Wide bandgap perovskite solar cells(PSCs)have attracted significant attention because they can be applied to the top cells of tandem solar cells.However,high open-circuit voltage(V_(OC))deficit(>0.4 V)result from p...Wide bandgap perovskite solar cells(PSCs)have attracted significant attention because they can be applied to the top cells of tandem solar cells.However,high open-circuit voltage(V_(OC))deficit(>0.4 V)result from poor crystallization and high non-radiative recombination losses become a serious limitation in the pursuit of high performance.Here,the relevance between different Pbl_(2)proportions and performance parameters are revealed through analysis of surface morphology,residual stress,and photostability.The increase of Pbl_(2)proportion promotes crystal growth and reduces the work function of the perovskite film surface and promotes the energy level alignment with the carrier transport layer,which decreased the V_(OC)deficit.However,residual PbI_(2)exacerbated the stress level of perovskite film,and the resulting lattice disorder deteriorated the photostability of the device.Ultimately,after the synergistic passivation of residual PbI_(2)and PEAI,the V_(OC)achieves 1.266 V and V_(OC)deficit is less than 0.4 V,the record value in wide bandgap PSCs.展开更多
Patients with locally advanced hepatocellular cancer(HCC)and portal vein tumor thrombosis(PVTT)have a dismal prognosis since limited treatment options are available for them.In recent years,effective systemic therapy,...Patients with locally advanced hepatocellular cancer(HCC)and portal vein tumor thrombosis(PVTT)have a dismal prognosis since limited treatment options are available for them.In recent years,effective systemic therapy,and advances in the understanding of technicalities and effectiveness of ablative therapies especially radiotherapy,have given some hope to prolong survival in them.This review summarized recent evidence in literature regarding the possible role of liver resection(LR)and liver transplantation(LT)in patients with locally advanced HCC and PVTT with no extrahepatic disease.Downstaging therapies have helped make curative resection or LT a reality in selected patients.This review emphasizes on the key points to focus on when considering surgery in these patients,who are usually relegated to palliative systemic therapy alone.Meticulous patient selection based on tumor biology,documented downstaging based on imaging and decrease in tumor marker levels,and an adequate waiting period to demonstrate stable disease,may help obtain satisfactory long-term outcomes post LR or LT in an intention to treat strategy in patients with HCC and PVTT.展开更多
BACKGROUND Mesenchymal stem cells(MSCs)as living biopharmaceuticals with unique properties,i.e.,stemness,viability,phenotypes,paracrine activity,etc.,need to be administered such that they reach the target site,mainta...BACKGROUND Mesenchymal stem cells(MSCs)as living biopharmaceuticals with unique properties,i.e.,stemness,viability,phenotypes,paracrine activity,etc.,need to be administered such that they reach the target site,maintaining these properties unchanged and are retained at the injury site to participate in the repair process.Route of delivery(RoD)remains one of the critical determinants of safety and efficacy.This study elucidates the safety and effectiveness of different RoDs of MSC treatment in heart failure(HF)based on phase II randomized clinical trials(RCTs).We hypothesize that the RoD modulates the safety and efficacy of MSCbased therapy and determines the outcome of the intervention.AIM To investigate the effect of RoD of MSCs on safety and efficacy in HF patients.METHODS RCTs were retrieved from six databases.Safety endpoints included mortality and serious adverse events(SAEs),while efficacy outcomes encompassed changes in left ventricular ejection fraction(LVEF),6-minute walk distance(6MWD),and pro-B-type natriuretic peptide(pro-BNP).Subgroup analyses on RoD were performed for all study endpoints.RESULTS Twelve RCTs were included.Overall,MSC therapy demonstrated a significant decrease in mortality[relative risk(RR):0.55,95%confidence interval(95%CI):0.33-0.92,P=0.02]compared to control,while SAE outcomes showed no significant difference(RR:0.84,95%CI:0.66-1.05,P=0.11).RoD subgroup analysis revealed a significant difference in SAE among the transendocardial(TESI)injection subgroup(RR=0.71,95%CI:0.54-0.95,P=0.04).The pooled weighted mean difference(WMD)demonstrated an overall significant improvement of LVEF by 2.44%(WMD:2.44%,95%CI:0.80-4.29,P value≤0.001),with only intracoronary(IC)subgroup showing significant improvement(WMD:7.26%,95%CI:5.61-8.92,P≤0.001).Furthermore,the IC delivery route significantly improved 6MWD by 115 m(WMD=114.99 m,95%CI:91.48-138.50),respectively.In biochemical efficacy outcomes,only the IC subgroup showed a significant reduction in pro-BNP by-860.64 pg/mL(WMD:-860.64 pg/Ml,95%CI:-944.02 to-777.26,P=0.001).CONCLUSION Our study concluded that all delivery methods of MSC-based therapy are safe.Despite the overall benefits in efficacy,the TESI and IC routes provided better outcomes than other methods.Larger-scale trials are warranted before implementing MSC-based therapy in routine clinical practice.展开更多
In his 50 years of practice,he has performed more than 20,000 hepatopancreatobiliary surgeries,being the first one to propose the concept of the“auxiliary partial orthotopic liver transplantation”internationally.Fur...In his 50 years of practice,he has performed more than 20,000 hepatopancreatobiliary surgeries,being the first one to propose the concept of the“auxiliary partial orthotopic liver transplantation”internationally.Furthermore,he developed the“Chen's inserting biliary-enteric anastomosis and pancreato-enteric anastomosis,”“Chen's hepatic vascular occlusion,”“Chen's liver double-hanging maneuver,”and“Chen's hepatic vascular occlusion without liver portal dissection.”He also popularized these theories and techniques both in China and worldwide.His name is Xiao-Ping Chen,an academician of the Chinese Academy of Sciences and honorary president of the Tongji Medical College of Huazhong University of Science and Technology.展开更多
With the rise of live streaming on social media, platforms like Facebook, Instagram, and YouTube have become powerful business tools. They enable users to share live videos, fostering direct connections between busine...With the rise of live streaming on social media, platforms like Facebook, Instagram, and YouTube have become powerful business tools. They enable users to share live videos, fostering direct connections between businesses and their customers. This critical literature review paper explores the impact of live streaming on businesses, focusing on its role in attracting and satisfying consumers by promoting products tailored to their needs and wants. It emphasizes live streaming’s crucial role in engaging customers, a key to business growth. The study also provides viable strategies for businesses to leverage live streaming for growth and customer engagement, underscoring its importance in the business landscape.展开更多
A t-container Ct(u,v)is a set of t internally disjoint paths between two distinct vertices u and v in a graph G,i.e.,Ct(u,v)={P_(1),P_(2),···,Pt}.Moreover,if V(P_(1))∪V(P_(2))∪···∪V(Pt...A t-container Ct(u,v)is a set of t internally disjoint paths between two distinct vertices u and v in a graph G,i.e.,Ct(u,v)={P_(1),P_(2),···,Pt}.Moreover,if V(P_(1))∪V(P_(2))∪···∪V(Pt)=V(G)then Ct(u,v)is called a spanning t-container,denoted by C_(t)^(sc)(u,v).The length of C_(t)^(sc)(u,v)={P_(1),P_(2),···,Pt}is l(C_(t)^(sc)(u,v))=max{l(P_(i))|1≤i≤t}.A graph G is spanning t-connected if there exists a spanning t-container between any two distinct vertices u and v in G.Assume that u and v are two distinct vertices in a spanning t-connected graph G.Let D_(t)^(sc)(u,v)be the collection of all C_(t)^(sc)(u,v)’s.Define the spanning t-wide distance between u and v in G,d_(t)^(sc)(u,v)=min{l(C_(t)^(sc)(u,v))|C_(t)^(sc)(u,v)∈D_(t)^(sc)(u,v)},and the spanning t-wide diameter of G,D_(t)^(sc)(G)=max{d_(t)^(sc)(u,v)|u,v∈V(G)}.In particular,the spanning wide diameter of G is D_(κ)^(sc)(G),whereκis the connectivity of G.In the paper we provide the upper and lower bounds of the spanning wide diameter of a graph,and show that the bounds are best possible.We also determine the exact values of wide diameters of some well known graphs including Harary graphs and generalized Petersen graphs et al..展开更多
Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues...Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues under extreme conditions are the main challenges for the practical application.With the expansion of human activities,such as space missions,polar exploration,and so on,the investigation of SSC with wide temperature tolerance,high energy density,power density,and sustainability is highly desired.In this review,the effects of temperature on SSC are systematically illustrated and clarified,including the properties of the electrolyte,ion diffusion,and reaction dynamics of the supercapacitor.Subsequently,we summarize the recent advances in wide-temperature-range SSCs from the aspect of electrolyte modification,electrode design,and interface adjustment between electrode and electrolyte,especially with critical concerns on ionic conductivity and cycling stability.In the end,a perspective is presented,expecting to promote the practical application of the SSC in harsh conditions.展开更多
Implementation of the BRI projects has heralded positive changes in the lives of Tanzanian people Tanzania is an important Belt and Road Initiative(BRI)hub in Africa.It signed a BRI cooperation memorandum with China i...Implementation of the BRI projects has heralded positive changes in the lives of Tanzanian people Tanzania is an important Belt and Road Initiative(BRI)hub in Africa.It signed a BRI cooperation memorandum with China in 2018.Bilateral exchanges have been on the rise since then.On the occasion of the 10th anniversary of the launch of the initiative,ChinAfrica sat down with Mbelwa Kairuki,Tanzanian ambassador to China,to hear his insights on the BRI,especially the changes brought by the BRI to the local people’s lives.展开更多
Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovski...Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be obtained.The 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases perovskite grain size,retards halide segregation,and accelerates hole extraction.The surface functionalization achieves a high power conversion efficiency(PCE)of 17.62%for a single-junction wide-bandgap(~1.77 e V)PSC.We also demonstrate a monolithic all-perovskite tandem solar cell using surfaceengineered HSC,showing high PCE of 24.66%with large open-circuit voltage of 2.008 V and high fillfactor of 81.45%.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.展开更多
Li–CO_(2) batteries are considered promising energy storage systems in extreme environments such as Mars;however,severe performance degradation will occur at a subzero temperature owning to the sluggish reaction kine...Li–CO_(2) batteries are considered promising energy storage systems in extreme environments such as Mars;however,severe performance degradation will occur at a subzero temperature owning to the sluggish reaction kinetics.Herein,a photo-energized strategy adopting sustainable solar energy in wide working temperature range Li–CO_(2) battery was achieved with a binder-free MoS_(2)/carbon nanotube(CNT)photo-electrode as cathode.The unique layered structure and excellent photoelectric properties of MoS_(2) facilitate the abundant generation and rapid transfer of photo-excited carriers,which accelerate the CO_(2) reduction and Li_(2)CO_(3) decomposition upon illumination.The illuminated battery at room temperature exhibited high discharge voltage of 2.95 V and mitigated charge voltage of 3.27 V,attaining superior energy efficiency of 90.2%and excellent cycling stability of over 120 cycles.Even at an extremely low temperature of−30℃,the battery with same electrolyte can still deliver a small polarization of 0.45 V by the photoelectric and photothermal synergistic mechanism of MoS_(2)/CNT cathode.This work demonstrates the promising potential of the photo-energized wide working temperature range Li–CO_(2) battery in addressing the obstacle of charge overpotential and energy efficiency.展开更多
Herein,two asymmetric hexacyclic fused small molecule acceptors(SMAs),namely BP4F-HU and BP4F-UU,were synthesized.The elongated outside chains in the BP4F-UU molecule played a crucial role in optimizing the morphology...Herein,two asymmetric hexacyclic fused small molecule acceptors(SMAs),namely BP4F-HU and BP4F-UU,were synthesized.The elongated outside chains in the BP4F-UU molecule played a crucial role in optimizing the morphology of blend film,thereby improving charge mobility and reducing energy loss within the corresponding film.Notably,the PM6:BP4F-UU device exhibited a higher open-circuit voltage(V_(oc))of 0.878 V compared to the PM6:BP4F-HU device with a V_(oc)of 0.863 V.Further,a new wide bandgap SMA named BTP-TA was designed and synthesized as the third component to the PM6:BP4F-UU host binary devices,which showed an ideal complementary absorption spectrum in PM6:BP4F-UU system.In addition,BTP-TA can achieve efficient intermolecular energy transfer to BP4F-UU by fluorescence resonance energy transfer(FRET)pathway,due to the good overlap between the photoluminescence(PL)spectrum of BTP-TA and the absorption region of BP4F-UU.Consequently,ternary devices with 15wt%BTP-TA exhibits broader photon utilization,optimal blend morphology,and reduced charge recombination compared to the corresponding binary devices.Consequently,PM6:BP4F-UU:BTP-TA ternary device achieved an optimal power conversion efficiency(PCE)of 17.83%with simultaneously increased V_(oc)of 0.905 V,short-circuit current density(J_(sc))of 26.14 mA/cm^(2),and fill factor(FF)of 75.38%.展开更多
It is found that when the parity–time symmetry phenomenon is introduced into the resonant optical gyro system and it works near the exceptional point,the sensitivity can in theory be significantly amplified at low an...It is found that when the parity–time symmetry phenomenon is introduced into the resonant optical gyro system and it works near the exceptional point,the sensitivity can in theory be significantly amplified at low angular rate.However,in fact,the exceptional point is easily disturbed by external environmental variables,which means that it depends on harsh experimental environment and strong control ability,so it is difficult to move towards practical application.Here,we propose a new angular rate sensor structure based on exceptional surface,which has the advantages of high sensitivity and high robustness.The system consists of two fiber-optic ring resonators and two optical loop mirrors,and one of the resonators contains a variable ratio coupler and a variable optical attenuator.We theoretically analyze the system response,and the effects of phase and coupling ratio on the system response.Finally,compared with the conventional resonant gyro,the sensitivity of this exceptional surface angular rate sensor can be improved by about 300 times at low speed.In addition,by changing the loss coefficient in the ring resonator,we can achieve a wide range of 600 rad/s.This scheme provides a new approach for the development of ultra-high sensitivity and wide range angular rate sensors in the future.展开更多
Stimulated emission depletion microscopy(STED)holds great potential in biological science applications,especially in studying nanoscale subcellular structures.However,multi-color STED imaging in live-cell remains chal...Stimulated emission depletion microscopy(STED)holds great potential in biological science applications,especially in studying nanoscale subcellular structures.However,multi-color STED imaging in live-cell remains challenging due to the limited excitation wavelengths and large amount of laser radiation.Here,we develop a multiplexed live-cell STED method to observe more structures simultaneously with limited photo-bleaching and photo-cytotoxicity.By separating live-cell fluorescent probes with similar spectral properties using phasor analysis,our method enables five-color live-cell STED imaging and reveals long-term interactions between different subcellular structures.The results here provide an avenue for understanding the complex and delicate interactome of subcellular structures in live-cell.展开更多
In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading m...In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading modification attack(SM-attack) that may disguise the occurrence of an event as that of another event by intruding sensor communication channels. To solve the problem, we introduce non-deterministic supervisors in the paper, which associate to every observed sequence a set of possible control actions offline and choose a control action from the set randomly online to control the system. Specifically, given a bounded Petri net(PN) as the reference formalism and an SMattack, an algorithm that synthesizes a liveness-enforcing nondeterministic supervisor tolerant to the SM-attack is proposed for the first time.展开更多
The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregul...The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregularities initiation and development is unclear.The motivation of the present study was the previous experimental studies on the application of wide sleepers in the ballasted track.The long-term track geometry measurements with wide sleepers show an enormous reduction of the vertical longitudinal irregularities compared to the conventional track.However,wide sleepers had higher twist and cross-section level irregularities.The present paper aims to explain the phenomenon by discrete element method(DEM)modeling the development process of sleeper inhomogeneous support at cross-level depending on the sleeper form.The DEM simulations show that the maximal settlement intensity is up to 3.5 times lower for a wide sleeper in comparison with the conventional one.Nevertheless,the cross-level differential settlements are almost the same for both sleepers.The particle loading distribution after all loading cycles is concentrated on the smaller area,up to the half sleeper length,with fully unloaded zones under sleeper ends.Ballast flow limitation under the central part of the sleeper could improve the resilience of wide sleepers to the development of cross-level irregularities.The mechanism of initiation of the cross-level irregularity is proposed,which assumes the loss of sleeper support under sleeper ends.The further growth of inhomogeneous settlements along the sleeper is assumed as a result of the interaction of two processes:ballast flow due to dynamic impact during void closing and on the other side high pressure due to the concentration of the pressure under the middle part of the sleeper.The DEM simulation results support the assumption of the mechanism and agree with the experimental studies.展开更多
基金the supports from the National Natural Science Foundation of China(Nos.62264012,62164009)Inner Mongolia Higher Education Research Project(No.NJZZ22343)+1 种基金Inner Mongolia University Research Foundation for Advanced Talents in 2021(No.10000-21311201/005)the Inner Mongolia Autonomous Region for Advanced Talents in 2020(No.12000-12102628)。
文摘Wide bandgap perovskite solar cells(PSCs)have attracted significant attention because they can be applied to the top cells of tandem solar cells.However,high open-circuit voltage(V_(OC))deficit(>0.4 V)result from poor crystallization and high non-radiative recombination losses become a serious limitation in the pursuit of high performance.Here,the relevance between different Pbl_(2)proportions and performance parameters are revealed through analysis of surface morphology,residual stress,and photostability.The increase of Pbl_(2)proportion promotes crystal growth and reduces the work function of the perovskite film surface and promotes the energy level alignment with the carrier transport layer,which decreased the V_(OC)deficit.However,residual PbI_(2)exacerbated the stress level of perovskite film,and the resulting lattice disorder deteriorated the photostability of the device.Ultimately,after the synergistic passivation of residual PbI_(2)and PEAI,the V_(OC)achieves 1.266 V and V_(OC)deficit is less than 0.4 V,the record value in wide bandgap PSCs.
文摘Patients with locally advanced hepatocellular cancer(HCC)and portal vein tumor thrombosis(PVTT)have a dismal prognosis since limited treatment options are available for them.In recent years,effective systemic therapy,and advances in the understanding of technicalities and effectiveness of ablative therapies especially radiotherapy,have given some hope to prolong survival in them.This review summarized recent evidence in literature regarding the possible role of liver resection(LR)and liver transplantation(LT)in patients with locally advanced HCC and PVTT with no extrahepatic disease.Downstaging therapies have helped make curative resection or LT a reality in selected patients.This review emphasizes on the key points to focus on when considering surgery in these patients,who are usually relegated to palliative systemic therapy alone.Meticulous patient selection based on tumor biology,documented downstaging based on imaging and decrease in tumor marker levels,and an adequate waiting period to demonstrate stable disease,may help obtain satisfactory long-term outcomes post LR or LT in an intention to treat strategy in patients with HCC and PVTT.
文摘BACKGROUND Mesenchymal stem cells(MSCs)as living biopharmaceuticals with unique properties,i.e.,stemness,viability,phenotypes,paracrine activity,etc.,need to be administered such that they reach the target site,maintaining these properties unchanged and are retained at the injury site to participate in the repair process.Route of delivery(RoD)remains one of the critical determinants of safety and efficacy.This study elucidates the safety and effectiveness of different RoDs of MSC treatment in heart failure(HF)based on phase II randomized clinical trials(RCTs).We hypothesize that the RoD modulates the safety and efficacy of MSCbased therapy and determines the outcome of the intervention.AIM To investigate the effect of RoD of MSCs on safety and efficacy in HF patients.METHODS RCTs were retrieved from six databases.Safety endpoints included mortality and serious adverse events(SAEs),while efficacy outcomes encompassed changes in left ventricular ejection fraction(LVEF),6-minute walk distance(6MWD),and pro-B-type natriuretic peptide(pro-BNP).Subgroup analyses on RoD were performed for all study endpoints.RESULTS Twelve RCTs were included.Overall,MSC therapy demonstrated a significant decrease in mortality[relative risk(RR):0.55,95%confidence interval(95%CI):0.33-0.92,P=0.02]compared to control,while SAE outcomes showed no significant difference(RR:0.84,95%CI:0.66-1.05,P=0.11).RoD subgroup analysis revealed a significant difference in SAE among the transendocardial(TESI)injection subgroup(RR=0.71,95%CI:0.54-0.95,P=0.04).The pooled weighted mean difference(WMD)demonstrated an overall significant improvement of LVEF by 2.44%(WMD:2.44%,95%CI:0.80-4.29,P value≤0.001),with only intracoronary(IC)subgroup showing significant improvement(WMD:7.26%,95%CI:5.61-8.92,P≤0.001).Furthermore,the IC delivery route significantly improved 6MWD by 115 m(WMD=114.99 m,95%CI:91.48-138.50),respectively.In biochemical efficacy outcomes,only the IC subgroup showed a significant reduction in pro-BNP by-860.64 pg/mL(WMD:-860.64 pg/Ml,95%CI:-944.02 to-777.26,P=0.001).CONCLUSION Our study concluded that all delivery methods of MSC-based therapy are safe.Despite the overall benefits in efficacy,the TESI and IC routes provided better outcomes than other methods.Larger-scale trials are warranted before implementing MSC-based therapy in routine clinical practice.
文摘In his 50 years of practice,he has performed more than 20,000 hepatopancreatobiliary surgeries,being the first one to propose the concept of the“auxiliary partial orthotopic liver transplantation”internationally.Furthermore,he developed the“Chen's inserting biliary-enteric anastomosis and pancreato-enteric anastomosis,”“Chen's hepatic vascular occlusion,”“Chen's liver double-hanging maneuver,”and“Chen's hepatic vascular occlusion without liver portal dissection.”He also popularized these theories and techniques both in China and worldwide.His name is Xiao-Ping Chen,an academician of the Chinese Academy of Sciences and honorary president of the Tongji Medical College of Huazhong University of Science and Technology.
文摘With the rise of live streaming on social media, platforms like Facebook, Instagram, and YouTube have become powerful business tools. They enable users to share live videos, fostering direct connections between businesses and their customers. This critical literature review paper explores the impact of live streaming on businesses, focusing on its role in attracting and satisfying consumers by promoting products tailored to their needs and wants. It emphasizes live streaming’s crucial role in engaging customers, a key to business growth. The study also provides viable strategies for businesses to leverage live streaming for growth and customer engagement, underscoring its importance in the business landscape.
基金supported by the National Natural Science Foundation of the People's Republic of China“On disjoint path covers of graphs and related problems”(12261085)Natural Science Foundation of Xinjiang Uygur Autonomous Region of China“On spanning wide diameter and spanning cycle ability of interconnection networks”(2021D01C116)。
文摘A t-container Ct(u,v)is a set of t internally disjoint paths between two distinct vertices u and v in a graph G,i.e.,Ct(u,v)={P_(1),P_(2),···,Pt}.Moreover,if V(P_(1))∪V(P_(2))∪···∪V(Pt)=V(G)then Ct(u,v)is called a spanning t-container,denoted by C_(t)^(sc)(u,v).The length of C_(t)^(sc)(u,v)={P_(1),P_(2),···,Pt}is l(C_(t)^(sc)(u,v))=max{l(P_(i))|1≤i≤t}.A graph G is spanning t-connected if there exists a spanning t-container between any two distinct vertices u and v in G.Assume that u and v are two distinct vertices in a spanning t-connected graph G.Let D_(t)^(sc)(u,v)be the collection of all C_(t)^(sc)(u,v)’s.Define the spanning t-wide distance between u and v in G,d_(t)^(sc)(u,v)=min{l(C_(t)^(sc)(u,v))|C_(t)^(sc)(u,v)∈D_(t)^(sc)(u,v)},and the spanning t-wide diameter of G,D_(t)^(sc)(G)=max{d_(t)^(sc)(u,v)|u,v∈V(G)}.In particular,the spanning wide diameter of G is D_(κ)^(sc)(G),whereκis the connectivity of G.In the paper we provide the upper and lower bounds of the spanning wide diameter of a graph,and show that the bounds are best possible.We also determine the exact values of wide diameters of some well known graphs including Harary graphs and generalized Petersen graphs et al..
基金Special Fund for Carbon Peak and Carbon Neutralization Scientific and Technological Innovation Project of Jiangsu Province,Grant/Award Number:BE2022042National Natural Science Foundation of China,Grant/Award Numbers:22201275,51873086,51673096,51873086,51673096+2 种基金the Project on the Enterprises-Universities-Research Cooperation of Kucap Smart Technology(Nanjing)Co.,Ltd.,Grant/Award Number:202240607Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:KYCX23-1407Anhui Provincial Natural Science Foundation,Grant/Award Number:2208085QB32。
文摘Solid-state supercapacitors(SSCs)are emerging as one of the promising energy storage devices due to their high safety,superior power density,and excellent cycling life.However,performance degradation and safety issues under extreme conditions are the main challenges for the practical application.With the expansion of human activities,such as space missions,polar exploration,and so on,the investigation of SSC with wide temperature tolerance,high energy density,power density,and sustainability is highly desired.In this review,the effects of temperature on SSC are systematically illustrated and clarified,including the properties of the electrolyte,ion diffusion,and reaction dynamics of the supercapacitor.Subsequently,we summarize the recent advances in wide-temperature-range SSCs from the aspect of electrolyte modification,electrode design,and interface adjustment between electrode and electrolyte,especially with critical concerns on ionic conductivity and cycling stability.In the end,a perspective is presented,expecting to promote the practical application of the SSC in harsh conditions.
文摘Implementation of the BRI projects has heralded positive changes in the lives of Tanzanian people Tanzania is an important Belt and Road Initiative(BRI)hub in Africa.It signed a BRI cooperation memorandum with China in 2018.Bilateral exchanges have been on the rise since then.On the occasion of the 10th anniversary of the launch of the initiative,ChinAfrica sat down with Mbelwa Kairuki,Tanzanian ambassador to China,to hear his insights on the BRI,especially the changes brought by the BRI to the local people’s lives.
基金supported by the National Research Foundation of Korea (NRF)the Ministry of Science,ICT (2022M3J1A1085285,2019R1A2C1084010,and 2022R1A2C2006532)the Korea Electric Power Corporation (R20XO02-1)。
文摘Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be obtained.The 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases perovskite grain size,retards halide segregation,and accelerates hole extraction.The surface functionalization achieves a high power conversion efficiency(PCE)of 17.62%for a single-junction wide-bandgap(~1.77 e V)PSC.We also demonstrate a monolithic all-perovskite tandem solar cell using surfaceengineered HSC,showing high PCE of 24.66%with large open-circuit voltage of 2.008 V and high fillfactor of 81.45%.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.
基金supported by the National Natural Science Foundation of China(52072173)the International Science and Technology Cooperation Program of Jiangsu Province(SBZ2022000084).
文摘Li–CO_(2) batteries are considered promising energy storage systems in extreme environments such as Mars;however,severe performance degradation will occur at a subzero temperature owning to the sluggish reaction kinetics.Herein,a photo-energized strategy adopting sustainable solar energy in wide working temperature range Li–CO_(2) battery was achieved with a binder-free MoS_(2)/carbon nanotube(CNT)photo-electrode as cathode.The unique layered structure and excellent photoelectric properties of MoS_(2) facilitate the abundant generation and rapid transfer of photo-excited carriers,which accelerate the CO_(2) reduction and Li_(2)CO_(3) decomposition upon illumination.The illuminated battery at room temperature exhibited high discharge voltage of 2.95 V and mitigated charge voltage of 3.27 V,attaining superior energy efficiency of 90.2%and excellent cycling stability of over 120 cycles.Even at an extremely low temperature of−30℃,the battery with same electrolyte can still deliver a small polarization of 0.45 V by the photoelectric and photothermal synergistic mechanism of MoS_(2)/CNT cathode.This work demonstrates the promising potential of the photo-energized wide working temperature range Li–CO_(2) battery in addressing the obstacle of charge overpotential and energy efficiency.
基金the National Natural Science Foundation of China(Nos.52125306 and 21875286)。
文摘Herein,two asymmetric hexacyclic fused small molecule acceptors(SMAs),namely BP4F-HU and BP4F-UU,were synthesized.The elongated outside chains in the BP4F-UU molecule played a crucial role in optimizing the morphology of blend film,thereby improving charge mobility and reducing energy loss within the corresponding film.Notably,the PM6:BP4F-UU device exhibited a higher open-circuit voltage(V_(oc))of 0.878 V compared to the PM6:BP4F-HU device with a V_(oc)of 0.863 V.Further,a new wide bandgap SMA named BTP-TA was designed and synthesized as the third component to the PM6:BP4F-UU host binary devices,which showed an ideal complementary absorption spectrum in PM6:BP4F-UU system.In addition,BTP-TA can achieve efficient intermolecular energy transfer to BP4F-UU by fluorescence resonance energy transfer(FRET)pathway,due to the good overlap between the photoluminescence(PL)spectrum of BTP-TA and the absorption region of BP4F-UU.Consequently,ternary devices with 15wt%BTP-TA exhibits broader photon utilization,optimal blend morphology,and reduced charge recombination compared to the corresponding binary devices.Consequently,PM6:BP4F-UU:BTP-TA ternary device achieved an optimal power conversion efficiency(PCE)of 17.83%with simultaneously increased V_(oc)of 0.905 V,short-circuit current density(J_(sc))of 26.14 mA/cm^(2),and fill factor(FF)of 75.38%.
基金supported in part by the National Natural Science Foundation of China (Grant Nos.62273314,U21A20141,and 51821003)Fundamental Research Program of Shanxi Province (Grant No.202303021224008)Shanxi Province Key Laboratory of Quantum Sensing and Precision Measure-ment (Grant No.201905D121001).
文摘It is found that when the parity–time symmetry phenomenon is introduced into the resonant optical gyro system and it works near the exceptional point,the sensitivity can in theory be significantly amplified at low angular rate.However,in fact,the exceptional point is easily disturbed by external environmental variables,which means that it depends on harsh experimental environment and strong control ability,so it is difficult to move towards practical application.Here,we propose a new angular rate sensor structure based on exceptional surface,which has the advantages of high sensitivity and high robustness.The system consists of two fiber-optic ring resonators and two optical loop mirrors,and one of the resonators contains a variable ratio coupler and a variable optical attenuator.We theoretically analyze the system response,and the effects of phase and coupling ratio on the system response.Finally,compared with the conventional resonant gyro,the sensitivity of this exceptional surface angular rate sensor can be improved by about 300 times at low speed.In addition,by changing the loss coefficient in the ring resonator,we can achieve a wide range of 600 rad/s.This scheme provides a new approach for the development of ultra-high sensitivity and wide range angular rate sensors in the future.
基金supported by the following grants:National Natural Science Foundation of China(62125504,62361166631)STI 2030-Major Projects(2021ZD0200401)+1 种基金the Fundamental Research Funds for the Central Universities(226-2022-00201)the Open Project Program of Wuhan National Laboratory for Optoelectronics(2021WNLOKF007).
文摘Stimulated emission depletion microscopy(STED)holds great potential in biological science applications,especially in studying nanoscale subcellular structures.However,multi-color STED imaging in live-cell remains challenging due to the limited excitation wavelengths and large amount of laser radiation.Here,we develop a multiplexed live-cell STED method to observe more structures simultaneously with limited photo-bleaching and photo-cytotoxicity.By separating live-cell fluorescent probes with similar spectral properties using phasor analysis,our method enables five-color live-cell STED imaging and reveals long-term interactions between different subcellular structures.The results here provide an avenue for understanding the complex and delicate interactome of subcellular structures in live-cell.
基金supported in part by the Public Technology Research Plan of Zhejiang Province (LGJ21F030001)the National Natural Science Foundation of China (62302448)the Zhejiang Provincial Key Laboratory of New Network Standards and Technologies (2013E10012)。
文摘In this paper, we study the supervisory control problem of discrete event systems assuming that cyber-attacks might occur. In particular, we focus on the problem of liveness enforcement and consider a sensor-reading modification attack(SM-attack) that may disguise the occurrence of an event as that of another event by intruding sensor communication channels. To solve the problem, we introduce non-deterministic supervisors in the paper, which associate to every observed sequence a set of possible control actions offline and choose a control action from the set randomly online to control the system. Specifically, given a bounded Petri net(PN) as the reference formalism and an SMattack, an algorithm that synthesizes a liveness-enforcing nondeterministic supervisor tolerant to the SM-attack is proposed for the first time.
文摘The cross-level and twist irregularities are the most dangerous irregularity types that could cause wheel unloading with the risk of derailments and additional maintenance expenses.However,the mechanism of the irregularities initiation and development is unclear.The motivation of the present study was the previous experimental studies on the application of wide sleepers in the ballasted track.The long-term track geometry measurements with wide sleepers show an enormous reduction of the vertical longitudinal irregularities compared to the conventional track.However,wide sleepers had higher twist and cross-section level irregularities.The present paper aims to explain the phenomenon by discrete element method(DEM)modeling the development process of sleeper inhomogeneous support at cross-level depending on the sleeper form.The DEM simulations show that the maximal settlement intensity is up to 3.5 times lower for a wide sleeper in comparison with the conventional one.Nevertheless,the cross-level differential settlements are almost the same for both sleepers.The particle loading distribution after all loading cycles is concentrated on the smaller area,up to the half sleeper length,with fully unloaded zones under sleeper ends.Ballast flow limitation under the central part of the sleeper could improve the resilience of wide sleepers to the development of cross-level irregularities.The mechanism of initiation of the cross-level irregularity is proposed,which assumes the loss of sleeper support under sleeper ends.The further growth of inhomogeneous settlements along the sleeper is assumed as a result of the interaction of two processes:ballast flow due to dynamic impact during void closing and on the other side high pressure due to the concentration of the pressure under the middle part of the sleeper.The DEM simulation results support the assumption of the mechanism and agree with the experimental studies.
