Intraday effects of ambient PM1 on emergency department visits in Guangzhou, China: A case-crossover study

Background: Short-term exposure to PM2.5 has been widely associated with human morbidity and mortality. However, most up-to-date research was conducted at a daily timescale, neglecting the intra-day variations in both exposure and outcome. As an important fraction in PM2.5, PM1 has not been investigated about the very acute effects within a few hours. Methods: Hourly data for size-specific PMs (i.e., PM1, PM2.5, and PM10), all-cause emergency department (ED) visits and meteorological factors were collected from Guangzhou, China, 2015–2016. A time-stratified case-crossover design with conditional logistic regression analysis was performed to evaluate the hourly association between size-specific PMs and ED visits, adjusting for hourly mean temperature and relative humidity. Subgroup analyses stratified by age, sex and season were conducted to identify potential effect modifiers. Results: A total of 292,743 cases of ED visits were included. The effects of size-specific PMs exhibited highly similar lag patterns, wherein estimated odds ratio (OR) experienced a slight rise from lag 0–3 to 4–6 h and subsequently attenuated to null along with the extension of lag periods. In comparison with PM2.5 and PM10, PM1 induced slightly larger effects on ED visits. At lag 0–3 h, for instance, ED visits increased by 1.49% (95% confidence interval: 1.18–1.79%), 1.39% (1.12–1.66%) and 1.18% (0.97–1.40%) associated with a 10-μg/m3 rise, respectively, in PM1, PM2.5 and PM10. We have detected a significant effect modification by season, with larger PM1-associated OR during the cold months (1.017, 1.013 to 1.021) compared with the warm months (1.010, 1.005 to 1.015). Conclusions: Our study provided brand-new evidence regarding the adverse impact of PM1 exposure on human health within several hours. PM-associated effects were significantly more potent during the cold months. These findings may aid health policy-makers in establishing hourly air quality standards and optimizing the allocation of emergency medical resources

Structure-Property Relationship in High Strength- High Ductility Combination Austenitic Stainless Steels

Austenitic stainless steels are widely used in our daily life, but their mechanical strength is low. In order to improve their yield strength via grain refinement, an investigation was carried out involving phase reversion annealing concept comprising of severe cold roll reduction followed by annealing at different temperatures for short durations. During annealing reversion of deformation-induced martensite to austenite occurred by shear mechanism, leading to fine-grained structure and high strength-high ductility combination. Nanoscale deformation studies suggested that the deformation mechanism of nanograined structure was different from the coarse-grained counterpart. Post-mortem electron microscopy of plastic zone surrounding the indent indicated that the active deformation mechanism was nanoscale twinning with typical characteristics of a network of intersecting twins in the nanograined structure, while strain-induced martensite transformation was the effective deformation mechanism for the coarse-grained structure. The presence of ~3 wt % Cu in austenitic stainless steel had a moderate effect on strain-rate sensitivity and activation volume at similar grain size in relation to the Cu-free counterpart. The nanoscale twin density was noticeably higher in Cu-bearing austenitic stainless steel as compared to Cu-free counterpart, a behavior that may be related to the increase of stacking fault energy. Furthermore, the synergistic effect of grain boundary and grain orientation on micro-mechanical properties of austenitic stainless steel was studied. Micro/nano-scale deformation behavior including hardness, elastic modulus, and pop-ins, was studied. Relatively higher hardness and modulus was observed near {101} and more pop-ins occurred in this orientation at high loading rate. From the perspective of engineering applications, the wear performance of fine-grained austenitic stainless steel through three-body abrasive wear tests at room and high temperatures was compared with the coarse-grained counterpart. The study demonstrated that fine austenite grains with high yield strength and elongation exhibited superior wear resistance at high temperature (250 °C), which was attributed to deformation twinning-induced plasticity in fine austenite grains. The wear mechanisms were microploughing and microcutting

Association between sleep duration and high blood pressure in adolescents: a systematic review and meta-analysis

Context: Sleep has been assessed as a risk factor for health consequences. Among adults, excessively longer and shorter sleep durations are associated with high blood pressure (BP), but knowledge of the association between sleep duration and high BP among adolescents is limited. Objectives: To estimate the associations between sleep duration and high BP in adolescents. Methods: PubMed, Web of Science, and Cochrane databases were searched for eligible publications up until 20 November 2017. This study reviewed the reference lists from retrieved articles to search for relevant studies. Pooled odds ratios (ORs) were calculated using a random-effects meta-analysis. Sub-group and sensitivity analyses were conducted to identify heterogeneity. Publication bias was evaluated using Egger’s test. Results: Seven studies involving 21,150 participants were included, with ages ranging from 10–18 years. For primary analysis, compared with the reference sleep duration, the pooled OR for high BP was 1.51 (95% confidence interval [CI] = 1.04–2.19) for the short sleep duration overall. For long sleep duration, the pooled OR was 1.04 (95% CI = 0.78–1.38). Further sub-group analysis showed that short sleep duration had a higher risk of incident high BP in males (OR = 1.55, 95% CI = 1.24–1.93) than in females (OR = 1.23, 95% CI = 0.47–3.22). Conclusions: Among adolescents, and particularly male adolescents, short sleep duration may be a risk factor for high BP. More attention should be given to this lifestyle factor

A Heavily Surface-Doped Polymer with the Bifunctional Catalytic Mechanism in Li-O2 Batteries

Summary: The application of conducting polymers (CPs) in energy storage systems is greatly limited by insufficient reversibility and stability. Here, we successfully incorporated functionalized dopants (Fe(CN)63− [FCN] and PO43− ions) in CPs matrixes to achieve a preferable electrochemical performance. A stable cation inserting/expulsing behavior of surface-doped polycarbazole (PCz) is demonstrated in our work, where doping levels and semiconductor properties of PCz are effectively controlled to adjust their redox properties and stability. With carbon nanotube (CNT) films as the substrate, the CNT/PCz:FCN composite is initially adopted as a free-standing catalytic electrode in Li-O2 cells. The molecule-level dispersed FCN dopants on the surface can work as bifunctional redox mediators on the charge-discharge process. Thus, this composite can not only achieve a low charge plateau of 3.62 V and a regular growth of capacities from 1,800 to 4,800 mAh/gCNT, but also maintain the most of charge voltages under 4.0 V for 150 cycles. : Catalysis; Energy Storage; Polymers Subject Areas: Catalysis, Energy Storage, Polymer

Research on ADRC controller of bidirectional DC–DC​ converter for MMC-BESS

The flexible interconnection AC/DC hybrid system with modular multilevel converter (MMC) as the core interface can comprehend the centralized get right of entry to of different and decentralized resources, decorate the reliability of strength supply, and enhance new energy consumption. However, the intermittence and fluctuation of distributed generations affect the safety and stability of flexible interconnected AC/DC hybrid systems. MMC based on battery energy storage system (MMC-BESS) can stabilize power fluctuations on the AC and DC sides of the system and improve the stability of the system. In order to improve the rapidity and immunity of MMC-BESS, this paper presents an active disturbance rejection control (ADRC) strategy for the bidirectional DC–DC converter of MMC-BESS. The voltage fluctuations of the interface capacitor in the energy storage and the current fluctuations of the inductor in the bidirectional DC–DC converter are discussed. Moreover, ADRC controller is designed for the bidirectional DC–DC converter of MMC-BESS. At last, simulations under different load mutations on the DC side and unbalanced three-phase grid voltage are carried out for verification of the performance of the ADRC control strategy in MMC-BESS. The results show that MMC-BESS based on ADRC strategy has more favorable rapidity and immunity than PI strategy, and is helpful to practical application in flexible interconnected AC/DC hybrid system in the future

Association between Short-Term Exposure to Ozone and Heart Rate Variability: A Systematic Review and Meta-Analysis

At present, ambient air pollution poses a significant threat to patients with cardiovascular disease (CVD). The heart rate variability (HRV) is a marker of the cardiac autonomic nervous system, and it is related to air pollution and cardiovascular disease. There is, however, considerable disagreement in the literature regarding the association between ozone (O3) and HRV. To further investigate the effects of short-term exposure to O3 on HRV, we conducted the first meta-analysis of relevant studies. The percentage change of HRV indicator(s) is the effect estimate extracted for the quantitative analysis in this study. In our meta-analysis, per 10 ppb increase in O3 was significantly associated with decreases in the time-domain measurements, for standard deviation of the normal-to-normal (NN) interval (SDNN) −1.11% (95%CI: −1.35%, −0.87%) and for root mean square of successive differences (RMSSD) −3.26% (95%CI: −5.42%, −1.09%); in the frequency-domain measurements, for high frequency (HF) −3.01% (95%CI: −4.66%, −1.35%) and for low frequency (LF) −2.14% (95%CI: −3.83%, −0.45%). This study showed short-term exposure to O3 was associated with reduced HRV indicators in adults, which suggested that the cardiac autonomic nervous system might be affected after O3 exposure, contributing to the association between O3 exposure and CVD risk

Phase Transformation Temperature Prediction in Steels via Machine Learning

The phase transformation temperature plays an important role in the design, production and heat treatment process of steels. In the present work, an improved version of the gradient-boosting method LightGBM has been utilized to study the influencing factors of the four phase transformation temperatures, namely Ac1, Ac3, the martensite transformation start (MS) temperature and the bainitic transformation start (BS) temperature. The effects of the alloying element were discussed in detail by comparing their influencing mechanisms on different phase transformation temperatures. The training accuracy was significantly improved by further introducing appropriate features related to atomic parameters. The melting temperature and coefficient of linear thermal expansion of the pure metals corresponding to the alloying elements, atomic Waber–Cromer pseudopotential radii and valence electron number were the top four among the eighteen atomic parameters used to improve the trained model performance. The training and prediction processes were analyzed using a partial dependence plot (PDP) and Shapley additive explanation (SHAP) methods to reveal the relationships between the features and phase transformation temperature