Do renewable energy and natural gas consumption mitigate CO2 emissions in the USA? New insights from NARDL approach

Environmental Science and Pollution Research - This article attempts to explore the asymmetric impact of renewable energy and natural gas consumptions on CO2 emissions for the selected ten most...     

Fetal bradycardia in the first trimester: an unusual presentation of atrial extrasystoles

We report a fetus with fetal bradycardia at 13 weeks of gestation secondary to atrial extrasystoles. The fetus subsequently developed paroxysmal supraventricular tachycardia and hydrops fetalis. The cardiac arrhythmia recovered spontaneously without any medical intervention. This case illustrates that atrial ectopic beats can present in the first trimester with fetal bradycardia. Rapidly evolving hydrops fetalis secondary to supraventricular tachycardia can develop, warranting close monitoring with weekly heart rate assessment. Fetal bradycardia secondary to atrial extrasystole should be differentiated from first trimester sinus bradycardia and those associated with major structural cardiac abnormality, which have a high fetal loss rate. Copyright © 2002 John Wiley & Sons, Ltd.     

硅胶腕带被动采集多环芳烃的可行性分析

多环芳烃（polycyclic aromatic hydrocarbons,PAHs）对人体危害巨大,目前关于人体暴露于大气环境PAHs研究主要以主动采样方式开展。硅胶腕带作为一种新的大气被动采样装置,具有体积小、价格低、耐磨耐热、无毒无味等优点,适合人体环境暴露监测。国际上研究刚起步,尚未建立完善的腕带被动采样与主动采样技术之间的定量关系。本研究于2019年秋冬季和2021年冬季在西安市城区,同时开展硅胶腕带被动采样与大气主动采样对低分子量（MW＜203 g·mol^?1）PAHs的对比实验,力求建立两者的联系。2019年和2021年西安冬季大气中低分子量PAHs浓度分别为(52.81±14.76) ng·m^?3和(134.59±39.48) ng·m^?3,与前人研究相当。相对应的腕带浓度为(183.07±40.43) ng·d^?1和(524.99±150.32) ng·d^?1。Pearson相关分析发现：萘、苊烯、1-甲基萘、2-甲基萘、荧蒽以及总PAHs的主、被动采样之间显著相关（P＜0.05）,相关系数均大于0.4,证明硅胶腕带被动采样方法适用于低分子量PAHs的人体暴露监测。     

A study on torrefaction characteristics of waste sawdust in an auger type pyrolyzer

Torrefaction is thermo-chemical process which can improve solid fuel quality as well as grindability. In previous studies, torrefaction has been studied mainly for removal of moisture and for improving grindability. In this experiment, the characteristics of torrefied waste sawdust were studied especially for its energy yield. Hence, torrefaction was performed on varying reaction temperatures (200, 220, 240, 260, 280, 300 °C) and solid residence time (10, 30, 60 min). The results indicated that the yield of torrefaction decreases with increasing temperature and residence time. It was found that above 280 °C, the yield got remarkably decreased. The lowest yield was obtained at the residence time of 60 min. It was also noticed that the HHV of torrefied samples increases with increasing temperature. The highest HHV was found to be 26.09 MJ/kg which was obtained at 60 min and 300 °C. However, the highest energy yield was obtained to be 104.17 % which was noticed at 30 min and 260 °C.     

Characterization of food waste from different sources in Hong Kong

Food waste from different sources or at different generation stages may have different compositional characteristics and is therefore suitable for recycling into different products. To have a better understanding of their chemical composition, five food waste types were collected, namely, household kitchen waste (HH), preconsumption and postconsumption food waste from a hotel (Hpr and Hpo), wet market food waste (WM) and kitchen waste from a Chinese restaurant (CR), and their compositions were assessed monthly for 1 year. They served as suitable feedstock for various conversion technologies according to their chemical profiles. HH and CR had higher crude protein content (26%) and considerable amounts of minerals, making them nutritionally suitable for feeding animals. Preconsumption food wastes Hpr and WM had more favorable C:N ratios (16.5–17.4) and crude fat contents (4.6–6.5%) as feedstock for composting. Postconsumption food wastes were potential feedstock for the production of biogas and biodiesel because of the higher dry matter (>26%) and fat content (>13%). The coefficients of variation (CV) in all nutrients analyzed except Ca for postconsumption food wastes ranged from 5% to 37%, which showed lower temporal variability than preconsumption food wastes (CVs 10–131%). This implies that the composition of postconsumption food waste was relatively less fluctuating and can be considered a more reliable feedstock for food waste conversion.

Implications: Characterization of food waste composition from different sources and determination of their temporal variation were performed to understand their characteristics and facilitate sound food waste management. Separating food wastes according to their sources and types helps reduce their composition variability, and thus increases the consistence in food-waste-derived products and recycling success. Study on temporal variation indicates that postconsumption food wastes varied less with time and could serve as reliable feedstocks for food waste conversion.     

Improvement of Synthesis and Dielectric Properties of Polyurethane/Mt-QASs<Superscript>+</Superscript> (Novel Synthesis)

Polyurethane-based nanocomposites were prepared and their dielectric properties were characterized. Polyurethane (PU) composites were prepared with different organoclay content (1, 3, 5, and 10 wt% for all cases). The composites included quaternary ammonium salts such as 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS-1), 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS-2), and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS-3) which were newly synthesized for modification of Na⁺-montmorillonite. Addition of aluminum silicate enhanced the dielectric properties at a constant concentration. Dielectric constants of nanocomposites compounded with 3 %- and 5 %-organoclay were close in value. The characterization of PU/organoclay composites was carried out using Fourier transform infrared and X-ray diffraction.     

Effects of controller-pilot communication medium,flight phase and the role in the cockpit on pilots’ workload and situation awareness

This study explores the effects of communication medium, flight phase, and the role in the cockpit on pilots’ workload and situation awareness. Eight pilots with the experience of Controller-Pilot Data Link Communications (CPDLCs) participated in this simulated experiment. Two types of communication medium (voice and datalink), three types of flight phase (departure, cruise, and arrival), and two types of role (pilot flying and pilot non-flying) were investigated in the experiment. The results indicated that flight phase is a significant factor and cruise is the most suitable phase for datalink use on pilots’ acceptance, workload, and situation awareness performance. Both medium and role were not the significant factors. Since there is no significant difference on medium when no extra tasks and interferences involved in a normal flight, that the use of CPDLC can be justified during all phases of a no-event flight. In addition, the results of usability indicated that the simulated CPDLC with command selection functions proposed in this study provides good utility for the participants. In order to use the CPDLC for all phases of flight in the future, adding more command selection functions in place of typing messages by pilots and accommodating appropriate interfaces for different phases are recommended to enhance the usability of the CPDLC unit.     

Evaluation on exposures to particulate matter at a junior secondary school: a comprehensive study on health risks and effective inflammatory responses in Northwestern China

Air pollutant measurement and respiratory inflammatory tests were conducted at a junior secondary school in Xi’an, Northwestern China. Hazardous substances including particulate matters (PMs), black carbon (BC) and particle-bounded polycyclic aromatic hydrocarbons (PAHs) were quantified both indoors and outdoors of the school. Source characterization with organic tracers and particle-size distribution demonstrated that the school’s air was mostly polluted by combustion emissions from the surrounding environment. The evaluation of health assessment related to air quality was conducted by two methods, including potential risk estimation of air pollutants and direct respiratory inflammatory test. The incremental lifetime cancer risks associated with PAHs were estimated and were 1.62 × 10⁻⁶ and 2.34 × 10⁻⁶, respectively, for indoor and outdoor fine PMs. Both the values exceeded the threshold value of 1 × 10⁻⁶, demonstrating that the carcinogenic PAHs are a health threat to the students. Respiratory inflammatory responses of 50 students who studied in the sample classroom were examined with a fractional exhaled nitric oxide (FeNO) test, with the aid of health questionnaires. The average FeNO concentration was 17.4 ± 8.5 ppb, which was slightly lower than the recommended level of 20 ppb established by the American Thoracic Society for children. However, a wide distribution and 6% of the values were > 35 ppb, suggesting that the potentials were still high for eosinophilic inflammation and responsiveness to corticosteroids. A preliminary interpretation of the relationship between air toxins and respiratory inflammatory response demonstrated the high exposure cancer risks and inflammatory responses of the students to PMs in the city.