To evaluate the impact of behavioral restrictions on perinatal care caused by the COVID-19 pandemic, we conducted a questionnaire survey of 1976 medical institutions handling deliveries across Japan. The survey examin...To evaluate the impact of behavioral restrictions on perinatal care caused by the COVID-19 pandemic, we conducted a questionnaire survey of 1976 medical institutions handling deliveries across Japan. The survey examined changes in the number of antenatal checkups due to behavioral restrictions, visit restrictions at medical institutions, and the acceptance of COVID-19-infected pregnant and nursing mothers. An increased burden was observed at delivery hospitals, irrespective of whether they accepted infected pregnant and nursing mothers. Some medical institutions were unable to manage infected pregnant women and transferred them to other facilities, highlighting the need for role-sharing among institutions. The number of antenatal checkups showed a decreasing trend, indicating that the pandemic negatively affected checkup attendance. However, no clear increase in perinatal deaths was observed during the observation period, despite the reduction in the number of checkups.展开更多
Background: Hip osteoarthritis (HOA) causes joint destruction, resulting in hip pain, limited range-of-motion, claudication, and joint deformity. In the conservative treatment of HOA, self-management is important to m...Background: Hip osteoarthritis (HOA) causes joint destruction, resulting in hip pain, limited range-of-motion, claudication, and joint deformity. In the conservative treatment of HOA, self-management is important to manage symptoms and control disease progression. In a previous study, the researchers conducted a conceptual analysis of 43 foreign studies on self-management during conservative therapy for patients with HOA. The results revealed a definition of self-management during conservative therapy for patients with HOA. However, because that study analyzed only the foreign literature, it remains unclear whether the findings reflect the characteristics of the Japanese health-care delivery system, health-care insurance system, or the lifestyles and cultural characteristics of Japanese patients with HOA. Objective: We aimed to clarify the self-management behaviors of patients with HOA. Methods: Semi-structured interviews were conducted with five patients diagnosed with HOA, and the results were subjected to inductive qualitative analysis. Results: Six categories of self-management behaviors were extracted for patients with HOA: [active information gathering about HOA], [personalized pain and weight management, and strategies for reducing hip joint load], [reflection on living conditions with individuals and professionals, and determination for future efforts], [continuation of exercise and weight management based on personal strengths and achievements, and mutual support with others], [coexistence with HOA while managing negative feelings], and [choosing treatment methods by trusting doctors while struggling with personal needs]. Conclusion: These findings suggest the need to develop health guidance and educational programs for patients with HOA that focus on how to prevent disease progression and cope with symptoms.展开更多
This study investigates the prevalence of HIV high-risk behaviors among university students in S City, Sichuan Province. Using a sampling survey method, a total of 3262 valid questionnaires were collected. Data analys...This study investigates the prevalence of HIV high-risk behaviors among university students in S City, Sichuan Province. Using a sampling survey method, a total of 3262 valid questionnaires were collected. Data analysis revealed ten significant issues related to HIV risk behaviors among university students, leading to suggested intervention strategies to address these behaviors.展开更多
Layered rock formations are frequently encountered during the excavation of underground structures. The stability of such structures is influenced not only by the stress concentration caused by the cavities in the str...Layered rock formations are frequently encountered during the excavation of underground structures. The stability of such structures is influenced not only by the stress concentration caused by the cavities in the strata but also by the anisotropy of the layered rock mass. The interaction between them can lead to critical structural failure, such as rupture, collapse, or significant deformation within the adjacent rock mass, thereby jeopardizing operational safety. However, the coupling law and mechanism between the stress concentration resulting from the cavities and the anisotropy of a layered rock mass remain unclear. In this study, a uniaxial compression test was performed on shale specimens containing a circular hole to investigate the effects of layer inclination and circular holes on the mechanical properties, elastic energy storage, and failure behaviors of these specimens. The failure mechanism of the rock surrounding the hole was analyzed on the basis of the single plane of weakness theory and the Kirsch solution. The test results indicated pronounced anisotropy in the compressive strength, elastic modulus, and elastic strain energy of the specimens, with distinct “V”, “M” and “U”-shaped patterns correlated with varying layer inclination angles. In addition, the combined effect of stress concentration and layer inclination resulted in different failure types, which were classified into four groups according to their failure behavior. Theoretical analysis revealed that failure around circular holes in layered rock is affected by a range of variables, such as layer inclination, layer strength, lateral pressure coefficient, azimuth, and loading stress.展开更多
The fall armyworm(Spodoptera frugiperda)is an invasive species and a destructive pest of maize,which significantly impacts native species and communities via complex mechanisms like competition for resources.However,t...The fall armyworm(Spodoptera frugiperda)is an invasive species and a destructive pest of maize,which significantly impacts native species and communities via complex mechanisms like competition for resources.However,the interaction between S.frugiperda and local pests remains unclear.In this study,we determined that Oriental armyworm(Mythimna separata)females with different mating status displayed different approach-avoidance behaviors towards maize which was infested by S.frugiperda larvae.The virgin M.separata females were repelled,while the mated females were attracted by the S.frugiperda-infested maize.To further understand the olfactory mechanism of this phenomenon,seven volatiles induced by S.frugiperda in maize were characterized by gas chromatography and mass spectrometry(GC-MS),including trans-2-hexenal,linalool,trans-β-farnesene,cis-3-hexenyl acetate,β-caryophyllene,trans-α-bergamotene,and isopentyl acetate.Additionally,electrophysiological and behavioral assays of the seven compounds were performed using both virgin and mated females of M.separata.We determined that virgin and mated females displayed different responses to the herbivore-induced plant volatile(HIPV).Trans-β-farnesene was the core compound for repelling virgin females,and trans-2-hexenal was the key attractant for oviposition in mated female M.separata individuals.These findings help our comprehension of the relationships between maize pests and offer new possibilities for controlling them by olfactory-based strategies.展开更多
In the deep geological disposal repository of high-level radioactive waste,buffer/backfill materials typically consist of compacted bentonite block and granular bentonite.As these materials undergo a long-term hydrati...In the deep geological disposal repository of high-level radioactive waste,buffer/backfill materials typically consist of compacted bentonite block and granular bentonite.As these materials undergo a long-term hydration,it is anticipated that the two forms of bentonite materials(i.e.compacted bentonite powder(CBP)and granular bentonite(GB))are expected to exhibit differing hydro-mechanical behaviors due to the differences in their structures.This work aims to investigate the differences in swelling pressure and compressibility through a series of swelling pressure tests,compression tests and mercury intrusion porosimetry(MIP)tests.The experimental results demonstrated that swelling pressure curves of the CBP specimens showed higher first peak values and more pronounced collapse than those of the GB specimens at a given dry density,regardless of vapor-water hydration or liquid-water hydration.The final swelling pressures of the two materials were similar at the same dry density,suggesting an independent correlation between swelling pressure and dry density.At the high suction range,the compression curves exhibited an obvious bi-linear pattern for the CBP specimens and a significant nonlinearity for the GB specimens.Meanwhile,the CBP specimens presented higher pre-consolidation pressures and larger compression indices than the GB specimens at a given suction.As suction decreased,the compression curves of the two materials gradually approached each other and their differences were reduced accordingly.After reaching saturation,a good consistency between them was observed whether for final swelling pressure or compressibility.Pore structure analysis revealed that the two materials both presented an initially double structure,and their differences were primarily manifested at the macrostructural level.Eventually,the differences in swelling pressure or compression curves of the two materials were well interpreted by combining microstructural evolutions.展开更多
Here we complete our work on the asymptotics of Hankel determinants studying the case wherein the entries are “ultrarapidly”-varying functions in the sense that their logarithms are rapidly varying. Moreover, the la...Here we complete our work on the asymptotics of Hankel determinants studying the case wherein the entries are “ultrarapidly”-varying functions in the sense that their logarithms are rapidly varying. Moreover, the last results in the paper highlight analogies between algebraic identities for Hankelians with special entries and asymptotic relations valid for large classes of entries.展开更多
Iodine is widely used in aqueous zinc batteries(ZBs)due to its abundant resources,low cost,and active redox reactions.In addition to the active material in zinc-iodine batteries,iodine also plays an important role in ...Iodine is widely used in aqueous zinc batteries(ZBs)due to its abundant resources,low cost,and active redox reactions.In addition to the active material in zinc-iodine batteries,iodine also plays an important role in other ZBs,such as regulating the electrochemical behavior of zinc ions,promoting the reaction kinetic and reversibility of other redox pairs,catalytic behaviors related to iodine reactions,coupling with other halogen ions,shuttle behaviors of polyiodides,etc.However,there is currently a lack of comprehensive discussion on these aspects.Here,this review provides a comprehensive overview of the electrochemical behaviors of iodide in the aqueous ZBs.The effect of iodine ions on the Zn^(2+)desolvation behaviors and the interfacial behaviors of Zn anode was summarized.Iodine redox pairs boosting other redox pairs,such as MnO_(2)/Mn^(2+)redox pair and vanadium redox pair to obtain high reversibility and capacity was also discussed.Moreover,the catalytic behaviors related to iodine reactions in aqueous ZBs,synergistic reaction with other halogen ions and suppression of shuttle behaviors for high performance zinc-iodine batteries were systematically analyzed.Finally,future prospects for designing effective iodine electrochemical behaviors with practicability are proposed,which will provide scientific guidance for the practical application of iodine-related aqueous ZBs.展开更多
The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control...The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.展开更多
BACKGROUND Depression is a prevalent affective disorder,but its pathophysiology remains unclear.Dysfunction in the gamma-aminobutyric acid(GABA)-ergic system may contribute to its onset.Recently,antidepressants(e.g.,b...BACKGROUND Depression is a prevalent affective disorder,but its pathophysiology remains unclear.Dysfunction in the gamma-aminobutyric acid(GABA)-ergic system may contribute to its onset.Recently,antidepressants(e.g.,brexanolone,zuranolone)targeting the GABA-A receptor were introduced.The zona incerta(ZI),an inhibitory subthalamic region mainly composed of GABAergic neurons,has been implicated in emotional regulation.Deep brain stimulation of the ZI in humans affects anxiety and depression symptoms,while activation of ZI neurons in mice can either worsen or alleviate anxiety.Currently,there is no direct evidence linking GABAergic neurons in the ZI to depression-like behaviors in rodents.AIM To explore the relationship between GABAergic neurons in the ZI and depression-like behaviors in mice.METHODS A chronic restraint stress(CRS)model was utilized to induce depression in mice.Whole-cell patch-clamp recordings assessed the excitability changes of GABAergic neurons in the ZI.Additionally,chemogenetic techniques were employed to modulate ZI GABAergic neurons.The performance of the mice in behavioral tests for depression and anxiety was observed.RESULTS The findings indicated that GABAergic neurons in the ZI were closely associated with depression-like behaviors in mice.Twenty-eight days after the CRS model was established,depression-like and anxiety-like behaviors were observed in the mice.The excitability of GABAergic neurons in the ZI was reduced.Chemogenetic activation of these neurons alleviated CRS-induced depression-like and anxiety-like behaviors.Conversely,inhibition of GABAergic neurons in the ZI led to changes in emotion-related behavioral outcomes in mice.CONCLUSION Activity of GABAergic neurons in the ZI was closely associated with depression-like phenotypes in mice,suggesting that these neurons could be a potential therapeutic target for treating depression.展开更多
This study aims to explore the characteristics of novice teachers’inappropriate behaviors in classroom teaching and their intervention strategies.With the continuous improvement of education quality,novice teachers f...This study aims to explore the characteristics of novice teachers’inappropriate behaviors in classroom teaching and their intervention strategies.With the continuous improvement of education quality,novice teachers face increasing challenges in teaching practice.Their inappropriate behaviors not only affect the classroom atmosphere but may also negatively impact students’learning outcomes.Therefore,researching the characteristics of novice teachers’inappropriate behaviors and their intervention strategies holds significant scientific and social value.This study employs a combination of quantitative and qualitative methods to analyze the behavioral patterns of novice teachers in classroom teaching and proposes corresponding intervention strategies.The results indicate that novice teachers’inappropriate behaviors mainly manifest as poor classroom management,monotonous teaching methods,and insufficient interaction with students.Based on these findings,the study proposes a series of effective intervention strategies,including enhancing teacher training,optimizing teaching design,and promoting positive interactions between teachers and students.The conclusions of the study not only provide practical guidance for educational practice but also point out directions for future research,emphasizing the crucial role of teacher professional development in improving teaching quality.展开更多
Dissolution of soluble soil,biodegradation of municipal solid waste(MSW),and internal erosion of gap-graded soil are typical mass loss processes of geomaterials,which result in various engineering problems.These three...Dissolution of soluble soil,biodegradation of municipal solid waste(MSW),and internal erosion of gap-graded soil are typical mass loss processes of geomaterials,which result in various engineering problems.These three processes are conceptually analogous and examined by a unified assessment of their behaviors considering the initial properties of geomaterials and testing conditions.This study collected additional data from twelve soil dissolution tests and five long-term MSW biodegradation tests.We then established a comprehensive mass loss behavior dataset based on the available studies and the supplementary data obtained from this study.In addition to the flow-reactive fraction,two initial volumetric properties are also critical,which are void ratio before mass loss(esolid,0)and inert-to-reactive size ratio.A characteristic parameter(Λ),describing the ratio between the change in voids volume and the change in flow-reactive solids volume,is correlated with the strain and change in esolid.The volumetric and structural changes of all the flow-reactive geomaterials are categorized into Λ=−1 for pseudo-stable,−1≤Λ<0 for collapsible,0≤Λ<esolid,0 for hyper-collapsible,and Λ≥esolid,0 for readily densified.A three-dimensional plot constructed by the three critical initial properties is divided into eight zones based on the differentΛvalues,which correspond to distinct mass loss behaviors.The a priori Λ estimation and corresponding zonation for a wide variety of flow-reactive geomaterials is shown to be beneficial for research and practice.展开更多
It is important to select suitable organisms to adapt the requirement of different environment monitoring purposes.Following our previous study,the behavioral responses of Daphnia magna and Japanese madaka （Oryzias l...It is important to select suitable organisms to adapt the requirement of different environment monitoring purposes.Following our previous study,the behavioral responses of Daphnia magna and Japanese madaka （Oryzias latipes） were investigated and compared under flow-through conditions in an on-line biomonitoring system.The results showed that both D.magna and Japanese madaka had similar biological clock,but the circadian rhythms of Japanese madaka was more clearly recorded than that of D.magna.And the sensitivity of D.magna was about two orders of magnitudes higher than that of Japanese madaka in different types of toxic chemicals （dichlorovos,deltamethrin and cadmium chloride）.However,when both animals were used in an on-line biomonitoring system,the life span of D.magna was less than 7 days and Japanese madaka could last for more than one month without feeding.Therefore,D.magna was proposed to be a more sensitive bioindicator and was suitable for short term monitoring the pollution events at concentration level closing to the water quality standard,while Japanese madaka was more suitable for the long-term monitoring for accidental discharges.展开更多
The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold s...The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold showed that gel Amberlite IRA-400 resin with Type Ⅰ quaternary ammonium functional group had better adsorption performance.The increases of resin dosage,ammonia concentration and solution pH were favorable to gold adsorption,whereas the rises of cupric and thiosulfate concentrations were disadvantageous to gold loading.Microscopic characterization results indicated that gold was adsorbed in the form of [Au(S_(2)O_(3))_(2)]^(3–) complex anion by exchanging with the counter ion Cl^(–) in the functional group of the resin.Density functional theory calculation result manifested that gold adsorption was mainly depended on the hydrogen bond and van der Waals force generated between O atom in [Au(S_(2)O_(3))_(2)]^(3–) and H atom in the quaternary ammonium functional group of the resin.展开更多
The benefits of using cryogenic liquid nitrogen shock to enhance coal permeability have been confirmed from experimental perspectives.In this paper,we develop a fully coupled thermo-elastic model in combination with t...The benefits of using cryogenic liquid nitrogen shock to enhance coal permeability have been confirmed from experimental perspectives.In this paper,we develop a fully coupled thermo-elastic model in combination with the strain-based isotropic damage theory to uncover the cooling-dominated cracking behaviors through three typical cases,i.e.coal reservoirs containing a wellbore,a primary fracture,and a natural fracture network,respectively.The progressive cracking processes,from thermal fracture initiation,propagation or cessation,deflection,bifurcation to multi-fracture interactions,can be well captured by the numerical model.It is observed that two hierarchical levels of thermal fractures are formed,in which the number of shorter thermal fractures consistently exceeds that of the longer ones.The effects of coal properties related to thermal stress levels and thermal diffusivity on the fracture morphology are quantified by the fracture fractal dimension and the statistical fracture number.The induced fracture morphology is most sensitive to changes in the elastic modulus and thermal expansion coefficient,both of which dominate the complexity of the fracture networks.Coal reservoir candidates with preferred thermal-mechanical properties are also recommended for improving the stimulation effect.Further findings are that there exists a critical injection temperature and a critical in-situ stress difference,above which no thermal fractures would be formed.Preexisting natural fractures with higher density and preferred orientations are also essential for the formation of complex fracture networks.The obtained results can provide some theoretical support for cryogenic fracturing design in coal reservoirs.展开更多
High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Exten...High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Extensive studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural materials.Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials.Recently,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation processes.In this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are discussed.The factors that influence the deformation mechanisms of HEAs are also outlined.This review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress changes.Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.展开更多
The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches....The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches.An improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric region.The symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of constraint.Different motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement sensors.The numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is obtained.The numerical solutions are in good agreement with the experimental results.The nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively analyzed.Due to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.展开更多
In this editorial,I comment on the article“Association of preschool children behavior and emotional problems with the parenting behavior of both parents”which was published in the latest issue of“World Journal of C...In this editorial,I comment on the article“Association of preschool children behavior and emotional problems with the parenting behavior of both parents”which was published in the latest issue of“World Journal of Clinical Cases”that demonstrates the prevalence of behavioral disorders in preschool children.Therefore I am focused on parenting which is the most effective factor shown to affect the development and continuity of these behaviors.The management of child behavior problems is crucial.Children in early ages,especially preschoolers who are in the first 5 years of life,are influenced by dramatic changes in various aspects of development,such as social,emotional,and physical.Also,children experience many changes linked to different developmental tasks,such as discovering themselves,getting new friendships,and adapting to a new environment.In this period,parents have a critical role in supporting child development.If parents do not manage and overcome their child’s misbehavior,it could be transformed into psychosocial problems in adulthood.Parenting is the most powerful predictor in the social development of preschool children.Several studies have shown that to reduce the child’s emotional and behavioral problems,a warm relationship between parents and children is needed.In addition,recent studies have demonstrated significant relationships between family regulation factors and parenting,as well as with child behaviors.展开更多
Polymer-blend geocell sheets(PBGS)have been developed as substitute materials for manufacturing geocells.Various attempts have been made to test and predict the behaviors of commonly used geogrids,geotextiles,geomembr...Polymer-blend geocell sheets(PBGS)have been developed as substitute materials for manufacturing geocells.Various attempts have been made to test and predict the behaviors of commonly used geogrids,geotextiles,geomembranes,and geocells.However,the elastic-viscoplastic behaviors of novel-developed geocell sheets are still poorly understood.Therefore,this paper investigates the elastic-viscoplastic behaviors of PBGS to gain a comprehensive understanding of their mechanical properties.Furthermore,the tensile load-strain history under various loading conditions is simulated by numerical calculation for widespread utilization.To achieve this goal,monotonic loading tests,short-term creep and stress relaxation tests,and multi-load-path tests(also known as arbitrary loading history tests)are performed using a universal testing machine.The results are simulated using the nonlinear three-component(NLTC)model,which consists of three nonlinear components,i.e.a hypo-elastic component,a nonlinear inviscid component,and a nonlinear viscid component.The experimental and numerical results demonstrate that PBGS exhibit significant elastic-viscoplastic behavior that can be accurately predicted by the NLTC model.Moreover,the tensile strain rates significantly influence the tensile load,with higher strain rates resulting in increased tensile loads and more linear load-strain curves.Also,parametric analysis of the rheological characteristics reveals that the initial tensile strain rates have negligible impact on the results.The rate-sensitivity coefficient of PBGS is approximately 0.163,which falls within the typical range observed in most geosynthetics.展开更多
The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an effici...The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ alloy.In ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials.In this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are discussed.The open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are analyzed.The results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ alloy.Moreover,the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed.Under low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb structure.Under high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy surface.Finally,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.展开更多
文摘To evaluate the impact of behavioral restrictions on perinatal care caused by the COVID-19 pandemic, we conducted a questionnaire survey of 1976 medical institutions handling deliveries across Japan. The survey examined changes in the number of antenatal checkups due to behavioral restrictions, visit restrictions at medical institutions, and the acceptance of COVID-19-infected pregnant and nursing mothers. An increased burden was observed at delivery hospitals, irrespective of whether they accepted infected pregnant and nursing mothers. Some medical institutions were unable to manage infected pregnant women and transferred them to other facilities, highlighting the need for role-sharing among institutions. The number of antenatal checkups showed a decreasing trend, indicating that the pandemic negatively affected checkup attendance. However, no clear increase in perinatal deaths was observed during the observation period, despite the reduction in the number of checkups.
文摘Background: Hip osteoarthritis (HOA) causes joint destruction, resulting in hip pain, limited range-of-motion, claudication, and joint deformity. In the conservative treatment of HOA, self-management is important to manage symptoms and control disease progression. In a previous study, the researchers conducted a conceptual analysis of 43 foreign studies on self-management during conservative therapy for patients with HOA. The results revealed a definition of self-management during conservative therapy for patients with HOA. However, because that study analyzed only the foreign literature, it remains unclear whether the findings reflect the characteristics of the Japanese health-care delivery system, health-care insurance system, or the lifestyles and cultural characteristics of Japanese patients with HOA. Objective: We aimed to clarify the self-management behaviors of patients with HOA. Methods: Semi-structured interviews were conducted with five patients diagnosed with HOA, and the results were subjected to inductive qualitative analysis. Results: Six categories of self-management behaviors were extracted for patients with HOA: [active information gathering about HOA], [personalized pain and weight management, and strategies for reducing hip joint load], [reflection on living conditions with individuals and professionals, and determination for future efforts], [continuation of exercise and weight management based on personal strengths and achievements, and mutual support with others], [coexistence with HOA while managing negative feelings], and [choosing treatment methods by trusting doctors while struggling with personal needs]. Conclusion: These findings suggest the need to develop health guidance and educational programs for patients with HOA that focus on how to prevent disease progression and cope with symptoms.
文摘This study investigates the prevalence of HIV high-risk behaviors among university students in S City, Sichuan Province. Using a sampling survey method, a total of 3262 valid questionnaires were collected. Data analysis revealed ten significant issues related to HIV risk behaviors among university students, leading to suggested intervention strategies to address these behaviors.
基金supported by Beijing Natural Science Foundation of China(Grant No.2244099)the China Postdoctoral Science Foundation(Grant No.2023T0025)the National Natural Science Foundation of China(Grant No.52074020).
文摘Layered rock formations are frequently encountered during the excavation of underground structures. The stability of such structures is influenced not only by the stress concentration caused by the cavities in the strata but also by the anisotropy of the layered rock mass. The interaction between them can lead to critical structural failure, such as rupture, collapse, or significant deformation within the adjacent rock mass, thereby jeopardizing operational safety. However, the coupling law and mechanism between the stress concentration resulting from the cavities and the anisotropy of a layered rock mass remain unclear. In this study, a uniaxial compression test was performed on shale specimens containing a circular hole to investigate the effects of layer inclination and circular holes on the mechanical properties, elastic energy storage, and failure behaviors of these specimens. The failure mechanism of the rock surrounding the hole was analyzed on the basis of the single plane of weakness theory and the Kirsch solution. The test results indicated pronounced anisotropy in the compressive strength, elastic modulus, and elastic strain energy of the specimens, with distinct “V”, “M” and “U”-shaped patterns correlated with varying layer inclination angles. In addition, the combined effect of stress concentration and layer inclination resulted in different failure types, which were classified into four groups according to their failure behavior. Theoretical analysis revealed that failure around circular holes in layered rock is affected by a range of variables, such as layer inclination, layer strength, lateral pressure coefficient, azimuth, and loading stress.
基金supported by the National Key Research and Development Program of China(2021YFD1400700)the Natural Science Foundation of Anhui Province,China(2308085MC89)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(ASTIP)。
文摘The fall armyworm(Spodoptera frugiperda)is an invasive species and a destructive pest of maize,which significantly impacts native species and communities via complex mechanisms like competition for resources.However,the interaction between S.frugiperda and local pests remains unclear.In this study,we determined that Oriental armyworm(Mythimna separata)females with different mating status displayed different approach-avoidance behaviors towards maize which was infested by S.frugiperda larvae.The virgin M.separata females were repelled,while the mated females were attracted by the S.frugiperda-infested maize.To further understand the olfactory mechanism of this phenomenon,seven volatiles induced by S.frugiperda in maize were characterized by gas chromatography and mass spectrometry(GC-MS),including trans-2-hexenal,linalool,trans-β-farnesene,cis-3-hexenyl acetate,β-caryophyllene,trans-α-bergamotene,and isopentyl acetate.Additionally,electrophysiological and behavioral assays of the seven compounds were performed using both virgin and mated females of M.separata.We determined that virgin and mated females displayed different responses to the herbivore-induced plant volatile(HIPV).Trans-β-farnesene was the core compound for repelling virgin females,and trans-2-hexenal was the key attractant for oviposition in mated female M.separata individuals.These findings help our comprehension of the relationships between maize pests and offer new possibilities for controlling them by olfactory-based strategies.
基金funded by the National Natural Science Foundation of China(Grant Nos.42207227)the Natural Science Foundation of Hunan Province,China(Grant No.2022JJ40586)The authors also thank the China Postdoctoral Science Foundation(Grant Nos.2022M722428).
文摘In the deep geological disposal repository of high-level radioactive waste,buffer/backfill materials typically consist of compacted bentonite block and granular bentonite.As these materials undergo a long-term hydration,it is anticipated that the two forms of bentonite materials(i.e.compacted bentonite powder(CBP)and granular bentonite(GB))are expected to exhibit differing hydro-mechanical behaviors due to the differences in their structures.This work aims to investigate the differences in swelling pressure and compressibility through a series of swelling pressure tests,compression tests and mercury intrusion porosimetry(MIP)tests.The experimental results demonstrated that swelling pressure curves of the CBP specimens showed higher first peak values and more pronounced collapse than those of the GB specimens at a given dry density,regardless of vapor-water hydration or liquid-water hydration.The final swelling pressures of the two materials were similar at the same dry density,suggesting an independent correlation between swelling pressure and dry density.At the high suction range,the compression curves exhibited an obvious bi-linear pattern for the CBP specimens and a significant nonlinearity for the GB specimens.Meanwhile,the CBP specimens presented higher pre-consolidation pressures and larger compression indices than the GB specimens at a given suction.As suction decreased,the compression curves of the two materials gradually approached each other and their differences were reduced accordingly.After reaching saturation,a good consistency between them was observed whether for final swelling pressure or compressibility.Pore structure analysis revealed that the two materials both presented an initially double structure,and their differences were primarily manifested at the macrostructural level.Eventually,the differences in swelling pressure or compression curves of the two materials were well interpreted by combining microstructural evolutions.
文摘Here we complete our work on the asymptotics of Hankel determinants studying the case wherein the entries are “ultrarapidly”-varying functions in the sense that their logarithms are rapidly varying. Moreover, the last results in the paper highlight analogies between algebraic identities for Hankelians with special entries and asymptotic relations valid for large classes of entries.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2023D01C168)Scientific Research Program of the Higher Education Institution of Xinjiang(Grant No.XJEDU2022P001)+1 种基金Autonomous Region"Tianchi Talent"Introduction Program Youth Doctoral Program(Grant No.51052401544)Tianshan Innovation Team Program of Xinjiang Uygur Autonomous Region(Grant No.2023D14001).
文摘Iodine is widely used in aqueous zinc batteries(ZBs)due to its abundant resources,low cost,and active redox reactions.In addition to the active material in zinc-iodine batteries,iodine also plays an important role in other ZBs,such as regulating the electrochemical behavior of zinc ions,promoting the reaction kinetic and reversibility of other redox pairs,catalytic behaviors related to iodine reactions,coupling with other halogen ions,shuttle behaviors of polyiodides,etc.However,there is currently a lack of comprehensive discussion on these aspects.Here,this review provides a comprehensive overview of the electrochemical behaviors of iodide in the aqueous ZBs.The effect of iodine ions on the Zn^(2+)desolvation behaviors and the interfacial behaviors of Zn anode was summarized.Iodine redox pairs boosting other redox pairs,such as MnO_(2)/Mn^(2+)redox pair and vanadium redox pair to obtain high reversibility and capacity was also discussed.Moreover,the catalytic behaviors related to iodine reactions in aqueous ZBs,synergistic reaction with other halogen ions and suppression of shuttle behaviors for high performance zinc-iodine batteries were systematically analyzed.Finally,future prospects for designing effective iodine electrochemical behaviors with practicability are proposed,which will provide scientific guidance for the practical application of iodine-related aqueous ZBs.
基金financial support from the National Natural Science Foundation of China(Grant No.41941018).
文摘The impacts of natural boulders carried by debris flows pose serious risks to the safety and reliability of structures and buildings.Natural boulders can be highly random and unpredictable.Consequently,boulder control during debris flows is crucial but difficult.Herein,an eco-friendly control system featuring anchoring natural boulders(NBs)with(negative Poisson's ratio)NPR anchor cables is proposed to form an NB-NPR baffle.A series of flume experiments are conducted to verify the effect of NB-NPR baffles on controlling debris flow impact.The deployment of NB-NPR baffles substantially influences the kinematic behavior of a debris flow,primarily in the form of changes in the depositional properties and impact intensities.The results show that the NB-NPR baffle matrix successfully controls boulder mobility and exhibits positive feedback on solid particle deposition.The NB-NPR baffle group exhibits a reduction in peak impact force ranging from 29%to 79%compared to that of the control group in the basic experiment.The NPR anchor cables play a significant role in the NB-NPR baffle by demonstrating particular characteristics,including consistent resistance,large deformation,and substantial energy absorption.The NB-NPR baffle innovatively utilizes the natural boulders in a debris flow gully by converting destructive boulders into constructive boulders.Overall,this research serves as a basis for future field experiments and applications.
基金Supported by the Natural Science Foundation of Xiaogan,China,No.XGKJ2023010036.
文摘BACKGROUND Depression is a prevalent affective disorder,but its pathophysiology remains unclear.Dysfunction in the gamma-aminobutyric acid(GABA)-ergic system may contribute to its onset.Recently,antidepressants(e.g.,brexanolone,zuranolone)targeting the GABA-A receptor were introduced.The zona incerta(ZI),an inhibitory subthalamic region mainly composed of GABAergic neurons,has been implicated in emotional regulation.Deep brain stimulation of the ZI in humans affects anxiety and depression symptoms,while activation of ZI neurons in mice can either worsen or alleviate anxiety.Currently,there is no direct evidence linking GABAergic neurons in the ZI to depression-like behaviors in rodents.AIM To explore the relationship between GABAergic neurons in the ZI and depression-like behaviors in mice.METHODS A chronic restraint stress(CRS)model was utilized to induce depression in mice.Whole-cell patch-clamp recordings assessed the excitability changes of GABAergic neurons in the ZI.Additionally,chemogenetic techniques were employed to modulate ZI GABAergic neurons.The performance of the mice in behavioral tests for depression and anxiety was observed.RESULTS The findings indicated that GABAergic neurons in the ZI were closely associated with depression-like behaviors in mice.Twenty-eight days after the CRS model was established,depression-like and anxiety-like behaviors were observed in the mice.The excitability of GABAergic neurons in the ZI was reduced.Chemogenetic activation of these neurons alleviated CRS-induced depression-like and anxiety-like behaviors.Conversely,inhibition of GABAergic neurons in the ZI led to changes in emotion-related behavioral outcomes in mice.CONCLUSION Activity of GABAergic neurons in the ZI was closely associated with depression-like phenotypes in mice,suggesting that these neurons could be a potential therapeutic target for treating depression.
文摘This study aims to explore the characteristics of novice teachers’inappropriate behaviors in classroom teaching and their intervention strategies.With the continuous improvement of education quality,novice teachers face increasing challenges in teaching practice.Their inappropriate behaviors not only affect the classroom atmosphere but may also negatively impact students’learning outcomes.Therefore,researching the characteristics of novice teachers’inappropriate behaviors and their intervention strategies holds significant scientific and social value.This study employs a combination of quantitative and qualitative methods to analyze the behavioral patterns of novice teachers in classroom teaching and proposes corresponding intervention strategies.The results indicate that novice teachers’inappropriate behaviors mainly manifest as poor classroom management,monotonous teaching methods,and insufficient interaction with students.Based on these findings,the study proposes a series of effective intervention strategies,including enhancing teacher training,optimizing teaching design,and promoting positive interactions between teachers and students.The conclusions of the study not only provide practical guidance for educational practice but also point out directions for future research,emphasizing the crucial role of teacher professional development in improving teaching quality.
基金Nanyang Technological University(NTU,Singapore)and Nanyang Environment and Water Research Institute for the financial support and scholarships of this research.
文摘Dissolution of soluble soil,biodegradation of municipal solid waste(MSW),and internal erosion of gap-graded soil are typical mass loss processes of geomaterials,which result in various engineering problems.These three processes are conceptually analogous and examined by a unified assessment of their behaviors considering the initial properties of geomaterials and testing conditions.This study collected additional data from twelve soil dissolution tests and five long-term MSW biodegradation tests.We then established a comprehensive mass loss behavior dataset based on the available studies and the supplementary data obtained from this study.In addition to the flow-reactive fraction,two initial volumetric properties are also critical,which are void ratio before mass loss(esolid,0)and inert-to-reactive size ratio.A characteristic parameter(Λ),describing the ratio between the change in voids volume and the change in flow-reactive solids volume,is correlated with the strain and change in esolid.The volumetric and structural changes of all the flow-reactive geomaterials are categorized into Λ=−1 for pseudo-stable,−1≤Λ<0 for collapsible,0≤Λ<esolid,0 for hyper-collapsible,and Λ≥esolid,0 for readily densified.A three-dimensional plot constructed by the three critical initial properties is divided into eight zones based on the differentΛvalues,which correspond to distinct mass loss behaviors.The a priori Λ estimation and corresponding zonation for a wide variety of flow-reactive geomaterials is shown to be beneficial for research and practice.
基金supported by the National Key Program for Water Pollution Control (No. 2009ZX07210-009,2009ZX07209-005,2009ZX07527-002)the State Key Laboratory of Environmental Aquatic Chemistry (No.08K07ESPCR)
文摘It is important to select suitable organisms to adapt the requirement of different environment monitoring purposes.Following our previous study,the behavioral responses of Daphnia magna and Japanese madaka （Oryzias latipes） were investigated and compared under flow-through conditions in an on-line biomonitoring system.The results showed that both D.magna and Japanese madaka had similar biological clock,but the circadian rhythms of Japanese madaka was more clearly recorded than that of D.magna.And the sensitivity of D.magna was about two orders of magnitudes higher than that of Japanese madaka in different types of toxic chemicals （dichlorovos,deltamethrin and cadmium chloride）.However,when both animals were used in an on-line biomonitoring system,the life span of D.magna was less than 7 days and Japanese madaka could last for more than one month without feeding.Therefore,D.magna was proposed to be a more sensitive bioindicator and was suitable for short term monitoring the pollution events at concentration level closing to the water quality standard,while Japanese madaka was more suitable for the long-term monitoring for accidental discharges.
基金the financial support from the Natural Science Foundation of Hunan Province, China (No. 2023JJ40723)China Postdoctoral Science Foundation (No. 2022M723549)the National Natural Science Foundation of China (Nos. 52174271, 51504293)。
文摘The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold showed that gel Amberlite IRA-400 resin with Type Ⅰ quaternary ammonium functional group had better adsorption performance.The increases of resin dosage,ammonia concentration and solution pH were favorable to gold adsorption,whereas the rises of cupric and thiosulfate concentrations were disadvantageous to gold loading.Microscopic characterization results indicated that gold was adsorbed in the form of [Au(S_(2)O_(3))_(2)]^(3–) complex anion by exchanging with the counter ion Cl^(–) in the functional group of the resin.Density functional theory calculation result manifested that gold adsorption was mainly depended on the hydrogen bond and van der Waals force generated between O atom in [Au(S_(2)O_(3))_(2)]^(3–) and H atom in the quaternary ammonium functional group of the resin.
基金funding support from the Natural Science Foundation of Sichuan,China(Grant No.2022NSFSC1227)the National Natural Science Foundation of China(Grant Nos.U1762216 and 51574270).
文摘The benefits of using cryogenic liquid nitrogen shock to enhance coal permeability have been confirmed from experimental perspectives.In this paper,we develop a fully coupled thermo-elastic model in combination with the strain-based isotropic damage theory to uncover the cooling-dominated cracking behaviors through three typical cases,i.e.coal reservoirs containing a wellbore,a primary fracture,and a natural fracture network,respectively.The progressive cracking processes,from thermal fracture initiation,propagation or cessation,deflection,bifurcation to multi-fracture interactions,can be well captured by the numerical model.It is observed that two hierarchical levels of thermal fractures are formed,in which the number of shorter thermal fractures consistently exceeds that of the longer ones.The effects of coal properties related to thermal stress levels and thermal diffusivity on the fracture morphology are quantified by the fracture fractal dimension and the statistical fracture number.The induced fracture morphology is most sensitive to changes in the elastic modulus and thermal expansion coefficient,both of which dominate the complexity of the fracture networks.Coal reservoir candidates with preferred thermal-mechanical properties are also recommended for improving the stimulation effect.Further findings are that there exists a critical injection temperature and a critical in-situ stress difference,above which no thermal fractures would be formed.Preexisting natural fractures with higher density and preferred orientations are also essential for the formation of complex fracture networks.The obtained results can provide some theoretical support for cryogenic fracturing design in coal reservoirs.
基金supported by the National Natural Science Foundation of China(Nos.52171098 and 51921001)the State Key Laboratory for Advanced Metals and Materials(No.2022Z-02)+1 种基金the National High-level Personnel of Special Support Program(No.ZYZZ2021001)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-20-03C2 and FRF-BD-20-02B).
文摘High-entropy alloys(HEAs)possess outstanding features such as corrosion resistance,irradiation resistance,and good mechan-ical properties.A few HEAs have found applications in the fields of aerospace and defense.Extensive studies on the deformation mech-anisms of HEAs can guide microstructure control and toughness design,which is vital for understanding and studying state-of-the-art structural materials.Synchrotron X-ray and neutron diffraction are necessary techniques for materials science research,especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information on materials.Recently,several re-searchers have applied synchrotron X-ray and neutron diffraction methods to study the deformation mechanisms,phase transformations,stress behaviors,and in situ processes of HEAs,such as variable-temperature,high-pressure,and hydrogenation processes.In this review,the principles and development of synchrotron X-ray and neutron diffraction are presented,and their applications in the deformation mechanisms of HEAs are discussed.The factors that influence the deformation mechanisms of HEAs are also outlined.This review fo-cuses on the microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation and the application of synchrotron X-ray and neutron diffraction methods to the characterization of dislocations,stacking faults,twins,phases,and intergrain/interphase stress changes.Perspectives on future developments of synchrotron X-ray and neutron diffraction and on research directions on the deformation mechanisms of novel metals are discussed.
基金Project supported by the National Natural Science Foundation of China(Nos.11832002 and 12072201)。
文摘The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches.An improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric region.The symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of constraint.Different motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement sensors.The numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is obtained.The numerical solutions are in good agreement with the experimental results.The nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively analyzed.Due to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.
基金the main study who are focused on parenting style and preschoolers'behavioral problems and give an opportunity to me to comment on this issue.
文摘In this editorial,I comment on the article“Association of preschool children behavior and emotional problems with the parenting behavior of both parents”which was published in the latest issue of“World Journal of Clinical Cases”that demonstrates the prevalence of behavioral disorders in preschool children.Therefore I am focused on parenting which is the most effective factor shown to affect the development and continuity of these behaviors.The management of child behavior problems is crucial.Children in early ages,especially preschoolers who are in the first 5 years of life,are influenced by dramatic changes in various aspects of development,such as social,emotional,and physical.Also,children experience many changes linked to different developmental tasks,such as discovering themselves,getting new friendships,and adapting to a new environment.In this period,parents have a critical role in supporting child development.If parents do not manage and overcome their child’s misbehavior,it could be transformed into psychosocial problems in adulthood.Parenting is the most powerful predictor in the social development of preschool children.Several studies have shown that to reduce the child’s emotional and behavioral problems,a warm relationship between parents and children is needed.In addition,recent studies have demonstrated significant relationships between family regulation factors and parenting,as well as with child behaviors.
基金supported by the National Natural Science Foundation of China(Grant Nos.42077262 and 42077261)the Research Fund Project of Xinjiang Transportation Planning Survey and Design Institute Co.,Ltd.(Grant No.KY2022042504).
文摘Polymer-blend geocell sheets(PBGS)have been developed as substitute materials for manufacturing geocells.Various attempts have been made to test and predict the behaviors of commonly used geogrids,geotextiles,geomembranes,and geocells.However,the elastic-viscoplastic behaviors of novel-developed geocell sheets are still poorly understood.Therefore,this paper investigates the elastic-viscoplastic behaviors of PBGS to gain a comprehensive understanding of their mechanical properties.Furthermore,the tensile load-strain history under various loading conditions is simulated by numerical calculation for widespread utilization.To achieve this goal,monotonic loading tests,short-term creep and stress relaxation tests,and multi-load-path tests(also known as arbitrary loading history tests)are performed using a universal testing machine.The results are simulated using the nonlinear three-component(NLTC)model,which consists of three nonlinear components,i.e.a hypo-elastic component,a nonlinear inviscid component,and a nonlinear viscid component.The experimental and numerical results demonstrate that PBGS exhibit significant elastic-viscoplastic behavior that can be accurately predicted by the NLTC model.Moreover,the tensile strain rates significantly influence the tensile load,with higher strain rates resulting in increased tensile loads and more linear load-strain curves.Also,parametric analysis of the rheological characteristics reveals that the initial tensile strain rates have negligible impact on the results.The rate-sensitivity coefficient of PBGS is approximately 0.163,which falls within the typical range observed in most geosynthetics.
基金supported by the National Natural Science Foundation of China(No.92160301)the Industrial Technology Development Program,China(No.JCKY2021605 B026)。
文摘The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ alloy.In ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials.In this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are discussed.The open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are analyzed.The results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ alloy.Moreover,the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed.Under low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb structure.Under high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy surface.Finally,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.
