Effect of Polystyrene Latex Addition on Size and Pore Volume of Porous Calcium Oxide Particles Prepared by Spray-Pyrolysis Method and Its Ability for SO2 Retention

In this study, the effects of polystyrene (PS) latex addition on the particle morphology and the pore content of calcium oxide (CaO) were investigated. The CaO particles were prepared using an ultrasonic nebulizer-assisted spray-pyrolysis method with variation of the PS/Ca(NO3)2·4H2O mass ratio in the precursor. Good crystallinity of CaO was obtained at 825°C of synthesis temperature under 2 l/min of nitrogen gas flow, which was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). According to scanning electron microscope (SEM) characterization, the CaO particles synthesized with 0 and 25 wt% PS addition had an almost spherical shape with an average size of 1.58 and 1.48 µm, respectively. In addition, macropores were formed in the CaO particles prepared with 25 wt% PS addition that had an average pore diameter of 583.26 nm. Meanwhile, the CaO particles prepared with 75 wt% PS addition had a random shape and an average size of 1.41 µm. The mesopore content was investigated by Barret-Joyner-Halenda (BJH) analysis, which showed improvement of the pore size from 3.45 nm to 5.42 nm for 0 and 25 wt% PS addition, respectively, which is proportional to the pore volume, pore surface area, and the capacity of SO2 retention

Dispersion of Vascular Plant in Kumo-do, Korea

AbstractThe vascular plants observed in the area were composed of a total of 228 taxa; 72 families, 172 genus, 201 species, 25 varieties, 1 sub-species and 1 cross species. The only endangered plants found in the area were Milletia japonica (Siebold & Zucc.) A.Gray. The endemic plants growing in the Geumodo except transplanted plants were Lespedeza x maritima Nakai and Carpinus coreana Nakai. which accounted for 0.8% of the vascular plants in Geumodo, 228 taxa. Specialized plants of Geumodo were a total of 41 species; 30 taxa in Grade I, 1 taxon in Grade II, 9 taxa in Grade III and 1 taxon in Grade V. Milletia japonica (Siebold & Zucc.) A.Gray was the only species found in important Grade IV to V. Currently, ferries ply to the island, attracting many tourists. This poses a threat to the rare plants living in the island and presses down the island to develop. Therefore, in the long-term perspective, the conservation plan such as comprehensive research and monitoring on the ecosystem shall be established to protect evergreen broad-leaved forests

Diffusion Decay Coefficient for Chloride Ions of Concrete Containing Mineral Admixtures

The diffusion coefficient for chloride ions and the diffusion decay coefficient for chloride ions are essential variables for a service life evaluation of concrete structures. They are influenced by water-binder ratio, exposure condition, curing temperature, cement type, and the type and use of mineral admixture. Mineral admixtures such as ground granulated blast furnace slag, fly ash, and silica fume have been increasingly used to improve resistance against chloride ions penetration in concrete structures built in an offshore environment. However, there is not enough measured data to identify the statistical properties of diffusion decay coefficient for chloride ions in concrete using mineral admixtures. This paper is aimed at evaluating the diffusion decay coefficient for chloride ions of concrete using ordinary Portland cement or blended cement. NT BUILD 492 method, an electrophoresis experiment, was used to measure the diffusion coefficient for chloride ions with ages. It was revealed from the test results that the diffusion decay coefficient for chloride ions was significantly influenced by W/B and the replacement ratio of mineral admixtures

Accidental benzene release risk assessment in an urban area using an atmospheric dispersion model

This study applied the American Meteorological Society and Environmental Protection Agency Regulatory Model (AERMOD) to assess the risk caused by an accidental release and dispersion of the toxic chemical benzene in the vicinity of a highly populated urban area. The modeling domain encompasses the Korean megacity of Ulsan, which includes two national industrial complexes and is characterized by a complex coastal terrain. Multiple AERMOD simulations were conducted for an assumed emission scenario using background wind data from August between 2009 and 2013. The series of experiments produced the spatial accident probability patterns for different concentration levels during daytime and nighttime scenarios based on the corresponding dominant wind patterns. This study further quantifies the potential accident risk based on the number of affected individuals by combining the accident probability with the indoor and outdoor population estimates. The chemical gas dispersion characteristics depend on various local meteorological conditions, such as the land-sea breeze direction, which alternates between daytime and nighttime, and the atmospheric stability. The results reveal that benzene dispersion affects a much larger area during the nighttime owing to the presence of a nocturnal stable boundary layer with significant temperature stratification. The affected area is smaller during the daytime owing to decreased stability and enhanced vertical mixing in the boundary layer. The results include a high degree of uncertainty during the nighttime owing to weak wind speeds and the lack of a prevailing wind direction, which impact the vulnerable area. However, vulnerable areas are more effectively identified during the daytime, when more consistent meteorological conditions exist. However, the potential risk becomes much lower during the nighttime owing to a substantial reduction of the outdoor population.ope

The Antibacterial Assay of Tectorigenin with Detergents or ATPase Inhibitors against Methicillin-Resistant Staphylococcus aureus

Tectorigenin (TTR) is an O-methylated isoflavone derived from the rhizome of Belamacanda chinensis (L.) DC. It is known to perform a wide spectrum of biological activities such as antioxidant, anti-inflammatory, anti-tumor. The aim of this study is to examine the mechanism of antibacterial activity of TTR against methicillin-resistant Staphylococcus aureus (MRSA). The anti-MRSA activity of TTR was analyzed in combination assays with detergent, ATPase inhibitors, and peptidoglycan (PGN) derived from S. aureus. Transmission electron microscopy (TEM) was used to monitor survival characteristics and changes in S. aureus morphology. The MIC values of TTR against all the tested strains were 125 μg/mL. The OD(600) of each suspension treated with a combination of Triton X-100, DCCD, and NaN3 with TTR (1/10 × MIC) had been reduced from 68% to 80%, compared to the TTR alone. At a concentration of 125 μg/mL, PGN blocked antibacterial activity of TTR. This study indicates that anti-MRSA action of TTR is closely related to cytoplasmic membrane permeability and ABC transporter, and PGN at 125 μg/mL directly bind to and inhibit TTR at 62.5 μg/mL. These results can be important indication in study on antimicrobial activity mechanism against multidrug resistant strains

NOVEL TECHNOLOGIES FOR INDOOR AIR CLEANING : PARTICLE AND BIOAGENT REMOVAL

Individuals spend a large amount of time in indoor environments, and hence along with thermal comfort, modern generation HVAC systems have to maintain a high degree of air quality. A brief overview of contaminant particle removal is presented. Recent literature indicates that there will an increased demand for removal of ultrafine particles (nanoparticles) due to their increased potential to cause adverse health effects. Current devices have a minima in collection efficiency in these size ranges. A description of a new technology based on an electrostatic collector enhanced by soft x-ray irradiation is provided. The system is effective for removal of particles and contaminant gases. Along with indoor environments in offices and residential buildings, there is a need for such technologies in car, bus and aircraft cabins; microelectronics processing industry and hospitals

Effect of Polystyrene Latex Addition on Size and Pore Volume of Porous Calcium Oxide Particles Prepared by Spray-Pyrolysis Method and Its Ability for SO2 Retention

In this study, the effects of polystyrene (PS) latex addition on the particle morphology and the pore content of calcium oxide (CaO) were investigated. The CaO particles were prepared using an ultrasonic nebulizer-assisted spray-pyrolysis method with variation of the PS/Ca(NO3)2·4H2O mass ratio in the precursor. Good crystallinity of CaO was obtained at 825°C of synthesis temperature under 2 l/min of nitrogen gas flow, which was confirmed by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). According to scanning electron microscope (SEM) characterization, the CaO particles synthesized with 0 and 25 wt% PS addition had an almost spherical shape with an average size of 1.58 and 1.48 µm, respectively. In addition, macropores were formed in the CaO particles prepared with 25 wt% PS addition that had an average pore diameter of 583.26 nm. Meanwhile, the CaO particles prepared with 75 wt% PS addition had a random shape and an average size of 1.41 µm. The mesopore content was investigated by Barret-Joyner-Halenda (BJH) analysis, which showed improvement of the pore size from 3.45 nm to 5.42 nm for 0 and 25 wt% PS addition, respectively, which is proportional to the pore volume, pore surface area, and the capacity of SO2 retention

Large-eddy simulations of complex aerodynamic flows over multi-element iced airfoils

Large-eddy simulations (LESs) of flows over two types of iced airfoils with three multi-elements are performed to investigate the aerodynamic characteristics and complex interactions between flows generated from slat, main, and flap elements. The two iced airfoils are considered under supercooled large droplet (SLD) and non-SLD conditions. A good agreement of the mean properties between our numerical and previous experimental data demonstrates that our LES method provides an accurate solution of the complex flows around iced airfoils., whereas it is not for unsteady Reynolds-averaged Navier-Stokes (URANS) data that is simulated independently. For the iced airfoils under the SLD and non-SLD conditions, the aerodynamic degradation is found compared to that of a clean airfoil because the separation bubbles (SBs) induced by ice accretion change shear layer (SL) trajectory shed from the slat cusp, leading to a severe reduction in mass flow. Furthermore, we show that the flow interactions near the slat gap play a crucial role in determining the flow characteristics on main and flap elements (e.g., flow separation). Although strong flow interactions are observed for the non-SLD case because of the presence of upwind horn-shaped ice, the smaller gap distance of the SLD case leads to a larger lift loss. The unsteady features of SBs on the upper surfaces of the slat and main elements under the non-SLD condition are characterized by the power spectral density (PSD) of the pressure fluctuations with multiple peaks at low and high frequencies. (C) 2020 Elsevier Masson SAS. All rights reserved