Changes In Concentration Of Components Research Articles

КОЭФФИЦИЕНТЫ ДИФФУЗИИ И АКТИВНОСТЬ КОМПОНЕНТОВ ВОДНОСПИРТОВЫХ СМЕСЕЙ В ПОЛИУРЕТАНОВЫХ ПЛЕНКАХ НА ОСНОВЕ АМИНОЭФИРОВ БОРНОЙ И ОРТОФОСФОРНОЙ КИСЛОТ

The work carried out studies to determine the diffusion coefficients and activities of water, isopropyl and ethyl alcohols in polymer polyurethane films based on amino esters of boric and orthophosphoric acids at temperatures of 22, 40 and 60 °C. To determine the diffusion coefficients, we used data on the dynamics of sorption of low molecular weight components in the polymers under study, presented in our previous study. To describe the process of swelling of a polymer film, the Fick differential equation was used; the process was represented as unsteady diffusion in a flat plate. The initial condition was the absence of a component in the polymer at the initial moment of time; the solution to the differential equation was the non-stationary field of concentrations of the component in the film. The experimental dependences of changes in the volume-mass concentration of components in the polymer were described using the Heaviside switching function; due to the presence of a maximum in the swelling curve, it is associated with a restructuring of the polymer structure that occurs due to possible relaxation processes. By minimizing the discrepancies between the calculated and experimental values of the concentration versus time dependence, the diffusion coefficients of pure components in AEPA and AEBA films were determined. Based on data on the diffusion of components through polymer films, the separation characteristics of polymers were assessed for their use as a selective layer of pervaporation membranes. Based on swelling data over long periods of time for water-alcohol mixtures of various compositions, the parameters of the Flory-Huggins model were determined for calculating the activities of components in the polymer. It was shown that among the solvents under study, water has the highest diffusion coefficient, and isopropyl alcohol has the lowest, regardless of the type of film (AEPA/AEBA). For all films, there is a tendency for the diffusion coefficient to increase with increasing temperature, regardless of the solvent.

Structural Characterization of Nanocellulose/Fe3O4 Hybrid Nanomaterials.

The rise of innovation in the electrical industry is driven by the controlled design of new materials. The hybrid materials based on magnetite/nanocellulose are highly interesting due to their various applications in medicine, ecology, catalysis and electronics. In this study, the structure and morphology of nanocellulose/magnetite hybrid nanomaterials were investigated. The effect of nanocellulose loading on the crystal structure of synthesized composites was investigated by XRD and FTIR methods. The presented study reveals that the interaction between the cellulose and magnetic nanoparticles depends on the nanocellulose content. Further, a transition from cellulose II to cellulose I allomorph is observed. SEM and EDS are employed to determine the variation in morphology with changes in component concentrations. By the calculation of magnetic interactions between adjacent Fe3+ and Fe2+ ions within composites, it is determined that ferromagnetic coupling predominates.

Maximizing Contact of Supersoft Bottlebrush Networks with Rough Surfaces To Promote Particulate Removal.

Efficient removal of particulates from a rough surface with a soft material through a "press and peel" method (i.e., an adhesion and release approach) depends on good conformal contact at the interface; a material should be sufficiently soft to maximize contact with a particle while also conforming to rough surface features to clean the entire substrate surface. Here, we investigate the use of bottlebrush networks-extremely soft elastomers composed of macromolecules with polymeric side chains-as materials for cleaning model substrates of varying roughness. Formed through free-radical polymerization of mono- and dimethacrylate functionalized polysiloxanes, these solvent-free supersoft elastomers exhibit moduli comparable to those of solvated gels, allowing for a lower moduli regime of elastomers to be used in contact experiments than previously possible. By varying the macromonomer to cross-linker ratio, we study the effect of modulus on conformal contact and cleaning for materials that are as soft as gels while minimizing/negating physical and/or chemical concerns that using a traditional material may involve (e.g., changes in component concentrations, solvent evaporation, and syneresis). We study cleaning efficacy by quantifying the conformal contact between soft materials and rough substrates via a contact adhesion-based measurement. These results give insight into the correlation between shear modulus and conformal contact with surfaces of varying feature height. Not only does a decrease in shear modulus leads to improved conformal contact with rough surfaces, but also it facilitates adhesion to particulates situated on the rough surface, thus aiding removal. We highlight this property control with a case study illustrating the removal of an artificial soil mixture from a rough, acrylic surface via peeling rather than rubbing, which can cause damage to delicate surfaces.

Organochlorine pesticides in ambient air from the littoral cities of northern China: Spatial distribution, seasonal variation, source apportionment and cancer risk assessment

Concentrations, composition and seasonal variations of organochlorine pesticides (OCPs) in the atmosphere (particulate phase and gaseous phase) at coastal cities in northern China were determined. OCP transport from emission source areas and lifetime excess cancer risks by inhalation exposure to specific OCPs were also investigated. The annual average concentration of total OCPs in gaseous phase ranged from 1.0ng/m3 to 6.3ng/m3, with the peak observed in summer at most sites. Particulate phase concentrations ranged from 29.9pg/m3 to 103.3pg/m3, with the maximum found in the local heating period at most locations. The detection rates of gaseous samples were considerably higher than those of particulate ones. The dominant components included endosulfan (I and II), (α- and γ-) chlordane, pentachlorobiphenyl (PeCB), hexachlorobenzene (HCB), heptachlor, (α-, β- and γ-) hexachlorocyclohexane (HCH), dichloro-diphenyl-trichloroethane (DDT) and their metabolic products. The specific ratios indicated different applications of DDT, technical HCH and endosulfan at most sites. Large differences in compositional profiles occurred in January (typical heating period) and July (representative non-heating period), and diurnal changes in component concentrations may have been influenced by local emission pattern. The potential source contribution function (PSCF) manifested seasonal concentrations of airborne OCPs affected by the input of potential sources in different regions. The emission sources with higher contribution probabilities to the sites were primarily distributed in the surrounding areas. The lifetime excess cancer risks for the local residents by inhalation exposure to specific components were not high, though the potential threat of α-HCH and HCB should be concerned. CapsuleGaseous OCPs reached peak values in summer and dominated relative to particulate (PM10) values; meanwhile, surrounding sources affected air OCP concentrations, and cancer risks of OCPs by inhalation exposure were not high.

The application of the Raman Spectroscopy Method for Evaluating Implants from the Dura Mater

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Model to predict inhomogeneous protein–sugar distribution in powders prepared by spray drying

A protein can be stabilized by spray drying an aqueous solution of the protein and a sugar, thereby incorporating the protein into a glassy sugar matrix. For optimal stability, the protein should be homogeneously distributed inside the sugar matrix. The aim of this study was to develop a model that can predict the distribution of protein and sugar in an evaporating droplet using bovine serum albumin (BSA) and trehalose as model protein and sugar, respectively. This was achieved by expanding a previously developed model that was able to predict the growth or shrinkage of inhaled droplets in the airways (Grasmeijer, Frijlink & Hinrichs, 2016). The droplet was considered to consist of a finite number of concentric spherical shells in which the change in concentration of components was calculated in time, enabling the prediction of concentration gradients inside the droplet. It was found that during evaporation of the droplet, an inhomogeneous protein–sugar distribution was formed even when surface active properties were not considered. The relatively large protein molecule was predicted to accumulate much faster at the surface of the droplet than the sugar due to slower diffusion, resulting in a lower sugar/protein ratio at the surface of the particle than in the center. For a mixture of BSA and trehalose, not considering surface active properties, it was predicted that 60% of protein was incorporated in the powder at a lower sugar/protein ratio than when protein and sugar would have been homogeneously distributed, which may hamper efficient protein stabilization. These predictions can be used to more accurately adapt the initial composition of the solution to ensure proper stabilization of the protein, for example by simply increasing the amount of sugar to increase the sugar/protein ratio at the surface. Or, if this is limited by the desired loading, changing the drying conditions to slow down the drying rate.

Optimization of the Mixing Process and Quality Evaluation of the Thirteen-Component Granular Mixture

The paper presents the research on the quality of thirteen-component granular mixture. The changes in the quality of the mixture after reduction the mixing time from a standard time of 30 minutes to: 25 minutes, 20 minutes and 15 minutes have been analyzed. The research has been conducted in industrial conditions where a vertical mixer with worm agitator with the charge of two tons was used. Research results were presented graphically as changes in concentration of components shares in the mixing time of 30, 25, 20 and 15 minutes and the obtained results were compared. Quality assessment of a thirteen-component mixture with the use of residual sum of squares for four mixing times was carried out.

Simulation of thermally induced processes of diffusion and phase formation in layered Fe-Sn and Fe-Zr systems

The simulation results of thermally induced processes of diffusion and phase formation for the Fe-Sn and Fe-Zr layered systems experimentally investigated by Mossbauer spectroscopy are presented. Simulation has been carried out using the specially designed DIFFUSION program, the basic functional possibilities of which are described in detail. The physical model is based on the phenomenological Darken theory and on the interdiffusion mechanism of components along the continuous diffusion channels of phases in two-phase regions of the system. The simulation results agree well with the experimental data. The character of phase transformations in the investigated layered systems is determined by the change in a local concentration of components during their interdiffusion and corresponds to the features of the equilibrium diagrams for both binary systems.

Quantifying epistatic interactions among the components constituting the protein translation system

In principle, the accumulation of knowledge regarding the molecular basis of biological systems should allow the development of large-scale kinetic models of their functions. However, the development of such models requires vast numbers of parameters, which are difficult to obtain in practice. Here, we used an in vitro translation system, consisting of 69 defined components, to quantify the epistatic interactions among changes in component concentrations through Bahadur expansion, thereby obtaining a coarse-grained model of protein synthesis activity. Analyses of the data measured using various combinations of component concentrations indicated that the contributions of larger than 2-body inter-component epistatic interactions are negligible, despite the presence of larger than 2-body physical interactions. These findings allowed the prediction of protein synthesis activity at various combinations of component concentrations from a small number of samples, the principle of which is applicable to analysis and optimization of other biological systems. Moreover, the average ratio of 2- to 1-body terms was estimated to be as small as 0.1, implying high adaptability and evolvability of the protein translation system.

Computation and analysis of time-dependent sensitivities in Generalized Mass Action systems

Understanding biochemical system dynamics is becoming increasingly important for insights into the functioning of organisms and for biotechnological manipulations, and additional techniques and methods are needed to facilitate investigations of dynamical properties of systems. Extensions to the method of Ingalls and Sauro, addressing time-dependent sensitivity analysis, provide a new tool for executing such investigations. We present here the results of sample analyses using time-dependent sensitivities for three model systems taken from the literature, namely an anaerobic fermentation pathway in yeast, a negative feedback oscillator modeling cell-cycle phenomena, and the Mitogen Activated Protein (MAP) kinase cascade. The power of time-dependent sensitivities is particularly evident in the case of the MAPK cascade. In this example it is possible to identify the emergence of a concentration of MAPKK that provides the best response with respect to rapid and efficient activation of the cascade, while over- and under-expression of MAPKK relative to this concentration have qualitatively different effects on the transient response of the cascade. Also of interest is the quite general observation that phase-plane representations of sensitivities in oscillating systems provide insights into the manner with which perturbations in the envelope of the oscillation result from small changes in initial concentrations of components of the oscillator. In addition to these applied analyses, we present an algorithm for the efficient computation of time-dependent sensitivities for Generalized Mass Action (GMA) systems, the most general of the canonical system representations of Biochemical Systems Theory (BST). The algorithm is shown to be comparable to, or better than, other methods of solution, as exemplified with three biochemical systems taken from the literature.

A mapping approach for three-dimensional distributive mixing analysis

A mapping approach is proposed for the numerical simulation of distributive mixing in three-dimensional laminar flows. The method is based on a spatial discretization of the locally averaged concentration of fluid components in the mixture (the so-called “coarse grain density”). A distribution matrix, that describes the changes in component concentration, is composed. The proposed method makes it possible to rapidly predict the (short- and long-term) mixing performances, and to compare a large number of different mixing protocols in an efficient way. The consistency and accuracy of this algorithm is validated by comparing the results obtained on grids with different spatial resolution, and by comparison with front tracking results. The technique is evaluated in a prototype mixing flow in a cubic cavity, generated by sliding opposite walls. Different mixing protocols are compared quantitatively, and result in optimal mixing protocol parameters.

Mathematical Modelling of Strongly Nonequilibrium Topochemical Reactions in Powder Systems

Theoretical analysis of nonequilibrium decomposition of transition metal compounds with elements forming diatomic phases is performed. Solution of the mathematical model for an open nonequilibrium system makes it possible to establish the nonmonotonous nature of the changes in component concentration. It is concluded that there are thermokinetic oscillations leading to the occurrence of dissipative structures.

Linear systems analysis of activating processes of complement system as a defense mechanism

The Complement system is an important element of the host defense mechanism, although its kinetics and characteristics as a system are still unclear. We have investigated its temporal changes and system properties from the view point of system engineering. The temporal changes of sequential activating processes of the system were expressed by 26 non-linear differential equations using reported values of rate constants and serum concentration for each component. The intermediate products in the activating processes increased parabolically while the membrane attack component as the final product, increased linearly. The little change in inactive precursors afforded validity for system linearization. Linear systems analysis revealed that the system which was insensitive to the changes in rate constants was unstable. The system became stable when the feed-back input from the final product was set to operate on the first step of the activating processes. Seven uncontrollable variables were insensitive to changes in rate constants or system optimization that minimized the changes in concentrations of components in the complement system. The singular values of the complement system were reduced and the impulse responses of the system were improved when the system was optimized. When stronger minimization was imposed on the changes of concentration of the components in the complement system, the singular values were reduced more, the magnitude of the impulse responses was depressed further and the responses terminated earlier than those when the elements in the weighting matrix of concentration of the components were set to be unity. By this potent minimization, the influences of changes in rate constants on the singular values were diminished. The present theoretical analysis is presented to evaluate the ability of defense mechanism of complement system.

High resolution electrophoresis of soybean seed isoesterases

A modified discontinuous buffer system for vertical polyacrylamide electrophoresis was developed with large changes in component concentration from the original Tris-HCl/Tris-glycine system of the Ornstein-Davis type. The new buffer system is able to resolve the fast soybean seed isoesterases crucial for cultivar discrimination. A higher number of anodic bands is obtained in comparison with separations under standard conditions. A "gelating boundary", resulting from the aggregation of seed proteins, is retarded and does not migrate out of the upper stacking gel. The same buffer modification is also beneficial to the separation of native seed proteins.

Fatty acid composition of fats of differing melting points extracted from ram subcutaneous tissue.

The observation that the subcutaneous fat of pasture-fed Southdown rams consists of two distinct regions is reported. Fatty acid composition of fat from the outer and inner regions of subcutaneous tissue taken from the rib region of eight Southdown rams fed pasture were determined. Relative to the harder inner regions (mean melting point 43.1 degrees C), the softer outer regions (mean melting point 31.8 degrees C) were shown to contain more 9:0-, 15:0-, 17:0-, 17:1-, 18:1-cis and total 18:1 fatty acids; less 14:0-, 16:0-, 18:0- and 18:1-trans fatty acids; and a greater variety and a greater concentration of branched-chain components. Proportions of medium chain-length fatty acids, other than 9:0, did not differ between the layers. The fatty acid contents of serial samples taken at 1-mm intervals through these tissues were determined. Changes in concentrations of components among samples were gradual through the tissues. There was no clear connective tissue sheet, as has been reported for pigs. The inner region of the tissues contains apparently nonrandom fluctuating changes in fatty acid composition.

Cell surface receptors for extracellular matrix molecules.

Table 2 lists most of the extracellular matrix and related receptors identified to date. The wide range of binding affinities of these receptors for their ligands may be important to their function. The affinity of integrins for fibronectin is moderate, with a dissociation constant in the micromolar range. This affinity level leads to relatively rapid dissociation and reformation of receptor-ligand complexes. Thus changes in component concentration can shift binding equilibria within minutes (the time scale of many biologic phenomena) and change the number or organization of adhesive complexes. This type of interaction would be useful in motile cells, in which adhesions must form and dissociate rapidly. In contrast, the affinity of the 68-kDa laminin receptor for its ligand is three orders of magnitude higher. Such levels of affinity would be useful in stabilizing tissue. Members of the integrin family appear to recognize an RGD sequence on the ligands to which they bind. Since there are many ligands containing the RGD sequence, the question of specificity arises. Avian integrin shows little specificity and appears to behave as a multifunctional, promiscuous receptor for extracellular matrix molecules. Figure 1 summarizes our current view of the structural and functional features of avian integrin. In contrast, the mammalian receptors for vitronectin and fibronectin are specific for their respective ligands. More than one of these receptors may be present simultaneously on a cell surface, e.g. fibroblasts express receptors for fibronectin, laminin, and vitronectin at the same time. This multiplicity of receptors provides potential mechanisms for generating the adhesive differences among cells believed to play a prominent role in morphogenesis. Further adhesive differences may stem from the formation of different combinations of various alpha- and beta-subunits expressed in the cell. The mechanism of regulation of adhesive interactions with the extracellular matrix is only beginning to be explored. There are several levels at which this regulation might occur. Integrin appears to be more regionalized in more developed cells that are integral parts of tissue structures. Changes in receptor distribution could alter the relative strength of adhesive interactions. In certain instances, avian integrin disappears, or its concentration is reduced, e.g. during the development of embryonic lung (Chen et al 1986) and erythroid cells (Patel & Lodish 1985). Post-translational modifications provide yet another mechanism for regulating integrin-ligand binding.(ABSTRACT TRUNCATED AT 400 WORDS)

Thermal-diffusion aging in solidified radioactive wastes

There is particular importance in the storage of high-level wastes (for example, vitrified ones) in the stability of the solid matrix (glass) containing radionuclides. This paper examines the most rapid process in glass component redistribution near inhomogeneities (inclusions, pores, cracks, etc.), as these inevitably arise during vitrification. The authors consider two model problems, whose solutions enable one to estimate the changes in component concentrations near inhomogeneities.

Complement changes during leukapheresis.

Alterations of the complement system occurring during continuous-flow filtration leukapheresis (CFFL) and intermittent-flow centrifugation leukapheresis (IFCL) were assessed in 16 donors. Five blood samples were obtained at timed intervals during each cytaphere-sis, three directly from each donor and two from the efferent lines returning blood from the leukapheresis machines to the donors. Components measured were C1, C2, C4, C3, C3-C9 and CH50 of the classical, and factor B, properdin and properdin convertase of the alternative pathways. Changes in concentrations of components were compared to baseline values present in donor blood obtained prior to cytapheresis. During the first 10 minutes of CFFL, C2, C4, C3-9 and CH50 were decreased (p < 0.05) in machine efferent fluids, but returned towards normal as the procedure continued. Changes in donor venous blood, decreased factor B, properdin and C3-C9, were demonstrated only at the end of cytapheresis. During IFCL, significant (p < 0.05) decreases of C1, C2, C3-C9 and factor B occurred in donor blood after 60 minutes of cytapheresis, however, all deficiencies except B corrected spontaneously as cytapheresis continued. In contrast, concentrations of C2, C4, C3-C9, CH50 and factor B remained decreased in machine efferent fluids throughout the procedure. The data support those of previous studies that have demonstrated complement activation at the filter site during CFFL. Changes in donor venous blood are a new finding that may indicate in vivo activation of the alternative pathway. Profound changes of the complement system occur during IFCL also, but complement activation seems a less likely explanation. Instead, complement proteins may be lost by adsorption onto the surfaces of the IFCL software.