MgO/γ-Al2O3催化酯交换合成碳酸甲丁酯

通过活性组分和载体筛选制备了MgO/γ-Al_2O_3催化剂,用于碳酸二甲酯(DMC)和正丁醇液相酯交换反应合成碳酸甲丁酯(BMC),并考察了活性组分前驱物、催化剂焙烧温度和活性组分负载量对催化剂活性的影响。结果表明,以Mg(OAc)_2·4H_2O为活性组分前驱物,催化剂焙烧温度为400℃,活性组分MgO负载量为5%时,MgO/γ-Al_2O_3表现出高的酯交换反应催化活性。同时考察了反应温度、原料配比对酯交换反应的影响,适宜的反应温度为100℃;物料配比n(DMC):n(正丁醇)=3:1时,正丁醇的转化率达到98.4%,BMC的选择性为91.9%,收率为90.4%。催化剂重复实验表明催化剂重复使用性能良好。     

γ-内酯类化合物的合成

γ-内酯是一类重要的香料化合物。研究了以廉价易得的糠醛为原料制备γ-内酯的合成路线。以糠醛和1-溴丙烷、1-溴丁烷、1-溴己烷为起始原料,合成了γ-辛内酯、γ-壬内酯以及γ-十一内酯。糠醛首先与溴代烷的格氏试剂在乙醚中反应,生成1-(2-呋喃基)烷醇,反应产率在86%左右。1-(2-呋喃基)烷醇在质量分数为0.5%的氯化氢的乙醇溶液中回流,开环水解得4-氧代羧酸,反应产率在60%左右。4-氧代羧酸与氯化亚砜在甲醇中回流反应,得4-氧代羧酸甲酯,产率约93%。4-氧代羧酸甲酯用硼氢化钠在甲醇中室温搅拌2 h,还原并且同时关环得γ-内酯,产率约85%。     

Comparative hot corrosion studies of EB-PVD and plasma sprayed coatings*

The use of directly fired heat engines, i. e. diesel and gas turbine engines, is likely to grow in the future. However, economic requirements will necessitate the development of highly efficient engines that operate at high temperatures and utilize low-grade fuels. An increase of combustion gas temperature and the utilization of low-grade fuels contaminated with, amongst others, sulphur and vanadium, may be accomplished by careful selection of the materials, e.g. by applying corrosion-resistant coatings on heatresistant alloys. The main purpose of the present work has been to test various coatingsubstrate combinations in a highly corrosive environment. The comparison of various coating techniques, e.g. electron beam physical vapour deposition (EB-PVD), air plasma spraying (APS), and low pressure plasma spraying/vacuum plasma spraying (LPPS/VPS), has been emphasized.     

Finishing works after welding of structures made of rust-resistant,high-alloy steels

In this paper, problems that occur when working with welds formed of high-alloy steels to restore their passive layers, damaged as a result of temperature impact, are discussed. Particular attention was paid to the procedures concerning aggressive etching agents during and after completion of the passivation processes (waste neutralization and utilization).     

Protocol for fast screening of multi-target drug candidates: Application to Alzheimer’s disease

The treatment of many diseases may require drugs that are capable to attack multiple targets simultaneously. Obviously, the virtual screening of multi-target drug candidates is much more time consuming compared to the single-target case. This, in particular, concerns the last step of virtual screening where the binding free energy is computed by conventional molecular dynamics simulation. To overcome this difficulty we propose a simple protocol which is relied on the fast steered molecular dynamics simulation and on available experimental data on binding affinity of reference ligand to a given target. Namely, first we compute non-equilibrium works generated during pulling ligands from the binding site using the steered molecular dynamics method. Then as top leads we choose only those compounds that have the non-equilibrium work larger than that of a reference compound for which the binding free energy has been already known from experiment.Despite many efforts no cures for AD (Alzheimer’s disease) have been found. One of possible reasons for this failure is that drug candidates were developed for a single target, while there are exist many possible pathways to AD. Applying our new protocol to five targets including amyloid beta fibril, peroxisome proliferator-activated receptor γ, retinoic X receptor α, β- and γ-secretases, we have found two potential drugs (CID 16040294 and CID 9998128) for AD from the large PubChem database. We have also shown that these two ligands can interfere with the activity of popular Acetylcholinesterase target through strong binding towards it.     

无皂硅丙胶乳表面施胶剂的制备及对纸张的增强作用

以γ-甲基丙烯酰氧丙基三甲氧基硅烷(KH570)作自交联单体,聚乙烯醇(PVA)为高分子胶体稳定剂,苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸(MAA)为单体采用无皂种子聚合制备了稳定性好、性能优异的无皂硅丙乳液表面施胶剂,并优化了合成工艺条件。结果表明,当w(MAA)=2%~3%,软硬单体比例n(BA)/n(St)=2~2.5,w(PVA)=10%~15%,w(KH570)=5%时,无皂硅丙乳液表面施胶剂具有优异的施胶效果;以质量分数为1.0%的聚合物乳液进行表面施胶时,纸张施胶度可达14.5 s,表面强度达3.69 m/s,耐折度3300次。     

γ-LiAlO2 Single Crystal Grown by Czochralski Technique and Modified by Vapor Transport Equilibration (VTE) Technique

Large-sized （～2 inch, 50.8 mm） γ-LiAlO2 single crystal has been grown by conventional Czochralski （Cz） method, but the crystal has a milky, dendriform center. The samples taken from transparent and milky parts were ground and examined by X-ray diffraction. All diffraction peaks could be indexed in γ-LiAlO2. The crystal quality was characterized by X-ray rocking curve. The full-width at half-maximum （FWHM） values are 116.9 and 132.0 arcsec for transparent and milky parts, respectively. The vapor transport equilibrium （VTE） technique was introduced to modify the crystal quality. After 1000℃/48 h, 1100℃/48 h, 1200℃/48 h VTE processes, the FWHM values dropped to 44.2 and 55.2 arcsec for transparent and milky part, respectively. The optical transmission of transparent part was greatly enhanced from 85% to 90%, and transmission of milky part from 75% to 80% in the range of 190~1900 nm at room temperature. When the VTE temperature was raised to 1300℃, the sample cracked and FWHM values of transparent and milky parts were increased to 55.2 and 80.9 arcsec, respectively. By combining Cz technique with VTE technique, large-sized and high quality γ-LiAlO2 crystal can be obtained.     

合成N-乙基哌嗪的催化剂改性研究

采用离子交换法对合成N-乙基哌嗪的催化剂γ-氧化铝进行改性,考察了催化剂制备方法对反应的影响。结果表明,γ-Al2O3在室温下经1.00 mol/L的Cu(NO3)2溶液浸渍48 h,110℃干燥3 h,500℃焙烧6 h,于0.6 MPa压力的反应器内、300℃,氢气还原3 h后具有较好的活性和选择性,可提高N-乙基哌嗪收率和哌嗪转化率。     

Preparation of Polymer-stabilized Palladium–silver Bimetallic Nanoparticles by γ-irradiation and their Catalytic Properties for Hydrogenation of cis,cis-1,3-Cyclooctadiene

Polyvinypyrrolidone (PVP)-stabilized Pd-Ag bimetallic colloids were successfully prepared in an acetone:2-propanol solution mixture of palladium acetate and silver perchlorate, and in an aqueous solution of palladium nitrate and silver nitrate by γ-irradiation. The prepared PVP-stabilized bimetallic nanoparticles were characterized by UV, TEM, XRD, and XPS. In Pd–Ag bimetallic nanoparticles, the XPS data indicated that the constituent elements were in the metallic state, and the palladium atoms were concentrated on the surface of the alloy cluster. These PVP-stabilized bimetallic nanoparticles were used as catalysts for hydrogenation of cis,cis-1,3-cyclooctadiene (COD).