The introduction of SCF2 motif into organic molecules would increases the bioactivity significantly.A silver-catalyzed tandem decarboxylative cyclization of 2,2-difluoro-2-(phenylthio)acetic acids with 2-aryl-N-acryla...The introduction of SCF2 motif into organic molecules would increases the bioactivity significantly.A silver-catalyzed tandem decarboxylative cyclization of 2,2-difluoro-2-(phenylthio)acetic acids with 2-aryl-N-acrylamide indoles is described,furnishing 28 examples of SCF2-substituted indolo[2,1-a]isoquinoline derivatives in moderate to good yields.Mechanistic studies reveal that a radical pathway is proposed in this transformation.展开更多
Herein,antibacterial silver‑doped fluorescent carbon dots(Ag‑CDs)were synthesized through a stepwise hydrothermal method,with polyethyleneimine(PEI),citric acid(CA),and silver nitrate(AgNO3)serving as precursors.The a...Herein,antibacterial silver‑doped fluorescent carbon dots(Ag‑CDs)were synthesized through a stepwise hydrothermal method,with polyethyleneimine(PEI),citric acid(CA),and silver nitrate(AgNO3)serving as precursors.The applicability and antimicrobial efficacy of these nanomaterials were systematically investigated for metal ion sensing.Experimental evidence demonstrated that the Ag‑CDs exhibited a pronounced fluorescence quenching response toward ferric ions(Fe^(3+)),enabling their quantitative determination via a linear concentration‑dependent relationship.These Ag‑CDs exhibited significant inhibitory effects on biofilm growth and disruption for both Escherichia coli and Staphylococcus aureus.Mechanism investigations indicate that Ag‑CDs induced the death of Escherichia coli and Pseudomonas aeruginosa by disrupting their bacterial morphology and structure,triggering the generation of intracellular reactive oxygen species(ROS),and impairing their antioxidant defense system.展开更多
The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the...The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the form of S—P bond.The ADD adsorption on argentite and sphalerite surface in Ag^(+)system was revealed by ICP,Zeta potential and XPS analyses.It is shown that the dissolved Ag^(+)from argentite surface can be absorbed on sphalerite surface in the form of silver hydroxide,and AgOH hydrophilic colloid prevents the adsorption of ADD on sphalerite surface.The ADD adsorption on argentite and sphalerite surface in the pulp containing silver and zinc ions was revealed by adsorption capacity and surface wettability analyses.It is shown that the combined Zn(OH)_(2) and AgOH hydrophilic colloid leads to greater ADD adsorption capacity on argentite surface and stronger surface hydrophobicity than sphalerite.Flotation tests demonstrate that ADD enables efficient separation of argentite from sphalerite in the pulp containing silver and zinc ions.展开更多
Understanding how genetic variation within forest species influences growth responses under climate change is essential for improving the accuracy of forest models and guiding adaptive management strategies.This study...Understanding how genetic variation within forest species influences growth responses under climate change is essential for improving the accuracy of forest models and guiding adaptive management strategies.This study models the dynamics of Italian silver fir(Abies alba)forests under varying climate change scenarios using the forest gap model FORMIND.Focusing on three distinct silver fir provenances(Western Alps,Northern Apennines,and Southern Apennines),the study simulates forest growth in the Tuscan-Emilian Apennine National Park under different representative concentration pathways(RCPs).The individual-based model FORMIND was parameterized and validated with field data for each of the provenances,demonstrating its ability to accurately reproduce key forest metrics and dynamics.Our results reveal significant differences in expected growth patterns,productivity,metabolism,and carbon storage capacity among the silver fir provenances in pure and mixed stands.In the simulations,the Northern Apennines provenance showed higher biomass production(biomass>10%±1%)and carbon uptake(net primary productivity,NPP>8%±1%)at the end of the century compared to the Western Alps provenance in the pure provenance(PP)and no regeneration scenario.Conversely,the Southern Apennines provenance showed higher biomass(biomass>5%–10%)and NPP(>15%–18%)in mixed provenance(MP)and regeneration scenarios.These results show that genetic diversity strongly affects forest growth and resilience to environmental changes.Hence,it should be included as a predictor variable in forest models.The study also demonstrates the resilience of silver fir to climatic stressors,emphasizing its potential as a robust species in multiple forest contexts.The integration of forest provenance data into the FORMIND model represents a significant advancement in forest modelling,enabling more accurate and reliable predictions under climate change scenarios.The study's findings advocate for a greater understanding and consideration of genetic diversity in forest management and conservation strategies,in support of assisted migration strategies aiming to enhance the resilience of forest ecosystems in a changing climate.展开更多
The efficient electrocatalytic oxidation of glycerol(GLY)is one of the most promising routes for the valorization of GLY.Doping has emerged as a powerful strategy to tailor the electrocatalytic performance of silver n...The efficient electrocatalytic oxidation of glycerol(GLY)is one of the most promising routes for the valorization of GLY.Doping has emerged as a powerful strategy to tailor the electrocatalytic performance of silver nanoclusters(Ag NCs),yet the effects of doping mode(surface vs.core)and the interface environment(e.g.,electrolyte concentration)on the electrocatalytic performance for Ag NCs toward GLY oxidation remain understood.In this work,surface-doped Ag_(4)M_(2)(SR)_(8) and core-doped Ag_(24)M(SR)_(18)(M=Ni,Pd,Pt;SR=SPhMe_(2))NCs were synthesized for electrocatalytic GLY oxidation.The results revealed a strong dependence of selectivity on doping mode and electrolyte concentration:under low KOH concentration,Pd-and Pt-doped Ag_(4)M_(2) NCs exhibited 100%selectivity toward oxalic acid(OA),whereas Pd-and Pt-doped Ag_(24)M NCs delivered>95%selectivity for formic acid(FA).In contrast,under high KOH concentration,Pd-and Pt-doped Ag_(4)M_(2) NCs gave rise to>80%FA,while Pd-and Pt-doped Ag_(24)M NCs produced>45%FA.Mechanism studies indicated that Ni doping predominantly enhanced catalytic activity via lowering the activation barrier of the initial reaction step(GLY→glyceraldehyde),whereas Pd and Pt doping modulated selectivity through reducing the energy barrier of the selective branch step(glyceric acid→OA,OA→FA).High KOH concentration promoted the oxidation by increasing the electrochemical active surface area and facilitating electron transfer of Ag NCs.This study provides clear guidance for designing high-performance Ag-based electrocatalysts for biomass valorization.展开更多
The purpose of this study is to explore the motivation,benefits and challenges of the elderly participating in e-sports,especially in the context of global population aging.E-sports has gradually become a growing glob...The purpose of this study is to explore the motivation,benefits and challenges of the elderly participating in e-sports,especially in the context of global population aging.E-sports has gradually become a growing global phenomenon.With the development of science and technology,more and more elderly people begin to participate in digital games to get fun and social interaction opportunities.The goal of the study is to deeply understand the motivation of the elderly to participate in e-sports,explore the cognitive,social and psychological benefits of this activity,and the challenges in the process of participation.Research methods include literature review,qualitative interviews and case studies.Through the analysis of existing research results and cases,we can comprehensively understand the performance and experience of the elderly in E-sports.The results show that the elderly's participation in E-sports can bring significant cognitive benefits,including improving memory,reaction speed and problem solving ability.In addition,E-sports provides a social platform for the elderly,promotes social interaction and emotional connection,and thus improves mental health.However,the elderly also face challenges such as technical barriers,health restrictions and social acceptance in the process of participation.The conclusion part points out that with the arrival of an aging society,Yinfa E-sports has broad prospects for development.Future research can focus on how E-sports can help the elderly cope with loneliness,promote cross generational communication,and how to optimize game design to meet the needs of the elderly.展开更多
Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are...Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution.In this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing agent.Experimental analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs.The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation.After the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite hydrogel.The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs.The prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.展开更多
The potent antibacterial activity of silver nanoparticles is primarily attributed to the release of silver ions,which disrupt cell membranes and inactivate essential enzymes through Ag−S bonding formation.[Objective]T...The potent antibacterial activity of silver nanoparticles is primarily attributed to the release of silver ions,which disrupt cell membranes and inactivate essential enzymes through Ag−S bonding formation.[Objective]To explore silver ion immobilization to minimize silver release.[Methods]A macrocyclic cryptand with nitrogen bridgeheads was prepared and subsequently chelated with silver ions to produce Cage silver(I),which was then coordinated with different ratios of sulfonated chitosan(SCS)to form SCS/Cage Ag(I)complexes(SCA1,SCA2,and SCA3).The antioxidant activities of the complexes were assessed by reducing power and 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical and hydrogen peroxide scavenging assays.The antibacterial activities of the complexes were evaluated based on the minimum inhibitory concentrations(MICs)and minimum bactericidal concentrations(MBCs)against Staphylococcus aureus ATCC 6538 and Escherichia coli O157:H7 and the inhibition rate on biofilm formation.[Results]Cage silver(I)exhibited strong antibacterial activity,with the MIC of 0.015 mg/mL and MBC of 0.031 mg/mL against S.aureus ATCC 6538,and the MIC of 0.031 mg/mL and MBC of 0.120 mg/mL against E.coli O157:H7.Significant antioxidant properties of Cage silver(I)were also observed,as demonstrated by the DPPH free radical scavenging rates of 42.2%and 53.1%at 326 nm and 517 nm,respectively.Cage silver(I)exhibited the highest antibacterial and antioxidant activities,followed by SCA1,SCA2,SCA3,and SCS,because the content of silver ions in Cage silver(I)was 10-fold higher than that in SCA1.The antibacterial and antioxidant activities of SCA1 were better than those of Cage silver(I),which further indicated that the sulfonic groups of SCS may intensely coordinate with silver ions to exert synergistic effects.[Conclusion]Combining the merits of silver ions and SCS improves the bioavailability of the agent at microbicidal concentrations,minimizes the accumulation in the environment,and reduces treatment costs.The method developed herein offers a sustainable approach to enhance microbial control while minimizing the impact on the environment.展开更多
The Zijinshan ore field located in southwestern Fujian Province,China,is a representative porphyry-epithermal ore system hosting diverse mineralization types(Mao et al.,2013).The ore field comprises of the Zijinshan h...The Zijinshan ore field located in southwestern Fujian Province,China,is a representative porphyry-epithermal ore system hosting diverse mineralization types(Mao et al.,2013).The ore field comprises of the Zijinshan highsulfidation Cu-Au deposit,the Luoboling porphyry Cu-Mo deposit,the transitional style Cu deposit(Longjiangting and Wuziqilong)and the Yueyang low-sulfidation Agpolymetallic deposit(Zhang,2013;Zhang et al.,2003)展开更多
Silver paste is widely used in power electronics as a die-attach material owing to its low-temperature sinterability,high melting point,and excellent electrical and thermal conductivities in sintered joints.However,ow...Silver paste is widely used in power electronics as a die-attach material owing to its low-temperature sinterability,high melting point,and excellent electrical and thermal conductivities in sintered joints.However,owing to the mismatch in the coefficient of thermal expansion(CTE)between the joints and chip,the high Young's modulus of sintered silver hinders the mitigation of the high thermal stress generated during the operation of power modules,which increases the susceptibility of sintered joints to cracking,thereby leading to potential failure.This study developed a facile approach to synthesizing bayberry-like Ag microparticles(AgMPs)through the in situ assembly of silver nanorods,resulting in a uniform distribution of nanoscale structures and mesopores on the particle surface.These particles exhibited a high specific surface area of 2.5389 m^(2)·g^(-1),which enhanced theirsintering activity,enabling sintering to occur at 149.7℃.Furthermore,the porous structure of the AgMPs effectively reduced the density of joints formed by sintering AgMP paste,thereby lowering the Young's modulus of the joints.The small grain size and intricate internal substructure of the joints yielded high shear strength,which reached112.50 MPa at 250℃.The Young's modulus could be adjusted,and the pores provided by the AgMPs maintained the Young's modulus within a low range(15.11-29.61GPa),effectively mitigating thermal stress.These new bayberry-like porous AgMPs offer a promising option for die-attach materials in electronic packaging.展开更多
A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthes...A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthesis of spirocyclic scaffolds containing a pyrroline motif.Notable features of this approach include good yields,remarkable enantioselectivity,as well as a broad substrate scope and significant step efficiency.展开更多
Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,an...Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,and precursor,respectively.Several technologies were employed to investigate the structures and optical properties of FA@Ag NCs,including transmission electron microscopy(TEM),X-ray photoelectron spectrometer(XPS),Fourier transform infrared spectrometer(FTIR),X-ray diffractometer(XRD),fluorescence spectrometer,and ultraviolet visible absorption spectrometer.FA@Ag NCs were suggested to be highly dispersed and spherical with a size of around 2.8 nm.Moreover,the maximum excitation and emission wavelengths of FA@Ag NCs were 370 and 447 nm,respectively.Under the optimal detection conditions,FA@Ag NCs could be used to effectively detect malachite green with the linear detection range of 0.5-200μmol·L^(-1).The detection limit was 0.084μmol·L^(-1).The fluorescence-quenching mechanism was ascribed to the static quenching.The detection system based on FA@AgNCs was successfully used for the detection of malachite green in actual samples with good accuracy and reproducibility.展开更多
Outdoor jackets are engineered to protect against extreme weather while ensuring comfort and safety. Key to this protection is the thermal properties, achieved through insulation materials like down feathers and synth...Outdoor jackets are engineered to protect against extreme weather while ensuring comfort and safety. Key to this protection is the thermal properties, achieved through insulation materials like down feathers and synthetic fibers, which trap heat and minimize heat loss. Resistance to wind, rain, and snow is provided by waterproof and windproof fabrics, while breathability allows moisture to escape, maintaining a comfortable microclimate. Air permeability and water resistance are essential for achieving this balance. This study examines two outdoor jacket prototypes with six material layers each. The outer layer (Layer 1) consists of 100% polyester coated with polyurethane for waterproofing. Inner layers (Layers 2, 3, and 6) use wool/cotton and wool/polyamide blends, offering insulation and moisture-wicking properties. Down feathers are used as the filling material, providing excellent warmth. Advanced materials like graphene and silver honeycomb fabrics were included to enhance thermal conductivity and regulate heat transfer. Performance testing focused on thermal conductivity, comfort (water and air permeability), and mechanical properties like tensile strength and tear resistance. Tests also assessed spray application and fastness to evaluate durability under environmental exposure. Results showed that jackets with silver-infused honeycomb fabrics had superior thermal conductivity, enabling better heat regulation and comfort in harsh conditions. The findings highlight the advantages of integrating silver honeycomb fabrics into outdoor jackets. These materials enhance insulation, thermal regulation, and overall comfort, making them ideal for high-performance designs. Incorporating such fabrics ensures functionality, durability, and user protection in extreme environments.展开更多
Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles...Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles to meet the demands of high precision and high efficiency in the process of fabricating a curved surface circuit,particularly achieving precise silver circuit molding on irregular substrates.Here,a high-precision and muti-scaled conformal manufacturing method for silver circuits is presented through the digital light processing(DLP)of ultraviolet-curable silver paste(UV-SP)with adjustable photocuring properties,enabling the successful preparation of micro-scaled conductive structure on the sharply skewed hook face.The minimum modeling depth and width of the cured silver paste can be well controlled to 10 and 88µm,respectively.Compared with traditional printing technology,the printing efficiency of complex patterns has increased by over 70%.The printed silver circuit demonstrates an exceptionally high electrical conductivity,reaching as high as 1.16×10^(7) S/m.Additionally,the UV-SP exhibits significant manufacturing efficiency and superior molding resolution compared to conventional direct ink writing and inkjet printing techniques,thereby contributing to the attainment of high precision and efficiency of conformal and micro-molding manufacturing in sensors,communication antennas,and other electronic devices based on curved substrates.展开更多
The main objective of the study was to prepare a highly active antimicrobial remedy by combining active agents such as tannic acid and silver nanoparticles,which are usually used separately.This was achieved by applyi...The main objective of the study was to prepare a highly active antimicrobial remedy by combining active agents such as tannic acid and silver nanoparticles,which are usually used separately.This was achieved by applying a coating of 11 alternating layers of an insoluble complex of tannic acid with polyvinyl alcohol on paper by the layerby-layer approach,on the surface of which uniformly distributed spherical silver nanoparticles of uniform size,mainly 20–30 nm,were synthesized by in situ reduction using tannic acid,which also acts as a stabilizer,or an external reducing agent,which prevented polyphenol oxidation.This gave an insight into which form-oxidized or reduced-ismore active against microorganisms.It was shown that sterilization was not required after the coating of the paper with tannic acid and silver nanoparticles.When combined,their activity against the studied bacteria-gram-negative Escherichia coli and gram-positive Staphylococcus aureus,as well as yeast Candida albicans was higher and lasting up to 7 days than when tannic acid and silver nanoparticles were used separately,indicating possible synergism in their action.展开更多
Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,an...Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,and other chemical reagents were used to synthesize chitosan-silver nanoparticles.The characterization,minimum inhibitory concentration,and biofilm inhibition rate of the chitosan-silver nanoparticles were tested.A total of 40 SD rats were randomly divided into four groups.After routine adaptive feeding,the control group received intraperitoneal injection of normal saline;the model group received intraperitoneal injection of Pseudomonas aeruginosa suspension;the positive group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with ampicillin at a volume ratio of 1∶1;the observation group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with chitosan-silver nanoparticles(at minimum inhibitory concentration)at a volume ratio of 1∶1.Bacterial load,inflammatory factors,and liver and kidney function indicators in tissues were observed and compared among the four groups on the 3^(rd)day after treatment.Results:When the concentration of chitosansilver nanoparticles reached 8μg/mL or above,the OD value of the experimental wells was close to that of the control wells,indicating that 8μg/mL was the minimum inhibitory concentration of the chitosan-silver nanoparticles;at concentrations of 8μg/mL or above,the biofilm inhibition rate was greater than 80%.The bacterial load in the observation group was significantly lower than that in the model and positive groups(P<0.05).The expression levels of interleukin-6,interferon-γ,and tumor necrosis factor-αin the observation group were significantly lower than those in the model and positive groups(P<0.05).There were no statistically significant differences in alanine aminotransferase,aspartate aminotransferase,blood urea nitrogen,and creatinine levels among the four groups(P>0.05).Conclusion:The chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms constructed in this study exhibit good antibacterial effects against Pseudomonas aeruginosa and have good safety.展开更多
Copper extraction from chalcopyrite is challenging,because acid dissolution is slow,occurring incongruently via a complex three-step reaction mechanism.Silver has been known to catalyse copper extraction from chalcopy...Copper extraction from chalcopyrite is challenging,because acid dissolution is slow,occurring incongruently via a complex three-step reaction mechanism.Silver has been known to catalyse copper extraction from chalcopyrite since the 1970's;yet the mechanism remains controversial.Microcharacterisation of experimental products obtained under optimal leaching conditions(50-150μm chalcopyrite grains in ferric/ferrous-sulfate solution with a redox potential around 500 mV vs.Ag/AgCl,approximately 1ppm Ag;[Ag]6.4×10^(−6)mol/L;70℃;4 days)highlights the heterogeneity of the reaction:µm-thick layers of a porous copper-sulfide with variable composition formed both in cracks within,and on the surface of the chalcopyrite grains.There is no evidence for formation of Ag-rich phases(Ag_(2)S_((s)),Ag_((s)^(0))).The fundamental three-step reaction mechanism remains the same with or without added silver;silver merely accelerates the initial dissolution step.An integrated model for the catalytic effect of silver is proposed that incorporates recent advances in the reactivity of sulfide minerals.The initial reaction follows a‘Fluid-Induced Solid State Diffusion Mechanism’,where diffusion of Fe in the chalcopyrite lattice is driven towards the surface by its rapid removal into solution,resulting in a Fe-deficient surface layer.The large Ag+ion,relative to Cu+/Fe3+,diffuses into this Fe-deficient surface layer and accelerates chalcopyrite dissolution in the subsequent step,whereby chalcopyrite is replaced by copper sulfides via an interface coupled dissolution reprecipitation reaction as a consequence of the sulfide-rich micro-environment at the mineral surface.Effective Ag+recycling is key to the catalytic effect of silver,and occurs as a result of the strong affinity of Ag+for bisulfide ligands accumulating at the surface of dissolving chalcopyrite.展开更多
文摘The introduction of SCF2 motif into organic molecules would increases the bioactivity significantly.A silver-catalyzed tandem decarboxylative cyclization of 2,2-difluoro-2-(phenylthio)acetic acids with 2-aryl-N-acrylamide indoles is described,furnishing 28 examples of SCF2-substituted indolo[2,1-a]isoquinoline derivatives in moderate to good yields.Mechanistic studies reveal that a radical pathway is proposed in this transformation.
文摘Herein,antibacterial silver‑doped fluorescent carbon dots(Ag‑CDs)were synthesized through a stepwise hydrothermal method,with polyethyleneimine(PEI),citric acid(CA),and silver nitrate(AgNO3)serving as precursors.The applicability and antimicrobial efficacy of these nanomaterials were systematically investigated for metal ion sensing.Experimental evidence demonstrated that the Ag‑CDs exhibited a pronounced fluorescence quenching response toward ferric ions(Fe^(3+)),enabling their quantitative determination via a linear concentration‑dependent relationship.These Ag‑CDs exhibited significant inhibitory effects on biofilm growth and disruption for both Escherichia coli and Staphylococcus aureus.Mechanism investigations indicate that Ag‑CDs induced the death of Escherichia coli and Pseudomonas aeruginosa by disrupting their bacterial morphology and structure,triggering the generation of intracellular reactive oxygen species(ROS),and impairing their antioxidant defense system.
基金the support from the National Key Research and Development Program of China (No. 2022YFC2904504)the Science and Technology Research Project of Jiangxi Provincial Department of Education, China (No. GJJ2200864)the Gansu Provincial Key Research and Development Project, China (No. 22YF7GA073)。
文摘The flotation separation of argentite from sphalerite using ammonium dibutyl dithiophosphate(ADD)was studied.Molecular simulation(MS)calculation shows that ADD is chemisorbed on argentite and sphalerite surface in the form of S—P bond.The ADD adsorption on argentite and sphalerite surface in Ag^(+)system was revealed by ICP,Zeta potential and XPS analyses.It is shown that the dissolved Ag^(+)from argentite surface can be absorbed on sphalerite surface in the form of silver hydroxide,and AgOH hydrophilic colloid prevents the adsorption of ADD on sphalerite surface.The ADD adsorption on argentite and sphalerite surface in the pulp containing silver and zinc ions was revealed by adsorption capacity and surface wettability analyses.It is shown that the combined Zn(OH)_(2) and AgOH hydrophilic colloid leads to greater ADD adsorption capacity on argentite surface and stronger surface hydrophobicity than sphalerite.Flotation tests demonstrate that ADD enables efficient separation of argentite from sphalerite in the pulp containing silver and zinc ions.
基金the University of Milan for funding the“ProForesta”project through the 2020 Research Support Planthe“Ente Parco Nazionale dell'Appennino Tosco-Emiliano”for having financed the project“First urgent measures to promote the adaptation of the silver fir forests of the Tuscan-Emilian Apennine National Park to the effects of climate change”。
文摘Understanding how genetic variation within forest species influences growth responses under climate change is essential for improving the accuracy of forest models and guiding adaptive management strategies.This study models the dynamics of Italian silver fir(Abies alba)forests under varying climate change scenarios using the forest gap model FORMIND.Focusing on three distinct silver fir provenances(Western Alps,Northern Apennines,and Southern Apennines),the study simulates forest growth in the Tuscan-Emilian Apennine National Park under different representative concentration pathways(RCPs).The individual-based model FORMIND was parameterized and validated with field data for each of the provenances,demonstrating its ability to accurately reproduce key forest metrics and dynamics.Our results reveal significant differences in expected growth patterns,productivity,metabolism,and carbon storage capacity among the silver fir provenances in pure and mixed stands.In the simulations,the Northern Apennines provenance showed higher biomass production(biomass>10%±1%)and carbon uptake(net primary productivity,NPP>8%±1%)at the end of the century compared to the Western Alps provenance in the pure provenance(PP)and no regeneration scenario.Conversely,the Southern Apennines provenance showed higher biomass(biomass>5%–10%)and NPP(>15%–18%)in mixed provenance(MP)and regeneration scenarios.These results show that genetic diversity strongly affects forest growth and resilience to environmental changes.Hence,it should be included as a predictor variable in forest models.The study also demonstrates the resilience of silver fir to climatic stressors,emphasizing its potential as a robust species in multiple forest contexts.The integration of forest provenance data into the FORMIND model represents a significant advancement in forest modelling,enabling more accurate and reliable predictions under climate change scenarios.The study's findings advocate for a greater understanding and consideration of genetic diversity in forest management and conservation strategies,in support of assisted migration strategies aiming to enhance the resilience of forest ecosystems in a changing climate.
基金support from the Jiangsu Natural Science Foundation of China(BK20230329)the National Natural Science Foundation of China(22401147,22361132540,and 22178161)the Russian Science Foundation(23-73-30007).
文摘The efficient electrocatalytic oxidation of glycerol(GLY)is one of the most promising routes for the valorization of GLY.Doping has emerged as a powerful strategy to tailor the electrocatalytic performance of silver nanoclusters(Ag NCs),yet the effects of doping mode(surface vs.core)and the interface environment(e.g.,electrolyte concentration)on the electrocatalytic performance for Ag NCs toward GLY oxidation remain understood.In this work,surface-doped Ag_(4)M_(2)(SR)_(8) and core-doped Ag_(24)M(SR)_(18)(M=Ni,Pd,Pt;SR=SPhMe_(2))NCs were synthesized for electrocatalytic GLY oxidation.The results revealed a strong dependence of selectivity on doping mode and electrolyte concentration:under low KOH concentration,Pd-and Pt-doped Ag_(4)M_(2) NCs exhibited 100%selectivity toward oxalic acid(OA),whereas Pd-and Pt-doped Ag_(24)M NCs delivered>95%selectivity for formic acid(FA).In contrast,under high KOH concentration,Pd-and Pt-doped Ag_(4)M_(2) NCs gave rise to>80%FA,while Pd-and Pt-doped Ag_(24)M NCs produced>45%FA.Mechanism studies indicated that Ni doping predominantly enhanced catalytic activity via lowering the activation barrier of the initial reaction step(GLY→glyceraldehyde),whereas Pd and Pt doping modulated selectivity through reducing the energy barrier of the selective branch step(glyceric acid→OA,OA→FA).High KOH concentration promoted the oxidation by increasing the electrochemical active surface area and facilitating electron transfer of Ag NCs.This study provides clear guidance for designing high-performance Ag-based electrocatalysts for biomass valorization.
文摘The purpose of this study is to explore the motivation,benefits and challenges of the elderly participating in e-sports,especially in the context of global population aging.E-sports has gradually become a growing global phenomenon.With the development of science and technology,more and more elderly people begin to participate in digital games to get fun and social interaction opportunities.The goal of the study is to deeply understand the motivation of the elderly to participate in e-sports,explore the cognitive,social and psychological benefits of this activity,and the challenges in the process of participation.Research methods include literature review,qualitative interviews and case studies.Through the analysis of existing research results and cases,we can comprehensively understand the performance and experience of the elderly in E-sports.The results show that the elderly's participation in E-sports can bring significant cognitive benefits,including improving memory,reaction speed and problem solving ability.In addition,E-sports provides a social platform for the elderly,promotes social interaction and emotional connection,and thus improves mental health.However,the elderly also face challenges such as technical barriers,health restrictions and social acceptance in the process of participation.The conclusion part points out that with the arrival of an aging society,Yinfa E-sports has broad prospects for development.Future research can focus on how E-sports can help the elderly cope with loneliness,promote cross generational communication,and how to optimize game design to meet the needs of the elderly.
基金financially supported by the National Natural Science Foundation of China(No.52203209)the State Key Laboratory of Solid Waste Reuse for Building Materials,China(No.SWR-2022-009)the Fundamental Research Funds for the Central Universities,China(No.FRF-IDRY22-012)。
文摘Silver nanoparticles(Ag NPs)have attracted attention in the field of biomaterials due to their excellent antibacterial property.However,the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution.In this work,Ag NPs(31.2 nm in diameter)were prepared using the extract of straw,an agricultural waste,as the reducing and stabilizing agent.Experimental analysis revealed that the straw extract contained lignin,the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs.The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation.After the prepared Ag NPs were added to the precursor solution of acrylamide,free radical polymerization was triggered without the need for extra heating or light irradiation,resulting in the rapid formation of an Ag NP-polyacrylamide composite hydrogel.The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs.The prepared hydrogel may have potential applications in the fabrication of biomedical materials,such as antibacterial dressings.
文摘The potent antibacterial activity of silver nanoparticles is primarily attributed to the release of silver ions,which disrupt cell membranes and inactivate essential enzymes through Ag−S bonding formation.[Objective]To explore silver ion immobilization to minimize silver release.[Methods]A macrocyclic cryptand with nitrogen bridgeheads was prepared and subsequently chelated with silver ions to produce Cage silver(I),which was then coordinated with different ratios of sulfonated chitosan(SCS)to form SCS/Cage Ag(I)complexes(SCA1,SCA2,and SCA3).The antioxidant activities of the complexes were assessed by reducing power and 1,1-diphenyl-2-picrylhydrazyl(DPPH)free radical and hydrogen peroxide scavenging assays.The antibacterial activities of the complexes were evaluated based on the minimum inhibitory concentrations(MICs)and minimum bactericidal concentrations(MBCs)against Staphylococcus aureus ATCC 6538 and Escherichia coli O157:H7 and the inhibition rate on biofilm formation.[Results]Cage silver(I)exhibited strong antibacterial activity,with the MIC of 0.015 mg/mL and MBC of 0.031 mg/mL against S.aureus ATCC 6538,and the MIC of 0.031 mg/mL and MBC of 0.120 mg/mL against E.coli O157:H7.Significant antioxidant properties of Cage silver(I)were also observed,as demonstrated by the DPPH free radical scavenging rates of 42.2%and 53.1%at 326 nm and 517 nm,respectively.Cage silver(I)exhibited the highest antibacterial and antioxidant activities,followed by SCA1,SCA2,SCA3,and SCS,because the content of silver ions in Cage silver(I)was 10-fold higher than that in SCA1.The antibacterial and antioxidant activities of SCA1 were better than those of Cage silver(I),which further indicated that the sulfonic groups of SCS may intensely coordinate with silver ions to exert synergistic effects.[Conclusion]Combining the merits of silver ions and SCS improves the bioavailability of the agent at microbicidal concentrations,minimizes the accumulation in the environment,and reduces treatment costs.The method developed herein offers a sustainable approach to enhance microbial control while minimizing the impact on the environment.
基金financially supported by Zijin Mining Group(No.01612216)the Ministry of Natural Resources,China(No.ZKKJ202426)。
文摘The Zijinshan ore field located in southwestern Fujian Province,China,is a representative porphyry-epithermal ore system hosting diverse mineralization types(Mao et al.,2013).The ore field comprises of the Zijinshan highsulfidation Cu-Au deposit,the Luoboling porphyry Cu-Mo deposit,the transitional style Cu deposit(Longjiangting and Wuziqilong)and the Yueyang low-sulfidation Agpolymetallic deposit(Zhang,2013;Zhang et al.,2003)
基金financially supported by the National Natural Science Foundation of China(Nos.52075125 and 52105331)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515010591)Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20210324124203009,JSGG20201102154600003,GXWD20231130103814001,GXWD20220721182229001)
文摘Silver paste is widely used in power electronics as a die-attach material owing to its low-temperature sinterability,high melting point,and excellent electrical and thermal conductivities in sintered joints.However,owing to the mismatch in the coefficient of thermal expansion(CTE)between the joints and chip,the high Young's modulus of sintered silver hinders the mitigation of the high thermal stress generated during the operation of power modules,which increases the susceptibility of sintered joints to cracking,thereby leading to potential failure.This study developed a facile approach to synthesizing bayberry-like Ag microparticles(AgMPs)through the in situ assembly of silver nanorods,resulting in a uniform distribution of nanoscale structures and mesopores on the particle surface.These particles exhibited a high specific surface area of 2.5389 m^(2)·g^(-1),which enhanced theirsintering activity,enabling sintering to occur at 149.7℃.Furthermore,the porous structure of the AgMPs effectively reduced the density of joints formed by sintering AgMP paste,thereby lowering the Young's modulus of the joints.The small grain size and intricate internal substructure of the joints yielded high shear strength,which reached112.50 MPa at 250℃.The Young's modulus could be adjusted,and the pores provided by the AgMPs maintained the Young's modulus within a low range(15.11-29.61GPa),effectively mitigating thermal stress.These new bayberry-like porous AgMPs offer a promising option for die-attach materials in electronic packaging.
文摘A Silver-catalyzed enantioselective[3+2]cycloaddition of azomethine ylides with activated alkenes by using a P-stereogenic ligand Ganphos is reported.The method provides an efficient strategy for the effective synthesis of spirocyclic scaffolds containing a pyrroline motif.Notable features of this approach include good yields,remarkable enantioselectivity,as well as a broad substrate scope and significant step efficiency.
文摘Herein,a one-pot chemical reduction method was reported to prepare folic acid(FA)-stabilized silver nanoclusters(FA@Ag NCs),in which FA,hydrazine hydrate,and silver nitrate were used as capping agent,reducing agent,and precursor,respectively.Several technologies were employed to investigate the structures and optical properties of FA@Ag NCs,including transmission electron microscopy(TEM),X-ray photoelectron spectrometer(XPS),Fourier transform infrared spectrometer(FTIR),X-ray diffractometer(XRD),fluorescence spectrometer,and ultraviolet visible absorption spectrometer.FA@Ag NCs were suggested to be highly dispersed and spherical with a size of around 2.8 nm.Moreover,the maximum excitation and emission wavelengths of FA@Ag NCs were 370 and 447 nm,respectively.Under the optimal detection conditions,FA@Ag NCs could be used to effectively detect malachite green with the linear detection range of 0.5-200μmol·L^(-1).The detection limit was 0.084μmol·L^(-1).The fluorescence-quenching mechanism was ascribed to the static quenching.The detection system based on FA@AgNCs was successfully used for the detection of malachite green in actual samples with good accuracy and reproducibility.
文摘Outdoor jackets are engineered to protect against extreme weather while ensuring comfort and safety. Key to this protection is the thermal properties, achieved through insulation materials like down feathers and synthetic fibers, which trap heat and minimize heat loss. Resistance to wind, rain, and snow is provided by waterproof and windproof fabrics, while breathability allows moisture to escape, maintaining a comfortable microclimate. Air permeability and water resistance are essential for achieving this balance. This study examines two outdoor jacket prototypes with six material layers each. The outer layer (Layer 1) consists of 100% polyester coated with polyurethane for waterproofing. Inner layers (Layers 2, 3, and 6) use wool/cotton and wool/polyamide blends, offering insulation and moisture-wicking properties. Down feathers are used as the filling material, providing excellent warmth. Advanced materials like graphene and silver honeycomb fabrics were included to enhance thermal conductivity and regulate heat transfer. Performance testing focused on thermal conductivity, comfort (water and air permeability), and mechanical properties like tensile strength and tear resistance. Tests also assessed spray application and fastness to evaluate durability under environmental exposure. Results showed that jackets with silver-infused honeycomb fabrics had superior thermal conductivity, enabling better heat regulation and comfort in harsh conditions. The findings highlight the advantages of integrating silver honeycomb fabrics into outdoor jackets. These materials enhance insulation, thermal regulation, and overall comfort, making them ideal for high-performance designs. Incorporating such fabrics ensures functionality, durability, and user protection in extreme environments.
基金supported by the National Natural Science Foundation of China(Nos.51972079 and 52302062)the National Key Research and Development Program of China(Nos.2022YFB370630202 and 2022YFB3706305).
文摘Electronic 3D printing possesses a remarkable molding ability and convenience in integrated circuits,flexible wearables,and individual automobile requirements.However,traditional 3D printing technology still struggles to meet the demands of high precision and high efficiency in the process of fabricating a curved surface circuit,particularly achieving precise silver circuit molding on irregular substrates.Here,a high-precision and muti-scaled conformal manufacturing method for silver circuits is presented through the digital light processing(DLP)of ultraviolet-curable silver paste(UV-SP)with adjustable photocuring properties,enabling the successful preparation of micro-scaled conductive structure on the sharply skewed hook face.The minimum modeling depth and width of the cured silver paste can be well controlled to 10 and 88µm,respectively.Compared with traditional printing technology,the printing efficiency of complex patterns has increased by over 70%.The printed silver circuit demonstrates an exceptionally high electrical conductivity,reaching as high as 1.16×10^(7) S/m.Additionally,the UV-SP exhibits significant manufacturing efficiency and superior molding resolution compared to conventional direct ink writing and inkjet printing techniques,thereby contributing to the attainment of high precision and efficiency of conformal and micro-molding manufacturing in sensors,communication antennas,and other electronic devices based on curved substrates.
基金funded by the Russian Science Foundation,grant 22-13-00337.
文摘The main objective of the study was to prepare a highly active antimicrobial remedy by combining active agents such as tannic acid and silver nanoparticles,which are usually used separately.This was achieved by applying a coating of 11 alternating layers of an insoluble complex of tannic acid with polyvinyl alcohol on paper by the layerby-layer approach,on the surface of which uniformly distributed spherical silver nanoparticles of uniform size,mainly 20–30 nm,were synthesized by in situ reduction using tannic acid,which also acts as a stabilizer,or an external reducing agent,which prevented polyphenol oxidation.This gave an insight into which form-oxidized or reduced-ismore active against microorganisms.It was shown that sterilization was not required after the coating of the paper with tannic acid and silver nanoparticles.When combined,their activity against the studied bacteria-gram-negative Escherichia coli and gram-positive Staphylococcus aureus,as well as yeast Candida albicans was higher and lasting up to 7 days than when tannic acid and silver nanoparticles were used separately,indicating possible synergism in their action.
文摘Objective:To develop chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms and verify their antibacterial performance through animal experiments.Methods:Chitosan,silver nitrate,glacial acetic acid,and other chemical reagents were used to synthesize chitosan-silver nanoparticles.The characterization,minimum inhibitory concentration,and biofilm inhibition rate of the chitosan-silver nanoparticles were tested.A total of 40 SD rats were randomly divided into four groups.After routine adaptive feeding,the control group received intraperitoneal injection of normal saline;the model group received intraperitoneal injection of Pseudomonas aeruginosa suspension;the positive group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with ampicillin at a volume ratio of 1∶1;the observation group received intraperitoneal injection of Pseudomonas aeruginosa suspension mixed with chitosan-silver nanoparticles(at minimum inhibitory concentration)at a volume ratio of 1∶1.Bacterial load,inflammatory factors,and liver and kidney function indicators in tissues were observed and compared among the four groups on the 3^(rd)day after treatment.Results:When the concentration of chitosansilver nanoparticles reached 8μg/mL or above,the OD value of the experimental wells was close to that of the control wells,indicating that 8μg/mL was the minimum inhibitory concentration of the chitosan-silver nanoparticles;at concentrations of 8μg/mL or above,the biofilm inhibition rate was greater than 80%.The bacterial load in the observation group was significantly lower than that in the model and positive groups(P<0.05).The expression levels of interleukin-6,interferon-γ,and tumor necrosis factor-αin the observation group were significantly lower than those in the model and positive groups(P<0.05).There were no statistically significant differences in alanine aminotransferase,aspartate aminotransferase,blood urea nitrogen,and creatinine levels among the four groups(P>0.05).Conclusion:The chitosan-silver nanoparticles targeting Pseudomonas aeruginosa biofilms constructed in this study exhibit good antibacterial effects against Pseudomonas aeruginosa and have good safety.
基金supporting this work through an ARC linkage grant(LP190101230)Part of this work was funded by ARC DP220100500+2 种基金The authors acknowledge the use of the instruments and scientific and technical assistance at the Monash Centre for Electron Microscopy,Monash University,a Microscopy Australia(ROR:042mm0k03)facility supported by NCRISThis research used equipment funded by Australian Research Council grant(s)(LE200100132,LE110100223).
文摘Copper extraction from chalcopyrite is challenging,because acid dissolution is slow,occurring incongruently via a complex three-step reaction mechanism.Silver has been known to catalyse copper extraction from chalcopyrite since the 1970's;yet the mechanism remains controversial.Microcharacterisation of experimental products obtained under optimal leaching conditions(50-150μm chalcopyrite grains in ferric/ferrous-sulfate solution with a redox potential around 500 mV vs.Ag/AgCl,approximately 1ppm Ag;[Ag]6.4×10^(−6)mol/L;70℃;4 days)highlights the heterogeneity of the reaction:µm-thick layers of a porous copper-sulfide with variable composition formed both in cracks within,and on the surface of the chalcopyrite grains.There is no evidence for formation of Ag-rich phases(Ag_(2)S_((s)),Ag_((s)^(0))).The fundamental three-step reaction mechanism remains the same with or without added silver;silver merely accelerates the initial dissolution step.An integrated model for the catalytic effect of silver is proposed that incorporates recent advances in the reactivity of sulfide minerals.The initial reaction follows a‘Fluid-Induced Solid State Diffusion Mechanism’,where diffusion of Fe in the chalcopyrite lattice is driven towards the surface by its rapid removal into solution,resulting in a Fe-deficient surface layer.The large Ag+ion,relative to Cu+/Fe3+,diffuses into this Fe-deficient surface layer and accelerates chalcopyrite dissolution in the subsequent step,whereby chalcopyrite is replaced by copper sulfides via an interface coupled dissolution reprecipitation reaction as a consequence of the sulfide-rich micro-environment at the mineral surface.Effective Ag+recycling is key to the catalytic effect of silver,and occurs as a result of the strong affinity of Ag+for bisulfide ligands accumulating at the surface of dissolving chalcopyrite.
