The effects of various biological soil crusts(BSCs)on soil properties have been extensively studied.However,the impacts of specific species such as Placidium squamulosum,Peccania terricola,and Grimmia ovalis on soil p...The effects of various biological soil crusts(BSCs)on soil properties have been extensively studied.However,the impacts of specific species such as Placidium squamulosum,Peccania terricola,and Grimmia ovalis on soil properties in arid regions have not been documented.Besides,the effects of soil parent rock on the extent of changes in soil properties caused by BSCs have not been thoroughly investigated.The objective of this study was to examine how BSCs including two different terricolous lichen species(Placidium squamulosum and Peccania terricola)and a moss species(Grimmia ovalis)could change major soil chemical and nutritional properties in an arid area under different parent rocks.Triplicate BSC-free surface soil and soil associated with the abovementioned BSCs were sampled from 13 different sites with sedimentary and igneous parent rocks in an arid area in Isfahan,Iran.Soil properties including p H,electrical conductivity(EC),organic matter(OM),calcium carbonate equivalent(CCE),total nitrogen,available phosphorus,and available potassium were determined in all the samples.The results indicated that the presence of lichens and mosses significantly changed the soil chemical and nutritional properties.Specifically,the content of total nitrogen,organic matter,and available potassium in the soil environment increased under the activity of these biological crusts developed on both sedimentary and igneous formations.Additionally,these biological crusts resulted in a significant reduction in soil p H,CCE,and available phosphorus.The electrical conductivity of soils slightly increased due to the activity of biological crusts.In general,biological crusts including both chlorolichen(Placidium squamulosum)and cyanolichen(Peccania terricola)species,as well as a moss species(Grimmia ovalis)appear to create a unique microenvironment in terms of biochemical and nutritional conditions,which is substantially different from those typically observed in drylands.展开更多
Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),...Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),have enabled achieving near-net-shape products with tailored properties and decreased in-process oxidation.However,improving their mechanical and physical properties require further enhancement.In this study,a novel Mg-0.7Ca alloy was produced using SPS process.The effects of process parameters such as sintering time and additive type on the microstructural evolutions,phase arrangements,and mechanical and physical properties of the consolidated materials were investigated through various characterization techniques.Full-dense samples were produced from 60-minute ball-milled powder mixtures through spark plasma sintering at 420℃ for 7,10,and 13 min under 38 MPa of externally applied pressure.The obtained samples were then characterized using Field Emission Scanning Electron Microscopy(FESEM),Electron Backscatter Diffraction(EBSD),X-ray Energy Dispersive Spectroscopy(EDS),and X-ray Diffraction(XRD)analysis methods,as well as mechanical tests including compression strength and micro-hardness measurements.The results indicated that while improved densification behavior is observed in paraffin-contained samples,relatively better compression properties are achieved in starch-contained alloys.It is also found that the phase arrangement of the starch-contained samples includes higher fractions of the secondary phases such as oxides and residual carbons,which can positively affect the mechanical strength,despite decreased hardness.The microstructural characterizations showed an intensified thermomechanical response of the materials in both groups via increased sintering time.However,the competition between the influencing parameters causes scattered strengthening behavior and texture in the consolidated samples.Detailed discussions about the densification behavior,texture,and obtained characteristics were also included.展开更多
Demand for fast-charging lithium-ion batteries(LIBs)has escalated incredibly in the past few years.A conventional method to improve the performance is to chemically partly substitute the transition metal with another ...Demand for fast-charging lithium-ion batteries(LIBs)has escalated incredibly in the past few years.A conventional method to improve the performance is to chemically partly substitute the transition metal with another to increase its conductivity.In this study,we have chosen to investigate the lithium diffusion in doped anatase(TiO_(2))anodes for high-rate LIBs.Substitutional doping of TiO_(2)with the pentavalent Nb has previously been shown to increase the high-rate performances of this anode material dramatically.Despite the conventional belief,we explicitly show that Nb is mobile and diffusing at room temperature,and different diffusion mechanisms are discussed.Diffusing Nb in TiO_(2)has staggering implications concerning most chemically substituted LIBs and their performance.While the only mobile ion is typically asserted to be Li,this study clearly shows that the transition metals are also diffusing,together with the Li.This implies that a method that can hinder the diffusion of transition metals will increase the performance of our current LIBs even further.展开更多
The family of transition-metal dipnictides,MX2(M:metal,X:N,P,As,Sb,and Bi),has emerged as an important quantum material system due to its unique physical properties,such as large magnetoresistance,colossal Seebeck coe...The family of transition-metal dipnictides,MX2(M:metal,X:N,P,As,Sb,and Bi),has emerged as an important quantum material system due to its unique physical properties,such as large magnetoresistance,colossal Seebeck coefficients,and Weyl semimetal characteristics.In order to study the M-site ions effect on the lattice structure and the related dynamics,we compared two isostructural compounds,FeSb_(2)and RuSb_(2).Neutron diffraction,specific heat,and Raman scattering spectra of RuSb_(2)were measured.We found that the thermal expansion coefficients are isotropic for RuSb_(2),in contrast to the anisotropic behavior reported previously in FeSb_(2).Moreover,the specific heat of RuSb_(2)shows a bosonlike anomaly around 25 K.Four of the six predicted vibrational modes were identified by polarized Raman scattering spectra and successfully simulated by ab initio calculations.Meanwhile,the temperature-dependent linewidths reveal that phonon-phonon interactions might dominate above 50 K,while electron-phonon coupling remains relatively weak.展开更多
Magnesium(Mg)alloys have several advantages,such as low density,high specific strength and biocompatibility.However,they also suffer weak points,such as high corrosion,low formability and easy ignition,which makes the...Magnesium(Mg)alloys have several advantages,such as low density,high specific strength and biocompatibility.However,they also suffer weak points,such as high corrosion,low formability and easy ignition,which makes their applications limited.Many studies have been conducted to overcome these disadvantages and further improve the advantages of Mg alloys.Severe plastic deformation(SPD)is one of the most important techniques and has great effects on the microstructure refinement of Mg alloys and improvements in their strength and formability.Several researchers have studied the corrosion behavior of SPD-processed Mg alloys in recent decades.However,these studies have reported some controversial effects of SPD on the corrosion of Mg alloys,which makes the research roadmap ambiguous.Therefore,it is important to review the literature related to the corrosion properties of Mg alloys prepared by SPD and understand the mechanisms controlling their corrosion behavior.Effective grain refinement by SPD improves the corrosion properties of pure Mg and Mg alloys,but control of the processing conditions is a key factor for achieving this goal because texture,dislocation density,size and morphology of secondary phase also importantly affects the corrosion properties of Mg alloys.Reduced grain size in the fine grain-size range can decrease the corrosion rate due to the increased barrier effect of grain boundaries against corrosion and the formation of a stable passivation layer on the surface of fine grains.Basal texture reduces the corrosion rate because basal planes with the highest atomic planar density are more corrosion resistant than other planes.Increased dislocation density after SPD deteriorates the corrosion resistance of the interior grains and thus proper annealing after SPD is important.The fine and uniform distribution of secondary phase particles during SPD is important to minimize the micro-galvanic corrosion effect and retain small grains during annealing treatment for removing dislocations.展开更多
Mechanical properties of （Cu50Zr43Al7）100 Nbx （x=0,1,3,6,9） bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room t...Mechanical properties of （Cu50Zr43Al7）100 Nbx （x=0,1,3,6,9） bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room temperture show that the best mechanical properties of 2.8% and 1.98 GPa for plastic strain and fracture strength, respectively, in the sample with x=3. Microstructure, fracture surface and shear bands of the samples were observed by SEM and XRD methods.展开更多
Cu47Ti33Zr11Ni6Sn2Si1-based bulk metallic glass matrix composites reinforced with tungsten wires were fabricated by infiltration process at different temperatures （850, 900, 950 and 1000 °C） and time （10, 20 a...Cu47Ti33Zr11Ni6Sn2Si1-based bulk metallic glass matrix composites reinforced with tungsten wires were fabricated by infiltration process at different temperatures （850, 900, 950 and 1000 °C） and time （10, 20 and 30 min） in a quartz or a steel tube. The mechanical tests were carried out by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the maximum strength and total strain of the composite are 1778 MPa and 2.8% fabricated in steel tube at 900 °C for 10 min, and 1582 MPa and 3.6% fabricated in quartz tube at 850 °C for 10 min, respectively.展开更多
Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but rec...Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO_2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO_2 nanostructures for dye sensitized solar cells.展开更多
Using melt infiltration casting at different temperatures （965, 990 and 1015 °C） for different time （10 and 15 min）, the composites of （Cu50Zr43Al7）99.5Si0.5 bulk metallic glass reinforced with tungsten wir...Using melt infiltration casting at different temperatures （965, 990 and 1015 °C） for different time （10 and 15 min）, the composites of （Cu50Zr43Al7）99.5Si0.5 bulk metallic glass reinforced with tungsten wires were produced. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and quasi-static compression tests were carried out to evaluate the microstructure and mechanical properties. The results show that the maximum ultimate compressive strength and strain-to-failure of about 1880 MPa and 16.7% were achieved, respectively, at the infiltration temperature of 965 °C for 15 min.展开更多
H-ZSM-5 zeolite was synthesized by hydrothermal method. The effects of different synthesis parameters, such as hydrothermal crystallization temperature （170-190 ℃） and Si/A1 molar ratio （100-150）, on the catalyti...H-ZSM-5 zeolite was synthesized by hydrothermal method. The effects of different synthesis parameters, such as hydrothermal crystallization temperature （170-190 ℃） and Si/A1 molar ratio （100-150）, on the catalytic performance of the dehydration of methanol to dimethyl ether （DME） over the synthesized H-ZSM-5 zeolite were studied. The catalysts were characterized by N2 adsorption-desorption, XRD, NH3-TPD, TGA/DTA, and SEM techniques. The full factorial design of experiments was applied to the synthesis of H-ZSM-5 zeolite and the effects of synthesis conditions and their interaction on the yield of DME as the response variable were determined. Analysis of variance showed that two variables and their interaction significantly affected the response. According to the experimental results, the optimized catalyst prepared at 170℃ with the Si/A1 molar ratio of 100 showed the best catalytic performance among the tested H-ZSM-5 zeolite.展开更多
One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether.Longitudinal temperature and conversion profiles predicted...One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether.Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor.The reactor was packed with 1.5mm γ-Al2O3 pellets as dehydration catalyst and operated in a temperature range of 543-603K at an atmospheric pressure.Also,the effects of weight hourly space velocity(WHSV)and temperature on methanol conversion were investigated.According to the results,the maximum conversion is obtained at 603.15K with WHSV of 72.87h-1.展开更多
Nickel-tungsten/carbon nanotube nanocomposite layers with high content and uniform dispersion of carbon nanotubes were fabricated using pulsed electrodeposition technique.Nanocomposite layers were analyzed by scanning...Nickel-tungsten/carbon nanotube nanocomposite layers with high content and uniform dispersion of carbon nanotubes were fabricated using pulsed electrodeposition technique.Nanocomposite layers were analyzed by scanning electron microscopy, atomic force microscopy, microhardness, and Tafel polarization tests.The effect of the duty cycle of pulsed current or concentration of carbon nanotubes in the metallic matrix on electrochemical and mechanical properties of obtained layers has been investigated.It has been shown that both the electrochemical and mechanical properties of nanocomposite layers that formed by pulsed current were improved significantly with respect to un-composed Ni-W layer.The results were not only concerned by the concentration of carbon nanotubes in the layer but also influenced by the distribution of nanoparticulates in the metallic matrix.展开更多
In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid s...In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid support, which was at first coated by 3-mercaptopropyltrimethoxysi- lane. A stationary phase of oxidized multi walled carbon nanotube (MWCNTs)) was bonded to the surface of the copper wire. The developed SPME was characterized by IR and Scanning Electron Microscopy (SEM) and coupled to gas chromatography for separation of the analytes. Stability of the fiber, the effect of coating thickness and recovery time were optimized. The MWCNTs film thickness was about 5 μm which was perfect for a rapid mass transfer. The detection limits were at the range of 0.005 to 0.1 μg·L<sup>-1</sup>. The calibration curves were linear R<sup>2</sup> > 0.9813 in the range of 0.01 to 5 μg·L<sup>-1</sup>. The method has been successfully applied for real samples with standard addition of 5 μL<sup>-1</sup> of each sample. Stability study of the fiber to acid and alkali shows that it can be used for more than 50 times.展开更多
The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thickne...The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thicknesses(2,4,6 and 8μm)were coated on tensile samples Then,low-temperature high-activity(LTHA)and hightemperature low-activity(HTLA)processes were used for aluminizing.Results of microstructural evaluations using scanning electron microscope(SEM)and phase analysis by X-ray diffraction(XRD)showed a three-layer structure coating for different platinum layer thicknesses and both aluminizing processes.Increasing the thickness of the platinum layer from 2 to 8μm led to the improvement in the final coating thickness from 91.6 to 102.1μm in HTLA.This increase was from 128.1 to 148.6μm in LTHA.The results of hot tensile tests at 871℃ showed a decrease in strength properties of the coated samples compared to the uncoated ones.However,HTLA and high thicknesses of the initial platinum layer showed an intense reduction.The results of fractographic evaluations abou uncoated samples showed a ductile fracture.On the other hand,coated samples showed a simultaneous ductile and brittle fracture failure mechanism.But the main fracture morphology was brittle cleavage fracture which was for the HTLA.展开更多
Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resona...Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resonance mode at ER~5kBTc,are important for understanding the superconductivity.Here,we use inelastic neutron scattering(INS)to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned Fe Se.The low-energy spin excitations(E<10 meV)appear mainly at Q=(±1,0)in the superconducting state(T9K)and the nematic state(T90 K),confirming the constant C_(2) rotational symmetry and ruling out the C_(4) mode at E≈3 meV reported in a prior INS study.Moreover,our results reveal an isotropic spin resonance in the superconducting state,which is consistent with the s±wave pairing symmetry.At slightly higher energy,low-energy spin excitations become highly anisotropic.The full width at half maximum of spin excitations is elongated along the transverse direction.The Q-space isotropic spin resonance and highly anisotropic low-energy spin excitations could arise from dyz intra-orbital selective Fermi surface nesting between the hole pocket aroundΓpoint and the electron pockets centered at MX point.展开更多
Correction to:Rare Met.https://doi.org/10.1007/s12598-019-01293-4 In the original publication,Fig.12 was published incorrectly.The correct version of Fig.12 is given in this correction.
Monoethanolamine(MEA)is a frequently utilized absorbent for CO_(2)capture in many settings,enabling biomanufacturing using carbon as the resource.Nevertheless,evidence indicates that MEA is toxic to biological systems...Monoethanolamine(MEA)is a frequently utilized absorbent for CO_(2)capture in many settings,enabling biomanufacturing using carbon as the resource.Nevertheless,evidence indicates that MEA is toxic to biological systems,and its emissions can exacerbate ecosystem pollution.Therefore,it is imperative that disposal or valorization measures be implemented for effective green biomanufacturing with MEA as the absorbent.This study examined the removal of MEA by Haematococcus pluvialis(H.pluvialis),an astaxanthin-rich microalgae,and its effects on microalgal cells and related mechanisms.Approximately half of the initial MEA was metabolized by H.pluvialis,with the resulting metabolic intermediates including acetyl-CoA.The genes involved in MEA utilization exhibited a significant increase in expression,signifying a pivotal advancement in our understanding of its potential as a nutrient for microalgae.Moreover,the exposure of H.pluvialis to MEA resulted in notable alterations in cellular components,including a 21.7%increase in lipid content and a 27.8% increase in carbohydrate content.Notably,there was a 1.49-fold increase in astaxanthin content,which was accompanied by notable changes in cell morphology.In addition to the increase in astaxanthin production,the antioxidant system was activated to counteract the adverse effects of MEA-induced oxidative stress.Furthermore,enhanced biosynthesis of both carotenoids and fatty acids directly contributed to the elevated cellular astaxanthin levels achieved through MEA metabolism by H.pluvialis.These findings offer valuable insights into the treatment of CO_(2)absorbents using microalgae while simultaneously producing high-value and healthy products,which may prove beneficial for the development of sustainable solutions for green biomanufacturing.展开更多
Salination of solutions of salinity gradient releases large‐scale clean and renewable energy, which can be directly and efficiently transformed into electrical energy using ion‐selective nanofluidic channel membrane...Salination of solutions of salinity gradient releases large‐scale clean and renewable energy, which can be directly and efficiently transformed into electrical energy using ion‐selective nanofluidic channel membranes. However, conventional ion‐selective membranes are typically either cation‐ or anion‐selective. A pH‐switchable system capable of dual cation and anion transport along with salt gradient energy harvesting properties has not been demonstrated in ion‐selective membranes. Here, we constructed an amphoteric heterolayer metal–organic framework (MOF) membrane with subnanochannels modified with carboxylic and amino functional groups. The amphoteric MOF‐composite membrane, AAO/aUiO‐66‐(COOH)2/UiO‐66‐NH2, exhibits pH‐tuneable ion conduction and achieves osmotic energy conversion of 7.4 and 5.7 W/m2 in acidic and alkaline conditions, respectively, using a 50‐fold salt gradient. For different anions but the same cation diffusion transport, the amphoteric membrane produces an outstanding I−/CO32− selectivity of ~4160 and an osmotic energy conversion of ~133.5 W/m2. The amphoteric membrane concept introduces a new pathway to explore the development of ion transport and separation technologies and their application in osmotic energy‐conversion devices and flow batteries.展开更多
Helicobacter pylori(H.pylori) is an important major cause of peptic ulcer disease and gastric malignancies such as mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma worldwide.H.pylori treatment sti...Helicobacter pylori(H.pylori) is an important major cause of peptic ulcer disease and gastric malignancies such as mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma worldwide.H.pylori treatment still remains a challenge,since many determinants for successful therapy are involved such as individual primary or secondary antibiotics resistance,mucosal drug concentration,patient compliance,side-effect profile and cost.While no new drug has been developed,current therapy still relies on different mixture of known antibiotics and anti-secretory agents.A standard triple therapy consisting of two antibiotics and a proton-pump inhibitor proposed as the first-line regimen.Bismuthcontaining quadruple treatment,sequential treatment or a non-bismuth quadruple treatment(concomitant) are also an alternative therapy.Levofloxacin containing triple treatment are recommended as rescue treatment for infection of H.pylori after defeat of first-line therapy.The rapid acquisition of antibiotic resistance reduces the effectiveness of any regimens involving these remedies.Therefore,adding probiotic to the medications,developing anti-H.pylori photodynamic or phytomedicine therapy,and achieving a successful H.pylori vaccine may have the promising to present synergistic or additive consequence against H.pylori,because each of them exert different effects.展开更多
Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosi...Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosis of Gussian shape distribution curves were studied and the effect of time was determined.The usage of longer time is more suitable for achieving less size of complex nano-carbides.Surface roughness of treated samples was measured.It is observed that there is an optimum level for time on surface roughness increasing(difference between two measured data).展开更多
文摘The effects of various biological soil crusts(BSCs)on soil properties have been extensively studied.However,the impacts of specific species such as Placidium squamulosum,Peccania terricola,and Grimmia ovalis on soil properties in arid regions have not been documented.Besides,the effects of soil parent rock on the extent of changes in soil properties caused by BSCs have not been thoroughly investigated.The objective of this study was to examine how BSCs including two different terricolous lichen species(Placidium squamulosum and Peccania terricola)and a moss species(Grimmia ovalis)could change major soil chemical and nutritional properties in an arid area under different parent rocks.Triplicate BSC-free surface soil and soil associated with the abovementioned BSCs were sampled from 13 different sites with sedimentary and igneous parent rocks in an arid area in Isfahan,Iran.Soil properties including p H,electrical conductivity(EC),organic matter(OM),calcium carbonate equivalent(CCE),total nitrogen,available phosphorus,and available potassium were determined in all the samples.The results indicated that the presence of lichens and mosses significantly changed the soil chemical and nutritional properties.Specifically,the content of total nitrogen,organic matter,and available potassium in the soil environment increased under the activity of these biological crusts developed on both sedimentary and igneous formations.Additionally,these biological crusts resulted in a significant reduction in soil p H,CCE,and available phosphorus.The electrical conductivity of soils slightly increased due to the activity of biological crusts.In general,biological crusts including both chlorolichen(Placidium squamulosum)and cyanolichen(Peccania terricola)species,as well as a moss species(Grimmia ovalis)appear to create a unique microenvironment in terms of biochemical and nutritional conditions,which is substantially different from those typically observed in drylands.
文摘Light-weight Mg-based alloys have gained attention owing to their various applications in engineering and biomedicalfields.Recent advancements in modern powder metallurgy techniques,such as spark plasma technique(SPS),have enabled achieving near-net-shape products with tailored properties and decreased in-process oxidation.However,improving their mechanical and physical properties require further enhancement.In this study,a novel Mg-0.7Ca alloy was produced using SPS process.The effects of process parameters such as sintering time and additive type on the microstructural evolutions,phase arrangements,and mechanical and physical properties of the consolidated materials were investigated through various characterization techniques.Full-dense samples were produced from 60-minute ball-milled powder mixtures through spark plasma sintering at 420℃ for 7,10,and 13 min under 38 MPa of externally applied pressure.The obtained samples were then characterized using Field Emission Scanning Electron Microscopy(FESEM),Electron Backscatter Diffraction(EBSD),X-ray Energy Dispersive Spectroscopy(EDS),and X-ray Diffraction(XRD)analysis methods,as well as mechanical tests including compression strength and micro-hardness measurements.The results indicated that while improved densification behavior is observed in paraffin-contained samples,relatively better compression properties are achieved in starch-contained alloys.It is also found that the phase arrangement of the starch-contained samples includes higher fractions of the secondary phases such as oxides and residual carbons,which can positively affect the mechanical strength,despite decreased hardness.The microstructural characterizations showed an intensified thermomechanical response of the materials in both groups via increased sintering time.However,the competition between the influencing parameters causes scattered strengthening behavior and texture in the consolidated samples.Detailed discussions about the densification behavior,texture,and obtained characteristics were also included.
基金supported by Vetenskapsrådet(2022-06217)supported by the Swedish Research Council(VR)through a Starting Grant(Dnr.2017-05078)+7 种基金M.M.through a Marie Sklodowska-Curie Action and the Swedish Research Council-VR(Dnr.2014-6426 and 2016-06955)Carl Tryggers Foundation for Scientific Research(CTS-18:272)supported by the Swedish Research Council(VR)through Grant 2022-06217the Foundation Blanceflor fellow scholarships for 2023 and 2024the Ruth and Nils-Erik Stenbäck Foundationthe funding from the Area of Advance-Material Sciences from Chalmers University of Technologysupported byÅForsk via the grant 22-378supported by the Japan Society for the Promotion Science(JSPS)KAKENHI Grant Nos.JP20K1149,JP23H01840 and JP24H00042.
文摘Demand for fast-charging lithium-ion batteries(LIBs)has escalated incredibly in the past few years.A conventional method to improve the performance is to chemically partly substitute the transition metal with another to increase its conductivity.In this study,we have chosen to investigate the lithium diffusion in doped anatase(TiO_(2))anodes for high-rate LIBs.Substitutional doping of TiO_(2)with the pentavalent Nb has previously been shown to increase the high-rate performances of this anode material dramatically.Despite the conventional belief,we explicitly show that Nb is mobile and diffusing at room temperature,and different diffusion mechanisms are discussed.Diffusing Nb in TiO_(2)has staggering implications concerning most chemically substituted LIBs and their performance.While the only mobile ion is typically asserted to be Li,this study clearly shows that the transition metals are also diffusing,together with the Li.This implies that a method that can hinder the diffusion of transition metals will increase the performance of our current LIBs even further.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U2032213 and 12334008)the Guangdong Provincial Key Laboratory of Extreme Conditions(Grant No.2023B1212010002)+1 种基金the Micro-Raman Spectroscopy System(https://cstr.cn/31125.02.SHMFF.RAMAN)at the Steady High Magnetic Field Facility,CAS(https://cstr.cn/31125.02.SHMFF),for providing technical support and assistance in data collection and analysisthe beam time granted by J-PARC。
文摘The family of transition-metal dipnictides,MX2(M:metal,X:N,P,As,Sb,and Bi),has emerged as an important quantum material system due to its unique physical properties,such as large magnetoresistance,colossal Seebeck coefficients,and Weyl semimetal characteristics.In order to study the M-site ions effect on the lattice structure and the related dynamics,we compared two isostructural compounds,FeSb_(2)and RuSb_(2).Neutron diffraction,specific heat,and Raman scattering spectra of RuSb_(2)were measured.We found that the thermal expansion coefficients are isotropic for RuSb_(2),in contrast to the anisotropic behavior reported previously in FeSb_(2).Moreover,the specific heat of RuSb_(2)shows a bosonlike anomaly around 25 K.Four of the six predicted vibrational modes were identified by polarized Raman scattering spectra and successfully simulated by ab initio calculations.Meanwhile,the temperature-dependent linewidths reveal that phonon-phonon interactions might dominate above 50 K,while electron-phonon coupling remains relatively weak.
基金financially supported by the National Research Foundation of Korea funded by the Korean government(MSIT)(Project No.NRF 2020R1A4A1018826)。
文摘Magnesium(Mg)alloys have several advantages,such as low density,high specific strength and biocompatibility.However,they also suffer weak points,such as high corrosion,low formability and easy ignition,which makes their applications limited.Many studies have been conducted to overcome these disadvantages and further improve the advantages of Mg alloys.Severe plastic deformation(SPD)is one of the most important techniques and has great effects on the microstructure refinement of Mg alloys and improvements in their strength and formability.Several researchers have studied the corrosion behavior of SPD-processed Mg alloys in recent decades.However,these studies have reported some controversial effects of SPD on the corrosion of Mg alloys,which makes the research roadmap ambiguous.Therefore,it is important to review the literature related to the corrosion properties of Mg alloys prepared by SPD and understand the mechanisms controlling their corrosion behavior.Effective grain refinement by SPD improves the corrosion properties of pure Mg and Mg alloys,but control of the processing conditions is a key factor for achieving this goal because texture,dislocation density,size and morphology of secondary phase also importantly affects the corrosion properties of Mg alloys.Reduced grain size in the fine grain-size range can decrease the corrosion rate due to the increased barrier effect of grain boundaries against corrosion and the formation of a stable passivation layer on the surface of fine grains.Basal texture reduces the corrosion rate because basal planes with the highest atomic planar density are more corrosion resistant than other planes.Increased dislocation density after SPD deteriorates the corrosion resistance of the interior grains and thus proper annealing after SPD is important.The fine and uniform distribution of secondary phase particles during SPD is important to minimize the micro-galvanic corrosion effect and retain small grains during annealing treatment for removing dislocations.
文摘Mechanical properties of （Cu50Zr43Al7）100 Nbx （x=0,1,3,6,9） bulk metallic glasses rods with a diameter of 2.5 mm prepared by suction casting method were studied. The results of uniaxial compression tests at room temperture show that the best mechanical properties of 2.8% and 1.98 GPa for plastic strain and fracture strength, respectively, in the sample with x=3. Microstructure, fracture surface and shear bands of the samples were observed by SEM and XRD methods.
文摘Cu47Ti33Zr11Ni6Sn2Si1-based bulk metallic glass matrix composites reinforced with tungsten wires were fabricated by infiltration process at different temperatures （850, 900, 950 and 1000 °C） and time （10, 20 and 30 min） in a quartz or a steel tube. The mechanical tests were carried out by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The results show that the maximum strength and total strain of the composite are 1778 MPa and 2.8% fabricated in steel tube at 900 °C for 10 min, and 1582 MPa and 3.6% fabricated in quartz tube at 850 °C for 10 min, respectively.
文摘Titania is one kind of important materials, which has been extensively investigated because of its unique electronic and optical properties. Research efforts have largely focused on the optimization of the dye,but recently the titania nanostructures electrode itself has attracted more attention. It has been shown that particle size, shape, crystallinity, surface morphology, and chemistry of the TiO_2 material are key parameters which should be controlled for optimized performance of the solar cell. Titania can be found in different shape of nanostructures including mesoporous, nanotube, nanowire, and nanorod structures. The present article reviews the structural, synthesis, electronic, and optical properties of TiO_2 nanostructures for dye sensitized solar cells.
文摘Using melt infiltration casting at different temperatures （965, 990 and 1015 °C） for different time （10 and 15 min）, the composites of （Cu50Zr43Al7）99.5Si0.5 bulk metallic glass reinforced with tungsten wires were produced. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and quasi-static compression tests were carried out to evaluate the microstructure and mechanical properties. The results show that the maximum ultimate compressive strength and strain-to-failure of about 1880 MPa and 16.7% were achieved, respectively, at the infiltration temperature of 965 °C for 15 min.
文摘H-ZSM-5 zeolite was synthesized by hydrothermal method. The effects of different synthesis parameters, such as hydrothermal crystallization temperature （170-190 ℃） and Si/A1 molar ratio （100-150）, on the catalytic performance of the dehydration of methanol to dimethyl ether （DME） over the synthesized H-ZSM-5 zeolite were studied. The catalysts were characterized by N2 adsorption-desorption, XRD, NH3-TPD, TGA/DTA, and SEM techniques. The full factorial design of experiments was applied to the synthesis of H-ZSM-5 zeolite and the effects of synthesis conditions and their interaction on the yield of DME as the response variable were determined. Analysis of variance showed that two variables and their interaction significantly affected the response. According to the experimental results, the optimized catalyst prepared at 170℃ with the Si/A1 molar ratio of 100 showed the best catalytic performance among the tested H-ZSM-5 zeolite.
文摘One-dimensional heterogeneous plug flow model was employed to model an adiabatic fixed-bed reactor for the catalytic dehydration of methanol to dimethyl ether.Longitudinal temperature and conversion profiles predicted by this model were compared to those experimentally measured in a bench scale reactor.The reactor was packed with 1.5mm γ-Al2O3 pellets as dehydration catalyst and operated in a temperature range of 543-603K at an atmospheric pressure.Also,the effects of weight hourly space velocity(WHSV)and temperature on methanol conversion were investigated.According to the results,the maximum conversion is obtained at 603.15K with WHSV of 72.87h-1.
基金financial support from Iranian Nanotechnology Initiative
文摘Nickel-tungsten/carbon nanotube nanocomposite layers with high content and uniform dispersion of carbon nanotubes were fabricated using pulsed electrodeposition technique.Nanocomposite layers were analyzed by scanning electron microscopy, atomic force microscopy, microhardness, and Tafel polarization tests.The effect of the duty cycle of pulsed current or concentration of carbon nanotubes in the metallic matrix on electrochemical and mechanical properties of obtained layers has been investigated.It has been shown that both the electrochemical and mechanical properties of nanocomposite layers that formed by pulsed current were improved significantly with respect to un-composed Ni-W layer.The results were not only concerned by the concentration of carbon nanotubes in the layer but also influenced by the distribution of nanoparticulates in the metallic matrix.
文摘In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid support, which was at first coated by 3-mercaptopropyltrimethoxysi- lane. A stationary phase of oxidized multi walled carbon nanotube (MWCNTs)) was bonded to the surface of the copper wire. The developed SPME was characterized by IR and Scanning Electron Microscopy (SEM) and coupled to gas chromatography for separation of the analytes. Stability of the fiber, the effect of coating thickness and recovery time were optimized. The MWCNTs film thickness was about 5 μm which was perfect for a rapid mass transfer. The detection limits were at the range of 0.005 to 0.1 μg·L<sup>-1</sup>. The calibration curves were linear R<sup>2</sup> > 0.9813 in the range of 0.01 to 5 μg·L<sup>-1</sup>. The method has been successfully applied for real samples with standard addition of 5 μL<sup>-1</sup> of each sample. Stability study of the fiber to acid and alkali shows that it can be used for more than 50 times.
文摘The effect of platinum(a rare metal)-aluminide coating parameters on the tensile properties of nickel-based superalloy Rene■80 was evaluated at 871℃.For this purpose,initial layers of platinum with different thicknesses(2,4,6 and 8μm)were coated on tensile samples Then,low-temperature high-activity(LTHA)and hightemperature low-activity(HTLA)processes were used for aluminizing.Results of microstructural evaluations using scanning electron microscope(SEM)and phase analysis by X-ray diffraction(XRD)showed a three-layer structure coating for different platinum layer thicknesses and both aluminizing processes.Increasing the thickness of the platinum layer from 2 to 8μm led to the improvement in the final coating thickness from 91.6 to 102.1μm in HTLA.This increase was from 128.1 to 148.6μm in LTHA.The results of hot tensile tests at 871℃ showed a decrease in strength properties of the coated samples compared to the uncoated ones.However,HTLA and high thicknesses of the initial platinum layer showed an intense reduction.The results of fractographic evaluations abou uncoated samples showed a ductile fracture.On the other hand,coated samples showed a simultaneous ductile and brittle fracture failure mechanism.But the main fracture morphology was brittle cleavage fracture which was for the HTLA.
基金Beijing Normal University was supported by the Fundamental Research Funds for the Central Universitiesthe National Key Projects for Research and Development of China(No.2021YFA1400400)+1 种基金the National Natural Science Foundation of China(Grant Nos.12174029 and 11922402)the neutron beamtimes from J-PARC(Proposal No.2019A0002)。
文摘Antiferromagnetic spin fluctuation is regarded as the leading driving force for electron pairing in high-Tc superconductors.In iron-based superconductors,spin excitations at low energy range,especially the spin-resonance mode at ER~5kBTc,are important for understanding the superconductivity.Here,we use inelastic neutron scattering(INS)to investigate the symmetry and in-plane wave-vector dependence of low-energy spin excitations in uniaxial-strain detwinned Fe Se.The low-energy spin excitations(E<10 meV)appear mainly at Q=(±1,0)in the superconducting state(T9K)and the nematic state(T90 K),confirming the constant C_(2) rotational symmetry and ruling out the C_(4) mode at E≈3 meV reported in a prior INS study.Moreover,our results reveal an isotropic spin resonance in the superconducting state,which is consistent with the s±wave pairing symmetry.At slightly higher energy,low-energy spin excitations become highly anisotropic.The full width at half maximum of spin excitations is elongated along the transverse direction.The Q-space isotropic spin resonance and highly anisotropic low-energy spin excitations could arise from dyz intra-orbital selective Fermi surface nesting between the hole pocket aroundΓpoint and the electron pockets centered at MX point.
文摘Correction to:Rare Met.https://doi.org/10.1007/s12598-019-01293-4 In the original publication,Fig.12 was published incorrectly.The correct version of Fig.12 is given in this correction.
基金supported by the National Key R&D Program of China(2022YFC3401800)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDC0120301)+5 种基金the National Natural Science Foundation of China(32470253)the Hundred Talents Program of the Chinese Academy of Sciences(E3J56201)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIP-IJCP-001TSBICIP-IJCP-002TSBICIP-CXRC-027)the Tangshan Science and Technology Program(24150214C).
文摘Monoethanolamine(MEA)is a frequently utilized absorbent for CO_(2)capture in many settings,enabling biomanufacturing using carbon as the resource.Nevertheless,evidence indicates that MEA is toxic to biological systems,and its emissions can exacerbate ecosystem pollution.Therefore,it is imperative that disposal or valorization measures be implemented for effective green biomanufacturing with MEA as the absorbent.This study examined the removal of MEA by Haematococcus pluvialis(H.pluvialis),an astaxanthin-rich microalgae,and its effects on microalgal cells and related mechanisms.Approximately half of the initial MEA was metabolized by H.pluvialis,with the resulting metabolic intermediates including acetyl-CoA.The genes involved in MEA utilization exhibited a significant increase in expression,signifying a pivotal advancement in our understanding of its potential as a nutrient for microalgae.Moreover,the exposure of H.pluvialis to MEA resulted in notable alterations in cellular components,including a 21.7%increase in lipid content and a 27.8% increase in carbohydrate content.Notably,there was a 1.49-fold increase in astaxanthin content,which was accompanied by notable changes in cell morphology.In addition to the increase in astaxanthin production,the antioxidant system was activated to counteract the adverse effects of MEA-induced oxidative stress.Furthermore,enhanced biosynthesis of both carotenoids and fatty acids directly contributed to the elevated cellular astaxanthin levels achieved through MEA metabolism by H.pluvialis.These findings offer valuable insights into the treatment of CO_(2)absorbents using microalgae while simultaneously producing high-value and healthy products,which may prove beneficial for the development of sustainable solutions for green biomanufacturing.
文摘Salination of solutions of salinity gradient releases large‐scale clean and renewable energy, which can be directly and efficiently transformed into electrical energy using ion‐selective nanofluidic channel membranes. However, conventional ion‐selective membranes are typically either cation‐ or anion‐selective. A pH‐switchable system capable of dual cation and anion transport along with salt gradient energy harvesting properties has not been demonstrated in ion‐selective membranes. Here, we constructed an amphoteric heterolayer metal–organic framework (MOF) membrane with subnanochannels modified with carboxylic and amino functional groups. The amphoteric MOF‐composite membrane, AAO/aUiO‐66‐(COOH)2/UiO‐66‐NH2, exhibits pH‐tuneable ion conduction and achieves osmotic energy conversion of 7.4 and 5.7 W/m2 in acidic and alkaline conditions, respectively, using a 50‐fold salt gradient. For different anions but the same cation diffusion transport, the amphoteric membrane produces an outstanding I−/CO32− selectivity of ~4160 and an osmotic energy conversion of ~133.5 W/m2. The amphoteric membrane concept introduces a new pathway to explore the development of ion transport and separation technologies and their application in osmotic energy‐conversion devices and flow batteries.
文摘Helicobacter pylori(H.pylori) is an important major cause of peptic ulcer disease and gastric malignancies such as mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma worldwide.H.pylori treatment still remains a challenge,since many determinants for successful therapy are involved such as individual primary or secondary antibiotics resistance,mucosal drug concentration,patient compliance,side-effect profile and cost.While no new drug has been developed,current therapy still relies on different mixture of known antibiotics and anti-secretory agents.A standard triple therapy consisting of two antibiotics and a proton-pump inhibitor proposed as the first-line regimen.Bismuthcontaining quadruple treatment,sequential treatment or a non-bismuth quadruple treatment(concomitant) are also an alternative therapy.Levofloxacin containing triple treatment are recommended as rescue treatment for infection of H.pylori after defeat of first-line therapy.The rapid acquisition of antibiotic resistance reduces the effectiveness of any regimens involving these remedies.Therefore,adding probiotic to the medications,developing anti-H.pylori photodynamic or phytomedicine therapy,and achieving a successful H.pylori vaccine may have the promising to present synergistic or additive consequence against H.pylori,because each of them exert different effects.
基金Partial work of this project funded by National Elite Foundation of Iran and Iranian Nanotechnology Initiative is appreciated.
文摘Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosis of Gussian shape distribution curves were studied and the effect of time was determined.The usage of longer time is more suitable for achieving less size of complex nano-carbides.Surface roughness of treated samples was measured.It is observed that there is an optimum level for time on surface roughness increasing(difference between two measured data).
