偶氮洋红G-SDS体系共振光散射法测定蛋白质

在十二烷基磺酸钠存在下及pH 1．98的Brittion-Robinson介质中,蛋白质与偶氮洋红G作用形成复合物,使最大波长421nm的共振光散射光谱得到加强,根据其共振光散射的增强程度,可定量测定蛋白质。十二烷基磺酸钠的加入,使灵敏度提高2．7倍。牛血清白蛋白、γ-球蛋白的线性范围分别为0.04～1．6、0．12～3．8mg／L,检出限分别为5．3、8．5μg/L。用于人血清、牛奶、豆浆、尿液中总蛋白质的测定,结果与经典的考马斯亮蓝法一致。     

表面活性剂和染料探针共振光散射法测定蛋白质

在pH为2.1的Britton-Robinson缓冲溶液中,蛋白质与十二烷基磺酸钠和吖啶红作用形成聚集体,导致体系产生较大的共振散射光(RLS)强度,并且RLS的增强程度与蛋白质的浓度呈线性关系,据此建立了测定蛋白质含量的方法.人血清白蛋白(HSA)和牛血清白蛋白(BSA)分别在0.03～3.0μg/mL和0.2～7.0μg/mL的浓度范围内与增强的共振光散射强度有良好的线性关系,相应的检测限分别为0.0119μg/mL和0.026μg/mL.对体系的反应机理进行了讨论.将方法用于人血清中蛋白质含量的测定,并将分析结果与考马斯亮蓝法进行了对照.t-检验证明,两种方法无显著性差异.     

考马斯亮蓝-SLS体系共振瑞利散射法测定蛋白质

研究了考马斯亮蓝与蛋白质的结合反应。在十二烷基磺酸钠的存在下,于pH1.6的酸性介质中,蛋白质与考马斯亮蓝可形成复合物,使最大波长351 nm的共振光散射光谱得到加强,据此,用于蛋白质的定量测定。十二烷基磺酸钠的加入,可使灵敏度提高3.2倍。本法测定牛血清白蛋白、人血清白蛋白、卵蛋白、γ-球蛋白的线性范围分别为:0.04~0.8、0.03~0.5、0.04~1.00、.06~1.2 mg/L,检出限分别为:6.3、4.7、7.9、9.2μg/L。已用于人血清、牛奶、豆浆、尿液中蛋白质的测定,所得结果与经典的考马斯亮蓝法一致。     

同多酸和染料探针共振光散射法测定蛋白质

在酸性条件下,铬黑T、钼酸铵与蛋白质形成聚合物,使体系的共振光散射明显增强。据此建立了利用共振光散射技术测定总蛋白含量的新方法。在最佳条件下,体系的最大散射峰位于555nm处。共振光散射增强的程度与蛋白质的浓度呈良好的线性关系。牛血清白蛋白和人血清白蛋白的线性范围分别为0.20～10.0μg/mL和0.10～8.0μg/mL,检出限为0.050μg/mL和0.039μg/mL。方法已用于人血清样品的分析,并与考马斯亮蓝的测定结果进行了比较,两者无显著性差异。     

盐酸苯海拉明和曙红B体系的光谱研究及其分析应用

在pH 3.1的Britton-Robison缓冲介质中,曙红B与盐酸苯海拉明借助静电引力和疏水作用力形成离子缔合物,使最大散射波长为364 nm处的共振光散射光谱得到加强。研究了体系的共振光散射光谱和紫外-可见吸收光谱。建立了一种测定盐酸苯海拉明的新方法。体系共振光散射增强的强度与盐酸苯海拉明的质量浓度在0.5~11.2 mg/L范围内呈现良好的线性关系,方法的检出限为41.7μg/L。可用于药物中盐酸苯海拉明的测定。     

虎红-牛血清白蛋白共振光散射光谱研究及其分析应用

基于在pH3.0的BR缓冲溶液中蛋白质的加入使虎红的共振光散射信号增强,建立了一种蛋白质测定的新方法.详细地探讨了pH、染料用量、表面活性剂、离子强度、共存物质等对信号的影响.牛血清白蛋白浓度在0～4.0μg/mL范围内与体系散射强度呈线性关系,检出限为0.01718μg/mL.该方法用于合成样品中牛血清白蛋白的测定,...     

溴代十六烷基三甲基铵敏化吡罗红B-核酸作用的共振光散射增强法测定核酸

基于表面活性剂溴代十六烷基三甲基铵（CTMAB）对吡罗红B-核酸作用的共振光散射增强效应有敏化作用,建立了一种高灵敏测定核酸的新方法。在pH7．4时,吡罗红B在328nm处的共振光散射的增强与核酸浓度有良好的线性关系。在最佳实验条件下,对小牛胸腺DNA（ct-DNA）、鲱鱼精DNA（fs-DNA）、酵母RNA（yeast—RNA）测定的线性范围分别为0．0～1．2mg／L、0．0～0．8mg／L和0．04～1．4mg／L。检出限分别为6．1μg／L、11．2μg／L和8．6μg／L。该法简便、快捷、重现性好,对合成样品进行了测定,结果令人满意。     

蛋白质-四羧基铜酞菁体系的共振散射行为及其分析应用

在pH 3.0的Clark-Lub's 缓冲溶液中,蛋白质与四羧基铜酞菁(CuPc(COOH)4)作用,使体系的共振光散射增强,在λ=389 nm处光散射强度最大.增强作用的强弱与蛋白质的含量成正比,据此建立了共振光散射测定蛋白质的新方法.此方法对牛血清白蛋白(BSA)、人血清白蛋白(HSA)、免疫球蛋白G(IgG)、鱼精蛋白(Protamine)、血清总蛋白(TP)的测定范围分别为0.05～1.60 mg/L、 0.025～1.60 mg/L、 0～1.45 mg/L、 0.1～1.50 mg/L、 0～1.60 mg/L,相应检出限分别为1.12×10-2 mg/L、 1.11×10-2 mg/L、 1.95×10-2 mg/L、 3.61×10-3 mg/L、 4.34×10-3 mg/L.方法应用于实际人血清样品中总蛋白的测定,结果与考马斯亮蓝法基本一致.     

等色吸收荧光猝灭法快速测定食品中苏丹红Ⅰ

在乙醇介质中, 强荧光染料吖啶的荧光波长478 nm与苏丹红Ⅰ的吸收光波长480 nm十分接近, 由于等色性苏丹红Ⅰ能够有效吸收吖啶发出的荧光, 使吖啶在激发波长λex=410 nm、荧光波长λem=478 nm处荧光猝灭, 依此建立了荧光猝灭测定苏丹红Ⅰ的新方法. 该方法快速、简便, 其线性范围为3.72～37.2 mg/L, 方法检出限为1.1 mg/L. 用于辣椒、辣椒酱食品中痕量苏丹红Ⅰ的测定. 6次平行测定, 相对标准偏差为0.8%～2.7%, 加标回收率为89.5%～104.0%.     

甲苯咪唑共振散射法用于蛋白质的痕量检测

建立了血液中痕量蛋白的共振散射(RLS)光谱分析方法。盐酸-甲苯咪唑(MEB)-牛血清白蛋白(BSA)体系的最大共振散射(RLS),二级散射(SOS),倍频散射(FDS)波长分别位于296、500和340nm。3种散射增强(ΔI)在一定范围内与蛋白质浓度成正比,方法线性范围分别是RLS为0.4～2.0 mg/L、SOS为0.4～2.4 mg/L;FDS为0.4～2.0 mg/L;检出限分别为1.059(RLS)、1.324(SOS)、4.743μg/L(FDS)。方法可用于血清中蛋白质的测定,回收率在97.9%～104.6%之间。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.