Direct oxidative C(sp3) -H cyanation of secondary benzylic ethers

A practical and efficient oxidative CH cyanation of secondary benzylic ethers with TMSCN in the presence of DDQ is described for the first time. The metal-free process is well tolerated with a wide variety of electronically varied α-monosubstituted isochromans for the synthesis of isochromans bearing α-aryl α-cyano substituent patterns.     

On the Ranked-Set Sampling M-Estimates for Symmetric Location Families

The ranked-set sampling (RSS) is applicable in practical problems where the variable of interest for an observed item is costly or time-consuming but the ranking of a set of items according to the variable can be easily done without actual measurement. In this article, the M-estimates of location parameters using RSS data are studied. We deal mainly with symmetric location families. The asymptotic properties of M-estimates based on ranked-set samples are established. The properties of unbalanced ranked-set sample M-estimates are employed to develop the methodology for determining optimal ranked-set sampling schemes. The asymptotic relative efficiencies of ranked-set sample M-estimates are investigated. Some simulation studies are reported.     

激光诱导液晶定向研究

Multiple target detection using a fringe-adjusted and power spectrum subtracted joint transform correlator is proposed. The best factor of the filter to deliver the best correlation output performance is found through computer simulation tests and the result is verified by a programmable single spatial light modulator joint transform correlator. The technique is found to deliver a better correlation output and the capacity to accommodate noise in the input scene than the classical, the previous fringe adjusted and modified fringe adjusted joint transform correlators.     

Neutron Total Scattering Investigation of the Dissolution Mechanism of Trehalose in Alkali/Urea Aqueous Solution

The atomic picture of cellulose dissolution in alkali/urea aqueous solution is still not clear. To reveal it, we use trehalose as the model molecule and total scattering as the main tool. Three kinds of alkali solution, i.e., LiOH, NaOH and KOH are compared. The most probable all-atom structures of the solution are thus obtained. The hydration shell of trehalose has a layered structure. The smaller alkali ions can penetrate into the glucose rings around oxygen atoms to form the first hydration layer. The larger urea molecules interact with hydroxide groups to form complexations. Then, the electronegative complexation can form the second hydration layer around alkali ions via electrostatic interaction. Therefore, the solubility of alkali aqueous solution for cellulose decreases with the alkali cation radius, i.e., LiOH > NaOH > KOH. Our findings are helpful for designing better green solvents for cellulose.     

Targeting EGFR Overexpression at the Surface of Colorectal Cancer Cells by Exploiting Amidated BODIPY-Peptide Conjugates

Three BODIPY-peptide conjugates designed to target the epidermal growth factor receptor (EGFR) at the extracellular domain were synthesized, and their specificity for binding to EGFR was investigated. Peptide sequences containing seven amino acids, GLARLLT ( 2) and KLARLLT ( 4 ), and 13 amino acids, GYHWYGYTPQNVI ( 3 ), were conjugated to carboxyl BODIPY dye ( 1 ) by amide bond formation in up to 73% yields. The BODIPY-peptide conjugates and their “parent” peptides were determined to bind to EGFR experimentally using SPR analysis and were further investigated using computational methods (AutoDock). Results of SPR, competitive binding and docking studies propose that conjugate 6 including the GYHWYGYTPQNVI sequence binds to EGFR more effectively than conjugates 5 and 7 , bearing the smaller peptide sequences. Findings in human carcinoma HEp2 cells overexpressing EGFR showed nontoxic behavior in the presence of activated light (1.5 J cm⁻²) and in the absence of light for all BODIPYs. Furthermore, conjugate 6 showed about five-fold higher accumulation within HEp2 cells compared with conjugates 5 and 7 , localizing preferentially in the cell ER and lysosomes. Our findings suggest that BODIPY-peptide conjugate 6 is a promising contrast agent for detection of colorectal cancer and potentially other EGFR-overexpressing cancers.     

Pd-Catalyzed Aerobic Intermolecular 1,2-Diamination of Conjugated Dienes: Regio- and Chemoselective Synthesis of Piperazines and 2-Piperazinones

Dinitrogen heterocycles are among the most important molecular structures, and the synthesis of these types of structures through intermolecular 1,2-diamination of olefins is a direct and efficient method. However, the types of nitrogen sources are mostly derived from ureas or arylamines, and nitrogen sources from aliphatic amines are still limited due to their distinct electronic and steric effects. Herein, we report a palladium-catalyzed aerobic intermolecular 1,2-diamination of conjugated dienes, using ethanediamine and α-amino amide derivatives as nitrogen sources respectively, for the synthesis of piperazines and 2-piperazinones in good yields (up to 95 %) and with high regio- and chemoselectivities.     

蒙特卡罗粒子输运程序JMCT研制

介绍了具有自主知识产权的蒙特卡罗(MC)粒子输运程序JMCT的初步研制成果。JMCT基于三维组合几何支撑软件框架JCOGIN,采用模块化,分成多层管理结构,可处理多群碰撞和连续能量碰撞,可进行粒子并行和区域分解并行两种并行方法,并具有良好的可扩展性和高速通信技术,同时配有可视化建模前处理软件。介绍了JMCT采用的多群物质碰撞机制,展示了程序模拟计算测试模型的结果,与MCNP程序计算结果一致。JMCT串行计算速度相比MCNP提高了约3 倍;在20 480个处理器核上模拟2109样本,并行效率可达70%。     

对产业链中上游企业R&D投入的政府补贴策略选择

在产业链中上游企业R&D投入的情况下,机会主义的存在使得上游企业R&D投入水平往往不能达到社会最优.政府需要判断通过对企业R&D投入进行补贴能否改善社会福利及应该采用哪种补贴方式.作者构建了三阶段博弈模型,分别对无补贴,投入补贴,产量补贴及社会福利最优模型4种情况进行了分析.研究表明:政府补贴能拉动企业R&D投入,改善社会福利,其中产量补贴的方式更为有效,在产业链中上游企业R&D投入的情况下,通过选择合适的补贴率,产量补贴甚至能达到社会最优福利模型的理想状态.