Performance decay of proton-exchange membrane fuel cells under open circuit conditions induced by membrane decomposition

The degradation in performance of proton-exchange membrane fuel cells (PEMFCs) under open circuit conditions was investigated. The oxygen reduction reaction (ORR) kinetic current density at 0.9 V was found to decrease from 36 to 4 mA cm⁻² (geometric) without significant crossover increase or loss in the electrochemically active surface area. Cyclic voltammograms for the electrodes show characteristic changes, e.g. appearance of peaks at ∼0.2 V and shift of the onset of platinum oxide formation to higher potentials. It was identified that the large ORR kinetic decay has its origins in the reduction of available Pt sites due to adsorption of anions, which are postulated to be membrane decomposition products such as sulfate ions. Procedures carried out to condense water in the fuel cell led to the expulsion of anions out of the membrane electrode assembly (MEA) resulting in the partial recovery of ORR kinetic current density to 15 mA cm⁻². In order to attain complete performance recovery of the catalyst, a more effective and practical method to flush out the anions is desirable.     

A spatial evaluation of forest biomass usage using GIS

We conducted a spatial evaluation of forest biomass usage using a geographic information system (GIS) for the Japanese town of Yusuhara. In Japan, over 60% of the land is covered with forest, of which at least 40% is artificial forest. However, because of high labor costs, the profitability of forestry is decreasing, so timber cultivation is not done to the extent that it could be, and thinning has to be subsidized. Under these circumstances, much of the forest is deteriorating. Most of the thinning is accounted for by throwaway thinning, in which the resulting wood is not used. However, with the steep rise in oil prices and the intensification of global warming concerns, expectations are rising for the use of biomass energy from thinned timber that has previously been discarded. If thinned timber, logging residues, and offcuts are utilized for biomass energy and their economic value becomes apparent, profitability will improve for both final cutting and thinning. And in addition to forestry activities being invigorated, it will be possible for some of the deteriorating forests (which have associated dangers such as landslides) to recover. However, using thinned timber and logging residues is problematic in that profitability is affected by harvesting costs. Harvesting costs are largely determined by geographic factors and are higher for more distant stands. Accordingly, in this article, operational costs for different stands are calculated using GIS and matched with total demand in the subject region. In addition, stands with lower operational costs are identified and an investigation of a highly feasible use of forest biomass is carried out.     

Mechanical property and dimensional stability of substrates for magnetic tapes

We have performed a comparative study on mechanical property and dimensional stability of substrates for magnetic tapes. The substrates include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and aromatic polyamide (ARAMID), which could be used for linear-type magnetic tapes for computer data storage. We have demonstrated that ARAMID is the most attractive substrate and that PET has the advantage of considerably smaller irreversible creep deformation and lateral contraction caused by tension as compared to PEN film. In this paper, we also introduce recently developed PET (Advanced PET) with higher glass transition temperature compared to conventional PET; moreover, we discuss the relationship between film properties and polymeric structures of these substrates.     

Persistent and secondary adenovirus-mediated hepatic gene expression using adenovirus vector containing CTLA4IgG

Some authors have hypothesized a relationship between rear-impact motor vehicle collisions and subsequent symptoms of neck pain and temporomandibular disorders, or TMD, despite no facial impact. This article examines the TMD aspect in terms of the physiological basis and cultural factors influencing the reporting of such symptoms.     

Effect of functional groups on the triboelectric charging property of polymer particles

Triboelectrification of small polymer particles (< 10 microns) in which various functional groups are introduced by addition of substituted comonomers is studied. The particles are produced by suspension polymerization and mechanical crushing of larger particles. The effect of the different production methods on the particle is described. The particles produced by the polymerization method have a spherical shape with a smooth surface, and those produced by the crushing method have an irregular shape. Studies show that particles that have easily ionizable functional groups are charged more effectively. It is believed the iontransfer route is the dominant mechanism in the triboelectrification charging of the particle. The magnitude of charge becomes saturated after 0.5% addition of substituted comonomers in the particles. The particles produced by the polymerization method have a tendency to be charged effectively compared with those produced by the crushing method. © 1994 John Wiley & Sons, Inc.     

Nondestructive low-cycle fatigue characterization of multi-layer thin film structures

A multi-layered thin film structure (namely, electrodeposited Cu/sputtered Cr/Kapton substrate/sputtered Cr/electrodeposited Cu), utilized as a flexible component for computers, has been exposed to fatigue. Although a standardized testing method for fatigue ductility is available for a solid monolayer of electrodeposited foil, there is no method available for examining such a multi-layered thin film structure. In this study, four different methods were employed to characterize the low-cycle fatigue damage: (1) DC resistance measurement, (2) residual stress development by x-ray diffraction, (3) dislocation density calculation by using obtained x-ray diffraction line profiles, and (4) microscopic observations. Low-cycle fatigue was conducted at eight levels of applied total strain, i.e., _T =13.95%, 7.69%, 5.83%, 4.69%, 3.37%, 2.37%, 1.59%, and 1.19%. The number of fatigue cycles, when the crack was first observed on the outer Cu layer, was identical to that observed with the onset of increased resistance. This cycle number is thus designated as the number of cycles-to-fatigue crack initiation,N _c . AtN _c , the residual stresses also show a noticeable relaxation, and the dislocation density shows a remarkable increase. IfN _c is plotted against the applied total strain amplitudes, a Manson-Coffin's relationship is obtained with an exponent of 0.39. It is recommended that monitoring the continuous changes in DC resistance could provide a reliable nondestructive evaluation of low-cycle fatigue life of a multi-layered thin film structure.     

Reactions of organoboron polymers prepared by hydroboration polymerization

Summary Organoboron polymers were prepared by hydroboration polymerization between various dienes and thexylborane. These polymers were reacted with -furyllithium followed by the treatment with acetic acid and then by the oxidative treatment to give the corresponding polyalcohols having primary and tertiary hydroxyl groups. The structures of the polyalcohols obtained were characterized by¹H-NMR compared with that for model compound, which was prepared by the reaction of dioctylthexylborane with -furyllithium. These conversions from organoboron polymers to polyalcohols include the migrations of two polymeric chains from boron atom to carbon and the ring-opening of furan ring.For parts I, II, and III, see references 4, 5 and 6, respectively.     

Pectin‐[(3‐acrylamidopropyl) trimethylammonium chloride‐co‐acrylic acid] hydrogel prepared by gamma radiation and selectively silver (Ag) metal adsorption

Pectin‐[(3‐acrylamidopropyl) trimethylammonium chloride‐co‐acrylic acid] hydrogel has been prepared from the aqueous blend solution of pectin, (3‐acrylamidopropyl) trimethylammonium chloride (APTAC), and acrylic acid (AAc) by applying gamma radiation of different doses (1–25 kGy) from ⁶⁰Co gamma source. The hydrogels were characterized by equilibrium swelling, Fourier transform infrared, differential scanning calorimetry, and scanning electron microscopy. The hydrogels were used in multielement adsorption and it was found that pectin‐(APTAC‐co‐AAc) gel is highly selective toward silver (I) ion among 27 metal ions. The data obtained from equilibrium adsorption studies were fitted in Langmuir and Freundlich adsorption isotherm models and model parameters evaluated. The maximum adsorption capacity of pectin‐(APTAC‐co‐AAc) gel was found to be 67.6413 mg/g of dry gel at sample volume of 25 mL. The kinetic data were tested using pseudo‐first order and pseudo‐second order kinetic models and different adsorption diffusion models such as film diffusion and intra‐particle diffusivity model. Thiourea solution was used for desorption of adsorbed metal ions from the hydrogel. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45906.     

Splat morphology and microstructure of plasma sprayed cast iron with different preheat substrate temperatures

A cast iron coating is a prime candidate for the surface modification of aluminum alloys for antiwear applications because cast iron is inexpensive and exhibits superior wear resistance arising from the self-lubricating properties of graphite. In the present study, fundamental aspects of a plasma sprayed cast iron coating on an aluminum alloy substrate, including (1) the effects of preheat substrate temperature on the splat morphology, (2) the formation of a reaction layer and pores, and (3) the splat microstructure, were investigated in low-pressure plasma spraying. With an increasing substrate temperature, the splat morphology changes from a splash type to a disk and star shape. Deformed substrate ridges mainly resulting from the slight surface melting, are recognized adjacent to the splat periphery at high substrate temperatures. The flattening ratio of disk splats decreases with substrate temperature because the ridges act as an obstacle for splat expansion. A reaction layer composed of iron, aluminum, and oxygen is ready to form at high substrate temperatures, which, along with the deformed ridges, improves the adhesive strength of splats. However, the pores appear at the splat interface at low substrate temperatures, which hinder the formation of a reaction layer. The amount of graphitized carbon increases in cast iron splats with an increase in substrate temperature.