The nanotechnology is of great siguifieance to the country＇s future economic, social development and national security, and it will bring a revolutionary change to the medicine, manufacturing, materials and informati...The nanotechnology is of great siguifieance to the country＇s future economic, social development and national security, and it will bring a revolutionary change to the medicine, manufacturing, materials and information communication and other industries, therefore, in recent years, nano science and technology is greatly favored all over the world especially in developed countries. All the countries （areas） in the world have developed the nanotechnology as the main driver of the technical innovation in the twenty-first century, and have formulated development strategies and plans, to promote and guide their development in nanotechnology, which lead to fiercer and fiercer competition. In this paper, the author mainly introduces the application of nano materials in catalysis, filtration, separation, paint and new fine chemical industry and so on.展开更多
Partial hepatectomy(PH)can lead to severe complications,including liver failure,due to the low regenerative capacity of the remaining liver,especially after extensive hepatectomy.Liver sinusoidal endothelial cells(LSE...Partial hepatectomy(PH)can lead to severe complications,including liver failure,due to the low regenerative capacity of the remaining liver,especially after extensive hepatectomy.Liver sinusoidal endothelial cells(LSECs),whose proliferation occurs more slowly and later than hepatocytes after PH,compose the lining of the hepatic sinusoids,which are the smallest blood vessels in the liver.Vascular endothelial growth factor(VEGF),secreted by hepatocytes,promotes LSEC proliferation.Supplementation of exogenous VEGF after hepatectomy also increases the number of LSECs in the remaining liver,thus promoting the reestablishment of the hepatic sinusoids and accelerating liver regeneration.At present,some shortcomings exist in the methods of supplementing exogenous VEGF,such as a low drug concentration in the liver and the reaching of other organs.Moreover,VEGF should be administered multiple times and in large doses because of its short half-life.This review summarized the most recent findings on liver regeneration and new strategies for the localized delivery VEGF in the liver.展开更多
A triethylenetetramine epoxy mixture was synthesized through the reaction of a low-molecular-weight liquid epoxy resin with triethylenetetramine(TETA).Then triethyltetramine(TETA)was injected dropwise into a pro-pylen...A triethylenetetramine epoxy mixture was synthesized through the reaction of a low-molecular-weight liquid epoxy resin with triethylenetetramine(TETA).Then triethyltetramine(TETA)was injected dropwise into a pro-pylene glycol methyl ether(PM)solution for chain extension reaction.A hydrophilic andflexible polyether seg-ment was introduced into the hardener molecule.The effects of TETA/DGEPG,reaction temperature and reaction time on the epoxy conversion of polyethylene glycol diglycidyl ether(DGEPG)were studied.In addition,several alternate strategies to add epoxy resin to the high-speed dispersion machine and synthesize MEA DGEBA adduct(without catalyst and with bisphenol A diglycidyl ether epoxy resin)were compared.It was found that the higher the molecular weight of triethylenetetramine,the longer the chain segment of the surface active molecule.When the equivalence ratio of amine hydrogen and epoxy group is low,the stability of lotion is good.When the ratio of amine hydrogen to epoxy group is large,the content of triethylenetetramine is small.The main objective of this study is the provision of new data and knowledge for the development of new materials in the coating and electronic industry.展开更多
The polymerization of amphiphilic self assemblies is a promising method to synthesize nano structured materials with novel properties. These materials have many attractive features for their application in biomedica...The polymerization of amphiphilic self assemblies is a promising method to synthesize nano structured materials with novel properties. These materials have many attractive features for their application in biomedical area and materials science, such as catalysis, separation, surface modification, and therapeutics areas. A general review on the polymerization of lipids and surfactant self assemblies to amphiphilic self assemblies is given in this paper with 49 references. The polymerization and the subsequently resulted structure of lipids in different morphologies are summarized. The polymerization of polymerizable surfactants(surfmers) in emulsion and liquid crystalline phases are also discussed. The potential application of new nano porous materials is briefly described.展开更多
Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both di...Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition （EBID） method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.展开更多
Combustion within small motors is key in the application-specific development of nanothermite-based micro-energetic systems. This study evaluates the performance of nanothermite mixtures in a converging-diverging nozz...Combustion within small motors is key in the application-specific development of nanothermite-based micro-energetic systems. This study evaluates the performance of nanothermite mixtures in a converging-diverging nozzle and an open tube. Mixtures were prepared using nano-aluminum(n-Al),potassium perchlorate(KClO_(4)), and different carbon nanomaterials(CNMs) including graphene-oxide(GO), reduced GO, carbon nanotubes(CNTs) and nanofibers(CNFs). The mixtures were packed at different densities and ignited by laser beam. Performance was measured using thrust measurement,high-speed imaging, and computational fluid dynamics modeling, respectively. Thrust, specific impulse(ISP), volumetric impulse(ISV), as well as normalized energy were found to increase notably with CNM content. Two distinctive reaction regimes(fast and slow) were observed in combustion of low and high packing densities(20% and 55%TMD), respectively. Total impulse(IFT) and ISPwere maximized in the 5%GO/Al/KClO_4 mixture, producing 7.95 m N·s and 135.20 s respectively at 20%TMD, an improvement of 57%compared to a GO-free sample(5.05 m N·s and 85.88 s). CFD analysis of the motors over predicts the thrust generated but trends in nozzle layout and packing density agree with those observed experimentally;peak force was maximized by reducing packing density and using an open tube. The numerical force profiles fit better for the nozzle cases than the open tube scenarios due to the rapid nature of combustion. This study reveals the potential of GO in improving oxygenated salt-based nanothermites,and further demonstrates their applicability for micro-propulsion and micro-energetic applications.展开更多
Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The fre...Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The frequency dependence of AC conductivity follows the Jonscher universal dynamic law.The AC-activation energies are determined at different frequencies.It is found that the correlated barrier hopping（CBH） model is the dominant conduction mechanism.The variation of the frequency exponent s with temperature is analyzed in terms of the CBH model.Coulombic barrier height Wm,hopping distance Rω,and the density of localized states N（EF） are valued at different frequencies.Dielectric constant ε1（ω,T） and dielectric loss ε2（ω,T） are discussed in terms of the dielectric polarization process.The dielectric modulus shows the non-Debye relaxation in the material.The extracted relaxation time by using the imaginary part of modulus（M’’）is found to follow the Arrhenius law.展开更多
With the advent of tissue engineering and biomedicine,the creation of extracellular matrix(ECM)biomaterials for in vitro applications has become a prominent and promising strategy.These ECM materials provide physical,...With the advent of tissue engineering and biomedicine,the creation of extracellular matrix(ECM)biomaterials for in vitro applications has become a prominent and promising strategy.These ECM materials provide physical,biochemical,and mechanical properties that guide cellular behaviors,such as proliferation,differentiation,migration,and apoptosis.Because micro-and nano-patterned materials have a unique surface topology and low energy replication process that directly affect cellular biological behaviors at the interface,the fabrication of micro-nano pattern biomaterials and the regulation of surface physical and chemical properties are of great significance in the fields of cell regulation,tissue engineering,and regenerative medicine.Herein,we provide a comprehensive review of the progress in the fabrication and application of patterned materials based on the coupling of mechanical action at the micro-and nano-meter scale,including photolithography,micro-contact printing,electron beam lithography,electrospinning,and 3D printing technology.Furthermore,a summary of the fabrication process,underlying principles,as well as the advantages and disadvantages of various technologies are reviewed.We also discuss the influence of material properties on the fabrication of micro-and nano-patterns.展开更多
We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the La...We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the Labview software. The current-voltage curves of nano-tip tungsten and carbon nanotube （CNT） arrays were measured. The electron emission of CNTs proceeded with a turn-on field of 1.24 V/μm and a threshold field of 1.85 V/μm. Compared to the field emission, field ionization turned on at 3.5 V/μm. Raman spectroscopy and scanning electron microscopy （SEM） measurements showed degradation of the CNTs after FE/FI testing. The measurement of a W-tip revealed strong electron emission and instability behavior at a field strength higher than 7.0 V/μm.展开更多
The present study is concerned with the physical behavior of the combined effect of nano particle material motion and heat generation/absorption due to the effect of different parameters involved in prescribed flow mo...The present study is concerned with the physical behavior of the combined effect of nano particle material motion and heat generation/absorption due to the effect of different parameters involved in prescribed flow model.The formulation of the flow model is based on basic universal equations of conservation of momentum,energy and mass.The prescribed flow model is converted to non-dimensional form by using suitable scaling.The obtained transformed equations are solved numerically by using finite difference scheme.For the analysis of above said behavior the computed numerical data for fluid velocity,temperature profile,and mass concentration for several constraints that is mixed convection parameterλt,modified mixed convection parameterλc,Prandtl number Pr,heat generation/absorption parameterδ,Schmidt number Sc,thermophoresis parameter Nt,and thermophoretic coefficient k are sketched in graphical form.Numerical results for skin friction,heat transfer rate and the mass transfer rate are tabulated for various emerging physical parameters.It is reported that in enhancement in heat,generation boosts up the fluid temperature at some positions of the surface of the sphere.As heat absorption parameter is decreased temperature field increases at position X=π/4 on the other hand,no alteration at other considered circumferential positions is noticed.展开更多
The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide （CO2）, which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex...The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide （CO2）, which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex- plore efficient and sustainable approaches for the carbon-neutral pathway of CO2 utilization and recycling. In our recent works with this context, we developed successfully a novel ＂chemical vapor deposition integrated process （CVD-IP）＂ technology to converting robustly CO2 into the value-added solid-form carbon materials, The monometallic FeNi0-Al2O3 （FNi0） and bimetallic FeNix-Al2O3 （FNi2, FNi4, FNi8 and FNi20） samples were synthesized and effective for this new approach. The catalyst labeled FNi8 gave the better performance, exhibited the single pass solid carbon yield of 30%. These results illustrated alternative promising cases for the CO2 capture utilization storage （CCUS）, by means of the CO2 catalytic conversion into the solid-form nano carbon materials.展开更多
The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technolo...The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technology for producing. The aim of this paper is the comparison properties of binders based on liquid glass containing strong organic bases silicates. We have shown how these systems are transformed from lower to higher oligomers through the formation of the silica sol and the implementation of the sol-gel process for these oligomers. We have conducted advanced research of various aspects of the use of these materials as the binder. Advantages of strong organic bases silicates in the preparation of heat resistant, nanocomposite materials are shown. Ways to obtaining quaternary ammonium silicates and their use to produce nanocomposites are proposed. Products obtained in this way can be used as a binder in the preparation of nanostruetured composite materials, water-based paints, coatings, etc. Modifiers have been proposed for making of hybrid nanostructured composite materials by a sol-gel process. There have been shown of structuring phenomena some aspects, synthesis and application of hybrid materials based on silica with grafted polymers. It has been shown, the possibility of modifying compositions using the nanostructuring agents such as tetrafurfuryloxysilane. This paper also describes methods for the synthesis of products for modifying a sol-gel process using organic soluble silicates. We are displaying their use for the production of new nanocomposite materials and coatings for protection against various external factors.展开更多
Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and me...Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.展开更多
The conducting polyaniline （PANI） prepared by three chemical oxidative polymerization pathways including microemulsion, emulsion and aqueous solution methods were studied and compared. Their structures, morphologies...The conducting polyaniline （PANI） prepared by three chemical oxidative polymerization pathways including microemulsion, emulsion and aqueous solution methods were studied and compared. Their structures, morphologies and properties were characterized using FT-IR, XRD, TEM and TGA. PANI particles formed in aqueous solution have a smallest size and doping HCl enables to increase their conductivity. In contrast, PANI particles prepared by emulsion method have the highest thermal stability and conductivity and more ordered morphology. Rather different from these two methods, microemulsion approach allows forming nanocomposite PANI with tube-like nanostructure.展开更多
Due to the widespread use of nanocarbon materials(NCMs),more researchers are studying their tribological performances.In this work,the tribological behaviors of the following five types of NCMs with different geometri...Due to the widespread use of nanocarbon materials(NCMs),more researchers are studying their tribological performances.In this work,the tribological behaviors of the following five types of NCMs with different geometric shapes were evaluated in a novel oil‐in‐water system:spherical fullerenes(C60,0D),tubular multi‐walled carbon nanotubes(MWCNT,1D),sheet graphene oxide(GO,2D),sheet graphene oxide derivative(Oct‐O‐GO,2D),and lamellar graphite(G,3D).Among these,GO with two types of oxidation degrees,i.e.,GO(1),GO(2),and Oct‐O‐GO(1)were synthesized and characterized using Fourier‐transform infrared spectroscopy,Raman spectroscopy,x‐ray diffraction,thermogravimetric analysis,scanning electron microscopy,and contact angle measurements.The load‐carrying capacity of the NCM emulsions were evaluated using a four‐ball test machine,and the lubrication performances were investigated using a high‐frequency reciprocating friction and wear tester with a sliding distance of 1,800 mm under different loads(50 N and 100 N)at 0.5 Hz.The results revealed that the Oct‐O‐GO(1)emulsion exhibited the best load‐carrying capacity,and the best friction‐reducing and anti‐wear properties compared to other emulsions.Moreover,the anti‐wear advantage was more prominent under high load conditions,whereas the other emulsions exhibited a certain degree of abrasive or adhesive wear.The lubrication mechanism was determined through the analysis of worn surfaces using scanning electron microscopy/energy‐dispersive x‐ray spectroscopy,micro‐Raman spectroscopy,and x‐ray photoelectron spectroscopy.The results revealed that during frictional sliding,the ingredients in the emulsion can absorb and react with the freshly exposed metal surface to form surface‐active films to protect the surfaces from abrasion.Moreover,it was found that the higher the amount of ingredients that contain alkyl and O‐H/C=O,the better was the lubrication performance in addition to an increase in the carbon residue in the tribofilm generated on the meal surface.展开更多
In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance in ordinary condition, iron nanoparticles synthesized by a chemical vapor condensation...In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance in ordinary condition, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in usual air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below 130℃ in air was 10-40 times higher than that of the normally passivated particles.展开更多
Three-dimensional(3 D)printing,also known as additive manufacturing,has the advantages of low cost,easy structure operation,rapid prototyping,and easy customization.In the past few years,materials with different struc...Three-dimensional(3 D)printing,also known as additive manufacturing,has the advantages of low cost,easy structure operation,rapid prototyping,and easy customization.In the past few years,materials with different structures,compositions,and properties have been widely studied as prospects in the field of 3 D printing.This paper reviews the synthesis methods and morphologies of one-,two-and threedimensional micro/nano materials and their composites,as well as their applications in electrochemistry,such as supercapacitors,batteries and electrocatalysis.The latest progress and breakthroughs in the synthesis and application of different structural materials in 3 D-printing materials,as well as the challenges and prospects of electrochemical applications,are discussed.展开更多
Nanocrystalline zirconium（IV） oxide （nc-ZrO2） possessing high surface area was synthesized by a low tem- perature eco-friendly solution combustion method using a new organic fuel alanine. The powder XRD, SEM and s...Nanocrystalline zirconium（IV） oxide （nc-ZrO2） possessing high surface area was synthesized by a low tem- perature eco-friendly solution combustion method using a new organic fuel alanine. The powder XRD, SEM and surface area measurements were carried out for characterization of nc-ZrO2. The powder XRD results revealed that, the nc-ZrO2 has the pure tetragonal phase. The crystallite size calculated by Scherrer＇s formula and BET surface area were found to be ca. 53--57 nm and ca. 275 m2/g, respectively. SEM micrograph exhibited the macroporous nature of the powder, nc-ZrO2 has been employed as a catalyst for the solvent-free synthesis of 3,4-dihydro- pyrimidin-2-ones （DHPMs） by a microwave （MW） assisted one-pot, multicomponent Biginelli condensation reaction of araldehydes, ethylacetoacetate and urea or thiourea. DHPMs are obtained in good to excellent yields （85%-- 96%） under this reaction condition within short interval of time （10--20 min）.展开更多
PrrOll nanoparticles were obtained by subsequent thermal decomposition of the as-prepared precipitate formed under ambient temperature and pressure using NaOH as precipitant. The calcination process was affected, for ...PrrOll nanoparticles were obtained by subsequent thermal decomposition of the as-prepared precipitate formed under ambient temperature and pressure using NaOH as precipitant. The calcination process was affected, for 1 h in static air atmosphere, at 400-700 ℃ temperature range. The different samples were characterized using X-ray diffraction （XRD）, transmission electron microscopy （TEM）, field emission scanning electron microscopy （FE-SEM）, thermogravimetric analysis （TGA）, in situ electrical conductivity, and N2 adsorption/desorption. The obtained results demonstrated that nano-crystalline Pr6O11, with crystallites size of 6-12 nm, started to form at 500 ℃. Such value increased to 20-33 nm for the sample calcined at 700℃. The as-synthesized PrrOll nanoparticles presented high electrical conductivity due to electron hopping between Pr（III）-Pr（IV） pairs.展开更多
1 Results On the basis of previous work,the general theory,least square methods and computing programs have been proposed and developed,which can separate the two-fold broadening effect caused by crystallite-micro str...1 Results On the basis of previous work,the general theory,least square methods and computing programs have been proposed and developed,which can separate the two-fold broadening effect caused by crystallite-micro strain,crystallite-stacking faults,strain-faults and which can also separate the three fold broadening effect caused by crystallite-strain-faults in closed-parked hexagonal (CPH) nano-materials.The method is applied to characterize and investigate the microstructure in β-Ni(OH)2 as negative ma...展开更多
文摘The nanotechnology is of great siguifieance to the country＇s future economic, social development and national security, and it will bring a revolutionary change to the medicine, manufacturing, materials and information communication and other industries, therefore, in recent years, nano science and technology is greatly favored all over the world especially in developed countries. All the countries （areas） in the world have developed the nanotechnology as the main driver of the technical innovation in the twenty-first century, and have formulated development strategies and plans, to promote and guide their development in nanotechnology, which lead to fiercer and fiercer competition. In this paper, the author mainly introduces the application of nano materials in catalysis, filtration, separation, paint and new fine chemical industry and so on.
基金the Natural Science Foundation of Zhejiang Province,No.LQ21H030005
文摘Partial hepatectomy(PH)can lead to severe complications,including liver failure,due to the low regenerative capacity of the remaining liver,especially after extensive hepatectomy.Liver sinusoidal endothelial cells(LSECs),whose proliferation occurs more slowly and later than hepatocytes after PH,compose the lining of the hepatic sinusoids,which are the smallest blood vessels in the liver.Vascular endothelial growth factor(VEGF),secreted by hepatocytes,promotes LSEC proliferation.Supplementation of exogenous VEGF after hepatectomy also increases the number of LSECs in the remaining liver,thus promoting the reestablishment of the hepatic sinusoids and accelerating liver regeneration.At present,some shortcomings exist in the methods of supplementing exogenous VEGF,such as a low drug concentration in the liver and the reaching of other organs.Moreover,VEGF should be administered multiple times and in large doses because of its short half-life.This review summarized the most recent findings on liver regeneration and new strategies for the localized delivery VEGF in the liver.
基金This work is financially supported by a University-Level Doctoral Research Start-Up Fund in 2019.
文摘A triethylenetetramine epoxy mixture was synthesized through the reaction of a low-molecular-weight liquid epoxy resin with triethylenetetramine(TETA).Then triethyltetramine(TETA)was injected dropwise into a pro-pylene glycol methyl ether(PM)solution for chain extension reaction.A hydrophilic andflexible polyether seg-ment was introduced into the hardener molecule.The effects of TETA/DGEPG,reaction temperature and reaction time on the epoxy conversion of polyethylene glycol diglycidyl ether(DGEPG)were studied.In addition,several alternate strategies to add epoxy resin to the high-speed dispersion machine and synthesize MEA DGEBA adduct(without catalyst and with bisphenol A diglycidyl ether epoxy resin)were compared.It was found that the higher the molecular weight of triethylenetetramine,the longer the chain segment of the surface active molecule.When the equivalence ratio of amine hydrogen and epoxy group is low,the stability of lotion is good.When the ratio of amine hydrogen to epoxy group is large,the content of triethylenetetramine is small.The main objective of this study is the provision of new data and knowledge for the development of new materials in the coating and electronic industry.
基金Supported by National Natural Science Foundation(No.0 5 1730 0 3) Beijing Science and Technology New Star Program(No.H0 10 4 10 0 10 112 ) and Im portant Natural Science Foundation of Beijing(No.2 0 310 0 1) .
文摘The polymerization of amphiphilic self assemblies is a promising method to synthesize nano structured materials with novel properties. These materials have many attractive features for their application in biomedical area and materials science, such as catalysis, separation, surface modification, and therapeutics areas. A general review on the polymerization of lipids and surfactant self assemblies to amphiphilic self assemblies is given in this paper with 49 references. The polymerization and the subsequently resulted structure of lipids in different morphologies are summarized. The polymerization of polymerizable surfactants(surfmers) in emulsion and liquid crystalline phases are also discussed. The potential application of new nano porous materials is briefly described.
文摘Several nano material and reaction systems were in situ monitored with an electrochemical TEM wet cell set up. In a 1 g/L sliver particle aqueous solution, the particles were observed to be ca. 10 nm sized, in both discrete particle and nano cluster forms. The silver particles were attached to the 50 nm-thick Si3N4 windows of the wet cell and could not move freely in the liquid. With a SIC14 liquid loaded in the wet cell, silicon nano materials were controllably grown on the wet cell windows by means of a liquid phase electron beam induced deposition （EBID） method. The deposited nano dots were nicely round-shaped, and demonstrated a power law growth dependency on beam exposure time in a log-log plot. In a NiCI2 solution/Ni system, both electrochemical deposition and dissolution of the nickel nano films were observed while applying electric biases on to the nickel electrodes in the wet cell. Instead of extensional growth on existing crystals, interestingly, it is more commonly observed that new nickel nano particles grow out in front of the existing film first and then merged into the film. The wet cell set up is demonstrated to be a versatile tool for nano liquid system research.
基金financial funding from the Egyptian governmentthe financial funding from the NSERC Discovery grant。
文摘Combustion within small motors is key in the application-specific development of nanothermite-based micro-energetic systems. This study evaluates the performance of nanothermite mixtures in a converging-diverging nozzle and an open tube. Mixtures were prepared using nano-aluminum(n-Al),potassium perchlorate(KClO_(4)), and different carbon nanomaterials(CNMs) including graphene-oxide(GO), reduced GO, carbon nanotubes(CNTs) and nanofibers(CNFs). The mixtures were packed at different densities and ignited by laser beam. Performance was measured using thrust measurement,high-speed imaging, and computational fluid dynamics modeling, respectively. Thrust, specific impulse(ISP), volumetric impulse(ISV), as well as normalized energy were found to increase notably with CNM content. Two distinctive reaction regimes(fast and slow) were observed in combustion of low and high packing densities(20% and 55%TMD), respectively. Total impulse(IFT) and ISPwere maximized in the 5%GO/Al/KClO_4 mixture, producing 7.95 m N·s and 135.20 s respectively at 20%TMD, an improvement of 57%compared to a GO-free sample(5.05 m N·s and 85.88 s). CFD analysis of the motors over predicts the thrust generated but trends in nozzle layout and packing density agree with those observed experimentally;peak force was maximized by reducing packing density and using an open tube. The numerical force profiles fit better for the nozzle cases than the open tube scenarios due to the rapid nature of combustion. This study reveals the potential of GO in improving oxygenated salt-based nanothermites,and further demonstrates their applicability for micro-propulsion and micro-energetic applications.
文摘Alternating current（AC） conductivity and dielectric properties of thermally evaporated Au/Pt OEP/Au thin films are investigated each as a function of temperature（303 K–473 K） and frequency（50 Hz–5 MHz）.The frequency dependence of AC conductivity follows the Jonscher universal dynamic law.The AC-activation energies are determined at different frequencies.It is found that the correlated barrier hopping（CBH） model is the dominant conduction mechanism.The variation of the frequency exponent s with temperature is analyzed in terms of the CBH model.Coulombic barrier height Wm,hopping distance Rω,and the density of localized states N（EF） are valued at different frequencies.Dielectric constant ε1（ω,T） and dielectric loss ε2（ω,T） are discussed in terms of the dielectric polarization process.The dielectric modulus shows the non-Debye relaxation in the material.The extracted relaxation time by using the imaginary part of modulus（M’’）is found to follow the Arrhenius law.
基金supported by Key Research Program of Frontier Sciences of CAS(No.QYKJZD-SSW-SLH02).
文摘With the advent of tissue engineering and biomedicine,the creation of extracellular matrix(ECM)biomaterials for in vitro applications has become a prominent and promising strategy.These ECM materials provide physical,biochemical,and mechanical properties that guide cellular behaviors,such as proliferation,differentiation,migration,and apoptosis.Because micro-and nano-patterned materials have a unique surface topology and low energy replication process that directly affect cellular biological behaviors at the interface,the fabrication of micro-nano pattern biomaterials and the regulation of surface physical and chemical properties are of great significance in the fields of cell regulation,tissue engineering,and regenerative medicine.Herein,we provide a comprehensive review of the progress in the fabrication and application of patterned materials based on the coupling of mechanical action at the micro-and nano-meter scale,including photolithography,micro-contact printing,electron beam lithography,electrospinning,and 3D printing technology.Furthermore,a summary of the fabrication process,underlying principles,as well as the advantages and disadvantages of various technologies are reviewed.We also discuss the influence of material properties on the fabrication of micro-and nano-patterns.
基金supported by National Natural Science Foundation(No.11075121)the International Science and Technology Cooperation Program(No.2010DFA02010)Three Gorges University of China(KJ2009B011)
文摘We have developed a computerized system for measuring field electron emission （FE） and field ionization （FI）, which has a three-electrode configuration with emitters biased up to 25 kV, and is programmed by the Labview software. The current-voltage curves of nano-tip tungsten and carbon nanotube （CNT） arrays were measured. The electron emission of CNTs proceeded with a turn-on field of 1.24 V/μm and a threshold field of 1.85 V/μm. Compared to the field emission, field ionization turned on at 3.5 V/μm. Raman spectroscopy and scanning electron microscopy （SEM） measurements showed degradation of the CNTs after FE/FI testing. The measurement of a W-tip revealed strong electron emission and instability behavior at a field strength higher than 7.0 V/μm.
基金The authors would like to acknowledge Natural Science Foundation of China(Grant Nos.61673169,11701176,11626101,11601485).
文摘The present study is concerned with the physical behavior of the combined effect of nano particle material motion and heat generation/absorption due to the effect of different parameters involved in prescribed flow model.The formulation of the flow model is based on basic universal equations of conservation of momentum,energy and mass.The prescribed flow model is converted to non-dimensional form by using suitable scaling.The obtained transformed equations are solved numerically by using finite difference scheme.For the analysis of above said behavior the computed numerical data for fluid velocity,temperature profile,and mass concentration for several constraints that is mixed convection parameterλt,modified mixed convection parameterλc,Prandtl number Pr,heat generation/absorption parameterδ,Schmidt number Sc,thermophoresis parameter Nt,and thermophoretic coefficient k are sketched in graphical form.Numerical results for skin friction,heat transfer rate and the mass transfer rate are tabulated for various emerging physical parameters.It is reported that in enhancement in heat,generation boosts up the fluid temperature at some positions of the surface of the sphere.As heat absorption parameter is decreased temperature field increases at position X=π/4 on the other hand,no alteration at other considered circumferential positions is noticed.
基金support for this project from the National Natural Science Foundation of China (21476145)the National 973 Program of Ministry of Sciences and Technologies of China (2011CB201202)
文摘The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide （CO2）, which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex- plore efficient and sustainable approaches for the carbon-neutral pathway of CO2 utilization and recycling. In our recent works with this context, we developed successfully a novel ＂chemical vapor deposition integrated process （CVD-IP）＂ technology to converting robustly CO2 into the value-added solid-form carbon materials, The monometallic FeNi0-Al2O3 （FNi0） and bimetallic FeNix-Al2O3 （FNi2, FNi4, FNi8 and FNi20） samples were synthesized and effective for this new approach. The catalyst labeled FNi8 gave the better performance, exhibited the single pass solid carbon yield of 30%. These results illustrated alternative promising cases for the CO2 capture utilization storage （CCUS）, by means of the CO2 catalytic conversion into the solid-form nano carbon materials.
文摘The work describes the properties of soluble organic silicates and their applications to obtain nanocomposite materials. We analyzed the properties of the water-soluble high-modulus silicate systems and their technology for producing. The aim of this paper is the comparison properties of binders based on liquid glass containing strong organic bases silicates. We have shown how these systems are transformed from lower to higher oligomers through the formation of the silica sol and the implementation of the sol-gel process for these oligomers. We have conducted advanced research of various aspects of the use of these materials as the binder. Advantages of strong organic bases silicates in the preparation of heat resistant, nanocomposite materials are shown. Ways to obtaining quaternary ammonium silicates and their use to produce nanocomposites are proposed. Products obtained in this way can be used as a binder in the preparation of nanostruetured composite materials, water-based paints, coatings, etc. Modifiers have been proposed for making of hybrid nanostructured composite materials by a sol-gel process. There have been shown of structuring phenomena some aspects, synthesis and application of hybrid materials based on silica with grafted polymers. It has been shown, the possibility of modifying compositions using the nanostructuring agents such as tetrafurfuryloxysilane. This paper also describes methods for the synthesis of products for modifying a sol-gel process using organic soluble silicates. We are displaying their use for the production of new nanocomposite materials and coatings for protection against various external factors.
基金supported by the Joint Research Program of Hunan Provincial Natural Science Foundation(Xiangtan)of China(2016JJ5030)Hunan 2011 Collaborative Innovation Center of Chemical Engineering&Technology with Environmental Benignity and Effective Resource Utilization and General project of Hunan Provincial Education Department(17C1526)+1 种基金PhD Startup Foundation of Xiangtan University(17QDZ05)Xiangtan University undergraduate innovative experiment program(2017XJ067)~~
文摘Sepiolite@LDH(Sep@LDH)composites were designed and prepared based on the assembly of layered double hydroxides(LDH)on acidified sepiolites(Sep)for the simultaneous photocatalytic degradation of methyl orange(MO)and methylene blue(MB).The structure,morphology,texture,optical properties,and photocatalytic performance of the prepared Sep@LDH were studied in detail.Among the Sep@LDH composites,Sep4@LDH(4.0 g Sep)exhibited the highest photocatalytic activity under visible‐light irradiation,which could be attributed to its large surface area,high crystallinity,and plentiful active sites on its surface.The photodegradation of the dyes followed a pseudo first‐order kinetic model(Langmuir‐Hinshelwood model),indicating that the copious and homogeneous active sites on the surface of the composites contributed to the high photocatalytic activity.The photodegradation mechanism was studied by examining the active species(^-OH,h+,and·O2^-anions)using appropriate scavengers.It was found that·OH radicals played a critical role in the photocatalytic process of MO and MB,where the generation of·OH radicals occurred on the electron/hole(e^-/h+)pairs on the surface of the Sep@LDH composites.
基金Funded by the National Natural Science Foundation of China ( No. 50771020)
文摘The conducting polyaniline （PANI） prepared by three chemical oxidative polymerization pathways including microemulsion, emulsion and aqueous solution methods were studied and compared. Their structures, morphologies and properties were characterized using FT-IR, XRD, TEM and TGA. PANI particles formed in aqueous solution have a smallest size and doping HCl enables to increase their conductivity. In contrast, PANI particles prepared by emulsion method have the highest thermal stability and conductivity and more ordered morphology. Rather different from these two methods, microemulsion approach allows forming nanocomposite PANI with tube-like nanostructure.
基金the National Natural Science Foundation of China(Nos.21703279,and21506064)Shanghai Natural Science Foundation(No.17ZR1442100)the Shanghai Municipal “Science and Technology Innovation Action Plan” International Cooperation Project(No.15540723600)for financial support
文摘Due to the widespread use of nanocarbon materials(NCMs),more researchers are studying their tribological performances.In this work,the tribological behaviors of the following five types of NCMs with different geometric shapes were evaluated in a novel oil‐in‐water system:spherical fullerenes(C60,0D),tubular multi‐walled carbon nanotubes(MWCNT,1D),sheet graphene oxide(GO,2D),sheet graphene oxide derivative(Oct‐O‐GO,2D),and lamellar graphite(G,3D).Among these,GO with two types of oxidation degrees,i.e.,GO(1),GO(2),and Oct‐O‐GO(1)were synthesized and characterized using Fourier‐transform infrared spectroscopy,Raman spectroscopy,x‐ray diffraction,thermogravimetric analysis,scanning electron microscopy,and contact angle measurements.The load‐carrying capacity of the NCM emulsions were evaluated using a four‐ball test machine,and the lubrication performances were investigated using a high‐frequency reciprocating friction and wear tester with a sliding distance of 1,800 mm under different loads(50 N and 100 N)at 0.5 Hz.The results revealed that the Oct‐O‐GO(1)emulsion exhibited the best load‐carrying capacity,and the best friction‐reducing and anti‐wear properties compared to other emulsions.Moreover,the anti‐wear advantage was more prominent under high load conditions,whereas the other emulsions exhibited a certain degree of abrasive or adhesive wear.The lubrication mechanism was determined through the analysis of worn surfaces using scanning electron microscopy/energy‐dispersive x‐ray spectroscopy,micro‐Raman spectroscopy,and x‐ray photoelectron spectroscopy.The results revealed that during frictional sliding,the ingredients in the emulsion can absorb and react with the freshly exposed metal surface to form surface‐active films to protect the surfaces from abrasion.Moreover,it was found that the higher the amount of ingredients that contain alkyl and O‐H/C=O,the better was the lubrication performance in addition to an increase in the carbon residue in the tribofilm generated on the meal surface.
基金supported by a grant-in-aid for the National Core Research Center Program from the Ministry of Science & Technology and the Korea Science & Engineering Foundation (R15-2006-022-03001-0)
文摘In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance in ordinary condition, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in usual air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below 130℃ in air was 10-40 times higher than that of the normally passivated particles.
基金supported by the National Natural Science Foundation of China(No.U1904215)Natural Science Foundation of Jiangsu Province(No.BK20200044)Changjiang Scholars Program of the Ministry of Education(No.Q2018270)。
文摘Three-dimensional(3 D)printing,also known as additive manufacturing,has the advantages of low cost,easy structure operation,rapid prototyping,and easy customization.In the past few years,materials with different structures,compositions,and properties have been widely studied as prospects in the field of 3 D printing.This paper reviews the synthesis methods and morphologies of one-,two-and threedimensional micro/nano materials and their composites,as well as their applications in electrochemistry,such as supercapacitors,batteries and electrocatalysis.The latest progress and breakthroughs in the synthesis and application of different structural materials in 3 D-printing materials,as well as the challenges and prospects of electrochemical applications,are discussed.
文摘Nanocrystalline zirconium（IV） oxide （nc-ZrO2） possessing high surface area was synthesized by a low tem- perature eco-friendly solution combustion method using a new organic fuel alanine. The powder XRD, SEM and surface area measurements were carried out for characterization of nc-ZrO2. The powder XRD results revealed that, the nc-ZrO2 has the pure tetragonal phase. The crystallite size calculated by Scherrer＇s formula and BET surface area were found to be ca. 53--57 nm and ca. 275 m2/g, respectively. SEM micrograph exhibited the macroporous nature of the powder, nc-ZrO2 has been employed as a catalyst for the solvent-free synthesis of 3,4-dihydro- pyrimidin-2-ones （DHPMs） by a microwave （MW） assisted one-pot, multicomponent Biginelli condensation reaction of araldehydes, ethylacetoacetate and urea or thiourea. DHPMs are obtained in good to excellent yields （85%-- 96%） under this reaction condition within short interval of time （10--20 min）.
文摘PrrOll nanoparticles were obtained by subsequent thermal decomposition of the as-prepared precipitate formed under ambient temperature and pressure using NaOH as precipitant. The calcination process was affected, for 1 h in static air atmosphere, at 400-700 ℃ temperature range. The different samples were characterized using X-ray diffraction （XRD）, transmission electron microscopy （TEM）, field emission scanning electron microscopy （FE-SEM）, thermogravimetric analysis （TGA）, in situ electrical conductivity, and N2 adsorption/desorption. The obtained results demonstrated that nano-crystalline Pr6O11, with crystallites size of 6-12 nm, started to form at 500 ℃. Such value increased to 20-33 nm for the sample calcined at 700℃. The as-synthesized PrrOll nanoparticles presented high electrical conductivity due to electron hopping between Pr（III）-Pr（IV） pairs.
文摘1 Results On the basis of previous work,the general theory,least square methods and computing programs have been proposed and developed,which can separate the two-fold broadening effect caused by crystallite-micro strain,crystallite-stacking faults,strain-faults and which can also separate the three fold broadening effect caused by crystallite-strain-faults in closed-parked hexagonal (CPH) nano-materials.The method is applied to characterize and investigate the microstructure in β-Ni(OH)2 as negative ma...
