Prof.Yun Zhang was born on 9 July 1963 in Kunming,Yunnan,China,during a tumultuous period which he often referenced.Throughout his life,he harbored a steadfast belief in using knowledge to unravel the mysteries of hum...Prof.Yun Zhang was born on 9 July 1963 in Kunming,Yunnan,China,during a tumultuous period which he often referenced.Throughout his life,he harbored a steadfast belief in using knowledge to unravel the mysteries of human diseases.His educational journey was marked by frequent changes in schools due to his parents’occupational relocations.However,despite these challenges,he consistently displayed diligence and was admitted to the East China University of Science and Technology,Shanghai,after completing high school in 1980.He remained an active and loyal member of the School of Biotechnology at the university.展开更多
In Senegal, particularly in the Senegal River valley, agricultural mechanization remains limited, mainly due to a lack of agricultural equipment, a lack of expertise in agricultural machinery and an apprehension of th...In Senegal, particularly in the Senegal River valley, agricultural mechanization remains limited, mainly due to a lack of agricultural equipment, a lack of expertise in agricultural machinery and an apprehension of the consequences on soil quality. To better understand agricultural mechanization of rice cultivation, this survey study has been carried out in the Senegal river valley. Precisely, this work aimed to characterize farm machinery and its effects on soil and rice cultivation. A questionnaire was administered to 304 out of 1270 farmers, spread over 8 rice-growing areas, 4 of which are located in the Podor department, three in Dagana and one in Saint-Louis. The results showed that 99.3% of farmers used motorized equipment, with 95.7% using tractor and 3.6% a power tiller. Offset tillage, which is a shallow cultivation practice carried out to break up hard soil without turning it over, was most widespread among growers (95.4%). 78.3% of the valley’s farmers felt that the machinery used to carry out tillage operations was inefficient. According to the farmers, the main constraints on the use of agricultural machinery in the valley were: the upkeep and maintenance of equipment (57%), the lack of expertise in mechanization (31%), and issues adapting machinery to local conditions (12%). Those constraints have contributed to a drop in yields in recent years, the spread of weeds on cultivated plots and the gradual degradation of the soil in the area according to 78% of farmers.展开更多
Infertility represents a significant health concern,with sperm quantity and quality being crucial determinants of male fertility.Oligoasthenoteratozoospermia(OAT)is characterized by reduced sperm motility,lower sperm ...Infertility represents a significant health concern,with sperm quantity and quality being crucial determinants of male fertility.Oligoasthenoteratozoospermia(OAT)is characterized by reduced sperm motility,lower sperm concentration,and morphological abnormalities in sperm heads and flagella.Although variants in several genes have been implicated in OAT,its genetic etiologies and pathogenetic mechanisms remain inadequately understood.In this study,we identified a homozygous nonsense mutation(c.916C>T,p.Arg306*)in the coiled-coil domain containing 146(CCDC146)gene in an infertile male patient with OAT.This mutation resulted in the production of a truncated CCDC146 protein(amino acids 1-305),retaining only two out of five coiled-coil domains.To validate the pathogenicity of the CCDC146 mutation,we generated a mouse model(Ccdc146^(mut/mut))with a similar mutation to that of the patient.Consistently,the Ccdc146mut/mut mice exhibited infertility,characterized by significantly reduced sperm counts,diminished motility,and multiple defects in sperm heads and flagella.Furthermore,the levels of axonemal proteins,including DNAH17,DNAH1,and SPAG6,were significantly reduced in the sperm of Ccdc146^(mut/mut) mice.Additionally,both human and mouse CCDC146 interacted with intraflagellar transport protein 20(IFT20),but this interaction was lost in the mutated versions,leading to the degradation of IFT20.This study identified a novel deleterious homozygous nonsense mutation in CCDC146 that causes male infertility,potentially by disrupting axonemal protein transportation.These findings offer valuable insights for genetic counseling and understanding the mechanisms underlying CCDC146 mutant-associated infertility in human males.展开更多
Spinal cord injury results in the loss of sensory,motor,and autonomic functions,which almost always produces permanent physical disability.Thus,in the search for more effective treatments than those already applied fo...Spinal cord injury results in the loss of sensory,motor,and autonomic functions,which almost always produces permanent physical disability.Thus,in the search for more effective treatments than those already applied for years,which are not entirely efficient,researches have been able to demonstrate the potential of biological strategies using biomaterials to tissue manufacturing through bioengineering and stem cell therapy as a neuroregenerative approach,seeking to promote neuronal recovery after spinal cord injury.Each of these strategies has been developed and meticulously evaluated in several animal models with the aim of analyzing the potential of interventions for neuronal repair and,consequently,boosting functional recovery.Although the majority of experimental research has been conducted in rodents,there is increasing recognition of the importance,and need,of evaluating the safety and efficacy of these interventions in non-human primates before moving to clinical trials involving therapies potentially promising in humans.This article is a literature review from databases(PubMed,Science Direct,Elsevier,Scielo,Redalyc,Cochrane,and NCBI)from 10 years ago to date,using keywords(spinal cord injury,cell therapy,non-human primates,humans,and bioengineering in spinal cord injury).From 110 retrieved articles,after two selection rounds based on inclusion and exclusion criteria,21 articles were analyzed.Thus,this review arises from the need to recognize the experimental therapeutic advances applied in non-human primates and even humans,aimed at deepening these strategies and identifying the advantages and influence of the results on extrapolation for clinical applicability in humans.展开更多
Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas an...Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.展开更多
Objective:To investigate the therapeutic effects and mechanisms of human mesenchymal stem cell-derived exosomes(hMSCs-Exo)carrying the NGF gene in treating ischemic stroke in rats,aiming to provide new insights and tr...Objective:To investigate the therapeutic effects and mechanisms of human mesenchymal stem cell-derived exosomes(hMSCs-Exo)carrying the NGF gene in treating ischemic stroke in rats,aiming to provide new insights and treatment methods for ischemic stroke therapy.Methods:After successful construction of the cerebral ischemia model in 40 male SPF-grade SD rats aged 6-8 weeks,the model rats were randomly divided into 4 groups:Sham group,PBS group,hMSCs-Exo group,and NGF-hMSCs-Exo group,with 10 rats in each group.The rat MCAO model was prepared using the classic filament method,and NGF-hMSCs-Exo were injected via the tail vein into the MCAO model rats.The expression of the NGF gene in brain ischemic tissues,neuronal regeneration,and rat neurological function recovery were observed using TTC staining,memory function evaluation,Western blot,qRT-PCR,and other methods.Results:Compared with the Sham group,neurological deficits were significant in the PBS group(P<0.01).Compared with the PBS group,neurological scores improved in the hMSCs-Exo group and NGF-hMSCs-Exo group(P<0.05).Compared with the hMSCs-Exo group,the improvement in neurological deficits was more significant in the NGF-hMSCs-Exo group(P<0.05).The infarct area after NGF-hMSCs-Exo intervention was significantly reduced(P<0.05)compared with the Sham group.Compared with the PBS group,relative expression levels of NGF mRNA and protein decreased,while Caspase-3 mRNA and protein expression significantly increased in the PBS group(P<0.01).Compared with the PBS group and hMSCs-Exo group,there were differences in NGF and Caspase-3 mRNA and protein expression in the NGF-hMSCs-Exo group rat brain tissues(P<0.05).Conclusion:Treatment with human mesenchymal stem cell-derived exosomes carrying the NGF gene improves cognitive function and exerts protective effects on SD rats while inhibiting apoptotic levels in cells.展开更多
Birds are good friends of humans.They kill a great number of pests.But it seems that humans are not friendly to them.Humans use much pesticide to kill pests.But a lot of birds are killed at the same time.Sometimes,hum...Birds are good friends of humans.They kill a great number of pests.But it seems that humans are not friendly to them.Humans use much pesticide to kill pests.But a lot of birds are killed at the same time.Sometimes,humans directly kill birds.Some people kill birds for food,money or even fun.So the number of birds has become smaller and smaller.展开更多
Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the ...Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the nucleosome,generated using cryoelectron microscopy(cryo-EM),cross-linking mass spectrometry,and homology modeling.展开更多
Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the ...Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the nucleosome,generated using cryoelectron microscopy(cryo-EM),cross-linking mass spectrometry,and homology modeling.BAF complexes bilaterally engage the nucleosome H2A/H2B acidic patch regions through the SMARCB1 C-terminalα-helix and the SMARCA4/2 C-terminal SnAc/postSnAc regions,with disease-associated mutations in either causing attenuated chromatin remodeling activities.Further,we define changes in BAF complex architecture upon nucleosome engagement and compare the structural model of endogenous BAF to those of related SWI/SNF-family complexes.Finally,we assign and experimentally interrogate cancer-associated hot-spot mutations localizing within the endogenous human BAF complex,identifying those that disrupt BAF subunit-subunit and subunit-nucleosome interfaces in the nucleosome-bound conformation.Taken together,this integrative structural approach provides important biophysical foundations for understanding the mechanisms of BAF complex function in normal and disease states.展开更多
Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in China.It is necessary to investigate the impac...Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in China.It is necessary to investigate the impacts of climate change and human activities on hydrological evolution and disaster risk from a holistic perspective of the basin.This study developed initiatives to clarify the mechanisms of hydrological evolution in the human-influenced Yellow River Basin.The proposed research method includes:(1)a tool to simulate multiple factors and a multi-scale water cycle using a grid-based spatiotemporal coupling approach,and(2)a new algorithm to separate the responses of the water cycle to climate change and human impacts,and de-couple the eco-environmental effects using artificial intelligence techniques.With this research framework,key breakthroughs are expected to be made in the understanding of the impacts of land cover change on the water cycle and blue/green water redirection.The outcomes of this research project are expected to provide theoretical support for ecological protection and water governance in the basin.展开更多
BACKGROUND Globally,complete neurological recovery of spinal cord injury(SCI)is still less than 1%,and 90%experience permanent disability.The key issue is that a pharmacological neuroprotective-neuroregenerative agent...BACKGROUND Globally,complete neurological recovery of spinal cord injury(SCI)is still less than 1%,and 90%experience permanent disability.The key issue is that a pharmacological neuroprotective-neuroregenerative agent and SCI regeneration mechanism have not been found.The secretomes of stem cell are an emerging neurotrophic agent,but the effect of human neural stem cells(HNSCs)secretome on SCI is still unclear.AIM To investigate the regeneration mechanism of SCI and neuroprotective-neuroregenerative effects of HNSCs-secretome on subacute SCI post-laminectomy in rats.METHODS An experimental study was conducted with 45 Rattus norvegicus,divided into 15 normal,15 control(10 mL physiologic saline),and 15 treatment(30μL HNSCssecretome,intrathecal T10,three days post-traumatic).Locomotor function was evaluated weekly by blinded evaluators.Fifty-six days post-injury,specimens were collected,and spinal cord lesion,free radical oxidative stress(F2-Isoprostanes),nuclear factor-kappa B(NF-κB),matrix metallopeptidase 9(MMP9),tumor necrosis factor-alpha(TNF-α),interleukin-10(IL-10),transforming growth factor-beta(TGF-β),vascular endothelial growth factor(VEGF),B cell lymphoma-2(Bcl-2),nestin,brain-derived neurotrophic factor(BDNF),glial cell line-derived neurotrophic factor(GDNF)were analyzed.The SCI regeneration mechanism was analyzed using partial least squares structural equation modeling(PLS SEM).RESULTS HNSCs-secretome significantly improved locomotor recovery according to Basso,Beattie,Bresnahan(BBB)scores and increased neurogenesis(nestin,BDNF,and GDNF),neuroangiogenesis(VEGF),anti-apoptotic(Bcl-2),anti-inflammatory(IL-10 and TGF-β),but decreased proinflammatory(NF-κB,MMP9,TNF-α),F2-Isoprostanes,and spinal cord lesion size.The SCI regeneration mechanism is valid by analyzed outer model,inner model,and hypothesis testing in PLS SEM,started with pro-inflammation followed by anti-inflammation,anti-apoptotic,neuroangiogenesis,neurogenesis,and locomotor function.CONCLUSION HNSCs-secretome as a potential neuroprotective-neuroregenerative agent for the treatment of SCI and uncover the SCI regeneration mechanism.展开更多
BACKGROUND Ferroptosis can induce low retention and engraftment after mesenchymal stem cell(MSC)delivery,which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension(PAH)ther...BACKGROUND Ferroptosis can induce low retention and engraftment after mesenchymal stem cell(MSC)delivery,which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension(PAH)therapy.Interestingly,the cystathionineγ-lyase(CSE)/hydrogen sulfide(H_(2)S)pathway may contribute to mediating ferroptosis.However,the influence of the CSE/H_(2)S pathway on ferroptosis in human umbilical cord MSCs(HUCMSCs)remains unclear.AIM To clarify whether the effect of HUCMSCs on vascular remodelling in PAH mice is affected by CSE/H_(2)S pathway-mediated ferroptosis,and to investigate the functions of the CSE/H_(2)S pathway in ferroptosis in HUCMSCs and the underlying mechanisms.METHODS Erastin and ferrostatin-1(Fer-1)were used to induce and inhibit ferroptosis,respectively.HUCMSCs were transfected with a vector to overexpress or inhibit expression of CSE.A PAH mouse model was established using 4-wk-old male BALB/c nude mice under hypoxic conditions,and pulmonary pressure and vascular remodelling were measured.The survival of HUCMSCs after delivery was observed by in vivo bioluminescence imaging.Cell viability,iron accumulation,reactive oxygen species production,cystine uptake,and lipid peroxidation in HUCMSCs were tested.Ferroptosis-related proteins and S-sulfhydrated Kelchlike ECH-associating protein 1(Keap1)were detected by western blot analysis.RESULTS In vivo,CSE overexpression improved cell survival after erastin-treated HUCMSC delivery in mice with hypoxiainduced PAH.In vitro,CSE overexpression improved H_(2)S production and ferroptosis-related indexes,such as cell viability,iron level,reactive oxygen species production,cystine uptake,lipid peroxidation,mitochondrial membrane density,and ferroptosis-related protein expression,in erastin-treated HUCMSCs.In contrast,in vivo,CSE inhibition decreased cell survival after Fer-1-treated HUCMSC delivery and aggravated vascular remodelling in PAH mice.In vitro,CSE inhibition decreased H_(2)S levels and restored ferroptosis in Fer-1-treated HUCMSCs.Interestingly,upregulation of the CSE/H_(2)S pathway induced Keap1 S-sulfhydration,which contributed to the inhibition of ferroptosis.CONCLUSION Regulation of the CSE/H_(2)S pathway in HUCMSCs contributes to the inhibition of ferroptosis and improves the suppressive effect on vascular remodelling in mice with hypoxia-induced PAH.Moreover,the protective effect of the CSE/H_(2)S pathway against ferroptosis in HUCMSCs is mediated via S-sulfhydrated Keap1/nuclear factor erythroid 2-related factor 2 signalling.The present study may provide a novel therapeutic avenue for improving the protective capacity of transplanted MSCs in PAH.展开更多
Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensiona...Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.展开更多
Visual odometry is critical in visual simultaneous localization and mapping for robot navigation.However,the pose estimation performance of most current visual odometry algorithms degrades in scenes with unevenly dist...Visual odometry is critical in visual simultaneous localization and mapping for robot navigation.However,the pose estimation performance of most current visual odometry algorithms degrades in scenes with unevenly distributed features because dense features occupy excessive weight.Herein,a new human visual attention mechanism for point-and-line stereo visual odometry,which is called point-line-weight-mechanism visual odometry(PLWM-VO),is proposed to describe scene features in a global and balanced manner.A weight-adaptive model based on region partition and region growth is generated for the human visual attention mechanism,where sufficient attention is assigned to position-distinctive objects(sparse features in the environment).Furthermore,the sum of absolute differences algorithm is used to improve the accuracy of initialization for line features.Compared with the state-of-the-art method(ORB-VO),PLWM-VO show a 36.79%reduction in the absolute trajectory error on the Kitti and Euroc datasets.Although the time consumption of PLWM-VO is higher than that of ORB-VO,online test results indicate that PLWM-VO satisfies the real-time demand.The proposed algorithm not only significantly promotes the environmental adaptability of visual odometry,but also quantitatively demonstrates the superiority of the human visual attention mechanism.展开更多
Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a p...Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.展开更多
Surrounding rocks of underground engineering are subjected to long-term seepage pressure,which can deteriorate the mechanical properties and cause serious disasters.In order to understand the impact of seepage pressur...Surrounding rocks of underground engineering are subjected to long-term seepage pressure,which can deteriorate the mechanical properties and cause serious disasters.In order to understand the impact of seepage pressure on the mechanical property of sandstone,uniaxial compression tests,P-wave velocity measurements,and nuclear magnetic resonance(NMR)tests were conducted on saturated sandstone samples with varied seepage pressures(i.e.0 MPa,3 MPa,4 MPa,5 MPa,6 MPa,7 MPa).The results demonstrate that the mechanical parameters(uniaxial compressive strength,peak strain,elastic modulus,and brittleness index),total energy,elastic strain energy,as well as elastic strain energy ratio,decrease with increasing seepage pressure,while the dissipation energy and dissipation energy ratio increase.Moreover,as seepage pressure increases,the micro-pores gradually transform into meso-pores and macro-pores.This increases the cumulative porosity of sandstone and decreases P-wave velocity.The numerical results indicate that as seepage pressure rises,the number of tensile cracks increases progressively,the angle range of microcracks is basically from 50-120to 80-100,and as a result,the failure mode transforms to the tensile-shear mixed failure mode.Finally,the effects of seepage pressure on mechanical properties were discussed.The results show that decrease in the effective stress and cohesion under the action of seepage pressure could lead to deterioration of strength behaviors of sandstone.展开更多
The remarkable properties of carbon nanotubes(CNTs)have led to promising applications in the field of electromagnetic inter-ference(EMI)shielding.However,for macroscopic CNT assemblies,such as CNT film,achieving high ...The remarkable properties of carbon nanotubes(CNTs)have led to promising applications in the field of electromagnetic inter-ference(EMI)shielding.However,for macroscopic CNT assemblies,such as CNT film,achieving high electrical and mechanical properties remains challenging,which heavily depends on the tube-tube interac-tions of CNTs.Herein,we develop a novel strategy based on metal-organic decomposition(MOD)to fabricate a flexible silver-carbon nanotube(Ag-CNT)film.The Ag particles are introduced in situ into the CNT film through annealing of MOD,leading to enhanced tube-tube interactions.As a result,the electrical conductivity of Ag-CNT film is up to 6.82×10^(5) S m^(-1),and the EMI shielding effectiveness of Ag-CNT film with a thickness of~7.8μm exceeds 66 dB in the ultra-broad frequency range(3-40 GHz).The tensile strength and Young’s modulus of Ag-CNT film increase from 30.09±3.14 to 76.06±6.20 MPa(~253%)and from 1.12±0.33 to 8.90±0.97 GPa(~795%),respectively.Moreover,the Ag-CNT film exhibits excellent near-field shield-ing performance,which can effectively block wireless transmission.This innovative approach provides an effective route to further apply macroscopic CNT assemblies to future portable and wearable electronic devices.展开更多
The deformation in sedimentary rock induced by train loads has potential threat to the safe operation of tunnels. This study investigated the influence of stratification structure on the infrared radiation and tempora...The deformation in sedimentary rock induced by train loads has potential threat to the safe operation of tunnels. This study investigated the influence of stratification structure on the infrared radiation and temporal damage mechanism of hard siltstone. The uniaxial compression tests, coupled with acoustic emission(AE) and infrared radiation temperature(IRT) were conducted on siltstones with different stratification effects. The results revealed that the stratigraphic structure significantly affects the stress-strain response and strength degradation characteristics. The mechanical parameters exhibit anisotropy characteristics, and the stratification effect exhibits a negative correlation with the cracking stress and peak stress. The failure modes caused by the stratification effect show remarkable anisotropic features, including splitting failure(Ⅰ: 0°-22.50°, Ⅱ: 90°), composite failure(45°), and shearing failure(67.50°). The AE temporal sequences demonstrate a stepwise response characteristic to the loading stress level. The AE intensity indicates that the stress sensitivity of shearing failure and composite failure is generally greater than that of splitting failure. The IRT field has spatiotemporal migration and progressive dissimilation with stress loading and its dissimilation degree increases under higher stress levels. The stronger the stratification effect, the greater the dissimilation degree of the IRT field. The abnormal characteristic points of average infrared radiation temperature(AIRT) variance at local stress drop and peak stress can be used as early and late precursors to identify fracture instability. Theoretical analysis shows that the competitive relationship between compaction strengthening and fracturing damage intensifies the dissimilation of the infrared thermal field for an increasing stress level. The present study provides a theoretical reference for disaster warnings in hard sedimentary rock mass.展开更多
Heart injury such as myocardial infarction leads to cardiomyocyte loss,fibrotic tissue deposition,and scar formation.These changes reduce cardiac contractility,resulting in heart failure,which causes a huge public hea...Heart injury such as myocardial infarction leads to cardiomyocyte loss,fibrotic tissue deposition,and scar formation.These changes reduce cardiac contractility,resulting in heart failure,which causes a huge public health burden.Military personnel,compared with civilians,is exposed to more stress,a risk factor for heart diseases,making cardiovascular health management and treatment innovation an important topic for military medicine.So far,medical intervention can slow down cardiovascular disease progression,but not yet induce heart regeneration.In the past decades,studies have focused on mechanisms underlying the regenerative capability of the heart and applicable approaches to reverse heart injury.Insights have emerged from studies in animal models and early clinical trials.Clinical interventions show the potential to reduce scar formation and enhance cardiomyocyte proliferation that counteracts the pathogenesis of heart disease.In this review,we discuss the signaling events controlling the regeneration of heart tissue and summarize current therapeutic approaches to promote heart regeneration after injury.展开更多
In this study,the extruded Mg-Zn-Mn-Ce-Ca alloy tube with a low compression anisotropy along the ED,45ED and TD was prepared.The effect of the second phases,initial texture and deformation behavior on this low mechani...In this study,the extruded Mg-Zn-Mn-Ce-Ca alloy tube with a low compression anisotropy along the ED,45ED and TD was prepared.The effect of the second phases,initial texture and deformation behavior on this low mechanical anisotropy was investigated.The results revealed that the alloy tube contains the high content(Mg1-xZnx)11Ce phase and the low content of Mg12Ce phase.These second phases are respectively incoherent and coherent with the Mg matrix,and their influence can be ignored.Additionally,the alloy tube exhibited a weak basal fiber texture,where the c-axis was aligned along the 0°∼30°tilt from TD to ED.Such a texture made the initial deformation(at 1.0%∼1.6%strain)of the three samples controlled by comparable basalslip.As deformation progressed(1.6∼9.0%strain),larger amounts of ETWs nucleated and gradually approached saturation in the three samples,re-orienting the c-axis to a 0°∼±30°deviation with respect to the loading directions.Meanwhile,the prismatic and pyramidal<c+a>slips replaced the dominant deformation progressively until fracture.Eventually,the similar deformation mechanisms determined by the weak initial texture in the three samples contribute to the comparable strain hardening rates,resulting in the low compressive anisotropy of the alloy tube.展开更多
文摘Prof.Yun Zhang was born on 9 July 1963 in Kunming,Yunnan,China,during a tumultuous period which he often referenced.Throughout his life,he harbored a steadfast belief in using knowledge to unravel the mysteries of human diseases.His educational journey was marked by frequent changes in schools due to his parents’occupational relocations.However,despite these challenges,he consistently displayed diligence and was admitted to the East China University of Science and Technology,Shanghai,after completing high school in 1980.He remained an active and loyal member of the School of Biotechnology at the university.
文摘In Senegal, particularly in the Senegal River valley, agricultural mechanization remains limited, mainly due to a lack of agricultural equipment, a lack of expertise in agricultural machinery and an apprehension of the consequences on soil quality. To better understand agricultural mechanization of rice cultivation, this survey study has been carried out in the Senegal river valley. Precisely, this work aimed to characterize farm machinery and its effects on soil and rice cultivation. A questionnaire was administered to 304 out of 1270 farmers, spread over 8 rice-growing areas, 4 of which are located in the Podor department, three in Dagana and one in Saint-Louis. The results showed that 99.3% of farmers used motorized equipment, with 95.7% using tractor and 3.6% a power tiller. Offset tillage, which is a shallow cultivation practice carried out to break up hard soil without turning it over, was most widespread among growers (95.4%). 78.3% of the valley’s farmers felt that the machinery used to carry out tillage operations was inefficient. According to the farmers, the main constraints on the use of agricultural machinery in the valley were: the upkeep and maintenance of equipment (57%), the lack of expertise in mechanization (31%), and issues adapting machinery to local conditions (12%). Those constraints have contributed to a drop in yields in recent years, the spread of weeds on cultivated plots and the gradual degradation of the soil in the area according to 78% of farmers.
基金supported by the National Key Research and Developmental Program of China(2021YFC2700202,2022YFC2702601,2019YFA0802600,2022YFA0806303)National Natural Science Foundation of China(32470915,32000587,32270901,82171601)+1 种基金Global Select Project(DJK-LX-2022010)of the Institute of Health and Medicine,Hefei Comprehensive National Science Center,Joint Fund for New Medicine of USTC(YD9100002034)Scientific Research Foundation for Scholars of the First Affiliated Hospital of USTC(RC2023054)。
文摘Infertility represents a significant health concern,with sperm quantity and quality being crucial determinants of male fertility.Oligoasthenoteratozoospermia(OAT)is characterized by reduced sperm motility,lower sperm concentration,and morphological abnormalities in sperm heads and flagella.Although variants in several genes have been implicated in OAT,its genetic etiologies and pathogenetic mechanisms remain inadequately understood.In this study,we identified a homozygous nonsense mutation(c.916C>T,p.Arg306*)in the coiled-coil domain containing 146(CCDC146)gene in an infertile male patient with OAT.This mutation resulted in the production of a truncated CCDC146 protein(amino acids 1-305),retaining only two out of five coiled-coil domains.To validate the pathogenicity of the CCDC146 mutation,we generated a mouse model(Ccdc146^(mut/mut))with a similar mutation to that of the patient.Consistently,the Ccdc146mut/mut mice exhibited infertility,characterized by significantly reduced sperm counts,diminished motility,and multiple defects in sperm heads and flagella.Furthermore,the levels of axonemal proteins,including DNAH17,DNAH1,and SPAG6,were significantly reduced in the sperm of Ccdc146^(mut/mut) mice.Additionally,both human and mouse CCDC146 interacted with intraflagellar transport protein 20(IFT20),but this interaction was lost in the mutated versions,leading to the degradation of IFT20.This study identified a novel deleterious homozygous nonsense mutation in CCDC146 that causes male infertility,potentially by disrupting axonemal protein transportation.These findings offer valuable insights for genetic counseling and understanding the mechanisms underlying CCDC146 mutant-associated infertility in human males.
文摘Spinal cord injury results in the loss of sensory,motor,and autonomic functions,which almost always produces permanent physical disability.Thus,in the search for more effective treatments than those already applied for years,which are not entirely efficient,researches have been able to demonstrate the potential of biological strategies using biomaterials to tissue manufacturing through bioengineering and stem cell therapy as a neuroregenerative approach,seeking to promote neuronal recovery after spinal cord injury.Each of these strategies has been developed and meticulously evaluated in several animal models with the aim of analyzing the potential of interventions for neuronal repair and,consequently,boosting functional recovery.Although the majority of experimental research has been conducted in rodents,there is increasing recognition of the importance,and need,of evaluating the safety and efficacy of these interventions in non-human primates before moving to clinical trials involving therapies potentially promising in humans.This article is a literature review from databases(PubMed,Science Direct,Elsevier,Scielo,Redalyc,Cochrane,and NCBI)from 10 years ago to date,using keywords(spinal cord injury,cell therapy,non-human primates,humans,and bioengineering in spinal cord injury).From 110 retrieved articles,after two selection rounds based on inclusion and exclusion criteria,21 articles were analyzed.Thus,this review arises from the need to recognize the experimental therapeutic advances applied in non-human primates and even humans,aimed at deepening these strategies and identifying the advantages and influence of the results on extrapolation for clinical applicability in humans.
基金supported by the project of China Geological Survey(Grant No.DD20221677-2)the fundamental research funds of Chinese Academy of Geological Sciences Basal Research Fund(Grant No.JKYQN202307).
文摘Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety,especially in aggregated population areas and economic hubs.This study focuses on the high F^(−)and NO_(3)^(−)concentration groundwater in Tongzhou District,Beijing,North China.A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics,elucidate genetic mechanisms and evaluate the potential human health risks.The results of the analysis indicate:Firstly,most of the groundwater samples are characterized by Mg-HCO_(3) and Na-HCO_(3) with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471-2337 mg/L.The NO_(3)^(−)concentration in 38.89%groundwater samples and the F^(−)concentration in 66.67%groundwater samples exceed the permissible limited value.Secondly,F^(−)in groundwater originates predominantly from water-rock interactions and the fluorite dissolution,which is also regulated by cation exchange,competitive adsorption of HCO_(3)−and an alkaline environment.Thirdly,the effect of sewage disposal and agricultural activities have a significant effect on high NO3-concentration,while the high F^(−)concentration is less influenced by anthropogenic activity.The alkaline environment favors nitrification,thus being conducive to the production of NO_(3)^(−).Finally,the health risk assessment is evaluated for different population groups.The results indicate that high NO_(3)^(−)and F^(−)concentration in groundwater would have the largest threat to children’s health.The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.
基金Clinical Medicine Science and Technology Development Fund of Jiangsu University 2021(Natural Science Category)(Grant No.JLY2021004)。
文摘Objective:To investigate the therapeutic effects and mechanisms of human mesenchymal stem cell-derived exosomes(hMSCs-Exo)carrying the NGF gene in treating ischemic stroke in rats,aiming to provide new insights and treatment methods for ischemic stroke therapy.Methods:After successful construction of the cerebral ischemia model in 40 male SPF-grade SD rats aged 6-8 weeks,the model rats were randomly divided into 4 groups:Sham group,PBS group,hMSCs-Exo group,and NGF-hMSCs-Exo group,with 10 rats in each group.The rat MCAO model was prepared using the classic filament method,and NGF-hMSCs-Exo were injected via the tail vein into the MCAO model rats.The expression of the NGF gene in brain ischemic tissues,neuronal regeneration,and rat neurological function recovery were observed using TTC staining,memory function evaluation,Western blot,qRT-PCR,and other methods.Results:Compared with the Sham group,neurological deficits were significant in the PBS group(P<0.01).Compared with the PBS group,neurological scores improved in the hMSCs-Exo group and NGF-hMSCs-Exo group(P<0.05).Compared with the hMSCs-Exo group,the improvement in neurological deficits was more significant in the NGF-hMSCs-Exo group(P<0.05).The infarct area after NGF-hMSCs-Exo intervention was significantly reduced(P<0.05)compared with the Sham group.Compared with the PBS group,relative expression levels of NGF mRNA and protein decreased,while Caspase-3 mRNA and protein expression significantly increased in the PBS group(P<0.01).Compared with the PBS group and hMSCs-Exo group,there were differences in NGF and Caspase-3 mRNA and protein expression in the NGF-hMSCs-Exo group rat brain tissues(P<0.05).Conclusion:Treatment with human mesenchymal stem cell-derived exosomes carrying the NGF gene improves cognitive function and exerts protective effects on SD rats while inhibiting apoptotic levels in cells.
文摘Birds are good friends of humans.They kill a great number of pests.But it seems that humans are not friendly to them.Humans use much pesticide to kill pests.But a lot of birds are killed at the same time.Sometimes,humans directly kill birds.Some people kill birds for food,money or even fun.So the number of birds has become smaller and smaller.
文摘Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the nucleosome,generated using cryoelectron microscopy(cryo-EM),cross-linking mass spectrometry,and homology modeling.
文摘Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture.Here,we present a structural model of the endogenously purified human canonical BAF complex bound to the nucleosome,generated using cryoelectron microscopy(cryo-EM),cross-linking mass spectrometry,and homology modeling.BAF complexes bilaterally engage the nucleosome H2A/H2B acidic patch regions through the SMARCB1 C-terminalα-helix and the SMARCA4/2 C-terminal SnAc/postSnAc regions,with disease-associated mutations in either causing attenuated chromatin remodeling activities.Further,we define changes in BAF complex architecture upon nucleosome engagement and compare the structural model of endogenous BAF to those of related SWI/SNF-family complexes.Finally,we assign and experimentally interrogate cancer-associated hot-spot mutations localizing within the endogenous human BAF complex,identifying those that disrupt BAF subunit-subunit and subunit-nucleosome interfaces in the nucleosome-bound conformation.Taken together,this integrative structural approach provides important biophysical foundations for understanding the mechanisms of BAF complex function in normal and disease states.
基金supported by the National Natural Science Foundation of China(Grant No.U2243203),the Fundamental Research Funds for the Central Universities(Grants No.B200204029 and B220201011),and the Natural Science Foundation of Jiangsu Province(Grant No.BK20210368).
文摘Significant changes in water cycle elements/processes have created serious challenges to regional sustainability and high-quality development in the Yellow River Basin in China.It is necessary to investigate the impacts of climate change and human activities on hydrological evolution and disaster risk from a holistic perspective of the basin.This study developed initiatives to clarify the mechanisms of hydrological evolution in the human-influenced Yellow River Basin.The proposed research method includes:(1)a tool to simulate multiple factors and a multi-scale water cycle using a grid-based spatiotemporal coupling approach,and(2)a new algorithm to separate the responses of the water cycle to climate change and human impacts,and de-couple the eco-environmental effects using artificial intelligence techniques.With this research framework,key breakthroughs are expected to be made in the understanding of the impacts of land cover change on the water cycle and blue/green water redirection.The outcomes of this research project are expected to provide theoretical support for ecological protection and water governance in the basin.
文摘BACKGROUND Globally,complete neurological recovery of spinal cord injury(SCI)is still less than 1%,and 90%experience permanent disability.The key issue is that a pharmacological neuroprotective-neuroregenerative agent and SCI regeneration mechanism have not been found.The secretomes of stem cell are an emerging neurotrophic agent,but the effect of human neural stem cells(HNSCs)secretome on SCI is still unclear.AIM To investigate the regeneration mechanism of SCI and neuroprotective-neuroregenerative effects of HNSCs-secretome on subacute SCI post-laminectomy in rats.METHODS An experimental study was conducted with 45 Rattus norvegicus,divided into 15 normal,15 control(10 mL physiologic saline),and 15 treatment(30μL HNSCssecretome,intrathecal T10,three days post-traumatic).Locomotor function was evaluated weekly by blinded evaluators.Fifty-six days post-injury,specimens were collected,and spinal cord lesion,free radical oxidative stress(F2-Isoprostanes),nuclear factor-kappa B(NF-κB),matrix metallopeptidase 9(MMP9),tumor necrosis factor-alpha(TNF-α),interleukin-10(IL-10),transforming growth factor-beta(TGF-β),vascular endothelial growth factor(VEGF),B cell lymphoma-2(Bcl-2),nestin,brain-derived neurotrophic factor(BDNF),glial cell line-derived neurotrophic factor(GDNF)were analyzed.The SCI regeneration mechanism was analyzed using partial least squares structural equation modeling(PLS SEM).RESULTS HNSCs-secretome significantly improved locomotor recovery according to Basso,Beattie,Bresnahan(BBB)scores and increased neurogenesis(nestin,BDNF,and GDNF),neuroangiogenesis(VEGF),anti-apoptotic(Bcl-2),anti-inflammatory(IL-10 and TGF-β),but decreased proinflammatory(NF-κB,MMP9,TNF-α),F2-Isoprostanes,and spinal cord lesion size.The SCI regeneration mechanism is valid by analyzed outer model,inner model,and hypothesis testing in PLS SEM,started with pro-inflammation followed by anti-inflammation,anti-apoptotic,neuroangiogenesis,neurogenesis,and locomotor function.CONCLUSION HNSCs-secretome as a potential neuroprotective-neuroregenerative agent for the treatment of SCI and uncover the SCI regeneration mechanism.
基金the Natural Science Foundation of Shandong Province of China,No.ZR2021QH179 and ZR2020MH014.
文摘BACKGROUND Ferroptosis can induce low retention and engraftment after mesenchymal stem cell(MSC)delivery,which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension(PAH)therapy.Interestingly,the cystathionineγ-lyase(CSE)/hydrogen sulfide(H_(2)S)pathway may contribute to mediating ferroptosis.However,the influence of the CSE/H_(2)S pathway on ferroptosis in human umbilical cord MSCs(HUCMSCs)remains unclear.AIM To clarify whether the effect of HUCMSCs on vascular remodelling in PAH mice is affected by CSE/H_(2)S pathway-mediated ferroptosis,and to investigate the functions of the CSE/H_(2)S pathway in ferroptosis in HUCMSCs and the underlying mechanisms.METHODS Erastin and ferrostatin-1(Fer-1)were used to induce and inhibit ferroptosis,respectively.HUCMSCs were transfected with a vector to overexpress or inhibit expression of CSE.A PAH mouse model was established using 4-wk-old male BALB/c nude mice under hypoxic conditions,and pulmonary pressure and vascular remodelling were measured.The survival of HUCMSCs after delivery was observed by in vivo bioluminescence imaging.Cell viability,iron accumulation,reactive oxygen species production,cystine uptake,and lipid peroxidation in HUCMSCs were tested.Ferroptosis-related proteins and S-sulfhydrated Kelchlike ECH-associating protein 1(Keap1)were detected by western blot analysis.RESULTS In vivo,CSE overexpression improved cell survival after erastin-treated HUCMSC delivery in mice with hypoxiainduced PAH.In vitro,CSE overexpression improved H_(2)S production and ferroptosis-related indexes,such as cell viability,iron level,reactive oxygen species production,cystine uptake,lipid peroxidation,mitochondrial membrane density,and ferroptosis-related protein expression,in erastin-treated HUCMSCs.In contrast,in vivo,CSE inhibition decreased cell survival after Fer-1-treated HUCMSC delivery and aggravated vascular remodelling in PAH mice.In vitro,CSE inhibition decreased H_(2)S levels and restored ferroptosis in Fer-1-treated HUCMSCs.Interestingly,upregulation of the CSE/H_(2)S pathway induced Keap1 S-sulfhydration,which contributed to the inhibition of ferroptosis.CONCLUSION Regulation of the CSE/H_(2)S pathway in HUCMSCs contributes to the inhibition of ferroptosis and improves the suppressive effect on vascular remodelling in mice with hypoxia-induced PAH.Moreover,the protective effect of the CSE/H_(2)S pathway against ferroptosis in HUCMSCs is mediated via S-sulfhydrated Keap1/nuclear factor erythroid 2-related factor 2 signalling.The present study may provide a novel therapeutic avenue for improving the protective capacity of transplanted MSCs in PAH.
基金the financial support from the National Natural Science Foundation of China(No.52109119)the Guangxi Natural Science Foundation(No.2021GXNSFBA075030)+2 种基金the Guangxi Science and Technology Project(No.Guike AD20325002)the Chinese Postdoctoral Science Fund Project(No.2022 M723408)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)(No.IWHR-SKL-202202).
文摘Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.
基金Supported by Tianjin Municipal Natural Science Foundation of China(Grant No.19JCJQJC61600)Hebei Provincial Natural Science Foundation of China(Grant Nos.F2020202051,F2020202053).
文摘Visual odometry is critical in visual simultaneous localization and mapping for robot navigation.However,the pose estimation performance of most current visual odometry algorithms degrades in scenes with unevenly distributed features because dense features occupy excessive weight.Herein,a new human visual attention mechanism for point-and-line stereo visual odometry,which is called point-line-weight-mechanism visual odometry(PLWM-VO),is proposed to describe scene features in a global and balanced manner.A weight-adaptive model based on region partition and region growth is generated for the human visual attention mechanism,where sufficient attention is assigned to position-distinctive objects(sparse features in the environment).Furthermore,the sum of absolute differences algorithm is used to improve the accuracy of initialization for line features.Compared with the state-of-the-art method(ORB-VO),PLWM-VO show a 36.79%reduction in the absolute trajectory error on the Kitti and Euroc datasets.Although the time consumption of PLWM-VO is higher than that of ORB-VO,online test results indicate that PLWM-VO satisfies the real-time demand.The proposed algorithm not only significantly promotes the environmental adaptability of visual odometry,but also quantitatively demonstrates the superiority of the human visual attention mechanism.
基金supported by the National Key Research and Development Program of China,Nos.2017YFE0122900(to BH),2019YFA0110800(to WL),2019YFA0903802(to YW),2021YFA1101604(to LW),2018YFA0108502(to LF),and 2020YFA0804003(to JW)the National Natural Science Foundation of China,Nos.31621004(to WL,BH)and 31970821(to YW)+1 种基金CAS Project for Young Scientists in Basic Research,No.YSBR-041(to YW)Joint Funds of the National Natural Science Foundation of China,No.U21A20396(to BH)。
文摘Numerous studies have shown that cell replacement therapy can replenish lost cells and rebuild neural circuitry in animal models of Parkinson’s disease.Transplantation of midbrain dopaminergic progenitor cells is a promising treatment for Parkinson’s disease.However,transplanted cells can be injured by mechanical damage during handling and by changes in the transplantation niche.Here,we developed a one-step biomanufacturing platform that uses small-aperture gelatin microcarriers to produce beads carrying midbrain dopaminergic progenitor cells.These beads allow midbrain dopaminergic progenitor cell differentiation and cryopreservation without digestion,effectively maintaining axonal integrity in vitro.Importantly,midbrain dopaminergic progenitor cell bead grafts showed increased survival and only mild immunoreactivity in vivo compared with suspended midbrain dopaminergic progenitor cell grafts.Overall,our findings show that these midbrain dopaminergic progenitor cell beads enhance the effectiveness of neuronal cell transplantation.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22A20234 and 42277170)Hubei Province Key Research and Development Project(Grant No.2023BCB121).
文摘Surrounding rocks of underground engineering are subjected to long-term seepage pressure,which can deteriorate the mechanical properties and cause serious disasters.In order to understand the impact of seepage pressure on the mechanical property of sandstone,uniaxial compression tests,P-wave velocity measurements,and nuclear magnetic resonance(NMR)tests were conducted on saturated sandstone samples with varied seepage pressures(i.e.0 MPa,3 MPa,4 MPa,5 MPa,6 MPa,7 MPa).The results demonstrate that the mechanical parameters(uniaxial compressive strength,peak strain,elastic modulus,and brittleness index),total energy,elastic strain energy,as well as elastic strain energy ratio,decrease with increasing seepage pressure,while the dissipation energy and dissipation energy ratio increase.Moreover,as seepage pressure increases,the micro-pores gradually transform into meso-pores and macro-pores.This increases the cumulative porosity of sandstone and decreases P-wave velocity.The numerical results indicate that as seepage pressure rises,the number of tensile cracks increases progressively,the angle range of microcracks is basically from 50-120to 80-100,and as a result,the failure mode transforms to the tensile-shear mixed failure mode.Finally,the effects of seepage pressure on mechanical properties were discussed.The results show that decrease in the effective stress and cohesion under the action of seepage pressure could lead to deterioration of strength behaviors of sandstone.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(52103090)the Natural Science Foundation of Guangdong Province(2022A1515011780)Autonomous deployment project of China National Key Laboratory of Materials for Integrated Circuits(NKLJC-Z2023-B03).
文摘The remarkable properties of carbon nanotubes(CNTs)have led to promising applications in the field of electromagnetic inter-ference(EMI)shielding.However,for macroscopic CNT assemblies,such as CNT film,achieving high electrical and mechanical properties remains challenging,which heavily depends on the tube-tube interac-tions of CNTs.Herein,we develop a novel strategy based on metal-organic decomposition(MOD)to fabricate a flexible silver-carbon nanotube(Ag-CNT)film.The Ag particles are introduced in situ into the CNT film through annealing of MOD,leading to enhanced tube-tube interactions.As a result,the electrical conductivity of Ag-CNT film is up to 6.82×10^(5) S m^(-1),and the EMI shielding effectiveness of Ag-CNT film with a thickness of~7.8μm exceeds 66 dB in the ultra-broad frequency range(3-40 GHz).The tensile strength and Young’s modulus of Ag-CNT film increase from 30.09±3.14 to 76.06±6.20 MPa(~253%)and from 1.12±0.33 to 8.90±0.97 GPa(~795%),respectively.Moreover,the Ag-CNT film exhibits excellent near-field shield-ing performance,which can effectively block wireless transmission.This innovative approach provides an effective route to further apply macroscopic CNT assemblies to future portable and wearable electronic devices.
基金National Natural Science Foundation of China(No.52178393)2023 High-level Talent Research Project from Yancheng Institute of Technology(No.xjr2023019)+1 种基金Open Fund Project of Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering(Grant No.YT202302)Science and Technology Innovation Team of Shaanxi Innovation Capability Support Plan(No.2020TD005).
文摘The deformation in sedimentary rock induced by train loads has potential threat to the safe operation of tunnels. This study investigated the influence of stratification structure on the infrared radiation and temporal damage mechanism of hard siltstone. The uniaxial compression tests, coupled with acoustic emission(AE) and infrared radiation temperature(IRT) were conducted on siltstones with different stratification effects. The results revealed that the stratigraphic structure significantly affects the stress-strain response and strength degradation characteristics. The mechanical parameters exhibit anisotropy characteristics, and the stratification effect exhibits a negative correlation with the cracking stress and peak stress. The failure modes caused by the stratification effect show remarkable anisotropic features, including splitting failure(Ⅰ: 0°-22.50°, Ⅱ: 90°), composite failure(45°), and shearing failure(67.50°). The AE temporal sequences demonstrate a stepwise response characteristic to the loading stress level. The AE intensity indicates that the stress sensitivity of shearing failure and composite failure is generally greater than that of splitting failure. The IRT field has spatiotemporal migration and progressive dissimilation with stress loading and its dissimilation degree increases under higher stress levels. The stronger the stratification effect, the greater the dissimilation degree of the IRT field. The abnormal characteristic points of average infrared radiation temperature(AIRT) variance at local stress drop and peak stress can be used as early and late precursors to identify fracture instability. Theoretical analysis shows that the competitive relationship between compaction strengthening and fracturing damage intensifies the dissimilation of the infrared thermal field for an increasing stress level. The present study provides a theoretical reference for disaster warnings in hard sedimentary rock mass.
基金supported by the Natural Science Foundation of Beijing,China(7214223,7212027)the Beijing Hospitals Authority Youth Programme(QML20210601)+3 种基金the Chinese Scholarship Council(CSC)scholarship(201706210415)the National Key Research and Development Program of China(2017YFC0908800)the Beijing Municipal Health Commission(PXM2020_026272_000002,PXM2020_026272_000014)the National Natural Science Foundation of China(82070293).
文摘Heart injury such as myocardial infarction leads to cardiomyocyte loss,fibrotic tissue deposition,and scar formation.These changes reduce cardiac contractility,resulting in heart failure,which causes a huge public health burden.Military personnel,compared with civilians,is exposed to more stress,a risk factor for heart diseases,making cardiovascular health management and treatment innovation an important topic for military medicine.So far,medical intervention can slow down cardiovascular disease progression,but not yet induce heart regeneration.In the past decades,studies have focused on mechanisms underlying the regenerative capability of the heart and applicable approaches to reverse heart injury.Insights have emerged from studies in animal models and early clinical trials.Clinical interventions show the potential to reduce scar formation and enhance cardiomyocyte proliferation that counteracts the pathogenesis of heart disease.In this review,we discuss the signaling events controlling the regeneration of heart tissue and summarize current therapeutic approaches to promote heart regeneration after injury.
基金supported by the National Natural Science Foundation of China(Nos.51974082,51901037)State Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization(No.2021H2279)Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project 2.0 of China,No.BP0719037).
文摘In this study,the extruded Mg-Zn-Mn-Ce-Ca alloy tube with a low compression anisotropy along the ED,45ED and TD was prepared.The effect of the second phases,initial texture and deformation behavior on this low mechanical anisotropy was investigated.The results revealed that the alloy tube contains the high content(Mg1-xZnx)11Ce phase and the low content of Mg12Ce phase.These second phases are respectively incoherent and coherent with the Mg matrix,and their influence can be ignored.Additionally,the alloy tube exhibited a weak basal fiber texture,where the c-axis was aligned along the 0°∼30°tilt from TD to ED.Such a texture made the initial deformation(at 1.0%∼1.6%strain)of the three samples controlled by comparable basalslip.As deformation progressed(1.6∼9.0%strain),larger amounts of ETWs nucleated and gradually approached saturation in the three samples,re-orienting the c-axis to a 0°∼±30°deviation with respect to the loading directions.Meanwhile,the prismatic and pyramidal<c+a>slips replaced the dominant deformation progressively until fracture.Eventually,the similar deformation mechanisms determined by the weak initial texture in the three samples contribute to the comparable strain hardening rates,resulting in the low compressive anisotropy of the alloy tube.