Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also ch...Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.展开更多
Previous studies have suggested that the incidence of post-traumatic stress disorder in earthquake rescue workers is relatively high. Risk factors for this disorder include demographic characteristics, earthquake-rela...Previous studies have suggested that the incidence of post-traumatic stress disorder in earthquake rescue workers is relatively high. Risk factors for this disorder include demographic characteristics, earthquake-related high-risk factors, risk factors in the rescue process, personality, social support and coping style. This study examined the current status of a unit of 1 040 rescue workers who participated in earthquake relief for the Wenchuan earthquake that occurred on May 12th, 2008. Post-traumatic stress disorder was diagnosed primarily using the Clinician-Administered Post-traumatic Stress Disorder Scale during structured interviews. Univariate and multivariate sta-tistical analyses were used to examine major risk factors that contributed to the incidence of post-traumatic stress disorder. Results revealed that the incidence of this disorder in the rescue group was 5.96%. The impact factors in univariate analysis included death of family members, contact with corpses or witnessing of the deceased or seriously injured, near-death experience, severe injury or mental trauma in the rescue process and working at the epicenter of the earthquake. Correlation analysis suggested that post-traumatic stress disorder was positively correlated with psychotic and neurotic personalities, negative coping and low social support. Impact factors in mul-tivariate logistic regression analysis included near-death experience, severe injury or mental trauma, working in the epicenter of the rescue, neurotic personality, negative coping and low social support, among which low social support had the largest odds ratio of 20.42. Findings showed that the oc-currence of post-traumatic stress disorder was the result of the interaction of multiple factors.展开更多
Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers...Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers.Rational designed the structure and doping elements become important alternative routes to improve the performance of photocatalyst.In this work,we rational designed oxygen-doped graphitic carbon nitride(OCN)nanotubes derived from supermolecular intermediates for photocata lytic water splitting.The as prepared OCN nanotubes exhibit an outstanding hydrogen evolution rate of 73.84μmol h^(-1),outperforming the most of reported one dimensional(1D)g-C_(3)N_(4) previously.Due to the rational oxygen doping,the band structure of g-C_(3)N_(4) is meliorated,which can narrow the band gap and reduce the recombination rate of photogene rated carriers.Furthermore,the hollow nanotube structure of OCN also provide multiple diffuse reflection during photocata lytic reaction,which can significantly promote the utilization capacity of visible light and enhance the photocatalytic water splitting performance.It is believed that our work not only rationally controls the nanostructure,but also introduces useful heteroatom into the matrix of photocatalyst,which provides an effective way to design high-efficiency g-C_(3)N_(4) photocatalyst.展开更多
Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagn...Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagnetic field in rocket-triggered lightning and tower-initiated lightning discharges; available channel base current data recorded in rocket-triggered lightning are also used. The negative leaders propagate in a stepped fashion accompanied by many branches. The stems ahead of the negative leader tip determine the manner and direction of the leader propagation, and even the branching and winding of the lightning channel. The impulsive current, electromagnetic field, and related optical images suggest that the positive leader may develop in a step-like fashion at its initial stage of triggered lightning. However, the stepping processes of the positive leader are obviously different from those of the negative leader. Tower-initiated lightning revealed that the most conspicuous characteristics of the stepwise positive leader involve the intermittent brush-like corona zone in front of the leader tip and the luminosity enhancement of the channel behind the tip. In rockettriggered lightning flashes, the charge transferred during an individual step for the negative leader was nearly an order greater than for the positive counterpart. The successive streamers ahead of the leader tip are essential for both negative and positive leader propagation, and the stems could be formed from one or more streamers in the previous negative streamer zone with the main leader channel dim. High-resolution observation of tower lightning also revealed a new type of bidirectional recoil leader, with polarity contrary to the traditional one, traversing in negative channels associated with tower-initiated and rocket-triggered lightning.展开更多
Background:Patients with coronavirus disease 2019(COVID-19)have high resource utilization.Identifying the causes of severe COVID-19 is helpful for early intervention to reduce the consumption of medical resources.Meth...Background:Patients with coronavirus disease 2019(COVID-19)have high resource utilization.Identifying the causes of severe COVID-19 is helpful for early intervention to reduce the consumption of medical resources.Methods:We included 103 patients with COVID-19 in this single-center observational study.To evaluate the incidence,predictors,and effects of COVID-19,we analyzed demographic information,laboratory results,comorbidities,and vital signs as factors for association with severe COVID-19.Results:The incidence of severe COVID-19 was 16.5%and the percent poor outcome(including mortality,entering in ICU or transferred to a superior hospital)was 6.8%.The majority of severe COVID-19 patients had abnormal electrocardiogram(ECG)(82.35%),hypertension(76.47%)and other cardiac diseases(58.82%).Multivariate logistic regression was used to determine the predictors of severe illness.Abnormal body mass index(BMI)and ECG(P<0.05)were independent predictors of severe COVID-19.ECG abnormality was associated with increased odds of poor outcome(area under the receiver operating characteristic curves[AUC],0.793;P=0.010)and severe COVID-19(AUC,0.807;P<0.0001).Overweight was also associated with increased odds of poor outcome(AUC,0.728;P=0.045)and severe illness COVID-19(AUC,0.816;P<0.0001).Conclusion:Overweight and electrophysiological disorders on admission are important predictors of prognosis of patients with COVID-19.展开更多
Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials...Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.展开更多
As one of the low-cost energy storage systems,Na-ion batteries(NIBs)have received tremendous attention.However,the performance of current anode materials still cannot meet the requirements of NIBs.In our work,we obtai...As one of the low-cost energy storage systems,Na-ion batteries(NIBs)have received tremendous attention.However,the performance of current anode materials still cannot meet the requirements of NIBs.In our work,we obtain sulfur-doped interconnected carbon microspheres(S-CSs)via a simple hydrothermal method and subsequent sulfurizing treatment.Our S-CSs exhibit an ultrahigh reversible capacity of 520 mAh g^(-1) at 100 mA g^(-1) after 50 cycles and an excellent rate capability of 257 mAh g^(-1),even at a high current density of 2 A g^(-1).The density functional theory calculations demonstrate that sulfur doping in carbon favors the adsorption of Na atom during the sodiation process,which is accountable for the performance enhancement.Furthermore,we also utilize operando Raman spectroscopy to analyze the electrochemical reaction of our S-CSs,which further highlights the sulfur doping in improving Na-ion storage performance.展开更多
Emissions trading schemes(ETSs)have been a central component of international climate change policies,as a carbon pricing tool to achieve emissions reduction targets.Forest carbon offset credits have been leveraged in...Emissions trading schemes(ETSs)have been a central component of international climate change policies,as a carbon pricing tool to achieve emissions reduction targets.Forest carbon offset credits have been leveraged in many ETSs to efficiently meet emission reduction targets,yet there is little knowledge about the perceptions,experiences,and challenges associated with the forest carbon offsetting in existing and pilot ETS.Given that the future inclusion of forest carbon offset in ETS management activities and policies will require strong support and acceptability among the institutions and experts involved in ETS,this study explores the experiences and lessons learned with 16 globally engaging experts representing major existing ETSs(North America,Europe,and New Zealand)and Chinese pilot ETSs towards the inclusion of forestry offsets,major concerns and challenges with existing implementation models.Findings revealed that many respondents particularly from North America,New Zealand,and Chinese pilot systems portrayed positive attitudes toward the inclusion of forestry carbon offsets and its role in contributing to a viable ETS,while European experts were not supportive.Respondents cited leakage,permanence,additionality,and monitoring design features as the major challenges and concerns that inhibit the expansion and inclusion of forest carbon offsetting.Respondents from Chinese pilot schemes referenced a unique set of challenges related to implementation,including the increasing cost of afforestation and reforestation projects,the uncertainty in the future supply and demand for their national Certified Emissions Reduction(CER)scheme and landowner engagement.Existing and future ETSs should learn from and address the challenges experienced by global experts and carbon pricing mechanisms to design,evaluate,or enhance their forest carbon offset programs for an effective and viable system that successfully contributes to GHG mitigation practices globally.We recommend inclusion of forest carbon offsets at the early stages of ETS improves the perceptions and experience of policy makers and practitioners toward the success and potential of forestry offsets in ETS ensuring familiarity and confidence in the mechanism.展开更多
As one of the promising anode materials,iron selenide has received much attention for potassium-ion batteries(KIBs).Nevertheless,volume expansion and sluggish kinetics of iron selenide result in the poor reversibility...As one of the promising anode materials,iron selenide has received much attention for potassium-ion batteries(KIBs).Nevertheless,volume expansion and sluggish kinetics of iron selenide result in the poor reversibility and stability during potassiation–depotassiation process.In this work,we develop iron selenide composite matching ether-based electrolyte for KIBs,which presents a reversible specific capacity of 356 mAh g^(−1) at 200 mA g^(−1) after 75 cycles.According to the measurement of mechanical properties,it is found that iron selenide composite also exhibits robust and elastic solid electrolyte interphase layer in ether-based electrolyte,contributing to the improvement in reversibility and stability for KIBs.To further investigate the electrochemical enhancement mechanism of ether-based electrolyte in KIBs,we also utilize in situ visualization technique to monitor the potassiation–depotassiation process.For comparison,iron selenide composite matching carbonate-based electrolyte presents vast morphology change during potassiation–depotassiation process.When changing to ether-based electrolyte,a few minor morphology changes can be observed.This phenomenon indicates an occurrence of homogeneous electrochemical reaction in ether-based electrolyte,which results in a stable performance for potassium-ion(K-ion)storage.We believe that our work will provide a new perspective to visually monitor the potassium-ion storage process and guide the improvement in electrode material performance.展开更多
Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable ...Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable attention.However,the sodiation-desodiation process is still unclear.In our work,we obtain expanded graphite through slight modified Hummer's method and subsequent thermal treatment,which exhibits excellent cycling stability.Even at a high current density of 1 A g^(-1),our expanded graphite still remains a high reversible capacity of 100 mA h g^(-1) after 2600 cycles.Furthermore,we also investigate the electrochemical mechanism of our expanded graphite for Na-ion storage by operando Raman technique,which illuminate the electrochemical reaction during different sodiation-desodiation processes.展开更多
With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attra...With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attracted much attention and evolved significant development because of the low price,safety,and similar property compared with Li-ion batteries.Due to the high reversibility,stability,and low potential plateau,graphite becomes a current research focus and is regarded as one of the most promising KIB’s anode materials.In this review,we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for Kion storage.Besides,we summarize several kinds of methods to improve the performance of graphite for KIBs,including the design of graphite structure,selection of appropriate binder,solvent chemistry,and salt chemistry.Meanwhile,a concept of“relative energy density”is raised,which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential.In addition,we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.展开更多
Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to develo...Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to developing an FCO project,such as carbon leakage and cost-eff ectiveness.There have been few attempts to summarize and synthesize all types and aspects of existing challenges and possible solutions for FCO projects.This paper systematically reviews and discusses the current challenges involved in developing FCO projects,and then draws on the experience and lessons of existing projects to show how those challenges were addressed in world-leading voluntary carbon standards,namely the Verifi ed Carbon Standard,the American Carbon Registry,the Climate Action Reserve,and Plan Vivo.These voluntary markets have rich experience in FCO projects and are responsible for a signifi cant share of the market.From the 53 publications used in this analysis,three broad thematic categories of challenges emerged.These were related to methodology,socio-economic implications,and implementation.Methodological challenges,particularly additionality,permanence,and leakage,were the focus of 46%of the selected research papers,while socio-economic challenges,including transaction,social,and opportunity costs,were addressed by 35%.The remaining 19%of the research articles focused on implementational challenges related to monitoring,reporting,and verifi cation.Major voluntary standards adequately addressed most of the methodological and implementational barriers by adopting various approaches.However,the standards did not adequately address socio-economic issues,despite these being the second most frequently discussed theme in the papers analyzed.More research is clearly needed on the socio-economic challenges involved in the development of FCO projects.For the development of high-quality forestry carbon off set projects,there are many challenges and no simple,universal recipe for addressing them.However,it is crucial to build upon the current science and move forward with carbon projects which ensure eff ective,long-term carbon sinks and maximize benefi ts for biodiversity and people;this is particularly important with a growing public and private interest in this fi eld.展开更多
The slow reaction kinetics,combined with the relatively large radius of K-ion,makes it challenging to develop acceptable electrode materials for reversible insertion/deinsertion of potassium ions,thus reducing the cyc...The slow reaction kinetics,combined with the relatively large radius of K-ion,makes it challenging to develop acceptable electrode materials for reversible insertion/deinsertion of potassium ions,thus reducing the cycle stability and reversible capacity of aqueous potassium-ion batteries(PIBs)[1].Given this,there is still a long way to go in developing high-performance electrode materials for PIBs with a stable cycle life and high energy density.According to a literature study on PIB electrode materials,the electrochemical performance of cathode materials can be easily achieved through various structural modifications[2–4].Nevertheless,the study of cathode material optimization and operating mechanisms is insufficient,hindering the energy density of PIBs from reaching a satisfactory level.In this context,the performance of cathode material becomes the decisive factor for the performance of PIBs.展开更多
We conducted a randomized,open-label,parallel-controlled,multicenter trial on the use of Shuanghuanglian(SHL),a traditional Chinese patent medicine,in treating cases of COVID-19.A total of 176 patients received SHL by...We conducted a randomized,open-label,parallel-controlled,multicenter trial on the use of Shuanghuanglian(SHL),a traditional Chinese patent medicine,in treating cases of COVID-19.A total of 176 patients received SHL by three doses(56 in low dose,61 in middle dose,and 59 in high dose)in addition to standard care.The control group was composed of 59 patients who received standard therapy alone.Treatment with SHL was not associated with a difference from standard care in the time to disease recovery.Patients with 14-day SHL treatment had significantly higher rate in negative conversion of SARS-CoV-2 in nucleic acid swab tests than the patients from the control group(93.4%vs.73.9%,P=0.006).Analysis of chest computed tomography images showed that treatment with high-dose SHL significantly promoted absorption of inflammatory focus of pneumonia,which was evaluated by density reduction of inflammatory focus from baseline,at day 7(mean difference(95%CI),−46.39(−86.83 to−5.94)HU;P=0.025)and day 14(mean difference(95%CI),−74.21(−133.35 to−15.08)HU;P=0.014).No serious adverse events occurred in the SHL groups.This study illustrated that SHL in combination with standard care was safe and partially effective for the treatment of COVID-19.展开更多
High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However...High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However,common spin-coated TiO^(2)ETLs endow many surface defects and have strong UV photocatalytic effect to decompose perovskite materials,resulting in inferior stability of devices.In this work,TiO^(2)bilayer film(Bi-TiO^(2))has been fabricated by combining spin-coating and atomic-layer-deposition process and its positive effects on UV stability and Idarkof Cs2 AgBiBr6-based PDs have been revealed for the first time.It is demonstrated that Bi-TiO^(2)possesses fewer surface defects and smoother morphology with type II band alignment,which is beneficial to suppress photocatalytic activity of TiO^(2)and reduce carrier recombination at the interface.After accelerated strong UV aging treatment,the PD with Bi-TiO^(2)maintains excellent performance,whereas the PD with spin-coated TiO^(2)film dramatically deteriorate with on-off ratio drops from~102 to~2.Besides,the Idarkof PD remarkably decreases from~10^(-8) A to~10^(-10) A after bilayer optimization.Furthermore,we have integrated the corresponding PDs into a self-built imaging system adopting diffuse reflection mode.This work suggests a feasible approach to fabricate TiO^(2)/Cs2 AgBiBr6-based PDs with remarkable UV tolerance for imaging applications.展开更多
There is no doubt that COVID-19 outbreak is currently the biggest public health threat,which has caused catastrophic con sequences in many countries and regions.As host immunity is key to fighting against virus infect...There is no doubt that COVID-19 outbreak is currently the biggest public health threat,which has caused catastrophic con sequences in many countries and regions.As host immunity is key to fighting against virus infection,it is important to characterize the immunologic changes in the COVID-19 patients,and to explore potential therapeutic candidates.The most efficient ways to end this pandemic are to vaccinate the susceptible population,and to use specific drugs,such as monoclonal antibodies against the viral spike protein(S protein),to treat the affected individuals.Several promising neutralizing antibodies have recently been reported(Cao et al.,2020;Lv et al.,2020).展开更多
Recently,Coordination Polymers(CPs)have been widely utilized as energy storage materials for reversible Lithium-Ion Batteries(LIBs)benefiting from their tunable building blocks and adjusted electrochemical properties....Recently,Coordination Polymers(CPs)have been widely utilized as energy storage materials for reversible Lithium-Ion Batteries(LIBs)benefiting from their tunable building blocks and adjusted electrochemical properties.However,the unsatisfied electrochemical behavior of CPs with poor conductivity and sluggish ion transport kinetics is still a bottle-neck for their large-scale energy storage applications in LIBs.Herein,we display the rational fabrication of a conductive Sn-based coordination polymer(Sn-DHTPA)via judiciously choosing suitable building units.The Sn-DHTPA is employed as anode for LIBs,exhibiting superior reversible storage capacity of 1142.6 m A h g^(-1) at 0.1 A g^(-1) after 100 cycles and impressive rate storage capability of 287.7 m A h g^(-1)at 20 A g^(-1).More importantly,a robust cycling performance of 205.5 m A h g^(-1) at an extra-high current density of 20 A g^(-1) are observed without remarkable capacity-fading up to1000 cycles.The behavior superiority of Sn-DHTPA is related to its advanced architecture with abundant lithium storage sites,high electrical conductivity and rapid lithium transport.A series of ex-situ characterizations reveal that the impressive lithium storage capacity is contributed by the redox active sites of both the aromatic linker and metal center related to in-situ generated metallic nanoparticles dispersed in the skeleton.展开更多
As an advanced combat weapon,Unmanned Aerial Vehicles(UAVs)have been widely used in military wars.In this paper,we formulated the Autonomous Navigation Control(ANC)problem of UAVs as a Markov Decision Process(MDP)and ...As an advanced combat weapon,Unmanned Aerial Vehicles(UAVs)have been widely used in military wars.In this paper,we formulated the Autonomous Navigation Control(ANC)problem of UAVs as a Markov Decision Process(MDP)and proposed a novel Deep Reinforcement Learning(DRL)method to allow UAVs to perform dynamic target tracking tasks in large-scale unknown environments.To solve the problem of limited training experience,the proposed Imaginary Filtered Hindsight Experience Replay(IFHER)generates successful episodes by reasonably imagining the target trajectory in the failed episode to augment the experiences.The welldesigned goal,episode,and quality filtering strategies ensure that only high-quality augmented experiences can be stored,while the sampling filtering strategy of IFHER ensures that these stored augmented experiences can be fully learned according to their high priorities.By training in a complex environment constructed based on the parameters of a real UAV,the proposed IFHER algorithm improves the convergence speed by 28.99%and the convergence result by 11.57%compared to the state-of-the-art Twin Delayed Deep Deterministic Policy Gradient(TD3)algorithm.The testing experiments carried out in environments with different complexities demonstrate the strong robustness and generalization ability of the IFHER agent.Moreover,the flight trajectory of the IFHER agent shows the superiority of the learned policy and the practical application value of the algorithm.展开更多
基金supported by the faculty startup funds from the Yangzhou Universitythe Natural Science Foundation of Jiangsu Province(BK20210821)+1 种基金the National Natural Science Foundation of China(22102141)the Lvyangjinfeng Talent Program of Yangzhou。
文摘Developing efficient energy storage for sodium-ion batteries(SIBs)by creating high-performance heterojunctions and understanding their interfacial interaction at the atomic/molecular level holds promise but is also challenging.Besides,sluggish reaction kinetics at low temperatures restrict the operation of SIBs in cold climates.Herein,cross-linking nanoarchitectonics of WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,featuring built-in electric field(BIEF),have been developed,employing as a model to reveal the positive effect of heterojunction design and BIEF for modifying the reaction kinetics and electrochemical activity.Particularly,the theoretical analysis manifests the discrepancy in work functions leads to the electronic flow from the electron-rich Ti_(3)C_(2)T_(x) to layered WS_(2),spontaneously forming the BIEF and“ion reservoir”at the heterogeneous interface.Besides,the generation of cross-linking pathways further promotes the transportation of electrons/ions,which guarantees rapid diffusion kinetics and excellent structure coupling.Consequently,superior sodium storage performance is obtained for the WS_(2)/Ti_(3)C_(2)T_(x) heterojunction,with only 0.2%decay per cycle at 5.0 A g^(-1)(25℃)up to 1000 cycles and a high capacity of 293.5 mA h g^(-1)(0.1A g^(-1)after 100 cycles)even at-20℃.Importantly,the spontaneously formed BIEF,accompanied by“ion reservoir”,in heterojunction provides deep understandings of the correlation between structure fabricated and performance obtained.
基金supported by the Chinese Police OfficeSichuan Police OfficeYunnan Police Office
文摘Previous studies have suggested that the incidence of post-traumatic stress disorder in earthquake rescue workers is relatively high. Risk factors for this disorder include demographic characteristics, earthquake-related high-risk factors, risk factors in the rescue process, personality, social support and coping style. This study examined the current status of a unit of 1 040 rescue workers who participated in earthquake relief for the Wenchuan earthquake that occurred on May 12th, 2008. Post-traumatic stress disorder was diagnosed primarily using the Clinician-Administered Post-traumatic Stress Disorder Scale during structured interviews. Univariate and multivariate sta-tistical analyses were used to examine major risk factors that contributed to the incidence of post-traumatic stress disorder. Results revealed that the incidence of this disorder in the rescue group was 5.96%. The impact factors in univariate analysis included death of family members, contact with corpses or witnessing of the deceased or seriously injured, near-death experience, severe injury or mental trauma in the rescue process and working at the epicenter of the earthquake. Correlation analysis suggested that post-traumatic stress disorder was positively correlated with psychotic and neurotic personalities, negative coping and low social support. Impact factors in mul-tivariate logistic regression analysis included near-death experience, severe injury or mental trauma, working in the epicenter of the rescue, neurotic personality, negative coping and low social support, among which low social support had the largest odds ratio of 20.42. Findings showed that the oc-currence of post-traumatic stress disorder was the result of the interaction of multiple factors.
基金financially supported by the Key-Area Research and Development Program of Guangdong Province(2019B010937001)the National Natural Science Foundation of China(50702022,51577070,51702056 and U1601208)+1 种基金Natural Science Foundation of Guangdong Province(2019A1515012129)Science and Technology Planning Project of Guangdong Province(2016B090932005)。
文摘Currently,photocatalytic water splitting is regarded as promising technology in renewable energy generation.However,the conversion efficiency suffers great restriction due to the rapid recombination of charge carriers.Rational designed the structure and doping elements become important alternative routes to improve the performance of photocatalyst.In this work,we rational designed oxygen-doped graphitic carbon nitride(OCN)nanotubes derived from supermolecular intermediates for photocata lytic water splitting.The as prepared OCN nanotubes exhibit an outstanding hydrogen evolution rate of 73.84μmol h^(-1),outperforming the most of reported one dimensional(1D)g-C_(3)N_(4) previously.Due to the rational oxygen doping,the band structure of g-C_(3)N_(4) is meliorated,which can narrow the band gap and reduce the recombination rate of photogene rated carriers.Furthermore,the hollow nanotube structure of OCN also provide multiple diffuse reflection during photocata lytic reaction,which can significantly promote the utilization capacity of visible light and enhance the photocatalytic water splitting performance.It is believed that our work not only rationally controls the nanostructure,but also introduces useful heteroatom into the matrix of photocatalyst,which provides an effective way to design high-efficiency g-C_(3)N_(4) photocatalyst.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41630425, 41761144074)
文摘Leader propagation is a fundamental issue in lightning physics. The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagnetic field in rocket-triggered lightning and tower-initiated lightning discharges; available channel base current data recorded in rocket-triggered lightning are also used. The negative leaders propagate in a stepped fashion accompanied by many branches. The stems ahead of the negative leader tip determine the manner and direction of the leader propagation, and even the branching and winding of the lightning channel. The impulsive current, electromagnetic field, and related optical images suggest that the positive leader may develop in a step-like fashion at its initial stage of triggered lightning. However, the stepping processes of the positive leader are obviously different from those of the negative leader. Tower-initiated lightning revealed that the most conspicuous characteristics of the stepwise positive leader involve the intermittent brush-like corona zone in front of the leader tip and the luminosity enhancement of the channel behind the tip. In rockettriggered lightning flashes, the charge transferred during an individual step for the negative leader was nearly an order greater than for the positive counterpart. The successive streamers ahead of the leader tip are essential for both negative and positive leader propagation, and the stems could be formed from one or more streamers in the previous negative streamer zone with the main leader channel dim. High-resolution observation of tower lightning also revealed a new type of bidirectional recoil leader, with polarity contrary to the traditional one, traversing in negative channels associated with tower-initiated and rocket-triggered lightning.
基金supported by the scientific research project approved by Heilongjiang Provincial Health Committee in 2019(2019-253).
文摘Background:Patients with coronavirus disease 2019(COVID-19)have high resource utilization.Identifying the causes of severe COVID-19 is helpful for early intervention to reduce the consumption of medical resources.Methods:We included 103 patients with COVID-19 in this single-center observational study.To evaluate the incidence,predictors,and effects of COVID-19,we analyzed demographic information,laboratory results,comorbidities,and vital signs as factors for association with severe COVID-19.Results:The incidence of severe COVID-19 was 16.5%and the percent poor outcome(including mortality,entering in ICU or transferred to a superior hospital)was 6.8%.The majority of severe COVID-19 patients had abnormal electrocardiogram(ECG)(82.35%),hypertension(76.47%)and other cardiac diseases(58.82%).Multivariate logistic regression was used to determine the predictors of severe illness.Abnormal body mass index(BMI)and ECG(P<0.05)were independent predictors of severe COVID-19.ECG abnormality was associated with increased odds of poor outcome(area under the receiver operating characteristic curves[AUC],0.793;P=0.010)and severe COVID-19(AUC,0.807;P<0.0001).Overweight was also associated with increased odds of poor outcome(AUC,0.728;P=0.045)and severe illness COVID-19(AUC,0.816;P<0.0001).Conclusion:Overweight and electrophysiological disorders on admission are important predictors of prognosis of patients with COVID-19.
基金Financial support from National Natural Science Foundation of China(Nos.51702056 and 51772135)the Ministry of Education of China(6141A02022516)China Postdoctoral Science Foundation(2017M622902 and 2019T120790).
文摘Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:21617330National Natural Science Foundation of China,Grant/Award Numbers:21703081,51702056,51772135Ministry of Education of the People's Republic of China,Grant/Award Number:6141A02022516。
文摘As one of the low-cost energy storage systems,Na-ion batteries(NIBs)have received tremendous attention.However,the performance of current anode materials still cannot meet the requirements of NIBs.In our work,we obtain sulfur-doped interconnected carbon microspheres(S-CSs)via a simple hydrothermal method and subsequent sulfurizing treatment.Our S-CSs exhibit an ultrahigh reversible capacity of 520 mAh g^(-1) at 100 mA g^(-1) after 50 cycles and an excellent rate capability of 257 mAh g^(-1),even at a high current density of 2 A g^(-1).The density functional theory calculations demonstrate that sulfur doping in carbon favors the adsorption of Na atom during the sodiation process,which is accountable for the performance enhancement.Furthermore,we also utilize operando Raman spectroscopy to analyze the electrochemical reaction of our S-CSs,which further highlights the sulfur doping in improving Na-ion storage performance.
基金funded by the China Green Carbon Foundation and the Faculty of Forestry,University of British Columbia。
文摘Emissions trading schemes(ETSs)have been a central component of international climate change policies,as a carbon pricing tool to achieve emissions reduction targets.Forest carbon offset credits have been leveraged in many ETSs to efficiently meet emission reduction targets,yet there is little knowledge about the perceptions,experiences,and challenges associated with the forest carbon offsetting in existing and pilot ETS.Given that the future inclusion of forest carbon offset in ETS management activities and policies will require strong support and acceptability among the institutions and experts involved in ETS,this study explores the experiences and lessons learned with 16 globally engaging experts representing major existing ETSs(North America,Europe,and New Zealand)and Chinese pilot ETSs towards the inclusion of forestry offsets,major concerns and challenges with existing implementation models.Findings revealed that many respondents particularly from North America,New Zealand,and Chinese pilot systems portrayed positive attitudes toward the inclusion of forestry carbon offsets and its role in contributing to a viable ETS,while European experts were not supportive.Respondents cited leakage,permanence,additionality,and monitoring design features as the major challenges and concerns that inhibit the expansion and inclusion of forest carbon offsetting.Respondents from Chinese pilot schemes referenced a unique set of challenges related to implementation,including the increasing cost of afforestation and reforestation projects,the uncertainty in the future supply and demand for their national Certified Emissions Reduction(CER)scheme and landowner engagement.Existing and future ETSs should learn from and address the challenges experienced by global experts and carbon pricing mechanisms to design,evaluate,or enhance their forest carbon offset programs for an effective and viable system that successfully contributes to GHG mitigation practices globally.We recommend inclusion of forest carbon offsets at the early stages of ETS improves the perceptions and experience of policy makers and practitioners toward the success and potential of forestry offsets in ETS ensuring familiarity and confidence in the mechanism.
基金The authors thank the financial supports from the National Natural Science Foundation of China(51772135)the Fundamental Research Funds for the Central Universities(11619103,21621406)+1 种基金the Science and Technology Program of Guangzhou,China(202102020737,201605030008)the Shenzhen Science and Technology Program(JCYJ20200109113606007).We also thank Prof.Weiguang Xie and Dr.Haojie Lai for the measurement of AFM.
文摘As one of the promising anode materials,iron selenide has received much attention for potassium-ion batteries(KIBs).Nevertheless,volume expansion and sluggish kinetics of iron selenide result in the poor reversibility and stability during potassiation–depotassiation process.In this work,we develop iron selenide composite matching ether-based electrolyte for KIBs,which presents a reversible specific capacity of 356 mAh g^(−1) at 200 mA g^(−1) after 75 cycles.According to the measurement of mechanical properties,it is found that iron selenide composite also exhibits robust and elastic solid electrolyte interphase layer in ether-based electrolyte,contributing to the improvement in reversibility and stability for KIBs.To further investigate the electrochemical enhancement mechanism of ether-based electrolyte in KIBs,we also utilize in situ visualization technique to monitor the potassiation–depotassiation process.For comparison,iron selenide composite matching carbonate-based electrolyte presents vast morphology change during potassiation–depotassiation process.When changing to ether-based electrolyte,a few minor morphology changes can be observed.This phenomenon indicates an occurrence of homogeneous electrochemical reaction in ether-based electrolyte,which results in a stable performance for potassium-ion(K-ion)storage.We believe that our work will provide a new perspective to visually monitor the potassium-ion storage process and guide the improvement in electrode material performance.
基金financial supports from the National Natural Science Foundation of China (51702056, 51772135)the Ministry of Education of China (6141A02022516)+2 种基金the Fundamental Research Funds for the Central Universities (21617330)the China Postdoctoral Science Foundation (2017M622902, 2019T120790)GDHVPS (2017)。
文摘Currently,Na-ion battery(NIB) has become one of the most potential alternatives for Li-ion batteries due to the safety and low cost.As a promising anode for Na-ion storage,expanded graphite has attracted considerable attention.However,the sodiation-desodiation process is still unclear.In our work,we obtain expanded graphite through slight modified Hummer's method and subsequent thermal treatment,which exhibits excellent cycling stability.Even at a high current density of 1 A g^(-1),our expanded graphite still remains a high reversible capacity of 100 mA h g^(-1) after 2600 cycles.Furthermore,we also investigate the electrochemical mechanism of our expanded graphite for Na-ion storage by operando Raman technique,which illuminate the electrochemical reaction during different sodiation-desodiation processes.
基金supports from the National Natural Science Foundation of China(51772135,52002115)the Fundamental Research Funds for the Central Universities(21617330)Science and Technology Development Project of Henan Province(212102210487)。
文摘With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attracted much attention and evolved significant development because of the low price,safety,and similar property compared with Li-ion batteries.Due to the high reversibility,stability,and low potential plateau,graphite becomes a current research focus and is regarded as one of the most promising KIB’s anode materials.In this review,we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for Kion storage.Besides,we summarize several kinds of methods to improve the performance of graphite for KIBs,including the design of graphite structure,selection of appropriate binder,solvent chemistry,and salt chemistry.Meanwhile,a concept of“relative energy density”is raised,which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential.In addition,we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.
基金funded by Zhejiang A&F University(POAU GR022067)China Green Carbon Foundation(PAFD GR015155)。
文摘Forest carbon offset(FCO)projects play an increasingly important role in mitigating climate change through market mechanisms in both compliance and voluntary markets.However,there are challenges and barriers to developing an FCO project,such as carbon leakage and cost-eff ectiveness.There have been few attempts to summarize and synthesize all types and aspects of existing challenges and possible solutions for FCO projects.This paper systematically reviews and discusses the current challenges involved in developing FCO projects,and then draws on the experience and lessons of existing projects to show how those challenges were addressed in world-leading voluntary carbon standards,namely the Verifi ed Carbon Standard,the American Carbon Registry,the Climate Action Reserve,and Plan Vivo.These voluntary markets have rich experience in FCO projects and are responsible for a signifi cant share of the market.From the 53 publications used in this analysis,three broad thematic categories of challenges emerged.These were related to methodology,socio-economic implications,and implementation.Methodological challenges,particularly additionality,permanence,and leakage,were the focus of 46%of the selected research papers,while socio-economic challenges,including transaction,social,and opportunity costs,were addressed by 35%.The remaining 19%of the research articles focused on implementational challenges related to monitoring,reporting,and verifi cation.Major voluntary standards adequately addressed most of the methodological and implementational barriers by adopting various approaches.However,the standards did not adequately address socio-economic issues,despite these being the second most frequently discussed theme in the papers analyzed.More research is clearly needed on the socio-economic challenges involved in the development of FCO projects.For the development of high-quality forestry carbon off set projects,there are many challenges and no simple,universal recipe for addressing them.However,it is crucial to build upon the current science and move forward with carbon projects which ensure eff ective,long-term carbon sinks and maximize benefi ts for biodiversity and people;this is particularly important with a growing public and private interest in this fi eld.
基金supported by the Natural Science Foundation of Jiangsu Province(BK20210821)Science and Technology Program of Guangzhou(202102020737)Shenzhen Science and Technology Program(JCYJ20200109113606007).
文摘The slow reaction kinetics,combined with the relatively large radius of K-ion,makes it challenging to develop acceptable electrode materials for reversible insertion/deinsertion of potassium ions,thus reducing the cycle stability and reversible capacity of aqueous potassium-ion batteries(PIBs)[1].Given this,there is still a long way to go in developing high-performance electrode materials for PIBs with a stable cycle life and high energy density.According to a literature study on PIB electrode materials,the electrochemical performance of cathode materials can be easily achieved through various structural modifications[2–4].Nevertheless,the study of cathode material optimization and operating mechanisms is insufficient,hindering the energy density of PIBs from reaching a satisfactory level.In this context,the performance of cathode material becomes the decisive factor for the performance of PIBs.
基金This work was supported by the National Key R&D Program of China(No.2020YFC0841400)Tongji Hospital Clinical Research Project(Nos.XXGZBDYJ009 and 2019YBKY019).
文摘We conducted a randomized,open-label,parallel-controlled,multicenter trial on the use of Shuanghuanglian(SHL),a traditional Chinese patent medicine,in treating cases of COVID-19.A total of 176 patients received SHL by three doses(56 in low dose,61 in middle dose,and 59 in high dose)in addition to standard care.The control group was composed of 59 patients who received standard therapy alone.Treatment with SHL was not associated with a difference from standard care in the time to disease recovery.Patients with 14-day SHL treatment had significantly higher rate in negative conversion of SARS-CoV-2 in nucleic acid swab tests than the patients from the control group(93.4%vs.73.9%,P=0.006).Analysis of chest computed tomography images showed that treatment with high-dose SHL significantly promoted absorption of inflammatory focus of pneumonia,which was evaluated by density reduction of inflammatory focus from baseline,at day 7(mean difference(95%CI),−46.39(−86.83 to−5.94)HU;P=0.025)and day 14(mean difference(95%CI),−74.21(−133.35 to−15.08)HU;P=0.014).No serious adverse events occurred in the SHL groups.This study illustrated that SHL in combination with standard care was safe and partially effective for the treatment of COVID-19.
基金financial supports from National Natural Science Foundation of China(51772135)the Ministry of Education of China(6141A02022516)+4 种基金the Fundamental Research Funds for the Central Universities(11619103)the China Postdoctoral Science Foundation(2019M663376)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2017A020215135 and2018A030310659)Guangdong Basic and Applied Basic Research Foundation(2020A1515011377)the Science and Technology Program of Guangzhou,China(Grant No.201804010432)。
文摘High ultraviolet(UV)stability and low dark current(Idark)are necessary for high-quality perovskite photodetectors(PDs).TiO^(2)thin film is known as effective electron-transport-layer(ETL)for perovskite devices.However,common spin-coated TiO^(2)ETLs endow many surface defects and have strong UV photocatalytic effect to decompose perovskite materials,resulting in inferior stability of devices.In this work,TiO^(2)bilayer film(Bi-TiO^(2))has been fabricated by combining spin-coating and atomic-layer-deposition process and its positive effects on UV stability and Idarkof Cs2 AgBiBr6-based PDs have been revealed for the first time.It is demonstrated that Bi-TiO^(2)possesses fewer surface defects and smoother morphology with type II band alignment,which is beneficial to suppress photocatalytic activity of TiO^(2)and reduce carrier recombination at the interface.After accelerated strong UV aging treatment,the PD with Bi-TiO^(2)maintains excellent performance,whereas the PD with spin-coated TiO^(2)film dramatically deteriorate with on-off ratio drops from~102 to~2.Besides,the Idarkof PD remarkably decreases from~10^(-8) A to~10^(-10) A after bilayer optimization.Furthermore,we have integrated the corresponding PDs into a self-built imaging system adopting diffuse reflection mode.This work suggests a feasible approach to fabricate TiO^(2)/Cs2 AgBiBr6-based PDs with remarkable UV tolerance for imaging applications.
基金This work was funded by the National Natural Science Foundation of China(Nos.61822108,62041102 and 62032007 to Q.J.)the Emergency Research Project for COVID-19 of Harbin Institute of Technology(No.2020-001 to Q.J.)the Scientific Research Project Approved by Heilongjiang Provincial Health Committee(No.2019-253 to J.L.).
文摘There is no doubt that COVID-19 outbreak is currently the biggest public health threat,which has caused catastrophic con sequences in many countries and regions.As host immunity is key to fighting against virus infection,it is important to characterize the immunologic changes in the COVID-19 patients,and to explore potential therapeutic candidates.The most efficient ways to end this pandemic are to vaccinate the susceptible population,and to use specific drugs,such as monoclonal antibodies against the viral spike protein(S protein),to treat the affected individuals.Several promising neutralizing antibodies have recently been reported(Cao et al.,2020;Lv et al.,2020).
基金financially supported by National Natural Science Foundation of China(51702056)Fundamental Research Funds for the Central Universities(2162140621617330)+2 种基金Science and Technology Program of Guangzhou(202102020737,201605030008)Provincial Natural Science Foundation of Anhui(1908085ME120)Primary Research and Development Program of Anhui Province(201904a05020087)。
文摘Recently,Coordination Polymers(CPs)have been widely utilized as energy storage materials for reversible Lithium-Ion Batteries(LIBs)benefiting from their tunable building blocks and adjusted electrochemical properties.However,the unsatisfied electrochemical behavior of CPs with poor conductivity and sluggish ion transport kinetics is still a bottle-neck for their large-scale energy storage applications in LIBs.Herein,we display the rational fabrication of a conductive Sn-based coordination polymer(Sn-DHTPA)via judiciously choosing suitable building units.The Sn-DHTPA is employed as anode for LIBs,exhibiting superior reversible storage capacity of 1142.6 m A h g^(-1) at 0.1 A g^(-1) after 100 cycles and impressive rate storage capability of 287.7 m A h g^(-1)at 20 A g^(-1).More importantly,a robust cycling performance of 205.5 m A h g^(-1) at an extra-high current density of 20 A g^(-1) are observed without remarkable capacity-fading up to1000 cycles.The behavior superiority of Sn-DHTPA is related to its advanced architecture with abundant lithium storage sites,high electrical conductivity and rapid lithium transport.A series of ex-situ characterizations reveal that the impressive lithium storage capacity is contributed by the redox active sites of both the aromatic linker and metal center related to in-situ generated metallic nanoparticles dispersed in the skeleton.
基金co-supported by the National Natural Science Foundation of China(Nos.62003267 and 61573285)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2020JQ-220)+1 种基金the Open Project of Science and Technology on Electronic Information Control Laboratory,China(No.JS20201100339)the Open Project of Science and Technology on Electromagnetic Space Operations and Applications Laboratory,China(No.JS20210586512).
文摘As an advanced combat weapon,Unmanned Aerial Vehicles(UAVs)have been widely used in military wars.In this paper,we formulated the Autonomous Navigation Control(ANC)problem of UAVs as a Markov Decision Process(MDP)and proposed a novel Deep Reinforcement Learning(DRL)method to allow UAVs to perform dynamic target tracking tasks in large-scale unknown environments.To solve the problem of limited training experience,the proposed Imaginary Filtered Hindsight Experience Replay(IFHER)generates successful episodes by reasonably imagining the target trajectory in the failed episode to augment the experiences.The welldesigned goal,episode,and quality filtering strategies ensure that only high-quality augmented experiences can be stored,while the sampling filtering strategy of IFHER ensures that these stored augmented experiences can be fully learned according to their high priorities.By training in a complex environment constructed based on the parameters of a real UAV,the proposed IFHER algorithm improves the convergence speed by 28.99%and the convergence result by 11.57%compared to the state-of-the-art Twin Delayed Deep Deterministic Policy Gradient(TD3)algorithm.The testing experiments carried out in environments with different complexities demonstrate the strong robustness and generalization ability of the IFHER agent.Moreover,the flight trajectory of the IFHER agent shows the superiority of the learned policy and the practical application value of the algorithm.