Second harmonic generation from corona-poled polymer thin films of Y-shape chromophore with different isolation groups

We characterize thermal stability fof second harmonic generation (SHG) properties of four different Y-type polymers poled using corona poling method. These polymers are based on donor–acceptor–donor-type repeating unit with different aromatic moieties acting as donors and dicyanomethylene acting as an acceptor through conjugated bridge. The donor varies from different substituted benzene to phenothiazine. Polymer containing phenothiazine as donor showed higher SHG intensity and high temperature stability due to rigid repeating unit of phenothiazine compared to others with benzene in the main chain.     

Plasma-filled rippled wall rectangular backward wave oscillator driven by sheet electron beam

Performance of the backward wave oscillator (BWO) is greatly enhanced with the introduction of plasma. Linear theory of the dispersion relation and the growth rate have been derived and analysed numerically for plasma-filled rippled wall rectangular waveguide driven by sheet electron beam. To see the effect of plasma on the TM₀₁ cold wave structure mode and on the generated frequency, the parameters used are: relativistic factor γ = 1.5 (i.e. v/c = 0.741), average waveguide height y ₀ = 1.445 cm, axial corrugation period z ₀ = 1.67 cm, and corrugation amplitude ε = 0.225 cm. The plasma density is varied from zero to 2 ×10¹² cm^− 3. The presence of plasma tends to raise the TM₀₁ mode cut-off frequency (14 GHz at 2 ×10¹² cm^− 3 plasma density) relative to the vacuum cut-off frequency (5 GHz) which also causes a decrease in the group velocity everywhere, resulting in a flattening of the dispersion relation. With the introduction of plasma, an enhancement in absolute instability was observed.     

SOLVING A CROP PROBLEM BY AN OPTIMAL CONTROL METHOD

ABSTRACT. A system of ordinary differential equations coupled with a parabolic partial differential equation is studied in order to understand an interaction between two crops and a pathogen. Two different types of crops are planted in same field in some pattern so that the spread of pathogen can be controlled. The pathogen prefers to eat one crop. The other crop, which is not preferred by the pathogen, is introduced to control the spread of pathogen in the farming land. The “optimal” initial planting pattern is sought to maximize plant yields while minimizing the variation in the planting pattern. The optimal pattern is characterized by a variation inequality involving the solutions of the optimality system. Numerical examples are given to illustrate the results.     

咪唑配合物[Co(C3H4N2)6](PhCHCHCOO)2的合成及晶体结构

The complex [Co(Im)6](Cin)2 (Im=imidazole,Cin=cinnamate) was prepared by reaction of Co(PhCHCHCOO)2 with imidazole in ethanol. It has been determined by single crystal X-ray analyses. The crystals are triclinic, space group P, with a=9.7601(3),b=10.5935(3),c=11.3269(2)(A),α =69.948(1),β =71.027(1),γ =62.803(1)°, and Z=1. The crystal structure of the title complex consists of monomeric [Co(Im)6]2+ cations and cinnamate anions in which the cobalt(Ⅱ) ion assumes a centrosymmetric octahedral geometry with the CoN6 chromophore. In the solid state, the complex forms a three dimensional network through N-H… O hydrogen bonds, the intermolecular hydrogen bonds connect the [Co(Im)6]2+ cations and cinnamate anions.The cinnamate anions are nearly planar.     

High-Order Finite-Differences Schemes to Solve Poisson's Equation in Polar Coordinates

In the present work finite difference schemes of second andfourth order are derived for the solution of Poisson's equationin polar coordinates. To solve the resulting system of linearequations, a direct method similar to Hockney's method is developed.The schemes are tested on six test problems whose exact solutionsare known. The numerical results obtained by these finite-differenceschemes show that they produce very accurate results.     

Thermal expansion behaviour and phase stability of AFe<Subscript>2</Subscript>As<Subscript>2</Subscript> (A = Ca,Sr and Eu) using powder diffraction technique

The thermal expansibilities and phase stabilities of AFe ₂As ₂ (A = Ca, Sr and Eu) have been investigated by powder diffraction techniques in the temperature range 5–600 K. We found the anisotropic thermal expansivities with temperature for all the compounds. The lattice parameter in the tetragonal phase ( A_T) of CaFe ₂As ₂ contracts with increasing temperature, whereas C_T expands. The rate of contraction in A_T is lower than the rate of expansion in C_T. Other compounds show normal thermal expansion behaviour along both a- and c-axes. In-plane expansion (i.e., along the a-axis) is found to be the smallest for EuFe ₂As ₂ and the highest for BaFe ₂As ₂. However, the rate of change of thermal expansivities along out-of-plane (i.e., along the c-axis) is higher as we go from Ba, Sr, Eu and Ca, respectively. Above 600 K, we notice the appearance /disappearance of certain reflections which suggest that tetragonal phase is not stable above this temperature for these compounds.     

TiO2担载镍催化剂上硝基苯液相加氢（英文）

The catalytic hydrogenation of nitrobenzene to aniline employing nickel impregnated on rutile,anatase,and high surface area titania supports has been investigated.The nickel is present in elemental state as fcc phase on the catalyst as evidenced by X-ray diffraction results.The Ni crystallite size was found to be greater for Ni/anatase.The temperature-programmed reduction results suggest a greater metal-support interaction for Ni/rutile.The observed order of catalytic activity for the hydrogenation of nitrobenzene is Ni/rutile > Ni/anatase > Ni/TiO2.A conversion of 99% was observed for Ni/rutile at 140 oC and hydrogen pressure of 1.96 MPa.Interestingly,aniline is the only product formed which demonstrates the catalytic hydrogenation of nitrobenzene proceeds with atom economy.Both Ni/rutile and Ni/anatase exhibited a better stability than Ni/TiO2.The hydrogenation proceeds with the preferential adsorption of hydrogen on nickel present in the catalyst surface,possibly assisted by TiOx species.     

Planar electron beams in a wiggler magnet array

Transport of high current (～kA range with particle energy ～1 MeV) planar electron beams is a topic of increasing interest for applications in high-power (1–10 GW) and high-frequency (10–20 GHz) microwave devices such as backward wave oscillator (BWO), klystrons, gyro-BWOs, etc. In this paper, we give a simulated result for transport of electron beams with velocity $V_{\rm b} = 5.23 \times 10^{8}$  cm s^???1, relativistic factor γ?=?1.16, and beam voltage = ～80 kV in notched wiggler magnet array. The calculation includes self-consistent effects of beam-generated fields. Our results show that the notched wiggler configuration with ～6.97 kG magnetic field strength can provide vertical and horizontal confinements for a sheet electron beam with 0.3 cm thickness and 2 cm width. The feasibility calculation addresses to a system expected to drive for 13–20 GHz BWO with rippled waveguide parameters as width w?=?3.0 cm, thickness t?=?1.0 cm, corrugation depth h?=?0.225 cm, and spatial periodicity d?=?1.67 cm.     

Synthesis and Crystal Structure of [NiL_2(H_2O)_2](ClO_4)_2L=MBPT=4-P-methylphenyl-3,5-bis-(pyridin-2-yl)-1,2,4-triazole

The substituted l,2,4-triazoles are very useful ligands in coordination chemistry'-'. It isvery interesting that some complexes containing substituted l,2,4-triazoles ligands havethe spin-crossover phenomena, which could be used as magnetic materials4-5. However,complexes containing triaryltriazole ligands have been little known so far. We haverecently synthesized some triaryltriazole compounds'-', and we first report here thesynthesis and crystal structure of [Ni(MBPT),(H,O),](CIO.),.Expe…     

OPTIMAL DYNAMIC HARVEST OF A MOBILE RENEWABLE RESOURCE

Abstract We present a mathematical model for the growth, movement, and harvesting of a renewable resource, and characterize the spatiotemporal distribution of harvest effort which maximizes the present value of harvest (yield) over a finite time horizon. We derive the optimality system for this model and show that the yield‐maximizing solution often includes one or more no‐take reserves that change in size over time. We explore how the results change with varying parameter values. The results inform ongoing debate about the use of reserves, and are increasingly relevant as technology enables enforcement of spatially structured harvest constraints.