Chelate synthesis of 2,2′-bipyridin-4-one

A method for the synthesis of 2,2′-bipyridin-4-one from 4-amino-4-(2-pyridyl)-but-3-en-2-onevia its diphenylboron, chelates was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2071–2073, November, 1997.     

血管紧张素转换酶与抑制肽结合模式的分子动力学研究

应用分子模拟方法研究了血管紧张素转换酶(Angiotensin-converting enzyme,ACE)C端结构域(C-domain)与两种抑制肽(RIGLF/AHEPVK)的结合机制,预测了两个体系的结合模式,提出在C-domain-RIGLF中His353,Asp377,Asp453,Phe457,His513,Tyr523和Phe527为RIGLF主要结合残基,而在C-domainAHEPVK中Gln281,His353,Ser355,Glu384,Lys511,His513和Tyr523等残基起关键作用.应用结合自由能计算比较了两个体系的结合能力,结果表明,RIGLF和AHEPVK均与C-domain活性位点残基存在较强作用,且AHEPVK对C-domain的结合能力较强,与实验结果一致.     

重组内切纤维素酶Fpendo5A转化三七总皂苷

从嗜热细菌基因组中克隆到1个新的纤维素酶基因,并在大肠杆菌中进行了高效可溶性表达,粗酶液经镍柱亲和层析进行分离纯化.利用快速分离液相色谱-四极杆飞行时间质谱联用仪(RRLC/Q-TOF-MS)对重组内切纤维素酶Fpendo5A转化三七总皂苷的产物结构进行了鉴定,并进一步阐明其转化机制.结果表明,该酶的最适反应温度和pH值分别为80℃和5.5.Fpendo5A能够催化三七总皂苷中的主要皂苷成分,即Ra_1,Rb_1,Rc,Rd和Rg_3的侧链糖基的水解反应,但对于不同的皂苷底物,Fpendo5A选择性催化的侧链糖基类型不同.经鉴定,Fpendo5A转化Ra_1,Rb_1,Rc,Rd和Rg_3的转化产物分别为Rb_2,GypⅩⅦ,CMC_1,F_2和Rh_2.由此可见,Fpendo5A通过水解Rb_1,Rc,Rd和Rg3的C3位的β-(1,2)糖苷键分别生成GypⅩⅦ,CMC1,F2和Rh2.在转化Ra_1时,Fpendo5A通过水解Ra_1的C20位的α-(1,4)木糖苷键生成Rb2.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.     

聚吡咯/多壁碳纳米管及其聚氨酯导电复合材料的制备和性能

以羧基化多壁碳纳米管(MWCNTs)做模版剂,采用化学氧化法将吡咯(Py)在羧基化MWCNTs表面聚合制备PPy/MWCNTs导电材料,将其添加到溶剂型聚氨酯(PU)溶液中制备了PPy/MWCNTs/PU导电复合材料,研究了Py用量对PPy/MWCNTs及其PU复合材料性能的影响.研究表明,随Py用量的增加,PPy/MWCNTs的长度不变,管径增大,sp~2和sp~3杂化C含量先提高后减少,N的掺杂梯度降低,PPy/MWCNTs的导电率高于羧基化MWCNTs和PPy.当Py用量为羧基化MWCNTs的20%时,其导电率最大.PPy/MWCNTs中N元素的掺杂程度及其管径变化是引起PPy/MWCNTs/PU复合材料的性能不同的主要原因.增加Py用量,MWCNTs中亲水的羧基因对PPy掺杂而消耗,相同导电材料用量时纳米导电粒子数目相对减少,PPy/MWCNTs/PU复合材料的耐水性能提高,定向应力、储能模量和玻璃化温度降低,导电率先增加后减小.当Py用量为羧基化MWCNTs的15%时,导电率最大.     

弱凝胶钻井液成胶剂AM/AMPS/OA_8的合成与表征

针对水平井、大斜度井钻井过程中井眼润滑性、岩屑携带以及钻井速度的影响等问题,通过合理的分子设计,以丙烯酰胺(AM)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和实验室自制疏水单体丙烯酸正辛醇OA_8为原料,利用胶束聚合法,制备了一种弱凝胶成胶剂AMAMPSOA_8,其结构经1H NMR和IR表征。以AMAMPSOA_8在低剪切速率下的表观粘度为指标设计正交试验,确定最优反应条件为:AM与AMPS摩尔配比为4.8∶1,引发剂用量为单体总质量的0.04%,疏水单体浓度为0.75%,于70℃反应9 h。该条件下,0.5%AMAMPS0A_8聚合物溶液在低剪切速率3 r·min~(-1)下表观粘度可达23 680 mPa·s。利用热分析仪、高温滚子炉、高温高压流变仪对产物性能进行了研究。研究表明:AMAMPSOA_8的抗温性能可达160℃;聚合物溶液体系有明显的触变性,在40 min后溶液切力增加幅度变缓。     

Comparison of Gasoline-Ranged <Emphasis Type="Italic">n</Emphasis>-Alkanes Conversions Using Dielectric Barrier Discharge: A Kinetic Study

Here, we compared the conversion of gasoline-ranged n-alkanes (C₆–C₉) using dielectric barrier discharge. For an energy density of ~68 J/L and an initial n-alkane concentration of ~230 ppm, when carbon number increased from 6 to 9, the energy efficiency of n-alkane conversion increased from 117 to 240 mmol/kWh, CO _x selectivity decreased from 46 to 20%, and ozone concentration increased from 216 to 240 ppm. The effect of energy density and initial n-alkane concentration were also investigated. The understanding of initial step of conversion was greatly aided by a proposed kinetic model. The pathways of consecutive reactions from the initiation to products were also discussed.     

Syntheses,crystal structures,electrochemical and photocatalytic properties of two mixed-ligand cobalt(II) coordination polymers based on flexible bis(2-methylbenzimidazole) dicarboxylic acid ligands

Two Co(II) coordination polymers (CPs), namely [Co(L)(tp)] _n (1) and [Co(L)_0.5(tbip)·H₂O] _n (2), (L = 1,6-bis(2-methylbenzimidazolyl) hexane, H₂tp = terephthalic acid, H₂tbip = 5-tert-butyl isophthalic acid), were hydrothermally synthesized and characterized by physicochemical and spectroscopic methods. CP 1 possesses a 2D (4,4) corrugated layer structure, which further extends into a 3D supramolecular framework by π–π stacking interactions, while CP 2 has a 1D ladder-like chain structure and combines into a 2D layer via O–H?O hydrogen-bonding interactions. The thermal stabilities, luminescence and electrochemical properties of both CPs, as well as photocatalytic activities for the decomposition of methylene blue, were presented. The photocatalytic mechanism was investigated by introducing t-butyl alcohol, EDTA-2Na and benzoquinone as ?OH, (hole)⁺ and ·O^2? scavengers, respectively.     

The role of MgO in the thermal behavior of MgO–silica fume pastes

The compounds of MgO–silica fume (SF) pastes constitute magnesium silicate hydrate (M–S–H) in a new generation of basic castables. However, Mg(OH)₂ is a common reaction product with the formation of M–S–H. This study aims to reduce the formation of Mg(OH)₂ in MgO–SF pastes. In this study, MgO powders were prepared by calcining magnesite at different temperatures and then mixed with SF and water to prepare MgO–SF pastes. The properties of MgO powders were characterized, and the pH values in the pore solutions of MgO–SF pastes were measured. The MgO–SF pastes cured for 90 days were calcined at 500, 700, 900 and 1200 °C, and the microstructure was characterized afterward. The results showed that both the reactivity of MgO powders and the pH value of the pore solution of MgO–SF pastes were diverse, which essentially depended on the grain sizes and the crystalline degree of MgO. Increasing the calcination temperature of MgO was beneficial to reduce the formation of Mg(OH)₂ or even stop it when using MgO calcined at 1450 °C. Enstatite and forsterite formed for all MgO–SF pastes after calcination. However, the microstructure of MgO–SF paste with MgO calcined at 1450 °C was denser than others. MgO–SF pastes were suitable for the new-generation refractory castables. Notably, using MgO calcined at 1450 °C is more appropriate.