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A new strategy for the sintering of transparent lanthanum‐doped yttrium oxide was presented. This method is the extension of the well‐accepted two‐step sintering process for the densification of nanomaterials. The samples were firstly sintered at an intermediate temperature T1 (1450°C) in air. Then the temperature decreased quickly to a lower point T2 (900°–1100°C) in air and held for more than 20 h in order to facilitate densification with limited grain growth. Nanocrystalline yttria ceramic with a high relative density was then obtained, which can be further densified at higher temperature T3 (>1700°C) in vacuum. After sintering, transparent yttria doped with 10% lanthanum ceramic was obtained with the grain size around 25 μm without annealing. The samples were densified mainly in air at low temperature, it is more easy for operation. The transmittance at 580 nm is 77%, which was equal or better than that from other sintering method for transparent yttria ceramics.

Objectives To assess the reporting and methodological quality of COVID-19 systematic reviews, and to analyze trends and gaps in the quality, clinical topics, author countries, and populations of the reviews using an evidence mapping approach. Study Design and Setting A structured search for systematic reviews concerning COVID-19 was performed using PubMed, Embase, Cochrane Library, Campbell Library, Web of Science, CBM, WanFang Data, CNKI, and CQVIP from inception until June 2020. The quality of each review was assessed using the Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) checklist and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Results In total, 243 systematic reviews met the inclusion criteria, over 50% of which (128, 52.7%) were from 14 developing countries, with China contributing the most reviews (76, 31.3%). In terms of methodological quality of the studies, 30 (12.3%) were of moderate quality, 63 (25.9%) were of low quality, and 150 (61.7%) were of critically low quality. In terms of reporting quality, the median (interquartile range) PRISMA score was 14 (10–18). Regarding the topics of the reviews, 24 (9.9%) focused on the prevalence of COVID-19, 69 (28.4%) focused on the clinical manifestations, 30 (12.3%) focused on etiology, 43 (17.7%) focused on diagnosis, 65 (26.7%) focused on treatment, 104 (42.8%) focused on prognosis, and 25 (10.3%) focused on prevention. These studies mainly focused on general patients with COVID-19 (161, 66.3%), followed by children (22, 9.1%) and pregnant patients (18, 7.4%). Conclusion This study systematically evaluated the methodological and reporting quality of systematic reviews of COVID-19, summarizing and analyzing trends in their clinical topics, author countries, and study populations.

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Aqueous tape casting of ZrB2 powder with sintering additives was investigated. The dispersion of ZrB2 suspensions in aqueous media was studied and characterized in terms of zeta potential, sedimentation, and rheological measurements. A well‐stabilized suspension with a high solid content (up to 45 vol%) was prepared in the alkaline pH region with 0.4 wt% Lopon 885 as the dispersant. Several suspensions with different compositions of binder and plasticizer were prepared for comparison. Crack‐free green tapes with a maximum thickness of approximately 250 μm were obtained with a binder content of 18–23 wt%. The green tapes had high qualities, such as homogeneity, good flexibility, and a smooth surface. Results showed that the slurries at selected formulations met the needs of the tape‐casting process.

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An ordered dental enamel-like structure of hydroxyapatite (HAp) was achieved through a solution mediated solid-state conversion process with organic phosphate surfactant and gelatin as the mediating agent. Transmission electron microscopy (TEM) tests demonstrated uniform sizes in the obtained apatite nanorods which arranged in parallel to each other along the c-axis and formed organized microarchitectural units over 10 microm in size. The sizes of the synthetic hydroxyapatite nanorods were similar to that observed in enamel from human teeth. The formation and regulation of the orientation and size of HAp nanorods might lead to a better understanding of the biomineralization process for the preparation of high performance biomaterials.