Effective treatment of hydrogen boride sheets for long-term stabilization.

Two-dimensional hydrogen boride (HB) sheets prepared via the ion-exchange reaction from magnesium diboride (MgB2) are known to possess several intriguing properties for a wide range of applications; however, previous reports have shown that the sheets prepared using this method contain small amounts of reactive components, making them unsuitable for certain applications. Therefore, developing a method for preparing HB sheets that exhibit long-term stability and do not contain reactive species is essential. In this study, we developed an effective treatment method for achieving long-term stabilization of HB sheets. We found that by pre-treating the HB sheets with water and then filtering the dried product from an acetonitrile dispersion, we could achieve excellent long-term stability over nine months. This stability was maintained even outside of a glovebox, with no H2 released by the decomposition and/or reaction. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) absorption spectroscopy measurements revealed that the sample exhibited pure HB characteristics with negatively charged boron and B-H-B and terminal B-H bonds, even after nine months of storage. Furthermore, based on thermal desorption spectroscopy (TDS) measurements, the presence of reactive species in the as-prepared HB sheets is attributed to fluctuating B-H bonds with relatively weak binding energies that can be removed using the method developed in this study.

An empirical analysis of US and Japanese health insurance using age-period-cohort decomposition.

Aggregate data on household health insurance expenditure in the US and Japan that are classified by period and age are decomposed into age, period, and cohort effects by using the Bayesian cohort models. These models are developed to overcome the identification problem involved in cohort analysis. Despite the differences between the health insurance systems of the two countries, three interesting empirical findings are obtained. First, in both the countries, the age effects are the most influential, and the cohort effects have negligible influence. The latter provides a striking policy implication since the generational imbalance in social security expenditures is widely recognized in developed countries. Second, in both the countries, the period effects show a roughly upward trend. Finally, the age effects exhibit a roughly upward movement for all age groups in the US; however, in Japan, these effects show a downward movement for the 55-59 age group due to the changes in the health insurance system on retirement.