Semi-parallel real hypersurfaces in complex two-plane Grassmannians

We prove that there does not exist any semi-parallel real hypersurface in complex two-plane Grassmannians. With this result, the nonexistence of recurrent real hypersurfaces in complex two-plane Grassmannians can also be proved.     

Fabrication of complex nanostructures on ZnO crystals by the interference of three femtosecond laser beams

By adjusting the laser polarization combinations, fluences and pulse numbers, we fabricated several types of two-dimensional (2D) complex nanostructures on the surface of c-cut ZnO single crystal by the interference of three femtosecond laser beams with central wavelength of 800 nm, pulse duration of 50 fs and pulse repetition frequency of 1 kHz. The hexagonal 2D nanostructures with a period of 600 nm are very regular and uniform, in which nanoparticles, nanorings and nanoripples with sizes of 200 nm are embedded. Excited by 800 nm femtosecond laser pulses, the photoluminescence (PL) micrographs reveal that the 2D nanostructures can emit purer and brighter blue light compared with the plane surface. These nanostructures have potential applications in blue light-emitting diodes (LEDs), high density optical storage and other optoelectronic devices.     

Characterizing emerging European stock markets through complex networks: From local properties to self-similar characteristics

We investigate the properties of the returns of the main emerging stock markets from Europe by means of complex networks. We transform the series of daily returns into complex networks, and analyze the local properties of these networks with respect to degree distributions, clustering, or average line length. We further use the clustering coefficients as quantities describing the local structure of the network, and approach them by using multifractal analysis. We find evidence of scale-free networks and multifractality of clustering coefficients.     

Chiral vectors-tunable electronic property of MoS2 nanotubes

It has been demonstrated that the mechanical and electronic properties of materials change significantly when the external dimension are confined to the nanoscale. Consequently, one-dimensional (1D) transition-metal dichalcogenide (TMDC) nanotubes (NTs), obtained from scrolling 2D TMDC, have attracted much attentions because of their intriguing properties and the chirality plays a key role in affecting the electronic properties. Taking the amount of speculations on the mechanism and the increasing needs for better device design and performance control, understanding the effect of chirality on the electronic properties is timely and relevant. Here, MoS₂ NTs are comprehensively studied by first-principles calculations. The results show that the armchair (6≤ch≤14) exhibits the indirect-band-gap and zigzag (10≤ch≤20) with direct-band-gap. Moreover, the carrier mobility is enhanced with the decrease of radial length, in accord with the smaller effective mass of hole and electron for both types NTs. Finally, the formation energy showed that the smaller the radial diameters is, the harder the NTs is to form. Moreover, the similarity of lattice parameters and formation energy implies a potential possibility of transition between two types of NTs with low index chiral vectors, such as ANT(6,6)/ZNT(10,0).     

Characterization and Molecular Structure of Bis(Isopropyl Xanthate) Bis(1,10-Phenanthroline) Nickel(II): [Ni(phen)2(CH3)2CHOCSS](CH3)2CHOCSS

The crystal and molecular structure of the title compound, [Ni(phen)₂(CH₃)₂CHOCSS](CH₃)₂CHOCSS has been determined by X-ray diffraction. The brown crystal is triclinic of space group Pi, with parameters a = 11.790(2), b = 12.410(3), c = 12.680(3) Å, α = 92.49(3), β = 96.54(3), γ = 117.43(3)° and Z = 2. The compound contains a six-coordinate cation and an isopropyl xanthate anion (CH₃)₂CHOCSS^?, the central Ni atom is chelated by four nitrogen atoms of two phenanthroline ligands and two sulfur atoms of an isopropyl xanthate ligand. The TG data indicate that it decomposed completely at 734°C.     

Water Soluble Benzimidazole Containing Ionic Palladium(II) Complex for Rapid Microwave‐Assisted Suzuki Reaction of Aryl Chlorides

In this paper a water soluble benzimidazole – Pd complex used for Suzuki reaction under conventional heating and microwave heating. To increase the activity of complex, ionic group change with bulky TBA⁺ and Bmim⁺ groups. To determine whether the reaction is homogeneous or heterogeneous, Hg(0) poisoning tests, hot filtration tests and CS₂ poisoning tests were performed.     

Synthesis and Self-assembly of a Linear Coil-Coil-Rod ABC Triblock Copolymer

An interesting order-order transition between two different complex nanostructures was observed in a new liquid crystalline linear coil-coil-rod ABC triblock copolymer（tri BCP）. First, the ABC tri BCP, poly（dimethylsiloxane）-bpolystyrene-b-poly{2,5-bis[（4-methoxyphenyl）oxycarbonyl]styrene}（PDMS-b-PS-b-PMPCS）, was synthesized through sequential atom transfer radical polymerization. The degrees of polymerization of PDMS, PS, and PMPCS blocks are 58, 159, and 106, and the corresponding volume fractions of PDMS, PS, and PMPCS are 0.09, 0.29, and 0.62, respectively. The phase behaviors of the PDMS-b-PS diblock copolymer precursor and the final triblock copolymer were studied by smallangle X-ray scattering, one-dimensional wide-angle X-ray scattering, and transmission electron microscopy experiments. The PDMS-b-PS precursor self-assembles into hexagonally packed cylinders with a relatively small periodic size after thermal annealing. When the triblock copolymer is annealed at a relatively low temperature（120 ○C） at which the PMPCS block is in the amorphous state, the tri BCP forms core-shell hexagonally packed cylinders（CSH） with a relativly large periodic size. After the tri BCP is annealed above 140 ○C at which the PMPCS block transforms to the liquid crystalline（LC） phase, the nanophase-separated structure transforms to a three-phase four-layer lamellar structure（LAM-3P4L）. Thus, accompanied with the transition of the PMPCS blocks from the amorphous state to the LC phase, the order-order transition from CSH to LAM-3P4 L occurs in the PDMS-b-PS-b-PMPCS ABC tri BCP.     

Solution for Eshelby’s elliptic inclusion with polynomials distribution of the eigenstrains in plane elasticity

This paper provides a closed form solution for the Eshelby’s elliptic inclusion in plane elasticity with the polynomials distribution of the eigenstrains. The complex variable method and the conformal mapping technique are used. The continuity conditions for the traction and displacement along the interface in the physical plane are reduced to a similar condition along the unit circle of the mapping plane. From those continuity conditions, we can obtain two sets of the complex potentials for the region outside of the unit circle and for the ring region, respectively. Further, we can obtain the complex potentials in the physical plane, or z-plane (z = x + iy). The mapping function maps the ring region in the mapping plane into a finite elliptic region with a crack on the real axis in the physical plane. An exact form for the complex potentials defined in the ring region is studied and proposed. In addition, the stress distribution on the inclusion is evaluated. Those results are first obtained in the paper.     

A study of design approach of spreading schemes for viral marketing based on human dynamics

Before launching a real viral marketing campaign, it is needed to design a spreading scheme by simulations. Based on a categorization of spreading patterns in real world and models, we point out that the existing research (especially Yang et al. (2010) Ref.  [16]) implicitly assume that if a user decides to post a received message (is activated), he/she will take the reposting action promptly (Prompt Action After Activation, or PAAA). After a careful analysis on a real dataset however, it is found that the observed time differences between action and activation exhibit a heavy-tailed distribution. A simulation model for heavy-tailed pattern is then proposed and performed. Similarities and differences of spreading processes between the heavy-tailed and PAAA patterns are analyzed. Consequently, a more practical design approach of spreading scheme for viral marketing on QQ platform is proposed. The design approach can be extended and applied to the contexts of non-heavy-tailed pattern, and viral marketing on other instant messaging platforms.     

Synthesis,characterization, crystal structure,and biological studies of vanadium complexes with glycolic acid

Synthesis, characterization, crystal structure, and biological studies of two complexes with glycolic acid are described. The solid complexes were formulated as K₂[VO(C₂H₂O₃)(C₂H₃O₃)₂] · H₂O (1) and K₂[{VO₂(C₂H₂O₃)}₂] (2) and characterized by X-ray studies, Fourier transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and magnetic susceptibility. Conversion of 1 to 2 was studied in aqueous solution by UV–Vis spectroscopy and in the solid state by diffuse reflectance spectroscopy. Complex 2 contains dinuclear [{VO₂(C₂H₂O₃)}₂]^2? anions in which glycolate(2?) is a five-membered chelating ring formed by carboxylate and α-hydroxy groups. The geometry around the vanadium in 2 was interpreted as intermediate between a trigonal bipyramid and a square pyramid. Vanadium(IV) is pentacoordinate in 1 as a distorted square pyramid. Complex 1 contains a vanadyl group (V=O) surrounded by two oxygens from deprotonated carboxylate and hydroxy groups forming a five-membered ring. Two oxygens from different glycolates(1?) are bonded to the (V=O) also. Biological analysis for potential cytotoxic effects of 1 was performed using Human Cervix Adenocarcinoma (HeLa) cells, a human cervix adenocarcinoma-derived cell line. After incubation for 48 h, 1 causes 90 and 95% of HeLa cells death at 20 and 200 μmol L^?1, respectively.