In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, ...In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 rain is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.展开更多
6-12 nm silver nanoparticles were synthesized by the pulsed laser ablation of a high purity silver bulk in distilled water. Effect of laser fluence on the size, morphology and structure of produced nanoparticles has b...6-12 nm silver nanoparticles were synthesized by the pulsed laser ablation of a high purity silver bulk in distilled water. Effect of laser fluence on the size, morphology and structure of produced nanoparticles has been studied experimentally. Pulses of a Q-switched Nd:YAG laser of 1064 wavelength at 7 ns pulse width at different fluences were employed to irradiate the silver target in water. The UV-Visible absorption spectra of the Ag nanoparticles exhibit surface plasmon resonance absorption peak in the UV region. TEM and SEM micrographs, in a good agreement with DLS results, indicate that with increasing the laser fluence the average size of spherical Ag nanoparticles is decreased. It is found that Ag nanoparticles exhibit photoluminescence emission with two peaks because of the inter band transition and electron-hole recombination.展开更多
Effect of laser fluence on the characteristics of gold nanoparticles (NPs) produced by laser ablation method is investigated experimentally. Five samples of gold NPs were synthesized by nanosecond pulsed laser ablatio...Effect of laser fluence on the characteristics of gold nanoparticles (NPs) produced by laser ablation method is investigated experimentally. Five samples of gold NPs were synthesized by nanosecond pulsed laser ablation of a high purity gold plate in distilled water at five different fluences in the range of 1-3 J/cm2. Results show that in this experimental condition gold NPs are produced by nucleation of Au atoms in the plasma, generated on the target surface during the ablation process. There is threshold fluence at which absorption of laser energy by water rises significantly. Absorption of the laser energy by water leads to increase oxygen atoms in the ablation medium and formation of gold oxide NPs. By increasing the laser fluence below the threshold, size of produced NPs decreases while by increasing the laser fluence above the threshold size of produced NPs increases.展开更多
文摘In this study atmospheric pressure dielectric barrier discharge （DBD） plasma has been employed for sterilizing dry turmeric powders. A 6 kV, 6 kHz frequency generator was used to generate plasma with Ar, Ar/Ou, He, and He/O2 gases between the 5 mm gap of two quartz covered electrodes. The complete sterilization time of samples due to plasma treatment was measured. The most important contaminant of turmeric is bacillus subtilis. The results show that the shortest sterilization time of 15 rain is achieved by exposing the samples to Ar/O2 plasma. Survival curves of samples are exponential functions of time and the addition of oxygen to plasma leads to a significant increase of the absolute value of time constant of the curves. Magnitudes of protein and DNA in treated samples were increased to a similar value for all samples. Taste, color, and solubility of samples were not changed after the plasma treatment.
文摘6-12 nm silver nanoparticles were synthesized by the pulsed laser ablation of a high purity silver bulk in distilled water. Effect of laser fluence on the size, morphology and structure of produced nanoparticles has been studied experimentally. Pulses of a Q-switched Nd:YAG laser of 1064 wavelength at 7 ns pulse width at different fluences were employed to irradiate the silver target in water. The UV-Visible absorption spectra of the Ag nanoparticles exhibit surface plasmon resonance absorption peak in the UV region. TEM and SEM micrographs, in a good agreement with DLS results, indicate that with increasing the laser fluence the average size of spherical Ag nanoparticles is decreased. It is found that Ag nanoparticles exhibit photoluminescence emission with two peaks because of the inter band transition and electron-hole recombination.
文摘Effect of laser fluence on the characteristics of gold nanoparticles (NPs) produced by laser ablation method is investigated experimentally. Five samples of gold NPs were synthesized by nanosecond pulsed laser ablation of a high purity gold plate in distilled water at five different fluences in the range of 1-3 J/cm2. Results show that in this experimental condition gold NPs are produced by nucleation of Au atoms in the plasma, generated on the target surface during the ablation process. There is threshold fluence at which absorption of laser energy by water rises significantly. Absorption of the laser energy by water leads to increase oxygen atoms in the ablation medium and formation of gold oxide NPs. By increasing the laser fluence below the threshold, size of produced NPs decreases while by increasing the laser fluence above the threshold size of produced NPs increases.
