Quantum Nernst effect

It is theoretically predicted that the Nernst coefficient is strongly suppressed and the thermal conductance is quantized in the quantum Hall regime of the two-dimensional electron gas. The Nernst effect is the induction of a thermomagnetic electromotive force in the y-direction under a temperature bias in the x-direction and a magnetic field in the z-direction. The quantum nature of the Nernst effect is analyzed with the use of a circulating edge current and is demonstrated numerically. The present system is a physical realization of the non-equilibrium steady state.     

A Narrative Review of Alternate Gait Training Using Knee-ankle-foot Orthosis in Stroke Patients with Severe Hemiparesis

Impairments resulting from stroke lead to persistent difficulties with walking. Subsequently, an improved walking ability is one of the highest priorities for people living with stroke. The degree to which gait can be restored after a stroke is related to both the initial impairment in walking ability and the severity of paresis of the lower extremities. However, there are some patients with severe motor paralysis and a markedly disrupted corticospinal tract who regain their gait function. Recently, several case reports have described the recovery of gait function in stroke patients with severe hemiplegia by providing alternate gait training. Multiple studies have demonstrated that gait training can induce “locomotor-like” coordinated muscle activity of paralyzed lower limbs in people with spinal cord injury. In the present review, we discuss the neural mechanisms of gait, and then we review case reports on the restoration of gait function in stroke patients with severe hemiplegia.     

Soot formation characteristics in a lab-scale turbulent pulverized coal flame with simultaneous planar measurements of laser induced incandescence of soot and Mie scattering of pulverized coal

Soot formation characteristics of a lab-scale pulverized coal flame were investigated by performing carefully controlled laser diagnostics. The spatial distributions of soot volume fraction and the pulverized coal particles were measured simultaneously by laser induced incandescence (LII) and Mie scattering imaging, respectively. In addition, the radial distributions of the soot volume fraction were compared with the OH radical fluorescence, gas temperature and oxygen concentration obtained in our previous studies [1], [2]. The results indicated that the laser pulse fluence used for LII measurement should be carefully controlled to measure the soot volume fraction in pulverized coal flames. To precisely measure the soot volume fraction in pulverized coal flames using LII, it is necessary to adjust the laser pulse fluence so that it is sufficiently high to heat up all the soot particles to the sublimation temperature but also sufficiently low to avoid including a too large of a change in the morphology of the soot particles and the superposition of the LII signal from the pulverized coal particles on that from the soot particles. It was also found that the radial position of the peak LII signal intensity was located between the positions of the peak Mie scattering signal intensity and peak OH radical signal intensity. The region, in which LII signal, OH radical fluorescence and Mie scattering coexisted, expanded with increasing height above the burner port. It was also found that the soot formation in pulverized coal flames was enhanced at locations where the conditions of high temperature, low oxygen concentration and the existence of pulverized coal particles were satisfied simultaneously.     

Synthesis of nano-polycrystalline diamond from glassy carbon at pressures up to 25 GPa

ABSTRACT

Nano-polycrystalline diamond (NPD) with various grain sizes has been synthesized from glassy carbon at pressures 15–25?GPa and temperatures 1700–2300°C using multianvil apparatus. The minimum temperature for the synthesis of pure NPD, below which a small amount of compressed graphite was formed, significantly increased with pressure from ～1700°C at 15?GPa to ～1900°C at 25?GPa. The NPD having grain sizes less than ～50?nm was synthesized at temperatures below ～2000°C at 15?GPa and ～2300°C at 25?GPa, above which significant grain growth was observed. The grain size of NPD decreases with increasing pressure and decreasing temperature, and the pure NPD with grain sizes less than 10?nm is obtained in a limited temperature range around 1800–2000°C, depending on pressure. The pure NPD from glassy carbon is highly transparent and exhibits a granular nano-texture, whose grain size is tunable by selecting adequate pressure and temperature conditions.     

WIDE RANGE DETECTOR USING PARABOLIC CYLINDRICAL MIRROR FOR THz APPLICATIONS

A new, wide-band, high-speed and high-sensitivity THz detector has been developed. The prototype detector consists of a parabolic cylindrical mirror, a long wire antenna and a Schottky barrier diode. Direct detection measurements have shown a stable sensitivity of 150 ± 50 V/W for 1–2 THz without any adjustments. The long wire antenna was fixed at the focus of parabolic cylindrical mirror then it has been realized less operation steps, easy coupling to the external THz signals and a dramatic enhancement in the practicality of this system. The optically polished mirror and frosted surface one showed comparable sensitivities, thus easy polishing and less cost mirror fabrication can be applied for this system. The radiation pattern showed a maximum radiation angle of approximately 23° with its dominant main lobe, which was attributed to the wire antenna character and confirmed good agreements with classical antenna theory.     

Visualization of Magnetization Transfer Effect in Polyethylene Glycol Impregnated Waterlogged Wood

To visualize the condition of impregnation of polyethylene glycol (PEG) in waterlogged wood, we demonstrated magnetic transfer (MT) magnetic resonance imaging (MRI) through a series of process of PEG impregnation. Three different samples were examined; reference wood, 10 cm cut wood, and 5 cm cut wood. During this study, the upper section sample was kept immersed in water, for the middle and lower sections the concentration of PEG solution was changed at 20 wt% intervals from 20 to 100 wt%. The impregnated periods of each PEG solution concentration were 14 days. Then, MR imaging were performed with/without MT pulse. The MTR value for both 10 cm- and 5 cm-samples were shown to decrease at 20 wt% PEG at peak concentration. When the sample volume was large, e.g., 10 cm-sample, the MTR value decreased to 100 wt% PEG concentration. In contrast, when a sample volume was small, e.g., 5 cm-sample, MTR value decreased to 60 wt% PEG concentration. In conclusion, MTR analysis makes it possible to nondestructively visualize and evaluate the inner condition concerning the PEG impregnation method for waterlogged wood.     

Magnetic behavior of Fe0.2Mg0.8TiO3 and Fe0.3Mg0.7TiO3 probed by Mössbauer timescale

Magnetization and Mössbauer measurements have been made on a diluted antiferromagnets Fe_xMg_1?xTiO₃ with x=0.2, 0.3 and 0.7. It has been demonstrated that this system exhibits a spin glass or a reentrant spin glass like behavior in the samples with x around the percolation concenrration x_c≈0.25. It has been shown that various sizes of magnetic clusters are formed well above the transition temperatures determined by the magnetization measurements in the samples with x near x_c. The behavior of Fe_0.2Mg_0.8TiO₃ is discussed as a typical cluster glass.     

Electrochemical formation of porous superlattices on n-type (1 0 0) InP

The present work deals with the electrochemical formation of superlattice structures on n-type (1 0 0) InP in HCl solutions. The superlattices consist of a stack of two layers with alternating high and low porosity on n-type material obtained by changing the anodizing current or the potential periodically in HCl solutions. The superlattice structures were characterized by scanning electron microscopy. The pore morphology and structure depend strongly on the electrochemical conditions. For anodization with low currents (e.g., 1 or 10 mA) or at low potentials (e.g., 1.5 V_Ag/AgCl), a porous layer with a facet-like structure was formed. For higher currents or potentials, such as 50 or 100 mA or 3 V_Ag/AgCl, respectively, a tree-like structure with random and/or tangled branches was observed. Finally, samples anodized at 5 V_Ag/AgCl, show a porous layer with a regular array of straight pores. The morphology and structure of the stacks of the porous layers can be controlled in the nanometer range, depending on the electrochemical conditions.     

Three-dimensional athermal waveguide at 1.3 μm wavelength for temperature independent lightwave devices

To eliminate the temperature dependence of narrow-band filter, a three-dimensional athermal waveguide of which optical path length is independent of temperature was developed at 1.3 μm wavelength. The temperature coefficient of the refractive index of films made of glass materials was measured at this wavelength, and a strip-loaded athermal waveguide was designed using a scalar finite element method. The temperature coefficient of optical path length was successfully decreased to 9.65X10^-9[/K] (0.1% of the conventional waveguide).     

Simultaneous Measurement of Individual ATPase and Mechanical Reactions by a Single Myosin Molecule at Work

Based on techniques for single molecule imaging and nanomanipulation by optical tweezers, we have developed a new technique that allows simultaneous measurement of individual ATPase and mechanical reactions from a single myosin molecule during force generation. We show how the ATPase reaction couples to the mechanical reaction directly at the single molecule level. The results show that the myosin head can produce force even after releasing the bound nucleotide, probably ADP, suggesting that the chemical energy driven by ATP hydrolysis can be hysteretically stored in the myosin molecule. This view does not support a widely accepted hypothesis in which the force generation is tightly coupled to ligand dissociation.This paper was originally presented as an invited paper at the seventh Meeting on Near Field Optics, which was held on July 1, 1998 at Nagoya University, Nagoya, organized by the Research Group on Near Field Optics of the Optical Society of Japan, an affiliate of the Japan Society of Applied Physics.