The parasitic polysulfides shuttle effect greatly hinders the practical application of lithium sulfur batteries,and this issue can be addressed by promoting polysulfides conversion with catalytic materials such as Mo ...The parasitic polysulfides shuttle effect greatly hinders the practical application of lithium sulfur batteries,and this issue can be addressed by promoting polysulfides conversion with catalytic materials such as Mo S_(2).However,the catalytic activity of Mo S_(2)mainly relies on edge sites,but is limited by inert basal planes.We herein report a novel,facile,ethylene glycol enabled competing reduction strategy to dope Mo S_(2)homogeneously with oxygen atoms so that its inert basal planes can be unlocked.Ethylene glycol works as a reducing agent and competes with thiourea to react with ammonium molybdate,leading to insufficient sulfuration of Mo,and consequent formation of O-Mo S_(2).Our theoretical and experimental investigations indicate that the homogeneously distributed O dopants can create abundant adsorption/-catalytic sites in the Mo S_(2)basal planes,enlarge the inter-plane distance to promote ion transport,and thus enhance the catalytic conversion of polysulfides.The oxygen doped Mo S_(2)(O-Mo S_(2))is supported on carbon nanosheets(CNS)and the composite(O-Mo S_(2)/CNS)is employed to modify the separator of Li-S battery.It gives the battery an initial discharge capacity of 1537 m Ah g-1at 0.2 C,and the battery retains a discharge capacity of 545 m Ah g-1after ultra-long 2000 cycles at 1 C,corresponding to a very small cyclic decay rate of 0.0237%.Even under a raising sulfur loading of 8.2 mg cm^(-2),the Li-S battery also delivers a high discharge capacity(554 m Ah g^(-1))with outstanding cycle stability(84.6%capacity retention)after 100 cycles at 0.5 C.Our work provides a novel,facile approach to fabricate highly catalytically active oxygen-doped Mo S_(2)for advanced Li-S batteries.展开更多
<strong>Background:</strong> A large percentage of deaths in an epidemic or pandemic can be due to overshoot of population (herd) immunity, either from the initial peak or from planned or unplanned exit fr...<strong>Background:</strong> A large percentage of deaths in an epidemic or pandemic can be due to overshoot of population (herd) immunity, either from the initial peak or from planned or unplanned exit from lockdown or social distancing conditions. <strong>Objectives:</strong> We study partial unlock or reopening interaction with seasonal effects in a managed epidemic to quantify overshoot effects on small and large unlock steps and discover robust strategies for reducing overshoot. <strong>Methods:</strong> We simulate partial unlock of social distancing for epidemics over a range of replication factor, immunity duration and seasonality factor for strategies targeting immunity thresholds using overshoot optimization. <strong>Results:</strong> Seasonality change must be taken into account as one of the steps in an easing sequence, and a two-step unlock, including seasonal effects, minimizes overshoot and deaths. It may cause undershoot, which causes rebounds and assists survival of the pathogen. <strong>Conclusions:</strong> Partial easing levels, even low levels for economic relief while waiting on a vaccine, have population immunity thresholds based on the reduced replication rates and may experience overshoot as well. We further find a two-step strategy remains highly sensitive to variations in case ratio, replication factor, seasonality and timing. We demonstrate a three or more step strategy is more robust, and conclude that the best possible approach minimizes deaths under a range of likely actual conditions which include public response.展开更多
The summit’s theme reflects the shared aspiration of G20 member states to steer the world economy towards a more sustainable path.A key success of the G20 in the aftermath of the financial crisis has been to signific...The summit’s theme reflects the shared aspiration of G20 member states to steer the world economy towards a more sustainable path.A key success of the G20 in the aftermath of the financial crisis has been to significantly strengthen the resilience of the global financial system.Now we need to focus on ways in展开更多
The traditional telecommunications operator of China has entered into a substantive network construction stage of NGN and new VoIP service in 2006. As the increasing understanding and the consideration of cost to VoIP...The traditional telecommunications operator of China has entered into a substantive network construction stage of NGN and new VoIP service in 2006. As the increasing understanding and the consideration of cost to VoIP, VoIP has become more acceptable for CIO of large-scale enterprises. Small and medium-scale enterprises are sensitive to communication cost, but influenced by the maturity of VoIP technology and reduction of VoIP equipment price, the market is intensified. All these drive the VoIP equipment entering into the actual purchase stage and promote the stable growth of VoIP equipment scale.展开更多
IN December 2012, as corporate South Africa closed down for the holiday season, more than 4,500 members of the ruling African National Congress （ANC） descended on the city of Mangaung to elect their leadership for t...IN December 2012, as corporate South Africa closed down for the holiday season, more than 4,500 members of the ruling African National Congress （ANC） descended on the city of Mangaung to elect their leadership for the next five years, and ultimately determine the future of South Africa＇s development.展开更多
Investment remains the vital ingredient for Africa’s success WHILE there are meaningful objections to the nature and structure of much of the new investment in African agriculture,it is clear that the introduction of...Investment remains the vital ingredient for Africa’s success WHILE there are meaningful objections to the nature and structure of much of the new investment in African agriculture,it is clear that the introduction of new capital,skills and technology is an essential component in unlocking the continent’s ultimate allure.展开更多
Purpose:Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures,especially in osteoporotic patients.The purpose of this study is to prospecti...Purpose:Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures,especially in osteoporotic patients.The purpose of this study is to prospectively investigate the effect of distal locking in long PFNA-II fixation of stable intertrochanteric fractures.Methods:A total of 58 patients with isolated stable intertrochanteric fractures and treated in our hospital during the study period of 2017–2019 by distal locked or unlocked long PFNA-II fixation were included in this study.Patients who had multiple injuries or open fractures were excluded.There were 40 female and 18 male patients,with 33 affecting the left side and 25 the right side.Of them,31 belonged to the distal locked group (group A) and 27 to the unlocked group (group B).Surgical procedures and implants used in both groups were similar except for the distal locking of the nails.General data (age,gender,fracture side,etc.) showed no significant difference between two groups (allp > 0.05).The intraoperative parameters like operative time,radiation exposure and follow-up parameters like functional and radiological outcomes were recorded and compared.Statistical tests like the independent samplest-test Fischer’’s exact and Chi-square test were used to analyze association.Results:The distribution of the fractures according to AO/OTA classification and 31A1.2 type of intertrochanteric fractures were most common in our study.All the included fractures united and the average functional outcome in both groups were good and comparable at the end of one year.The operative time (mL,107.1 ± 12.6vs.77.0 ± 12.0,p < 0.001) and radiation exposure (s,78.6 ± 11.0vs.40.3 ± 9.3,p < 0.001) were significantly less among the patients in group B.Fracture consolidation,three months after the operative procedures,was seen in a significantly greater proportion of patients in group B (92.6%vs.67.7%,p = 0.025).Hardware irritation because of distal locking bolt was exclusively seen in group A,however this was not statistically significant (p = 0.241).Conclusion:We conclude that,in fixation of stable intertrochanteric fractures by long PFNA-II nail,distal locking not only increases the operative time and radiation exposure but also delays the fracture consolidation and increases the chances of hardware irritation,and hence is not required.展开更多
基金financial support from the fund for Creative Research Groups of the National Natural Science Foundation of China(22021005)the Science and Technology Innovation Fund of Dalian(2018J12GX052)+3 种基金the National Natural Science Foundation of China(21776042,22108027)the Fundamental Research Funds for the Central Universities of China(DUT19ZD214)the Shenzhen Science and Technology Program(201908163000519)the GDSTC-Key R&D Project(GDSTC No.2019B090908001)。
文摘The parasitic polysulfides shuttle effect greatly hinders the practical application of lithium sulfur batteries,and this issue can be addressed by promoting polysulfides conversion with catalytic materials such as Mo S_(2).However,the catalytic activity of Mo S_(2)mainly relies on edge sites,but is limited by inert basal planes.We herein report a novel,facile,ethylene glycol enabled competing reduction strategy to dope Mo S_(2)homogeneously with oxygen atoms so that its inert basal planes can be unlocked.Ethylene glycol works as a reducing agent and competes with thiourea to react with ammonium molybdate,leading to insufficient sulfuration of Mo,and consequent formation of O-Mo S_(2).Our theoretical and experimental investigations indicate that the homogeneously distributed O dopants can create abundant adsorption/-catalytic sites in the Mo S_(2)basal planes,enlarge the inter-plane distance to promote ion transport,and thus enhance the catalytic conversion of polysulfides.The oxygen doped Mo S_(2)(O-Mo S_(2))is supported on carbon nanosheets(CNS)and the composite(O-Mo S_(2)/CNS)is employed to modify the separator of Li-S battery.It gives the battery an initial discharge capacity of 1537 m Ah g-1at 0.2 C,and the battery retains a discharge capacity of 545 m Ah g-1after ultra-long 2000 cycles at 1 C,corresponding to a very small cyclic decay rate of 0.0237%.Even under a raising sulfur loading of 8.2 mg cm^(-2),the Li-S battery also delivers a high discharge capacity(554 m Ah g^(-1))with outstanding cycle stability(84.6%capacity retention)after 100 cycles at 0.5 C.Our work provides a novel,facile approach to fabricate highly catalytically active oxygen-doped Mo S_(2)for advanced Li-S batteries.
文摘<strong>Background:</strong> A large percentage of deaths in an epidemic or pandemic can be due to overshoot of population (herd) immunity, either from the initial peak or from planned or unplanned exit from lockdown or social distancing conditions. <strong>Objectives:</strong> We study partial unlock or reopening interaction with seasonal effects in a managed epidemic to quantify overshoot effects on small and large unlock steps and discover robust strategies for reducing overshoot. <strong>Methods:</strong> We simulate partial unlock of social distancing for epidemics over a range of replication factor, immunity duration and seasonality factor for strategies targeting immunity thresholds using overshoot optimization. <strong>Results:</strong> Seasonality change must be taken into account as one of the steps in an easing sequence, and a two-step unlock, including seasonal effects, minimizes overshoot and deaths. It may cause undershoot, which causes rebounds and assists survival of the pathogen. <strong>Conclusions:</strong> Partial easing levels, even low levels for economic relief while waiting on a vaccine, have population immunity thresholds based on the reduced replication rates and may experience overshoot as well. We further find a two-step strategy remains highly sensitive to variations in case ratio, replication factor, seasonality and timing. We demonstrate a three or more step strategy is more robust, and conclude that the best possible approach minimizes deaths under a range of likely actual conditions which include public response.
文摘The summit’s theme reflects the shared aspiration of G20 member states to steer the world economy towards a more sustainable path.A key success of the G20 in the aftermath of the financial crisis has been to significantly strengthen the resilience of the global financial system.Now we need to focus on ways in
文摘The traditional telecommunications operator of China has entered into a substantive network construction stage of NGN and new VoIP service in 2006. As the increasing understanding and the consideration of cost to VoIP, VoIP has become more acceptable for CIO of large-scale enterprises. Small and medium-scale enterprises are sensitive to communication cost, but influenced by the maturity of VoIP technology and reduction of VoIP equipment price, the market is intensified. All these drive the VoIP equipment entering into the actual purchase stage and promote the stable growth of VoIP equipment scale.
文摘IN December 2012, as corporate South Africa closed down for the holiday season, more than 4,500 members of the ruling African National Congress （ANC） descended on the city of Mangaung to elect their leadership for the next five years, and ultimately determine the future of South Africa＇s development.
文摘Investment remains the vital ingredient for Africa’s success WHILE there are meaningful objections to the nature and structure of much of the new investment in African agriculture,it is clear that the introduction of new capital,skills and technology is an essential component in unlocking the continent’s ultimate allure.
文摘Purpose:Long proximal femoral nail anti-rotation (PFNA-II) is a preferred implant in recent years for fixation of pertrochanteric fractures,especially in osteoporotic patients.The purpose of this study is to prospectively investigate the effect of distal locking in long PFNA-II fixation of stable intertrochanteric fractures.Methods:A total of 58 patients with isolated stable intertrochanteric fractures and treated in our hospital during the study period of 2017–2019 by distal locked or unlocked long PFNA-II fixation were included in this study.Patients who had multiple injuries or open fractures were excluded.There were 40 female and 18 male patients,with 33 affecting the left side and 25 the right side.Of them,31 belonged to the distal locked group (group A) and 27 to the unlocked group (group B).Surgical procedures and implants used in both groups were similar except for the distal locking of the nails.General data (age,gender,fracture side,etc.) showed no significant difference between two groups (allp > 0.05).The intraoperative parameters like operative time,radiation exposure and follow-up parameters like functional and radiological outcomes were recorded and compared.Statistical tests like the independent samplest-test Fischer’’s exact and Chi-square test were used to analyze association.Results:The distribution of the fractures according to AO/OTA classification and 31A1.2 type of intertrochanteric fractures were most common in our study.All the included fractures united and the average functional outcome in both groups were good and comparable at the end of one year.The operative time (mL,107.1 ± 12.6vs.77.0 ± 12.0,p < 0.001) and radiation exposure (s,78.6 ± 11.0vs.40.3 ± 9.3,p < 0.001) were significantly less among the patients in group B.Fracture consolidation,three months after the operative procedures,was seen in a significantly greater proportion of patients in group B (92.6%vs.67.7%,p = 0.025).Hardware irritation because of distal locking bolt was exclusively seen in group A,however this was not statistically significant (p = 0.241).Conclusion:We conclude that,in fixation of stable intertrochanteric fractures by long PFNA-II nail,distal locking not only increases the operative time and radiation exposure but also delays the fracture consolidation and increases the chances of hardware irritation,and hence is not required.
