RESUMO
Predicting and preventing disasters in difficult-to-access environments, such as oceans, requires self-powered monitoring devices. Since the need to periodically charge and replace batteries is an economic and environmental concern, energy harvesting from external stimuli to supply electricity to batteries is increasingly being considered. Especially, in aqueous environments including electrolytes, coiled carbon nanotube (CNT) yarn harvesters have been reported as an emerging approach for converting mechanical energy into electrical energy driven by large and reversible capacitance changes under stretching and releasing. To realize enhanced harvesting performance, experimental and computational approaches to optimize structural homogeneity and electrochemical accessible area in CNT yarns to maximize intrinsic electrochemical capacitance (IEC) and stretch-induced changes are presented here. Enhanced IEC further enables to decrease matching impedance for more energy efficient circuits with harvesters. In an ocean-like environment with a frequency from 0.1 to 1 Hz, the proposed harvester demonstrates the highest volumetric power (1.6-10.45 mW cm-3 ) of all mechanical harvesters reported in the literature to the knowledge of the authors. Additionally, a high electrical peak power of 540 W kg-1 and energy conversion efficiency of 2.15% are obtained from torsional and tensile mechanical energy.
RESUMO
The role of air filters is becoming increasingly important due to the threat of air pollution to public health. Understanding the lifetime of air filters is essential for assessing air pollution exposure. However, the effects of common environmental chemicals on filter performance have not been explored. Air filters in ventilation systems and air purifiers are commonly exposed to cigarette smoke aerosols. Moreover, due to the coronavirus pandemic, people are more likely to be in close proximity with smokers while wearing face masks, such that their masks will be exposed to cigarette aerosols. In this study, we applied a stepwise approach to analyze the effects of cigarette smoke on the filtration performance of electret melt-blown filter media that are commonly used to create face masks. We found that cigarette aerosols dramatically reduced filtration efficiency, while standard test particles of a similar loading weight did not affect filtration efficiency. After loading up to 204 µg/cm2 of cigarette smoke on 100 cm2 of electret filter medium, the filtration efficiency of some filters decreased from 92.5% to 33.3% (-Δ59.2%). Interestingly, we founded no changes in pressure drop following cigarette smoke exposure despite the reduction in filtration efficiency, suggesting that cigarette smoke aerosols significantly impact the electrostatic charge properties of the filters. Our results indicate that the lifetime of commonly-used air filters may be much shorter than expected and that people may unknowingly be directly exposed to airborne pollutants.
Assuntos
Filtros de Ar , Ar Condicionado , Filtração , Humanos , Fumaça/efeitos adversos , FumarRESUMO
Background The clinical significance of complete revascularization for ST segment elevation myocardial infarction (STEMI) pa-tients during admission is still debatable. Methods A total of 1406 STEMI patients from the Korean Myocardial Infarction Registry with multivessel diseases without cardiogenic shock who underwent primary percutaneous coronary intervention (PPCI) were analyzed. We used propensity score matching (PSM) to control differences of baseline characteristics between culprit only intervention (CP) and multivessel percutaneous coronary interventions (MP), and between double vessel disease (DVD) and triple vessel disease (TVD). The major adverse cardiac event (MACE) was analyzed for one year after discharge. Results TVD patients showed higher incidence of MACE (14.2%vs. 8.6%, P=0.01), any cause of revascularization (10.6%vs. 5.9%, P=0.01), and repeated PCI (9.5%vs. 5.7%, P=0.02), as compared to DVD patients during one year after discharge. MP reduced MACE effectively (7.3%vs. 13.8%, P=0.03), as compared to CP for one year, but all cause of death (1.6%vs. 3.2%, P=0.38), MI (0.4%vs. 0.8%, P=1.00), and any cause of revascularization (5.3%vs. 9.7%, P=0.09) were comparable in the two treatment groups. Conclusions STEMI patients with TVD showed higher rate of MACE, as compared to DVD. MP performed during PPCI or ad hoc during admission for STEMI patients without cardiogenic shock showed lower rate of MACE in this large scaled database. Therefore, MP could be considered as an effective treatment option for STEMI patients without cardiogenic shock.
