Dehydrating large amounts of sludge produced by sewage treatment plants is difficult.Microwave pretreatment can effectively and significantly improve the dewaterability and hydrogen production of sludge subjected to a...Dehydrating large amounts of sludge produced by sewage treatment plants is difficult.Microwave pretreatment can effectively and significantly improve the dewaterability and hydrogen production of sludge subjected to anaerobic digestion. The aim of this study was to investigate the effects of different microwave conditions on hydrogen production from anaerobic digestion and dewaterability of sludge. Based on an analysis of the electric field distribution, a spiral reactor was designed and a continuous microwave system was built to conduct intermittent and continuous experiments under different conditions. Settling Volume, Capillary Suction Time, particle size, and moisture content of the sludge were measured. The results show that sludge pretreatment in continuous experiments has equally remarkable dehydration performance as in intermittent experiments; the minimum moisture content was 77.29% in the intermittent experiment under a microwave power of 300 W and an exposure time of 60 sec, and that in the continuous experiment was 77.56% under a microwave power of 400 W and an exposure time of 60 sec.The peak measured by Differential Scanning Calorimeter appeared earliest under a microwave power of 600 W and an exposure time of 180 sec. The heat flux at the peak was 4.343 W/g, which is relatively small. This indicates that microwave pretreatment induced desirable effects. The maximum yield of hydrogen production was 7.967% under the conditions of microwave power of 500 W, exposure time of 120 sec, and water bath at 55℃. This research provides a theoretical and experimental basis for the development of a continuous microwave sludge-conditioning system.展开更多
Assessment of lung and heart states is of critical importance for patients with pneumonia.In this study,we present a small-sized and ultrasensitive accelerometer for continuous monitoring of lung and heart sounds to e...Assessment of lung and heart states is of critical importance for patients with pneumonia.In this study,we present a small-sized and ultrasensitive accelerometer for continuous monitoring of lung and heart sounds to evaluate the lung and heart states of patients.Based on two-stage amplification,which consists of an asymmetric gapped cantilever and a charge amplifier,our accelerometer exhibited an extremely high ratio of sensitivity to noise compared with conventional structures.Our sensor achieves a high sensitivity of 9.2V/g at frequencies less than 1000 Hz,making it suitable to use to monitor weak physiological signals,including heart and lung sounds.For the first time,lung injury,heart injury,and both lung and heart injuries in discharged pneumonia patients were revealed by our sensor device.Our sound sensor also successfully tracked the recovery course of the discharged pneumonia patients.Over time,the lung and heart states of the patients gradually improved after discharge.Our observations were in good agreement with clinical reports.Compared with conventional medical instruments,our sensor device provides rapid and highly sensitive detection of lung and heart sounds,which greatly helps in the evaluation of lung and heart states of pneumonia patients.This sensor provides a cost-effective alternative approach to the diagnosis and prognosis of pneumonia and has the potential for clinical and home-use health monitoring.展开更多
基金supported by a National Natural Science Fund project(No.51104022)teacher team construction Top-notch Youth Project(municipal)(No.PXM2016 014222 000043)
文摘Dehydrating large amounts of sludge produced by sewage treatment plants is difficult.Microwave pretreatment can effectively and significantly improve the dewaterability and hydrogen production of sludge subjected to anaerobic digestion. The aim of this study was to investigate the effects of different microwave conditions on hydrogen production from anaerobic digestion and dewaterability of sludge. Based on an analysis of the electric field distribution, a spiral reactor was designed and a continuous microwave system was built to conduct intermittent and continuous experiments under different conditions. Settling Volume, Capillary Suction Time, particle size, and moisture content of the sludge were measured. The results show that sludge pretreatment in continuous experiments has equally remarkable dehydration performance as in intermittent experiments; the minimum moisture content was 77.29% in the intermittent experiment under a microwave power of 300 W and an exposure time of 60 sec, and that in the continuous experiment was 77.56% under a microwave power of 400 W and an exposure time of 60 sec.The peak measured by Differential Scanning Calorimeter appeared earliest under a microwave power of 600 W and an exposure time of 180 sec. The heat flux at the peak was 4.343 W/g, which is relatively small. This indicates that microwave pretreatment induced desirable effects. The maximum yield of hydrogen production was 7.967% under the conditions of microwave power of 500 W, exposure time of 120 sec, and water bath at 55℃. This research provides a theoretical and experimental basis for the development of a continuous microwave sludge-conditioning system.
基金supported by the National Natural Science Foundation of China(51727901,81871484)。
文摘Assessment of lung and heart states is of critical importance for patients with pneumonia.In this study,we present a small-sized and ultrasensitive accelerometer for continuous monitoring of lung and heart sounds to evaluate the lung and heart states of patients.Based on two-stage amplification,which consists of an asymmetric gapped cantilever and a charge amplifier,our accelerometer exhibited an extremely high ratio of sensitivity to noise compared with conventional structures.Our sensor achieves a high sensitivity of 9.2V/g at frequencies less than 1000 Hz,making it suitable to use to monitor weak physiological signals,including heart and lung sounds.For the first time,lung injury,heart injury,and both lung and heart injuries in discharged pneumonia patients were revealed by our sensor device.Our sound sensor also successfully tracked the recovery course of the discharged pneumonia patients.Over time,the lung and heart states of the patients gradually improved after discharge.Our observations were in good agreement with clinical reports.Compared with conventional medical instruments,our sensor device provides rapid and highly sensitive detection of lung and heart sounds,which greatly helps in the evaluation of lung and heart states of pneumonia patients.This sensor provides a cost-effective alternative approach to the diagnosis and prognosis of pneumonia and has the potential for clinical and home-use health monitoring.
