Photothermal energy conversion represents a cornerstone process in the renewable energy technologies domain,enabling the capture of solar irradiance and its subsequent transformation into thermal energy.This mechanism...Photothermal energy conversion represents a cornerstone process in the renewable energy technologies domain,enabling the capture of solar irradiance and its subsequent transformation into thermal energy.This mechanism is paramount across many applications,facilitating the exploitation of solar energy for different purposes.The photothermal conversion efficiency and applications are fundamentally contingent upon the characteristics and performance of the materials employed.Consequently,deploying high-caliber materials is essential for optimizing energy capture and utilization.Within this context,photothermal nanomaterials have emerged as pivotal components in various applications,ranging from catalysis and sterilization to medical therapy,desalination,and electric power generation via the photothermal conversion effect.This review endeavors to encapsulate the current research landscape,delineating both the developmental trajectories and application horizons of photothermal conversion materials.It aims to furnish a detailed exposition of the mechanisms underlying photothermal conversion across various materials,shedding light on the principles guiding the design of photothermal nanomaterials.Furthermore,addressing the prevailing challenges and outlooks within the field elucidates potential avenues for future research and identifying priority areas.This review aspires to enrich the understanding of photothermal materials within the framework of energy conversion,offering novel insights and fostering a more profound comprehension of their role and potential in harnessing solar energy.展开更多
In recent times,there has been a surge of attention towards advanced high-performance materials for storing energy,specifically in supercapacitors.One encouraging method involves utilizing nanocomposites based on tran...In recent times,there has been a surge of attention towards advanced high-performance materials for storing energy,specifically in supercapacitors.One encouraging method involves utilizing nanocomposites based on transition metal oxides/graphene which have demonstrated significant potential for improving capacitance.The electrochemical properties of titanium oxide doped graphene in current research have been improved through the incorporation of rare earth metals.The hydrothermal technique was chosen for the fabrication of nanocomposites as electrode materials.X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM) approaches were employed for the characterization of nanocomposites.Ternary and quaternary nanocomposites with 2 wt% rare earth elements doped with titanium oxide and graphene were synthesized with various ratios of lanthanum and cerium as dopants.In 2 wt% La:Ce-TiO_(2)/rGO,lanthanum,and cerium were doped in 1:1,1:3,and 1:5 ratios.2 wt% La:Ce(1:5)-TiO_(2)/rGO among co-doped composites exhibits better capacitive performance as determined through cyclic voltammetry and galvanostatic charge-discharge.Among all the nanocomposites 422 F/g was the maximum depicted by 2 wt%La:Ce(1:5)-TiO_(2)/rGO at a scan rate of 10 mV/s(potential window from-0.4 to+0.6 V) and 1895 F/g at1 mV/s(potential window-0.6 to+0.6 V).specific capacitance was also determined via GCD,and a maximum capacitance of 486 F/g is depicted by 2 wt% La:Ce(1:5)-TiO_(2)/rGO.The same composites have also served as promising electrode materials in terms of columbic efficiency,power,and energy density.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
Personalized health services are of paramount importance for the treatment and prevention of cardiorespiratory diseases,such as hypertension.The assessment of cardiorespiratory function and biometric identification(ID...Personalized health services are of paramount importance for the treatment and prevention of cardiorespiratory diseases,such as hypertension.The assessment of cardiorespiratory function and biometric identification(ID)is crucial for the effectiveness of such personalized health services.To effectively and accurately monitor pulse wave signals,thus achieving the assessment of cardiorespiratory function,a wearable photonic smart wristband based on an all-polymer sensing unit(All-PSU)is proposed.The smart wristband enables the assessment of cardiorespiratory function by continuously monitoring respiratory rate(RR),heart rate(HR),and blood pressure(BP).Furthermore,it can be utilized for biometric ID purposes.Through the analysis of pulse wave signals using power spectral density(PSD),accurate monitoring of RR and HR is achieved.Additionally,utilizing peak detection algorithms for feature extraction from pulse signals and subsequently employing a variety of machine learning methods,accurate BP monitoring and biometric ID have been realized.For biometric ID,the accuracy rate is 98.55%.Aiming to monitor RR,HR,BP,and ID,our solution demonstrates advantages in integration,functionality,and monitoring precision.These enhancements may contribute to the development of personalized health services aimed at the treatment and prevention of cardiorespiratory diseases.展开更多
Biomass conversion to value-added chemicals has received tremendous attention for solving global warming issues and fossil fuel depletion.5-Hydroxymethylfurfural(HMF)is a key bio-based platform molecule to produce man...Biomass conversion to value-added chemicals has received tremendous attention for solving global warming issues and fossil fuel depletion.5-Hydroxymethylfurfural(HMF)is a key bio-based platform molecule to produce many useful organic chemicals by oxidation,hydrogenation,polymerization,and ring-opening reactions.Among all derivatives,the oxidation product 2,5-furandicarboxylic acid(FDCA)is a promising alternative to petroleum-based terephthalic acid for the synthesis of biodegradable plastics.This review analytically discusses the recent progress in the thermocatalytic,electrocatalytic,and photocatalytic oxidation of HMF into FDCA,including catalyst screening,synthesis processes,and reaction mechanism.Rapid fundamental advances may be possible in non-precious metal and metal-free catalysts that are highly efficient under the base-free conditions,and external field-assisted processes like electrochemical or photoelectrochemical cells.展开更多
A series of nanosized CeO2-Fe2O3 mixed-oxide nanocomposites with different Ce4+/Fe3+molar ratios were successfully prepared by a co-precipitation technique.The surface area increased with Fe2O3 content increasing up t...A series of nanosized CeO2-Fe2O3 mixed-oxide nanocomposites with different Ce4+/Fe3+molar ratios were successfully prepared by a co-precipitation technique.The surface area increased with Fe2O3 content increasing up to 60 wt%in the composite.However,with further increase in Fe2O3 content,the surface area began to decrease.The reduction processes of the CeO2-Fe2O3 nanocomposites were studied in a hydrogen atmosphere at 300-600℃.The reduction rates increased by increasing both the temperature and Fe2O3 content in the nanocomposites.The microstructure of the reduced composites at 500℃illustrated the presence of a considerable number of macro-and micro-pores.The activation energy values were calculated which were in the range of 3.56-5.37 kJ mol-1 at the initial stages(up to 35%reduction)and 5.21-10.2 kJ·mol-1 at the final stages(up to 80%reduction)of reduction.The rate-controlling mechanisms in both the initial and final reduction stages were determined,and the initial reaction stage was controlled by combined gaseous diffusion and interfacial chemical reaction mechanisms for all the composites except for pure CeO2,which was controlled by a chemical reaction mechanism.The final reaction stage was controlled by a gaseous diffusion mechanism for some composites,while for the others it was controlled by combined gaseous diffusion and interfacial chemical reaction mechanisms.The hydrogen sorption properties of the nanocomposites were studied by pressure composition isotherms using a volumetric method.Hydrogen storage in the nanocomposites increased by increasing the temperature because of the formation of oxygen vacancies which enhance atomic H adsorption and function as strong adsorption sites forming more metal hydride covalent bonds.展开更多
Lithium/Sodium-ion batteries(LIB/SIB)have attracted enormous attention as a promising electrochemical energy storage system due to their high energy density and long cycle life.One of the major hurdles is the initial ...Lithium/Sodium-ion batteries(LIB/SIB)have attracted enormous attention as a promising electrochemical energy storage system due to their high energy density and long cycle life.One of the major hurdles is the initial irreversible capacity loss during the first few cycles owing to forming the solid electrolyte interphase layer(SEI).This process consumes a profusion of lithium/sodium,which reduces the overall energy density and cycle life.Thus,a suitable approach to compensate for the irreversible capacity loss must be developed to improve the energy density and cycle life.Pre-lithiation/sodiation is a widely accepted process to compensate for the irreversible capacity loss during the initial cycles.Various strategies such as physical,chemical,and electrochemical pre-lithiation/sodiation have been explored;however,these approaches add an extra step to the current manufacturing process.Alternative to these strategies,pre-lithiation/sodiation additives have attracted enormous attention due to their easy adaptability and compatibility with the current battery manufacturing process.In this review,we consolidate recent developments and emphasize the importance of using pre-lithiation/sodiation additives(anode and cathode)to overcome the irreversible capacity loss during the initial cycles in lithium/sodium-ion batteries.This review also addresses the technical and scientific challenges of using pre-lithiation/sodiation additives and offers the insights to boost the energy density and cycle life with their possible commercial exploration.The most important prerequisites for designing effective pre-lithiation/sodiation additives have been explored and the future directions have been discussed.展开更多
The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0....The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFM） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.展开更多
The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance,especially in societies with a large elderly population.Self-assembled peptide hydrogels are a new generat...The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance,especially in societies with a large elderly population.Self-assembled peptide hydrogels are a new generation of biomaterials that provide excellent biocompatibility,tunable mechanical stability,injectability,trigger capability,lack of immunogenic reactions,and the ability to load cells and active pharmaceutical agents for tissue regeneration.Peptide-based hydrogels are ideal templates for the deposition of hydroxyapatite crystals,which can mimic the extracellular matrix.Thus,peptide-based hydrogels enhance hard tissue repair and regeneration compared to conventional methods.This review presents three major self-assembled peptide hydrogels with potential application for bone and dental tissue regeneration,including ionic self-complementary peptides,amphiphilic(surfactant-like)peptides,and triple-helix(collagen-like)peptides.Special attention is given to the main bioactive peptides,the role and importance of self-assembled peptide hydrogels,and a brief overview on molecular simulation of self-assembled peptide hydrogels applied for bone and dental tissue engineering and regeneration.展开更多
Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties...Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continu- ous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M marten- site phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation （MIR）. In situ magnetic domain structure observation on the film deposited at 873 K reflects that the marten- sitic transformation could be divided into two periods： nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH = 0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.展开更多
Objective:To determine the antileishmanial vaccine effectiveness of lipophosphoglycan(LPG)and polyacrylic acids(PAA)conjugates on in vivo mice models.Methods:LPG molecule was isolated and purified from large-scale Lei...Objective:To determine the antileishmanial vaccine effectiveness of lipophosphoglycan(LPG)and polyacrylic acids(PAA)conjugates on in vivo mice models.Methods:LPG molecule was isolated and purified from large-scale Leishmania donovani parasite culture.Protection efficacies of LPG alone,in combination with Freund's adjuvant,in a physical mixture and in conjugate(consisting of various LPG concentrations)with PAA,were comparatively determined by various techniques,such as cultivation with the micro-culture method,assessment of in vitro infection rates of peritoneal macrophages,determination of parasite load in liver with Leishman-Donovan Units,and detection of cytokine responses.Results:Obtained results demonstrated that the highest vaccine-mediated immune protection was provided by LPG-PAA conjugate due to all parameters investigated.According to the Leishman-Donovan Units results,the sharpest decline in parasite load was seen with a ratio of 81.17%when 35 mg LPG containing conjugate was applied.This value was 44.93%for the control group immunized only with LPG.Moreover,decreases in parasite load were 53.37%,55.2%and 65.8%for the groups immunized with 10 mg LPG containing LPG-PAA conjugate,a physical mixture of the LPG–PAA,and a mixture of LPG+Freund's adjuvant,respectively.Furthermore,cytokine results supported that Th1 mediated protection occurred when mice were immunized with LPG-PAA conjugate.Conclusions:It has been demonstrated in this study that conjugate of LPG and PAA has an antileishmanial vaccine effect against visceral leishmaniasis.In this respect,the present study may lead to new vaccine approaches based on high immunogenic LPG molecule and adjuvant polymers in fighting against Leishmania infection.展开更多
Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence ...Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence of the reversible magnetic field-induced reorientation. Magnetic domain structure and twin structure of the film were controlled by the in- terplay of the magnetic and temperature field. With cooling under an out-of-plane magnetic field, the evolution of magnetic domain structure reveals that martensitic transformation could be divided into two periods： nucleation and growth. With an in-plane magnetic field applied to a thermomagnetic-treated film, the evolution of magnetic domain structure gives evidence of a reorientation of twin variants of martensite. A microstructural model is described to define the twin structure and to produce the magnetic domain structure at the beginning of martensitic transformation; based on this model, the relationship between the twin structure and the magnetic domain structure for the treated film under an in-plane field is also described.展开更多
The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary cha...The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.展开更多
Based on the good extensibility and conductivity,the flexible sensors(FSs)have a wide range of applications in the field of the electrochemical energy storage and variable stress sensors,which causes that the preparat...Based on the good extensibility and conductivity,the flexible sensors(FSs)have a wide range of applications in the field of the electrochemical energy storage and variable stress sensors,which causes that the preparation of FSs also become a hot spot of research.Among the materials for preparing the FSs,the flexible carbon matrix composites(FCMCs)have become the widely used material since the good performance in the properties of electrochemistry and mechanics,which could be divided into three types:the carbon nanofibers(CNFs),the carbon nanospheres(CNSs)and the carbon nanotubes(CNTs).Compared with CNFs and CNSs,the CNTs wrapped by the polydimethylsiloxane(PDMS)have the advantages of the excellent extensibility and electrochemical stability.Therefore,the CNTs flexible sensor(CFS)could be well used in the field of the FSs.The purpose of this review is summarizing the preparation methods and application fields of CFS and proposing the research direction of CFS in the future.In this paper,two methods for fabricating the CFS have been designed by consulting the methods mentioned in the literature in recent years,and the advantages and disadvantages between the two methods have been explained.The application fields of CFS in recent years are enumerated,and the conclusion that the application fields of CFS are very wide is drawn.At the end of this paper,the review concludes with an overview of key remaining challenges in the application fields of the CFS.展开更多
Diseases and disorders associated with nervous system such as injuries by trauma and neurodegeneration are shown to be one of the most serious problems in medicine, requiring innovative strategies to trigger and enhan...Diseases and disorders associated with nervous system such as injuries by trauma and neurodegeneration are shown to be one of the most serious problems in medicine, requiring innovative strategies to trigger and enhance the nerve regeneration. Tissue engineering aims to provide a highly biomimetic environment by using a combination of cells, materials and suitable biological cues, by which the lost body part may be regenerated or even fully rebuilt. Electrospinning, being able to produce extracellular matrix （ECM）-like nanostructures with great flexibility in design and choice of materials, have demonstrated their great po- tential for fabrication of nerve tissue engineered scaffolds. The review here begins with a brief description of the anatomy of native nervous system, which provides basic knowledge and ideas for the design of nerve tissue scaffolds, followed by five main parts in the design of electrospun nerve tissue engineered scaffolds including materials selection, structural design, in vitro bioreactor, functionalization and cellular support. Performances of biomimetic electrospun nanofibrous nerve implant devices are also reviewed. Finally, future directions for advanced electrospun nerve tissue engineered scaffolds are discussed.展开更多
This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, t...This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, the paper focuses on the effect of adding Al2O3 nanopartiles in PAN nanofibers, which were incorporated in unidirectional （UD） laminates. The effectiveness of adding a thin film made of Al2O3-PAN on the fracture behavior of the carbon fiber reinforced polymer （CFRP） has been addressed by comparing the energy release rates, obtained by testing double cantilever beam （DCB） samples under mode I loading condition. A general improvement in interlaminar fracture energy of the CFRP is observed when the both neat PAN nanofibers and Al2O3-PAN nanofibers are interleaved. However, higher interlaminar strength has been observed for the samples with a thin film of Al2O3-PAN nanofibers, suggesting a better stress distribution and stress transformation from resin-rich area to reinforcement phase of hybrid composites.展开更多
Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based n...Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based nanoparticles were homogenously integrated within the polymer matrix,facilitating penetration of CO_2 through the membrane while acting as barrier for methane gas.The membrane containing 4.6 wt% fumed silica(FS)(PEBAX/4.6 wt%FS)exhibits astonishing selectivity results where binary gas mixture of CO_2/CH_4 was used as feed gas.As detected by gas chromatography,in the permeate side,data showed a significant increase of CO_2 permeance,while CH_4 transport through the mixed matrix membrane was not detectable.Moreover,PEBAX/4.6 wt%FS greatly exceeds the Robeson limit.According to data reported on CO_2/CH_4 gas pair separation in the literature,the results achieved in this work are beyond those data reported in the literature,particularly when PEBAX/4.6 wt%FS membrane was utilized.展开更多
BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24...BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24, were subject to studies of ethene, cis-2-butene and ethene-butene mixture conversion under conditions where C3-C5 alkene formation is thermodynamically favoured over higher hydrocarbons(673-823 K, 1 atm). Ethene and cis-2-butene partial pressures were varied in the range 9-60 and 0.9-8.1 kPa, respectively, and contact times were varied in the range 3.78-756 and 0.573-76.4 s.μmol H+/cm^3 over H-SAPO-5 and H-SSZ-24, respectively. Less than 1% conversion of ethene and less than 10% conversion of butene was obtained in the range of conditions used for elucidation of rate parameters. The ethene conversion rates were more than an order of magnitude higher over the more acidic H-SSZ-24 than over H-SAPO-5(6.5 vs. 0.3 mmol/mol H+.s at 748 K, Pethene = 33 kP a), with corresponding lower reaction order in ethene(1.5 vs. 2.0 at 673 K) and lower apparent activation energy(52 vs. 80 kJ/mol at 698-823 K). Propene selectivity was substantially higher over H-SSZ-24 than over H-SAPO-5(68% vs. 36% at 0.5% ethene conversion). A similar difference in apparent reaction rates was observed for cis-2-butene conversion over the two catalysts, and for co-feeds of ethene and cis-2-butene. However, the cis-2-butene conversion to C3-C5 alkenes was found to be severely influenced by thermodynamic limitations, impeding a detailed kinetic analysis, and leading predominantly to isobutene formation at the highest temperatures.展开更多
ZnO and Mn-doped ZnO polycrystalline films are prepared by plasma enhanced chemical vapour deposition at low temperature （220℃）, and room-temperature photoluminescence of the films is systematically investigated. A...ZnO and Mn-doped ZnO polycrystalline films are prepared by plasma enhanced chemical vapour deposition at low temperature （220℃）, and room-temperature photoluminescence of the films is systematically investigated. Analysis from x-ray diffraction reveals that a11 the prepared films exhibit the wurtzite structure of ZnO, and Mndoping does not induce the second phase in the films. X-ray photoelectron spectroscopy confirms the existence of Mn^2＋ ions in the films rather than metalic Mn or Mn^4＋ ions. The emission efficiency of the ZnO film is found to be dependent strongly on the post-treatment and to degrade with increasing temperature either in air or in nitrogen ambient. However, the enhancement of near band edge （NBE） emission is observed after hydrogenation in ammonia plasma, companied with more defect-related emission. Furthermore, the position of NBE shifts towards to high-energy legion with increasing Mn-doped concentration due to Mn incorporation into ZnO lattice.展开更多
基金support from the National Natural Science Foundation of China(22072170,U23A20125)the Zhejiang Provincial Key Research and Development Program(2021C03170).
文摘Photothermal energy conversion represents a cornerstone process in the renewable energy technologies domain,enabling the capture of solar irradiance and its subsequent transformation into thermal energy.This mechanism is paramount across many applications,facilitating the exploitation of solar energy for different purposes.The photothermal conversion efficiency and applications are fundamentally contingent upon the characteristics and performance of the materials employed.Consequently,deploying high-caliber materials is essential for optimizing energy capture and utilization.Within this context,photothermal nanomaterials have emerged as pivotal components in various applications,ranging from catalysis and sterilization to medical therapy,desalination,and electric power generation via the photothermal conversion effect.This review endeavors to encapsulate the current research landscape,delineating both the developmental trajectories and application horizons of photothermal conversion materials.It aims to furnish a detailed exposition of the mechanisms underlying photothermal conversion across various materials,shedding light on the principles guiding the design of photothermal nanomaterials.Furthermore,addressing the prevailing challenges and outlooks within the field elucidates potential avenues for future research and identifying priority areas.This review aspires to enrich the understanding of photothermal materials within the framework of energy conversion,offering novel insights and fostering a more profound comprehension of their role and potential in harnessing solar energy.
文摘In recent times,there has been a surge of attention towards advanced high-performance materials for storing energy,specifically in supercapacitors.One encouraging method involves utilizing nanocomposites based on transition metal oxides/graphene which have demonstrated significant potential for improving capacitance.The electrochemical properties of titanium oxide doped graphene in current research have been improved through the incorporation of rare earth metals.The hydrothermal technique was chosen for the fabrication of nanocomposites as electrode materials.X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FT-IR),and scanning electron microscopy(SEM) approaches were employed for the characterization of nanocomposites.Ternary and quaternary nanocomposites with 2 wt% rare earth elements doped with titanium oxide and graphene were synthesized with various ratios of lanthanum and cerium as dopants.In 2 wt% La:Ce-TiO_(2)/rGO,lanthanum,and cerium were doped in 1:1,1:3,and 1:5 ratios.2 wt% La:Ce(1:5)-TiO_(2)/rGO among co-doped composites exhibits better capacitive performance as determined through cyclic voltammetry and galvanostatic charge-discharge.Among all the nanocomposites 422 F/g was the maximum depicted by 2 wt%La:Ce(1:5)-TiO_(2)/rGO at a scan rate of 10 mV/s(potential window from-0.4 to+0.6 V) and 1895 F/g at1 mV/s(potential window-0.6 to+0.6 V).specific capacitance was also determined via GCD,and a maximum capacitance of 486 F/g is depicted by 2 wt% La:Ce(1:5)-TiO_(2)/rGO.The same composites have also served as promising electrode materials in terms of columbic efficiency,power,and energy density.
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funded by the National Key R&D Program of China(2022YFE0140400)the National Natural Science Foundation of China(62405027, 62111530238, 62003046)+3 种基金Supporting project of major scientific research projects of Beijing Normal University at Zhuhai (ZHPT2023007)supported by the Tang Scholar of Beijing Normal Universityco-funded by the financial support of the European Union under the REFRESH-Research Excellence For REgion Sustainability and High-tech Industries project number CZ.10.03.01/00/22003/0000048 via the Operational Programme Just Transitionthe scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) financed by national funds through the FCT/MCTES (PIDDAC)
文摘Personalized health services are of paramount importance for the treatment and prevention of cardiorespiratory diseases,such as hypertension.The assessment of cardiorespiratory function and biometric identification(ID)is crucial for the effectiveness of such personalized health services.To effectively and accurately monitor pulse wave signals,thus achieving the assessment of cardiorespiratory function,a wearable photonic smart wristband based on an all-polymer sensing unit(All-PSU)is proposed.The smart wristband enables the assessment of cardiorespiratory function by continuously monitoring respiratory rate(RR),heart rate(HR),and blood pressure(BP).Furthermore,it can be utilized for biometric ID purposes.Through the analysis of pulse wave signals using power spectral density(PSD),accurate monitoring of RR and HR is achieved.Additionally,utilizing peak detection algorithms for feature extraction from pulse signals and subsequently employing a variety of machine learning methods,accurate BP monitoring and biometric ID have been realized.For biometric ID,the accuracy rate is 98.55%.Aiming to monitor RR,HR,BP,and ID,our solution demonstrates advantages in integration,functionality,and monitoring precision.These enhancements may contribute to the development of personalized health services aimed at the treatment and prevention of cardiorespiratory diseases.
基金supported by Chinese Academy of Sciences(QYZDB-SSW-JSC037)Natural Science Foundation of Zhejiang Province(LY19B030003,LQ19B060002)+1 种基金Ningbo Science and Technology Bureau(2018B10056,2019B10096)Fujian Institute of Innovation(FJCXY18020202)。
文摘Biomass conversion to value-added chemicals has received tremendous attention for solving global warming issues and fossil fuel depletion.5-Hydroxymethylfurfural(HMF)is a key bio-based platform molecule to produce many useful organic chemicals by oxidation,hydrogenation,polymerization,and ring-opening reactions.Among all derivatives,the oxidation product 2,5-furandicarboxylic acid(FDCA)is a promising alternative to petroleum-based terephthalic acid for the synthesis of biodegradable plastics.This review analytically discusses the recent progress in the thermocatalytic,electrocatalytic,and photocatalytic oxidation of HMF into FDCA,including catalyst screening,synthesis processes,and reaction mechanism.Rapid fundamental advances may be possible in non-precious metal and metal-free catalysts that are highly efficient under the base-free conditions,and external field-assisted processes like electrochemical or photoelectrochemical cells.
文摘A series of nanosized CeO2-Fe2O3 mixed-oxide nanocomposites with different Ce4+/Fe3+molar ratios were successfully prepared by a co-precipitation technique.The surface area increased with Fe2O3 content increasing up to 60 wt%in the composite.However,with further increase in Fe2O3 content,the surface area began to decrease.The reduction processes of the CeO2-Fe2O3 nanocomposites were studied in a hydrogen atmosphere at 300-600℃.The reduction rates increased by increasing both the temperature and Fe2O3 content in the nanocomposites.The microstructure of the reduced composites at 500℃illustrated the presence of a considerable number of macro-and micro-pores.The activation energy values were calculated which were in the range of 3.56-5.37 kJ mol-1 at the initial stages(up to 35%reduction)and 5.21-10.2 kJ·mol-1 at the final stages(up to 80%reduction)of reduction.The rate-controlling mechanisms in both the initial and final reduction stages were determined,and the initial reaction stage was controlled by combined gaseous diffusion and interfacial chemical reaction mechanisms for all the composites except for pure CeO2,which was controlled by a chemical reaction mechanism.The final reaction stage was controlled by a gaseous diffusion mechanism for some composites,while for the others it was controlled by combined gaseous diffusion and interfacial chemical reaction mechanisms.The hydrogen sorption properties of the nanocomposites were studied by pressure composition isotherms using a volumetric method.Hydrogen storage in the nanocomposites increased by increasing the temperature because of the formation of oxygen vacancies which enhance atomic H adsorption and function as strong adsorption sites forming more metal hydride covalent bonds.
基金the support of the Deputyship for Research and Innovation-Ministry of Education,Kingdom of Saudi Arabia,for this research through a grant(NU/IFC/INT/01/002)under the Institutional Funding Committee at Najran University,Kingdom of Saudi Arabiathe support from the National Research Foundation of Korea(NRF)funded by the Brain Pool program(2021H1D3A2A02039346)。
文摘Lithium/Sodium-ion batteries(LIB/SIB)have attracted enormous attention as a promising electrochemical energy storage system due to their high energy density and long cycle life.One of the major hurdles is the initial irreversible capacity loss during the first few cycles owing to forming the solid electrolyte interphase layer(SEI).This process consumes a profusion of lithium/sodium,which reduces the overall energy density and cycle life.Thus,a suitable approach to compensate for the irreversible capacity loss must be developed to improve the energy density and cycle life.Pre-lithiation/sodiation is a widely accepted process to compensate for the irreversible capacity loss during the initial cycles.Various strategies such as physical,chemical,and electrochemical pre-lithiation/sodiation have been explored;however,these approaches add an extra step to the current manufacturing process.Alternative to these strategies,pre-lithiation/sodiation additives have attracted enormous attention due to their easy adaptability and compatibility with the current battery manufacturing process.In this review,we consolidate recent developments and emphasize the importance of using pre-lithiation/sodiation additives(anode and cathode)to overcome the irreversible capacity loss during the initial cycles in lithium/sodium-ion batteries.This review also addresses the technical and scientific challenges of using pre-lithiation/sodiation additives and offers the insights to boost the energy density and cycle life with their possible commercial exploration.The most important prerequisites for designing effective pre-lithiation/sodiation additives have been explored and the future directions have been discussed.
基金Project supported by ACIISI of Gobierno de Canarias (ID20100152)Ministerio de Economíay Competitividad of Spain(MINECO)within the National Program of Materials(MAT2010-21270-C04-02/-03/-04)+2 种基金the Consol-ider-Ingenio 2010 Program(MALTACSD2007-0045,www.malta-consolider.com)ACIISI(Gobierno de canarias)project ID20100152governments of Spainand India for the award of a project within the indo-Spanish Joint Programme of Cooperation in Science and Technology(PRI-PIBIN-2011-1153/DST-INT-Spain-P-38-11)
文摘The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋ （0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFM） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.
文摘The development of natural biomaterials applied for hard tissue repair and regeneration is of great importance,especially in societies with a large elderly population.Self-assembled peptide hydrogels are a new generation of biomaterials that provide excellent biocompatibility,tunable mechanical stability,injectability,trigger capability,lack of immunogenic reactions,and the ability to load cells and active pharmaceutical agents for tissue regeneration.Peptide-based hydrogels are ideal templates for the deposition of hydroxyapatite crystals,which can mimic the extracellular matrix.Thus,peptide-based hydrogels enhance hard tissue repair and regeneration compared to conventional methods.This review presents three major self-assembled peptide hydrogels with potential application for bone and dental tissue regeneration,including ionic self-complementary peptides,amphiphilic(surfactant-like)peptides,and triple-helix(collagen-like)peptides.Special attention is given to the main bioactive peptides,the role and importance of self-assembled peptide hydrogels,and a brief overview on molecular simulation of self-assembled peptide hydrogels applied for bone and dental tissue engineering and regeneration.
基金Project supported by the National Key Project of Fundamental Research of China (Grant No.2012CB932304)the National Natural Science Foundation of China (Grant No.50831006)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Ferromagnetic Ni-Mn-Ga films were fabricated by depositing on MgO （001） substrates at temperatures from 673 K to 923 K. Microstructure, crystal structure, martensitic transformation behavior, and magnetic properties of the films were studied. With increasing deposition temperature, the surface morphology of the films transforms from granular to continu- ous. The martensitic transformation temperature is not dependent on deposition temperature; while transformation behavior is affected substantially by deposition temperature. X-ray analysis reveals that the film deposited at 873 K has a 7M marten- site phase, and its magnetization curve provides a typical step-increase, indicating the occurrence of magnetically induced reorientation （MIR）. In situ magnetic domain structure observation on the film deposited at 873 K reflects that the marten- sitic transformation could be divided into two periods： nucleation and growth, in the form of stripe domains. The MIR occurs at the temperature at which martensitic transformation starts, and the switching field increases with the decrease of temperature due to damped thermal activation. The magnetically induced martensitic transformation is related to the difference of magnetization between martensite and austenite. A shift of martensite temperature of dT/dH = 0.43 K/T is observed, consistent with the theoretical value, 0.41 K/T.
基金financially supported by TUBITAK(1085170SBAG–4007)
文摘Objective:To determine the antileishmanial vaccine effectiveness of lipophosphoglycan(LPG)and polyacrylic acids(PAA)conjugates on in vivo mice models.Methods:LPG molecule was isolated and purified from large-scale Leishmania donovani parasite culture.Protection efficacies of LPG alone,in combination with Freund's adjuvant,in a physical mixture and in conjugate(consisting of various LPG concentrations)with PAA,were comparatively determined by various techniques,such as cultivation with the micro-culture method,assessment of in vitro infection rates of peritoneal macrophages,determination of parasite load in liver with Leishman-Donovan Units,and detection of cytokine responses.Results:Obtained results demonstrated that the highest vaccine-mediated immune protection was provided by LPG-PAA conjugate due to all parameters investigated.According to the Leishman-Donovan Units results,the sharpest decline in parasite load was seen with a ratio of 81.17%when 35 mg LPG containing conjugate was applied.This value was 44.93%for the control group immunized only with LPG.Moreover,decreases in parasite load were 53.37%,55.2%and 65.8%for the groups immunized with 10 mg LPG containing LPG-PAA conjugate,a physical mixture of the LPG–PAA,and a mixture of LPG+Freund's adjuvant,respectively.Furthermore,cytokine results supported that Th1 mediated protection occurred when mice were immunized with LPG-PAA conjugate.Conclusions:It has been demonstrated in this study that conjugate of LPG and PAA has an antileishmanial vaccine effect against visceral leishmaniasis.In this respect,the present study may lead to new vaccine approaches based on high immunogenic LPG molecule and adjuvant polymers in fighting against Leishmania infection.
基金supported by the National Key Project of Fundamental Research of China(Grant No.2012CB932304)the National Natural Science Foundation of China(Grant No.50831006)+1 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-11-0156)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Ferromagnetic shape memory Ni-Mn-Ga films with 7M modulated structure were prepared on MgO （001） substrates by magnetron sputtering. Magnetization process with a typical two-hysteresis loop indicates the occurrence of the reversible magnetic field-induced reorientation. Magnetic domain structure and twin structure of the film were controlled by the in- terplay of the magnetic and temperature field. With cooling under an out-of-plane magnetic field, the evolution of magnetic domain structure reveals that martensitic transformation could be divided into two periods： nucleation and growth. With an in-plane magnetic field applied to a thermomagnetic-treated film, the evolution of magnetic domain structure gives evidence of a reorientation of twin variants of martensite. A microstructural model is described to define the twin structure and to produce the magnetic domain structure at the beginning of martensitic transformation; based on this model, the relationship between the twin structure and the magnetic domain structure for the treated film under an in-plane field is also described.
基金Thiswork is financially supported by IranUniversity of Science and Technology(IUST)and Motamed Cancer Institute(ACECR).
文摘The optimization of the scaffolds to provide a suitable matrix and accelerate the regeneration process is vital for bone tissue engineering.However,poor mechanical and biological characteristics remain the primary challenges that must be addressed.For example,although bredigite(Br)has shown great potential for application in bone tissue engineering,it easily fails in replacement.In the present work,these challenges are addressed by reinforcing the Br matrix with nanosheets of graphene oxide(rGO)that have been reduced by bovine serum albumin(BSA)in order to enhance the mechanical properties and biological behavior.The reduction of graphene oxide by BSA improves the water stability of the nanosheets and provides an electrostatic interaction between theBSA-rGO nanosheets and theBr particles.The high thermal conductivity of theBSA-rGO nanosheets decreases the porosity of the Br by transferring heat to the core of the tablet.Furthermore,the addition of BSA-rGO nanosheets into the Br matrix enhances the adhesion of G-292 cells on the surface of the tablets.These findings suggest that the tablet consisting of BSA-rGO-reinforced Br has encouraging potential for application in bone tissue engineering.
基金supported by the Qingdao Postdoctoral Fund and Key Research (No. 2015118)the Development Plan of Shandong Province (No. 2017GGX50114 and No. 2018GGX105007)+1 种基金the Scientific Research Development Plan of Shandong Higher Education Institutions (No. J18KA316)National Natural Science Foundation of China (No. 60123456)
文摘Based on the good extensibility and conductivity,the flexible sensors(FSs)have a wide range of applications in the field of the electrochemical energy storage and variable stress sensors,which causes that the preparation of FSs also become a hot spot of research.Among the materials for preparing the FSs,the flexible carbon matrix composites(FCMCs)have become the widely used material since the good performance in the properties of electrochemistry and mechanics,which could be divided into three types:the carbon nanofibers(CNFs),the carbon nanospheres(CNSs)and the carbon nanotubes(CNTs).Compared with CNFs and CNSs,the CNTs wrapped by the polydimethylsiloxane(PDMS)have the advantages of the excellent extensibility and electrochemical stability.Therefore,the CNTs flexible sensor(CFS)could be well used in the field of the FSs.The purpose of this review is summarizing the preparation methods and application fields of CFS and proposing the research direction of CFS in the future.In this paper,two methods for fabricating the CFS have been designed by consulting the methods mentioned in the literature in recent years,and the advantages and disadvantages between the two methods have been explained.The application fields of CFS in recent years are enumerated,and the conclusion that the application fields of CFS are very wide is drawn.At the end of this paper,the review concludes with an overview of key remaining challenges in the application fields of the CFS.
文摘Diseases and disorders associated with nervous system such as injuries by trauma and neurodegeneration are shown to be one of the most serious problems in medicine, requiring innovative strategies to trigger and enhance the nerve regeneration. Tissue engineering aims to provide a highly biomimetic environment by using a combination of cells, materials and suitable biological cues, by which the lost body part may be regenerated or even fully rebuilt. Electrospinning, being able to produce extracellular matrix （ECM）-like nanostructures with great flexibility in design and choice of materials, have demonstrated their great po- tential for fabrication of nerve tissue engineered scaffolds. The review here begins with a brief description of the anatomy of native nervous system, which provides basic knowledge and ideas for the design of nerve tissue scaffolds, followed by five main parts in the design of electrospun nerve tissue engineered scaffolds including materials selection, structural design, in vitro bioreactor, functionalization and cellular support. Performances of biomimetic electrospun nanofibrous nerve implant devices are also reviewed. Finally, future directions for advanced electrospun nerve tissue engineered scaffolds are discussed.
文摘This paper presents an experimental investigation on fracture behavior of epoxy resin-carbon fibers composites interleaved with both neat polyacrylonitrile （PAN） nanofibers and A1203-PAN nanofibers. In particular, the paper focuses on the effect of adding Al2O3 nanopartiles in PAN nanofibers, which were incorporated in unidirectional （UD） laminates. The effectiveness of adding a thin film made of Al2O3-PAN on the fracture behavior of the carbon fiber reinforced polymer （CFRP） has been addressed by comparing the energy release rates, obtained by testing double cantilever beam （DCB） samples under mode I loading condition. A general improvement in interlaminar fracture energy of the CFRP is observed when the both neat PAN nanofibers and Al2O3-PAN nanofibers are interleaved. However, higher interlaminar strength has been observed for the samples with a thin film of Al2O3-PAN nanofibers, suggesting a better stress distribution and stress transformation from resin-rich area to reinforcement phase of hybrid composites.
基金financial support of Research Institute of Petroleum Industry
文摘Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based nanoparticles were homogenously integrated within the polymer matrix,facilitating penetration of CO_2 through the membrane while acting as barrier for methane gas.The membrane containing 4.6 wt% fumed silica(FS)(PEBAX/4.6 wt%FS)exhibits astonishing selectivity results where binary gas mixture of CO_2/CH_4 was used as feed gas.As detected by gas chromatography,in the permeate side,data showed a significant increase of CO_2 permeance,while CH_4 transport through the mixed matrix membrane was not detectable.Moreover,PEBAX/4.6 wt%FS greatly exceeds the Robeson limit.According to data reported on CO_2/CH_4 gas pair separation in the literature,the results achieved in this work are beyond those data reported in the literature,particularly when PEBAX/4.6 wt%FS membrane was utilized.
文摘BrФnsted-acidic zeolite and zeotype materials are potential catalysts for the conversion of ethene to higher alkenes. In this study, two materials with AFI structure but different acid strength, H-SAPO-5 and H-SSZ-24, were subject to studies of ethene, cis-2-butene and ethene-butene mixture conversion under conditions where C3-C5 alkene formation is thermodynamically favoured over higher hydrocarbons(673-823 K, 1 atm). Ethene and cis-2-butene partial pressures were varied in the range 9-60 and 0.9-8.1 kPa, respectively, and contact times were varied in the range 3.78-756 and 0.573-76.4 s.μmol H+/cm^3 over H-SAPO-5 and H-SSZ-24, respectively. Less than 1% conversion of ethene and less than 10% conversion of butene was obtained in the range of conditions used for elucidation of rate parameters. The ethene conversion rates were more than an order of magnitude higher over the more acidic H-SSZ-24 than over H-SAPO-5(6.5 vs. 0.3 mmol/mol H+.s at 748 K, Pethene = 33 kP a), with corresponding lower reaction order in ethene(1.5 vs. 2.0 at 673 K) and lower apparent activation energy(52 vs. 80 kJ/mol at 698-823 K). Propene selectivity was substantially higher over H-SSZ-24 than over H-SAPO-5(68% vs. 36% at 0.5% ethene conversion). A similar difference in apparent reaction rates was observed for cis-2-butene conversion over the two catalysts, and for co-feeds of ethene and cis-2-butene. However, the cis-2-butene conversion to C3-C5 alkenes was found to be severely influenced by thermodynamic limitations, impeding a detailed kinetic analysis, and leading predominantly to isobutene formation at the highest temperatures.
基金Supported by the National Key Basic Research Programme of China under Grant No 2005CB623605, and the National Natural Science Foundation of China under Grant Nos 10374044 and 60676055.
文摘ZnO and Mn-doped ZnO polycrystalline films are prepared by plasma enhanced chemical vapour deposition at low temperature （220℃）, and room-temperature photoluminescence of the films is systematically investigated. Analysis from x-ray diffraction reveals that a11 the prepared films exhibit the wurtzite structure of ZnO, and Mndoping does not induce the second phase in the films. X-ray photoelectron spectroscopy confirms the existence of Mn^2＋ ions in the films rather than metalic Mn or Mn^4＋ ions. The emission efficiency of the ZnO film is found to be dependent strongly on the post-treatment and to degrade with increasing temperature either in air or in nitrogen ambient. However, the enhancement of near band edge （NBE） emission is observed after hydrogenation in ammonia plasma, companied with more defect-related emission. Furthermore, the position of NBE shifts towards to high-energy legion with increasing Mn-doped concentration due to Mn incorporation into ZnO lattice.
