[en] In this study, we developed a procedure for assembling hepatic microstructures into tube shapes using magnetic self-assembly for in vitro 3D micro-tissue fabrication. To this end, biocompatible hydrogels, which have a toroidal shape, were made using the micro-patterned electrodeposition method. Ferrite particles were used to coat the fabricated toroidal hydrogel microcapsules using a poly-L-lysine membrane. The microcapsules were then magnetized with a 3 T magnetic field, and assembled using a magnetic self-assembly process. During electrodeposition, hepatic cells were trapped inside the microcapsules, and they were cultured to construct tissue-like structures. The magnetized toroidal microstructures then automatically assembled to form tube structures. Shaking was used to enhance the assembly process, and the shaking speed was experimentally optimized to achieve the high-speed assembly of longer tube structures. The flow velocity inside the dish during shaking was measured by particle image velocimetry. Hepatic functions were evaluated to check for side-effects of the magnetized ferrite particles on the microstructures. Collectively, our findings indicated that the developed method can achieve the high-speed assembly of a large number of microstructures to form tissue-like hepatic structures. (paper)
Journal
Biomedical Materials (Bristol. Online); ISSN 1748-605X; 
; v. 15(5); [10 p.]
; v. 15(5); [10 p.]
[en] Highlights: • Upwind NOx condition changed the ratio of NO3− and HNO3 being transported. • NOx reduction in high NOx upwind area increased direct long-range transport of NO3−. • Downwind NH3 availability affected additional conversion of transported HNO3 to NO3−. • The cross impact outweighs the direct impact in NH3-rich downwind areas. • Direct NO3− transport increased the overall impact over NH3-poor downwind areas. Emissions reductions in upwind areas can influence the PM2.5 concentrations in downwind areas via long-range transport. However, few studies have assessed the impact of upwind PM2.5 precursor controls on changes in downwind PM2.5 concentrations. In this study, we analyzed the overall impact of PM2.5 precursor emission controls in upwind areas on PM2.5 in downwind areas with two types of impacts: “direct impact” and “cross impact.” The former refers to PM2.5 changes in downwind areas due to the transported PM2.5 itself, whereas the latter represents PM2.5 changes due to reactions between the transported gaseous precursors and intermediates (i.e., HNO3) originating from upwind areas and locally emitted precursors (i.e. NH3) in the downwind areas. As a case study, we performed air quality modeling for Northeast Asia for January 15–17, 2016 by setting China and South Korea as the upwind and downwind areas, respectively. To account for potential spatiotemporal variations in NH3 emissions in downwind areas, we considered two NH3 conditions. When NOx emissions in China were reduced by 35%, in downwind areas the PM2.5 concentrations decreased by 2.2 μg/m3 under NH3-rich conditions, while PM2.5 concentrations increased by 2.3 μg/m3 under NH3-poor conditions. The direct impact increased by 4.0 μg/m3 in both cases due to upwind NOx disbenefit effects. However, the cross impacts led to a PM2.5 decrease of 6.2 μg/m3 under NH3-rich conditions versus a PM2.5 increase of 1.7 μg/m3 under NH3-poor conditions. We noted that PM2.5 concentrations in the downwind areas may not improve unless a cross impact outweighs a direct impact. This may be one of the reasons why South Korea PM2.5 concentrations have not declined despite efforts by China to reduce their PM2.5 precursor emissions.
Journal
[en] Intra-hospital transport is associated with fatal risks for the occupants of an intensive care unit (ICU). Thus, mobile CT is used in ICUs. In this study, two-dimensional equivalent dose distribution data were expanded using the inverse square law of distance to identify the potential exposure of radiologic technologists and public and the maximum number of possible daily CT procedures. The exposure dose at 1.5 m from the isocentre of the mobile CT was 2.260 μSv. Based on the dose limitation (5 mSv/yr for controlled area and 1 mSv/yr for uncontrolled area) as per National Council on Radiation Protection and Measurement report, the number of possible scans per day was 9 for radiologic technologists and 2 for public. When using the radiation shielding partition with a lead equivalent of 0.3 mm Pb, the exposure dose reduced as 0.399 μSv. Therefore, mobile CT can be used in ICUs when appropriate shielding is provided. (authors)
Journal
Radiation Protection Dosimetry; ISSN 0144-8420; ; v. 196(1-2); p. 60-70
; v. 196(1-2); p. 60-70
[en] Highlights: • The impact of the upwind NH3 emission on downwind PM2.5 is highest in spring. • NO3− change leads to an overall PM2.5 change under various NH3 conditions. • Downwind NH3 additionally converts HNO3 originating upwind to NO3−. • Vertical mixing determines the surface and aloft AdjGR even under NH3-rich condition. • The impact of NH3 emission control is similar regardless of the emission uncertainty. Ammonia (NH3) is an important precursor for forming PM2.5. In this study, we estimated the impact of upwind transboundary and local downwind NH3 emissions on PM2.5 and its inorganic components via photochemical grid model simulations. Nine sensitivity scenarios with ±50% perturbations of upwind (China) and/or downwind (South Korea) NH3 emissions were simulated for the year 2016 over Northeast Asia. The annual mean PM2.5 concentrations in the downwind area were predicted to change from −3.3 (−18%) to 2.4 (13%) when the NH3 emissions in the upwind and downwind areas were perturbed by -50% to +50%. The change in PM2.5 concentrations in the downwind area depending on the change in NH3 emissions in the upwind area was the highest in spring, followed by winter. This was mainly attributed to the change in nitrate (NO3-), a secondary inorganic aerosol (SIA) that is a predominant constituent of PM2.5. Since NH3 is mainly emitted near the surface and vertical mixing is limited during the night, it was modeled that the aloft nitric acid (HNO3)-to-NO3- conversion in the morning hours was increased when the NH3 accumulated near the surface during nighttime begins to mix up within the Planetary Boundary Layer (PBL) as it develops after sunrise. This implies that the control of upwind and/or downwind NH3 emissions is effective at reducing PM2.5 concentrations in the downwind area even under NH3 rich conditions in Northeast Asia.
Journal
[en] An optical functional film applicable to various lighting devices is demonstrated in this study. The phase separation of two immiscible polymers in a common solvent was used to fabricate the film. In this paper, a self-organized lens-like structure is realized in this manner with optical OLED functional film. For an OLED, there are a few optical drawbacks, including light confinement or viewing angle distortion. By applying the optical film to an OLED, the angular spectra distortion resulting from the designed organic stack which produced the highest efficiency was successfully stabilized, simultaneously enhancing the efficiency of the OLED. We prove the effect of the film on the efficiency of OLEDs through an optical simulation. With the capability to overcome the main drawbacks of OLEDs, we contend that the proposed film can be applied to various lighting devices. (paper)
Journal
Nanotechnology (Print); ISSN 0957-4484; ; v. 27(7); [9 p.]
; v. 27(7); [9 p.]