Influence of activated carbon pore structure on oxygen reduction at catalyst layers supported on rotating disk electrodes

Carbon materials are often used as catalyst supports, and for catalysts in electrodes of a polymer electrolyte fuel cell, carbon black has been used. Recently, it was found, however, that activated carbon could replace carbon black and besides, significantly improve the activity of the electrode catalyst layer for oxygen reduction. In the present study, to optimize the pore structure of activated carbon for further activity improvement, the influence of the pore structure on the activity was investigated using activated carbon of various specific surface areas and mean pore diameters. A catalyst layer was formed from activated carbon loaded with platinum and a polymer electrolyte. The activity of the layer was measured in an oxygen-saturated perchloric acid solution, supporting the layer on a rotating glassy carbon disk electrode. We found that increases in the specific surface area and mean pore diameter increased the activity and that the latter was more effective than the former mainly due to the enhanced mass-transfer in the pores; the catalyst layer formed from activated carbon with the largest mean pore diameter was the most active. Unless pores excessively develop and lose connections between particles, a large pore diameter is therefore desired for the fuel cell electrodes.     

Effect of surface properties of silica nanoparticles on their cytotoxicity and cellular distribution in murine macrophages

In this study, complexes composed of poly-l-tyrosine (pLT) and single-walled carbon nanotubes (SWCNTs) were produced and the dispersibility of the pLT/SWCNT complexes in water by measuring the ζ potential of the complexes and the turbidity of the solution were investigated. It is found that the absolute value of the ζ potential of the pLT/SWCNT complexes is as high as that of SWCNTs modified with double-stranded DNA (dsDNA) and that the complexes remain stably dispersed in the water at least for two weeks. Thermogravimetry analysis (TGA) and visualization of the surface structures of pLT/SWCNT complexes using an atomic force microscope (AFM) were also carried out.     

Photoinduced increase in surfactant solution viscosity using azobenzene dicarboxylate for molecular switching

We provide further insight into the photochemical control of viscoelasticity through the use of azobenzene sodium dicarboxylate for molecular switching. As a photoresponsive molecule, Sodium 3,3'-azobenzene dicarboxylate (3,3'-Azo2Na) was added to a solution of cetyltrimethylammonium bromide (CTAB)/sodium salicylate (NaSal), which is known for inducing the formation of wormlike micelles. This solution maintained a wormlike micellar structure, although a reduction in zero-shear viscosity was observed. When this mixed aqueous solution of CTAB/NaSal/3,3'-Azo2Na (16.7 mM each) was irradiated by ultraviolet light, the 3,3'-Azo2Na exhibited molecular trans-cis photoisomerization. We measured the dynamic viscoelasticity of the sample in the photostationary state and found that the zero-shear viscosity increased approximately sevenfold compared to the preirradiation state. This phenomenon is the opposite of the system wherein viscosity reduced by irradiation, as reported by us. We discuss the mechanism of this viscosity change.     

Dietary supplementation of gamma-linolenic acid improves skin parameters in subjects with dry skin and mild atopic dermatitis

Disruption of the skin barrier function caused by epidermal hyper-proliferation, results in the skin becoming dry and showing high transepidermal water loss (TEWL). Gamma linolenic acid (GLA) is reportedly efficacious for treating TEWL and epidermal hyper-proliferation. In this study, to elucidate the effect of GLA-rich oil on skin function, GLA-containing food was given to adults with dry skin or mild atopic dermatitis and skin parameters were evaluated. In the results, we recognized beneficial effects on the TEWL index. The efficacy of GLA was also demonstrated to be statistically significant especially in subjects with pro-inflammatory features. The results suggest that the mechanism of improvement of skin barrier has been associated with possible generation of anti-inflammatory metabolites from GLA. The clinical physician also confirmed that none of the subjects showed any noteworthy side effects. GLA-enriched food appears to be safe and to improve skin barrier function in subjects with dry skin conditions and mild atopic dermatitis.     

Fabrication and Pore Size Control of Large-Pore Mesoporous Silica Particles through a Solvent Evaporation Process

Large-pore mesoporous silica particles were synthesized through a solvent evaporation process using hydrophobic fumed silica particles and tetraethyl orthosilicate (TEOS) as silica sources. The solvent evaporation of an ethanol solution of fumed silica particles, TEOS, HCl and triblock copolymer (F127) resulted in mesoporous silica particles with pores with sizes of about 7 nm. In addition, the interplanar spacing of the mesoporous silica particles can be controlled by changing the solvent evaporation temperatures.     

Germanium recovery using polyphenol microspheres prepared by horseradish peroxidase reaction

BACKGROUND: The formation of polyphenol microspheres by the polymerization of 3‐methylcatechol was performed in a methanol/phosphate buffer solution using horseradish peroxidase (HRP), without the use of a surfactant or a water/oil interface, to be used for germanium recovery. RESULTS: The polyphenol microspheres were of diameter 1 mm. The functional group density of phenol group in the polymer was approximately 15 mol kg^?1 determined by the Folin‐Denis method. In batchwise experiments, the amount of germanium adsorbed was 0.23 mol kg^?1. CONCLUSION: Because germanium is a rare metal, a system for its recovery is required. Using the proposed system, continuous recovery of germanium can be achieved using multilayered microspheres. Copyright © 2011 Society of Chemical Industry     

Pyrrolizidine Alkaloids Mediate Host-Plant Recognition by Ovipositing Females of an Old World Danaid Butterfly, Idea leuconoe

A giant danaid butterfly, Idea leuconoe, specializes on apocynaceous plants such as Parsonsia laevigata, which has been reported to contain pyrrolizidine alkaloids. Females of I. leuconoe deposited eggs in response to methanolic extract of P. laevigata, and subsequent bioassay-guided fractionation of the extract revealed that phytochemicals crucial for host recognition by ovipositing females are Parsonsia-specific macrocyclic pyrrolizidine alkaloids including parsonsianine, parsonsianidine, and 17-methylparsonsianidine. Parsonine, another P. laevigata pyrrolizidine component with a keto-dihydropyrrolizine moiety that is closely related in structure to male pheromones of the butterfly, and several nonhost pyrrolizidine alkaloids were entirely inactive. We interpret these data as strong evidence for an ancestral association through herbivory between danaid butterflies and pyrrolizidine alkaloids.     

Prevention of Osteoporosis by Oral Administration of Phytate-Removed and Deamidated Soybean β-Conglycinin

Phytate-removed and deamidated soybean β-conglycinin (PrDS) prepared by ion-exchange resins was supplemented to be 4% in the diet administered to ovariectomized rats to investigate its preventive effect on osteoporosis. The apparent calcium absorption rate decreased following ovariectomy and was not replenished by oral administration of phytate-removed soybean β-conglycinin (PrS) or casein. On the other hand, administration of PrDS restored the calcium absorption rate to the same level as the sham group. Markers of bone resorption, such as serum parathyroid hormone (PTH) and urinary deoxypyridinoline (DPD), increased, and the bone mineral density and breaking stress decreased following ovariectomy. However, PrDS supplementation suppressed the changes caused by the decrease in calcium absorption from the small intestine. Therefore, PrDS supplementation shows promise for the prevention of postmenopausal osteoporosis.