乙基罗丹明B与大豆甙的显色反应及其应用研究

在 p H1 0 .5的 NH3- NH4 Cl缓冲溶液中 ,在聚乙烯醇存在下 ,乙基罗丹明 B与大豆甙形成 1∶ 1有色缔合物。其最大吸收波长为 5 65 nm,表观摩尔吸光系数为2 .0 1× 1 0 4 L· mol- 1· cm- 1,大豆甙在 1 .6～ 6.2 mg/L范围内符合比耳定律。方法用于大豆提取液中大豆异黄酮甙的测定 ,结果满意     

高质量AlPO4-5分子筛单晶的螯合剂法合成与表征

考察了几种螯合剂对AlPO4-5分子筛单晶合成的影响，结果表明，用邻苯二酚，乙酰丙酮，水杨醛为螯合剂可以得到高质量的，尺寸较大的分子筛单晶，其作用机理可能与它们加入到分子筛合成体系中，改变了溶胶中铝的配位数或产生了铝的螯合物有关。     

CBS法合成光学活性二茂铁基醇

以非天然氨基酸合成的手性β-氨基醇(4a～4c)为催化剂，用于不对称硼烷还原反应来合成光学活性的二茂铁基醇(1a～1e)，对映体过量值高达96%。     

KF/Al2O3催化合成2-甲基-3-(3,4-亚甲二氧基苯基)丙烯醛

缩合;催化剂;洋茉莉醛;KF/Al2O3催化合成2-甲基-3-(3;4-亚甲二氧基苯基)丙烯醛     

The practice for eight-year operation of the cobalt-60 irradiation facility at Beijing Radiation Application Research Center

The radiation facility was made by Sulzer Company in Switzerland. The designed capacity is 3.7 × 10¹⁶Bq( 1MCi) and 12.21 × 10¹⁵Bq(330kCi)of Cobalt -60 source was loaded at the first phase. Current cobalt -60 source-loading is 2.4 × 10¹⁶Bq(650kCi). The equipment assembling and installation regulating and testing were completed at the end of 1988. The facility was put into commissioning in 1989. It operates 7000–8000 hours per year. The facility has been utilized to carry out many research work and irradiate many kinds of items. Lots of economical benefits have been gained since then. Now it is becoming a radiation processing model base in China. This paper summarized the strong and weak points of the design of the facility through in eight years' practice and analysed the economical benefits.     

Ionic Liquid‐Hemoglobin‐Carbon Paste Composite Bioelectrode and Its Electrocatalytic Activity

A new carbon ionic liquid paste bioelectrode was fabricated by mixing hemoglobin (Hb) with graphite powder, ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF₄) and liquid paraffin homogeneously. Nafion film was cast on the electrode surface to improve the stability of bioelectrode. Direct electrochemistry of Hb in the bioelectrode was carefully investigated. Cyclic voltammetric results indicated that a pair of well‐defined and quasi‐reversible electrochemical responses appeared in pH 7.0 phosphate buffer solution (PBS), indicating that direct electron transfer of Hb was realized in the modified electrode. The formal potential (E^0′) was calculated as ?0.316 V (vs. SCE), which was the typical characteristic of the electrochemical reaction of heme Fe(III)/Fe(II) redox couple. Based on the cyclic voltammetric results the electrochemical parameters of the electrode reaction were calculated. This bioelectrode showed high electrocatalytic activity towards the reduction of trichloroacetic acid (TCA) with good stability and reproducibility.     

Thermal and pH‐sensitive gold nanoparticles from H‐shaped block copolymers of (PNIPAM/PDMAEMA)‐b‐PEG‐b‐(PNIPAM/PDMAEMA)

Well‐defined H‐shaped pentablock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM), poly(N,N‐dimethylaminoethylacrylamide) (PDMAEMA), and poly(ethylene glycol) (PEG) with the chain architecture of (A/B)‐b‐C‐b‐(A/B) were synthesized by the combination of single‐electron‐transfer living radical polymerization, atom‐transfer radical polymerization, and click chemistry. Single‐electron‐transfer living radical polymerization of NIPAM using α,ω azide‐capped PEG macroinitiator resulted in PNIPAM‐b‐PEG‐b‐PNIPAM with azide groups at the block joints. Atom‐transfer radical polymerization of DMAEMA initiated by propargyl 2‐chloropropionate gave out α‐capped alkyne‐PDMAEMA. The H‐shaped copolymers were finally obtained by the click reaction between PNIPAM‐b‐PEG‐b‐PNIPAM and alkyne‐PDMAEMA. These copolymers were used to prepare stable colloidal gold nanoparticles (GNPs) in aqueous solution without any external reducing agent. The formation of GNPs was affected by the length of PDMAEMA block, the feed ratio of the copolymer to HAuCl₄, and the pH value. The surface plasmon absorbance of these obtained GNPs also exhibited pH and thermal dependence because of the existence of PNIAPM and PDAMEMA blocks. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

In silico prediction and screening of γ‐secretase inhibitors by molecular descriptors and machine learning methods

γ‐Secretase inhibitors have been explored for the prevention and treatment of Alzheimer's disease (AD). Methods for prediction and screening of γ‐secretase inhibitors are highly desired for facilitating the design of novel therapeutic agents against AD, especially when incomplete knowledge about the mechanism and three‐dimensional structure of γ‐secretase. We explored two machine learning methods, support vector machine (SVM) and random forest (RF), to develop models for predicting γ‐secretase inhibitors of diverse structures. Quantitative analysis of the receiver operating characteristic (ROC) curve was performed to further examine and optimize the models. Especially, the Youden index (YI) was initially introduced into the ROC curve of RF so as to obtain an optimal threshold of probability for prediction. The developed models were validated by an external testing set with the prediction accuracies of SVM and RF 96.48 and 98.83% for γ‐secretase inhibitors and 98.18 and 99.27% for noninhibitors, respectively. The different feature selection methods were used to extract the physicochemical features most relevant to γ‐secretase inhibition. To the best of our knowledge, the RF model developed in this work is the first model with a broad applicability domain, based on which the virtual screening of γ‐secretase inhibitors against the ZINC database was performed, resulting in 368 potential hit candidates. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

A new biomarker of protein oxidation degree and site using angiotensin as the target by MS

Hydroxyl radicals generated from Fenton reaction were used to damage the angiotensin. The oxidative damage degree and sites of peptides were measured by HPLC–MS and MS/MS. Experimental results proved that the oxidative damage degree increased with longer reaction time. The results also showed that the side chains of phenylalanine and tyrosine in angiotension can be attacked by hydroxyl radicals to form the oxidative products. A new strategy was established to monitor the oxidative degree and sites of peptides and laid the foundation for protein oxidation. This method can be used to investigate the mechanism of protein oxidative damage caused by oxidative stress which is induced by environmental pollutants and physiological activities. There will also be a wide application in the research of pathogenesis of some disease related to oxidative stress.     

4,4′‐Bis(2,2,2‐trifluoroethoxymethyl)‐2,2′‐bipyridine

As part of a homologous series of novel polyfluorinated bipyridyl (bpy) ligands, the title compound, C₁₆H₁₄F₆N₂O₂, contains the smallest fluorinated group, viz. CF₃. The molecule resides on a crystallographic inversion centre at the mid‐point of the pyridine C_ipso—C_ipso bond. Therefore, the bpy skeleton lies in an anti conformation to avoid repulsion between the two pyridyl N atoms. Weak intramolecular C—H...N and C—H...O interactions are observed, similar to those in related polyfluorinated bpy–metal complexes. A π–π interaction is observed between the bpy rings of adjacent molecules and this is probably a primary driving force in crystallization. Weak intermolecular C—H...N hydrogen bonding is present between one of the CF₃CH₂– methylene H atoms and a pyridyl N atom related by translation along the [010] direction, in addition to weak benzyl‐type C—H...F interactions to atoms of the terminal CF₃ group. It is of note that the O—CH₂CF₃ bond is almost perpendicular to the bpy plane.