The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Me...The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Metal oxides are able to expedite the sulfur electrochemistry,and the structural defects enhance the adsorption-conversion ability of metal oxides for polysulfides.However,a significant research gap still remains regarding the relationship between the oxygen vacancy concentration and the adsorptivecatalytic performance of metal oxides.Herein,we establish a correlation between oxygen vacancy concentration and adsorptive-catalytic properties by using tungsten oxide(WO_(x))as model catalysts.It is revealed that high-concentration oxygen vacancy is beneficial for enhancing the binding between tungsten oxide and LiPSs,reducing the energy barrier of Li_(2)S decomposition,and promoting polysulfide conversion kinetics.Consequently,the Li-S batteries using the tungsten oxide with high-concentration oxygen vacancies deliver high initial discharge capacity of 1169 mA h g^(-1)at 0.2 C and 865 mA h g^(-1)at 2 C,low attenuation rate of 0.064%per cycle over 1100 cycles at 2 C.With a high sulfur area loading of 5.34 mg cm^(-2),the Li-S batteries still exhibit high initial gravimetric capacity of 982 mA h g^(-1)at 0.1 C and areal capacity of 5.92 mA h cm^(-2).This work promotes the feasibility of defect engineering on metal oxides as an effective mean to enhance the practicality of Li-S batteries.展开更多
Soil water-stable aggregates (WSAs) are the basic unit of soil constitution and can contribute to remaining the stable soil constitution. The objective of this study was to clarify the distribution and stability of WS...Soil water-stable aggregates (WSAs) are the basic unit of soil constitution and can contribute to remaining the stable soil constitution. The objective of this study was to clarify the distribution and stability of WSAs and the soil organic carbon (SOC), the total nitrogen (TN), and the total phosphorus (TP) concentrations in 0 - 20 cm and 20 - 40 cm soil layers under the different ages of Robinia pseudoacacia plantations. The 20, 25, 40, and 50 years-old Robinia pseudoacacia plantations were selected. Stepwise regression analysis showed that >5 mm and 1 - 2 mm WSAs, SOC concentration in 2 - 5 mm WSAs, and TN and TP concentrations in < 0.25 mm WSAs were dominant independent variables affecting aggregate stability and that SOC in 0.25 - 0.5 mm WSAs, TN in <0.25 mm and 1 - 2 mm WSAs and TP in 2 - 5 mm WSAs were dominant independent variables affecting SOC, TN, and TP concentrations in bulk soils.展开更多
BACKGROUND Non-ketotic hyperglycaemic(NKH)seizures are a rare neurological complication of diabetes caused by hyperglycaemia in non-ketotic and non-hyperosmotic states.The clinical characteristics of NKH seizures are ...BACKGROUND Non-ketotic hyperglycaemic(NKH)seizures are a rare neurological complication of diabetes caused by hyperglycaemia in non-ketotic and non-hyperosmotic states.The clinical characteristics of NKH seizures are atypical and lack unified diagnostic criteria,leading to potential misdiagnoses in the early stages of the disease.CASE SUMMARY This report presents a rare case of NKH seizures in a 52-year-old male patient with a history of type 2 diabetes mellitus.We performed comprehensive magnetic resonance imaging(MRI)studies at admission,12 d post-admission,and 20 d post-discharge.The imaging techniques included contrast-enhanced head MRI,T2-weighted imaging(T2WI),fluid-attenuated inversion recovery(FLAIR),diffusion-weighted imaging,susceptibility-weighted imaging,magnetic reso-nance spectroscopy(MRS),and magnetic resonance venography.At the time of admission,T2WI and FLAIR of the cranial MRI showed that the left parieto-occipital cortex had gyrus-like swelling and high signal,and subcortical stripes had low signal.MRS showed a reduced N-acetylaspartate peak and increased creatine and choline peaks in the affected areas.A follow-up MRI 20 d later showed that the swelling and high signal of the left parieto-occipital cortex had disappeared,and the low signal of the subcortex had disappeared.CONCLUSION This case study provides valuable insights into the potential pathogenesis,diagnosis,and treatment of NKH seizures.The comprehensive MRI findings highlight the potential utility of various MRI sequences in diagnosing and characterizing NKH seizures.展开更多
The aim of this paper is to understand the common characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objec...The aim of this paper is to understand the common characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objects or temporally capture ejecta into circling orbits. The gravitational potential of elongated bodies is described by a unified approximate model, i.e., the rotating mass dipole which is two point masses connected with a constant massless rod The energy power is used to illustrate the flyby effect in terms of the instantaneous orbital energy. The essential of the single flyby trajectory is studied analytically, and the relationship between the flyby trajectory and its Jacobi integral is also illustrated. Sample trajectories are given to show the variational trend of the energy increment with respect to differen orbital periapsides. The distribution of natural ejecting orbits is presented by varying the parameters of the approximate model.展开更多
Aluminum-metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety.However,the crucial limitations of metallic Al anodes,such as dendrite and corrosion...Aluminum-metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety.However,the crucial limitations of metallic Al anodes,such as dendrite and corrosion problems in conventional aluminum-metal batteries,remain challenging and elusive.Here,we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology,low local current density,and mitigatory volume change.The symmetrical cells with the 3D Al anode show superior stable cycling(>450 h)and low-voltage hysteresis(~170 mV)at 0.5 mA cm^(−2).High reversibility(~99.7%)is achieved for the Al plating/stripping.The graphite||Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g^(−1) capacity at a high current density of 1000 mA g^(−1),benefiting from the high capacitive-controlled distribution.This study proposes a novel strategy to design 3D Al anodes for metallic-Al-based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum-graphite batteries.展开更多
A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56...A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56Ω·mm at an alloy temperature of 550℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the specific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emission(TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52×10^(18) cm^(−3),which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic transfer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compatible metal-insulator-semiconductor high-mobility transistor(MIS-HEMT)was fabricated with the proposed Au-free ohmic contact technique.展开更多
The Electro-Fenton(EF)process is one of the promising advanced oxidation processes(AOPs)for environmental remediation.The H_(2)O_(2) yield of EF process largely determines its performance on organic pollutants degrada...The Electro-Fenton(EF)process is one of the promising advanced oxidation processes(AOPs)for environmental remediation.The H_(2)O_(2) yield of EF process largely determines its performance on organic pollutants degradation.Conventional Pd-catalytic EF process generates H_(2)O_(2) via the combination reaction of anodic O_(2) and cathodic H;.However,the relatively expensive catalyst limits its application.Herein,a hybrid Pd/activated carbon(Pd/AC)-stainless steel mesh(SS)cathode(PACSS)was proposed,which enables more efficie nt H_(2)O_(2)generation.It utilizes AC,the support of Pd catalyst,as part of cathode for H_(2)O_(2) generation via 2-electron anodic O_(2) reduction,and SS serve as a current distributor.Moreover,H_(2)O_(2) could be catalytically decomposed upon AC to generate highly reactive·OH,which avoids the use of Fe;.Compared with conventional Pd catalyst,H_(2)O_(2) concentration obtained by PACSS cathode is248.2%higher,the O_(2)utilization efficiency was also increased from 3.2%to 10.8%.Within 50 min,26.3%,72.5%,and 94.0%H_(2)O_(2) was decomposed by Pd,AC,and Pd/AC.Fluorescence detection results implied that Pd/AC is effective upon H_(2)O_(2) activation for·OH generation.Finally,iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19(RB19)degradation.After continuous running for 10 cycles(500 min),the PACSS cathode was still stable for H_(2)O_(2)generation,H_(2)O_(2)activation,and RB19 degradation,showing its potential application for organic pollutants degradation without increase in the running cost.展开更多
The United Nations Framework Convention on Climate Change(UNFCCC)has established a climate governance mechanism with intergovernmental negotiations among sovereign states as the core.After nearly 30 years,progress in ...The United Nations Framework Convention on Climate Change(UNFCCC)has established a climate governance mechanism with intergovernmental negotiations among sovereign states as the core.After nearly 30 years,progress in combating climate change has remained very modest compared with the numerous challenges raised.The global climate governance has entered a new era,such that incorporating other factors into the governance process is timely.Therefore,the study emphasizes technological innovation and business actors in climate governance after the Paris Agreement.Technological innovation can provide effective solutions for combating climate change and has been a crucial driving force in climate governance's evolution.Business actors are significant because they are actual implementers of technological innovation and can apply different types of power and influence on climate governance processes at various levels.In summary,business actors,as well as technological innovation in line with governments and the UNFCCC governance frameworks,create a new potential for climate governance in the new era.展开更多
Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characte...Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.展开更多
We construct the Hall-bar device with the size of several hundred nanometers based on the HZO/Co multiferroic heterojunction. A remarkable voltage-controlled magnetism is observed in the device that possesses both fer...We construct the Hall-bar device with the size of several hundred nanometers based on the HZO/Co multiferroic heterojunction. A remarkable voltage-controlled magnetism is observed in the device that possesses both ferroelectric property and perpendicular magnetic anisotropy(PMA). The nucleation field and coercivity can be modulated by voltage pulse while saturation field keeps stable. The non-volatile and reversible voltage-controlled magnetism is ascribable to interfacial charges caused by ferroelectric polarization. Meanwhile, the effective anisotropy energy density(Ku) can also be controlled by voltage pulse, a decrease of 83% and increase of 28% in Kuare realized under-3-V and 3-V pulses,respectively. Because the energy barrier is directly proportional to Ku under a given volume, a decreased or enhanced energy barrier can be controlled by voltage pulse. Thus, it is an effective method to realize low-power and high-stability magneto-resistive random-access memory(MRAM).展开更多
Polystyrene resins(PS)have been practical ion exchangers for radionuclides removal from water.However,nonspecific effects of ion exchange groups continue to be a major obstacle for emergency treatment with coexisting ...Polystyrene resins(PS)have been practical ion exchangers for radionuclides removal from water.However,nonspecific effects of ion exchange groups continue to be a major obstacle for emergency treatment with coexisting ions of high concentrations.The selectivity for Cs+enables zirconium phosphate(ZrP)to be the most promising inorganic sorbent for radioactive cesium extraction,despite being difficult to synthesize and causing excessive pressure loss in fixed-bed reactors due to fine powder.Herein,through facile confined crystallization in host macropores,we prepared PS confinedα-ZrP nanocrystalline(ZrP-PS).Size-screen sorption of layeredα-ZrP and sulfonic acid group preconcentration of PS synergistically enable a considerably higher Cs+affinity of ZrP-PS than PS,as confirmed by X-ray photoelectron spectroscopy(XPS)analysis.ZrP-PS demonstrated remarkable cesium sequestration performance in both batch and continuous experiments,with a high adsorption capacity of 269.58 mg/g,a rapid equilibrium within 80 min,and a continuous effluent volume of 2300 L/kg sorbents.Given the excellent selectivity for Cs+and flexibility to separate from treated water,ZrP-PS holds great promise as purification packages for the emergency treatment of radioactively contaminated water.展开更多
Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and ...Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method.展开更多
One of the core issues in modern celestial mechanics is the orbital dynamics in the near-regime gravitational field of asteroids,which provides deep insights into the mathematical nature of a class of nonlinear system...One of the core issues in modern celestial mechanics is the orbital dynamics in the near-regime gravitational field of asteroids,which provides deep insights into the mathematical nature of a class of nonlinear systems,and plays as a critical basis for in situ explorations of different science goals.Lots of efforts have been made to reveal the characteristics of orbital motion in the vicinity of asteroids,and to improve展开更多
Given n≥2 and α≥1/2,we obtained an improved upbound of Hausdorff's dimension of the fractional Schrodinger operator;that is,supf∈H^(s)(R^(n)) dim_(H){x∈R^(n):limt→0 e^(it)(-△)^(α) f(x)≠f(x)}≤n+1-2(n+1)s/...Given n≥2 and α≥1/2,we obtained an improved upbound of Hausdorff's dimension of the fractional Schrodinger operator;that is,supf∈H^(s)(R^(n)) dim_(H){x∈R^(n):limt→0 e^(it)(-△)^(α) f(x)≠f(x)}≤n+1-2(n+1)s/n for n/2(n+1)<s≤n/2.展开更多
It was estimated that every year more than 30000 persons in the United States- approximately 80 people per day- are diagnosed with type 1 diabetes(T1D). T1 D is caused by autoimmune destruction of the pancreatic islet...It was estimated that every year more than 30000 persons in the United States- approximately 80 people per day- are diagnosed with type 1 diabetes(T1D). T1 D is caused by autoimmune destruction of the pancreatic islet(β cells) cells. Islet transplantation has become a promising therapy option for T1 D patients, while the lack of suitable tools is difficult to directly evaluate of the viability of the grafted islet over time. Positron emission tomography(PET) as an important non-invasive methodology providing high sensitivity and good resolution, is able to accurate detection of the disturbed biochemical processes and physiological abnormality in living organism. The successful PET imaging of islets would be able to localize the specific site where transplanted islets engraft in the liver, and to quantify the level of islets remain alive and functional over time. This information would be vital to establishing and evaluating the efficiency of pancreatic islet transplantation. Many novel imaging agents have been developed to improve the sensitivity and specificity of PET islet imaging. In this article, we summarize the latest developments in carbon-11, fluorine-18, copper-64, and gallium-68 labeled radioligands for the PET imaging of pancreatic islet cells.展开更多
The traditional thought of energy security under the framework of fossil energy can no longer cope with the new energy security problems.In this case,a systematic transition towards low-carbon,clean energy from fossil...The traditional thought of energy security under the framework of fossil energy can no longer cope with the new energy security problems.In this case,a systematic transition towards low-carbon,clean energy from fossil fuels is the key to addressing the new energy security challenges.This is mainly because the energy transition promotes three major shifts that strengthen energy security.The development mode shifts from resource dependence to technology dependence,laying a material foundation for common energy security,energy production shifts from mineral mining to equipment manufacturing,stimulating a new economic vitality,conventional energy consumption mode enters into the era of electrification,ensuring the sustainable energy security.展开更多
With the rise of open-source software,the social development paradigm occupies an indispensable position in the current software development process.This paper puts forward a variant of the PageRank algorithm to build...With the rise of open-source software,the social development paradigm occupies an indispensable position in the current software development process.This paper puts forward a variant of the PageRank algorithm to build the importance assessment model,which provides quantifiable importance assessment metrics for new Java projects based on Java open-source projects or components.The critical point of the model is to use crawlers to obtain relevant information about Java open-source projects in the GitHub open-source community to build a domain knowledge graph.According to the three dimensions of the Java open-source project’s project influence,project activity and project popularity,the project is measured.A modified PageRank algorithm is proposed to construct the importance evaluation model.Thereby providing quantifiable importance evaluation indicators for new Java projects based on or components of Java open-source projects.This article evaluates the importance of 4512 Java open-source projects obtained on GitHub and has a good effect.展开更多
The d-band centers of catalysts have exhibited excellent performance in various reactions.Among them,the enhanced catalytic reaction is considered a crucial way to power dynamics and reduce the“shuttle”effect in pol...The d-band centers of catalysts have exhibited excellent performance in various reactions.Among them,the enhanced catalytic reaction is considered a crucial way to power dynamics and reduce the“shuttle”effect in polysulfide conversions of lithium-sulfur batteries.Here,we report two-dimensional-shaped tungsten borides(WB)nanosheets with d-band centers,where the d orbits of W atoms on the(001)facets show greatly promoting the electrocatalytic sulfur reduction reaction.As-prepared WB-based Li-S cells exhibit excellent electrochemical performance for Li-ion storage.Especially,it delivers superior capacities of 7.7 mAh/cm^(2) under the 8.0 mg/cm^(2) sulfur loading,which is far superior to most other electrode catalysts.This study provides insights into the d-band centers as a promising catalyst of twodimensional boride materials.展开更多
基金financially supported by National Natural Science Foundation of China(Grant Nos.51972070 and 52062004)Guizhou Provincial High Level Innovative Talents Project(Grant No.QKHPTRC-GCC[2022]013-1)+2 种基金Innovation Team for Advanced Electrochemical Energy Storage Devices and Key Materials of Guizhou Provincial Higher Education Institutions(Grant No.QianJiaoJi[2023]054)Guizhou Provincial Science and Technology Projects(Grant No.QKHJC[2020]1Z042)Cultivation Project of Guizhou University(Grant No.GDPY[2019]01)。
文摘The“shuttle effect”of lithium polysulfides(LiPSs)is a huge challenge for practical use of high-energydensity lithium-sulfur(Li-S)batteries,and one of the main reasons is the sluggish kinetics of sulfur conversion.Metal oxides are able to expedite the sulfur electrochemistry,and the structural defects enhance the adsorption-conversion ability of metal oxides for polysulfides.However,a significant research gap still remains regarding the relationship between the oxygen vacancy concentration and the adsorptivecatalytic performance of metal oxides.Herein,we establish a correlation between oxygen vacancy concentration and adsorptive-catalytic properties by using tungsten oxide(WO_(x))as model catalysts.It is revealed that high-concentration oxygen vacancy is beneficial for enhancing the binding between tungsten oxide and LiPSs,reducing the energy barrier of Li_(2)S decomposition,and promoting polysulfide conversion kinetics.Consequently,the Li-S batteries using the tungsten oxide with high-concentration oxygen vacancies deliver high initial discharge capacity of 1169 mA h g^(-1)at 0.2 C and 865 mA h g^(-1)at 2 C,low attenuation rate of 0.064%per cycle over 1100 cycles at 2 C.With a high sulfur area loading of 5.34 mg cm^(-2),the Li-S batteries still exhibit high initial gravimetric capacity of 982 mA h g^(-1)at 0.1 C and areal capacity of 5.92 mA h cm^(-2).This work promotes the feasibility of defect engineering on metal oxides as an effective mean to enhance the practicality of Li-S batteries.
文摘Soil water-stable aggregates (WSAs) are the basic unit of soil constitution and can contribute to remaining the stable soil constitution. The objective of this study was to clarify the distribution and stability of WSAs and the soil organic carbon (SOC), the total nitrogen (TN), and the total phosphorus (TP) concentrations in 0 - 20 cm and 20 - 40 cm soil layers under the different ages of Robinia pseudoacacia plantations. The 20, 25, 40, and 50 years-old Robinia pseudoacacia plantations were selected. Stepwise regression analysis showed that >5 mm and 1 - 2 mm WSAs, SOC concentration in 2 - 5 mm WSAs, and TN and TP concentrations in < 0.25 mm WSAs were dominant independent variables affecting aggregate stability and that SOC in 0.25 - 0.5 mm WSAs, TN in <0.25 mm and 1 - 2 mm WSAs and TP in 2 - 5 mm WSAs were dominant independent variables affecting SOC, TN, and TP concentrations in bulk soils.
基金Supported by Four"Batches"Innovation Project of Invigorating Medical Through Science and Technology of Shanxi Province,No.2023XM016.
文摘BACKGROUND Non-ketotic hyperglycaemic(NKH)seizures are a rare neurological complication of diabetes caused by hyperglycaemia in non-ketotic and non-hyperosmotic states.The clinical characteristics of NKH seizures are atypical and lack unified diagnostic criteria,leading to potential misdiagnoses in the early stages of the disease.CASE SUMMARY This report presents a rare case of NKH seizures in a 52-year-old male patient with a history of type 2 diabetes mellitus.We performed comprehensive magnetic resonance imaging(MRI)studies at admission,12 d post-admission,and 20 d post-discharge.The imaging techniques included contrast-enhanced head MRI,T2-weighted imaging(T2WI),fluid-attenuated inversion recovery(FLAIR),diffusion-weighted imaging,susceptibility-weighted imaging,magnetic reso-nance spectroscopy(MRS),and magnetic resonance venography.At the time of admission,T2WI and FLAIR of the cranial MRI showed that the left parieto-occipital cortex had gyrus-like swelling and high signal,and subcortical stripes had low signal.MRS showed a reduced N-acetylaspartate peak and increased creatine and choline peaks in the affected areas.A follow-up MRI 20 d later showed that the swelling and high signal of the left parieto-occipital cortex had disappeared,and the low signal of the subcortex had disappeared.CONCLUSION This case study provides valuable insights into the potential pathogenesis,diagnosis,and treatment of NKH seizures.The comprehensive MRI findings highlight the potential utility of various MRI sequences in diagnosing and characterizing NKH seizures.
基金supported by the National Basic Research Program of China(973 Program),(Grant 2012CB720000)China Postdoctoral Science Foundation(Grant 2014M560076)Support from Shanghai Satellite Engineering Research Institute(Grant 13dz2260100)is also acknowledged
文摘The aim of this paper is to understand the common characteristics of the generalized flyby trajectory around natural elongated bodies. Such flyby trajectories provide a short-term mechanism to clear away vicinal objects or temporally capture ejecta into circling orbits. The gravitational potential of elongated bodies is described by a unified approximate model, i.e., the rotating mass dipole which is two point masses connected with a constant massless rod The energy power is used to illustrate the flyby effect in terms of the instantaneous orbital energy. The essential of the single flyby trajectory is studied analytically, and the relationship between the flyby trajectory and its Jacobi integral is also illustrated. Sample trajectories are given to show the variational trend of the energy increment with respect to differen orbital periapsides. The distribution of natural ejecting orbits is presented by varying the parameters of the approximate model.
基金This study was funded by the Science and Technology Development Fund,Macao SAR(File no.0191/2017/A3,0041/2019/A1,0046/2019/AFJ,0021/2019/AIR)the University of Macao(File no.MYRG2017-00216-FST and MYRG2018-00192-IAPME)+2 种基金the UEA funding,Science and Technology Program of Guangzhou(2019050001)the National Key Research and Development Program of China(2019YFE0198000)Fuming Chen acknowledges the Pearl River Talent Program(2019QN01L951).
文摘Aluminum-metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety.However,the crucial limitations of metallic Al anodes,such as dendrite and corrosion problems in conventional aluminum-metal batteries,remain challenging and elusive.Here,we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology,low local current density,and mitigatory volume change.The symmetrical cells with the 3D Al anode show superior stable cycling(>450 h)and low-voltage hysteresis(~170 mV)at 0.5 mA cm^(−2).High reversibility(~99.7%)is achieved for the Al plating/stripping.The graphite||Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g^(−1) capacity at a high current density of 1000 mA g^(−1),benefiting from the high capacitive-controlled distribution.This study proposes a novel strategy to design 3D Al anodes for metallic-Al-based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum-graphite batteries.
基金supported by National Natural Science Foundation of China under Grant 61822407,Grant 62074161,and Grant 11634002in part by the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)under Grant QYZDB-SSW-JSC012+3 种基金in part by the National Key Research and Development Program of China under Grant 2016YFB0400105 and Grant 2017YFB0403000in part by the Youth Innovation Promotion Association of CASin part by the University of Chinese Academy of Sciencesand in part by the Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology,Institute of Microelectronics,CAS.
文摘A pre-ohmic micro-patterned recess process,is utilized to fabricate Ti/Al/Ti/TiN ohmic contact to an ultrathin-barrier(UTB)AlGaN/GaN heterostructure,featuring a significantly reduced ohmic contact resistivity of 0.56Ω·mm at an alloy temperature of 550℃.The sheet resistances increase with the temperature following a power law with the index of +2.58,while the specific contact resistivity decreases with the temperature.The contact mechanism can be well described by thermionic field emission(TFE).The extracted Schottky barrier height and electron concentration are 0.31 eV and 5.52×10^(18) cm^(−3),which suggests an intimate contact between ohmic metal and the UTB-AlGaN as well as GaN buffer.A good correlation between ohmic transfer length and the micro-pattern size is revealed,though in-depth investigation is needed.A preliminary CMOS-process-compatible metal-insulator-semiconductor high-mobility transistor(MIS-HEMT)was fabricated with the proposed Au-free ohmic contact technique.
基金financially supported by the National Natural Science Foundation of China(Nos.52006049,51776055)the China Postdoctoral Science Foundation(Nos.2019M661293,2020T130149)。
文摘The Electro-Fenton(EF)process is one of the promising advanced oxidation processes(AOPs)for environmental remediation.The H_(2)O_(2) yield of EF process largely determines its performance on organic pollutants degradation.Conventional Pd-catalytic EF process generates H_(2)O_(2) via the combination reaction of anodic O_(2) and cathodic H;.However,the relatively expensive catalyst limits its application.Herein,a hybrid Pd/activated carbon(Pd/AC)-stainless steel mesh(SS)cathode(PACSS)was proposed,which enables more efficie nt H_(2)O_(2)generation.It utilizes AC,the support of Pd catalyst,as part of cathode for H_(2)O_(2) generation via 2-electron anodic O_(2) reduction,and SS serve as a current distributor.Moreover,H_(2)O_(2) could be catalytically decomposed upon AC to generate highly reactive·OH,which avoids the use of Fe;.Compared with conventional Pd catalyst,H_(2)O_(2) concentration obtained by PACSS cathode is248.2%higher,the O_(2)utilization efficiency was also increased from 3.2%to 10.8%.Within 50 min,26.3%,72.5%,and 94.0%H_(2)O_(2) was decomposed by Pd,AC,and Pd/AC.Fluorescence detection results implied that Pd/AC is effective upon H_(2)O_(2) activation for·OH generation.Finally,iron-free EF process enabled by PACSS cathode was examined to be effective for reactive blue 19(RB19)degradation.After continuous running for 10 cycles(500 min),the PACSS cathode was still stable for H_(2)O_(2)generation,H_(2)O_(2)activation,and RB19 degradation,showing its potential application for organic pollutants degradation without increase in the running cost.
文摘The United Nations Framework Convention on Climate Change(UNFCCC)has established a climate governance mechanism with intergovernmental negotiations among sovereign states as the core.After nearly 30 years,progress in combating climate change has remained very modest compared with the numerous challenges raised.The global climate governance has entered a new era,such that incorporating other factors into the governance process is timely.Therefore,the study emphasizes technological innovation and business actors in climate governance after the Paris Agreement.Technological innovation can provide effective solutions for combating climate change and has been a crucial driving force in climate governance's evolution.Business actors are significant because they are actual implementers of technological innovation and can apply different types of power and influence on climate governance processes at various levels.In summary,business actors,as well as technological innovation in line with governments and the UNFCCC governance frameworks,create a new potential for climate governance in the new era.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences (Project ID.XDA0330300)in part by Innovation Program for Quantum Science and Technology (Project ID.2021ZD0302301)in part by the Youth Innovation Promotion Association of CAS (Project ID.2020037)。
文摘Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.
基金supported by Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA18000000)the Fund from the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. 2015097)Guangzhou City Research and Development Program in Key Fields (Grant No. 202103020001)。
文摘We construct the Hall-bar device with the size of several hundred nanometers based on the HZO/Co multiferroic heterojunction. A remarkable voltage-controlled magnetism is observed in the device that possesses both ferroelectric property and perpendicular magnetic anisotropy(PMA). The nucleation field and coercivity can be modulated by voltage pulse while saturation field keeps stable. The non-volatile and reversible voltage-controlled magnetism is ascribable to interfacial charges caused by ferroelectric polarization. Meanwhile, the effective anisotropy energy density(Ku) can also be controlled by voltage pulse, a decrease of 83% and increase of 28% in Kuare realized under-3-V and 3-V pulses,respectively. Because the energy barrier is directly proportional to Ku under a given volume, a decreased or enhanced energy barrier can be controlled by voltage pulse. Thus, it is an effective method to realize low-power and high-stability magneto-resistive random-access memory(MRAM).
基金NSFC(Nos.U22A20403,21301151 and 52070115)Natural Science Foundation of Hebei Province(Nos.B2021203036 and E2022203011)Key Project of the Hebei Education Department(No.ZD2021103).
文摘Polystyrene resins(PS)have been practical ion exchangers for radionuclides removal from water.However,nonspecific effects of ion exchange groups continue to be a major obstacle for emergency treatment with coexisting ions of high concentrations.The selectivity for Cs+enables zirconium phosphate(ZrP)to be the most promising inorganic sorbent for radioactive cesium extraction,despite being difficult to synthesize and causing excessive pressure loss in fixed-bed reactors due to fine powder.Herein,through facile confined crystallization in host macropores,we prepared PS confinedα-ZrP nanocrystalline(ZrP-PS).Size-screen sorption of layeredα-ZrP and sulfonic acid group preconcentration of PS synergistically enable a considerably higher Cs+affinity of ZrP-PS than PS,as confirmed by X-ray photoelectron spectroscopy(XPS)analysis.ZrP-PS demonstrated remarkable cesium sequestration performance in both batch and continuous experiments,with a high adsorption capacity of 269.58 mg/g,a rapid equilibrium within 80 min,and a continuous effluent volume of 2300 L/kg sorbents.Given the excellent selectivity for Cs+and flexibility to separate from treated water,ZrP-PS holds great promise as purification packages for the emergency treatment of radioactively contaminated water.
基金Supported by National Key R&D Projects(Grant No.2018YFB0905500)National Natural Science Foundation of China(Grant No.51875498)+1 种基金Hebei Provincial Natural Science Foundation of China(Grant Nos.E2018203439,E2018203339,F2016203496)Key Scientific Research Projects Plan of Henan Higher Education Institutions(Grant No.19B460001)
文摘Based on Multi-Masking Empirical Mode Decomposition (MMEMD) and fuzzy c-means (FCM) clustering, a new method of wind turbine bearing fault diagnosis FCM-MMEMD is proposed, which can determine the fault accurately and timely. First, FCM clustering is employed to classify the data into different clusters, which helps to estimate whether there is a fault and how many fault types there are. If fault signals exist, the fault vibration signals are then demodulated and decomposed into different frequency bands by MMEMD in order to be analyzed further. In order to overcome the mode mixing defect of empirical mode decomposition (EMD), a novel method called MMEMD is proposed. It is an improvement to masking empirical mode decomposition (MEMD). By adding multi-masking signals to the signals to be decomposed in different levels, it can restrain low-frequency components from mixing in highfrequency components effectively in the sifting process and then suppress the mode mixing. It has the advantages of easy implementation and strong ability of suppressing modal mixing. The fault type is determined by Hilbert envelope finally. The results of simulation signal decomposition showed the high performance of MMEMD. Experiments of bearing fault diagnosis in wind turbine bearing fault diagnosis proved the validity and high accuracy of the new method.
文摘One of the core issues in modern celestial mechanics is the orbital dynamics in the near-regime gravitational field of asteroids,which provides deep insights into the mathematical nature of a class of nonlinear systems,and plays as a critical basis for in situ explorations of different science goals.Lots of efforts have been made to reveal the characteristics of orbital motion in the vicinity of asteroids,and to improve
基金Li Dan and Li Junfeng were supported by NSFC-DFG(11761131002)NSFC(12071052)Xiao Jie was supported by NSERC of Canada(202979463102000).
文摘Given n≥2 and α≥1/2,we obtained an improved upbound of Hausdorff's dimension of the fractional Schrodinger operator;that is,supf∈H^(s)(R^(n)) dim_(H){x∈R^(n):limt→0 e^(it)(-△)^(α) f(x)≠f(x)}≤n+1-2(n+1)s/n for n/2(n+1)<s≤n/2.
基金Supported by The grant from the Larry L.Hillblom Foundation
文摘It was estimated that every year more than 30000 persons in the United States- approximately 80 people per day- are diagnosed with type 1 diabetes(T1D). T1 D is caused by autoimmune destruction of the pancreatic islet(β cells) cells. Islet transplantation has become a promising therapy option for T1 D patients, while the lack of suitable tools is difficult to directly evaluate of the viability of the grafted islet over time. Positron emission tomography(PET) as an important non-invasive methodology providing high sensitivity and good resolution, is able to accurate detection of the disturbed biochemical processes and physiological abnormality in living organism. The successful PET imaging of islets would be able to localize the specific site where transplanted islets engraft in the liver, and to quantify the level of islets remain alive and functional over time. This information would be vital to establishing and evaluating the efficiency of pancreatic islet transplantation. Many novel imaging agents have been developed to improve the sensitivity and specificity of PET islet imaging. In this article, we summarize the latest developments in carbon-11, fluorine-18, copper-64, and gallium-68 labeled radioligands for the PET imaging of pancreatic islet cells.
文摘The traditional thought of energy security under the framework of fossil energy can no longer cope with the new energy security problems.In this case,a systematic transition towards low-carbon,clean energy from fossil fuels is the key to addressing the new energy security challenges.This is mainly because the energy transition promotes three major shifts that strengthen energy security.The development mode shifts from resource dependence to technology dependence,laying a material foundation for common energy security,energy production shifts from mineral mining to equipment manufacturing,stimulating a new economic vitality,conventional energy consumption mode enters into the era of electrification,ensuring the sustainable energy security.
基金This work has been supported by the National Science Foundation of China Grant No.61762092“Dynamic multi-objective requirement optimization based on transfer learning,”and the Open Foundation of the Key Laboratory in Software Engineering of Yunnan Province,Grant No.2017SE204+1 种基金“Research on extracting software feature models using transfer learning,”and the National Science Foundation of China Grant No.61762089“The key research of high order tensor decomposition in a distributed environment”.
文摘With the rise of open-source software,the social development paradigm occupies an indispensable position in the current software development process.This paper puts forward a variant of the PageRank algorithm to build the importance assessment model,which provides quantifiable importance assessment metrics for new Java projects based on Java open-source projects or components.The critical point of the model is to use crawlers to obtain relevant information about Java open-source projects in the GitHub open-source community to build a domain knowledge graph.According to the three dimensions of the Java open-source project’s project influence,project activity and project popularity,the project is measured.A modified PageRank algorithm is proposed to construct the importance evaluation model.Thereby providing quantifiable importance evaluation indicators for new Java projects based on or components of Java open-source projects.This article evaluates the importance of 4512 Java open-source projects obtained on GitHub and has a good effect.
基金supported by the National Natural Science Foundation of China(Nos.61904080,22205101)the Natural Science Foundation of Jiangsu Province(No.BK20190670)+5 种基金the Natural Science Foundation of Colleges and Universities in Jiangsu Province(No.19KJB530008)the Macao Young Scholars Program(No.AM2020005)the High-Performance Computing Cluster(HPCC)of Information and Communication Technology Office(ICTO)at University of Macao,Science and Technology Development Fund,Macao SAR(Nos.0191/2017/A3,0041/2019/A1,0046/2019/AFJ,0021/2019/AIR)University of Macao(Nos.MYRG2017-00216-FST and MYRG2018-00192-IAPME),FDCT Funding Scheme for Postdoctoral Researchers(No.0026/APD/2021)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the UEA funding,and Guangdong Basic and Applied Basic Research Foundation(No.2022A1515110994).
文摘The d-band centers of catalysts have exhibited excellent performance in various reactions.Among them,the enhanced catalytic reaction is considered a crucial way to power dynamics and reduce the“shuttle”effect in polysulfide conversions of lithium-sulfur batteries.Here,we report two-dimensional-shaped tungsten borides(WB)nanosheets with d-band centers,where the d orbits of W atoms on the(001)facets show greatly promoting the electrocatalytic sulfur reduction reaction.As-prepared WB-based Li-S cells exhibit excellent electrochemical performance for Li-ion storage.Especially,it delivers superior capacities of 7.7 mAh/cm^(2) under the 8.0 mg/cm^(2) sulfur loading,which is far superior to most other electrode catalysts.This study provides insights into the d-band centers as a promising catalyst of twodimensional boride materials.
