Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by res...Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by researchers and industries alike,as there are still pressing issues that require attention.These include(1)a large mismatch in the elastic modulus of the implant material,which causes a stress shielding problem;(2)the release of harmful ions from Ti alloys after long-term use;(3)a low bioactivity of the Ti alloy surface,which prolongs the healing process.More research has been directed toward finding new generation Ti alloys composed of more biocompatible phases and modifying the surface of Ti alloys from naturally bio-inert to bioactive in order to circumvent the problems.This review examines recent work reported on the fabrication of Ti alloys,and based on the survey,major characteristics highlighted the importance of elastic modulus and the use of non-toxic metal elements to improve biocompatibility.In terms of surface modification of Ti alloys,numerous studies have found that a nano-scaled surface oxide layer grown on the surface is always beneficial to improving the bioactivity of Ti alloys for rapid recovery after implantation.This comprehensive review focuses on the appropriate phase and composition for new Ti alloys intended for use as biomedical implants,emphasizing both fabrication and surface modification methods.展开更多
Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aero...Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aerospace industry.The microstructure and mechanical properties of the weldments were also investigated.Relationships between the parameters and weld bead geometry were found.High quality weld joints without solidification crack that met AWS D17.1 requirements were obtained at(I)high pulse energy(25 J)and high average peak power(4.2 kW)and(II)low pulse energy(17.6 J)and low average peak power(2.8 kW).The weld joint formed at lower heat energy input exhibited finer dendritic grain structure.Mg vapourisation and hard phase compound(Al0.5Fe3Si0.5)formation decreased in the weld joint formed at lower heat energy input.Consequently,the tensile strength of the weldment formed at lower heat energy input(168 MPa)is by a factor of 1.15 higher but showed^29%decrease in hardness(111 HV0.1)at the joint when being compared with the weldment formed at higher heat energy input.Appropriate parameters selection is critical to obtaining 0.6 mm-thick AA5052-H32 pulse laser weld joints that meet AWS D17.1 requirements for aircraft structures.展开更多
Magnesium-based biomaterials have recently gained great attention as promising candidates for the new generation of biodegradable implants.This study investigated the mechanical performance and biodegradation behaviou...Magnesium-based biomaterials have recently gained great attention as promising candidates for the new generation of biodegradable implants.This study investigated the mechanical performance and biodegradation behaviour of magnesium-zinc/hydroxyapatite(Mg-Zn/HA)composites fabricated by different powder mixing techniques.A single step mixing process involved mechanical alloying or mechanical milling techniques,while double step processing involved a combination of both mechanical alloying and mechanical milling.Optimum mechanical properties of the composite were observed when the powders were prepared using single step processing via mechanical alloying technique.However,Mg-Zn/HA composite fabricated through single step processing via mechanical milling technique was found to have the most desirable low degradation rate coupled with highest bioactivity.The composite achieved the lowest degradation rate of 0.039×10^−3 mm/year as measured by immersion test and 0.0230 mm/year as measured by electrochemical polarization.Ca:P ratio of the composite also slightly more than enough to aid the initial bone mineralization,that is 1:1.76,as the required Ca:P ratio for initial bone mineralization is between 1:1 and 1:1.67.展开更多
Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is hel...Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina（ZTA） was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19（SA6） phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load; these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not enhanced because of the increase in porosity; in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.展开更多
This work aimed to fabricate magnesium zinc/hydroxyapatite （Mg-Zn/HA） composite via powder metallurgy method and to develop a mathematical model to predict the compressive strength of the composite using response su...This work aimed to fabricate magnesium zinc/hydroxyapatite （Mg-Zn/HA） composite via powder metallurgy method and to develop a mathematical model to predict the compressive strength of the composite using response surface methodology method. The effect of various mechanical milling parameters, milling speed （200-300 r/rain）, ball-to-powder weight ratio （5-12.5） and HA content （2.6-10 wt%） on the compressive strength of Mg-Zn/HA composite was investigated. The model shows that high compressive strength of Mg-Zn/HA composite was achieved when the powders were prepared with high milling speed and ball-to- powder weight ratio and low HA content. The mathematical model was adequate with error percentage lower than 3.4%. The microstructure of Mg-Zn/HA composite with different process parameters revealed that fine microstructure was observed at high milling speed and ball-to-powder weight ratio while agglomeration of HA was found in composite with 10 wt% HA. The agglomeration of HA led to degradation of interfacial bonding strength between matrix and reinforcement phases and hence decreased the overall compressive strength of Mg-Zn/HA composite. Biodegradation test revealed that sample with higher HA content had more weight gain and there was more formation of hydroxyapatite. Mg-Zn/HA composite with 8 wt% HA was found to be the best candidate for implant application because it had considerable compressive strength and good biodegradation properties.展开更多
The influence of La_(2)O_(3)inclusion(0-3 wt%)on the micro structure,phase formation and mechanical properties of zirconia toughed alumina(ZTA)added with 5.0 wt%CeO_(2)was investigated.ZTA CeO_(2)composites were sinte...The influence of La_(2)O_(3)inclusion(0-3 wt%)on the micro structure,phase formation and mechanical properties of zirconia toughed alumina(ZTA)added with 5.0 wt%CeO_(2)was investigated.ZTA CeO_(2)composites were sintered at 1600℃for 4 h.The microstructure,phase formation,density,fracture toughness and hardness properties were characterised through FESEM,Microscopy Image Analysis Software and XRD diffractometer,Archimedes principle and Vickers indentation technique,respectively.The XRD,image processing and FESEM reveal the existence of LaAl_(11)O_(18).The addition of La_(2)O_(3)incites the sintering,microstructure refinement,densification of ZTA-CeO_(2)matrix and phase transformation.Hence,the hardness of ZTA-CeO_(2)ceramics is increased rapidly based on refinement of Al_(2)O_(3)grains,densification of ZTA-CeO_(2)composites and porosity reduction.It is observed that the fracture toughness is enhanced through in situ formation of elongated LaAl_(11)O_(18)grains.The addition of 0.7 wt%La_(2)O_(3)culminated in the achievement of the optimum findings for density(4.41 g/cm^(3)),porosity(0.46%),hardness(1792 HV)and fracture toughness(8.8 MPa·m^(1/2)).Nevertheless,excess La_(2)O_(3)is proven to be detrimental as it displays poor mechanical properties due to the poor compactness of numerous LaAl_(11)O_(18)grains,coarsening of Al_(2)O_(3)grains and decline in density.展开更多
Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestab...Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.展开更多
The properties of cancer stem cells(CSCs),such as self-renewal,drug resistance,and metastasis,have been indicated to be responsible for the poor prognosis of patients with colon cancers.The epigenetic regulatory netwo...The properties of cancer stem cells(CSCs),such as self-renewal,drug resistance,and metastasis,have been indicated to be responsible for the poor prognosis of patients with colon cancers.The epigenetic regulatory network plays a crucial role in CSC properties.Regulatory non-coding RNA(ncRNA),including microRNAs,long noncoding RNAs,and circular RNAs,have an important influence on cell physiopathology.They modulate cells by regulating gene expression in different ways.This review discusses the basic characteristics and the physiological functions of colorectal cancer(CRC)stem cells.Elucidation of these ncRNAs will help us understand the pathological mechanism of CRC progression,and they could become a new target for cancer treatment.展开更多
Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in...Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.展开更多
Objective:The bulb of Albuca bracteata Jacq.,and Albuca setosa commonly used in Eastern Cape Province of South Africa for the treatment of several types of disease conditions including diabetes,was investigated for th...Objective:The bulb of Albuca bracteata Jacq.,and Albuca setosa commonly used in Eastern Cape Province of South Africa for the treatment of several types of disease conditions including diabetes,was investigated for their phytochemical contents and antioxidant activities.Methods:The antioxidant activity was determined by evaluating the effect of various solvent extracts(acetone,methanol,ethanol and water) on 2,2 – diphenyl-2-picrylhydrazyl(DPPH) scavenging activity,2,20– azino-bis(3-ethylbenzthiazoline-6-sulfonic acid diammonium salt(ABTS),ferric reducing power,hydrogen peroxide and nitric oxide scavenging activity while the various extracts were also analysed for phytochemical their contents.Results:The results obtained indicate that polyphenols,proanthocyanidins,saponins and alkaloids are present in higher concentrations.The composition of phenols(117 mg/g),flavonols(26.28 mg/g),proanthocyanidins(84.85 mg/g) and flavonoids(5.36 mg/g) were significantly higher in the acetone extract while saponin and alkaloids contents were higher in the aqueous extract.Antioxidant studies of the extracts for nitric oxide,hydrogen peroxide,ABTS and DPPH showed high antioxidant potential in a concentration-dependent manner that was not significantly different from Vitamin C,BHT and Rutin used as standard references.The methanol extract showed higher ferric reducing potential compared to the aqueous extract but was significantly different from Vitamin C,BHT and Rutin.Conclusion:This implies that the bulb of Albuca bracteata may serve as a natural source of antioxidants,which together with the numerous phytochemicals present,could account for its folkloric use as a medicinal plant.展开更多
The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers.In particular,if the acoustic waves are at...The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers.In particular,if the acoustic waves are attributes of live concerts at open-air theatres,without losing the sheen and quality,the audience should certainly receive the unbroken depth of the performance.Hence,at all times,it is advisable to analyse the auditory receptiveness,particularly in all intended recreational spaces.The current pandemic circumstances and the mandated COVID-19 prevention protocols encourage gatherings in naturally ventilated outdoor regions than confined indoors.This work predicts and quantifies the acoustic experience at the naturally carved amphitheatre at SAINTGITS,an autonomous institution at the down South-West of the Indian Subcontinent.The entire recreational space at SAINTGITS AMPHI was separately modelled as a Base case and Advanced case,and were analysed using the acoustic modelling module of EASE Focus,a renowned simulation freeware,which is in strict adherence with the International standards.The variation in loudness received at the nearest and farthest ends of the amphitheatre was between 67 to 80 dB.Though the Zero frequency SPL(Z-weighting)exhibited the loudness in the range of 81 to 85 dB and could maintain a safer auditory level for any human ear,it was confined to a hemispherical region near the sound source.A vertical beam angle of−4.0°was found to be effective throughout.The procedures and analyses will certainly help the future organizers and stakeholders to effectively plan the resources to reap rich acoustic experience at terrain-centric locales.The surface topography and contours were plotted with another set of freeware,the CADMAPPER and the QUIKGRID,to compare terrain gradient with the known data.Furthermore,this interdisciplinary research exhibits the extensive simulation capability of both EASE Focus and QUIKGRID and demonstrates the modelling versatility and deliverable potential of these freeware to benefit the budding architects and researchers.展开更多
We report on an all-solid-state battery that employs a closo-type complex hydride solid electrolyte and a LiCoO2 cathode.Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer en...We report on an all-solid-state battery that employs a closo-type complex hydride solid electrolyte and a LiCoO2 cathode.Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9V (vs.Li^+/Li) at room temperature.Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface.The interfacial resistance is lowered by ca.10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer,so that a discharge capacity of 109 mAh g^-1 is achieved.These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type complex hydride solid electrolytes and oxide cathodes.展开更多
The underlying structural origin of magnetic properties is still elusive in Fe-based amorphous alloys.In this study,distinctive soft magnetic properties were developed in Fe_(76)Si_(9)B_(10)P_(5)amorphous ribbons thro...The underlying structural origin of magnetic properties is still elusive in Fe-based amorphous alloys.In this study,distinctive soft magnetic properties were developed in Fe_(76)Si_(9)B_(10)P_(5)amorphous ribbons through systematic design of annealing process.Combining with synchrotron radiation,high-resolution transmission electron microscopy and first principle ab initio molecular dynamic simulation,it is found that the atomic structural evolution both in short range order and medium range order is responsible for the magnetic softness at proper annealing temperature.In short range,formation of separated and densely coordinated Fe-metalloid clusters is instigated to adapt energy minimization,resulting in strengthening of ferromagnetic exchange interaction locally.In medium range,a homogeneous exchangecoupling from the uniformly strong and weak ferromagnetic regions is generated,which significantly weakens magnetic heterogeneity and leads to the excellent magnetic softness.Our findings may provide an effective/promising pathway to modulate the magnetic properties for Fe-based amorphous alloys,and give a comprehensive and quantitative understanding of the structure-properties relationship in amorphous materials.展开更多
In this study,geochemical anomaly separation was carried out with methods based on the distribution model,which includes probability diagram(MPD),fractal(concentration-area technique),and U-statistic methods.The main ...In this study,geochemical anomaly separation was carried out with methods based on the distribution model,which includes probability diagram(MPD),fractal(concentration-area technique),and U-statistic methods.The main objective is to evaluate the efficiency and accuracy of the methods in separation of anomalies on the shear zone gold mineralization.For this purpose,samples were taken from the secondary lithogeochemical environment(stream sediment samples)on the gold mineralization in Saqqez,NW of Iran.Interpretation of the histograms and diagrams showed that the MPD is capable of identifying two phases of mineralization.The fractal method could separate only one phase of change based on the fractal dimension with high concentration areas of the Au element.The spatial analysis showed two mixed subpopulations after U=0 and another subpopulation with very high U values.The MPD analysis followed spatial analysis,which shows the detail of the variations.Six mineralized zones detected from local geochemical exploration results were used for validating the methods mentioned above.The MPD method was able to identify the anomalous areas higher than 90%,whereas the two other methods identified 60%(maximum)of the anomalous areas.The raw data without any estimation for the concentration was used by the MPD method using aminimum of calculations to determine the threshold values.Therefore,the MPD method is more robust than the other methods.The spatial analysis identified the detail soft hegeological and mineralization events that were affected in the study area.MPD is recommended as the best,and the spatial U-analysis is the next reliable method to be used.The fractal method could show more detail of the events and variations in the area with asymmetrical grid net and a higher density of sampling or at the detailed exploration stage.展开更多
基金funded by the Malaysian Ministry of Higher Education under the Fundamental Research Grant Scheme(Project Code FRGS/1/2018/TK05/USM/01/5)the first author is supported financially by a scholarship from Universiti Sains Malaysia(USM Fellowship)。
文摘Titanium and its alloys have long been used as implant materials due to their outstanding mechanical properties and apparent biocompatibility.Despite this,the search for better alloys has continued to be active by researchers and industries alike,as there are still pressing issues that require attention.These include(1)a large mismatch in the elastic modulus of the implant material,which causes a stress shielding problem;(2)the release of harmful ions from Ti alloys after long-term use;(3)a low bioactivity of the Ti alloy surface,which prolongs the healing process.More research has been directed toward finding new generation Ti alloys composed of more biocompatible phases and modifying the surface of Ti alloys from naturally bio-inert to bioactive in order to circumvent the problems.This review examines recent work reported on the fabrication of Ti alloys,and based on the survey,major characteristics highlighted the importance of elastic modulus and the use of non-toxic metal elements to improve biocompatibility.In terms of surface modification of Ti alloys,numerous studies have found that a nano-scaled surface oxide layer grown on the surface is always beneficial to improving the bioactivity of Ti alloys for rapid recovery after implantation.This comprehensive review focuses on the appropriate phase and composition for new Ti alloys intended for use as biomedical implants,emphasizing both fabrication and surface modification methods.
基金the funding (UniversityIndustry Engagement Grant)support provided by the Universiti Sains Malaysia under the Teaching Fellowship Scheme
文摘Pulse laser welding of 0.6 mm-thick AA5052-H32 was performed to determine the optimum set of parameters including laser pulse current,pulse frequency and pulse duration that meets the AWS D17.1 specifications for aerospace industry.The microstructure and mechanical properties of the weldments were also investigated.Relationships between the parameters and weld bead geometry were found.High quality weld joints without solidification crack that met AWS D17.1 requirements were obtained at(I)high pulse energy(25 J)and high average peak power(4.2 kW)and(II)low pulse energy(17.6 J)and low average peak power(2.8 kW).The weld joint formed at lower heat energy input exhibited finer dendritic grain structure.Mg vapourisation and hard phase compound(Al0.5Fe3Si0.5)formation decreased in the weld joint formed at lower heat energy input.Consequently,the tensile strength of the weldment formed at lower heat energy input(168 MPa)is by a factor of 1.15 higher but showed^29%decrease in hardness(111 HV0.1)at the joint when being compared with the weldment formed at higher heat energy input.Appropriate parameters selection is critical to obtaining 0.6 mm-thick AA5052-H32 pulse laser weld joints that meet AWS D17.1 requirements for aircraft structures.
基金The authors would like thank to Universiti Sains Malaysia for FRGS Grant No.203/PBAHAN/6071386 and financial scholarship from Ministry of Higher Education of Malaysia.
文摘Magnesium-based biomaterials have recently gained great attention as promising candidates for the new generation of biodegradable implants.This study investigated the mechanical performance and biodegradation behaviour of magnesium-zinc/hydroxyapatite(Mg-Zn/HA)composites fabricated by different powder mixing techniques.A single step mixing process involved mechanical alloying or mechanical milling techniques,while double step processing involved a combination of both mechanical alloying and mechanical milling.Optimum mechanical properties of the composite were observed when the powders were prepared using single step processing via mechanical alloying technique.However,Mg-Zn/HA composite fabricated through single step processing via mechanical milling technique was found to have the most desirable low degradation rate coupled with highest bioactivity.The composite achieved the lowest degradation rate of 0.039×10^−3 mm/year as measured by immersion test and 0.0230 mm/year as measured by electrochemical polarization.Ca:P ratio of the composite also slightly more than enough to aid the initial bone mineralization,that is 1:1.76,as the required Ca:P ratio for initial bone mineralization is between 1:1 and 1:1.67.
基金supported by research university grant (RU) of 1001/PBAHAN/811212 from Universiti Sains Malaysia
文摘Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina（ZTA） was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19（SA6） phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load; these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not enhanced because of the increase in porosity; in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.
基金Ministry of High Education(FRGS Grant No.6071304)for the financial support
文摘This work aimed to fabricate magnesium zinc/hydroxyapatite （Mg-Zn/HA） composite via powder metallurgy method and to develop a mathematical model to predict the compressive strength of the composite using response surface methodology method. The effect of various mechanical milling parameters, milling speed （200-300 r/rain）, ball-to-powder weight ratio （5-12.5） and HA content （2.6-10 wt%） on the compressive strength of Mg-Zn/HA composite was investigated. The model shows that high compressive strength of Mg-Zn/HA composite was achieved when the powders were prepared with high milling speed and ball-to- powder weight ratio and low HA content. The mathematical model was adequate with error percentage lower than 3.4%. The microstructure of Mg-Zn/HA composite with different process parameters revealed that fine microstructure was observed at high milling speed and ball-to-powder weight ratio while agglomeration of HA was found in composite with 10 wt% HA. The agglomeration of HA led to degradation of interfacial bonding strength between matrix and reinforcement phases and hence decreased the overall compressive strength of Mg-Zn/HA composite. Biodegradation test revealed that sample with higher HA content had more weight gain and there was more formation of hydroxyapatite. Mg-Zn/HA composite with 8 wt% HA was found to be the best candidate for implant application because it had considerable compressive strength and good biodegradation properties.
基金financially supported by research university grantUniversiti Sains Malaysia RUI 1001/PBAHAN/811212teaching fellow scheme USM.9/25 Jld.ⅩⅢ。
文摘The influence of La_(2)O_(3)inclusion(0-3 wt%)on the micro structure,phase formation and mechanical properties of zirconia toughed alumina(ZTA)added with 5.0 wt%CeO_(2)was investigated.ZTA CeO_(2)composites were sintered at 1600℃for 4 h.The microstructure,phase formation,density,fracture toughness and hardness properties were characterised through FESEM,Microscopy Image Analysis Software and XRD diffractometer,Archimedes principle and Vickers indentation technique,respectively.The XRD,image processing and FESEM reveal the existence of LaAl_(11)O_(18).The addition of La_(2)O_(3)incites the sintering,microstructure refinement,densification of ZTA-CeO_(2)matrix and phase transformation.Hence,the hardness of ZTA-CeO_(2)ceramics is increased rapidly based on refinement of Al_(2)O_(3)grains,densification of ZTA-CeO_(2)composites and porosity reduction.It is observed that the fracture toughness is enhanced through in situ formation of elongated LaAl_(11)O_(18)grains.The addition of 0.7 wt%La_(2)O_(3)culminated in the achievement of the optimum findings for density(4.41 g/cm^(3)),porosity(0.46%),hardness(1792 HV)and fracture toughness(8.8 MPa·m^(1/2)).Nevertheless,excess La_(2)O_(3)is proven to be detrimental as it displays poor mechanical properties due to the poor compactness of numerous LaAl_(11)O_(18)grains,coarsening of Al_(2)O_(3)grains and decline in density.
基金supported by the Universiti Sains Malaysia(USM) fellowship(APEX 91002/JHEA/ATSG4001)fundamental research grant scheme(FRGS) under grant number of 203/PBAHAN/6071263
文摘Electroceramic calcium copper titanates(CaCu3Ti4O12,CCTO),with high dielectric permittivities（e） of approximately 105 and 104,respectively,for single crystal and bulk materials,are produced for a number of wellestablished and emerging applications such as resonator,capacitor,and sensor.These applications take advantage of the unique properties achieved through the structure and properties of CCTO.This review comprehensively focuses on the primary processing routes,effect of impurity,dielectric permittivity,and deposition technique used for the processing of electroceramics along with their chemical composition and micro and nanostructures.Emphasis is given to versatile and basic approaches that allow one to control the microstructural features that ultimately determine the properties of the CCTO ceramic.Despite the intensive research in this area,none of the studies available in the literature provides all the possible relevant information about CCTO fabrication,structure,the factors influencing its dielectric properties,CCTO immobilization,and sensing applications.
文摘The properties of cancer stem cells(CSCs),such as self-renewal,drug resistance,and metastasis,have been indicated to be responsible for the poor prognosis of patients with colon cancers.The epigenetic regulatory network plays a crucial role in CSC properties.Regulatory non-coding RNA(ncRNA),including microRNAs,long noncoding RNAs,and circular RNAs,have an important influence on cell physiopathology.They modulate cells by regulating gene expression in different ways.This review discusses the basic characteristics and the physiological functions of colorectal cancer(CRC)stem cells.Elucidation of these ncRNAs will help us understand the pathological mechanism of CRC progression,and they could become a new target for cancer treatment.
基金Universiti Sains Malaysia for providing the fund for this study under RU grant No.1001/PBahan/8014105.
文摘Effect of annealing and solution treatment prior to cryorolling on the formation of initial structure influencing microstructure formation from nano to micron scale and resultant mechanical and corrosion properties in Al 1100 alloy has been studied in detail.Before subjecting to 50%cryorolling,samples were pre-annealed at 250℃ for 2 h and pre-solution treated at 540℃ for 1 h.X-ray diffraction and HRTEM techniques were used to understand the crystallite size,lattice strain and dislocation configuration in the processed alloy.The results indicate that the pre-annealed sample has the highest grain aspect ratio(4.43),the smallest crystallite size(37.53 nm),the highest lattice strain(9.12×10^(−3))and the highest dislocation density(45.16×10^(13) m^(−2))among the tested sample.The pre-annealed sample shows a significant improvement of 43.44%,24.64%and 20.33%in hardness,ultimate tensile strength and yield strength.Both pre-annealed and pre-solution treated samples show improved corrosion resistance when compared to cryorolled samples without any pre-treatment,with the pre-annealed sample showing the best corrosion resistance.
基金Govan Mbeki Research Development Council(GMRDC),University of Fort Hare(Grant No.C228)National Research Foundation(NRF)(Grant No.95187)both of South Africa for funding this work
文摘Objective:The bulb of Albuca bracteata Jacq.,and Albuca setosa commonly used in Eastern Cape Province of South Africa for the treatment of several types of disease conditions including diabetes,was investigated for their phytochemical contents and antioxidant activities.Methods:The antioxidant activity was determined by evaluating the effect of various solvent extracts(acetone,methanol,ethanol and water) on 2,2 – diphenyl-2-picrylhydrazyl(DPPH) scavenging activity,2,20– azino-bis(3-ethylbenzthiazoline-6-sulfonic acid diammonium salt(ABTS),ferric reducing power,hydrogen peroxide and nitric oxide scavenging activity while the various extracts were also analysed for phytochemical their contents.Results:The results obtained indicate that polyphenols,proanthocyanidins,saponins and alkaloids are present in higher concentrations.The composition of phenols(117 mg/g),flavonols(26.28 mg/g),proanthocyanidins(84.85 mg/g) and flavonoids(5.36 mg/g) were significantly higher in the acetone extract while saponin and alkaloids contents were higher in the aqueous extract.Antioxidant studies of the extracts for nitric oxide,hydrogen peroxide,ABTS and DPPH showed high antioxidant potential in a concentration-dependent manner that was not significantly different from Vitamin C,BHT and Rutin used as standard references.The methanol extract showed higher ferric reducing potential compared to the aqueous extract but was significantly different from Vitamin C,BHT and Rutin.Conclusion:This implies that the bulb of Albuca bracteata may serve as a natural source of antioxidants,which together with the numerous phytochemicals present,could account for its folkloric use as a medicinal plant.
基金This research is funded and supported by the Centre for Engineering Research and Development under the Research Seed Money scheme(CERD-RSM 2018 No.ME02 KTU/Research 2/3894/2018)of APJ Abdul Kalam Technological University,Thiruvanathapuram,Kerala State,India.
文摘The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers.In particular,if the acoustic waves are attributes of live concerts at open-air theatres,without losing the sheen and quality,the audience should certainly receive the unbroken depth of the performance.Hence,at all times,it is advisable to analyse the auditory receptiveness,particularly in all intended recreational spaces.The current pandemic circumstances and the mandated COVID-19 prevention protocols encourage gatherings in naturally ventilated outdoor regions than confined indoors.This work predicts and quantifies the acoustic experience at the naturally carved amphitheatre at SAINTGITS,an autonomous institution at the down South-West of the Indian Subcontinent.The entire recreational space at SAINTGITS AMPHI was separately modelled as a Base case and Advanced case,and were analysed using the acoustic modelling module of EASE Focus,a renowned simulation freeware,which is in strict adherence with the International standards.The variation in loudness received at the nearest and farthest ends of the amphitheatre was between 67 to 80 dB.Though the Zero frequency SPL(Z-weighting)exhibited the loudness in the range of 81 to 85 dB and could maintain a safer auditory level for any human ear,it was confined to a hemispherical region near the sound source.A vertical beam angle of−4.0°was found to be effective throughout.The procedures and analyses will certainly help the future organizers and stakeholders to effectively plan the resources to reap rich acoustic experience at terrain-centric locales.The surface topography and contours were plotted with another set of freeware,the CADMAPPER and the QUIKGRID,to compare terrain gradient with the known data.Furthermore,this interdisciplinary research exhibits the extensive simulation capability of both EASE Focus and QUIKGRID and demonstrates the modelling versatility and deliverable potential of these freeware to benefit the budding architects and researchers.
基金supported by JSPS KAKENHI(Grant-in-Aid for Research Activity Start-up 17H06519)Grant-in-Aid for Early-Career Scientists(19K15666)+2 种基金Grant-in-Aid for Scientific Research on Innovative Areas“Hydrogenomics”(JP18H05513)the Collaborative Research Center on Energy Materials in IMR(E-IMR)Advanced Target Project-4 of WPI-AIMR,Tohoku University。
文摘We report on an all-solid-state battery that employs a closo-type complex hydride solid electrolyte and a LiCoO2 cathode.Interfacial modification between the solid electrolyte and cathode with a LiNbO3 buffer layer enables reversible charge-discharge cycling with a cell voltage of 3.9V (vs.Li^+/Li) at room temperature.Electrochemical analyses clarify that the given modification effectively suppresses side reactions at the cathode/solid electrolyte interface.The interfacial resistance is lowered by ca.10 times with a 5 nm thick LiNbO3 buffer layer compared to that without a buffer layer,so that a discharge capacity of 109 mAh g^-1 is achieved.These results suggest that interfacial modification can be a viable approach to the development of high-voltage all-solid-state batteries using closo-type complex hydride solid electrolytes and oxide cathodes.
基金financially supported by the Guangdong Major Project of Basic and Applied Basic Research,China(No.2019B030302010)the National Natural Science Foundation of China(Nos.52001219,52071222,51971179)+1 种基金the Chongqing Natural Science Foundation,China(No.cstc2019jcyj-msxmX0328)the Shaanxi Natural Science Foundation,China(No.2020JM-112)。
文摘The underlying structural origin of magnetic properties is still elusive in Fe-based amorphous alloys.In this study,distinctive soft magnetic properties were developed in Fe_(76)Si_(9)B_(10)P_(5)amorphous ribbons through systematic design of annealing process.Combining with synchrotron radiation,high-resolution transmission electron microscopy and first principle ab initio molecular dynamic simulation,it is found that the atomic structural evolution both in short range order and medium range order is responsible for the magnetic softness at proper annealing temperature.In short range,formation of separated and densely coordinated Fe-metalloid clusters is instigated to adapt energy minimization,resulting in strengthening of ferromagnetic exchange interaction locally.In medium range,a homogeneous exchangecoupling from the uniformly strong and weak ferromagnetic regions is generated,which significantly weakens magnetic heterogeneity and leads to the excellent magnetic softness.Our findings may provide an effective/promising pathway to modulate the magnetic properties for Fe-based amorphous alloys,and give a comprehensive and quantitative understanding of the structure-properties relationship in amorphous materials.
文摘In this study,geochemical anomaly separation was carried out with methods based on the distribution model,which includes probability diagram(MPD),fractal(concentration-area technique),and U-statistic methods.The main objective is to evaluate the efficiency and accuracy of the methods in separation of anomalies on the shear zone gold mineralization.For this purpose,samples were taken from the secondary lithogeochemical environment(stream sediment samples)on the gold mineralization in Saqqez,NW of Iran.Interpretation of the histograms and diagrams showed that the MPD is capable of identifying two phases of mineralization.The fractal method could separate only one phase of change based on the fractal dimension with high concentration areas of the Au element.The spatial analysis showed two mixed subpopulations after U=0 and another subpopulation with very high U values.The MPD analysis followed spatial analysis,which shows the detail of the variations.Six mineralized zones detected from local geochemical exploration results were used for validating the methods mentioned above.The MPD method was able to identify the anomalous areas higher than 90%,whereas the two other methods identified 60%(maximum)of the anomalous areas.The raw data without any estimation for the concentration was used by the MPD method using aminimum of calculations to determine the threshold values.Therefore,the MPD method is more robust than the other methods.The spatial analysis identified the detail soft hegeological and mineralization events that were affected in the study area.MPD is recommended as the best,and the spatial U-analysis is the next reliable method to be used.The fractal method could show more detail of the events and variations in the area with asymmetrical grid net and a higher density of sampling or at the detailed exploration stage.
