The dendrite morphologies and spacings of directionally solidified DZ125 superalloy were investigated under high thermal gradient about 500 K/cm. The results reveal that, with increasing cooling rate, both the spacing...The dendrite morphologies and spacings of directionally solidified DZ125 superalloy were investigated under high thermal gradient about 500 K/cm. The results reveal that, with increasing cooling rate, both the spacings of primary and secondary dendrite arms decrease, and the dendrite morphologies transit from coarse to superfme dendrite. The secondary dendrite arms trend to be refined and be well developed, and the tertiary dendrite will occur. The predictions of the Kurz/Fisher model and the Hunt/Lu model accord basically with the experimental data for primary dendrite arm spacing. The regression equation of the primary dendrite arm spacings 21 and the cooling rate Vc is λ1 = 0.013 Vc^-0.32. The regression equation of the secondary dendrite arm spacing λ2 and the cooling rate Vc is λ2 = 0.00258 Vc^-0.31, which gives good agreement with the Feurer/Wunderlin model.展开更多
The microstructure scales of dendrites, such as primary and secondary dendrite arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic regions, which determine the pr...The microstructure scales of dendrites, such as primary and secondary dendrite arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic regions, which determine the properties of solidified structures. Investigations on primary and secondary dendrite arm spacings of primary a-phase during directionally solidified Pb-26wt%Bi hypo-peritectic alloy were carried out in this research, and systematic studies were conducted using cylindrical samples with different diameters （Ф = 1.8 and 7.0 mm） in order to analyze the effects of sample diameter on the primary and secondary dendrite arm spacings. In this work, the dependence of dendrite arm spacings on growth velocity was established. In addition, the experimental data concerning the primary and secondary dendrite ann spacings were compared with the main predictive dendritic models from the literatures. A comparison between experimental results for dendrite arm spacings of the 1.8-mm-diameter sample and 7.0-ram-diameter sample was also conducted.展开更多
Fatigue crack growth experiments were per- formed on A1 alloy LD 10 and Ti-6A1-4V alloy. Fatigue striation spacings and the deviation angles between the direction of micro-crack growth and that of macro-crack growth w...Fatigue crack growth experiments were per- formed on A1 alloy LD 10 and Ti-6A1-4V alloy. Fatigue striation spacings and the deviation angles between the direction of micro-crack growth and that of macro-crack growth were quanti- tatively measured on fracture surface using scanning electron microscope. A statistical model of the relationship between striation spacings and fatigue crack propagation rates was developed on the basis of a statistical analysis of the deviation angles, Good agreement between experimental results and theoretical results calculated with the present model was obtained.展开更多
The interaction between the TBM cutters and the rock mass is the main factor in TBM tunneling.The rock damage characteristics under the cutters are directly associated with the cutting efficiency and rock fragmentatio...The interaction between the TBM cutters and the rock mass is the main factor in TBM tunneling.The rock damage characteristics under the cutters are directly associated with the cutting efficiency and rock fragmentation mechanism.Four sets of linear cutting tests were performed in this paper with various cutter spacing to obtain the cutter force and muck.Then,fluorescence experiments were conducted to evaluate the rock damage characteristics by sawing the rock samples after the tests.The findings reveal that the effect of cutter spacing on mean normal force increases gradually as penetration depth increases,but only affects mean rolling force for penetration depths exceeding 2.0 mm.The optimal cutting efficiency is achieved at an S/P of 20-60.The area ratio of the crushed zone and the crack dense zone decreases as cutter spacing increases while that of the crack sparse zone increases.Moreover,increasing the cutter force or cutting spacing at the same penetration depth expands the crack sparse zone,increasing the cutting efficiency.This study could provide ideas and data support for designing the TBM cutterhead and optimizing the TBM operation.展开更多
Effective adjustment of fertilization spacing and amounts for different plant distances is beneficial to increase production and reduce the amount of fertilizer used.In order to achieve such a target,an electric-ferti...Effective adjustment of fertilization spacing and amounts for different plant distances is beneficial to increase production and reduce the amount of fertilizer used.In order to achieve such a target,an electric-fertilizing vehicle with staggered fan-shaped openings in a fertilization device is proposed here,and its fertilization spacing and amounts are controlled by a control system and mobile phone-based programs.Further validating multivariable effects on fertilization spacing and amounts,such as openings,rotary speeds,and moving parameters of the vehicle,an integration discrete element model(DEM)is established so that the feasibility of the fertilization device could be evaluated before manufacturing and testing.Finally,it is reflected through field-simulated experiments that fertilizer spacing ranges from 0.27 to 5.45 m.Compared with simulated results,the absolute error varies from-0.08 to 0.05 m,and the maximum relative error is about-5.67%.Therefore,the uniform and stable fertilization for different plant spacing is semi-actively achieved by the designed device and a control system with mobile phone-based programs.The proposed simulation model is feasible,thus presenting a good reference for designing these components.展开更多
背景:新型生物材料不仅提供必要的机械支撑,还能促进细胞增殖和分化、诱导骨再生,从而改善治疗效果,为骨再生技术的发展提供了新的视角和方法。目的:通过文献计量学方法可视化分析生物材料在骨再生领域的研究状况及发展前景。方法:在Web...背景:新型生物材料不仅提供必要的机械支撑,还能促进细胞增殖和分化、诱导骨再生,从而改善治疗效果,为骨再生技术的发展提供了新的视角和方法。目的:通过文献计量学方法可视化分析生物材料在骨再生领域的研究状况及发展前景。方法:在Web of Science核心数据库中,精选了数据库建库至2024-09-24关于骨再生和生物材料领域最具影响力的文献500篇,运用VOSviewer和CiteSpace两款工具进行深入的计量学可视化分析,以揭示该领域的研究趋势和核心文献结果与结论:在所选的500篇文献中,中国和美国在发表论文数量和被引用率方面均占据领先地位,而常江是发文最多的作者,发表文章最多的期刊为Acta Biomaterialia。骨再生和材料学是一个跨学科的研究范畴,涵盖了材料科学、生物医学工程、细胞生物学、分子生物学等多个学科领域。骨修复材料的研究正从传统的生物惰性材料向生物活性材料转变,这些材料不仅提供机械支撑,还能促进细胞增殖和分化,诱导骨再生。合成骨修复材料因丰富的来源、可调节的物理化学特性以及较低的免疫排斥和疾病传播风险,正逐渐替代传统材料,成为临床骨移植手术的首选。研究者们正在不断改进这些材料的生物相容性、仿生特性、骨传导性和骨诱导性,使其更接近天然骨,前沿主要集中在生物活性陶瓷、3D打印、水凝胶、壳聚糖、羟基磷灰石等材料。新型材料在骨再生领域中的作用至关重要,随着材料科学技术的不断进步,这些新型材料在骨再生领域的应用前景非常广阔,有望为骨缺损治疗提供更为有效和个性化的治疗方案。展开更多
Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological me...Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.展开更多
The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,p...The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,particularly given the current lack of disease-modifying treatments.The glymphatic system,a recently identified perivascular fluid transport network,is crucial for clearing neurotoxic proteins.This review aims to synthesize current knowledge on the role of the glymphatic system inα-synuclein clearance and its implications for the pathology of Parkinson's disease while emphasizing potential therapeutic strategies and areas for future research.The review begins with an overview of the glymphatic system and details its anatomical structure and physiological functions that facilitate cerebrospinal fluid circulation and waste clearance.It summarizes emerging evidence from neuroimaging and experimental studies that highlight the close correlation between the glymphatic system and clinical symptom severity in patients with Parkinson's disease,as well as the effect of glymphatic dysfunction onα-synuclein accumulation in Parkinson's disease models.Subsequently,the review summarizes the mechanisms of glymphatic system impairment in Parkinson's disease,including sleep disturbances,aquaporin-4 impairment,and mitochondrial dysfunction,all of which diminish glymphatic system efficiency.This creates a vicious cycle that exacerbatesα-synuclein accumulation and worsens Parkinson's disease.The therapeutic perspectives section outlines strategies for enhancing glymphatic activity,such as improving sleep quality and pharmacologically targeting aquaporin-4 or its subcellular localization.Promising interventions include deep brain stimulation,melatonin supplementation,γ-aminobutyric acid modulation,and non-invasive methods(such as exercise and bright-light therapy),multisensoryγstimulation,and ultrasound therapy.Moreover,identifying neuroimaging biomarkers to assess glymphatic flow as an indicator ofα-synuclein burden could refine Parkinson's disease diagnosis and track disease progression.In conclusion,the review highlights the critical role of the glymphatic system inα-synuclein clearance and its potential as a therapeutic target in Parkinson's disease.It advocates for further research to elucidate the specific mechanisms by which the glymphatic system clears misfoldedα-synuclein and the development of imaging biomarkers to monitor glymphatic activity in patients with Parkinson's disease.Findings from this review suggest that enhancing glymphatic clearance is a promising strategy for reducingα-synuclein deposits and mitigating the progression of Parkinson's disease.展开更多
Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization...Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.展开更多
In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale in...In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale inequalities of mixed quasi-martingale Hardy spaces.Moreover,we furnish sufficient conditions for the boundedness ofσ-sublinear operators in these spaces.These findings extend the existing conclusions regarding mixed quasi-martingale Hardy spaces defined with the help of the mixed L_(p)-norm.展开更多
Space exploration is significant for scientific innovation,resource utilization,and planetary security.Space exploration involves several systems including satellites,space suits,communication systems,and robotics,whi...Space exploration is significant for scientific innovation,resource utilization,and planetary security.Space exploration involves several systems including satellites,space suits,communication systems,and robotics,which have to function under harsh space conditions such as extreme temperatures(−270 to 1650℃),microgravity(10^(-6)g),unhealthy humidity(<20%RH or>60%RH),high atmospheric pressure(~1450 psi),and radiation(4000–5000 mSv).Conventional energy-harvesting technologies(solar cells,fuel cells,and nuclear energy),that are normally used to power these space systems have certain limitations(e.g.,sunlight dependence,weight,degradation,big size,high cost,low capacity,radioactivity,complexity,and low efficiency).The constraints in conventional energy resources have made it imperative to look for non-conventional yet efficient alternatives.A great potential for enhancing efficiency,sustainability,and mission duration in space exploration can be offered by integrating triboelectric nanogenerators(TENGs)with existing energy sources.Recently,the potential of TENG including energy harvesting(from vibrations/movements in satellites and spacecraft),self-powered sensing,and microgravity,for multiple applications in different space missions has been discussed.This review comprehensively covers the use of TENGs for various space applications,such as planetary exploration missions(Mars environment monitoring),manned space equipment,In-orbit robotic operations/collision monitoring,spacecraft’s design and structural health monitoring,Aeronautical systems,and conventional energy harvesting(solar and nuclear).This review also discusses the use of self-powered TENG sensors for deep space object perception.At the same time,this review compares TENGs with conventional energy harvesting technologies for space systems.Lastly,this review talks about energy harvesting in satellites,TENG-based satellite communication systems,and future practical implementation challenges(with possible solutions).展开更多
In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operato...In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operator of M_(r)^(5) is diagonalizable,then the mean curvature is a constant.As an application,we find some types of biharmonic hypersurfaces of N_(p)^(6)(c)are minimal.展开更多
Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development...Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development of mechanization,wide-row spacing substrate cultivation became an optimize mode of the greenhouse cucumber cultivation,aligning with the trend of intelligent agriculture.To determine the optimal nutrient solution supply amount(NS)and supply frequency(SF)for promoting the integrated growth of cucumber under wide-row spacing substrate cultivation,we explored the effects of substrate supply amount(SS),NS,and SF on cucumber yield,quality,and element utilization efficiency.A five-level quadratic orthogonal rotation combination design with three experimental factors(NS,SF,and SS)was implemented for 23 coupling treatments over three growing seasons,including spring(2022S and 2023S)and autumn(2022A).The technique for order preference by similarity to ideal solution(TOPSIS)combining weights based on game theory was applied to construct cucumber comprehensive growth evaluation model.Single and two experimental factors analyses revealed significant effects of single factors and the coupling of NS-SS,NS-SF and SS-SF on the integrated growth of cucumber for all three growing seasons.For the NS-SF-SS combination,the optimal parameters for comprehensive cucumber growth were determined as follows:levels of^(-1).68 for NS,-0.7 for SF,and^(-1).682 for SS in 2022A;-0.43 for NS,-0.06 for SF,and 0.34 for SS in 2022S;0.3 for NS,-0.02 for SF,and 0.04 for SS in 2023S.Furthermore,for SS ranges of 2.00-3.01,3.01-4.50,4.50-5.99,5.99-7.00(L·plant^(-1)),the corresponding NS and SF intervals maximizing cucumber integrated growth in spring were:0.28-0.30(L·plant^(-1))and 6(times·d^(-1)),0.26-0.30(L·plant^(-1))and 6(times·d^(-1)),0.25-0.30(L·plant^(-1))and 6(times·d^(-1)),0.23-0.30(L·plant^(-1))and 6(times·d^(-1)),respectively.With the same SS,the corresponding NS and SF intervals that maximized cucumber integrated growth in autumn were:0.10(L·plant^(-1))and 8(times·d^(-1)),0.18(L·plant^(-1))and 7(times·d^(-1)),0.30(L·plant^(-1))and 6(times·d^(-1)),0.49(L·plant^(-1))and 5(times·d^(-1)),respectively.The results provide a theoretical basis for solution management,and further in-depth research on cucumber cultivation.展开更多
Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2)...Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2) management in life-support systems of confined space.Here,a micro/nano-reconfigurable robot is constructed from the CO_(2) molecular hunters,temperature-sensitive molecular switch,solar photothermal conversion,and magnetically-driven function engines.The molecular hunters within the molecular extension state can capture 6.19 mmol g^(−1) of CO_(2) to form carbamic acid and ammonium bicarbonate.Interestingly,the molecular switch of the robot activates a molecular curling state that facilitates CO_(2) release through nano-reconfiguration,which is mediated by the temperature-sensitive curling of Pluronic F127 molecular chains during the photothermal desorption.Nano-reconfiguration of robot alters the amino microenvironment,including increasing surface electrostatic potential of the amino group and decreasing overall lowest unoccupied molecular orbital energy level.This weakened the nucleophilic attack ability of the amino group toward the adsorption product derivatives,thereby inhibiting the side reactions that generate hard-to-decompose urea structures,achieving the lowest regeneration temperature of 55℃ reported to date.The engine of the robot possesses non-contact magnetically-driven micro-reconfiguration capability to achieve efficient photothermal regeneration while avoiding local overheating.Notably,the robot successfully prolonged the survival time of mice in the sealed container by up to 54.61%,effectively addressing the issue of carbon suffocation in confined spaces.This work significantly enhances life-support systems for deep-space exploration,while stimulating innovations in sustainable carbon management technologies for terrestrial extreme environments.展开更多
The synthesis of pillared clays have led to the development of new materialswith suitable pore size and sufficient stability to be used as shape-selective catalystsand molecular sieves. There are numerous layered inor...The synthesis of pillared clays have led to the development of new materialswith suitable pore size and sufficient stability to be used as shape-selective catalystsand molecular sieves. There are numerous layered inorganic oxides which havethe potential to undergo ion-exchange reactions analogous to those observed withclays, but the nonswelling nature of most ionic layered oxides generally prevents展开更多
基金supported by the National Natural Science Foundation of China (Nos.50771081,50827102)the National Basic Research Program of China (No.2006CB605202)
文摘The dendrite morphologies and spacings of directionally solidified DZ125 superalloy were investigated under high thermal gradient about 500 K/cm. The results reveal that, with increasing cooling rate, both the spacings of primary and secondary dendrite arms decrease, and the dendrite morphologies transit from coarse to superfme dendrite. The secondary dendrite arms trend to be refined and be well developed, and the tertiary dendrite will occur. The predictions of the Kurz/Fisher model and the Hunt/Lu model accord basically with the experimental data for primary dendrite arm spacing. The regression equation of the primary dendrite arm spacings 21 and the cooling rate Vc is λ1 = 0.013 Vc^-0.32. The regression equation of the secondary dendrite arm spacing λ2 and the cooling rate Vc is λ2 = 0.00258 Vc^-0.31, which gives good agreement with the Feurer/Wunderlin model.
基金supported by the China Postdoctoral Science Foundation (No. 20110491492)National Natural Science Foundation of China (No. 50765005)the Innovative Group of Science and Technology of College of Jiangxi Province,China (No. 00008713)
文摘The microstructure scales of dendrites, such as primary and secondary dendrite arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic regions, which determine the properties of solidified structures. Investigations on primary and secondary dendrite arm spacings of primary a-phase during directionally solidified Pb-26wt%Bi hypo-peritectic alloy were carried out in this research, and systematic studies were conducted using cylindrical samples with different diameters （Ф = 1.8 and 7.0 mm） in order to analyze the effects of sample diameter on the primary and secondary dendrite arm spacings. In this work, the dependence of dendrite arm spacings on growth velocity was established. In addition, the experimental data concerning the primary and secondary dendrite ann spacings were compared with the main predictive dendritic models from the literatures. A comparison between experimental results for dendrite arm spacings of the 1.8-mm-diameter sample and 7.0-ram-diameter sample was also conducted.
文摘Fatigue crack growth experiments were per- formed on A1 alloy LD 10 and Ti-6A1-4V alloy. Fatigue striation spacings and the deviation angles between the direction of micro-crack growth and that of macro-crack growth were quanti- tatively measured on fracture surface using scanning electron microscope. A statistical model of the relationship between striation spacings and fatigue crack propagation rates was developed on the basis of a statistical analysis of the deviation angles, Good agreement between experimental results and theoretical results calculated with the present model was obtained.
基金supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202400720)。
文摘The interaction between the TBM cutters and the rock mass is the main factor in TBM tunneling.The rock damage characteristics under the cutters are directly associated with the cutting efficiency and rock fragmentation mechanism.Four sets of linear cutting tests were performed in this paper with various cutter spacing to obtain the cutter force and muck.Then,fluorescence experiments were conducted to evaluate the rock damage characteristics by sawing the rock samples after the tests.The findings reveal that the effect of cutter spacing on mean normal force increases gradually as penetration depth increases,but only affects mean rolling force for penetration depths exceeding 2.0 mm.The optimal cutting efficiency is achieved at an S/P of 20-60.The area ratio of the crushed zone and the crack dense zone decreases as cutter spacing increases while that of the crack sparse zone increases.Moreover,increasing the cutter force or cutting spacing at the same penetration depth expands the crack sparse zone,increasing the cutting efficiency.This study could provide ideas and data support for designing the TBM cutterhead and optimizing the TBM operation.
基金supported by the Natural Science Foundation of Hubei Province(Grant No.2021CFB592)the Outstanding Youth Fund of Hubei University of Automotive Technology(Grant No.2023YQ04)+1 种基金This work was also sponsored by the Outstanding Young and Middle-aged Scientific Innovation Team of Colleges and Universities of Hubei Province(Grant No.T201913)the Initiation Fund for Doctoral Research from Hubei University of Automotive Technology(Grant No.BK201608).
文摘Effective adjustment of fertilization spacing and amounts for different plant distances is beneficial to increase production and reduce the amount of fertilizer used.In order to achieve such a target,an electric-fertilizing vehicle with staggered fan-shaped openings in a fertilization device is proposed here,and its fertilization spacing and amounts are controlled by a control system and mobile phone-based programs.Further validating multivariable effects on fertilization spacing and amounts,such as openings,rotary speeds,and moving parameters of the vehicle,an integration discrete element model(DEM)is established so that the feasibility of the fertilization device could be evaluated before manufacturing and testing.Finally,it is reflected through field-simulated experiments that fertilizer spacing ranges from 0.27 to 5.45 m.Compared with simulated results,the absolute error varies from-0.08 to 0.05 m,and the maximum relative error is about-5.67%.Therefore,the uniform and stable fertilization for different plant spacing is semi-actively achieved by the designed device and a control system with mobile phone-based programs.The proposed simulation model is feasible,thus presenting a good reference for designing these components.
文摘背景:新型生物材料不仅提供必要的机械支撑,还能促进细胞增殖和分化、诱导骨再生,从而改善治疗效果,为骨再生技术的发展提供了新的视角和方法。目的:通过文献计量学方法可视化分析生物材料在骨再生领域的研究状况及发展前景。方法:在Web of Science核心数据库中,精选了数据库建库至2024-09-24关于骨再生和生物材料领域最具影响力的文献500篇,运用VOSviewer和CiteSpace两款工具进行深入的计量学可视化分析,以揭示该领域的研究趋势和核心文献结果与结论:在所选的500篇文献中,中国和美国在发表论文数量和被引用率方面均占据领先地位,而常江是发文最多的作者,发表文章最多的期刊为Acta Biomaterialia。骨再生和材料学是一个跨学科的研究范畴,涵盖了材料科学、生物医学工程、细胞生物学、分子生物学等多个学科领域。骨修复材料的研究正从传统的生物惰性材料向生物活性材料转变,这些材料不仅提供机械支撑,还能促进细胞增殖和分化,诱导骨再生。合成骨修复材料因丰富的来源、可调节的物理化学特性以及较低的免疫排斥和疾病传播风险,正逐渐替代传统材料,成为临床骨移植手术的首选。研究者们正在不断改进这些材料的生物相容性、仿生特性、骨传导性和骨诱导性,使其更接近天然骨,前沿主要集中在生物活性陶瓷、3D打印、水凝胶、壳聚糖、羟基磷灰石等材料。新型材料在骨再生领域中的作用至关重要,随着材料科学技术的不断进步,这些新型材料在骨再生领域的应用前景非常广阔,有望为骨缺损治疗提供更为有效和个性化的治疗方案。
基金supported by the National Natural Science Foundation of China,No.82274304(to YH)the Major Clinical Study Projects of Shanghai Shenkang Hospital Development Center,No.SHDC2020CR2046B(to YH)Shanghai Municipal Health Commission Talent Plan,No.2022LJ010(to YH).
文摘Cerebral small vessel disease encompasses a group of neurological disorders characterized by injury to small blood vessels,often leading to stroke and dementia.Due to its diverse etiologies and complex pathological mechanisms,preventing and treating cerebral small vessel vasculopathy is challenging.Recent studies have shown that the glymphatic system plays a crucial role in interstitial solute clearance and the maintenance of brain homeostasis.Increasing evidence also suggests that dysfunction in glymphatic clearance is a key factor in the progression of cerebral small vessel disease.This review begins with a comprehensive introduction to the structure,function,and driving factors of the glymphatic system,highlighting its essential role in brain waste clearance.Afterwards,cerebral small vessel disease was reviewed from the perspective of the glymphatic system,after which the mechanisms underlying their correlation were summarized.Glymphatic dysfunction may lead to the accumulation of metabolic waste in the brain,thereby exacerbating the pathological processes associated with cerebral small vessel disease.The review also discussed the direct evidence of glymphatic dysfunction in patients and animal models exhibiting two subtypes of cerebral small vessel disease:arteriolosclerosis-related cerebral small vessel disease and amyloid-related cerebral small vessel disease.Diffusion tensor image analysis along the perivascular space is an important non-invasive tool for assessing the clearance function of the glymphatic system.However,the effectiveness of its parameters needs to be enhanced.Among various nervous system diseases,including cerebral small vessel disease,glymphatic failure may be a common final pathway toward dementia.Overall,this review summarizes prevention and treatment strategies that target glymphatic drainage and will offer valuable insight for developing novel treatments for cerebral small vessel disease.
基金supported by the National Natural Science Foundation of China,No.81971031(to ZL)the National Key Research and Development Program of China,No.2022YFE0210100(to JFC)+7 种基金the National Natural Science Foundation of China(Original Exploration Project),No.82151308(to JFC)the National Natural Science Foundation of China(Research Fund for International Senior Scientists),No.82150710558(to JFC)Science&Technology Initiative STI2030-Major Projects,No.2021ZD0203400(to JFC)Key Research and Development Program of Zhejiang Province,No.2023C03079(to JFC)Scientific Research Starting Foundation of Oujiang Laboratory(Zhejiang Laboratory for Regenerative Medicine,Vision and Brain Health),No.OJQDSP2022007(to JFC)Project of State Key Laboratory of Ophthalmology,Optometry and Visual Science,Wenzhou Medical University,No.J01-20190101(to JFC)Scientific Research Starting Foundation of Wenzhou Medical University,No.QTJ12003(to JFC)Department of Science and Technology of Zhejiang Province,No.2023ZY1011(to JFC)。
文摘The excessive buildup of neurotoxicα-synuclein plays a pivotal role in the pathogenesis of Parkinson's disease,highlighting the urgent need for innovative therapeutic strategies to promoteα-synuclein clearance,particularly given the current lack of disease-modifying treatments.The glymphatic system,a recently identified perivascular fluid transport network,is crucial for clearing neurotoxic proteins.This review aims to synthesize current knowledge on the role of the glymphatic system inα-synuclein clearance and its implications for the pathology of Parkinson's disease while emphasizing potential therapeutic strategies and areas for future research.The review begins with an overview of the glymphatic system and details its anatomical structure and physiological functions that facilitate cerebrospinal fluid circulation and waste clearance.It summarizes emerging evidence from neuroimaging and experimental studies that highlight the close correlation between the glymphatic system and clinical symptom severity in patients with Parkinson's disease,as well as the effect of glymphatic dysfunction onα-synuclein accumulation in Parkinson's disease models.Subsequently,the review summarizes the mechanisms of glymphatic system impairment in Parkinson's disease,including sleep disturbances,aquaporin-4 impairment,and mitochondrial dysfunction,all of which diminish glymphatic system efficiency.This creates a vicious cycle that exacerbatesα-synuclein accumulation and worsens Parkinson's disease.The therapeutic perspectives section outlines strategies for enhancing glymphatic activity,such as improving sleep quality and pharmacologically targeting aquaporin-4 or its subcellular localization.Promising interventions include deep brain stimulation,melatonin supplementation,γ-aminobutyric acid modulation,and non-invasive methods(such as exercise and bright-light therapy),multisensoryγstimulation,and ultrasound therapy.Moreover,identifying neuroimaging biomarkers to assess glymphatic flow as an indicator ofα-synuclein burden could refine Parkinson's disease diagnosis and track disease progression.In conclusion,the review highlights the critical role of the glymphatic system inα-synuclein clearance and its potential as a therapeutic target in Parkinson's disease.It advocates for further research to elucidate the specific mechanisms by which the glymphatic system clears misfoldedα-synuclein and the development of imaging biomarkers to monitor glymphatic activity in patients with Parkinson's disease.Findings from this review suggest that enhancing glymphatic clearance is a promising strategy for reducingα-synuclein deposits and mitigating the progression of Parkinson's disease.
文摘Space-Based Solar Power(SBSP) presents a promising solution for achieving carbon neutrality and Renewable Electricity 100%(RE100) goals by offering a stable and continuous energy supply. However, its commercialization faces significant obstacles due to the technical challenges of long-distance microwave Wireless Power Transmission(WPT) from geostationary orbit. Even ground-based kilometer-scale WPT experiments remain difficult because of limited testing infrastructure, high costs, and strict electromagnetic wave regulations. Since the 1975 NASA-Raytheon experiment, which successfully recovered 30 kW of power over 1.55 km, there has been little progress in extending the transmission distance or increasing the retrieved power. This study proposes a cost-effective methodology for conducting long-range WPT experiments in constrained environments by utilizing existing infrastructure. A deep space antenna operating at 2.08 GHz with an output power of 2.3 kW and a gain of 55.3 dBi was used as the transmitter. Two test configurations were implemented: a 1.81 km ground-to-air test using an aerostat to elevate the receiver and a 1.82 km ground-to-ground test using a ladder truck positioned on a plateau. The rectenna consists of a lightweight 3×3 patch antenna array(0.9 m × 0.9 m), accompanied by a steering device and LED indicators to verify power reception. The aerostat-based test achieved a power density of 154.6 mW/m2, which corresponds to approximately 6.2% of the theoretical maximum. The performance gap is primarily attributed to near-field interference, detuning of the patch antenna, rectifier mismatch, and alignment issues. These limitations are expected to be mitigated through improved patch antenna fabrication, a transition from GaN to GaAs rectifiers optimized for lower input power, and the implementation of an automated alignment system. With these enhancements, the recovered power is expected to improve by approximately four to five times. The results demonstrate a practical and scalable framework for long-range WPT experiments under constrained conditions and provide key insights for advancing SBSP technology.
基金Supported by the National Natural Science Foundation of China(11871195)。
文摘In this article,we conduct a study on mixed quasi-martingale Hardy spaces that are defined by means of the mixed L_(p)-norm.By utilizing Doob’s inequalities,we explore the atomic decomposition and quasi-martingale inequalities of mixed quasi-martingale Hardy spaces.Moreover,we furnish sufficient conditions for the boundedness ofσ-sublinear operators in these spaces.These findings extend the existing conclusions regarding mixed quasi-martingale Hardy spaces defined with the help of the mixed L_(p)-norm.
基金supported by Swedish Research Council(Vetenskapsradet,2023-04962).
文摘Space exploration is significant for scientific innovation,resource utilization,and planetary security.Space exploration involves several systems including satellites,space suits,communication systems,and robotics,which have to function under harsh space conditions such as extreme temperatures(−270 to 1650℃),microgravity(10^(-6)g),unhealthy humidity(<20%RH or>60%RH),high atmospheric pressure(~1450 psi),and radiation(4000–5000 mSv).Conventional energy-harvesting technologies(solar cells,fuel cells,and nuclear energy),that are normally used to power these space systems have certain limitations(e.g.,sunlight dependence,weight,degradation,big size,high cost,low capacity,radioactivity,complexity,and low efficiency).The constraints in conventional energy resources have made it imperative to look for non-conventional yet efficient alternatives.A great potential for enhancing efficiency,sustainability,and mission duration in space exploration can be offered by integrating triboelectric nanogenerators(TENGs)with existing energy sources.Recently,the potential of TENG including energy harvesting(from vibrations/movements in satellites and spacecraft),self-powered sensing,and microgravity,for multiple applications in different space missions has been discussed.This review comprehensively covers the use of TENGs for various space applications,such as planetary exploration missions(Mars environment monitoring),manned space equipment,In-orbit robotic operations/collision monitoring,spacecraft’s design and structural health monitoring,Aeronautical systems,and conventional energy harvesting(solar and nuclear).This review also discusses the use of self-powered TENG sensors for deep space object perception.At the same time,this review compares TENGs with conventional energy harvesting technologies for space systems.Lastly,this review talks about energy harvesting in satellites,TENG-based satellite communication systems,and future practical implementation challenges(with possible solutions).
基金Supported by National Natural Science Foundation of China(12161078)Foundation for Innovative Fundamental Research Group Project of Gansu Province(24JRRA778)Project of Northwest Normal University(20240010)。
文摘In this paper,we studyλ-biharmonic hypersurfaces M_(r)^(5) of 6-dimensional pseudo Riemannian space form N_(p)^(6)(c)with the indexs 0≤p≤6,r=p−1 or p,and constant curvature c.It was proved that if the shape operator of M_(r)^(5) is diagonalizable,then the mean curvature is a constant.As an application,we find some types of biharmonic hypersurfaces of N_(p)^(6)(c)are minimal.
基金supported by the China Agriculture Research System(Grant No.CARS-23-D06)the Key Research and Development Program of Shaanxi Province(Grant Nos.2024NC2-GJHX-29 and 2024NC-ZDCYL-05-08)Shaanxi Agricultural Collaborative Innovation and Extension Alliance Project(Grant No.LMZD202202).
文摘Substrate and nutrient supply are essential for vegetable cultivation in greenhouse.The strategies for plant nutrient supply vary depending on the cultivation methods or substrate dosages employed.With the development of mechanization,wide-row spacing substrate cultivation became an optimize mode of the greenhouse cucumber cultivation,aligning with the trend of intelligent agriculture.To determine the optimal nutrient solution supply amount(NS)and supply frequency(SF)for promoting the integrated growth of cucumber under wide-row spacing substrate cultivation,we explored the effects of substrate supply amount(SS),NS,and SF on cucumber yield,quality,and element utilization efficiency.A five-level quadratic orthogonal rotation combination design with three experimental factors(NS,SF,and SS)was implemented for 23 coupling treatments over three growing seasons,including spring(2022S and 2023S)and autumn(2022A).The technique for order preference by similarity to ideal solution(TOPSIS)combining weights based on game theory was applied to construct cucumber comprehensive growth evaluation model.Single and two experimental factors analyses revealed significant effects of single factors and the coupling of NS-SS,NS-SF and SS-SF on the integrated growth of cucumber for all three growing seasons.For the NS-SF-SS combination,the optimal parameters for comprehensive cucumber growth were determined as follows:levels of^(-1).68 for NS,-0.7 for SF,and^(-1).682 for SS in 2022A;-0.43 for NS,-0.06 for SF,and 0.34 for SS in 2022S;0.3 for NS,-0.02 for SF,and 0.04 for SS in 2023S.Furthermore,for SS ranges of 2.00-3.01,3.01-4.50,4.50-5.99,5.99-7.00(L·plant^(-1)),the corresponding NS and SF intervals maximizing cucumber integrated growth in spring were:0.28-0.30(L·plant^(-1))and 6(times·d^(-1)),0.26-0.30(L·plant^(-1))and 6(times·d^(-1)),0.25-0.30(L·plant^(-1))and 6(times·d^(-1)),0.23-0.30(L·plant^(-1))and 6(times·d^(-1)),respectively.With the same SS,the corresponding NS and SF intervals that maximized cucumber integrated growth in autumn were:0.10(L·plant^(-1))and 8(times·d^(-1)),0.18(L·plant^(-1))and 7(times·d^(-1)),0.30(L·plant^(-1))and 6(times·d^(-1)),0.49(L·plant^(-1))and 5(times·d^(-1)),respectively.The results provide a theoretical basis for solution management,and further in-depth research on cucumber cultivation.
基金supported by the National Natural Science Foundation of China(22168008,22378085)the Guangxi Natural Science Foundation(2024GXNSFDA010053)+1 种基金the Technology Development Project of Guangxi Bossco Environmental Protection Technology Co.,Ltd(202100039)Innovation Project of Guangxi Graduate Education(YCBZ2024065).
文摘Strategically coupling nanoparticle hybrids and internal thermosensitive molecular switches establishes an innovative paradigm for constructing micro/nanoscale-reconfigurable robots,facilitating energyefficient CO_(2) management in life-support systems of confined space.Here,a micro/nano-reconfigurable robot is constructed from the CO_(2) molecular hunters,temperature-sensitive molecular switch,solar photothermal conversion,and magnetically-driven function engines.The molecular hunters within the molecular extension state can capture 6.19 mmol g^(−1) of CO_(2) to form carbamic acid and ammonium bicarbonate.Interestingly,the molecular switch of the robot activates a molecular curling state that facilitates CO_(2) release through nano-reconfiguration,which is mediated by the temperature-sensitive curling of Pluronic F127 molecular chains during the photothermal desorption.Nano-reconfiguration of robot alters the amino microenvironment,including increasing surface electrostatic potential of the amino group and decreasing overall lowest unoccupied molecular orbital energy level.This weakened the nucleophilic attack ability of the amino group toward the adsorption product derivatives,thereby inhibiting the side reactions that generate hard-to-decompose urea structures,achieving the lowest regeneration temperature of 55℃ reported to date.The engine of the robot possesses non-contact magnetically-driven micro-reconfiguration capability to achieve efficient photothermal regeneration while avoiding local overheating.Notably,the robot successfully prolonged the survival time of mice in the sealed container by up to 54.61%,effectively addressing the issue of carbon suffocation in confined spaces.This work significantly enhances life-support systems for deep-space exploration,while stimulating innovations in sustainable carbon management technologies for terrestrial extreme environments.
文摘The synthesis of pillared clays have led to the development of new materialswith suitable pore size and sufficient stability to be used as shape-selective catalystsand molecular sieves. There are numerous layered inorganic oxides which havethe potential to undergo ion-exchange reactions analogous to those observed withclays, but the nonswelling nature of most ionic layered oxides generally prevents
