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Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems with varying socio-economic development statuses and different levels and histories of eutrophication. Although these coastal systems share common features of eutrophication, site-specific characteristics are also substantial, depending on the regional environmental setting and level of social-economic development along with policy implementation and management. Nevertheless, ecosystem recovery generally needs greater reduction in pressures compared to that initiated degradation and becomes less feasible to achieve past norms with a longer time anthropogenic pressures on the ecosystems. While the qualitative causality between drivers and consequences is well established, quantitative attribution of these drivers to eutrophication and hypoxia remains difficult especially when we consider the social economic drivers because the changes in coastal ecosystems are subject to multiple influences and the cause–effect relationship is often non-linear. Such relationships are further complicated by climate changes that have been accelerating over the past few decades. The knowledge gaps that limit our quantitative and mechanistic understanding of the human-coastal ocean nexus are identified, which is essential for science-based policy making. Recognizing lessons from past management practices, we advocate for a better, more efficient indexing system of coastal eutrophication and an advanced regional earth system modeling framework with optimal modules of human dimensions to facilitate the development and evaluation of effective policy and restoration actions.
Grain refinement has been applied to enhance the materials strength for miniaturization and lightweight design of nuclear equipment. It is critically important to investigate the low-cycle fatigue (LCF) properties of grain refined 316LN austenitic stainless steels for structural design and safety assessment. In the present work, a series of fine-grained (FG) 316LN steels were produced by thermo-mechanical processes. The LCF properties were studied under a fully reversed strain-controlled mode at room temperature. Results show that FG 316LN steels demonstrate good balance of high strength and high ductility. However, a slight loss of ductility in FG 316LN steel induces a significant deterioration of LCF life. The rapid energy dissipation in FG 316LN steels leads to the reduction of their LCF life. Dislocations develop rapidly in the first stage of cycles, which induces the initial cyclic hardening. The dislocations rearrange to form dislocations cell structure resulting in cyclic softening in the subsequent cyclic deformation. Strain-induced martensite transformation appears in FG 316LN stainless steels at high strain amplitude (Δε/2 = 0.8%), which leads to the secondary cyclic hardening. Moreover, a modified LCF life prediction model for grain refined metals predicts the LCF life of FG 316LN steels well.
We performed the cohort study to evaluate the association between BMI, high-sensitivity C-reactive protein (hs-CRP) and the conversion from metabolically healthy to unhealthy phenotype in Chinese adults.
Metabolically healthy was defined as participants without history of metabolic diseases and with normal fasting blood glucose level, glycated Hb A1c level, blood pressure, lipid profile, serum uric acid level and liver ultrasonographic findings at baseline. Participants were either classified into normal weight (18·5 ≤ BMI < 24·0 kg/m2) and overweight (BMI ≥ 24·0 kg/m2) based on baseline BMI, or low (<1 mg/l) and high (≥1 mg/l) groups based on baseline hs-CRP. The conversion from metabolically healthy to unhealthy phenotype was deemed if any of the metabolic abnormalities had been confirmed twice or more during 5 years of follow-up.
Included were 4855 (1942 men and 2913 women, aged 36·0 ± 8·9 years) metabolically healthy Chinese adults. We identified 1692 participants who converted to metabolically unhealthy phenotype during the follow-up. Compared with their counterparts, the adjusted hazards ratio of the conversion was 1·19 (95 % CI 1·07, 1·33) for participants with overweight, while it was 1·15 (95 % CI 1·03, 1·29) for those with high hs-CRP level (≥1 mg/l). Further adjustment of hs-CRP did not materially change the association between BMI and the conversion. However, the association between hs-CRP and the conversion was not significant after further adjustment of BMI. The sensitivity analysis generated similar results to main analysis.
BMI was associated with the risk of the conversion from metabolically healthy to unhealthy status in Chinese adults.
This article is to discuss the bilinear and linear immersed finite element (IFE) solutions generated from the algebraic multigrid solver for both stationary and moving interface problems. For the numerical methods based on finite difference formulation and a structured mesh independent of the interface, the stiffness matrix of the linear system is usually not symmetric positive-definite, which demands extra efforts to design efficient multigrid methods. On the other hand, the stiffness matrix arising from the IFE methods are naturally symmetric positive-definite. Hence the IFE-AMG algorithm is proposed to solve the linear systems of the bilinear and linear IFE methods for both stationary and moving interface problems. The numerical examples demonstrate the features of the proposed algorithms, including the optimal convergence in both L2 and semi-H1 norms of the IFE-AMG solutions, the high efficiency with proper choice of the components and parameters of AMG, the influence of the tolerance and the smoother type of AMG on the convergence of the IFE solutions for the interface problems, and the relationship between the cost and the moving interface location.
This article extends the finite element method of lines to a parabolic initial boundary value problem whose diffusion coefficient is discontinuous across an interface that changes with respect to time. The method presented here uses immersed finite element (IFE) functions for the discretization in spatial variables that can be carried out over a fixed mesh (such as a Cartesian mesh if desired), and this feature makes it possible to reduce the parabolic equation to a system of ordinary differential equations (ODE) through the usual semi-discretization procedure. Therefore, with a suitable choice of the ODE solver, this method can reliably and efficiently solve a parabolic moving interface problem over a fixed structured (Cartesian) mesh. Numerical examples are presented to demonstrate features of this new method.
Isothermal sections at 1100 and 1500 °C were determined by X-ray powder diffraction method to reveal stable phases and chemical pathways in the Co–Si–C system. There is no ternary compound present in either isothermal. Cobalt silicides are formed in the Co-rich region at temperatures lower than those in the Si-rich region.
CoSi2 reacts with carbon to form CoSi and SiC at 1500 °C, and
and CoSi are more stable in equilibrium with carbon. The results are also discussed in terms of thermodynamics and binding energy of the reacting substances.
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