Inhomogeneous compression of PEMFC gas diffusion layer: Part II. Modeling the effect

The effect of inhomogeneous compression of GDL on the mass and charge transfer in PEMFC is studied. The model utilizes experimentally evaluated GDL parameters as a function of thickness. The modeling results are compared with a conventional model that excludes the effects. As a result, it is shown that the inhomogeneous compression has a significant effect on the current density distribution because of the varying contact resistance between GDL and electrode. This also implies that there are possible hot spots occurring inside the electrode, and thus inhomogeneous compression can have significant effects on the lifetime and local performance of the cell. According to the achieved results, the inhomogeneous compression of GDL cannot be neglected.     

Clinical analysis of internal carotid artery aneurysms with reference to classification and clipping techniques

OBJECTIVE: To determine the differential effects of parental major depression (MDD) on psychopathology of childhood, adolescent, and early-adult onset in offspring. METHOD: One hundred eighty-two offspring from 91 families in which one or more parents or neither parent had MDD were followed for more than 10 years and blindly reassessed by means of a structured diagnostic instrument. RESULTS: Parental MDD is associated with increased risk in offspring of childhood-onset MDD (eightfold), anxiety disorder (threefold), conduct disorder (fivefold), and early-adult-onset MDD (fivefold) but not adolescent-onset MDD, where there is a marked increase in risk, particularly in girls, regardless of parental diagnosis. These findings were not explained by parental comorbidity, but the association with MDD was explained by parental age at onset of MDD--there was a 13-fold increase in childhood-onset MDD and a 7-fold increase in adult-onset MDD in offspring of parents with MDD of early (before age 30 years) onset. CONCLUSION: Childhood- and early-adult-onset MDD may be etiologically homogeneous and familial subtypes. The reason for the high incidence of adolescent-onset MDD, particularly in girls, regardless of parental diagnosis, needs to be determined. The childhood offspring of depressed parents are a potential target for evaluation, especially when the parent had an early-onset depression.     

Experimental study of physiological advantages of assist circulation using oscillated blood flow

Duplication of the stomach is a rare congenital disease of the childhood. We report the exceptional manifestation in two adults. The clinical presentation and developmental theory is discussed by reviewing the literature. Today the therapy of choice is resection of the duplication with removal of the adjacent wall of the stomach.     

Ultrasonic velocity and attenuation of polymeric solids under oscillatory deformation: Apparatus and preliminary results

A new apparatus has been constructed in which ultrasonic velocity and attenuation coefficients can be measured under oscillatory deformation. Using this apparatus, dynamic ultrasonic parameters were obtained with sufficient accuracy to investigate plastic deformation directly. It is found that this method has potential as a new tool for the study of solid polymers during deformation.     

Study on explosion characteristics of natural gas and methane in semi-open space for the HTTR hydrogen production system

It is important to grasp the explosion characteristics of object gases: natural gas and methane, in order to evaluate the influence of a gas explosion accident in the HTTR hydrogen production system on the reactor. Thus, we carried out explosion experiments of the object gases in semi-open space, and verified a numerical analysis code for the simulation of the explosion accident. It was confirmed that NG–air mixture or methane-air mixture in semi-open space did not result in DDT although 10 g of C-4 explosive was used as an ignition source, and the numerical results agreed relatively with the experimental results. As a result, we could have the prospects for predicting the influence of the explosion accident on the reactor.     

Maltal binding mechanism and a role of the mobile loop of soybean beta-amylase

The inhibition of hydration of maltal (alpha-D-glucopyranosyl-(1-->4)-2-deoxy-D-glucal) catalyzed by soybean beta-amylase with 4-O-alpha-D-glucopyranosyl-(1-->4)-1-deoxynojirimycin (GDN) was investigated at 25 degrees C and at pH 5.4. As the concentrations of GDN used were comparable to that of the enzyme, Henderson's treatment was applied to this system. It was found that two maltal molecules bind to the enzyme according to a random mechanism and GDN inhibits the hydration of maltal competitively at subsites 1 and 2, and noncompetitively at the other site. On the basis of this result, it was inferred that the role of the mobile loop of this enzyme is to create a convenient catalytic environment for the hydration, and the closing of the active site by the mobile loop is induced by the binding of maltal.     

The effect of the addition of silica particles on linear spherulite growth rate of isotactic polypropylene and its explanation by lamellar cluster model

The effect of the addition of silica particles on spherulite growth rates of isotactic polypropylene has been investigated using an optical microscope. The spherulite growth rate remained constant with time and the growth rates decreased with increasing the silica content. The addition of silica particles generally causes a reduction of the average distance between adjacent silica particles and the linear growth rates become zero when the inter-particle distance reached to the end-to-end distance of the matrix chains. The reduction in the linear growth rate can be explained by assuming the lamellar clustering process that the precursor or solidified units with the single chain space, which spontaneously are built up from the melt, act as the crystallizing units and the diffusive mobility of the units was restricted by spatial confinement between adjacent silica particles.     

Michaelis-Menten analysis of immobilized enzyme by affinity capillary electrophoresis

Michaelis constant of enzymatic reaction was evaluated by affinity capillary electrophoresis using beta-galactosidase as a model enzyme and o- and p-isomers of nitrophenyl-beta-galactoside as substrates. The enzyme was immobilized on the inner surface of a fused-silica capillary by the covalent bonding through a bridging group, and the substrates were introduced into the capillary. The reaction products migrated electrophoretically toward the detection side (anodic side), while the unreacted substrates moved toward the injection side (cathodic side) on a slow electroosmotic flow generated by the weak negative charge of the immobilized enzyme. The initial velocity of the enzymatic reaction was estimated from the peak height of the product, and the Michaelis constant was calculated according to Lineweaver-Burk equation. The results (Km, 2.34 mM for o-isomer and 1.09 mM for p-isomer) were reproducible (RSD < 11.8%, n = 5). Although the estimated Michaelis constants were larger than the reported values measured in homogeneous solution, the ratio of the Michaelis constants of o-/p-isomers was in good agreement with the literature value. The present method required as low as a few microgram amount of enzyme and nanogram amount of substrate which is far smaller than those required in a conventional affinity HPLC.