The buckling behavior of stiffened panels is significantly influenced by material and geometric defects,making it a critical factor in ensuring structural integrity and safety.These panels are widely used in mechanica...The buckling behavior of stiffened panels is significantly influenced by material and geometric defects,making it a critical factor in ensuring structural integrity and safety.These panels are widely used in mechanical,aerospace,marine,and civil engineering applications due to their ability to enhance bending stiffness with minimal additional weight.Under high loads or stress concentrations,localized structural failures can initiate global buckling in stiffened panels.This study investigates how such defects affect the critical buckling load,stiffness,and thickness of stiffened panels.Two finite element analyses were conducted:a linear analysis to identify the initial buckling mode and a nonlinear analysis using the Riks algorithm in Abaqus CAE,incorporating localized imperfections.The simulations show that material and geometric defects can reduce buckling resistance depending on their severity.展开更多
BACKGROUND Solid pseudopapillary neoplasm(SPN)of the pancreas is a rare epithelial tumor that primarily affects young women.Since the condition is often asymptomatic or presents with non-specific symptoms,its diagnosi...BACKGROUND Solid pseudopapillary neoplasm(SPN)of the pancreas is a rare epithelial tumor that primarily affects young women.Since the condition is often asymptomatic or presents with non-specific symptoms,its diagnosis can be difficult.CASE SUMMARY This report details the case of a 15-year-old girl who presented with a 2-year history of abdominal pain,with no significant findings during physical examination.Abdominal ultrasound revealed a well-defined heterogeneous solidcystic mass in the epigastric region,likely originating from the tail of the pancreas.A subsequent contrast-enhanced computed tomography scan indicated a welldefined cystic lesion with an enhancing solid component and capsule in the tail of the pancreas,suggestive of a cystic neoplasm.The patient underwent an open distal pancreatectomy with splenectomy,and histopathological analysis confirmed the diagnosis of SPN of the pancreas.CONCLUSION This case highlights the risk of SPN in adolescent girls and the necessity of early diagnosis and intervention for better outcomes.展开更多
A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).Th...A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.展开更多
This study investigates the physical properties of the rare earth XFes(X=Sm,Dy,or Nd)materials.Our analysis encompasses these compounds'structural,electronic,thermodynamic,and optical characteristics using density...This study investigates the physical properties of the rare earth XFes(X=Sm,Dy,or Nd)materials.Our analysis encompasses these compounds'structural,electronic,thermodynamic,and optical characteristics using density functional theory(DFT)as implemented in the Wien2k software package.The GGA+SOC+U method was employed to determine the exchange-correlation potential.Our results show that the XFes materials exhibit metallic behavior and exhibit ferromagnetic(FM)phases.Notably,our optical analysis reveals a strong absorption response in the UV region,with characteristic absorption curves and peak intensities varying across the different materials.We also investigated the thermodynamic properties of the materials,finding that the entropy increases exponentially with temperature as the materials transition from a ground state to a more disordered and amorphous state.Our thermodynamic results show that the Debye temperature decreases for all three materials,with DyFes exhibiting the highest Debye temperature at 0 K(307 K),followed by NdFes(298 K),and then SmFes(288 K).This indicates that each material has a unique thermal energy barrier to overcome before vibrations occur.As the temperature increases,the Debye temperature decreases,reflecting a decrease in the thermal energy required to induce vibrations.The differences in Debye temperature values between the three materials may suggest differences in their lattice structures or phonon properties,highlighting the importance of understanding these thermal properties for developing new materials and technologies.展开更多
We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-ly...We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.展开更多
This paper addresses the evolution problem governed by the fractional sweeping process with prox-regular nonconvex constraints.The values of the moving set are time and state-dependent.The aim is to illustrate how a f...This paper addresses the evolution problem governed by the fractional sweeping process with prox-regular nonconvex constraints.The values of the moving set are time and state-dependent.The aim is to illustrate how a fixed point method can establish an existence theorem for this fractional nonlinear evolution problem.By combining Schauder’s fixed point theorem with a well-posedness theorem when the set C is independent of the state u(i.e.C:=C(t),as presented in[22,23]),we prove the existence of a solution to our quasi-variational fractional sweeping process in infinite-dimensional Hilbert spaces.Similar to the conventional state-dependent sweeping process,achieving this result requires a condition on the size of the Lipschitz constant of the moving set relative to the state.展开更多
This study evaluates the impact of heavy metals(zinc,copper and cadmium)on the development and metabolic responses of the maize(Zea mays)variety“Torro Plus”.Seeds were cultivated on MS medium enriched with progressi...This study evaluates the impact of heavy metals(zinc,copper and cadmium)on the development and metabolic responses of the maize(Zea mays)variety“Torro Plus”.Seeds were cultivated on MS medium enriched with progressively higher concentrations of heavy metals(50,100 and 150μM),and plants were analyzed after 21 days.The results show a significant reduction in morphological parameters,notably an 87.28%decrease in the fresh weight of aerial parts and a 69.93%decrease in the fresh weight of roots under 150μM of Cd.Chlorophyll a,b and total content also decreased drastically,reaching a maximum reduction of 74.31%under Cd(150μM).In contrast,secondary metabolites such as proline and flavonoids increased,with a maximum proline accumulation of 0.71 mg/g under Cu(150μM)and a flavonoid concentration reaching 176.33 mg/g under Cu(100μM).These results show mechanisms of adaptation to stress,notably the accumulation of flavonoids and proline,while highlighting the increased toxicity of cadmium at high doses.These data are promising for applications in phytoremediation and sustainable agriculture.This study provides important data on the physiological and biochemical responses of plants to heavy metals and opens up prospects for phytoremediation applications.展开更多
In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light ...In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).展开更多
Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow o...Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.展开更多
Unlike primary metabolites,secondary metabolites serve critical ecological functions,including plant protection,stress tolerance,and symbiosis.This review focuses on extracting,separating,and identifying the major cla...Unlike primary metabolites,secondary metabolites serve critical ecological functions,including plant protection,stress tolerance,and symbiosis.This review focuses on extracting,separating,and identifying the major classes of secondary metabolites,including alkaloids,terpenoids,phenolics,glycosides,saponins,and coumarins.It describes optimized methods regarding plant selection,extraction by solvents,and purification of the metabolites,highlighting the latest advancements in chromatographic and spectroscopic techniques.The review also describes some of the most important problems,such as the instability of the compounds or diversity of the structures,and discusses emerging technologies that solve these issues.Moreover,it examines the secondary roles of these metabolites in medicine,such as anticancer and antimicrobial drugs,sustainable agriculture biopesticides,and environmental ecology-also known as allelopathy and bioindicators.It combines traditional ethnobotanical approaches with contem-porary science,demonstrating the vital need to protect biodiversity in key ecosystems such as tropical rainforests,mountain regions,coral reefs,and arid zones as a foundation for anticipatory bio-discoveries.It organizes the methodological frameworks and outlines the steps needed to enhance the extraction of bioactive compounds from natural sources.展开更多
Magnesium(Mg)alloys are widely used for temporary bone implants due to their favorable biodegradability,cytocompatibility,hemocompatibility,and close mechanical properties to bone.However,rapid degradation and inadequ...Magnesium(Mg)alloys are widely used for temporary bone implants due to their favorable biodegradability,cytocompatibility,hemocompatibility,and close mechanical properties to bone.However,rapid degradation and inadequate strength limit their applicability.To overcome this,the direct current magnetron sputtering technique is employed for surface coating in Mg-based alloys using various zirconium(Zr)content.This approach presents a promising strategy for simultaneously improving corrosion resistance,maintaining biocompatibility,and enhancing strength without compromising osseointegration.By leveraging Mg’s inherent biodegradability,it has the potential to minimize the need for secondary surgeries,thereby reducing costs and resources.This paper is a systematic study aimed at understanding the corrosion mechanisms of Mg–Zr coatings,denoted Mg-xZr(x=0–5 at.%).Zr-doped coatings exhibited columnar growth leading to denser and refined structures with increasing Zr content.XRD analysis confirmed the presence of the Mg(00.2)basal plane,shifting towards higher angles(1.15°)with 5 at.%Zr doping due to lattice parameter changes(i.e.,decrease and increase of“c”and“a”lattice parameters,respectively).Mg–Zr coatings exhibited“liquidphilic”behavior,while Young’s modulus retained a steady value around 80 GPa across all samples.However,the hardness has significantly improved across all samples’coating,reaching the highest value of(2.2±0.3)GPa for 5 at.%Zr.Electrochemical testing in simulated body fluid(SBF)at 37℃ revealed a significant enhancement in corrosion resistance for Mg–Zr coatings containing 1.0–3.4 at.%Zr.Compared with the 5 at.%Zr coating which exhibited a corrosion rate of 32 mm/year,these coatings displayed lower corrosion rates,ranging from 1 to 12 mm/year.This synergistic enhancement in mechanical properties and corrosion resistance,achieved with 2.0–3.4 at.%Zr,suggests potential ability for reducing stress shielding and controlled degradation performance,and consequently,promising functional biodegradable materials for temporary bone implants.展开更多
Scalp necrosis is uncommon in malnourished children,yet temporal catheterization is frequently observed in pediatric hospital settings.The condition is characterized by a black,hard,and unresponsive scalp.Etiologies s...Scalp necrosis is uncommon in malnourished children,yet temporal catheterization is frequently observed in pediatric hospital settings.The condition is characterized by a black,hard,and unresponsive scalp.Etiologies such as temporal arteritis,burns,and Takayasu’s disease,have been proposed.There is a decline in the use of peripheral catheter monitoring in hospitals.War-related food shortages and social instability significantly affect the trauma and risks that undermine the health,social,and psychological well-being of children.This report describes the case of a 5-month-old infant suffering from severe acute malnutrition following the abduction and subsequent release of his mother by armed individuals after one and a half weeks.The infant,who underwent temporal catheterization for medication administration,presented with extensive scalp necrosis.The necrotic tissue was surgically removed,and the malnutrition was successfully treated,resulting in a favorable clinical outcome.The mother received comprehensive mother-child care from a psychologist.展开更多
The current study presents for the first time the preparation of a NiAl(68%(mass)Ni)intermetallic compound through the induction heating technique as a cathode for alkaline water electrolysis.The high-purity target wa...The current study presents for the first time the preparation of a NiAl(68%(mass)Ni)intermetallic compound through the induction heating technique as a cathode for alkaline water electrolysis.The high-purity target was confirmed by X-ray diffraction and scanning electron microscopy combined with energy dispersive X-ray analysis.The chemical activation of Al from the NiAl electrode was achieved in a 25%NaOH solution at 353 K for 72 h.The performance and stability tests in a 1 mol·L^(-1)KOH solution at 298 K demonstrated that the enhancement of the hydrogen evolution reactionwas 13 times higher in the activated NiAl electrode than in the non-activated NiAl electrode.In addition,the electrochemical tests showed that the activated NiAl electrode exhibited the best hydrogen evolution reaction performance.Based on the findings,it is believed that the induction heating technique is a promising route for preparing a highly active and cost-effective NiAl electrode for green hydrogen production.展开更多
Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore d...Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by SiO_(2)+Fe_(2)O_(3)(97.1 to 99.84 wt%),with low concentrations of clastic elements e.g.,Al_(2)O_(3),TiO_(2),and HFSE,depicting a nearly pure chemical precipitate.The REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising environment.The^(87)Sr/^(86)Sr ratios of the BIF are higher than the maximum^(87)Sr/^(86)Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicating involvement of continentally-derived components during BIF formation and alteration.TheƐ_(Nd)(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 Ga.The variable and diverse O and H isotope data(−1.9‰to 17.3‰and−57‰to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric fluids.Mass balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of>2.67 and SiO_(2)depletion factor of>0.99.This is associated with an overall volume reduction of 28.27%,reflecting net leaching and volume collapse of the BIF protholith.展开更多
In our study of super quantum discord between two excitonic qubits inside a coupled semiconductor quantum dots system,our primary focus is to uncover the impact of weak measurement on its quantum characteristics.To ac...In our study of super quantum discord between two excitonic qubits inside a coupled semiconductor quantum dots system,our primary focus is to uncover the impact of weak measurement on its quantum characteristics.To achieve this,we analyze how varying the measurement strength x,affects this super quantum correlation in the presence of thermal effects.Additionally,we assess the effect of this variation on the system's evolution against its associated quantum parameters;external electric fields,exciton-exciton dipole interaction energy and F?rster interaction.Our findings indicate that adjusting x to smaller values effectively enhances the super quantum correlation,making weak measurements act as a catalyst.This adjustment ensures its robustness against thermal effects while preserving the non-classical attributes of the system.Furthermore,our study unveils that the effect of weak measurements on this latter surpasses the quantum effects associated with the system.Indeed,manipulating the parameter x allows the weak measurement to function as a versatile tool for modulating quantum characteristics and controlling exciton-exciton interactions within the coupled semiconductor quantum dots system.展开更多
This work presents an analysis of the research conducted in many countries in recent years on the so-called Gatchina discharge.The findings indicate that the Gatchina discharge exhibits the majority of the characteris...This work presents an analysis of the research conducted in many countries in recent years on the so-called Gatchina discharge.The findings indicate that the Gatchina discharge exhibits the majority of the characteristics of natural ball lightning,making it the most effective method for reproducing and studying this phenomenon.To a large extent,our new results are based on experiments performed for the first time to visualize dust particles arising in an erosive emission,as well as the formation of vortex flows.These experiments make it possible to explain the ability of the Gatchina discharge to maintain its shape for a long time in the afterglow.展开更多
This correction adds some information to our publication[Chin.J.Chem.Phys.32,365–372(2019)]that we previously missed to include.Our previous work published in[Appl.Catal.B Env-iron.186,10(2016)]was based on the same ...This correction adds some information to our publication[Chin.J.Chem.Phys.32,365–372(2019)]that we previously missed to include.Our previous work published in[Appl.Catal.B Env-iron.186,10(2016)]was based on the same sample series but with the focus of explaining the interplay between the catalytic behavior and properties of the cuprous thin films.A superior catalytic performance was demonstrated when water was added in the deposition process[1](see Ref.[47]in our publication corrected here).展开更多
Conservation Agriculture(CA)covers more than 205 million hectares in the world.This made it possible to face and mitigate the challenges of climate change,reducing soil erosion and providing multiple ecosystem service...Conservation Agriculture(CA)covers more than 205 million hectares in the world.This made it possible to face and mitigate the challenges of climate change,reducing soil erosion and providing multiple ecosystem services.The first elementary factor influenced is the yield evaluation.It has a direct effect on farmers’choices for sustainable production.The present article records a review focused on wheat yield average positive change compared between conventional tillage(CT)and no tillage(NT)systems.The international database collected showed that NT is adaptable everywhere.The results of wheat yield differentiation showed the influence of crop rotation depending on stations located in different climatic zones.In more than 40 years of research,specialists have succeeded in demonstrating the importance of crop productivity like wheat.The whole integrates also experimentations where the initiation starts more than ten years.展开更多
In this work,we studied the electronic and magnetic properties of the double perovskite Sr_(2)CrMoO_(6)using ab initio calculations with generalized gradient approximation(GGA)and Monte Carlo(MC)simulations.The compou...In this work,we studied the electronic and magnetic properties of the double perovskite Sr_(2)CrMoO_(6)using ab initio calculations with generalized gradient approximation(GGA)and Monte Carlo(MC)simulations.The compound has two magnetic sublattices:one occupied by Mo5+with spin(S=1/2)and the other by Cr^(3+)with spin(σ=3/2)The results showed halfmetallic behavior with a total magnetic moment of 2.0μB.Using Monte Carlo simulations,we investigated the phase transitions and observed interesting phenomena such as a critical endpoint and both second-order and first-order phase transitions.Additionally,the results revealed compensation points for specific values of the crystal field.展开更多
文摘The buckling behavior of stiffened panels is significantly influenced by material and geometric defects,making it a critical factor in ensuring structural integrity and safety.These panels are widely used in mechanical,aerospace,marine,and civil engineering applications due to their ability to enhance bending stiffness with minimal additional weight.Under high loads or stress concentrations,localized structural failures can initiate global buckling in stiffened panels.This study investigates how such defects affect the critical buckling load,stiffness,and thickness of stiffened panels.Two finite element analyses were conducted:a linear analysis to identify the initial buckling mode and a nonlinear analysis using the Riks algorithm in Abaqus CAE,incorporating localized imperfections.The simulations show that material and geometric defects can reduce buckling resistance depending on their severity.
文摘BACKGROUND Solid pseudopapillary neoplasm(SPN)of the pancreas is a rare epithelial tumor that primarily affects young women.Since the condition is often asymptomatic or presents with non-specific symptoms,its diagnosis can be difficult.CASE SUMMARY This report details the case of a 15-year-old girl who presented with a 2-year history of abdominal pain,with no significant findings during physical examination.Abdominal ultrasound revealed a well-defined heterogeneous solidcystic mass in the epigastric region,likely originating from the tail of the pancreas.A subsequent contrast-enhanced computed tomography scan indicated a welldefined cystic lesion with an enhancing solid component and capsule in the tail of the pancreas,suggestive of a cystic neoplasm.The patient underwent an open distal pancreatectomy with splenectomy,and histopathological analysis confirmed the diagnosis of SPN of the pancreas.CONCLUSION This case highlights the risk of SPN in adolescent girls and the necessity of early diagnosis and intervention for better outcomes.
文摘A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.
文摘This study investigates the physical properties of the rare earth XFes(X=Sm,Dy,or Nd)materials.Our analysis encompasses these compounds'structural,electronic,thermodynamic,and optical characteristics using density functional theory(DFT)as implemented in the Wien2k software package.The GGA+SOC+U method was employed to determine the exchange-correlation potential.Our results show that the XFes materials exhibit metallic behavior and exhibit ferromagnetic(FM)phases.Notably,our optical analysis reveals a strong absorption response in the UV region,with characteristic absorption curves and peak intensities varying across the different materials.We also investigated the thermodynamic properties of the materials,finding that the entropy increases exponentially with temperature as the materials transition from a ground state to a more disordered and amorphous state.Our thermodynamic results show that the Debye temperature decreases for all three materials,with DyFes exhibiting the highest Debye temperature at 0 K(307 K),followed by NdFes(298 K),and then SmFes(288 K).This indicates that each material has a unique thermal energy barrier to overcome before vibrations occur.As the temperature increases,the Debye temperature decreases,reflecting a decrease in the thermal energy required to induce vibrations.The differences in Debye temperature values between the three materials may suggest differences in their lattice structures or phonon properties,highlighting the importance of understanding these thermal properties for developing new materials and technologies.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602501)the National Natural Science Foundation of China(Grant No.12011530060)+1 种基金supported solely by the Russian Science Foundation(Grant No.22-12-00043)supported by the Chinese Academy of Sciences(CAS)Presidents International Fellowship Initiative(PIFI)(Grant Nos.2018VMB0016 and 2022VMC0002),respectively。
文摘We explored a distinct mechanism for matter creation via electron-positron pair production during bound-bound transitions in the deexcitation of muonic atoms.For ions with nuclear charges Z≥24,transitions from low-lying excited states to the 1s-muon state can lead to the production of electron-positron pairs.We show that the Breit interaction determines the transition probabilities for states with nonzero orbital momentum.We show that the pair production arises mainly from the decay of the 2p states.Thus,the Breit interaction governs electron-positron pair production in bound-bound muon transitions.This process offers a unique opportunity to explore quantum electrodynamics in strong fields,as well as a class of nonradiative transitions involving electron-positron pair production.
基金supported by the Natural Science Foundation of Guangxi(2021GXNSFFA196004,2024GXNSFBA010337)the NNSF of China(12371312)+1 种基金the Natural Science Foundation of Chongqing(CSTB2024NSCQ-JQX0033)supported by the project cooperation between Guangxi Normal University and Yulin Normal University.
文摘This paper addresses the evolution problem governed by the fractional sweeping process with prox-regular nonconvex constraints.The values of the moving set are time and state-dependent.The aim is to illustrate how a fixed point method can establish an existence theorem for this fractional nonlinear evolution problem.By combining Schauder’s fixed point theorem with a well-posedness theorem when the set C is independent of the state u(i.e.C:=C(t),as presented in[22,23]),we prove the existence of a solution to our quasi-variational fractional sweeping process in infinite-dimensional Hilbert spaces.Similar to the conventional state-dependent sweeping process,achieving this result requires a condition on the size of the Lipschitz constant of the moving set relative to the state.
文摘This study evaluates the impact of heavy metals(zinc,copper and cadmium)on the development and metabolic responses of the maize(Zea mays)variety“Torro Plus”.Seeds were cultivated on MS medium enriched with progressively higher concentrations of heavy metals(50,100 and 150μM),and plants were analyzed after 21 days.The results show a significant reduction in morphological parameters,notably an 87.28%decrease in the fresh weight of aerial parts and a 69.93%decrease in the fresh weight of roots under 150μM of Cd.Chlorophyll a,b and total content also decreased drastically,reaching a maximum reduction of 74.31%under Cd(150μM).In contrast,secondary metabolites such as proline and flavonoids increased,with a maximum proline accumulation of 0.71 mg/g under Cu(150μM)and a flavonoid concentration reaching 176.33 mg/g under Cu(100μM).These results show mechanisms of adaptation to stress,notably the accumulation of flavonoids and proline,while highlighting the increased toxicity of cadmium at high doses.These data are promising for applications in phytoremediation and sustainable agriculture.This study provides important data on the physiological and biochemical responses of plants to heavy metals and opens up prospects for phytoremediation applications.
文摘In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).
文摘Maximizing the efficiency of thermal engineering equipment involves minimizing entropy generation,which arises from irreversible processes.This study examines thermal transport and entropy generation in viscous flow over a radially stretching disk,incorporating the effects of magnetohydrodynamics(MHD),viscous dissipation,Joule heating,and radiation.Similarity transformations are used to obtain dimensionless nonlinear ordinary differential equations(ODEs)from the governing coupled partial differential equations(PDEs).The converted equations are then solved by using the BVP4C solver in MATLAB.To validate the findings,the results are compared with previously published studies under fixed parameter conditions,demonstrating strong agreement.Various key parameters are analyzed graphically to assess their impact on velocity and temperature distributions.Additionally,Bejan number and entropy generation variations are presented for different physical parameters.The injection parameter(S<0)increases the heat transfer rate,while the suction parameter(S>0)reduces it,exhibiting similar effects on fluid velocity.The magnetic parameter(M)effectively decreases entropy generation within the range of approximately 0≤η≤0.6.Beyond this interval,its influence diminishes as entropy generation values converge,with similar trends observed for the Bejan number.Furthermore,increased thermal radiation intensity is identified as a critical factor in enhancing entropy generation and the Bejan number.
文摘Unlike primary metabolites,secondary metabolites serve critical ecological functions,including plant protection,stress tolerance,and symbiosis.This review focuses on extracting,separating,and identifying the major classes of secondary metabolites,including alkaloids,terpenoids,phenolics,glycosides,saponins,and coumarins.It describes optimized methods regarding plant selection,extraction by solvents,and purification of the metabolites,highlighting the latest advancements in chromatographic and spectroscopic techniques.The review also describes some of the most important problems,such as the instability of the compounds or diversity of the structures,and discusses emerging technologies that solve these issues.Moreover,it examines the secondary roles of these metabolites in medicine,such as anticancer and antimicrobial drugs,sustainable agriculture biopesticides,and environmental ecology-also known as allelopathy and bioindicators.It combines traditional ethnobotanical approaches with contem-porary science,demonstrating the vital need to protect biodiversity in key ecosystems such as tropical rainforests,mountain regions,coral reefs,and arid zones as a foundation for anticipatory bio-discoveries.It organizes the methodological frameworks and outlines the steps needed to enhance the extraction of bioactive compounds from natural sources.
基金support by the project n°7225-ILLIANCE High Performing EnergyPro-jeto apoiado pelo PRR-Plano de Recuperação e Resiliência e pelos Fundos Europeus Next Generation EU,no sequência do AVISO N.°02/C05-i01/2022,Componente 5-Capital-ização e Inovação Empresarial-Agendas Mobilizadores para a Inovação Empresarialsupport by national funds through FCT-Fundação para a Ciência e a Tecnologia,under the project UID/EMS/00285/2020,ARISE-LA/P/0112/2020.
文摘Magnesium(Mg)alloys are widely used for temporary bone implants due to their favorable biodegradability,cytocompatibility,hemocompatibility,and close mechanical properties to bone.However,rapid degradation and inadequate strength limit their applicability.To overcome this,the direct current magnetron sputtering technique is employed for surface coating in Mg-based alloys using various zirconium(Zr)content.This approach presents a promising strategy for simultaneously improving corrosion resistance,maintaining biocompatibility,and enhancing strength without compromising osseointegration.By leveraging Mg’s inherent biodegradability,it has the potential to minimize the need for secondary surgeries,thereby reducing costs and resources.This paper is a systematic study aimed at understanding the corrosion mechanisms of Mg–Zr coatings,denoted Mg-xZr(x=0–5 at.%).Zr-doped coatings exhibited columnar growth leading to denser and refined structures with increasing Zr content.XRD analysis confirmed the presence of the Mg(00.2)basal plane,shifting towards higher angles(1.15°)with 5 at.%Zr doping due to lattice parameter changes(i.e.,decrease and increase of“c”and“a”lattice parameters,respectively).Mg–Zr coatings exhibited“liquidphilic”behavior,while Young’s modulus retained a steady value around 80 GPa across all samples.However,the hardness has significantly improved across all samples’coating,reaching the highest value of(2.2±0.3)GPa for 5 at.%Zr.Electrochemical testing in simulated body fluid(SBF)at 37℃ revealed a significant enhancement in corrosion resistance for Mg–Zr coatings containing 1.0–3.4 at.%Zr.Compared with the 5 at.%Zr coating which exhibited a corrosion rate of 32 mm/year,these coatings displayed lower corrosion rates,ranging from 1 to 12 mm/year.This synergistic enhancement in mechanical properties and corrosion resistance,achieved with 2.0–3.4 at.%Zr,suggests potential ability for reducing stress shielding and controlled degradation performance,and consequently,promising functional biodegradable materials for temporary bone implants.
文摘Scalp necrosis is uncommon in malnourished children,yet temporal catheterization is frequently observed in pediatric hospital settings.The condition is characterized by a black,hard,and unresponsive scalp.Etiologies such as temporal arteritis,burns,and Takayasu’s disease,have been proposed.There is a decline in the use of peripheral catheter monitoring in hospitals.War-related food shortages and social instability significantly affect the trauma and risks that undermine the health,social,and psychological well-being of children.This report describes the case of a 5-month-old infant suffering from severe acute malnutrition following the abduction and subsequent release of his mother by armed individuals after one and a half weeks.The infant,who underwent temporal catheterization for medication administration,presented with extensive scalp necrosis.The necrotic tissue was surgically removed,and the malnutrition was successfully treated,resulting in a favorable clinical outcome.The mother received comprehensive mother-child care from a psychologist.
文摘The current study presents for the first time the preparation of a NiAl(68%(mass)Ni)intermetallic compound through the induction heating technique as a cathode for alkaline water electrolysis.The high-purity target was confirmed by X-ray diffraction and scanning electron microscopy combined with energy dispersive X-ray analysis.The chemical activation of Al from the NiAl electrode was achieved in a 25%NaOH solution at 353 K for 72 h.The performance and stability tests in a 1 mol·L^(-1)KOH solution at 298 K demonstrated that the enhancement of the hydrogen evolution reactionwas 13 times higher in the activated NiAl electrode than in the non-activated NiAl electrode.In addition,the electrochemical tests showed that the activated NiAl electrode exhibited the best hydrogen evolution reaction performance.Based on the findings,it is believed that the induction heating technique is a promising route for preparing a highly active and cost-effective NiAl electrode for green hydrogen production.
文摘Bulk geochemistry,Sr,Nd,and O-H isotope systematics are reported for the first time on banded iron formation(BIF)-hosted high-grade iron ore at the northwestern segment of Congo Craton(CC).Located in Mbalam iron ore district,Southern Cameroon,Metzimevin iron ore deposit is a hematite-magnetite BIF system,dominated by SiO_(2)+Fe_(2)O_(3)(97.1 to 99.84 wt%),with low concentrations of clastic elements e.g.,Al_(2)O_(3),TiO_(2),and HFSE,depicting a nearly pure chemical precipitate.The REE+Y signature of the iron deposit displays strong positive Eu anomaly,strong negative Ce anomaly,and chondritic to superchondritic Y/Ho ratios,suggestive of formation by mixed seawater-high temperature hydrothermal fluids in oxidising environment.The^(87)Sr/^(86)Sr ratios of the BIF are higher than the maximum^(87)Sr/^(86)Sr evolution curves for all Archean reservoirs(bulk silicate earth,Archean crust and Archean seawater),indicating involvement of continentally-derived components during BIF formation and alteration.TheƐ_(Nd)(t)(+2.26 to+3.77)and Nd model age indicate that chemical constituents for the BIF were derived from undifferentiated crustal source,between 3.002 and 2.88 Ga.The variable and diverse O and H isotope data(−1.9‰to 17.3‰and−57‰to 136‰respectively)indicate that the Metzimevin iron ore formed initially from magmatic plumes and later enriched by magmatic-metamorphic-modified meteoric fluids.Mass balance calculations indicate mineralisation by combined leaching and precipitation,with an average iron enrichment factor of>2.67 and SiO_(2)depletion factor of>0.99.This is associated with an overall volume reduction of 28.27%,reflecting net leaching and volume collapse of the BIF protholith.
文摘In our study of super quantum discord between two excitonic qubits inside a coupled semiconductor quantum dots system,our primary focus is to uncover the impact of weak measurement on its quantum characteristics.To achieve this,we analyze how varying the measurement strength x,affects this super quantum correlation in the presence of thermal effects.Additionally,we assess the effect of this variation on the system's evolution against its associated quantum parameters;external electric fields,exciton-exciton dipole interaction energy and F?rster interaction.Our findings indicate that adjusting x to smaller values effectively enhances the super quantum correlation,making weak measurements act as a catalyst.This adjustment ensures its robustness against thermal effects while preserving the non-classical attributes of the system.Furthermore,our study unveils that the effect of weak measurements on this latter surpasses the quantum effects associated with the system.Indeed,manipulating the parameter x allows the weak measurement to function as a versatile tool for modulating quantum characteristics and controlling exciton-exciton interactions within the coupled semiconductor quantum dots system.
基金supported by Province Key R&D Program of Heilongjiang(No.JD22A005)National Natural Science Foundation of China(Nos.12175050 and 12205067)。
文摘This work presents an analysis of the research conducted in many countries in recent years on the so-called Gatchina discharge.The findings indicate that the Gatchina discharge exhibits the majority of the characteristics of natural ball lightning,making it the most effective method for reproducing and studying this phenomenon.To a large extent,our new results are based on experiments performed for the first time to visualize dust particles arising in an erosive emission,as well as the formation of vortex flows.These experiments make it possible to explain the ability of the Gatchina discharge to maintain its shape for a long time in the afterglow.
文摘This correction adds some information to our publication[Chin.J.Chem.Phys.32,365–372(2019)]that we previously missed to include.Our previous work published in[Appl.Catal.B Env-iron.186,10(2016)]was based on the same sample series but with the focus of explaining the interplay between the catalytic behavior and properties of the cuprous thin films.A superior catalytic performance was demonstrated when water was added in the deposition process[1](see Ref.[47]in our publication corrected here).
文摘Conservation Agriculture(CA)covers more than 205 million hectares in the world.This made it possible to face and mitigate the challenges of climate change,reducing soil erosion and providing multiple ecosystem services.The first elementary factor influenced is the yield evaluation.It has a direct effect on farmers’choices for sustainable production.The present article records a review focused on wheat yield average positive change compared between conventional tillage(CT)and no tillage(NT)systems.The international database collected showed that NT is adaptable everywhere.The results of wheat yield differentiation showed the influence of crop rotation depending on stations located in different climatic zones.In more than 40 years of research,specialists have succeeded in demonstrating the importance of crop productivity like wheat.The whole integrates also experimentations where the initiation starts more than ten years.
文摘In this work,we studied the electronic and magnetic properties of the double perovskite Sr_(2)CrMoO_(6)using ab initio calculations with generalized gradient approximation(GGA)and Monte Carlo(MC)simulations.The compound has two magnetic sublattices:one occupied by Mo5+with spin(S=1/2)and the other by Cr^(3+)with spin(σ=3/2)The results showed halfmetallic behavior with a total magnetic moment of 2.0μB.Using Monte Carlo simulations,we investigated the phase transitions and observed interesting phenomena such as a critical endpoint and both second-order and first-order phase transitions.Additionally,the results revealed compensation points for specific values of the crystal field.
