Abstract. In this paper, we study stochastic differential equations with two well-separated time scales. We prove that the rate of strong convergence to the averaged effective dynamics is of order O(ε 1/2 ) , where ε ≪ 1 is the parameter measuring the disparity of the time scales in the system. The convergence rate is shown to be optimal through examples.
We report a biomimetic mineralization of hydroxyapatite induced by poly-dopamine-functionalized reduced graphene oxide (RGO-PDA). Graphene oxide was first simultaneously reduced and surface functionalized by one-step oxidative polymerization of dopamine. The resultant RGO-PDA was further used as a bioinspired surface to mimic the mineralization of hydroxyapatite during bone formation. MC3T3-E1 cells were cultured on the RGO-PDA substrates to observe various cellular activities and hydroxyapatite mineralization. The MC3T3-E1 cells on RGO-PDA substrates show higher cellular activities such as proliferation, adhesion, and osteogenic differentiation over the bare glass and graphene oxide substrates. Those results suggest the potentials of using RGO-PDA as osteogenesis-promoting scaffolds for successful applications in bone tissue regeneration.
In this paper, a spectral method is formulated as a numerical solution for the stochastic Ginzburg-Landau equation driven by space-time white noise. The rates of pathwise convergence and convergence in expectation in Sobolev spaces are given based on the convergence rates of the spectral approximation for the stochastic convolution. The analysis can be generalized to other spectral methods for stochastic PDEs driven by additive noises, provided the regularity condition for the noises.
As a tool that can effectively support ecosystem management, ecological risk assessment is closely related to the sustainable development of ecosystems and human well-being and has become an active area of research in ecology, geography and other disciplines. Taking Dujiashi Gully for the study of gully loess erosion, a comprehensive risk assessment system for identifying risk probability, sensitivity and impairment was established. The spatial distribution of comprehensive ecological risk was analyzed, the ecological risk management categories were simultaneously delineated based on the risk dominant factor and the risk management strategies were formulated in loess regions. The results were as follows: (1) the spatial differences in comprehensive ecological risk were significantly different in the research area. The regions with extremely high and high risk were mainly located in gully areas and secondary erosion gullies, which are in 28.02% of study area. The extremely low-risk areas covered 1/3 of the study area and were mainly distributed to the northwest and south of the study area, where hills are widely spaced. (2) The combined analysis of ecological risk and terrain found that the elevation decreased first and then rose but the comprehensive ecological risk increased first and then decreased from north to south. Comprehensive ecological risk and terrain generally showed an inverse relationship. (3) The study area was divided into four types of risk management categories. Risk monitoring zones, habitat recovery zones, monitoring and recovery zones and natural regulation zones encompass 14.84%, 12.44%, 26.47% and 46.25% of the study area, respectively. According to four types of risk management categories, different risk reduction measures were designed to improve regional sustainable development capacity. Risk identification and risk management categories based on comprehensive ecological risk model can design a sustainable development path for social ecosystem and local farmers and provide a method for sustainable development for similar gully landscapes.
The aim of this research was to investigate the antioxidant and anti-apoptotic activities of Potentilla anserina polysaccharide (PAP) on kidney damage induced by cadmium (Cd) in vitro and in vivo. PAP has been suggested to have anti-oxidation, anti-apoptosis, immunoregulation, antimicrobial, antitussive, and expectorant abilities. In this study, PAP was extracted and the major components of PAP were analyzed. It was shown that PAP pretreatment remarkably improved redox homeostasis, both in human embryonic kidney 293 (HEK293) cells and in BALB/c mice. Administration of PAP attenuated the mitochondrial dysfunction, degeneration, and fibrosis of kidney induced by Cd. Furthermore, PAP exhibited anti-apoptotic activity, which involved regulating both the mitochondria-mediated intrinsic apoptotic pathway and the death receptor-initiated extrinsic pathway. These results suggest that PAP is a potential therapeutic agent for Cd-induced nephrotoxicity.
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