Postfunctionalization of aromatic polyamine by [2+2] cycloaddition of 7,7,8,8-tetracyanoquinodimethane with side chain alkynes

Electron-rich, side chain alkynes of an aromatic polyamine were functionalized by a [2+2] cycloaddition, followed by retro-cyclization with the electron-accepting 7,7,8,8-tetracyanoquinodimethane (TCNQ). ¹H NMR studies were used to optimize the reaction conditions. Mild heating to >50?°C afforded the postfunctionalized aromatic polyamines with the desired acceptor amounts. The quantitative TCNQ addition was demonstrated by the MALDI-TOF mass spectrum and elemental analysis. Introduction of the cyano-based acceptor moieties into the polymer side chains resulted in unusually strong intermolecular interactions. In addition to the ?ШC?? interactions of the extended acceptor moieties, these intermolecular forces were supposed to improve the thermal stability of the aromatic polymers. Furthermore, the donor?Cacceptor chromophores formed by this postfunctionalization displayed low energy charge-transfer bands and redox activities in both the anodic and cathodic directions. The straightforward postfunctionalization technique using the alkyne?CTCNQ addition is useful for the preparation of narrow band gap polymers in one step.     

Piezoelectric properties of langasite group based on the ionic size of cation

As langasite A₃BC₃D₂O₁₄ compounds group with piezoelectric properties has no phase transition up to the melting point of 1400–1500 °C, they have been applied for the combustion pressure sensor. As they also have a larger electromechanical coupling factor compared to quartz and nearly the same temperature stability as quartz, the surface acoustic wave (SAW) filters are expected based on the digital transformation of wider bandwidth and higher-bit rates. In the case of three-element compounds such as [R₃]_A[Ga]_B[Ga₃]_C[GaSi]_DO₁₄ (R=La, Pr and Nd), the piezoelectric constant increases with the ionic radius R. In the case of four-element compounds such as [A₃]_A[B]_B[Ga₃]_C[Si₂]_DO₁₄ (A=Ca or Sr, B=Ta or Nb), |d₁₁| and k₁₂ values as a function of A_L/B_L ratio showed a linear relationship completely. There are two effects for the substitutions of A- and B-site cations: the substitution of Sr for Ca brings expansion toward [100] and enlargement in |d₁₁| and k₁₂. On the other hand, as the substitution of Ta for Nb brings not much change, the properties are similar. In this study, five-element compounds such as La_3?xSr_xTa_yGa_5?x+ySi_1+x?2yO₁₄ (0≤x≤3, 0≤y≤1) solid solutions analysed by a single crystal X-ray diffraction are compared with the three- and four-element compounds on the coordinates of oxygen ions. As the coordinates positions are located on the extended line of coordinate positions on the three-element compounds as increasing ionic radius of R-ions in A-site, the piezoelectric properties |d₁₁| and k₁₂ are expected become large.     

A consistent grayscale‐free topology optimization method using the level‐set method and zero‐level boundary tracking mesh

This paper proposes a level‐set based topology optimization method incorporating a boundary tracking mesh generating method and nonlinear programming. Because the boundary tracking mesh is always conformed to the structural boundary, good approximation to the boundary is maintained during optimization; therefore, structural design problems are solved completely without grayscale material. Previously, we introduced the boundary tracking mesh generating method into level‐set based topology optimization and updated the design variables by solving the level‐set equation. In order to adapt our previous method to general structural optimization frameworks, the incorporation of the method with nonlinear programming is investigated in this paper. To successfully incorporate nonlinear programming, the optimization problem is regularized using a double‐well potential. Furthermore, the sensitivities with respect to the design variables are strictly derived to maintain consistency in mathematical programming. We expect the investigation to open up a new class of grayscale‐free topology optimization. The usefulness of the proposed method is demonstrated using several numerical examples targeting two‐dimensional compliant mechanism and metallic waveguide design problems. Copyright © 2014 John Wiley & Sons, Ltd.     

General topology optimization method with continuous and discrete orientation design using isoparametric projection

A general topology optimization method, which is capable of simultaneous design of density and orientation of anisotropic material, is proposed by introducing orientation design variables in addition to the density design variable. In this work, the Cartesian components of the orientation vector are utilized as the orientation design variables. The proposed method supports continuous orientation design, which is out of the scope of discrete material optimization approaches, as well as design using discrete angle sets. The advantage of this approach is that vector element representation is less likely to fail into local optima because it depends less on designs of former steps, especially compared with using the angle as a design variable (Continuous Fiber Angle Optimization) by providing a flexible path from one angle to another with relaxation of orientation design space. An additional advantage is that it is compatible with various projection or filtering methods such as sensitivity filters and density filters because it is free from unphysical bound or discontinuity such as the one at θ = 2π and θ = 0 seen with direct angle representation. One complication of Cartesian component representation is the point‐wise quadratic bound of the design variables; that is, each pair of element values has to reside in a given circular bound. To overcome this issue, we propose an isoparametric projection method, which transforms box bounds into circular bounds by a coordinate transformation with isoparametric shape functions without having the singular point that is seen at the origin with polar coordinate representation. A new topology optimization method is built by taking advantage of the aforementioned features and modern topology optimization techniques. Several numerical examples are provided to demonstrate its capability. Copyright © 2014 John Wiley & Sons, Ltd.     

Characterization of alternative plasticizers in poly(vinyl chloride) sheets for blood containers

This study aimed to optimize the ratio of dioctyl 4‐cyclohexene‐1,2‐dicarboxylate (DOTH) and di‐isononyl‐cyclohexane‐1,2‐dicarboxylate (DINCH^®) for use as plasticizers in poly(vinyl chloride) (PVC) sheets. We also evaluated the biological safety of DOTH for its potential to be part of a safe PVC‐based blood container. The suppression of hemolysis in mannitol‐adenine‐phosphate / red cell concentrates (MAP/RCC) with DOTH/(DINCH^®‐PVC) sheets and the elution of plasticizers from the sheets increased with higher DOTH compositions. The properties of the PVC sheet containing DOTH and DINCH^® in the ratio of 25:33 parts against PVC 100 parts as a weight were almost identical to the PVC sheet made of di(2‐ethylhexyl) phthalate. From a subchronic toxicity test, DOTH did not show any adverse effects on all organs, including the testes, epididymis, liver, and kidneys. The no‐observed‐adverse‐effect level was 300 mg/kg body weight/day in a rat. These results suggest that DOTH/DINCH^® (25:33) is a promising candidate for the replacement of di(2‐ethylhexyl) phthalate in blood containers. J. VINYL ADDIT. TECHNOL., 22:520–528, 2016. © 2015 Society of Plastics Engineers     

Oil film behavior under minute vibrating conditions in EHL point contacts

The oil film thickness was measured under conditions of minute vibrations using an elastohydrodynamic lubrication (EHL) ball-on-disk test rig. Poly-alpha-olefin (PAO) oil was used as the lubricant under conditions of pure sliding where only the ball specimen was minutely vibrated. It was found that an oil film formed when the amplitude ratio was greater than 1.6. Moreover, when conditions were changed to the maximum vibrating speed, oil viscosity, and maximum contact pressure, the critical amplitude ratio at which the oil film began to form remained at 1.6. Consequently, calculated results showed that the oil film was formed when the amplitude ratio was π/2 (nearly equal to 1.6), which closely agreed with our test results.     

Effect of axial reflector on radial uniformity in neutron transmutation doping of silicon

Significant axial variation of radial uniformity is observed in Si-ingot neutron transmutation doping in the flux screening method, and leads to non-uniform resistivity distribution for a certain part of Si-ingot. This axial variation of radial uniformity is caused by the installation of a partial neutron screen which decreases the reaction rates differently in the center and surface at the region not surrounded by the partial neutron screen. For the improvement of the specific distribution of radial uniformity in the axial direction, a new concept of axial reflector is introduced to partly change the reaction rate at a certain region of Si-ingot, and neutron irradiation experiments are carried out at the heavy water neutron irradiation facility in the Kyoto University Research Reactor. Based on the experimental and numerical results, the new axial reflector is proved to be effective for improving the axial variation of radial uniformity.