Reduction of life-cycle CO2 emissions by expanding car-sharing services: A case study on Japan

Carbon neutrality is a growing concern for all global economies. We considered the number of new and used cars registered during 2009-2018 in Japan and estimated the total number of private and shared cars, assuming that when owners abandoned their old cars, a certain percentage of the owners chose to use a car-sharing service (i.e., car rental service), instead of buying a new private car. We estimated the CO2 emissions generated during the manufacturing, driving, and disposal stages of cars, to analyze the impact of car sharing on CO2 emissions. Then, we determined the changes in the life-cycle CO2 emissions of all the cars for three car-sharing penetration rates (0, 5, and 100%), assuming that all the cars were gasoline-powered. Additionally, we analyzed how electric vehicles can optimize the proposed strategy. An increase in car-sharing services significantly reduced vehicular CO2 emissions; the decrease in CO2 emissions from private cars when owners switched to car services significantly exceeded the increase in the CO2 emissions associated with the increased number of cars. The proposed model can serve as a reliable framework to analyze the current status of CO2 emissions and simulate the future changes in car-sharing services.

Barium sulphate with a negative zeta potential accelerates skin permeability barrier recovery and prevents epidermal hyperplasia induced by barrier disruption

BACKGROUND

Barium sulphate, a stable inorganic material, has been used in contrast media and cosmetic products because of its stability. As a negative external electric potential accelerates the skin barrier repair after barrier disruption, we hypothesized that topical application of barium sulphate may affect the skin barrier recovery rate depending on its zeta potential.

OBJECTIVES

To investigate whether barium sulphate particles in aqueous solution have different zeta potentials depending on their surface structure, and to investigate the possible relation between zeta potential and skin barrier recovery rate.

METHODS

Mice were subjected to tape stripping to disrupt barrier function, or were treated with acetone and kept in a dry environment to induce epidermal hyperplasia. They were then treated with different forms of barium sulphate, and barrier recovery was monitored by measurements of transepidermal water loss.

RESULTS

There was a significant correlation between the barrier recovery rate and zeta potential of barium sulphate applied topically. Barium sulphate with a negative zeta potential significantly accelerated barrier recovery, but barium sulphate with a positive zeta potential did not accelerate or even delayed barrier repair. Barium sulphate with a negative zeta potential had an X-ray diffraction pattern different from that with a positive potential. The distribution of calcium in the epidermis was also influenced by the polarity of zeta potential.

CONCLUSIONS

These findings suggest a new pharmacological approach towards altering barrier function or epidermal hyperplasia with inorganic particles in healthy and diseased skin.

Inclusion complexation of p-hydroxybenzoic acid esters with 2-hydroxypropyl-beta-cyclodextrins. On changes in solubility and antimicrobial activity

To obtain a transparent and effective solution of p-hydroxybenzoic acid esters (parabens), the use of 2-hydroxypropyl-beta-cyclodextrins (2-HP-beta-CyDs) as solubilizers with different degrees of substitution (D.S.) was surveyed. 2-HP-beta-CyDs significantly increased the aqueous solubility of four kinds of parabens (methyl < ethyl < propyl < butyl esters), where the solubilizing ability decreased with an increase in the D.S. of the 2-hydroxypropyl group in beta-CyD. The antimicrobial activity of the parabens tended to decrease by complexation with 2-HP-beta-CyDs. However, the activity could be maintained by lengthening the alkyl chain of the parabens. 1H- and 13C-nuclear magnetic resonance and circular dichroism spectroscopic studies suggest that the hydrophobic alkyl moiety of butyl paraben is preferably included in the cavity, and the phenol group extrudes from the cavity. The present results suggest that a suitable combination of 2-HP-beta-CyDs and hydrophobic, longer alkyl parabens is useful for the preservation of liquid formulations.