On a new method for numerical solution of the Navier-Stokes equations

Summary The method presented in this paper refers to the known system of partial differential equations of Fluid Mechanics, consisting of the continuity equation as well as of the Navier-Stokes equations, and describing unsteady flow of viscous incompressible fluid. In the plane case this system contains three unknown functions, i.e. two velocity components and pressure. At every instant all these functions have to be univalent with respect to space variables. Advantage is taken of this property in order to eliminate pressure from the Navier-Stokes equations. Because integration is applied for this purpose instead of the customary differentiation, the order of the resulting system of equations is not higher in comparison with the original one. Consequently, no need arises for additional boundary conditions.By means of the method of finite differences as well as the method of splines applied to space variables in the system of so obtained equations, which already do not contain pressure, a set of ordinary differential equations is derived-with time as the only independent variable. Two velocity components at every node of the computational mesh represent a set of unknown functions, their initial values being naught. The initial problem so determined has been solved by means of the Runge-Kutta method for the test case represented by the driven cavity problem. Workability of the method has been demonstrated.     

Characterization of Seed,Oil, and Fatty Acid Methyl Esters of an Ethyl Methanesulfonate Mutant of Camelina sativa with Reduced Seed-Coat Mucilage

Camelina sativa L. Crantz (large-seeded false flax) is a promising oilseed crop for the production of edible oil and biodiesel. An ethyl methanesulfonate (EMS) mutant of C. sativa was identified that lacked seed coat mucilage (SCM) using Ruthenium Red (RR) colorimetric staining. Compared with wild-type (WT) plants, the mucilage-defect mutant line (Cs98) had smaller seeds and seeds with significantly less SCM, but exhibited significantly taller plant height. The seed mass and oil content of the seeds of Cs98 were significantly lower than those of WT plants. However, the seeds of Cs98 had significantly higher crude protein and starch contents, but a significantly lower neutral detergent-soluble fiber (NDSF) fraction (pectin) content. Although Cs98 seed contained significantly higher mineral contents for various macro- and microminerals (e.g., Mg, S, Al, Cu, Mn, Fe, and Zn), these large differences did not prevent the Cs98 seed biodiesel from passing all American Society for Testing and Materials (ASTM) standards for macro- and micromineral content and viscosity, pH, and turbidity. Notably, the oil and biodiesel derived from Cs98 had significantly reduced viscosity compared with WT. Water washes of oil derived from WT and Cs98 seed confirmed that the Cs98 contained only 57% of the mucilage content of the WT oil washes. These significantly lower pectic residues are expected to improve the flow characteristics of the resultant oil and require less washing during biodiesel production.     

Chemical aspects of wear of alumina ceramics

In our investigation, the effects of the tribochemically-induced dissolution of alumina ceramics and modulation of near-surface forces (surface charge) within the tribocontact were studied. The wear and friction behaviors of alumina were investigated using a reciprocating sliding test in different chemical environments. The samples for the tests were hemispherical pins and plates of polished alumina, both prepared by a near-net-shaping method.

The sliding tests were conducted in water-based liquids with different pH values or with the addition of a polyelectrolyte to control the surface charge at solid surfaces. The coefficient of friction was continuously recorded during the tests and the wear-loss was subsequently determined for all samples. The results show a significant effect of the chemical agents on the coefficient of friction as well as on the material-removal rate in different aqueous media. The results are discussed in terms of the chemical and electrochemical properties of the materials in the tribocontact.     

The course of the hydrolysis and the reaction kinetics of AlN powder in diluted aqueous suspensions

The reactivity of AlN powder in diluted aqueous suspensions in the temperature range 22–90 °C was investigated in order to better understand and control the process of hydrolysis. The hydrolysis exhibits three interdependent stages: during the induction period (first stage) amorphous aluminum hydroxide gel is formed, followed by the crystallization of boehmite (second stage) and bayerite (third stage). The hydrolysis rate significantly increased with higher starting temperatures of the suspension, but was independent of the starting pH value; however, the pH value of 10 caused the disappearance of the induction period. The kinetics was described using un-reacted-core model, and the chemical reaction at the product-layer/un-reacted-core interface was the rate-controlling step for the second stage of the hydrolysis in the temperature range 22–70 °C, for which the calculated activation energy is 101 kJ/mol; whereas at 90 °C, the diffusion through the product layer became the rate-controlling step.     

Inflammation-Related Changes in Mood Disorders and the Immunomodulatory Role of Lithium

Mood disorders are chronic, recurrent diseases characterized by changes in mood and emotions. The most common are major depressive disorder (MDD) and bipolar disorder (BD). Molecular biology studies have indicated an involvement of the immune system in the pathogenesis of mood disorders, and showed their correlation with altered levels of inflammatory markers and energy metabolism. Previous reports, including meta-analyses, also suggested the role of microglia activation in the M1 polarized macrophages, reflecting the pro-inflammatory phenotype. Lithium is an effective mood stabilizer used to treat both manic and depressive episodes in bipolar disorder, and as an augmentation of the antidepressant treatment of depression with a multidimensional mode of action. This review aims to summarize the molecular studies regarding inflammation, microglia activation and energy metabolism changes in mood disorders. We also aimed to outline the impact of lithium on these changes and discuss its immunomodulatory effect in mood disorders.     

Single step fabrication of polymer/silicate porous composite membranes via water-glass induced phase inversion

Water-glass, a low-cost silica precursor solution, is used to produce mostly skinned, polymer–silicate composite membranes with a porous bulk. We explore primarily Nylon 6-10/formic acid dopes where the polymer solvent is an acid, and polysulfone/DMF dope as an example of a polymer dope based on a non-acidic water-miscible solvent. Elemental distribution of silicon in cross sections suggests compositional uniformity of the formed membranes with in some cases 20 wt. % of silicate load. Membranes formed can be used either as separation media or as precursors for compact polymers reinforced with silicate particles.     

β-TCP coatings on zirconia bioceramics: The importance of heating temperature on the bond strength and the substrate/coating interface

β-tricalcium phosphate (β-TCP) coatings were synthesized on tetragonal zirconia (Y-TZP) discs by heating the apatite coating between 800?°C and 1200?°C. The study results suggest that heating temperature has a strong influence on the coating bond strength and microstructure of the substrate/coating interface. The β-TCP coatings fired at 800?°C and 900?°C exhibited excellent tensile bond strength (～50?MPa) while heating at 1100?°C and 1200?°C led to decreased bond strength (～30?MPa) as the result of substantial structural and microstructural changes: diffusion of Y³⁺ from the zirconia substrate in the coating resulting in partial crystal transformation (t-m) of zirconia, formation of surface uplifts and nanoporosity in zirconia, as well as generation of large residual thermal stresses leading to microcracking of the β-TCP coatings. However, these structural changes did not have any measurable effect on the flexural strength of the bulk zirconia substrates.     

Geographical Differentiation of Greek Extra Virgin Olive Oil from Late-Harvested Koroneiki Cultivar Fruits

Seventy‐four monovarietal olive oil samples belonging to the Koroneiki cultivar were collected from four selected olive oil‐producing regions of Greece (Messinia, Lakonia, Irakleio and Etoloakarnania), during two harvesting periods (2012/2013 and 2013/2014) at the stage of full maturation (maturation index 5–6). Determination of volatile compounds (VC), fatty acid (FA) composition, total phenolic content (TPC) and color parameters was carried out in an effort to classify Koroneiki olive oil samples according to geographical origin, while conventional quality parameters (CQP) were used to characterize the samples. The analytical data were then subjected to statistical analysis using multivariate analysis of variance (MANOVA) and linear discriminant analysis (LDA). The results showed a correct classification rate of 79.7% based on VC analysis, 81.1% based on the combination of VC analysis and FA composition, and 87.8% based on the combination of VC analysis and color parameters.