Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

Structure changes in nickel on silicon nano-layers under vacuum ultraviolet irradiation

The structure changes in nickel-on-silicon systems due to vacuum ultraviolet irradiation (VUV) have been studied using the X-ray reflectometry. An ultra-thin (1 to 2 nm) layer (of the density ρ = 3.2 to 3.4 g/cm³ at VUV wavelength λ = 120 nm and 2.1 to 2.6 g/cm³ at λ = 180 nm) has been revealed to be formed at the nickel film surface under irradiation. The nickel films themselves remain unchanged both in thickness and density after a short-time VUV irradiation. It has been supposed that the surface layer formation is a result of the VUV interaction with the silicon substrate, silicon nitride Si₃N₄ being formed at λ = 120 nm while oxide SiOₓ at λ = 180 nm.Методом рентгеновской рефлектометрии исследованы изменения структуры никелевых пленок различной толщины на кремниевых подложках при облучении вакуумным ультрафиолетом. Обнаружен тончайший (1-2 нм) слой (с плотностью ρ = 3,2 ÷ 3,4 г/см³ при λ = 120 нм и ρ = 2,1 ÷ 2,6 г/см³ при λ = 180 нм), возникающий на поверхности пленок никеля в результате ВУФ облучения. При этом слой никеля по плотности и толщине заметно не изменялся. Выдвинуто предположение, что образующийся на поверхности слой является результатом взаимодействия ВУФ с кремниевой подложкой, причем в случае ВУФ с λ = 120 нм образуется нитрид кремния Si₃N₄, а в случае λ = 180 нм образуется оксид кремния SiOₓ.Методом рентгенiвської рефлектометрiї дослiджено змiнення структури нiкелевих плiвок рiзної товщини на кремнiйових пiдкладках пiдчас опромiнювання вакуумним ультрафiолетом. Виявлений надтонкий (1-2 нм) шар (з густиною ρ = 3,2 ÷ 3,4 г/см³ при λ = 120 нм та ρ = 2,1 ÷ 2,6 г/см³ при λ = 180 нм), який утворюється на поверхнi плiвок нiкелю в результатi ВУФ опромiнення. При цьому шар нiкелю за густиною i товщиною помiтно не змiнювався. 3роблено припущення, що шар, який утворюється на поверхнi, є результатом взаємодiї ВУФ з кремнiйовою пiдкладкою, причому у випадку ВУФ з λ = 120 нм утворюється нiтрид кремнiю Si₃N₄, а у випадку λ = 180 нм створюється оксид кремнiю SiOₓ

The role of beneficial bacteria wall elasticity in regulating innate immune response

Background: Probiotics have great potential to contribute to development of healthy dietary regimes, preventive care, and an integrated approach to immunity-related disease management. The bacterial wall is a dynamic entity, depending on many components and playing an essential role in modulating immune response. The impact of cell wall elasticity on the beneficial effects of probiotic strains has not been sufficiently studied. The aim was to investigate the effect of lactic acid bacteria (LAB) and bifidobacteria strains on phagocytic system cells (macrophages) as related to bacterial wall elasticity, estimated using atomic force microscopy (AFM). Methods: We conducted studies on Balb/c line mice 18\u201320 g in weight using lyophilized strains of LAB\u2014Lactobacillus acidophilus IMV B-7279, Lactobacillus casei IMV B-7280, Lactobacillus delbrueckii subsp. bulgaricus IMV B-7281, and bifidobacteria\u2014Bifidobacterium animalis VKL and Bifidobacterium animalis VKB. We cultivated the macrophages obtained from the peritoneal cavity of mice individually with the strains of LAB and bifidobacteria and evaluated their effect on macrophages, oxygen-dependent bactericidal activity, nitric oxide production, and immunoregulatory cytokines. We used AFM scanning to estimate bacterial cell wall elasticity. Results: All strains had a stimulating effect on the functional activity of macrophages and ability to produce NO/NO2 in vitro. Lactobacilli strains increased the production of IL-12 and IFN-\u3b3 in vitro. The AFM demonstrated different cell wall elasticity levels in various strains of LAB and bifidobacteria. The rigidity of the cell walls among lactobacilli was distributed as follows: Lactobacillus acidophilus IMV B-7279 > Lactobacillus casei IMV B-7280 > Lactobacillus delbrueckii subsp. bulgaricus IMV B-7281; among the strains of bifidobacteria: B. animalis VKB > B. animalis VKL. Probiotic strain survival in the macrophages depended on the bacterial cell wall elasticity and on the time of their joint cultivation. Conclusion: LAB and bifidobacteria strains stimulate immune-modulatory cytokines and active oxygen and nitrogen oxide compound production in macrophages. Strains with a more elastic cell wall according to AFM data demonstrated higher resistance to intracellular digestion in macrophages and higher level of their activation. AFM might be considered as a fast and accurate method to assess parameters of probiotic strain cell wall to predict their immune-modulatory properties