Electric current stimulation has been shown to have a positive influence on heterotrophic denitrifying microbial viability and has the potential to improve wastewater denitrification performance. This study investigat...Electric current stimulation has been shown to have a positive influence on heterotrophic denitrifying microbial viability and has the potential to improve wastewater denitrification performance. This study investigated the effects of varying current densities on microbial activity and NO3- removal efficiency under heterotrophic conditions.NO3-removal rate was highest at an applied current density of 400 mA/m2. However, the optimum removal efficiency of total inorganic nitrogen(TIN;99%) was achieved when the current density was fixed at 200 m A/m2. Accumulation of NH4+-N and NO2--N byproducts were also minimized at this current density. The activity of heterotrophic denitrifying microorganisms was much higher at both 200 and 400 mA/m2. Moreover, the average adenosine-5′-triphosphate(ATP)content(an indicator of cell metabolism) at a current density of 1600 mA/m2 was lower than that under no current, indicating heterotrophic denitrifying microbial activity can be inhibited at high current densities. Hence, direct electrical stimulation on the activity of heterotrophic denitrifying microorganisms in the developed system should be lower than 1600 mA/m2. This study improves the understanding of electric current influence on heterotrophic denitrifying microorganisms and promotes the intelligent application of direct electrical stimulation on wastewater treatment processes.展开更多
Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pr...Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pressure of N 2 , the nitrogen content in the weld pool increased dramatically, and the γ zone was enlarged. The nitrogen content increased as alloying elements such as Cr and Mn were added to the molten steel. The δ zone with high temperature treatment was compressed by adding Ni. These alloying elements play important roles in the formation of the single γ region at the temperature of 298 K. With proper Mn addition, the phase area of γ was extended and became more stable, and the “ferrite trap” was also avoided. Two kinds of welding wires with different nitrogen contents were developed and corresponding MIG welding experiments were performed. As the nitrogen content in wire was higher than that in the base metal, severe blowhole defects and mixture microstructure of δ and γ developed.展开更多
We present a multi-transition study to investigate the physical properties of dust and moleculargas in the archetypical merger Arp 299 by using data including James Clerk Maxwell Telescope (JCMT)850 and 450 μm obse...We present a multi-transition study to investigate the physical properties of dust and moleculargas in the archetypical merger Arp 299 by using data including James Clerk Maxwell Telescope (JCMT)850 and 450 μm observations, Herschel 500, 350, 250, 160 and 70 ktm continuum maps, as well as theCO(3-2), CO(4-3) low-J CO lines and CO(11-10), CO(13-12), CO(14-13) high-J CO lines. TheCO(3-2) and CO(4-3) lines are observed by JCMT, and the CO(11-10), CO(13-12), CO(14-13) linesare available on the Herschel Science Archive. The resolution of the Herschel Spectral and PhotometricImaging Receiver (SPIRE) Fourier transform spectrometer (FTS) CO(11-10) data is similar to that ofthe JCMT CO(3-2) line, while the resolution of the SPIRE/FTS CO(13-12) and Photodetector ArrayCamera and Spectrometer (PACS) CO(14-13) data is similar to that of JCMT CO(4-3), allowing us toobtain accurate line ratios of/CO(11-10)/Ico(3-2), Ico(13-12)/Ico(4-3) and Ico(14-13)//CO(4-3).By modeling the spectral energy distribution of the continuum data, we conclude that two components(cold and warm) exist in the dust, with the warm component occupying a small percent of the total dustmass. We further use a radiative transfer analysis code, RADEX, to calculate the density, temperatureand column density of warm gas in the central region, which shows that the kinetic temperature Tkin isin the range 1 l0 to 150 K and hydrogen density n(H2) is in the range 104.7 - 10^5.5 cm^-3. We showthat the hot dust is located in the central region of IC 694 with a radius of-4″ and estimate that thewarm gas mass is in the range 3.8×10^7 Mo to 7.7 × 10^7 M, which contains 5.0%-15.0% of the totalH2 mass for the region of IC 694. We also calculate the star formation rate of the galaxy in particular,which is much higher than that of the Milky Way.展开更多
基金supported by the National Key Research and Development Program of China(No.2016YFD0501405)the National Natural Science Foundation of China(No.51578519)+1 种基金the China Postdoctoral Science Foundation(No.2018M630245)the Beijing Postdoctoral Research Foundation(No.2017-ZZ-137).
文摘Electric current stimulation has been shown to have a positive influence on heterotrophic denitrifying microbial viability and has the potential to improve wastewater denitrification performance. This study investigated the effects of varying current densities on microbial activity and NO3- removal efficiency under heterotrophic conditions.NO3-removal rate was highest at an applied current density of 400 mA/m2. However, the optimum removal efficiency of total inorganic nitrogen(TIN;99%) was achieved when the current density was fixed at 200 m A/m2. Accumulation of NH4+-N and NO2--N byproducts were also minimized at this current density. The activity of heterotrophic denitrifying microorganisms was much higher at both 200 and 400 mA/m2. Moreover, the average adenosine-5′-triphosphate(ATP)content(an indicator of cell metabolism) at a current density of 1600 mA/m2 was lower than that under no current, indicating heterotrophic denitrifying microbial activity can be inhibited at high current densities. Hence, direct electrical stimulation on the activity of heterotrophic denitrifying microorganisms in the developed system should be lower than 1600 mA/m2. This study improves the understanding of electric current influence on heterotrophic denitrifying microorganisms and promotes the intelligent application of direct electrical stimulation on wastewater treatment processes.
文摘Based on thermodynamic calculations, the effect of pressure and alloying elements on the nitrogen content, solidification mode, and welding characteristics were investigated in this study. By increasing the partial pressure of N 2 , the nitrogen content in the weld pool increased dramatically, and the γ zone was enlarged. The nitrogen content increased as alloying elements such as Cr and Mn were added to the molten steel. The δ zone with high temperature treatment was compressed by adding Ni. These alloying elements play important roles in the formation of the single γ region at the temperature of 298 K. With proper Mn addition, the phase area of γ was extended and became more stable, and the “ferrite trap” was also avoided. Two kinds of welding wires with different nitrogen contents were developed and corresponding MIG welding experiments were performed. As the nitrogen content in wire was higher than that in the base metal, severe blowhole defects and mixture microstructure of δ and γ developed.
基金supported by the China Ministry of Science and Technology under the State Key Development Program for Basic Research (2012CB821800)+2 种基金
supported by the Joint Research Fund in Astronomy (U1531246) under cooperative agreement between the National Natural Science Foundation of China (NSFC) and the Chinese Academy of Sciences (CAS)
supported by the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences (Grant No. XDB09000000)
文摘We present a multi-transition study to investigate the physical properties of dust and moleculargas in the archetypical merger Arp 299 by using data including James Clerk Maxwell Telescope (JCMT)850 and 450 μm observations, Herschel 500, 350, 250, 160 and 70 ktm continuum maps, as well as theCO(3-2), CO(4-3) low-J CO lines and CO(11-10), CO(13-12), CO(14-13) high-J CO lines. TheCO(3-2) and CO(4-3) lines are observed by JCMT, and the CO(11-10), CO(13-12), CO(14-13) linesare available on the Herschel Science Archive. The resolution of the Herschel Spectral and PhotometricImaging Receiver (SPIRE) Fourier transform spectrometer (FTS) CO(11-10) data is similar to that ofthe JCMT CO(3-2) line, while the resolution of the SPIRE/FTS CO(13-12) and Photodetector ArrayCamera and Spectrometer (PACS) CO(14-13) data is similar to that of JCMT CO(4-3), allowing us toobtain accurate line ratios of/CO(11-10)/Ico(3-2), Ico(13-12)/Ico(4-3) and Ico(14-13)//CO(4-3).By modeling the spectral energy distribution of the continuum data, we conclude that two components(cold and warm) exist in the dust, with the warm component occupying a small percent of the total dustmass. We further use a radiative transfer analysis code, RADEX, to calculate the density, temperatureand column density of warm gas in the central region, which shows that the kinetic temperature Tkin isin the range 1 l0 to 150 K and hydrogen density n(H2) is in the range 104.7 - 10^5.5 cm^-3. We showthat the hot dust is located in the central region of IC 694 with a radius of-4″ and estimate that thewarm gas mass is in the range 3.8×10^7 Mo to 7.7 × 10^7 M, which contains 5.0%-15.0% of the totalH2 mass for the region of IC 694. We also calculate the star formation rate of the galaxy in particular,which is much higher than that of the Milky Way.