Gold Nanoparticle Formation via X-ray Radiolysis Investigated with Time-Resolved X-ray Liquidography.

We report the generation of gold nanoparticles (AuNPs) from the aqueous solution of chloro(2,2',2″-terpyridine)gold(III) ion ([Au(tpy)Cl]2+) through X-ray radiolysis and optical excitation at a synchrotron. The original purpose of the experiment was to investigate the photoinduced structural changes of [Au(tpy)Cl]2+ upon 400 nm excitation using time-resolved X-ray liquidography (TRXL). Initially, the TRXL data did not show any signal that would suggest structural changes of the solute molecule, but after an induction time, the TRXL data started to show sharp peaks and valleys. In the early phase, AuNPs with two types of morphology, dendrites, and spheres, were formed by the reducing action of hydrated electrons generated by the X-ray radiolysis of water, thereby allowing the detection of TRXL data due to the laser-induced lattice expansion and relaxation of AuNPs. Along with the lattice expansion, the dendritic and spherical AuNPs were transformed into smaller, raspberry-shaped AuNPs of a relatively uniform size via ablation by the optical femtosecond laser pulse used for the TRXL experiment. Density functional theory calculations confirm that the reduction potential of the metal complex relative to the hydration potential of X-ray-generated electrons determines the facile AuNP formation observed for [Au(tpy)Cl]2+.

The impact of obesity and overweight on medical expenditures and disease incidence in Korea from 2002 to 2013.

OBJECTIVES: Few studies have assessed the long-term medical costs and incidence of obesity and overweight in Asia. We evaluated the impact of body mass index (BMI) on medical expenditures and disease incidence and prevalence over more than 10 years in South Korea. METHODS: Using 2002-2013 data from the Korean National Claims Database, we analysed two population sets (initial BMI in 2002-2003; consistent BMI in 2002-2003 and 2012-2013). Obesity was defined by Asian BMI criteria. Incremental medical expenditures or Charlson Comorbidity Index (CCI) ratios for obese compared to normal weight individuals were calculated. Medical expenditure over 11 years was estimated by BMI using a generalised linear model. Individual obesity-related disease incidence was determined and adjusted hazard ratios were calculated. RESULTS: Data for 496,469 and 214,477 individuals were included in the entire and consistent BMI level populations, respectively. Average CCI score change in normal weight and the obesity III (BMI 35-59.99 kg/m2) group over 11 years were 0.94 and 1.56, respectively in the entire population, and incremental ratio in the obesity III group was 66.0% compared to the normal weight group. In consistent BMI level population, incremental ratio (92.1%) for obesity III was higher than entire population. Medical costs in the obesity III groups versus the normal weight group in the entire and consistent BMI level populations increased by 38.4% and 77.1%, respectively. Over 11 years, individuals with BMI ≥30 kg/m2 in the entire and consistent BMI level populations had post-adjustment medical expenditures of 1.13-1.20 and 1.21-1.40 times the normal weight group, respectively. Incidence rate and adjusted hazard ratio of obesity-related disease increased in the obesity groups compared to the normal weight group. CONCLUSIONS: Our findings emphasize the importance of the effective and sustainable obesity management strategies, considering the dramatic increase in obesity (BMI ≥30 kg/m2) in South Korea.

Protein tertiary structural changes visualized by time-resolved X-ray solution scattering.

We obtained a solution structural model of myoglobin (Mb) formed upon the CO photolysis of MbCO by analyzing time-resolved X-ray solution scattering data. An experiment-restrained rigid-body molecular dynamics simulation was used to find the best model whose theoretical difference scattering curve gives a satisfactory agreement with the experimental data at the time delay of 10 ns. The obtained solution model shows structural changes similar to crystallographic models for MbCO --> Mb but also displays a noticeable difference in that the N-terminus and F helix show larger structural changes.