Methane adsorption onto silicas with various degree of hydrophobicity

The methane adsorption onto a hydrated surface of hydrophobic silica AM1 alone and impregnated by arginine, and silica gel Si-100 has been studied using low-temperature 1H NMR spectroscopy. It has been shown that the methane adsorption onto the AM1 surface depends on the degree of hydration and pretreatment type. The maximum adsorption (up to 80 mg/g) is observed for a sample hydrated after complete drying. It has been established that the adsorption is determined by a number of clusters of bound water of small radii. Based on a shape of the temperature dependence of the adsorption, it has been assumed that not only physical adsorption occurs, but also the quasi-solid methane hydrates are formed. It has been established that the amount of methane adsorbed onto a surface of a composite system AM1/arginine under isobaric conditions increases by tens of times (from 0.5 to 80 mg/g) in the presence of pre-adsorbed water pre-adsorbed at the surface. Probable mechanisms of the methane adsorption are physical adsorption on a surface, condensation in narrow voids between silica nanoparticles and nano-scaled (1-10 nm) water clusters, and the formation of solid (clathrate) methane hydrates. Water, adsorbed at a surface in a wide range of hydration, forms various clusters. This water is mainly strongly associated and characterized by chemical shifts in the range dH = 4-6 ppm. The hydrate structures with methane/water are quite stable and can exist even in the chloroform medium. However, in this case, a part of water transforms into a weakly associated state and it is observed at dH = 1.5-2 ppm.

Effect of the water-soluble cholesterol-methyl-β-cyclodextrin complex on the development of pulmonary edema with an analysis of the osmotic resistance of erythrocytes in rats

Introduction. Methyl-β-cyclodextrin is a potent acceptor of cellular membrane cholesterol and, at the same time, used as a solubilizer, which makes it a potential target for targeted delivery of hydrophobic compounds.Aim. To assess the effect of administration of methyl-β-cyclodextrin containing cholesterol on the degree of lung hydration and osmotic resistance of erythrocytes against the background of pulmonary edema in adult rats caused by the administration of mezaton.Materials and methods. We investigated the degree of hydration of the lungs by the value of the pulmonary coefficient and their dry residue. Osmotic resistance of erythrocytes were assessed by the intensity of their hemolysis in a series of hypotonic sodium chloride solutions in adult male Wistar rats (220±40 g) of the control group (intact, n=10) and two experimental groups with pulmonary edema caused by the administration of mezaton (n=10) and with the subsequent introduction of a water-soluble complex cholesterol-methyl-β-cyclodextrin against the background of the development of pulmonary edema (n=10). We used additional criteria for assessing the osmotic resistance of erythrocytes: minimum resistance – the concentration of sodium chloride solution, at which the first “weak” erythrocytes begin to hemolyze; maximum resistance is the concentration of sodium chloride solution at which all or almost all erythrocytes hemolyzed.Results. The introduction of mezaton led to the development of pronounced hemolysis and hydration of the lungs with the development of their edema and a narrowing of the range of minimum and maximum osmotic resistance of erythrocytes. The introduction of a complex of cholesterol with methyl-β-cyclodextrin after edemogenic exposure led to a decrease in the severity of pulmonary edema, determined by a decrease in the pulmonary coefficient and an increase in the dry residue, and to an increase in the osmotic resistance of erythrocytes with an expansion of the range of their minimum and maximum osmotic resistance.Conclusion. The introduction of a water-soluble complex of cholesterol with methyl-β-cyclodextrin against the background of the development of hemodynamic pulmonary edema significantly reduced the degree of hydration of the lungs, which combined with an increase in the osmotic resistance of erythrocytes.

Determining the properties of chia seed meal gel

Potential areas of using chia seeds meal as part of mincemeat semi-finished products were substantiated. The modern stage of development of the food industry involves the expansion of the range of natural functional ingredients that improve the organoleptic characteristics of finished products and provide consumers with "healthy" food. This causes the use of new ingredients in the meat processing industry for producing and devising products. The relationship between the indicators of emulsifying capacity, emulsion resistance, and the degree of hydration of chia meal was determined experimentally. It was found that the ability of chia meal to absorb and retain water and fat molecules in the emulsion composition decreased proportionally to a decrease in its concentration in the composition of hydrated samples. The existence of non-polar side chains of amino acids that get bound to fat molecules contributes to an increase in the indicators of emulsifying capacity and emulsion stability during heat treatment (70±2 °C) and after pre-freezing on average by 7–8.7 % and by 16–18.8 %, respectively. Analysis of effective viscosity of the dispersed system of chia seeds meal indicates that in the area of a higher concentration, the viscous-elastic and solid-like behavior of the suspension depends on dynamic changes in the volume of the phase of particles. Heating the experimental samples to a temperature of 70±2 °C in the center leads to a maximum increase in viscosity of the formed dispersions. When studying the effect of the processes of freezing on the properties of the studied systems, the cryoprotective properties for the proposed additives were detected. The obtained data indicate the thermal stabilization of the proposed additive, the ability to form a microgel structure in the finished product, and retain moisture during heat treatment of semi-finished products.

The Development of a New Phosphogypsum-Based Construction Material: A Study of the Physicochemical, Mechanical and Thermal Characteristics

Phosphogypsum (PG) is a waste (or by-product) of the production of phosphoric acid, a basic constituent in the manufacturing of modern fertilizers. The annual production of phosphogypsum in Tunisia is currently estimated to be 10 million tons. Its storage in slag in close proximity to production plants generates pollution problems; however, valorization may be a solution. The present paper proposes a simple process for the valorization of this by-product into a construction material. Several physicochemical characterizations are used to prove the characteristics of samples. The chemical composition shows that PG is a gypsum compound with several impurities. The morphological analyses show that the powder materials are mesoporous with a lower specific area. The structural characterizations show that these solids play the role of a water pump as the degree of hydration changes from 2 to 0 and vice versa, depending on the temperature. Mechanical and thermal analyses show that the prepared formulation is brittle and insulating, which presents opportunities for it to be used as a decoration material.

The Thermodynamics of Copper (II) and Nickel (II)- Diamine Complex Formation in Aqueous Solution

<p>This work describes the accurate measurement of the thermodynamic functions Delta G degree and Delta H degree for the step-wise coordination equilibria between each of the ions H+, Ni2+, Cu2+, and, a series of C1-substituted 1,2-diaminoethanes in aqueous solution. The study Involved. (a) The construction of a sensitive constant temperature environment calorimeter for measuring the enthalpy changes in the complex-formation reactions, (b) The rigorous calibration of an electrode system, incorporating a glass electrode, for the direct potentiometric measurement of equilibrium hydrogen ion concentrations in the solutions containing complex ions. The thermodynamic functions Delta G degree and Delta H degree led to accurate Delta S degree values for the step-wise complex-formation reactions. The thesis considers the contribution of the entropy of ligation to the stability of complex ions. The molar entropies of the complex ions have been calculated and their values considered with respect to the coordination number and the possible structure, degree of hydration and steric properties of the ions.</p>

Surface-Functionalized Nanocelluloses as Viscosity-Modifying Agents in Engineered Cementitious Composites

This study investigated the feasibility of using nanofibrilliated celluloses (CNF) (0.1% by weight of binder materials) with three oxidation degrees, no oxidation (NCNF), low oxidation (LCNF), and high oxidation (HCNF), as a viscosity-modifying agent (VMA) to develop polyethylene fiber (PE)-engineered cementitious composites (ECC). Attenuated total reflection-Fourier transform infrared (ATR-FTIR), dynamic light scattering (DLS), and zeta potential were performed to characterize the properties of the CNF with different oxidation degrees. More stable CNF suspensions could be obtained due to the increasing oxidation degree. Rheology tests showed that CNF replacing VMA could modify the plastic viscosity and yield stress of the fresh matrices. With increasing the oxidation degree of CNF, a significant enhancement was seen for the rheological parameters. It was conducted that CNF could increase the compressive strength, the tensile stress, the nominal flexural strength, and the fracture toughness compared with ECC using VMA, and much higher oxidation degrees yielded higher enhancements (HCNF &gt; LCNF &gt; NCNF). ECC using CNF to replace VMA also achieved ultra-high ductility behavior with the tensile strain of over 8% and the saturated multiple cracking pattern. These finds were supplemented by thermal gravimetric analysis (TGA), which showed that the degree of hydration increased with increasing CNF surface oxidation degree. Additionally, the morphology images of PE fibers were observed by scanning electron microscope (SEM).

The Thermodynamics of Copper (II) and Nickel (II)- Diamine Complex Formation in Aqueous Solution

<p>This work describes the accurate measurement of the thermodynamic functions Delta G degree and Delta H degree for the step-wise coordination equilibria between each of the ions H+, Ni2+, Cu2+, and, a series of C1-substituted 1,2-diaminoethanes in aqueous solution. The study Involved. (a) The construction of a sensitive constant temperature environment calorimeter for measuring the enthalpy changes in the complex-formation reactions, (b) The rigorous calibration of an electrode system, incorporating a glass electrode, for the direct potentiometric measurement of equilibrium hydrogen ion concentrations in the solutions containing complex ions. The thermodynamic functions Delta G degree and Delta H degree led to accurate Delta S degree values for the step-wise complex-formation reactions. The thesis considers the contribution of the entropy of ligation to the stability of complex ions. The molar entropies of the complex ions have been calculated and their values considered with respect to the coordination number and the possible structure, degree of hydration and steric properties of the ions.</p>

Filaggrin: from history of discovery to clinical usage (literature review)

The article is of an overview nature and contains up-to-date information about one of the main factors in the violation of the skin barrier, filaggrin dysfunction, which is a component of the natural moisturizing factor. The data on the leading role of the filaggrin defect in the pathogenesis of a number of dermatoses make it an attractive target for the creation of topical dermatocosmetics in order to compensate for its deficiency. The first and only registered emollient with a modulator of filaggrin activity from unsaponifiable fractions of vegetable oils is filagrinol, which stimulates the maturation of profilaggrin by activating ATPases involved in dephosphorylation of profilaggrin and inducing the incorporation of histidine into the granular layer [30]. It is expected that thanks to plant lipids this formula enhances the skin’s ability to renew, significantly slowing down the aging process and restores the skin’s water-holding capacity, thereby normalizing the degree of hydration.

Performance Parameter Analysis of Magnesia Based Cement Products – A Review

Magnesium oxide (MgO) based cements finds its way active in current researches where diverse range of applications and characteristics such as production process, reactivity and physical properties are essentially focus with the perception of individual expansion objectives. In general, relativity between distinctive MgO characteristics is examined in conjunction with the impact of MgO embodiment on the resources of cementitious materials is further considered. MgO is a key to develop the construction industry thereby mechanical strength and durability performance of cement paste, adhesive and concrete composites impose of MgO needs to be explored. Subsequently, this research paper explicitly defines the investigation of MgO cement composites in terms of compressive and flexural behavior, toughness, tensile and durability performances, flexibility, water susceptibility, porosity, carbonation, chloride ion diffusion, shrinkage and degree of hydration. In this regard, to application of magnesia-based cement products is influenced by various factors such as raw material, composition, performance. The review provides a detailed information of current research available related to magnesia-based cement products based on its properties.

What Does Time-Dependent Fluorescence Shift (TDFS) in Biomembranes (and Proteins) Report on?

The organization of biomolecules and bioassemblies is highly governed by the nature and extent of their interactions with water. These interactions are of high intricacy and a broad range of methods based on various principles have been introduced to characterize them. As these methods view the hydration phenomena differently (e.g., in terms of time and length scales), a detailed insight in each particular technique is to promote the overall understanding of the stunning “hydration world.” In this prospective mini-review we therefore critically examine time-dependent fluorescence shift (TDFS)—an experimental method with a high potential for studying the hydration in the biological systems. We demonstrate that TDFS is very useful especially for phospholipid bilayers for mapping the interfacial region formed by the hydrated lipid headgroups. TDFS, when properly applied, reports on the degree of hydration and mobility of the hydrated phospholipid segments in the close vicinity of the fluorophore embedded in the bilayer. Here, the interpretation of the recorded TDFS parameters are thoroughly discussed, also in the context of the findings obtained by other experimental techniques addressing the hydration phenomena (e.g., molecular dynamics simulations, NMR spectroscopy, scattering techniques, etc.). The differences in the interpretations of TDFS outputs between phospholipid biomembranes and proteins are also addressed. Additionally, prerequisites for the successful TDFS application are presented (i.e., the proper choice of fluorescence dye for TDFS studies, and TDFS instrumentation). Finally, the effects of ions and oxidized phospholipids on the bilayer organization and headgroup packing viewed from TDFS perspective are presented as application examples.