The risk factors of environmental contamination by SARS-CoV-2 are largely unknown. We analyzed 1,320 environmental samples obtained from COVID-19 patients over 1 year. The risk factors for contamination of COVID-19 patients’ surrounding environment were higher viral load in the respiratory tract and shorter duration from symptom onset to sample collection.

Background: The influences of demographics, culture, language, and environmental changes on Mini-Mental State Examination (MMSE) scores are considerable.

Methods: Using a sample of 7452 healthy, community-dwelling elderly Koreans, aged 55 to 94 years, who participated in the four ongoing geriatric cohorts in Korea, we investigated demographic influences on MMSE scores and derived normative data for this population. Geropsychiatrists strictly excluded subjects with cognitive disorders according to the protocol of the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet (CERAD-K) Clinical Assessment Battery (CERAD-K-C).

Results: Education (standardized β = 0.463), age (standardized β = −0.303), and gender (standardized β = −0.057) had significant effects on MMSE scores (p < 0.001). The score of MMSE increase 0.379 point per 1-year education, decrease 0.188 per 1-year older, and decrease 0.491 in women compared to men. Education explained 30.4% of the scores’ total variance, which was much larger than the variances explained by age (8.4%) or gender (0.3%). Accordingly, we present normative data for the MMSE stratified by education (0, 1–3, 4–6, 7–9, 10–12, and ≥ 13 years), age (60–69, 70–79, and 80–89 years), and gender.

Conclusions: We provide contemporary education-, age-, and gender-stratified norms for the MMSE, derived from a large, community-dwelling elderly Korean population sample, which could be useful in evaluating individual MMSE scores.

Bilayer structures consisting of ZrO2-3mol% Y2O3(TZ-3Y) and zirconia-alumina composites as inner (substrate) and outer (coating) layers, respectively, are fabricated using gel-casting for the inner layer and dip-coating for the outer layer in aqueous system. The relatively tough TZ-3Y is used as the inner layer for damage absorption due to its mechanical properties. The mixture ratio of alumina/zirconia slips for dip-coating is 1:9, 2:8, and 3:7 as mole ratio. The processing additives for gel casting, such as dispersant, monomer, dimer, and initiator, are adjusted and optimized by measuring viscosity. From which the solid loading of starting material (TZ-3Y) is determined. The optimum amount of dispersant (D-3019; anionic dispersant agent) for TZ-3Y is 0.7 wt%. The slip pH affects the electric double layer in sols, which causes the different rheological behaviors and solid loadings. The castable solid loading of TZ-3Y is 37 vol%, showing a pseudoplastic rheological behavior. The effect of slip type (different mixture ratio) on sintered body is investigated through hardness (Vickers indentation), microstructure (SEM), and strength (4-point bending tests). Strength of sintered bodies after dip-coating into the slips is higher than that before dip-coating, but hardness is not much different among cases. The effects of thickness in the outer layer on damage resistance and mechanical properties of the bilayer structures are discussed extensively.

The formation of BaCeO3 and its effects on microstructure were studied in sintered/melt-textured Y-Ba-Cu-O oxides containing 5 wt. % CeO2 and various amounts of Y2Ba1Cu1O5. The added CeO2 was converted to fine particles of BaCeO3 near 930 °C, which is the conventional sintering temperature for Y-Ba–Cu-O. Y2Ba1Cu1O5 and CuO are formed as by-products of the reaction between CeO2 and Y1Ba2Cu3O7−y phase. The CeO2 addition reduced the particle size of Y2Ba1Cu1O5 which was trapped in the Y1Ba2Cu3O7−y matrix after the melt-texture growth. During the peritectic decomposition stage of Y1Ba2Cu3O7−y phase into Y2Ba1Cu1O5 and liquid phase, the morphology of the decomposed Y2Ba1Cu1O5 was changed from a blocky shape in the undoped sample to an acicular shape of high anisotropy in the CeO2-added sample. The formation of the highly anisotropic Y2Ba1Cu1O5 particles appears to be responsible for the refinement of Y2Ba1Cu1O5 particle after the melt-texture processing.

In order to investigate microstructural variation by 2-1-1 addition in partially melted Y–Ba–Cu–O, a specimen resulting from 2-1-1 added to 1-2-3 was heat-treated through the peritectic temperature. Microstructure was observed on the directionally solidified region near the interface of the two samples. The 2-1-1 addition results in a homogeneous microstructure where no remnant liquid phase is present. It reduced the 1-2-3 plate thickness, as well as suppressed the formation of microcracks due to the tetragonal-to-orthorhombic phase transition or the thermal contraction during cooling from the peritectic temperature. The formation of microcracks induced by the phase transition seems to be closely related to the process of oxygen diffusion into a sample. We discuss the formation of microcracks in terms of the oxygen diffusion along the plate boundaries and of the thickness of 1-2-3 plates. The decrease in the plate thickness and the fine dispersion of 2-1-1 particles contribute suppression of the formation of microcracks and their propagation.

The CeO2-added Y–Ba–Cu–O oxides were prepared by two different processes, the conventional solid-state reaction process and the partial melt process using powders, to examine the effect of the dopant on microstructure, microhardness, and superconductivity. In the solid-state reacted sample, most of the added CeO2 was converted to a form of BaCeO3, but some might enter into the 1-2-3 phase, resulting in the orthorhombic-to-tetragonal phase transition that accompanied the disappearance of twin structure in 1-2-3 grains. In the partially melted sample, however, the phase change was not observed up to 5 wt. % of CeO2. All the added CeO2 in these samples was consumed to form only BaCeO3 which was finely dispersed in large 1-2-3 grains during the peritectic reaction stage. The zero resistance temperature (Tc) of the solid-state reacted sample gradually decreased with increasing CeO2 content due to the phase change and the formation of BaCeO3, whereas the Tc of the partially melted sample was nearly constant regardless of CeO2 content up to 5 wt. %, owing to the separation of the second phase from the 1-2-3 superconducting phase. Microhardness of the partially melted sample increased with increasing CeO2 content. The strengthening effect appears to come from the composite system where the fine BaCeO3 particles are dispersed in a 1-2-3 matrix.