Numerical analysis for stochastic age-dependent population equations with Poisson jumps

In this paper, stochastic age-dependent population equations with Poisson jumps are considered. In general, most of stochastic age-dependent population equations with jumps do not have explicit solutions, thus numerical approximation schemes are invaluable tools for exploring their properties. The main purpose of this paper is to develop a numerical Euler scheme and show the convergence of the numerical approximation solution to the true solution.     

现代热力学的完整分类系统--非平衡非耗散热力学新领域

在同一体系中同时有多个不可逆过程时，不可逆过程之间会有相互影响，原来的非自发过程有可能在其他自发过程的影响下得以进行，这种现象就称为热力学耦合或反应耦合，长期以来，经典热力学把热力学第二定律的等式作为平衡体系的充分必要条件，其中隐含了一个前提性的假定，即经典热力学的对象只限于非耦合的体系，摈弃这一隐含的前提性假定以后，热力学自身就发展成为一个现代热力学的完整学术体系，适用于任何宏观体系（包括极其复杂的生命体系），现代热力学的完整学术体系中包含了一个崭新的非平衡非耗散热力学新领域，由于该领域属于热力学第二定律的等式部分，因此可以定量计算，并得到一系列理论计算的非平衡相图，与文献上报道的激尖低压金刚石合成等的大量实验数据相符。     

Density functional theory study on antiferromagnetic interactions in a silver (I) complex of nitronyl nitroxide

A one-dimensional (1D) silver (I) complex of nitronyl nitroxide with fairly strong antiferromagnetic interaction, in which the metal ions are diamagnetic, is investigated by means of the ab initio crystal orbital method based on the density functional theory. The calculated values of the magnetic coupling constant (J) are close to the experimental measured J value in the periodic system. The magneto-structural correlation reveals that the existence of an antiferromagnetic coupling pathway along nitronyl nitroxide units via silver (I) ion in this system. The spin population distribution also shows the existence of spin delocalization along the ONCNO–Ag–ONCNO, which affords a rational interpretation for the antiferromagnetic interaction mechanism.     

Examples of non-Kähler Hamiltonian circle manifolds with the strong Lefschetz property

In this paper we construct six-dimensional compact non-Kähler Hamiltonian circle manifolds which satisfy the strong Lefschetz property themselves but nevertheless have a non-Lefschetz symplectic quotient. This provides the first known counterexamples to the question whether the strong Lefschetz property descends to the symplectic quotient. We also give examples of Hamiltonian strong Lefschetz circle manifolds which have a non-Lefschetz fixed point submanifold. In addition, we establish a sufficient and necessary condition for a finitely presentable group to be the fundamental group of a strong Lefschetz manifold. We then use it to show the existence of Lefschetz four-manifolds with non-Lefschetz finite covering spaces.     

Asymmetric synthesis of abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling. Formal total asymmetric synthesis of 12-deoxyroyleanone and cryptoquinone

A convergent synthetic strategy for abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling and Lewis acid-mediated cyclization reactions is established. Asymmetric total synthesis of 12-deoxyroyleanone, an antileishmanial diterpene, is described.     

各向同性湍流中颗粒引起湍流变动的直接模拟

本文通过直接数值模拟对均匀各向同性湍流中颗粒对湍流的变动作用进行了研究.颗粒相的体积分数很小而质量载荷足够大,以至于颗粒之间的相互作用可以忽略不计,而重点考虑颗粒与湍流间能量的交换。颗粒对湍流的反向作用使得湍动能的耗散率增强,以至于湍动能的衰减速率增大.湍动能的衰减速率随颗粒惯性的增大而增大。三维湍动能谱显示,颗粒对湍动能的影响在不同的尺度上是不均匀的。在低波数段,流体带动颗粒,而高波数段则相反.     

Imidazol(in)ium carboxylates as N-heterocyclic carbene ligand precursors for Suzuki-Miyaura reactions

Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product.     

DIELECTRIC EFFECT ON THE RADIO-FREQUENCY CHARACTERISTICS OF A RECTANGULAR WAVEGUIDE GRATING TRAVELING WAVE TUBE

A new type of partial-dielectric-loaded rectangular waveguide grating slow-wave structure (SWS) for millimeter wave traveling wave tube (TWT) is presented in this paper. The radio-frequency characteristics including the dispersion properties, the longitudinal electric field distribution and the beam-wave coupling impedance of this structure are analyzed. The results show that the dispersion of the rectangular waveguide grating circuit is weakened, the phase velocity is reduced and the position of the maximum E _z is basically invariant after partially filling the dielectric materials in the rectangular waveguide grating SWS. Although the coupling impedance decreases a little, it still keeps above 40 Ω.