The role of grain-boundary on the hydrogen-induced degradation inthin-film ferroelectric capacitors

The electrical properties of thin-film ferroelectric capacitors are known to degrade severely when exposed to hydrogen. In this study, we directly measured the effects of the grain boundary on the hydrogen-induced degradation in ferroelectric Pb(Zr, Ti)O₃ (PZT) thin films by the location of the top Pt electrode either inside the grains or at the grain boundary. A strong relationship between the grain boundary and the electrical properties of ferroelectric capacitors as a result of hydrogen annealing was found. The degradation of the electrical properties in thin-film ferroelectric capacitors after hydrogen annealing is mainly due to the presence of the grain boundary in the ferroelectric thin film     

Study of the growth of YBa2Cu3O7−x films on a Al2O3 single crystal with a CeO2 buffer sublayer

Superconducting YBa₂Cu₃O_7−x films were prepared by magnetron sputtering on Al₂O₃ single crystals with a CeO₂ sublayer. Scattering of moderate-energy ions and x-ray diffraction were used to show that the films exhibit good single-crystal properties over the entire thickness up to 2.6 μm. The hypothesis is advanced that the indentations formed by the growth of films above “extraneous” phase grains may act as defect sinks. Pis’ma Zh. Tekh. Fiz. 24, 91–95 (January 12, 1998)     

A vertical and floor line-based monocular SLAM system for corridor environments

In this paper, we propose a vertical and floor line-based monocular simultaneous localization and mapping (SLAM) system which utilizes vertical lines, floor lines, and vanishing points as sensory input to perform robust SLAM in corridor environments. By combining three map feature types, our design can help a robot to perform accurate pose estimation, repeatable loop closure, and to construct a more expressive environmental map. As a primitive element of a geometric structure, a line segment has one additional dimension compared to a point feature, thereby allowing the use of line segments to easily represent a geometric structure using a smaller number of features. This system presents map features on a 2D ground space: the vertical line as a projection point, the floor line as the original line, and the vanishing point as a directional vector. Although the vertical line, floor line, and vanishing point use different parameterization and initialization methods, their measurement models are integrated into a unified extended Kalman filter (EKF) framework. Experimental results show that our system can be deployed in a structured indoor environment as a suitable SLAM solution.     

Effect of hydrogen on the impedance of passivating oxide films formed on aluminium in sodium nitrate solution

A.c. impedance has been determined at room temperature on hydrogen-free and hydrogen-charged passivating oxide films on aluminium in 0.05m Na₂SO₄ solution. Analysis of the impedance data enabled a clear distinction between the capacitance and inductance of the hydrogen-free oxide film and those of the hydrogen-charged oxide film to be made. The changes in capacitance and inductance by hydrogen-charging into the oxide films are discussed in relation to the compositional change from -Al₂O₃ to hydrated alumina.     

Local Protein Translation and RNA Processing of Synaptic Proteins in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a heritable neurodevelopmental condition associated with impairments in social interaction, communication and repetitive behaviors. While the underlying disease mechanisms remain to be fully elucidated, dysfunction of neuronal plasticity and local translation control have emerged as key points of interest. Translation of mRNAs for critical synaptic proteins are negatively regulated by Fragile X mental retardation protein (FMRP), which is lost in the most common single-gene disorder associated with ASD. Numerous studies have shown that mRNA transport, RNA metabolism, and translation of synaptic proteins are important for neuronal health, synaptic plasticity, and learning and memory. Accordingly, dysfunction of these mechanisms may contribute to the abnormal brain function observed in individuals with autism spectrum disorder (ASD). In this review, we summarize recent studies about local translation and mRNA processing of synaptic proteins and discuss how perturbations of these processes may be related to the pathophysiology of ASD.     

Synergistic Flame Retardant Effects of Carbon Nanotube-Based Multilayer Nanocoatings

In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers.     

A kinetic study on medium temperature desulfurization using a natural manganese ore

Natural manganese ores were selected as raw materials for the desulfurization sorbent because of economical efficiency and high reactivity on hydrogen sulfide. Initial reaction rates between H₂S and desulfurization sorbent of natural manganese ores were determined in a temperature range of 400-800°C using a thermobalance reactor. All reactions were first order with respect to H₂S and were expressed by the Arrhenius relation. When the sulfidation reaction was controlled by diffusion, the temperature dependence of the effective diffusivity was given by the Arrhenius equation. Activation energies and frequency factors were obtained from the product layer diffusion coefficient of various sorbents by plotting as an Arrhenius equation form. Several additives were mixed to improve the sulfidation capacity, and NiO was the best additive.     

Preparation and characterization of syndiotactic polystyrene/ethylene‐propylene copolymer blends

The reactive compatibilization of syndiotactic polystyrene (sPS)/oxazoline‐styrene copolymer (RPS)/maleic anhydride grafted ethylene‐propylene copolymer (EPR‐MA) blends is investigated in this study. First, the miscibility of sPS/RPS blends is examined by thermal analysis. The cold crystallization peak (T_cc) moved toward higher temperature with increased PRS, and, concerning enthalpy relaxation behaviors, only a single enthalpy relation peak was found in all aged samples. These results indicate that the sPS/RPS blend is miscible along the various compositions and RPS can be used in the reactive compatibilization of sPS/RPS/EPR‐MA blends. The reactive compatibilized sPS/RPS/EPR‐MA blends showed finer morphology than sPS/EPR‐MA physical blends and higher storage modulus (G') and complex viscosity (η*) when RPS contents were increased. Moreover, the impact strength of sPS/RPS/EPR‐MA increased significantly compared to sPS/EPR‐MA blend, and SEM micrographs after impact testing show that the sPS/RPS/EPR‐MA blend has better adhesion between the sPS matrix and the dispersed EPR‐MA phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2084–2091, 2002