Bentonite is a necessary binder in producing pellets.Its excessive use reduces the iron grade of pellets and increases production costs.Minimizing bentonite dosage is essential for producing high-quality iron ore pell...Bentonite is a necessary binder in producing pellets.Its excessive use reduces the iron grade of pellets and increases production costs.Minimizing bentonite dosage is essential for producing high-quality iron ore pellets.Addressing the gap in the application of organically-intercalated modified bentonite in the pelletizing field,this study introduces an innovative modification process for bentonite that employs the synergistic effect of mechanical force and dimethyl sulfoxide to enhance the intercalation of organic compounds within bentonite,thus significantly enhancing its binding performance.The colloid value and swell capacity of modified bentonite(98.5 m L/3g and 55.0 m L/g)were much higher than the original bentonite(90.5 m L/3g and 17.5 m L/g).With the decrease of bentonite dosage from1.5wt%to 1.0wt%,the drop number of green pellets from a height of 0.5 m and the compressive strengths of roasted pellets using the modified bentonite(6.0 times and 2916 N per pellet)were significantly higher than those of the original bentonite(4.0 times and 2739 N per pellet).This study provides a comprehensive analysis of the intercalation modification mechanism of bentonite,offering crucial technical insights for the development of high-performance modified bentonite as iron ore pellet binders.展开更多
Mesenchymal stem cells(MSCs),which are mechanosensitive cells,mediate the cells crosstalk in response to mechanical force,thereby playing a crucial role in bone homeostasis.Migrasomes serve as an important mediator fo...Mesenchymal stem cells(MSCs),which are mechanosensitive cells,mediate the cells crosstalk in response to mechanical force,thereby playing a crucial role in bone homeostasis.Migrasomes serve as an important mediator for cellular communication.However,whether the mechanical stimulus regulates the biology and property of migrasomes on bone metabolism remains unknown.This study shows that mechanical stimulus could promote MSCs to synthesize and secrete migrasomes,which could significantly alleviate chronic infectious bone destruction in periodontal tissue by inhibiting osteoclastic differentiation of macrophage and reestablishing local immune microenvironment.Mechanistically,miR-29b-3p is more abundant in migrasomes from mechanical force stimulated MSCs than in control ones.MiR-29b-3p blocks the activation of pyrin domain containing protein 3(NLRP3)and mitochondrial DNA(mtDNA)release by directly targeting on Tet1.Thus,mechanical sensing migrasomes inhibit osteoclast differentiation to alleviate inflammation induced bone destruction.These findings reveal that the mechanical stimulus controls the formation and properties of migrasomes,which provides a new biotechnological strategy for chronic infectious bone destruction intervention.展开更多
Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean...Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean meridional circu- lation are modulated by a certain ratio.This ratio is determined by the inherent baroclinity,static stability and absolute vorticity of the atmosphere. By employing a parameterization scheme for radiative heating and condensation heating,together with the analysis data of the European Center for Medium-range Weather Forecasts,the mean meridional circulation for January was simulated numerically.It was found that latent heat release in the tropics may result in the formation of double-layered Hadley circulation,so do the eddy momentum transfer processes.On the other hand,mean meridional circulations in ex- tra-tropics are mainly determined by external momentum forcing and atmospheric properties of eddy momentum and heat transfer.展开更多
Mechanical forces in the tumor microenvironment(TME)are associated with tumor growth,proliferation,and drug resistance.Strong mechanical forces in tumors alter the metabolism and behavior of cancer cells,thus promotin...Mechanical forces in the tumor microenvironment(TME)are associated with tumor growth,proliferation,and drug resistance.Strong mechanical forces in tumors alter the metabolism and behavior of cancer cells,thus promoting tumor progression and metastasis.Mechanical signals are transformed into biochemical signals,which activate tumorigenic signaling pathways through mechanical transduction.Cancer immunotherapy has recently made exciting progress,ushering in a new era of“chemo-free”treatments.However,immunotherapy has not achieved satisfactory results in a variety of tumors,because of the complex tumor microenvironment.Herein,we discuss the effects of mechanical forces on the tumor immune microenvironment and highlight emerging therapeutic strategies for targeting mechanical forces in immunotherapy.展开更多
The carbonization of magnesium oxide particles by CO2 was investigated using a stirring mill reactor. The effects of the system temperature, stirring rotation speed, influx rate of CO2 and initial diameter of the magn...The carbonization of magnesium oxide particles by CO2 was investigated using a stirring mill reactor. The effects of the system temperature, stirring rotation speed, influx rate of CO2 and initial diameter of the magnesium oxide particles on the carbonization process were determined, The results show that the system temperature and the stirring rotation speed are the most significant influencing factors on the carbonization rate. The determi-nation of critical decomposition temperature (CDT) gives the maximum carbonization rate with other conditions fixed. A theoretical model involving mass transfer and reaction kinetics was presented for the carbonization process. The apparent activation energy was calculated to be 32.8kJ·mol-1. The carbonization process is co-controlled by diffusive mass transfer and chemical reaction. The model fits well with the experimental results.展开更多
Cross-talk between tumor cells and mechanical stress in the tumor microenvironment has been shown to be involved in carcinogenesis.High mechanical stress in tumors can alter the metabolism and behaviors of cancer cell...Cross-talk between tumor cells and mechanical stress in the tumor microenvironment has been shown to be involved in carcinogenesis.High mechanical stress in tumors can alter the metabolism and behaviors of cancer cells and cause cancer cells to attain cancer stem-like cell properties,thus driving tumor progression and promoting metastasis.The mechanical signal is converted into a biochemical signal that activates tumorigenic signaling pathways through mechanotransduction.Herein,we describe the physical changes occurring during reprogramming of cancer cell metabolism,which regulate cancer stem cell functions and promote tumor progression and aggression.Furthermore,we highlight emerging therapeutic strategies targeting mechanotransduction signaling pathways.展开更多
Dune fields at the northern margin of the East Asian monsoon （EAM）, are mosaics of mobile and vegetation-stabilized aeolian dunes. These sand dunes are highly sensitive to environmental change, thus the distribution...Dune fields at the northern margin of the East Asian monsoon （EAM）, are mosaics of mobile and vegetation-stabilized aeolian dunes. These sand dunes are highly sensitive to environmental change, thus the distribution and the timing of their development may provide important clues to past environmental dynamics. Due to the strong wind erosion and dune migration, long and continuous stratigraphic records are seldom preserved. Synthesizing a large body of events, ultimately producing a relatively complete and high-resolution record, may be a proper method to investigate the dune development history and climate change. In this study, we synthesized a large body of luminescence ages for aeolian deposits from the Mu Us, Otindag, Horqin dune fields at the northern margin of the EAM. The results show that these dune fields, as a whole experienced a most extensive mobility during the early Holocene, followed by a widespread shift toward limited mobility and soil development in the mid-Holocene, and widespread reactivation occurred during late Holocene. The dune developments are directly linked to the effective moisture change controlled by the EAM changes, which respond to the low latitude summer insolation variation. The increased subsidence at the margin contrary to the core EAM, the delay from the feedback of the soil-vegetation-air coupled system, the increased evaporation due to the high temperature all play partial role in the lag of the margin EAM effective moisture change to the low latitude summer insolation. The asynchronous end of the wetter mid-Holocene mainly responds to the southeastwardly shift of the precipitation belt, while the regional sensitivity, response speed and internal feedback also contributed. The correspondence between dune records and North Atlantic drift-ice records of the rapid climate changes implies a close relationship between North Atlantic climate and the frequent dune activity at the northern margin of EAM.展开更多
In order to make further steps in dealing with climate change, China proposed to peak carbon dioxide emissions by about 2030 and to make best efforts for the peaking early. The carbon emission peak target(CEPT) must r...In order to make further steps in dealing with climate change, China proposed to peak carbon dioxide emissions by about 2030 and to make best efforts for the peaking early. The carbon emission peak target(CEPT) must result in a forcing mechanism on China's economic transition. This paper, by following the logical order from "research on carbon emission history" to "carbon emission trend prediction," from "research on paths of realizing peak" to "peak restraint research," provides a general review of current status and development trend of researches on China's carbon emission and its peak value. Furthermore,this paper also reviews the basic theories and specific cases of the forcing mechanism.Based on the existing achievements and development trends in this field, the following research directions that can be further expanded are put forward. First, from the perspective of long-term strategy of sustainable development, we should analyze and construct the forcing mechanism of CEPT in a reverse thinking way. Second, economic transition paths under the forcing mechanism should be systematically studied. Third, by constructing a large-scale policy evaluation model, the emission reduction performance and economic impact of a series of policy measures adopted during the transition process should be quantitatively evaluated.展开更多
In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate...In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relation- ship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.展开更多
To improve the osteogenic property of bone repairing materials and to accelerate bone healing are major tasks in bone biomaterials research. The objective of this study was to investigate if the mechanical force could...To improve the osteogenic property of bone repairing materials and to accelerate bone healing are major tasks in bone biomaterials research. The objective of this study was to investigate if the mechanical force could be used to accelerate bone formation in a bony defect in vivo. The calcium sulfate cement was implanted into the left distal femoral epiphyses surgically in 16 rats. The half of rats were subjected to external mechanical force via treadmill exercise, the exercise started at day 7 postoperatively for 30 consecutive days and at a constant speed 8 m·min-1 for 45 min·day-1, while the rest served as a control. The rats were scanned four times longitudinally after surgery using microcomputed tomography and newly formed bone was evaluated. After sacrificing, the femurs had biomechanical test of three-point bending and histological analysis. The results showed that bone healing under mechanical force were better than the control with residual defect areas of 0.64±0.19 mm2 and 1.78±0.39 mm2（P〈0.001）, and the ultimate loads to failure under mechanical force were 69.56±4.74 N, stronger than the control with ultimate loads to failure of 59.17±7.48 N（P=0.039）. This suggests that the mechanical force might be used to improve new bone formation and potentially offer a clinical strategy to accelerate bone healing.展开更多
Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP)...Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP),and water mass formation for both coastal polynyas and open-ocean polynyas in the Southern Ocean,as well as the variability and controlling mechanisms of polynya processes on different time scales.Polynyas play an irreplaceable role in the regulation of global ocean circulation and biological processes in regional ocean ecosystems.The coastal polynyas(latent heat polynyas)are mainly located in the Weddell Sea,the Ross Sea and on the west side of protruding topographic features in East Antarctica.During the formation of coastal polynyas,which are mainly forced by offshore winds or ocean currents,brine rejection triggered by high SIP results in the formation of high salinity shelf water,which is the predecessor of the Antarctic bottom water-the lower limb of the global thermohaline circulation.The open-ocean polynyas(sensible heat polynyas)are mainly found in the Indian sector of the Southern Ocean,which are formed by ocean convection processes generated by topography and negative wind stress curl.The convection processes bring nutrients into the upper ocean,which supports biological production and makes the polynya regions an important sink for atmospheric carbon dioxide.The limitations and challenges in polynya research are also discussed.展开更多
The switching process of ferroelectric thin films in electronic devices is one of the most important requirements for their application. Especially for the different external fields acting on the film surface, the mec...The switching process of ferroelectric thin films in electronic devices is one of the most important requirements for their application. Especially for the different external fields acting on the film surface, the mechanism of domain switching is more complicated. Here we observe the nanoscale domain switchings of Bi3.15Eu0.85Ti3O12 thin film under different mechanical forces at a fast scan rate. As the force increases from initial state to 247.5 n N, the original bright or grey contrasts within the selected grains are all changed into dark contrasts corresponding to the polarization vectors reversed from the up state to the down state, except for the clusters. As the mechanical force increases to 495 n N, the color contrasts in all of the selected grains further turn into grey contrasts and some are even changed into grey contrasts completely showing the typical 90° domain switching. When another stronger loading force 742.5 n N is applied, the phase image becomes unclear and it indicates that the piezoelectric signal can be suppressed under a sufficiently high force, which is coincident with previous experimental results. Furthermore, we adopt the domain switching criterion from the perspective of equilibrium state free energy of ferroelectric nanodomain to explain the mechanisms of force-generated domain switchings.展开更多
Artificial vascular graft(AVG)fistula is widely used for hemodialysis treatment in patients with renal failure.However,it has poor elasticity and compliance,leading to stenosis and thrombosis.The ideal artificial bloo...Artificial vascular graft(AVG)fistula is widely used for hemodialysis treatment in patients with renal failure.However,it has poor elasticity and compliance,leading to stenosis and thrombosis.The ideal artificial blood vessel for dialysis should replicate the structure and components of a real artery,which is primarily maintained by collagen in the extracellular matrix(ECM)of arterial cells.Studies have revealed that in hepatitis B virus(HBV)-induced liver fibrosis,hepatic stellate cells(HSCs)become hyperactive and produce excessive ECM fibers.Furthermore,mechanical stimulation can encourage ECM secretion and remodeling of a fiber structure.Based on the above factors,we transfected HSCs with the hepatitis B viral X(HBX)gene for simulating the process of HBV infection.Subsequently,these HBX-HSCs were implanted into a polycaprolactonepolyurethane(PCL-PU)bilayer scaffold in which the inner layer is dense and the outer layer consists of pores,which was mechanically stimulated to promote the secretion of collagen nanofiber from the HBX-HSCs and to facilitate crosslinking with the scaffold.We obtained an ECM-PCL-PU composite bionic blood vessel that could act as access for dialysis after decellularization.Then,the vessel scaffold was implanted into a rabbit’s neck arteriovenous fistula model.It exhibited strong tensile strength and smooth blood flow and formed autologous blood vessels in the rabbit’s body.Our study demonstrates the use of human cells to create biomimetic dialysis blood vessels,providing a novel approach for creating clinical vascular access for dialysis.展开更多
BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[...BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].Recently, the BK channels have展开更多
Convection and its ensuing severe weather, such as heavy rainfall, hail, tornado, and high wind, have significant im- pacts on our society and economy （e.g., Cao et al., 2004; Fritsch and Carbone, 2004; Verbout et al...Convection and its ensuing severe weather, such as heavy rainfall, hail, tornado, and high wind, have significant im- pacts on our society and economy （e.g., Cao et al., 2004; Fritsch and Carbone, 2004; Verbout et al., 2006; Ashley and Black, 2008; Cao, 2008; Cao and Ma, 2009; Zhang et al., 2014）. Due to its localized and transient nature, the initiation of convection or convective initiation remains one of the least understood aspects of convection in the scientific communi- ties, and it is a significant challenge to accurately predict the exact timing and location of convective initiation （e.g., Cai et al., 2006; Wilson and Roberts, 2006; Xue and Martin, 2006; Cao and Zhang, 2016）.展开更多
The vibration response formulas of the mechanical system under the affect of thevari-frequency exciting force are deduced. It is proved by the theoretical analysis and experimentalresults that the vibration response a...The vibration response formulas of the mechanical system under the affect of thevari-frequency exciting force are deduced. It is proved by the theoretical analysis and experimentalresults that the vibration response amplitude of the mechanical system under the affect of thevari-frequency exciting force is far smaller than that under the affect of the constant frequency exciting force on condition that the exciting force amplitudes are just the same;while the vari-fre-quency rate a increases to 5 Hz per second the vibration amplitude will decrease to 10% only as lowas that under the affect of the constant frequency exciting force. All these conclusions will be of significance for revealing the mechanism of suppressing chatter in van-speed cutting and analyzing theexperimental results of sine-wave scanning exciting test.展开更多
Cells are exposed to various mechanical forces,including extracellular and intracellular forces such as stiffness,tension,compression,viscosity,and shear stress,which regulate cell biology.The process of transducing m...Cells are exposed to various mechanical forces,including extracellular and intracellular forces such as stiffness,tension,compression,viscosity,and shear stress,which regulate cell biology.The process of transducing mechanical stimuli into biochemical signals is termed mechanotransduction.These mechanical forces can regulate protein and gene expression,thereby impacting cell morphology,adhesion,proliferation,apoptosis,and migration.During cancer development,significant changes in extracellular and intracellular mechanical properties occur,resulting in altered mechanical inputs to which cells are exposed.MicroRNAs(miRNAs),key post-transcriptional regulators of gene and protein expression,are increasingly recognized as mechanosensitive molecules involved in cancer development.In this review,we summarize the primary cellular pathways involved in force sensing and mechanotransduction,emphasizing the role of forces in miRNA biogenesis and expression,as well as their influence on the regulation of key mechanotransducers.Furthermore,we focus on recent evidence regarding the induction or repression of miRNAs involved in cancer development by mechanical forces and their impact on the regulation of proteins that contribute to cancer progression.展开更多
The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies d...The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies diverse and the scarcity of accurate quantitative reconstruction records.In this study,we employed diatoms and pollen records from lacustrine sediment in the Aibi Lake of Southwest Junggar Basin to quantitatively reconstruct salinity and watershed precipitation amounts while exploring the associated forcing mechanisms.The results indicate that Aibi Lake salinity varied between 2 and 47 g/L during the Late Holocene Period,indicating a generally brackish environment,and corresponding to prevailing Tryblionella granulata diatom in the lake basin.Westerly-dominated annual precipitation varied between 250 and 320 mm during the Late Holocene Period in the basin,exhibiting a generally semi-arid environment and prevailing desert steppe vegetation.The Aibi Lake has a low salinity of average value of~15 g/L and exhibits elevated precipitation(average value of~280 mm)during the periods of the 2900-1990,1570-1140,and 590-120 cal yr BP.The reconstructed precipitation and salinity exhibit a periodicity of~200 years,which is consistent with the cycle of phase changes of the North Atlantic oscillation(NAO)and total solar irradiance(TSI).This correlation suggests that variations in NOA and TSI significantly influence the precipitation and salinity changes in Central Asia over centennial to millennial timescales.展开更多
Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in ...Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.展开更多
Adaptive gaits for legged robots often requires force sensors installed on foot-tips,however impact,temperature or humidity can affect or even damage those sensors.Efforts have been made to realize indirect force esti...Adaptive gaits for legged robots often requires force sensors installed on foot-tips,however impact,temperature or humidity can affect or even damage those sensors.Efforts have been made to realize indirect force estimation on the legged robots using leg structures based on planar mechanisms.Robot Octopus III is a six-legged robot using spatial parallel mechanism（UP-2UPS） legs.This paper proposed a novel method to realize indirect force estimation on walking robot based on a spatial parallel mechanism.The direct kinematics model and the inverse kinematics model are established.The force Jacobian matrix is derived based on the kinematics model.Thus,the indirect force estimation model is established.Then,the relation between the output torques of the three motors installed on one leg to the external force exerted on the foot tip is described.Furthermore,an adaptive tripod static gait is designed.The robot alters its leg trajectory to step on obstacles by using the proposed adaptive gait.Both the indirect force estimation model and the adaptive gait are implemented and optimized in a real time control system.An experiment is carried out to validate the indirect force estimation model.The adaptive gait is tested in another experiment.Experiment results show that the robot can successfully step on a 0.2 m-high obstacle.This paper proposes a novel method to overcome obstacles for the six-legged robot using spatial parallel mechanism legs and to avoid installing the electric force sensors in harsh environment of the robot＇s foot tips.展开更多
基金financial support by the National Key Research and Development Program of China(No.2023YFC2907801)the Hunan Provincial Natural Science Foundation of China(No.2023JJ40760)the Scientific and Technological Project of Yunnan Precious Metals Laboratory,China(No.YPML-2023050276)。
文摘Bentonite is a necessary binder in producing pellets.Its excessive use reduces the iron grade of pellets and increases production costs.Minimizing bentonite dosage is essential for producing high-quality iron ore pellets.Addressing the gap in the application of organically-intercalated modified bentonite in the pelletizing field,this study introduces an innovative modification process for bentonite that employs the synergistic effect of mechanical force and dimethyl sulfoxide to enhance the intercalation of organic compounds within bentonite,thus significantly enhancing its binding performance.The colloid value and swell capacity of modified bentonite(98.5 m L/3g and 55.0 m L/g)were much higher than the original bentonite(90.5 m L/3g and 17.5 m L/g).With the decrease of bentonite dosage from1.5wt%to 1.0wt%,the drop number of green pellets from a height of 0.5 m and the compressive strengths of roasted pellets using the modified bentonite(6.0 times and 2916 N per pellet)were significantly higher than those of the original bentonite(4.0 times and 2739 N per pellet).This study provides a comprehensive analysis of the intercalation modification mechanism of bentonite,offering crucial technical insights for the development of high-performance modified bentonite as iron ore pellet binders.
基金supported by the National Key Research and Development Program of China(No.2022YFA1105800(R.L.Y.))Clinical Medicine Plus X-Young Scholars Project of Peking University(No.2025PKULCXQ015(R.L.Y.))+2 种基金Research Foundation of Peking University School and Hospital of Stomatology(No.PKUSS20230103)the Fundamental Research Funds for the Central Universities-Peking University Clinical Scientist Training Program(No.L232107(R.L.Y.))Beijing Municipal Natural Science Foundation-Haidian Original Innovation Joint Fund(Nos.L222001(Xiaomo Liu)and L232107(Jie Shi)).
文摘Mesenchymal stem cells(MSCs),which are mechanosensitive cells,mediate the cells crosstalk in response to mechanical force,thereby playing a crucial role in bone homeostasis.Migrasomes serve as an important mediator for cellular communication.However,whether the mechanical stimulus regulates the biology and property of migrasomes on bone metabolism remains unknown.This study shows that mechanical stimulus could promote MSCs to synthesize and secrete migrasomes,which could significantly alleviate chronic infectious bone destruction in periodontal tissue by inhibiting osteoclastic differentiation of macrophage and reestablishing local immune microenvironment.Mechanistically,miR-29b-3p is more abundant in migrasomes from mechanical force stimulated MSCs than in control ones.MiR-29b-3p blocks the activation of pyrin domain containing protein 3(NLRP3)and mitochondrial DNA(mtDNA)release by directly targeting on Tet1.Thus,mechanical sensing migrasomes inhibit osteoclast differentiation to alleviate inflammation induced bone destruction.These findings reveal that the mechanical stimulus controls the formation and properties of migrasomes,which provides a new biotechnological strategy for chronic infectious bone destruction intervention.
文摘Upon investigating the relative locations of internal and external forcing and the resultant mean meridional circula- tion,it was found that thermal forcing and mechanical forcing for the formation of atmospheric mean meridional circu- lation are modulated by a certain ratio.This ratio is determined by the inherent baroclinity,static stability and absolute vorticity of the atmosphere. By employing a parameterization scheme for radiative heating and condensation heating,together with the analysis data of the European Center for Medium-range Weather Forecasts,the mean meridional circulation for January was simulated numerically.It was found that latent heat release in the tropics may result in the formation of double-layered Hadley circulation,so do the eddy momentum transfer processes.On the other hand,mean meridional circulations in ex- tra-tropics are mainly determined by external momentum forcing and atmospheric properties of eddy momentum and heat transfer.
基金supported by grants from the National Natural Science Foundation of China(Grant Nos.81972455 and 81902358)。
文摘Mechanical forces in the tumor microenvironment(TME)are associated with tumor growth,proliferation,and drug resistance.Strong mechanical forces in tumors alter the metabolism and behavior of cancer cells,thus promoting tumor progression and metastasis.Mechanical signals are transformed into biochemical signals,which activate tumorigenic signaling pathways through mechanical transduction.Cancer immunotherapy has recently made exciting progress,ushering in a new era of“chemo-free”treatments.However,immunotherapy has not achieved satisfactory results in a variety of tumors,because of the complex tumor microenvironment.Herein,we discuss the effects of mechanical forces on the tumor immune microenvironment and highlight emerging therapeutic strategies for targeting mechanical forces in immunotherapy.
文摘The carbonization of magnesium oxide particles by CO2 was investigated using a stirring mill reactor. The effects of the system temperature, stirring rotation speed, influx rate of CO2 and initial diameter of the magnesium oxide particles on the carbonization process were determined, The results show that the system temperature and the stirring rotation speed are the most significant influencing factors on the carbonization rate. The determi-nation of critical decomposition temperature (CDT) gives the maximum carbonization rate with other conditions fixed. A theoretical model involving mass transfer and reaction kinetics was presented for the carbonization process. The apparent activation energy was calculated to be 32.8kJ·mol-1. The carbonization process is co-controlled by diffusive mass transfer and chemical reaction. The model fits well with the experimental results.
基金the National Natural Science Foundation of China(Grant No.11832008 and 11772073)by the Program of the Postgraduate Tutor Team,Chongqing Education Commission(2018).
文摘Cross-talk between tumor cells and mechanical stress in the tumor microenvironment has been shown to be involved in carcinogenesis.High mechanical stress in tumors can alter the metabolism and behaviors of cancer cells and cause cancer cells to attain cancer stem-like cell properties,thus driving tumor progression and promoting metastasis.The mechanical signal is converted into a biochemical signal that activates tumorigenic signaling pathways through mechanotransduction.Herein,we describe the physical changes occurring during reprogramming of cancer cell metabolism,which regulate cancer stem cell functions and promote tumor progression and aggression.Furthermore,we highlight emerging therapeutic strategies targeting mechanotransduction signaling pathways.
基金financially supported by the National Science Foundation of China(Grant No.41102102)"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No.XDB03020300)the Key Research Program of the Chinese Academy of Sciences(Grant No.KZZD-EW-04-03)
文摘Dune fields at the northern margin of the East Asian monsoon （EAM）, are mosaics of mobile and vegetation-stabilized aeolian dunes. These sand dunes are highly sensitive to environmental change, thus the distribution and the timing of their development may provide important clues to past environmental dynamics. Due to the strong wind erosion and dune migration, long and continuous stratigraphic records are seldom preserved. Synthesizing a large body of events, ultimately producing a relatively complete and high-resolution record, may be a proper method to investigate the dune development history and climate change. In this study, we synthesized a large body of luminescence ages for aeolian deposits from the Mu Us, Otindag, Horqin dune fields at the northern margin of the EAM. The results show that these dune fields, as a whole experienced a most extensive mobility during the early Holocene, followed by a widespread shift toward limited mobility and soil development in the mid-Holocene, and widespread reactivation occurred during late Holocene. The dune developments are directly linked to the effective moisture change controlled by the EAM changes, which respond to the low latitude summer insolation variation. The increased subsidence at the margin contrary to the core EAM, the delay from the feedback of the soil-vegetation-air coupled system, the increased evaporation due to the high temperature all play partial role in the lag of the margin EAM effective moisture change to the low latitude summer insolation. The asynchronous end of the wetter mid-Holocene mainly responds to the southeastwardly shift of the precipitation belt, while the regional sensitivity, response speed and internal feedback also contributed. The correspondence between dune records and North Atlantic drift-ice records of the rapid climate changes implies a close relationship between North Atlantic climate and the frequent dune activity at the northern margin of EAM.
基金National Natural Science Foundation of China Projects "Study on the Forced Mechanism of Carbon Emission Peak Target in China:Transition Pathways,Emission Reduction Performance and Economic Effects"[grant number:71673217],"Study on Green Behaviors of Households"[grant number:71573217]Shaanxi Soft Science Research Project "Cost and Benefit analysis of Residential End-use Demand Side Management under Smart Grid in Xi'an City"[grant number:2015KRM143]
文摘In order to make further steps in dealing with climate change, China proposed to peak carbon dioxide emissions by about 2030 and to make best efforts for the peaking early. The carbon emission peak target(CEPT) must result in a forcing mechanism on China's economic transition. This paper, by following the logical order from "research on carbon emission history" to "carbon emission trend prediction," from "research on paths of realizing peak" to "peak restraint research," provides a general review of current status and development trend of researches on China's carbon emission and its peak value. Furthermore,this paper also reviews the basic theories and specific cases of the forcing mechanism.Based on the existing achievements and development trends in this field, the following research directions that can be further expanded are put forward. First, from the perspective of long-term strategy of sustainable development, we should analyze and construct the forcing mechanism of CEPT in a reverse thinking way. Second, economic transition paths under the forcing mechanism should be systematically studied. Third, by constructing a large-scale policy evaluation model, the emission reduction performance and economic impact of a series of policy measures adopted during the transition process should be quantitatively evaluated.
文摘In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relation- ship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.
基金supported in part by the Natural Science Foundation of China under the grants of 11072165,31270995 and 81320108018
文摘To improve the osteogenic property of bone repairing materials and to accelerate bone healing are major tasks in bone biomaterials research. The objective of this study was to investigate if the mechanical force could be used to accelerate bone formation in a bony defect in vivo. The calcium sulfate cement was implanted into the left distal femoral epiphyses surgically in 16 rats. The half of rats were subjected to external mechanical force via treadmill exercise, the exercise started at day 7 postoperatively for 30 consecutive days and at a constant speed 8 m·min-1 for 45 min·day-1, while the rest served as a control. The rats were scanned four times longitudinally after surgery using microcomputed tomography and newly formed bone was evaluated. After sacrificing, the femurs had biomechanical test of three-point bending and histological analysis. The results showed that bone healing under mechanical force were better than the control with residual defect areas of 0.64±0.19 mm2 and 1.78±0.39 mm2（P〈0.001）, and the ultimate loads to failure under mechanical force were 69.56±4.74 N, stronger than the control with ultimate loads to failure of 59.17±7.48 N（P=0.039）. This suggests that the mechanical force might be used to improve new bone formation and potentially offer a clinical strategy to accelerate bone healing.
基金This work is funded by the National Natural Science Foundation of China(Grant nos.41941008 and 41876221)the Shanghai Science and Technology Committee(Grant nos.20230711100 and 21QA1404300)+2 种基金the Academy of Finland(Grant no.304345)the Ministry of Natural Resources of the People’s Republic of China(Impact and Response of Antarctic Seas to Climate Change,Grant no.IRASCC 1-02-01B)the Advanced Polar Science Institute of Shanghai(APSIS).
文摘Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP),and water mass formation for both coastal polynyas and open-ocean polynyas in the Southern Ocean,as well as the variability and controlling mechanisms of polynya processes on different time scales.Polynyas play an irreplaceable role in the regulation of global ocean circulation and biological processes in regional ocean ecosystems.The coastal polynyas(latent heat polynyas)are mainly located in the Weddell Sea,the Ross Sea and on the west side of protruding topographic features in East Antarctica.During the formation of coastal polynyas,which are mainly forced by offshore winds or ocean currents,brine rejection triggered by high SIP results in the formation of high salinity shelf water,which is the predecessor of the Antarctic bottom water-the lower limb of the global thermohaline circulation.The open-ocean polynyas(sensible heat polynyas)are mainly found in the Indian sector of the Southern Ocean,which are formed by ocean convection processes generated by topography and negative wind stress curl.The convection processes bring nutrients into the upper ocean,which supports biological production and makes the polynya regions an important sink for atmospheric carbon dioxide.The limitations and challenges in polynya research are also discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51272158 and 11302185)the Scientific Research Fund of Hunan Provincial Education Department,China(Grant No.13C901)the Hunan Provincial Natural Science Foundation,China(Grant Nos.14JJ3081 and 13JJ1019)
文摘The switching process of ferroelectric thin films in electronic devices is one of the most important requirements for their application. Especially for the different external fields acting on the film surface, the mechanism of domain switching is more complicated. Here we observe the nanoscale domain switchings of Bi3.15Eu0.85Ti3O12 thin film under different mechanical forces at a fast scan rate. As the force increases from initial state to 247.5 n N, the original bright or grey contrasts within the selected grains are all changed into dark contrasts corresponding to the polarization vectors reversed from the up state to the down state, except for the clusters. As the mechanical force increases to 495 n N, the color contrasts in all of the selected grains further turn into grey contrasts and some are even changed into grey contrasts completely showing the typical 90° domain switching. When another stronger loading force 742.5 n N is applied, the phase image becomes unclear and it indicates that the piezoelectric signal can be suppressed under a sufficiently high force, which is coincident with previous experimental results. Furthermore, we adopt the domain switching criterion from the perspective of equilibrium state free energy of ferroelectric nanodomain to explain the mechanisms of force-generated domain switchings.
基金supported by the National Natural Science Foundation of China(No.81770294)the Natural Science Foundation of Fujian Province(No.2023J05261),China.
文摘Artificial vascular graft(AVG)fistula is widely used for hemodialysis treatment in patients with renal failure.However,it has poor elasticity and compliance,leading to stenosis and thrombosis.The ideal artificial blood vessel for dialysis should replicate the structure and components of a real artery,which is primarily maintained by collagen in the extracellular matrix(ECM)of arterial cells.Studies have revealed that in hepatitis B virus(HBV)-induced liver fibrosis,hepatic stellate cells(HSCs)become hyperactive and produce excessive ECM fibers.Furthermore,mechanical stimulation can encourage ECM secretion and remodeling of a fiber structure.Based on the above factors,we transfected HSCs with the hepatitis B viral X(HBX)gene for simulating the process of HBV infection.Subsequently,these HBX-HSCs were implanted into a polycaprolactonepolyurethane(PCL-PU)bilayer scaffold in which the inner layer is dense and the outer layer consists of pores,which was mechanically stimulated to promote the secretion of collagen nanofiber from the HBX-HSCs and to facilitate crosslinking with the scaffold.We obtained an ECM-PCL-PU composite bionic blood vessel that could act as access for dialysis after decellularization.Then,the vessel scaffold was implanted into a rabbit’s neck arteriovenous fistula model.It exhibited strong tensile strength and smooth blood flow and formed autologous blood vessels in the rabbit’s body.Our study demonstrates the use of human cells to create biomimetic dialysis blood vessels,providing a novel approach for creating clinical vascular access for dialysis.
基金supported by Natural Science Foundation of China grants10732070,10602031
文摘BK channels are widely expressed in both excitable and non-excitable cells and known to be involved in many physiological processes,such as vascular smooth tone regulation,neuronal firing and endocrine cell secretion[1].Recently, the BK channels have
文摘Convection and its ensuing severe weather, such as heavy rainfall, hail, tornado, and high wind, have significant im- pacts on our society and economy （e.g., Cao et al., 2004; Fritsch and Carbone, 2004; Verbout et al., 2006; Ashley and Black, 2008; Cao, 2008; Cao and Ma, 2009; Zhang et al., 2014）. Due to its localized and transient nature, the initiation of convection or convective initiation remains one of the least understood aspects of convection in the scientific communi- ties, and it is a significant challenge to accurately predict the exact timing and location of convective initiation （e.g., Cai et al., 2006; Wilson and Roberts, 2006; Xue and Martin, 2006; Cao and Zhang, 2016）.
文摘The vibration response formulas of the mechanical system under the affect of thevari-frequency exciting force are deduced. It is proved by the theoretical analysis and experimentalresults that the vibration response amplitude of the mechanical system under the affect of thevari-frequency exciting force is far smaller than that under the affect of the constant frequency exciting force on condition that the exciting force amplitudes are just the same;while the vari-fre-quency rate a increases to 5 Hz per second the vibration amplitude will decrease to 10% only as lowas that under the affect of the constant frequency exciting force. All these conclusions will be of significance for revealing the mechanism of suppressing chatter in van-speed cutting and analyzing theexperimental results of sine-wave scanning exciting test.
文摘Cells are exposed to various mechanical forces,including extracellular and intracellular forces such as stiffness,tension,compression,viscosity,and shear stress,which regulate cell biology.The process of transducing mechanical stimuli into biochemical signals is termed mechanotransduction.These mechanical forces can regulate protein and gene expression,thereby impacting cell morphology,adhesion,proliferation,apoptosis,and migration.During cancer development,significant changes in extracellular and intracellular mechanical properties occur,resulting in altered mechanical inputs to which cells are exposed.MicroRNAs(miRNAs),key post-transcriptional regulators of gene and protein expression,are increasingly recognized as mechanosensitive molecules involved in cancer development.In this review,we summarize the primary cellular pathways involved in force sensing and mechanotransduction,emphasizing the role of forces in miRNA biogenesis and expression,as well as their influence on the regulation of key mechanotransducers.Furthermore,we focus on recent evidence regarding the induction or repression of miRNAs involved in cancer development by mechanical forces and their impact on the regulation of proteins that contribute to cancer progression.
基金supported by the Gansu Province Outstanding Youth Fund(No.23JRRA1016)the National Natural Science Foundation of China(Nos.42422102,42071101,41907379)the National Key R&D Program of China(No.2022YFF0801501)。
文摘The response of lake environments in arid Central Asia to climate change during the Late Holocene over the centennial to millennial timescales remains contentious.The reason that primarily paleoenvironmental proxies diverse and the scarcity of accurate quantitative reconstruction records.In this study,we employed diatoms and pollen records from lacustrine sediment in the Aibi Lake of Southwest Junggar Basin to quantitatively reconstruct salinity and watershed precipitation amounts while exploring the associated forcing mechanisms.The results indicate that Aibi Lake salinity varied between 2 and 47 g/L during the Late Holocene Period,indicating a generally brackish environment,and corresponding to prevailing Tryblionella granulata diatom in the lake basin.Westerly-dominated annual precipitation varied between 250 and 320 mm during the Late Holocene Period in the basin,exhibiting a generally semi-arid environment and prevailing desert steppe vegetation.The Aibi Lake has a low salinity of average value of~15 g/L and exhibits elevated precipitation(average value of~280 mm)during the periods of the 2900-1990,1570-1140,and 590-120 cal yr BP.The reconstructed precipitation and salinity exhibit a periodicity of~200 years,which is consistent with the cycle of phase changes of the North Atlantic oscillation(NAO)and total solar irradiance(TSI).This correlation suggests that variations in NOA and TSI significantly influence the precipitation and salinity changes in Central Asia over centennial to millennial timescales.
基金supported by National Key R&D Program of China (Grant No. 2017YFC1501100)the National Natural Science Foundation of China (Grant No. 51279090)Sponsored by Research Fund for Excellent Dissertation of China Three Gorges University
文摘Shallow slope failures induced by rainfall infiltration occur frequently, and the relevant triggering mechanisms have been widely studied.Rainfall-induced landslides are widely recognized to be caused by increases in soil weight, seepage force and pore water pressure or decreases in soil mechanical properties. However, even when all these factors are considered, some landslides still cannot be explained well. The increased pore water pressure in a slope reduces the effective stress of the soil and may trigger slope failure. Similarly, the pore gas pressure in a slope also reduces the effective stress of the soil but has been neglected in previous studies. As the viscosity of air is nearly negligible when compared with that of water, the pore gas pressure spreads faster, and its influence is wider, which is harmful for the stability of the slope. In this paper, the effects of pore gas pressure are considered in a shallow slope stability analysis, and a self-designed experiment is conducted to validate the force transfer mechanism.Numerical simulation results show that the pore gas pressure in the slope increases sharply at different locations under heavy rainfall conditions and that the pore gas pressure causes a rapid decrease in the slope safety factor. Laboratory experimental results show that the pore gas pressure throughout the whole unsaturated zone has the same value, which indicates that the gas pressure could spread quickly to the whole sample.
基金Supported by National Basic Research Program of China(973 Program,Grant No.2013CB035501)Research Fund of the State Key Lab of MSV of China(Grant No.MSV201208)
文摘Adaptive gaits for legged robots often requires force sensors installed on foot-tips,however impact,temperature or humidity can affect or even damage those sensors.Efforts have been made to realize indirect force estimation on the legged robots using leg structures based on planar mechanisms.Robot Octopus III is a six-legged robot using spatial parallel mechanism（UP-2UPS） legs.This paper proposed a novel method to realize indirect force estimation on walking robot based on a spatial parallel mechanism.The direct kinematics model and the inverse kinematics model are established.The force Jacobian matrix is derived based on the kinematics model.Thus,the indirect force estimation model is established.Then,the relation between the output torques of the three motors installed on one leg to the external force exerted on the foot tip is described.Furthermore,an adaptive tripod static gait is designed.The robot alters its leg trajectory to step on obstacles by using the proposed adaptive gait.Both the indirect force estimation model and the adaptive gait are implemented and optimized in a real time control system.An experiment is carried out to validate the indirect force estimation model.The adaptive gait is tested in another experiment.Experiment results show that the robot can successfully step on a 0.2 m-high obstacle.This paper proposes a novel method to overcome obstacles for the six-legged robot using spatial parallel mechanism legs and to avoid installing the electric force sensors in harsh environment of the robot＇s foot tips.
