In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of S...In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.展开更多
As a preliminary investigation towards obtaining carbon nanotube composite adsorbent for CO2 capture, in this study CO2 adsorption performance of three commercial carbon nanotubes （CNTs） one single-walled carbon nan...As a preliminary investigation towards obtaining carbon nanotube composite adsorbent for CO2 capture, in this study CO2 adsorption performance of three commercial carbon nanotubes （CNTs） one single-walled carbon nanotubes （SWCNTs）, and two （2） different multi-walled carbon nanotubes （referred to as A-MWCNTs and B-MWCNTs） were evaluated and compared. The purpose of this study was to compare the different types of CNTs and select the best to serve as the solid anchor in the development of a hydrophobic composite adsorbent material for CO2 capture. The N2 physi- sorption of the CNTs was conducted to determine their surface area, pore volume and pore size. In addition, morphology and purity of the CNTs were checked with Transmission Electron Microscopy and Raman Spectroscopy, respectively. The CO2 adsorption capacity of the CNTs was evaluated using Thermo-gravimetric analysis （TGA） at 1.1 bar, at operating temperature ranged from 25 to 55 ~C and at different CO2 feed flow rates, in order to evaluate the effects of these variables on the CO2 adsorption capacity. The results of CO2 adsorption with the TGA show that CO2 adsorption capacity for both SWCNTs and MWCNTs was the highest at 25 ~C. Changing the CO2 flowrates had no significant effect on the adsorption capacity of MWCNTs, but decreasing the CO2 flow rate resulted in the enhancement of the CO2 adsorption capacity of SWCNTs. Overall, it was found that the SWCNTs displayed the highest CO2 adsorption capacity （29.97 gCO2/kg ad- sorbent） when compared to the MWCNTs （12.09 gCO2/kg adsorbent）, indicating a 150% increase in adsorption capacity over MWCNTs.展开更多
The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of th...The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of the main properties to evaluate the CFRP＇s performance for transportation and aerospace structures. Two types of nanoparticle, namely nanofibers and nano-silica beads, were added into the epoxy resin to improve the impact absorption capacity of the CFRP. Two modified additives and conventional epoxy resins were quantitatively compared. The impact test results showed that impact absorbed energy for nanofibers was higher than nano-silica beads, and nanofibers as the additive promoted about 11% of impact absorbed energy compared with neat epoxy resin.展开更多
Polymer-coated mesoporous carbon nanocomposites were prepared from the immobilization of acrylonitrile and acrylic acid copolymers with divinylbenzene as a crosslinker onto a mesoporous carbon framework.High surface a...Polymer-coated mesoporous carbon nanocomposites were prepared from the immobilization of acrylonitrile and acrylic acid copolymers with divinylbenzene as a crosslinker onto a mesoporous carbon framework.High surface areas were maintained after polymerization with accessible porosity.This functional nanocomposite was tested as an adsorbent for uranium from high salinity solutions.Uranium adsorption results have shown that the adsorption capacities are strongly influenced by the density of the amidoxime groups and the specific surface area.展开更多
In this work,the influence of strain on threshold energy of absorption in Silicon circular nanowires is investigated.For this purpose,we first have used the density functional theory(DFT) to calculate the electron and...In this work,the influence of strain on threshold energy of absorption in Silicon circular nanowires is investigated.For this purpose,we first have used the density functional theory(DFT) to calculate the electron and hole effective masses.Then,we have obtained absorption threshold energy with two different procedures,DFT and effective mass approximation(EMA).We have also obtained the band structures of Si nanowires both DFT and EMA.The results show that:i) the expansive strain increases the hole effective mass while compressive strain increases the electron effective mass,ii) the electron and hole effective masses reduce with decreasing the wire size,iii) the absorption threshold energy decreases by increasing strain for compressive and tensile strain and its behavior as a function of strain is approximately parabolic,iv) the absorption threshold energy(for all sizes) obtained using EMA is greater than the DFT results.展开更多
文摘In this study, author investigated the spectral response of EM （electromagnetic） energy absorption in a colloidal system of Fe3O4 nanoparticles with an average size of 9.50 nm immersed in a 2% aqueous solution of SDS （sodium dodeci[ sulfate）. The temperature of the nanoparticles and the SDS solution was evaluated by a novel method based on measuring the Q-factor （quality-factor） of a resonant circuit. The Q-factor of the investigated system as a function of the frequency of the EM field was obtained. The nanoparticles-SDS liquid system exhibited a resonance-like behavior of the absorption, where the resonance frequency was about 170 MHz, and the absorption rise up to the resonance frequency was rather slow. The observed absorption of EM energy was accompanied by a small temperature increasing of the system. Measurements of the ESR （electron spin resonance） spectrum of the Fe3O4 nanoparticles have presented a slightly asymmetric singlet with the proportionality factor g = 2 and a line-width of the magnetic field strength △H = 0.1 mT. It was shown that the observed absorption spectrum corresponds to paramagnetic behavior of the investigated nanoparticles.
文摘As a preliminary investigation towards obtaining carbon nanotube composite adsorbent for CO2 capture, in this study CO2 adsorption performance of three commercial carbon nanotubes （CNTs） one single-walled carbon nanotubes （SWCNTs）, and two （2） different multi-walled carbon nanotubes （referred to as A-MWCNTs and B-MWCNTs） were evaluated and compared. The purpose of this study was to compare the different types of CNTs and select the best to serve as the solid anchor in the development of a hydrophobic composite adsorbent material for CO2 capture. The N2 physi- sorption of the CNTs was conducted to determine their surface area, pore volume and pore size. In addition, morphology and purity of the CNTs were checked with Transmission Electron Microscopy and Raman Spectroscopy, respectively. The CO2 adsorption capacity of the CNTs was evaluated using Thermo-gravimetric analysis （TGA） at 1.1 bar, at operating temperature ranged from 25 to 55 ~C and at different CO2 feed flow rates, in order to evaluate the effects of these variables on the CO2 adsorption capacity. The results of CO2 adsorption with the TGA show that CO2 adsorption capacity for both SWCNTs and MWCNTs was the highest at 25 ~C. Changing the CO2 flowrates had no significant effect on the adsorption capacity of MWCNTs, but decreasing the CO2 flow rate resulted in the enhancement of the CO2 adsorption capacity of SWCNTs. Overall, it was found that the SWCNTs displayed the highest CO2 adsorption capacity （29.97 gCO2/kg ad- sorbent） when compared to the MWCNTs （12.09 gCO2/kg adsorbent）, indicating a 150% increase in adsorption capacity over MWCNTs.
文摘The present study investigates the effect of the addition of nanoparticles into epoxy resins as the matrix on the impact absorbed energy of CFRP （carbon fiber reinforced polymer）. Impact absorbed energy is one of the main properties to evaluate the CFRP＇s performance for transportation and aerospace structures. Two types of nanoparticle, namely nanofibers and nano-silica beads, were added into the epoxy resin to improve the impact absorption capacity of the CFRP. Two modified additives and conventional epoxy resins were quantitatively compared. The impact test results showed that impact absorbed energy for nanofibers was higher than nano-silica beads, and nanofibers as the additive promoted about 11% of impact absorbed energy compared with neat epoxy resin.
基金sponsored by the US Department of EnergyOffice of Nuclear Energy+2 种基金under contract DE-AC05-00OR22725 with Oak Ridge National Laboratorymanaged by UT-BattelleLLC
文摘Polymer-coated mesoporous carbon nanocomposites were prepared from the immobilization of acrylonitrile and acrylic acid copolymers with divinylbenzene as a crosslinker onto a mesoporous carbon framework.High surface areas were maintained after polymerization with accessible porosity.This functional nanocomposite was tested as an adsorbent for uranium from high salinity solutions.Uranium adsorption results have shown that the adsorption capacities are strongly influenced by the density of the amidoxime groups and the specific surface area.
文摘In this work,the influence of strain on threshold energy of absorption in Silicon circular nanowires is investigated.For this purpose,we first have used the density functional theory(DFT) to calculate the electron and hole effective masses.Then,we have obtained absorption threshold energy with two different procedures,DFT and effective mass approximation(EMA).We have also obtained the band structures of Si nanowires both DFT and EMA.The results show that:i) the expansive strain increases the hole effective mass while compressive strain increases the electron effective mass,ii) the electron and hole effective masses reduce with decreasing the wire size,iii) the absorption threshold energy decreases by increasing strain for compressive and tensile strain and its behavior as a function of strain is approximately parabolic,iv) the absorption threshold energy(for all sizes) obtained using EMA is greater than the DFT results.
