Visible-Light-Induced Vicinal Dichlorination of Alkenes through LMCT Excitation of CuCl2

This work demonstrates photoredox vicinal dichlorination of alkenes, based on the homolysis of CuCl₂ in response to irradiation with visible light. This catalysis proceeds via a ligand to metal charge transfer process and provides an exciting opportunity for the synthesis of 1,2-dichloride compounds using an inexpensive, low-molecular-weight chlorine source. This new process exhibits a wide substrate scope, excellent functional group tolerance, extraordinarily mild conditions and does not require external ligands. Mechanistic studies show that the ready formation of chlorine atom radicals is responsible for the facile formation of C−Cl bonds in this synthetic process.     

Divergent Synthesis of Vinyl‐, Benzyl‐, and Borylsilanes: Aryl to Alkyl 1,5‐Palladium Migration/Coupling Sequences

Organosilicon compounds have been extensively utilized both in industry and academia. Studies on the syntheses of diverse organosilanes is highly appealing. Through‐space metal/hydrogen shifts allow functionalization of C?H bonds at a remote site, which are otherwise difficult to achieve. However, until now, an aryl to alkyl 1,5‐palladium migration process seems to have not been presented. Reported herein is the remote olefination, arylation, and borylation of a methyl group on silicon to access diverse vinyl‐, benzyl‐, and borylsilanes, constituting a unique C(sp³)?H transformation based on a 1,5‐palladium migration process.     

Shape morphing and topology optimization of fluid channels by explicit boundary tracking

An integrated shape morphing and topology optimization approach based on the deformable simplicial complex methodology is developed to address Stokes and Navier‐Stokes flow problems. The optimized geometry is interpreted by a set of piecewise linear curves embedded in a well‐formed triangular mesh, resulting in a physically well‐defined interface between fluid and impermeable regions. The shape evolution is realized by deforming the curves while maintaining a high‐quality mesh through adaption of the mesh near the structural boundary, rather than performing global remeshing. Topological changes are allowed through hole merging or splitting of islands. The finite element discretization used provides smooth and stable optimized boundaries for simple energy dissipation objectives. However, for more advanced problems, boundary oscillations are observed due to conflicts between the objective function and the minimum length scale imposed by the meshing algorithm. A surface regularization scheme is introduced to circumvent this issue, which is specifically tailored for the deformable simplicial complex approach. In contrast to other filter‐based regularization techniques, the scheme does not introduce additional control variables, and at the same time, it is based on a rigorous sensitivity analysis. Several numerical examples are presented to demonstrate the applicability of the approach.     

Peptide dendrimer-crosslinked inorganic-organic hybrid supramolecular hydrogel for efficient anti-biofouling

A novel kind of inorganic-organic hybrid supramolecular hydrogel with excellent anti-biofouling capability was developed. The hydrogel was formed via ionic interaction between the negative-charged sodium polyacrylate (SPA) entwined clay nanosheets (CNS) and positive-charged polyhedral oligomeric silsesquioxane (POSS) core-based generation one (L-Arginine) dendrimer (POSS-R).     

非自治动力系统的原像熵

本文对紧致度量空间上的连续自映射序列应用生成集和分离集引入了点原像熵、原像分枝熵以及原像关系熵等几类原像熵的定义并进行了研究.主要结果是:(1) 证明了这些熵都是等度拓扑共轭不变量.(2)讨论了这些原像熵之间及它们与拓扑熵之间的关系,得到了联系这些熵的不等式.(3)证明了对正向可扩的连续自映射序列而言, 两类点原像熵相等,原像分枝熵与原像关系熵也相等.(4)证明了对(a).由闭Riemann 流形上的一个扩张映射经充分小的C1-扰动生成的自映射序列,以及(b).有限图上等度连续的自映射序列,有零原像分枝熵.     

Optical wavelet de-noising applied in multi-span nonlinear fiber links

In this work, optical wavelet de-noising with several different types of wavelets such as db4, coif4 and dmey wavelet was applied at the end of the 40 Gbit/s multi-span intensity-modulated fiber communication systems. The results of numerical simulations carried out in different fiber links demonstrated that the optical wavelet de-noising method could remove the random amplitude fluctuation induced by the interaction of EDFA’s ASE noise and optical fiber’s dispersion and nonlinearity. The SNR and BER curves of the optical bit sequence without and with optical wavelet de-noising in dispersion compensation fiber link were plotted to show the effectiveness of the wavelet de-noising in the fiber-optic communication systems and wavelet de-noising with demy wavelet can achieve better result than with other type wavelet.     

有限重数的Dirichlet移位

In this paper, we show that a multiplication operator on the Dirichlet space D is unitarily equivalent to Dirichlet shift of multiplicity n ＋ 1 （n ≥ 0） if and only if its symbol is c zn＋1 for some constant c. The result is very different from the cases of both the Bergman space and the Hardy space.     

Nanoindentation analysis of the pop-in events on SiGe single layer

The growth of metastable silicon germanium (Si_0.8Ge_0.2) thin film on Si(1 0 0) by ultrahigh-vacuum chemical vapor deposition has been subjected to residual indentation studies. A nanoindentation system has been applied to analyze SiGe film after different annealing treatments. A number of phenomena have been found for the heteroepitaxial growth of SiGe film at the critical thickness of 350 nm, including single discontinuity (the so-called “pop-in” event) as well as the elastic/plastic contact translation. Atomic force microscopy is employed to investigate the surface impression. Pop-in events in the load-indentation depth curves of 400 and 500 °C and no nano-cracks in the vicinity regions are found. The values of H ranging from 13.13±0.9, 21.66±1.3, 18.52±1.1, 14.47±0.7 GPa and the values of E ranging from 221.8±5.3, 230.7±6.4, 223.5±4.6, 156.7±3.8 GPa, are obtained. The elastic/plastic contact translation of the SiGe film occurs at different annealing conditions, with h_f/h_max values in the range of 0.501, 0.392, 0.424, and 0.535 for samples are treated at RT, 400, 500, and 600 °C, respectively. The mechanism responsible for the pop-in event in such crystal structure is due to the interaction of the indenter tip with the pre-existing threading dislocations, since the release of the indentation load is bound to be reflected in the directly compressed volume.     

更正:质子束治疗中非均匀组织的等效水厚度修正研究[物理学报2013,62,068701]

《物理学报》2013年第62卷第6期第068701页《质子束治疗中非均匀组织的等效水厚度修正研究》一文中,因作者疏忽导致几处错误,特此更正,并诚挚地向读者致歉.期刊网上此文的电子版已做相应的更正.将3.1节中三个公式做如下更正:将(1)式:"WET=R介质/R水×b"改成:"WET=R水/R介质×b"将(2)式:"WET=R1/R水×d1+R2/R水×d2+···+Rn/R水×dn"改成:"WET=R水/R1×d1+R水/R2×d2+···+R水/Rn×dn"