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It has been shown that the blue photoluminescence (PL) of porous silicon (PS) can be obtained simply from postanodization illumination by white light without any oxidation processes. The PS samples were formed on 5–6 Ω cm p-type (100) Si wafers. The anodization was carried out in an ethanoic HF solution at a current density of 50 mA/cm2 for 5 min in the dark. After the anodization, the samples were illuminated under the open-circuit condition by a 500 W tungsten lamp for several minutes. The PL measurements of prepared PS samples were carried out in vacuum. With increasing the postanodization illumination time, the PL band exhibited a continuous shift from red to blue. During this blue shift, fourier transform infrared spectra did not show any signs of the growth of the surface oxide. In addition, the emission energy dependence of the PL decay time for each PL band behaved in accordance with a universal curve. These results strongly suggest that there is an oxide-free mechanism in the PL emission from PS throughout the visible range.

We assessed the relationship between day-by-day home blood pressure (BP) variability and incident cardiovascular disease (CVD) in clinical practice. J-HOP study (Japan Morning Surge-Home Blood Pressure) participants underwent home BP monitoring in the morning and evening for a 14-day period, and their BP levels and BP variability independent of the mean (VIM) were assessed. Incident CVD events included coronary heart disease and stroke. Cox models were fitted to assess the home BP variability-CVD risk association. Among 4231 participants (mean±SD age, 64.9±10.9 years; 53.3% women; 79.1% taking antihypertensive medication), mean (SD) home systolic BP (SBP) levels over time and VIM were 134.2 (14.3) and 6.8 (2.5) mm Hg, respectively. During a 4-year follow-up period (16 750.3 person-years), 148 CVD events occurred. VIM was associated with CVD risk (hazard ratio per 1-SD increase, 1.32; 95% confidence interval [CI], 1.15-1.52), independently of mean home SBP levels over time and circulating B-type natriuretic peptide levels or urine albumin-to-creatinine ratio. Adding VIM to the CVD prediction model improved the discrimination (C statistic, 0.785 versus 0.770; C statistic difference, 0.015; 95% CI, 0.003-0.028). Changes in continuous net reclassification improvement (0.259; 95% CI, 0.052-0.537), absolute integrated discrimination improvement (0.010; 95% CI, 0.003-0.016), and relative integrated discrimination improvement (0.104; 95% CI, 0.037-0.166) were also observed with the addition of VIM to the CVD prediction models. In addition to the assessments of mean home SBP levels and cardiovascular end-organ damage, home BP variability measurements may provide a clinically useful distinction between high- and low-risk groups among Japanese outpatients.