This work’s goal was to compile a list of fishing-related violations in order to suggest ways to enhance the surveillance system.In order to accomplish this goal,the following approach was used:Executive consultation...This work’s goal was to compile a list of fishing-related violations in order to suggest ways to enhance the surveillance system.In order to accomplish this goal,the following approach was used:Executive consultation and archive exploitation;surveillance agent survey;surveillance system identification and description;identification of offenses and fleet involved in the Guinean exclusive and economic area in recent years;identification and categorization of offense causes;surveillance system evaluation;and suggestion for enhanced surveillance system measures.Monitoring of this strategy showed that:fishing operating zones,administrative paperwork,and fishing gear are all linked to the infractions committed in the Guinean exclusive and economic zone.Records show that there were 308 boardings between 2006 and 2021.IP(Intellectual Property)infringement rates are 59%,Motorized Artisanal Fishing is 25%,and Semi-industrial fishing is 16%.In Motorized Artisanal Fishing,the Guineans have committed 33,the Senegalese have committed 23,and the Leonese have committed 18.In Semi-industrial fishing,the Chinese have committed 17 and the Senegalese have committed 16.According to the stakeholder survey,Vessal Monitoring System monitored 79 vessels in industrial fishing and 49 in Semi-industrial fishing in 2021.Registration certificates,personnel,rescue gear,gross tonnage,coastal state fishing authority,and maritime radio license are typically the primary documents examined at sea.From 2006 to 2022,a total of 135 fleets-80 demersal trawlers,7 cephalopod boats,21 shrimp boats,22 pelagic trawlers,and 5 cargo ships-were implicated in violations in the Guinean exclusive and economic area.By integrating the automatic identification system and Vessal Monitoring systems for fisheries surveillance,establishing a marking system for fishing gear,investing in highly effective launches,and protecting the privacy of patrol activities,Guinea’s surveillance system might be improved more effectively.展开更多
at present,data security has become the most urgent and primary issue in the era of digital economy.Marine scientific data security is the most urgent core issue of marine data resource management and sharing service....at present,data security has become the most urgent and primary issue in the era of digital economy.Marine scientific data security is the most urgent core issue of marine data resource management and sharing service.This paper focuses on the analysis of the needs of marine scientific data security governance,in-depth development of marine scientific data security governance approaches and methods,and practical application in the national marine scientific data center,optimizing the existing data management model,ensuring the safety of marine scientific data,and fully releasing the data value.展开更多
To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conduc...To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conducted based on the numerical results of two mathematical models,the rigid-body model and fluid-structure interaction model.In addition,the applicable scope of the above two methods,and the structural response characteristics of the projectile have also been investigated.Our results demonstrate that:(1) The impact loads and angular motion of the projectile of the rigid-body method are more likely to exhibit periodic variations due to the periodic tail slap,its range of positive angles of attack is about α<2°.(2) When the projectile undergone significant wetting,a strong coupling effect is observed among wetting,structural deformation,and projectile motion.With the applied projectile shape,it is observed that,when the projectile bends,the final wetting position is that of Part B(cylinder of body).With the occu rrence of this phenomenon,the projectile ballistics beco me completely unstable.(3) The force exerted on the lower surface of the projectile induced by wetting is the primary reason of the destabilization of the projectile traj ectory and structu ral deformation failure.Bending deformation is most likely to appear at the junction of Part C(cone of body) and Part D(tail).The safe angles of attack of the projectile stability are found to be about α≤2°.展开更多
Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical e...Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical experimental measurement and numerical simulation pose research challenges.This study focuses on the ice load of a cylinder structure breaking upward through the ice sheet form underneath in the Small Ice Model Basin of China Ship Scientific Research Center(CSSRC SIMB).A high-speed camera system was employed to observe the ice sheet failure during the tests,in which,with the loading position as center,local radial cracks and circumferential cracks were generated.A load sensor was used to measure the overall ice load during this process.Meanwhile,a numerical model was developed using LS-DYNA for validation and comparison.With this model,numerical simulation was conducted under various ice thicknesses and upgoing speeds to analyze the instantaneous curves of ice load.The calculation results were statistically analyzed under different working conditions to determine the influence of the factors on the ice load of the cylinder.The study explores the measurement method about ice load of objects vertically breaking through model ice sheet and is expected to provide some fundamental insights into the safety design of underwater structures operating in ice waters.展开更多
Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data...Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data that mooring system designers aim to acquire.To address the need for long-term continuous monitoring of mooring tension in deep-sea marine environments,this paper presents a mooring cable tension monitoring method based on the principle of direct mechanical measurement.The developed tension monitoring sensors were installed and applied in the mooring system of the"Yongle"scientific experimental platform.Over the course of one year,a substantial amount of in-situ tension monitoring data was obtained.Under wave heights of up to 1.24 m,the mooring tension on the floating platform reached 16.5 tons.Through frequency domain and time domain analysis,the spectral characteristics of mooring tension,including waveinduced force,slow drift force,and mooring cable elastic restoring force,were determined.The mooring cable elastic restoring force frequency was approximately half of that of the wave signal.Due to the characteristics of the hinge connection structure of the dual module floating platform,under some specific working conditions the wave-induced force was the maximum of the three different frequency forces,and restoring force was the smallest.展开更多
The semiconductor photocatalysis are considered as one of the most promising candidates in hydrogen energy source and environmental remediation area.In this paper,flower-shaped SnS,is successfully combined on g-C,Ns,a...The semiconductor photocatalysis are considered as one of the most promising candidates in hydrogen energy source and environmental remediation area.In this paper,flower-shaped SnS,is successfully combined on g-C,Ns,and the well matching band structure successfully constitutes a new Type-II heterojunction.As expected,the photocatalytic hydrogen production experiment showed that the quantity of hydrogen produced on 5% SnS_(2)/C_(3)N_(5)was 922.5μmol/(g.h),which is 3.6 times higher than that of pure g-C_(3)N_(5).Meanwhile,in photocatalytic degradation of methylene blue,5%SnS2/C,Ns composite material can degrade 95% of contaminants within 40 min,showing good photocatalytic degradation performance.The mechanism study indicates that SnS_(2)/C_(3)N_(5)heterojunction improves the photogenerated charge migration rate and reduces the electron-hole recombination rate,and effectively improves the photocatalytic performance of g-C_(3)N_(5).This work provides a new idea for designing C,Ns-based heterojunctions with efficient hydrogen production and degradation performance.展开更多
The operation of deep-sea underwater vehicles relies entirely on onboard batteries.However,the extreme deep-sea conditions,characterized by ultrahigh hydraulic pressure,low temperature,and seawater conductivity,pose s...The operation of deep-sea underwater vehicles relies entirely on onboard batteries.However,the extreme deep-sea conditions,characterized by ultrahigh hydraulic pressure,low temperature,and seawater conductivity,pose significant challenges for battery development.These conditions drive the need for specialized designs in deep-sea batteries,incorporating critical aspects of power generation,protection,distribution,and management.Over time,deep-sea battery technology has evolved through multiple generations,with lithium(Li)batteries emerging in recent decades as the preferred power source due to their high energy and reduced operational risks.Although the rapid progress of Li batteries has notably advanced the capabilities of underwater vehicles,critical technical issues remain unresolved.This review first systematically presents the whole picture of deep-sea battery manufacturing,focusing on Li batteries as the current mainstream solution for underwater power.It examines the key aspects of deep-sea Li battery development,including materials selection informed by electro-chemo-mechanics models,component modification and testing,and battery management systems specialized in software and hardware.Finally,it discusses the main challenges limiting the utilization of deep-sea batteries and outlines promising directions for future development.Based on the systematic reflection on deep-sea batteries and discussion on deep-sea Li batteries,this review aims to provide a research foundation for developing underwater power tailored for extreme environmental exploration.展开更多
As a typical steel,the fatigue of marine high-strength steels has been emphasized by scholars.In this paper,the fatigue performance and crack growth mechanism of a high-strength steel for ships are investigated by exp...As a typical steel,the fatigue of marine high-strength steels has been emphasized by scholars.In this paper,the fatigue performance and crack growth mechanism of a high-strength steel for ships are investigated by experimental methods.First,the fatigue threshold test and fatigue crack growth rate test of this high-strength steel under different stress ratios were carried out.The influence of stress ratio on the fatigue properties of this steel was analyzed.Secondly,scanning electron microscope was used to analyze the crack growth specimen section of this steel.The crack growth and failure mechanism of this steel were revealed.Finally,based on the above research results,the stress ratio effect of high-strength steel was investigated from the perspectives of crack closure and driving force.Considering the fatigue behavior in the near-threshold stage and the destabilization stage,a fatigue crack growth behavior prediction model of highstrength steel was established.The accuracy of the model was verified by test data.Moreover,the applicability of the modified model to various materials and its excellent predictive ability were verified through comparison with literature data and existing models.展开更多
The high prevalence of obesity and associated nonalcoholic fatty liver disease(NAFLD)in the population determines the increased interest in identifying molecular targets for regulating the processes underlying these p...The high prevalence of obesity and associated nonalcoholic fatty liver disease(NAFLD)in the population determines the increased interest in identifying molecular targets for regulating the processes underlying these patholo-gies.The search for new endogenous bioregulators of lipid metabolism and their inclusion in therapeutic regimens for the treatment of patients is becoming a potentially promising direction in science and medicine.Oleoylethanolamide(OEA)is an endogenous lipid mediator capable of exerting multiple hypolipidemic,anti-inflammatory,and hepato-protective effects mediated by agonism with receptors of the peroxisome proliferator-activated receptor(PPAR)family(PPAR-αand PPAR-γ).This review focuses on a detailed description of the PPAR-dependent mechanisms of the hepatoprotective activity of OEA in the development of NAFLD.The main attention is paid to such topics as reduction of oxidative stress and inflammation,inhibition of liver fibrogenesis,suppression of hepatocyte death,and changes in various parameters of lipid metabolism.展开更多
The problem of ulcerative colitis(UC)is becoming increasingly relevant due to its prevalence and combination with psychological disorders.UC is associated with alterations in the intestinal microbiocenosis as one of t...The problem of ulcerative colitis(UC)is becoming increasingly relevant due to its prevalence and combination with psychological disorders.UC is associated with alterations in the intestinal microbiocenosis as one of the factors reducing tolerance to self-antigens.In addition,patients with UC often experience anxiety,depression and other negative emotional and psychological factors aggravating the course of the underlying disease.The study presented by Wang et al shows that the traditional Chinese medicine Wuling can exert its therapeutic effect by reversing the aberrant precursor of brain-derived neurotrophic factor(BDNF)/BDNF signaling in mice with UC and depression.The combination of Wuling powder with mesalazine can exhibit an antidepressant effect and reduce intestinal inflammation.Undoubtedly,the study by Chinese authors deserves attention,and changes in the balance of precursor of BDNF/p75 neurotrophin receptor/sortilin and BDNF/tropomyosin receptor kinase B signaling may become a novel therapeutic target for clinical treatment and further development of research.展开更多
The problem of metabolic dysfunction-associated steatotic liver disease(MASLD)is becoming a non-infectious pandemic,the growth drivers of which are obesity and diabetes mellitus.According to modern concepts,MASLD deve...The problem of metabolic dysfunction-associated steatotic liver disease(MASLD)is becoming a non-infectious pandemic,the growth drivers of which are obesity and diabetes mellitus.According to modern concepts,MASLD develops and progresses as a result of the interaction of multiple genetic,environmental and adaptive factors,which include specific genetic polymorphisms(for example,the patatin-like phospholipase domain-containing protein 3 gene)and epigenetic modifications,dietary patterns(for example,high consumption of saturated fats and fructose),physical inactivity,obesity,insulin resistance,dysregulation of adipokine production,lipotoxicity,oxidative stress,intestinal microbiota dysbiosis(small intestinal bacterial overgrowth syndrome).In addition,due to the high infection rate of Helicobacter pylori(up to 80%)of people in the population,the influence of this factor on the development and progression of MASLD cannot be ruled out.Ye et al presented a study investigating the relationship between Helicobacter pylori infection and metabolic dysfunction associated with hepatic steatosis and identified prognostic factors.Certainly,the work of the Chinese authors deserves attention and further study.展开更多
The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic...The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic study on isostructural 2D coordination polymers(CPs)based on 1,10-ferrocenediyl-bis(H-phosphinic)acid,with cobalt,manganese,and cadmium metals as electrocatalysts for OER.These polymers were synthesized via a facile solution reaction,yielding crystalline materials with excellent structural integrity.The electrocatalytic performance of CPs composites,prepared with carbon and phosphonium ionic liquid,was evaluated in 0.1 M KOH using a three-electrode system.Notably,the Co-and Cd-based CPs demonstrated exceptional OER activity,achieving an overpotential as low as 236–255 mV at 10 mA cm^(-2),surpassing those of many previously reported CP-based OER catalysts.Furthermore,these materials exhibited high stability over prolonged electrolysis,maintaining their activity without significant degradation.This work not only introduces a new class of ferrocenyl phosphinatebased CPs as highly active and durable OER catalysts but also provides valuable insights into their structureactivity relationships,paving the way for future advancements in electrocatalysis.展开更多
The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucas...The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucasus under the global climate change conditions are introduced in the current article.The main goal of our scientific work is to study and assess the current ecological and resource state of natural phytocenoses,pastures and hayfields in the arid and semi-arid landscapes under climate change.The paper presents the results of determining the areas and levels of degradation of the natural biogeocenoses and biogeocenoses of the pastures and hayfields in the mountain and highland landscapes.The results were obtained using remote sensing,field and laboratory studies and analyses.The conducted studies have revealed that along 34,174.5 ha pasture and 1342.0 meadows areas of the pastures at the Areni,Yeghegis,Yeghegnadzor and Vayq consolidated administrative territories situated in the arid and semi-arid zones of the Vayots Dzor Region high degradation was recorded in about 6508 hectares of pasture and 407 hectares of meadows areas,which is related to irregular and uncontrolled economic mismanagement of the local population and global climate change.To improve the ecological condition,accessibility and quality of ecosystem services of the pastures,hayfields and natural meadows,comprehensive restoration bioecological and agrotechnical measures have been proposed.They are aimed at improving the air,water and nutrient regimes of soils,at their bioprotection,as well as at the general increase in area and at improving the economic characteristics of the vegetation cover.Such measures on the ecosystem basis are appropriate in the context of enriching the qualitative composition of plants with useful ecological and economic bioecological characteristics,taking into account the characteristics of landscapes,weather and climatic conditions,and agricultural opportunities.展开更多
Objective:Activation of mitophagy is a promising option to overcome the mitochondrial malfunction that accompanies many diseases.Herein,we investigate the mechanisms underlying the ability of sodium lactate and pyruva...Objective:Activation of mitophagy is a promising option to overcome the mitochondrial malfunction that accompanies many diseases.Herein,we investigate the mechanisms underlying the ability of sodium lactate and pyruvate to initiate mitophagy,from the perspective of action on mitochondrial network and expression levels.Methods:Fluorescent and confocal microscopy was used to assess key cell parameters characterizing the state of the mitochondrial network and the level of mitophagy in human fibroblasts carrying mutations in genes encoding LRRK2 and PINK1 after the combined application of lactate and pyruvate and after direct acidification.qRT-PCR was used to study the expression levels of key mitophagy genes.Results:Cells with a mutation in the PINK1 gene showed a lower basal cytosolic pH.The application of sodium lactate and pyruvate to the cells with mutations associated with Parkinson’s disease caused intracellular acidification.Lowering extracellular pH to 6.0 led to a decrease in mitochondrial membrane potential,while the effect of lactate and pyruvate tended to increase this parameter.Extracellular acidification,as well as the effects of lactate and pyruvate,led to an increased level of mitophagy,and also affected such parameters of the mitochondrial network morphology as the ratio of individual to network mitochondria,branch length in mitochondrial network,number of mitochondrial junctions in the network,and also altered the expression of key mitophagy genes.Conclusion:Direct acidification and one induced by lactate and pyruvate do not differ in the efficiency of their effects on the mitochondrial network and mitophagy but change the cell fate differently.The mechanisms of acidification-induced activation of mitophagy differ in control and mutant fibroblasts.展开更多
Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in...Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in regions where wheat cultivation is challenging or unfeasible.To clarify its drought adaptation mechanisms,we analyzed the effects of moderate soil drought on growth,hormonal homeostasis,and the dynamics and distribution of free amino acids and phenolic compounds in rye at early vegetative stages and post-recovery.Drought triggered both general and organ-specific changes in endogenous phytohormones.A nonspecific response involved the accumulation of stress hormones abscisic acid(ABA)and salicylic acid(SA),alongside the suppression of growth hormones indole-3-acetic acid(IAA)and gibberellins.However,hormone dynamics and localization varied across plant organs.ABA and SA levels significantly increased in shoots of drought-stressed and recovered plants,corresponding with inhibited growth.Prolonged drought further enhanced ABA accumulation in both shoots and roots of recovered plants,while SA levels declined in roots but remained elevated in shoots.Drought also caused a substantial reduction in IAA,particularly in shoots,while gibberellins(GA_(3)+GA_(4))significantly decreased in roots.GA_(3)was predominant in most samples,except in the shoots of 2-day-old control plants.Post-recovery,IAA levels increased but remained below control values,while GA_(4)accumulation in roots led to a rise in total gibberellin levels.In contrast,shoot GA_(3)+GA_(4)levels declined,primarily due to GA_(3)reduction.The dominant free amino acids:aspartic acid,glutamic acid,glycine,alanine,and leucinedecreased significantly,underscoring their key role in stress adaptation.Increased flavonoid accumulation,especially in roots,suggests their involvement in antioxidant defense against oxidative stress.A significant increase in ABA and SA levels,along with a marked reduction in IAA and GA content in stressed rye plants occurred alongside a reduction in free amino acid content,accumulation of phenolic compounds,and an increase in flavonoid levels.These findings indicate distinct adaptation strategies in rye shoots and roots undermoderate soil drought.They provide a foundation for further research on drought resistance mechanisms in cereals and the development of strategies to enhance their adaptive potential.展开更多
Humans have always engaged with their surroundings and the ecology in which they live.However,during the industrial age,this contact has been more intense and has had a substantial impact on environment and ecosystems...Humans have always engaged with their surroundings and the ecology in which they live.However,during the industrial age,this contact has been more intense and has had a substantial impact on environment and ecosystems.For example,overexploitation of natural resources,mining,pollution,and deforestation are all elements that negatively affect biodiversity and natural resources.Few studies have been conducted to evaluate the damage caused,despite the significant uncontrolled pressure from human activity.However,maintaining its environment is essential to the survival of coastal fishing.Goal:This study’s goal was to evaluate how human activity affected Tabounsou’s coastal ecology in order to suggest remedial actions for sustainable management.The following was the methodological approach used:executive consultation and archival analysis;stakeholder survey(locals,farmers,salt producers,fishers,and loggers);inventory of species;anthropogenic activity inventory;evaluation of how human activity affects aquatic life in the research region;suggestion and action for sustainable management;Outcome:Executive consultation indicated that the main issues are:construction projects that reduce the estuary’s surface area;agricultural practices such as woodcutting and salt farming;the rise in resource exploitation;noncompliance with fisheries laws;and the catching of young fish.Eighty-three percent of fisherman ditch their nets on the coast after using them,but only seventeen percent burn them.With a 75%frequency rate,the same survey indicates that most fisherman fish around the coast.In the Tabounsou area,according to loggers’survey,68%of the wood cut is Rhizophora,24%is Avicennia,and 8%is Laguncularia.Three fish stocks,representing nine families and nine species,were identified by the species inventory.At 18%and 15%,respectively,the actors most frequently capture the species Pseudotolithus elongatus and Arius parkii.According to a poll of 30 farmers,90%of them apply fertilizer to their soil,while only 10%do not.During the dry season,salt is grown.According to two actors,Bougna Toro Toro produces 100 kg of salt per day,followed by Khoumawadé,which produces 80 kg,and Toumbibougni,which produces 70 kg.展开更多
This study presents a new boundary element method(BEM)framework for the numerical solution of general time-dependent or transient problems.By reformulating the time derivative as a domain integral,the framework effect...This study presents a new boundary element method(BEM)framework for the numerical solution of general time-dependent or transient problems.By reformulating the time derivative as a domain integral,the framework effectively decouples the treatment of spatial and temporal variables,allowing for the independent application of specialized discretization methods.For the temporal domain,we introduce an innovative time-spectral integration technique,which is based on Gaussian-quadrature-based orthogonal polynomial expansions.This method not only achieves arbitrary orders of accuracy but also significantly enhances computational efficiency and stability,particularly for simulations involving rapid transients or long-time dynamic simulations.The domain integrals in the spatial domain are calculated using the scaled coordinate transformation BEM(SCT-BEM),a mathematically rigorous technique that converts domain integrals into equivalent boundary integrals,preserving the boundary-only discretization advantage inherent in BEM.Numerical experiments on transient heat conduction and dynamic wave propagation further demonstrate the framework’s performance and capabilities.These experiments show that the proposed framework outperforms traditional time-stepping BEM methods,particularly in terms of stability,convergence rates,and computational cost,making it a highly promising tool for practical engineering applications.展开更多
Currently,there is an essential need for bioresorbable bone implants with antibacterial,anti-inflammatory properties as well as osteoinductivity.Considering this,in presented study for the first time hybrid Mg-ZK coat...Currently,there is an essential need for bioresorbable bone implants with antibacterial,anti-inflammatory properties as well as osteoinductivity.Considering this,in presented study for the first time hybrid Mg-ZK coatings with polydopamine(PDA),menaquinone-7(MK-7),zoledronate(ZA)and vancomycin on the hydroxyapatite(HA)containing layer are formed.Porous coatings were obtained by the plasma electrolytic oxidation(PEO)on an Mg alloy,then MK-7 was impregnated into the pores and PDA film with ZA and vancomycin was polymerized on the samples surface.The presence of HA and organic bioactive compounds was confirmed by EDS,Raman spectroscopy,XRD and XPS.Surface free energy values of hybrid coatings are close to optimal for cell adhesion:75.28±1.35 mJ/m^(2).Viability tests of the medium,in which Mg-ZK implants were soaked,revealed cytotoxic activity on human osteosarcoma cells with no such an effect on fibroblasts.Antibacterial tests showed an inhibition zone on S.aureus with no viable colonies on the hybrid coatings.The growth inhibition zones for the samples with the hybrid coating were 21±1 mm.Data of electrochemical impedance spectroscopy shows increase of corrosion resistance of samples with hybrid coating by 7 times comparing the Mg alloy without a coating.These properties make the hybrid Mg-ZK coating an attractive modification for bone implants.展开更多
During strong unsteady flow processes such as cavitation initiation and collapse,the volume changes generated by the materials transformation of cavitation phase transition seriously lag behind the volume evolution fo...During strong unsteady flow processes such as cavitation initiation and collapse,the volume changes generated by the materials transformation of cavitation phase transition seriously lag behind the volume evolution formed by the flow process.The phase transition and hydrodynamics are in a non-equilibrium state.A cavitation model that can describe such non-equilibrium phenomena is needed in numerical simulations of cavitation flow.The paper starts from the molecular dynamics’principle of phase change of matter,and based on the Maxwell velocity distribution form of molecular thermal motion,elaborates on the formation process of Hertz Knudsen formula for material exchange at the interface between liquid and vapor.On this basis,using the evolution equation of gas nucleus number density in water and the compressible state equation of vapor,a non-equilibrium cavitation model for phase transition and hydrodynamics is established.The simulation results of a vapor bubble collapse process in the non-equilibrium cavitation model show different behavior from the simulation results of the equilibrium cavitation model.The simulation results of the equilibrium cavitation model show that the vapor bubble collapses once and completely disappear,while the simulation results of the non-equilibrium cavitation model show multiple collapses and rebound,which is agreement with the experimental results of the vapor bubble collapse.展开更多
Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In t...Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In this study,based on the fracture mechanics method,a calculation method for estimating the residual fatigue life of a PMMA manned cabin is proposed by improving the small-time scale fatigue crack growth rate model.This improved model is verified by the experimental data of the PMMA material.Then,through the Weibull and Gumbel combined distribution functions,the fatigue load spectrum suitable for the fully transparent manned cabin is fitted according to the dive data.A parametric analysis of the residual fatigue life of the fully transparent manned cabin under various initial crack sizes and dwell time is conducted,yielding valuable results.This study aims to increase the safety of fully transparent pressure-resistant cabins and offer insights for fatigue analysis of underwater structures utilizing PMMA materials.展开更多
文摘This work’s goal was to compile a list of fishing-related violations in order to suggest ways to enhance the surveillance system.In order to accomplish this goal,the following approach was used:Executive consultation and archive exploitation;surveillance agent survey;surveillance system identification and description;identification of offenses and fleet involved in the Guinean exclusive and economic area in recent years;identification and categorization of offense causes;surveillance system evaluation;and suggestion for enhanced surveillance system measures.Monitoring of this strategy showed that:fishing operating zones,administrative paperwork,and fishing gear are all linked to the infractions committed in the Guinean exclusive and economic zone.Records show that there were 308 boardings between 2006 and 2021.IP(Intellectual Property)infringement rates are 59%,Motorized Artisanal Fishing is 25%,and Semi-industrial fishing is 16%.In Motorized Artisanal Fishing,the Guineans have committed 33,the Senegalese have committed 23,and the Leonese have committed 18.In Semi-industrial fishing,the Chinese have committed 17 and the Senegalese have committed 16.According to the stakeholder survey,Vessal Monitoring System monitored 79 vessels in industrial fishing and 49 in Semi-industrial fishing in 2021.Registration certificates,personnel,rescue gear,gross tonnage,coastal state fishing authority,and maritime radio license are typically the primary documents examined at sea.From 2006 to 2022,a total of 135 fleets-80 demersal trawlers,7 cephalopod boats,21 shrimp boats,22 pelagic trawlers,and 5 cargo ships-were implicated in violations in the Guinean exclusive and economic area.By integrating the automatic identification system and Vessal Monitoring systems for fisheries surveillance,establishing a marking system for fishing gear,investing in highly effective launches,and protecting the privacy of patrol activities,Guinea’s surveillance system might be improved more effectively.
文摘at present,data security has become the most urgent and primary issue in the era of digital economy.Marine scientific data security is the most urgent core issue of marine data resource management and sharing service.This paper focuses on the analysis of the needs of marine scientific data security governance,in-depth development of marine scientific data security governance approaches and methods,and practical application in the national marine scientific data center,optimizing the existing data management model,ensuring the safety of marine scientific data,and fully releasing the data value.
基金supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_0714).
文摘To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conducted based on the numerical results of two mathematical models,the rigid-body model and fluid-structure interaction model.In addition,the applicable scope of the above two methods,and the structural response characteristics of the projectile have also been investigated.Our results demonstrate that:(1) The impact loads and angular motion of the projectile of the rigid-body method are more likely to exhibit periodic variations due to the periodic tail slap,its range of positive angles of attack is about α<2°.(2) When the projectile undergone significant wetting,a strong coupling effect is observed among wetting,structural deformation,and projectile motion.With the applied projectile shape,it is observed that,when the projectile bends,the final wetting position is that of Part B(cylinder of body).With the occu rrence of this phenomenon,the projectile ballistics beco me completely unstable.(3) The force exerted on the lower surface of the projectile induced by wetting is the primary reason of the destabilization of the projectile traj ectory and structu ral deformation failure.Bending deformation is most likely to appear at the junction of Part C(cone of body) and Part D(tail).The safe angles of attack of the projectile stability are found to be about α≤2°.
文摘Ice load on underwater vehicles breaking through ice covers from underneath is a significant concern for researchers in polar exploration,and the research on this problem is still in its early stages.Both mechanical experimental measurement and numerical simulation pose research challenges.This study focuses on the ice load of a cylinder structure breaking upward through the ice sheet form underneath in the Small Ice Model Basin of China Ship Scientific Research Center(CSSRC SIMB).A high-speed camera system was employed to observe the ice sheet failure during the tests,in which,with the loading position as center,local radial cracks and circumferential cracks were generated.A load sensor was used to measure the overall ice load during this process.Meanwhile,a numerical model was developed using LS-DYNA for validation and comparison.With this model,numerical simulation was conducted under various ice thicknesses and upgoing speeds to analyze the instantaneous curves of ice load.The calculation results were statistically analyzed under different working conditions to determine the influence of the factors on the ice load of the cylinder.The study explores the measurement method about ice load of objects vertically breaking through model ice sheet and is expected to provide some fundamental insights into the safety design of underwater structures operating in ice waters.
文摘Mooring cable tension is a crucial parameter for evaluating the safety and reliability of a floating platform mooring system.The real-time mooring tension in an actual marine environment has always been essential data that mooring system designers aim to acquire.To address the need for long-term continuous monitoring of mooring tension in deep-sea marine environments,this paper presents a mooring cable tension monitoring method based on the principle of direct mechanical measurement.The developed tension monitoring sensors were installed and applied in the mooring system of the"Yongle"scientific experimental platform.Over the course of one year,a substantial amount of in-situ tension monitoring data was obtained.Under wave heights of up to 1.24 m,the mooring tension on the floating platform reached 16.5 tons.Through frequency domain and time domain analysis,the spectral characteristics of mooring tension,including waveinduced force,slow drift force,and mooring cable elastic restoring force,were determined.The mooring cable elastic restoring force frequency was approximately half of that of the wave signal.Due to the characteristics of the hinge connection structure of the dual module floating platform,under some specific working conditions the wave-induced force was the maximum of the three different frequency forces,and restoring force was the smallest.
基金This project was supported by the Fundamental Research Program of Shanxi Province(202303021221058)。
文摘The semiconductor photocatalysis are considered as one of the most promising candidates in hydrogen energy source and environmental remediation area.In this paper,flower-shaped SnS,is successfully combined on g-C,Ns,and the well matching band structure successfully constitutes a new Type-II heterojunction.As expected,the photocatalytic hydrogen production experiment showed that the quantity of hydrogen produced on 5% SnS_(2)/C_(3)N_(5)was 922.5μmol/(g.h),which is 3.6 times higher than that of pure g-C_(3)N_(5).Meanwhile,in photocatalytic degradation of methylene blue,5%SnS2/C,Ns composite material can degrade 95% of contaminants within 40 min,showing good photocatalytic degradation performance.The mechanism study indicates that SnS_(2)/C_(3)N_(5)heterojunction improves the photogenerated charge migration rate and reduces the electron-hole recombination rate,and effectively improves the photocatalytic performance of g-C_(3)N_(5).This work provides a new idea for designing C,Ns-based heterojunctions with efficient hydrogen production and degradation performance.
基金support provided by National Key Research and Development Program of China(2023YFE0203000 and 2016YFC0300200)the NSAF(Grant No.U2330205)+3 种基金Full-Sea-Depth Battery Project(2020-XXXX-XX-246-00)Open project of Shaanxi Laboratory of Aerospace Power(2022ZY2-JCYJ-01-09)Fundamental Research Funds for the Central Universities,ND Basic Research Funds(G2022WD)the Innovation Team of Shaanxi Province。
文摘The operation of deep-sea underwater vehicles relies entirely on onboard batteries.However,the extreme deep-sea conditions,characterized by ultrahigh hydraulic pressure,low temperature,and seawater conductivity,pose significant challenges for battery development.These conditions drive the need for specialized designs in deep-sea batteries,incorporating critical aspects of power generation,protection,distribution,and management.Over time,deep-sea battery technology has evolved through multiple generations,with lithium(Li)batteries emerging in recent decades as the preferred power source due to their high energy and reduced operational risks.Although the rapid progress of Li batteries has notably advanced the capabilities of underwater vehicles,critical technical issues remain unresolved.This review first systematically presents the whole picture of deep-sea battery manufacturing,focusing on Li batteries as the current mainstream solution for underwater power.It examines the key aspects of deep-sea Li battery development,including materials selection informed by electro-chemo-mechanics models,component modification and testing,and battery management systems specialized in software and hardware.Finally,it discusses the main challenges limiting the utilization of deep-sea batteries and outlines promising directions for future development.Based on the systematic reflection on deep-sea batteries and discussion on deep-sea Li batteries,this review aims to provide a research foundation for developing underwater power tailored for extreme environmental exploration.
文摘As a typical steel,the fatigue of marine high-strength steels has been emphasized by scholars.In this paper,the fatigue performance and crack growth mechanism of a high-strength steel for ships are investigated by experimental methods.First,the fatigue threshold test and fatigue crack growth rate test of this high-strength steel under different stress ratios were carried out.The influence of stress ratio on the fatigue properties of this steel was analyzed.Secondly,scanning electron microscope was used to analyze the crack growth specimen section of this steel.The crack growth and failure mechanism of this steel were revealed.Finally,based on the above research results,the stress ratio effect of high-strength steel was investigated from the perspectives of crack closure and driving force.Considering the fatigue behavior in the near-threshold stage and the destabilization stage,a fatigue crack growth behavior prediction model of highstrength steel was established.The accuracy of the model was verified by test data.Moreover,the applicability of the modified model to various materials and its excellent predictive ability were verified through comparison with literature data and existing models.
基金supported by the Russian Science Foundation(project 24-75-00072).
文摘The high prevalence of obesity and associated nonalcoholic fatty liver disease(NAFLD)in the population determines the increased interest in identifying molecular targets for regulating the processes underlying these patholo-gies.The search for new endogenous bioregulators of lipid metabolism and their inclusion in therapeutic regimens for the treatment of patients is becoming a potentially promising direction in science and medicine.Oleoylethanolamide(OEA)is an endogenous lipid mediator capable of exerting multiple hypolipidemic,anti-inflammatory,and hepato-protective effects mediated by agonism with receptors of the peroxisome proliferator-activated receptor(PPAR)family(PPAR-αand PPAR-γ).This review focuses on a detailed description of the PPAR-dependent mechanisms of the hepatoprotective activity of OEA in the development of NAFLD.The main attention is paid to such topics as reduction of oxidative stress and inflammation,inhibition of liver fibrogenesis,suppression of hepatocyte death,and changes in various parameters of lipid metabolism.
文摘The problem of ulcerative colitis(UC)is becoming increasingly relevant due to its prevalence and combination with psychological disorders.UC is associated with alterations in the intestinal microbiocenosis as one of the factors reducing tolerance to self-antigens.In addition,patients with UC often experience anxiety,depression and other negative emotional and psychological factors aggravating the course of the underlying disease.The study presented by Wang et al shows that the traditional Chinese medicine Wuling can exert its therapeutic effect by reversing the aberrant precursor of brain-derived neurotrophic factor(BDNF)/BDNF signaling in mice with UC and depression.The combination of Wuling powder with mesalazine can exhibit an antidepressant effect and reduce intestinal inflammation.Undoubtedly,the study by Chinese authors deserves attention,and changes in the balance of precursor of BDNF/p75 neurotrophin receptor/sortilin and BDNF/tropomyosin receptor kinase B signaling may become a novel therapeutic target for clinical treatment and further development of research.
文摘The problem of metabolic dysfunction-associated steatotic liver disease(MASLD)is becoming a non-infectious pandemic,the growth drivers of which are obesity and diabetes mellitus.According to modern concepts,MASLD develops and progresses as a result of the interaction of multiple genetic,environmental and adaptive factors,which include specific genetic polymorphisms(for example,the patatin-like phospholipase domain-containing protein 3 gene)and epigenetic modifications,dietary patterns(for example,high consumption of saturated fats and fructose),physical inactivity,obesity,insulin resistance,dysregulation of adipokine production,lipotoxicity,oxidative stress,intestinal microbiota dysbiosis(small intestinal bacterial overgrowth syndrome).In addition,due to the high infection rate of Helicobacter pylori(up to 80%)of people in the population,the influence of this factor on the development and progression of MASLD cannot be ruled out.Ye et al presented a study investigating the relationship between Helicobacter pylori infection and metabolic dysfunction associated with hepatic steatosis and identified prognostic factors.Certainly,the work of the Chinese authors deserves attention and further study.
文摘The oxygen evolution reaction(OER)is a key process in water splitting for hydrogen production,yet its sluggish kinetics pose significant challenges for catalyst development.In this work,we present the first systematic study on isostructural 2D coordination polymers(CPs)based on 1,10-ferrocenediyl-bis(H-phosphinic)acid,with cobalt,manganese,and cadmium metals as electrocatalysts for OER.These polymers were synthesized via a facile solution reaction,yielding crystalline materials with excellent structural integrity.The electrocatalytic performance of CPs composites,prepared with carbon and phosphonium ionic liquid,was evaluated in 0.1 M KOH using a three-electrode system.Notably,the Co-and Cd-based CPs demonstrated exceptional OER activity,achieving an overpotential as low as 236–255 mV at 10 mA cm^(-2),surpassing those of many previously reported CP-based OER catalysts.Furthermore,these materials exhibited high stability over prolonged electrolysis,maintaining their activity without significant degradation.This work not only introduces a new class of ferrocenyl phosphinatebased CPs as highly active and durable OER catalysts but also provides valuable insights into their structureactivity relationships,paving the way for future advancements in electrocatalysis.
基金the framework of the Project 21T-4C045 of the Higher Education and Science Committee(RA)。
文摘The results of the 2022-2025 study conducted for the vulnerability assessment of pastures and for the development of improvement measures on the degraded land sections in the arid and semi-arid provinces of the Caucasus under the global climate change conditions are introduced in the current article.The main goal of our scientific work is to study and assess the current ecological and resource state of natural phytocenoses,pastures and hayfields in the arid and semi-arid landscapes under climate change.The paper presents the results of determining the areas and levels of degradation of the natural biogeocenoses and biogeocenoses of the pastures and hayfields in the mountain and highland landscapes.The results were obtained using remote sensing,field and laboratory studies and analyses.The conducted studies have revealed that along 34,174.5 ha pasture and 1342.0 meadows areas of the pastures at the Areni,Yeghegis,Yeghegnadzor and Vayq consolidated administrative territories situated in the arid and semi-arid zones of the Vayots Dzor Region high degradation was recorded in about 6508 hectares of pasture and 407 hectares of meadows areas,which is related to irregular and uncontrolled economic mismanagement of the local population and global climate change.To improve the ecological condition,accessibility and quality of ecosystem services of the pastures,hayfields and natural meadows,comprehensive restoration bioecological and agrotechnical measures have been proposed.They are aimed at improving the air,water and nutrient regimes of soils,at their bioprotection,as well as at the general increase in area and at improving the economic characteristics of the vegetation cover.Such measures on the ecosystem basis are appropriate in the context of enriching the qualitative composition of plants with useful ecological and economic bioecological characteristics,taking into account the characteristics of landscapes,weather and climatic conditions,and agricultural opportunities.
基金supported by the Ministry of Science and Higher Education of the Russian Federation in the Framework of State Assignment of PSCBR RAS 075-00609-24-01(No.1022080100047-5-1.6.4,Neuroprotective drugs of a new generation).
文摘Objective:Activation of mitophagy is a promising option to overcome the mitochondrial malfunction that accompanies many diseases.Herein,we investigate the mechanisms underlying the ability of sodium lactate and pyruvate to initiate mitophagy,from the perspective of action on mitochondrial network and expression levels.Methods:Fluorescent and confocal microscopy was used to assess key cell parameters characterizing the state of the mitochondrial network and the level of mitophagy in human fibroblasts carrying mutations in genes encoding LRRK2 and PINK1 after the combined application of lactate and pyruvate and after direct acidification.qRT-PCR was used to study the expression levels of key mitophagy genes.Results:Cells with a mutation in the PINK1 gene showed a lower basal cytosolic pH.The application of sodium lactate and pyruvate to the cells with mutations associated with Parkinson’s disease caused intracellular acidification.Lowering extracellular pH to 6.0 led to a decrease in mitochondrial membrane potential,while the effect of lactate and pyruvate tended to increase this parameter.Extracellular acidification,as well as the effects of lactate and pyruvate,led to an increased level of mitophagy,and also affected such parameters of the mitochondrial network morphology as the ratio of individual to network mitochondria,branch length in mitochondrial network,number of mitochondrial junctions in the network,and also altered the expression of key mitophagy genes.Conclusion:Direct acidification and one induced by lactate and pyruvate do not differ in the efficiency of their effects on the mitochondrial network and mitophagy but change the cell fate differently.The mechanisms of acidification-induced activation of mitophagy differ in control and mutant fibroblasts.
基金This publication presents findings from research conducted under Project No.III-99-24.489Natural Growth Regulators in the Induction of Resistance of Cereal Plants to HeavyMetals(2024-2028)funded by the NationalAcademy of Sciences of Ukraine.
文摘Prolonged lack of rain and high-temperature lead to soil water deficits,inhibiting cereal crop growth in early ontogenesis and reducing grain quality and yield.Rye(Secale cereale L.)is a key grain crop,particularly in regions where wheat cultivation is challenging or unfeasible.To clarify its drought adaptation mechanisms,we analyzed the effects of moderate soil drought on growth,hormonal homeostasis,and the dynamics and distribution of free amino acids and phenolic compounds in rye at early vegetative stages and post-recovery.Drought triggered both general and organ-specific changes in endogenous phytohormones.A nonspecific response involved the accumulation of stress hormones abscisic acid(ABA)and salicylic acid(SA),alongside the suppression of growth hormones indole-3-acetic acid(IAA)and gibberellins.However,hormone dynamics and localization varied across plant organs.ABA and SA levels significantly increased in shoots of drought-stressed and recovered plants,corresponding with inhibited growth.Prolonged drought further enhanced ABA accumulation in both shoots and roots of recovered plants,while SA levels declined in roots but remained elevated in shoots.Drought also caused a substantial reduction in IAA,particularly in shoots,while gibberellins(GA_(3)+GA_(4))significantly decreased in roots.GA_(3)was predominant in most samples,except in the shoots of 2-day-old control plants.Post-recovery,IAA levels increased but remained below control values,while GA_(4)accumulation in roots led to a rise in total gibberellin levels.In contrast,shoot GA_(3)+GA_(4)levels declined,primarily due to GA_(3)reduction.The dominant free amino acids:aspartic acid,glutamic acid,glycine,alanine,and leucinedecreased significantly,underscoring their key role in stress adaptation.Increased flavonoid accumulation,especially in roots,suggests their involvement in antioxidant defense against oxidative stress.A significant increase in ABA and SA levels,along with a marked reduction in IAA and GA content in stressed rye plants occurred alongside a reduction in free amino acid content,accumulation of phenolic compounds,and an increase in flavonoid levels.These findings indicate distinct adaptation strategies in rye shoots and roots undermoderate soil drought.They provide a foundation for further research on drought resistance mechanisms in cereals and the development of strategies to enhance their adaptive potential.
文摘Humans have always engaged with their surroundings and the ecology in which they live.However,during the industrial age,this contact has been more intense and has had a substantial impact on environment and ecosystems.For example,overexploitation of natural resources,mining,pollution,and deforestation are all elements that negatively affect biodiversity and natural resources.Few studies have been conducted to evaluate the damage caused,despite the significant uncontrolled pressure from human activity.However,maintaining its environment is essential to the survival of coastal fishing.Goal:This study’s goal was to evaluate how human activity affected Tabounsou’s coastal ecology in order to suggest remedial actions for sustainable management.The following was the methodological approach used:executive consultation and archival analysis;stakeholder survey(locals,farmers,salt producers,fishers,and loggers);inventory of species;anthropogenic activity inventory;evaluation of how human activity affects aquatic life in the research region;suggestion and action for sustainable management;Outcome:Executive consultation indicated that the main issues are:construction projects that reduce the estuary’s surface area;agricultural practices such as woodcutting and salt farming;the rise in resource exploitation;noncompliance with fisheries laws;and the catching of young fish.Eighty-three percent of fisherman ditch their nets on the coast after using them,but only seventeen percent burn them.With a 75%frequency rate,the same survey indicates that most fisherman fish around the coast.In the Tabounsou area,according to loggers’survey,68%of the wood cut is Rhizophora,24%is Avicennia,and 8%is Laguncularia.Three fish stocks,representing nine families and nine species,were identified by the species inventory.At 18%and 15%,respectively,the actors most frequently capture the species Pseudotolithus elongatus and Arius parkii.According to a poll of 30 farmers,90%of them apply fertilizer to their soil,while only 10%do not.During the dry season,salt is grown.According to two actors,Bougna Toro Toro produces 100 kg of salt per day,followed by Khoumawadé,which produces 80 kg,and Toumbibougni,which produces 70 kg.
基金supported by the National Natural Science Foundation of China(Grant Nos.12372199,12422207,and W2431010)the Natural Science Foundation of Shandong Province of China(Grant No.ZR2021JQ02)the Ningbo Municipal Excellence Research Program(Zhejiang Province,China).
文摘This study presents a new boundary element method(BEM)framework for the numerical solution of general time-dependent or transient problems.By reformulating the time derivative as a domain integral,the framework effectively decouples the treatment of spatial and temporal variables,allowing for the independent application of specialized discretization methods.For the temporal domain,we introduce an innovative time-spectral integration technique,which is based on Gaussian-quadrature-based orthogonal polynomial expansions.This method not only achieves arbitrary orders of accuracy but also significantly enhances computational efficiency and stability,particularly for simulations involving rapid transients or long-time dynamic simulations.The domain integrals in the spatial domain are calculated using the scaled coordinate transformation BEM(SCT-BEM),a mathematically rigorous technique that converts domain integrals into equivalent boundary integrals,preserving the boundary-only discretization advantage inherent in BEM.Numerical experiments on transient heat conduction and dynamic wave propagation further demonstrate the framework’s performance and capabilities.These experiments show that the proposed framework outperforms traditional time-stepping BEM methods,particularly in terms of stability,convergence rates,and computational cost,making it a highly promising tool for practical engineering applications.
基金The formation of coatingsas well as SEM,EDS,FIB,Raman spectroscopy,XRD,XPS,EIS,IR spectra,release studies and antibacterial studies were supported by Russian Science Foundation Grant No 22-73-10149,https://rscf.ru/project/22-73-10149/The wettability studies,all viability tests,alizarin red assay,evaluation of inflammatory activity and adhesion tests were supported by Russian Science Foundation Grant No 23-13-00329,https://rscf.ru/project/23-13-00329/。
文摘Currently,there is an essential need for bioresorbable bone implants with antibacterial,anti-inflammatory properties as well as osteoinductivity.Considering this,in presented study for the first time hybrid Mg-ZK coatings with polydopamine(PDA),menaquinone-7(MK-7),zoledronate(ZA)and vancomycin on the hydroxyapatite(HA)containing layer are formed.Porous coatings were obtained by the plasma electrolytic oxidation(PEO)on an Mg alloy,then MK-7 was impregnated into the pores and PDA film with ZA and vancomycin was polymerized on the samples surface.The presence of HA and organic bioactive compounds was confirmed by EDS,Raman spectroscopy,XRD and XPS.Surface free energy values of hybrid coatings are close to optimal for cell adhesion:75.28±1.35 mJ/m^(2).Viability tests of the medium,in which Mg-ZK implants were soaked,revealed cytotoxic activity on human osteosarcoma cells with no such an effect on fibroblasts.Antibacterial tests showed an inhibition zone on S.aureus with no viable colonies on the hybrid coatings.The growth inhibition zones for the samples with the hybrid coating were 21±1 mm.Data of electrochemical impedance spectroscopy shows increase of corrosion resistance of samples with hybrid coating by 7 times comparing the Mg alloy without a coating.These properties make the hybrid Mg-ZK coating an attractive modification for bone implants.
文摘During strong unsteady flow processes such as cavitation initiation and collapse,the volume changes generated by the materials transformation of cavitation phase transition seriously lag behind the volume evolution formed by the flow process.The phase transition and hydrodynamics are in a non-equilibrium state.A cavitation model that can describe such non-equilibrium phenomena is needed in numerical simulations of cavitation flow.The paper starts from the molecular dynamics’principle of phase change of matter,and based on the Maxwell velocity distribution form of molecular thermal motion,elaborates on the formation process of Hertz Knudsen formula for material exchange at the interface between liquid and vapor.On this basis,using the evolution equation of gas nucleus number density in water and the compressible state equation of vapor,a non-equilibrium cavitation model for phase transition and hydrodynamics is established.The simulation results of a vapor bubble collapse process in the non-equilibrium cavitation model show different behavior from the simulation results of the equilibrium cavitation model.The simulation results of the equilibrium cavitation model show that the vapor bubble collapses once and completely disappear,while the simulation results of the non-equilibrium cavitation model show multiple collapses and rebound,which is agreement with the experimental results of the vapor bubble collapse.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2800600)the National Natural Science Foundation of China(Grant No.52071203).
文摘Polymethyl methacrylate(PMMA)has the advantages of good transparency,corrosion resistance and light weight and can be used as the preferred material for pressure-resistant cabins of fully transparent submersibles.In this study,based on the fracture mechanics method,a calculation method for estimating the residual fatigue life of a PMMA manned cabin is proposed by improving the small-time scale fatigue crack growth rate model.This improved model is verified by the experimental data of the PMMA material.Then,through the Weibull and Gumbel combined distribution functions,the fatigue load spectrum suitable for the fully transparent manned cabin is fitted according to the dive data.A parametric analysis of the residual fatigue life of the fully transparent manned cabin under various initial crack sizes and dwell time is conducted,yielding valuable results.This study aims to increase the safety of fully transparent pressure-resistant cabins and offer insights for fatigue analysis of underwater structures utilizing PMMA materials.
