomyces starkeyi

For the first time, corncob acid hydrolysate was used for microbial oil production by the oleaginous yeast Lipomyces starkeyi. After hydrolysis by dilute sulfuric acid, corncob could turn into an acid hydrolysate with a sugar concentration of about 42.3 g/L. Detoxified by overliming and absorption with activated carbon, the corncob hydrolysate could be used by L. starkeyi efficiently that a total biomass of 17.2 g/L with a lipid content of 47.0 % (corresponding to a lipid yield of 8.1 g/L) and a lipid coefficient of 20.9 could be obtained after cultivation on the corncob hydrolysate for 8 days. Therefore, L. starkeyi is a promising strain for microbial oil production from lignocellulosic biomass. Glucose and xylose were used by L. starkeyi simultaneously during lipid fermentation while arabinose could not be utilized by it. Besides, the lipid composition of L. starkeyi was similar to that of vegetable oils; thus, it is a promising feedstock for biodiesel production.     

Platinum(II) complexes of reduced amino acid ester Schiff bases: synthesis, characterization, and antitumor activity

A series of platinum(II) complexes of reduced amino acid esters Schiff bases were synthesized as potential anticancer agents and characterized by ¹H NMR, EA, IR, and molar conductivity. These compounds were tested for their DNA interaction with salmon sperm DNA by ultraviolet spectrum and CD spectrum, and their in vitro anticancer activities have been validated against HL-60, KB, BGC-823, and Bel-7402 cell lines by MTT assay. The cytotoxicity of complexes 5d and 5f are better than cisplatin against Bel-7402 cell lines, and show a close cytotoxic effect against HL-60 cell line.     

化学教学内容的学科理解研究——以“醛的结构与性质探究”为例

为在教学中切实落实化学学科核心素养,本研究从“学科”角度切入,针对教学内容探究教师如何进行学科理解。以乙醛课题为载体通过扎根理论分析专家团队基于学科理解的教学内容研讨过程,发现学科理解的对象主要是化学概念,在不同层级的概念理解中融汇化学学科思想方法。以核心概念羰基的理解过程为例,经历以下4个步骤:(1)比较烃类,确定乙醛的特殊性在于羰基;(2)基于乙醛特质挖掘本原性问题:如何基于结构认识羰基的性质;(3)运用比较分类逻辑方法抽提羰基的认识视角:极性多重键;(4)利用原子的杂化方式、电负性认识羰基结构特征,宏微结合发展认识思路。     

黄芪口服液中8种重金属元素含量的测定

在2015年版《中国药典》的基础上,采用原子荧光光谱法和电感耦合等离子体质谱法对黄芪口服液中的铅、砷、镉、汞、铜、锌、镍和铬进行测定,并对所用试剂、器皿,赶酸时间,内标的种类和加入方式进行了优化。结果表明,在样品处理前对器皿采用硝酸(30%)处理,赶酸时间在1.5h以上,以手动方式加入单内标103 Rh溶液,可以得到较准确、稳定的测定结果,8种元素测定的相对标准偏差(RSD)均小于4%,Hg、As、Cu、Pb、Zn、Cd、Ni、Cr的检出限分别为0.089、0.21、0.45、0.15、0.45、0.025、0.35和0.39μg/L,8种元素的加标回收率在92.0%～114%。方法对于黄芪口服液中痕量元素的检测,结果稳定,过程简单,引入污染小。     

歧管式微通道流动特性的研究

岐管式微通道(MMC)热沉具有热阻小、结构紧凑、冷却液流量小、流速低、沿流动方向温度分布均匀等优点.本文针对以去离子水为介质的岐管式微通道(宽W=100 μm,深H=300 μm)的流动特性进行了实验研究,实验的雷诺数范围为5O～3500.结果表明工质在微通道内流态由层流向紊流转变的临界雷诺数提前,此外数值模拟结果与实验值也吻合较好.最后在实验基础上,拟合出工质在层流和紊流下的流动阻力经验关联式.     

低压下酞菁裂解法制备定向碳纳米管阵列

在低压条件下以酞菁铁为原料, 采用独立双温控加热系统在石英玻璃基底上气相沉积制备了大面积准直性好和管径均匀的碳纳米管. 利用扫描电子显微镜(SEM/FESEM)和透射电子显微镜(TEM)研究了定向碳纳米管的生长形态和结构. 详细讨论了系统真空度、反应温度、气体流速及氢气和氩气的体积比例等参数对碳纳米管生长的影响, 并测试了该碳纳米管的场发射性能及超电容性能.     

石墨炉原子吸收光谱法测定土壤中离子交换态的镉

本文研究了石墨炉原子吸收光谱法测定土壤中离子交换态的镉的适宜条件.试样经MgCl2溶液震荡提取离心后,以10%的磷酸二氢铵做基体改进剂,方法检出限为0.03840 μg/L,相对标准偏差(n=6)为0.9231%.本方法具有准确、简便之优点,可用于土壤样品中镉的测定.