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Inland lakes are indicators of climate change and environmental deterioration. As a unique ecosystem unit, an inland lake is one of the basic locations for human survival and development. In recent years, with the rapid development of regional society and economy, the ecological environment of inland lakes has been continuously disturbed by human activities under the influence of large-scale water and soil exploitation activities, which have affected the ecological environment of lakes. Therefore, lake ecological restoration and water quality monitoring under the coupled effect of climate change and human activities are the key to lake protection and management. In recent years, remote sensing has played an increasingly important role in the monitoring of the terrestrial water cycle. Remote sensing technology has been applied in many fields, such as water storage, water quality, water level, and hydrodynamics. Furthermore, the explosive growth of remote sensing data applications is driven by the coupling of multisource remote sensing data and the expansion of new modeling technology.

Biochemistry.

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This open access book focuses on cutting-edge construction techniques for deep-sea tunnels. A world leader in construction technology for deep-sea tunnels and large undersea engineering structures, China has in these years completed several world-renowned undersea tunnel projects, such as the undersea tunnel connecting Shenzhen and Zhongshan, and the Shantou Bay undersea tunnel. The nation also boasts mature technology and enviable scientific research achievements in large-scale shield technology and deep-sea soil hydrostatic surveying. This book intends to provide a review of relevant studies on deep-sea tunnel construction for civil engineers around the globe and equip scholars in related fields of research with a deeper insight into this domain through comprehensive analyses of real-world engineering cases and the most up-to-date research results. The topics of this book include but are not limited to the following: 1. Deep-sea survey technology and equipment. 2. Complex load characteristics and numerical simulation technology in the marine environment. 3. Key technology of immersed tube and shield tunnel construction. 4. Deep-sea construction equipment and safety assessment methods. 5. Deep-sea positioning, measurement and control technology.

Underground construction. --- Offshore structures. --- Marine engineering. --- Underground Engineering and Tunnel Construction. --- Offshore Engineering. --- Marine Engineering.

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Zirconia ceramics have become popular in dentistry, due to their superior biocompatibility, excellent mechanical properties (fracture toughness and strength) and high aesthetic potential. In restorative dentistry, 3 mol% yttria-stabilized zirconia polycrystalline (3Y-TZP) ceramics have been widely accepted as a promising material for fabricating dental crowns and more importantly for fixed partial dentures (FPD) in both anterior and stress-bearing posterior area. However, 3Y-TZP ceramics suffer from low-temperature degradation (LTD), i.e. the spontaneous transformation of the tetragonal to monoclinic ZrO2 phase in the presence of water (hydrothermal aging). Hydrothermal aging can result in enhanced wear rates with the release of small zirconia particles in the surrounding environment, roughening of the surface finish, aesthetic degradation, loss of mechanical properties and even catastrophic failure.This doctoral research focuses on understanding the mechanisms and kinetics of hydrothermal aging by processing and investigating different experimental 3Y-TZP ceramics. The aim is to develop aging-resistant 3Y-TZP ceramics without compromising their high strength and fracture toughness, and aesthetics.A linear relationship between the transformed depth and the aging time was observed for all investigated 3Y-TZPs, and the tensile stress accumulation at the transformation front could be primarily responsible for transformation front propagating into the material. The linear kinetics of the transformation propagation was also shown to be more accurate to calculate the apparent activation energy of the aging process and allowed a more straightforward way to estimate the lifetime of 3Y-TZP at body temperature, compared with the conventional aging kinetic parameters obtained from the phase transformation analysis on the surface.Apart from the normally reported factors like grain size, stabilizer type and stabilizer content, the zirconia grain boundaries were found to play a key role in the hydrothermal aging behavior of 3Y-TZP ceramics. Tailoring the composition of the zirconia grain boundaries at the nanometer level by adding only a slight amount of trivalent oxide provided a satisfactory strategy to balance between the aging resistance and the mechanical properties.The use of Y2O3-stabilizer coated ZrO2 starting powder resulted innbsp;combination of higher toughness and aging resistance, as compared to stabilizer co-precipitated starting powder. The grain boundaries were more enriched in Y3+ in Y2O3-coated 3Y-TZPs, indicating the crucial role of the zirconia grain boundary. More clear evidence was obtained by doping 3Y-TZP ceramics with a small amount of trivalent oxides (Al2O3, Sc2O3, Nd2O3 or La2O3) which have a different cation radius (Al3+ (53.5 pm) < Zr4+ (84.0 pm) ~ Sc3+ (87.0 pm) < Y3+ (101.9 pm) < Nd3+ (110.9 pm) < La3+ (116.0 pm). Sc2O3-doped 3Y-TZP degraded fastest, although the ionic radius of Sc3+ was neither the largest nor the smallest. TEM investigation showed that Al3+, Nd3+ and La3+ segregated to the zirconia grain boundaries, whereas Sc3+ did not because of its small mismatch with the host Zr4+ cations. Therefore, cation dopant segregation to the grain boundaries plays a key role in retarding the hydrothermal aging rate of 3Y-TZP ceramics.The hydrothermal stability increased with increasing dopant cation radius (La3+ > Nd3+ > Al3+). It was found that the ionic conductivity (especially grain boundary conductivity) and aging resistance were oppositely influenced by the cation radius of the dopant, which strongly proved the fact that hydrothermal aging is driven by the diffusion of water-derived mobile species through the oxygen vacancies. Accordingly, the depletion of oxygen vacancies at the zirconia grain boundary makes the grain boundary vulnerable to hydrothermal aging. The trivalent cations which have a strong segregation effect at the grain boundary andnbsp;can form strong defect clusters are able to inhibit the mobility of the oxygen vacancies and thereby retard the aging kinetics of 3Y-TZP ceramics. Furthermore, it was observed that the grain growth of tetragonal zirconia can be limited by the addition of larger cations segregating at the zirconia grain boundary.Although large trivalent dopant cations with a strong segregation to the ZrO2 grain boundary are preferred to design hydrothermally stable and highly-translucent 3Y-TZP ceramics, the amount of the trivalent dopant was critical. There was an optimum amount resulting in the highest aging resistance of 3Y-TZPs in the case of Al2O3 (optimum 0.25 wt.%), Nd2O3 (optimum 0.4-0.6 mol%) and La2O3 (optimum 0.2-0.4 mol% ) dopant. A higher dopant content on the contrary could form secondary phases or bimodal microstructure, reducing the aging resistance or translucency.At last, the introduction of 0.2 mol% La2O3 in conventional Al2O3-doped 3Y-TZP resulted in a unique combination of high translucency (42% increase compared to conventional 0.25 wt.% alumina-doped 3Y-TZP) and superior hydrothermal stability (no transformation up to 120 h of hydrothermal aging at 134 °C), while retaining the excellent mechanical properties (fracture toughness and strength).

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Pure sciences. Natural sciences (general)