The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a ...The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a rise time of≈1.5μs were applied across a 45-mm point-to-plane gap.Under these conditions,spark channels consisting of bright and dim regions(bead structure)were observed.It is shown that when current is limited,an increase in the rise time and the gap length does not affect the formation of the bead structure.It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads.The appearance of the bead structure is more likely at negative polarity of the pointed electrode.The formation of spark channels was studied with a four-channel ICCD camera.展开更多
Electrospun sodium alginate(SA)fibers,which are always considered as a kind of biocompatible and non-toxic materials,have great potential application in the biomedical field due to high specific surface area and large...Electrospun sodium alginate(SA)fibers,which are always considered as a kind of biocompatible and non-toxic materials,have great potential application in the biomedical field due to high specific surface area and large porosity.However,in order to facilitate the electrospinning process,another polymer should be added into the SA solution.The effect of the added polymer of polyethylene oxide(PEO),SA,and ethanol on tuning the beaded structure of electrospun fibers was evaluated.Pure SA electrospun membrane with a beaded structure was prepared.The results show that PEO can facilitate the fabrication,but the mass fractions of SA and ethanol are positively correlated with the bead forming.When the mass fraction of ethanol in the solution was 15.0%(mass fractions of SA and PEO were 1.0%and 1.5%,respectively),the average diameter of the obtained beads was 824.80 nm,and the average length was 2.88μm.Besides,the fibrous structure can be maintained even after the removal of PEO by ethanol.After removing PEO,the average diameter of the beads was reduced to 578.73 nm and the average length was reduced to 2.34μm.展开更多
A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions.The core,made of sodium alginate-g-polyacrylamide and attapulgite nanofibers,was cross-linked by Calci...A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions.The core,made of sodium alginate-g-polyacrylamide and attapulgite nanofibers,was cross-linked by Calcium ions(Ca^(2+)).The shell,composed of a chitosan/activated carbon mixture,was then coated onto the core.Fourier transform infrared spectroscopy confirmed the grafting polymerization of acrylamide onto sodium alginate.Scanning electron microscopy images showed the core-shell structure.The core exhibited a high water uptake ratio,facilitating the diffusion of methylene blue into the core.During the diffusion process,the methylene blue was first adsorbed by the shell and then further adsorbed by the core.Adsorption tests showed that the coreshell structure had a larger adsorption capacity than the core alone.The shell effectively enhanced the adsorption capacity to methylene blue compared to the single core.Methylene blue was adsorbed by activated carbon and chitosan in the shell,and the residual methylene blue diffused into the core and was further adsorbed.展开更多
基金The work is performed in the framework of the State task for HCEI SB RAS,project#13.1.4.
文摘The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a rise time of≈1.5μs were applied across a 45-mm point-to-plane gap.Under these conditions,spark channels consisting of bright and dim regions(bead structure)were observed.It is shown that when current is limited,an increase in the rise time and the gap length does not affect the formation of the bead structure.It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads.The appearance of the bead structure is more likely at negative polarity of the pointed electrode.The formation of spark channels was studied with a four-channel ICCD camera.
基金Fundamental Research Funds for the Central Universities of China(No.2232019D3-15)。
文摘Electrospun sodium alginate(SA)fibers,which are always considered as a kind of biocompatible and non-toxic materials,have great potential application in the biomedical field due to high specific surface area and large porosity.However,in order to facilitate the electrospinning process,another polymer should be added into the SA solution.The effect of the added polymer of polyethylene oxide(PEO),SA,and ethanol on tuning the beaded structure of electrospun fibers was evaluated.Pure SA electrospun membrane with a beaded structure was prepared.The results show that PEO can facilitate the fabrication,but the mass fractions of SA and ethanol are positively correlated with the bead forming.When the mass fraction of ethanol in the solution was 15.0%(mass fractions of SA and PEO were 1.0%and 1.5%,respectively),the average diameter of the obtained beads was 824.80 nm,and the average length was 2.88μm.Besides,the fibrous structure can be maintained even after the removal of PEO by ethanol.After removing PEO,the average diameter of the beads was reduced to 578.73 nm and the average length was reduced to 2.34μm.
文摘A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions.The core,made of sodium alginate-g-polyacrylamide and attapulgite nanofibers,was cross-linked by Calcium ions(Ca^(2+)).The shell,composed of a chitosan/activated carbon mixture,was then coated onto the core.Fourier transform infrared spectroscopy confirmed the grafting polymerization of acrylamide onto sodium alginate.Scanning electron microscopy images showed the core-shell structure.The core exhibited a high water uptake ratio,facilitating the diffusion of methylene blue into the core.During the diffusion process,the methylene blue was first adsorbed by the shell and then further adsorbed by the core.Adsorption tests showed that the coreshell structure had a larger adsorption capacity than the core alone.The shell effectively enhanced the adsorption capacity to methylene blue compared to the single core.Methylene blue was adsorbed by activated carbon and chitosan in the shell,and the residual methylene blue diffused into the core and was further adsorbed.
