We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated th...We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated the atrial and ventricular walls causing cardiac tamponade and a left hemothorax associated with ventricular perforation. An emergency sternotomy was performed to facilitate drainage and hemostasis. Although hemothorax due to pacing lead perforation is very rare, such a possibility should always be considered.展开更多
This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Pro...This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.展开更多
Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly im...Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.展开更多
Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony a...Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.展开更多
Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims ...Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.展开更多
Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value ...Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value catalyst not only solves the energy crisis but also reduces environmental pollution.Herein,we present a viable strategy to recycle Pb and iron(Fe)from Pb-Zn slags for the fabrication of efficient methylammonium lead tri-iodide(r-MAPbI_(3))piezocatalysts with single-atom Fe-N_(4) sites.Intriguingly,atomically dispersed Fe sites from Pb-Zn slags,which coordinated with N in the neighboring four CH3NH3 to form the FeN_(4) configuration,were detected in the as-obtained r-MAPbI_(3) by synchrotron X-ray absorption spectroscopy.The introduction of Fe single atoms amplified the polarization of MAPbI_(3) and upshifted the d-band center of MAPbI_(3).This not only enhanced the piezoelectric response of MAPbI_(3) but also promoted the proton transfer during the hydrogen evolution process.Due to the decoration of Fe single atoms,r-MAPbI_(3) showed a pronounced H2 yield of 322.4μmol g^(−1) h^(−1),which was 2.52 times that of MAPbI_(3) synthesized using commercially available reagents.This simple yet robust strategy to manufactureMAPbI_(3) piezocatalysts paves a novel way to the large-scale and value-added consumption of Pb-containing waste residues.展开更多
This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(G...This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(GPA)and 13-hydroxyglucopiericidin A(13-OH-GPA).The research aims to facilitate lead selection and optimization for developing a viable preclinical candidate.Rapid absorption of PA and GPAs in mice was observed,characterized by short half-lives and low bioavailability.Glycosides and hydroxyl groups significantly enhanced the absorption rate(13-OH-GPA>GPA>PA).PA and GPAs exhibited metabolic instability in liver microsomes due to Cytochrome P450 enzymes(CYPs)and uridine diphosphoglucuronosyl transferases(UGTs).Glucuronidation emerged as the primary metabolic pathway,with UGT1A7,UGT1A8,UGT1A9,and UGT1A10 demonstrating high elimination rates(30%-70%)for PA and GPAs.This rapid glucuronidation may contribute to the low bioavailability of GPAs.Despite its low bioavailability(2.69%),13-OH-GPA showed higher kidney distribution(19.8%)compared to PA(10.0%)and GPA(7.3%),suggesting enhanced biological efficacy in kidney diseases.Modifying the C-13 hydroxyl group appears to be a promising approach to improve bioavailability.In conclusion,this study provides valuable metabolic insights for the development and optimization of marine-derived piericidins as potential drug leads for kidney disease.展开更多
The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and obli...The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and oblique backscatter detection.The ionograms obtained by these detection methods can effectively reflect a large amount of effective information in the ionosphere.The focus of this article is on the oblique backscatter ionogram obtained by oblique backscatter detection.By extracting the leading edge of the oblique backscatter ionogram,effective information in the ionosphere can be inverted.The key issue is how to accurately obtain the leading edge of the oblique backscatter ionogram.In recent years,the application of pattern recognition has become increasingly widespread,and the YOLO model is one of the best fast object detection algorithms in one-stage.Therefore,the core idea of this article is to use the newer YOLOX object detection algorithm in the YOLO family to perform pattern recognition on the F and E_(s) layers echoes in the oblique backscatter ionogram.After image processing,a single-layer oblique backscatter echoes are obtained.It can be found that the leading edge extraction of the oblique backscatter ionogram obtained after pattern recognition and image processing by the YOLOX model is more fitting to the actual oblique backscatter leading edge.展开更多
Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli ce...Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli cells from 6-week-old rooster testes were divided into four goups.They were treated with serum-free DMEM-F12 medium(the control group),40μM lead acetate,100μM alpha-lipoic acid,or 40μM lead acetate plus 100μM alpha-lipoic acid for 24 h,respectively.Cell viability,reactive oxygen species levels(DCFH-DA),antioxidant enzyme activities(catalase,superoxide dismutase),blood-testis barrier-related proteins,nuclear factor-erythroid 2-related factor 2(Nrf2)pathway components,proliferation/apoptosis markers(Western blot),and related gene expression(qPCR)were analyzed.Results:Alpha-lipoic acid treatment significantly reduced lead-induced reactive oxygen species(ROS)production by 58.3%compared to the lead acetate group(P<0.05),enhanced catalase activity by 35.8%(P<0.05),and elevated lead-reduced PCNA expression by 47.2%(P<0.05).Lead acetate 40μM plus 100μM alpha-lipoic acid significantly increased Nrf2 expression by 78.9%and HO1/NQO1 expression by 97.5%and 89.4%,respectively(P<0.05),significantly upregulated the expression of Bcl2 protein and significantly downregulated Bax protein expression(P<0.05).Conclusions:Alpha-lipoic acid enhances the antioxidant properties of Sertoli cells by activating the Nrf2 pathway,restores lead-induced excessive autophagy,and inhibits apoptosis,thus alleviating the damage caused by lead in Sertoli cells.展开更多
Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool ...Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool to evaluate the Pb-contaminated soils stabilized by electrolytic manganese residue(EMR)-based geopolymer(EG-OPC)from the strength and environmental benefits perspective.First,unconfined compressive strength(UCS)and leaching tests were conducted to study the stabilization effectiveness of EG-OPC.Results indicated that the UCS values of soil(5000 mg/kg of pollutants)stabilized by 20%EG-OPC were 4.87 MPa and 8.13 MPa after 7 d and 60 d of curing,respectively.After 60 d of curing,the Pb concentration in the leachate reached 44 mg/L,far lower than the control group(321 mg/L).Second,soil,pore water,and leachate resistivity(ERS,ERW,and ERL)were measured to establish fitting relationships with strength parameters and pollution risk.The good fitting results(e.g.ERS/ERW versus UCS/secant modulus(E50):correlation coefficient R2 z 0.9,ERS/ERW versus Pb contents:R2 z 0.9,and ERL versus Pb2þconcentration:R2¼0.92)and well used Archie's law(ERS versus ERW:R2>0.9)indicate that the resistivity can be used to evaluate the stabilization effectiveness.Furthermore,the microscopic results revealed two behaviors,demonstrating the reliability of resistivity:(1)with the hydration process,resistivity increases due to a denser structure and lower amounts of free water and Pb ions,and(2)the addition of Pb reduces resistivity due to its inhibition or even destructive effects on cementation and formation of hydration products.展开更多
Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead i...Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.展开更多
This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw ma...This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.展开更多
The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified cont...The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified continuity method is used to forecast the shock configurations.The theoretical predictions and the numerical simulations for the Mach stem and the triple point as well as the curved shock accord well.Based on the theoretical model,an analysis of the impact of the axial ratio a/b of the cross-sectional shape and the eccentricity e of the crotch sweep path on shock structures is carried out.The shock configurations obtained from the theoretical model enable the derivation of the transition boundaries between the primary MR and the same family Regular Reflection(sRR).It is found that the increase of a/b and e can both facilitate the primary MR to sRR transition.The resulting transition and the corresponding generation of the wall pressure and heat flux are then investigated.The results indicate that higher values of the ratio a/b can significantly reduce the wall pressure and heating loads by inducing the primary MR to sRR transition.Conversely,the increase in the eccentricity e results in increased loads,despite causing the same transition.展开更多
Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribu...Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribute to greener aviation.In response to this need,this paper proposes a design optimization method for a variable-camber leading edge featuring an outer variablethickness composite compliant skin and an inner open-kinematic-chain mechanism.The optimization methodology employs a fiber continuity model based on a ply-drop sequence,a guiding sequence and a thickness sequence to describe the variable-thickness composite compliant skin structure,enabling direct generation of a composite layup sequence that meets fiber continuity criteria.Additionally,the design methodology for the inner open kinematic chain considers the rigidflexible coupling effect and analyzes the number of driving ribs along the span-wise direction.Finally,a full-scale physical prototype for a large-scale civil aircraft is developed and experimented in the FL-10 wind tunnel,demonstrating that the variable-camber leading edge can smoothly and precisely achieve its target shape and hold its final profile under the corresponding aerodynamic loads,thereby validating the proposed design methodology.展开更多
The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the vari...The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.展开更多
Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack...Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack of a confirmed geogas formation mechanism.Investigating the sources of geogas anomalies can help clarify this mechanism.This study focuses on the Bairendaba silver-polymetallic deposit,located in a grassland-covered area.Tracer research was conducted on lead isotope compositions in the mining area by analyzing various solid media(soil,rocks,ores)and geogas samples.The results revealed considerable differences in lead isotope compositions between background geogas samples and solid media.Furthermore,the lead isotope compositions of anomalous geogas samples differed markedly from those of background samples.These anomalous samples are located closer to the ore body,suggesting that ore-derived lead is incorporated into the geogas.The anomalous lead in geogas is inferred to originate from deep,concealed ore bodies.This study provides a theoretical basis for applying geogas surveys in mineral exploration within covered terrains.展开更多
Houttuynia cordata, a characteristic edible and medicinal plant in southwestern China, is prone to absorbing lead (Pb^(2+)). Excessive consumption may lead to Pb^(2+) accumulation in the human body, which has been lin...Houttuynia cordata, a characteristic edible and medicinal plant in southwestern China, is prone to absorbing lead (Pb^(2+)). Excessive consumption may lead to Pb^(2+) accumulation in the human body, which has been linked to serious health risks such as neurotoxicity, kidney damage, anemia, and developmental disorders, particularly in children. Therefore, the development of molecular markers associated with Pb^(2+) uptake and the investigation of the plant’s physiological responses to Pb^(2+) pollution are of great significance. In this study, 72 H. cordata germplasms were evaluated for Pb^(2+) accumulation after exogenous Pb^(2+) treatment. A significant variation in Pb^(2+) content was observed among the germplasms, indicating rich genetic diversity. Using RAPD markers, seven loci were identified to be significantly associated with Pb^(2+) uptake, with locus 43 (R^(2) = 6.72%) and locus 53 (R^(2) = 5.39%) showing the strongest correlations. Marker validation was performed using five low- and five high-accumulating accessions. Two representative germplasms were further subjected to 0, 500 and 1000 mg/kg Pb^(2+) treatments for 40 days. Pb^(2+) content, membrane lipid peroxidation, and redox enzyme activities (SOD, POD and CAT) were measured across different organs. Organs with greater soil contact (roots) exhibited higher Pb^(2+) accumulation and oxidative damage. POD and CAT activities were markedly induced by Pb^(2+) stress, while SOD response was limited. This study provides a theoretical foundation for breeding low Pb^(2+)-accumulating H. cordata varieties through marker-assisted selection (MAS) and supports their safe use and application in phytoremediation.展开更多
The purpose of this research is to analyze the causal mechanisms of learning difficulties of middle school students and use them to propose strategies to help them.This research is particularly valuable for its focus ...The purpose of this research is to analyze the causal mechanisms of learning difficulties of middle school students and use them to propose strategies to help them.This research is particularly valuable for its focus on middle school students.Research on this critical transition period is often lacking compared to primary and high school.Therefore,this research establishes a structured equation model and analyzes the data from the survey using the partial least squares method.The data were obtained from a 13,900 Wenzhou City,China students’questionnaire.The research found that learning strategies were the most significant influences on learning effectiveness,followed by learning motivation and learning relationships.Meanwhile,learning relationships had a significant impact on learning pressure.Therefore,this research proposes targeted support strategies.It aims to enhance learning motivation(Set achievable learning goals for each student with learning difficulties based on their actual situation),optimize learning strategies(Encourage students with learning difficulties to learn self-regulatory strategies such as goal setting,time management,and self-reflection),and improve learning relationships(Establish a good social network to promote positive interaction between students with learning difficulties and their peers).At the same time,it reduces students’learning pressure.Ultimately,the learning effectiveness of students with learning difficulties is improved.展开更多
The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and...The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.展开更多
The sources and accumulation of heavy metals in soil are of great significance for soil utilization and pollution control.Lead(Pb),a common heavy metal element,tends to accumulate in the soils with time.Excess Pb in s...The sources and accumulation of heavy metals in soil are of great significance for soil utilization and pollution control.Lead(Pb),a common heavy metal element,tends to accumulate in the soils with time.Excess Pb in soils accumulates in plants and becomes toxic to humans and livestock when it enters the food chain.The historical data of Pb contents in soils in northwest China were stud-ied to establish the historical change curve in this paper.The results indicate geochemical background and wind and dust deposition have the minor contribution to the accumulation of Pb in soils,but human activities have caused a rapid accumulation of Pb in soils.From 1990 to 2020,the accumulation of about 0.1 mg/kg of Pb in the soils is due to natural wind-dust deposits,but the content of Pb in the soils has nearly tripled from about 22 mg/kg to about 52 mg/kg with the process of anthropogenic urbanization and industrialization.We found that the influence of human activities on lead content was closely related to the total primary energy production(10,000 tons of SCE),and the evolution of soil Pb contents in the study area was consis-tent with the Allometric1 model.展开更多
文摘We describe the case of a 77-year-old female who underwent dual-chamber permanent pacemaker implantation using two active screw-in leads for complete atrioventricular block. The two active screw-in leads perforated the atrial and ventricular walls causing cardiac tamponade and a left hemothorax associated with ventricular perforation. An emergency sternotomy was performed to facilitate drainage and hemostasis. Although hemothorax due to pacing lead perforation is very rare, such a possibility should always be considered.
文摘This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0110300)the National Natural Science Foundation of China(Grant Nos.52372215,92163114,and 52202274)+5 种基金the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20230504)the Special Fund for the"Dual Carbon"Science and Technology Innovation of Jiangsu province(Industrial Prospect and Key Technology Research program)(Grant Nos.BE2022023 and BE2022021)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.21KJA430004)Gusu Innovation and Entre preneurship Leading Talent Program(Grant No.ZXL2022451)the China Postdoctoral Science Foundation(Grant No.2023M732523)supported by Suzhou Key Laboratory of Functional Nano&Soft Materials,Collaborative Innovation Center of Suzhou Nano Science&Technology,the 111 Project.
文摘Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.
基金financially supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ22F040001)China Postdoctoral Science Foundation (Grant No. 2022M723281)Science and Technology Planning Project of Shaoxing City (Grant No. 2023B41006)。
文摘Owing to their low toxicity and remarkable stability, perovskites based on antimony and bismuth have garnered significant interest in recent years. However, A_(3)B_(2)X_(9) perovskite materials derived from antimony and bismuth face several challenges, including excessively wide band gaps, elevated defect densities, and suboptimal film quality, all of which hinder advancements in device efficiency. While extensive studies have been undertaken to investigate the effects of modulating the A-site and X-site elements in lead-free A_(3)B_(2)X_(9) perovskites, there remains a notable scarcity of reports addressing the impact of modifications to the B-site element. In this study, we investigated the alloying of antimony and bismuth within the 2D Cs_(3)B_(2)I_(6)Br_(3) perovskite. By systematically varying the ratios of two elements, we found that the incorporation of both antimony and bismuth at the B-site significantly enhances the quality of the perovskite films. Our findings indicate that a 1 : 1 ratio of antimony to bismuth produces the densest films, the highest photoluminescence intensity, and superior photovoltaic performance. Ultimately,the devices fabricated using this optimal ratio achieved an open-circuit voltage(VOC) of 1.01 V and a power conversion efficiency(PCE) of 0.645%.
基金supported by the National Natural Science Foundation of China(12322210,12172351,92252202,and 12388101)the Fundamental Research Funds for the Central Universities.
文摘Rod-airfoil interaction noise becomes a major issue in some aeronautical applications.The design of four wavy leading edges(WLEs)with varying wavelengths,bioinspired by the tubercles on humpback whales’flippers,aims to mitigate far-field noise.Among these cases,a reduction in the wavelength is found to be advantageous for noise suppression,with the smallest wavelength case achieving a maximum noise reduction of 1.9 dB.Furthermore,the noise radiation induced by WLEs is suppressed mainly at medium frequencies.The theory of multiprocess aeroacoustics is applied to reveal their underlying mechanisms.The dominant factor is the source cutoff effect,which significantly decreases the source strength on hills.Additionally,spanwise decoherence with phase interference serves as another crucial mechanism,particularly for reducing mid-frequency noise.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004,U23B20166)Guangdong Basic and Applied Basic Research Foundation(2024A1515030039,2025A1515010312).
文摘Lead(Pb)-zinc(Zn)slags contain large amounts of Pb,causing irreversible damage to the environment.Therefore,developing an effective strategy to extract Pb from Pb-Zn slags and convert them into a renewable high-value catalyst not only solves the energy crisis but also reduces environmental pollution.Herein,we present a viable strategy to recycle Pb and iron(Fe)from Pb-Zn slags for the fabrication of efficient methylammonium lead tri-iodide(r-MAPbI_(3))piezocatalysts with single-atom Fe-N_(4) sites.Intriguingly,atomically dispersed Fe sites from Pb-Zn slags,which coordinated with N in the neighboring four CH3NH3 to form the FeN_(4) configuration,were detected in the as-obtained r-MAPbI_(3) by synchrotron X-ray absorption spectroscopy.The introduction of Fe single atoms amplified the polarization of MAPbI_(3) and upshifted the d-band center of MAPbI_(3).This not only enhanced the piezoelectric response of MAPbI_(3) but also promoted the proton transfer during the hydrogen evolution process.Due to the decoration of Fe single atoms,r-MAPbI_(3) showed a pronounced H2 yield of 322.4μmol g^(−1) h^(−1),which was 2.52 times that of MAPbI_(3) synthesized using commercially available reagents.This simple yet robust strategy to manufactureMAPbI_(3) piezocatalysts paves a novel way to the large-scale and value-added consumption of Pb-containing waste residues.
基金supported by the Special Project for Marine Economic Development of Department of Natural Resources of Guangdong Province(No.GDNRC[2024]25)National Natural Science Foundation of China(Nos.82274002,U20A20101)+1 种基金Guangdong Local Innovation Team Program(No.2019BT02Y262)Science and Technology Innovation Project of Guangdong Medical Products Administration(Nos.S2021ZDZ042,2023ZDZ06,2024-ZDZ08,2024A1515012477)。
文摘This study investigates the pharmacokinetics and metabolic characteristics of three marinederived piericidins as potential drug leads for kidney disease:piericidin A(PA)and its two glycosides(GPAs),glucopiericidin A(GPA)and 13-hydroxyglucopiericidin A(13-OH-GPA).The research aims to facilitate lead selection and optimization for developing a viable preclinical candidate.Rapid absorption of PA and GPAs in mice was observed,characterized by short half-lives and low bioavailability.Glycosides and hydroxyl groups significantly enhanced the absorption rate(13-OH-GPA>GPA>PA).PA and GPAs exhibited metabolic instability in liver microsomes due to Cytochrome P450 enzymes(CYPs)and uridine diphosphoglucuronosyl transferases(UGTs).Glucuronidation emerged as the primary metabolic pathway,with UGT1A7,UGT1A8,UGT1A9,and UGT1A10 demonstrating high elimination rates(30%-70%)for PA and GPAs.This rapid glucuronidation may contribute to the low bioavailability of GPAs.Despite its low bioavailability(2.69%),13-OH-GPA showed higher kidney distribution(19.8%)compared to PA(10.0%)and GPA(7.3%),suggesting enhanced biological efficacy in kidney diseases.Modifying the C-13 hydroxyl group appears to be a promising approach to improve bioavailability.In conclusion,this study provides valuable metabolic insights for the development and optimization of marine-derived piericidins as potential drug leads for kidney disease.
基金Supported by the National Natural Science Foundation of China(42104151,42074184,42188101,41727804)。
文摘The ionosphere is an important component of the near Earth space environment.The three common methods for detecting the ionosphere with high frequency(HF)radio signals are vertical detection,oblique detection,and oblique backscatter detection.The ionograms obtained by these detection methods can effectively reflect a large amount of effective information in the ionosphere.The focus of this article is on the oblique backscatter ionogram obtained by oblique backscatter detection.By extracting the leading edge of the oblique backscatter ionogram,effective information in the ionosphere can be inverted.The key issue is how to accurately obtain the leading edge of the oblique backscatter ionogram.In recent years,the application of pattern recognition has become increasingly widespread,and the YOLO model is one of the best fast object detection algorithms in one-stage.Therefore,the core idea of this article is to use the newer YOLOX object detection algorithm in the YOLO family to perform pattern recognition on the F and E_(s) layers echoes in the oblique backscatter ionogram.After image processing,a single-layer oblique backscatter echoes are obtained.It can be found that the leading edge extraction of the oblique backscatter ionogram obtained after pattern recognition and image processing by the YOLOX model is more fitting to the actual oblique backscatter leading edge.
基金funded by Zhejiang Provincial Natural Science Foundation of China under Grant No.LTGN24C170001Zhejiang Province Vocational Education Teaching Reform Project jg20230038+1 种基金Zhejiang Province Education Science Planning Project 2024JCD034Jinhua Science and Technology Plan Project 2024-2-002.
文摘Objective:To investigate the protective effect of alpha-lipoic acid on lead-induced Sertoli cell injury and its potential molecular mechanisms using primary Sertoli cells from rooster testes.Methods:Primary Sertoli cells from 6-week-old rooster testes were divided into four goups.They were treated with serum-free DMEM-F12 medium(the control group),40μM lead acetate,100μM alpha-lipoic acid,or 40μM lead acetate plus 100μM alpha-lipoic acid for 24 h,respectively.Cell viability,reactive oxygen species levels(DCFH-DA),antioxidant enzyme activities(catalase,superoxide dismutase),blood-testis barrier-related proteins,nuclear factor-erythroid 2-related factor 2(Nrf2)pathway components,proliferation/apoptosis markers(Western blot),and related gene expression(qPCR)were analyzed.Results:Alpha-lipoic acid treatment significantly reduced lead-induced reactive oxygen species(ROS)production by 58.3%compared to the lead acetate group(P<0.05),enhanced catalase activity by 35.8%(P<0.05),and elevated lead-reduced PCNA expression by 47.2%(P<0.05).Lead acetate 40μM plus 100μM alpha-lipoic acid significantly increased Nrf2 expression by 78.9%and HO1/NQO1 expression by 97.5%and 89.4%,respectively(P<0.05),significantly upregulated the expression of Bcl2 protein and significantly downregulated Bax protein expression(P<0.05).Conclusions:Alpha-lipoic acid enhances the antioxidant properties of Sertoli cells by activating the Nrf2 pathway,restores lead-induced excessive autophagy,and inhibits apoptosis,thus alleviating the damage caused by lead in Sertoli cells.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3901204)the Foundation for Distinguished Young Scholars of Hubei Province,China(Grant No.2021CFA096)the National Natural Science Foundation of China(Grant No.U20A20320).
文摘Evaluating the stabilized lead(Pb)-contaminated soils through sampling and laboratory testing involves costly and time-consuming processes.Therefore,this study employed a low-cost and non-destructive resistivity tool to evaluate the Pb-contaminated soils stabilized by electrolytic manganese residue(EMR)-based geopolymer(EG-OPC)from the strength and environmental benefits perspective.First,unconfined compressive strength(UCS)and leaching tests were conducted to study the stabilization effectiveness of EG-OPC.Results indicated that the UCS values of soil(5000 mg/kg of pollutants)stabilized by 20%EG-OPC were 4.87 MPa and 8.13 MPa after 7 d and 60 d of curing,respectively.After 60 d of curing,the Pb concentration in the leachate reached 44 mg/L,far lower than the control group(321 mg/L).Second,soil,pore water,and leachate resistivity(ERS,ERW,and ERL)were measured to establish fitting relationships with strength parameters and pollution risk.The good fitting results(e.g.ERS/ERW versus UCS/secant modulus(E50):correlation coefficient R2 z 0.9,ERS/ERW versus Pb contents:R2 z 0.9,and ERL versus Pb2þconcentration:R2¼0.92)and well used Archie's law(ERS versus ERW:R2>0.9)indicate that the resistivity can be used to evaluate the stabilization effectiveness.Furthermore,the microscopic results revealed two behaviors,demonstrating the reliability of resistivity:(1)with the hydration process,resistivity increases due to a denser structure and lower amounts of free water and Pb ions,and(2)the addition of Pb reduces resistivity due to its inhibition or even destructive effects on cementation and formation of hydration products.
基金Supported by Natural Science Foundation of Fujian Province(2023J011667)Natural Science Foundation of Xiamen(3502Z202374084).
文摘Microwave digestion-inductively coupled plasma mass spectrometry(ICP-MS)was used to analyze the sources of lead in farmland soil and rice in the Jiulongjiang River Basin.The results suggested that the source of lead in rice was differ from that in soil.There were four main sources of lead in farmland soil:natural source,agricultural source,industrial source and fossil fuel source,among which natural source,agricultural source and industrial source contributed more.There were four main sources of lead in rice:natural,agricultural,industrial and fossil fuel sources,and more importantly,fossil fuel sources.The comparison of lead isotope composition with potential sources(^(206)Pb/^(207)Pb,^(208)Pb/^(206)Pb,^(208)Pb/^(207)Pb)can provide a scientific basis for the identification and treatment of heavy metal lead pollution sources in farmland soil and rice in the Jiulong River Basin.
基金Funded by the Natural Science Foundation of Henan(No.252300421563)the Key Research Projects of Henan Provincial Colleges and Universities(No.25B450001)+3 种基金the Basic and Frontier Research Project of Nanyang(No.24JCQY032)National Natural Science Foundation of China(No.52201044)the Key Specialized Research&Development and Promotion Project(Scientific and Technological Project)of Henan Province(No.232102221022)the Basic and Frontier Technology Research Project of Nanyang(No.23JCQY1001)。
文摘This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.
基金support of the National Natural Science Foundation of China(Nos.U20A2069,12302389,12372295)the Natural Science Foundation of Fujian Province,China(No.2023J01046)。
文摘The primary Mach Reflection(MR)and pressure/heating loads on V-shaped Blunt Leading Edges(VBLEs)with variable elliptic cross-sections and conic crotches are theoretically investigated in this study.The simplified continuity method is used to forecast the shock configurations.The theoretical predictions and the numerical simulations for the Mach stem and the triple point as well as the curved shock accord well.Based on the theoretical model,an analysis of the impact of the axial ratio a/b of the cross-sectional shape and the eccentricity e of the crotch sweep path on shock structures is carried out.The shock configurations obtained from the theoretical model enable the derivation of the transition boundaries between the primary MR and the same family Regular Reflection(sRR).It is found that the increase of a/b and e can both facilitate the primary MR to sRR transition.The resulting transition and the corresponding generation of the wall pressure and heat flux are then investigated.The results indicate that higher values of the ratio a/b can significantly reduce the wall pressure and heating loads by inducing the primary MR to sRR transition.Conversely,the increase in the eccentricity e results in increased loads,despite causing the same transition.
基金supported by the National Research Project“Variable CAmber wing TechNology(VCAN)”,China。
文摘Climate change has prompted the aviation industry to reduce greenhouse gas emissions.Variable-camber leading edges,with their adaptable aerodynamic shapes,hold significant potential for laminar flow wings and contribute to greener aviation.In response to this need,this paper proposes a design optimization method for a variable-camber leading edge featuring an outer variablethickness composite compliant skin and an inner open-kinematic-chain mechanism.The optimization methodology employs a fiber continuity model based on a ply-drop sequence,a guiding sequence and a thickness sequence to describe the variable-thickness composite compliant skin structure,enabling direct generation of a composite layup sequence that meets fiber continuity criteria.Additionally,the design methodology for the inner open kinematic chain considers the rigidflexible coupling effect and analyzes the number of driving ribs along the span-wise direction.Finally,a full-scale physical prototype for a large-scale civil aircraft is developed and experimented in the FL-10 wind tunnel,demonstrating that the variable-camber leading edge can smoothly and precisely achieve its target shape and hold its final profile under the corresponding aerodynamic loads,thereby validating the proposed design methodology.
基金co-supported by the National Natural Science Foundation of China(Nos.12302300,12272312,12372288 and 12388101)the Open Fund of Key Laboratory of Icing and Anti/De-icing,China(No.IADL20220413)the 1-0 Major Engineering Science Problem Project of Northwestern Polytechnical University(No.G2024KY0613)。
文摘The contradiction between the efficiency and the ice tolerance remains a challenge to the traditional aerodynamic design considering the icing effect.To address the problem,a new ice-tolerant concept based on the variable drooping leading edge is proposed and extended to a single-aisle commercial aircraft with the swept wing.The outer-wing and full-spanwise drooping leading edge configurations are set up to distinguish the effect of different ice tolerant strategies.The Reynolds-averaged Navier-Stokes results reveal that the stall angle of attack is delayed by 25.0%,and the maximum lift coefficient is increased by 23.3%with the full-spanwise drooping in the presence of horn-shaped ice on the wing.This improvement is primarily driven by the recovery of leading-edge suction.With the formulation of the improved delayed detached eddy simulation,the structures and the behaviors of the separated flow near the stall point are analyzed via the comparison before and after drooping the leading edge in full-spanwise.The results indicate that the suppression of the spatial development of the shedding shear layer promotes the closure of the separation bubble and mitigates the sweeping motion of the large-scale spanwise vortex.These integrated effects contribute to the enhancement of ice tolerance.
基金supported by Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources(No.2023IRERE102)National Nonprofit Institute Research Grant of Institute of Geophysical and Geochemical Exploration(AS2022P03)。
文摘Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits.However,its application in covered areas has been questioned due to the lack of a confirmed geogas formation mechanism.Investigating the sources of geogas anomalies can help clarify this mechanism.This study focuses on the Bairendaba silver-polymetallic deposit,located in a grassland-covered area.Tracer research was conducted on lead isotope compositions in the mining area by analyzing various solid media(soil,rocks,ores)and geogas samples.The results revealed considerable differences in lead isotope compositions between background geogas samples and solid media.Furthermore,the lead isotope compositions of anomalous geogas samples differed markedly from those of background samples.These anomalous samples are located closer to the ore body,suggesting that ore-derived lead is incorporated into the geogas.The anomalous lead in geogas is inferred to originate from deep,concealed ore bodies.This study provides a theoretical basis for applying geogas surveys in mineral exploration within covered terrains.
基金supported by the Guizhou Provincial Department of Agriculture and Rural Afairs,the Guizhou Provincial Department of Science and Technology,and the Guizhou Provincial Department of Education.Funding Project are Guizhou Highland Specialty Vegetable Green Production Science,Technology Innovation Talent Team(Qiankehe Platform Talent-CXTD[2022]003)Guizhou Mountain Agriculture Key Core Technology Research Project(GZNYGJHX 2023013)Platform construction project of Engineering Research Center for Protected Vegetable Crops in Higher Learning Institutions of Guizhou Province(Qian Jiao Ji[2022]No.040).
文摘Houttuynia cordata, a characteristic edible and medicinal plant in southwestern China, is prone to absorbing lead (Pb^(2+)). Excessive consumption may lead to Pb^(2+) accumulation in the human body, which has been linked to serious health risks such as neurotoxicity, kidney damage, anemia, and developmental disorders, particularly in children. Therefore, the development of molecular markers associated with Pb^(2+) uptake and the investigation of the plant’s physiological responses to Pb^(2+) pollution are of great significance. In this study, 72 H. cordata germplasms were evaluated for Pb^(2+) accumulation after exogenous Pb^(2+) treatment. A significant variation in Pb^(2+) content was observed among the germplasms, indicating rich genetic diversity. Using RAPD markers, seven loci were identified to be significantly associated with Pb^(2+) uptake, with locus 43 (R^(2) = 6.72%) and locus 53 (R^(2) = 5.39%) showing the strongest correlations. Marker validation was performed using five low- and five high-accumulating accessions. Two representative germplasms were further subjected to 0, 500 and 1000 mg/kg Pb^(2+) treatments for 40 days. Pb^(2+) content, membrane lipid peroxidation, and redox enzyme activities (SOD, POD and CAT) were measured across different organs. Organs with greater soil contact (roots) exhibited higher Pb^(2+) accumulation and oxidative damage. POD and CAT activities were markedly induced by Pb^(2+) stress, while SOD response was limited. This study provides a theoretical foundation for breeding low Pb^(2+)-accumulating H. cordata varieties through marker-assisted selection (MAS) and supports their safe use and application in phytoremediation.
基金2025 Wenzhou Key Research Base of Philosophy and Social Science(Wenzhou University Learning Science and Technology Research Centre)Research Project:Investigation and Strategy Research on the Causes of Middle School Students’Learning Difficulties in the Context of the Leading Country in Education.
文摘The purpose of this research is to analyze the causal mechanisms of learning difficulties of middle school students and use them to propose strategies to help them.This research is particularly valuable for its focus on middle school students.Research on this critical transition period is often lacking compared to primary and high school.Therefore,this research establishes a structured equation model and analyzes the data from the survey using the partial least squares method.The data were obtained from a 13,900 Wenzhou City,China students’questionnaire.The research found that learning strategies were the most significant influences on learning effectiveness,followed by learning motivation and learning relationships.Meanwhile,learning relationships had a significant impact on learning pressure.Therefore,this research proposes targeted support strategies.It aims to enhance learning motivation(Set achievable learning goals for each student with learning difficulties based on their actual situation),optimize learning strategies(Encourage students with learning difficulties to learn self-regulatory strategies such as goal setting,time management,and self-reflection),and improve learning relationships(Establish a good social network to promote positive interaction between students with learning difficulties and their peers).At the same time,it reduces students’learning pressure.Ultimately,the learning effectiveness of students with learning difficulties is improved.
基金funding from the Ongoing Research Funding program,ORF-2025-298,King Saud University,Riyadh,Saudi Arabia.
文摘The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.
基金supported by the National Natural Science Foundation of China(Grant number:41440027)Geological Prospecting Fund of Qinghai Province(Grant number:2017042185sh029)Special project of Key Laboratory of Environmental Geology of Qinghai Province(Grant number:2023-KJ-13).Our special appreciate go to the editors and anonymous reviewers for their critical reviews and helpful comments.
文摘The sources and accumulation of heavy metals in soil are of great significance for soil utilization and pollution control.Lead(Pb),a common heavy metal element,tends to accumulate in the soils with time.Excess Pb in soils accumulates in plants and becomes toxic to humans and livestock when it enters the food chain.The historical data of Pb contents in soils in northwest China were stud-ied to establish the historical change curve in this paper.The results indicate geochemical background and wind and dust deposition have the minor contribution to the accumulation of Pb in soils,but human activities have caused a rapid accumulation of Pb in soils.From 1990 to 2020,the accumulation of about 0.1 mg/kg of Pb in the soils is due to natural wind-dust deposits,but the content of Pb in the soils has nearly tripled from about 22 mg/kg to about 52 mg/kg with the process of anthropogenic urbanization and industrialization.We found that the influence of human activities on lead content was closely related to the total primary energy production(10,000 tons of SCE),and the evolution of soil Pb contents in the study area was consis-tent with the Allometric1 model.
