Double Michael addition of nitromethane to divinyl ketones: A remarkably positive effect of additive

An efficient double Michael addition of nitromethane to divinyl ketones was established in good to high yields (75–99%). A wide range of cyclohexanones were obtained with excellent diastereocontrol (up to >20:1 dr) and enantioinduction (91–99% ee) in a one-pot fashion. The involvement of basic additive significantly enhanced the reactivity of this cascade sequence.     

A new type of microemulsion containing task-special ionic liquid [NH2ebim][BF4]

The formation of microemulsions in the presence of cyclohexane, Triton X-100, n-butanol, water, and task-special ionic liquid (TSIL) (1-2-aminoethyl-3-butylimidazolium tetrafluoroborate) was studied at 25°C. The phase behavior of this ternary system was investigated. Three subregions (namely, water-in-oil phase, bicontinuous phase, and oil-in-water phase) were identified in the single-phase region by dynamic light scattering (DLS) technique and electrical conductivity measurement. Microstructures of microemulsions with different water contents have been predicted by using dissipative particle dynamics (DPD) simulation. It was found that the DPD simulations successfully reproduce the experimental results in the article. The location of TSIL in the microemulsions was predicted by DPD simulation further. The result indicates that TSIL is more easy to locate in the surfactant and cosurfactant layer and has amphiphilicity, which provides us new insights into the potential applications of TSIL-based microemulsions in separation and new nano-scale material preparation because of the interaction of TSIL with some special components at the interface of oil and water.     

A multi-detector integrated automation system of routine INAA

An integrated automation system of routine instrumental neutron activation analysis (INAA) with three HPGe detectors has been built at China Institute of Atomic Energy. This system is mainly composed of sample counting system, pneumatic transfer system, software control and analysis systems, etc. The characteristics include more than 200 samples can be controlled for a batch of INAA with three detectors simultaneously, sample counting position can be optimized automatically according to the counting dead time, the real-time tracking and the high consistency between the spectrum and counting sample are possible to be realized through radio frequency identification tag.

     

Fabrication of Electrospun PVDF Nanofibers with Higher Content of Polar β Phase and Smaller Diameter by Adding a Small Amount of Dioctadecyl Dimethyl Ammonium Chloride

In this work,the effect of dioctadecyl dimethyl ammonium chloride(DDAC,a kind of alkyl ammonium salt) on polar β phase content and the diameter of electrospun PVDF nanofibers was investigated for the first time.Our experimental results show that the diameter of the electrospun PVDF nanofiber could be largely reduced and the content of polar β phase also become dominant immediately by just adding a little amount of DDAC.When the mass fraction of DDAC reached 4%,the content of polar β phase increased by about 39.1% compared with PVDF nanofibers without DDAC.Besides,the crystallinity of PVDF nanofibers also increased with the addition of DDAC.Based on the results,the possible mechanism of cooperative effect between electrospinning and DDAC on fiber diameter and formation of β phase in PVDF was discussed.     

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.     

三峡工程坝址花岗岩体缓倾角结构面成因综合研究

本文对长江三峡工程坝址花岗岩体中缓倾角结构面成因进行了全面的综合研究。从野外地质调查人手,在大量野外勘测的基础上进行宏观分析,同时辅之以扫描电镜、透射电镜、包体温度测定等方法进行微观构造组构、差异应力等的研究。在地质力学宏观分析的基础上,利用地质力学物理模拟进行相似条件下的反演,并利用非线性有限元数值模拟进行验证。同类研究在国内外均未见先例,可为同类工程研究借鉴。     

结构随机激励的响应灵敏度分析

本文建立了有色噪声随机激励的响应协方差矩阵方程,推导了响应灵敏度的计算式,给出了进行灵敏度计算的方法,并作了实例计算。     

可扩展的冲击—接触并行计算研究

冲击—接触计算模型在汽车碰撞、金属成型等的模拟计算中有着广泛的应用，鉴于冲击—接触计算过程复杂和计算量大，本文在分布式可扩展的并行计算平台上，设计并实现了冲击—接触的并行计算。算例证明，计算平台稳定可靠，算法简单实用，且具有较好的并行效率和可扩展性。     

Delayed Fluorescent Emission from Pyrene Doped Phenanthrene Nanoparticles Based on Triplet-triplet Energy Transfer

Doped nanoparticles were prepared from pyrene and phenanthrene using a facile reprecipitation method. The doped nanoparticles presented unique delayed fluorescent emissions of pyrene under the unprotected condition. The ratio of the intensity of delayed fluorescence (I_DF) to that of phosphorescence (I_P) is about 4:1, which almost keeps unchanged with the decrease of pyrene content at room temperature. The intensity of the delayed fluorescence emissions is dependent on the relative content of pyrene, as well as the aggregation degree of nanoparticles. The delayed emissions are contributed to efficient triplet‐triplet energy transfer from phenanthrene (donor) to pyrene (acceptor). Steady fluorescence measurement have proved that the singlet‐singlet energy transfer process was also existent dominated by the radiation energy transfer mechanism.     

Synthesis and Structural Characterization of Lanthanide Amides Stabilized by an N-Aryloxo Functionalized β-Ketoiminate Ligand

The synthesis and characterization of dimeric lanthanide amides stabilized by a dianionic N‐aryloxo functionalized β‐ketoiminate ligand are described in this paper. Reactions of 4‐(2‐hydroxy‐5‐tert‐butyl‐phenyl)imino‐2‐pentanone (LH₂) with Ln[N(SiMe₃)₂]₃(µ‐Cl)Li(THF)₃ in a 1:1 molar ratio in THF gave the dimeric lanthanide amido complexes [LLn{N(SiMe₃)₂}(THF)]₂ [Ln=Nd ( 1 ), Sm ( 2 ), Yb ( 3 ), Y ( 4 )] in good isolated yields. These complexes were characterized by IR spectroscopy, elemental analysis, and ¹H NMR spectroscopy in the case of complex 4 . The definitive molecular structures of complexes 1 , 3 , and 4 were determined. It was found that complexes 1 to 4 can initiate the ring‐opening polymerization of L‐lactide.