甾体化合物D环结构对4-位二甲基化反应和3-位氧甲基化反应选择性的远程效应

目的在有4-烯-3-酮结构的甾体化合物4-位上引入二甲基。方法以7个带有4-烯-3-酮结构的甾体化合物为底物,按文献方法以相同的反应条件与碘甲烷-叔丁醇钾-叔丁醇反应系统反应。结果4个底物反应结果和文献一致,顺利得到了4-位二甲基化的产物,而另外3个底物则以高收率转化成为3-位氧甲基化的产物。结论7个甾体底物A、B、C3个环的结构基本一致,只是D环的结构不同,所以这7个化合物的不同反应结果表明甾体D环结构通过远程效应对4-位二甲基化和3-位氧甲基化反应的选择性产生了影响。

EDC/NHS交联对胶原物理化学性能的影响

为了提高胶原的物理化学性能,采用1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺(EDC)和N-羟基琥珀酰亚胺(NHS)交联剂对胶原进行交联,考察了不同交联剂浓度对胶原物理化学性能的影响,并通过红外、差示扫描量热分析(DSC)、吸水率、膨胀动力学、抗酶解性能、扫描电镜(SEM)等技术手段对胶原交联前后的性能进行表征.研究结果表明,胶原经EDC/NHS交联后,热稳定性、形态稳定性增强,抵抗酶解的能力显著增加,胶原的显微结构由交联前的无序状态变为紧密有序的结构.说明EDC/NHS交联可有效改善胶原的物理化学性能.

恶性疟原虫合子/动合子表面25蛋白自身偶联条件的优化及其聚体蛋白的制备

目的探讨影响恶性疟原虫合子/动合子表面25蛋白(25 k Da Plasmodium falciparum sexual stage protein,Pfs25)偶联的因素,优化Pfs25蛋白的偶联反应条件,制备具有免疫原性的Pfs25纯化聚体蛋白。方法通过对偶联反应时Pfs25蛋白浓度、偶联反应的酸碱度、不同的缓冲液及偶联试剂添加方式的探索,考察不同反应条件对Pfs25蛋白偶联的影响。凝胶过滤层析纯化Pfs25偶联反应产物,双抗体夹心ELISA和SDS-PAGE对凝胶柱洗脱液进行检测,Western blot检测纯化的Pfs25聚体蛋白。结果 Pfs25蛋白偶联反应选择1/15 mol/L Na_2HPO_4-KH_2PO_4为偶联缓冲液,反应体系在pH 5.6～6.0时偶联效果更好,而Pfs25蛋白反应质量浓度为25 mg/m L时可获得最佳的Pfs25偶联效率(68.67%),凝胶过滤层析法获得Pfs25聚体蛋白,经双抗体夹心ELISA和Western blot检测,形成的Pfs25聚体蛋白保持了与Pfs25蛋白相同的抗体结合能力。结论优化了Pfs25蛋白最佳偶联反应条件,获得具有免疫原性的Pfs25纯化聚体蛋白。在形成Pfs25聚体中,以二聚体(Pfs25)2为主要形式,兼有少量三聚体(Pfs25)3和四聚体(Pfs25)4。

Effect of NH_4^+ exchange on CuY catalyst for oxidative carbonylation of methanol

NaY and ion exchanged NaNH4Y zeolite with NH4NO3 were used as the support to prepare CuY cata‐lysts by a high temperature anhydrous interaction between the support and copper （II） acety‐lacetonate Cu（acac）2. The catalysts were used for the oxidative carbonylation of methanol to dime‐thyl carbonate （DMC） at atmospheric pressure. The textural and acidic properties of NaNH4Y zeolite and the CuY catalysts were investigated by X‐ray diffraction, scanning electron microscopy, N2 ad‐sorption‐desorption, temperature programmed reduction of H2, X‐ray photoelectron spectroscopy and temperature programmed desorption of NH3. With increasing NH4NO3 concentration, the NH4＋exchange degree increased while the crystallinity of the zeolite remained intact. Crystalline CuO was formed when the NH4＋exchange degree of NaNH4Y was low, and the corresponding CuY catalyst showed low catalytic activity. With increasing of the NH4＋exchange degree of NaNH4Y, the content of surface bound Cu＋active centers increased and the catalytic activity of the corresponding CuY catalyst also increased. The surface bound Cu＋content reached its maximum when the NH4＋ex‐change degree of NaNH4Y reached towards saturation. The CuY exhibited optimal catalytic activity with 267.3 mg/（g·h） space time yield of DMC, 6.9%conversion of methanol, 68.5%selectivity of DMC.

Binding tendency with oligonucleotides and cell toxicity of cetyltrimethyl ammonium bromide-coated single-walled carbon nanotubes

Functionalized carbon nanotubes （CNTs） were made for the delivery of genes and drugs and CNT-based biosensors. The basis of CNTs is for binding with biomolecules in biomedical applications. The binding tendency with small interfering RNA oligonucleotides and cytotoxicity of cetyltrimethyl ammonium bromide （CTAB）-coated single-walled carbon nanotubes （SWNTs） were studied. The field emission scanning electron microscopy and transmission electron microscopy results show that a SWNT suspension in CTAB solution was well-dispersed and stable. CTAB is the cross-linker between SWNTs and oligonucleotides. The CTAB-coated SWNTs have less cytotoxicity to human umbilical vein endothelial cells than single SWNTs and the cytotoxicity of CTAB-coated SWNTs depended on the concentration of CTAB-coated SWNTs.

柠檬酸-EDC/NHS胶原凝胶修复破损纤维环

目的探讨利用柠檬酸-EDC/NHS一型胶原凝胶修复纤维环损伤,减缓椎间盘退变的效果。方法使用鼠尾肌腱一型胶原凝胶,柠檬酸(CA)、1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺(EDC)和N-羟基琥珀酰亚胺(NHS)作为交联剂,将一型胶原凝胶与交联剂按不同质量比混合制成一型胶原混合凝胶。建立鼠尾椎间盘纤维环穿刺模型。清洁级SD大鼠48只,分为假手术组(n=8)、CA-EDC/NHS凝胶(CA6)治疗组(n=10)、CA-EDC/NHS凝胶(CA3)治疗组(n=10)、EDC/NHS凝胶(CA0)治疗组(n=10)、穿刺未治疗组(n=10)。分别于1、2、4周行小动物X摄片、小动物MRI检查,统计分析不同时间点椎间隙高度系数、髓核像素值及Pfirrmann分级,于第4周时将大鼠处死行组织学切片观察。结果 4周后,CA-EDC/NHS凝胶(CA6)治疗组的鼠尾椎间盘对比假手术组仅发生了轻微的退变,基本保持了髓核组织的完整性,在椎间盘高度系数(均数79%)、髓核像素值(均数126.9)和Pfirrmann分级结果(平均1.3分)均优于其余两个治疗组和穿刺未治疗组(P<0.05)。CA-EDC/NHS凝胶(CA6)治疗组的组织学观察显示,针道的周围没有发现炎性细胞浸润和瘢痕组织,针道尽头可见一团凝胶状物质在断裂的纤维环组织之间形成了桥接使其闭合。结论柠檬酸-EDC/NHS胶原凝胶具有一定的修复破损纤维环,减缓椎间盘退变的能力,并且与柠檬酸剂量存在相关性。

Modification of ACFs by chemical vapor deposition and its application for removal of methyl orange from aqueous solution

Viscose activated carbon fibers （ACFs） were characterized using specific surface area, scanning electron modified with chemical vapor deposition （CVD）. The samples were microscopy （SEM）, pore size distribution and Fourier transform infrared spectroscopy （FTIR）. Batch adsorption experiments were carried out to investigate the adsorption behavior of modified ACFs for methyl orange（MO） from its aqueous solutions. The results show that the adsorption isotherms of MO onto modified ACFs well follows the Langmuir isotherm equation. The adsorption kinetics of MO can be well described by the pseudo second-order kinetic model. The adsorption process involves the intra-particle diffusion, but is not the only rate-controlling step. Thermodynamic parameters including AG, AH and AS were calculated, suggesting that the adsorption of MO onto modified ACFs is a spontaneous, exothermic and physisorption process. FTIR result indicates that the major adsorption mechanism of modified ACFs for MO is hydrogen bond.

导向农药

本文提出了导向农药的概念,从植物中可能存在的导向载体、导向载体与农药活性成分的拼接方法,导向农药用量、药害及导向载体的饱和性问题等方面论证了导向农药的可行性,阐明了导向农药的研究和应用意义。

(Z)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione protects rats from carbon tetrachloride-induced liver injury and fibrogenesis

AIM： To evaluate the hepatoprotective roles of （Z）- 5-（4-methoxybenzylidene）thiazolidine-2,4-dione （SKLB010） against carbon tetrachloride （CCI4）-induced acute and chronic liver injury and its underlying mecha- nisms of action.

Application of density-functional theory to studying methylation with dimethyl carbonate and dimethyl sulfate

The activities of dimethyl carbonate and dimethyl sulfate as a methylation reagent were studied by density- functional theory （DFT）. B3LYP/6-31G（d, p） methods were used to optimize the structures of dirnethyl carbonate and dimethyl sulfate and calculate theirs charge densities. Dimethyl sulfate is easier than dimethyl carbonate to react with a nucleophUic reagent. In dimethyl sulfate, the alkoxy carbons are the only reactive atomic nucleus because of steric hindrance. A nucleophilic reagent is more likely to react with carbonyl carbons than alkoxy carbons of dimethyl carbonate; in the presence of a Lewis acid, the phenyl nucleophilic reagent reacts with the Lewis acid first. Lewis acid increases the negative charge density of a nucleophUic reagent in polar solvent, and also incurs an accretion of steric hindrance. Polar solvent avails to ionize dimethyl carbonate and thus enables the reaction of methylation. The frequencies of transition state calculated by Gaussion 03 confirm the inferred reaction mechanism. The harvest rates of 4-methoxyphenol in the experiments of methylation reactions of hydroquinone with respectively dimethyl carbonate and dimethyl sulfate support the foregoing theortical conclusions.

Preparation of nitrogen-doped carbon nanoblocks with high electrocatalytic activity for oxygen reduction reaction in alkaline solution

The oxygen reduction reaction （ORR） is traditionally performed using noble‐metals catalysts, e.g. Pt. However, these metal‐based catalysts have the drawbacks of high costs, low selectivity, poor stabili‐ties, and detrimental environmental effects. Here, we describe metal‐free nitrogen‐doped carbon nanoblocks （NCNBs） with high nitrogen contents （4.11%）, which have good electrocatalytic proper‐ties for ORRs. This material was fabricated using a scalable, one‐step process involving the pyrolysis of tris（hydroxymethyl）aminomethane （Tris） at 800℃. Rotating ring disk electrode measurements show that the NCNBs give a high electrocatalytic performance and have good stability in ORRs. The onset potential of the catalyst for the ORR is-0.05 V （vs Ag/AgCl）, the ORR reduction peak potential is-0.20 V （vs Ag/AgCl）, and the electron transfer number is 3.4. The NCNBs showed pronounced electrocatalytic activity, improved long‐term stability, and better tolerance of the methanol crosso‐ver effect compared with a commercial 20 wt%Pt/C catalyst. The composition and structure of, and nitrogen species in, the NCNBs were investigated using Fourier‐transform infrared spectroscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy, and X‐ray diffraction. The pyroly‐sis of Tris at high temperature increases the number of active nitrogen sites, especially pyridinic nitrogen, which creates a net positive charge on adjacent carbon atoms, and the high positive charge promotes oxygen adsorption and reduction. The results show that NCNBs prepared by pyrolysis of Tris as nitrogen and carbon sources are a promising ORR catalyst for fuel cells.

Solubility of CO2 in Methanol, 1-Octyl-3-methylimidazolium Bis（trifluoromethylsulfonyl）imide, and Their Mixtures

Solubility data of carbon dioxide （CO2） （1） in methanol （2）, 1-octyl-3-methylimidazolium bis（trifluoro- methylsulfonyl）imide （[omim]＋[TfzN]-） （3）, and their mixtures （w3 = 0.2, 0.5, and 0.8） at temperatures 313.2 and 333.2 K and pressures up to 7.0 MPa were measured by a high-pressure view-cell technique. The solubility of CO2 in methanol （w3 = 0）, [omim]＋[Tf2N]- （w3 = 1.0） and their mixtures follows the order of （w3 = 0）〈（w3 = 0.2）〈 （w3 = 0.5）〈（w3 = 0.8）〈（w3 = 1.0） at the same temperature and pressure, while the magnitude of Henry＇s constants follows the reverse order at a given temperature, which is consistent with the COSMO-RS （conductor-like screen- ing for real solvents） calculation. The solubility data of CO2 in methanol and [omim]~[Tf2N]- are correlated with the Peng-Robinson equation of state, and the solubility of CO2 in the mixtures of methanol and [omim]＋[TfzN] can be well predicted based on the mole fraction average of methanol and [omim]＋[Tf2N] over the solubility of CO2 in pure methanol and [omim]＋[Tf2N] . The mixtures of methanol and [omim]＋[Tf2N]- may be used as physical solvents for capturing CO2 with high partial pressures since they combine the advantages of organic solvents and ionic liquids.

Cytotoxicity effect assessment of acid purified carbon nanotubes modified with cetyltrimethyl ammonium bromide

The cytotoxicities of single-walled carbon nanotubes （SWNTs） and acid purified single-walled carbon nanotubes （SWNT-COOH） were investigated by spectroscopic analysis. Cell viability and cell apoptosis were applied to assessing the cytotoxicity of SWNT-COOH, cetyltrimethyl ammonium bromide （CTAB） and acid purified carbon nanotubes modified with cetyltrimethyl ammonium bromide （SWNT-COOH/CTAB）. The results indicate that SWNTs are more toxic than SWNT-COOH. Concentration and time-curve analyses indicate that cytotoxicity of SWNT-COOH/CTAB is more related to the toxicity of the surfactant CTAB. The cytotoxicity effect of CTAB and SWNT-COOH/CTAB is acceptable at low concentrations （0.5-25μg/mL）. The cytotoxicity observation suggests that SWNT-COOH/CTAB can safely applied to biomedical field at low concentrations （0.5-25μg/mL）.

Ordered mesoporous carbon supported bifunctional PtM(M=Ru,Fe,Mo)electrocatalysts for a fuel cell anode

The deposition onto an ordered mesoporous carbon（OMC）support of well dispersed PtM（M = Ru,Fe,Mo）alloy nanoparticles（NPs）were synthesized by a direct replication method using SBA-15 as the hard template,furfuryl alcohol and trimethylbeneze as the primary carbon sources,and metal acetylacetonate as the alloying metal precursor and secondary carbon source.The physicochemical properties of the PtM-OMC catalysts were characterized by N2 adsorption-desorption,X-ray diffraction,transmission electron microscopy,X-ray absorption near edge structure,and extended X-ray absorption fine structure.The alloy PtM NPs have an average size of 2-3 nm and were well dispersed in the pore channels of the OMC support.The second metal（M）in the PtM NPs was mostly in the reduced state,and formed a typical core（Pt）-shell（M）structure.Cyclic voltammetry measurements showed that these PtM-OMC electrodes had excellent electrocatalytic activities and tolerance to CO poisoning during the methanol oxidation reaction,which surpassed those of typical activated carbon-supported PtRu catalysts.In particular,the PtFe-OMC catalyst,which exhibited the best performance,can be a practical anodic electrocatalyst in direct methanol fuel cells due to its superior stability,excellent CO tolerance,and low production cost.

Recent advances in fixation of CO_(2) into organic carbamates through multicomponent reaction strategies

Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.

Modeling and Kinetic Study on Absorption of CO2 by Aqueous Solutions of N-methyldiethanolamine in a Modified Wetted Wall Column

To get more accurate kinetic data of the absorption of CO2 into aqueous solution of N-methyldiethanolamine,a wetted wall column was modified to more uniformly distribute the liquid on the column surface and gas in the absorbing chamber and change the length of the column.The average liquid film thickness and the liquid-phase mass transfer coefficient were measured,and a correlation for the Sherwood number,Reynolds number and Schmidt number was obtained for the modified wetted wall column.The equilibrium concentrations in chemical reactions were calculated with a minor absolute error for calculating the rate constant more accurately.A mathe-matical model for the CO2 absorption was established based on the diffusional mass transfer accompanied with parallel reversible reactions,and the partial differential equation was solved by Laplace transform.An analytical ex-pression for the concentration of carbon dioxide as a function of time and penetration depth in liquid film and the average interphase mass transfer rate was obtained.This model was also used to calculate the rate constant for a second-order reaction,which was in good agreement with reported data.

Nitrate reduction by·CO_(2)^(-) from UV-activated HCOOH

To address the environmental and health hazards of nitrate(NO_(3)^(-))in water,a denitrification advanced reduction process(ARP)using only formic acid(HCOOH)activated by ultraviolet(UV)light was proposed.The efficiency,influencing factors,mechanism,and kinetics of the reduction were investigated through component analysis and radical detection.Results show that,after 90 min of UV illumination,the reduction and gas conversion ratios of 50 mg/L NO_(3)^(-)-N reach 99.9%and 99.8%,respectively,under 9 mM of C_(0)(HCOOH),pH=3.0,and N_(2) aeration.Meanwhile,96.7%of HCOOH is consumed and converted into gas.The NO_(3)^(-)-N conversion process includes the transformation to NO_(2)^(-)-N,followed by a further reduction to gas and a direct conversion into gas,introducing small amounts of nitrite and ammonia.The carbon dioxide anion radical(·CO_(2)^(-))from HCOOH/HCOO^(-)is the principal cause of NO_(3)^(-)-N reduction by UV/HCOOH/N 2 ARP.In contrast,·CO_(2)^(-)production is caused by the hydroxyl radical(·OH).The NO_(3)^(-)-N reduction efficiency is enhanced by the increase in the light intensity,considerably affected by the initial pH,and less affected by inorganic anions,including Cl^(-),H_(2)PO_(4)^(-),and HCO_(3)^(-)/CO_(3)^(2-).The initial HCOOH concentration and light intensity are the main factors that influence the NO_(3)^(-)-N reduction rate.

Synergy of adsorption and visible light photocatalysis to decolor methyl orange by activated carbon/nanosized CdS/chitosan composite

Activated carbon/nanosized CdS/chitosan(AC/n-CdS/CS) composites as adsorbent and photoactive catalyst were prepared under low temperature(≤60 ℃) and ambient pressure.Methyl orange(MO) was chosen as a model pollutant to evaluate synergistic effect of adsorption and photocatalytic decolorization by this innovative photocatalyst under visible light irradiation.Effects of various parameters such as catalyst amount,initial MO concentration,solution pH and reuse of catalyst on the decolorization of MO were investigated to optimize operational conditions.The decolorization of MO catalyzed by AC/n-CdS/CS fits the Langmuir-Hinshelwood kinetics model,and a surface reaction,where the dyes are absorbed,is the controlling step of the process.Decolorization efficiency of MO is improved with the increase in catalyst amount within a certain range.The photodecolorization of MO is more efficient in acidic media than alkaline media.The decolorization efficiency of MO is still higher than 84% after five cycles and 60 min under visible light irradiation,which confirms the reusability of AC/n-CdS/CS composite catalyst.

不同交联剂对明胶静电纺丝膜性能的影响

采用静电纺丝法制备的明胶组织工程支架耐水性和力学性能较差,无法直接作为软骨组织工程支架使.用。为改善其物理化学性能,分别采用1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺(EDC)与戊二醛(GA)对明胶电纺膜进行交联。分析对比了两种交联方法对纤维形貌、溶胀比、交联度、力学性能、细胞毒性及降解性能的影响,并考察了不同交联剂浓度对明胶膜物理和化学性能的影响。结果表明,与GA交联相比,采用1.5%EDC交联可以维持明胶膜的表面形貌,交联度可以达到65%,并且无细胞毒性,更有利于其作为骨及软骨组织工程支架的生物学应用。体外降解实验结果表明,采用GA和EDC交联的明胶膜在降解60d时降解率均为70%左右,基本符合软骨的修复要求。

Absorption Rate of CO_2 into MDEA Aqueous Solution Blended with Piperazine and Diethanolanline

Absorption rate of CO2 into aqueous solution of N-methyldiethanolamine (MDEA) blended with diethanolamine (DEA) and piperazine (PZ) was studied and a kinetic model was established. It is shown that homogeneous activation mechanism could explain this absorption process. The absorption rate coefficients of carbon dioxide into MDEA aqueous solution blended with DEA, PZ or DEA+PZ were compared with each other. The results demonstrated that the different activation effect of DEA, PZ and DEA+PZ on the carbon dioxide absorption comes from the difference in CO2 combination rate, transport of PZ and DEA to MDEA and the regeneration rate of PZ and DEA.