In order to analyze the impact of dispersal on disease transmission, we establish an SIS epidemic integrodifference model with a nonlinear incidence function. Firstly, the discrete-time SIS epidemic model is establish...In order to analyze the impact of dispersal on disease transmission, we establish an SIS epidemic integrodifference model with a nonlinear incidence function. Firstly, the discrete-time SIS epidemic model is established and studied, including the existence and stability of equilibria, the existence of a flip bifurcation, and chaos. Secondly, the SIS epidemic integrodifference model is built based on the discrete-time SIS epidemic model with dispersal. The dynamic analysis of the model includes the existence and stability of equilibria, the existence of a traveling wave solution, and a minus-one bifurcation. Finally, the results suggest that dispersal causes the system to become more unstable and accelerates the spread of the disease when the equilibrium is unstable. Numerical examples are provided to demonstrate the theoretical results.展开更多
Cerebral ischemia-reperfusion injury(CI/RI)remains the main cause of disability and death in stroke patients due to lack of effective therapeutic strategies.One of the main issues related to CI/RI treatment is the pre...Cerebral ischemia-reperfusion injury(CI/RI)remains the main cause of disability and death in stroke patients due to lack of effective therapeutic strategies.One of the main issues related to CI/RI treatment is the presence of the blood-brain barrier(BBB),which affects the intracerebral delivery of drugs.Ginkgolide B(GB),a major bioactive component in commercially available products of Ginkgo biloba,has been shown significance in CI/RI treatment by regulating inflammatory pathways,oxidative damage,and metabolic disturbance,and seems to be a candidate for stroke recovery.However,limited by its poor hydrophilicity and lipophilicity,the development of GB preparations with good solubility,stability,and the ability to cross the BBB remains a challenge.Herein,we propose a combinatorial strategy by conjugating GB with highly lipophilic docosahexaenoic acid(DHA)to obtain a covalent complex GB-DHA,which can not only enhance the pharmacological effect of GB,but can also be encapsulated in liposomes stably.The amount of finally constructed Lipo@GB-DHA targeting to ischemic hemisphere was validated 2.2 times that of free solution in middle cerebral artery occlusion(MCAO)rats.Compared to the marketed ginkgolide injection,Lipo@GB-DHA significantly reduced infarct volume with better neurobehavioral recovery in MCAO rats after being intravenously administered both at 2 h and 6 h post-reperfusion.Low levels of reactive oxygen species(ROS)and high neuron survival in vitro was maintained via Lipo@GB-DHA treatment,while microglia in the ischemic brain were polarized from the pro-inflammatory M1 phenotype to the tissue-repairing M2 phenotype,which modulate neuroinflammatory and angiogenesis.In addition,Lipo@GB-DHA inhibited neuronal apoptosis via regulating the apoptotic pathway and maintained homeostasis by activating the autophagy pathway.Thus,transforming GB into a lipophilic complex and loading it into liposomes provides a promising nanomedicine strategy with excellent CI/RI therapeutic efficacy and industrialization prospects.展开更多
This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance ...This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.展开更多
We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance...We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance of the cloud is measured to be~1.1 kpc.Using the ^(13)CO data,we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud,which together show a"hub-filament"structure.Filaments F1 and F2 are thermally supercritical.Furthermore,F1 displays clear localized systematic motions in the ^(13)CO position-velocity diagram,which could be explained by accretion along the filament.The mean estimated accretion rate is~132M_(⊙)Myr^(-1).Approximately 150 ^(13)CO clumps are identified in the cloud,of which 39 are gravitationally bound.Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2.Based on the complementary infrared and optical data,we identify~186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1.The calculated star formation rate(SFR)surface densities(∑_(SFR))in the clusters range from 1.4 to 2.5 M_(⊙)Myr^(-1)pc^(-2),with a mean value of~2.0M_(⊙)Myr^(-1)pc^(-2).We therefore regard them as mini-starburst cluster candidates.The comparison between ∑_(SFR) and column density N_(gas) along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud.Along the main filament F1,five bipolar outflows are also found.All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.展开更多
Ultrathin and air-stable Li metal anodes hold great promise toward high-energy and high-safety Li metal batteries(LMBs).However,the application of LMBs is technically impeded by existing Li metal anodes with large thi...Ultrathin and air-stable Li metal anodes hold great promise toward high-energy and high-safety Li metal batteries(LMBs).However,the application of LMBs is technically impeded by existing Li metal anodes with large thickness,high reactivity,and poor performance.Here,we developed a novel and scalable approach for the construction of a 10-μm-thick flexible and air-stable Li metal anode by conformally encapsulating Li within a multifunctional VN film.Specifically,the highly lithiophilic VN layer guides a uniform deposition of Li,while abundant and multilevel pores arising from assembly of ultrathin nanosheets enable a spatially confined immersion of metallic Li,thus ensuring an ultrathin and sandwiched Li anode.More impressively,the strong hydrophobicity of VN surface can effectively improve the stability of anode to humid air,whereas the highly conductive framework greatly boosts charge transfer dynamics and enhances Li utilization and high-rate capability.Benefiting from such fascinating features,the constructed Li-VN anode exhibits ultrastable cycling stability in both ether(2500 h)and carbonate(900 h)electrolytes,respectively.Moreover,even exposed to ambient air for 12 h,the anode still can retain~78%capacity,demonstrating excellent air-defendable capability.This work affords a promising strategy for fabricating high-performance,high-safety,and low-cost LMBs.展开更多
Leaves are crucial for maintaining plant growth and development via photosynthesis,and their function is simultaneously regulated by a suite of phenotypic traits.Although much is known about the genetic architecture o...Leaves are crucial for maintaining plant growth and development via photosynthesis,and their function is simultaneously regulated by a suite of phenotypic traits.Although much is known about the genetic architecture of individual leaf traits,unraveling the genetic basis of complex leafmorphology remains a challenge.Based on the functional correlation and coordination ofmulti-traits,we divided 15 leaf morphological traits into three modules,comprising size(area,length,width,and perimeter),shape(leaf lobes,aspect ratio,circularity,rectangularity,and the relevant ratios),and color(red,green,and blue)for an ornamental tree species,Catalpa bungei.A total of 189 significant single-nucleotide polymorphisms were identified in the leaves of C.bungei:35,82,and 76 in the size,shape,and color modules,respectively.Four quantitative trait loci were common between the size and shape modules,which were closely related according to phenotype correlation,genetic mapping,and mRNA analysis.The color module was independent of them.Synergistic changes in the aspect ratio,leaf lobe,and circularity suggest that these traits could be the core indicators of the leaf shape module.The LAS and SRK genes,associated with leaf lobe and circularity,were found to function in plant defense mechanisms and the growth of leaves.The associations between the SRK and CRK2 genes and the leaf lobe and circularity traits were further verified by RT-qPCR.Our findings demonstrate the importance of integrating multi-trait modules to characterize leaf morphology and facilitate a holistic understanding of the genetic architecture of intraspecific leaf morphology diversity.展开更多
Gravity field is the most basic physical field generated by the material properties of the Earth system.It reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic p...Gravity field is the most basic physical field generated by the material properties of the Earth system.It reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic process inside the Earth.Over the years,a variety of technical means have been used to detect the Earth’s gravity field and supported numerous studies on the global change,resource detection,geological structure movement,water resources change and other related fields of research.Here is part of the progress in surface and marine gravimetry obtained by Chinese geodesy scientists from 2019 to 2023 from the following aspects,including:①Continuous gravity network in Chinese mainland;②Application of superconducting gravity measurement;③Network adjustment for continental-scale gravity survey campaign and data quality control;④Regional time-variable gravity field and its application;⑤Research progress on novel technologies for gravity inversion;⑥Research progress on marine gravity field determination;⑦Application research on marine gravity field.展开更多
[Objectives]This study was conducted to find out the causes of abnormal antler shedding in Père David s deer(Elaphurus davidianus).[Methods]Abnormally-shed antlers were compared with normally-shed antlers in term...[Objectives]This study was conducted to find out the causes of abnormal antler shedding in Père David s deer(Elaphurus davidianus).[Methods]Abnormally-shed antlers were compared with normally-shed antlers in terms of light condition,antler development and bone nutritional status during the abnormal shedding season in the growth area of Père David s deer.[Results]Abnormally-shed antlers had no significant differences in the development of shed antlers,or even in the overall composition of antlers,from those of normal Père David s deer.[Conclusions]Insufficient light was the main cause of abnormal antler shedding in Père David s deer.展开更多
Background:Compared with the fixed-price mechanism,the bookbuilding mechanism has not changed the Chinese IPO high underpricing.How to develop scientific and reasonable IPO pricing,and reduce the high IPO underpricing...Background:Compared with the fixed-price mechanism,the bookbuilding mechanism has not changed the Chinese IPO high underpricing.How to develop scientific and reasonable IPO pricing,and reduce the high IPO underpricing has become a major challenge for China's securities market.Methods:In this paper,using behavioral finance theory and game theory,we build the Initial public offering(IPO)pricing and underpricing models with investors’heterogeneity based on different issuing mechanisms and provide a comparative analysis.Results:Firstly,our models show that IPO underpricing will not be eliminated by using either fixed-price or bookbuilding mechanisms,but when the investors’heterogeneity expectation is the same,lower IPO underpricing can be obtained by the issuing of bookbuilding compared with that of fixed price.Secondly,the IPO underpricing may be larger than that under fixed price if the heterogeneity of investors under bookbuilding is larger than that under fixed price.Thirdly,the numerical analysis results provide strong support for our model.Conclusions:These findings further explains the cause of the high IPO underpricing long-standing in China.展开更多
A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichlo...A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichloroacetic acid solution and centrifuged.The supernatant is purified by a solid phase extraction column.Then,the anions in the solution were purified using SH-AP-1(250 mm×4.0 mm)as a separation column,and measured by a suppressed conductivity detector;the melamine in the solution was separated using SH-CC-4(200 mm×4.0 mm)as a separation column and detected by a UV detector.The results show that the mass concentration of anions had a linear relationship with its peak area within a certain range,the linear correlation coefficient r of the standard curve was greater than 0.999,the recovery rate of spiked samples was 93.4%-104.4%,and the relative standard deviation(RSD)of the measured value(n=6)was less than 4%.Thus,this method is widely suitable for detection of anions and cations in a variety of fertilizer samples.展开更多
Objective:To investigate and analyze the changes of nutritional status in patients undergoing postoperative adjuvant chemotherapy for gastrointestinal tumors based on patient-reported outcomes.Methods:From July 2020 t...Objective:To investigate and analyze the changes of nutritional status in patients undergoing postoperative adjuvant chemotherapy for gastrointestinal tumors based on patient-reported outcomes.Methods:From July 2020 to March 2021,60 patients with gastrointestinal tumor who received adjuvant chemotherapy for the first time after surgery under the oncology department of a third-level,first-class hospital in Shaanxi Province were recruited by convenience sampling.The patient-reported nutritional evaluation outcomes within 24 hours after admission and during the fourth chemotherapy cycle incorporated nutritional risk screening 2002(NRS2002),Functional Assessment of Anorexia/Cachexia Therapy(FAACT),psychological pain screening,Generalized Anxiety Disorder Assessment(GAD-7),Patient Health Questionnaire-9(PHQ-9)to screen for depression,dietary self-assessment,health index scale(EQ-5D),and nutrition supervisor overall assessment scale.Results:The self-reported nutritional evaluation outcomes by adjuvant chemotherapy patients showed an upward trend along with their chemotherapy cycle.Their PG-SGA score,FAACT score,psychological pain score,and EQ-5D score during the fourth cycle were better than those during the first chemotherapy cycle(p<0.05)・Conclusion:Based on the patient・reported nutritional evaluation outcomes,the nutritional status and quality of life of patients with gastrointestinal tumors during chemotherapy did not worsen.Medical staff should timely evaluate the nutritional status of patients with gastrointestinal tumors during chemotherapy and implement reasonable nutritional intervention to improve the quality of life of patients.In the future,patient-reported outcomes should be considered for integration into clinical practice in order to facilitate patient participation in decision-making and improve their medical experience.展开更多
The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped w...The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped with a 2.5-meter diameter primary mirror, an active optics system, and a mosaic CCD camera with 0.73 gigapixels on the primary focal plane for highquality image capture over a 6.5-square-degree field of view. The installation of WFST near the summit of Saishiteng mountain in the Lenghu region is scheduled in summer of 2023, and the operation is planned to start three months later. WFST will scan the northern sky in four optical bands(u, g, r and i) at cadences from hourly/daily in the deep high-cadence survey(DHS) program, to semi-weekly in the wide field survey(WFS) program. During a photometric night, a nominal 30 s exposure in the WFS program will reach a depth of 22.27, 23.32, 22.84, and 22.31(AB magnitudes) in these four bands, respectively, allowing for the detection of a tremendous amount of transients in the low-z universe and a systematic investigation of the variability of Galactic and extragalactic objects. In the DHS program, intranight 90 s exposures as deep as 23(u) and 24 mag(g), in combination with target of opportunity follow-ups, will provide a unique opportunity to explore energetic transients in demand for high sensitivities, including the electromagnetic counterparts of gravitational wave events, supernovae within a few hours of their explosions,tidal disruption events and fast, luminous optical transients even beyond redshift of unity. In addition, the final 6-year co-added images, anticipated to reach g■25.8 mag in WFS or 1.5 mags deeper in DHS, will be of fundamental importance to general Galactic and extragalactic science. The highly uniform legacy surveys of WFST will serve as an indispensable complement to those of the Vera C. Rubin Observatory's Legacy Survey of Space and Time(LSST) that monitors the southern sky.展开更多
Neoadjuvant chemotherapy has become an indispensable weapon against high-risk resectable cancers,which benefits from tumor downstaging.However,the utility of chemotherapeutics alone as a neoadjuvant agent is incapable...Neoadjuvant chemotherapy has become an indispensable weapon against high-risk resectable cancers,which benefits from tumor downstaging.However,the utility of chemotherapeutics alone as a neoadjuvant agent is incapable of generating durable therapeutic benefits to prevent postsurgical tumor metastasis and recurrence.Herein,a tactical nanomissile(TALE),equipped with a guidance system(PD-L1 monoclonal antibody),ammunition(mitoxantrone,Mit),and projectile bodies(tertiary amines modified azobenzene derivatives),is designed as a neoadjuvant chemo-immunotherapy setting,which aims at targeting tumor cells,and fast-releasing Mit owing to the intracellular azoreductase,thereby inducing immunogenic tumor cells death,and forming an in situ tumor vaccine containing damage-associated molecular patterns and multiple tumor antigen epitopes to mobilize the immune system.The formed in situ tumor vaccine can recruit and activate antigen-presenting cells,and ultimately increase the infiltration of CD8^(+)T cells while reversing the immunosuppression microenvironment.Moreover,this approach provokes a robust systemic immune response and immunological memory,as evidenced by preventing 83.3%of mice from postsurgical metastasis or recurrence in the B16-F10 tumor mouse model.Collectively,our results highlight the potential of TALE as a neoadjuvant chemo-immunotherapy paradigm that can not only debulk tumors but generate a long-term immunosurveillance to maximize the durable benefits of neoadjuvant chemotherapy.展开更多
Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycol...Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycolamide(TCHDGA),was synthesized,and the separation performance of scandium from impurity metal ions(Ti,Mn,Ba,Fe,Al and Mg)was investigated,The effects of mixing time,acid concentration and temperature on the scandium extraction were considered.The extraction mechanism was studied by infrared spectroscopy and the Equimole Series Method.Under optimized conditions,the extractant shows a strong affinity to scandium in the nitric acid medium and high extraction separation factors between scandium and these impurity metal ions,A process for the purification of scandium was established.The crude product obtained from titanium white waste acid,95%purity scandium oxide,can be purified to 99.99%after only one step of extraction,scrubbing,and stripping:This technology is economical and straightforward and can realize the high-value recovery of scandium in the titanium white waste acid.展开更多
Electrospun nanofiber/hydrogel composites combine the excellent biochemical properties of hydrogel with the biomimetic nature of electrospun fibers,and have attracted widespread attention in the last few years.Besides...Electrospun nanofiber/hydrogel composites combine the excellent biochemical properties of hydrogel with the biomimetic nature of electrospun fibers,and have attracted widespread attention in the last few years.Besides,nanofiber/hydrogel composites with tunable mechanical properties can mimic the microstructure of extracellular matrix(ECM)of various tissues and the microenvironment of different cells.These features enable electrospun fiber/hydrogel composites have uniquely advantageous for tissue repair.However,a comprehensive review of electrospun fiber/hydrogel composites as tissue engineering scaffolds is still lacking.Thus,this article systematically reviewed the preparation of electrospun fiber/hydrogel composites and their application in tissue engineering.First,the preparation strategies of electrospun fiber/hydrogel composites are classified and discussed.Second,the application of electrospun fiber/hydrogel-based scaffolds in tissue engineering,involving skin,blood vessel,nerve,bone and other tissue engineering,are summarized.Finally,future research directions for functional electrospun fiber/hydrogel scaffold materials are proposed.展开更多
Endogenous electric fields(EFs)are capable of regulating the behaviors of skin cells in wound healing.However,majority of current dressings are primarily engaged in the passive repair of defective tissue,as they lack ...Endogenous electric fields(EFs)are capable of regulating the behaviors of skin cells in wound healing.However,majority of current dressings are primarily engaged in the passive repair of defective tissue,as they lack the ability to actively respond to physiological electrical signals.In this work,a series of nanofibrous membranes(NFMs)were fabricated by coaxial electrospinning,combining the good mechanical properties of poly(ε-caprolactone)(PCL),the bioactivity of gelatin and the electroactivity of Ti_(3)C_(2)T_(x)MXene,as electroactive and antibacterial dressings for cutaneous wound healing.The obtained NFMs exhibited suitable mechanical properties and hydrophilicity,excellent electroactivity,antibacterial activity,and biocompatibility.Especially,Ti_(3)C_(2)T_(x)MXene/PCL/gelatin-6(MPG-6,6 wt.%of Ti_(3)C_(2)T_(x)MXene in sheath spinning liquids)showed the optimal conductivity and antibacterial activity.Excitingly,this scaffold significantly promoted the adhesion,proliferation,and migration of NIH 3T3 cells under the electrical stimulation(ES).The in vivo evaluation in a full-thickness wounds defect model demonstrated that the MPG-6 films significantly accelerated wound closure,increased granulation tissue formation,increased collagen deposition,and promoted wound vascularization.In summary,the versatile scaffold is expected to be an ideal candidate as wound dressings due to its ability to promote the transmission of physiological electrical signals and thus improved the therapeutic outcomes of wound regeneration.展开更多
文摘In order to analyze the impact of dispersal on disease transmission, we establish an SIS epidemic integrodifference model with a nonlinear incidence function. Firstly, the discrete-time SIS epidemic model is established and studied, including the existence and stability of equilibria, the existence of a flip bifurcation, and chaos. Secondly, the SIS epidemic integrodifference model is built based on the discrete-time SIS epidemic model with dispersal. The dynamic analysis of the model includes the existence and stability of equilibria, the existence of a traveling wave solution, and a minus-one bifurcation. Finally, the results suggest that dispersal causes the system to become more unstable and accelerates the spread of the disease when the equilibrium is unstable. Numerical examples are provided to demonstrate the theoretical results.
基金This research was funded by the National Natural Science Foundation of China(No.81773911,81690263 and 81573616)the Development Project of Shanghai Peak Disciplines-Integrated Medicine(No.20180101).
文摘Cerebral ischemia-reperfusion injury(CI/RI)remains the main cause of disability and death in stroke patients due to lack of effective therapeutic strategies.One of the main issues related to CI/RI treatment is the presence of the blood-brain barrier(BBB),which affects the intracerebral delivery of drugs.Ginkgolide B(GB),a major bioactive component in commercially available products of Ginkgo biloba,has been shown significance in CI/RI treatment by regulating inflammatory pathways,oxidative damage,and metabolic disturbance,and seems to be a candidate for stroke recovery.However,limited by its poor hydrophilicity and lipophilicity,the development of GB preparations with good solubility,stability,and the ability to cross the BBB remains a challenge.Herein,we propose a combinatorial strategy by conjugating GB with highly lipophilic docosahexaenoic acid(DHA)to obtain a covalent complex GB-DHA,which can not only enhance the pharmacological effect of GB,but can also be encapsulated in liposomes stably.The amount of finally constructed Lipo@GB-DHA targeting to ischemic hemisphere was validated 2.2 times that of free solution in middle cerebral artery occlusion(MCAO)rats.Compared to the marketed ginkgolide injection,Lipo@GB-DHA significantly reduced infarct volume with better neurobehavioral recovery in MCAO rats after being intravenously administered both at 2 h and 6 h post-reperfusion.Low levels of reactive oxygen species(ROS)and high neuron survival in vitro was maintained via Lipo@GB-DHA treatment,while microglia in the ischemic brain were polarized from the pro-inflammatory M1 phenotype to the tissue-repairing M2 phenotype,which modulate neuroinflammatory and angiogenesis.In addition,Lipo@GB-DHA inhibited neuronal apoptosis via regulating the apoptotic pathway and maintained homeostasis by activating the autophagy pathway.Thus,transforming GB into a lipophilic complex and loading it into liposomes provides a promising nanomedicine strategy with excellent CI/RI therapeutic efficacy and industrialization prospects.
基金supported in part by the National Natural Science Foundation of China(61825305,62171274,U1933125,U2241228,62273019)the Shanghai Science and Technology Major Project(2021SHZDZX)+2 种基金the National Natural Science Foundation of China through the Main Research Projecton Machine Behavior and Human-Machine Collaborated Decision Making Methodology(72192820)the Third Research Projecton Human Behavior in HumanMachine Collaboration(72192822)the China Postdoctoral Science Foundation(2022M710093)。
文摘This paper presents a finite-time sideslip differentiator-based line-of-sight(LOS)guidance method for robust path following of snake robots.Firstly,finite-time stable sideslip differentiator and adaptive LOS guidance method are proposed to counteract sideslip drift caused by cross-track velocity.The proposed differentiator can accurately observe the cross-track error and sideslip angle for snake robots to avoid errors caused by calculating sideslip angle approximately.In our method,the designed piecewise auxiliary function guarantees the finite-time stability of position errors.Secondly,for the case of external disturbances and state constraints,a Barrier Lyapunov functionbased backstepping adaptive path following controller is presented to improve the robot’s robustness.The uniform ultimate boundedness of the closed-loop system is proved by analyzing stability.Additionally,a gait frequency adjustment-based virtual velocity control input is derived to achieve the exponential convergence of the tangential velocity.At last,the availability and superiority of this work are shown through simulation and experiment results.
基金supported by the National Key R&D Program of China(grant No.2017YFA0402702)the National Natural Science Foundation of China(NSFC,Grant Nos.12041305,12173090 and 12073079)+2 种基金the CAS International Cooperation Program(grant No.114332KYSB20190009)sponsored by the National Key R&D Program of China with grant 2017YFA0402701the CAS Key Research Program of Frontier Sciences with grant QYZDJ-SSW-SLH047。
文摘We present large-scale(2°×2°)observations toward the molecular cloud M120.1+3.0,using ^(12)CO,^(13)CO and C^(18)O(J=1-0)data from the Purple Mountain Observatory 13.7 m millimeter telescope.The distance of the cloud is measured to be~1.1 kpc.Using the ^(13)CO data,we identify a main filament F1 and two sub-filaments F2 and F3 in the cloud,which together show a"hub-filament"structure.Filaments F1 and F2 are thermally supercritical.Furthermore,F1 displays clear localized systematic motions in the ^(13)CO position-velocity diagram,which could be explained by accretion along the filament.The mean estimated accretion rate is~132M_(⊙)Myr^(-1).Approximately 150 ^(13)CO clumps are identified in the cloud,of which 39 are gravitationally bound.Most of these virialized clumps are well distributed along the supercritical filaments F1 and F2.Based on the complementary infrared and optical data,we identify~186 young stellar objects in the observed area and extract five clusters within the dense ridge of F1.The calculated star formation rate(SFR)surface densities(∑_(SFR))in the clusters range from 1.4 to 2.5 M_(⊙)Myr^(-1)pc^(-2),with a mean value of~2.0M_(⊙)Myr^(-1)pc^(-2).We therefore regard them as mini-starburst cluster candidates.The comparison between ∑_(SFR) and column density N_(gas) along the skeleton of F1 suggests that star formation is closely related to the dense gas in the cloud.Along the main filament F1,five bipolar outflows are also found.All these results indicate intense star-forming activities in the M120.1+3.0 molecular cloud.
基金financialy supported by National Natural Science Foundation of China(52002297,51974208,and 21875080)Wuhan Yellow Crane Talents ProgramNumerical calculation is supported by High-Performance Computing Center of Wuhan University of Science and Technology)
文摘Ultrathin and air-stable Li metal anodes hold great promise toward high-energy and high-safety Li metal batteries(LMBs).However,the application of LMBs is technically impeded by existing Li metal anodes with large thickness,high reactivity,and poor performance.Here,we developed a novel and scalable approach for the construction of a 10-μm-thick flexible and air-stable Li metal anode by conformally encapsulating Li within a multifunctional VN film.Specifically,the highly lithiophilic VN layer guides a uniform deposition of Li,while abundant and multilevel pores arising from assembly of ultrathin nanosheets enable a spatially confined immersion of metallic Li,thus ensuring an ultrathin and sandwiched Li anode.More impressively,the strong hydrophobicity of VN surface can effectively improve the stability of anode to humid air,whereas the highly conductive framework greatly boosts charge transfer dynamics and enhances Li utilization and high-rate capability.Benefiting from such fascinating features,the constructed Li-VN anode exhibits ultrastable cycling stability in both ether(2500 h)and carbonate(900 h)electrolytes,respectively.Moreover,even exposed to ambient air for 12 h,the anode still can retain~78%capacity,demonstrating excellent air-defendable capability.This work affords a promising strategy for fabricating high-performance,high-safety,and low-cost LMBs.
基金supported by the National Key Research and Development Plan of China(2021YFD2200202)the National Natural Science Foundation of China(32001337)。
文摘Leaves are crucial for maintaining plant growth and development via photosynthesis,and their function is simultaneously regulated by a suite of phenotypic traits.Although much is known about the genetic architecture of individual leaf traits,unraveling the genetic basis of complex leafmorphology remains a challenge.Based on the functional correlation and coordination ofmulti-traits,we divided 15 leaf morphological traits into three modules,comprising size(area,length,width,and perimeter),shape(leaf lobes,aspect ratio,circularity,rectangularity,and the relevant ratios),and color(red,green,and blue)for an ornamental tree species,Catalpa bungei.A total of 189 significant single-nucleotide polymorphisms were identified in the leaves of C.bungei:35,82,and 76 in the size,shape,and color modules,respectively.Four quantitative trait loci were common between the size and shape modules,which were closely related according to phenotype correlation,genetic mapping,and mRNA analysis.The color module was independent of them.Synergistic changes in the aspect ratio,leaf lobe,and circularity suggest that these traits could be the core indicators of the leaf shape module.The LAS and SRK genes,associated with leaf lobe and circularity,were found to function in plant defense mechanisms and the growth of leaves.The associations between the SRK and CRK2 genes and the leaf lobe and circularity traits were further verified by RT-qPCR.Our findings demonstrate the importance of integrating multi-trait modules to characterize leaf morphology and facilitate a holistic understanding of the genetic architecture of intraspecific leaf morphology diversity.
基金Open Fund of Hubei Luojia Laboratory(No.220100033)National Natural Science Foundation of China(Nos.42174108,42192535,42242015)。
文摘Gravity field is the most basic physical field generated by the material properties of the Earth system.It reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic process inside the Earth.Over the years,a variety of technical means have been used to detect the Earth’s gravity field and supported numerous studies on the global change,resource detection,geological structure movement,water resources change and other related fields of research.Here is part of the progress in surface and marine gravimetry obtained by Chinese geodesy scientists from 2019 to 2023 from the following aspects,including:①Continuous gravity network in Chinese mainland;②Application of superconducting gravity measurement;③Network adjustment for continental-scale gravity survey campaign and data quality control;④Regional time-variable gravity field and its application;⑤Research progress on novel technologies for gravity inversion;⑥Research progress on marine gravity field determination;⑦Application research on marine gravity field.
基金Supported by Science and Technology Research Project of Hubei Provincial Department of Education (B2018522).
文摘[Objectives]This study was conducted to find out the causes of abnormal antler shedding in Père David s deer(Elaphurus davidianus).[Methods]Abnormally-shed antlers were compared with normally-shed antlers in terms of light condition,antler development and bone nutritional status during the abnormal shedding season in the growth area of Père David s deer.[Results]Abnormally-shed antlers had no significant differences in the development of shed antlers,or even in the overall composition of antlers,from those of normal Père David s deer.[Conclusions]Insufficient light was the main cause of abnormal antler shedding in Père David s deer.
基金supports from National Natural Science Foundation of China(71361005)。
文摘Background:Compared with the fixed-price mechanism,the bookbuilding mechanism has not changed the Chinese IPO high underpricing.How to develop scientific and reasonable IPO pricing,and reduce the high IPO underpricing has become a major challenge for China's securities market.Methods:In this paper,using behavioral finance theory and game theory,we build the Initial public offering(IPO)pricing and underpricing models with investors’heterogeneity based on different issuing mechanisms and provide a comparative analysis.Results:Firstly,our models show that IPO underpricing will not be eliminated by using either fixed-price or bookbuilding mechanisms,but when the investors’heterogeneity expectation is the same,lower IPO underpricing can be obtained by the issuing of bookbuilding compared with that of fixed price.Secondly,the IPO underpricing may be larger than that under fixed price if the heterogeneity of investors under bookbuilding is larger than that under fixed price.Thirdly,the numerical analysis results provide strong support for our model.Conclusions:These findings further explains the cause of the high IPO underpricing long-standing in China.
文摘A chromatographic analysis method for determining inorganic anions and melamine in fertilizers was established using ion chromatography(IC).The fertilizer samples were extracted by ultrasonic method with 7 g/L trichloroacetic acid solution and centrifuged.The supernatant is purified by a solid phase extraction column.Then,the anions in the solution were purified using SH-AP-1(250 mm×4.0 mm)as a separation column,and measured by a suppressed conductivity detector;the melamine in the solution was separated using SH-CC-4(200 mm×4.0 mm)as a separation column and detected by a UV detector.The results show that the mass concentration of anions had a linear relationship with its peak area within a certain range,the linear correlation coefficient r of the standard curve was greater than 0.999,the recovery rate of spiked samples was 93.4%-104.4%,and the relative standard deviation(RSD)of the measured value(n=6)was less than 4%.Thus,this method is widely suitable for detection of anions and cations in a variety of fertilizer samples.
文摘Objective:To investigate and analyze the changes of nutritional status in patients undergoing postoperative adjuvant chemotherapy for gastrointestinal tumors based on patient-reported outcomes.Methods:From July 2020 to March 2021,60 patients with gastrointestinal tumor who received adjuvant chemotherapy for the first time after surgery under the oncology department of a third-level,first-class hospital in Shaanxi Province were recruited by convenience sampling.The patient-reported nutritional evaluation outcomes within 24 hours after admission and during the fourth chemotherapy cycle incorporated nutritional risk screening 2002(NRS2002),Functional Assessment of Anorexia/Cachexia Therapy(FAACT),psychological pain screening,Generalized Anxiety Disorder Assessment(GAD-7),Patient Health Questionnaire-9(PHQ-9)to screen for depression,dietary self-assessment,health index scale(EQ-5D),and nutrition supervisor overall assessment scale.Results:The self-reported nutritional evaluation outcomes by adjuvant chemotherapy patients showed an upward trend along with their chemotherapy cycle.Their PG-SGA score,FAACT score,psychological pain score,and EQ-5D score during the fourth cycle were better than those during the first chemotherapy cycle(p<0.05)・Conclusion:Based on the patient・reported nutritional evaluation outcomes,the nutritional status and quality of life of patients with gastrointestinal tumors during chemotherapy did not worsen.Medical staff should timely evaluate the nutritional status of patients with gastrointestinal tumors during chemotherapy and implement reasonable nutritional intervention to improve the quality of life of patients.In the future,patient-reported outcomes should be considered for integration into clinical practice in order to facilitate patient participation in decision-making and improve their medical experience.
基金supported by the Cyrus Chun Ying Tang Foundationsthe Major Science and Technology Project of Qinghai Province(Grant No.2019ZJ-A10)+4 种基金the 111 Project for“Observational and Theoretical Research on Dark Matter and Dark Energy”(Grant No.B23042)the National Natural Science Foundation of China(Grant Nos.11833007,12073078,12173088,12192221,12192224,12233008,12273036,and 12273113)the Frontier Scientific Research Program of Deep Space Exploration Laboratory(Grant No.2022-QYKYJH-HXYF-012)the support from the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2030002009)Project for Young Scientists in Basic Research of the Chinese Academy of Sciences(Grant No.YSBR-061),respectively。
文摘The Wide Field Survey Telescope(WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China(USTC) and the Purple Mountain Observatory(PMO). It is equipped with a 2.5-meter diameter primary mirror, an active optics system, and a mosaic CCD camera with 0.73 gigapixels on the primary focal plane for highquality image capture over a 6.5-square-degree field of view. The installation of WFST near the summit of Saishiteng mountain in the Lenghu region is scheduled in summer of 2023, and the operation is planned to start three months later. WFST will scan the northern sky in four optical bands(u, g, r and i) at cadences from hourly/daily in the deep high-cadence survey(DHS) program, to semi-weekly in the wide field survey(WFS) program. During a photometric night, a nominal 30 s exposure in the WFS program will reach a depth of 22.27, 23.32, 22.84, and 22.31(AB magnitudes) in these four bands, respectively, allowing for the detection of a tremendous amount of transients in the low-z universe and a systematic investigation of the variability of Galactic and extragalactic objects. In the DHS program, intranight 90 s exposures as deep as 23(u) and 24 mag(g), in combination with target of opportunity follow-ups, will provide a unique opportunity to explore energetic transients in demand for high sensitivities, including the electromagnetic counterparts of gravitational wave events, supernovae within a few hours of their explosions,tidal disruption events and fast, luminous optical transients even beyond redshift of unity. In addition, the final 6-year co-added images, anticipated to reach g■25.8 mag in WFS or 1.5 mags deeper in DHS, will be of fundamental importance to general Galactic and extragalactic science. The highly uniform legacy surveys of WFST will serve as an indispensable complement to those of the Vera C. Rubin Observatory's Legacy Survey of Space and Time(LSST) that monitors the southern sky.
基金financially supported by the National Natural Science Foundation of China(82172094)Funds of Sichuan Province for Distinguished Young Scholar(2021JDJQ0037,China)1.3.5 project for disciplines of excellence,West China Hospital,Sichuan University(ZYYC08002,China)。
文摘Neoadjuvant chemotherapy has become an indispensable weapon against high-risk resectable cancers,which benefits from tumor downstaging.However,the utility of chemotherapeutics alone as a neoadjuvant agent is incapable of generating durable therapeutic benefits to prevent postsurgical tumor metastasis and recurrence.Herein,a tactical nanomissile(TALE),equipped with a guidance system(PD-L1 monoclonal antibody),ammunition(mitoxantrone,Mit),and projectile bodies(tertiary amines modified azobenzene derivatives),is designed as a neoadjuvant chemo-immunotherapy setting,which aims at targeting tumor cells,and fast-releasing Mit owing to the intracellular azoreductase,thereby inducing immunogenic tumor cells death,and forming an in situ tumor vaccine containing damage-associated molecular patterns and multiple tumor antigen epitopes to mobilize the immune system.The formed in situ tumor vaccine can recruit and activate antigen-presenting cells,and ultimately increase the infiltration of CD8^(+)T cells while reversing the immunosuppression microenvironment.Moreover,this approach provokes a robust systemic immune response and immunological memory,as evidenced by preventing 83.3%of mice from postsurgical metastasis or recurrence in the B16-F10 tumor mouse model.Collectively,our results highlight the potential of TALE as a neoadjuvant chemo-immunotherapy paradigm that can not only debulk tumors but generate a long-term immunosurveillance to maximize the durable benefits of neoadjuvant chemotherapy.
基金supported by the National Natural Science Foundation of China(21876062)。
文摘Recovery of scandium from titanium white waste acid is an essential source of scandium.Simple and economical production of high purity scandium remains a challenge.A new extractant,N,N,N’,N’-tetracyclohexyl-diglycolamide(TCHDGA),was synthesized,and the separation performance of scandium from impurity metal ions(Ti,Mn,Ba,Fe,Al and Mg)was investigated,The effects of mixing time,acid concentration and temperature on the scandium extraction were considered.The extraction mechanism was studied by infrared spectroscopy and the Equimole Series Method.Under optimized conditions,the extractant shows a strong affinity to scandium in the nitric acid medium and high extraction separation factors between scandium and these impurity metal ions,A process for the purification of scandium was established.The crude product obtained from titanium white waste acid,95%purity scandium oxide,can be purified to 99.99%after only one step of extraction,scrubbing,and stripping:This technology is economical and straightforward and can realize the high-value recovery of scandium in the titanium white waste acid.
基金supported in part by the Key Research and Development Program of Shaanxi(No.2022SF-200)the Fund of Jiangsu Key Laboratory of Advanced Functional Polymers Design and Application in Soochow University(No.KJS2007).
文摘Electrospun nanofiber/hydrogel composites combine the excellent biochemical properties of hydrogel with the biomimetic nature of electrospun fibers,and have attracted widespread attention in the last few years.Besides,nanofiber/hydrogel composites with tunable mechanical properties can mimic the microstructure of extracellular matrix(ECM)of various tissues and the microenvironment of different cells.These features enable electrospun fiber/hydrogel composites have uniquely advantageous for tissue repair.However,a comprehensive review of electrospun fiber/hydrogel composites as tissue engineering scaffolds is still lacking.Thus,this article systematically reviewed the preparation of electrospun fiber/hydrogel composites and their application in tissue engineering.First,the preparation strategies of electrospun fiber/hydrogel composites are classified and discussed.Second,the application of electrospun fiber/hydrogel-based scaffolds in tissue engineering,involving skin,blood vessel,nerve,bone and other tissue engineering,are summarized.Finally,future research directions for functional electrospun fiber/hydrogel scaffold materials are proposed.
基金This research was financially supported by the Key Research and Development Program of Shaanxi(No.2022SF-200)the Fund of Jiangsu Key Laboratory of Advanced Functional Polymers Design and Application in Soochow University(No.KJS2007)the Undergraduate Training Programs of Shaanxi Province for Innovation and Entrepreneurship(No.S202210699534).
文摘Endogenous electric fields(EFs)are capable of regulating the behaviors of skin cells in wound healing.However,majority of current dressings are primarily engaged in the passive repair of defective tissue,as they lack the ability to actively respond to physiological electrical signals.In this work,a series of nanofibrous membranes(NFMs)were fabricated by coaxial electrospinning,combining the good mechanical properties of poly(ε-caprolactone)(PCL),the bioactivity of gelatin and the electroactivity of Ti_(3)C_(2)T_(x)MXene,as electroactive and antibacterial dressings for cutaneous wound healing.The obtained NFMs exhibited suitable mechanical properties and hydrophilicity,excellent electroactivity,antibacterial activity,and biocompatibility.Especially,Ti_(3)C_(2)T_(x)MXene/PCL/gelatin-6(MPG-6,6 wt.%of Ti_(3)C_(2)T_(x)MXene in sheath spinning liquids)showed the optimal conductivity and antibacterial activity.Excitingly,this scaffold significantly promoted the adhesion,proliferation,and migration of NIH 3T3 cells under the electrical stimulation(ES).The in vivo evaluation in a full-thickness wounds defect model demonstrated that the MPG-6 films significantly accelerated wound closure,increased granulation tissue formation,increased collagen deposition,and promoted wound vascularization.In summary,the versatile scaffold is expected to be an ideal candidate as wound dressings due to its ability to promote the transmission of physiological electrical signals and thus improved the therapeutic outcomes of wound regeneration.
