Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different exp...Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients,making the particles easier to be removed.Laser plasma can ionize and even vaporize particles more significantly than an incident laser and,therefore,it can remove the particles more efficiently.The laser plasma shock wave plays a dominant role in removing particles,which is attributed to its strong burst force.The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface.In order to obtain the working conditions for particle removal,the removal mechanism,as well as the temporal and spatial characteristics of velocity,propagation distance and pressure of shock wave have been researched.On the basis of our results,the conditions for nano-particle removal are achieved.展开更多
Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles(NPs)directly exposed to infants and young children.However,the impact of steam disinfection on release of NPs an...Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles(NPs)directly exposed to infants and young children.However,the impact of steam disinfection on release of NPs and the related potential risks to children's health are unknown.Here,we investigated contents and form of Ag and Zn in 57 nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers of seven countries and examined the impacts of steam disinfection on in vitro bioaccessibility(IVBA)of Ag and Zn in the articles.Nearly 89%articles had a mixture of Ag-and Zn-containing NPs and the teethers had relatively high Ag and Zn contents(up to 501 and 254μg/g,respectively).Steam disinfection caused rubber decomposition into micro(nano)plastics(0.54-15.7μm)and NP release from the interior of bulk rubber and micro-sized plastics,thus enhancing the IVBA of Ag and Zn by up to 5.5 times.The findings provide insights into mechanisms for NP release by steam disinfection.Though oral exposure risk assessment suggested low health concerns on individual metal release,our study points out the need to assess the potential health risks of child co-exposure to metallic NPs and micro(nano)plastics.展开更多
In this study, the performance of stable nanofluid containing SiO2 nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this ...In this study, the performance of stable nanofluid containing SiO2 nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this work, the stability of silica nanoparticles in different range of water salinity(0–100000 mg·L-1) is investigated. Next, stable nanofluid containing highest salinity is selected as asphaltene inhibitor agent to inject into the damaged core sample. The estimated values of oil recovery for base case, after damage process and after inhibition of asphaltene precipitation using nanofluid are 51.6%, 36.1% and 46.7%, respectively. The results showed the reduction in core damage after using nanofluid. In addition, the relative permeability curves are plotted for the base case, after damage process and also after inhibition of asphaltene precipitation using nanofluid. Comparison of relative permeability curves shows, relative permeability of oil phase decreased after damage process as compared with the base case. But after using nanofluid the oil relative permeability curve has shifted to the right and effective permeability of oil phase has been improved.展开更多
Nano silicon particles can be become nano fibre under low energy electron beam bombarding. The formation of the nano silicon fibre include two stages. At first, on the nano silicon particle surface many silicon atoms ...Nano silicon particles can be become nano fibre under low energy electron beam bombarding. The formation of the nano silicon fibre include two stages. At first, on the nano silicon particle surface many silicon atoms are gasified, then these silicon atoms deposit in the place where have more charge on account of the static electrical absorption and the point effect of the charge accumulation , these atoms grow into non crystalline silicon fibres. The second stage is the non crystalline silicon fibres crystallizing. Its crystallizing temperature is about 180℃. The growth mechanism of the nano silicon fibre is vapour solid mode.展开更多
The following article has been retracted due to the fact that it cannot be accepted by the author as a journal publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. Th...The following article has been retracted due to the fact that it cannot be accepted by the author as a journal publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. This paper published in Journal of Biosciences and Medicines Vol.2 No.2, April 2014, has been removed from this site.展开更多
As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to ...As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles(nanobubbles and microbubbles) on the flotation of fine( 38 + 14.36 lm) and ultrafine( 14.36 + 5 lm) chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nanomicrobubble generator based on the cavitation phenomenon in Venturi tubes. In order to better understand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nanobubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16–21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles( 14.36 + 5 lm) more than that of fine particles( 38 + 14.36 lm). Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%,respectively.展开更多
The influence of nano-particles on CO2absorption was studied experimentally in a stirred thermostatic reactor.Nano-Al2O3and carbon nanotube(CNT) particles which showed different hydrophobic properties were chosen for ...The influence of nano-particles on CO2absorption was studied experimentally in a stirred thermostatic reactor.Nano-Al2O3and carbon nanotube(CNT) particles which showed different hydrophobic properties were chosen for the investigation.The experimental results were compared with that of micron-size activated carbon(AC)and Al2O3particles.From the results,no enhancement by micron-size Al2O3was found,and with the increase of Al2O3concentration,the enhancement factor decreased.However,nano-Al2O3showed a weak enhancement for the CO2absorption.AC and CNT particles all intensified the gas-liquid mass transfer effectively,yet the trend of the enhancement factor with stirring speed for the two particles was different.With increasing stirring speed,the enhancement factor of AC particles was decreased,whereas in CNT suspensions it was increased.The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles.For nano-particles,besides the influence of adsorbability and hydrophobicity,the micro-convection caused by Brownian motion should be also taken into account.Considering the micro-convection effect,a theoretical model was developed to shed light on the absorption enhancement by nano-particles.展开更多
Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter...Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter were investigated. The particle sizes of the as obtained samples were found to be ~10 nm which increases upto ~92 nm on annealing at 1000oC. The frequency bands near 564-588 cm-1 and 425-442 cm-1 are assigned to the tetrahedral and octahedral clusters which confirm the presence of M-O stretching band in ferrites. The unit cell parameter ‘a’ increases linearly with increasing concentration of zinc due to larger ionic radii of Zn2+ ion . It was found that this substitution allows tunable changes in the magnetic properties of cobalt ferrite. Interestingly, saturation magnetization first increases upto x = 0.4 and then decreases for higher Zn substitution, thus tunable changes in magnetic properties of cobalt ferrite are possible. Source of such behaviour could be the variation of exchange interaction between the tetrahedral and the octahedral sites.展开更多
Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its appli...Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC). Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition (1%, mass fraction) were prepared by the laser cladding technique on Ni-based superalloy substrates, aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings (the bond coat of the duplex structure thermal barrier coatings). Scanning electron microscope (SEM), X-ray diffractometer(XRD) and thermogravimetry were employed to investigate their morphologies, phases and cyclic oxidation behaviors in atmosphere at 1 050℃, compared with the coating without nano-particles. With the addition of nano-particles, the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth; slender dendrites were broken and cellularized; cracks and pores were restrained; and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well. Among the three kinds of nano-particles, the SiC nano-particles showed the most improvement on microstructure, while the CeO2 nano-particles were insufficient, but its effects on the oxidation resistance are the same as those of the SiC nano-particles. Based on the discussions of the influence mechanism, it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted, with the synergistic action of nanometer effect and reactive element effect.展开更多
A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamin...A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.展开更多
Poly(St-co-BuA)/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-(trimethoxysilyl)propyl methacrylate modified colloidal nano-silica. The effects of surface p...Poly(St-co-BuA)/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-(trimethoxysilyl)propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope (TEM) and scanning electron microscope (SEM) in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.展开更多
To understand the deformation and removal mechanism of material on nano-scale at ultralow loads,a systemic study on AFM micro/nano-machining on single crystal ailicon is conducted. The results indicate that AFM nano- ...To understand the deformation and removal mechanism of material on nano-scale at ultralow loads,a systemic study on AFM micro/nano-machining on single crystal ailicon is conducted. The results indicate that AFM nano- machining has a precisely dimensional controllability and a good surface quality on nanometer scale.A SEM is adopted to observe nano-machined region and chips,the results indicate that the material removal mechanisms change with the applied normal load. An XPS is used to analyze the changes of chemical composition inside and outside the nano-machined region respectively.The nano-indentation which is conducted with the same AFM diamond tip on the machined region shows a big discrepancy compared with that on the macro-scale. The calculated results show higher nano-hardness and elastic modulus than normal values .This phenomenon on be regarded as the indentation size effect(ISE).展开更多
Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on...Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.展开更多
In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by f...In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by flow coat method on the surface of industrially pure titanium TB1-0. The effects of nano-size nickel particles on the wear resistance and high temperature oxidation resistance of coating substrate system were investigated through oxidation kinetics experiment and wear resistance test. The morphologies of the specimens were examined by means of optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the high temperature ultra fine ceramic coating has notable protection effect on industrially pure titanium TB1-0 from oxidation. The oxidation and wear resistance properties of the coating can be effectively improved by adding nano-size nickel particles. The oxidative mass gain of the specimen decreases from 11.33 mg·cm-2 to 5.25 mg·cm-2 and the friction coefficient decreases from 1.1 to 0.6 by adding nano-size nickel particles, and the coating containing 10% （mass fraction） nano-size nickel shows the optimum properties.展开更多
In order to synthesize the targeting drug carrier system,magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil(5-Fu)as model drug,Fe3O4 nano-particles as kernel,chitosan as enveloping m...In order to synthesize the targeting drug carrier system,magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil(5-Fu)as model drug,Fe3O4 nano-particles as kernel,chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique.The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM).The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm.The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis.The results showed that the loading capacity was 13.4%and the cumulative release percentage in the phosphate buffer(pH=7.2)solutions was 68%in 30 h.These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released.The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance.Without external magnetic field,the nano-particle deposition rate was slow.When being subjected to 8 mT magnetic field,the particle sedimentation rate was increased rapidly.The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.展开更多
Si3N4-Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering （LPS）. The Si2N2O phase was generated by an in-situ reaction 2Si3N4（s）+ 1.5 O2（g）=3Si2N2O（...Si3N4-Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering （LPS）. The Si2N2O phase was generated by an in-situ reaction 2Si3N4（s）+ 1.5 O2（g）=3Si2N2O（s）+N2（g）. The content of Si2N2O phase up to 60% in the volume was obtained at a sintering temperature of 1 650 ℃ and reduced when the sintering temperature increased or decreased, indicating the reaction is reversible. The mass loss, relative density and average grain size increased with increasing the sintering temperature. The average grain size was less than 500 nm when the sintering temperature was below 1 700 ℃. The sintering procedure contains a complex crystallization and a phase transition: amorphous silicon nitride→equiaxial α-Si3N4→equiaxial β-Si3N4→rod-like Si2N2O→needle-like β-Si3N4. Small round-shaped β-Si3N4 particles were entrapped in the Si2N2O grains and a high density of staking faults was situated in the middle of Si2N2O grains at a sintering temperature of 1 650 ℃. The toughness increased from 3.5 MPa·m 1/2 at 1 600 ℃ to 7.2 MPa·m 1/2 at 1 800 ℃. The hardness was as high as 21.5 GPa （Vickers） at 1 600 ℃.展开更多
Many researchers in academia and industries are interested in reducing particle sizes from few submicrometers to nano-meter levels.These nano-particles find application in several areas including ceramics,paints,cosme...Many researchers in academia and industries are interested in reducing particle sizes from few submicrometers to nano-meter levels.These nano-particles find application in several areas including ceramics,paints,cosmetics,microelectronics,sensors,textiles and biomedical,etc.This article reviews the present state of the art for solid state synthesis of mineral nano-particles by wet milling,including their operating variables such as ball size,solid mass fraction and suspension stability.This article concludes and recommends with a critical discussion of nano-particles synthesis and a few common strategies to overcome stability issues.展开更多
Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modi...Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modification mechanism and the bonding status on the surface of nano silicon dioxide after modification were suggested via the results of the infrared spectrum, transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formed by hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxide to form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto the surface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer through free radical polymerization between the double bonds on the surface of nano silicon dioxide and styrene under the action of initiating agent. The dispersibility of nano silicon dioxide and the controllability of surface modification of nano silicon dioxide can be greatly improved by the modification process.展开更多
In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, ...In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process.展开更多
Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images i...Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn_(0.6)Fe_(0.4)PO_4(S2)was about 80 nm in diameter.The discharge capacity of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn_(0.6)Fe_(0.4)PO_4 and it in situ reduction of GO could improve the electrical conductivity of LiMn_(0.6)Fe_(0.4)PO_4 material.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11574221)
文摘Particles can be removed from a silicon surface by means of irradiation and a laser plasma shock wave.The particles and silicon are heated by the irradiation and they will expand differently due to their different expansion coefficients,making the particles easier to be removed.Laser plasma can ionize and even vaporize particles more significantly than an incident laser and,therefore,it can remove the particles more efficiently.The laser plasma shock wave plays a dominant role in removing particles,which is attributed to its strong burst force.The pressure of the laser plasma shock wave is determined by the laser pulse energy and the gap between the focus of laser and substrate surface.In order to obtain the working conditions for particle removal,the removal mechanism,as well as the temporal and spatial characteristics of velocity,propagation distance and pressure of shock wave have been researched.On the basis of our results,the conditions for nano-particle removal are achieved.
基金supported by the Key-Area Research and Development Program of Guangdong Province (No.2020B1111380003)the National Natural Science Foundation of China (Nos.42177377 and 31861133003)。
文摘Nano-enabled silicone-rubber articles for feeding or chewing could be a source of metallic nanoparticles(NPs)directly exposed to infants and young children.However,the impact of steam disinfection on release of NPs and the related potential risks to children's health are unknown.Here,we investigated contents and form of Ag and Zn in 57 nano-enabled silicone-rubber baby bottle teats,pacifiers,and teethers of seven countries and examined the impacts of steam disinfection on in vitro bioaccessibility(IVBA)of Ag and Zn in the articles.Nearly 89%articles had a mixture of Ag-and Zn-containing NPs and the teethers had relatively high Ag and Zn contents(up to 501 and 254μg/g,respectively).Steam disinfection caused rubber decomposition into micro(nano)plastics(0.54-15.7μm)and NP release from the interior of bulk rubber and micro-sized plastics,thus enhancing the IVBA of Ag and Zn by up to 5.5 times.The findings provide insights into mechanisms for NP release by steam disinfection.Though oral exposure risk assessment suggested low health concerns on individual metal release,our study points out the need to assess the potential health risks of child co-exposure to metallic NPs and micro(nano)plastics.
基金the support of the Department of Petroleum Engineering, Amirkabir University of Technology during this study
文摘In this study, the performance of stable nanofluid containing SiO2 nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this work, the stability of silica nanoparticles in different range of water salinity(0–100000 mg·L-1) is investigated. Next, stable nanofluid containing highest salinity is selected as asphaltene inhibitor agent to inject into the damaged core sample. The estimated values of oil recovery for base case, after damage process and after inhibition of asphaltene precipitation using nanofluid are 51.6%, 36.1% and 46.7%, respectively. The results showed the reduction in core damage after using nanofluid. In addition, the relative permeability curves are plotted for the base case, after damage process and also after inhibition of asphaltene precipitation using nanofluid. Comparison of relative permeability curves shows, relative permeability of oil phase decreased after damage process as compared with the base case. But after using nanofluid the oil relative permeability curve has shifted to the right and effective permeability of oil phase has been improved.
文摘Nano silicon particles can be become nano fibre under low energy electron beam bombarding. The formation of the nano silicon fibre include two stages. At first, on the nano silicon particle surface many silicon atoms are gasified, then these silicon atoms deposit in the place where have more charge on account of the static electrical absorption and the point effect of the charge accumulation , these atoms grow into non crystalline silicon fibres. The second stage is the non crystalline silicon fibres crystallizing. Its crystallizing temperature is about 180℃. The growth mechanism of the nano silicon fibre is vapour solid mode.
文摘The following article has been retracted due to the fact that it cannot be accepted by the author as a journal publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. This paper published in Journal of Biosciences and Medicines Vol.2 No.2, April 2014, has been removed from this site.
基金the Tarbiat Modares University (TMU), the Iran Mineral Processing Research Center (IMPRC) and the IMIDRO for the technical assistance and financial support
文摘As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles(nanobubbles and microbubbles) on the flotation of fine( 38 + 14.36 lm) and ultrafine( 14.36 + 5 lm) chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nanomicrobubble generator based on the cavitation phenomenon in Venturi tubes. In order to better understand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nanobubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16–21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles( 14.36 + 5 lm) more than that of fine particles( 38 + 14.36 lm). Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%,respectively.
文摘The influence of nano-particles on CO2absorption was studied experimentally in a stirred thermostatic reactor.Nano-Al2O3and carbon nanotube(CNT) particles which showed different hydrophobic properties were chosen for the investigation.The experimental results were compared with that of micron-size activated carbon(AC)and Al2O3particles.From the results,no enhancement by micron-size Al2O3was found,and with the increase of Al2O3concentration,the enhancement factor decreased.However,nano-Al2O3showed a weak enhancement for the CO2absorption.AC and CNT particles all intensified the gas-liquid mass transfer effectively,yet the trend of the enhancement factor with stirring speed for the two particles was different.With increasing stirring speed,the enhancement factor of AC particles was decreased,whereas in CNT suspensions it was increased.The experimental phenomena demonstrated a difference in enhancement mechanism for different size particles.For nano-particles,besides the influence of adsorbability and hydrophobicity,the micro-convection caused by Brownian motion should be also taken into account.Considering the micro-convection effect,a theoretical model was developed to shed light on the absorption enhancement by nano-particles.
文摘Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter were investigated. The particle sizes of the as obtained samples were found to be ~10 nm which increases upto ~92 nm on annealing at 1000oC. The frequency bands near 564-588 cm-1 and 425-442 cm-1 are assigned to the tetrahedral and octahedral clusters which confirm the presence of M-O stretching band in ferrites. The unit cell parameter ‘a’ increases linearly with increasing concentration of zinc due to larger ionic radii of Zn2+ ion . It was found that this substitution allows tunable changes in the magnetic properties of cobalt ferrite. Interestingly, saturation magnetization first increases upto x = 0.4 and then decreases for higher Zn substitution, thus tunable changes in magnetic properties of cobalt ferrite are possible. Source of such behaviour could be the variation of exchange interaction between the tetrahedral and the octahedral sites.
基金supported by Specialized Research Fund for Doctoral Program of Higher Education of China (Grant No. 20060287019)Opening Research Fund of Jiangsu Provincial Key Laboratory of Tribology of China (Grant No. kjsmcx07001)Jiangsu Provincial Graduate Innovation Foundation of China (Grant No. CX08B-039Z)
文摘Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its application in the bond coat of duplex structure thermal barrier coating(TBC). Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition (1%, mass fraction) were prepared by the laser cladding technique on Ni-based superalloy substrates, aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings (the bond coat of the duplex structure thermal barrier coatings). Scanning electron microscope (SEM), X-ray diffractometer(XRD) and thermogravimetry were employed to investigate their morphologies, phases and cyclic oxidation behaviors in atmosphere at 1 050℃, compared with the coating without nano-particles. With the addition of nano-particles, the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth; slender dendrites were broken and cellularized; cracks and pores were restrained; and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well. Among the three kinds of nano-particles, the SiC nano-particles showed the most improvement on microstructure, while the CeO2 nano-particles were insufficient, but its effects on the oxidation resistance are the same as those of the SiC nano-particles. Based on the discussions of the influence mechanism, it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted, with the synergistic action of nanometer effect and reactive element effect.
基金the financial support by the National Natural Science Foundation of China(No.20973022 and No.11472048)
文摘A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.
基金This research was financially supported by the Key Project of China Educational Ministry (No. 103064)the Doctoral Foundation of University (No. 20020246031)
文摘Poly(St-co-BuA)/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-(trimethoxysilyl)propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope (TEM) and scanning electron microscope (SEM) in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.
基金This project is supported by National Natural ScienceFoundation of China (No.59835180) and Science andTechnology Foundatio
文摘To understand the deformation and removal mechanism of material on nano-scale at ultralow loads,a systemic study on AFM micro/nano-machining on single crystal ailicon is conducted. The results indicate that AFM nano- machining has a precisely dimensional controllability and a good surface quality on nanometer scale.A SEM is adopted to observe nano-machined region and chips,the results indicate that the material removal mechanisms change with the applied normal load. An XPS is used to analyze the changes of chemical composition inside and outside the nano-machined region respectively.The nano-indentation which is conducted with the same AFM diamond tip on the machined region shows a big discrepancy compared with that on the macro-scale. The calculated results show higher nano-hardness and elastic modulus than normal values .This phenomenon on be regarded as the indentation size effect(ISE).
基金Project(20806035) supported by the National Natural Science Foundation of ChinaProject(2009CI026) supported by Back-up Personnel Foundation of Academic and Technology Leaders of Yunnan Province,China+4 种基金Project(KKZ6200927001) supported by Opening Fund of Key Laboratory of Inorganic Coating Materials, Chinese Academy of Sciences Project(2007E187M) supported by Applied Basic Research Plans of Yunnan Province,ChinaProject(08C0025) supported by Scientific Research Fund of Yunnan Provincial Education Department, China Project(KKZ3200927029) supported by Training Foundation for Talents of Kunming University of Science and Technology,ChinaProject(2008-003) supported by Analysis and Measurement Research Fund of Kunming University of Science and Technology,China
文摘Ni-W-P base composites containing CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by pulse co-deposition of Ni,W,P,CeO2 and SiO2 nano-particles.The influence of SiO2 concentrations in bath on microstructures and properties of Ni-W-P/CeO2-SiO2 composites was studied,and the characteristics were assessed by chemical compositions,element distribution,surface morphologies,deposition rate and microhardness.The results indicate that when SiO2 concentration in bath is controlled at 20 g/L,the composites possess the fastest deposition rate,the highest microhardness,compact microstructures,smaller crystallite sizes and uniform distribution of W,P,Ce and Si within Ni-W-P matrix metal.Increasing SiO2 concentration in bath from 10 to 20 g/L leads to the refinement in grain size and the inhomogeneity of microstructures.While when SiO2 concentration is increased to 30 g/L,the crystallite sizes increase again and some bosses with nodulation shape appear on the surface of composites.
文摘In order to improve the wear resistance and high temperature oxidation resistance of titanium and titanium alloy, the high temperature ultra fine ceramic coating containing nano-size nickel particles was prepared by flow coat method on the surface of industrially pure titanium TB1-0. The effects of nano-size nickel particles on the wear resistance and high temperature oxidation resistance of coating substrate system were investigated through oxidation kinetics experiment and wear resistance test. The morphologies of the specimens were examined by means of optical microscopy, scanning electron microscopy and X-ray diffraction. The results show that the high temperature ultra fine ceramic coating has notable protection effect on industrially pure titanium TB1-0 from oxidation. The oxidation and wear resistance properties of the coating can be effectively improved by adding nano-size nickel particles. The oxidative mass gain of the specimen decreases from 11.33 mg·cm-2 to 5.25 mg·cm-2 and the friction coefficient decreases from 1.1 to 0.6 by adding nano-size nickel particles, and the coating containing 10% （mass fraction） nano-size nickel shows the optimum properties.
基金Projects(30572455,30670990)supported by the National Natural Science Foundation of ChinaProject(20060390891)supported by Postdoctor Foundation of China+1 种基金Project(NCET-06-0685)supported by the Program of New Century Excellent Talent in University of Ministry of Education of ChinaProject(2006FJ4243)supported by Science and Technology of Hunan Province,China
文摘In order to synthesize the targeting drug carrier system,magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil(5-Fu)as model drug,Fe3O4 nano-particles as kernel,chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique.The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM).The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm.The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis.The results showed that the loading capacity was 13.4%and the cumulative release percentage in the phosphate buffer(pH=7.2)solutions was 68%in 30 h.These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released.The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance.Without external magnetic field,the nano-particle deposition rate was slow.When being subjected to 8 mT magnetic field,the particle sedimentation rate was increased rapidly.The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.
基金Funded by the National Science Foundation of China ( No.50375037)
文摘Si3N4-Si2N2O composites were fabricated with amorphous nano-sized silicon nitride powders by the liquid phase sintering （LPS）. The Si2N2O phase was generated by an in-situ reaction 2Si3N4（s）+ 1.5 O2（g）=3Si2N2O（s）+N2（g）. The content of Si2N2O phase up to 60% in the volume was obtained at a sintering temperature of 1 650 ℃ and reduced when the sintering temperature increased or decreased, indicating the reaction is reversible. The mass loss, relative density and average grain size increased with increasing the sintering temperature. The average grain size was less than 500 nm when the sintering temperature was below 1 700 ℃. The sintering procedure contains a complex crystallization and a phase transition: amorphous silicon nitride→equiaxial α-Si3N4→equiaxial β-Si3N4→rod-like Si2N2O→needle-like β-Si3N4. Small round-shaped β-Si3N4 particles were entrapped in the Si2N2O grains and a high density of staking faults was situated in the middle of Si2N2O grains at a sintering temperature of 1 650 ℃. The toughness increased from 3.5 MPa·m 1/2 at 1 600 ℃ to 7.2 MPa·m 1/2 at 1 800 ℃. The hardness was as high as 21.5 GPa （Vickers） at 1 600 ℃.
文摘Many researchers in academia and industries are interested in reducing particle sizes from few submicrometers to nano-meter levels.These nano-particles find application in several areas including ceramics,paints,cosmetics,microelectronics,sensors,textiles and biomedical,etc.This article reviews the present state of the art for solid state synthesis of mineral nano-particles by wet milling,including their operating variables such as ball size,solid mass fraction and suspension stability.This article concludes and recommends with a critical discussion of nano-particles synthesis and a few common strategies to overcome stability issues.
文摘Based on the composite modification technology of the surface of nano silicon dioxide by non-soap emulsion polymerization, it is verified that there are polymer grafted on the surface of nano silicon dioxide. The modification mechanism and the bonding status on the surface of nano silicon dioxide after modification were suggested via the results of the infrared spectrum, transmission electronic microscope photograph and X-ray photoelectron spectrum. The hydroxyl formed by hydrolyzing of silane coupling agent reacts with hydroxyl on the surface of nano silicon dioxide to form Si-O-Si bonds by losing water molecules and hence the double bonds are introduced onto the surface of nano silicon dioxide. The surface of nano silicon dioxide is grafted with polymer through free radical polymerization between the double bonds on the surface of nano silicon dioxide and styrene under the action of initiating agent. The dispersibility of nano silicon dioxide and the controllability of surface modification of nano silicon dioxide can be greatly improved by the modification process.
基金Project(51206033)supported by the National Natural Science Foundation of ChinaProjects(2011M500652,2013T60354)supported by the China Postdoctoral Science FoundationProject(2011LBH-Z11139)supported by the Heilongjiang Postdoctoral Science Foundation,China
文摘In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process.
基金supported by 973(2011CB935900,2010CB631303)NSFC(21231005,51071087)+4 种基金111 Project(B12015)MOE(IRT13R30)the Research Fund for the Doctoral Program of Higher Education of China(20120031110001)Tianjin Sci&Tech Project(10SYSYJC27600)the Nature Science Foundation of Tianjin(11JCYBJC07700)
文摘Assisted by graphene oxide(GO),nano-sized LiMn_(0.6)Fe_(0.4)PO_4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn_(0.6)Fe_(0.4)PO_4(S2)was about 80 nm in diameter.The discharge capacity of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn_(0.6)Fe_(0.4)PO_4 and it in situ reduction of GO could improve the electrical conductivity of LiMn_(0.6)Fe_(0.4)PO_4 material.
