Analytical method for beta-amyloid fibrils using CE-laser induced fluorescence and its application to screening for inhibitors of beta-amyloid protein aggregation

More than 20 million people are suffering from Alzheimer's disease, and the number of patients will dramatically increase with the arrival of an aging society unless preventive or curative medications are discovered. A fast and sensitive analytical method for beta-amyloid (Abeta) aggregates was developed by the combination of CE-laser induced fluorescence and the fluorescence reagent, thioflavine T. The developed method separates two different fibrils within 5 min. The first peak, which migrated at approximately 4 min, was supposed to be derived from a precursor of a fibril that migrated at approximately 3.5 min. The developed method was also applicable to the high-throughput screening of the Abeta aggregation inhibitors, which was expected to be an effective therapeutic agent candidate of Alzheimer's disease. Three compounds (daunomycin, 3-indolepropionic acid (3-IPA), melatonin) were used for the assay. The order of the antiaggregation activity of these compounds was daunomycin > 3-IPA > melatonin, which was the same as that of the reported one. These results suggest that this analytical method may be used to analyze the Abeta fibrils and identify potential therapeutic agents for the treatment of Alzheimer's disease.     

Prevention of melanin formation by yeast cerebroside in B16 mouse melanoma cells

The effects of plant and yeast cerebrosides on melanin formation were examined in B16 mouse melanoma cells. Addition of yeast cerebroside significantly reduced melanin content to the same level as that of arbutin in control cells, although there was no suppression by plant cerebrosides and bovine brain cerebroside up-regulated melanin formation. None of the bovine brain cerebrosides examined had any effect on tyrosinase activity, but yeast cerebroside reduced the contents of tyrosinase. The results of the present study clearly showed that melanin formation is regulated by several different cerebrosides via tyrosinase. In addition, the findings presented here suggest that cerebrosides containing a 9-methyl type sphingoid base, such as yeast cerebroside, may be useful as skincare products for suppressing melanin formation.     

Promotion of tyrosinase folding in COS 7 cells by calnexin

To evaluate the role of serum free or unbound insulin-like growth factor I (IGF-I) on bone growth, we measured serum free IGF-I levels in 354 healthy children and adults (193 males and 161 females, aged 0-40 yr) and in 21 prepubertal GH-deficient (GHD) children (complete GHD, n = 5; partial GHD, n = 16) using a recently developed immunoradiometric assay. We obtained the following results. 1) In the normal children, the serum free IGF-I levels were low in infancy (<1 yr of age; males, 0.71 +/- 0.26 microg/L, mean +/- SD; females, 1.05 +/- 0.49 microg/L), increased during puberty (males, 5.84 +/- 2.18 microg/L; females, 5.80 +/- 1.49 microg/L), and declined thereafter. 2) Free IGF-I in the serum occupied about 0.95-2.02% of the total IGF-I values, with the highest ratio occurring in infancy (males, 1.77 +/- 0.60%; females, 2.02 +/- 0.87%). 3) The SD scores of serum free IGF-I in the 21 GHD children ranged from -3.30 to 0.30, and the 5 complete GHD children had free IGF-I values more than -2 SD below those of age-matched normal subjects. 4) There was a significant correlation between the SD scores of free IGF-I and those of total IGF-I (r = 0.715; P < 0.0005) in the GHD children. 5) In the 16 partial GHD children receiving GH treatment, the serum free IGF-I levels were elevated to 209% of pretreatment levels after 1 month of GH treatment and remained high during GH therapy. The GH-induced increase in the serum free IGF-I levels was significantly higher than those of the total IGF-I and IGF binding protein-3 levels. 6) The percent increase in the serum free IGF-I level after 1 month of GH treatment showed a significant positive correlation with that of the GH-induced improvement in the percent increase in the height velocity during 1 yr of GH therapy (r = 0.526; P < 0.05). These results show that free IGF-I in the serum has an essential role in bone formation because the higher free IGF-I levels were observed when the growth rate accelerated. The measurement of serum free IGF-I may become a useful tool for both diagnosing GH deficiency and predicting growth responses to long term GH therapy.     

Monte Carlo simulation for electron transport in MESFETs includingrealistic band structure of GaAs

A full band Monte Carlo (FBMC) simulator was developed for electron transport in GaAs MESFETs. As a result of increased scattering rate due to the complicated band structure, the average velocity in the high field region was lower than the analytical band Monte Carlo (ABMC) result. Also, the simulated energy peak was higher than the ABMC result, due to electrons populating the upper bands. Not only due to a limited number of the first conduction band states capable of ionization, but also due to a small mass of the second conduction band, more than 95% of ionization events were shown to occur in the upper bands. The simulated ionization rate lies within the range of experimental results. To our knowledge, this is the first report on the full band two-dimensional (2-D) self-consistent GaAs MESFET simulation     

Motion control in an electric vehicle with four independentlydriven in-wheel motors

We study methods of motion control for an electric vehicle (EV) with four independently driven in-wheel motors. First, we propose and simulate a novel robust dynamic yaw-moment control (DYC). DYC is a vehicle attitude control method that generates yaw from torque differences between the right and left wheels. The results of simulations, however, identify a problem with instability on slippery, low μ roads. To solve this problem, a new skid detection method is proposed that will be a part of traction control system (TCS) for each drive wheel. The experimental results show that this method can detect a skidding wheel, without any information on chassis velocity. Therefore, this method will be of great help during cornering or braking in a TCS. These methods will be integrated and tested in our new experimental EV     

Reduction of Devolatilization Rate of Fuel During Bubbling Fluidized Bed Combustion Using Porous Bed Material

Plastic waste combustion in bubbling fluidized bed combustors (BFBC) is characterized by the rapid devolatilization of the fuel. Noncombusted hydrocarbons are often formed, which have been reported to promote the formation of dioxins. In this work, porous bed material was employed instead of commonly used non‐porous sand to reduce the devolatilization rate. We measured (1) the heat transfer coefficient between an immersed object (brass sphere) and the bed and (2) the time required for the devolatilization of a plastic pellet after dropping it into the bed at 943 K. For porous particles we found a 30 % lower heat transfer coefficient, delayed onset of devolatilization and prolonged devolatilization time, compared with quartz sand. Therefore, porous particles were found to be effective in suppressing the rapid devolatilization of plastic waste.     

High‐frequency equivalent circuit of an induction motor driven by a PWM inverter

This paper deals with the high‐frequency equivalent circuits in an induction motor driven by a PWM inverter. The leakage current flows through stray capacitance among stator windings and iron core (frame) of the induction motor at the switching instants of the inverter transistors. The high‐frequency equivalent circuits are derived based on the frequency characteristics of the high‐frequency zero‐phase impedance and line‐to‐line impedance of the induction motor. The validity of the derived equivalent circuits is confirmed by simulation and experimental results. © 2001 Scripta Technica, Electr Eng Jpn, 135(1): 65–76, 2001     

Development of an ultrafast X‐ray computed tomography scanner system: Application for measurement of instantaneous void distribution of gas–liquid two‐phase flow

An ultrafast X‐ray computed tomography (CT) scanner has been developed. This scanner overcomes problems that occur in a transient or unsettled state, which make the conventional CT scanner inappropriate. To reduce the scanning time, this X‐ray CT system uses electronic switching of electron beams for X‐ray generation instead of the mechanical motion adopted by conventional CT scanners. The mechanical motion is a major obstacle to improving scanning speed. A prototype system with a scanning time of 3.6 ms was initially developed and confirmed to measure the dynamic events of two‐phase flow. However, an increased scanning speed is generally required for practical use in the thermal hydraulics research field. Therefore, an advanced type which can operate under the scanning time of 0.5 ms and can measure two‐phase flow with a velocity up to 4 to 5 m/s was developed. © 2000 Scripta Technica, Heat Trans Asian Res, 29(3): 155–165, 2000     

Stochastic finite element method for elasto‐plastic body

This paper proposes a Stochastic Finite Element Method (SFEM) for non‐linear elasto‐plastic bodies, as a generalization of the SFEM for linear elastic bodies developed by Ghanem and Spanos who applied the Karhunen–Loeve expansion and the polynomial chaos expansion for stochastic material properties and field variables, respectively. The key feature of the proposed SFEM is the introduction of two fictitious bodies whose behaviours provide upper and lower bounds for the mean of field variables. The two bounding bodies are rigorously obtained from a given distribution of material properties. The deformation of an ideal elasto‐plastic body of the Huber–von Mises type is computed as an illustrative example. The results are compared with Monte‐Carlo simulation. It is shown that the proposed SFEM can satisfactorily estimate means, variances and other probabilistic characteristics of field variables even when the body has a larger variance of the material properties. Copyright © 1999 John Wiley & Sons, Ltd.     

Monte Carlo simulations of spectral albedo for artificial snowpacks composed of spherical and nonspherical particles

The optical properties of snowpacks composed of spherical and nonspherical particles artificially prepared in a cold laboratory are investigated by measuring spectral albedos. The measured spectral albedo in the spectral region lambda=0.35-2.5 microm is compared with the theoretically calculated albedo, for which a Monte Carlo radiative transfer model is employed for multiple scattering combined with the Mie theory and the ray-tracing technique for single scattering by snow particles. Since the spherical particles are a little aggregate, the effects of a cluster of the spheres on snow albedo are examined using a generalized multiparticle Mie-solution model [Appl. Opt. 34, 4573 (1995); J. Quant. Spectrosc. Radiat. Transf. 79-80, 1121 (2003)]. The snow albedo of a cluster of the spheres can be represented with that of the singe sphere slightly larger than its component of the cluster in case of small grains. The observed albedos for the spherical snow particles agree with the theoretically calculated ones for the snow grain size measured in the snow pit work. The snow albedos for the nonspherical particles, which were dendrites, are influenced by the branch width and the branch length, based on a comparison of the theoretically calculated albedo by using circular cylindrical snow particles and the observed albedo. The snow albedo in the near-infrared region depends on the branch width only when the branch length is sufficiently greater than the branch width. The comparison between the spherical and nonspherical snow particles indicates that the spectral albedo of the nonspherical particles can be represented by using an equal volume-area ratio sphere.