Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or ...Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.展开更多
Objective:In this study,we investigated the composition of the intestinal microflora associated with Yang-deficiency and the function-specific members of this microflora.Method:Subjects with normal and Yang-deficient ...Objective:In this study,we investigated the composition of the intestinal microflora associated with Yang-deficiency and the function-specific members of this microflora.Method:Subjects with normal and Yang-deficient constitutions were recruited in Beijing,with 30 subjects in each group.Illumina high-throughput sequencing was used to sequence the DNA of their fecal bacteria in the 16S rRNA V3-V4 region.The species abundance and distribution of the intestinal microflora in each specimen were determined with a statistical analysis of these sequences.We identified an underlying taxonomic trend with nonparametric PCoA and other statistical techniques.Results:(1) Subjects with Yang-deficiency displayed more uneven abundances of the taxa in their intestinal microflora than the subjects with normal Yang;(2) several differences were observed in the proportions of certain bacterial groups between the Yang-deficient and control groups;and (3) the fallowing bacteria differed significantly between the two groups:(i) Brevundimonas,Leuconostoc,Turicibacter,Defluviitaleaceae incertae sedis,Rothia,and Butyricimonas were slightly higher in the Yang-deficient subjects,whereas (ii)Megasphaera,Ruminococcus,and Lachnospira were higher in the normal subjects than in the Yang-deficient subjects.展开更多
Stroke is classified as ischemic or hemorrhagic,and there are few effective treatments for either type.Immunologic mechanisms play a critical role in secondary brain injury following a stroke,which manifests as cytoki...Stroke is classified as ischemic or hemorrhagic,and there are few effective treatments for either type.Immunologic mechanisms play a critical role in secondary brain injury following a stroke,which manifests as cytokine release,blood–brain barrier disruption,neuronal cell death,and ultimately behavioral impairment.Suppressing the inflammatory response has been shown to mitigate this cascade of events in experimental stroke models.However,in clinical trials of anti-inflammatory agents,longterm immunosuppression has not demonstrated significant clinical benefits for patients.This may be attributable to the dichotomous roles of inflammation in both tissue injury and repair,as well as the complex pathophysiologic inflammatory processes in stroke.Inhibiting acute harmful inflammatory responses or inducing a phenotypic shift from a pro-inflammatory to an anti-inflammatory state at specific time points after a stroke are alternative and promising therapeutic strategies.Identifying agents that can modulate inflammation requires a detailed understanding of the inflammatory processes of stroke.Furthermore,epigenetic reprogramming plays a crucial role in modulating post-stroke inflammation and can potentially be exploited for stroke management.In this review,we summarize current findings on the epigenetic regulation of the inflammatory response in stroke,focusing on key signaling pathways including nuclear factor-kappa B,Janus kinase/signal transducer and activator of transcription,and mitogen-activated protein kinase as well as inflammasome activation.We also discuss promising molecular targets for stroke treatment.The evidence to date indicates that therapeutic targeting of the epigenetic regulation of inflammation can shift the balance from inflammation-induced tissue injury to repair following stroke,leading to improved post-stroke outcomes.展开更多
目的系统评价老年人口腔衰弱(oral frailty,OF)评估工具,为选择合适的OF评估工具提供参考。方法检索PubMed、Web of Science、CINAHL、Cochrane Library、中国知网、万方数据知识服务平台、中国生物医学文献数据库、维普中文科技期刊全...目的系统评价老年人口腔衰弱(oral frailty,OF)评估工具,为选择合适的OF评估工具提供参考。方法检索PubMed、Web of Science、CINAHL、Cochrane Library、中国知网、万方数据知识服务平台、中国生物医学文献数据库、维普中文科技期刊全文数据库,采用基于共识驱动的健康测量工具选择标准(consensus-based standards for the selection of health measurement instrument,COSMIN)指南对纳入研究进行评价。结果本文共纳入9项研究,包括7个英文测评工具及2个中文版工具。1个工具内容效度和内部一致性均为充分,为A类推荐;6个工具均没有“任何等级证据证明内容效度充分,且内部一致性充分(至少为低质量证据)”,为B类推荐;2个工具由于有高质量的证据证明其内部一致性的不充分,为C类推荐。结论未来研究者应遵循COSMIN指南,规范开发流程,完善测量属性报告,开发并验证适合我国老年人OF的本土化评估工具,为OF的识别与管理提供科学可靠的工具。展开更多
目的:对慢性阻塞性肺疾病(COPD)病人戒烟研究热点及发展动态进行文献计量学分析,以期为COPD病人戒烟相关研究提供参考。方法:检索2011年1月1日—2021年12月31日Web of Science核心合集和中国知网中与COPD病人戒烟相关的文献,采用CiteSpa...目的:对慢性阻塞性肺疾病(COPD)病人戒烟研究热点及发展动态进行文献计量学分析,以期为COPD病人戒烟相关研究提供参考。方法:检索2011年1月1日—2021年12月31日Web of Science核心合集和中国知网中与COPD病人戒烟相关的文献,采用CiteSpace 5.6.R4软件进行文献计量学分析。结果:共纳入3161篇文献,COPD病人戒烟研究领域的发文量逐年增多,该领域呈现研究范围逐渐扩大化、研究人群逐渐精细化、研究内容逐渐具体化的特点。疾病负担、急性加重期、戒烟效果、戒烟依从性及肺康复为近年的研究热点。结论:COPD病人戒烟研究处于稳步发展阶段,相关研究不断深入,但在影响因素分析、干预策略研究、方案实施管理等方面的探索仍存在不足,未来需在整体把握该领域研究特点、热点与发展趋势的基础上进一步开展研究,同时加强交流合作,推动COPD病人戒烟研究领域的快速发展。展开更多
Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthqu...Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.展开更多
Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of...Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.展开更多
Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyz...Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyze the data characteristics of continuous hunting of high-speed trains passing through turnouts and propose a diagnostic method for engineering applications.Design/methodology/approach–First,Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)is performed to determine the first characteristic component of the car body’s lateral acceleration.Then,the Short-Time Fourier Transform(STFT)is performed to calculate the marginal spectra.Finally,the presence of a continuous hunting problem is determined based on the results of the comparison calculations and diagnostic thresholds.To improve computational efficiency,permutation entropy(PE)is used as a fast indicator to identify turnouts with potential problems.Findings–Under continuous hunting conditions,the PE is less than 0.90;the ratio of the maximum peak value of the signal component to the original signal peak value exceeded 0.7,and there is an energy band in the STFT time-frequency map,which corresponds to a frequency distribution range of 1–2 Hz.Originality/value–The research results have revealed the lateral vibration characteristics of the high-speed train’s car body during continuous hunting when passing through turnouts.On this basis,an effective diagnostic method has been proposed.With a focus on practical engineering applications,a rapid screening index for identifying potential issues has been proposed,significantly enhancing the efficiency of diagnostic processes.展开更多
The Majiagou Formation in the Fuxian area of the southeastern Ordos Basin has undergone a complex diagenetic evolution history under the influence of eustacy and the Caledonian karstification,resulting in several comp...The Majiagou Formation in the Fuxian area of the southeastern Ordos Basin has undergone a complex diagenetic evolution history under the influence of eustacy and the Caledonian karstification,resulting in several complex reservoir types.Through analyses of mineralogy,petrology,and reservoir geology,three major types of dolomite reservoirs with different genetic mechanisms,including anhydritic moldicdissolved pore type,dolomitic intercrystalline-pore type,and fractured type were identified,and their formation mechanisms and distribution patterns were examined.The aphanocrystalline to very finecrystalline anhydritic dolomite was resulted from Sabhak dolomitization,and is characterized by small size of crystals and high content of anhydrite.Dolomite reservoirs of anhydritic moldic-dissolved pore type were developed in multi-stage dissolution processes and mainly distributed at higher positions of the paleogeomorphology where the filling was weak.The very fine to fine-crystalline dolomite of shoal facies was formed under seepage-reflux dolomitization,and characterized by larger sizes of crystals and well-developed intercrystalline pores.Dolomite reservoirs of intercrystalline-pore type were mainly developed at the lower positions of the paleogeomorphology where bedding-parallel karst dissolution was strong.The fractured dolomite reservoirs,generated by the anhydrite swelling and karst cave collapse,occur in multiple horizons but within limited areas due to multi-stage fillings.展开更多
The effects of drawing strain during intermediate annealing on the microstructure and properties of Cu-20 wt%Fe alloy wires while maintaining constant total deformation were investigated.Intermediate annealing effecti...The effects of drawing strain during intermediate annealing on the microstructure and properties of Cu-20 wt%Fe alloy wires while maintaining constant total deformation were investigated.Intermediate annealing effectively removes work hardening in both the Cu matrix and Fe fibers,restoring their plastic deformation capacity and preserving fiber continuity during subsequent redrawing.The process also refines the Fe phase,leading to a more uniform size distribution and straighter,better-aligned Cu/Fe phase interfaces,thereby enhancing the comprehensive properties of the alloy.The magnitude of drawing strain during intermediate annealing plays a critical role in balancing the mechanical strength and electrical conductivity of redrawn wires.A lower initial drawing strain requires greater redrawing strain,leading to excessive hardening of the Fe fibers,which negatively impacts the electrical conductivity and tensile plasticity.Conversely,a higher initial drawing strain can result in insufficient work hardening during the redrawing deformation process,yielding minimal strength improvements.Among the tested alloys,H/3.5 wires show a slight reduction in strength and hardness compared to W and H/4.5 wires but exhibit a significant increase in tensile elongation and electrical conductivity.The tensile strength was 755 MPa,and the electrical conductivity was 47%international-annealed copper standard(IACS).The optimal performance is attributed to the formation of a high-density,ultrafine Fe fiber structure-aligned parallel to the drawing direction,which is achieved through a suitable combination of the drawing process and intermediate annealing.展开更多
Radical anions of electron-deficient perylene diimides(PDI)are attractive near-infrared(NIR)absorbers for photothermal conversion;however,their stability is often compromised by strong aggregation and reoxidation in a...Radical anions of electron-deficient perylene diimides(PDI)are attractive near-infrared(NIR)absorbers for photothermal conversion;however,their stability is often compromised by strong aggregation and reoxidation in air.Herein,we present a class of bacterial composites hybridized with a newly synthesized doubly-strapped PDI cyclophane,termed“Gemini Box”(GBox-3^(4+)),which features air-stable PDI radicals for NIR photothermal conversion.The effective spatial isolation provided by the double-sided cationic molecular straps allows GBox-3^(4+)to completely suppress chromophore aggregation,even in concentrated aqueous solutions up to 2 mmol/L,thereby preserving its characteristic fluorescence for live-cell imaging.After incubation of bacteria with GBox-3^(4+),the radical species PDI·-have been found to stably exist in the bacterial composites under ambient conditions,both in aqueous suspension and solid forms.Further experiments demonstrate that the air stability of the radical species relies on the simultaneous presence of the doubly-strapped PDI dye and the bacteria.Moreover,the dye-bacterial composites exhibited an high-efficiency NIR photothermal effect with high durability,enabling their application as photothermal agents for seawater desalination.This work provides a new access to the in situ fabrication of photothermal materials from biomass,relying on the rational molecular design and the unique microenvironment of bacteria.展开更多
The deformation of Cu–20 wt.%Fe alloy wires leads to a significant improvement in mechanical properties and a decrease in electrical conductivity.Simultaneous improvements in strength and conductivity were achieved b...The deformation of Cu–20 wt.%Fe alloy wires leads to a significant improvement in mechanical properties and a decrease in electrical conductivity.Simultaneous improvements in strength and conductivity were achieved by intermediate annealing of drawn Cu–20 wt.%Fe wires.As the annealing temperature increased,the strength of Cu–20 wt.%Fe alloy wire decreased monotonically,but the electrical conductivity first increased and then decreased,reaching its peak value after annealing at 500℃.The decrease in strength is related to dislocation recovery and static recrystallization of Cu and Fe phases,and the increase in electrical conductivity mainly results from the aging precipitation of solid solution Fe.After annealing at 500℃,there was no obvious recrystallization of Cu phase,and many of the nano-Fe particles precipitated from Cu matrix.An annealing temperature of 600℃ induced the recrystallization of Cu matrix and an increase in Fe solid solubility,resulting in a decrease in strength and electrical conductivity.Subsequently,the wires annealed at 500℃ were drawn to 2 mm.Compared with those of the continuously drawn Cu–20 wt.%Fe alloy wires,the deformation ability,strength,and electrical conductivity of Cu–20 wt.%Fe alloy wires subjected to intermediate annealing treatment are significantly greater.This is mainly related to the sufficient precipitation of Fe in Cu matrix and the strengthening of refined Fe fibers parallel to the drawing direction.展开更多
Nano-lamellar Ti_(3)Al/TiAl(α2/γ)alloy with significantly improved nanohardness was prepared using dual-wire-fed electron beam-directed energy deposition(EB-DED)in this study.This investigation focused on the evolut...Nano-lamellar Ti_(3)Al/TiAl(α2/γ)alloy with significantly improved nanohardness was prepared using dual-wire-fed electron beam-directed energy deposition(EB-DED)in this study.This investigation focused on the evolution of the colony shape and lamellar thickness of the Ti-43Al lamellar alloy at different heights.Nanoindentation tests were employed to evaluate deformation resistance,and numerical simulations provided deeper insights into the deposition process.The results indicate that the colonies are mostly columnar,except for a few equiaxed colonies at the top.Rapid cooling significantly refines theα2 lamellae,resulting in an average spacing of 218 nm and thickness of 41 nm.Additionally,substantial microstrain and a nonequilibrium Al distribution lead to a significant generation ofγvariants,refining theγlamellae to 57 nm.Abundantγ/γ’andα2/γinterfaces,along with fineα2 phases,contribute to improved deformation resistance.Consequently,the nano-lamellar TiAl alloy exhibited a notable 32%increase in nanohardness(8.3 GPa)while maintaining a similar modulus(197 GPa)to conventionally prepared alloys.This study holds significant promise for advancing high-performance TiAl alloys through the dual-wire-fed EB-DED process.展开更多
文摘Conventional locking/release mechanisms often face challenges in aircraft wing separation processes,such as excessive impact loads and insufficient synchronization.These may cause structural damage to the airframe or attitude instability,seriously compromising mission reliability.To address this engineering challenge,this paper proposes a multi-point low-impact locking/release mechanism based on the mobility model and energy conversion strategy.Through establishing a DOF constraint framework system,this paper systematically analyzes the energy transfer and conversion characteristics during the wing separation process,reveals the generation mechanism of impact loads,and conducts research on low-impact design based on energy conversion strategy.Building on this foundation,a single-point locking/release mechanism employing parallel trapezoidal key shaft structure was designed,which increases frictional contact time and reduces the energy release rate,thereby achieving low-impact characteristics.The mechanism's performance was validated through physical prototype development and systematic functional testing(including unlocking force,synchronization,and impact tests).Experimental results demonstrate:(1)Under 14 kN preload condition,the maximum unlocking force was only 92.54 N,showing a linear relationship with preload that satisfies the"strong-connection/weak-unlock"design requirement;(2)Wing separation was completed within 46 ms,with synchronization time difference among three separation mechanisms stably controlled within 12-14 ms,proving rapid and reliable operation;(3)The unlocking impact acceleration ranged between 26 and 73 g,below the 100 g design limit,confirming the effectiveness of the energy conversion strategy.The proposed low-impact locking/release mechanism design method based on energy conversion strategy resolves the traditional challenges of high impact and synchronization deficiencies.The synergistic optimization mechanism of"structural load reduction and performance improvement"provides a highly reliable technical solution for wing separable mechanisms while offering novel design insights for wing connection/separation systems engineering.
文摘Objective:In this study,we investigated the composition of the intestinal microflora associated with Yang-deficiency and the function-specific members of this microflora.Method:Subjects with normal and Yang-deficient constitutions were recruited in Beijing,with 30 subjects in each group.Illumina high-throughput sequencing was used to sequence the DNA of their fecal bacteria in the 16S rRNA V3-V4 region.The species abundance and distribution of the intestinal microflora in each specimen were determined with a statistical analysis of these sequences.We identified an underlying taxonomic trend with nonparametric PCoA and other statistical techniques.Results:(1) Subjects with Yang-deficiency displayed more uneven abundances of the taxa in their intestinal microflora than the subjects with normal Yang;(2) several differences were observed in the proportions of certain bacterial groups between the Yang-deficient and control groups;and (3) the fallowing bacteria differed significantly between the two groups:(i) Brevundimonas,Leuconostoc,Turicibacter,Defluviitaleaceae incertae sedis,Rothia,and Butyricimonas were slightly higher in the Yang-deficient subjects,whereas (ii)Megasphaera,Ruminococcus,and Lachnospira were higher in the normal subjects than in the Yang-deficient subjects.
基金supported by the National Natural Science Foundation of China,Nos.32070735(to QL),82371321(to QL),82171270(to ZL)Public Service Platform for Artificial Intelligence Screening and Auxiliary Diagnosis for the Medical and Health Industry,Ministry of Industry and Information Technology of the People's Republic of China,No.2020-0103-3-1(to ZL)+2 种基金the Natural Science Foundation of Beijing,No.Z200016(to ZL)Beijing Talents Project,No.2018000021223ZK03(to ZL)Beijing Municipal Committee of Science and Technology,No.Z201100005620010(to ZL)。
文摘Stroke is classified as ischemic or hemorrhagic,and there are few effective treatments for either type.Immunologic mechanisms play a critical role in secondary brain injury following a stroke,which manifests as cytokine release,blood–brain barrier disruption,neuronal cell death,and ultimately behavioral impairment.Suppressing the inflammatory response has been shown to mitigate this cascade of events in experimental stroke models.However,in clinical trials of anti-inflammatory agents,longterm immunosuppression has not demonstrated significant clinical benefits for patients.This may be attributable to the dichotomous roles of inflammation in both tissue injury and repair,as well as the complex pathophysiologic inflammatory processes in stroke.Inhibiting acute harmful inflammatory responses or inducing a phenotypic shift from a pro-inflammatory to an anti-inflammatory state at specific time points after a stroke are alternative and promising therapeutic strategies.Identifying agents that can modulate inflammation requires a detailed understanding of the inflammatory processes of stroke.Furthermore,epigenetic reprogramming plays a crucial role in modulating post-stroke inflammation and can potentially be exploited for stroke management.In this review,we summarize current findings on the epigenetic regulation of the inflammatory response in stroke,focusing on key signaling pathways including nuclear factor-kappa B,Janus kinase/signal transducer and activator of transcription,and mitogen-activated protein kinase as well as inflammasome activation.We also discuss promising molecular targets for stroke treatment.The evidence to date indicates that therapeutic targeting of the epigenetic regulation of inflammation can shift the balance from inflammation-induced tissue injury to repair following stroke,leading to improved post-stroke outcomes.
文摘目的系统评价老年人口腔衰弱(oral frailty,OF)评估工具,为选择合适的OF评估工具提供参考。方法检索PubMed、Web of Science、CINAHL、Cochrane Library、中国知网、万方数据知识服务平台、中国生物医学文献数据库、维普中文科技期刊全文数据库,采用基于共识驱动的健康测量工具选择标准(consensus-based standards for the selection of health measurement instrument,COSMIN)指南对纳入研究进行评价。结果本文共纳入9项研究,包括7个英文测评工具及2个中文版工具。1个工具内容效度和内部一致性均为充分,为A类推荐;6个工具均没有“任何等级证据证明内容效度充分,且内部一致性充分(至少为低质量证据)”,为B类推荐;2个工具由于有高质量的证据证明其内部一致性的不充分,为C类推荐。结论未来研究者应遵循COSMIN指南,规范开发流程,完善测量属性报告,开发并验证适合我国老年人OF的本土化评估工具,为OF的识别与管理提供科学可靠的工具。
文摘目的:对慢性阻塞性肺疾病(COPD)病人戒烟研究热点及发展动态进行文献计量学分析,以期为COPD病人戒烟相关研究提供参考。方法:检索2011年1月1日—2021年12月31日Web of Science核心合集和中国知网中与COPD病人戒烟相关的文献,采用CiteSpace 5.6.R4软件进行文献计量学分析。结果:共纳入3161篇文献,COPD病人戒烟研究领域的发文量逐年增多,该领域呈现研究范围逐渐扩大化、研究人群逐渐精细化、研究内容逐渐具体化的特点。疾病负担、急性加重期、戒烟效果、戒烟依从性及肺康复为近年的研究热点。结论:COPD病人戒烟研究处于稳步发展阶段,相关研究不断深入,但在影响因素分析、干预策略研究、方案实施管理等方面的探索仍存在不足,未来需在整体把握该领域研究特点、热点与发展趋势的基础上进一步开展研究,同时加强交流合作,推动COPD病人戒烟研究领域的快速发展。
基金supported by the National Natural Science Foundation of China (Grant No.52108361)the Sichuan Science and Technology Program of China (Grant No.2023YFS0436)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project (Grant No.SKLGP2022Z015).
文摘Bedding parallel stepped rock slopes exist widely in nature and are used in slope engineering.They are characterized by complex topography and geological structure and are vulnerable to shattering under strong earthquakes.However,no previous studies have assessed the mechanisms underlying seismic failure in rock slopes.In this study,large-scale shaking table tests and numerical simulations were conducted to delineate the seismic failure mechanism in terms of acceleration,displacement,and earth pressure responses combined with shattering failure phenomena.The results reveal that acceleration response mutations usually occur within weak interlayers owing to their inferior performance,and these mutations may transform into potential sliding surfaces,thereby intensifying the nonlinear seismic response characteristics.Cumulative permanent displacements at the internal corners of the berms can induce quasi-rigid displacements at the external corners,leading to greater permanent displacements at the internal corners.Therefore,the internal corners are identified as the most susceptible parts of the slope.In addition,the concept of baseline offset was utilized to explain the mechanism of earth pressure responses,and the result indicates that residual earth pressures at the internal corners play a dominant role in causing deformation or shattering damage.Four evolutionary deformation phases characterize the processes of seismic responses and shattering failure of the bedding parallel stepped rock slope,i.e.the formation of tensile cracks at the internal corners of the berm,expansion of tensile cracks and bedding surface dislocation,development of vertical tensile cracks at the rear edge,and rock mass slipping leading to slope instability.Overall,this study provides a scientific basis for the seismic design of engineering slopes and offers valuable insights for further studies on preventing seismic disasters in bedding parallel stepped rock slopes.
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program of China(No.2019QZKK0306-02)the National Natural Science Foundation of China(Nos.42322102 and 42271058)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2021310)the Science&Technology Fundamental Resources Investigation Program of China(No.2022FY100202)
文摘Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.
基金support from the funds of National Natural Science Foundation of China(52308473)China Academy of Railway Science Corporation Limited(2022YJ192)are gratefully acknowledged。
文摘Purpose–High-speed turnouts are more complex in structure and thus may cause abnormal vibration of highspeed train car body,affecting driving safety and passenger riding experience.Therefore,it is necessary to analyze the data characteristics of continuous hunting of high-speed trains passing through turnouts and propose a diagnostic method for engineering applications.Design/methodology/approach–First,Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)is performed to determine the first characteristic component of the car body’s lateral acceleration.Then,the Short-Time Fourier Transform(STFT)is performed to calculate the marginal spectra.Finally,the presence of a continuous hunting problem is determined based on the results of the comparison calculations and diagnostic thresholds.To improve computational efficiency,permutation entropy(PE)is used as a fast indicator to identify turnouts with potential problems.Findings–Under continuous hunting conditions,the PE is less than 0.90;the ratio of the maximum peak value of the signal component to the original signal peak value exceeded 0.7,and there is an energy band in the STFT time-frequency map,which corresponds to a frequency distribution range of 1–2 Hz.Originality/value–The research results have revealed the lateral vibration characteristics of the high-speed train’s car body during continuous hunting when passing through turnouts.On this basis,an effective diagnostic method has been proposed.With a focus on practical engineering applications,a rapid screening index for identifying potential issues has been proposed,significantly enhancing the efficiency of diagnostic processes.
基金The research project is funded by the Geological Joint Fund(U2244209).
文摘The Majiagou Formation in the Fuxian area of the southeastern Ordos Basin has undergone a complex diagenetic evolution history under the influence of eustacy and the Caledonian karstification,resulting in several complex reservoir types.Through analyses of mineralogy,petrology,and reservoir geology,three major types of dolomite reservoirs with different genetic mechanisms,including anhydritic moldicdissolved pore type,dolomitic intercrystalline-pore type,and fractured type were identified,and their formation mechanisms and distribution patterns were examined.The aphanocrystalline to very finecrystalline anhydritic dolomite was resulted from Sabhak dolomitization,and is characterized by small size of crystals and high content of anhydrite.Dolomite reservoirs of anhydritic moldic-dissolved pore type were developed in multi-stage dissolution processes and mainly distributed at higher positions of the paleogeomorphology where the filling was weak.The very fine to fine-crystalline dolomite of shoal facies was formed under seepage-reflux dolomitization,and characterized by larger sizes of crystals and well-developed intercrystalline pores.Dolomite reservoirs of intercrystalline-pore type were mainly developed at the lower positions of the paleogeomorphology where bedding-parallel karst dissolution was strong.The fractured dolomite reservoirs,generated by the anhydrite swelling and karst cave collapse,occur in multiple horizons but within limited areas due to multi-stage fillings.
基金support provided by the National Natural Science Foundation of China(Nos.52405364,and 52171110)the Jiangsu Funding Program for Excellent Postdoctoral Talent.W.Huo acknowledges the support from the European Union Horizon 2020 Research and Innovation Program(No.857470)+1 种基金from the European Regional Development Fund via the Foundation for Polish Science International Research Agenda PLUS Program(No.MAB PLUS/2018/8)The publication was partly created within the framework of the project of the Minister of Science and Higher Education"Support for the activities of Centers of Excellence established in Poland under Horizon 2020"(No.MEiN/2023/DIR/3795).
文摘The effects of drawing strain during intermediate annealing on the microstructure and properties of Cu-20 wt%Fe alloy wires while maintaining constant total deformation were investigated.Intermediate annealing effectively removes work hardening in both the Cu matrix and Fe fibers,restoring their plastic deformation capacity and preserving fiber continuity during subsequent redrawing.The process also refines the Fe phase,leading to a more uniform size distribution and straighter,better-aligned Cu/Fe phase interfaces,thereby enhancing the comprehensive properties of the alloy.The magnitude of drawing strain during intermediate annealing plays a critical role in balancing the mechanical strength and electrical conductivity of redrawn wires.A lower initial drawing strain requires greater redrawing strain,leading to excessive hardening of the Fe fibers,which negatively impacts the electrical conductivity and tensile plasticity.Conversely,a higher initial drawing strain can result in insufficient work hardening during the redrawing deformation process,yielding minimal strength improvements.Among the tested alloys,H/3.5 wires show a slight reduction in strength and hardness compared to W and H/4.5 wires but exhibit a significant increase in tensile elongation and electrical conductivity.The tensile strength was 755 MPa,and the electrical conductivity was 47%international-annealed copper standard(IACS).The optimal performance is attributed to the formation of a high-density,ultrafine Fe fiber structure-aligned parallel to the drawing direction,which is achieved through a suitable combination of the drawing process and intermediate annealing.
基金supported by the Beijing Natural Science Foundation(Nos.2242004 and 2232027)the National Natural Science Foundation of China(No.22171021)the China Postdoctoral Science Foundation(No.2023M730245).
文摘Radical anions of electron-deficient perylene diimides(PDI)are attractive near-infrared(NIR)absorbers for photothermal conversion;however,their stability is often compromised by strong aggregation and reoxidation in air.Herein,we present a class of bacterial composites hybridized with a newly synthesized doubly-strapped PDI cyclophane,termed“Gemini Box”(GBox-3^(4+)),which features air-stable PDI radicals for NIR photothermal conversion.The effective spatial isolation provided by the double-sided cationic molecular straps allows GBox-3^(4+)to completely suppress chromophore aggregation,even in concentrated aqueous solutions up to 2 mmol/L,thereby preserving its characteristic fluorescence for live-cell imaging.After incubation of bacteria with GBox-3^(4+),the radical species PDI·-have been found to stably exist in the bacterial composites under ambient conditions,both in aqueous suspension and solid forms.Further experiments demonstrate that the air stability of the radical species relies on the simultaneous presence of the doubly-strapped PDI dye and the bacteria.Moreover,the dye-bacterial composites exhibited an high-efficiency NIR photothermal effect with high durability,enabling their application as photothermal agents for seawater desalination.This work provides a new access to the in situ fabrication of photothermal materials from biomass,relying on the rational molecular design and the unique microenvironment of bacteria.
基金support provided by National Natural Science Foundation of China(Nos.52405364 and 52171110)Jiangsu Funding Program for Excellent Postdoctoral Talent+3 种基金JITRI Advanced Materials R&D Co.Ltdsupport by European Union Horizon 2020 Research and Innovation Program(857470)European Regional Development Fund via the Foundation for Polish Science International Research Agenda PLUS program(MAB PLUS/2018/8)The publication was created within the framework of the project of the Minister of Science and Higher Education,Support for the Activities of Centres of Excellence established in Poland under Horizon 2020,under contract No.MEiN/2023/DIR/3795.
文摘The deformation of Cu–20 wt.%Fe alloy wires leads to a significant improvement in mechanical properties and a decrease in electrical conductivity.Simultaneous improvements in strength and conductivity were achieved by intermediate annealing of drawn Cu–20 wt.%Fe wires.As the annealing temperature increased,the strength of Cu–20 wt.%Fe alloy wire decreased monotonically,but the electrical conductivity first increased and then decreased,reaching its peak value after annealing at 500℃.The decrease in strength is related to dislocation recovery and static recrystallization of Cu and Fe phases,and the increase in electrical conductivity mainly results from the aging precipitation of solid solution Fe.After annealing at 500℃,there was no obvious recrystallization of Cu phase,and many of the nano-Fe particles precipitated from Cu matrix.An annealing temperature of 600℃ induced the recrystallization of Cu matrix and an increase in Fe solid solubility,resulting in a decrease in strength and electrical conductivity.Subsequently,the wires annealed at 500℃ were drawn to 2 mm.Compared with those of the continuously drawn Cu–20 wt.%Fe alloy wires,the deformation ability,strength,and electrical conductivity of Cu–20 wt.%Fe alloy wires subjected to intermediate annealing treatment are significantly greater.This is mainly related to the sufficient precipitation of Fe in Cu matrix and the strengthening of refined Fe fibers parallel to the drawing direction.
基金supported by the National Key Research and Development Program of China(No.2022YFF0609000)the National Natural Science Foundation of China(Nos.51871075,52171034 and 52101037).
文摘Nano-lamellar Ti_(3)Al/TiAl(α2/γ)alloy with significantly improved nanohardness was prepared using dual-wire-fed electron beam-directed energy deposition(EB-DED)in this study.This investigation focused on the evolution of the colony shape and lamellar thickness of the Ti-43Al lamellar alloy at different heights.Nanoindentation tests were employed to evaluate deformation resistance,and numerical simulations provided deeper insights into the deposition process.The results indicate that the colonies are mostly columnar,except for a few equiaxed colonies at the top.Rapid cooling significantly refines theα2 lamellae,resulting in an average spacing of 218 nm and thickness of 41 nm.Additionally,substantial microstrain and a nonequilibrium Al distribution lead to a significant generation ofγvariants,refining theγlamellae to 57 nm.Abundantγ/γ’andα2/γinterfaces,along with fineα2 phases,contribute to improved deformation resistance.Consequently,the nano-lamellar TiAl alloy exhibited a notable 32%increase in nanohardness(8.3 GPa)while maintaining a similar modulus(197 GPa)to conventionally prepared alloys.This study holds significant promise for advancing high-performance TiAl alloys through the dual-wire-fed EB-DED process.
