Chemo-enzymatic Synthesis of Z-Asp-Val-Tyr-NH_2——A Precursor Tripeptide of Thymopentin

Z-Asp-Val-Tyr-NH2,a precursor tripeptide of thymopentin(TP-5),was successfully synthesized by a combination of chemical and enzyme methods.Firstly,the precursor dipeptide Val-Tyr-NH2 was synthesized by a novel chemical method in four steps including the preparation of NCA-Val,the esterification of L-tyrosine and the ammonolysis of L-tyrosine ethyl ester,and the formation of Val-Tyr-NH2 from NCA-Val and L-Tyr-NH2.Secondly,a thermolysin,thermoase PC 10F was used to catalyze the formation of Z-Asp-Val-Tyr-NH2 in an aqueous/organic solvent diphase system with Z-Asp-OH and Val-Ty-NH2 as the substrates under thermodynamic control.The optimum conditions were pH=6.5,40 ℃,thermoase 100 mg,in 2-(N-morpholino) ethanesulfonic acid MES/NaOH(containing 5 mmol/L CaCl2) of n-butanol system(15/85,volume ratio) for 20 h in a maximum yield of 27.02%.     

反相离子对色谱-脉冲安培电化学法测定硫酸庆大霉素中各组分含量

建立了一种新的用反相离子对液相色谱(LC)分离,以金电极为工作电极的脉冲安培电化学法(PAD)直接检测硫酸庆大霉素中各组分含量的分析方法。流动相为0.033 mol/L草酸、0.012 mol/L七氟丁酸、210 mL/L乙睛,用稀NaOH调节pH至3.4。与报道的其它方法相比,该方法能使庆大霉素各有效组分C1、C1 a、C2、C2 a很好分离,整个分析过程<30 m in。考察了各色谱参数对分离测定的影响。实验证明,本方法不需要衍生化,可直接检测硫酸庆大霉素。     

聚邻氨基酚/Ni2+修饰碳糊电极的制备及其对葡萄糖的电催化氧化

以循环伏安法在碳糊电极(CPE)表面上修饰聚邻氨基酚膜(P-OAP),再以浸泡吸附法在此膜中嵌入金属离子Ni2 ,制成Ni/P-OAP/CPE。该电极在0.09mol/LNaOH溶液中通过90圈扫描活化后,在-0.15至0.65V区间出现一对峰形良好且稳定的氧化还原峰。循环伏安实验发现,Ni/P-OAP/CPE对葡萄糖的电氧化有良好的催化特性,催化活性受薄膜的厚度、薄膜中Ni2 的浓度、电极的活化时间以及电解液组成的影响。实验结果表明:该电极是一种良好的无酶葡萄糖传感器。     

Alkali Uptake and Swelling Behavior of Lyocell Fiber and their Effects on Crosslinking Reaction

The swelling behavior of lyocell fiber in alkali solutions and the alkali uptake were investigated as well as their influences on the reaction of sodium-hydroxy-dichlor-triazine with lyocell. The uptake of NaOH was increased from 0.69 mmol/g up to 4.63 mmol/g, leading to the enhancement of fiber swelling from 1.01 cm³/g to 2.34 cm³/g when alkali concentration in preliminary alkali treatment was increased from 0.4 mol/l to 8.0 mol/l. The rise in alkali uptake heightened the crosslinking reaction. The fiber swelling was hindered by addition of acetone to alkali solution, resulting in water retention capacity of 0.64 cm³/g in the 37.5% v/v of acetone/water mixture and increase in the reaction yield. The fiber was more swollen in NaOH solution than in KOH though the uptake of NaOH was 5.7-times less than that of KOH. The reaction yield of crosslinking agent in NaOH solution was 9.9-times larger than that in KOH at the same alkali uptake. The abrasion resistance of lyocell fiber was improved by the method used in this work, causing high pilling resistance of lyocell fabric as compared to a conventional method.     

Grafting Vinyl Monomers onto Wool Fibers: Graft Copolymerization of Methyl Methacrylate onto Wool Using Ferric Acetylacetonate Complex

The graft copolymerization of methyl methacrylate (MMA) onto native and reduced Indian Chokla wool fibers was studied in aqueous solution using an acetylacetonate complex of Fe(III). Perchloric acid was found to catalyze the reaction. The rate of grafting was investigated by varying the concentration of the monomer and the complex, the acidity of the medium, and the solvent composition of the reaction medium. The graft yield increases with increasing concentration of the initiator and with increasing temperature. An increase of monomer concentration up to 0.5634 mol/L and of the HClO4 concentration up to 0.01 mol/L increases the graft yield. Reduced and oxidized wools were found to be better substrates than untreated, esterified, cross-linked, and trinitrophenylated wools. Among the various monomers studied, MMA was found to be the most active. A suitable kinetic scheme is proposed. From the activation energy data, average molecular weight, and spectral studies, the reactivity of -SH groups, and the extent of chain transfer is ascertained.     

Application of pH‐zone‐refining countercurrent chromatography in the chiral separation of two β‐adrenergic blocking agents

Two β‐adrenergic blocking agents, 1‐[(1‐methylethyl)amino]‐3‐phenoxy‐2‐propanol ( 1 ) and 1‐[(1‐methylethyl)amino]‐3‐(3‐methylphenoxy)‐2‐propanol ( 2 ; Toliprolol), were enantioseparated by pH‐zone‐refining countercurrent chromatography. A two‐phase solvent system composed of chloroform containing 0.10 mol/L of di‐n‐hexyl l‐ tartrate/0.10 mol/L of boric acid aqueous solution (1:1, v/v) was selected, in which 20 mmol/L triethylamine was added in the organic phase as a retainer and 2 mmol/L HCl was added in the aqueous phase as an eluter. Fifty milligrams of each racemate was completely enantioseparated by pH‐zone‐refining countercurrent chromatography to yield each enantiomer with a purity of more than 98%, and the recovery of each separated enantiomer reached around 76–82%.     

三烷基混合叔胺-正辛醇-磺化煤油萃取菜籽粕酸脱毒液中的植酸

用三烷基混合叔胺(N235)-正辛醇-磺化煤油从菜籽粕酸脱毒废液中萃取植酸,研究了水相pH值、植酸浓度、N235浓度对植酸分配比的影响。 确定萃取植酸的最佳条件为：初始pH=3.0、N235的浓度0.17 mol/L、正辛醇浓度0.48 mol/L、相比R为5∶1、萃取时间5 min,对0.02 mol/L标准植酸溶液的萃取率为95.2%。 以0.25 mol/L NaOH溶液为反萃取剂,在相比5∶2下反萃取5 min,三级反萃取总收率达到82.6%。 实验证明加入正辛醇可提高N235萃取植酸的分配比,可能与正辛醇和N235形成“分子簇”结构产生协同萃取有关。     

多肽在金纳米粒子表面偶联反应效率研究

通过1-(3-二甲氨基丙基)-3-乙基碳二亚胺(EDC)与N-羟基琥珀酰亚胺(NHS)活化反应将多肽偶联到金纳米粒子表面,采用荧光光谱研究其形成的酰胺键的反应偶联效率.考察了实验条件,包括缓冲液的种类(HEPES、Tris-HCl、硼酸、PBS缓冲液)、pH值(pH 6.5~9.0)、缓冲液浓度(10, 25, 40和50 mmol/L)、NHS和EDC的浓度(NHS 0.2~1.0 mol/L,EDC 0.01~0.5 mol/L)及二者比例(0,0.5,1.0,2.0和2.5)、偶联反应时间(4, 8, 12, 24和36 h)等对偶联效率的影响,筛选出最佳实验条件.实验结果表明, 25 mmol/L 4-羟乙基哌嗪乙磺酸(HEPES)缓冲液(pH 7.0), NHS/EDC浓度为0.4 mol/L/0.2 mol/L和24 h的反应时间为EDC-NHS活化反应将多肽偶联到金纳米粒子上的最佳实验条件.本研究结果可为相关研究提供技术参考.     

液相色谱-脉冲安培电化学法测定硫酸卡那霉素中各组分含量

建立了一种用反相离子对液相色谱(LC)分离,以金电极为工作电极的脉冲安培电化学法(PAD)直接检测硫酸卡那霉素中主要组分及杂质含量的分析方法。流动相为0.033mol/L草酸、0.012mol/L七氟丁酸、105mL/L乙腈,用稀NaOH调节pH至3.4。考察了各色谱参数对分离测定的影响。实验证明,本方法不需要衍生化,可直接检测硫酸卡那霉素。与报道的其它方法相比,本方法不仅能使硫酸卡那霉素中的卡那霉素A、B得到了很好的分离,还分离出了其它一些未能确证的组分。如用质谱法等对未知组分进行确证后,对硫酸卡那霉素原料药、注射液、滴眼液及兽药等实际样品中的卡那霉素各组分进行测定。可望成为一种标准分析方法。     

月桂酰基苹果酸酯胶束电动色谱-质谱法同时测定牛黄上清片中5种生物碱

建立了基于月桂酰基苹果酸酯的胶束电动色谱-质谱法同时分离测定牛黄上清片中黄连碱、小檗碱、药根碱、黄柏碱以及川芎嗪5种有效成分含量的新方法。以7.5 mmol/L月桂酰基苹果酸酯-15 mmol/L氨水-50 mmol/L醋酸铵(含12.5%的乙腈,pH=7.0)为电泳介质,未涂层弹性石英毛细管(88 cm×50 μm)为分离通道,50%异丙醇水溶液(含3 mmol/L乙酸)为鞘液,在25 kV的运行电压下,各组分可以在18 min内得到基线分离。各组分的浓度与其峰面积呈现良好的线性关系,迁移时间和峰面积的相对标准偏差均小于5%,样品中5种生物碱成分的样品加标回收率在96.0%～105%之间。该法简便、快速、准确、重现性好,可用于牛黄上清片中这5种有效成分含量的同时测定。     

Scanning electrochemical microscopy in combination with piezoelectric quartz crystal impedance analysis for studying the growth and electrochemistry as well as microetching of poly(o-phenylenediamine) thin films

The combination of scanning electrochemical microscopy (SECM) with piezoelectric quartz crystal impedance (PQCI) analysis was proposed as a novel multiparameter method for investigating the cyclic voltammetric growth of poly(o-phenylenediamine) (PoPD) thin films at Au electrodes in aqueous solutions of various pH values and the potentiostatic microetching (localized degradation) of these films in 0.10 mol/L aqueous H2SO4 for comparative examinations on polymer porosity and stability. Two potential-sweep ranges, -0.4 to 0.9 (I) and 0 to 0.9 (II) V versus SCE, and four solutions, acidic (A, 0.20 mol/L H2SO4 + 0.10 mol/L Na2SO4; B, 0.10 mol/L H2SO4 + 0.20 mol/L Na2SO4), neutral (C, 0.10 mol/L PBS + 0.20 mol/L Na2SO4, pH 7.2), and alkaline (D, 0.20 mol/L NaOH + 0.20 mol/L Na2SO4) aqueous solutions, were selected for PoPD growth. The pH increase for the polymerization solution increased the molar percentage of polyaniline-like chains in PoPD, as quantified from the current peaks at approximately 0.6 V versus a saturated calomel electrode (SCE) for the oxidation of -NH2 groups in as-prepared PoPD (grown from solutions C and D) during their redox switching in 0.10 mol/L aqueous H2SO4 for the first time. The unusual PQCI responses observed at negative potentials (potential range I) in the first several potential cycles during the cyclic voltammetric growth of PoPD in acidic and neutral solutions have been reasonably explained as being due to the precipitation/dissolution of the poorly soluble phenazinehydrine charge-transfer complexes developed during redox switching of oligomers for the first time, which brought about much less compact PoPD films and their higher degradability than those grown in the same solution but over potential range II. SECM, scanning electron microscopy (SEM), and piezoelectric quartz crystal (PQC) frequency were used to estimate the sizes of etched microscale spots. In addition, the x-, y-, or z-axis movement of a Pt microelectrode of 25-mum diameter near the PQC electrode was found to influence negligibly the PQCI responses in 1.0 mol/L aqueous Na2SO4 containing K4Fe(CN)6 up to 0.10 mol/L, and a new protocol of dynamically electrodepositing silver microwires via the chemical-lens method was proposed for examining the local mass-sensitivity distribution on the PQC surface.     

皂化P204微乳体系萃取大豆蛋白的研究

研究了NaOH皂化P204/正辛烷微乳体系萃取大豆蛋白的机理和工艺,考察了大豆加入量、P204的浓度、NaOH的浓度、萃取时间、水相pH值及离子强度等对大豆蛋白萃取率的影响。实验结果表明,该微乳体系萃取大豆蛋白的优化工艺条件为:大豆粉与微乳液的质量体积比1∶10,P204在油相中浓度0.8 mol/L,NaOH的浓度1.25 mol/L,萃取时间15 min,外水相pH值5,萃取率可达88.48%。通过调节水相pH和离子强度可实现大豆蛋白的萃取和反萃取。     

Analysis of etimicin sulfate by liquid chromatography with pulsed amperometric detection

A new method for determination of etimicin's (ETM) purity and content is developed by liquid chromatography (LC) and pulsed amperometric detection (PAD). A reversed-phase ion-pair LC method with pulsed amperometric detection on a gold electrode after post-added NaOH is described. The mobile phase consisted of an aqueous solution containing 0.033 mol L(-1) oxalic acid, 0.012 mol L(-1) heptafluorobutyric acid, and 210 mL L(-1) acetonitrile with pH 3.40 adjusting by dilute NaOH solution. The total analysis time was not more than 30 min. The effects of the different chromatographic parameters on the separation were also investigated. A number of commercial samples of etimicin sulfate were analyzed using this method.     

有机溶剂/缓冲液两相体系中全细胞催化拆分环氧氯丙烷

研究了有机溶剂/缓冲液两相体系中重组大肠杆菌E.coli BL21 (DE3)全细胞水解动力学拆分外消旋环氧氯丙烷制备(R)-环氧氯丙烷的过程.结果表明,最适反应条件为:最适有机溶剂异辛烷与缓冲液的体积比7:3,最适缓冲液pH 8.0,底物浓度574mmol/L,全细胞加入量0.07g湿菌体/ml溶液,温度30℃.在此条件下于1L反应器中反应45min,(R)-环氧氯丙烷的摩尔产率、光学纯度和时空产率分别达到37.5%,99.3%ee和0.286mol/(L·h).与单一水相体系相比,异辛烷/缓冲液两相体系中底物浓度和(R)-环氧氯丙烷时空产率分别提高了55.2%和98.6%.     

柱前衍生-超高效液相色谱法测定鱼卵中的17种氨基酸

建立了一种快速、灵敏的柱前衍生-超高效液相色谱-光电二极管阵列检测器(UPLC-PDA)测定史氏鲟(Acipenser schrenckii)、达氏鳇(Huso dauricus)和小体鲟(Acipenser ruthenus)鱼卵中17种氨基酸含量的方法。采用6.0 mol/L的盐酸水解鱼卵,提取液经低压浓缩、碱性中和,然后以6-氨基喹啉-N-羟基琥珀酰亚胺基氨基甲酸酯(AQC)为衍生试剂在pH 8.8硼酸盐缓冲溶液中衍生化。采用的色谱分离柱为Waters BEH C18柱(100 mm×2.1 mm, 1.7 μm),流动相为30 mmol/L乙酸铵水溶液(pH 3.5)和乙腈(含0.15%(v/v)甲酸及30 mmol/L乙酸铵),梯度洗脱,流速为0.7 mL/min,在260 nm波长下检测。17种氨基酸在5.0～1000 μmol/L浓度范围内,峰面积与浓度之间的线性关系良好(r2≥0.9950)。以标准加入法测定回收率和相对标准偏差(RSD),在100、500、750 μmol/L的添加水平下,17种氨基酸的平均回收率为75.4%～107.3%, RSD为2.19%～12.3%。以3倍信噪比(S/N＞3)计方法的检出限,17种氨基酸的检出限为0.94～4.04 μmol/L。应用该方法检测了3种鲟鳇鱼鱼卵中的17种氨基酸含量。结果表明,该方法简便、准确、快速、可靠。     

PbS纳米粒子与全共轭高分子的自组装膜原位复合及其光电转换性质

无机纳米粒子因其在催化、磁学、光子学等方面的特殊性质而越来越受到关注,纳米粒子粒径及分布可以人为控制,由此能够改变与有机聚合物所形成的纳米复合材料性能,在各种无机纳米粒子／有机聚合物复合材料制备方法中,纳米反应器(Nanoreactor)技术正日益受到关注,与常规的作为化学反应特定场所的化学反应器不同,纳米反应器不是一般的具体的机械设备,     

水溶性钯配合物催化柠檬醛的选择加氢反应研究 Ⅰ.反应条件的影响

研究了在水／有机物两相体系中水溶性钯－膦配合物催化柠檬醛的加氢反应．考察了反应温度、氢气压力、底物和催化剂浓度、反应时间、水相ｐＨ值等对该反应的影响，并与几种柠檬醛衍生物的加氢结果进行了比较．发现仅用蒸馏水作水相，则主要产物是二氢香茅醛（＞９３％）；而水相中加入Ｎａ２ＣＯ３后，则主要产物为香茅醛（９７％），且加氢速度比同样条件下使用Ｐｄ／Ｃ催化剂快得多．     

高碳铬铁在氢氧化钠水溶液中电化学氧化过程

铬铁电化学氧化法是一种新的制备铬酸钠的方法,然而高碳铬铁在NaOH水溶液中的电化学氧化过程尚不明确。 采用循环伏安法(CV)、稳态极化法(LSV)等电化学测试方法对金属铬、高碳铬铁在NaOH水溶液中的电化学氧化过程进行研究,通过扫描电子显微镜(SEM)、能量散射谱(EDS)和X射线光电子能谱(XPS)对高碳铬铁电解后固相产物表征,判断固相产物的组成。 结果表明,高碳铬铁不同于金属铬的电氧化过程,它在NaOH溶液中通过Cr(0)→Cr(Ⅵ)的电氧化方式生成铬酸钠,中间产物Cr(OH)₃和Fe(0)发生电化学反应生成稳定的FeCr₂O₄。 随着NaOH浓度的增加,电势较低时,受高碳铬铁中Fe(0)的影响,高碳铬铁容易在NaOH水溶液中发生钝化;当电势足够正时,钝化膜溶解,生成铬酸钠、氢氧化铁和亚铬酸亚铁,同时,阳极表面有氧气析出。 高碳铬铁电化学氧化制备铬酸钠的适宜条件:碱浓度≥2 mol/L,阳极电势≥1.6 V(vs.SCE)。     

磷酸三丁酯/正辛醇络合萃取对氯苯酚

以对氯苯酚稀溶液为研究对象,以正辛醇为稀释剂,研究了萃取剂种类及其浓度、水相平衡pH、对氯苯酚初始浓度等因素对萃取分配比的影响,并用NaOH对其负载溶质的有机相进行反萃.结果表明,络合萃取对处理高浓度对氯苯酚废水具有优势;磷酸三丁酯(TBP)的浓度和体系的pH是影响络合萃取的关键因素;采用NaOH对有机相进行反萃,当NaOH浓度为0.5mol/L时反萃率达到98.55%.红外光谱分析表明,TBP萃取对氯苯酚基于氢键作用机理.     

Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10~(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1％ (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1％ HNO_3(3.0 mL/min). A good precision(1.6％ for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h~(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.