HPLC Determination of Ascorbic Acid Using Luminol-Cu(Ⅱ) Chemiluminescence-Application to the Analysis of Juice Beverage

The chemiluminescence (CL) of luminol-Cu(Ⅱ) was applied to HPLC determination of ascorbic acid, which was separated by a C18 reverse-phase column with a mobile phase of 0.25 mol/L HAc. The eluted ascorbic acid was mixed with 0.3 mmol/L luminol and 0.05 mol/L CuSO4. The light emission from the reaction of Cu(Ⅱ) oxidized ascorbic acid and luminol was detected by a modified luminometer. The detection limit was 3.6×10-6 mol/L for ascorbic acid at a S/N ratio of 3, and the linear calibration range was 2×10-4- 2×10-3 mol/L. The relative standard deviation for 5 replicate injections of 1×10-3 mol/L ascorbic acid was calculated as 4.3 %. The method was successfully applied to determination of ascorbic acid in juice beverage.     

E.coli酪氨酸转氨酶的纯化与非天然氨基酸的底物特异性检测

构建重组菌株E.coliBL21(DE3)转pET23a-tyrB,IPTG诱导其大量表达,然后依次通过盐析、离子交换层析、疏水层析、凝胶过滤层析获得纯酶,运用薄层层析技术(TLC)检测,结果表明纯化的TyrAT转氨酶对自身底物酪氨酸在37℃和50℃具有较高活性.分别加入非天然氨基酸L-正缬氨酸、L-新戊基甘氨酸、L-叔亮氨酸、D-正亮氨酸作为底物,检测到TyrAT转氨酶对L-叔亮氨酸在50℃下有活性,对D-正亮氨酸在37℃和50℃均有催化活性,且50℃下效果更好.     

小球藻(Chlorella vulgaris)产油脂最佳培养条件的筛选

以低温作为环境条件诱导小球藻(Chlorella vulgaris)产脂,采用正交试验的方法来研究不同水平下Mn,K,Mg和S各元素对小球藻生长及脂肪产量的影响.本实验C N-1比为41.2:1,pH值范围为7.4~7.5之间,培养温度为15℃,P浓度为0.2~0.4 mmol.L-1,Fe浓度为0.04 mmol.L-1,以自养生长型式培养,而培养基成份根据BG11培养基作为基础进行改良.根据实验结果显示,脂肪产量最高为实验编号10(64.59 mg(100 mL)-1,64.59%),即锰及镁在一定程度上能促进小球藻的生长,且脂肪产率更高.     

Electrooxidation of Mn(Ⅱ) on Pb-Sb-As Electrode in Sulfuric Acid

The electrooxidation of Mn(Ⅱ) on Pb-Sb-As alloy electrode in sulfuric acid has been investigated.In order to make the two steps of indirect electrosynthesis of benzaldehyde carried out in the same sulfuric acid concentration and also obtain high current efficiency of Mn(Ⅱ) to Mn(Ⅲ) and high yield of Mn(Ⅲ) oxidizing toluene to benzaldehyde in the mean time,the electrooxidation of Mn(Ⅱ) in 60% H2SO4 has been studied.Experimental results show that high current efficiency of Mn(Ⅲ) (about 75%) is obtained in 60%H2SO4 at 60℃.The reason affecting the current efficiency of Mn(Ⅲ) is discussed,and it is the coordination of sulfuric acid concentration and electrolytic temperature.The law is found that it is suitable for electrolysis at low temperature when sulfuric acid concentration is low and at high temperature when sulfuric acid concentration is high.     

N-杂环-2，2-二甲基环丙烷甲酰胺类化合物的合成及表征

以2，2-二甲基环丙烷甲酸类化合物为先导化合物，合成了7种新的N-杂环2，2-二甲基环丙烷甲酰胺类化合物，所有新化合物经元素分析、^1H NMR确证，7种新化合物的产率较高，为43％～72％．     

TBP萃取一元有机酸的研究

考察了不同稀释剂中ＴＢＰ对甲酸、乙酸、丙酸、丁酸、氯乙酸、二氯乙酸、三氯乙酸等一元有机酸的萃取．探讨了被萃取物结构与萃取性能的关系及稀释剂性质和温度对萃取的影响．用红外光谱对萃取机理进行了研究．正辛烷中不同有机酸的萃取顺序为，①三氯乙酸＞二氯乙酸＞氯乙酸＞乙酸，萃取平衡常数随有机酸的取代基诱导常数σ＊的增大而增大，两者间遵从Ｔａｆｔ线性关系，诱导效应是影响萃取的主要因素．②丁酸＞丙酸＞乙酸＞甲酸，随诱导效应减弱和空间效应增大，萃取能力增强，表明空腔效应起主要作用．     

Synthesis of 2,4-dibromo-5-fluorobenzonitrile

2,4-Dibromo-5-fluorobenzonitrile has been synthesized for the first time (81.5% yield). It may be used in synthesizing 2,4-dibromo-5-fluorobenzoic acid, the intermediates of fluoroquinolones. The ammoxidation procedure for preparation of the nitrile has been described in detail. Zheng Qiong: born in 1945, Associate professor     

硝酸洗涤剂对磷钼酸铵沉淀组成的影响

本文通过实验证实,磷钼酸铵沉淀与硝酸洗涤剂之间发生离子交换作用。经用稀硝酸洗涤后,部分沉淀的组成由(NH_4)_3PO_4·12MoO_3·nH_2O转变成为(NH_4)_2HPO_4·12MoO_3·nH_2O。并由此提出化学式(NH_4)_2HPO_4·12MoO_3·nH_2O不能代表磷钼酸铵沉淀的初始组成。     

D-Amino acids in mouse tissues are not of microbial origin

Summary Neutral free D-amino acid contents in the serum, kidney, liver, brain, small intestine and urine in germ-free mice and those in specific pathogen-free mice were compared. No significant difference was found. This strongly suggests that the free D-amino acids which were shown to be present in mice in our previous work^{1, 2} did not originate from the enteric microbial flora.