Application of chitosan solutions gelled by melB tyrosinase to water‐resistant adhesives

An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenethylamine (dopamine). The tyrosinase‐catalyzed reaction with dopamine conferred water‐resistant adhesive properties to the semi‐dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase‐catalyzed quinone conversion and the subsequent nonenzymatic reactions of o‐quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel‐like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microstructure of magnesium fluoride films deposited by boat evaporation at 193 nm

Single layer magnesium fluoride (MgF2) was deposited on fused-silica substrates by a molybdenum boat evaporation process at 193 nm. The formation of various microstructures in relation to the different substrate temperatures and deposition rates were investigated. The relation between these microstructures (including cross-sectional morphology, surface roughness, and crystalline structures), the optical properties (including refractive index and optical loss) and stress, were all investigated. It was found that the laser-induced damage threshold (LIDT) would be affected by the microstructure, optical loss, and stress of the thin film. To obtain a larger LIDT value and better optical characteristics, MgF2 films should be deposited at a high substrate temperature (300 degrees C) and at a low deposition rate (0.05 nm s(-1)).     

A combined environmental straining specimen holder for high-voltage electron microscopy

A novel specimen holder that enables in situ observation of crack-tip deformation and/or fracture under a controlled environment is developed for a high-voltage electron microscope (HVEM). A window-type environmental cell (EC) that incorporates a uniaxial straining apparatus is built into a side-entry-type single-tilt specimen holder. The gas control in EC, straining apparatus design, limited field of view for crack-tip observation, and specimen preparation for the specimen holder are presented in detail. Experimental results successfully demonstrate that the developed specimen holder is quite useful for the dynamic observation of crack-tip deformation and/or fracture subjected to a hostile environment, such as hydrogen gas.     

不同摩尔质量聚碳酸酯的增韧改性

研究了弹性体SEBS（苯乙烯-乙烯/丁烯-苯乙烯共混物）和SEP（苯乙烯-乙烯/丙烯共混物）的加入对不同摩尔质量聚碳酸酯（PC）力学性能的影响.对于通用级PC及低摩尔质量的PC,其缺口冲击强度随样品厚度增加大幅度降低,而少量弹性体（SEPTON 1003、SEPTON 8006）的加入使其6.4 mm厚样品缺口冲击强度有大幅度的提高,其它的力学性能如拉伸强度等变化不大.SEM和DSC分析表明：SEPTON与PC的相容性较好,共混物由PC明显的脆性断裂转变为韧性断裂.     

A MATHEMATICAL MODEL THAT LEARNS AN ADAPTIVELY GENERATED NOVEL PATTERN IN QUADRUPED LOCOMOTION

Quadrupeds show several locomotion patterns when adapting to environmental conditions. An immediate transition among walk, trot, and gallop implies the existence of a memory for locomotion patterns. In this article, we postulate that motion pattern learning necessitates the repetitive presentation of the same environmental conditions and aim at constructing a mathematical model for new pattern learning. The model construction considers a decerebrate cat experiment in which only the left forelimb is driven at higher speed by a belt on a treadmill. A central pattern generator (CPG) model that qualitatively describes this decerebrate cat's behavior has already been proposed. In developing this model, we introduce a memory mechanism to store the locomotion pattern, where the memory is represented as the minimal point of the potential function. The recollection process is described as a gradient system of this potential function, while in the memorization process a new pattern learning is regarded as a new minimal point generation by the bifurcation from an already existing minimal point. Finally, we discuss the generalization of this model to motion adaptation and learning.     

Early damaged area estimation system using DMSP-OLS night-time imagery

The disaster information system, the Early Damaged Area Estimation System (EDES), was developed to estimate damaged areas of natural disaster using the night-time imagery of the Defense Meteorological Satellite Program Operational Linescan System (DMSP-OLS). The system employs two estimation methods to detect the city lights loss or reduction as possible impacted areas; one is the bi-temporal images (BTI) method and the other is the time-series images (TSI) method. Both methods are based on significance tests assuming that brightness of city lights fluctuates as normal random variables, and the BTI method is simplified by introducing the assumption that the standard deviation of city lights fluctuation is constant. The validity of the estimation method is discussed based on the result of the application to the 2001 Western India earthquake disaster. The estimation results identify the damaged areas distant from the epicentre fairly well, especially when using the TSI method. The system is designed to estimate the global urban damage and to provide geographic information through the Internet within 24?h after a severe disaster event. The information is expected to support the disaster response and relief activities of governments and non-governmental organizations.     

The Design and Implementation of the Massively Parallel Processor Based on the Matrix Architecture

This paper describes the design and implementation of the massively parallel processor based on the matrix architecture which is suitable for portable multimedia applications. The proposed architecture in this paper achieves the high performance of 40 GOPS in the case of consecutive fixed-point 16-bit additions at 200MHz clock frequency and the small power dissipation of 250mW. In addition, 1Mbit SRAM for data registers and 2048 2-bit-grained processing elements connected by a flexible switching network are integrated in the small area of 3.1 mm ² in 90nm CMOS low standby technology. These design techniques and architectures described in this paper are attractive for realizing area-efficient, energy-efficient, and high-performance multimedia processors