Synthesis and characterization of poly(1,4‐bis((E)‐2‐(3‐dodecylthiophen‐2‐yl)vinyl)benzene) derivatives

New amorphous semiconducting copolymers, poly(9,9‐dialkylfluorene)‐alt‐(3‐dodecylthienyl‐divinylbenzene‐3‐dodecylthienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized. The structure of copolymers was confirmed by H NMR, IR, and elemental analysis. The copolymers showed very good solubility in organic solvents and high thermal stability with high T_g of 178–185 °C. The weight average molecular weight was found to be 107,900 with polydispersity of 3.14 for PEFTVB and 76,700 with that of 3.31 for POFTVB. UV–vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB. Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB. The solution‐processed thin‐film transistors showed the carrier mobility of 2 × 10^?4 cm² V^?1 s^?1 for PEFTVB‐based devices and 2 × 10^?5 cm² V^?1 s^?1 for POFTVB‐based devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3942–3949, 2010     

A nanoscale field effect data storage of bipolar endo-fullerenes shuttle device

We investigated the internal dynamics of an electro-fluid shuttle memory element, consisting of K⁺@C₆₀ and F⁻@C₆₀ encapsulated in a C₆₄₀ nanocapsule. Energetics and operating responses of bipolar endo-fullerenes shuttle memory device, (K⁺@C₆₀–F⁻@C₆₀)@C₆₄₀, were examined by classical molecular dynamics simulations under the external force fields.     

High-throughput screening of ferroelectric materials for non-volatile random access memory using multilayer perceptrons

During the last several years, the development of combinatorial technology has enabled synthesis of a huge amount of chemical compounds in a short time. The large number of variables makes the direct human interpretation of data derived from combinatorial experimentation for high-throughput screening (HTS) very difficult. Artificial neural networks using multilayer perceptrons (MLP) have been successfully applied to the regression problems with various material data. In this work, MLP model was applied to HTS of ferroelectric materials including Bi_4−xLa_xTi₃O₁₂ (BLT) and Bi_4−xCe_xTi₃O₁₂ (BCT). The model using MLP was made to predict the ferroelectric properties of whole feasible experimental conditions. Once a neural network model with high accuracy and good generalization performance was established, we could predict the expected optimal reaction conditions with the best characteristics. The highest gradient value obtained using MLP model is higher than the maximum value found from experiments, thereby accelerating the discovery of the optimal compositions and post-annealing time of BCT and BLT.     

A robust variant of the method of contracting compacta

There is presented a modified method of contracting compacta that gives an estimate of the error of approximate solutions of certain ill-posed problems in the case when all initial data are measured with a preassigned exactness.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 43, No. 12, pp. 1693–1696, December, 1991.     

Ruled real hypersurfaces of a complex space form

The purpose of this paper is to define a ruled real hypersurface of a complex space formM _n (c), c≠0, and to give characterizations of this hypersurface by the infinitesimal affine transformation of the structure vector field induced on the hypersurface. Supported by Grant for the Institute of Mathematics, the University of Tsukuba, and TGRC-KOSEF (1993).     

Sasakian manifolds with vanishing C-Bochner curvature tensor

Supported by TGRC-KOSEF.     

Advantages of Adaptive Speckle Filtering Prior to Application of Iterative Deconvolution Methods for Optical Coherent Tomography Imaging

The axial resolution of optical coherence tomography (OCT) is closely related to the light source spectrum width. Unfortunately, most basic sources providing the required power for decent OCT image have narrow spectra, which generate a resolution loss. Assuming the OCT system is linear shift-invariant, we can consider the system output as the convolution of the theoretical signal with a system impulse response due to this spectrum narrowness. It becomes then possible to enhance this resolution through iterative deconvolution methods (IDM). However those methods have a significant drawback, as they usually significantly enhance speckle, which is another consequence of the source spectrum narrowness. To compensate this, we rely on preliminary speckle filtering, and especially the adaptative ones, which allow tackling the speckle without blurring the image. We first studied enhancement proposed by most popular IDMs on OCT images, and then the effect of preliminary adaptive speckle filtering (ASF) by different common adaptive methods. Then, among those methods, we combined Frost filter and Richardson-Lucy deconvolution in the appropriated way; this way we both enhanced resolution by 2 and reduced speckle (raising CNR from 0.7 to 1.3)