Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a m...Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a meta-analysis of studies on sperm DNA damage （assessed by SCSA, TUNEL, SCD, or Comet assay） and clinical pregnancy after IVF and/or ICSI treatment from MEDLINE, EMBASE, and PUBMED database searches for this analysis. We identified 41 articles （with a total of 56 studies） including 16 IVF studies, 24 ICSI studies, and 16 mixed （IVF ＋ ICSI） studies. These studies measured DNA damage （by one of four assays： 23 SCSA, 18 TUNEL, 8 SCD, and 7 Comet） and included a total of 8068 treatment cycles （3734 IVF, 2282 ICSI, and 2052 mixed IVF ＋ ICSI）. The combined OR of 1.68 （95% Ch 1.49-1.89; P 〈 0.0001） indicates that sperm DNA damage affects clinical pregnancy following IVF and/or ICSI treatment. In addition, the combined OR estimates of IVF （16 estimates, OR = 1.65; 95% CI： 1.34-2.04; P 〈 0.0001）, ICSI （24 estimates, OR = 1.31; 95% Ch 1.08-1.59; P = 0.0068）, and mixed IVF ＋ ICSI studies （16 estimates, OR = 2.37; 95% Ch 1.89-2.97; P〈 0.0001） were also statistically significant. There is sufficient evidence in the existing literature suggesting that sperm DNA damage has a negative effect on clinical pregnancy following IVF and/or ICSI treatment.展开更多
Chinese outward direct investment （ODI） is expanding at an unprecedented rate. The present study augments the understanding of the determinants and drivers of Chinese ODI. It reviews the literature on Chinese 0191 a...Chinese outward direct investment （ODI） is expanding at an unprecedented rate. The present study augments the understanding of the determinants and drivers of Chinese ODI. It reviews the literature on Chinese 0191 and analyzes investment by state-owned enterprises （SOE） for the period 2003-2008, focusing specifically on the differences between the determinants of Chinese investment in developed （OECD） and developing （non-OECD） economies. In addition, the study assesses the appropriateness of the general framework used for investigating ODI determinants （Dunning＇s eclectic paradigm） to analyze the experience of Chinese SOE. The findings indicate that Dunning＇s eclectic paradigm provides an excellent theoretical framework for analyzing the determinants of Chinese SOE investment in developed countries, and provides a good starting point for analysis of Chinese investment in developing countries. However, Dunning＇s specification requires refinement for developing countries. This paper finds a distinct difference between the motivations for Chinese SOE investment in developed and developing countries.展开更多
Background： Although much attention has been paid to the pharmacokinetics （PKs） of different factor VIII （FVIlI） concentrates in persons with hemophilia A （HA）, limited information is available in young boys wi...Background： Although much attention has been paid to the pharmacokinetics （PKs） of different factor VIII （FVIlI） concentrates in persons with hemophilia A （HA）, limited information is available in young boys with severe HA. In this study, we aimed to assess the PK parameters of FVIII products in boys with severe HA in China. Methods： A total of 36 boys （plasma-derived [pd]-FVIII, n= 15; recombinant [r] FVIII, n = 21） were enrolled between January 2015 and May 2016 in Beijing Children＇s Hospital. PK characteristics of FVIII products were studied according to a reduced 4-sampling time point design （1 h, 9 h, 24 h, and 48 h postinfusion）. Results： The mean FVIII half-life （t1/2） was 10.99 ± 3.45 h （range 5.52-20.02 h）, the mean in vivo recovery （IVR） was 2.01 ± 0.42 IU/dl per IU/kg （range 1.24-3.02 IU/dl per IU/kg） and mean clearance （CL） of FVIII is 4.34 ± 1.58 ml·kg^-1·h ^-1 （range 2.29-7.90 ml·kg^-1·h·^-1）. We also analyzed the influence of several parameters that potentially modulate FVIII PK. The age was closely associated with FVIII half-life （R^2 = 0.32, P 〈 0.01 ）. The t1/2 of FVIII increased by 0.59 h per year. Besides age, yon Willebrand factor antigen （VWF：Ag） also was associated with FVIII half-life （R^2 = 0.52, P 〈 0.01）. Patients with blood Group O had a shorter FVIII halt-life than patients with non-O blood group （9.40 ± 0.68 h vs. 12.3 ± 0.79 h, t = 2.70, P = 0.01）. The FVIII IVR correlated with age （R^2 =0.21, P 〈 0.01） and VWF：Ag level （R^2 = 0.28, P 〈 0.01 ）. CL rates were taster in young patients and in those with low-VWF：Ag levels. CL rates of FVIII are higher in blood Group O versus non-blood Group O persons （5.02 ± 0.38 vs. 4.00 ± 0.32 ml·kg^-1·h^-1 , t = 2.53, P = 0.02）. Conclusions： Chinese boys with severe HA have similar PK values to other ethnic groups and large differences in FVIII PK between individual patients. Age, blood group, and VWF：Ag levels are important determining fac展开更多
Hepatic ischemia-reperfusion injury (IRI) limits access to transplantation. Heme oxygenase-1 (HO-1) is a powerful antioxidant enzyme which degrades free heme into biliverdin,free iron and carbon monoxide. HO-1 and its...Hepatic ischemia-reperfusion injury (IRI) limits access to transplantation. Heme oxygenase-1 (HO-1) is a powerful antioxidant enzyme which degrades free heme into biliverdin,free iron and carbon monoxide. HO-1 and its metabolites have the ability to modulate a wide variety of inflammatory disorders including hepatic IRI. Mechanisms of this protective effect include reduction of oxygen free radicals,alteration of macrophage and T cell phenotype. Further work is required to understand the physiological importance of the many actions of HO-1 identified experimentally,and to harness the protective effect of HO-1 for therapeutic potential.展开更多
With improvements in personnel and vehicular body armor,robust casualty evacuation capabilities,and damage control resuscitation strategies,more combat casualties are surviving to reach higher levels of care throughou...With improvements in personnel and vehicular body armor,robust casualty evacuation capabilities,and damage control resuscitation strategies,more combat casualties are surviving to reach higher levels of care throughout the casualty evacuation system.As such,medical centers are becoming more accustomed to managing the deleterious late consequences of combat trauma related to the dysregulation of the immune system.In this review,we aim to highlight these late consequences and identify areas for future research and therapeutic strategies.Trauma leads to the dysregulation of both the innate and adaptive immune responses,which places the injured at risk for several late consequences,including delayed wound healing,late onset sepsis and infection,multi-organ dysfunction syndrome,and acute respiratory distress syndrome,which are significant for their association with the increased morbidity and mortality of wounded personnel.The mechanisms by which these consequences develop are complex but include an imbalance of the immune system leading to robust inflammatory responses,triggered by the presence of damage associated molecules and other immune-modifying agents following trauma.Treatment strategies to improve outcomes have been difficult to develop as the immunophenotype of injured personnel following trauma is variable,fluid and difficult to determine.As more information regarding the triggers that lead to immune dysfunction following trauma is elucidated,it may be possible to identify the immunophenotype of injured personnel and provide targeted treatments to reduce the late consequences of trauma,which are known to lead to significant morbidity and mortality.展开更多
A new coronavirus(SARS-CoV-2)has been identified as the etiologic agent for the COVID-19 outbreak.Currently,effective treatment options remain very limited for this disease;therefore,there is an urgent need to identif...A new coronavirus(SARS-CoV-2)has been identified as the etiologic agent for the COVID-19 outbreak.Currently,effective treatment options remain very limited for this disease;therefore,there is an urgent need to identify new anti-COVID-19 agents.In this study,we screened over 6,000 compounds that included approved drugs,drug candidates in clinical trials,and pharmacologically active compounds to identify leads that target the SARS-CoV-2 papain-like protease(PLpro).Together with main protease(Mpro),PLpro is responsible for processing the viral replicase polyprotein into functional units.There-fore,it is an attractive target for antiviral drug develop-ment.Here we discovered four compounds,YM155,cryptotanshinone,tanshinone I and GRL0617 that inhibit SARS-CoV-2 PLpro with IC50 values ranging from 1.39 to 5.63 pmol/L.These compounds also exhibit strong antiviral activities in cell-based assays.YM155,an anti-cancer drug candidate in clinical trials,has the most potent antiviral activity with an EC50 value of 170 nmol/L.In addition,we have determined the crystal structures of this enzyme and its complex with YM155,revealing a unique binding mode.YM155 simultaneously targets three"hot"spots on PLpro,including the substrate-binding pocket,the interferon stimulating gene product 15(ISG15)binding site and zinc finger motif.Our results demonstrate the efficacy of this screening and repur-posing strategy,which has led to the discovery of new drug leads with clinical potential for COVID-19 treatments.展开更多
This paper is concerned with power reduction control which is used to avoid DC over-voltage for multiterminal HVDC transmission of offshore wind power.Voltages and frequencies of offshore AC wind farm networks are use...This paper is concerned with power reduction control which is used to avoid DC over-voltage for multiterminal HVDC transmission of offshore wind power.Voltages and frequencies of offshore AC wind farm networks are used for transmitting control signals for the power reduction control.These methods do not require fast communication.Power reduction sharing among the offshore wind farms using the different control signals is analysed.The control systems are also compared against the DC chopper method to prevent a DC overvoltage.Simulation and experiments are carried out to evaluate the control systems.展开更多
AIM:To assess the relationship between preoperative computed tomography(CT)and postoperative pathological measurements of esophageal tumor length and the prognostic significance of CT tumor length data.METHODS:A retro...AIM:To assess the relationship between preoperative computed tomography(CT)and postoperative pathological measurements of esophageal tumor length and the prognostic significance of CT tumor length data.METHODS:A retrospective study was carried out in 56 patients who underwent curative esophagogastrectomy.Tumor lengths were measured on the immediate preoperative CT and on the post-operative resection specimens.Inter-and intra-observer variations in CT measurements were assessed.Survival data were collected.RESULTS:There was a weak correlation between CT and pathological tumor length(r=0.30,P=0.025).CT lengths were longer than pathological lengths in 68%(38/56)of patients with a mean difference of 1.67 cm(95%CI:1.18-2.97).The mean difference in measurements by two radiologists was 0.39 cm(95% CI:-0.59-1.44).The mean difference between repeat CT measured tumor length(intra-observer variation) were 0.04 cm(95%CI:-0.59-0.66)and 0.47 cm (95%CI:-0.53-1.47).When stratified,patients not receiving neoadjuvant chemotherapy showed a strong correlation between CT and pathological tumor length(r =0.69,P=0.0014,n=37)than patients that did(r= 0.13,P=0.43,n=19).Median survival with CT tumor length>5.6 cm was poorer than with smaller tumors,but the difference was not statistically significant.CONCLUSION:Esophageal tumor length assessed using CT does not reflect pathological tumor extent and should not be the only modality used for management decisions,particularly for planning radiotherapy.展开更多
Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg ...Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg of carbon dioxide （CO2） emission per kilogram of ethylene produced, We propose an alternative pro- cess for the redox oxy-cracking （ROC） of naphtha, In this two-step process, hydrogen （H2） from naphtha cracking is selectively comhusted by a redox catalyst with its lattice oxygen first, The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions, This intensified process reduces parasitic energy consumption and CO2 and NOx emissions, Moreover, the formation of ethylene and propylene can he enhanced due to the selective com-bustion of H2, In this study, the ROC process is simulated with ASPEN Plus^R based on experimental data from recently developed redox catalysts, Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO2 emissions, The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock,展开更多
Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and ...Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.展开更多
Social vulnerability influences the ability to prepare for, respond to, and recover from disasters. The identification of vulnerable populations and factors that contribute to their vulnerability are crucial for effec...Social vulnerability influences the ability to prepare for, respond to, and recover from disasters. The identification of vulnerable populations and factors that contribute to their vulnerability are crucial for effective disaster risk reduction. Nepal exhibits multihazard risk and has experienced socioeconomic and political upheaval in recent decades, further increasing susceptibility to hazards.However, we still know little regarding social vulnerability in Nepal. Here, we investigate social vulnerability in Nepal by adapting Social Vulnerability Index(SoVI) methods to the Nepali context. Variables such as caste, and populations who cannot speak/understand Nepali were added to reflect the essence of the Nepali context. Using principal component analysis, 39 variables were reduced to seven factors that explained 63.02% of variance in the data.Factor scores were summarized to calculate final SoVI scores. The highest levels of social vulnerability are concentrated in the central and western Mountain, western Hill, and central and eastern Tarai regions of Nepal, while the least vulnerable areas are in the central and eastern Hill regions. These findings, supplemented with smaller-scale analyses, have the potential to assist village officers, policymakers,and emergency managers in the development of more effective and geographically targeted disaster management programs.展开更多
International financial adjustment is the process whereby valuation shifts from asset price and currency changes result in relatively durable net wealth transfers across countries＇ international balance sheets. Thisp...International financial adjustment is the process whereby valuation shifts from asset price and currency changes result in relatively durable net wealth transfers across countries＇ international balance sheets. Thispaper applies a financial valuation approach to estimate the direction and the broad extent of recent international financial adjustments on China international balance sheet. We estimate China＇s international balance sheet losses resulting from the valuation shifts over the period 2005 2010 and reveal that international currency shifts over the past decade have also generated a range of non-balance sheet financial and monetary adjustment pressures for China. This paper also evaluates how China＇s evolving international financial policy arrangements could better mitigate China＇s exposure to international financial adjustments. These arrangements include a more effective currency mechanism and the mechanisms to internationalize the RMB to buffer international financial valuation shocks展开更多
文摘Sperm DNA damage is prevalent among infertile men and is known to influence natural reproduction. However, the impact of sperm DNA damage on assisted reproduction outcomes remains controversial. Here, we conducted a meta-analysis of studies on sperm DNA damage （assessed by SCSA, TUNEL, SCD, or Comet assay） and clinical pregnancy after IVF and/or ICSI treatment from MEDLINE, EMBASE, and PUBMED database searches for this analysis. We identified 41 articles （with a total of 56 studies） including 16 IVF studies, 24 ICSI studies, and 16 mixed （IVF ＋ ICSI） studies. These studies measured DNA damage （by one of four assays： 23 SCSA, 18 TUNEL, 8 SCD, and 7 Comet） and included a total of 8068 treatment cycles （3734 IVF, 2282 ICSI, and 2052 mixed IVF ＋ ICSI）. The combined OR of 1.68 （95% Ch 1.49-1.89; P 〈 0.0001） indicates that sperm DNA damage affects clinical pregnancy following IVF and/or ICSI treatment. In addition, the combined OR estimates of IVF （16 estimates, OR = 1.65; 95% CI： 1.34-2.04; P 〈 0.0001）, ICSI （24 estimates, OR = 1.31; 95% Ch 1.08-1.59; P = 0.0068）, and mixed IVF ＋ ICSI studies （16 estimates, OR = 2.37; 95% Ch 1.89-2.97; P〈 0.0001） were also statistically significant. There is sufficient evidence in the existing literature suggesting that sperm DNA damage has a negative effect on clinical pregnancy following IVF and/or ICSI treatment.
文摘Chinese outward direct investment （ODI） is expanding at an unprecedented rate. The present study augments the understanding of the determinants and drivers of Chinese ODI. It reviews the literature on Chinese 0191 and analyzes investment by state-owned enterprises （SOE） for the period 2003-2008, focusing specifically on the differences between the determinants of Chinese investment in developed （OECD） and developing （non-OECD） economies. In addition, the study assesses the appropriateness of the general framework used for investigating ODI determinants （Dunning＇s eclectic paradigm） to analyze the experience of Chinese SOE. The findings indicate that Dunning＇s eclectic paradigm provides an excellent theoretical framework for analyzing the determinants of Chinese SOE investment in developed countries, and provides a good starting point for analysis of Chinese investment in developing countries. However, Dunning＇s specification requires refinement for developing countries. This paper finds a distinct difference between the motivations for Chinese SOE investment in developed and developing countries.
文摘Background： Although much attention has been paid to the pharmacokinetics （PKs） of different factor VIII （FVIlI） concentrates in persons with hemophilia A （HA）, limited information is available in young boys with severe HA. In this study, we aimed to assess the PK parameters of FVIII products in boys with severe HA in China. Methods： A total of 36 boys （plasma-derived [pd]-FVIII, n= 15; recombinant [r] FVIII, n = 21） were enrolled between January 2015 and May 2016 in Beijing Children＇s Hospital. PK characteristics of FVIII products were studied according to a reduced 4-sampling time point design （1 h, 9 h, 24 h, and 48 h postinfusion）. Results： The mean FVIII half-life （t1/2） was 10.99 ± 3.45 h （range 5.52-20.02 h）, the mean in vivo recovery （IVR） was 2.01 ± 0.42 IU/dl per IU/kg （range 1.24-3.02 IU/dl per IU/kg） and mean clearance （CL） of FVIII is 4.34 ± 1.58 ml·kg^-1·h ^-1 （range 2.29-7.90 ml·kg^-1·h·^-1）. We also analyzed the influence of several parameters that potentially modulate FVIII PK. The age was closely associated with FVIII half-life （R^2 = 0.32, P 〈 0.01 ）. The t1/2 of FVIII increased by 0.59 h per year. Besides age, yon Willebrand factor antigen （VWF：Ag） also was associated with FVIII half-life （R^2 = 0.52, P 〈 0.01）. Patients with blood Group O had a shorter FVIII halt-life than patients with non-O blood group （9.40 ± 0.68 h vs. 12.3 ± 0.79 h, t = 2.70, P = 0.01）. The FVIII IVR correlated with age （R^2 =0.21, P 〈 0.01） and VWF：Ag level （R^2 = 0.28, P 〈 0.01 ）. CL rates were taster in young patients and in those with low-VWF：Ag levels. CL rates of FVIII are higher in blood Group O versus non-blood Group O persons （5.02 ± 0.38 vs. 4.00 ± 0.32 ml·kg^-1·h^-1 , t = 2.53, P = 0.02）. Conclusions： Chinese boys with severe HA have similar PK values to other ethnic groups and large differences in FVIII PK between individual patients. Age, blood group, and VWF：Ag levels are important determining fac
基金Supported by The Maurice Wohl Fellowship from the Royal College of Surgeons of Edinburgh and a Research Training Fel-lowship from The Wellcome Trust (to Richards JA)Tenovus Scotland and The Peel Medical Research Trust to support his cur-rent work (to Richards JA)A Clinician Scientist Fellowship from the Academy of Medical Sciences and the Health Foundation (to Devey LR)
文摘Hepatic ischemia-reperfusion injury (IRI) limits access to transplantation. Heme oxygenase-1 (HO-1) is a powerful antioxidant enzyme which degrades free heme into biliverdin,free iron and carbon monoxide. HO-1 and its metabolites have the ability to modulate a wide variety of inflammatory disorders including hepatic IRI. Mechanisms of this protective effect include reduction of oxygen free radicals,alteration of macrophage and T cell phenotype. Further work is required to understand the physiological importance of the many actions of HO-1 identified experimentally,and to harness the protective effect of HO-1 for therapeutic potential.
基金RJS was supported by National Institutes of Health grants,K08-GM117367.
文摘With improvements in personnel and vehicular body armor,robust casualty evacuation capabilities,and damage control resuscitation strategies,more combat casualties are surviving to reach higher levels of care throughout the casualty evacuation system.As such,medical centers are becoming more accustomed to managing the deleterious late consequences of combat trauma related to the dysregulation of the immune system.In this review,we aim to highlight these late consequences and identify areas for future research and therapeutic strategies.Trauma leads to the dysregulation of both the innate and adaptive immune responses,which places the injured at risk for several late consequences,including delayed wound healing,late onset sepsis and infection,multi-organ dysfunction syndrome,and acute respiratory distress syndrome,which are significant for their association with the increased morbidity and mortality of wounded personnel.The mechanisms by which these consequences develop are complex but include an imbalance of the immune system leading to robust inflammatory responses,triggered by the presence of damage associated molecules and other immune-modifying agents following trauma.Treatment strategies to improve outcomes have been difficult to develop as the immunophenotype of injured personnel following trauma is variable,fluid and difficult to determine.As more information regarding the triggers that lead to immune dysfunction following trauma is elucidated,it may be possible to identify the immunophenotype of injured personnel and provide targeted treatments to reduce the late consequences of trauma,which are known to lead to significant morbidity and mortality.
基金National Key R&D Program of China grants 2017YFC0840300(Z.R.)and 2020YFA0707500(H.Y.)Project of International Cooperation and Exchanges NSFC(Grant No.81520108019 to Z.R.)+3 种基金Science and Technology Commission of Shanghai Municipality(Grant No.20431900200 to H.Y.)Department of Science and Technology of Guangxi Zhuang Autonomous Region(Grant No.2020AB40007 to X.Y.)Hubei Science and Technology Project(Grant No.2020FCA003 to L.Z.)Youth Program of NSFC(Grant No.81900729 to L.S.).
文摘A new coronavirus(SARS-CoV-2)has been identified as the etiologic agent for the COVID-19 outbreak.Currently,effective treatment options remain very limited for this disease;therefore,there is an urgent need to identify new anti-COVID-19 agents.In this study,we screened over 6,000 compounds that included approved drugs,drug candidates in clinical trials,and pharmacologically active compounds to identify leads that target the SARS-CoV-2 papain-like protease(PLpro).Together with main protease(Mpro),PLpro is responsible for processing the viral replicase polyprotein into functional units.There-fore,it is an attractive target for antiviral drug develop-ment.Here we discovered four compounds,YM155,cryptotanshinone,tanshinone I and GRL0617 that inhibit SARS-CoV-2 PLpro with IC50 values ranging from 1.39 to 5.63 pmol/L.These compounds also exhibit strong antiviral activities in cell-based assays.YM155,an anti-cancer drug candidate in clinical trials,has the most potent antiviral activity with an EC50 value of 170 nmol/L.In addition,we have determined the crystal structures of this enzyme and its complex with YM155,revealing a unique binding mode.YM155 simultaneously targets three"hot"spots on PLpro,including the substrate-binding pocket,the interferon stimulating gene product 15(ISG15)binding site and zinc finger motif.Our results demonstrate the efficacy of this screening and repur-posing strategy,which has led to the discovery of new drug leads with clinical potential for COVID-19 treatments.
基金supported by the Research Councils UK,through the HubNet consortium,www.hubnet.org.uk(grant number:EP/I01363611)the Top and Tail Transformation programme,(grant number:EP/I031707/1)+1 种基金supported by the People Programme(Marie Curie Actions)of the European Union's Seventh Framework Programme FP7/2007-20131(grant number:317221,project title MEDOW)supported by the Joint Research Fund for Overseas Chinese,Hong Kong,and Macao Scientists of the National Natural Science Foundation of China(grant number:51128701).
文摘This paper is concerned with power reduction control which is used to avoid DC over-voltage for multiterminal HVDC transmission of offshore wind power.Voltages and frequencies of offshore AC wind farm networks are used for transmitting control signals for the power reduction control.These methods do not require fast communication.Power reduction sharing among the offshore wind farms using the different control signals is analysed.The control systems are also compared against the DC chopper method to prevent a DC overvoltage.Simulation and experiments are carried out to evaluate the control systems.
基金Supported by The local departmental research fund
文摘AIM:To assess the relationship between preoperative computed tomography(CT)and postoperative pathological measurements of esophageal tumor length and the prognostic significance of CT tumor length data.METHODS:A retrospective study was carried out in 56 patients who underwent curative esophagogastrectomy.Tumor lengths were measured on the immediate preoperative CT and on the post-operative resection specimens.Inter-and intra-observer variations in CT measurements were assessed.Survival data were collected.RESULTS:There was a weak correlation between CT and pathological tumor length(r=0.30,P=0.025).CT lengths were longer than pathological lengths in 68%(38/56)of patients with a mean difference of 1.67 cm(95%CI:1.18-2.97).The mean difference in measurements by two radiologists was 0.39 cm(95% CI:-0.59-1.44).The mean difference between repeat CT measured tumor length(intra-observer variation) were 0.04 cm(95%CI:-0.59-0.66)and 0.47 cm (95%CI:-0.53-1.47).When stratified,patients not receiving neoadjuvant chemotherapy showed a strong correlation between CT and pathological tumor length(r =0.69,P=0.0014,n=37)than patients that did(r= 0.13,P=0.43,n=19).Median survival with CT tumor length>5.6 cm was poorer than with smaller tumors,but the difference was not statistically significant.CONCLUSION:Esophageal tumor length assessed using CT does not reflect pathological tumor extent and should not be the only modality used for management decisions,particularly for planning radiotherapy.
基金This work was supported by the US National Science Foundation （CBET-1604605） and the Kenan Institute for Engineering, Technol-ogy and Science at North Carolina State University.
文摘Ethylene production by the thermal cracking of naphtha is an energy-intensive process （up to 40 GJ heat per tonne ethylene）, leading to significant formation of coke and nitrogen oxide （NOx）, along with 1,8- 2 kg of carbon dioxide （CO2） emission per kilogram of ethylene produced, We propose an alternative pro- cess for the redox oxy-cracking （ROC） of naphtha, In this two-step process, hydrogen （H2） from naphtha cracking is selectively comhusted by a redox catalyst with its lattice oxygen first, The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions, This intensified process reduces parasitic energy consumption and CO2 and NOx emissions, Moreover, the formation of ethylene and propylene can he enhanced due to the selective com-bustion of H2, In this study, the ROC process is simulated with ASPEN Plus^R based on experimental data from recently developed redox catalysts, Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO2 emissions, The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock,
基金financial support for much of the early development of the AE analysis methods was provided by the U.S. Department of Energy (DOE) (Grant No. DE-FE0002760)
文摘Understanding microcracking near coalesced fracture generation is critically important for hydrocarbon and geothermal reservoir characterization as well as damage evaluation in civil engineering structures. Dense and sometimes random microcracking near coalesced fracture formation alters the mechanical properties of the nearby virgin material. Individual microcrack characterization is also significant in quantifying the material changes near the fracture faces （i.e. damage）. Acoustic emission （AE） monitoring and analysis provide unique information regarding the microcracking process temporally, and infor- mation concerning the source characterization of individual microcracks can be extracted. In this context, laboratory hydraulic fracture tests were carried out while monitoring the AEs from several piezoelectric transducers. In-depth post-processing of the AE event data was performed for the purpose of under- standing the individual source mechanisms. Several source characterization techniques including moment tensor inversion, event parametric analysis, and volumetric deformation analysis were adopted. Post-test fracture characterization through coring, slicing and micro-computed tomographic imaging was performed to determine the coalesced fracture location and structure. Distinct differences in fracture characteristics were found spatially in relation to the openhole injection interval. Individual microcrack AE analysis showed substantial energy reduction emanating spatially from the injection interval. It was quantitatively observed that the recorded AE signals provided sufficient information to generalize the damage radiating spatially away from the injection wellbore.
文摘Social vulnerability influences the ability to prepare for, respond to, and recover from disasters. The identification of vulnerable populations and factors that contribute to their vulnerability are crucial for effective disaster risk reduction. Nepal exhibits multihazard risk and has experienced socioeconomic and political upheaval in recent decades, further increasing susceptibility to hazards.However, we still know little regarding social vulnerability in Nepal. Here, we investigate social vulnerability in Nepal by adapting Social Vulnerability Index(SoVI) methods to the Nepali context. Variables such as caste, and populations who cannot speak/understand Nepali were added to reflect the essence of the Nepali context. Using principal component analysis, 39 variables were reduced to seven factors that explained 63.02% of variance in the data.Factor scores were summarized to calculate final SoVI scores. The highest levels of social vulnerability are concentrated in the central and western Mountain, western Hill, and central and eastern Tarai regions of Nepal, while the least vulnerable areas are in the central and eastern Hill regions. These findings, supplemented with smaller-scale analyses, have the potential to assist village officers, policymakers,and emergency managers in the development of more effective and geographically targeted disaster management programs.
文摘International financial adjustment is the process whereby valuation shifts from asset price and currency changes result in relatively durable net wealth transfers across countries＇ international balance sheets. Thispaper applies a financial valuation approach to estimate the direction and the broad extent of recent international financial adjustments on China international balance sheet. We estimate China＇s international balance sheet losses resulting from the valuation shifts over the period 2005 2010 and reveal that international currency shifts over the past decade have also generated a range of non-balance sheet financial and monetary adjustment pressures for China. This paper also evaluates how China＇s evolving international financial policy arrangements could better mitigate China＇s exposure to international financial adjustments. These arrangements include a more effective currency mechanism and the mechanisms to internationalize the RMB to buffer international financial valuation shocks
