Analysis of XANES for identification of highly dispersed transition metal oxides on supports

XANES of vanadium and niobium oxide on silica or alumina have been analyzed quantitatively by a deconvolution technique. Based on the results for reference compounds, local structures of supported vanadium and niobium species were identified. The composition was estimated from difference spectra for the samples which consisted of two kinds of species.     

Acoustic wave propagation in disordered microscale granular media under compression

We investigate the effect of dynamic and uniaxial static loading on the wave speeds and rise times of laser generated acoustic waves traveling through a disordered, multilayer aggregate of 2 \(\mu {\mathrm {m}}\) diameter silica microspheres, where the excited dynamic amplitudes are estimated to approach the level of the static overlap between the particles caused by adhesion and externally applied loads. Two cases are studied: a case where the as-fabricated particle network is retained, and a case where the static load has been increased to the point where the aggregate collapses and a rearrangement of the particle network occurs. We observe increases in wave speeds with static loading significantly lower than, and in approximate agreement with, predictions from models based on Hertzian contact mechanics for the pre- and post-collapse states, respectively. The measured rise time of the leading pulse is found to decrease with increasing static load in both cases, which we attribute to decreased scattering and stiffening of the contact network. Finally, we observe an increase in wave speed with increased excitation amplitude that depends on static loading, and whether the system is in the pre- or post-collapse state. The wave speed dependence on amplitude and static load is found to be in qualitative agreement with a one-dimensional discrete model of adhesive spheres, although the observed difference between pre- and post-collapse states is not captured. This investigation, and the approach presented herein, may find use in future studies of the contact mechanics and dynamics of adhesive microgranular systems.     

Structural analysis of Ti-Fe thin films prepared by pulsed laser deposition

Titanium iron oxide (Ti-Fe-O) thin films have been successfully deposited by pulsed laser deposition (PLD). Experiments were carried out by using some targets. One was a Ti-50 at.% Fe-sintered target, while the others were Ti and Fe plates with various surface area ratio [S_R=S_Fe/(S_Fe+S_Ti)] from 30 to 70%. The thin films were analyzed by X-ray diffractometry, Rutherford backscattering spectroscopy (RBS) and transmission electron microscopy (TEM). From XRD analysis, the main phase in the thin films deposited at S_R=30 and 50% was β-Ti (Fe). By increasing S_R to 70%, the main phase of the thin film changed to TiFe. By phase diagram, composition of TiFe must be between Ti-47.5-50.3 at.% Fe at a temperature of 1085 °C. However, the composition of the thin film deposited at S_R=70% was found to be Ti_0.15Fe_0.62O_0.23. Thus, the composition of Fe in the thin film was much greater than the solubility limit. This fact suggests two possibilities. One is that the thin films, which we have deposited, were in a metastable state. The other is that metal oxides of amorphous state could be contained in the thin film.     

Polypropylene plasticization and photodegradation with a TiO2/poly(ethylene oxide)/methyl linoleate paint photocatalyst system

The photodegradation of polypropylene (PP) film was performed by a TiO₂/polyethylene oxide (PEO)/plant oil paint photocatalyst system. The photodegradation underwent two stages of development as follows: Initially PP reacted with linoleic acid radical originated from the photoreaction of plant oil component. Second, the linoleic acid graft‐polymer was decomposed, and then PP chain scission was caused. The process was studied using methyl linoleate (ML) in detail. The melting point of the 24 h‐photodegraded PP slightly decreased, and those of the 48 h‐ and 96 h‐ones drastically did as compared with the pristine PP. The crystallinity (χ_c) decreased at the 48 h photodegradation time and drastically increased at the 96 h one. The 24 h‐photodegraded PP showed the 77% Young's modulus, 88% tensile strength, and 103% strain at break values to those of the pristine PP. The ML graft‐polymerization and decomposition brought about the PP plasticizing and chemi‐crystallization, causing the PP degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39909.     

Analog Circuit Design Methodology in a Low Power RISC Microprocessor

There are various kinds of analog CMOS circuits in microprocessors. IOs, clock distribution circuits including PLL, memories are the main analog circuits. The circuit techniques to achieve low power dissipation combined with high performance in newest prototype chip in the Super H RISC engines are described. A TLB delay can be decreased by using a CAM with a differential amplifier to generate the match signal. The accelerator circuit also helps to speed up the TLB circuit, enabling single-cycle operation. A fabricated 96-mm² test chip with the super H architecture using 0.35-m four metal CMOS technology is capable of 167-MHz operation at 300 Dhrystone MIPS with 2.0-W power dissipation.     

EEG topography recognition by neural networks

Electroencephalography (EEG) pattern-recognition studies were carried out using EEG topography (readiness potential, or RP, spatiotemporal patterns) generated the moment before voluntary movements of muscles. RPs generated prior to pronouncing syllables and controlling a joystick were studied by experiments and simulation. The spatiotemporal patterns of RPs were measured by multichannel surface electrodes pasted on the subject's scalp. Backpropagation neural networks were used for RP pattern recognition. The results show that RPs generated prior to syllable pronouncement contain some information about those syllables, and that RPs generated prior to joy stick movements contain information on the direction of intended movement. They also show that neural networks can be used to recognize EEG information and so create a new type of man-machine interface for data input.     

A comparative study on the thermally enhanced reorientation between random and diblock methacrylate copolymers with photo-cross-linkable mesogenic side groups by irradiating with linearly polarized ultraviolet light

The thermally enhanced photoinduced reorientation behavior of random and diblock copolymer films of methyl methacrylate and methacrylate with a photo-cross-linkable 4-(4-methoxycinnamoyloxy)biphenyl (MCB) side groups was investigated by irradiating with linearly polarized ultraviolet light and subsequently annealing. Random copolymers were synthesized by free radical copolymerization, while diblock ones were obtained by an atom transfer radical polymerization method with a PMMA macroinitiator. The photoinduced optical anisotropy was thermally amplified when the copolymer exhibited a liquid crystalline phase. The random copolymers with a high composition of MCB side groups reverted the orientation direction and inhibited molecular aggregation. For the diblock copolymers, the reorientation behavior was analogous to the methacrylate homopolymer with MCB side groups and transmission electron microscopy revealed a phase separation structure with molecular orientation of the MCB groups.     

跳跃式移动机构的移动机理及实验研究

介绍了一种新型跳跃式移动机构,阐述了该机构的移动机理及其控制方法.跳跃式移动机构采用小型振动电机作为驱动,利用电机内偏心轮的旋转所产生的周期性的向心力及与工作表面的间歇性摩擦力的共同作用,实现机构的跳跃移动,两个不同放置位置的电机的组合运用,可实现机构可调速的直线运动和回转运动,通过一系列实验.验证了跳跃式移动机构可实现二维平面内的自由移动.