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In this article, we applied tunable diode laser absorption spectroscopy (TDLAS) technique to measure variation of water vapor concentration in gas flow channels in an operating polymer electrolyte membrane fuel cell (PEMFC). TDLAS measurement offered an optical remote sensing to detect slight change of water vapor concentration, showing that electrochemical reaction in an operating PEMFC is not uniformly observed. We performed TDLAS measurement in gas flow channels in the anode and the cathode with variation of cell current density. We observed increase of water vapor concentration due to electrochemical reaction along the cathode channel as well as along the anode channel from the inlet, suggesting that generated water was exhausted through the both channels. It was also shown that less electrochemical reaction was observed in the upstream of the channel presumably due to less hydration of the membrane because of dry gas supply.

An effect of a micro porous layer (MPL) on water transport under a low-humidity condition was examined in a PEMFC with a single straight channel using a tunable diode laser absorption spectroscopy (TDLAS) measurement system, which can measure local through-plane water transport based on measurement of the distribution of water vapor concentration along the channel. The TDLAS results showed that the MPL imparts mass transport resistance at the cathode side under low-humidity conditions with co-flow and counter-flow modes and enhanced back-diffusion of the generated water to the anode side. The MPL at the cathode side strongly affected through-plane water transport and is therefore effective for membrane hydration under low-humidity conditions.

Polymer electrolyte membrane fuel cells (PEMFCs) are expected to be future power sources for vehicle and on-site power generation. For implementation of PEMFCs, water management is essential to keep membrane hydration under fuel cell operation without ‘flooding’ and ‘plugging’ [1]. To establish a water management method, fundamental understandings of mass transport processes involved in PEMFCs are strongly needed. In the cathode of PEMFC, supplied oxygen (O2) is consumed by electrochemical reaction with hydrogen (H2) supplied from the anode. Water (H2O) is generated depending on current density of the PEMFC. Along fuel cell channels, oxygen concentration decreases and water vapor concentration increases and thus local water vapor and oxygen concentration reflect local current density of fuel cell.

We present a durability test of polymer electrolyte membrane fuel cell (PEMFC) under load cycle operation. Polarization curves of the fuel cell was deteriorated by load cycle, although cross-sectional analysis by scanning electron microscopy (SEM) indicated no identical degradation on the membrane electrode assembly (MEA). In-line direct gas mass spectroscopy (DGMS) analysis successfully detected intermittent peaks of carbon dioxide (CO2) emission in exhausted gas from the cathode, indicating carbon corrosion proceeding during load cycle in the fuel cell.

Spreading characteristics of novel cyclotriphosphazine-terminated Perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of novel lubricants were also studied in order to evaluate the spreading speed and they were compared with the conventional Zdol. It was found that the mobility of cyclotriphosphazine-terminated PFPE films is lower than that of Zdol. This characteristics is dependent on the interactions between the end groups of the lubricants and carbon surfaces and it is found that the tendency of “work of adhesion” for the lubricants has a good correlation with the mobility tendency of the lubricants. In addition, the monolayer film thickness of novel lubricant films as well as conventional Zdol was identified, which was extracted using Matano interface method. As a result, the existing conformation of novel cyclotriphosphazine-terminated PFPE film on carbon surfaces could be estimated, based on the monolayer film thickness results.

Flutamide, when administered subcutaneously to female rats at doses of 3, 10, or 30 mg/kg/day during late pregnancy (gestational days 16-21), significantly and dose-dependently decreased anogenital distance (AGD) of the male offspring in each dose group compared to controls. Significant delays in preputial separation were found in males at a dose of 30 mg/kg, but body weight gain was not inhibited. Cryptorchidism and absence of the prostate gland and seminal vesicles were found in males at doses > or = 10 mg/kg, and testicular hypoplasia at a dose of 30 mg/kg. Hypospadias was noted in all dose groups and vaginal pouches at doses of > or =10 mg/kg. The effects on the accessory reproductive organs were severe, although the effects on the testes themselves were mild. However, those effects appeared to become more pronounced with growth, as evaluated on Days 30 and 42 and Weeks 16 to 18. Most of these affected animals displayed cryptorchidism. Male offspring exposed to flutamide in utero showed impairments of sexual behavior as adults in a dose-related manner. Number and frequency of mounts with intromissions was markedly decreased in all treated groups as compared to controls. At 10 mg/kg, no mounting with ejaculation was observed, and at a dose of 30 mg/kg, no mounting with intromission or ejaculation was observed. These changes in sexual behavior were closely associated with abnormalities of the external genitalia. Animals with hypospadias did not display mounts with ejaculation. However, F1 males that copulated at a dose of 3 mg/kg had a normal reproductive function. Histological examination of the reproductive organs revealed degeneration of the seminiferous tubules, hypospermatogenesis, and hypoplasia and inflammation of the seminal vesicles and prostate. Serum levels of FSH, LH, and testosterone in these animals were comparable between control and all dose groups. Therefore, the male reproductive dysfunction seen in the present study could not be attributed to abnormal sex hormone levels during maturation, but to possible demasculinization of the brain and progressively delayed dysmorphology of the male genitalia caused by fetal exposure to flutamide.

In this study, we present optical remote sensing of oxygen and water vapor concentration in gas flow channels in an operating polymer electrolyte membrane fuel cell (PEMFC) by using Tunable Diode Laser Absorption Spectroscopy (TDLAS). Wavelengths of the diode laser are 1392nm for measurement of water vapor concentration and 760nm for measurement of oxygen concentration, respectively. We demonstrated that the optical remote sensing based on TDLAS techniques could detect variation of oxygen and water vapor concentration in the PEMFC channel.Copyright © 2007 by ASME

Flutamide is a drug with antiandrogen effects that are mediated through androgen receptors (ARs). In this study, flutamide was subcutaneously administered to female rats (3, 10 or 30 mg/kg/day) on gestation Days 16-21 to evaluate effects on memory and learning performance in F1 offspring. Brain sexual differentiation was also evaluated by measuring the volume of the sexual dimorphic nucleus of the preoptic area (SDN-POA) and analyzing levels of androgen receptor (AR) mRNA expression in the prostate, hypothalamus and hippocampus. In F1 offspring exposed in utero to flutamide, evaluation of motor activity, learning performance and spatial perception showed that flutamide tended to exert a dose-dependent increase on the motor activity in F1 males, but no significant differences were identified in the other measurements. Prominent changes in development of the SDN-POA were apparent in males after maturation. Doses of > or =3 mg/kg/day resulted in significantly decreased length and volume of the SDN-POA compared to controls. These differences tended to become more marked at higher doses. Volumes of the SDN-POA did not differ significantly between F1 males and females exposed to flutamide at 30 mg/kg/day. AR mRNA was assayed using the dot-blotting method in F1 animals. In flutamide dose groups, AR mRNA expression tended to be increased in the prostate gland and decreased in the hippocampus. These results might suggest that exposure to flutamide in utero might affect controlling AR expression on a hormonal signal transduction system mediated by testosterone. However, these changes were not clearly correlated to learning performance in male offspring other than motor activity.

Micro porous layer (MPL), which is a thin porous layer embedded between a gas diffusion layer (GDL) and a catalyst layer (CL), is expected to give a solution as one of the methods to keep membrane hydration under low humidity operation [3]. However, further understanding of effect of the MPL on membrane hydration is still needed. The membrane is hydrated by three water sources, which are humidification water at cathode, humidification water at anode and generated water. In this study, effect of the MPL at the cathode side on membrane hydration path was examined by using nuclei-labeling magnetic resonance imaging (NL-MRI) technique [4]. The NL-MRI technique is useful in order to investigate the effect of the each water sources on membrane hydration.

This report deals principally with variation of the tapping torque by the left spiral and the straight fluted taps for the duralumin and the cast iron FC 20. As conclusions, (1) The helix angle of the left fluted taps is recommended to be 13 to 15 deg. for the duralumin because chip flow becomes smooth.(2) From the dimensional analysis, the following equation for tapping torque is derived.T=p2deks(k1+k2Vp/D)where T=tapping torque, p=pitch, ks=specific cutting force, V=cutting speed and D=thermal diffusivity. And also k1, k2 are the constants.

The phenolyses of 1,1- and 3,3-dimethylallyl chlorides were shown by kinetic studies to undergo SN1 solvolysis. The distributions of the products, dimethylallyl phenyl ethers and (dimethylallyl)phenols, supported the mechanism that involves both localized ion-pairs and mesomeric ion-pairs.

The phenolyses of 1,1- and 3,3-dimethylallyl chlorides were shown by kinetic studies to undergo SN1 solvolysis. The distributions of the products, dimethylallyl phenyl ethers and (dimethylallyl)phenols, supported the mechanism that involves both localized ion-pairs and mesomeric ion-pairs.

The stoicheiometry and kinetics of the CeIV oxidation of 1,2,2,2-tetrakis-(p-methoxyphenyl)ethanone (1a) have been investigated at 25.0 °C in acetic acid as solvent by the use of cerium(IV) ammonium nitrate as oxidant. The reaction occurs with the stoicheiometry 2 CeIV+ An3C·CO·An → 2 CeIII+ An3C++ An·CO+(An =p-methoxyphenyl), affording tris-(p-methoxyphenyl)methanol and anisic acid after work-up. The kinetics were monitored by u.v.–visible spectrophotometry of the tris-(p-methoxyphenyl)methyl cation, showing that the rate-determining step is first order in each reactant. Evidence was found for the formation of p-methoxybenzoyl radical by means of spin-trapping with 2,3,5,6-tetrakis(trideuteriomethyl)nitrosobenzene. The rate constants at 25.0 °C, the oxidation potential, as measured by cyclic voltammetry, and the charge transfer energy with tetracyanoethylene have been measured for five para-substituted benzpinacolones (substituents MeO, Me, and Cl), including (1a). A good correlation of the logarithms of the rates with the oxidation potentials or with the charge transfer energies was found, indicating that a single electron-transfer step between the substrate and CeIV is rate determining. The formation of a radical cation of the benzpinacolone in the rate-determining step and subsequent rapid cleavage into the triarylmethyl cation and the aroyl radical are proposed as a possible mechanism.