Antioxidant behaviour of carotenoids highly accumulated in HepG2 cells

The antioxidant behaviour of major dietary carotenoids accumulated at high concentrations in human hepatoma HepG2 cells was evaluated, in comparison with a-tocopherol. The cells that accumulated carotenoids and a-tocopherol at levels higher than the values reported in the human liver were exposed to mild oxidative stress with tert-butylhydroperoxide. b-Carotene (>2.6 nmol/mg protein) and astaxanthin (>1.8 nmol/mg protein) significantly suppressed lipid peroxidation, while b-cryptoxanthin and lutein did not. a-Tocopherol remarkably suppressed lipid peroxidation with an IC50 value of 0.16 nmol/mg protein. Neither a-tocopherol nor any of the carotenoids except for lycopene showed pro-oxidant action even at high cellular concentrations. The antioxidant behaviours of carotenoids in a cellular milieu were quite different from those previously found in liposomes and homogeneous solutions. Further studies are required to assess the implications of the antioxidant behaviours found in the cultured cells on human health

Effects of Ag Nanoparticle Coated Metal Electrodes on Electrochemical CO2 Reduction in Aqueous KHCO3

Electrochemical CO2 reduction is crucial for developing a sustainable closed-carbon-cycle society; however, the factors determining product selectivity have not been fully established, especially when the reaction is carried out over metal cathodes. The selectivity of the CO2 reduction pathway can be improved by modifying the cathode’s catalyst surface. This can be achieved by using specific surface of single crystal or by alloying through the addition of an impurity. In this study, the products of electrochemical CO2 reduction were evaluated in an aqueous KHCO3 system at various applied currents and with various metal cathodes. The metal cathodes were coated by Ag nanoparticles, as the Ag cathode was determined to yield the best Faradaic efficiency for CO production in an aqueous KHCO3 system. Our results suggest that some Ag coated cathodes enhance CO2 reduction, and thus the reduction products are tunable through surface modification

Highly Efficient Electrocatalytic Hydrogen Production over Carbon Nanotubes Loaded with Platinum Nanoparticles Using Solution Processing

Abstract Proton exchange membrane (PEM) electrolyzers are used for hydrogen (H2) production by water electrolysis. The commercial cathodic electrocatalyst for this process is typically mechanically mixed platinum on carbon (Pt/C). However, aggregation of the platinum (Pt) makes high loading of the catalyst difficult. Therefore, a method for the homogeneous combination of Pt and carbon materials is required. Herein, the first example of a highly efficient single‐walled carbon nanotube (SWCNT) cathodic H2‐production electrocatalyst that is loaded with platinum nanoparticles (PtNPs) using a newly developed suspension method is reported. Combining SWCNTs lapped with a water‐soluble, thiol‐functionalized polymer with PtNPs in water yields a PtNP‐conjugated SWCNT suspension. The electrocatalyst exhibits a low overpotential of 47 mV at a current density of 10 mA cm−2 toward H2 evolution in 0.5 m sulfuric acid. A PEM electrolyzer fabricated using the optimally prepared electrocatalyst with the low loading of 15 µgPt cm−2 shows a high mass activity of 27 200 A gPt−1, which is 80 times that of Pt/C with a loading amount of 2.8 mgPt cm−2 (324 A gPt−1). In addition, the PEM electrolyzer produces H2 at a Faradaic efficiency of 97% and operates stably for 150 h at 100 mA cm−2

A single dose of oral nattokinase accelerates skin temperature recovery after cold water immersion: A double-blind, placebo-controlled crossover study

Nattokinase (NK) intake may improve blood flow; however, its effects on skin temperature, which is predominantly controlled by skin surface blood flow, are unknown. The purpose of this study was to determine the effects of a single dose of NK on changes in skin temperature after cold water immersion. A double-blinded, placebo-controlled, crossover intervention study was performed on nine healthy men. The participants were randomised to receive either a single dose of 2,000 fibrinolytic units (FU) of NK or a placebo with subsequent crossover. Two hours after supplementation, the participants immersed both hands in a water bath maintained at 10 °C for 1 min. Skin temperature, perceived coldness, cardiac output, and sympathetic nervous activity were measured before, during, and after water immersion. Two-way analysis of variance showed a significant effect of treatment interaction on the skin temperature of the middle finger, palm, and back of the right hand (p < 0.05). These findings represented that the skin temperatures of the middle finger, palm, and back of the right hand immersed in the cold water were significantly dropped due to the cold water immersion, and then recovered more quickly by NK intake than by placebo intake. The results of the current study highlight the potential implications of NK for the prevention of excessive vasoconstriction. It may be more significant for those with cold-sensitive constitution, such as women and elderly. In contrast, the acute administration of 2,000 FU of NK did not affect changes in heart rate, cardiac output, sympathetic nervous activity compared with a placebo in healthy men