Cardiac injury initiates repair mechanisms and results in cardiac remodeling and fi-brosis,which appears to be a leading cause of cardiovascular diseases.Cardiac fi-brosis is characterized by the accumulation of extra...Cardiac injury initiates repair mechanisms and results in cardiac remodeling and fi-brosis,which appears to be a leading cause of cardiovascular diseases.Cardiac fi-brosis is characterized by the accumulation of extracellular matrix proteins,mainly collagen in the cardiac interstitium.Many experimental studies have demonstrated that fibrotic injury in the heart is reversible;therefore,it is vital to understand differ-ent molecular mechanisms that are involved in the initiation,progression,and resolu-tion of cardiac fibrosis to enable the development of antifibrotic agents.Of the many experimental models,one of the recent models that has gained renewed interest is isoproterenol(ISP)-induced cardiac fibrosis.ISP is a synthetic catecholamine,sympa-thomimetic,and nonselectiveβ-adrenergic receptor agonist.The overstimulated and sustained activation ofβ-adrenergic receptors has been reported to induce biochemi-cal and physiological alterations and ultimately result in cardiac remodeling.ISP has been used for decades to induce acute myocardial infarction.However,the use of low doses and chronic administration of ISP have been shown to induce cardiac fibrosis;this practice has increased in recent years.Intraperitoneal or subcutaneous ISP has been widely used in preclinical studies to induce cardiac remodeling manifested by fibrosis and hypertrophy.The induced oxidative stress with subsequent perturbations in cellular signaling cascades through triggering the release of free radicals is consid-ered the initiating mechanism of myocardial fibrosis.ISP is consistently used to induce fibrosis in laboratory animals and in cardiomyocytes isolated from animals.In recent years,numerous phytochemicals and synthetic molecules have been evaluated in ISP-induced cardiac fibrosis.The present review exclusively provides a comprehensive summary of the pathological biochemical,histological,and molecular mechanisms of ISP in inducing cardiac fibrosis and hypertrophy.It also summarizes the application of this experimental model in the therapeutic evaluation of natural as well as syn-thetic compounds to demonstrate their potential in mitigating myocardial fibrosis and hypertrophy.展开更多
Neuromyelitis optica spectrum disorders are neuroinflammatory demyelinating disorders that lead to permanent visual loss and motor dysfunction.To date,no effective treatment exists as the exact causative mechanism rem...Neuromyelitis optica spectrum disorders are neuroinflammatory demyelinating disorders that lead to permanent visual loss and motor dysfunction.To date,no effective treatment exists as the exact causative mechanism remains unknown.Therefore,experimental models of neuromyelitis optica spectrum disorders are essential for exploring its pathogenesis and in screening for therapeutic targets.Since most patients with neuromyelitis optica spectrum disorders are seropositive for IgG autoantibodies against aquaporin-4,which is highly expressed on the membrane of astrocyte endfeet,most current experimental models are based on aquaporin-4-IgG that initially targets astrocytes.These experimental models have successfully simulated many pathological features of neuromyelitis optica spectrum disorders,such as aquaporin-4 loss,astrocytopathy,granulocyte and macrophage infiltration,complement activation,demyelination,and neuronal loss;however,they do not fully capture the pathological process of human neuromyelitis optica spectrum disorders.In this review,we summarize the currently known pathogenic mechanisms and the development of associated experimental models in vitro,ex vivo,and in vivo for neuromyelitis optica spectrum disorders,suggest potential pathogenic mechanisms for further investigation,and provide guidance on experimental model choices.In addition,this review summarizes the latest information on pathologies and therapies for neuromyelitis optica spectrum disorders based on experimental models of aquaporin-4-IgG-seropositive neuromyelitis optica spectrum disorders,offering further therapeutic targets and a theoretical basis for clinical trials.展开更多
With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rock...With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rockbursts.To investigate the influence of tunnel diameter on the deformation and failure characteristics of surrounding rock,large-sized rocklike gypsum specimens were tested using a selfdeveloped true triaxial rockburst loading system containing circular tunnels with three different diameters(D=0.07 m,0.11 m,and 0.15 m).Acoustic emission monitoring,together with a miniature intelligent camera,was employed to analyze the entire process,focusing on macroscopic failure patterns,fragment characteristics,and underlying failure mechanisms.In addition,theoretical analyses were carried out and combined with numerical simulations to investigate the differences in energy evolution associated with rockburst physical models.The results indicate that:(1)The rockburst process with different tunnel diameters consistently evolved through three distinct stages—initial particle ejection,crack propagation accompanied by flake spalling,and,finally,fragment ejection leading to the formation of a‘V'-shaped notch.(2)Increasing tunnel diameter reduces rockburst failure load while increasing surrounding rock damage extent,total mass and average size of ejected fragments.Additionally,shear failure proportion decreases with tensile failure becoming increasingly dominant.(3)Larger tunnel diameters reduce the attenuation rate of elastic strain energy,thereby expanding the zone of elastic strain energy accumulation and disturbance and creating conditions for larger volume rockburst.(4)Larger tunnel diameters result in a smaller principal stress ratio at equivalent distances in the surrounding rock,indicating a higher likelihood of tensile failure.(5)Numerical analyses further reveal that larger tunnel diameters reduce the maximum elastic strain energy density around the tunnel,lowering the energy released per unit volume of rockburst fragments and their ejection velocities.However,both the total failure volume and overall energy release from rockburst increase.Model experiments with different tunnel diameters are of great significance for optimizing engineering design and parameter selection,as well as guiding tunnel construction under complex geological conditions.展开更多
This article aims tomodel and analyze the heat and fluid flow characteristics of a carboxymethyl cellulose(CMC)nanofluid within a convergent-divergent shaped microchannel(Two-dimensional).The base fluid,water+CMC(0.5%...This article aims tomodel and analyze the heat and fluid flow characteristics of a carboxymethyl cellulose(CMC)nanofluid within a convergent-divergent shaped microchannel(Two-dimensional).The base fluid,water+CMC(0.5%),is mixed with CuO and Al2O3 nanoparticles at volume fractions of 0.5%and 1.5%,respectively.The research is conducted through the conjugate usage of experimental and theoretical models to represent more realistic properties of the non-Newtonian nanofluid.Three types of microchannels including straight,divergent,and convergent are considered,all having the same length and identical inlet cross-sectional area.Using ANSYS FLUENT software,Navier-Stokes equations are solved for the laminar flow of the non-Newtonian nanofluid.The study examines the effects of Reynolds number,nanoparticle concentration and type,and microchannel geometry on flow and heat transfer.The results prove that the alumina nanoparticles outperform copper oxide in increasing the Nusselt number at a 0.5% volume fraction,while copper oxide nanoparticles excel at a 1.5%volume fraction.Moreover,in the selected case study,as the Reynolds number increases from 100 to 500,the Nusselt number rises by 56.26% in straight geometry,52.93% in divergent geometry,and 59.10%in convergent geometry.Besides,the Nusselt number enhances by 18.75% when transitioning from straight to convergent geometry at a Reynolds number of 500,and by 19.81%at a Reynolds number of 1000.Finally,the results of the research depict that the use of thermophysical properties derived from the experimental achievements,despite creating complexity in the modeling and the solution method,leads to more accurate and realistic outputs.展开更多
Background:Refined models of kidney disease are critical to better understand disease processes and study novel treatments while minimizing discomfort in research animals.The objective of this study was to report a te...Background:Refined models of kidney disease are critical to better understand disease processes and study novel treatments while minimizing discomfort in research animals.The objective of this study was to report a technique for minimally invasive partial kidney embolism in cats and describe outcomes following transcatheter administration of embolic microspheres with subsequent contralateral nephrectomy.Methods:Eleven,apparently healthy,male,purpose-bred cats underwent unilateral kidney embolism with 0.25 or 0.5 mL of embolic microparticle(40-120μm)suspension(0.2 mL microspheres/mL)delivered into the right renal artery under fluoroscopic guidance,followed 5 months later by contralateral nephrectomy.One month after nephrectomy,blood and urinary markers of kidney function were evaluated,and embolized kidneys were harvested for histopathology evaluation.Results:Renal artery embolization was possible in all cats.Two cats did not complete the study,one after experiencing congestive heart failure(n=1)and the other following evidence of complete kidney embolism precluding nephrectomy(n=1)postembolization.At study end,compared to baseline,cats had significant increases in median(range)serum creatinine(159.1μmol/L[141.4-530.4]versus 128.2μmol/L[92.8-150.3];p=0.0004),urea nitrogen(15.71 mmol/L[9.29-47.85]versus 7.50 mmol/L[6.07-8.57];p<0.0001),and symmetric dimethylarginine(0.74μmol/L[0.59-3.12]versus 0.67μmol/L[0.54-0.72];p=0.0288)concentrations.No differences in markers of kidney function were documented between dose groups.Conclusions:M inimally invasive kidney embolism is a promising technique for modeling kidney disease in cats.Understanding optimal dose,timing of nephrectomy,and longer-term consequences requires additional work.展开更多
BACKGROUND Acute pancreatitis(AP)encompasses a spectrum of pancreatic inflammatory conditions,ranging from mild inflammation to severe pancreatic necrosis and multisystem organ failure.Given the challenges associated ...BACKGROUND Acute pancreatitis(AP)encompasses a spectrum of pancreatic inflammatory conditions,ranging from mild inflammation to severe pancreatic necrosis and multisystem organ failure.Given the challenges associated with obtaining human pancreatic samples,research on AP predominantly relies on animal models.In this study,we aimed to elucidate the fundamental molecular mechanisms underlying AP using various AP models.AIM To investigate the shared molecular changes underlying the development of AP across varying severity levels.METHODS AP was induced in animal models through treatment with caerulein alone or in combination with lipopolysaccharide(LPS).Additionally,using Ptf1αto drive the specific expression of the hM3 promoter in pancreatic acinar cells transgenic C57BL/6J-hM3/Ptf1α(cre)mice were administered Clozapine N-oxide to induce AP.Subsequently,we conducted RNA sequencing of pancreatic tissues and validated the expression of significantly different genes using the Gene Expression Omnibus(GEO)database.RESULTS Caerulein-induced AP showed severe inflammation and edema,which were exacerbated when combined with LPS and accompanied by partial pancreatic tissue necrosis.Compared with the control group,RNA sequencing analysis revealed 880 significantly differentially expressed genes in the caerulein model and 885 in the caerulein combined with the LPS model.Kyoto Encyclopedia of Genes and Genomes enrichment analysis and Gene Set Enrichment Analysis indicated substantial enrichment of the TLR and NOD-like receptor signaling pathway,TLR signaling pathway,and NF-κB signaling pathway,alongside elevated levels of apoptosis-related pathways,such as apoptosis,P53 pathway,and phagosome pathway.The significantly elevated genes in the TLR and NOD-like receptor signaling pathways,as well as in the apoptosis pathway,were validated through quantitative real-time PCR experiments in animal models.Validation from the GEO database revealed that only MYD88 concurred in both mouse pancreatic tissue and human AP peripheral blood,while TLR1,TLR7,RIPK3,and OAS2 genes exhibited marked elevation in human AP.The genes TUBA1A and GADD45A played significant roles in apoptosis within human AP.The transgenic mouse model hM3/Ptf1α(cre)successfully validated significant differential genes in the TLR and NOD-like receptor signaling pathways as well as the apoptosis pathway,indicating that these pathways represent shared pathological processes in AP across different models.CONCLUSION The TLR and NOD receptor signaling pathways play crucial roles in the inflammatory progression of AP,notably the MYD88 gene.Apoptosis holds a central position in the necrotic processes of AP,with TUBA1A and GADD45A genes exhibiting prominence in human AP.展开更多
To ensure the long-term and sustainable development and utilization of geothermal resources,the extracted geothermal water should be reinjected.Considering Guantao Formation in the Dezhou Area,the geothermal reinjecti...To ensure the long-term and sustainable development and utilization of geothermal resources,the extracted geothermal water should be reinjected.Considering Guantao Formation in the Dezhou Area,the geothermal reinjection process is analyzed through experimental and numerical modeling.Numerical analysis suggests that the reinjectionflow only has a strong influence on the reservoir pressure over a relatively narrow range,whereas the range over which this process has a weak influence exceeds 500 m.Assuming that the reinjection well is full,a reinjectionflow rate of 50-100 m^(3)/h can theoretically be achieved without additional pressure.Experimental modeling of geothermal exploitation and reinjection suggests that sandstone reservoirs with good porosity and permeability should be selected to lower the reinjection pressure of geothermal reservoir projects.In real geothermal reinjection processes,the reinjectionflow rate should be carefully determined to prevent excessive pressure in sandstone reservoirs and ensure long-term stable and efficient reinjection.The Huaneng Geothermal Project has been operating for 2 years,and there has been no significant change in the outlet temperature and reinjection pressure of the geothermal wells.This is generally consistent with the modeling results,demonstrating the accuracy of the exploitation and reinjection modeling analysis.An efficient reinjection scheme for sandstone geothermal reservoirs is developed based on the Huaneng Dezhou Geothermal Heating Project,in which the total reinjection rate is approximately 99.1%.Based on our experimental and numerical modeling,no significant temperature and pressure changes will happen for at least 5 years at the present exploitation and reinjection pressure and amount.展开更多
BACKGROUND Chronic biliary disease,including cholangitis and cholecystitis,is attributed to ascending infection by intestinal bacteria.Development of a mouse model for bile duct inflammation is imperative for the adva...BACKGROUND Chronic biliary disease,including cholangitis and cholecystitis,is attributed to ascending infection by intestinal bacteria.Development of a mouse model for bile duct inflammation is imperative for the advancement of novel therapeutic approaches.Current models fail to replicate the harmful bacterial influx to the biliary tract observed in humans and spread of inflammation to the liver.Therefore,we aimed to establish an animal model of biliary disease that faithfully replicates the mechanisms of human diseases.AIM To establish a cholecystoduodenal anastomosis model capable of mimicking the mechanisms of ascending infection and inflammation observed in human biliary diseases.METHODS We established a mouse biliary disease model by directly connecting the gallbladder and duodenum,enabling ascending infection into the biliary tract without traversing the sphincter of Oddi.RESULTS In the cholecystoduodenal anastomosis mouse model,we observed impaired epithelial structure,wall thickening,and macrophage recruitment in the gallbladder.Despite the absence of postoperative antibiotics,we detected no changes in serum proinflammatory cytokine levels,indicating no systemic inflammation.Moreover,patency between the gallbladder and duodenum was confirmed via common bile duct ligation.Injection of patient-derived pathogenic bacteria into bile duct-ligated mice led to ascending infection,which significantly increased proinflammatory cytokine mRNA expression in the liver,duodenum,and ileum.These results indicate that our mouse model exhibited a direct connection between the gallbladder and duodenum,leading to ascending infection and closely mimicking the clinical features of biliary diseases observed in humans.CONCLUSION The cholecystoduodenal anastomosis mouse model is an effective chronic biliary disease model with significant relevance in the development of microbiome-based therapies for the prevention and treatment of biliary disease.展开更多
BACKGROUND Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity,that negatively affect the patients’quality of life.Experimental studies play an imp...BACKGROUND Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity,that negatively affect the patients’quality of life.Experimental studies play an important role in understanding the pathophysiological background of anastomotic healing and there are still many fields that require further investigation.Knowledge drawn from these studies can lead to interventions or techniques that can reduce the risk of anastomotic leak in patients with high-risk features.Despite the advances in experimental protocols and techniques,designing a high-quality study is still challenging for the investigators as there is a plethora of different models used.AIM To review current state of the art for experimental protocols in high-risk anastomosis in rats.METHODS This systematic review was performed according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.To identify eligible studies,a comprehensive literature search was performed in the electronic databases PubMed(MEDLINE)and Scopus,covering the period from conception until 18 October 2023.RESULTS From our search strategy 102 studies were included and were categorized based on the mechanism used to create a high-risk anastomosis.Methods of assessing anastomotic healing were extracted and were individually appraised.CONCLUSION Anastomotic healing studies have evolved over the last decades,but the findings are yet to be translated into human studies.There is a need for high-quality,well-designed studies that will help to the better understanding of the pathophysiology of anastomotic healing and the effects of various interventions.展开更多
Breast cancer metastasis is a major cause of treatment failure and patient mortality. Mouse tumor models largely replicate the pathophysiological processes of human tumors. Establishing mouse models of breast cancer m...Breast cancer metastasis is a major cause of treatment failure and patient mortality. Mouse tumor models largely replicate the pathophysiological processes of human tumors. Establishing mouse models of breast cancer metastasis helps to elucidate metastatic mechanisms, and in vivo imaging techniques enable dynamic monitoring of tumor cell metastasis in animals. This paper summarizes the mechanisms of breast cancer metastasis, the development, and application of various mouse breast cancer distant metastasis models over the past decade, and evaluates the characteristics and efficacy of each model to provide references for future experimental studies.展开更多
The high temperature split Hopkinson pressure bar （SHPB） compression experiment is conducted to obtain the data relationship among strain, strain rate and flow stress from room temperature to 550 C for aeronautical ...The high temperature split Hopkinson pressure bar （SHPB） compression experiment is conducted to obtain the data relationship among strain, strain rate and flow stress from room temperature to 550 C for aeronautical aluminum alloy 7050-T7451. Combined high-speed orthogonal cutting experiments with the cutting process simulations, the data relationship of high temperature, high strain rate and large strain in high-speed cutting is modified. The Johnson-Cook empirical model considering the effects of strain hardening, strain rate hardening and thermal softening is selected to describe the data relationship in high-speed cutting, and the material constants of flow stress constitutive model for aluminum alloy 7050-T7451 are determined. Finally, the constitutive model of aluminum alloy 7050-T7451 is established through experiment and simulation verification in high-speed cutting. The model is proved to be reasonable by matching the measured values of the cutting force with the estimated results from FEM simulations.展开更多
In order to check the validity of the mathematical model for analyzing the flow field in the air-agitated seed precipitation tank,a scaled down experimental apparatus was designed and the colored tracer and KCl tracer...In order to check the validity of the mathematical model for analyzing the flow field in the air-agitated seed precipitation tank,a scaled down experimental apparatus was designed and the colored tracer and KCl tracer were added in the apparatus to follow the real flow line.Virtue tracers were considered in the mathematical model and the algorithm of tracers was built.The comparison of the results between the experiment and numerical calculation shows that the time of the tracer flows out of stirring tube are 40 s in the experiment and 42 s in numerical calculated result.The transient diffusion process and the solution residence time of the numerical calculation are in good agreement with the experimental results,which indicates that the mathematical model is reliable and can be used to predict the flow field of the air-agitated seed precipitation tank.展开更多
Beishan Rock Carvings in Chongqing,a renowned cultural heritage site in China,flourished during the Tang and Song dynasties and are often referred to as the“Stone Carving Art Museum of the Tang and Song Dynasties.”C...Beishan Rock Carvings in Chongqing,a renowned cultural heritage site in China,flourished during the Tang and Song dynasties and are often referred to as the“Stone Carving Art Museum of the Tang and Song Dynasties.”Cave 168 is a key component of the Beishan Rock Carvings.At present,several through-going cracks have developed in the roof of Cave 168,severely compromising the structural stability of the grotto.The early internal steel plate supports have suffered severe corrosion and can no longer provide effective reinforcement.In addition,the presence of steel columns obstructs visitor access and negatively affects the viewing experience.A new reinforcement method is urgently needed.Therefore,studying the deformation patterns of the structure is of critical importance.This study analyzes the stratigraphic parameters and fracture distribution of Cave 168,considering key influencing factors such as rainfall,self-weight,and the overlying Quaternary soil.On-site monitoring and physical model experiments were conducted to evaluate the changes in roof crack width and displacement before and after reinforcement with negative Poisson's ratio(NPR)anchor cables.The results reveal that the roof of Cave 168 contains several through-going cracks and numerous microcracks,which serve as infiltration channels for surface water.These accelerate the softening of the mudstone and pose a significant threat to the cave's structural safety.During the experiment,the main change in the crack exhibited a“semi-archshaped”propagation pattern.In the first ten minutes,as the rock transitioned from dry to moist conditions,a slight crack closure was observed.As rainfall continued,crack propagation accelerated.After rainfall ceased,crack width remained stable over a short period.Under NPR anchor support,the influence of rainfall on roof settlement was effectively mitigated,ensuring the safety and stability of the roof.The NPR anchors successfully limited the roof settlement to within 0.3 mm and provided effective control over both total and differential settlement.These findings offer valuable insights into the application of NPR anchor cables in the conservation of grotto heritage structures.展开更多
Objective The present study aimed to establish a cerebral schistosomiasis model in rabbits,to provide a valuable tool for morphological analysis,clinical manifestation observation,as well as investigations into immuno...Objective The present study aimed to establish a cerebral schistosomiasis model in rabbits,to provide a valuable tool for morphological analysis,clinical manifestation observation,as well as investigations into immunological reactions and pathogenesis of focal inflammatory reaction in neuroschistosomiasis（NS）.Methods Sixty New Zealand rabbits were randomly assigned into operation,sham-operation and normal groups.Rabbits in the operation group received direct injection of dead schistosome eggs into the brain,while their counterparts in the sham-operation group received saline injection.Rabbits in the normal group received no treatment.Base on the clinical manifestations,rabbits were sacrificed on days 3,5,7,10,20,and 30 post injection,and brain samples were sectioned and stained with hematoxylin-eosin.Sections were observed under the microscope.Results The rabbits in the operation group exhibited various neurological symptoms,including anorexy,partial and general seizures,and paralysis.The morphological analysis showed several schistosome eggs in the nervous tissue on day 3 post operation,with very mild inflammation.On days 7-10 post operation,several schistosome eggs were localized in proximity to red blood cells with many neutrophilic granulocytes and eosinophilic granulocytes around them.The schistosome eggs developed into the productive granuloma stage on days 14-20 post operation.On day 30,the schistosome eggs were found to be in the healing-by-fibrosis stage,and the granuloma area was replaced by fibrillary glia through astrocytosis.The sham-operation group and the normal group showed negative results.Conclusion This method might be used to establish the cerebral schistosomiasis experimental model.Several factors need to be considered in establishing this model,such as the antigenic property of eggs,the time of scarification,and the clinical manifestations.展开更多
Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections ...Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don＇t support theoretical conclusions. The main experimental conclusions are： 1. Wide angle reflection energies are stronger than non-wide-angle reflections （up to twice as strong） but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the non- wide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than non- wide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor.展开更多
In designing modern vessels, calculating the propulsion performance of ships in ice is important, including propeller effective thrust, number of revolutions, consumed power, and ship speed. Such calculations allow fo...In designing modern vessels, calculating the propulsion performance of ships in ice is important, including propeller effective thrust, number of revolutions, consumed power, and ship speed. Such calculations allow for more accurate prediction of the ice performance of a designed ship and provide inputs for designers of ship power and automation systems. Preliminary calculations of ship propulsion and thrust characteristics in ice can enable predictions of full-scale ice resistance without measuring the propeller thrust during sea trials. Measuring propeller revolutions,ship speed, and the power delivered to propellers could be sufficient to determine the propeller thrust of the vessel. At present, significant difficulties arise in determining the thrust of icebreakers and ice-class ships in ice conditions. These challenges are related to the fact that the traditional system of propeller/hull interaction coefficients does not function correctly in ice conditions. The wake fraction becomes negative and tends to minus infinity starting from a certain value of the propeller advance coefficient. This issue prevents accurate determination of the performance characteristics, thrust, and rotational speed of the propulsors. In this study, an alternative system of propeller/hull interaction coefficients for ice is proposed. It enables the calculation of all propulsion parameters in ice based on standard hydrodynamic tests with selfpropulsion models. An experimental method is developed to determine alternative propeller/hull interaction coefficients. A prediction method is suggested to determine propulsion performance in ice based on the alternative interaction coefficient system. A case study applying the propulsion prediction method for ice conditions is provided. This study also discusses the following issues of ship operation in ice: the scale effect of icebreaker propellers and the prospects for introducing an ice interaction coefficient.展开更多
Plant roots improve the stability of collapsing walls and prevent their collapse;they are thus important for controlling the degree of Benggang erosion in southern China.The vegetation species on the collapsing walls ...Plant roots improve the stability of collapsing walls and prevent their collapse;they are thus important for controlling the degree of Benggang erosion in southern China.The vegetation species on the collapsing walls are diverse,and the interaction of the root systems with soil affects the stability of the collapsing walls.Most recent studies have only examined the effects of single plants.In order to investigate the effects of the roots of different vegetation types on the shear strength of soil in collapsing walls and their interaction mechanisms of action,this study was conducted using the roots of the herb Dicranopteris dichotoma and the shrub Melastoma candidum.A direct shear test of indoor remodeled soil was carried out by varying water content(15%,25%)and herb to shrub root ratio(100:0,75:25,50:50,25:75,and 0:100).The results showed that the shear strength(96.09 kPa)and cohesion(49.26 kPa)of root-containing soil were significantly higher than plain soil(91.77 kPa,42.17 kPa),and the highest values were obtained when herb to shrub root ratio was 100:0(113.27 kPa,62.85 kPa).Here,tensile tests and scanning electron microscopy revealed that the tensile force and tensile strength of the roots of Dicranopteris dichotoma were weaker but effective for maintaining soil stability because of their abundance roots,which could achieve a stronger bond to soil.Simultaneously,herbaceous roots have a small diameter,the Root Area Ratio(RAR)of the roots is larger under the same mass condition,which can better contact with soil and the mechanical properties of roots are fully utilized.Therefore,the soil shear strength is higher and can better resist external damage when herbaceous roots accounts for a larger proportion.The results of this research have implications for the selection and allocation of ecological measures for prevention and control of Benggang.展开更多
The instability and failure of high rock slopes have a significant impact on the safe mining operations.Therefore,revealing the instability mechanism of high rock slopes is of great research significance.This paper ai...The instability and failure of high rock slopes have a significant impact on the safe mining operations.Therefore,revealing the instability mechanism of high rock slopes is of great research significance.This paper aims to reveal the instability mechanism of high rock slopes through physical model tests and numerical simulations.Taking the slope failure on the west side of Pit 1 of Husab Uranium Mine in Namibia in 2021 as the research background,a physical model of the high rock slope of Husab Uranium Mine was established by combining with on-site geological data.The experimental system was monitored by a GoPro camera,a CCD camera,and strain sensors.The damage evolution process of the high rock slope model was analyzed,and numerical simulation verification was carried out using Flac 3D software.Thus,the instability mechanism of the slope failure in this open-pit mine was revealed from multiple perspectives.The results show that the instability mechanism of the high rock slope was determined through the evolution of the displacement field and strain field during the model excavation process,as well as the deformation characteristics of the images at the time of instability and failure.The slope deformation process can be divided into four stages:the initial inter-layer dislocation stage,the crack generation stage,the crack propagation stage,and the crack penetration and failure stage.The results of the model experiment and numerical simulation confirm the consistency between the failure mode of the model slope and the actual slope failure on-site,providing guidance for the prevention and control projects of similar types of mine failures.展开更多
The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in...The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in frozen regions remains underexplored.In seasonally frozen areas,F-T(freeze-thaw)cycles threaten subgrade stability,necessitating research on pile-plate structure’s behavior under such conditions.To address this challenge,a scaled model experiment was conducted on a silty sand foundation,simulating F-T cycles using temperature control devices.Key parameters,including soil temperature,frozen depth,and displacement,were systematically monitored.Results indicate that the bearing plate functions as an effective insulation layer,significantly reducing sub-zero temperature penetration.Additionally,the anchoring action of the piles mitigates frost heave in the foundation soil,while the plate middle restrains soil deformation more effectively due to increased constraint.The thermal insulation provided by the plate maintains higher soil temperatures,delaying the onset of freezing.By the end of each freezing stage,the vertical displacement in the natural subgrade is approximately 4 times greater than that beneath the pile-plate structure.Furthermore,the frost depth is about 1.3-1.4 times and 1.6-4.9 times greater than that measured below the plate edge and middle,respectively.These insights contribute to the development of more resilient designs for high-speed railway subgrades in seasonally frozen regions,offering engineers a robust,scientifically-backed foundation for future infrastructure projects.展开更多
A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and trans...A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and transient electromagnetic responses occur in the casing,including direct coupling and casing responses.As the range between the transmitting and receiving coils increases,direct coupling responses decay rapidly,are less than the casing response at 0.3 m,and disappear at 0.7 m.By contrast,a casing response increases rapidly and then declines slowly after reaching a peak and changes little within a specifi c range.The peak decreases slowly with range.The continuous addition of water to the tank causes slight changes in transient electromagnetic responses,so the diff erence which are subtracted from the response without water is used.Moreover,the diff erences at the time of rapid increase in response and the time of rapid decrease in response are large,forming a peak and a trough.Given that the conductivity of water in a full tank changes after the addition of salt,the diff erence in the peak is linear with the increase in the conductivity of water.This result provides an experimental basis for the design of a transient electromagnetic logging instrument that measures the conductivity of formation in cased well.展开更多
基金United Arab Emirates University,Grant/Award Number:12R104 and 12R121。
文摘Cardiac injury initiates repair mechanisms and results in cardiac remodeling and fi-brosis,which appears to be a leading cause of cardiovascular diseases.Cardiac fi-brosis is characterized by the accumulation of extracellular matrix proteins,mainly collagen in the cardiac interstitium.Many experimental studies have demonstrated that fibrotic injury in the heart is reversible;therefore,it is vital to understand differ-ent molecular mechanisms that are involved in the initiation,progression,and resolu-tion of cardiac fibrosis to enable the development of antifibrotic agents.Of the many experimental models,one of the recent models that has gained renewed interest is isoproterenol(ISP)-induced cardiac fibrosis.ISP is a synthetic catecholamine,sympa-thomimetic,and nonselectiveβ-adrenergic receptor agonist.The overstimulated and sustained activation ofβ-adrenergic receptors has been reported to induce biochemi-cal and physiological alterations and ultimately result in cardiac remodeling.ISP has been used for decades to induce acute myocardial infarction.However,the use of low doses and chronic administration of ISP have been shown to induce cardiac fibrosis;this practice has increased in recent years.Intraperitoneal or subcutaneous ISP has been widely used in preclinical studies to induce cardiac remodeling manifested by fibrosis and hypertrophy.The induced oxidative stress with subsequent perturbations in cellular signaling cascades through triggering the release of free radicals is consid-ered the initiating mechanism of myocardial fibrosis.ISP is consistently used to induce fibrosis in laboratory animals and in cardiomyocytes isolated from animals.In recent years,numerous phytochemicals and synthetic molecules have been evaluated in ISP-induced cardiac fibrosis.The present review exclusively provides a comprehensive summary of the pathological biochemical,histological,and molecular mechanisms of ISP in inducing cardiac fibrosis and hypertrophy.It also summarizes the application of this experimental model in the therapeutic evaluation of natural as well as syn-thetic compounds to demonstrate their potential in mitigating myocardial fibrosis and hypertrophy.
文摘Neuromyelitis optica spectrum disorders are neuroinflammatory demyelinating disorders that lead to permanent visual loss and motor dysfunction.To date,no effective treatment exists as the exact causative mechanism remains unknown.Therefore,experimental models of neuromyelitis optica spectrum disorders are essential for exploring its pathogenesis and in screening for therapeutic targets.Since most patients with neuromyelitis optica spectrum disorders are seropositive for IgG autoantibodies against aquaporin-4,which is highly expressed on the membrane of astrocyte endfeet,most current experimental models are based on aquaporin-4-IgG that initially targets astrocytes.These experimental models have successfully simulated many pathological features of neuromyelitis optica spectrum disorders,such as aquaporin-4 loss,astrocytopathy,granulocyte and macrophage infiltration,complement activation,demyelination,and neuronal loss;however,they do not fully capture the pathological process of human neuromyelitis optica spectrum disorders.In this review,we summarize the currently known pathogenic mechanisms and the development of associated experimental models in vitro,ex vivo,and in vivo for neuromyelitis optica spectrum disorders,suggest potential pathogenic mechanisms for further investigation,and provide guidance on experimental model choices.In addition,this review summarizes the latest information on pathologies and therapies for neuromyelitis optica spectrum disorders based on experimental models of aquaporin-4-IgG-seropositive neuromyelitis optica spectrum disorders,offering further therapeutic targets and a theoretical basis for clinical trials.
基金funded by the National Natural Science Foundation of China(Nos.42077228,52174085)。
文摘With the increasing development of deepburied engineering projects,rockburst disasters have become a frequent concern.Studies have indicated that tunnel diameter is a critical factor influencing the occurrence of rockbursts.To investigate the influence of tunnel diameter on the deformation and failure characteristics of surrounding rock,large-sized rocklike gypsum specimens were tested using a selfdeveloped true triaxial rockburst loading system containing circular tunnels with three different diameters(D=0.07 m,0.11 m,and 0.15 m).Acoustic emission monitoring,together with a miniature intelligent camera,was employed to analyze the entire process,focusing on macroscopic failure patterns,fragment characteristics,and underlying failure mechanisms.In addition,theoretical analyses were carried out and combined with numerical simulations to investigate the differences in energy evolution associated with rockburst physical models.The results indicate that:(1)The rockburst process with different tunnel diameters consistently evolved through three distinct stages—initial particle ejection,crack propagation accompanied by flake spalling,and,finally,fragment ejection leading to the formation of a‘V'-shaped notch.(2)Increasing tunnel diameter reduces rockburst failure load while increasing surrounding rock damage extent,total mass and average size of ejected fragments.Additionally,shear failure proportion decreases with tensile failure becoming increasingly dominant.(3)Larger tunnel diameters reduce the attenuation rate of elastic strain energy,thereby expanding the zone of elastic strain energy accumulation and disturbance and creating conditions for larger volume rockburst.(4)Larger tunnel diameters result in a smaller principal stress ratio at equivalent distances in the surrounding rock,indicating a higher likelihood of tensile failure.(5)Numerical analyses further reveal that larger tunnel diameters reduce the maximum elastic strain energy density around the tunnel,lowering the energy released per unit volume of rockburst fragments and their ejection velocities.However,both the total failure volume and overall energy release from rockburst increase.Model experiments with different tunnel diameters are of great significance for optimizing engineering design and parameter selection,as well as guiding tunnel construction under complex geological conditions.
文摘This article aims tomodel and analyze the heat and fluid flow characteristics of a carboxymethyl cellulose(CMC)nanofluid within a convergent-divergent shaped microchannel(Two-dimensional).The base fluid,water+CMC(0.5%),is mixed with CuO and Al2O3 nanoparticles at volume fractions of 0.5%and 1.5%,respectively.The research is conducted through the conjugate usage of experimental and theoretical models to represent more realistic properties of the non-Newtonian nanofluid.Three types of microchannels including straight,divergent,and convergent are considered,all having the same length and identical inlet cross-sectional area.Using ANSYS FLUENT software,Navier-Stokes equations are solved for the laminar flow of the non-Newtonian nanofluid.The study examines the effects of Reynolds number,nanoparticle concentration and type,and microchannel geometry on flow and heat transfer.The results prove that the alumina nanoparticles outperform copper oxide in increasing the Nusselt number at a 0.5% volume fraction,while copper oxide nanoparticles excel at a 1.5%volume fraction.Moreover,in the selected case study,as the Reynolds number increases from 100 to 500,the Nusselt number rises by 56.26% in straight geometry,52.93% in divergent geometry,and 59.10%in convergent geometry.Besides,the Nusselt number enhances by 18.75% when transitioning from straight to convergent geometry at a Reynolds number of 500,and by 19.81%at a Reynolds number of 1000.Finally,the results of the research depict that the use of thermophysical properties derived from the experimental achievements,despite creating complexity in the modeling and the solution method,leads to more accurate and realistic outputs.
文摘Background:Refined models of kidney disease are critical to better understand disease processes and study novel treatments while minimizing discomfort in research animals.The objective of this study was to report a technique for minimally invasive partial kidney embolism in cats and describe outcomes following transcatheter administration of embolic microspheres with subsequent contralateral nephrectomy.Methods:Eleven,apparently healthy,male,purpose-bred cats underwent unilateral kidney embolism with 0.25 or 0.5 mL of embolic microparticle(40-120μm)suspension(0.2 mL microspheres/mL)delivered into the right renal artery under fluoroscopic guidance,followed 5 months later by contralateral nephrectomy.One month after nephrectomy,blood and urinary markers of kidney function were evaluated,and embolized kidneys were harvested for histopathology evaluation.Results:Renal artery embolization was possible in all cats.Two cats did not complete the study,one after experiencing congestive heart failure(n=1)and the other following evidence of complete kidney embolism precluding nephrectomy(n=1)postembolization.At study end,compared to baseline,cats had significant increases in median(range)serum creatinine(159.1μmol/L[141.4-530.4]versus 128.2μmol/L[92.8-150.3];p=0.0004),urea nitrogen(15.71 mmol/L[9.29-47.85]versus 7.50 mmol/L[6.07-8.57];p<0.0001),and symmetric dimethylarginine(0.74μmol/L[0.59-3.12]versus 0.67μmol/L[0.54-0.72];p=0.0288)concentrations.No differences in markers of kidney function were documented between dose groups.Conclusions:M inimally invasive kidney embolism is a promising technique for modeling kidney disease in cats.Understanding optimal dose,timing of nephrectomy,and longer-term consequences requires additional work.
基金Supported by National Natural Science Foundation of China,No.82260133 and No.82370661the Academic and Technical Leader of major disciplines in Jiangxi Province,No.20225BCJ23021+2 种基金the Jiangxi Medicine Academy of Nutrition and Health Management,No.2022-PYXM-01the Natural Science Foundation of Jiangxi Province,No.20224ACB216004the Technological Innovation Team Cultivation Project of the First Affiliated Hospital of Nanchang University,No.YFYKCTDPY202202.
文摘BACKGROUND Acute pancreatitis(AP)encompasses a spectrum of pancreatic inflammatory conditions,ranging from mild inflammation to severe pancreatic necrosis and multisystem organ failure.Given the challenges associated with obtaining human pancreatic samples,research on AP predominantly relies on animal models.In this study,we aimed to elucidate the fundamental molecular mechanisms underlying AP using various AP models.AIM To investigate the shared molecular changes underlying the development of AP across varying severity levels.METHODS AP was induced in animal models through treatment with caerulein alone or in combination with lipopolysaccharide(LPS).Additionally,using Ptf1αto drive the specific expression of the hM3 promoter in pancreatic acinar cells transgenic C57BL/6J-hM3/Ptf1α(cre)mice were administered Clozapine N-oxide to induce AP.Subsequently,we conducted RNA sequencing of pancreatic tissues and validated the expression of significantly different genes using the Gene Expression Omnibus(GEO)database.RESULTS Caerulein-induced AP showed severe inflammation and edema,which were exacerbated when combined with LPS and accompanied by partial pancreatic tissue necrosis.Compared with the control group,RNA sequencing analysis revealed 880 significantly differentially expressed genes in the caerulein model and 885 in the caerulein combined with the LPS model.Kyoto Encyclopedia of Genes and Genomes enrichment analysis and Gene Set Enrichment Analysis indicated substantial enrichment of the TLR and NOD-like receptor signaling pathway,TLR signaling pathway,and NF-κB signaling pathway,alongside elevated levels of apoptosis-related pathways,such as apoptosis,P53 pathway,and phagosome pathway.The significantly elevated genes in the TLR and NOD-like receptor signaling pathways,as well as in the apoptosis pathway,were validated through quantitative real-time PCR experiments in animal models.Validation from the GEO database revealed that only MYD88 concurred in both mouse pancreatic tissue and human AP peripheral blood,while TLR1,TLR7,RIPK3,and OAS2 genes exhibited marked elevation in human AP.The genes TUBA1A and GADD45A played significant roles in apoptosis within human AP.The transgenic mouse model hM3/Ptf1α(cre)successfully validated significant differential genes in the TLR and NOD-like receptor signaling pathways as well as the apoptosis pathway,indicating that these pathways represent shared pathological processes in AP across different models.CONCLUSION The TLR and NOD receptor signaling pathways play crucial roles in the inflammatory progression of AP,notably the MYD88 gene.Apoptosis holds a central position in the necrotic processes of AP,with TUBA1A and GADD45A genes exhibiting prominence in human AP.
基金funded by the Huaneng Group Technology Project‘Geothermal energy exploration,development and area selection in Fujian Province’(TY-21-HJK09)‘Research and application of thermal energy evaluation and gas coupling technology in Fengdong Huaneng Heating Zone’(HNKJ23QN203)‘Research and application of exploration and evaluation of different types of geothermal resources in Shandong Region coupled with clean heating technology’(HNKJ24H021)。
文摘To ensure the long-term and sustainable development and utilization of geothermal resources,the extracted geothermal water should be reinjected.Considering Guantao Formation in the Dezhou Area,the geothermal reinjection process is analyzed through experimental and numerical modeling.Numerical analysis suggests that the reinjectionflow only has a strong influence on the reservoir pressure over a relatively narrow range,whereas the range over which this process has a weak influence exceeds 500 m.Assuming that the reinjection well is full,a reinjectionflow rate of 50-100 m^(3)/h can theoretically be achieved without additional pressure.Experimental modeling of geothermal exploitation and reinjection suggests that sandstone reservoirs with good porosity and permeability should be selected to lower the reinjection pressure of geothermal reservoir projects.In real geothermal reinjection processes,the reinjectionflow rate should be carefully determined to prevent excessive pressure in sandstone reservoirs and ensure long-term stable and efficient reinjection.The Huaneng Geothermal Project has been operating for 2 years,and there has been no significant change in the outlet temperature and reinjection pressure of the geothermal wells.This is generally consistent with the modeling results,demonstrating the accuracy of the exploitation and reinjection modeling analysis.An efficient reinjection scheme for sandstone geothermal reservoirs is developed based on the Huaneng Dezhou Geothermal Heating Project,in which the total reinjection rate is approximately 99.1%.Based on our experimental and numerical modeling,no significant temperature and pressure changes will happen for at least 5 years at the present exploitation and reinjection pressure and amount.
基金Supported by Korea Health Technology R&D Project through the Korea Health Industry Development Institute,Funded by the Ministry of Health&Welfare,Republic of Korea,No.HR20C0025 and No.HI22C1212the National Research Foundation of Korea Grant Funded by the Korea Government,No.RS-2023-00238188。
文摘BACKGROUND Chronic biliary disease,including cholangitis and cholecystitis,is attributed to ascending infection by intestinal bacteria.Development of a mouse model for bile duct inflammation is imperative for the advancement of novel therapeutic approaches.Current models fail to replicate the harmful bacterial influx to the biliary tract observed in humans and spread of inflammation to the liver.Therefore,we aimed to establish an animal model of biliary disease that faithfully replicates the mechanisms of human diseases.AIM To establish a cholecystoduodenal anastomosis model capable of mimicking the mechanisms of ascending infection and inflammation observed in human biliary diseases.METHODS We established a mouse biliary disease model by directly connecting the gallbladder and duodenum,enabling ascending infection into the biliary tract without traversing the sphincter of Oddi.RESULTS In the cholecystoduodenal anastomosis mouse model,we observed impaired epithelial structure,wall thickening,and macrophage recruitment in the gallbladder.Despite the absence of postoperative antibiotics,we detected no changes in serum proinflammatory cytokine levels,indicating no systemic inflammation.Moreover,patency between the gallbladder and duodenum was confirmed via common bile duct ligation.Injection of patient-derived pathogenic bacteria into bile duct-ligated mice led to ascending infection,which significantly increased proinflammatory cytokine mRNA expression in the liver,duodenum,and ileum.These results indicate that our mouse model exhibited a direct connection between the gallbladder and duodenum,leading to ascending infection and closely mimicking the clinical features of biliary diseases observed in humans.CONCLUSION The cholecystoduodenal anastomosis mouse model is an effective chronic biliary disease model with significant relevance in the development of microbiome-based therapies for the prevention and treatment of biliary disease.
文摘BACKGROUND Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity,that negatively affect the patients’quality of life.Experimental studies play an important role in understanding the pathophysiological background of anastomotic healing and there are still many fields that require further investigation.Knowledge drawn from these studies can lead to interventions or techniques that can reduce the risk of anastomotic leak in patients with high-risk features.Despite the advances in experimental protocols and techniques,designing a high-quality study is still challenging for the investigators as there is a plethora of different models used.AIM To review current state of the art for experimental protocols in high-risk anastomosis in rats.METHODS This systematic review was performed according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.To identify eligible studies,a comprehensive literature search was performed in the electronic databases PubMed(MEDLINE)and Scopus,covering the period from conception until 18 October 2023.RESULTS From our search strategy 102 studies were included and were categorized based on the mechanism used to create a high-risk anastomosis.Methods of assessing anastomotic healing were extracted and were individually appraised.CONCLUSION Anastomotic healing studies have evolved over the last decades,but the findings are yet to be translated into human studies.There is a need for high-quality,well-designed studies that will help to the better understanding of the pathophysiology of anastomotic healing and the effects of various interventions.
基金Hebei Province Natural Science Foundation Key Project(H2024104001)Hebei Province Medical Science Research Project Plan(20240287)。
文摘Breast cancer metastasis is a major cause of treatment failure and patient mortality. Mouse tumor models largely replicate the pathophysiological processes of human tumors. Establishing mouse models of breast cancer metastasis helps to elucidate metastatic mechanisms, and in vivo imaging techniques enable dynamic monitoring of tumor cell metastasis in animals. This paper summarizes the mechanisms of breast cancer metastasis, the development, and application of various mouse breast cancer distant metastasis models over the past decade, and evaluates the characteristics and efficacy of each model to provide references for future experimental studies.
文摘The high temperature split Hopkinson pressure bar （SHPB） compression experiment is conducted to obtain the data relationship among strain, strain rate and flow stress from room temperature to 550 C for aeronautical aluminum alloy 7050-T7451. Combined high-speed orthogonal cutting experiments with the cutting process simulations, the data relationship of high temperature, high strain rate and large strain in high-speed cutting is modified. The Johnson-Cook empirical model considering the effects of strain hardening, strain rate hardening and thermal softening is selected to describe the data relationship in high-speed cutting, and the material constants of flow stress constitutive model for aluminum alloy 7050-T7451 are determined. Finally, the constitutive model of aluminum alloy 7050-T7451 is established through experiment and simulation verification in high-speed cutting. The model is proved to be reasonable by matching the measured values of the cutting force with the estimated results from FEM simulations.
基金Project(07JJ4016) supported by the Natural Science Foundation of Hunan Procvince,China
文摘In order to check the validity of the mathematical model for analyzing the flow field in the air-agitated seed precipitation tank,a scaled down experimental apparatus was designed and the colored tracer and KCl tracer were added in the apparatus to follow the real flow line.Virtue tracers were considered in the mathematical model and the algorithm of tracers was built.The comparison of the results between the experiment and numerical calculation shows that the time of the tracer flows out of stirring tube are 40 s in the experiment and 42 s in numerical calculated result.The transient diffusion process and the solution residence time of the numerical calculation are in good agreement with the experimental results,which indicates that the mathematical model is reliable and can be used to predict the flow field of the air-agitated seed precipitation tank.
文摘Beishan Rock Carvings in Chongqing,a renowned cultural heritage site in China,flourished during the Tang and Song dynasties and are often referred to as the“Stone Carving Art Museum of the Tang and Song Dynasties.”Cave 168 is a key component of the Beishan Rock Carvings.At present,several through-going cracks have developed in the roof of Cave 168,severely compromising the structural stability of the grotto.The early internal steel plate supports have suffered severe corrosion and can no longer provide effective reinforcement.In addition,the presence of steel columns obstructs visitor access and negatively affects the viewing experience.A new reinforcement method is urgently needed.Therefore,studying the deformation patterns of the structure is of critical importance.This study analyzes the stratigraphic parameters and fracture distribution of Cave 168,considering key influencing factors such as rainfall,self-weight,and the overlying Quaternary soil.On-site monitoring and physical model experiments were conducted to evaluate the changes in roof crack width and displacement before and after reinforcement with negative Poisson's ratio(NPR)anchor cables.The results reveal that the roof of Cave 168 contains several through-going cracks and numerous microcracks,which serve as infiltration channels for surface water.These accelerate the softening of the mudstone and pose a significant threat to the cave's structural safety.During the experiment,the main change in the crack exhibited a“semi-archshaped”propagation pattern.In the first ten minutes,as the rock transitioned from dry to moist conditions,a slight crack closure was observed.As rainfall continued,crack propagation accelerated.After rainfall ceased,crack width remained stable over a short period.Under NPR anchor support,the influence of rainfall on roof settlement was effectively mitigated,ensuring the safety and stability of the roof.The NPR anchors successfully limited the roof settlement to within 0.3 mm and provided effective control over both total and differential settlement.These findings offer valuable insights into the application of NPR anchor cables in the conservation of grotto heritage structures.
基金supported by the Science Foundation of the Department of Health,Hubei Province,China (No.XF06D43,XF2008-23)
文摘Objective The present study aimed to establish a cerebral schistosomiasis model in rabbits,to provide a valuable tool for morphological analysis,clinical manifestation observation,as well as investigations into immunological reactions and pathogenesis of focal inflammatory reaction in neuroschistosomiasis（NS）.Methods Sixty New Zealand rabbits were randomly assigned into operation,sham-operation and normal groups.Rabbits in the operation group received direct injection of dead schistosome eggs into the brain,while their counterparts in the sham-operation group received saline injection.Rabbits in the normal group received no treatment.Base on the clinical manifestations,rabbits were sacrificed on days 3,5,7,10,20,and 30 post injection,and brain samples were sectioned and stained with hematoxylin-eosin.Sections were observed under the microscope.Results The rabbits in the operation group exhibited various neurological symptoms,including anorexy,partial and general seizures,and paralysis.The morphological analysis showed several schistosome eggs in the nervous tissue on day 3 post operation,with very mild inflammation.On days 7-10 post operation,several schistosome eggs were localized in proximity to red blood cells with many neutrophilic granulocytes and eosinophilic granulocytes around them.The schistosome eggs developed into the productive granuloma stage on days 14-20 post operation.On day 30,the schistosome eggs were found to be in the healing-by-fibrosis stage,and the granuloma area was replaced by fibrillary glia through astrocytosis.The sham-operation group and the normal group showed negative results.Conclusion This method might be used to establish the cerebral schistosomiasis experimental model.Several factors need to be considered in establishing this model,such as the antigenic property of eggs,the time of scarification,and the clinical manifestations.
文摘Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don＇t support theoretical conclusions. The main experimental conclusions are： 1. Wide angle reflection energies are stronger than non-wide-angle reflections （up to twice as strong） but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the non- wide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than non- wide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor.
基金supported by a grant No. 23-19-00039 of Russian Research Fund “Theoretical basis and application tools for developing a system of intellectual fleet planning and support of decisions on Arctic navigation”。
文摘In designing modern vessels, calculating the propulsion performance of ships in ice is important, including propeller effective thrust, number of revolutions, consumed power, and ship speed. Such calculations allow for more accurate prediction of the ice performance of a designed ship and provide inputs for designers of ship power and automation systems. Preliminary calculations of ship propulsion and thrust characteristics in ice can enable predictions of full-scale ice resistance without measuring the propeller thrust during sea trials. Measuring propeller revolutions,ship speed, and the power delivered to propellers could be sufficient to determine the propeller thrust of the vessel. At present, significant difficulties arise in determining the thrust of icebreakers and ice-class ships in ice conditions. These challenges are related to the fact that the traditional system of propeller/hull interaction coefficients does not function correctly in ice conditions. The wake fraction becomes negative and tends to minus infinity starting from a certain value of the propeller advance coefficient. This issue prevents accurate determination of the performance characteristics, thrust, and rotational speed of the propulsors. In this study, an alternative system of propeller/hull interaction coefficients for ice is proposed. It enables the calculation of all propulsion parameters in ice based on standard hydrodynamic tests with selfpropulsion models. An experimental method is developed to determine alternative propeller/hull interaction coefficients. A prediction method is suggested to determine propulsion performance in ice based on the alternative interaction coefficient system. A case study applying the propulsion prediction method for ice conditions is provided. This study also discusses the following issues of ship operation in ice: the scale effect of icebreaker propellers and the prospects for introducing an ice interaction coefficient.
基金supported by the Water Conservancy Science and Technology Project of Fujian Province(KJG21009A)the Significant Science and Technology Projects of the Ministry of Water Resources(SKS-2022073)the Scientific and Technological Innovation Project of Natural Resources in Fujian Province(KY-070000-04-2022-013)。
文摘Plant roots improve the stability of collapsing walls and prevent their collapse;they are thus important for controlling the degree of Benggang erosion in southern China.The vegetation species on the collapsing walls are diverse,and the interaction of the root systems with soil affects the stability of the collapsing walls.Most recent studies have only examined the effects of single plants.In order to investigate the effects of the roots of different vegetation types on the shear strength of soil in collapsing walls and their interaction mechanisms of action,this study was conducted using the roots of the herb Dicranopteris dichotoma and the shrub Melastoma candidum.A direct shear test of indoor remodeled soil was carried out by varying water content(15%,25%)and herb to shrub root ratio(100:0,75:25,50:50,25:75,and 0:100).The results showed that the shear strength(96.09 kPa)and cohesion(49.26 kPa)of root-containing soil were significantly higher than plain soil(91.77 kPa,42.17 kPa),and the highest values were obtained when herb to shrub root ratio was 100:0(113.27 kPa,62.85 kPa).Here,tensile tests and scanning electron microscopy revealed that the tensile force and tensile strength of the roots of Dicranopteris dichotoma were weaker but effective for maintaining soil stability because of their abundance roots,which could achieve a stronger bond to soil.Simultaneously,herbaceous roots have a small diameter,the Root Area Ratio(RAR)of the roots is larger under the same mass condition,which can better contact with soil and the mechanical properties of roots are fully utilized.Therefore,the soil shear strength is higher and can better resist external damage when herbaceous roots accounts for a larger proportion.The results of this research have implications for the selection and allocation of ecological measures for prevention and control of Benggang.
文摘The instability and failure of high rock slopes have a significant impact on the safe mining operations.Therefore,revealing the instability mechanism of high rock slopes is of great research significance.This paper aims to reveal the instability mechanism of high rock slopes through physical model tests and numerical simulations.Taking the slope failure on the west side of Pit 1 of Husab Uranium Mine in Namibia in 2021 as the research background,a physical model of the high rock slope of Husab Uranium Mine was established by combining with on-site geological data.The experimental system was monitored by a GoPro camera,a CCD camera,and strain sensors.The damage evolution process of the high rock slope model was analyzed,and numerical simulation verification was carried out using Flac 3D software.Thus,the instability mechanism of the slope failure in this open-pit mine was revealed from multiple perspectives.The results show that the instability mechanism of the high rock slope was determined through the evolution of the displacement field and strain field during the model excavation process,as well as the deformation characteristics of the images at the time of instability and failure.The slope deformation process can be divided into four stages:the initial inter-layer dislocation stage,the crack generation stage,the crack propagation stage,and the crack penetration and failure stage.The results of the model experiment and numerical simulation confirm the consistency between the failure mode of the model slope and the actual slope failure on-site,providing guidance for the prevention and control projects of similar types of mine failures.
基金The authors express their gratitude to the financial support from National Key R&D Program of China(No.2023YFB2604001)National Natural Science Foundation of China(No.52478475,No.52378463 and No.52168066).
文摘The pile-plate structure has proven highly effective support for high-speed railway subgrades,particularly in poor geological conditions.Although its efficacy in non-frozen regions is well-established,its potential in frozen regions remains underexplored.In seasonally frozen areas,F-T(freeze-thaw)cycles threaten subgrade stability,necessitating research on pile-plate structure’s behavior under such conditions.To address this challenge,a scaled model experiment was conducted on a silty sand foundation,simulating F-T cycles using temperature control devices.Key parameters,including soil temperature,frozen depth,and displacement,were systematically monitored.Results indicate that the bearing plate functions as an effective insulation layer,significantly reducing sub-zero temperature penetration.Additionally,the anchoring action of the piles mitigates frost heave in the foundation soil,while the plate middle restrains soil deformation more effectively due to increased constraint.The thermal insulation provided by the plate maintains higher soil temperatures,delaying the onset of freezing.By the end of each freezing stage,the vertical displacement in the natural subgrade is approximately 4 times greater than that beneath the pile-plate structure.Furthermore,the frost depth is about 1.3-1.4 times and 1.6-4.9 times greater than that measured below the plate edge and middle,respectively.These insights contribute to the development of more resilient designs for high-speed railway subgrades in seasonally frozen regions,offering engineers a robust,scientifically-backed foundation for future infrastructure projects.
基金supported by the National Natural Science Foundation of China (grant nos. 42074137)。
文摘A cased well model consists of a coaxial tank and casing,which houses coaxially installed transmitting and receiving coils.The transmitting coil is excited by the current produced by the transmitting circuit,and transient electromagnetic responses occur in the casing,including direct coupling and casing responses.As the range between the transmitting and receiving coils increases,direct coupling responses decay rapidly,are less than the casing response at 0.3 m,and disappear at 0.7 m.By contrast,a casing response increases rapidly and then declines slowly after reaching a peak and changes little within a specifi c range.The peak decreases slowly with range.The continuous addition of water to the tank causes slight changes in transient electromagnetic responses,so the diff erence which are subtracted from the response without water is used.Moreover,the diff erences at the time of rapid increase in response and the time of rapid decrease in response are large,forming a peak and a trough.Given that the conductivity of water in a full tank changes after the addition of salt,the diff erence in the peak is linear with the increase in the conductivity of water.This result provides an experimental basis for the design of a transient electromagnetic logging instrument that measures the conductivity of formation in cased well.
