Incorporating nanomaterials into membranes will enhance wastewater treatment efficiency with their unique characteristics,such as higher permeability,thermal stability,surface roughness,hydrophilicity,and fouling cont...Incorporating nanomaterials into membranes will enhance wastewater treatment efficiency with their unique characteristics,such as higher permeability,thermal stability,surface roughness,hydrophilicity,and fouling control.In this study,the surface-modified boron nitride with phosphoric acid 2-hydroxyethyl methacrylate ester(PA/BN)was grafted with polyethylene glycol(PEG)via conventional grafting.The PEG grafted PA/BN(PEG-g-PA/BN)melt blended with polyvinylidene fluoride(PVDF)resin by using an internal mixer at different mass percentages 100%PVDF(PVDF),3%PEG-g-PA/BN+97%PVDF(97:3 BN),5%PEG-g-PA/BN+95%PVDF(95:5 BN),7%PEG-g-PA/BN+93%PVDF(93:7 BN),and 7%PEG-g-PA/BNNS+93%PVDF(93:7 BNNS).Phase inversion technique was used to cast the blended mixture into a thin membrane.The prepared membranes were analyzed with different characterization techniques to determine chemical composition,crystallinity,morphology,and thermal properties.The prepared composite membrane was evaluated in terms of water permeability,anti-fouling resistance,and solute rejection efficiency with deionized water,bovine serum albumin,and arsenic solution as well.PVDF membranes show high water flux and porosity.The water flux and porosity of the blends decrease as the percentage of PEG-g-PA/BN increases.However,the highest removal capacity for arsenic was observed at 93:7 BN.The adsorption of arsenic ions takes place via complexation with PA/BN in the PVDF matrix.This was confirmed with field emission scanning electron microscopyeenergy-dispersive X-ray analysis and X-ray photoelectron spectroscopy analyses.展开更多
Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coat...Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coating was synthesized on Ti O2-coated Mg alloy by physical vapour deposition（PVD） assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction（XRD） analysis and field emission scanning electron microscopy（FE-SEM） images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O2 film with a thickness of 1 μm. The potentiodynamic polarization（PDP） and electrochemical impedance spectroscopy（EIS） tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid（SBF） solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone（3.86 mm） towards Escherichia coli（E. coli） compared with the Ti O2-coated Mg alloy（2.61 mm）. The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.展开更多
Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection foll...Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection following surgical implants. The aim of present study was to synthesize and in-vitro characterize Mg-based scaffolds containing silver for bone tissue engineering. Porous Mg-based scaffolds with four silver concentrations (i.e., 0, 0.5 wt.%, 1 wt.%, and 2 wt.%), denoted by Mg?Ca?Mn-Zn-xAg (MCMZ?xAg)(where x is the silver concentration), were fabricated by the space holder technique. The effects of silver concentration on pore architecture, mechanical properties, bioactivity, and zone of bacterial inhibition were investigated in-vitro. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence microscopy were utilized to characterize the obtained scaffolds. In-vitro corrosion test results indicated that the MCMZ scaffolds with lower silver content were more resistant to corrosion than those enriched with higher amounts of silver. Examination of the antibacterial activity showed that the MCMZ?Ag scaffolds exhibited superb potential with respect to suppressing the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in the inhibition zone around the MCMZ?Ag scaffolds, with increasing in the amount of incorporated silver;however, higher amounts of silver increased the cytotoxicity. Taken together, the results of this study demonstrate that the porous 0.5 wt.% Ag-containing scaffolds with interconnected pores, adequate mechanical properties, antibacterial activity, and cell adhesion are promising with respect to the repair and substitution of damaged and diseased bones.展开更多
In this study,a quantitative performance of three commercial polyamide nanofiltration(NF) membranes(i.e.,NF,NF90,and NF270) for phosphorus removal under different feed conditions was investigated.The experiments were ...In this study,a quantitative performance of three commercial polyamide nanofiltration(NF) membranes(i.e.,NF,NF90,and NF270) for phosphorus removal under different feed conditions was investigated.The experiments were conducted at different feed phosphorus concentrations(2.5,5,10,and 15 mg·L^-1) and elevated pHs(pH 1.5,5,10,and 13.5) at a constant feed pressure of 1 MPa using a dead-end filtration cell.Membrane rejection against total phosphorus generally increased with increasing phosphorus concentration regardless of membrane type.In contrast,the permeate flux for all the membranes only decreased slightly with increasing phosphorus concentration.The results also showed that the phosphorus rejections improved while water flux remained almost unchanged with increasing feed solution pH.When the three membranes were exposed to strong pHs(pH 1.5 and 13.5) for a longer duration(up to 6 weeks)it was found that the rejection capability and water flux of the membranes remained very similar throughout the duration,except for NF membrane with marginal decrement in phosphorus rejection.Adsorption study also revealed that more phosphorus was adsorbed onto the membrane structure at alkaline conditions(pH 10 and 13.5) compared to the same membranes tested at lower pHs(pH 1.5 and 5).In eonelusion,NF270 membrane outperformed Nf and NF90 membranes owing to its desirable performance of water flux and phosphorus rejection particularly under strong alkali solution.The NF270 membrane achieved 14.0 L·m^-2·h^-1 and 96.5% rejection against 10 mg·L^-1 phosphorus solution with a pH value of 13.5 at the applied pressure of 1 MPa.展开更多
The addition of nanoscale additions to magnesium(Mg)based alloys can boost mechanical characteristics without noticeably decreasing ductility.Since Mg is the lightest structural material,the Mg-based nanocomposites(NC...The addition of nanoscale additions to magnesium(Mg)based alloys can boost mechanical characteristics without noticeably decreasing ductility.Since Mg is the lightest structural material,the Mg-based nanocomposites(NCs)with improved mechanical properties are appealing materials for lightweight structural applications.In contrast to conventional Mg-based composites,the incorporation of nano-sized reinforcing particles noticeably boosts the strength of Mg-based nanocomposites without significantly reducing the formability.The present article reviews Mg-based metal matrix nanocomposites(MMNCs)with metallic and ceramic additions,fabricated via both solid-based(sintering and powder metallurgy)and liquid-based(disintegrated melt deposition)technologies.It also reviews strengthening models and mechanisms that have been proposed to explain the improved mechanical characteristics of Mg-based alloys and nanocomposites.Further,synergistic strengthening mecha-nisms in Mg matrix nanocomposites and the dominant equations for quantitatively predicting mechanical properties are provided.Furthermore,this study offers an overview of the creep and fatigue behavior of Mg-based alloys and nanocomposites using both traditional(uniaxial)and depth-sensing indentation techniques.The potential applications of magnesium-based alloys and nanocomposites are also surveyed.展开更多
In the present work,a chemically modified electrode has been fabricated utilizing Bi_(2)O_(3)/ZnO nanocomposite.The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and ...In the present work,a chemically modified electrode has been fabricated utilizing Bi_(2)O_(3)/ZnO nanocomposite.The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and morphological properties by using XRD,FESEM,EDAX,HRTEM and XPS techniques.The results clearly indicated co-existence of Bi_(2)O_(3) and ZnO in the nanocomposite with chemical interaction between them.Bi_(2)O_(3)/ZnO nanocomposite based glassy carbon electrode(GCE)was utilized for sensitive voltammetric detection of an anti-biotic drug(balofloxacin).The modification amplified the electroactive surface area of the sensor,thus providing more sites for oxidation of analyte.Cyclic and square wave voltammograms revealed that Bi_(2)O_(3)/ZnO modified electrode provides excellent electrocatalytic action towards balofloxacin oxidation.The current exhibited a wide linear response in concentration range of 150e1000 nM and detection limit of 40.5 nM was attained.The modified electrode offered advantages in terms of simplicity of preparation,fair stability(RSD 1.45%),appreciable reproducibility(RSD 2.03%)and selectivity.The proposed sensor was applied for determining balofloxacin in commercial pharmaceutical formulations and blood serum samples with the mean recoveries of 99.09% and 99.5%,respectively.展开更多
Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly l...Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.展开更多
The discharge of industrial effluent containing heavy metal ions would cause water pollution if such effluent is not properly treated.In this work,the performance of emerging nanofiltration(NF)like-forward osmosis(FO)...The discharge of industrial effluent containing heavy metal ions would cause water pollution if such effluent is not properly treated.In this work,the performance of emerging nanofiltration(NF)like-forward osmosis(FO)membrane was evaluated for its efficiency to remove copper ion from water.Conventionally,copper ion is removed from aqueous solution via adsorption and/or ion-exchange method.The engineered osmosis method as proposed in this work considered four commercial NF membranes(i.e.,NF90,DK,NDX and PFO)where their separation performances were accessed using synthetic water sample containing 100 mg·L-1 copper ion under FO and pressure retarded osmosis(PRO)orientation.The findings indicated that all membranes could achieve almost complete removal of copper regardless of membrane orientation without applying external driving force.The high removal rates were in good agreement with the outcomes of the membranes tested under pressuredriven mode at 1 MPa.The use of appropriate salts as draw solutes enabled the NF membranes to be employed in engineered osmosis process,achieving a relatively low reverse solute flux.The findings showed that the best performing membrane is PFO membrane in which it achieved N 99.4%copper rejection with very minimum reverse solute flux of<1 g·m-2·h-1.展开更多
Zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacte...Zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%（x = 0.05）. However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli（Gram negative bacteria）cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.展开更多
Rechargeable lithium-ion batteries(LIBs)are the dominant technology for secondary batteries due to their exceptional cycle life and superior energy density.However,for large-scale energy storage applications,sodium-io...Rechargeable lithium-ion batteries(LIBs)are the dominant technology for secondary batteries due to their exceptional cycle life and superior energy density.However,for large-scale energy storage applications,sodium-ion batteries(SIBs)are considered a promising alternative owing to their abundant sodium resources,low cost,and relatively high energy density.SIBs display gorgeous application prospects as a superior alternative to extensively commercialized LIBs.Problems such as the low performance of suitable anode materials in large-scale SIBs,due to the large size and sluggish kinetics of Na+have limited their development.So,further progress in SIBs performance is still needed in terms of fast-charging capability,cyclic stability,and power/energy densities.In this review,the latest progress in the preparation strategies and application challenges of SIBs is summarized,focusing on the fundamentals of the design principles and sodium storage mechanisms in various classes of anode materials including carbon-based,inorganic,organic,and MXene-derived systems.Structural and surface engineering techniques,electrochemical performance evaluation,machine learning(ML),and artificial intelligence(AI)are also discussed to elucidate ion storage mechanisms and accelerate anode material design for next-generation SIBs.展开更多
Magnesium(Mg)and its alloys are revolutionizing the field of interventional surgeries in the medical industry.Their high biocompatibility,biodegradability,and a similar elastic modulus to natural bone make porous Mg-b...Magnesium(Mg)and its alloys are revolutionizing the field of interventional surgeries in the medical industry.Their high biocompatibility,biodegradability,and a similar elastic modulus to natural bone make porous Mg-based structures potential candidates for orthopedic implants and tissue engineering scaffolding.However,fabricating and machining porous Mg-based structures is challenging due to their complexity and difficulties in achieving uniform or gradient porosity.This review aims to thoroughly explore various fabrication procedures used to create metallic scaffolds,with a specific focus on those made from Mg-based alloys.Both traditional manufacturing techniques,including the directional solidification of metal-gas eutectic technique,pattern casting,methods using space holders,and modern fabrication methods,which are based on additive manufacturing,are covered in this review article.Furthermore,the paper highlights the most important findings of recent studies on Mg-based scaffolds in terms of their microstructure specifications,mechanical properties,degradation and corrosion behavior,antibacterial activity,and biocompatibility(both in vivo and in vitro).While extensive research has been conducted to optimize manufacturing parameters and qualities of Mg-based scaffolds for use in biomedical applications,specifically for bone tissue engineering applications,further investigation is needed to fabricate these scaffolds with specific properties,such as high resistance to corrosion,good antibacterial properties,osteoconductivity,osteoinductivity,and the ability to elicit a favorable response from osteoblast-like cell lines.The review concludes with recommendations for future research in the field of medical applications.展开更多
Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts.Despite their very promising ...Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts.Despite their very promising separation performance,chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite.The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer.From material point of view,a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement.Various strategies,particularly those involved membrane material optimization and surface modifications,have been established to address this issue.This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide.The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and postfabrication membrane modifications using a broad range of functional materials.The challenges and future directions in this field are also highlighted.展开更多
Controlled growth and careful characterization of cobalt ferrite nanoparticles for antibacterial applica- tions are challenging. Copper-substituted cobalt ferrite nanoparticles （CuxCo1-xFe2O4）, where x = 0.0, 0.3, 0...Controlled growth and careful characterization of cobalt ferrite nanoparticles for antibacterial applica- tions are challenging. Copper-substituted cobalt ferrite nanoparticles （CuxCo1-xFe2O4）, where x = 0.0, 0.3, 0.5, 0.7 and 1.0, were synthesized using an economical and simple co-precipitation technique. The crys- tal structure and antibacterial properties of the samples as a function of Cu-substituted content were systematically studied. With increasing Cu concentration, the nanopartide size decreased from ~30 to ~20 nm. The Fourier transform infra-red spectra exhibit two prominent fundamental absorption bands, at ~595 and 419 cm^-1. These bands correspond to intrinsic stretching vibrations of metals at tetrahedral and octahedral sites, respectively. The Raman scattering results reveal that increasing the Cu content enhances the local disorder at both tetrahedral and octahedral sub lattices. The results indicate that the substitution of Co with Cu in cobalt ferrite nanoparticles strongly influences the microstructure, crystal structure, and oarticle diameter, and also improves the antibacterial properties.展开更多
Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique,followed by a grafting with fluoroalkylsilane(FAS).The ...Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique,followed by a grafting with fluoroalkylsilane(FAS).The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes(gas permeation,mechanical strength,pore size,porosity,tortuosity,morphology,and contact angle)by the addition of alumina(Al2O3)to the pure kaolin with mono or multiparticle sizes.By varying the overall loading and particle size of alumina addition,different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange.The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140°after grafting.Kaolin-alumina-4,one of the hollow fibres fabricated in this work,achieved a mean pore size of 0.25μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10^(-5)mol·m^(-2)·Pa^(-1)·s^(-1),which makes the hollow fibre most suitable for the membrane contactor application.展开更多
Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback fr...Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback from environments, in which optical fibers act as a signal carrier. A novel Ag coated intensity modulated optical fiber sensor based on refractive index changes using IR and UV-Vis （UV-visible） light sources is proposed. The sensor with an IR light source has higher sensitivity compared to a UV-Vis source. When the refractive index is en- hanced to 1.38, the normalized intensity of IR and UV-Vis light diminishes to 0.2 and 0.8. respectively.展开更多
Insufficient hole cleaning,cutting suspension,clay swelling,and filtrate invasion of the formation might result from inadequate drilling mud properties.For effective drilling and wellbore stability,water-based mud(WBM...Insufficient hole cleaning,cutting suspension,clay swelling,and filtrate invasion of the formation might result from inadequate drilling mud properties.For effective drilling and wellbore stability,water-based mud(WBM)rheology,lubricity,filtration,and shale inhibition must be optimized and controlled.WBMs react with clays and cause time-dependent borehole issues,which is their principal drawback.Moreover,prolonged exposure destroys certain WBM components,resulting in minimal mud properties.These indicate the need for multifunctional additives to improve WBMs.Thus,this study developed WBM systems employing graphene nanoplatelets(GNPs)and locally acquired discarded coconut shells to overcome severe drilling challenges.By adding triton-X100 to coconut shell-based graphene(GN-CS),a greater dispersion of modified graphene(GN-TX)particles was produced.Characterization,rheology,lubricity,inhibition,and filtration tests were performed on these GN-CS and GN-TX at concentrations of 0.125,0.25,0.375,and 0.50 wt%.Furthermore,biotoxicity,biodegradability,and heavy metal content experiments were performed to study the environmental impact of GN-CS and GN-TX.The results showed that GN-TX had good thermal resistance up to 300℃ with only a 10%loss in weight.Both EDX and FTIR tests showed that the epoxy,carboxyl,and hydroxyl groups are in the GNP-based materials'basal plane.The GN-CS and GN-TX had better fluid properties,including better lubricity,rheology,filtration,and inhibition over the base mud,and the optimal rheological model of the drilling muds was the Herschel Buckley model.The GN-TX(modified)decreased the fluid loss to 20.6e14.3 mL from 24.6 mL at 353 K,whereas the GN-CS(unmodified)reduced it to 21.3e16.7 mL.GN-TX and GN-CS decreased the coefficient of friction of WBM from 0.47 to 0.55 to 0.25e0.41 and 0.33e0.44,respec-tively,from 298 to 353 K.In addition,0.50 wt%of GN-CS and GN-TX reduced the shale pellet swelling height to 5.4%and 5.6%,respectively,from 8.8%.Moreover,the EC 50 values for GN-CS and GN-TX were about 54,000 mg/L and the BOD/COD ratio was about 47%.These results show that the GNP-based products are safe and biodegradable.The GNP-based materials have promising prospects for drilling in environmentally sensitive formations.展开更多
基金financially supported Faculty of Chemical and Energy Engineering,Universiti Teknologi Malaysia under Fundamental Research Grant Scheme,(R.J130000.7846.4F981).
文摘Incorporating nanomaterials into membranes will enhance wastewater treatment efficiency with their unique characteristics,such as higher permeability,thermal stability,surface roughness,hydrophilicity,and fouling control.In this study,the surface-modified boron nitride with phosphoric acid 2-hydroxyethyl methacrylate ester(PA/BN)was grafted with polyethylene glycol(PEG)via conventional grafting.The PEG grafted PA/BN(PEG-g-PA/BN)melt blended with polyvinylidene fluoride(PVDF)resin by using an internal mixer at different mass percentages 100%PVDF(PVDF),3%PEG-g-PA/BN+97%PVDF(97:3 BN),5%PEG-g-PA/BN+95%PVDF(95:5 BN),7%PEG-g-PA/BN+93%PVDF(93:7 BN),and 7%PEG-g-PA/BNNS+93%PVDF(93:7 BNNS).Phase inversion technique was used to cast the blended mixture into a thin membrane.The prepared membranes were analyzed with different characterization techniques to determine chemical composition,crystallinity,morphology,and thermal properties.The prepared composite membrane was evaluated in terms of water permeability,anti-fouling resistance,and solute rejection efficiency with deionized water,bovine serum albumin,and arsenic solution as well.PVDF membranes show high water flux and porosity.The water flux and porosity of the blends decrease as the percentage of PEG-g-PA/BN increases.However,the highest removal capacity for arsenic was observed at 93:7 BN.The adsorption of arsenic ions takes place via complexation with PA/BN in the PVDF matrix.This was confirmed with field emission scanning electron microscopyeenergy-dispersive X-ray analysis and X-ray photoelectron spectroscopy analyses.
文摘Mg-based alloys received significant attention for temporary implant applications while, their applications have been limited by high degradation rate. Therefore, silver-zeolite doped hydroxyapatite（Ag-Zeo-HAp） coating was synthesized on Ti O2-coated Mg alloy by physical vapour deposition（PVD） assisted electrodeposition technique to decrease the degradation rate of Mg alloy. X-ray diffraction（XRD） analysis and field emission scanning electron microscopy（FE-SEM） images showed the formation of a uniform and compact layer of Ag-Zeo-HAp with a thickness of 15 μm on the Ti O2 film with a thickness of 1 μm. The potentiodynamic polarization（PDP） and electrochemical impedance spectroscopy（EIS） tests indicated that corrosion resistance of Mg-Ca alloy was considerably increased by the Ag-Zeo-HAp coating. The bioactivity test in the simulated body fluid（SBF） solution showed that a dense and homogeneous bonelike apatite layer was formed on the Ag-Zeo-HAp surface after 14 d. Investigation of antibacterial activity via disk diffusion and spread plate methods showed that the Ag-Zeo-HAp coating had a significantly larger inhibition zone（3.86 mm） towards Escherichia coli（E. coli） compared with the Ti O2-coated Mg alloy（2.61 mm）. The Ag-Zeo-HAp coating showed high antibacterial performance, good bioactivity, and high corrosion resistance which make it a perfect coating material for biomedical applications.
基金partial financial support to this research from the Saskatchewan Health Research Foundation (SHRF)
文摘Infection is a major potential complication in the clinical treatment of bone injuries. Magnesium (Mg)-based composites are biodegradable and antibacterial biomaterials that have been employed to reduce infection following surgical implants. The aim of present study was to synthesize and in-vitro characterize Mg-based scaffolds containing silver for bone tissue engineering. Porous Mg-based scaffolds with four silver concentrations (i.e., 0, 0.5 wt.%, 1 wt.%, and 2 wt.%), denoted by Mg?Ca?Mn-Zn-xAg (MCMZ?xAg)(where x is the silver concentration), were fabricated by the space holder technique. The effects of silver concentration on pore architecture, mechanical properties, bioactivity, and zone of bacterial inhibition were investigated in-vitro. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence microscopy were utilized to characterize the obtained scaffolds. In-vitro corrosion test results indicated that the MCMZ scaffolds with lower silver content were more resistant to corrosion than those enriched with higher amounts of silver. Examination of the antibacterial activity showed that the MCMZ?Ag scaffolds exhibited superb potential with respect to suppressing the growth of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), in the inhibition zone around the MCMZ?Ag scaffolds, with increasing in the amount of incorporated silver;however, higher amounts of silver increased the cytotoxicity. Taken together, the results of this study demonstrate that the porous 0.5 wt.% Ag-containing scaffolds with interconnected pores, adequate mechanical properties, antibacterial activity, and cell adhesion are promising with respect to the repair and substitution of damaged and diseased bones.
基金Supported by the Ministry of Education(MoE)Malaysia to Universiti Teknologi Malaysia(UTM)under the grant of Higher Institution Centre of Excellence(HICoE)(R.J090301.7846.4J175)Universiti Tunku Abdul Rahman(UTAR)under the research publication scheme(6251/K02)
文摘In this study,a quantitative performance of three commercial polyamide nanofiltration(NF) membranes(i.e.,NF,NF90,and NF270) for phosphorus removal under different feed conditions was investigated.The experiments were conducted at different feed phosphorus concentrations(2.5,5,10,and 15 mg·L^-1) and elevated pHs(pH 1.5,5,10,and 13.5) at a constant feed pressure of 1 MPa using a dead-end filtration cell.Membrane rejection against total phosphorus generally increased with increasing phosphorus concentration regardless of membrane type.In contrast,the permeate flux for all the membranes only decreased slightly with increasing phosphorus concentration.The results also showed that the phosphorus rejections improved while water flux remained almost unchanged with increasing feed solution pH.When the three membranes were exposed to strong pHs(pH 1.5 and 13.5) for a longer duration(up to 6 weeks)it was found that the rejection capability and water flux of the membranes remained very similar throughout the duration,except for NF membrane with marginal decrement in phosphorus rejection.Adsorption study also revealed that more phosphorus was adsorbed onto the membrane structure at alkaline conditions(pH 10 and 13.5) compared to the same membranes tested at lower pHs(pH 1.5 and 5).In eonelusion,NF270 membrane outperformed Nf and NF90 membranes owing to its desirable performance of water flux and phosphorus rejection particularly under strong alkali solution.The NF270 membrane achieved 14.0 L·m^-2·h^-1 and 96.5% rejection against 10 mg·L^-1 phosphorus solution with a pH value of 13.5 at the applied pressure of 1 MPa.
基金H.R.Bakhsheshi-Rad and S.Sharif would like to acknowledge UTM Research Management for the financial support through the funding(Q.J130000.2409.08G37).
文摘The addition of nanoscale additions to magnesium(Mg)based alloys can boost mechanical characteristics without noticeably decreasing ductility.Since Mg is the lightest structural material,the Mg-based nanocomposites(NCs)with improved mechanical properties are appealing materials for lightweight structural applications.In contrast to conventional Mg-based composites,the incorporation of nano-sized reinforcing particles noticeably boosts the strength of Mg-based nanocomposites without significantly reducing the formability.The present article reviews Mg-based metal matrix nanocomposites(MMNCs)with metallic and ceramic additions,fabricated via both solid-based(sintering and powder metallurgy)and liquid-based(disintegrated melt deposition)technologies.It also reviews strengthening models and mechanisms that have been proposed to explain the improved mechanical characteristics of Mg-based alloys and nanocomposites.Further,synergistic strengthening mecha-nisms in Mg matrix nanocomposites and the dominant equations for quantitatively predicting mechanical properties are provided.Furthermore,this study offers an overview of the creep and fatigue behavior of Mg-based alloys and nanocomposites using both traditional(uniaxial)and depth-sensing indentation techniques.The potential applications of magnesium-based alloys and nanocomposites are also surveyed.
文摘In the present work,a chemically modified electrode has been fabricated utilizing Bi_(2)O_(3)/ZnO nanocomposite.The nanocomposite was synthesized by simple sonochemical method and characterized for its structural and morphological properties by using XRD,FESEM,EDAX,HRTEM and XPS techniques.The results clearly indicated co-existence of Bi_(2)O_(3) and ZnO in the nanocomposite with chemical interaction between them.Bi_(2)O_(3)/ZnO nanocomposite based glassy carbon electrode(GCE)was utilized for sensitive voltammetric detection of an anti-biotic drug(balofloxacin).The modification amplified the electroactive surface area of the sensor,thus providing more sites for oxidation of analyte.Cyclic and square wave voltammograms revealed that Bi_(2)O_(3)/ZnO modified electrode provides excellent electrocatalytic action towards balofloxacin oxidation.The current exhibited a wide linear response in concentration range of 150e1000 nM and detection limit of 40.5 nM was attained.The modified electrode offered advantages in terms of simplicity of preparation,fair stability(RSD 1.45%),appreciable reproducibility(RSD 2.03%)and selectivity.The proposed sensor was applied for determining balofloxacin in commercial pharmaceutical formulations and blood serum samples with the mean recoveries of 99.09% and 99.5%,respectively.
文摘Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.
基金the financial support provided by the Malaysian Ministry of Education(Mo E)under the Fundamental Research Grant Scheme(Grant No.R.J130000.7851.5F017)Universiti Teknologi Malaysia(UTM)under the UTMSHINE Signature Grant(Grant No.Q.J130000.2451.07G79).
文摘The discharge of industrial effluent containing heavy metal ions would cause water pollution if such effluent is not properly treated.In this work,the performance of emerging nanofiltration(NF)like-forward osmosis(FO)membrane was evaluated for its efficiency to remove copper ion from water.Conventionally,copper ion is removed from aqueous solution via adsorption and/or ion-exchange method.The engineered osmosis method as proposed in this work considered four commercial NF membranes(i.e.,NF90,DK,NDX and PFO)where their separation performances were accessed using synthetic water sample containing 100 mg·L-1 copper ion under FO and pressure retarded osmosis(PRO)orientation.The findings indicated that all membranes could achieve almost complete removal of copper regardless of membrane orientation without applying external driving force.The high removal rates were in good agreement with the outcomes of the membranes tested under pressuredriven mode at 1 MPa.The use of appropriate salts as draw solutes enabled the NF membranes to be employed in engineered osmosis process,achieving a relatively low reverse solute flux.The findings showed that the best performing membrane is PFO membrane in which it achieved N 99.4%copper rejection with very minimum reverse solute flux of<1 g·m-2·h-1.
基金Project supported by the Universiti Teknologi Malaysia(UTM)(Grant No.R.J1300000.7809.4F626)RMC for postdoctoral grants
文摘Zn（1-x）Cux O（x=0.00, 0.01, 0.03, and 0.05） nanoparticles are synthesized via the sol-gel technique using gelatin and nitrate precursors. The impact of copper concentration on the structural, optical, and antibacterial properties of these nanoparticles is demonstrated. Powder x-ray diffraction investigations have illustrated the organized Cu doping into ZnO nanoparticles up to Cu concentration of 5%（x = 0.05）. However, the peak corresponding to CuO for x= 0.01 is not distinguishable. The images of field emission scanning electron microscopy demonstrate the existence of a nearly spherical shape with a size in the range of 30–52 nm. Doping Cu creates the Cu–O–Zn on the surface and results in a decrease in the crystallite size. Photoluminescence and absorption spectra display that doping Cu causes an increment in the energy band gap. The antibacterial activities of the nanoparticles are examined against Escherichia coli（Gram negative bacteria）cultures using optical density at 600 nm and a comparison of the size of inhibition zone diameter. It is found that both pure and doped ZnO nanoparticles indicate appropriate antibacterial activity which rises with Cu doping.
基金supporting this research under the Geran Penyelidikan Hi-Tech(F4)[Cost centre no.:R.J130000.7113.07E71&Q.J130000.4654.00Q23].
文摘Rechargeable lithium-ion batteries(LIBs)are the dominant technology for secondary batteries due to their exceptional cycle life and superior energy density.However,for large-scale energy storage applications,sodium-ion batteries(SIBs)are considered a promising alternative owing to their abundant sodium resources,low cost,and relatively high energy density.SIBs display gorgeous application prospects as a superior alternative to extensively commercialized LIBs.Problems such as the low performance of suitable anode materials in large-scale SIBs,due to the large size and sluggish kinetics of Na+have limited their development.So,further progress in SIBs performance is still needed in terms of fast-charging capability,cyclic stability,and power/energy densities.In this review,the latest progress in the preparation strategies and application challenges of SIBs is summarized,focusing on the fundamentals of the design principles and sodium storage mechanisms in various classes of anode materials including carbon-based,inorganic,organic,and MXene-derived systems.Structural and surface engineering techniques,electrochemical performance evaluation,machine learning(ML),and artificial intelligence(AI)are also discussed to elucidate ion storage mechanisms and accelerate anode material design for next-generation SIBs.
基金U.S.National Institute of Health-National Heart,Lung,and Blood Institute Grants R56HL163552 and R01HL168696 are acknowledged by J W D for funding work on biodegradable metals.
文摘Magnesium(Mg)and its alloys are revolutionizing the field of interventional surgeries in the medical industry.Their high biocompatibility,biodegradability,and a similar elastic modulus to natural bone make porous Mg-based structures potential candidates for orthopedic implants and tissue engineering scaffolding.However,fabricating and machining porous Mg-based structures is challenging due to their complexity and difficulties in achieving uniform or gradient porosity.This review aims to thoroughly explore various fabrication procedures used to create metallic scaffolds,with a specific focus on those made from Mg-based alloys.Both traditional manufacturing techniques,including the directional solidification of metal-gas eutectic technique,pattern casting,methods using space holders,and modern fabrication methods,which are based on additive manufacturing,are covered in this review article.Furthermore,the paper highlights the most important findings of recent studies on Mg-based scaffolds in terms of their microstructure specifications,mechanical properties,degradation and corrosion behavior,antibacterial activity,and biocompatibility(both in vivo and in vitro).While extensive research has been conducted to optimize manufacturing parameters and qualities of Mg-based scaffolds for use in biomedical applications,specifically for bone tissue engineering applications,further investigation is needed to fabricate these scaffolds with specific properties,such as high resistance to corrosion,good antibacterial properties,osteoconductivity,osteoinductivity,and the ability to elicit a favorable response from osteoblast-like cell lines.The review concludes with recommendations for future research in the field of medical applications.
基金support provided by the Ministry of Higher Education Malaysia under Malaysia Research University Network Grant(Grant No.4L862)the research support provided by Universiti Teknologi Malaysia.
文摘Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts.Despite their very promising separation performance,chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite.The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer.From material point of view,a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement.Various strategies,particularly those involved membrane material optimization and surface modifications,have been established to address this issue.This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide.The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and postfabrication membrane modifications using a broad range of functional materials.The challenges and future directions in this field are also highlighted.
文摘Controlled growth and careful characterization of cobalt ferrite nanoparticles for antibacterial applica- tions are challenging. Copper-substituted cobalt ferrite nanoparticles （CuxCo1-xFe2O4）, where x = 0.0, 0.3, 0.5, 0.7 and 1.0, were synthesized using an economical and simple co-precipitation technique. The crys- tal structure and antibacterial properties of the samples as a function of Cu-substituted content were systematically studied. With increasing Cu concentration, the nanopartide size decreased from ~30 to ~20 nm. The Fourier transform infra-red spectra exhibit two prominent fundamental absorption bands, at ~595 and 419 cm^-1. These bands correspond to intrinsic stretching vibrations of metals at tetrahedral and octahedral sites, respectively. The Raman scattering results reveal that increasing the Cu content enhances the local disorder at both tetrahedral and octahedral sub lattices. The results indicate that the substitution of Co with Cu in cobalt ferrite nanoparticles strongly influences the microstructure, crystal structure, and oarticle diameter, and also improves the antibacterial properties.
基金support from Universiti Teknologi Malaysia under Research University Grant Tier 1(Project No.Q.J130000.2546.12H25)Flagship UTMShine(Project No.Q.J130000.2446.03G29)Nippon Sheet Glass Foundation for Materials Science and Engineering under Overseas Research Grant Scheme(Project No.Q.J130000.2446.03G29)。
文摘Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique,followed by a grafting with fluoroalkylsilane(FAS).The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes(gas permeation,mechanical strength,pore size,porosity,tortuosity,morphology,and contact angle)by the addition of alumina(Al2O3)to the pure kaolin with mono or multiparticle sizes.By varying the overall loading and particle size of alumina addition,different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange.The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140°after grafting.Kaolin-alumina-4,one of the hollow fibres fabricated in this work,achieved a mean pore size of 0.25μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10^(-5)mol·m^(-2)·Pa^(-1)·s^(-1),which makes the hollow fibre most suitable for the membrane contactor application.
基金supported by the Universiti Teknologi Malaysia,AMTEC(No.R.J130000.7609.4C112)the Frontier Material Research Alliance
文摘Miniature optical fiber sensors with thin films as sensitive elements could open new fields for optical fiber sensor applications. Thin films work as sensitive elements and a transducer to get response and feedback from environments, in which optical fibers act as a signal carrier. A novel Ag coated intensity modulated optical fiber sensor based on refractive index changes using IR and UV-Vis （UV-visible） light sources is proposed. The sensor with an IR light source has higher sensitivity compared to a UV-Vis source. When the refractive index is en- hanced to 1.38, the normalized intensity of IR and UV-Vis light diminishes to 0.2 and 0.8. respectively.
文摘Insufficient hole cleaning,cutting suspension,clay swelling,and filtrate invasion of the formation might result from inadequate drilling mud properties.For effective drilling and wellbore stability,water-based mud(WBM)rheology,lubricity,filtration,and shale inhibition must be optimized and controlled.WBMs react with clays and cause time-dependent borehole issues,which is their principal drawback.Moreover,prolonged exposure destroys certain WBM components,resulting in minimal mud properties.These indicate the need for multifunctional additives to improve WBMs.Thus,this study developed WBM systems employing graphene nanoplatelets(GNPs)and locally acquired discarded coconut shells to overcome severe drilling challenges.By adding triton-X100 to coconut shell-based graphene(GN-CS),a greater dispersion of modified graphene(GN-TX)particles was produced.Characterization,rheology,lubricity,inhibition,and filtration tests were performed on these GN-CS and GN-TX at concentrations of 0.125,0.25,0.375,and 0.50 wt%.Furthermore,biotoxicity,biodegradability,and heavy metal content experiments were performed to study the environmental impact of GN-CS and GN-TX.The results showed that GN-TX had good thermal resistance up to 300℃ with only a 10%loss in weight.Both EDX and FTIR tests showed that the epoxy,carboxyl,and hydroxyl groups are in the GNP-based materials'basal plane.The GN-CS and GN-TX had better fluid properties,including better lubricity,rheology,filtration,and inhibition over the base mud,and the optimal rheological model of the drilling muds was the Herschel Buckley model.The GN-TX(modified)decreased the fluid loss to 20.6e14.3 mL from 24.6 mL at 353 K,whereas the GN-CS(unmodified)reduced it to 21.3e16.7 mL.GN-TX and GN-CS decreased the coefficient of friction of WBM from 0.47 to 0.55 to 0.25e0.41 and 0.33e0.44,respec-tively,from 298 to 353 K.In addition,0.50 wt%of GN-CS and GN-TX reduced the shale pellet swelling height to 5.4%and 5.6%,respectively,from 8.8%.Moreover,the EC 50 values for GN-CS and GN-TX were about 54,000 mg/L and the BOD/COD ratio was about 47%.These results show that the GNP-based products are safe and biodegradable.The GNP-based materials have promising prospects for drilling in environmentally sensitive formations.
