It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to o...It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to obtain the higher content. As the shell material of the first microcapsules prepared by the spray drying method, palmitic acid with the melting point of 60°C was adopted in order to prevent grape polyphenol from dissolution into water. As the shell material of the second microcapsules prepared by the layer-by-layer method, chitosan was used to coat the first microcapsules and to give the microcapsules alcohol resistance. In the experiment, the spray drying conditions such as the inlet temperature and the spraying pressure, the oil soluble surfactant species and the chitosan concentration were changed. The mean diameters of microcapsules could be controlled in the range from 5 μm to 35 μm by changing the spraying pressure and the inlet temperature. The yield of microcapsules and the microencapsulation efficiency over 50% could be obtained under the conditions of P = 1.0 kgf/cm2 and Tin = 100°C. Furthermore, the microencapsulation efficiency could be increased by adding the oil soluble surfactant with the larger HLB value. Coating with chitosan could considerably increase alcohol resistance.展开更多
In order to enhance the power output of microbial fuel cell as well as its stability, the development of a new type of anode is essential. The purpose of this work is to modify a stainless steel foam, using the layer-...In order to enhance the power output of microbial fuel cell as well as its stability, the development of a new type of anode is essential. The purpose of this work is to modify a stainless steel foam, using the layer-by-layer self-assembly technique, with rGO （reduced grapbene oxide） and PEI （polyethyleneimine）. The efficiency of this kind of modification has been investigated to determine the supply of graphene in term of electricity generation and stability. Under an applied voltage, which is used to form an electroactive biofilm, the modified stainless steel foam （SSF/（PE1/rGO）5） exhibited a current 50 times higher than the blank anode. The roughness of the SSF/（PEI/rGO）5 observed by SEM （scanning electron microscopy） is more favorable to attach more bacteria on it. Also, graphene improved the stability of the electrode as no response where observed for the blank anode after 18 days meanwhile the SSF/（PEI/rGO）5 was still running after 54 days.展开更多
Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic a...Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.展开更多
The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In...The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.展开更多
In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to ...In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.展开更多
In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical m...In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.展开更多
Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision...Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.展开更多
The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environmen...The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.展开更多
Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The t...Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.展开更多
At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systema...At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.展开更多
To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnes...To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.展开更多
Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg ...Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.展开更多
A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photo...A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.展开更多
Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly...Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.展开更多
Layer-by-layer(LbL)assembly technology is a facile method for constructing thin film composite membrane.Herein,a novel nanofiltration(NF)membrane was prepared by LbL assembly of polyethyleneimine(PEI)and sodium lignos...Layer-by-layer(LbL)assembly technology is a facile method for constructing thin film composite membrane.Herein,a novel nanofiltration(NF)membrane was prepared by LbL assembly of polyethyleneimine(PEI)and sodium lignosulfonate(LS)followed by cross-linking.The surface composition,morphology,and property of PEI/LS bilayer were detailedly investigated by FTIR/ATR,XPS,SEM,AFM,and water contact angle test.The PEI/LS bilayer full of amino and hydroxyl groups presents increased roughness and improved hydrophilicity.Moreover,the NF performance of PEI/LS LbL assembly membranes can be modulated by bilayer number,polyelectrolyte concentration,and salt content.The water flux reduced while the salt rejection greatly improved as increasing the bilayer numbers,PEI concentration,or NaCl content.More than 95%MgSO4 and MgCl2,as well as 80%NaCl can be rejected by a NF membrane prepared by 6 PEI/LS bilayers,1 wt%PEI,0.5 wt%LS,and 1 mol/L NaCl.Furthermore,this NF membrane can be used to remove more than 95%heavy metal ions(Cd2+,Zn2+,Mn2+,Cr2+,Cu2+,and Ni2+).This work proposed a promising NF membrane by using PEI/LS as low cost polyelectrolytes and facile LbL assembly method,which should receive much attention in water purification.展开更多
Morphology is of great significance to the performance of organic solar cells(OSCs),since appropriate morphology could not only promote the exciton dissociation,but also reduce the charge recombination.In this work,we...Morphology is of great significance to the performance of organic solar cells(OSCs),since appropriate morphology could not only promote the exciton dissociation,but also reduce the charge recombination.In this work,we have developed a solid additive-assisted layer-by-layer(SAA-LBL)processing to fabricate high-efficiency OSCs.By adding the solid additive of fatty acid(FA)into polymer donor PM6 solution,controllable pre-phase separation forms between PM6 and FA.This intermixed morphology facilitates the diffusion of acceptor Y6 into the donor PM6 during the LBL processing,due to the good miscibility and fast-solvation of the FA with chloroform solution dripping.Interestingly,this results in the desired morphology with refined phase-separated domain and vertical phase-separation structure to better balance the charge transport/collection and exciton dissociation.Consequently,the binary single junction OSCs based on PM6:Y6 blend reach champion power conversion efficiency(PCE)of 18.16%with SAA-LBL processing,which can be generally applicable to diverse systems,e.g.,the PM6:L8-BO-based devices and thick-film devices.The efficacy of SAA-LBL is confirmed in binary OSCs based on PM6:L8-BO,where record PCEs of 19.02%and 16.44%are realized for devices with 100 and 250 nm active layers,respectively.The work provides a simple but effective way to control the morphology for high-efficiency OSCs and demonstrates the SAA-LBL processing a promising methodology for boosting the industrial manufacturing of OSCs.展开更多
Layer-by-layer(LBL)assembly shows great potential in fabrication of flexible conductive cotton fabrics(FCCF)with carbon nanotubes(CNT)as conductive components but is limited because complicated chemical modification o...Layer-by-layer(LBL)assembly shows great potential in fabrication of flexible conductive cotton fabrics(FCCF)with carbon nanotubes(CNT)as conductive components but is limited because complicated chemical modification of CNT is usually required.Herein,we reported a facile and eco-friendly LBL approach to fabricating FCCF by dipping in chitosan(CS)aqueous solution and poly(sodium 4-styrenesulfonate)(PSS)wrapped CNT aqueous dispersion alternately.The FCCF with electrical conductivity higher than 30 S/m was achieved when 4 layers of CNT were coated on the cotton fabric(CF).The obtained FCCF possessed outstanding mechanical stability with electrical resistivity almost unchanged after exposure to 500 times mechanical abrasion and 500 circles of tape peeling.The FCCF showed excellent strain sensing performance with high sensitivity(with a gauge factor up to 35.1)and a fast response time(70 ms).It can be used as a strain sensor to accurately detect various human deformations such as finger bending and joint movements.The FCCF could be used as a temperature sensor in that it exhibited stable and reproducible negative temperature sensing behavior in the temperature range of 30-100℃.展开更多
The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform as...The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.展开更多
Multifunctional（poly（diallyldimethyl ammonium chloride）/sodium poly（4-styrene sulfonate）） n（（PDDA/PSS） n） thin films were fabricated by layer-by-layer assembled on the glass substrate.The monolayer silica na...Multifunctional（poly（diallyldimethyl ammonium chloride）/sodium poly（4-styrene sulfonate）） n（（PDDA/PSS） n） thin films were fabricated by layer-by-layer assembled on the glass substrate.The monolayer silica nanoparticles were prepared on the（PDDA/PSS） n films.The SiO 2-polyelectrolyte coatings exhibit antireflection properties with low refractive index（as low as 1.22）.Interestingly,wavelengths of maximum transmittance could be well tailored by simply changing the particle size of SiO 2.A maximum transmittance of 97.03% in the visible spectral range is achieved for the particle size of 100 nm SiO 2 films.The coatings also show excellent mechanical stability and good adhesion to substrates.The easy availability of the raw materials and simplicity of the fabrication method for such films might make them be potentially useful for various applications.展开更多
Spherical polyelectrolyte brushes （SPBs） consisting of polystyrene （PS） core and poly（2-aminoethyl methacrylate hydrochloride） （PAEMH） shell were prepared by photo-emulsion polymerization. Au nanoparticles （A...Spherical polyelectrolyte brushes （SPBs） consisting of polystyrene （PS） core and poly（2-aminoethyl methacrylate hydrochloride） （PAEMH） shell were prepared by photo-emulsion polymerization. Au nanoparticles （Au-NPs） with controlled size and size distribution were synthesized in situ using SPBs as nanoreactors. Via layer-by-layer deposition technique on the surface of SPBs, nano-composite particles with Au/Ag-NPs bilayer and Au/Ag/Au-NPs trilayer were prepared. The structures of the as-prepared Au/Ag multilayer SPBs were characterized by UV-Vis spectroscopy, TEM, ICP-AES and DLS. The charge reversal of the nano-composite particles observed by zeta potential confirmed the success of layer-by-layer assembly. The Au/Ag-NPs bilayer nano-composite particles showed high catalytic efficiency with an apparent activation energy of about 41.2 kJ/mol in the reduction reaction of 4-nitrophenol to 4-aminophenol in the existence of sodium borohydride monitored. The catalytic activity ofAu/Ag-NPs multilayer SPBs close to that of Au-NPs SPBs and much higher than that of Ag-NPs SPBs reveals its potential applications in cost-effective catalysts with high-performance.展开更多
文摘It was tried to prepare the microcapsules containing grape polyphenol with the spray drying method followed by the layer-by-layer method. As grape polyphenol was water soluble, the spray drying method was adopted to obtain the higher content. As the shell material of the first microcapsules prepared by the spray drying method, palmitic acid with the melting point of 60°C was adopted in order to prevent grape polyphenol from dissolution into water. As the shell material of the second microcapsules prepared by the layer-by-layer method, chitosan was used to coat the first microcapsules and to give the microcapsules alcohol resistance. In the experiment, the spray drying conditions such as the inlet temperature and the spraying pressure, the oil soluble surfactant species and the chitosan concentration were changed. The mean diameters of microcapsules could be controlled in the range from 5 μm to 35 μm by changing the spraying pressure and the inlet temperature. The yield of microcapsules and the microencapsulation efficiency over 50% could be obtained under the conditions of P = 1.0 kgf/cm2 and Tin = 100°C. Furthermore, the microencapsulation efficiency could be increased by adding the oil soluble surfactant with the larger HLB value. Coating with chitosan could considerably increase alcohol resistance.
文摘In order to enhance the power output of microbial fuel cell as well as its stability, the development of a new type of anode is essential. The purpose of this work is to modify a stainless steel foam, using the layer-by-layer self-assembly technique, with rGO （reduced grapbene oxide） and PEI （polyethyleneimine）. The efficiency of this kind of modification has been investigated to determine the supply of graphene in term of electricity generation and stability. Under an applied voltage, which is used to form an electroactive biofilm, the modified stainless steel foam （SSF/（PE1/rGO）5） exhibited a current 50 times higher than the blank anode. The roughness of the SSF/（PEI/rGO）5 observed by SEM （scanning electron microscopy） is more favorable to attach more bacteria on it. Also, graphene improved the stability of the electrode as no response where observed for the blank anode after 18 days meanwhile the SSF/（PEI/rGO）5 was still running after 54 days.
基金supported by Rachadapisek Sompote Fund for Postdoctoral Fellowship, Chulalongkorn University, Thailandthe Nanotechnology Center (NANOTEC), NSTDA Ministry of Science and Technology, Thailand, through its program of Center of Excellence Network+1 种基金National Research University Project of CHEthe Rachadapisek Sompote Endowment Fund (No. AM1041A)
文摘Polypropylene（PP） meltblown fibers were coated with titanium dioxide（Ti O2） nanoparticles using layer-by-layer（Lb L） deposition technique. The fibers were first modified with 3layers of poly（4-styrenesulfonic acid）（PSS） and poly（diallyl-dimethylammonium chloride）（PDADMAC） to improve the anchoring of the Ti O2 nanoparticle clusters. PDADMAC, which is positively charged, was then used as counter polyelectrolyte in tandem with anionic Ti O2 nanoparticles to construct Ti O2/PDADMAC bilayer in the Lb L fashion. The number of deposited Ti O2/PDADMAC layers was varied from 1 to 7 bilayer, and could be used to adjust Ti O2 loading. The Lb L technique showed higher Ti O2 loading efficiency than the impregnation approach. The modified fibers were tested for their photocatalytic activity against a model dye, Methylene Blue（MB）. Results showed that the Ti O2 modified fibers exhibited excellent photocatalytic activity efficiency similar to that of Ti O2 powder dispersed in solution. The deposition of Ti O23 bilayer on the PP substrate was sufficient to produce nanocomposite fibers that could bleach the MB solution in less than 4 hr.Ti O2-Lb L constructions also preserved Ti O2 adhesion on substrate surface after 1 cycle of photocatalytic test. Successive photocatalytic test showed decline in MB reduction rate with loss of Ti O2 particles from the substrate outer surface. However, even in the third cycle, the Ti O2 modified fibers are still moderately effective as it could remove more than 95% of MB after 8 hr of treatment.
基金supported by the Italian Ministry of University(MIUR)call PRIN 2017 with the project“PANACEA:A technology Platform for the sustainable recovery and advanced use of NAnostructured CEllulose from Agro-food residues”(grant No.2017LEPH3M).
文摘The increasing consciousness about the depletion of natural resources and the sustainability agenda are the major driving forces to try to reuse and recycle organic materials such as agri-food and industrial wastes.In this context,keratin fibers,as a waste from the tannery industry,represent a great opportunity for the development of green functional materials.In this paper,keratin fibers were surface functionalized using the Layer-by-Layer(LbL)deposition technique and then freeze-dried in order to obtain a lightweight,fire-resistant,and sustainable material.The LbL coating,made with chitosan and carboxymethylated cellulose nanofibers,is fundamental in enabling the formation of a self-sustained structure after freeze-drying.The prepared porous fiber networks(density 100 kg m^(-3))display a keratin fiber content greater than 95 wt%and can easily self-extinguish the flame during a flammability test in a vertical configuration.In addition,during forced combustion tests(50 kW m^(-2))the samples exhibited a reduction of 37% in heat release rate and a reduction of 75%in smoke production if compared with a commercial polyurethane foam.The results obtained represent an excellent opportunity for the development of fire-safe sustainable materials based on fiber wastes.
基金Supported in part by Natural Science Foundation of Guangxi(2023GXNSFAA026246)in part by the Central Government's Guide to Local Science and Technology Development Fund(GuikeZY23055044)in part by the National Natural Science Foundation of China(62363003)。
文摘In this paper,we consider the maximal positive definite solution of the nonlinear matrix equation.By using the idea of Algorithm 2.1 in ZHANG(2013),a new inversion-free method with a stepsize parameter is proposed to obtain the maximal positive definite solution of nonlinear matrix equation X+A^(*)X|^(-α)A=Q with the case 0<α≤1.Based on this method,a new iterative algorithm is developed,and its convergence proof is given.Finally,two numerical examples are provided to show the effectiveness of the proposed method.
基金supported by Anhui Provincial Natural Science Foundation(2408085QA030)Natural Science Research Project of Anhui Educational Committee,China(2022AH050825)+3 种基金Medical Special Cultivation Project of Anhui University of Science and Technology(YZ2023H2C008)the Excellent Research and Innovation Team of Anhui Province,China(2022AH010052)the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology,China(2021yjrc51)Collaborative Innovation Program of Hefei Science Center,CAS,China(2019HSC-CIP006).
文摘In this paper,a novel method for investigating the particle-crushing behavior of breeding particles in a fusion blanket is proposed.The fractal theory and Weibull distribution are combined to establish a theoretical model,and its validity was verified using a simple impact test.A crushable discrete element method(DEM)framework is built based on the previously established theoretical model.The tensile strength,which considers the fractal theory,size effect,and Weibull variation,was assigned to each generated particle.The assigned strength is then used for crush detection by comparing it with its maximum tensile stress.Mass conservation is ensured by inserting a series of sub-particles whose total mass was equal to the quality loss.Based on the crushable DEM framework,a numerical simulation of the crushing behavior of a pebble bed with hollow cylindrical geometry under a uniaxial compression test was performed.The results of this investigation showed that the particle withstands the external load by contact and sliding at the beginning of the compression process,and the results confirmed that crushing can be considered an important method of resisting the increasing external load.A relatively regular particle arrangement aids in resisting the load and reduces the occurrence of particle crushing.However,a limit exists to the promotion of resistance.When the strain increases beyond this limit,the distribution of the crushing position tends to be isotropic over the entire pebble bed.The theoretical model and crushable DEM framework provide a new method for exploring the pebble bed in a fusion reactor,considering particle crushing.
基金funded by the Beijing Engineering Research Center of Electric Rail Transportation.
文摘Effective partitioning is crucial for enabling parallel restoration of power systems after blackouts.This paper proposes a novel partitioning method based on deep reinforcement learning.First,the partitioning decision process is formulated as a Markov decision process(MDP)model to maximize the modularity.Corresponding key partitioning constraints on parallel restoration are considered.Second,based on the partitioning objective and constraints,the reward function of the partitioning MDP model is set by adopting a relative deviation normalization scheme to reduce mutual interference between the reward and penalty in the reward function.The soft bonus scaling mechanism is introduced to mitigate overestimation caused by abrupt jumps in the reward.Then,the deep Q network method is applied to solve the partitioning MDP model and generate partitioning schemes.Two experience replay buffers are employed to speed up the training process of the method.Finally,case studies on the IEEE 39-bus test system demonstrate that the proposed method can generate a high-modularity partitioning result that meets all key partitioning constraints,thereby improving the parallelism and reliability of the restoration process.Moreover,simulation results demonstrate that an appropriate discount factor is crucial for ensuring both the convergence speed and the stability of the partitioning training.
基金supported by the National Key Research and Develop-ment Program(No.2022YFC3701103)the National Natural Science Foundation of China(Nos.42130714 and 41931287).
文摘The application of nitrogen fertilizers in agricultural fields can lead to the release of nitrogen-containing gases(NCGs),such as NO_(x),NH_(3) and N_(2)O,which can significantly impact regional atmospheric environment and con-tribute to global climate change.However,there remain considerable research gaps in the accurate measurement of NCGs emissions from agricultural fields,hindering the development of effective emission reduction strategies.We improved an open-top dynamic chambers(OTDCs)system and evaluated the performance by comparing the measured and given fluxes of the NCGs.The results showed that the measured fluxes of NO,N_(2)O and NH_(3)were 1%,2%and 7%lower than the given fluxes,respectively.For the determination of NH_(3) concentration,we employed a stripping coil-ion chromatograph(SC-IC)analytical technique,which demonstrated an absorption efficiency for atmospheric NH_(3) exceeding 96.1%across sampling durations of 6 to 60 min.In the summer maize season,we utilized the OTDCs system to measure the exchange fluxes of NO,NH_(3),and N_(2)O from the soil in the North China Plain.Substantial emissions of NO,NH_(3) and N_(2)O were recorded following fertilization,with peaks of 107,309,1239 ng N/(m^(2)·s),respectively.Notably,significant NCGs emissions were observed following sus-tained heavy rainfall one month after fertilization,particularly with NH_(3) peak being 4.5 times higher than that observed immediately after fertilization.Our results demonstrate that the OTDCs system accurately reflects the emission characteristics of soil NCGs and meets the requirements for long-term and continuous flux observation.
基金Supported by the National Natural Science Foundation of China under Grant No.51975138the High-Tech Ship Scientific Research Project from the Ministry of Industry and Information Technology under Grant No.CJ05N20the National Defense Basic Research Project under Grant No.JCKY2023604C006.
文摘Marine thin plates are susceptible to welding deformation owing to their low structural stiffness.Therefore,the efficient and accurate prediction of welding deformation is essential for improving welding quality.The traditional thermal elastic-plastic finite element method(TEP-FEM)can accurately predict welding deformation.However,its efficiency is low because of the complex nonlinear transient computation,making it difficult to meet the needs of rapid engineering evaluation.To address this challenge,this study proposes an efficient prediction method for welding deformation in marine thin plate butt welds.This method is based on the coupled temperature gradient-thermal strain method(TG-TSM)that integrates inherent strain theory with a shell element finite element model.The proposed method first extracts the distribution pattern and characteristic value of welding-induced inherent strain through TEP-FEM analysis.This strain is then converted into the equivalent thermal load applied to the shell element model for rapid computation.The proposed method-particularly,the gradual temperature gradient-thermal strain method(GTG-TSM)-achieved improved computational efficiency and consistent precision.Furthermore,the proposed method required much less computation time than the traditional TEP-FEM.Thus,this study lays the foundation for future prediction of welding deformation in more complex marine thin plates.
基金supported by the National Natural Science Foundation of China(Project No.42307555).
文摘At present,there is currently a lack of unified standard methods for the determination of antimony content in groundwater in China.The precision and trueness of related detection technologies have not yet been systematically and quantitatively evaluated,which limits the effective implementation of environmental monitoring.In response to this key technical gap,this study aimed to establish a standardized method for determining antimony in groundwater using Hydride Generation–Atomic Fluorescence Spectrometry(HG-AFS).Ten laboratories participated in inter-laboratory collaborative tests,and the statistical analysis of the test data was carried out in strict accordance with the technical specifications of GB/T 6379.2—2004 and GB/T 6379.4—2006.The consistency and outliers of the data were tested by Mandel's h and k statistics,the Grubbs test and the Cochran test,and the outliers were removed to optimize the data,thereby significantly improving the reliability and accuracy.Based on the optimized data,parameters such as the repeatability limit(r),reproducibility limit(R),and method bias value(δ)were determined,and the trueness of the method was statistically evaluated.At the same time,precision-function relationships were established,and all results met the requirements.The results show that the lower the antimony content,the lower the repeatability limit(r)and reproducibility limit(R),indicating that the measurement error mainly originates from the detection limit of the method and instrument sensitivity.Therefore,improving the instrument sensitivity and reducing the detection limit are the keys to controlling the analytical error and improving precision.This study provides reliable data support and a solid technical foundation for the establishment and evaluation of standardized methods for the determination of antimony content in groundwater.
基金Project(2014TDJH104)supported by Shandong University of Science and Technology(SDUST)Research FundChina+3 种基金Project(2013RCJJ006)supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited TalentsChinaProject(BS2013CL009)supported by Scientific Research Foundation of Shandong for Outstanding Young ScientistChina
文摘To enhance the corrosion resistance of magnesium（Mg） alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg（OH）2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate（GS） and poly（sodium 4-styrene sulfonate）（PSS）, were prepared via layer-by-layer（Lb L） assembly. The morphologies, chemical compositions and corrosion resistance of the obtained（PSS/GS）n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of（PSS/GS）n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.
基金Projects(51571134,51601108)supported by the National Natural Science Foundation of ChinaProject(2013RCJJ006)supported by the Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents,China+1 种基金Project(2016ZRB01A62)supported by the Natural Science Foundation of Shandong Province,ChinaProject(2014TDJH104)supported by Shandong University of Science and Technology Research Fund,China
文摘Surface functionalization of magnesium(Mg)alloys is desired to obtain the surfaces with both improved corrosion resistance and antibacterial property.A corrosion-resistant and antimicrobial coating was prepared on Mg alloy surface by layer-by-layer(LbL)assembly of chitosan(CHI)and poly-L-glutamic acid(PGA)by electrostatic attraction.The functionalized surfaces of the Mg alloys were characterized by field-emission scanning electron microscopy(FE-SEM),Fourier transform infrared(FT-IR)spectroscopy and electrochemical tests.The bactericidal activity of the samples against Staphylococcus aureus was assessed by the zone of plate-counting method.The obtained coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance.
基金This work was supported by the National Natural Sci-ence Foundation of China(51571134)Shandong Provincial Natural Science Foundation(ZR2017BEM002)Shan-dong University of Science and Technology Research Fund(2014TDJH104).
文摘A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.
基金Supported by the National Basic Research Program of China(2015CB655301)the Natural Science Foundation of China(21825803)+2 种基金and the Natural Science Foundation of Jiangsu Province(BK20150063)the Program of Excellent Innovation Teams of Jiangsu Higher Education Institutionsthe Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Thin film composite(TFC) membranes represent a highly promising platform for efficient nanofiltration(NF)processes. However, the improvement in permeance is impeded by the substrates with low permeances. Herein,highly permeable gradient phenolic membranes with tight selectivity are used as substrates to prepare TFC membranes with high permeances by the layer-by-layer assembly method. The negatively charged phenolic substrates are alternately assembled with polycation polyethylenimine(PEI) and polyanion poly(acrylic acid)(PAA)as a result of electrostatic interactions, forming thin and compact PEI/PAA layers tightly attached to the substrate surface. Benefiting from the high permeances and tight surface pores of the gradient nanoporous structures of the substrates, the produced PEI/PAA membranes exhibit a permeance up to 506 L? m-2?h-1?MPa-1, which is ~2–10 times higher than that of other membranes with similar rejections. The PEI/PAA membranes are capable of retaining N 96.1% of negatively charged dyes following the mechanism of electrostatic repulsion. We demonstrate that the membranes can also separate positively and neutrally charged dyes from water via other mechanisms.This work opens a new avenue for the design and preparation of high-flux NF membranes, which is also applicable to enhance the permeance of other TFC membranes.
基金Zhejiang Provincial Natural Science Foundation of China(No.LY18E030002)Natural Science Foundation of Ningbo(No.2018A610111)K.C.Wong Magna Fund in Ningbo University.
文摘Layer-by-layer(LbL)assembly technology is a facile method for constructing thin film composite membrane.Herein,a novel nanofiltration(NF)membrane was prepared by LbL assembly of polyethyleneimine(PEI)and sodium lignosulfonate(LS)followed by cross-linking.The surface composition,morphology,and property of PEI/LS bilayer were detailedly investigated by FTIR/ATR,XPS,SEM,AFM,and water contact angle test.The PEI/LS bilayer full of amino and hydroxyl groups presents increased roughness and improved hydrophilicity.Moreover,the NF performance of PEI/LS LbL assembly membranes can be modulated by bilayer number,polyelectrolyte concentration,and salt content.The water flux reduced while the salt rejection greatly improved as increasing the bilayer numbers,PEI concentration,or NaCl content.More than 95%MgSO4 and MgCl2,as well as 80%NaCl can be rejected by a NF membrane prepared by 6 PEI/LS bilayers,1 wt%PEI,0.5 wt%LS,and 1 mol/L NaCl.Furthermore,this NF membrane can be used to remove more than 95%heavy metal ions(Cd2+,Zn2+,Mn2+,Cr2+,Cu2+,and Ni2+).This work proposed a promising NF membrane by using PEI/LS as low cost polyelectrolytes and facile LbL assembly method,which should receive much attention in water purification.
基金supported by the National Key Research and Development Program of China(No.2019YFA0705900)the National Natural Science Foundation of China(Nos.52127806,52173185,21734008,and 61721005)+1 种基金the Fundamental Research Funds for the Central Universities(No.226-2022-00133 and No.226-2022-00209)research start up fund from Zhejiang University。
文摘Morphology is of great significance to the performance of organic solar cells(OSCs),since appropriate morphology could not only promote the exciton dissociation,but also reduce the charge recombination.In this work,we have developed a solid additive-assisted layer-by-layer(SAA-LBL)processing to fabricate high-efficiency OSCs.By adding the solid additive of fatty acid(FA)into polymer donor PM6 solution,controllable pre-phase separation forms between PM6 and FA.This intermixed morphology facilitates the diffusion of acceptor Y6 into the donor PM6 during the LBL processing,due to the good miscibility and fast-solvation of the FA with chloroform solution dripping.Interestingly,this results in the desired morphology with refined phase-separated domain and vertical phase-separation structure to better balance the charge transport/collection and exciton dissociation.Consequently,the binary single junction OSCs based on PM6:Y6 blend reach champion power conversion efficiency(PCE)of 18.16%with SAA-LBL processing,which can be generally applicable to diverse systems,e.g.,the PM6:L8-BO-based devices and thick-film devices.The efficacy of SAA-LBL is confirmed in binary OSCs based on PM6:L8-BO,where record PCEs of 19.02%and 16.44%are realized for devices with 100 and 250 nm active layers,respectively.The work provides a simple but effective way to control the morphology for high-efficiency OSCs and demonstrates the SAA-LBL processing a promising methodology for boosting the industrial manufacturing of OSCs.
基金financially supported by the Natural Science Foundation of Chongqing,China(No.cstc2021jcyj-msxmX0943)the Chongqing Talent Plan for Young Top-Notch Talents(No.CQYC2021059217)the Foundation of Science and Technology Department of Sichuan Province(No.2022YFH0019).
文摘Layer-by-layer(LBL)assembly shows great potential in fabrication of flexible conductive cotton fabrics(FCCF)with carbon nanotubes(CNT)as conductive components but is limited because complicated chemical modification of CNT is usually required.Herein,we reported a facile and eco-friendly LBL approach to fabricating FCCF by dipping in chitosan(CS)aqueous solution and poly(sodium 4-styrenesulfonate)(PSS)wrapped CNT aqueous dispersion alternately.The FCCF with electrical conductivity higher than 30 S/m was achieved when 4 layers of CNT were coated on the cotton fabric(CF).The obtained FCCF possessed outstanding mechanical stability with electrical resistivity almost unchanged after exposure to 500 times mechanical abrasion and 500 circles of tape peeling.The FCCF showed excellent strain sensing performance with high sensitivity(with a gauge factor up to 35.1)and a fast response time(70 ms).It can be used as a strain sensor to accurately detect various human deformations such as finger bending and joint movements.The FCCF could be used as a temperature sensor in that it exhibited stable and reproducible negative temperature sensing behavior in the temperature range of 30-100℃.
基金supported by the Starting Foundation of Renmin University of China and the National Natural Science Foundation of China(No.20703066).
文摘The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.
基金Supported by the National Science Foundation of China(21174108)the Fundamental Research Funds for the Central Universities(20102020201000017)
文摘Multifunctional（poly（diallyldimethyl ammonium chloride）/sodium poly（4-styrene sulfonate）） n（（PDDA/PSS） n） thin films were fabricated by layer-by-layer assembled on the glass substrate.The monolayer silica nanoparticles were prepared on the（PDDA/PSS） n films.The SiO 2-polyelectrolyte coatings exhibit antireflection properties with low refractive index（as low as 1.22）.Interestingly,wavelengths of maximum transmittance could be well tailored by simply changing the particle size of SiO 2.A maximum transmittance of 97.03% in the visible spectral range is achieved for the particle size of 100 nm SiO 2 films.The coatings also show excellent mechanical stability and good adhesion to substrates.The easy availability of the raw materials and simplicity of the fabrication method for such films might make them be potentially useful for various applications.
基金financially supported by the National Natural Science Foundation of China(No.51273063 and 51003028)the Fundamental Research Funds for the Central Universities+1 种基金the Higher School Specialized Research Fund for the Doctoral Program(No.20110074110003)111 Project Grant(No.B08021)
文摘Spherical polyelectrolyte brushes （SPBs） consisting of polystyrene （PS） core and poly（2-aminoethyl methacrylate hydrochloride） （PAEMH） shell were prepared by photo-emulsion polymerization. Au nanoparticles （Au-NPs） with controlled size and size distribution were synthesized in situ using SPBs as nanoreactors. Via layer-by-layer deposition technique on the surface of SPBs, nano-composite particles with Au/Ag-NPs bilayer and Au/Ag/Au-NPs trilayer were prepared. The structures of the as-prepared Au/Ag multilayer SPBs were characterized by UV-Vis spectroscopy, TEM, ICP-AES and DLS. The charge reversal of the nano-composite particles observed by zeta potential confirmed the success of layer-by-layer assembly. The Au/Ag-NPs bilayer nano-composite particles showed high catalytic efficiency with an apparent activation energy of about 41.2 kJ/mol in the reduction reaction of 4-nitrophenol to 4-aminophenol in the existence of sodium borohydride monitored. The catalytic activity ofAu/Ag-NPs multilayer SPBs close to that of Au-NPs SPBs and much higher than that of Ag-NPs SPBs reveals its potential applications in cost-effective catalysts with high-performance.
