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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2007.10.003 Byline: Wonho Yang (a), Jongryeul Sohn (b), Jihwan Kim (b), Busoon Son (c), Jinchul Park (d) Abstract: Since the majority of schools are housed in buildings dating from the 1960s and 1970s, a comprehensive construction and renovation program of school buildings has been carried out to improve the educational conditions in Korea. However, classrooms and computer rooms, with pressed wood desks, chairs and furnishings, as well as construction materials, might have negative effects on the indoor air quality. Furthermore, most schools have naturally ventilated classrooms. The purpose of this study was to characterize the concentrations of different indoor air pollutants within Korean schools and to compare their indoor levels within schools according to the age of school buildings. Indoor and outdoor air samples of carbon monoxide (CO), carbon dioxide (CO.sub.2), particulate matter (PM.sub.10), total microbial count (TBC), total volatile organic compounds (TVOCs) and formaldehyde (HCHO) were obtained during summer, autumn and winter from three sites; a classroom, a laboratory and a computer classroom at 55 different schools. The selection of the schools was based on the number of years since the schools had been constructed. The problems causing indoor air pollution at the schools were chemicals emitted by building materials or furnishings, and insufficient ventilation rates. The I/O ratio for HCHO was 6.32 during the autumn, and the indoor HCHO concentrations (mean=0.16ppm) in schools constructed within 1 year were significantly higher than the Korean Indoor Air Standard, indicating that schools have indoor sources of HCHO. Therefore, increasing the ventilation rate by means of a mechanical system and the use of low-emission furnishings can play key roles in improving the indoor air quality within schools. Author Affiliation: (a) Department of Occupational Health, Catholic University of Daegu, Hayang-eup, Gyeongsan-si, Kyongbuk 712-702, South Korea (b) Department of Environmental Health, Korea University, Seoul, South Korea (c) Department of Environmental Health, Soonchunhyang University, Chungnam, South Korea (d) School of Architecture, Chungang University, Seoul, South Korea Article History: Received 15 March 2007; Revised 20 September 2007; Accepted 12 October 2007

The morphological and mechanical characteristics of red blood cells (RBCs) largely vary depending on the occurrence of hematologic disorders. Variations in the rheological properties of RBCs affect the dynamic motions of RBCs, especially their rotational behavior. However, conventional techniques for measuring the orientation of biconcave-shaped RBCs still have some technical limitations, including complicated optical setups, complex post data processing, and low throughput. In this study, we propose a novel image-based technique for measuring 3D position and orientation of normal RBCs using digital in-line holographic microscopy (DIHM) and artificial intelligence (AI). Formaldehyde-fixed RBCs are immobilized in coagulated polydimethylsiloxane (PDMS). Holographic images of RBCs positioned at various out-of-plane angles are acquired by precisely manipulating the PDMS-trapped RBC sample attached to a 4-axis optical stage. With the aid of deep learning algorithms for data augmentation and regression analysis, the out-of-plane angle of RBCs is directly predicted from the captured holographic images. The 3D position and in-plane angle of RBCs are acquired by employing numerical reconstruction and ellipse detection methods. Combining these digital image processing techniques, the 3D positional and orientational information of each RBC recorded in a single holographic image is measured within 23.5 and 3.07 s, respectively. The proposed AI-based DIHM technique that can extract the 3D position, orientation, and morphology of individual RBCs would be utilized to analyze the dynamic translational and rotational motions of abnormal RBCs with hematologic disorders in shear flows through further research. • AI-based analysis of out-of-plane angles of RBCs was demonstrated. • 3D positions and in-plane angles of RBCs were measured using a DIHM technique. • 3D positions and orientations of RBCs recorded in a single hologram were measured. • This technique has a simpler optical setup and higher throughputs than others. • It would be utilized to analyze 3D dynamics of RBCs flowing in a microchannel. [ABSTRACT FROM AUTHOR]

Cobalt hexacyanoferrate (CoHCF) suffers from low rate capability and lifespan because of the dissolution and structural instability of Co during cycling. A smaller active material can relieve the stress caused by volume change during cycling and enable shorter transport pathways. Here, particle size reduction is performed by reducing the mixing time or citrate concentration in the coprecipitation reaction to improve the rate capability and lifespan of CoHCF. The reduced mixing time produces smaller particles with enlarged active sites, thus improving the capacity. Upon coprecipitation at a low citrate concentration, particle precipitation at reduced sizes is achieved by preferential nucleation versus growth. Although lowering the citrate concentration enlarges the external surface area, the reduced redox-active Fe degrades the capacity. All CoHCF samples with small sizes achieved enhance rate capability and stability. In particular, the sample synthesized with a short mixing time (0 h) achieve a specific capacity of 122 mAh g−1 with improved rate capability (79.4%) and stability (79.3%) over 500 cycles. Structural distortions are relaxed because of the shortened transport pathways and relieved distortion owing to particle size reduction. This study paves the approach for fast rechargeable and long-lasting aqueous Na-ion batteries using CoHCF electrodes. [Display omitted] • A decreased mixing time or citrate concentration yielded smaller CoHCF particles. • The capacity, rate capability, and lifespan were improved with shorter mixing times. • The low citrate ion concentration increased Fe vacancies and decreased the capacity. • Fe vacancies limited Na access in the lattice, thus improving structural stability. • The reduced CoHCF particle size improved rate capability and lifespan. [ABSTRACT FROM AUTHOR]

The flexural resistance of fiber reinforced cementitious composites (FRCCs) under biaxial condition was investigated by using two different types of biaxial bending test methods: the biaxial flexural test (BFT) and the centrally loaded round panel test (RPT). The flexural responses of FRCCs under biaxial condition were then compared with those of FRCCs under uniaxial condition; i.e. four-points bending test (4PBT). The test results, including the equivalent biaxial strength and normalized energy absorption capacity of the RPT, were found to be clearly higher than those of the BFT, and completely different cracking behavior was observed between the two biaxial test methods; the BFT generated numerous randomly distributed micro-cracks at the bottom of specimens, whereas the RPT mostly showed three major cracks, with minor radial cracks around them. In addition, the equivalent flexural tensile strength and normalized energy absorption capacity of the FRCCs under biaxial condition were found to be higher than those under uniaxial condition. The energy absorption capacity and the ratio of flexural tensile strength to the direct tensile strength of FRCCs are dependent on the stress state. [ABSTRACT FROM AUTHOR]