Highly atom efficient guanylation of both aromatic and secondary amines catalyzed by simple lanthanide amides

It is demonstrated that the cyclopentadienyl-free simple lanthanide amides [(Me(3)Si)(2)N](3)Ln(mu-Cl)Li(THF)(3)(Ln = La, Sm, Eu, Y, Yb) and Ln[N(SiMe(3))(2)]3 (Ln = Y, Yb) are highly efficient catalysts for the guanylation of both aromatic and secondary amines with a high activity under mild conditions. It is found that these catalysts are compatible with a wide range of solvents and substrates.     

浓甲醛水溶液催化聚合动力学

在饱和或过饱和的浓甲醛水溶液中,在离子型催化剂作用下的甲醛聚合难以用缩聚机理解释的情况下,我们提出了离子型聚合机理。     

Improvement of Soliton Communication System with Optical Phase Conjugation

Optical phase conjugation is used to improve soliton communication system cascaded by distributed erbium-doped fibers. The results show that if its periodic length is chosen properly, optical phase conjugation can reduce the radiated energy and the time jitters, postpone the widening of soliton pulse width, also improve the stability of the soliton system.     

Two-dimensional Hermite-Gaussian solitons in strongly nonlocal nonlinear medium with rectangular boundaries

An analytical solution of self-similar waves, Hermite-Gaussian solitons, emerging in a strongly nonlocal thermal nonlinear medium with the rectangular boundaries was found. The theoretical analysis and numerical simulation showed that the Hermite-Gaussian solitons are elliptic and form a rectangular matrix cluster. Moreover, the symmetries of the soliton and matrix cluster depend not only on the boundary conditions, but also on the symmetry and power of the input beam as well as the propagation distance. The particular interest lies in that the intensities of the solitons in the edges of the rectangular cluster are bigger than those on the center, the most intense solitons occurring at four angles.     

Cannizzaro-type disproportionation of aromatic aldehydes to amides and alcohols by using either a stoichiometric amount or a catalytic amount of lanthanide compounds

Aromatic aldehydes can be directly converted to the corresponding amides and alcohols in good to excellent yields by the treatment of aromatic aldehydes with lithium amide LiN(SiMe3)2 in the presence of catalytic lanthanide chlorides LnCl3 or by the treatment of aromatic aldehydes with a stoichiometric amount of lanthanide amides [(Me3Si)2N]3Ln(mu-Cl)Li(THF)3 at ambient temperature. The effects of solvents, substitutents on the phenyl ring, and lanthanide metals on the reaction have been examined. The mechanism of the disproportionation reaction was proposed based on the experimental results.     

基于代价优化的云工作流调度改进PSO算法

云计算可以通过即付即用的方式向用户工作流提供资源。为了解决资源服务代价异构环境下的云工作流任务调度代价问题,提出一种基于改进粒子群算法的云工作流任务调度算法WSA-IPSO。通过综合考虑任务的执行代价和依赖任务间发生数据传输时的通信代价,算法将总代价优化问题形式化为有向无环图DAG中的任务调度模型,并提出基于改进粒子群算法的优化模型对其进行求解。通过改进传统粒子群算法的粒子速度更新策略和惯性权重更新策略,算法可以以更快的收敛速度得到代价最小化的调度方案。通过仿真实验,与MCT算法及标准粒子群算法进行性能比较。实验结果表明,WSA-IPSO算法在降低总代价、任务分布的负载均衡以及算法收敛性方面比较同类算法均表现出更好的性能。     

Highly efficient hydrophosphonylation of aldehydes and unactivated ketones catalyzed by methylene-linked pyrrolyl rare earth metal amido complexes

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.     

La3+提高拟南芥耐旱能力研究

稀土元素有着广泛的生物学效应,稀土作为微肥在我国农业广泛使用.然而,稀土对植物抗旱性影响的研究很少.以模式植物拟南芥为材料,研究了不同浓度的镧(La3+)对植物根生长以及对植物耐旱能力的影响.结果表明,10和100 μmol ·L-1的La3能显著促进根生长,提高植物耐旱能力;1μmol·L-1La3+没有明显促进根生长,但显著提高了植物耐旱能力;1和10 mmol·L-1的La3+不能促进根生长,同时还降低了植物耐旱能力.该结果提示,稀土农用过程中要重视剂量的使用,同时避免带来生态环境问题.     

Highly Efficient Hydrophosphonylation of Aldehydes and Unactivated Ketones Catalyzed by Methylene‐Linked Pyrrolyl Rare Earth Metal Amido Complexes

A series of rare earth metal amido complexes bearing methylene‐linked pyrrolyl‐amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent‐free conditions for liquid substrates. Treatment of [(Me₃Si)₂N]₃Ln(μ‐Cl)Li(THF)₃ with 2‐(2,6‐Me₂C₆H₃NHCH₂)C₄H₃NH ( 1 , 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ‐η⁵:η¹):η¹‐2‐[(2,6‐Me₂C₆H₃)NCH₂](C₄H₃N)LnN(SiMe₃)₂}₂ [Ln=Y ( 2 ), Nd ( 3 ), Sm ( 4 ), Dy ( 5 ), Yb ( 6 )] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by ¹H NMR spectroscopic analyses. The structures of complexes 2 , 3 , 4 , and 6 were determined by single‐crystal X‐ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol %) afforded the products in high yields (up to 99 %) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99 % with employment of low loadings (0.1 to 0.5 mol %) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α‐hydroxy diaryl phosphonates in moderate to high yields.     

基于FPGA的RFID防碰撞算法的硬件实现

采用改进型二进制树搜索算法,优化了二进制树搜索路径、仲裁中断信道传输及高效随机数产生器的设计,用Verilog HDL语言在RTL级对全算法模块进行了描述,并用ModelSim软件进行功能仿真及时序验证,在Stratix EP1S10F484C5器件上进行防碰撞现场可编程门阵列(FPGA)综合,使射频识别技术(RFID)系统兼容基于位碰撞及非基于位碰撞两种识别机制的硬件设计得以实现.实验结果表明:该改进算法执行效率接近50%,比传统算法具有更高的时分多址(TDMA)信号利用率及平均识别效率,能满足多标签的快速准确识别,起到良好的防碰撞作用.