This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet ...This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.展开更多
AIM: Choledocholithiasis is present in 5 to 10 percent of patients who have cholelithiasis. Tn the area of laparoscopic cholecystectomy (LC), laparoscopic common bile duct exploration (LCBDE) and intraoperative endosc...AIM: Choledocholithiasis is present in 5 to 10 percent of patients who have cholelithiasis. Tn the area of laparoscopic cholecystectomy (LC), laparoscopic common bile duct exploration (LCBDE) and intraoperative endoscopic sphincterotomy (IOES) have been used to treat choledocholithiasis. The purpose of this study was to compare the clinical outcomes and hospital costs of LCBDE with IOES.METHODS: Between November 1999 and October 2002,patients with choledocholithiasis undergoing LC plus LCBDE (Group A, n=45) were retrospectively compared to those undergoing LC plus IOES (Group B, n=57) at a single institution.RESULTS: Ductal stone clearance rates were equivalent for the two groups (88 % versus 89 %, P=0.436). The conversion rate was higher for Group B (8.8 % versus 4.4 %,P=0.381), as was the morbidity (12.3 % versus 6.7 %,P=0.336). There were no other significant differences between the two groups. The complications were mainly related to endoscopic sphincterotomy (ES), and the hospital costs were significantly increased in this subset of Group B (median, 23 910 versus 14 955 RMB yuan, P=0.03). Although hospital stay was longer in Group A (median, 7 versus 6 days,P=0.041), the patients in Group A had a significantly decreased cost of hospitalization compared with those in Group B (median, L1 362 versus 15 466 RMB yuan, P=0.000).CONCLUSION: The results demonstrate equivalent ductal stone clearance rates for the two groups. LCBDE management appears safer, and is associated with a significantly decreased hospital cost. The findings suggest LCBDE for choledocholithiasis is a better option.展开更多
AIM: Transcystic biliary decompression (TCBD) has been proposed as an alternative to T-tube placement after laparoscopic choledochotomy (LCD). This permits safe primary closure of the choledochotomy and eliminates the...AIM: Transcystic biliary decompression (TCBD) has been proposed as an alternative to T-tube placement after laparoscopic choledochotomy (LCD). This permits safe primary closure of the choledochotomy and eliminates the complications associated with T-tubes. TCBD tube has been secured by Roeder knots and transfixation, and removed later than 3 wk after surgery. We presented a modified TCBD (mTCBD) method after LCD using the ureteral catheter and the Lapro-Clip (David and Geck, Danbury, Connecticut, USA), and compared it with T-tube drainage.METHODS: Between October 2002 and June 2003, patients with choledocholithiasis undergoing LCD with mTCBD (mTCBD Group, n = 30) were retrospectively compared to those undergoing LCD with T-tube drainage (T-tube Group,n = 52) at a single institution.RESULTS: There were no significant differences in operative time and retained stones between the two groups. Patients in mTCBD group had a significantly decreased average output of bile compared with those in T-tube group (306±141 vs 409±243 mL/24 h, P=0.000). Removal of dra in tubes inmTCBD group was done significantly earlier than that in T-tube group (median, 5 vs 29 d, P=0.000). No complication related to drain tubes was found in mTCBD group, and morbidity rate with the T-tube was significantly higher (11.5%), and bile leakage following T-tube removal was 5.8%.CONCLUSION: A modified TCBD after LCD is safe, effective and easy to perform. It may reduce postoperative complications, especially bile leakage.展开更多
AIM:To describe the use of hand-assisted laparoscopic surg-ery(HALS) as an alternative to open conversion for complex gall-stone diseases, including Mirizzi syndrome (MS) and mimic MS. METHODS: Five patients with MS a...AIM:To describe the use of hand-assisted laparoscopic surg-ery(HALS) as an alternative to open conversion for complex gall-stone diseases, including Mirizzi syndrome (MS) and mimic MS. METHODS: Five patients with MS and mimic MS of 232 consecutive patients undergoing laparoscopic cholecyst-ectomies were analyzed. HALS without a hand-port device was performed as an alternative to open conversion if the anatomy was still unclear after the neck of the gallbladder was reached. RESULTS: HALS was performed on three patients with MS type I and 2 with mimic MS owing to an unclear or abnormal anatomy, or an unusual circumstance in which an impacted stone was squeezed out from the infundibulum or the aberrant cystic duct impossible with laparoscopic approach. The median operative time was 165 min (range, 115-190 min). The median hand-assisted time was 75 min (range, 65-100 min). The median postoperative stay was 4 d (range, 3-5 d). The postoperative course was uneventful, except for 1 patient complicated with a minor incision infection. CONCLUSION: HALS for MS type I and mimic MS is safe and feasible. It simplifies laparoscopic procedure, and can be used as an alternative to open conversion for complex gallstone diseases.展开更多
Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering.Here,we numerically and experimentally present a design of a broadband ...Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering.Here,we numerically and experimentally present a design of a broadband lowfrequency absorber based on an acoustic metaporous composite(AMC).The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer.The finite element simulations show that a high absorption(absorptance A>0.8)can be achieved within a broad frequency range(from 290 Hz to 1074 Hz),while the thickness of AMC is 1/13of the corresponding wavelength at 290 Hz.The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode.The numerical simulations and experimental results are obtained to be in good agreement with each other.Moreover,the high broadband absorption can be maintained under random incident acoustic waves.The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.展开更多
中心性肥胖人群是指由于腹部脂肪的过量堆积引起诸多问题的一类人群。本研究通过使用不同重量等级的硅胶假肚子模拟腹部脂肪,表征不同程度的中心性肥胖,并测量分析了不同中心性肥胖等级人群在多种坐姿下臀腿部的压力分布。同时,对中心...中心性肥胖人群是指由于腹部脂肪的过量堆积引起诸多问题的一类人群。本研究通过使用不同重量等级的硅胶假肚子模拟腹部脂肪,表征不同程度的中心性肥胖,并测量分析了不同中心性肥胖等级人群在多种坐姿下臀腿部的压力分布。同时,对中心性肥胖体型人群的身体尺寸和坐姿体压分布进行了相关性分析,重点探讨了腰围、腰臀比、和腰围身高比与坐姿体压指标的相互关系。结果显示:腹部大小与臀腿部最大压力和最大压力梯度显著相关,整体上呈正相关,但并非是腹部越大压力越大的线性关系,与平均压力、座椅压力分布SPD%(Percentage of Seat Pressure Distribution)以及接触面积无显著相关。此外,腰围与体压指标的相关性相对较高,最大压力梯度与腰围之间存在较高的正相关性,腰围的增加伴随着最大压力梯度的上升。该研究所取得结果能够为中心性肥胖人群的坐姿建议和座椅研发提供科学依据。展开更多
Extremely-large-scale multiple-input multiple-output(XL-MIMO)technology,offering vast spatial degrees of freedom by deploying a huge number of antennas,is a promising enabling technology to empower sixthgeneration mob...Extremely-large-scale multiple-input multiple-output(XL-MIMO)technology,offering vast spatial degrees of freedom by deploying a huge number of antennas,is a promising enabling technology to empower sixthgeneration mobile networks(6G).The XL-MIMO channel model is a prerequisite of XL-MIMO technology optimization,system design,and performance evaluation.In this paper,we provide an overview of challenges and ongoing research in XL-MIMO channel measurement,characterization,and modeling.In particular,characterizing and modeling near-field effects and spatial non-stationarity(SnS)are discussed.Also,the channel modeling methods that can describe these new channel characteristics are surveyed.Furthermore,open issues in XL-MIMO channel measurement,characterization,and modeling are presented to give insights into future XL-MIMO channel research.展开更多
基金supported by the National Special Project for Science and Technology on Water Pollution Control and Management(No.2017ZX07102-003)the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(No.2020030257).
文摘This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.
文摘AIM: Choledocholithiasis is present in 5 to 10 percent of patients who have cholelithiasis. Tn the area of laparoscopic cholecystectomy (LC), laparoscopic common bile duct exploration (LCBDE) and intraoperative endoscopic sphincterotomy (IOES) have been used to treat choledocholithiasis. The purpose of this study was to compare the clinical outcomes and hospital costs of LCBDE with IOES.METHODS: Between November 1999 and October 2002,patients with choledocholithiasis undergoing LC plus LCBDE (Group A, n=45) were retrospectively compared to those undergoing LC plus IOES (Group B, n=57) at a single institution.RESULTS: Ductal stone clearance rates were equivalent for the two groups (88 % versus 89 %, P=0.436). The conversion rate was higher for Group B (8.8 % versus 4.4 %,P=0.381), as was the morbidity (12.3 % versus 6.7 %,P=0.336). There were no other significant differences between the two groups. The complications were mainly related to endoscopic sphincterotomy (ES), and the hospital costs were significantly increased in this subset of Group B (median, 23 910 versus 14 955 RMB yuan, P=0.03). Although hospital stay was longer in Group A (median, 7 versus 6 days,P=0.041), the patients in Group A had a significantly decreased cost of hospitalization compared with those in Group B (median, L1 362 versus 15 466 RMB yuan, P=0.000).CONCLUSION: The results demonstrate equivalent ductal stone clearance rates for the two groups. LCBDE management appears safer, and is associated with a significantly decreased hospital cost. The findings suggest LCBDE for choledocholithiasis is a better option.
文摘AIM: Transcystic biliary decompression (TCBD) has been proposed as an alternative to T-tube placement after laparoscopic choledochotomy (LCD). This permits safe primary closure of the choledochotomy and eliminates the complications associated with T-tubes. TCBD tube has been secured by Roeder knots and transfixation, and removed later than 3 wk after surgery. We presented a modified TCBD (mTCBD) method after LCD using the ureteral catheter and the Lapro-Clip (David and Geck, Danbury, Connecticut, USA), and compared it with T-tube drainage.METHODS: Between October 2002 and June 2003, patients with choledocholithiasis undergoing LCD with mTCBD (mTCBD Group, n = 30) were retrospectively compared to those undergoing LCD with T-tube drainage (T-tube Group,n = 52) at a single institution.RESULTS: There were no significant differences in operative time and retained stones between the two groups. Patients in mTCBD group had a significantly decreased average output of bile compared with those in T-tube group (306±141 vs 409±243 mL/24 h, P=0.000). Removal of dra in tubes inmTCBD group was done significantly earlier than that in T-tube group (median, 5 vs 29 d, P=0.000). No complication related to drain tubes was found in mTCBD group, and morbidity rate with the T-tube was significantly higher (11.5%), and bile leakage following T-tube removal was 5.8%.CONCLUSION: A modified TCBD after LCD is safe, effective and easy to perform. It may reduce postoperative complications, especially bile leakage.
文摘AIM:To describe the use of hand-assisted laparoscopic surg-ery(HALS) as an alternative to open conversion for complex gall-stone diseases, including Mirizzi syndrome (MS) and mimic MS. METHODS: Five patients with MS and mimic MS of 232 consecutive patients undergoing laparoscopic cholecyst-ectomies were analyzed. HALS without a hand-port device was performed as an alternative to open conversion if the anatomy was still unclear after the neck of the gallbladder was reached. RESULTS: HALS was performed on three patients with MS type I and 2 with mimic MS owing to an unclear or abnormal anatomy, or an unusual circumstance in which an impacted stone was squeezed out from the infundibulum or the aberrant cystic duct impossible with laparoscopic approach. The median operative time was 165 min (range, 115-190 min). The median hand-assisted time was 75 min (range, 65-100 min). The median postoperative stay was 4 d (range, 3-5 d). The postoperative course was uneventful, except for 1 patient complicated with a minor incision infection. CONCLUSION: HALS for MS type I and mimic MS is safe and feasible. It simplifies laparoscopic procedure, and can be used as an alternative to open conversion for complex gallstone diseases.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174197,11874222,and 12027808)。
文摘Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering.Here,we numerically and experimentally present a design of a broadband lowfrequency absorber based on an acoustic metaporous composite(AMC).The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer.The finite element simulations show that a high absorption(absorptance A>0.8)can be achieved within a broad frequency range(from 290 Hz to 1074 Hz),while the thickness of AMC is 1/13of the corresponding wavelength at 290 Hz.The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode.The numerical simulations and experimental results are obtained to be in good agreement with each other.Moreover,the high broadband absorption can be maintained under random incident acoustic waves.The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.
文摘中心性肥胖人群是指由于腹部脂肪的过量堆积引起诸多问题的一类人群。本研究通过使用不同重量等级的硅胶假肚子模拟腹部脂肪,表征不同程度的中心性肥胖,并测量分析了不同中心性肥胖等级人群在多种坐姿下臀腿部的压力分布。同时,对中心性肥胖体型人群的身体尺寸和坐姿体压分布进行了相关性分析,重点探讨了腰围、腰臀比、和腰围身高比与坐姿体压指标的相互关系。结果显示:腹部大小与臀腿部最大压力和最大压力梯度显著相关,整体上呈正相关,但并非是腹部越大压力越大的线性关系,与平均压力、座椅压力分布SPD%(Percentage of Seat Pressure Distribution)以及接触面积无显著相关。此外,腰围与体压指标的相关性相对较高,最大压力梯度与腰围之间存在较高的正相关性,腰围的增加伴随着最大压力梯度的上升。该研究所取得结果能够为中心性肥胖人群的坐姿建议和座椅研发提供科学依据。
基金Project supported by the National Natural Science Foundation of China(Nos.62201086,62101069,and 92167202)the National Science Fund for Distinguished Young Scholars(No.61925102)the BUPT-CMCC Joint Innovation Center。
文摘Extremely-large-scale multiple-input multiple-output(XL-MIMO)technology,offering vast spatial degrees of freedom by deploying a huge number of antennas,is a promising enabling technology to empower sixthgeneration mobile networks(6G).The XL-MIMO channel model is a prerequisite of XL-MIMO technology optimization,system design,and performance evaluation.In this paper,we provide an overview of challenges and ongoing research in XL-MIMO channel measurement,characterization,and modeling.In particular,characterizing and modeling near-field effects and spatial non-stationarity(SnS)are discussed.Also,the channel modeling methods that can describe these new channel characteristics are surveyed.Furthermore,open issues in XL-MIMO channel measurement,characterization,and modeling are presented to give insights into future XL-MIMO channel research.
