In response to new European Union regulations,studies are underway to mitigate accumulation of toxic cadmium(Cd)in cacao(Theobroma cacao,Tc).This study advances such research with Cd isotope analyses of 19 genetically...In response to new European Union regulations,studies are underway to mitigate accumulation of toxic cadmium(Cd)in cacao(Theobroma cacao,Tc).This study advances such research with Cd isotope analyses of 19 genetically diverse cacao clones and yeast transformed to express cacao natural resistance-associated macrophage protein(NRAMP5)and heavy metal ATPases(HMAs).The plants were enriched in light Cd isotopes relative to the hydroponic solution withΔ^(114/110)Cd_(tot-sol)=−0.22±0.08‰.Leaves show a systematic enrichment of isotopically heavy Cd relative to total plants,in accord with closed-system isotope fractionation ofΔ^(114/110)C_(dseq-mob)=−0.13‰,by sequestering isotopically light Cd in roots/stems and mobilisation of remaining Cd to leaves.The findings demonstrate that(i)transfer of Cd between roots and leaves is primarily unidirectional;(ii)different clones utilise similar pathways for Cd sequestration,which differ from those of other studied plants;(iii)clones differ in their efficiency of Cd sequestration.Transgenic yeast that expresses TcNRAMP5(T.cacao natural resistance-associated macrophage gene)had isotopically lighter Cd than did cacao.This suggests that NRAMP5 transporters constitute an important pathway for uptake of Cd by cacao.Cd isotope signatures of transgenic yeast expressing HMA-family proteins suggest that they may contribute to Cd sequestration.The data are the first to record isotope fractionation induced by transporter proteins in vivo.展开更多
Deforestation and associated ecological disturbances are the issues of global concern.Researchers have investigated a number of driving forces which accelerate the rate of deforestation at local and regional levels.Th...Deforestation and associated ecological disturbances are the issues of global concern.Researchers have investigated a number of driving forces which accelerate the rate of deforestation at local and regional levels.These include poverty,population growth,market demand and prices,political instability,agricultural expansion and changes in property right and ownership regimes.This paper seeks to explore the impacts of population growth,changing tenure system and other socioeconomic factors on the forest cover of Roghani Valley,located in Hindu Raj Mountains,Northern Pakistan.The present study is mainly based on information collected through participatory observation,selfadministered interviews and questionnaire survey.Geographical Information System(GIS) database is also used for mapping and quantification.The results reveal that in the past three to four decades the study area has been subjected to severe deforestation and about half of the forest area has been converted into barren land.Thus,the area under natural forests decreased from 2099 to 1444 hectares in four decades.This large-scale deforestation is attributed to both proximate and under lying causes particularly traditional land tenure system and demographic development.Consequently,forest resources have been degraded and a number of plant species have disappeared from the forests of the study area while several others are in the process of disappearance.展开更多
Live video streaming is one of the newly emerged services over the Internet that has attracted immense interest of the service providers.Since Internet was not designed for such services during its inception,such a se...Live video streaming is one of the newly emerged services over the Internet that has attracted immense interest of the service providers.Since Internet was not designed for such services during its inception,such a service poses some serious challenges including cost and scalability.Peer-to-Peer(P2P)Internet Protocol Television(IPTV)is an application-level distributed paradigm to offer live video contents.In terms of ease of deployment,it has emerged as a serious alternative to client server,Content Delivery Network(CDN)and IP multicast solutions.Nevertheless,P2P approach has struggled to provide the desired streaming quality due to a number of issues.Stability of peers in a network is one of themajor issues among these.Most of the existing approaches address this issue through older-stable principle.This paper first extensively investigates the older-stable principle to observe its validity in different scenarios.It is observed that the older-stable principle does not hold in several of them.Then,it utilizes machine learning approach to predict the stability of peers.This work evaluates the accuracy of severalmachine learning algorithms over the prediction of stability,where the Gradient Boosting Regressor(GBR)out-performs other algorithms.Finally,this work presents a proof-of-concept simulation to compare the effectiveness of older-stable rule and machine learning-based predictions for the stabilization of the overlay.The results indicate that machine learning-based stability estimation significantly improves the system.展开更多
Recent advancements in hardware and communication technologies have enabled worldwide interconnection using the internet of things(IoT).The IoT is the backbone of smart city applications such as smart grids and green ...Recent advancements in hardware and communication technologies have enabled worldwide interconnection using the internet of things(IoT).The IoT is the backbone of smart city applications such as smart grids and green energy management.In smart cities,the IoT devices are used for linking power,price,energy,and demand information for smart homes and home energy management(HEM)in the smart grids.In complex smart gridconnected systems,power scheduling and secure dispatch of information are the main research challenge.These challenges can be resolved through various machine learning techniques and data analytics.In this paper,we have proposed a particle swarm optimization based machine learning algorithm known as a collaborative execute-before-after dependency-based requirement,for the smart grid.The proposed collaborative execute-before-after dependencybased requirement algorithm works in two phases,analysis and assessment of the requirements of end-users and power distribution companies.In the rst phases,a xed load is adjusted over a period of 24 h,and in the second phase,a randomly produced population load for 90 days is evaluated using particle swarm optimization.The simulation results demonstrate that the proposed algorithm performed better in terms of percentage cost reduction,peak to average ratio,and power variance mean ratio than particle swarm optimization and inclined block rate.展开更多
Hybrid cotton production through exploitation of heterosis is the only way for having vertical improvement and betterment in seed cotton yield which has been stagnated in the recent years. The current study was conduc...Hybrid cotton production through exploitation of heterosis is the only way for having vertical improvement and betterment in seed cotton yield which has been stagnated in the recent years. The current study was conducted to evaluate the performance of F2 population for studying mean performance, heterotic effects and inbreeding depression in upland cotton for polygenic traits. Parental genotypes and their F2s were sown at Khyber Pakhtunkhwa Agricultural University, Peshawar during 2010, manually. All the traits revealed highly significant (p ≤ 0.01) variations for both parents and their F2 hybrids. Mean performance for parents and their F2 hybrids is: (5.26 to 7.12 & 4.43 to 6.60) seeds locule-1, (21.10 to 28.03 & 20.40 to 28.50) seed boll-1, (32.20 to 34.80 & 32.22 to 35.05) lint% and (62.87 to 85.47 & 45.94 to 92.04) seed cotton yield plant-1, respectively. Heterotic effects found over mid parent and better parent were: 66.66% & 46.66% (seeds locule-1), 60% & 30% (seed boll-1), 43.33% & 30% (lint %) and 36.66% & 16.66% (seed cotton yield plant-1), respectively. For the parameters: seeds locule-1 (11 & 10), seeds boll-1 (2 & 1) and seed cotton yield plant-1 (3 & 1) showed positive highly significant heterosis for both mid and better parent, respectively while lint% did not reveal any positive significant heterosis. F2 populations i.e. CIM-499 × CIM-554 and CIM-554 × CIM-499 revealed highly significant heterotic effects over mid and better parent for all the traits except lint % while CIM-554 × CIM-707 showed highly significant heterotic effects for seeds locule-1 and seed cotton yield palnt-1. Positive economic heterotic effects were also exhibited by more than 50% of the F2 population i.e., 76.66% for seed locule-1, 50% for seeds boll-1, 3.33% for lint% and 20% for seed cotton yield plant-1, respectively. By comparing F2 mean values with F1s, only lint % showed (0.00% to 15.55%) maximum inbreeding depression while negligible amount of inbreeding depression was observed for the remaining traits. However, negative inbreeding depression was revealed by majority of the F2 population like 96.66% (seeds locule-1 & seeds boll-1), 60% (lint%) and 90% (seed cotton yield-1), respectively meant F2 population has shown more stability even after segregation and have exceeded the check cultivars and better parents in performance.展开更多
The widespread use and production of plastic have led to increased accumulation of plastic waste in the environment which threatens terrestrial and marine life.Efficient methods for management of plastic waste remain ...The widespread use and production of plastic have led to increased accumulation of plastic waste in the environment which threatens terrestrial and marine life.Efficient methods for management of plastic waste remain a key challenge.Biodegradation of plastics is considered an environmentally safe method,but is still limited to laboratory scale.Several previous studies have reported microbial enzymes capable of degrading plastic.These discoveries offer a promising starting point for the development of biocatalyzed plastic degradation technology.In this review,we discuss recent advancements and applications of biocatalyst technology.We also describe the different steps for development of biocatalyzed plastic degradation technology and the major issues related to each stage.Breakthroughs in research into biocatalyzed plastic degradation would lead to new opportunities for sustainable alleviation of the worldwide problem of plastic waste accumulation.展开更多
Zinc telluride is a versatile wide band gap semiconductor used in many applications.But it has certain limitations like large dimensions and large band gaps.Introducing alkali metal to its bulk lattice(3D)can reduce i...Zinc telluride is a versatile wide band gap semiconductor used in many applications.But it has certain limitations like large dimensions and large band gaps.Introducing alkali metal to its bulk lattice(3D)can reduce its dimensions and lanthanide can produce a red shift in the energy gap by converting it into quaternary compounds.The alkali and lanthanide incorporated quaternary zinc tellurides CsLnZnTe_(3)(Ln=La,Pr,Nd and Sm)form layered crystal structure in which_(∞)^(2)[LnZnTe_(3)]-layers are separated by Cs+layer.The famous lanthanide contraction is experimental both from lattice constants and bond lengths.The calculated band gaps are 2.26,2.28,2.12,2.05 eV for CsLaZnTe_(3),CsPrZnTe_(3),CsNdZnTe_(3) and CsSmZnTe_(3),respectively.These compounds show direct band gap nature.The energy band gaps of these compounds have not been evaluated yet both experimentally and theoretically.Energy loss functions,refractive index and dielectric functions were also calculated to explore the potential applications of CsLnZnTe_(3) in optoelectronic devices.展开更多
Plasma-sprayed hydroxyapatite (HA) coatings have been widely utilized in load-bearing titanium alloy implants. In this study, Mg, Sr co-substituted HA ((Mg,Sr)-HA) nano-scale powders have been synthesized, which are f...Plasma-sprayed hydroxyapatite (HA) coatings have been widely utilized in load-bearing titanium alloy implants. In this study, Mg, Sr co-substituted HA ((Mg,Sr)-HA) nano-scale powders have been synthesized, which are further used to prepare (Mg,Sr)-HA coatings on Ti-6A1-4V alloys in order to improve the biological functions. The average size of (Mg,Sr)-HA nano particles is ~75nm. The average bonding strength for (Mg,Sr)-HA coating and samples after heat treatment at 500℃ or 600℃ for 3h are 26.17±2.11 MPa, 36.07±4.48 MPa and 37.07 ±2.95 MPa, respectively. There is a significantly increase of bonding strength likely due to low residual stress after heated treatment.MC3T3-E1 cells show a high proliferation rate when cultured with (Mg,Sr)-HA coating extract compared to the normal culture medium, which also exhibit large extension and depositi on of extracellular matrices when adhered on the coating surfaces. Thus, these (Mg,Sr)-HA coatings show high bonding strength and improved biological functions, which offer promising future applications in the fields of orthopedics and dentistry.展开更多
Implant-related infection and early bone integration are the main risk factors of implants for long-term service,to overcome these difficulties,SLA-TiCu surface was prepared by sandblasting and large-grits etching(SLA...Implant-related infection and early bone integration are the main risk factors of implants for long-term service,to overcome these difficulties,SLA-TiCu surface was prepared by sandblasting and large-grits etching(SLA)treatment on a novel antibacterial titanium-copper alloy(TiCu),which is the most prevalent surface treatment with micro/submicron hierarchical structures to titanium-based implants.Effects of SLA-TiCu surface on the adhesion,proliferation,apoptosis and differentiation of MC3T3-E1 cells as well as the antibacterial activity against a common orthopedic pathogen(Staphylococcus aureus)were studied.Compared to the following surfaces:sandblasting and large-grits etched pure titanium(SLATi),mechanically ground pure titanium and TiCu alloy(M-Ti and M-TiCu),these results indicated that SLA-TiCu surface obviously enhanced the bone-related gene expressions(alkaline phosphates(ALP),collagen typeⅠ(COLⅠ),Runt-related transcription factor 2(RUN x 2),and osteopontin(OPN)).Moreover,SLA-TiCu surface could maintain a sustainable release of Cu2+ions and effectively inhibited the viability of bacteria.This study demonstrated that SLA-TiCu surface possessed multifunctional characteristics of improved osteogenic ability and antibacterial activity,making it promising as a novel implant material for hard tissue repairs such as orthopedics and dental implants.展开更多
Ti-15 Zr-xCu(3≤x≤7,wt.%) novel antibacterial and antibiofilm alloys with competitive mechanical properties,biological responses and corrosion resistance were designed and fabricated.Annealing heat treatment on Ti-15...Ti-15 Zr-xCu(3≤x≤7,wt.%) novel antibacterial and antibiofilm alloys with competitive mechanical properties,biological responses and corrosion resistance were designed and fabricated.Annealing heat treatment on Ti-15 Zr-7 Cu(TZC-7 A),after holding for 2 h at slightly above their beta transus temperature(BTT) ensured their tensile strength(UTS),yield strength(YS) and hardness(HRV) were improved by31.2%,20% and 12.3% respectively compared to the control without Cu,Ti-15 Zr(T-15 ZA).Although the3 wt.% Cu alloy displayed the highest elongation(26%),the TZC-7 A alloy also possessed a good ductility.Presence of evenly dispersed Ti2 Cu and Zr2 Cu Cu-rich intermetallic phases formed as interwoven and alternating lamellae within the α+β matrix as a result of Cu addition,as revealed by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).These greatly contributed to their strengthening and bactericidal properties.Over 98% antibacterial effect against E.coli and S.aureus have been imparted,coupled with excellent biofilm inhibition.Potentiodynamic polarization curves showed that the TZC-7 A alloy possessed higher corrosion resistance than commercially pure titanium,cp-Ti;contact angle test revealed enhanced hydrophilicity;while confocal laser scanning microscopy(CLSM) and cell counting kit(CCK-8) assays also displayed drastically lowered bacterial adhesion rate with comparatively no cytotoxicity.Cell attachment on all alloys was similar but the best spread was obtained on TZC-7 A after 24 h.The developed alloy has good potential as an antibacterial implant material with combination of optimized properties.展开更多
The adsorption behavior, antibacterial, and corrosion properties of a Ti-3 Cu alloy were studied in a phosphate-buffered saline solution containing 0, 1, 3, and 6 gL^(-1) bovine serum albumin protein at 37℃ and pH = ...The adsorption behavior, antibacterial, and corrosion properties of a Ti-3 Cu alloy were studied in a phosphate-buffered saline solution containing 0, 1, 3, and 6 gL^(-1) bovine serum albumin protein at 37℃ and pH = 7.4(±0.2). The protein adsorption behavior was examined via cyclic voltammetry, secondary ions mass spectroscopy(SIMS), and angle-resolved X-ray photoelectron spectroscopy(ARXPS). The corrosion property was analyzed by the open circuit potential(OCP), potentiodynamic polarization(PD),and electrochemical impedance spectroscopy(EIS) examinations. The antibacterial test was conducted according to the GB/T 21510 China Standard. It was observed that the surface charge density(QA DS) was directly proportional to the amount of the adsorbed BSA protein, signifying that the protein adsorption was accompanied by the charge transfer, pointing to chemisorptions phenomena. BSA amino groups and other organic species were observed in the surface analysis examinations. It was shown that the formation of barrier complexes between the TiO_(2) oxide-layer and PBS solution resulted in decreasing the release of Cu-ions, which consequently reduced the antibacterial activity. On the other hand, these barrier complexes improved the corrosion resistance by increasing the charge transfer resistance and double-layer capacitance of the Ti-3 Cu alloy.展开更多
The effects of different aging conditions on the microstructure,strength,corrosion resistance,cytotoxicity and antibacterial ability of Ti-15Zr-xCu(3≤x≤7,wt%)(TZC)alloys were systematically investigated.Microstructu...The effects of different aging conditions on the microstructure,strength,corrosion resistance,cytotoxicity and antibacterial ability of Ti-15Zr-xCu(3≤x≤7,wt%)(TZC)alloys were systematically investigated.Microstructural evolution and behavior were analyzed by X-ray diffraction(XRD)patterns and scanning electron microscopy with energy-dispersive spectroscopy(SEM-EDS),while potentiodynamic polarization technique was employed to characterize the corrosion response of the alloys after solution-treatment and aging(STA).High-temperature aging at 660℃ for 4 h(660-4)gave the best combination of properties by enabling significant precipitation of the Cu-rich Ti_(2)Cu and Zr_(2)Cu compounds,and mild formation of the Zr_(7)Cu_(10) secondary phase.The high kinetics at this condition was beneficial to the complete precipitation and more homogeneous distribution of the intermetallic particles.These led to the inhibition of dislocation movements and allowed for significantly improved mechanical strengths with added ductility,availability of more Cu ions for the desired oligodynamic activity without evoking cytotoxicity,better corrosion resistance and very high antibacterial ability(over 99.5%),thus improving the overall properties of the TZC alloys for biomedical applications.展开更多
基金supported by grants from the GCRF programmes of STFC(grants ST/P003257/1,4070200262)and UKRI(grant EP/S515875/1)to M.R.as well as funding from Mars Wrigley Confectionery to J.M.D.and M.R.and Cocoa Research UK to J.M.D.V.H.d.O.was supported by CAPES(Coordination for the Improvement of Higher Education Personnel—Brazil)[project:13462-13-0].
文摘In response to new European Union regulations,studies are underway to mitigate accumulation of toxic cadmium(Cd)in cacao(Theobroma cacao,Tc).This study advances such research with Cd isotope analyses of 19 genetically diverse cacao clones and yeast transformed to express cacao natural resistance-associated macrophage protein(NRAMP5)and heavy metal ATPases(HMAs).The plants were enriched in light Cd isotopes relative to the hydroponic solution withΔ^(114/110)Cd_(tot-sol)=−0.22±0.08‰.Leaves show a systematic enrichment of isotopically heavy Cd relative to total plants,in accord with closed-system isotope fractionation ofΔ^(114/110)C_(dseq-mob)=−0.13‰,by sequestering isotopically light Cd in roots/stems and mobilisation of remaining Cd to leaves.The findings demonstrate that(i)transfer of Cd between roots and leaves is primarily unidirectional;(ii)different clones utilise similar pathways for Cd sequestration,which differ from those of other studied plants;(iii)clones differ in their efficiency of Cd sequestration.Transgenic yeast that expresses TcNRAMP5(T.cacao natural resistance-associated macrophage gene)had isotopically lighter Cd than did cacao.This suggests that NRAMP5 transporters constitute an important pathway for uptake of Cd by cacao.Cd isotope signatures of transgenic yeast expressing HMA-family proteins suggest that they may contribute to Cd sequestration.The data are the first to record isotope fractionation induced by transporter proteins in vivo.
基金a part of a research project entitled"Tenure system as a determinant of resource management and utilization in mountainous areas:A study of Roghani Territory in Dir districts"funded by Pakistan Science Foundation,Islamabad,Pakistan
文摘Deforestation and associated ecological disturbances are the issues of global concern.Researchers have investigated a number of driving forces which accelerate the rate of deforestation at local and regional levels.These include poverty,population growth,market demand and prices,political instability,agricultural expansion and changes in property right and ownership regimes.This paper seeks to explore the impacts of population growth,changing tenure system and other socioeconomic factors on the forest cover of Roghani Valley,located in Hindu Raj Mountains,Northern Pakistan.The present study is mainly based on information collected through participatory observation,selfadministered interviews and questionnaire survey.Geographical Information System(GIS) database is also used for mapping and quantification.The results reveal that in the past three to four decades the study area has been subjected to severe deforestation and about half of the forest area has been converted into barren land.Thus,the area under natural forests decreased from 2099 to 1444 hectares in four decades.This large-scale deforestation is attributed to both proximate and under lying causes particularly traditional land tenure system and demographic development.Consequently,forest resources have been degraded and a number of plant species have disappeared from the forests of the study area while several others are in the process of disappearance.
文摘Live video streaming is one of the newly emerged services over the Internet that has attracted immense interest of the service providers.Since Internet was not designed for such services during its inception,such a service poses some serious challenges including cost and scalability.Peer-to-Peer(P2P)Internet Protocol Television(IPTV)is an application-level distributed paradigm to offer live video contents.In terms of ease of deployment,it has emerged as a serious alternative to client server,Content Delivery Network(CDN)and IP multicast solutions.Nevertheless,P2P approach has struggled to provide the desired streaming quality due to a number of issues.Stability of peers in a network is one of themajor issues among these.Most of the existing approaches address this issue through older-stable principle.This paper first extensively investigates the older-stable principle to observe its validity in different scenarios.It is observed that the older-stable principle does not hold in several of them.Then,it utilizes machine learning approach to predict the stability of peers.This work evaluates the accuracy of severalmachine learning algorithms over the prediction of stability,where the Gradient Boosting Regressor(GBR)out-performs other algorithms.Finally,this work presents a proof-of-concept simulation to compare the effectiveness of older-stable rule and machine learning-based predictions for the stabilization of the overlay.The results indicate that machine learning-based stability estimation significantly improves the system.
文摘Recent advancements in hardware and communication technologies have enabled worldwide interconnection using the internet of things(IoT).The IoT is the backbone of smart city applications such as smart grids and green energy management.In smart cities,the IoT devices are used for linking power,price,energy,and demand information for smart homes and home energy management(HEM)in the smart grids.In complex smart gridconnected systems,power scheduling and secure dispatch of information are the main research challenge.These challenges can be resolved through various machine learning techniques and data analytics.In this paper,we have proposed a particle swarm optimization based machine learning algorithm known as a collaborative execute-before-after dependency-based requirement,for the smart grid.The proposed collaborative execute-before-after dependencybased requirement algorithm works in two phases,analysis and assessment of the requirements of end-users and power distribution companies.In the rst phases,a xed load is adjusted over a period of 24 h,and in the second phase,a randomly produced population load for 90 days is evaluated using particle swarm optimization.The simulation results demonstrate that the proposed algorithm performed better in terms of percentage cost reduction,peak to average ratio,and power variance mean ratio than particle swarm optimization and inclined block rate.
文摘Hybrid cotton production through exploitation of heterosis is the only way for having vertical improvement and betterment in seed cotton yield which has been stagnated in the recent years. The current study was conducted to evaluate the performance of F2 population for studying mean performance, heterotic effects and inbreeding depression in upland cotton for polygenic traits. Parental genotypes and their F2s were sown at Khyber Pakhtunkhwa Agricultural University, Peshawar during 2010, manually. All the traits revealed highly significant (p ≤ 0.01) variations for both parents and their F2 hybrids. Mean performance for parents and their F2 hybrids is: (5.26 to 7.12 & 4.43 to 6.60) seeds locule-1, (21.10 to 28.03 & 20.40 to 28.50) seed boll-1, (32.20 to 34.80 & 32.22 to 35.05) lint% and (62.87 to 85.47 & 45.94 to 92.04) seed cotton yield plant-1, respectively. Heterotic effects found over mid parent and better parent were: 66.66% & 46.66% (seeds locule-1), 60% & 30% (seed boll-1), 43.33% & 30% (lint %) and 36.66% & 16.66% (seed cotton yield plant-1), respectively. For the parameters: seeds locule-1 (11 & 10), seeds boll-1 (2 & 1) and seed cotton yield plant-1 (3 & 1) showed positive highly significant heterosis for both mid and better parent, respectively while lint% did not reveal any positive significant heterosis. F2 populations i.e. CIM-499 × CIM-554 and CIM-554 × CIM-499 revealed highly significant heterotic effects over mid and better parent for all the traits except lint % while CIM-554 × CIM-707 showed highly significant heterotic effects for seeds locule-1 and seed cotton yield palnt-1. Positive economic heterotic effects were also exhibited by more than 50% of the F2 population i.e., 76.66% for seed locule-1, 50% for seeds boll-1, 3.33% for lint% and 20% for seed cotton yield plant-1, respectively. By comparing F2 mean values with F1s, only lint % showed (0.00% to 15.55%) maximum inbreeding depression while negligible amount of inbreeding depression was observed for the remaining traits. However, negative inbreeding depression was revealed by majority of the F2 population like 96.66% (seeds locule-1 & seeds boll-1), 60% (lint%) and 90% (seed cotton yield-1), respectively meant F2 population has shown more stability even after segregation and have exceeded the check cultivars and better parents in performance.
文摘The widespread use and production of plastic have led to increased accumulation of plastic waste in the environment which threatens terrestrial and marine life.Efficient methods for management of plastic waste remain a key challenge.Biodegradation of plastics is considered an environmentally safe method,but is still limited to laboratory scale.Several previous studies have reported microbial enzymes capable of degrading plastic.These discoveries offer a promising starting point for the development of biocatalyzed plastic degradation technology.In this review,we discuss recent advancements and applications of biocatalyst technology.We also describe the different steps for development of biocatalyzed plastic degradation technology and the major issues related to each stage.Breakthroughs in research into biocatalyzed plastic degradation would lead to new opportunities for sustainable alleviation of the worldwide problem of plastic waste accumulation.
基金the Deanship of Scientific Research at King Khalid University for funding this work through research groups program under grant number(RGP.2/141/43)。
文摘Zinc telluride is a versatile wide band gap semiconductor used in many applications.But it has certain limitations like large dimensions and large band gaps.Introducing alkali metal to its bulk lattice(3D)can reduce its dimensions and lanthanide can produce a red shift in the energy gap by converting it into quaternary compounds.The alkali and lanthanide incorporated quaternary zinc tellurides CsLnZnTe_(3)(Ln=La,Pr,Nd and Sm)form layered crystal structure in which_(∞)^(2)[LnZnTe_(3)]-layers are separated by Cs+layer.The famous lanthanide contraction is experimental both from lattice constants and bond lengths.The calculated band gaps are 2.26,2.28,2.12,2.05 eV for CsLaZnTe_(3),CsPrZnTe_(3),CsNdZnTe_(3) and CsSmZnTe_(3),respectively.These compounds show direct band gap nature.The energy band gaps of these compounds have not been evaluated yet both experimentally and theoretically.Energy loss functions,refractive index and dielectric functions were also calculated to explore the potential applications of CsLnZnTe_(3) in optoelectronic devices.
基金supported by the National Key Research and Development Program of China from Ministry of Science and Technology (No. 2016YFC1100502)the College Students’ Innovative Program of Liaoning Province (No. 201310163023)+2 种基金Key Research Program of Frontier Sciences (No. QYZDY-SSW-JSC027)the Hundred-Talent Program from Chinese Academy of Sciences (CAS)the Innovation Research Program from Institute of Metal Research, CAS (No. 2015-ZD01)
文摘Plasma-sprayed hydroxyapatite (HA) coatings have been widely utilized in load-bearing titanium alloy implants. In this study, Mg, Sr co-substituted HA ((Mg,Sr)-HA) nano-scale powders have been synthesized, which are further used to prepare (Mg,Sr)-HA coatings on Ti-6A1-4V alloys in order to improve the biological functions. The average size of (Mg,Sr)-HA nano particles is ~75nm. The average bonding strength for (Mg,Sr)-HA coating and samples after heat treatment at 500℃ or 600℃ for 3h are 26.17±2.11 MPa, 36.07±4.48 MPa and 37.07 ±2.95 MPa, respectively. There is a significantly increase of bonding strength likely due to low residual stress after heated treatment.MC3T3-E1 cells show a high proliferation rate when cultured with (Mg,Sr)-HA coating extract compared to the normal culture medium, which also exhibit large extension and depositi on of extracellular matrices when adhered on the coating surfaces. Thus, these (Mg,Sr)-HA coatings show high bonding strength and improved biological functions, which offer promising future applications in the fields of orthopedics and dentistry.
基金supported by the National Research Foundation of Korea(NRF)Ministry of Science,ICT and Future-Planning through Basic-Science Research Program(No.2014R1A1A2A10058022)
基金financially supported by the National Key Research and Development Program of China(2018YFC1106601,2016YFC1100601)Liao Ning Revitalization Talents Program(XLYC1807069)+1 种基金National Natural Science Foundation(No.51631009,31870954)Key Projects for Foreign Cooperation of Bureau of International Cooperation Chinese Academy of Sciences(174321KYSB2018000)。
文摘Implant-related infection and early bone integration are the main risk factors of implants for long-term service,to overcome these difficulties,SLA-TiCu surface was prepared by sandblasting and large-grits etching(SLA)treatment on a novel antibacterial titanium-copper alloy(TiCu),which is the most prevalent surface treatment with micro/submicron hierarchical structures to titanium-based implants.Effects of SLA-TiCu surface on the adhesion,proliferation,apoptosis and differentiation of MC3T3-E1 cells as well as the antibacterial activity against a common orthopedic pathogen(Staphylococcus aureus)were studied.Compared to the following surfaces:sandblasting and large-grits etched pure titanium(SLATi),mechanically ground pure titanium and TiCu alloy(M-Ti and M-TiCu),these results indicated that SLA-TiCu surface obviously enhanced the bone-related gene expressions(alkaline phosphates(ALP),collagen typeⅠ(COLⅠ),Runt-related transcription factor 2(RUN x 2),and osteopontin(OPN)).Moreover,SLA-TiCu surface could maintain a sustainable release of Cu2+ions and effectively inhibited the viability of bacteria.This study demonstrated that SLA-TiCu surface possessed multifunctional characteristics of improved osteogenic ability and antibacterial activity,making it promising as a novel implant material for hard tissue repairs such as orthopedics and dental implants.
基金supported financially by the National Key Research and Development Program of China (Nos. 2018YFC1106601 and 2016YFC1100600)National Natural Science Foundation (No. 51631009)+2 种基金Youth Innovation Promotion Association, CAS (No. 2014168)Promoting Liaoning Province Talents Program-Top Young Talents (XLYC1807069)the support of CAS-TWAS President Fellowship。
文摘Ti-15 Zr-xCu(3≤x≤7,wt.%) novel antibacterial and antibiofilm alloys with competitive mechanical properties,biological responses and corrosion resistance were designed and fabricated.Annealing heat treatment on Ti-15 Zr-7 Cu(TZC-7 A),after holding for 2 h at slightly above their beta transus temperature(BTT) ensured their tensile strength(UTS),yield strength(YS) and hardness(HRV) were improved by31.2%,20% and 12.3% respectively compared to the control without Cu,Ti-15 Zr(T-15 ZA).Although the3 wt.% Cu alloy displayed the highest elongation(26%),the TZC-7 A alloy also possessed a good ductility.Presence of evenly dispersed Ti2 Cu and Zr2 Cu Cu-rich intermetallic phases formed as interwoven and alternating lamellae within the α+β matrix as a result of Cu addition,as revealed by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).These greatly contributed to their strengthening and bactericidal properties.Over 98% antibacterial effect against E.coli and S.aureus have been imparted,coupled with excellent biofilm inhibition.Potentiodynamic polarization curves showed that the TZC-7 A alloy possessed higher corrosion resistance than commercially pure titanium,cp-Ti;contact angle test revealed enhanced hydrophilicity;while confocal laser scanning microscopy(CLSM) and cell counting kit(CCK-8) assays also displayed drastically lowered bacterial adhesion rate with comparatively no cytotoxicity.Cell attachment on all alloys was similar but the best spread was obtained on TZC-7 A after 24 h.The developed alloy has good potential as an antibacterial implant material with combination of optimized properties.
基金financially supported by the National Key Research and Development Program of China(2018YFC1106601)Liaoning Revitalization Talents Program(XLYC1807069)+1 种基金National Natural Science Foundation(No.51631009,31870954)support of the CSC scholarship。
文摘The adsorption behavior, antibacterial, and corrosion properties of a Ti-3 Cu alloy were studied in a phosphate-buffered saline solution containing 0, 1, 3, and 6 gL^(-1) bovine serum albumin protein at 37℃ and pH = 7.4(±0.2). The protein adsorption behavior was examined via cyclic voltammetry, secondary ions mass spectroscopy(SIMS), and angle-resolved X-ray photoelectron spectroscopy(ARXPS). The corrosion property was analyzed by the open circuit potential(OCP), potentiodynamic polarization(PD),and electrochemical impedance spectroscopy(EIS) examinations. The antibacterial test was conducted according to the GB/T 21510 China Standard. It was observed that the surface charge density(QA DS) was directly proportional to the amount of the adsorbed BSA protein, signifying that the protein adsorption was accompanied by the charge transfer, pointing to chemisorptions phenomena. BSA amino groups and other organic species were observed in the surface analysis examinations. It was shown that the formation of barrier complexes between the TiO_(2) oxide-layer and PBS solution resulted in decreasing the release of Cu-ions, which consequently reduced the antibacterial activity. On the other hand, these barrier complexes improved the corrosion resistance by increasing the charge transfer resistance and double-layer capacitance of the Ti-3 Cu alloy.
基金financially supported by the National Natural Science Foundation of China(Nos.51631009 and 31870954).S.K.Kolawole graciously appreciates CAS-TWAS President Fellowship for the scholarship aid。
文摘The effects of different aging conditions on the microstructure,strength,corrosion resistance,cytotoxicity and antibacterial ability of Ti-15Zr-xCu(3≤x≤7,wt%)(TZC)alloys were systematically investigated.Microstructural evolution and behavior were analyzed by X-ray diffraction(XRD)patterns and scanning electron microscopy with energy-dispersive spectroscopy(SEM-EDS),while potentiodynamic polarization technique was employed to characterize the corrosion response of the alloys after solution-treatment and aging(STA).High-temperature aging at 660℃ for 4 h(660-4)gave the best combination of properties by enabling significant precipitation of the Cu-rich Ti_(2)Cu and Zr_(2)Cu compounds,and mild formation of the Zr_(7)Cu_(10) secondary phase.The high kinetics at this condition was beneficial to the complete precipitation and more homogeneous distribution of the intermetallic particles.These led to the inhibition of dislocation movements and allowed for significantly improved mechanical strengths with added ductility,availability of more Cu ions for the desired oligodynamic activity without evoking cytotoxicity,better corrosion resistance and very high antibacterial ability(over 99.5%),thus improving the overall properties of the TZC alloys for biomedical applications.
