Road transport safety has always been paid attention to by the safety production managers of enterprises. In this study, cloud model and analytic hierarchy process were applied to the safety of long-tube trailer trans...Road transport safety has always been paid attention to by the safety production managers of enterprises. In this study, cloud model and analytic hierarchy process were applied to the safety of long-tube trailer transport. The opinions of 30 experts were analyzed, from which 29 key parameters were selected. The study addressed the relevance of the parameters and the possibility of automatic collection and transmission to obtain 12 core risk factors. The macro-safety risk indicator system for long-tube trailers was established based on the identified risk indicators. Finally, a risk assessment model for road transport of long tube trailers consisting of 3 dimensions of likelihood, severity and sensitivity was constructed. This model provides a technical method for strengthening the risk control of road transport of long-tube trailers.展开更多
A comprehensive study on Sn macrosegregation behavior in ternary Al-Sn-Cu alloys was carried out by comparative analysis between gravity casting and squeeze casting samples.The microstructure and Sn distribution of th...A comprehensive study on Sn macrosegregation behavior in ternary Al-Sn-Cu alloys was carried out by comparative analysis between gravity casting and squeeze casting samples.The microstructure and Sn distribution of the castings were characterized by metallography,scanning electron microscopy(SEM),energy-dispersive X-ray(EDX)spectroscopy,and a direct reading spectrometer.Results show that there are obvious differences in Sn morphology between gravity casting and squeeze casting alloys.Under squeeze casting condition,the grain size of the casting is smaller and the distribution ofβ(Sn)is uniform.This effectively reduces the segregation of triangular grain boundary as well as the segregation of Sn.The segregation types of Sn in gravity casting and squeeze casting samples are obviously different.The upper surfaces of gravity casting samples show severe negative segregation,while all the lower surfaces have positive segregation.Compared with gravity casting,squeeze casting solidifies under isostatic pressure.Due to the direct contact between the upper surface of the casting and the mold,the casting solidifies faster under higher undercooling degree and pressure.Consequently,the uniform distribution of Sn reduces the segregation phenomenon on the surface of the casting.展开更多
With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of...With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of data generated from the devices challenges the AIoT systems from information collection,storage,processing and communication.In the review,we introduce volatile threshold switching memristors,which can be roughly classified into three types:metallic conductive filament-based TS devices,amorphous chalcogenide-based ovonic threshold switching devices,and metal-insulator transition based TS devices.They play important roles in high-density storage,energy efficient computing and hardware security for AIoT systems.Firstly,a brief introduction is exhibited to describe the categories(materials and characteristics)of volatile TS devices.And then,switching mechanisms of the three types of TS devices are discussed and systematically summarized.After that,attention is focused on the applications in 3D cross-point memory technology with high storage-density,efficient neuromorphic computing,hardware security(true random number generators and physical unclonable functions),and others(steep subthreshold slope transistor,logic devices,etc.).Finally,the major challenges and future outlook of volatile threshold switching memristors are presented.展开更多
Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reaction...Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reactions.Herein,the ultrasmall Ru nanoclusters(~0.9 nm)were successfully fabricated over P25 support with positive charged Ru^(δ+)species at the interface.A new route was developed to achieve the furfural(FAL)to furfurylamine(FAM)by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst.Strikingly,the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium.The Ru^(δ+)species at the interface promote the formation of active imine intermediates;moreover,the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines.In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products.In addition,the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster.This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.展开更多
As the need for high-energy–density batteries continues to grow, lithium-sulfur(Li–S) batteries have become a highly promising next-generation energy solution due to their low cost and exceptional energy density com...As the need for high-energy–density batteries continues to grow, lithium-sulfur(Li–S) batteries have become a highly promising next-generation energy solution due to their low cost and exceptional energy density compared to commercially available Li-ion batteries. Research into carbon-based sulfur hosts for Li–S batteries has been ongoing for over two decades, leading to a significant number of publications and patents.However, the commercialization of Li–S batteries has yet to be realized. This can be attributed, in part, to the instability of the Li metal anode. However, even when considering just the cathode side, there is still no consensus on whether carbon-based hosts will prove to be the best sulfur hosts for the industrialization of Li–S batteries. Recently, there has been controversy surrounding the use of carbon-based materials as the ideal sulfur hosts for practical applications of Li–S batteries under high sulfur loading and lean electrolyte conditions. To address this question, it is important to review the results of research into carbon-based hosts, assess their strengths and weaknesses, and provide a clear perspective. This review systematically evaluates the merits and mechanisms of various strategies for developing carbon-based host materials for high sulfur loading and lean electrolyte conditions. The review covers structural design and functional optimization strategies in detail, providing a comprehensive understanding of the development of sulfur hosts. The review also describes the use of efficient machine learning methods for investigating Li–S batteries. Finally, the outlook section lists and discusses current trends, challenges, and uncertainties surrounding carbon-based hosts, and concludes by presenting our standpoint and perspective on the subject.展开更多
Colorless‐to‐black switching has attracted widespread attention for smart windows and multifunctional displays because they are more useful to control solar energy.However,it still remains a challenge owing to the t...Colorless‐to‐black switching has attracted widespread attention for smart windows and multifunctional displays because they are more useful to control solar energy.However,it still remains a challenge owing to the tremendous difficulties in the design of completely reverse absorptions in transmissive and colored states.Herein,we report on an electrochemical device that can switch between colorless and black by using the electrochemical process of hybrid organic–inorganic perovskite MAPbBr_(3),which shows a high integrated contrast ratio of up to 73%from 400 to 800 nm.The perovskite solution can be used as the active layer to assemble the device,showing superior transmittance over the entire visible region in neutral states.By applying an appropriate voltage,the device undergoes reversible switching between colorless and black,which is attributed to the formation of lead and Br_(2)in the redox reaction induced by the electron transfer process in MAPbBr_(3).In addition,the contrast ratio can be modulated over the entire visible region by changing the concentration and the applied voltage.These results contribute toward gaining an insightful understanding of the electrochemical process of perovskites and greatly promoting the development of switchable devices.展开更多
The macrosegregation behaviors of Al-Sn-Cu ternary immiscible alloy castings and their effects on mechanical and tribological properties were investigated.The results demonstrate that Sn and Cu segregate in the castin...The macrosegregation behaviors of Al-Sn-Cu ternary immiscible alloy castings and their effects on mechanical and tribological properties were investigated.The results demonstrate that Sn and Cu segregate in the casting simultaneously,and the mass fraction of the two elements has a"U"shaped distribution.Significantly,positive and negative segregation occur in the casting,with positive segregation appearing on the top and lower surfaces and negative segregation on the remaining surfaces,with the 1/2 surface(hot node location)having the highest degree of negative segregation.Furthermore,the results of Vickers hardness,tensile strength,and elongation show that Sn and Cu cooperatively affect the mechanical properties of castings.The higher the mass fraction of Sn and Cu elements,the higher the hardness,the greater the tensile strength,and the better the elongation.The findings of the step-by-step loading tests demonstrate that the segregation of Sn and Cu significantly impacts the tribological characteristics of the castings.The higher the mass fraction of Sn and Cu on the sample surface,the better the tribological characteristics.展开更多
The lithium-sulfur(Li-S)battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the slug...The lithium-sulfur(Li-S)battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium polysulfides(LiPSs)intermediates that result in low sulfur utilization.The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utilization in Li-S batteries by achieving effective regulation of LiPSs.Herein,a promising self-assembly strategy is proposed to achieve the low-cost fabrication of hollow and hierarchically porous Fe_(3)O_(4)nanospheres(p-Fe_(3)O_(4)-NSs)assembled by numerous extremely-small primary nanocrystals as building blocks.The rationally-designed p-Fe_(3)O_(4)-NSs are utilized as a multifunctional layer on the separator with highly efficient trapping and conversion features toward LiPSs.Results demonstrate that the nanostructured p-Fe_(3)O_(4)-NSs provide chemical adsorption toward LiPSs and kinetically promote the mutual transformation between LiPSs and Li_(2)S_(2)/Li_(2)S during cycling,thus inhibiting the LiPSs shuttling and boosting the redox reaction kinetics via a chemisorption-catalytic conversion mechanism.The enhanced wettability of the p-Fe_(3)O_(4)-NSs-based separator with the electrolyte enables fast transportation of lithium ions.Benefitting from these alluring properties,the functionalized separator with p-Fe_(3)O_(4)-NSs endows the battery with an admirable rate performance of 877 mAh g^(−1)at 2 C,an ultra-durable cycling performance of up to 2176 cycles at 1 C,and a promising areal capacity of 4.55 mAh cm^(−2)under high-sulfur-loading and lean-electrolyte conditions(4.29 mg cm^(−2),electrolyte/ratio:8μl mg^(−1)).This study will offer fresh insights on the rational design and low-cost fabrication of multifunctional separator to strengthen electrochemical reaction kinetics by regulating LiPSs conversion for developing efficient and long-life Li-S batteries.展开更多
BACKGROUND Carcinosarcomas of the common bile duct(CBD)are an extremely rare finding in the clinical setting.Based on a review of 12 literatures,3 cases had the imaging features of ossification.Carcinosarcomas are pro...BACKGROUND Carcinosarcomas of the common bile duct(CBD)are an extremely rare finding in the clinical setting.Based on a review of 12 literatures,3 cases had the imaging features of ossification.Carcinosarcomas are prone to distant metastasis,as they possess clinical features of both carcinoma and sarcoma,and generally have with a poor prognosis.Due to the small number of cases reported,clinical experience in the diagnosis and treatment of the disease is lacking.CASE SUMMARY The patient was a 75-year-old woman who had experienced recurrent chills with nausea and vomiting for 3 mo.Computed tomography,magnetic resonance imaging,endoscopic ultrasonography and endoscopic retrograde cholangiopancreatography led to the diagnosis of malignant tumor of the CBD.The patient ultimately underwent cholecystectomy,CBD resection,and choledochojejunostomy.Postoperative pathological examination revealed carcinosarcoma of the CBD,and the latest follow-up showed that the patient is recovering well.Based on previous case reports,some carcinosarcoma has ossification characteristics in imaging.If it is misdiagnosed as biliary calculi,the use of laser lithotripsy in surgery may lead to tumor diffusion.Choledochoscopy and narrow band staining of mucosa are very important for diagnosis.CONCLUSION We herein present a rare case of carcinosarcomas of the CBD,we found the tumours may have imaging features of polypoid growth and ossification only when the sarcomal components are bone differentiation,while show soft tissue shadow when non bone differentiation.Confirmation of diagnosis depends greatly upon postoperative pathological examination and the adjuvant treatment has not been established,which leads to the poor prognosis.展开更多
Nonalcoholic fatty liver disease(NAFLD)is the most common chronic liver dis-ease worldwide.NAFLD comprises a continuum of liver abnormalities from non-alcoholic fatty liver to nonalcoholic steatohepatitis,and can even...Nonalcoholic fatty liver disease(NAFLD)is the most common chronic liver dis-ease worldwide.NAFLD comprises a continuum of liver abnormalities from non-alcoholic fatty liver to nonalcoholic steatohepatitis,and can even lead to cirrhosis and liver cancer.However,a well-established treatment for NAFLD has yet to be identified.Exosomes have become an ideal drug delivery tool because of their high transmissibility,low immunogenicity,easy accessibility and targeting.Exosomes with specific modifications,known as engineered exosomes,have the potential to treat a variety of diseases.Here,we review the treatment of NAFLD with engineered exosomes and the potential use of exosomes as biomarkers and therapeutic targets for NAFLD.展开更多
传统虚拟直流电机VDCM(Virtual DC Machine)控制策略未考虑直流电机转速动态调节问题,不能够在直流母线电压变化瞬间起调节作用。对此,提出一种模拟直流电机闭环调速的储能侧双向DC/DC变换器新型VDCM控制策略。对直流电机与双向DC/DC变...传统虚拟直流电机VDCM(Virtual DC Machine)控制策略未考虑直流电机转速动态调节问题,不能够在直流母线电压变化瞬间起调节作用。对此,提出一种模拟直流电机闭环调速的储能侧双向DC/DC变换器新型VDCM控制策略。对直流电机与双向DC/DC变换器在数学模型和控制策略上进行联系等效与差异剖析,模拟直流电机定转子绕组间的电磁感应作用,将直流电机动态数学模型嵌入P-U下垂控制中,使其兼备电压动态调节能力和惯性阻尼特性。对采用新型VDCM控制策略前、后的作用效果进行对比,仿真和实验结果表明该控制策略能够在提升母线电压动态调节特性的同时,增强惯性调节和阻尼效果,在负载切换或分布式发电单元输出功率波动时维持直流微电网稳定运行。展开更多
目的比较拉米呋定与乙肝疫苗方案预防乙型肝炎核心抗体(hepatitis B core antibody,HBcAb)阳性供肝儿童肝移植术后新发乙型肝炎病毒(hepatitis B virus,HBV)感染效果。方法对天津市第一中心医院自2013年5月—2019年6月251例接受HBcAb阳...目的比较拉米呋定与乙肝疫苗方案预防乙型肝炎核心抗体(hepatitis B core antibody,HBcAb)阳性供肝儿童肝移植术后新发乙型肝炎病毒(hepatitis B virus,HBV)感染效果。方法对天津市第一中心医院自2013年5月—2019年6月251例接受HBcAb阳性供肝儿童肝移植的资料进行回顾性分析,依据采用预防方案的不同分为拉米呋定组和乙肝疫苗组,对两组患儿的新发乙肝病毒感染情况以及临床资料进行比较分析。结果拉米呋定组45例和乙肝疫苗组206例,两组在供受者的临床特征方面无显著差异,两组的新发乙肝病毒感染例数分别为5例(11.1%)和10例(4.9%),发生率无显著统计意义(P=0.075),停用拉米呋定与新发乙肝存在关系。结论单用拉米呋定和乙肝疫苗均是有效预防HBcAb阳性供肝术后新发乙肝的方案,停用拉米呋定会增加新发乙肝的风险。展开更多
文摘Road transport safety has always been paid attention to by the safety production managers of enterprises. In this study, cloud model and analytic hierarchy process were applied to the safety of long-tube trailer transport. The opinions of 30 experts were analyzed, from which 29 key parameters were selected. The study addressed the relevance of the parameters and the possibility of automatic collection and transmission to obtain 12 core risk factors. The macro-safety risk indicator system for long-tube trailers was established based on the identified risk indicators. Finally, a risk assessment model for road transport of long tube trailers consisting of 3 dimensions of likelihood, severity and sensitivity was constructed. This model provides a technical method for strengthening the risk control of road transport of long-tube trailers.
基金financially supported by the National Natural Science Foundation of China(No.51575151)the Science and Technology Project of Anhui Province,China(No.1501021006)。
文摘A comprehensive study on Sn macrosegregation behavior in ternary Al-Sn-Cu alloys was carried out by comparative analysis between gravity casting and squeeze casting samples.The microstructure and Sn distribution of the castings were characterized by metallography,scanning electron microscopy(SEM),energy-dispersive X-ray(EDX)spectroscopy,and a direct reading spectrometer.Results show that there are obvious differences in Sn morphology between gravity casting and squeeze casting alloys.Under squeeze casting condition,the grain size of the casting is smaller and the distribution ofβ(Sn)is uniform.This effectively reduces the segregation of triangular grain boundary as well as the segregation of Sn.The segregation types of Sn in gravity casting and squeeze casting samples are obviously different.The upper surfaces of gravity casting samples show severe negative segregation,while all the lower surfaces have positive segregation.Compared with gravity casting,squeeze casting solidifies under isostatic pressure.Due to the direct contact between the upper surface of the casting and the mold,the casting solidifies faster under higher undercooling degree and pressure.Consequently,the uniform distribution of Sn reduces the segregation phenomenon on the surface of the casting.
基金supported by the STI 2030—Major Projects(Grant No.2021ZD0201201)National Natural Science Foundation of China(Grant No.92064012)Hubei Province Postdoctoral Innovation Research Program(Grant No.0106182103)。
文摘With rapid advancement and deep integration of artificial intelligence and the internet-of-things,artificial intelligence of things has emerged as a promising technology changing people’s daily life.Massive growth of data generated from the devices challenges the AIoT systems from information collection,storage,processing and communication.In the review,we introduce volatile threshold switching memristors,which can be roughly classified into three types:metallic conductive filament-based TS devices,amorphous chalcogenide-based ovonic threshold switching devices,and metal-insulator transition based TS devices.They play important roles in high-density storage,energy efficient computing and hardware security for AIoT systems.Firstly,a brief introduction is exhibited to describe the categories(materials and characteristics)of volatile TS devices.And then,switching mechanisms of the three types of TS devices are discussed and systematically summarized.After that,attention is focused on the applications in 3D cross-point memory technology with high storage-density,efficient neuromorphic computing,hardware security(true random number generators and physical unclonable functions),and others(steep subthreshold slope transistor,logic devices,etc.).Finally,the major challenges and future outlook of volatile threshold switching memristors are presented.
基金financially supported by the National Natural Science Foundation of China(202102007,21978147 and 21935001)the Fundamental Research Funds for the Central Universities(buctrc202112)。
文摘Selective reductive amination of carbonyl compounds with high activity is very essential for the chemical and pharmaceutical industry,but scarcely successful paradigm was reported via efficient photocatalytic reactions.Herein,the ultrasmall Ru nanoclusters(~0.9 nm)were successfully fabricated over P25 support with positive charged Ru^(δ+)species at the interface.A new route was developed to achieve the furfural(FAL)to furfurylamine(FAM)by coupling the light-driven reductive amination and hydrogen transfer of ethanol over this type catalyst.Strikingly,the photocatalytic activity and selectivity are strongly dependent on the particle size and electronic structure of Ruthenium.The Ru^(δ+)species at the interface promote the formation of active imine intermediates;moreover,the Ru nanoclusters facilitate the separation efficiency of electrons and holes as well as accelerate the further hydrogenation of imine intermediates to product primary amines.In contrast Ru particles in larger nanometer size facilitate the formation of the furfuryl alcohol and excessive hydrogenation products.In addition,the coupling byproducts can be effectively inhibited via the construction of sub-nanocluster.This study offers a new path to produce the primary amines from biomass-derived carbonyl compounds over hybrid semiconductor/metal-clusters photocatalyst via light-driven tandem catalytic process.
基金support from EPSRC-New Investigator Award 2020 (EP/V002260/1)The Faraday Institute-Battery Study and Seed Research Project (FIRG052)+2 种基金The Royal Society-International Exchanges 2021 Cost Share (NSFC)(IECNSFC211074)the China Scholarship Council (CSC, No. 201806130168)the International Postdoctoral Exchange Fellowship Program (Grant No. PC2022020)
文摘As the need for high-energy–density batteries continues to grow, lithium-sulfur(Li–S) batteries have become a highly promising next-generation energy solution due to their low cost and exceptional energy density compared to commercially available Li-ion batteries. Research into carbon-based sulfur hosts for Li–S batteries has been ongoing for over two decades, leading to a significant number of publications and patents.However, the commercialization of Li–S batteries has yet to be realized. This can be attributed, in part, to the instability of the Li metal anode. However, even when considering just the cathode side, there is still no consensus on whether carbon-based hosts will prove to be the best sulfur hosts for the industrialization of Li–S batteries. Recently, there has been controversy surrounding the use of carbon-based materials as the ideal sulfur hosts for practical applications of Li–S batteries under high sulfur loading and lean electrolyte conditions. To address this question, it is important to review the results of research into carbon-based hosts, assess their strengths and weaknesses, and provide a clear perspective. This review systematically evaluates the merits and mechanisms of various strategies for developing carbon-based host materials for high sulfur loading and lean electrolyte conditions. The review covers structural design and functional optimization strategies in detail, providing a comprehensive understanding of the development of sulfur hosts. The review also describes the use of efficient machine learning methods for investigating Li–S batteries. Finally, the outlook section lists and discusses current trends, challenges, and uncertainties surrounding carbon-based hosts, and concludes by presenting our standpoint and perspective on the subject.
基金Natural Science Foundation of Hebei Province(China),Grant/Award Numbers:B2020203013,B2021203016Science and Technology Project of Hebei Education Department(China),Grant/Award Number:QN2020137+3 种基金Cultivation Project for Basic Research Innovation of Yanshan University(China),Grant/Award Number:2021LGZD015Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(China),Grant/Award Number:22567616HNatural Science Foundation of Heilongjiang Province(China),Grant/Award Number:LH2022B025Fundamental Research Funds for the Provincial Universities of Heilongjiang Province(China),Grant/Award Number:KYYWF10236190104。
文摘Colorless‐to‐black switching has attracted widespread attention for smart windows and multifunctional displays because they are more useful to control solar energy.However,it still remains a challenge owing to the tremendous difficulties in the design of completely reverse absorptions in transmissive and colored states.Herein,we report on an electrochemical device that can switch between colorless and black by using the electrochemical process of hybrid organic–inorganic perovskite MAPbBr_(3),which shows a high integrated contrast ratio of up to 73%from 400 to 800 nm.The perovskite solution can be used as the active layer to assemble the device,showing superior transmittance over the entire visible region in neutral states.By applying an appropriate voltage,the device undergoes reversible switching between colorless and black,which is attributed to the formation of lead and Br_(2)in the redox reaction induced by the electron transfer process in MAPbBr_(3).In addition,the contrast ratio can be modulated over the entire visible region by changing the concentration and the applied voltage.These results contribute toward gaining an insightful understanding of the electrochemical process of perovskites and greatly promoting the development of switchable devices.
基金This research was financially supported by the National Natural Science Foundation of China(No.51575151 and No.52005005)the Science and Technology Project of Anhui Province,China(No.1501021006).
文摘The macrosegregation behaviors of Al-Sn-Cu ternary immiscible alloy castings and their effects on mechanical and tribological properties were investigated.The results demonstrate that Sn and Cu segregate in the casting simultaneously,and the mass fraction of the two elements has a"U"shaped distribution.Significantly,positive and negative segregation occur in the casting,with positive segregation appearing on the top and lower surfaces and negative segregation on the remaining surfaces,with the 1/2 surface(hot node location)having the highest degree of negative segregation.Furthermore,the results of Vickers hardness,tensile strength,and elongation show that Sn and Cu cooperatively affect the mechanical properties of castings.The higher the mass fraction of Sn and Cu elements,the higher the hardness,the greater the tensile strength,and the better the elongation.The findings of the step-by-step loading tests demonstrate that the segregation of Sn and Cu significantly impacts the tribological characteristics of the castings.The higher the mass fraction of Sn and Cu on the sample surface,the better the tribological characteristics.
基金financially supported by National Natural Science Foundation of China (Nos. U22A20193 and 51975218)Fundamental Research Funds for the Central Universities(No. 2022ZYGXZR101)+3 种基金Natural Science Foundation of Guangdong Province (No. 2021A1515010642)GuangdongHong Kong Joint Innovation Project of Guangdong Province(No. 2021A0505110002)Guangdong-Foshan Joint Foundation (No. 2021B1515120031)Innovation Group Project of Foshan (No. 2120001010816)
文摘The lithium-sulfur(Li-S)battery with an ultrahigh theoretical energy density has emerged as a promising rechargeable battery system.However,the practical applications of Li-S batteries are severely plagued by the sluggish reaction kinetics of sulfur species and notorious shuttling of soluble lithium polysulfides(LiPSs)intermediates that result in low sulfur utilization.The introduction of functional layers on separators has been considered as an effective strategy to improve the sulfur utilization in Li-S batteries by achieving effective regulation of LiPSs.Herein,a promising self-assembly strategy is proposed to achieve the low-cost fabrication of hollow and hierarchically porous Fe_(3)O_(4)nanospheres(p-Fe_(3)O_(4)-NSs)assembled by numerous extremely-small primary nanocrystals as building blocks.The rationally-designed p-Fe_(3)O_(4)-NSs are utilized as a multifunctional layer on the separator with highly efficient trapping and conversion features toward LiPSs.Results demonstrate that the nanostructured p-Fe_(3)O_(4)-NSs provide chemical adsorption toward LiPSs and kinetically promote the mutual transformation between LiPSs and Li_(2)S_(2)/Li_(2)S during cycling,thus inhibiting the LiPSs shuttling and boosting the redox reaction kinetics via a chemisorption-catalytic conversion mechanism.The enhanced wettability of the p-Fe_(3)O_(4)-NSs-based separator with the electrolyte enables fast transportation of lithium ions.Benefitting from these alluring properties,the functionalized separator with p-Fe_(3)O_(4)-NSs endows the battery with an admirable rate performance of 877 mAh g^(−1)at 2 C,an ultra-durable cycling performance of up to 2176 cycles at 1 C,and a promising areal capacity of 4.55 mAh cm^(−2)under high-sulfur-loading and lean-electrolyte conditions(4.29 mg cm^(−2),electrolyte/ratio:8μl mg^(−1)).This study will offer fresh insights on the rational design and low-cost fabrication of multifunctional separator to strengthen electrochemical reaction kinetics by regulating LiPSs conversion for developing efficient and long-life Li-S batteries.
文摘BACKGROUND Carcinosarcomas of the common bile duct(CBD)are an extremely rare finding in the clinical setting.Based on a review of 12 literatures,3 cases had the imaging features of ossification.Carcinosarcomas are prone to distant metastasis,as they possess clinical features of both carcinoma and sarcoma,and generally have with a poor prognosis.Due to the small number of cases reported,clinical experience in the diagnosis and treatment of the disease is lacking.CASE SUMMARY The patient was a 75-year-old woman who had experienced recurrent chills with nausea and vomiting for 3 mo.Computed tomography,magnetic resonance imaging,endoscopic ultrasonography and endoscopic retrograde cholangiopancreatography led to the diagnosis of malignant tumor of the CBD.The patient ultimately underwent cholecystectomy,CBD resection,and choledochojejunostomy.Postoperative pathological examination revealed carcinosarcoma of the CBD,and the latest follow-up showed that the patient is recovering well.Based on previous case reports,some carcinosarcoma has ossification characteristics in imaging.If it is misdiagnosed as biliary calculi,the use of laser lithotripsy in surgery may lead to tumor diffusion.Choledochoscopy and narrow band staining of mucosa are very important for diagnosis.CONCLUSION We herein present a rare case of carcinosarcomas of the CBD,we found the tumours may have imaging features of polypoid growth and ossification only when the sarcomal components are bone differentiation,while show soft tissue shadow when non bone differentiation.Confirmation of diagnosis depends greatly upon postoperative pathological examination and the adjuvant treatment has not been established,which leads to the poor prognosis.
基金National Natural Science Foundation of China,No.81970535。
文摘Nonalcoholic fatty liver disease(NAFLD)is the most common chronic liver dis-ease worldwide.NAFLD comprises a continuum of liver abnormalities from non-alcoholic fatty liver to nonalcoholic steatohepatitis,and can even lead to cirrhosis and liver cancer.However,a well-established treatment for NAFLD has yet to be identified.Exosomes have become an ideal drug delivery tool because of their high transmissibility,low immunogenicity,easy accessibility and targeting.Exosomes with specific modifications,known as engineered exosomes,have the potential to treat a variety of diseases.Here,we review the treatment of NAFLD with engineered exosomes and the potential use of exosomes as biomarkers and therapeutic targets for NAFLD.
文摘传统虚拟直流电机VDCM(Virtual DC Machine)控制策略未考虑直流电机转速动态调节问题,不能够在直流母线电压变化瞬间起调节作用。对此,提出一种模拟直流电机闭环调速的储能侧双向DC/DC变换器新型VDCM控制策略。对直流电机与双向DC/DC变换器在数学模型和控制策略上进行联系等效与差异剖析,模拟直流电机定转子绕组间的电磁感应作用,将直流电机动态数学模型嵌入P-U下垂控制中,使其兼备电压动态调节能力和惯性阻尼特性。对采用新型VDCM控制策略前、后的作用效果进行对比,仿真和实验结果表明该控制策略能够在提升母线电压动态调节特性的同时,增强惯性调节和阻尼效果,在负载切换或分布式发电单元输出功率波动时维持直流微电网稳定运行。
文摘目的比较拉米呋定与乙肝疫苗方案预防乙型肝炎核心抗体(hepatitis B core antibody,HBcAb)阳性供肝儿童肝移植术后新发乙型肝炎病毒(hepatitis B virus,HBV)感染效果。方法对天津市第一中心医院自2013年5月—2019年6月251例接受HBcAb阳性供肝儿童肝移植的资料进行回顾性分析,依据采用预防方案的不同分为拉米呋定组和乙肝疫苗组,对两组患儿的新发乙肝病毒感染情况以及临床资料进行比较分析。结果拉米呋定组45例和乙肝疫苗组206例,两组在供受者的临床特征方面无显著差异,两组的新发乙肝病毒感染例数分别为5例(11.1%)和10例(4.9%),发生率无显著统计意义(P=0.075),停用拉米呋定与新发乙肝存在关系。结论单用拉米呋定和乙肝疫苗均是有效预防HBcAb阳性供肝术后新发乙肝的方案,停用拉米呋定会增加新发乙肝的风险。
