High‐mobility solution‐processed organic thin‐film transistor array for active‐matrix color liquid‐crystal displays

Abstract— A solution‐processed organic thin‐film‐transistor array to drive a 5‐in.‐diagonal liquid‐crystal display has been fabricated, where semiconductor films, a gate dielectric film, and passivation films have all been formed using solution processes. A field‐effect mobility of 1.6 cm²/V‐sec, which is among the highest for solution‐processed organic thin‐film transistors ever reported, was obtained. This result is due to semiconductor material with large‐grain‐sized pentacene crystals formed from a solution and adoption of three‐layered passivation films that minimize the performance degradation of organic thin‐film transistors.     

Gel shrinking resulting from uneven distribution of ionic micelles between the inside and the outside of the polymer gel network

The volume change of crosslinked nonionic poly (N‐isopropylacrylamide) (NIPA) polymer gel immersed in tetradecyldimethylaminoxide (C14DMAO) surfactant solutions at 0.1M NaCl, were investigated to distinguish between binding and nonbinding polymer gel/C14DMAO surfactants. Also, the aggregation behavior of C14DMAO surfactants the inside and the outside the polymer hydrogels has been studied through solubilization of Sudan III dye. For the C14DMAO surfactants at the degrees of ionization (α) of 0.5 and 1, they bind to the NIPA gel at low surfactant concentration (C_D) that enhance the gel swelling due mainly to the osmotic pressure contribution from the counter ions (regime I, C_D<10mM). However, the deswelling behavior was observed as the surfactant concentration increases above 10 mM (regime II). The solubilization experiments indicated that the surfactant concentration inside the gel is lower than that outside the gel in the regime II, which may be due to the large micelle size that cannot accommodate the mesh size of the gel. It was suggested that the uneven distribution of the ionic micelles leads to the reduction of the net swelling osmotic pressure of the gel (i.e., the decrease of the gel volume). In the case of the nonionic C14DMAO at α = 0, on the other hand, the deswelling behavior was not clearly observed and the surfactant concentration inside the gel and outside the gel was almost identical even at 30 mM. For the nonionic surfactant, it was also found that the gel volume increases with the surfactant concentration at low surfactant concentration less than 1mM. This may be attribute to the dipole‐dipole repulsion of N‐O headgroups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2001–2006, 2004     

Crystallization behavior of polypropylene filled with surface-modified calcium carbonate

Polypropylene (PP) and calcium carbonate (CaCO₃) were mixed in a two-roll mill. The mixed compounds were molded on the plate by using a compression press heater. To improve the affinity of the relation between CaCO₃ and the PP matrix, we modified the CaCO₃ surface through chemical reaction with alkyl dihydrogen phosphates. The CaCO₃ content and size modification affected the crystallization behavior of the filled PP composites. The crystallization temperature in the nonisothermal crystallization process increased with the increase of CaCO₃ content and the decrease of CaCO₃ size. The crystallization temperature revealed the function of log (1 + T_s) (T_s, total surface area of CaCO₃) irrespective of CaCO₃ content and size for modified and unmodified systems, respectively. The shoulder or double crystallization peak of PP composites is recognized for the unmodified system (particle sizes: 1.0 and 4.5 μm).     

Automated synthesis of radiopharmaceuticals for PET: an apparatus for [1-11C]labelled aldoses

This paper describes an instrumentation system for positron emission tomography (PET). A variety of [1-¹¹C]labelled aldoses, such as [1-¹¹C]-D-glucose, and galactose by a modification of the Kiliani-Fischer method have been produced. The instrumentation is fully automatic and consists of a synthesis system and control system. The synthesis system has the following functions: supplying reagents; performing reactions; purifying ¹¹C labelled aldose; and preparing an injectable solution of ¹¹C labelled aldose. These operations are performed by the control system in a remote control room. In a preliminary, hot experiment an injectable solution of [1-¹¹C]-D-glucose was obtained. In addition, the operator is exposed to minimal radiation. The radioactivity of [1-¹¹C]-Dglucose was 47 MBq, and the preparation time was 49 min.     

Single-walled carbon nanotubes grown on natural minerals

Single-walled carbon nanotubes (SWNTs) are successfully grown on magnesite crystal by pyrolysis of methane gas under moderate conditions, demonstrating the possibility of naturally occurring SWNTs.The obtained SWNTs were analyzed by Raman scattering, transmission electron microscope (TEM), and thermogravimetric (TG) measurements. These measurements revealed that high purity SWNTs having diameters of about 1-1.8 nm occur on the surface of natural magnesite sample by the pyrolysis of methane gas at 1073-1173 K. Structural properties and formation mechanism of the obtained SWNTs were discussed.     

Kinetic Study of Metal-Catalyzed Reaction of Solid Calcium Oxide with Gas Mixtures of Methane and Water Vapor to Form Hydrogen

With noble metal catalysts (Pd, Pt, Rh, Ir) present, hydrogen is formed by the interaction of solid calcium oxide with gas mixtures of methane and water vapor, according to CaO + CH₄ + 2H₂O CaCO₃ + 4H₂. Among the metals, Ir and Rh are so active that the reaction takes place at temperatures as low as 600 K. Rate data obtained with these metals show a nearly first order with respect to CH₄ pressure, while a negative order with respect to H₂O vapor pressure. The apparent activation energies are 171 and 217 kJ/mol for the Ir- and Rh-catalyzed reactions, respectively. On the other hand, Ni does not catalyze the reaction below 733 K, probably due to its strong interaction with H₂O vapor.     

XRD and TEM study of high pressure treated single-walled carbon nanotubes and C60-peapods

In situ synchrotron X-ray diffraction measurements of single-walled carbon nanotube and C₆₀-peapod samples under high pressures up to 13 GPa and at high temperature were carried out. Anisotropical shrinkages of their bundle two-dimensional lattices by compression at room temperature were observed. It was found that the lattices recover original forms reversibly upon pressure release. It was also found that irreversible phase transformations occur by raising temperature at the highest pressure. The high pressure and high temperature treated samples were examined by X-ray diffraction, transmission electron microscope, and Raman measurements. It was indicated by transmission electron microscope observation that hexagonal diamond is able to be synthesized by high pressure and high temperature treatment of C₆₀-peapods.     

Current‐Induced Nucleation and Annihilation of Magnetic Skyrmions at Room Temperature in a Chiral Magnet

A magnetic skyrmion is a nanometer‐scale magnetic vortex carrying an integer topological charge. Skyrmions show a promise for potential application in low‐power‐consumption and high‐density memory devices. To promote their use in applications, it is attempted to control the existence of skyrmions using low electric currents at room temperature (RT). This study presents real‐space observations for the current‐induced formation and annihilation of a skyrmion lattice (SkL) as well as isolated skyrmions in a microdevice composed of a thin chiral magnet Co₈Zn₉Mn₃ with a Curie temperature, T _C ≈ 325 K, above RT. It is found that the critical current for the manipulation of Bloch‐type skyrmions is on the order of 10⁸ A m^?2, approximately three orders of magnitude lower than that needed for the creation and drive of ferromagnetic (FM) domain walls in thin FM films. The in situ real‐space imaging also demonstrates the dynamical topological transition from a helical or conical structure to a SkL induced by the flow of DC current, thus paving the way for the electrical control of magnetic skyrmions.     

An investigation of cavity growth in a superplastic aluminum alloy processed by ECAP

Quantitative measurements were taken to evaluate the significance of cavitation in the tensile testing of a superplastic spray-cast Al-7034 alloy processed by equal-channel angular pressing (ECAP). Samples were processed by ECAP and then tested in tension at 673 K using strain rates from 10⁻³ to 10⁻¹ s⁻¹. For comparison purposes, similar tensile testing was conducted also on samples without ECAP processing. Inspection of polished sections after tensile testing revealed extensive internal cavitation in all samples. Measurements were taken to provide detailed information on the sizes and shapes of the cavities and these measurements were analyzed to determine the dominant cavity growth mechanisms. The results demonstrate the importance of superplastic diffusion growth in ultrafine-grained materials processed by ECAP.     

An analysis of expression data using a support vector machine and dimensional reduction methods

Gene expression data are expected to be a significant aid in the development of efficient cancer diagnosis and classification platforms. However, gene expression data are high-dimensional and the number of samples is small in comparison to the dimensions of the data. Furthermore, the data are inherently noisy. Therefore, in order to improve the accuracy of the classifiers, we would be better off reducing the dimensionality of the data. As a method of dimensionality reduction, there are two previous proposals: feature selection and dimensionality reduction. Feature selection is a feedback method which incorporate the classifier algorithm in the future selection process. Dimensionality reduction refers to algorithms and techniques which create new attributes as combinations of the original attributes in order to reduce the dimensionality of a data set. In this article, we compared the feature selection methods and the dimensionality reduction methods, and verified the effectiveness of both types. For the feature selection methods we used one previously known method and three proposed methods, and for the dimensionality reduction methods we used one previously known method and one proposed method. From an experiment using a benchmark data set, we confirmed the effectiveness of our proposed method with each type of dimensional reduction method.