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This study investigates the non-Oberbeck–Boussinesq (NOB) Rayleigh–Bénard convection inside a two-dimensional rectangular cavity for a fluid with a high Prandtl number ( Pr = 2547.0 ). The parametric study focuses on the aspect ratio (Γ , 0.3 ≤ Γ ≤ 8 ) dependence of heat transfer and fluid flows on the Rayleigh number (Ra) ranging from 5 × 10 3 to 10 8 and an NOB assumption with a temperature difference ( Δ θ ~ ) of up to 50 K. We numerically find that the critical Ra (Ra c ) for convection onset decreases as Δ θ ~ increases for small Γ , while it increases as Δ θ ~ increases for large Γ . Four flow regimes are classified based on kinetic and thermal energy dissipation rates in the Γ –Ra plane. The aspect ratio dependency of the Nusselt number (Nu), Reynolds number (Re), and top and bottom thermal boundary layer (BL) thicknesses ( λ ¯ h , c θ ) is also investigated under both OB and NOB conditions. It is found that the Γ effect on Re (up to 61%) is more serious than that on Nu (up to 4.5%), while Γ does not obviously affect the generality of the classical NOB effects on scaling exponents of Nu, Re, and λ ¯ h , c θ for fully chaotic regimes. Top–bottom λ ¯ h , c θ asymmetry is confirmed, where the top BL is always thicker than the bottom one, and their ratio is up to 1.8 for Δ θ ~ = 50 K at Ra = 10 8 . Although λ ¯ h θ + λ ¯ c θ increases with an NOB effect enhancement for all aspect ratios, the compensation between λ ¯ h θ and λ ¯ c θ leads to small deviation (up to 7.0%) of λ ¯ h θ + λ ¯ c θ from unity. This contributes to the robustness of Nu because it is confirmed that the NOB effects on Nu are dominated by the change in λ ¯ h θ + λ ¯ c θ . [ABSTRACT FROM AUTHOR]

Hippocampal astrocytes play a pivotal role in hippocampal functions. However, trophic factor deprivation during brain injury or neurodegenerative diseases leads to abnormal functions. C-phycocyanin (C-Pc) is an antioxidant compound derived from Spirulina. C-Pc has been studied as a neuroprotectant against brain damage and diseases, however, its effects on hippocampal astrocytes cultured under trophic factor deprivation are unclear. Presently, serum deprivation lowered the metabolic activities, decreasing NADPH diaphorase activity, and decreased production of superoxide dismutase in astrocytes. These effects were reversed after C-Pc treatment. The upregulated NADPH diaphorase activity in activated astrocytes resulted in the increased production of nitric oxide, which protected the hippocampal astrocytes from the harsh trophic factor-deprived environment. [ABSTRACT FROM AUTHOR]

Microalgal carotenoids are attractive health ingredients, but their production should be optimized to improve cost-effectiveness. Understanding cellular physiology centered on carotenoid synthesis is the prerequisite for this work. Therefore, systematic correlation analyses were conducted among chlorophyll, carotenoids, non-pigmented cell mass, and cell number of Dunaliella salina in a specified condition over a relatively long culture time. First, an integrated correlation was performed: a temporal profile of the carotenoids was correlated with those of other factors, including chlorophyll, non-pigmented cell mass, and cell number. Pearson and Spearman correlation analyses were performed to identify linearity and monotonicity of the correlation, respectively, and then cross-correlation was executed to determine if the correlation had a time lag. Second, to understand the cellular potential of metabolism, the procedure was repeated to provide a data set composed of the specific synthesis rates of the factors or growth rate, which additionally provided kinetic correlations among the constituting components of the cell, excluding the effect of cell number. This systematic approach could generate a blueprint model that is composed of only what it needs, which could make it possible to efficiently control and optimize the process. [ABSTRACT FROM AUTHOR]

Owing to complex configurations and the multi-physics phenomenon in a Redox flow battery (RFB), designing an RFB flow frame through Computational fluid dynamics (CFD) or experimentally requires high design costs. As an alternative approach, a compartment model can be applied to the design of an optimal RFB flow frame. In this study, we developed a pre-design model to estimate the parameters related to the energy efficiency of an RFB. A key factor of the proposed model is applying a classical pipe network theory and an electric circuit analogy to an RFB flow frame and stack. The pre-design model enables an estimation of the total pressure drop, flow rate distribution, and shunt current at the RFB cells or stack. Model-based estimates show good agreement with CFD and experimental results. [ABSTRACT FROM AUTHOR]

We performed numerical simulations of blast wave propagations on surfaces by solving axisymmetric two-dimensional Euler equations. Assuming the initial stage of fireball at the breakaway point after an explosion, we investigated the effect of surface conditions considering surface convex or concave elements and thermal conditions on blast wave propagations near the ground surface. Parametric studies were performed by varying the geometrical factors of the surface element as well as thermal layer characteristics. We found that the peak overpressure near the ground zero was increased due to the surface elements, while modulations of the blast wave propagations were limited within a region for the surface elements. Because of the thermal layer, the precursor was formed in the propagations, which led to the attenuation of the peak overpressure on the ground surface. [ABSTRACT FROM AUTHOR]

Turbulent flow and dispersion characteristics over a complex urban street canyon are investigated by large-eddy simulation using a modified version of the Fire Dynamics Simulator. Two kinds of subgrid scale (SGS) models, the constant coefficient Smagorinsky model and the Vreman model, are assessed. Turbulent statistics, particularly turbulent stresses and wake patterns, are compared between the two SGS models for three different wind directions. We found that while the role of the SGS model is small on average, the local or instantaneous contribution to total stress near the surface or edge of the buildings is not negligible. By yielding a smaller eddy viscosity near solid surfaces, the Vreman model appears to be more appropriate for the simulation of a flow in a complex urban street canyon. Depending on wind direction, wind fields, turbulence statistics, and dispersion patterns show very different characteristics. Particularly, tall buildings near the street canyon predominantly generate turbulence, leading to homogenization of the mean flow inside the street canyon. Furthermore, the release position of pollutants sensitively determines subsequent dispersion characteristics. [ABSTRACT FROM AUTHOR]