[en] In order to operate a Power conversion system (PCS) reliably, which is used for solar or wind power generation and energy storage systems, a design engineer of a PCS must evaluate that the junction temperature of power semiconductor devices, such as an Insulatedgate bipolar transistor (IGBT) module, meets the design criteria in the cooling design stage. An engineer must have evaluation procedure to design the airflow passage structure of a PCS in a way that the heat generated from inside of the system can be effectively exhausted externally. This study investigated the thermal performance of a PCS for four different airflow passage structures using the airflow rate of the heat sink attached to the IGBT module as an evaluation index. Out of the suggested airflow passage structures, the structure using the upper supply-lower exhaust type without the cooling fan for the reactor, which forms the air curtain around the airflow passage guide of the IGBT module and the louver of the maintenance door, has been found to perform the best thermal performance. In this design, the airflow rate of the heat sink was approximately 14 % larger than the required rate, with the junction temperature of the IGBT module of 132.2 °C, which satisfied the cooling design criteria. When the ventilation area of the supply is increased by approximately 2.3 times and the thickness of the filter reduced by 10 mm, the airflow rate of the heat sink can reach up to 700.4 m3hr-1, and in this case, the design criteria of the IGBT module can be satisfied even in an overload condition of 106.7 % of the rated load.

[en] The read/write performance and yield of a negative capacitance field effect transistor (NCFET)-based eight-transistor (8-T) static random access memory (SRAM) are quantitatively evaluated and then compared with a conventional 8-T SRAM. The performance of the 8-T SRAM cell is analyzed by read/write metrics (i.e. read static noise margin, write-ability current and read ‘zero (0)’ current). The sensitivity of the 8-T SRAM cell to the read/write metric is estimated by quantitatively evaluating the impact of systematic variation (i.e. channel width, length and threshold voltage variation). Based on variation-aware sensitivity analysis, quantitative yield estimation is done using the ‘cell sigma’ concept. Finally, the minimum power supply voltage (V _DD) (which satisfies six cell sigma for yield estimation of a NCFET-based/baseline 8-T SRAM cell) is quantitatively estimated. (paper)

[en] Despite their popular use and emerging evidences of adverse health effects, consequent trends in population level triclosan and benzophenone-3 exposure have been poorly evaluated. Therefore, we examined temporal trends of urinary triclosan and benzophenone-3 concentration in the general U.S. population by combining five cycles of National Health and Nutritional Examination Survey (NHANES, 2003–2012) data. We calculated percent changes and the least square geometric means (LSGMs) of urinary triclosan and benzophenone-3 concentration from 10,232 participants by using multivariable regression models. As a result, LSGM concentration of urinary triclosan and benzophenone-3 did not show statistically significant changes over the study period. [Percent change (95% CI): Triclosan, −7.35% (−20.86, 8.47); Benzophenone-3, 7.08% (−27.88, 58.99)] However, we found decreasing trend of urinary triclosan concentration and increasing trend of urinary benzophenone-3 concentration since 2005–2006. Socio-demographic factors which affected urinary concentration of triclosan and benzophenone-3 persisted throughout 10 year study period. Highest income group showed higher level of urinary triclosan and benzophenone-3 concentration. Overall concentration of benzophenone-3 was higher in female than in male, and higher in non-Hispanic Whites than any other races/ethnicities. - Highlights: • We analyzed 2003–2012 NHANES to evaluate temporal trends in triclosan and BP3 exposure levels. • There was decreasing trend of urinary triclosan concentration since 2005–2006. • There was increasing trend of urinary BP3 concentration since 2005–2006. • Urinary triclosan and BP3 concentration of each NHANES cycle varied by socio-demographic factors. - In the analysis of 2003–2012 National Health and Nutrition Examination Surveys data, we found decreasing trend of urinary triclosan concentration and increasing trend of urinary Benzophenone-3 concentration since 2005–2006.

[en] Highlights: • We did a systematic review of studies on blood pressure effects of PM respirator use. • Seven randomized crossover studies were selected for our systematic review. • Use of PM respirator was associated with −1.23 and −1.57 mmHg change in SBP and MAP. • However, significant heterogeneities and publication bias were observed. • Further interventions on blood pressure effects of PM respirator are needed. People use a particulate respirator in order to reduce exposure to ambient fine particulate matter (PM_2.5). Acute exposure to PM_2.5 is known to increase blood pressure. However, systematic reviews or meta-analyses on blood pressure-related benefits of using a particulate respirator is lacking. Therefore, we reviewed randomized crossover intervention studies on blood pressure-related effects of particulate matter respirator use. We conducted a literature review of articles found on Embase, Medline, and Cochrane library on August 31, 2020. The study outcomes were systolic and diastolic blood pressure and mean arterial pressure. A random-effect model was used in the meta-analysis. Subgroup analyses, based on age (adult < 60 years, elderly ≥ 60 years), personal PM_2.5 exposure levels (High: ≥ 25 μg/m³, Low: < 25 μg/m³), and types of monitoring methods (ambulatory and resting blood pressure) were conducted. We identified 297 references, and seven studies were included in our systematic review. None of the studies used a sham respirator as control and complete allocation concealment and blinding were impossible. The use of a particulate respirator was associated with a −1.23 mmHg (95% confidence interval (CI): −2.53, 0.07) change in systolic blood pressure and a −1.57 mmHg (95% CI: −3.85, 0.71) change in mean arterial pressure. There were significant heterogeneities and possibilities for publication bias. The subgroup analyses revealed that studies involving elderly individuals, those conducted in high PM_2.5 personal exposure, and those in which resting blood pressure was monitored demonstrated a larger decrease in blood pressure resulting from respirator use. Further intervention studies with a large sample size and subjects with diverse characteristics and different personal PM_2.5 levels may add the evidence to current literature.

[en] Although many studies have evaluated the effects of ambient particulate matter with diameters of less than 2.5 μm (PM_2.5) on stroke mortality in the general population, little is known about the mortality effects of PM_2.5 in post-stroke populations. Therefore, a retrospective cohort was constructed using information from the health insurance database to evaluate whether exposure to PM_2.5 is associated with increased mortality in aged stroke survivors residing in seven Korean metropolitan cities. A total of 45,513 older adults (≥65 years) who visited emergency rooms due to stroke and who were discharged alive between 2008 and 2016 were followed up. By using district-level modeled PM_2.5 concentrations and a time-varying Cox proportional hazard model, associations between 1-month and 2-month moving average PM_2.5 exposures and mortality in stroke survivors were evaluated. The annual average concentration of PM_2.5 was 27.9 μg/m³ in the seven metropolitan cities, and 14,880 subjects died during the follow-up period. A 10 μg/m³ increase in the 1-month and 2-month moving average PM_2.5 exposures was associated with mortality hazard ratios of 1.07 (95% confidence interval: 1.05, 1.09) and 1.06 (95% confidence interval: 1.03, 1.08), respectively. The effects of PM_2.5 were similar across types of stroke (ischemic and hemorrhagic), age groups (65–74, 75–84, and ≥85), and income groups (low and high) but were greater in women than in men. This study highlights the adverse health effects of ambient PM_2.5 in post-stroke populations. Active avoidance behaviors against PM_2.5 are recommended for aged stroke survivors.