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Sample records for fluid ionic regulation

  1. Nanoparticle enhanced ionic liquid heat transfer fluids

    DOEpatents

    Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Gray, Joshua R.; Garcia-Diaz, Brenda L.

    2014-08-12

    A heat transfer fluid created from nanoparticles that are dispersed into an ionic liquid is provided. Small volumes of nanoparticles are created from e.g., metals or metal oxides and/or alloys of such materials are dispersed into ionic liquids to create a heat transfer fluid. The nanoparticles can be dispersed directly into the ionic liquid during nanoparticle formation or the nanoparticles can be formed and then, in a subsequent step, dispersed into the ionic liquid using e.g., agitation.

  2. Dynamic Dielectrophoresis Model of Multi-Phase Ionic Fluids

    PubMed Central

    Yan, Ying; Luo, Jing; Guo, Dan; Wen, Shizhu

    2015-01-01

    Ionic-based dielectrophoretic microchips have attracted significant attention due to their wide-ranging applications in electro kinetic and biological experiments. In this work, a numerical method is used to simulate the dynamic behaviors of ionic droplets in a microchannel under the effect of dielectrophoresis. When a discrete liquid dielectric is encompassed within a continuous fluid dielectric placed in an electric field, an electric force is produced due to the dielectrophoresis effect. If either or both of the fluids are ionic liquids, the magnitude and even the direction of the force will be changed because the net ionic charge induced by an electric field can affect the polarization degree of the dielectrics. However, using a dielectrophoresis model, assuming ideal dielectrics, results in significant errors. To avoid the inaccuracy caused by the model, this work incorporates the electrode kinetic equation and defines a relationship between the polarization charge and the net ionic charge. According to the simulation conditions presented herein, the electric force obtained in this work has an error exceeding 70% of the actual value if the false effect of net ionic charge is not accounted for, which would result in significant issues in the design and optimization of experimental parameters. Therefore, there is a clear motivation for developing a model adapted to ionic liquids to provide precise control for the dielectrophoresis of multi-phase ionic liquids. PMID:25699513

  3. Ionic liquids as potential carriers of low viscosity magnetorheological fluids

    NASA Astrophysics Data System (ADS)

    Guerrero-Sanchez, Carlos; Ortiz-Alvarado, Armando; Schubert, Ulrich S.

    2009-03-01

    Based on the latest investigations on the formulation of new magneto-rheological fluids, it is envisioned that the use of ionic liquids as carriers of magneto-rheological fluids will open new possibilities of applications for these smart fluids due to the fact that their physical and chemical properties can be fine-tuned in a broad range. This contribution addresses one potentially important advantage of magneto-rheological fluids which use ionic liquids as novel carriers. In connection with this, magneto-rheological fluids with a low viscosity in the off-state without compromising other properties of the formulations (e. g., sedimentation of the dispersed magnetic particles, liquid state of the carriers in a broad range of temperatures) are often required for specific applications. In this regard, ionic liquids of low viscosity can be very useful in the development of such magneto-rheological fluids. Thus, this contribution reports on the magnetorheological properties of iron(II, III) oxide particles dispersed in the ionic liquid 1-ethyl-3-methylimidazolium thiocyanate (a low viscosity ionic liquid) in the temperature range from 20 °C to 80 °C. The experimental results have revealed that the apparent viscosity of the dispersion slightly changes with the temperature when a constant magnetic field is applied and its value mainly depends on the shear rate and the strength of the magnetic field. The viscosity of the dispersion remains practically unmodified with both the temperature and the magnetic field intensity as the magnetic saturation of the material is reached; in this regime the viscosity will only depend on the applied shear rate. In contrast, the yield stress values of the dispersion as well as the corresponding shear stress vs. shear rate curves have shown an inverse behavior with temperature for a constant magnetic field.

  4. On the Ginzburg temperature of ionic and dipolar fluids

    NASA Astrophysics Data System (ADS)

    Weiss, V. C.; Schröer, W.

    1997-02-01

    Critical fluctuations in fluids are investigated within the framework of the generalized van der Waals theory. The square-gradient term—added to the Landau expansion of the Helmholtz free energy density—is obtained following a procedure similar to that originally proposed by van der Waals in the theory of surface tension, however replacing the Heaviside step function originally used by an approximative pair distribution function. Representative for ionic fluids we choose the restricted primitive model (RPM) and treat it within the Debye-Hückel theory, thus neglecting effects of ion pairing. The other approximative extreme—complete ion pairing resulting in a fluid of hard dipolar dumbbells—is mimicked by a fluid composed of dipolar hard spheres (DHS). For this case we use the Onsager reaction field and the second pressure virial coefficient. We calculate the amplitudes of the correlation length and the Ginzburg temperatures, and find (in reduced quantities) ξ0*=3.50 and ΔTGi*=0.0087 for the ionic system, and ξ0*=0.82 and ΔTGi*=1.63 for the dipolar fluid. For calibration we compute the same quantities for simple neutral fluids and obtain ξ0*=0.50 and ΔTGi*=2.89 for a Sutherland fluid (hard core term plus attractive r-6-potential) and ξ0*=0.43 and ΔTGi*=8.50 for a square-well fluid. The result of a smaller Ginzburg temperature for the ionic fluid than for nonionic fluids in a treatment that neglects ion pairing is clearly at variance with the results of other groups. The correlation length in the low-density limit obtained from our approach has the same functional dependencies as the Lee-Fisher expression, but differs by a numerical factor of 5.7.

  5. Hypothalamic integration of body fluid regulation.

    PubMed Central

    Denton, D A; McKinley, M J; Weisinger, R S

    1996-01-01

    The progression of animal life from the paleozoic ocean to rivers and diverse econiches on the planet's surface, as well as the subsequent reinvasion of the ocean, involved many different stresses on ionic pattern, osmotic pressure, and volume of the extracellular fluid bathing body cells. The relatively constant ionic pattern of vertebrates reflects a genetic "set" of many regulatory mechanisms--particularly renal regulation. Renal regulation of ionic pattern when loss of fluid from the body is disproportionate relative to the extracellular fluid composition (e.g., gastric juice with vomiting and pancreatic secretion with diarrhea) makes manifest that a mechanism to produce a biologically relatively inactive extracellular anion HCO3- exists, whereas no comparable mechanism to produce a biologically inactive cation has evolved. Life in the ocean, which has three times the sodium concentration of extracellular fluid, involves quite different osmoregulatory stress to that in freshwater. Terrestrial life involves risk of desiccation and, in large areas of the planet, salt deficiency. Mechanisms integrated in the hypothalamus (the evolutionary ancient midbrain) control water retention and facilitate excretion of sodium, and also control the secretion of renin by the kidney. Over and above the multifactorial processes of excretion, hypothalamic sensors reacting to sodium concentration, as well as circumventricular organs sensors reacting to osmotic pressure and angiotensin II, subserve genesis of sodium hunger and thirst. These behaviors spectacularly augment the adaptive capacities of animals. Instinct (genotypic memory) and learning (phenotypic memory) are melded to give specific behavior apt to the metabolic status of the animal. The sensations, compelling emotions, and intentions generated by these vegetative systems focus the issue of the phylogenetic emergence of consciousness and whether primal awareness initially came from the interoreceptors and vegetative

  6. Protein Crystallization Using Room Temperature Ionic Fluids

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Paley, Mark Steve; Turner, Megan B.; Rogers, Robin D.

    2006-01-01

    The ionic liquids (ILs) 1-butyl-3-methylimidizolium chloride (C4mim-C1), 1-butyl-3- methylimidizolium diethyleneglycol monomethylethersulfate ([C4mim]DEMGS), and 1-butyl-1 -methylpyrollidinium dihydrogenphosphate ([p1,4]dhp) were tested for their effects on the crystallization of the proteins canavalin, beta-lactoglobulin B, xylanase, and glucose isomerase, using a standard high throughput screen. The crystallization experiments were set up with the ILs added to the protein solutions at 0.2 and 0.4 M final concentrations. Crystallization droplets were set up at three proteixprecipitant ratios (1:1, 2:1, and 4:l), which served to progressively dilute the effects of the screen components while increasing the equilibrium protein and IL concentrations. Crystals were obtained for all four proteins at a number of conditions where they were not obtained from the IL-free control experiment. Over half of the protein-IL combinations tested had more successful outcomes than negative, where the IL-free crystallization was better than the corresponding IL-containing outcome, relative to the control. One of the most common causes of a negative outcome was solubilization of the protein by the IL, resulting in a clear drop. In one instance, we were able to use the IL-induced solubilizing to obtain beta-lactoglobulin B crystals from conditions that gave precipitated protein in the absence of IL. The results suggest that it may be feasible to develop ILs specifically for the task of macromolecule crystallization.

  7. The line tension of two-dimensional ionic fluids

    NASA Astrophysics Data System (ADS)

    Eustaquio-Armenta, María del Rosario; Méndez-Maldonado, Gloria Arlette; González-Melchor, Minerva

    2016-04-01

    Pressure tensor components are very useful in the calculation of the tension associated with a liquid-vapor interface. In this work, we present expressions for the pressure tensor components of two-dimensional ionic fluids, modeled at the level of the primitive model. As an application, we carried out molecular dynamics simulations of liquid-vapor interfaces to calculate the line tension of the 1:1 two-dimensional ionic fluid, whose liquid-vapor coexistence curve had already been obtained in a previous work. The pressure tensor components were validated by simulating states of one phase and reproducing the scalar pressure, previously obtained from bulk simulations and reported in the literature. The effects on the line tension and the coexisting densities, originated by the choice of the Ewald parameters, the cutoff radius, and the interfacial length were also evaluated.

  8. Predicting critical temperatures of ionic and non-ionic fluids from thermophysical data obtained near the melting point.

    PubMed

    Weiss, Volker C

    2015-10-14

    In the correlation and prediction of thermophysical data of fluids based on a corresponding-states approach, the critical temperature Tc plays a central role. For some fluids, in particular ionic ones, however, the critical region is difficult or even impossible to access experimentally. For molten salts, Tc is on the order of 3000 K, which makes accurate measurements a challenging task. Room temperature ionic liquids (RTILs) decompose thermally between 400 K and 600 K due to their organic constituents; this range of temperatures is hundreds of degrees below recent estimates of their Tc. In both cases, reliable methods to deduce Tc based on extrapolations of experimental data recorded at much lower temperatures near the triple or melting points are needed and useful because the critical point influences the fluid's behavior in the entire liquid region. Here, we propose to employ the scaling approach leading to universal fluid behavior [Román et al., J. Chem. Phys. 123, 124512 (2005)] to derive a very simple expression that allows one to estimate Tc from the density of the liquid, the surface tension, or the enthalpy of vaporization measured in a very narrow range of low temperatures. We demonstrate the validity of the approach for simple and polar neutral fluids, for which Tc is known, and then use the methodology to obtain estimates of Tc for ionic fluids. When comparing these estimates to those reported in the literature, good agreement is found for RTILs, whereas the ones for the molten salts NaCl and KCl are lower than previous estimates by 10%. The coexistence curve for ionic fluids is found to be more adequately described by an effective exponent of βeff = 0.5 than by βeff = 0.33. PMID:26472385

  9. Corresponding-states behavior of an ionic model fluid with variable dispersion interactions

    NASA Astrophysics Data System (ADS)

    Weiss, Volker C.

    2016-06-01

    Guggenheim's corresponding-states approach for simple fluids leads to a remarkably universal representation of their thermophysical properties. For more complex fluids, such as polar or ionic ones, deviations from this type of behavior are to be expected, thereby supplying us with valuable information about the thermodynamic consequences of the interaction details in fluids. Here, the gradual transition of a simple fluid to an ionic one is studied by varying the relative strength of the dispersion interactions compared to the electrostatic interactions among the charged particles. In addition to the effects on the reduced surface tension that were reported earlier [F. Leroy and V. C. Weiss, J. Chem. Phys. 134, 094703 (2011)], we address the shape of the coexistence curve and focus on properties that are related to and derived from the vapor pressure. These quantities include the enthalpy and entropy of vaporization, the boiling point, and the critical compressibility factor Zc. For all of these properties, the crossover from simple to characteristically ionic fluid is seen once the dispersive attraction drops below 20%-40% of the electrostatic attraction (as measured for two particles at contact). Below this threshold, ionic fluids display characteristically low values of Zc as well as large Guggenheim and Guldberg ratios for the reduced enthalpy of vaporization and the reduced boiling point, respectively. The coexistence curves are wider and more skewed than those for simple fluids. The results for the ionic model fluid with variable dispersion interactions improve our understanding of the behavior of real ionic fluids, such as inorganic molten salts and room temperature ionic liquids, by gauging the importance of different types of interactions for thermodynamic properties.

  10. Corresponding-states behavior of an ionic model fluid with variable dispersion interactions.

    PubMed

    Weiss, Volker C

    2016-06-21

    Guggenheim's corresponding-states approach for simple fluids leads to a remarkably universal representation of their thermophysical properties. For more complex fluids, such as polar or ionic ones, deviations from this type of behavior are to be expected, thereby supplying us with valuable information about the thermodynamic consequences of the interaction details in fluids. Here, the gradual transition of a simple fluid to an ionic one is studied by varying the relative strength of the dispersion interactions compared to the electrostatic interactions among the charged particles. In addition to the effects on the reduced surface tension that were reported earlier [F. Leroy and V. C. Weiss, J. Chem. Phys. 134, 094703 (2011)], we address the shape of the coexistence curve and focus on properties that are related to and derived from the vapor pressure. These quantities include the enthalpy and entropy of vaporization, the boiling point, and the critical compressibility factor Zc. For all of these properties, the crossover from simple to characteristically ionic fluid is seen once the dispersive attraction drops below 20%-40% of the electrostatic attraction (as measured for two particles at contact). Below this threshold, ionic fluids display characteristically low values of Zc as well as large Guggenheim and Guldberg ratios for the reduced enthalpy of vaporization and the reduced boiling point, respectively. The coexistence curves are wider and more skewed than those for simple fluids. The results for the ionic model fluid with variable dispersion interactions improve our understanding of the behavior of real ionic fluids, such as inorganic molten salts and room temperature ionic liquids, by gauging the importance of different types of interactions for thermodynamic properties. PMID:27334174

  11. Reorganization energy of electron transfer processes in ionic fluids: A molecular Debye-Hueckel approach

    SciTech Connect

    Xiao Tiejun; Song Xueyu

    2013-03-21

    The reorganization energy of electron transfer processes in ionic fluids is studied under the linear response approximation using a molecule Debye-Hueckel theory. Reorganization energies of some model reactants of electron transfer reactions in molten salts are obtained from molecular simulations and a molecule Debye-Hueckel approach. Good agreements between simulation results and the results from our theoretical calculations using the same model Hamiltonian are found. Applications of our theory to electron transfer reactions in room temperature ionic liquids further demonstrate that our theoretical approach presents a reliable and accurate methodology for the estimation of reorganization energies of electron transfer reactions in ionic fluids.

  12. Mixed ionic liquids: the case of pyridinium-based fluids.

    PubMed

    Aparicio, Santiago; Atilhan, Mert

    2012-03-01

    We report in this work a combined experimental and computational study on the molecular level structuring of binary ionic liquid mixtures comprising pyridium cations. The effect of anions on liquid structure was analyzed from the mixing (mixture 1) of [b3mpy][BF(4)] and [b3mpy][N(CN)(2)] ionic liquids, in the full composition range, leading to [b3mpy][BF(4)](x)[N(CN)(2)](1-x) mixed ionic liquids. The effect of the length of alkylic chains in cations was studied with mixtures (mixture 2) of [b3mpy][BF(4)] and [o3mpy][BF(4)] ionic liquids, also studied in the full composition range, leading to [b3mpy](x)[o3mpy](1-x)[BF(4)] ionic liquids. Fourier transform infrared-attenuated total reflection spectra were recorded and analyzed as a function of anionic and cationic composition for the two studied mixture types. Classical molecular dynamics simulations were also performed for mixtures 1 and 2 as a function of anionic and cationic composition. The reported experimental and computational results show that the properties of the studied mixed systems change in an almost linear way, leading to almost ideal mixtures from the thermodynamic viewpoint, and thus pointing to simple dilution effects of the involved ions controlling the mixture properties. PMID:22309042

  13. Size-selective chemical synthesis of tartrate stabilized cobalt ferrite ionic magnetic fluid.

    PubMed

    Neveu, S; Bee, A; Robineau, M; Talbot, D

    2002-11-15

    Ionic magnetic fluid (ferrofluid) is a stable suspension of magnetic nanoparticles in water. Cobalt ferrite nanoparticles are interesting in view of high-density recording storage. The size of the magnetic particles strongly influences the physical properties of the ferrofluids. In this study, we describe the synthesis of ionic magnetic fluid in the presence of tartrate ions. By varying the amount of organic ligands, nanoparticles in a large range of size are obtained: the mean diameter varies from 3 to 10 nm. The effect of tartrate ions on the stability of the ionic magnetic fluid is also studied in relation with the size of the magnetic particles and the amount of adsorbed ligand. PMID:12505076

  14. Thermophysical Properties of Nanoparticle-Enhanced Ionic Liquids (NEILs) Heat-Transfer Fluids

    SciTech Connect

    Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Amoroso, Jake W.

    2013-06-20

    An experimental investigation was completed on nanoparticle enhanced ionic liquid heat transfer fluids as an alternative to conventional organic based heat transfer fluids (HTFs). These nanoparticle-based HTFs have the potential to deliver higher thermal conductivity than the base fluid without a significant increase in viscosity at elevated temperatures. The effect of nanoparticle morphology and chemistry on thermophysical properties was examined. Whisker shaped nanomaterials were found to have the largest thermal conductivity temperature dependence and were also less likely to agglomerate in the base fluid than spherical shaped nanomaterials.

  15. Vapour-liquid phase diagram for an ionic fluid in a random porous medium.

    PubMed

    Holovko, M F; Patsahan, O; Patsahan, T

    2016-10-19

    We study the vapour-liquid phase behaviour of an ionic fluid confined in a random porous matrix formed by uncharged hard sphere particles. The ionic fluid is modelled as an equimolar binary mixture of oppositely charged equisized hard spheres, the so-called restricted primitive model (RPM). Considering the matrix-fluid system as a partly-quenched model, we develop a theoretical approach which combines the method of collective variables with the extension of the scaled-particle theory (SPT) for a hard-sphere fluid confined in a disordered hard-sphere matrix. The approach allows us to formulate the perturbation theory using the SPT for the description of the thermodynamics of the reference system. The phase diagrams of the RPM in matrices of different porosities and for different size ratios of matrix and fluid particles are calculated in the random-phase approximation and also when the effects of higher-order correlations between ions are taken into account. Both approximations correctly reproduce the basic effects of porous media on the vapour-liquid phase diagram, i.e. with a decrease of porosity the critical point shifts towards lower fluid densities and lower temperatures and the coexistence region gets narrower. For the fixed matrix porosity, both the critical temperature and the critical density increase with an increase of size of matrix particles and tend to the critical values of the bulk RPM. PMID:27548356

  16. Edemagenic gain and interstitial fluid volume regulation.

    PubMed

    Dongaonkar, R M; Quick, C M; Stewart, R H; Drake, R E; Cox, C S; Laine, G A

    2008-02-01

    Under physiological conditions, interstitial fluid volume is tightly regulated by balancing microvascular filtration and lymphatic return to the central venous circulation. Even though microvascular filtration and lymphatic return are governed by conservation of mass, their interaction can result in exceedingly complex behavior. Without making simplifying assumptions, investigators must solve the fluid balance equations numerically, which limits the generality of the results. We thus made critical simplifying assumptions to develop a simple solution to the standard fluid balance equations that is expressed as an algebraic formula. Using a classical approach to describe systems with negative feedback, we formulated our solution as a "gain" relating the change in interstitial fluid volume to a change in effective microvascular driving pressure. The resulting "edemagenic gain" is a function of microvascular filtration coefficient (K(f)), effective lymphatic resistance (R(L)), and interstitial compliance (C). This formulation suggests two types of gain: "multivariate" dependent on C, R(L), and K(f), and "compliance-dominated" approximately equal to C. The latter forms a basis of a novel method to estimate C without measuring interstitial fluid pressure. Data from ovine experiments illustrate how edemagenic gain is altered with pulmonary edema induced by venous hypertension, histamine, and endotoxin. Reformulation of the classical equations governing fluid balance in terms of edemagenic gain thus yields new insight into the factors affecting an organ's susceptibility to edema. PMID:18056984

  17. Ionic conductances regulating the excitability of colonic smooth muscles

    PubMed Central

    Koh, Sang Don; Ward, Sean M.; Sanders, Kenton M.

    2012-01-01

    The tunica muscularis of the gastrointestinal (GI) tract contains two layers of smooth muscle cells (SMC) oriented perpendicular to each other. SMC express a variety of voltage-dependent and voltage-independent ionic conductance(s) that develop membrane potential and control excitability. Resting membrane potentials (RMP) vary through the GI tract but generally are within the range of −80 to −40mV. RMP sets the ‘gain’ of smooth muscle and regulates openings of voltage-dependent Ca2+ channels. A variety of K+ channels contribute to setting RMP of SMC. In most regions RMP is considerably less negative than the K+ equilibrium potential, due to a finely tuned balance between background K+ channels and non-selective cation channels (NSCC). Variations in expression patterns and openings of K+ channels and NSCC account for differences of the RMP in different regions of the GI tract. Smooth muscle excitability is also regulated by interstitial cells (interstitial cells of Cajal (ICC) and PDGFRα+ cells) that express additional conductances and are electrically coupled to SMC. Thus, ‘myogenic’ activity results from the integrated behavior of the SMC/ICC/PDGFRα+ cell (SIP) syncytium. Inputs from excitatory and inhibitory motor neurons are required to produce the complex motor patterns of the gut. Motor neurons innervate three cell-types in the SIP, and receptors, second messenger pathways and ion channels in these cells mediate post-junctional responses. Studies of isolated SIP cells have begun to unravel the mechanisms responsible for neural responses. This review discusses ion channels that set and regulate RMP of SIP cells and how neurotransmitters regulate membrane potential. PMID:22726670

  18. Stability and magnetorheological behaviour of magnetic fluids based on ionic liquids

    NASA Astrophysics Data System (ADS)

    Rodríguez-Arco, Laura; López-López, Modesto T.; Durán, Juan D. G.; Zubarev, Andrey; Chirikov, Dmitrij

    2011-11-01

    This paper reports the preparation of magnetic fluids consisting of magnetite nanoparticles dispersed in an ionic liquid. Different additives were used in order to stabilize the fluids. Colloidal stability was checked by magnetic sedimentation, centrifugation and direct observation. The results of these tests showed that a true ferrofluid was only obtained when the nanoparticles were coated with a layer of surfactant compatible with the ionic liquid. These experiments also showed that stability could not be reached just by electrostatic repulsion. The conclusions of the stability tests were confirmed by calculations of the interparticle energies of interaction. The rheological behaviour of the magnetic fluids upon magnetic field application was also investigated. The experimental magnetoviscous response was fitted by a microstructural model. The model considered that the fluids consisted of two populations of particles, one with a magnetic core diameter of 9 nm, and another with a larger diameter. Upon field application chain-like structures are supposed to be induced. According to estimations particles of 9 nm are too small to aggregate upon field application. The results of the calculations showed that the intensity of the magnetoviscous response depends on the concentration and size of the large particles, and on the thickness of the surfactant layers.

  19. Stability and magnetorheological behaviour of magnetic fluids based on ionic liquids.

    PubMed

    Rodríguez-Arco, Laura; López-López, Modesto T; Durán, Juan D G; Zubarev, Andrey; Chirikov, Dmitrij

    2011-11-16

    This paper reports the preparation of magnetic fluids consisting of magnetite nanoparticles dispersed in an ionic liquid. Different additives were used in order to stabilize the fluids. Colloidal stability was checked by magnetic sedimentation, centrifugation and direct observation. The results of these tests showed that a true ferrofluid was only obtained when the nanoparticles were coated with a layer of surfactant compatible with the ionic liquid. These experiments also showed that stability could not be reached just by electrostatic repulsion. The conclusions of the stability tests were confirmed by calculations of the interparticle energies of interaction. The rheological behaviour of the magnetic fluids upon magnetic field application was also investigated. The experimental magnetoviscous response was fitted by a microstructural model. The model considered that the fluids consisted of two populations of particles, one with a magnetic core diameter of 9 nm, and another with a larger diameter. Upon field application chain-like structures are supposed to be induced. According to estimations particles of 9 nm are too small to aggregate upon field application. The results of the calculations showed that the intensity of the magnetoviscous response depends on the concentration and size of the large particles, and on the thickness of the surfactant layers. PMID:21971064

  20. Solvation dynamics in ionic fluids: an extended Debye-Hückel dielectric continuum model.

    PubMed

    Song, Xueyu

    2009-07-28

    Motivated by our recent proposition on the possibility of using dielectric continuum models to interpret experimental measurements of solvation dynamics in room temperature ionic liquids [J. Phys. Chem. A 110, 8623 (2006)], some detailed simulation studies are performed to test the validity of our proposition. From these simulation studies, it seems to be justified that an extended Debye-Hückel continuum model can be used to understand the solvation dynamics of ionic fluids. The theoretical underpinning of such an extended Debye-Hückel model is presented from the general dispersion relation in electrodynamics. The connection with the static extension from the dressed ion theory of electrolyte solutions is also discussed. Such a connection between the Debye-Hückel theory and the dispersion relation may be exploited to enhance our understanding of the electric double layer problem not only for the static case but also for dynamic situations. PMID:19655890

  1. Effect of ionic additives on the elution of sodium aryl sulfonates in supercritical fluid chromatography.

    PubMed

    Zheng, J; Taylor, L T; Pinkston, J David; Mangels, M L

    2005-08-01

    Addition of a small amount of polar solvent (i.e., modifier) to CO2 in packed column supercritical fluid chromatography (SFC) has shown major improvements in both polar analyte solubility and interaction of the polar analyte with the stationary phase. Recently, the addition of an ionic component (i.e., additive) to the primary modifier by one of us has been shown to extend even further the application of SFC to polar analytes. In this work, the effect of various ionic additives on the elution of ionic compounds, such as sodium 4-dodecylbenzene sulfonate and sodium 4-octylbenene sulfonate, has been studied. The additives were lithium acetate, ammonium acetate, tetramethylammonium acetate, tetrabutylammonium acetate, and ammonium chloride dissolved in methanol. Three stationary phases with different degrees of deactivation were considered: conventional cyanopropyl, deltabond cyanopropyl, and bare silica. The effect of additive concentration and additive functionality on analyte retention was investigated. Sodium 4-dodecylbenzene sulfonate was successfully eluted using all the additives with good peak shape under isocratic/isobaric/isothermal conditions. Different additives, however, yielded different retention times and in some cases different peak shapes. PMID:16035365

  2. Sprint training enhances ionic regulation during intense exercise in men.

    PubMed Central

    McKenna, M J; Heigenhauser, G J; McKelvie, R S; MacDougall, J D; Jones, N L

    1997-01-01

    plasma [HCO3-] were lower after training (mean differences) by 1.7 mmHg, 4.5 mmHg and 1.2 mmol l-1, respectively (P < 0.05), with arterial plasma [H+] being greater after training by 2.2 nmol l-1 (P < 0.05). 7. The acute changes in whole blood volume and ion concentrations during maximal exercise were similar to previous observations: Arterial and femoral whole blood [K+] and [Cl-] were increased, whilst [Na+] was lower, across all observation times after training (P < 0.05). 8. Net uptake or release of ions by exercising muscle was assessed by arteriovenous whole blood concentration differences, corrected for fluid movements. A net K+ uptake by muscle occurred at all times, including exercise, but this was not significantly different after training. An increased net Na+ uptake by muscle occurred during exercise (P < 0.05) with greater Na+ uptake after training (P < 0.05). Net muscle Lac- release and Cl- uptake occurred at all times (P < 0.05) and were unchanged by training. 9. Sprint training improved muscle ion regulation, associated with increased intense exercise performance, at the expense of a greater systemic acidosis. Increased muscle Na+ and K+ uptake by muscle during the final seconds of exercise after training are consistent with a greater activation of the muscle Na(+) - K+ pump, reduced cellular K+ loss and the observed lesser rate of fatigue. The greater plasma acidosis found after sprint training was caused by a lower arterial plasma [SID] due to lower plasma [K+] and [Na+], and higher plasma [Lac-]. PMID:9218228

  3. Dynamic Hydraulic Fluid Stimulation Regulated Intramedullary Pressure

    PubMed Central

    Hu, Minyi; Serra-Hsu, Frederick; Bethel, Neville; Lin, Liangjun; Ferreri, Suzanne; Cheng, Jiqi; Qin, Yi-Xian

    2013-01-01

    Physical signals within bone, i.e. generated from mechanical loading, have the potential to initiate skeletal adaptation. Strong evidence has pointed to bone fluid flow (BFF) as a media between an external load and the bone cells, in which altered velocity and pressure can ultimately initiate the mechanotransduction and the remodeling process within bone. Load-induced BFF can be altered by factors such as intramedullary pressure (ImP) and/or bone matrix strain, mediating bone adaptation. Previous studies have shown that BFF induced by ImP alone, with minimum bone strain, can initiate bone remodeling. However, identifying induced ImP dynamics and bone strain factor in vivo using a non-invasive method still remains challenging. To apply ImP as a means for alteration of BFF, it was hypothesized that non-invasive dynamic hydraulic stimulation (DHS) can induce local ImP with minimal bone strain to potentially elicit osteogenic adaptive responses via bone-muscle coupling. The goal of this study was to evaluate the immediate effects on local and distant ImP and strain in response to a range of loading frequencies using DHS. Simultaneous femoral and tibial ImP and bone strain values were measured in three 15-month-old female Sprague Dawley rats during DHS loading on the tibia with frequencies of 1Hz to 10Hz. DHS showed noticeable effects on ImP induction in the stimulated tibia in a nonlinear fashion in response to DHS over the range of loading frequencies, where peaked at 2Hz. DHS at various loading frequencies generated minimal bone strain in the tibiae. Maximal bone strain measured at all loading frequencies was less than 8με. No detectable induction of ImP or bone strain was observed in the femur. This study suggested that oscillatory DHS may regulate the local fluid dynamics with minimal mechanical strain in bone, which serves critically in bone adaptation. These results clearly implied DHS’s potential as an effective, non-invasive intervention for osteopenia and

  4. The new nanophysiology: regulation of ionic flow in neuronal subcompartments.

    PubMed

    Holcman, David; Yuste, Rafael

    2015-11-01

    Cable theory and the Goldman-Hodgkin-Huxley-Katz models for the propagation of ions and voltage within a neuron have provided a theoretical foundation for electrophysiology and been responsible for many cornerstone advances in neuroscience. However, these theories break down when they are applied to small neuronal compartments, such as dendritic spines, synaptic terminals or small neuronal processes, because they assume spatial and ionic homogeneity. Here we discuss a broader theory that uses the Poisson-Nernst-Planck (PNP) approximation and electrodiffusion to more accurately model the constraints that neuronal nanostructures place on electrical current flow. This extension of traditional cable theory could advance our understanding of the physiology of neuronal nanocompartments. PMID:26462753

  5. THE POTENTIAL OF NANOPARTICLE ENHANCED IONIC LIQUIDS (NEILS) AS ADVANCED HEAT TRANSFER FLUIDS

    SciTech Connect

    Fox, E.; Bridges, N.; Visser, A.

    2011-09-14

    Interest in capturing the energy of the sun is rising as demands for renewable energy sources increase. One area of developing research is the use of concentrating solar power (CSP), where the solar energy is concentrated by using mirrors to direct the sunlight towards a collector filled with a heat transfer fluid (HTF). The HTF transfers the collected energy into pressurized steam, which is used to generate energy. The greater the energy collected by the HTF, the more efficent the electrical energy production is, thus the overall efficiency is controlled by the thermal fluid. Commercial HTFs such as Therminol{reg_sign} (VP-1), which is a blend of biphenyl and diphenyl oxide, have a significant vapor pressure, especially at elevated temperatures. In order for these volatile compounds to be used in CSP systems, the system either has to be engineered to prevent the phase change (i.e., volatilization and condensation) through pressurization of the system, or operate across the phase change. Over thirty years ago, a class of low-melting organic compounds were developed with negligible vapor pressure. These compounds are referred to as ionic liquids (ILs), which are organic-based compounds with discrete charges that cause a significant decrease in their vapor pressure. As a class, ILs are molten salts with a melting point below 100 C and can have a liquidus range approaching 400 C, and in several cases freezing points being below 0 C. Due to the lack of an appreciable vapor pressure, volatilization of an IL is not possible at atmospheric pressure, which would lead to a simplification of the design if used as a thermal fluid and for energy storage materials. Though the lack of a vapor pressure does not make the use of ILs a better HTF, the lack of a vapor pressure is a compliment to their higher heat capacity, higher volummetric density, and thus higher volumetric heat capacity. These favorable physical properties give ILs a pontential advantage over the current

  6. Osmotic/ionic status of body fluids in the euryhaline cephalopod suggest possible parallel evolution of osmoregulation

    PubMed Central

    Sakamoto, Tatsuya; Ogawa, Satoshi; Nishiyama, Yudai; Akada, Chiaki; Takahashi, Hideya; Watanabe, Taro; Minakata, Hiroyuki; Sakamoto, Hirotaka

    2015-01-01

    Acclimation from marine to dilute environments constitutes among the dramatic evolutionary transitions in the history of life. Such adaptations have evolved in multiple lineages, but studies of the blood/hemolymph homeostasis mechanisms are limited to those using evolutionarily advanced Deuterostome (chordates) and Ecdysozoa (crustaceans). Here, we examined hemolymph homeostasis in the advanced Lophotrochozoa/mollusc, the other unexplored taxa, and its possible regulation by the vasopressin/oxytocin superfamily peptides known to be implicated in fluid homeostasis in Chordata and Arthropoda. The hemolymph osmotic and ionic status in the euryhaline cephalopod (Octopus ocellatus) following transfer from 30-ppt normal seawater to 20 ppt salinity indicate hyperosmo- and hyperionoregulatory abilities for more than 1 week, as in crustaceans and teleost fish. While ventilation frequency decreased by 1 day, Na+/K+-ATPase activity, which has been generally implicated in ion transport, was induced in two of the eight posterior gills after 1 week. In addition, the octopuses were intravenously injected with 1 or 100 ng/g octopressin or cephalotocin, which are Octopus vasopressin/oxytocin orthologs. After 1 day, octopressin, but not cephalotocin, decreased the hemolymph osmolality and Ca concentrations, as well as urinary Na concentrations. These data provide evidence for possible parallel evolution in hyperionoregulatory mechanisms and coordination by conserved peptides. PMID:26403952

  7. Osmotic/ionic status of body fluids in the euryhaline cephalopod suggest possible parallel evolution of osmoregulation.

    PubMed

    Sakamoto, Tatsuya; Ogawa, Satoshi; Nishiyama, Yudai; Akada, Chiaki; Takahashi, Hideya; Watanabe, Taro; Minakata, Hiroyuki; Sakamoto, Hirotaka

    2015-01-01

    Acclimation from marine to dilute environments constitutes among the dramatic evolutionary transitions in the history of life. Such adaptations have evolved in multiple lineages, but studies of the blood/hemolymph homeostasis mechanisms are limited to those using evolutionarily advanced Deuterostome (chordates) and Ecdysozoa (crustaceans). Here, we examined hemolymph homeostasis in the advanced Lophotrochozoa/mollusc, the other unexplored taxa, and its possible regulation by the vasopressin/oxytocin superfamily peptides known to be implicated in fluid homeostasis in Chordata and Arthropoda. The hemolymph osmotic and ionic status in the euryhaline cephalopod (Octopus ocellatus) following transfer from 30-ppt normal seawater to 20 ppt salinity indicate hyperosmo- and hyperionoregulatory abilities for more than 1 week, as in crustaceans and teleost fish. While ventilation frequency decreased by 1 day, Na(+)/K(+)-ATPase activity, which has been generally implicated in ion transport, was induced in two of the eight posterior gills after 1 week. In addition, the octopuses were intravenously injected with 1 or 100 ng/g octopressin or cephalotocin, which are Octopus vasopressin/oxytocin orthologs. After 1 day, octopressin, but not cephalotocin, decreased the hemolymph osmolality and Ca concentrations, as well as urinary Na concentrations. These data provide evidence for possible parallel evolution in hyperionoregulatory mechanisms and coordination by conserved peptides. PMID:26403952

  8. Feedback regulated induction heater for a flowing fluid

    DOEpatents

    Migliori, Albert; Swift, Gregory W.

    1985-01-01

    A regulated induction heater for heating a stream of flowing fluid to a predetermined desired temperature. The heater includes a radiofrequency induction coil which surrounds a glass tube through which the fluid flows. A heating element consisting of a bundle of approximately 200 stainless steel capillary tubes located within the glass tube couples the output of the induction coil to the fluid. The temperature of the fluid downstream from the heating element is sensed with a platinum resistance thermometer, the output of which is applied to an adjustable proportional and integral feedback control circuit which regulates the power applied to the induction coil. The heater regulates the fluid temperature to within 0.005.degree. C. at a flow rate of 50 cm.sup.3 /second with a response time of less than 0.1 second, and can accommodate changes in heat load up to 1500 watts.

  9. Feedback regulated induction heater for a flowing fluid

    DOEpatents

    Migliori, A.; Swift, G.W.

    1984-06-13

    A regulated induction heater for heating a stream of flowing fluid to a predetermined desired temperature. The heater includes a radiofrequency induction coil which surrounds a glass tube through which the fluid flows. A heating element consisting of a bundle of approximately 200 stainless steel capillary tubes located within the glass tube couples the output of the induction coil to the fluid. The temperature of the fluid downstream from the heating element is sensed with a platinum resistance thermometer, the output of which is applied to an adjustable porportional and integral feedback control circuit which regulates the power applied to the induction coil. The heater regulates the fluid temperature to within 0.005/sup 0/C at a flow rate of 50 cm/sup 3//sec with a response time of less than 0.1 second, and can accommodate changes in heat load up to 1500 watts.

  10. Hormonal regulation of fluid and electrolyte metabolism during periods of headward fluid shifts

    NASA Technical Reports Server (NTRS)

    Keil, Lanny C.; Severs, W. B.; Thrasher, T.; Ramsay, D. J.

    1991-01-01

    In the broadest sense, this project evaluates how spaceflight induced shifts of blood and interstitial fluids into the thorax affect regulation by the central nervous system (CNS) of fluid-electrolyte hormone secretion. Specifically, it focuses on the role of hormones related to salt/water balance and their potential function in the control of intracranial pressure and cerebrospinal fluid (CSF) composition. Fluid-electrolyte status during spaceflight gradually equilibrates, with a reduction in all body fluid compartments. Related to this is the cardiovascular deconditioning of spaceflight which is manifested upon return to earth as orthostatic intolerance.

  11. Crystalline polymorphism induced by charge regulation in ionic membranes

    PubMed Central

    Leung, Cheuk-Yui; Palmer, Liam C.; Kewalramani, Sumit; Qiao, Baofu; Stupp, Samuel I.; Olvera de la Cruz, Monica; Bedzyk, Michael J.

    2013-01-01

    The crystallization of molecules with polar and hydrophobic groups, such as ionic amphiphiles and proteins, is of paramount importance in biology and biotechnology. By coassembling dilysine (+2) and carboxylate (–1) amphiphiles of various tail lengths into bilayer membranes at different pH values, we show that the 2D crystallization process in amphiphile membranes can be controlled by modifying the competition of long-range and short-range interactions among the polar and the hydrophobic groups. The pH and the hydrophobic tail length modify the intermolecular packing and the symmetry of their crystalline phase. For hydrophobic tail lengths of 14 carbons (C14), we observe the coassembly into crystalline bilayers with hexagonal molecular ordering via in situ small- and wide-angle X-ray scattering. As the tail length increases, the hexagonal lattice spacing decreases due to an increase in van der Waals interactions, as demonstrated by atomistic molecular dynamics simulations. For C16 and C18 we observe a reentrant crystalline phase transition sequence, hexagonal–rectangular-C–rectangular-P–rectangular-C–hexagonal, as the solution pH is increased from 3 to 10.5. The stability of the rectangular phases, which maximize tail packing, increases with increasing tail length. As a result, for very long tails (C22), the possibility of observing packing symmetries other than rectangular-C phases diminishes. Our work demonstrates that it is possible to systematically exchange chemical and mechanical energy by changing the solution pH value within a range of physiological conditions at room temperature in bilayers of molecules with ionizable groups. PMID:24065818

  12. Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.

    PubMed

    Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

    2013-01-01

    Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level. PMID:23552653

  13. Direct Ionic Regulation of the Activity of Myo-Inositol Biosynthesis Enzymes in Mozambique Tilapia

    PubMed Central

    Villarreal, Fernando D.; Kültz, Dietmar

    2015-01-01

    Myo-inositol (Ins) is a major compatible osmolyte in many cells, including those of Mozambique tilapia (Oreochromis mossambicus). Ins biosynthesis is highly up-regulated in tilapia and other euryhaline fish exposed to hyperosmotic stress. In this study, enzymatic regulation of two enzymes of Ins biosynthesis, Ins phosphate synthase (MIPS) and inositol monophosphatase (IMPase), by direct ionic effects is analyzed. Specific MIPS and IMPase isoforms from Mozambique tilapia (MIPS-160 and IMPase 1) were selected based on experimental, phylogenetic, and structural evidence supporting their role for Ins biosynthesis during hyperosmotic stress. Recombinant tilapia IMPase 1 and MIPS-160 activity was assayed in vitro at ionic conditions that mimic changes in the intracellular milieu during hyperosmotic stress. The in vitro activities of MIPS-160 and IMPase 1 are highest at alkaline pH of 8.8. IMPase 1 catalytic efficiency is strongly increased during hyperosmolality (particularly for the substrate D-Ins-3-phosphate, Ins-3P), mainly as a result of [Na+] elevation. Furthermore, the substrate-specificity of IMPase 1 towards D-Ins-1-phosphate (Ins-1P) is lower than towards Ins-3P. Because MIPS catalysis results in Ins-3P this results represents additional evidence for IMPase 1 being the isoform that mediates Ins biosynthesis in tilapia. Our data collectively demonstrate that the Ins biosynthesis enzymes are activated under ionic conditions that cells are exposed to during hypertonicity, resulting in Ins accumulation, which, in turn, results in restoration of intracellular ion homeostasis. We propose that the unique and direct ionic regulation of the activities of Ins biosynthesis enzymes represents an efficient biochemical feedback loop for regulation of intracellular physiological ion homeostasis during hyperosmotic stress. PMID:26066044

  14. Extraction of proteins from biological fluids by use of an ionic liquid/aqueous two-phase system.

    PubMed

    Du, Zhuo; Yu, Yong-Liang; Wang, Jian-Hua

    2007-01-01

    An ionic liquid/aqueous two-phase system based on the hydrophilic ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and K(2)HPO(4) has been employed for direct extraction of proteins from human body fluids for the first time. Proteins present at low levels were quantitatively extracted into the BmimCl-rich upper phase with a distribution ratio of about 10 between the upper and lower phase and an enrichment factor of 5. Addition of an appropriate amount of K(2)HPO(4) to the separated upper phase results in a further phase separation, giving rise to an improved enrichment factor of 20. FTIR and UV spectroscopy demonstrated that no chemical (bonding) interactions between the ionic liquid and the protein functional groups were identifiable, while no alterations of the natural properties of the proteins were observed. The partitioning of proteins in the two-phase system was assumed to have been facilitated by the electrostatic potential difference between the coexisting phases, as well as by salting out effects. The system could be applied successfully for the quantification of proteins in human urine after on-line phase separation in a flow system. The use of an ionic liquid, as a green solvent, offers clear advantages over traditional liquid-liquid extractions, in which the use of toxic organic solvents is unavoidable. PMID:17136782

  15. Use of TOUGHREACT to Simulate Effects of Fluid Chemistry onInjectivity in Fractured Geothermal Reservoirs with High Ionic StrengthFluids

    SciTech Connect

    Xu, Tianfu; Zhang, Guoxiang; Pruess, Karsten

    2005-02-09

    Recent studies suggest that mineral dissolution/precipitation and clay swelling effects could have a major impact on the performance of hot dry rock (HDR) and hot fractured rock (HFR) reservoirs. A major concern is achieving and maintaining adequate injectivity, while avoiding the development of preferential short-circuiting flow paths. A Pitzer ionic interaction model has been introduced into the publicly available TOUGHREACT code for solving non-isothermal multi-phase reactive geochemical transport problems under conditions of high ionic strength, expected in typical HDR and HFR systems. To explore chemically-induced effects of fluid circulation in these systems, we examine ways in which the chemical composition of reinjected waters can be modified to improve reservoir performance. We performed a number of coupled thermo-hydrologic-chemical simulations in which the fractured medium was represented by a one-dimensional MINC model (multiple interacting continua). Results obtained with the Pitzer activity coefficient model were compared with those using an extended Debye-Hueckel equation. Our simulations show that non-ideal activity effects can be significant even at modest ionic strength, and can have major impacts on permeability evolution in injection-production systems. Alteration of injection water chemistry, for example by dilution with fresh water, can greatly alter precipitation and dissolution effects, and can offer a powerful tool for operating hot dry rock and hot fractured rock reservoirs in a sustainable manner.

  16. Ionic Regulation of Cell Volume Changes and Cell Death after Ischemic Stroke

    PubMed Central

    Song, Mingke; Yu, Shan Ping

    2014-01-01

    Stroke is a leading cause of human death and disability in the US and around the world. Shortly after the cerebral ischemia, cell swelling is the earliest morphological change in injured neuronal, glial and endothelial cells. Cytotoxic swelling directly results from increased Na+ (with H2O) and Ca2+ influx into cells via ionic mechanisms evoked by membrane depolarization and a number of harmful factors such as glutamate accumulation and the production of oxygen reactive species (ROS). During the sub-acute and chronic phases after ischemia, injured cells may show a phenotype of cell shrinkage due to complex processes involving membrane receptors/channels and programmed cell death signals. This review will introduce some progress in the understanding of the regulation of pathological cell volume changes and the involved receptors and channels, including NMDA and AMPA receptors, acid-sensing ion channels (ASIC), hemichannels, transient receptor potential (TRP) channels and KCNQ channels. Moreover, accumulating evidence supports a key role of energy deficiency and dysfunction of Na+/K+-ATPase in ischemia-induced cell volume changes and cell death. Specifically, the Na+ pump failure is a prerequisite for disruption of ionic homeostasis including a pro-apoptotic disruption of the K+ homeostasis. Finally, we will introduce the concept of hybrid cell death as a result of the Na+ pump failure in cultured cells and the ischemic brain. The goal of this review is to outline recent understanding of the ionic mechanism of ischemic cytoxicity and suggest innovative ideas for future translational research. PMID:24323733

  17. Impact of Single-Particle Compressibility on the Fluid-Solid Phase Transition for Ionic Microgel Suspensions

    NASA Astrophysics Data System (ADS)

    Pelaez-Fernandez, M.; Souslov, Anton; Lyon, L. A.; Goldbart, P. M.; Fernandez-Nieves, A.

    2015-03-01

    We study ionic microgel suspensions composed of swollen particles for various single-particle stiffnesses. We measure the osmotic pressure π of these suspensions and show that it is dominated by the contribution of free ions in solution. As this ionic osmotic pressure depends on the volume fraction of the suspension ϕ , we can determine ϕ from π , even at volume fractions so high that the microgel particles are compressed. We find that the width of the fluid-solid phase coexistence, measured using ϕ , is larger than its hard-sphere value for the stiffer microgels that we study and progressively decreases for softer microgels. For sufficiently soft microgels, the suspensions are fluidlike, irrespective of volume fraction. By calculating the dependence on ϕ of the mean volume of a microgel particle, we show that the behavior of the phase-coexistence width correlates with whether or not the microgel particles are compressed at the volume fractions corresponding to fluid-solid phase coexistence.

  18. Balance point characterization of interstitial fluid volume regulation.

    PubMed

    Dongaonkar, R M; Laine, G A; Stewart, R H; Quick, C M

    2009-07-01

    The individual processes involved in interstitial fluid volume and protein regulation (microvascular filtration, lymphatic return, and interstitial storage) are relatively simple, yet their interaction is exceedingly complex. There is a notable lack of a first-order, algebraic formula that relates interstitial fluid pressure and protein to critical parameters commonly used to characterize the movement of interstitial fluid and protein. Therefore, the purpose of the present study is to develop a simple, transparent, and general algebraic approach that predicts interstitial fluid pressure (P(i)) and protein concentrations (C(i)) that takes into consideration all three processes. Eight standard equations characterizing fluid and protein flux were solved simultaneously to yield algebraic equations for P(i) and C(i) as functions of parameters characterizing microvascular, interstitial, and lymphatic function. Equilibrium values of P(i) and C(i) arise as balance points from the graphical intersection of transmicrovascular and lymph flows (analogous to Guyton's classical cardiac output-venous return curves). This approach goes beyond describing interstitial fluid balance in terms of conservation of mass by introducing the concept of inflow and outflow resistances. Algebraic solutions demonstrate that P(i) and C(i) result from a ratio of the microvascular filtration coefficient (1/inflow resistance) and effective lymphatic resistance (outflow resistance), and P(i) is unaffected by interstitial compliance. These simple algebraic solutions predict P(i) and C(i) that are consistent with reported measurements. The present work therefore presents a simple, transparent, and general balance point characterization of interstitial fluid balance resulting from the interaction of microvascular, interstitial, and lymphatic function. PMID:19420292

  19. Diffusion and structure in complex fluids: I. Axial diffusion in membranes II. Proteins in ionic liquids

    NASA Astrophysics Data System (ADS)

    Bihari, Malvika

    Geometrically hindered motions of a single large solute (particle or polymer) can be imaged in real time via optical microscopy. The dynamics of fluorescent colloidal particles near surfaces and in porous membranes were monitored using confocal microscopy. A method of analysis to estimate diffusivity of particles in the axial direction by observing their intensity fluctuations was developed. The intensity fluctuations correspond to the Brownian motion of the particles in the axial direction. The method was successful in capturing the hindered diffusion of particles close to surfaces and in pores. This study provides a novel route to monitor the dynamics of particles, including biomacromolecules, near surfaces, through porous substrates and biological tissues. Ionic liquid (IL) as a medium for room temperature preservation of biomacromolecules has been proposed and, to investigate the possibility, physicochemical and enzymatic properties of proteins in the neat hydrophilic IL, ethylmethyl imidazolium ethyl sulfate [EMIM][EtSO4] were studied. Spectroscopic techniques were employed to probe the secondary and tertiary structure of proteins whereas light scattering and viscometry were used to estimate the hydrodynamic size. The secondary structure of the protein was retained in the ionic liquid but the tertiary structure was found to change. Alterations in protein conformation/activity were investigated after transfer of the dissolved protein from the IL to buffer. Further, suitability of ionic liquid gels as protein encapsulation and preservation media was assessed.

  20. Ionic osmolytes and intracellular calcium regulate tissue production in chondrocytes cultured in a 3D charged hydrogel.

    PubMed

    Farnsworth, Nikki L; Mead, Benjamin E; Antunez, Lorena R; Palmer, Amy E; Bryant, Stephanie J

    2014-11-01

    The goal of this study was to investigate the role of fixed negative charges in regulating cartilage-like tissue production by chondrocytes under static and dynamic three-dimensional culture, and to determine whether intracellular calcium ([Ca(2+)]i) is involved in mediating this response. Initial experiments using the 3D neutral hydrogel were conducted in static isotonic culture with ionic and non-ionic osmolytes added to the culture medium. Tissue production by bovine chondrocytes with non-ionic osmolytes was 1.9-fold greater than with ionic osmolytes, suggesting that the ionic nature of the osmolyte is an important regulator of tissue production. To investigate fixed negative charges, a 3D culture system containing encapsulated chondrocytes was employed based on a synthetic and neutral hydrogel platform within which negatively charged chondroitin sulfate was incorporated in a controlled manner. Incorporation of negative charges did not affect the mechanical properties of the hydrogel; however, intracellular ion concentration was elevated from the culture medium (330 mOsm) and estimated to be similar to that in ~400 mOsm culture medium. With dynamic loading, GAG synthesis decreased by 26% in neutral hydrogels cultured in 400mOsm medium, and increased by 26% in charged gels cultured in 330 mOsm. Treatment of chondrocyte-seeded hydrogels with the Ca(2+) chelator BAPTA-AM decreased GAG synthesis by 32-46% and was similar among all conditions, suggesting multiple roles for Ca(2+) mediated tissue production including with ionic osmolytes. In conclusion, findings from this study suggest that a dynamic ionic environment regulates tissue synthesis and points to [Ca(2+)]i signaling as a potential mediator. PMID:25128592

  1. Protein Kinase C Regulates Ionic Conductance in Hippocampal Pyramidal Neurons: Electrophysiological Effects of Phorbol Esters

    NASA Astrophysics Data System (ADS)

    Baraban, Jay M.; Snyder, Solomon H.; Alger, Bradley E.

    1985-04-01

    The vertebrate central nervous system contains very high concentrations of protein kinase C, a calcium-and phospholipid-stimulated phosphorylating enzyme. Phorbol esters, compounds with inflammatory and tumor-promoting properties, bind to and activate this enzyme. To clarify the role of protein kinase C in neuronal function, we have localized phorbol ester receptors in the rat hippocampus by autoradiography and examined the electrophysiological effects of phorbol esters on hippocampal pyramidal neurons in vitro. Phorbol esters blocked a calcium-dependent potassium conductance. In addition, phorbol esters blocked the late hyperpolarization elicited by synaptic stimulation even though other synaptic potentials were not affected. The potencies of several phorbol esters in exerting these actions paralleled their affinities for protein kinase C, suggesting that protein kinase C regulates membrane ionic conductance.

  2. Regulation of body fluid volume and electrolyte concentrations in spaceflight

    NASA Technical Reports Server (NTRS)

    Smith, S. M.; Krauhs, J. M.; Leach, C. S.

    1997-01-01

    Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian

  3. Regulation of body fluid volume and electrolyte concentrations in spaceflight.

    PubMed

    Smith, S M; Krauhs, J M; Leach, C S

    1997-01-01

    Despite a number of difficulties in performing experiments during weightlessness, a great deal of information has been obtained concerning the effects of spaceflight on the regulation of body fluid and electrolytes. Many paradoxes and questions remain, however. Although body mass, extracellular fluid volume, and plasma volume are reduced during spaceflight and remain so at landing, the changes in total body water are comparatively small. Serum or plasma sodium and osmolality have generally been unchanged or reduced during the spaceflight, and fluid intake is substantially reduced, especially during the first of flight. The diuresis that was predicted to be caused by weightlessness, has only rarely been observed as an increased urine volume. What has been well established by now, is the occurrence of a relative diuresis, where fluid intake decreases more than urine volume does. Urinary excretion of electrolytes has been variable during spaceflight, but retention of fluid and electrolytes at landing has been consistently observed. The glomerular filtration rate was significantly elevated during the SLS missions, and water and electrolyte loading tests have indicated that renal function is altered during readaptation to Earth's gravity. Endocrine control of fluid volumes and electrolyte concentrations may be altered during weightlessness, but levels of hormones in body fluids do not conform to predictions based on early hypotheses. Antidiuretic hormone is not suppressed, though its level is highly variable and its secretion may be affected by space motion sickness and environmental factors. Plasma renin activity and aldosterone are generally elevated at landing, consistent with sodium retention, but inflight levels have been variable. Salt intake may be an important factor influencing the levels of these hormones. The circadian rhythm of cortisol has undoubtedly contributed to its variability, and little is known yet about the influence of spaceflight on circadian

  4. Spatial resolution of the electrical conductance of ionic fluids using a Green-Kubo method.

    PubMed

    Jones, R E; Ward, D K; Templeton, J A

    2014-11-14

    We present a Green-Kubo method to spatially resolve transport coefficients in compositionally heterogeneous mixtures. We develop the underlying theory based on well-known results from mixture theory, Irving-Kirkwood field estimation, and linear response theory. Then, using standard molecular dynamics techniques, we apply the methodology to representative systems. With a homogeneous salt water system, where the expectation of the distribution of conductivity is clear, we demonstrate the sensitivities of the method to system size, and other physical and algorithmic parameters. Then we present a simple model of an electrochemical double layer where we explore the resolution limit of the method. In this system, we observe significant anisotropy in the wall-normal vs. transverse ionic conductances, as well as near wall effects. Finally, we discuss extensions and applications to more realistic systems such as batteries where detailed understanding of the transport properties in the vicinity of the electrodes is of technological importance. PMID:25399135

  5. Ionic liquids: nondestructive, nonvolatile imaging fluids for submicrometer-scale monolayer patterns.

    PubMed

    Hozumi, Atsushi; Bien, Pei; McCarthy, Thomas J

    2010-04-28

    A method for visualizing submicrometer-scale patterns of approximately 1.0-nm-thick monolayers terminated with CF(3) and CH(3) groups using an ionic liquid (IL) is described. Bis(hydroxyethyl)dimethylammonium methanesulfonate (BHDAMS) was spin-cast onto the photolithographically patterned samples. The BHDAMS wetted the photodecomposed regions selectively. Pattern widths of the mask ranged from 500 nm to 10 microm, and the IL-replicated patterns were observed using optical and laser microscopy. The nonvolatile BHDAMS had sufficient contrast to image submicrometer-scale patterns of monolayers over large areas. We note that this imaging technique involves no damage and is compatible with readily available laboratory equipment. PMID:20373769

  6. Analytic properties of the OCP and ionic mixtures in the strongly coupled fluid state

    SciTech Connect

    DeWitt, H.E.

    1993-12-02

    Exact results for the Madelung constants and first order anharmonic energies are given for the inverse power potentials with the Coulomb potential as the softest example. Similar exact results are obtained using the analysis of Rosenfeld on the {Gamma} {yields} {infinity} limit for the OCP internal energy, direct correlation function, screening function, and bridge functions. Knowing these exact limits for the fluid phase of the OCP allows one to determine the nature of the thermal corrections to the strongly coupled results. Solutions of the HNC equation modified with the hard sphere bridge function give an example.

  7. LRRC8 Proteins Form Volume-Regulated Anion Channels that Sense Ionic Strength.

    PubMed

    Syeda, Ruhma; Qiu, Zhaozhu; Dubin, Adrienne E; Murthy, Swetha E; Florendo, Maria N; Mason, Daniel E; Mathur, Jayanti; Cahalan, Stuart M; Peters, Eric C; Montal, Mauricio; Patapoutian, Ardem

    2016-01-28

    The volume-regulated anion channel (VRAC) is activated when a cell swells, and it plays a central role in maintaining cell volume in response to osmotic challenges. SWELL1 (LRRC8A) was recently identified as an essential component of VRAC. However, the identity of the pore-forming subunits of VRAC and how the channel is gated by cell swelling are unknown. Here, we show that SWELL1 and up to four other LRRC8 subunits assemble into heterogeneous complexes of ∼800 kDa. When reconstituted into bilayers, LRRC8 complexes are sufficient to form anion channels activated by osmolality gradients. In bilayers, as well as in cells, the single-channel conductance of the complexes depends on the LRRC8 composition. Finally, low ionic strength (Γ) in the absence of an osmotic gradient activates the complexes in bilayers. These data demonstrate that LRRC8 proteins together constitute the VRAC pore and that hypotonic stress can activate VRAC through a decrease in cytoplasmic Γ. PMID:26824658

  8. Implementation of a model of bodily fluids regulation.

    PubMed

    Fontecave-Jallon, Julie; Thomas, S Randall

    2015-09-01

    The classic model of blood pressure regulation by Guyton et al. (Annu Rev Physiol 34:13-46, 1972a; Ann Biomed Eng 1:254-281, 1972b) set a new standard for quantitative exploration of physiological function and led to important new insights, some of which still remain the focus of debate, such as whether the kidney plays the primary role in the genesis of hypertension (Montani et al. in Exp Physiol 24:41-54, 2009a; Exp Physiol 94:382-388, 2009b; Osborn et al. in Exp Physiol 94:389-396, 2009a; Exp Physiol 94:388-389, 2009b). Key to the success of this model was the fact that the authors made the computer code (in FORTRAN) freely available and eventually provided a convivial user interface for exploration of model behavior on early microcomputers (Montani et al. in Int J Bio-med Comput 24:41-54, 1989). Ikeda et al. (Ann Biomed Eng 7:135-166, 1979) developed an offshoot of the Guyton model targeting especially the regulation of body fluids and acid-base balance; their model provides extended renal and respiratory functions and would be a good basis for further extensions. In the interest of providing a simple, useable version of Ikeda et al.'s model and to facilitate further such extensions, we present a practical implementation of the model of Ikeda et al. (Ann Biomed Eng 7:135-166, 1979), using the ODE solver Berkeley Madonna. PMID:25935135

  9. Estimation of zeta potential by electrokinetic analysis of ionic fluid flows through a divergent microchannel.

    PubMed

    Chun, Myung-Suk; Lee, Sang-Yup; Yang, Seung-Man

    2003-10-01

    The streaming potential is generated by the electrokinetic flow effect within the electrical double layer of a charged solid surface. Surface charge properties are commonly quantified in terms of the zeta potential obtained by computation with the Helmholtz-Smoluchowski (H-S) equation following experimental measurement of streaming potential. In order to estimate a rigorous zeta potential for cone-shaped microchannel, the correct H-S equation is derived by applying the Debye-Hückel approximation and the fluid velocity of diverging flow on the specified position. The present computation provides a correction ratio relative to the H-S equation for straight cylindrical channel and enables us to interpret the effects of the channel geometry and the electrostatic interaction. The correction ratio decreases with increasing of diverging angle, which implies that smaller zeta potential is generated for larger diverging angle. The increase of Debye length also reduces the correction ratio due to the overlapping of the Debye length inside of the channel. It is evident that as the diverging angle of the channel goes to nearly zero, the correction ratio converges to the previous results for straight cylindrical channel. PMID:12957590

  10. Understanding Fluid Shifts in the Brain: Choroidal Regulation Involved in the Cerebral Fluid Response to Altered Gravity

    NASA Technical Reports Server (NTRS)

    Gabrion, Jaqueline; Vasques, Marilyn; Aquilina, Rudy (Technical Monitor)

    2002-01-01

    Fluid balance and regulation of body fluid production are critical aspects of life and survival on Earth. In space, without gravity exerting its usual downward pulling effect, the fluids of the human body shift in an unnatural, headward direction. After awhile, humans and other mammalian species adapt to the microgravity environment which leads to changes in the regulation and distribution of these body fluids. Previous spaceflight experiments have indicated that production of fluid in the brain and spinal cord, cerebrospinal fluid (CSF), might be reduced in rats exposed to microgravity. In this experiment conducted by Dr. Jacqueline Gabrion (University of Pierre and Marie Curie, France), proteins important for CSF production, and several molecules that regulate water and mineral transport, will be investigated in rats flown on the Shuttle. Dr. Gabrion and her team will determine the amounts of these proteins and molecules present in the brain in order to evaluate whether any changes have taken place during the rats' adaptation to microgravity. The levels of different aquaporins (proteins that act as a channel for water transport in and out of cells) will also be investigated in other areas of the brain and body to better understand the regulatory responses affecting these important water channel proteins. In addition to producing essential and basic information about fluid production in the brain and body, this experiment will reveal fundamental information about the mechanisms involved in cerebral adaptation and fluid balance during spaceflight.

  11. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria) in Response to Salinity Challenges.

    PubMed

    Lin, Chia-Hao; Yeh, Po-Ling; Lee, Tsung-Han

    2016-01-01

    Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan) have not been determined. In this study, we examined the effect of exposure to hypo (10‰)- and hyper (35‰)-osmotic salinity on hard clams raised at their natural salinity (20‰). The osmolality, [Na(+)], and [Cl(-)] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na(+), K(+)-ATPase (NKA) activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT) is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore the

  12. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria) in Response to Salinity Challenges

    PubMed Central

    Lin, Chia-Hao; Yeh, Po-Ling; Lee, Tsung-Han

    2016-01-01

    Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan) have not been determined. In this study, we examined the effect of exposure to hypo (10‰)- and hyper (35‰)-osmotic salinity on hard clams raised at their natural salinity (20‰). The osmolality, [Na+], and [Cl−] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na+, K+-ATPase (NKA) activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT) is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore the

  13. Ionic permeability of K, Na, and Cl in crayfish nerve. Regulation by membrane fixed charges and pH.

    PubMed Central

    Strickholm, A; Clark, H R

    1977-01-01

    Teorell's fixed charge theory for membrane ion permeability was utilized to calculate specific ionic permeabilities from measurements of membrane potential, conductance, and specific ionic transference numbers. The results were compared with the passive ionic conductances calculated from the branched equivalent circuit membrane model of Hodgkin Huxley. Ionic permeabilities for potassium, sodium, and chloride of crayfish (Procambarus clarkii) medial giant axons were examined over an external pH range from 3.8 to 11.4. Action potentials were obtained over this pH range. Failures occurred below pH 3.8 during protonation of membrane phospholipid phosphate and carboxyl, and above pH 11.4 from calcium precipitation. In general, chloride permeability increases with membrane protonation, while cation permeability decreases. At pH 7.0, PK = 1.33 X 10(-5), PCl = 1.49 X 10(-6), PNa = 1.92 X 10(-8) cm/s. PK: PCl: PNa = 693:78:1. PCl is zero above pH 10.6 and is opened predominately by protonation of epsilon-amino, and partially by tyrosine and sulfhydryl groups from pH 10.6 to 9. PK is activated in part by ionization of phospholipid phosphate and carboxyl around pH 4, then further by imidazole from pH 5 to 7, and then predominately from pH 7 to 9 by most probably phosphatidic acid. PNa permeability parallels that of potassium from pH 5 to 9.4. Below pH 5 and above pH 9.4, PNa increases while PK decreases. Evidence was obtained that these ions possibly share common passive permeable channels. The data best support the theory of Teorell, that membrane fixed charges regulate permiability and that essentially every membrane ionizable group appears involved in various amounts in ionic permeability control. PMID:18219

  14. Self-regulated magnetic fluid hyperthermia: A potential cancer therapy

    NASA Astrophysics Data System (ADS)

    Bagaria, Hitesh Ghanshyam

    An emerging cancer therapy, self-regulated magnetic fluid hyperthermia (MFH), is the motivation for this work. In this therapy, cancer is annihilated by heating the tumor to desired therapeutic temperatures (˜45°C) by using magnetic nanoparticles of controlled Curie temperatures (Tc). This work was aimed at preparing and characterizing FePt, NiPd and NiPt nanoparticles for self-regulated MFH because their Tc could be tuned by changing their composition. Based on the excellent colloidal stability, size tunability and toxicity considerations, FePt was an obvious choice for self-regulated MFH. The 3.2 nm Fe61Pt39 particles displayed a Tc of 151°C, which is well below the Tc of bulk Fe61Pt39 (˜327°C). To reach the desired Tc of 45°C the composition of iron needs to be increased. However, a major obstacle was the formation of iron oxide shells with increase in iron composition of the particles. A recent finding that the composition of individual FePt particles deviated significantly from the average value encouraged us to study the mechanism of formation of FePt particles. Our analysis showed that early in the reaction the particles were Pt-rich and as the reaction proceeded the Fe content increased. It was found that the wide distribution in the composition of individual particles started early in the synthesis, suggesting that the compositional variability may be attributed to the Pt nuclei. The synthesized FePt particles are unsuitable for biological applications because of their hydrophobic surface. Hence, their surface was modified by ligand exchange with mercapto alkanoic acids. After ligand exchange, stable FePt dispersions could be formed in alkaline water. The study revealed that both the carboxylate and thiol groups were required to form stable FePt dispersions. In addition, 15 nm gold particles were successfully conjugated to genetically modified adenoviruses that selectively bind to cancer tumors. We also modeled the thermal transport in tissues during

  15. Influence of electroosmotic flow on the ionic current rectification in a pH-regulated, conical nanopore

    NASA Astrophysics Data System (ADS)

    Lin, Dong-Huei; Lin, Chih-Yuan; Tseng, Shiojenn; Hsu, Jyh-Ping

    2015-08-01

    The ionic current rectification (ICR) is studied theoretically by considering a pH-regulated, conical nanopore. In particular, the effect of electroosmotic flow (EOF), which was often neglected in previous studies, is investigated by solving a set of coupled Poisson, Nernst-Planck, and Navier-Stokes equations. The behaviors of ICR under various conditions are examined by varying solution pH, bulk ionic concentration, and applied electric potential bias. We show that the EOF effect is significant when the bulk ionic concentration is medium high, the pH is far away from the iso-electric point, and the electric potential bias is high. The percentage deviation in the current rectification ratio arising from neglecting the EOF effect can be on the order of 100%. In addition, the behavior of the current rectification ratio at a high pH taking account of EOF is different both qualitatively and quantitatively from that without taking account of EOF.The ionic current rectification (ICR) is studied theoretically by considering a pH-regulated, conical nanopore. In particular, the effect of electroosmotic flow (EOF), which was often neglected in previous studies, is investigated by solving a set of coupled Poisson, Nernst-Planck, and Navier-Stokes equations. The behaviors of ICR under various conditions are examined by varying solution pH, bulk ionic concentration, and applied electric potential bias. We show that the EOF effect is significant when the bulk ionic concentration is medium high, the pH is far away from the iso-electric point, and the electric potential bias is high. The percentage deviation in the current rectification ratio arising from neglecting the EOF effect can be on the order of 100%. In addition, the behavior of the current rectification ratio at a high pH taking account of EOF is different both qualitatively and quantitatively from that without taking account of EOF. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03433g

  16. Estrogen effects on osmotic regulation of AVP and fluid balance.

    PubMed

    Stachenfeld, Nina S; Keefe, David L

    2002-10-01

    To determine estrogen effects on osmotic regulation of arginine vasopressin (AVP) and body fluids, we suppressed endogenous estrogen and progesterone using the gonadotropin-releasing hormone (GnRH) analog leuprolide acetate (GnRHa). Subjects were assigned to one of two groups: 1) GnRHa alone, then GnRHa + estrogen (E, n = 9, 25 +/- 1 yr); 2) GnRHa alone, then GnRHa + estrogen with progesterone (E/P, n = 6, 26 +/- 3). During GnRHa alone and with hormone treatment, we compared AVP and body fluid regulatory responses to 3% NaCl infusion (HSI, 120 min, 0.1 ml. min(-1). kg body wt(-1)), drinking (30 min, 15 ml/kg body wt), and recovery (60 min of seated rest). Plasma [E(2)] increased from 23.9 to 275.3 pg/ml with hormone treatments. Plasma [P(4)] increased from 0.6 to 5.7 ng/ml during E/P and was unchanged (0.4 to 0.6 ng/ml) during E. Compared with GnRHa alone, E reduced osmotic AVP release threshold (275 +/- 4 to 271 +/- 4 mosmol/kg, P < 0.05), and E/P reduced the AVP increase in response during HSI (6.0 +/- 1.3 to 4.2 +/- 0.6 pg/ml at the end of HSI), but free water clearance was unaffected in either group. Relative to GnRHa, pre-HSI plasma renin activity (PRA) was greater during E (0.8 +/- 0.1 vs. 1.2 +/- 0.2 ng ANG I. ml(-1). h(-1)) but not after HSI or recovery. PRA was greater than GnRHa during E/P at baseline (1.1 +/- 0.2 vs. 2.5 +/- 0.6) and after HSI (0.6 +/- 0.1 vs. 1.1 +/- 1.1) and recovery (0.5 +/- 0.1 vs. 1.3 +/- 0.2 ng ANG I. ml(-1). h(-1)). Baseline fractional excretion of sodium was unaffected by E or E/P but was attenuated by the end of recovery for both E (3.3 +/- 0.6 vs. 2.4 +/- 0.4%) and E/P (2.8 +/- 0.4 vs 1.7 +/- 0.4%, GnRHa alone and with hormone treatment, respectively). Fluid retention increased with both hormone treatments. Renal sensitivity to AVP may be lower during E due to intrarenal effects on water and sodium excretion. E/P increased sodium retention and renin-angiotensin-aldosterone stimulation. PMID:12217888

  17. Energy variational analysis of ions in water and channels: Field theory for primitive models of complex ionic fluids

    PubMed Central

    Eisenberg, Bob; Hyon, YunKyong; Liu, Chun

    2010-01-01

    Ionic solutions are mixtures of interacting anions and cations. They hardly resemble dilute gases of uncharged noninteracting point particles described in elementary textbooks. Biological and electrochemical solutions have many components that interact strongly as they flow in concentrated environments near electrodes, ion channels, or active sites of enzymes. Interactions in concentrated environments help determine the characteristic properties of electrodes, enzymes, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend on the charges, concentrations, and sizes of all ions, not just the same type of ion. We use a variational method EnVarA (energy variational analysis) that combines Hamilton’s least action and Rayleigh’s dissipation principles to create a variational field theory that includes flow, friction, and complex structure with physical boundary conditions. EnVarA optimizes both the action integral functional of classical mechanics and the dissipation functional. These functionals can include entropy and dissipation as well as potential energy. The stationary point of the action is determined with respect to the trajectory of particles. The stationary point of the dissipation is determined with respect to rate functions (such as velocity). Both variations are written in one Eulerian (laboratory) framework. In variational analysis, an “extra layer” of mathematics is used to derive partial differential equations. Energies and dissipations of different components are combined in EnVarA and Euler–Lagrange equations are then derived. These partial differential equations are the unique consequence of the contributions of individual components. The form and parameters of the partial differential equations are determined by algebra without additional physical content or assumptions. The partial differential equations of mixtures automatically combine physical properties of individual (unmixed) components

  18. Energy variational analysis of ions in water and channels: Field theory for primitive models of complex ionic fluids.

    PubMed

    Eisenberg, Bob; Hyon, Yunkyong; Liu, Chun

    2010-09-14

    Ionic solutions are mixtures of interacting anions and cations. They hardly resemble dilute gases of uncharged noninteracting point particles described in elementary textbooks. Biological and electrochemical solutions have many components that interact strongly as they flow in concentrated environments near electrodes, ion channels, or active sites of enzymes. Interactions in concentrated environments help determine the characteristic properties of electrodes, enzymes, and ion channels. Flows are driven by a combination of electrical and chemical potentials that depend on the charges, concentrations, and sizes of all ions, not just the same type of ion. We use a variational method EnVarA (energy variational analysis) that combines Hamilton's least action and Rayleigh's dissipation principles to create a variational field theory that includes flow, friction, and complex structure with physical boundary conditions. EnVarA optimizes both the action integral functional of classical mechanics and the dissipation functional. These functionals can include entropy and dissipation as well as potential energy. The stationary point of the action is determined with respect to the trajectory of particles. The stationary point of the dissipation is determined with respect to rate functions (such as velocity). Both variations are written in one Eulerian (laboratory) framework. In variational analysis, an "extra layer" of mathematics is used to derive partial differential equations. Energies and dissipations of different components are combined in EnVarA and Euler-Lagrange equations are then derived. These partial differential equations are the unique consequence of the contributions of individual components. The form and parameters of the partial differential equations are determined by algebra without additional physical content or assumptions. The partial differential equations of mixtures automatically combine physical properties of individual (unmixed) components. If a new

  19. Body Fluid Regulation and Hemopoiesis in Space Flight

    NASA Technical Reports Server (NTRS)

    1997-01-01

    In this session, Session JA2, the discussion focuses on the following topics: Bodymass and Fluid Distribution During Longterm Spaceflight with and without Countermeasures; Plasma Volume, Extracellular Fluid Volume, and Regulatory Hormones During Long-Term Space Flight; Effect of Microgravity and its Ground-Based Models on Fluid Volumes and Hemocirculatory Volumes; Seventeen Weeks of Horizontal Bed Rest, Lower Body Negative Pressure Testing, and the Associated Plasma Volume Response; Evaporative Waterloss in Space Theoretical and Experimental Studies; Erythropoietin Under Real and Simulated Micro-G Conditions in Humans; and Vertebral Bone Marrow Changes Following Space Flight.

  20. Local fluid transfer regulation in heart extracellular matrix.

    PubMed

    McGee, Maria P; Morykwas, Michael J; Jordan, James E; Wang, Rui; Argenta, Louis C

    2016-06-01

    The interstitial myocardial matrix is a complex and dynamic structure that adapts to local fluctuations in pressure and actively contributes to the heart's fluid exchange and hydration. However, classical physiologic models tend to treat it as a passive conduit for water and solute, perhaps because local interstitial regulatory mechanisms are not easily accessible to experiment in vivo. Here, we examined the interstitial contribution to the fluid-driving pressure ex vivo. Interstitial hydration potentials were determined from influx/efflux rates measured in explants from healthy and ischemia-reperfusion-injured pigs during colloid osmotic pressure titrations. Adaptive responses were further explored by isolating myocardial fibroblasts and measuring their contractile responses to water activity changes in vitro. Results show hydration potentials between 5 and 60 mmHg in healthy myocardia and shifts in excess of 200 mmHg in edematous myocardia after ischemia-reperfusion injury. Further, rates of fluid transfer were temperature-dependent, and in collagen gel contraction assays, myocardial fibroblasts tended to preserve the micro-environment's hydration volume by slowing fluid efflux rates at pressures above 40 mmHg. Our studies quantify components of the fluid-driving forces in the heart interstitium that the classical Starling's equation does not explicitly consider. Measured hydration potentials in healthy myocardia and shifts with edema are larger than predicted from the known values of hydrostatic and colloid osmotic interstitial fluid pressures. Together with fibroblast responses in vitro, they are consistent with regulatory mechanisms that add local biological controls to classic fluid-balance models. PMID:26961911

  1. Ionic fluids containing both strongly and weakly interacting ions of the same charge have unique ionic and chemical environments as a function of ion concentration.

    PubMed

    Wang, Hui; Kelley, Steven P; Brantley, Jimmy W; Chatel, Gregory; Shamshina, Julia; Pereira, Jorge F B; Debbeti, Varun; Myerson, Allan S; Rogers, Robin D

    2015-04-01

    Liquid multi-ion systems made by combining two or more salts can exhibit charge ordering and interactions not found in the parent salts, leading to new sets of properties. This is investigated herein by examining a liquid comprised of a single cation, 1-ethyl-3-methylimidazolium ([C2mim](+)), and two anions with different properties, acetate ([OAc](-)) and bis(trifluoromethylsulfonyl)imide ([NTf2](-)). NMR and IR spectroscopy indicate that the electrostatic interactions are quite different from those in either [C2mim][OAc] or [C2mim][NTf2]. This is attributed to the ability of [OAc](-) to form complexes with the [C2mim](+) ions at greater than 1:1 stoichiometries by drawing [C2mim](+) ions away from the less basic [NTf2](-) ions. Solubility studies with molecular solvents (ethyl acetate, water) and pharmaceuticals (ibuprofen, diphenhydramine) show nonlinear trends as a function of ion content, which suggests that solubility can be tuned through changes in the ionic compositions. PMID:25652555

  2. Regulation of tumor invasion by interstitial fluid flow

    NASA Astrophysics Data System (ADS)

    Shieh, Adrian C.; Swartz, Melody A.

    2011-02-01

    The importance of the tumor microenvironment in cancer progression is undisputed, yet the significance of biophysical forces in the microenvironment remains poorly understood. Interstitial fluid flow is a nearly ubiquitous and physiologically relevant biophysical force that is elevated in tumors because of tumor-associated angiogenesis and lymphangiogenesis, as well as changes in the tumor stroma. Not only does it apply physical forces to cells directly, but interstitial flow also creates gradients of soluble signals in the tumor microenvironment, thus influencing cell behavior and modulating cell-cell interactions. In this paper, we highlight our current understanding of interstitial fluid flow in the context of the tumor, focusing on the physical changes that lead to elevated interstitial flow, how cells sense flow and how they respond to changes in interstitial flow. In particular, we emphasize that interstitial flow can directly promote tumor cell invasion through a mechanism known as autologous chemotaxis, and indirectly support tumor invasion via both biophysical and biochemical cues generated by stromal cells. Thus, interstitial fluid flow demonstrates how important biophysical factors are in cancer, both by modulating cell behavior and coupling biophysical and biochemical signals.

  3. Computer simulation studies in fluid and calcium regulation and orthostatic intolerance

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The systems analysis approach to physiological research uses mathematical models and computer simulation. Major areas of concern during prolonged space flight discussed include fluid and blood volume regulation; cardiovascular response during shuttle reentry; countermeasures for orthostatic intolerance; and calcium regulation and bone atrophy. Potential contributions of physiologic math models to future flight experiments are examined.

  4. Seminal Fluid Regulation of Female Sexual Attractiveness in Drosophila melanogaster

    NASA Astrophysics Data System (ADS)

    Tram, Uyen; Wolfner, Mariana F.

    1998-03-01

    Finding a willing and suitable mate is critical for sexual reproduction. Visual, auditory, and chemical cues aid in locating and/or attracting partners. After mating, females from many insect species become less attractive. This is caused by changes in the quantity and/or quality of pheromones synthesized by the female and to changes in the female's behavior. For example, female insects may stop releasing pheromones, assume a mate refusal posture, or move less in response to males. Many postmating changes in female insects are triggered by seminal fluid proteins from the male's accessory gland proteins (Acps) and by sperm. To determine the role of seminal fluid components in mediating changes in attractiveness, we measured the attractiveness of Drosophila melanogaster females that had been mated to genetically altered males that lack sperm and/or Acps. We found that the drop in female attractiveness occurs in two phases. A short-term drop in attractiveness is triggered independent of the receipt of sperm and Acps. Maintenance of lowered attractiveness is dependent upon sperm.

  5. The regulation of fluid and electrolyte metabolism in weightlessness

    NASA Technical Reports Server (NTRS)

    Leach, C. S.; Johnson, P. C.; Cintron, N. M.

    1986-01-01

    Endocrine and biochemical changes in astronauts caused by weightlessness are discussed. Translocation of fluid from the extremities to the head and chest at the onset of weightlessness is thought to lead to the establishment of a lower blood volume as an adaptation to microgravity. Results of Skylab experiments indicate that several other regulatory systems have lower homeostatic set points during space flight. Inflight blood samples from three Spacelab flights show increased antidiuretic hormone throughout these short flights and decreased aldosterone and cortisol after 3 days. Results help to explain blood hypoosmolality and hyponatremia but do not explain what happens between the onset of weightlessness and hormone changes. Other factors such as natriuretic peptides and changes in renal function are being studied to elucidate the physiologic adaptation mechanisms.

  6. Alveolar lining fluid regulates mononuclear phagocyte 5-lipoxygenase metabolism.

    PubMed

    Phare, S M; Peters-Golden, M; Coffey, M J

    1998-11-01

    The enzyme 5-lipoxygenase (5-LO) catalyses the synthesis of leukotrienes (LT), which are important in phagocytosis and killing of microorganisms. The alveolar macrophage (AM), the primary resident defender of the alveolar space, has a greater capacity for LT synthesis than its precursor, the peripheral blood monocyte (PBM). This study investigated whether the alveolar lining fluid (ALF) upregulates LT synthetic capacity in mononuclear phagocytes. Rat AM, peritoneal macrophages (PM) and ALF were obtained by lavage from pathogen-free animals. Human PBM were isolated from normal subjects. 5-LO metabolism and expression were measured with and without ALF. Rat ALF increased 5-LO metabolism (136.4+/-15.1% of control) in cultured PBM. This was associated with increased 5-LO activating protein (FLAP) (357+/-29.5 %), and 5-LO expression (188+/-31.3%). Culture of AM for 3 days resulted in a greater decrement in LTB4 synthesis (LTB4 15.4+/-6.9% of day 1) than in PM (54.7+/-8.3% of day 1), suggesting a greater dependence of AM 5-LO metabolism on ALF. 5-LO and FLAP expression decreased to a greater degree in AM than PM in culture. Furthermore, AM cultured with ALF maintained their LT synthetic capacity, FLAP and 5-LO expression compared with control cells cultured in medium alone. In conclusion, alveolar lining fluid increased 5-lipoxygenase metabolism in peripheral blood monocytes and maintained it in cultured alveolar macrophages, by a mechanism of increased 5-lipoxygenase and 5-lipoxygenase activating protein expression. This may boost host defence capabilities. PMID:9864011

  7. Synthesis of novel ICIE16/BSG and ICIE16/BSG-NITRI bioglasses and description of ionic release kinetics upon immersion in SBF fluid: Effect of nitridation

    PubMed Central

    Orgaz, Felipe; Amat, Daniel; Szycht, Olga; Dzika, Aleksandra; Barba, Flora; Becerra, José; Santos-Ruiz, Leonor

    2015-01-01

    A novel bioactive glass scaffold ICIE16/BSG has been prepared from a mixture of two different melt-derived glasses: a silicate bioglass (ICIE16) and a borosilicate bioglass (BSG). Combined processing techniques (gel casting and foam replication) were used to form three-dimensional, interconnected porous monolith scaffolds (Orgaz et al., 2016) [1]. They were then nitrided with a hot ammonia flow as described in (Aleixandre et al., 1973) [3] and (Nieto, 1984) [4] to synthesize the ICIE16/BSG-NITRI bioglass (Orgaz et al., 2016) [1]. Herein we present a flow chart summarizing the forming process, plus images of the resulting scaffold after sintering and drying. Bioactivity was characterized in vitro by immersion in simulated body fluid (SBF) for up to seven days. Data of ionic release kinetics upon SBF immersion are presented. PMID:26858981

  8. Synthesis of novel ICIE16/BSG and ICIE16/BSG-NITRI bioglasses and description of ionic release kinetics upon immersion in SBF fluid: Effect of nitridation.

    PubMed

    Orgaz, Felipe; Amat, Daniel; Szycht, Olga; Dzika, Aleksandra; Barba, Flora; Becerra, José; Santos-Ruiz, Leonor

    2016-03-01

    A novel bioactive glass scaffold ICIE16/BSG has been prepared from a mixture of two different melt-derived glasses: a silicate bioglass (ICIE16) and a borosilicate bioglass (BSG). Combined processing techniques (gel casting and foam replication) were used to form three-dimensional, interconnected porous monolith scaffolds (Orgaz et al., 2016) [1]. They were then nitrided with a hot ammonia flow as described in (Aleixandre et al., 1973) [3] and (Nieto, 1984) [4] to synthesize the ICIE16/BSG-NITRI bioglass (Orgaz et al., 2016) [1]. Herein we present a flow chart summarizing the forming process, plus images of the resulting scaffold after sintering and drying. Bioactivity was characterized in vitro by immersion in simulated body fluid (SBF) for up to seven days. Data of ionic release kinetics upon SBF immersion are presented. PMID:26858981

  9. Is the solvation parameter model or its adaptations adequate to account for ionic interactions when characterizing stationary phases for drug impurity profiling with supercritical fluid chromatography?

    PubMed

    Galea, Charlene; West, Caroline; Mangelings, Debby; Vander Heyden, Yvan

    2016-06-14

    Nine commercially available polar and aromatic stationary phases were characterized under supercritical fluid chromatographic (SFC) conditions. Retention data of 64 pharmaceutical compounds was acquired to generate models based on the linear solvation energy relationship (LSER) approach. Previously, adaptation of the LSER model was done in liquid chromatography by the addition of two solute descriptors to describe the influence of positive (D(+)) and negative (D(-)) charges on the retention of ionized compounds. In this study, the LSER models, with and without the ionization terms for acidic and basic solutes, were compared. The improved fits obtained for the modified models support inclusion of the D(+) and D(-) terms for pharmaceutical compounds. Moreover, the statistical significance of the new terms in the models indicates the importance of ionic interactions in the retention of pharmaceutical compounds in SFC. However, unlike characterization through the retention profiles, characterization of the stationary phases by modelling never explains the retention variance completely and thus seems less appropriate. PMID:27181639

  10. An emerging role for gasotransmitters in the control of breathing and ionic regulation in fish.

    PubMed

    Perry, Steve; Kumai, Y; Porteus, C S; Tzaneva, V; Kwong, R W M

    2016-02-01

    Three gases comprising nitric oxide, carbon monoxide and hydrogen sulphide, collectively are termed gasotransmitters. The gasotransmitters control several physiological functions in fish by acting as intracellular signaling molecules. Hydrogen sulphide, first implicated in vasomotor control in fish, plays a critical role in oxygen chemoreception owing to its production and downstream effects within the oxygen chemosensory cells, the neuroepithelial cells. Indeed, there is emerging evidence that hydrogen sulphide may contribute to oxygen sensing in both fish and mammals by promoting membrane depolarization of the chemosensory cells. Unlike hydrogen sulphide which stimulates breathing in zebrafish, carbon monoxide inhibits ventilation in goldfish and zebrafish whereas nitric oxide stimulates breathing in zebrafish larvae while inhibiting breathing in adults. Gasotransmitters also modulate ionic uptake in zebrafish. Though nothing is known about the role of CO, reduced activities of branchial Na(+)/K(+)-ATPase and H(+)-ATPase activities in the presence of NO donors suggest an inhibitory role of NO in fish osmoregulation. Hydrogen sulphide inhibits Na(+) uptake in zebrafish larvae and contributes to lowering Na(+) uptake capacity in fish acclimated to Na(+)-enriched water whereas it stimulates Ca(2+) uptake in larvae exposed to Ca(2+)-poor water. PMID:26660653

  11. Regulation of EGFR nanocluster formation by ionic protein-lipid interaction

    PubMed Central

    Wang, Ye; Gao, Jing; Guo, Xingdong; Tong, Ti; Shi, Xiaoshan; Li, Lunyi; Qi, Miao; Wang, Yajie; Cai, Mingjun; Jiang, Junguang; Xu, Chenqi; Ji, Hongbin; Wang, Hongda

    2014-01-01

    The abnormal activation of epidermal growth factor receptor (EGFR) is strongly associated with a variety of human cancers but the underlying molecular mechanism is not fully understood. By using direct stochastic optical reconstruction microscopy (dSTORM), we find that EGFR proteins form nanoclusters in the cell membrane of both normal lung epithelial cells and lung cancer cells, but the number and size of clusters significantly increase in lung cancer cells. The formation of EGFR clusters is mediated by the ionic interaction between the anionic lipid phosphatidylinositol-4,5-bisphosphate (PIP2) in the plasma membrane and the juxtamembrane (JM) region of EGFR. Disruption of EGFR clustering by PIP2 depletion or JM region mutation impairs EGFR activation and downstream signaling. Furthermore, JM region mutation in constitutively active EGFR mutant attenuates its capability of cell transformation. Collectively, our findings highlight the key roles of anionic phospholipids in EGFR signaling and function, and reveal a novel mechanism to explain the aberrant activation of EGFR in cancers. PMID:25001389

  12. Electrostatics in ionic solution : work and energy, charge regulation, and in homogeneous surfaces

    NASA Astrophysics Data System (ADS)

    Boon, N. J. H.

    2012-01-01

    This thesis concerns the electrostatic properties of charged objects that are immersed into an ionic solvent, for example water with dissolved salt. Typically, the ions inside such a solvent form layers of countercharge close to the charged objects, causing `screening' of the charges. By employing Density Functional Theory (DFT) one is able integrate out the degrees of freedom of the ions and find relations that describe the effective electrostatic properties of the charged objects. One finds that for a large parameter regime the electrostatic potential everywhere in the solvent should satisfy the well established Poisson-Boltzmann equation. We study the electrostatic capacity of porous electrodes in salt water, and derive a method to reversibly extract electric energy from salinity gradients that occur for example at an estuary where sea- and river water meet. However, in the main part of this thesis we consider charged colloidal particles, and study the effect of internal porosity as well as heterogeneities in the surface-charge density (patchy particles) on colloid-colloid interactions. In a far-field analysis we derive equations that describe these interactions for particles with nonvanishing multipole moments, for example `Janus' colloids with a strong dipole component. If such particles locally have a high surface charge density, then the nonlinear dependence of the counterion density on the local charge density leads to a generalisation of charge renormalisation from purely monopolar to dipolar, quadrupolar, etc., including `mode couplings'. In a more detailed approach, which turns out to be important for colloidal particles at smaller distances from each other, we consider the chemical processes that lead to surface charge, and specify a parameter regime in which charging can be described by a single `chargeability' parameter. As we show in this thesis, the phase diagrams we obtain within this regime have many similarities with a `constant surface potential

  13. Fluid flow release regulating device, ERIP {number_sign}624: Final report

    SciTech Connect

    1997-12-01

    DOE/ERIP project {number_sign}624 ``Fluid Flow Release Regulating Device`` designed, constructed, tested, and installed a rubber crest gate for regulating water levels at an impoundment such as a hydroelectric dam. A 92 foot long by 27 inch high rubber panel was installed in January 1997. Initial results were good until fabric degradation internal to the rubber caused loss of stiffness. Substitutes for the failed fabric are being tested. The project will continue after DOE participation terminates.

  14. Binary ionic porphyrin nanosheets: electronic and light-harvesting properties regulated by crystal structure

    NASA Astrophysics Data System (ADS)

    Tian, Yongming; M. Beavers, Christine; Busani, Tito; Martin, Kathleen E.; Jacobsen, John L.; Mercado, Brandon Q.; Swartzentruber, Brian S.; van Swol, Frank; Medforth, Craig J.; Shelnutt, John A.

    2012-02-01

    Crystalline solids self-assembled from anionic and cationic porphyrins provide a new class of multifunctional optoelectronic micro- and nanomaterials. A 1 : 1 combination of zinc(ii) tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) and tin(iv) tetra(N-methyl-4-pyridiniumyl)porphyrin (SnTNMePyP) gives porphyrin nanosheets with high aspect ratios and varying thickness. The room temperature preparation of the nanosheets has provided the first X-ray crystal structure of a cooperative binary ionic (CBI) solid. The unit cell contains one and one-half molecules of aquo-ZnTPPS4- (an electron donor) and three half molecules of dihydroxy-SnTNMePyP4+ (an electron acceptor). Charge balance in the solid is reached without any non-porphyrinic ions, as previously determined for other CBI nanomaterials by non-crystallographic means. The crystal structure reveals a complicated molecular arrangement with slipped π-π stacking only occurring in isolated dimers of one of the symmetrically unique zinc porphyrins. Consistent with the crystal structure, UV-visible J-aggregate bands indicative of exciton delocalization and extended π-π stacking are not observed. XRD measurements show that the structure of the Zn/Sn nanosheets is distinct from that of Zn/Sn four-leaf clover-like CBI solids reported previously. In contrast with the Zn/Sn clovers that do exhibit J-aggregate bands and are photoconductive, the nanosheets are not photoconductive. Even so, the nanosheets act as light-harvesting structures in an artificial photosynthesis system capable of reducing water to hydrogen but not as efficiently as the Zn/Sn clovers.Crystalline solids self-assembled from anionic and cationic porphyrins provide a new class of multifunctional optoelectronic micro- and nanomaterials. A 1 : 1 combination of zinc(ii) tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) and tin(iv) tetra(N-methyl-4-pyridiniumyl)porphyrin (SnTNMePyP) gives porphyrin nanosheets with high aspect ratios and varying thickness. The room

  15. Embryonic cerebrospinal fluid regulates neuroepithelial survival, proliferation, and neurogenesis in chick embryos.

    PubMed

    Gato, Angel; Moro, J A; Alonso, M I; Bueno, D; De La Mano, A; Martín, C

    2005-05-01

    Early in development, the behavior of neuroepithelial cells is controlled by several factors, which act in a developmentally regulated manner. Diffusible factors are secreted locally by the neuroepithelium itself, although other nearby structures may also be involved. Evidence suggests a physiological role for the cerebrospinal fluid in the development of the brain. Here, using organotypic cultures of chick embryo neuroepithelial explants from the mesencephalon, we show that the neuroepithelium in vitro is not able to self-induce cell survival, replication, and neurogenesis. We also show that the embryonic cerebrospinal fluid (E-CSF) promotes neuroepithelial stem cell survival and induces proliferation and neurogenesis in mesencephalic explants. These data strongly suggest that E-CSF is involved in the regulation of neuroepithelial cells behavior, supporting the hypothesis that this fluid plays a key role during the early development of the central nervous system. PMID:15803475

  16. Long Term Thermal Stability In Air Of Ionic Liquid Based Alternative Heat Transfer Fluids For Clean Energy Production

    SciTech Connect

    Fox, Elise B; Kendrick, Sarah E.; Visser, Ann E.; Bridges, Nicholas J.

    2012-10-15

    The purpose of this study was to investigate the effect of long-term aging on the thermal stability and chemical structure of seven different ILs so as to explore their suitability for use as a heat transfer fluid. This was accomplished by heating the ILs for 15 weeks at 200°C in an oxidizing environment and performing subsequent analyses on the aged chemicals.

  17. Mathematical modelling of fluid transport and its regulation at multiple scales.

    PubMed

    Chara, Osvaldo; Brusch, Lutz

    2015-04-01

    Living matter equals water, to a first approximation, and water transport across barriers such as membranes and epithelia is vital. Water serves two competing functions. On the one hand, it is the fundamental solvent enabling random mobility of solutes and therefore biochemical reactions and intracellular signal propagation. Homeostasis of the intracellular water volume is required such that messenger concentration encodes the stimulus and not inverse volume fluctuations. On the other hand, water flow is needed for transport of solutes to and away from cells in a directed manner, threatening volume homeostasis and signal transduction fidelity of cells. Feedback regulation of fluid transport reconciles these competing objectives. The regulatory mechanisms often span across multiple spatial scales from cellular interactions up to the architecture of organs. Open questions relate to the dependency of water fluxes and steady state volumes on control parameters and stimuli. We here review selected mathematical models of feedback regulation of fluid transport at the cell scale and identify a general "core-shell" structure of such models. We propose that fluid transport models at other spatial scales can be constructed in a generalised core-shell framework, in which the core accounts for the biophysical effects of fluid transport whilst the shell reflects the regulatory mechanisms. We demonstrate the applicability of this framework for tissue lumen growth and suggest future experiments in zebrafish to test lumen size regulation mechanisms. PMID:25666503

  18. Regulation of ionic conductances and gene expression by hypoxia in an oxygen sensitive cell line.

    PubMed

    Millhorn, D E; Conforti, L; Beitner-Johnson, D; Zhu, W; Raymond, R; Filisko, T; Kobayashi, S; Peng, M; Genter, M B

    1996-01-01

    We have shown that the PC12 cell line is an excellent model system for investigations of the molecular and cellular processes involved in O2-chemosensitivity. We have identified an O2-sensitive K channel in this cell line that mediates membrane depolarization, an increase in intracellular free Ca2+, and dopamine release during hypoxia. We also presented evidence which shows that expression of the gene for tyrosine hydroxylase, the rate-limiting enzyme in dopamine biosynthesis, is stimulated by reduced O2 tension in PC12 and type I carotid body cells. In addition, we have successfully identified the DNA sequences and trans-acting protein factors that regulate transcription of the TH gene during hypoxia. The mechanisms by which a reduction in O2 tension is transduced into alter cell function including increased gene expression remain unknown. Unpublished results from our laboratory show that the increased TH gene expression during hypoxia does not require activation of the cAMP-PKA signal transduction pathway. We propose that the increase in intracellular free Ca2+ that occurs as a result of membrane depolarization might play an important role. Preliminary findings from our laboratory show that blockade of the voltage operated Ca2+ channel or chelation of intracellular Ca2+ prevent full activation of the TH gene during hypoxia. PMID:9030290

  19. Fluid shear stress regulates metalloproteinase-1 and 2 in human periodontal ligament cells: involvement of extracellular signal-regulated kinase (ERK) and P38 signaling pathways.

    PubMed

    Zheng, Lisha; Huang, Yan; Song, Wei; Gong, Xianghui; Liu, Meili; Jia, Xiaolin; Zhou, Gang; Chen, Luoping; Li, Ang; Fan, Yubo

    2012-09-21

    Matrix metalloproteinase (MMP)-1, 2, with their endogenous inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1, 2 are critical for extracellular matrix remodeling in human periodontal ligament (PDL) and their expression are sensitive to mechanical stresses. Shear stress as the main type of mechanical stress in tooth movement is involved in matrix turnover. However, how shear stress regulates MMPs and TIMPs system is still unclear. In this study, we investigated the effect of fluid shear stress on expression of MMP-1, 2 and TIMP-1, 2 in human PDL cells and the possible roles of mitogen-activated protein kinases in this process. Three levels of fluid shear stresses (6, 9 and 12 dyn/cm(2)) were loaded on PDL cells for 2, 4, 8 and 12h. The results indicated that fluid shear stress rearranged cytoskeleton in PDL cells. Fluid shear stress increased expression of MMP-1, 2, TIMP-1 and suppressed TIMP-2 expression. MAP kinases including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 were activated rapidly by fluid shear stress. The ERK inhibitor blocked fluid shear stress induced MMP-1 expression and P38 inhibitor reduced fluid shear stress stimulated MMP-2 expression. Our study suggested that fluid shear stress involved in PDL remodeling via regulating MMP-1, 2 and TIMP-1, 2 expression. ERK regulated fluid shear stress induced MMP-1 expression and P38 play a role in fluid shear stress induced MMP-2 upregulation. PMID:22863019

  20. Modeling the [NTf2] pyridinium ionic liquids family and their mixtures with the soft statistical associating fluid theory equation of state.

    PubMed

    Oliveira, M B; Llovell, F; Coutinho, J A P; Vega, L F

    2012-08-01

    In this work, the soft statistical associating fluid theory (soft-SAFT) equation of state (EoS) has been used to provide an accurate thermodynamic characterization of the pyridinium-based family of ionic liquids (ILs) with the bis(trifluoromethylsulfonyl)imide anion [NTf(2)](-). On the basis of recent molecular simulation studies for this family, a simple molecular model was proposed within the soft-SAFT EoS framework. The chain length value was transferred from the equivalent imidazolium-based ILs family, while the dispersive energy and the molecular parameters describing the cation-anion interactions were set to constant values for all of the compounds. With these assumptions, an appropriate set of molecular parameters was found for each compound fitting to experimental temperature-density data at atmospheric pressure. Correlations for the nonconstant parameters (describing the volume of the IL) with the molecular weight were established, allowing the prediction of the parameters for other pyridiniums not included in the fitting. Then, the suitability of the proposed model and its optimized parameters were tested by predicting high-pressure densities and second-order thermodynamic derivative properties such as isothermal compressibilities of selected [NTf(2)] pyridinium ILs, in a large range of thermodynamic conditions. The surface tension was also provided using the density gradient theory coupled to the soft-SAFT equation. Finally, the soft-SAFT EoS was applied to describe the phase behavior of several binary mixtures of [NTf(2)] pyridinium ILs with carbon dioxide, sulfur dioxide, and water. In all cases, a temperature-independent binary parameter was enough to reach quantitative agreement with the experimental data. The description of the solubility of CO(2) in these ILs also allowed identification of a relation between the binary parameter and the molecular weight of the ionic liquid, allowing the prediction of the CO(2) + C(12)py[NTf(2)] mixture. The good

  1. Impact of synovial fluid flow on temperature regulation in knee cartilage.

    PubMed

    Moghadam, Mohamadreza Nassajian; Abdel-Sayed, Philippe; Camine, Valérie Malfroy; Pioletti, Dominique P

    2015-01-21

    Several studies have reported an increase of temperature in cartilage submitted to cyclic sinusoidal loading. The temperature increase is in part due to the viscous behavior of this tissue, which partially dissipates the input mechanical energy into heat. While the synovial fluid flow within the intra-articular gap and inside the porous cartilage is supposed to play an important role in the regulation of the cartilage temperature, no specific study has evaluated this aspect. In the present numerical study, a poroelastic model of the knee cartilage is developed to evaluate first the temperature increase in the cartilage due to dissipation and second the impact of the synovial fluid flow in the cartilage heat transfer phenomenon. Our results showed that, the local temperature is effectively increased in knee cartilage due to its viscous behavior. The synovial fluid flow cannot significantly preventing this phenomenon. We explain this result by the low permeability of cartilage and the moderate fluid exchange at the surface of cartilage under deformation. PMID:25488136

  2. Regulation of amniotic fluid volume: mathematical model based on intramembranous transport mechanisms

    PubMed Central

    Anderson, Debra F.; Cheung, Cecilia Y.

    2014-01-01

    Experimentation in late-gestation fetal sheep has suggested that regulation of amniotic fluid (AF) volume occurs primarily by modulating the rate of intramembranous transport of water and solutes across the amnion into underlying fetal blood vessels. In order to gain insight into intramembranous transport mechanisms, we developed a computer model that allows simulation of experimentally measured changes in AF volume and composition over time. The model included fetal urine excretion and lung liquid secretion as inflows into the amniotic compartment plus fetal swallowing and intramembranous absorption as outflows. By using experimental flows and solute concentrations for urine, lung liquid, and swallowed fluid in combination with the passive and active transport mechanisms of the intramembranous pathway, we simulated AF responses to basal conditions, intra-amniotic fluid infusions, fetal intravascular infusions, urine replacement, and tracheoesophageal occlusion. The experimental data are consistent with four intramembranous transport mechanisms acting in concert: 1) an active unidirectional bulk transport of AF with all dissolved solutes out of AF into fetal blood presumably by vesicles; 2) passive bidirectional diffusion of solutes, such as sodium and chloride, between fetal blood and AF; 3) passive bidirectional water movement between AF and fetal blood; and 4) unidirectional transport of lactate into the AF. Further, only unidirectional bulk transport is dynamically regulated. The simulations also identified areas for future study: 1) identifying intramembranous stimulators and inhibitors, 2) determining the semipermeability characteristics of the intramembranous pathway, and 3) characterizing the vesicles that are the primary mediators of intramembranous transport. PMID:25186112

  3. Regulation of amniotic fluid volume: mathematical model based on intramembranous transport mechanisms.

    PubMed

    Brace, Robert A; Anderson, Debra F; Cheung, Cecilia Y

    2014-11-15

    Experimentation in late-gestation fetal sheep has suggested that regulation of amniotic fluid (AF) volume occurs primarily by modulating the rate of intramembranous transport of water and solutes across the amnion into underlying fetal blood vessels. In order to gain insight into intramembranous transport mechanisms, we developed a computer model that allows simulation of experimentally measured changes in AF volume and composition over time. The model included fetal urine excretion and lung liquid secretion as inflows into the amniotic compartment plus fetal swallowing and intramembranous absorption as outflows. By using experimental flows and solute concentrations for urine, lung liquid, and swallowed fluid in combination with the passive and active transport mechanisms of the intramembranous pathway, we simulated AF responses to basal conditions, intra-amniotic fluid infusions, fetal intravascular infusions, urine replacement, and tracheoesophageal occlusion. The experimental data are consistent with four intramembranous transport mechanisms acting in concert: 1) an active unidirectional bulk transport of AF with all dissolved solutes out of AF into fetal blood presumably by vesicles; 2) passive bidirectional diffusion of solutes, such as sodium and chloride, between fetal blood and AF; 3) passive bidirectional water movement between AF and fetal blood; and 4) unidirectional transport of lactate into the AF. Further, only unidirectional bulk transport is dynamically regulated. The simulations also identified areas for future study: 1) identifying intramembranous stimulators and inhibitors, 2) determining the semipermeability characteristics of the intramembranous pathway, and 3) characterizing the vesicles that are the primary mediators of intramembranous transport. PMID:25186112

  4. Correlation of Apical Fluid-Regulating Channel Proteins with Lung Function in Human COPD Lungs

    PubMed Central

    Zhao, Meimi; Liu, Shan-Lu; Huang, Yao; Idell, Steven; Li, Xiumin; Ji, Hong-Long

    2014-01-01

    Links between epithelial ion channels and chronic obstructive pulmonary diseases (COPD) are emerging through animal model and in vitro studies. However, clinical correlations between fluid-regulating channel proteins and lung function in COPD remain to be elucidated. To quantitatively measure epithelial sodium channels (ENaC), cystic fibrosis transmembrane conductance regulator (CFTR), and aquaporin 5 (AQP5) proteins in human COPD lungs and to analyze the correlation with declining lung function, quantitative western blots were used. Spearman tests were performed to identify correlations between channel proteins and lung function. The expression of α and β ENaC subunits was augmented and inversely associated with lung function. In contrast, both total and alveolar type I (ATI) and II (ATII)-specific CFTR proteins were reduced. The expression level of CFTR proteins was associated with FEV1 positively. Abundance of AQP5 proteins and extracellular superoxide dismutase (SOD3) was decreased and correlated with spirometry test results and gas exchange positively. Furthermore, these channel proteins were significantly associated with severity of disease. Our study demonstrates that expression of ENaC, AQP5, and CFTR proteins in human COPD lungs is quantitatively associated with lung function and severity of COPD. These apically located fluid-regulating channels may thereby serve as biomarkers and potent druggable targets of COPD. PMID:25329998

  5. Hormonal regulation of fluid and electrolyte metabolism in zero-g and bedrest

    NASA Technical Reports Server (NTRS)

    Vernikos, Joan

    1991-01-01

    The study of man in spaceflight has consistently indicated changes in fluid and electrolyte balance. Sodium (Na), Potassium (K), and Calcium (Ca) excretion are increased, accompanied by changes in the levels and responsiveness of adrenal hormones and the sympathetic nervous system (SNS). These hormones and neurohumors are critical to the regulation of blood pressure, blood flow, and blood volume. The primary objectives of the research conducted under this task have been to use -6 deg head down bedrest (BR) as the analog to spaceflight, to determine the long term changes in these systems, their relationship to orthostatic tolerance, and to develop and test suitable countermeasures.

  6. Embryonic cerebrospinal fluid collaborates with the isthmic organizer to regulate mesencephalic gene expression.

    PubMed

    Parada, Carolina; Martín, Cristina; Alonso, María I; Moro, José A; Bueno, David; Gato, Angel

    2005-11-01

    Early in development, the behavior of neuroepithelial cells is controlled by several factors acting in a developmentally regulated manner. Recently it has been shown that diffusible factors contained within embryonic cerebrospinal fluid (CSF) promote neuroepithelial cell survival, proliferation, and neurogenesis in mesencephalic explants lacking any known organizing center. In this paper, we show that mesencephalic and mesencephalic+isthmic organizer explants cultured only with basal medium do not express the typically expressed mesencephalic or isthmic organizer genes analyzed (otx2 and fgf8, respectively) and that mesencephalic explants cultured with embryonic CSF-supplemented medium do effect such expression, although they exhibit an altered pattern of gene expression, including ectopic shh expression domains. Other trophic sources that are able to maintain normal neuroepithelial cell behavior, i.e., fibroblast growth factor-2, fail to activate this ectopic shh expression. Conversely, the expression pattern of the analyzed genes in mesencephalic+isthmic organizer explants cultured with embryonic cerebrospinal fluid-supplemented medium mimics the pattern for control embryos developed in ovo. We demonstrate that embryonic CSF collaborates with the isthmic organizer in regulation of the expression pattern of some characteristic neuroectodermal genes during early stages of central nervous system (CNS) development, and we suggest that this collaboration is not restricted to the maintenance of neuroepithelial cell survival. Data reported in this paper corroborate the hypothesis that factors contained within embryonic CSF contribute to the patterning of the CNS during early embryonic development. PMID:16180222

  7. Role of epithelial sodium channels in the regulation of lung fluid homeostasis.

    PubMed

    Matalon, Sadis; Bartoszewski, Rafal; Collawn, James F

    2015-12-01

    In utero, fetal lung epithelial cells actively secrete Cl(-) ions into the lung air spaces while Na(+) ions follow passively to maintain electroneutrality. This process, driven by an electrochemical gradient generated by the Na(+)-K(+)-ATPase, is responsible for the secretion of fetal fluid that is essential for normal lung development. Shortly before birth, a significant upregulation of amiloride-sensitive epithelial channels (ENaCs) on the apical side of the lung epithelial cells results in upregulation of active Na(+) transport. This process is critical for the reabsorption of fetal lung fluid and the establishment of optimum gas exchange. In the adult lung, active Na(+) reabsorption across distal lung epithelial cells limits the degree of alveolar edema in patients with acute lung injury and cardiogenic edema. Cl(-) ions are transported either paracellularly or transcellularly to preserve electroneutrality. An increase in Cl(-) secretion across the distal lung epithelium has been reported following an acute increase in left atrial pressure and may result in pulmonary edema. In contrast, airway epithelial cells secrete Cl(-) through apical cystic fibrosis transmembrane conductance regulator and Ca(2+)-activated Cl(-) channels and absorb Na(+). Thus the coordinated action of Cl(-) secretion and Na(+) absorption is essential for maintenance of the volume of epithelial lining fluid that, in turn, maximizes mucociliary clearance and facilitates clearance of bacteria and debris from the lungs. Any factor that interferes with Na(+) or Cl(-) transport or dramatically upregulates ENaC activity in airway epithelial cells has been associated with lung diseases such as cystic fibrosis or chronic obstructive lung disease. In this review we focus on the role of the ENaC, the mechanisms involved in ENaC regulation, and how ENaC dysregulation can lead to lung pathology. PMID:26432872

  8. Ionic Blocks

    ERIC Educational Resources Information Center

    Sevcik, Richard S.; Gamble, Rex; Martinez, Elizabet; Schultz, Linda D.; Alexander, Susan V.

    2008-01-01

    "Ionic Blocks" is a teaching tool designed to help middle school students visualize the concepts of ions, ionic compounds, and stoichiometry. It can also assist high school students in reviewing their subject mastery. Three dimensional blocks are used to represent cations and anions, with color indicating charge (positive or negative) and size…

  9. Fluid cognitive ability is a resource for successful emotion regulation in older and younger adults.

    PubMed

    Opitz, Philipp C; Lee, Ihno A; Gross, James J; Urry, Heather L

    2014-01-01

    The Selection, Optimization, and Compensation with Emotion Regulation (SOC-ER) framework suggests that (1) emotion regulation (ER) strategies require resources and that (2) higher levels of relevant resources may increase ER success. In the current experiment, we tested the specific hypothesis that individual differences in one internal class of resources, namely cognitive ability, would contribute to greater success using cognitive reappraisal (CR), a form of ER in which one reinterprets the meaning of emotion-eliciting situations. To test this hypothesis, 60 participants (30 younger and 30 older adults) completed standardized neuropsychological tests that assess fluid and crystallized cognitive ability, as well as a CR task in which participants reinterpreted the meaning of sad pictures in order to alter (increase or decrease) their emotions. In a control condition, they viewed the pictures without trying to change how they felt. Throughout the task, we indexed subjective emotional experience (self-reported ratings of emotional intensity), expressive behavior (corrugator muscle activity), and autonomic physiology (heart rate and electrodermal activity) as measures of emotional responding. Multilevel models were constructed to explain within-subjects variation in emotional responding as a function of ER contrasts comparing increase or decrease conditions with the view control condition and between-subjects variation as a function of cognitive ability and/or age group (older, younger). As predicted, higher fluid cognitive ability-indexed by perceptual reasoning, processing speed, and working memory-was associated with greater success using reappraisal to alter emotional responding. Reappraisal success did not vary as a function of crystallized cognitive ability or age group. Collectively, our results provide support for a key tenet of the SOC-ER framework that higher levels of relevant resources may confer greater success at emotion regulation. PMID:24987387

  10. Fluid cognitive ability is a resource for successful emotion regulation in older and younger adults

    PubMed Central

    Opitz, Philipp C.; Lee, Ihno A.; Gross, James J.; Urry, Heather L.

    2014-01-01

    The Selection, Optimization, and Compensation with Emotion Regulation (SOC-ER) framework suggests that (1) emotion regulation (ER) strategies require resources and that (2) higher levels of relevant resources may increase ER success. In the current experiment, we tested the specific hypothesis that individual differences in one internal class of resources, namely cognitive ability, would contribute to greater success using cognitive reappraisal (CR), a form of ER in which one reinterprets the meaning of emotion-eliciting situations. To test this hypothesis, 60 participants (30 younger and 30 older adults) completed standardized neuropsychological tests that assess fluid and crystallized cognitive ability, as well as a CR task in which participants reinterpreted the meaning of sad pictures in order to alter (increase or decrease) their emotions. In a control condition, they viewed the pictures without trying to change how they felt. Throughout the task, we indexed subjective emotional experience (self-reported ratings of emotional intensity), expressive behavior (corrugator muscle activity), and autonomic physiology (heart rate and electrodermal activity) as measures of emotional responding. Multilevel models were constructed to explain within-subjects variation in emotional responding as a function of ER contrasts comparing increase or decrease conditions with the view control condition and between-subjects variation as a function of cognitive ability and/or age group (older, younger). As predicted, higher fluid cognitive ability—indexed by perceptual reasoning, processing speed, and working memory—was associated with greater success using reappraisal to alter emotional responding. Reappraisal success did not vary as a function of crystallized cognitive ability or age group. Collectively, our results provide support for a key tenet of the SOC-ER framework that higher levels of relevant resources may confer greater success at emotion regulation. PMID:24987387

  11. Mechanisms of proximal tubule sodium transport regulation that link extracellular fluid volume and blood pressure.

    PubMed

    McDonough, Alicia A

    2010-04-01

    One-hundred years ago, Starling articulated the interdependence of renal control of circulating blood volume and effective cardiac performance. During the past 25 years, the molecular mechanisms responsible for the interdependence of blood pressure (BP), extracellular fluid volume (ECFV), the renin-angiotensin system (RAS), and sympathetic nervous system (SNS) have begun to be revealed. These variables all converge on regulation of renal proximal tubule (PT) sodium transport. The PT reabsorbs two-thirds of the filtered Na(+) and volume at baseline. This fraction is decreased when BP or perfusion pressure is increased, during a high-salt diet (elevated ECFV), and during inhibition of the production of ANG II; conversely, this fraction is increased by ANG II, SNS activation, and a low-salt diet. These variables all regulate the distribution of the Na(+)/H(+) exchanger isoform 3 (NHE3) and the Na(+)-phosphate cotransporter (NaPi2), along the apical microvilli of the PT. Natriuretic stimuli provoke the dynamic redistribution of these transporters along with associated regulators, molecular motors, and cytoskeleton-associated proteins to the base of the microvilli. The lipid raft-associated NHE3 remains at the base, and the nonraft-associated NaPi2 is endocytosed, culminating in decreased Na(+) transport and increased PT flow rate. Antinatriuretic stimuli return the same transporters and regulators to the body of the microvilli associated with an increase in transport activity and decrease in PT flow rate. In summary, ECFV and BP homeostasis are, at least in part, maintained by continuous and acute redistribution of transporter complexes up and down the PT microvilli, which affect regulation of PT sodium reabsorption in response to fluctuations in ECFV, BP, SNS, and RAS. PMID:20106993

  12. Regulation of cerebrospinal fluid (CSF) flow in neurodegenerative, neurovascular and neuroinflammatory disease.

    PubMed

    Simon, Matthew J; Iliff, Jeffrey J

    2016-03-01

    Cerebrospinal fluid (CSF) circulation and turnover provides a sink for the elimination of solutes from the brain interstitium, serving an important homeostatic role for the function of the central nervous system. Disruption of normal CSF circulation and turnover is believed to contribute to the development of many diseases, including neurodegenerative conditions such as Alzheimer's disease, ischemic and traumatic brain injury, and neuroinflammatory conditions such as multiple sclerosis. Recent insights into CSF biology suggesting that CSF and interstitial fluid exchange along a brain-wide network of perivascular spaces termed the 'glymphatic' system suggest that CSF circulation may interact intimately with glial and vascular function to regulate basic aspects of brain function. Dysfunction within this glial vascular network, which is a feature of the aging and injured brain, is a potentially critical link between brain injury, neuroinflammation and the development of chronic neurodegeneration. Ongoing research within this field may provide a powerful new framework for understanding the common links between neurodegenerative, neurovascular and neuroinflammatory disease, in addition to providing potentially novel therapeutic targets for these conditions. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger. PMID:26499397

  13. Paradoxes of body fluid volume regulation in health and disease. A unifying hypothesis.

    PubMed Central

    Schrier, R W; Niederberger, M

    1994-01-01

    The body's normal homeostasis is maintained by the integrity of the excretory capacity of the kidneys. In advanced cardiac failure, however, the avidity of the renal sodium and water retention contributes to the occurrence of pulmonary congestion and peripheral edema. In patients with advanced cirrhosis, the kidneys again fail to excrete the amounts of sodium and water ingested, thus leading to ascites and peripheral edema. The signals for this renal retention of sodium and water in a patient with cirrhosis must be extrarenal because when the same kidneys are transplanted into persons with normal liver function, renal sodium and water retention no longer occurs; rather, the kidneys maintain normal fluid and electrolyte balance. Excessive sodium and water retention by the kidneys also occurs during pregnancy despite a 30% to 50% increase in plasma volume, cardiac output, and glomerular filtration rate. What are the afferent and efferent signals whereby normal kidneys retain sodium and water so that total extracellular, interstitial, and intravascular volumes expand far beyond those limits observed in normal subjects? These dilemmas are the subject of this review, in which a "unifying hypothesis of body fluid volume regulation" is presented. PMID:7817551

  14. Role of fluid shear stress in regulating VWF structure, function and related blood disorders

    PubMed Central

    Gogia, Shobhit; Neelamegham, Sriram

    2015-01-01

    Von Willebrand factor (VWF) is the largest glycoprotein in blood. It plays a crucial role in primary hemostasis via its binding interaction with platelet and endothelial cell surface receptors, other blood proteins and extra-cellular matrix components. This protein is found as a series of repeat units that are disulfide bonded to form multimeric structures. Once in blood, the protein multimer distribution is dynamically regulated by fluid shear stress which has two opposing effects: it promotes the aggregation or self-association of multiple VWF units, and it simultaneously reduces multimer size by facilitating the force-dependent cleavage of the protein by various proteases, most notably ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type repeats, motif 1 type 13). In addition to these effects, fluid shear also controls the solution and substrate-immobilized structure of VWF, the nature of contact between blood platelets and substrates, and the biomechanics of the GpIbα–VWF bond. These features together regulate different physiological and pathological processes including normal hemostasis, arterial and venous thrombosis, von Willebrand disease, thrombotic thrombocytopenic purpura and acquired von Willebrand syndrome. This article discusses current knowledge of VWF structure–function relationships with emphasis on the effects of hydrodynamic shear, including rapid methods to estimate the nature and magnitude of these forces in selected conditions. It shows that observations made by many investigators using solution and substrate-based shearing devices can be reconciled upon considering the physical size of VWF and the applied mechanical force in these different geometries. PMID:26600266

  15. Role of fluid shear stress in regulating VWF structure, function and related blood disorders.

    PubMed

    Gogia, Shobhit; Neelamegham, Sriram

    2015-01-01

    Von Willebrand factor (VWF) is the largest glycoprotein in blood. It plays a crucial role in primary hemostasis via its binding interaction with platelet and endothelial cell surface receptors, other blood proteins and extra-cellular matrix components. This protein is found as a series of repeat units that are disulfide bonded to form multimeric structures. Once in blood, the protein multimer distribution is dynamically regulated by fluid shear stress which has two opposing effects: it promotes the aggregation or self-association of multiple VWF units, and it simultaneously reduces multimer size by facilitating the force-dependent cleavage of the protein by various proteases, most notably ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type repeats, motif 1 type 13). In addition to these effects, fluid shear also controls the solution and substrate-immobilized structure of VWF, the nature of contact between blood platelets and substrates, and the biomechanics of the GpIbα-VWF bond. These features together regulate different physiological and pathological processes including normal hemostasis, arterial and venous thrombosis, von Willebrand disease, thrombotic thrombocytopenic purpura and acquired von Willebrand syndrome. This article discusses current knowledge of VWF structure-function relationships with emphasis on the effects of hydrodynamic shear, including rapid methods to estimate the nature and magnitude of these forces in selected conditions. It shows that observations made by many investigators using solution and substrate-based shearing devices can be reconciled upon considering the physical size of VWF and the applied mechanical force in these different geometries. PMID:26600266

  16. Phosphodiesterase Isoform Regulation of Cell Proliferation and Fluid Secretion in Autosomal Dominant Polycystic Kidney Disease.

    PubMed

    Pinto, Cibele S; Raman, Archana; Reif, Gail A; Magenheimer, Brenda S; White, Corey; Calvet, James P; Wallace, Darren P

    2016-04-01

    cAMP stimulates cell proliferation and Cl(-)-dependent fluid secretion, promoting the progressive enlargement of renal cysts in autosomal dominant polycystic kidney disease (ADPKD). Intracellular cAMP levels are determined by the balance of cAMP synthesis by adenylyl cyclases and degradation by phosphodiesterases (PDEs). Therefore, PDE isoform expression and activity strongly influence global and compartmentalized cAMP levels. We report here that PDE3 and PDE4 expression levels are lower in human ADPKD tissue and cells compared with those of normal human kidneys (NHKs), whereas PDE1 levels are not significantly different. Inhibition of PDE4 caused a greater increase in basal and vasopressin (AVP)-stimulated cAMP levels and Cl(-) secretion by ADPKD cells than inhibition of PDE1, and inhibition of PDE4 induced cyst-like dilations in cultured mouse Pkd1(-/-) embryonic kidneys. In contrast, inhibition of PDE1 caused greater stimulation of extracellular signal-regulated kinase (ERK) and proliferation of ADPKD cells than inhibition of PDE4, and inhibition of PDE1 enhanced AVP-induced ERK activation. Notably, inhibition of PDE1, the only family of Ca(2+)-regulated PDEs, also induced a mitogenic response to AVP in NHK cells, similar to the effect of restricting intracellular Ca(2+). PDE1 coimmunoprecipitated with B-Raf and A-kinase anchoring protein 79, and AVP increased this interaction in ADPKD but not NHK cells. These data suggest that whereas PDE4 is the major PDE isoform involved in the regulation of global intracellular cAMP and Cl(-) secretion, PDE1 specifically affects the cAMP signal to the B-Raf/MEK/ERK pathway and regulates AVP-induced proliferation of ADPKD cells. PMID:26289612

  17. Magnesium as a regulator of thrombin formation in bovine ovarian follicular fluid.

    PubMed

    Yamada, M; Hirakushi, K; Inoue, K; Horiuchi, T; Sakai, J; Okada, T; Sugie, I

    1998-07-01

    In the ovarian follicular fluid (FF) of Holstein cows, calcium (Ca) and magnesium (Mg) levels and their roles on thrombin generation were examined and compared with the blood samples. Total Ca levels in FF increased while the total Mg levels decreased with follicular development from preantral to preovulatory stage of follicles. These changes resulted in Ca values being significantly (p < 0.05) higher in FF from the most developed follicles and the Mg values being significantly higher (p < 0.05) in the least developed follicles. To determine whether the high level of Mg might function to regulate thrombin generation in FF as occurs in plasma, the influence of Mg supplementation of FF from various types of follicles was examined. In FF from small size follicles, Mg accelerated the prothrombin time, an estimation of the overall rate of thrombin production, although a similar effects was not observed in FF from medium and large size follicles. The addition of Mg to FF from all sizes of follicles resulted an inhibition in factor X activation. Since activation of factor X is a precursor step for thrombin formation it is concluded that Mg can function as a slow accelerator of thrombin generation in FF from follicles at the antral stage of development. It is likely to have a more important role in regulating the rate of thrombin generation as the follicle develops. PMID:9713812

  18. Regulated traffic of anion transporters in mammalian Brunner's glands: a role for water and fluid transport

    PubMed Central

    Collaco, Anne M.; Jakab, Robert L.; Hoekstra, Nadia E.; Mitchell, Kisha A.; Brooks, Amos

    2013-01-01

    The Brunner's glands of the proximal duodenum exert barrier functions through secretion of glycoproteins and antimicrobial peptides. However, ion transporter localization, function, and regulation in the glands are less clear. Mapping the subcellular distribution of transporters is an important step toward elucidating trafficking mechanisms of fluid transport in the gland. The present study examined 1) changes in the distribution of intestinal anion transporters and the aquaporin 5 (AQP5) water channel in rat Brunner's glands following second messenger activation and 2) anion transporter distribution in Brunner's glands from healthy and disease-affected human tissues. Cystic fibrosis transmembrane conductance regulator (CFTR), AQP5, sodium-potassium-coupled chloride cotransporter 1 (NKCC1), sodium-bicarbonate cotransporter (NBCe1), and the proton pump vacuolar ATPase (V-ATPase) were localized to distinct membrane domains and in endosomes at steady state. Carbachol and cAMP redistributed CFTR to the apical membrane. cAMP-dependent recruitment of CFTR to the apical membrane was accompanied by recruitment of AQP5 that was reversed by a PKA inhibitor. cAMP also induced apical trafficking of V-ATPase and redistribution of NKCC1 and NBCe1 to the basolateral membranes. The steady-state distribution of AQP5, CFTR, NBCe1, NKCC1, and V-ATPase in human Brunner's glands from healthy controls, cystic fibrosis, and celiac disease resembled that of rat; however, the distribution profiles were markedly attenuated in the disease-affected duodenum. These data support functional transport of chloride, bicarbonate, water, and protons by second messenger-regulated traffic in mammalian Brunner's glands under physiological and pathophysiological conditions. PMID:23744739

  19. A noninvasive method to study regulation of extracellular fluid volume in rats using nuclear magnetic resonance.

    PubMed

    Gordon, Christopher J; Phillips, Pamela M; Johnstone, Andrew F M

    2016-03-01

    Time-domain nuclear magnetic resonance (TD-NMR)-based measurement of body composition of rodents is an effective method to quickly and repeatedly measure proportions of fat, lean, and fluid without anesthesia. TD-NMR provides a measure of free water in a living animal, termed %fluid, and is a measure of unbound water in the vascular and extracellular spaces. We hypothesized that injecting a bolus of fluid into the peritoneal cavity would lead to an abrupt increase in %fluid and the rate of clearance monitored with TD-NMR would provide a noninvasive assessment of the free water homeostasis in an awake rat. Several strains of laboratory rats were injected intraperitoneally with 10 ml/kg isotonic or hypertonic saline and %fluid was monitored repeatedly with a Bruker "Minispec" TD-NMR body composition system. Following isotonic saline, %fluid increased immediately by 0.5% followed by a recovery over ∼6 h. Injecting hypertonic (3 times normal saline) resulted in a significantly greater rise in %fluid and longer recovery. Intraperitoneal and subcutaneous fluid injection led to similar rates of clearance. The Wistar-Kyoto rat strain displayed significantly slower recovery to fluid loads compared with Long-Evans and Sprague-Dawley strains. Rats exercised chronically showed significant increases in %fluid, but the rate of clearance of fluid was similar to that of sedentary animals. We conclude that this technique could be used to study vascular and extracellular volume homeostasis noninvasively in rats. PMID:26697983

  20. Connexin 43 is a potential regulator in fluid shear stress-induced signal transduction in osteocytes.

    PubMed

    Li, Xiaoting; Liu, Chenglin; Li, Ping; Li, Shengnan; Zhao, Zhihe; Chen, Yangxi; Huo, Bo; Zhang, Ding

    2013-12-01

    Connexin 43 (Cx43), a gap junctional protein, regulates osteocyte viability, and modulates mechanical stimulation-induced bone remodeling. However, the underlying mechanisms of its action remain unclear. In the current study, osteocyte-like MLO-Y4 cells were exposed to fluid shear stress (FSS) of 16 (physiological) or 30 (high) dyne/cm(2) for the indicated time points. Cx43 gene (Gja1) was silenced using siRNA or the protein was blocked chemically. The signaling molecules related to osteocyte apoptosis, osteogenesis, or osteoclastogenesis were detected at mRNA or protein levels. The results showed that physiological FSS significantly upregulated Cx43, which further inhibited apoptosis pathways (e.g., caspase-3) and osteoclastogenesis signaling (e.g., RANKL), but activated osteogenesis signaling (Sost/sclerostin). Suppressing Cx43 gene (Gja1) by siRNA or chemically blocking gap junction communication enhanced caspase-3, RANKL, and Sost/sclerostin, which could be restored with physiological FSS over 8 h. In addition, high FSS decreased Cx43 expression and adversely affected signaling molecules compared with physiological FSS. The findings indicate the involvement of Cx43 in mechanotransduction of FSS and in the modulation of mechanical loading-related apoptosis, osteogenesis, and osteoclastogenesis of osteocytes. This may provide a cellular and molecular basis for interpreting the biomechanical mechanism of bone absorption and remodeling. PMID:23878018

  1. Development of a novel naphthoic acid ionic liquid and its application in "no-organic solvent microextraction" for determination of triclosan and methyltriclosan in human fluids and the method optimization by central composite design.

    PubMed

    Wang, Hui; Gao, Jiajia; Yu, Nana; Qu, Jingang; Fang, Fang; Wang, Huili; Wang, Mei; Wang, Xuedong

    2016-07-01

    In traditional ionic liquids (ILs)-based microextraction, the hydrophobic and hydrophilic ILs are often used as extractant and disperser, respectively. However, the functional effects of ILs are not utilized in microextraction procedures. Herein, we introduced 1-naphthoic acid into imidazolium ring to synthesize a novel ionic liquid 1-butyl-3-methylimidazolium naphthoic acid salt ([C4MIM][NPA]), and its structure was characterized by IR, (1)H NMR and MS. On the basis of its acidic property and lower solubility than common [CnMIM][BF4], it was used as a mixing dispersive solvent with [C4MIM][BF4] in "functionalized ionic liquid-based no organic solvent microextraction (FIL-NOSM)". Utilization of [C4MIM][NPA] in FIL-NOSM procedures has two obvious advantages: (1) it promoted the non-polar environment, increased volume of the sedimented phase, and thus could enhance the extraction recoveries of triclosan (TCS) and methyltriclosan (MTCS) by more than 10%; and (2) because of the acidic property, it can act as a pH modifier, avoiding extra pH adjustment step. By combining single factor optimization and central composite design, the main factors in the FIL-NOSM method were optimized. Under the optimal conditions, the relative recoveries of TCS and MTCS reached up to 98.60-106.09%, and the LODs of them were as low as 0.12-0.15µgL(-1) in plasma and urine samples. In total, this [C4MIM][NPA]-based FIL-NOSM method provided high extraction efficiency, and required less pretreatment time and unutilized any organic solvent. To the best of our knowledge, this is the first application of [C4mim][NPA]-based microextraction method for the simultaneous quantification of trace TCS and MTCS in human fluids. PMID:27154690

  2. The improved resistance to high salinity induced by trehalose is associated with ionic regulation and osmotic adjustment in Catharanthus roseus.

    PubMed

    Chang, Bowen; Yang, Lei; Cong, Weiwei; Zu, Yuangang; Tang, Zhonghua

    2014-04-01

    The effects of exogenous trehalose (Tre) on salt tolerance of pharmaceutical plant Catharanthus roseus and the physiological mechanisms were both investigated in this study. The results showed that the supplement of Tre in saline condition (250 mM NaCl) largely alleviated the inhibitory effects of salinity on plant growth, namely biomass accumulation and total leaf area per plant. In this saline condition, the decreased level of relative water content (RWC) and photosynthetic rate were also greatly rescued by exogenous Tre. This improved performance of plants under high salinity induced by Tre could be partly ascribed to its ability to decrease accumulation of sodium, and increase potassium in leaves. The exogenous Tre led to high levels of fructose, glucose, sucrose and Tre inside the salt-stressed plants during whole the three-week treatment. The major free amino acids such as proline, arginine, threonine and glutamate were also largely elevated in the first two-week course of treatment with Tre in saline solution. It was proposed here that Tre might act as signal to make the salt-stressed plants actively increase internal compatible solutes, including soluble sugars and free amino acids, to control water loss, leaf gas exchange and ionic flow at the onset of salt stress. The application of Tre in saline condition also promoted the accumulation of alkaloids. The regulatory role of Tre in improving salt tolerance was optimal with an exogenous concentration of 10 mM Tre. Larger concentrations of Tre were supra-optimum and adversely affected plant growth. PMID:24589477

  3. Multiple functions of the crustacean gill: osmotic/ionic regulation, acid-base balance, ammonia excretion, and bioaccumulation of toxic metals

    PubMed Central

    Henry, Raymond P.; Lucu, Čedomil; Onken, Horst; Weihrauch, Dirk

    2012-01-01

    The crustacean gill is a multi-functional organ, and it is the site of a number of physiological processes, including ion transport, which is the basis for hemolymph osmoregulation; acid-base balance; and ammonia excretion. The gill is also the site by which many toxic metals are taken up by aquatic crustaceans, and thus it plays an important role in the toxicology of these species. This review provides a comprehensive overview of the ecology, physiology, biochemistry, and molecular biology of the mechanisms of osmotic and ionic regulation performed by the gill. The current concepts of the mechanisms of ion transport, the structural, biochemical, and molecular bases of systemic physiology, and the history of their development are discussed. The relationship between branchial ion transport and hemolymph acid-base regulation is also treated. In addition, the mechanisms of ammonia transport and excretion across the gill are discussed. And finally, the toxicology of heavy metal accumulation via the gill is reviewed in detail. PMID:23162474

  4. Ionic liquid-assisted bidirectional regulation strategy for carbon quantum dots (CQDs)/Bi4O5I2 nanomaterials and enhanced photocatalytic properties.

    PubMed

    Ji, Mengxia; Xia, Jiexiang; Di, Jun; Wang, Bin; Yin, Sheng; Xu, Li; Zhao, Junze; Li, Huaming

    2016-09-15

    In this study, novel visible-light-driven carbon quantum dots (CQDs)/Bi4O5I2 material has been prepared via a reactable ionic liquid 1-hexyl-3-methylimidazolium iodide ([Hmim]I) assisted bidirectional regulation solvothermal method. This is the first time for the preparation of CQDs/Bi4O5I2 material with halogen and CQDs bidirectional regulation at the same time. With CQDs modified on the surface of Bi4O5I2, fast transfer of photogenerated charges and low recombination of photo-induced electron-hole pairs facilitated the enhancement of photodegradation activity. At the same time, the introduction of CQDs made the electrons occupied in high-energy potential on the conduction band of Bi4O5I2 transfer to the reaction center CQDs and the molecular oxygen can be thus activated. The enhanced mechanisms for the active species (holes, hydroxyl and superoxide radicals) during the photocatalytic reaction under visible irradiation were analyzed using DRS analysis, electron spin resonance (ESR) technique and free radicals trapping experiments. PMID:27318012

  5. Hydraulic Pressure during Fluid Flow Regulates Purinergic Signaling and Cytoskeleton Organization of Osteoblasts

    PubMed Central

    Gardinier, Joseph D.; Gangadharan, Vimal; Wang, Liyun; Duncan, Randall L.

    2014-01-01

    During physiological activities, osteoblasts experience a variety of mechanical forces that stimulate anabolic responses at the cellular level necessary for the formation of new bone. Previous studies have primarily investigated the osteoblastic response to individual forms of mechanical stimuli. However in this study, we evaluated the response of osteoblasts to two simultaneous, but independently controlled stimuli; fluid flow-induced shear stress (FSS) and static or cyclic hydrostatic pressure (SHP or CHP, respectively). MC3T3-E1 osteoblasts-like cells were subjected to 12dyn/cm2 FSS along with SHP or CHP of varying magnitudes to determine if pressure enhances the anabolic response of osteoblasts during FSS. For both SHP and CHP, the magnitude of hydraulic pressure that induced the greatest release of ATP during FSS was 15 mmHg. Increasing the hydraulic pressure to 50 mmHg or 100 mmHg during FSS attenuated the ATP release compared to 15 mmHg during FSS. Decreasing the magnitude of pressure during FSS to atmospheric pressure reduced ATP release to that of basal ATP release from static cells and inhibited actin reorganization into stress fibers that normally occurred during FSS with 15 mmHg of pressure. In contrast, translocation of nuclear factor kappa B (NFκB) to the nucleus was independent of the magnitude of hydraulic pressure and was found to be mediated through the activation of phospholipase-C (PLC), but not src kinase. In conclusion, hydraulic pressure during FSS was found to regulate purinergic signaling and actin cytoskeleton reorganization in the osteoblasts in a biphasic manner, while FSS alone appeared to stimulate NFκB translocation. Understanding the effects of hydraulic pressure on the anabolic responses of osteoblasts during FSS may provide much needed insights into the physiologic effects of coupled mechanical stimuli on osteogenesis. PMID:24910719

  6. Adaptive Force Regulation of Muscle Strengthening Rehabilitation Device With Magnetorheological Fluids

    PubMed Central

    Dong, Shufang; Lu, Ke-Qian; Sun, Jian Qiao; Rudolph, Katherine

    2008-01-01

    In rehabilitation from neuromuscular trauma or injury, strengthening exercises are often prescribed by physical therapists to recover as much function as possible. Strengthening equipment used in clinical settings range from low-cost devices, such as sandbag weights or elastic bands to large and expensive isotonic and isokinetic devices. The low-cost devices are incapable of measuring strength gains and apply resistance based on the lowest level of torque that is produced by a muscle group. Resistance that varies with joint angle can be achieved with isokinetic devices in which angular velocity is held constant and variable torque is generated when the patient attempts to move faster than the device but are ineffective if a patient cannot generate torque rapidly. In this paper, we report the development of a versatile rehabilitation device that can be used to strengthen different muscle groups based on the torque generating capability of the muscle that changes with joint angle. The device is low cost, is smaller than other commercially available machines, and can be programmed to apply resistance that is unique to a particular patient and that will optimize strengthening. The core of the device, a damper with smart magnetorheological fluids, provides passive exercise force. A digital adaptive control is capable of regulating exercise force precisely following the muscle strengthening profile prescribed by a physical therapist. The device could be programmed with artificial intelligence to dynamically adjust the target force profile to optimize rehabilitation effects. The device provides both isometric and isokinetic strength training and can be developed into a small, low-cost device that may be capable of providing optimal strengthening in the home. PMID:16562632

  7. Adaptive force regulation of muscle strengthening rehabilitation device with magnetorheological fluids.

    PubMed

    Dong, Shufang; Lu, Ke-Qian; Sun, Jian Qiao; Rudolph, Katherine

    2006-03-01

    In rehabilitation from neuromuscular trauma or injury, strengthening exercises are often prescribed by physical therapists to recover as much function as possible. Strengthening equipment used in clinical settings range from low-cost devices, such as sandbag weights or elastic bands to large and expensive isotonic and isokinetic devices. The low-cost devices are incapable of measuring strength gains and apply resistance based on the lowest level of torque that is produced by a muscle group. Resistance that varies with joint angle can be achieved with isokinetic devices in which angular velocity is held constant and variable torque is generated when the patient attempts to move faster than the device but are ineffective if a patient cannot generate torque rapidly. In this paper, we report the development of a versatile rehabilitation device that can be used to strengthen different muscle groups based on the torque generating capability of the muscle that changes with joint angle. The device is low cost, is smaller than other commercially available machines, and can be programmed to apply resistance that is unique to a particular patient and that will optimize strengthening. The core of the device, a damper with smart magnetorheological fluids, provides passive exercise force. A digital adaptive control is capable of regulating exercise force precisely following the muscle strengthening profile prescribed by a physical therapist. The device could be programmed with artificial intelligence to dynamically adjust the target force profile to optimize rehabilitation effects. The device provides both isometric and isokinetic strength training and can be developed into a small, low-cost device that may be capable of providing optimal strengthening in the home. PMID:16562632

  8. Regulation of electrolyte and fluid metabolism in multi-stage ultra-marathoners.

    PubMed

    Knechtle, B; Knechtle, P; Rüst, C A; Gnädinger, M; Imoberdorf, R; Kohler, G; Rosemann, T; Ballmer, P

    2012-11-01

    The purposes of this study were (i) to determine the prevalence of exercise-associated hyponatremia (EAH) in multi-stage ultra-marathoners and (ii) to gain more insight into fluid and electrolyte regulation during a multi-stage race. Body mass, sodium concentration ([Na⁺]), potassium concentration ([K⁺]), creatinine, urea, specific gravity, and osmolality in urine were measured in 25 male ultra-marathoners in the 'Swiss Jura Marathon' 2008 with 11,000 m gain of altitude over 7 stages covering 350 km, before and after each stage. Haemoglobin, haematocrit, creatinine, urea, [Na⁺], [K⁺], and osmolality were measured in plasma before stage 1 and after stages 1, 3, 5, and 7. Two athletes (8%) showed plasma [Na⁺] <135 mmol/l. Body mass, plasma [Na⁺], and plasma [K⁺] remained unchanged (p>0.05). Urine specific gravity (p<0.001) and osmolality in both plasma (p<0.01) and urine (p<0.001) were increased and haematocrit (p<0.0001), haemoglobin (p<0.0001) and plasma albumin were decreased (p<0.001). Plasma volume (p<0.01) and plasma urea (p<0.001) were increased. The K⁺/Na⁺ ratio in urine increased >1.0 after each stage and returned to <1.0 the morning of the next stage (p<0.001). To summarize, more sodium than potassium was excreted during rest. The increased urinary sodium losses during rest are compatible with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) or the cerebral salt-wasting syndrome (CSWS). Further studies are needed to determine the antidiuretic hormone (ADH) and both the atrial natriuretic peptide (ANP) and the brain natriuretic peptide (BNP) during multi-stage races. PMID:22638835

  9. Metabolite and ionic composition of follicular fluid from different-sized follicles and their relationship to serum concentrations in dairy cows.

    PubMed

    Leroy, J L M R; Vanholder, T; Delanghe, J R; Opsomer, G; Van Soom, A; Bols, P E J; de Kruif, A

    2004-02-01

    Metabolic changes in blood serum may be reflected in the biochemical composition of follicular fluid and could indirectly influence oocyte quality. The purpose of this study was to examine the biochemical composition of follicular fluid harvested from different-sized follicles and its relationship with that of blood serum in dairy cattle. Following slaughter, blood samples were collected from dairy cows n=30 and follicular fluid aspirated from three size classes of non-atretic follicles (<4 mm, 6-8 mm and >10 mm diameter). Samples remained independent between cows and between size classes within cows. Serum and follicular fluid samples were assayed using commercial clinical and photometric chemistry assays for ions (sodium, potassium and chloride) and metabolites (glucose, beta-hydroxybutyrate (beta-OHB), lactate, urea, total protein, triglycerides, non-esterified fatty acids (NEFA) and total cholesterol). Results showed that follicular fluid concentrations of glucose, beta-OHB and total cholesterol increased from small to large follicles and decreased for potassium, chloride, lactate, urea and triglycerides. There was a significant concentration gradient for all variables between their levels in serum and follicular fluid (P<0.05). Significant correlations were observed for chloride (r=0.40), glucose (r=0.56), beta-OHB (r=0.85), urea (r=0.95) and total protein (r=0.60) for all three follicle size classes and for triglycerides (r=0.43), NEFA (r=0.50) and total cholesterol (r=0.42) for large follicles (P<0.05). The results from the present study suggest that the oocyte and the granulosa cells of dairy cows grow and mature in a biochemical environment that changes from small to large follicles. Furthermore, the significant correlation between the composition of serum and follicular fluid for the above-mentioned metabolites suggests that metabolic changes in serum levels will be reflected in the follicular fluid and, therefore, may affect the quality of both the

  10. Adrenocorticotropic hormone in serial cerebrospinal fluid in man - Subject to acute regulation by the hypothalamic-pituitary-adrenocortical system?

    PubMed

    Kellner, Michael; Wortmann, Viola; Salzwedel, Cornelie; Kober, Daniel; Petzoldt, Martin; Urbanowicz, Tatiana; Pulic, Mersija; Boelmans, Kai; Yassouridis, Alexander; Wiedemann, Klaus

    2016-05-30

    Acute regulation of adrenocorticotropic hormone (ACTH) in cerebrospinal fluid (CSF) by the hypothalamic-pituitary-adrenocortical system has not been investigated in man. In a pilot study in healthy male volunteers we measured ACTH every twenty minutes in serial CSF for three hours after an intravenous placebo, hydrocortisone (100mg) or insulin (2mg/kg) injection. No acute inhibitory or stimulatory effects of these interventions were discovered. Our results corroborate previous findings in rhesus monkeys. The regulation of CSF ACTH and its potential relevance for behavioral alterations in health and disease (e.g. major depression or anorexia nervosa) in humans need further study. PMID:27031591

  11. Wettability by Ionic Liquids.

    PubMed

    Liu, Hongliang; Jiang, Lei

    2016-01-01

    Ionic liquids (ILs) have become particularly attractive recently because they have demonstrated themselves to be important construction units in the broad fields of chemistry and materials science, from catalysis and synthesis to analysis and electrochemistry, from functional fluids to clean energy, from nanotechnology to functional materials. One of the greatest issues that determines the performance of ILs is the wettability of correlated surfaces. In this concept article, the key developments and issues in IL wettability are surveyed, including the electrowetting of ILs in gas-liquid-solid systems and liquid-liquid-solid systems, ILs as useful probe fluids, the superwettability of Ils, and future directions in IL wettability. This should generate extensive interest in the field and encourage more scientists to engage in this area to tackle its scientific challenges. PMID:26619157

  12. An integrated mechanism of pediatric pseudotumor cerebri syndrome: evidence of bioenergetic and hormonal regulation of cerebrospinal fluid dynamics

    PubMed Central

    Sheldon, Claire A.; Kwon, Young Joon; Liu, Grant T.; McCormack, Shana E.

    2015-01-01

    Pseudotumor cerebri syndrome (PTCS) is defined by the presence of elevated intracranial pressure (ICP) in the setting of normal brain parenchyma and cerebrospinal fluid (CSF). Headache, vision changes, and papilledema are common presenting features. Up to 10% of appropriately treated patients may experience permanent visual loss. The mechanism(s) underlying PTCS is unknown. PTCS occurs in association with a variety of conditions, including kidney disease, obesity, and adrenal insufficiency, suggesting endocrine and/or metabolic derangements may occur. Recent studies suggest that fluid and electrolyte balance in renal epithelia is regulated by a complex interaction of metabolic and hormonal factors; these cells share many of the same features as the choroid plexus cells in the central nervous system (CNS) responsible for regulation of CSF dynamics. Thus, we posit that similar factors may influence CSF dynamics in both types of fluid-sensitive tissues. Specifically, we hypothesize that, in patients with PTCS, mitochondrial metabolites (glutamate, succinate) and steroid hormones (cortisol, aldosterone) regulate CSF production and/or absorption. In this integrated mechanism review, we consider the clinical and molecular evidence for each metabolite and hormone in turn. We illustrate how related intracellular signaling cascades may converge in the choroid plexus, drawing on evidence from functionally similar tissues. PMID:25420176

  13. Effects of hypoxia on ionic regulation, glycogen utilization and antioxidative ability in the gills and liver of the aquatic air-breathing fish Trichogaster microlepis.

    PubMed

    Huang, Chun-Yen; Lin, Hui-Chen; Lin, Cheng-Huang

    2015-01-01

    We examined the hypothesis that Trichogaster microlepis, a fish with an accessory air-breathing organ, uses a compensatory strategy involving changes in both behavior and protein levels to enhance its gas exchange ability. This compensatory strategy enables the gill ion-regulatory metabolism to maintain homeostasis during exposure to hypoxia. The present study aimed to determine whether ionic regulation, glycogen utilization and antioxidant activity differ in terms of expression under hypoxic stresses; fish were sampled after being subjected to 3 or 12h of hypoxia and 12h of recovery under normoxia. The air-breathing behavior of the fish increased under hypoxia. No morphological modification of the gills was observed. The expression of carbonic anhydrase II did not vary among the treatments. The Na(+)/K(+)-ATPase enzyme activity did not decrease, but increases in Na(+)/K(+)-ATPase protein expression and ionocyte levels were observed. The glycogen utilization increased under hypoxia as measured by glycogen phosphorylase protein expression and blood glucose level, whereas the glycogen content decreased. The enzyme activity of several components of the antioxidant system in the gills, including catalase, glutathione peroxidase, and superoxidase dismutase, increased in enzyme activity. Based on the above data, we concluded that T. microlepis is a hypoxia-tolerant species that does not exhibit ion-regulatory suppression but uses glycogen to maintain energy utilization in the gills under hypoxic stress. Components of the antioxidant system showed increased expression under the applied experimental treatments. PMID:25218942

  14. Regulation of the Cardiac Sodium/Bicarbonate Cotransporter by Angiotensin II: Potential Contribution to Structural, Ionic and Electrophysiological Myocardial Remodelling

    PubMed Central

    Aiello, Ernesto Alejandro; Giusti, Verónica Celeste De

    2013-01-01

    The sodium/ bicarbonate cotransporter (NBC) is, with the Na+/H+ exchanger (NHE), an important alkalinizing mechanism that maintains cellular intracellular pH (pHi). In the heart exists at least three isoforms of NBC, one that promotes the co-influx of 1 molecule of Na+ per 1molecule of HCO3-(electroneutral isoform; nNBC) and two others that generates the co-influx of 1 molecule of Na+ per 2 molecules of HCO3- (electrogenic isoforms; eNBC). In addition, the eNBC generates an anionic repolarizing current that modulate the cardiac action potential (CAP), adding to such isoforms the relevance to modulate the electrophysiological function of the heart. Angiotensin II (Ang II) is one of the main hormones that regulate cardiac physiology. The alkalinizing mechanisms (NHE and NBC) are stimulated by Ang II, increasing pHi and intracellular Na+ concentration, which indirectly, due to the stimulation of the Na+/Ca2+ exchanger (NCX) operating in the reverse form, leads to an increase in the intracellular Ca2+ concentration. Interestingly, it has been shown that Ang II exhibits an opposite effect on NBC isoforms: it activates the nNBC and inhibits the eNBC. This inhibition generates a CAP prolongation, which could directly increase the intracellular Ca2+ concentration. The regulation of the intracellular Na+ and Ca2+ concentrations is crucial for the cardiac cellular physiology, but these ions are also involved in the development of cardiac hypertrophy and the damage produced by ischemia-reperfusion, suggesting a potential role of NBC in cardiac diseases. PMID:23116057

  15. Effect of dietary sodium on fluid/electrolyte regulation during bed rest

    NASA Technical Reports Server (NTRS)

    Williams, W. Jon; Schneider, Suzanne M.; Gretebeck, Randall J.; Lane, Helen W.; Stuart, Charles A.; Whitson, Peggy A.

    2003-01-01

    BACKGROUND: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning. HYPOTHESIS: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses. METHODS: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.0 +/- 0.06 g x d(-1) (174 mmol x d(-1)) (CONT; n = 6), 1.0 +/- 0.02 g x d(-1) (43 mmol x d(-1)) (LS; n = 6), or 10.0 +/- 0.04 g x d(-1) (430 mmol x d(-1)) (HS; n = 5) sodium diet before, during, and after 21 d of 6 degrees head-down BR. PV, total body water, urine volume and osmolality, POSM, and F/E controlling hormone concentrations were measured. RESULTS: In HS subjects, plasma renin activity (-92%), plasma/urinary aldosterone (-59%; -64%), and PV (-15.0%; 6.0 ml x kg(-1); p < 0.05) decreased while plasma atrial natriuretic peptide (+34%) and urine antidiuretic hormone (+24%) increased during BR (p < 0.05) compared with CONT. In LS, plasma renin activity (+166%), plasma aldosterone (+167%), plasma antidiuretic hormone (+19%), and urinary aldosterone (+335%) increased with no change in PV compared with CONT (p < 0.05). Total body water did not change in any of the subjects. CONCLUSIONS: Contrary to our hypothesis, increasing dietary sodium while controlling fluid intake during BR resulted in a greater loss of PV compared with the CONT subjects. Reducing dietary sodium while controlling fluid intake did not alter the PV response during BR compared with CONT subjects.

  16. Alkaline phosphatase in osteoblasts is down-regulated by pulsatile fluid flow

    NASA Technical Reports Server (NTRS)

    Hillsley, M. V.; Frangos, J. A.

    1997-01-01

    It is our hypothesis that interstitial fluid flow plays a role in the bone remodeling response to mechanical loading. The fluid flow-induced expression of three proteins (collagen, osteopontin, and alkaline phosphatase) involved in bone remodeling was investigated. Rat calvarial osteoblasts subjected to pulsatile fluid flow at an average shear stress of 5 dyne/cm2 showed decreased alkaline phosphatase (AP) mRNA expression after only 1 hour of flow. After 3 hours of flow, AP mRNA levels had decreased to 30% of stationary control levels and remained at this level for an additional 5 hours of flow. Steady flow (4 dyne/cm2 fluid shear stress), in contrast, resulted in a delayed and less dramatic decrease in AP mRNA expression to 63% of control levels after 8 hours of flow. The reduced AP mRNA expression under pulsatile flow conditions was followed by reduced AP enzyme activity after 24 hours. No changes in collagen or osteopontin mRNA expression were detected over 8 hours of pulsatile flow. This is the first time fluid flow has been shown to affect gene expression in osteoblasts.

  17. Eco-friendly ionic liquid assisted capillary electrophoresis and α-acid glycoprotein-assisted liquid chromatography for simultaneous determination of anticancer drugs in human fluids.

    PubMed

    Abd El-Hady, Deia; Albishri, Hassan M; Rengarajan, Rajesh

    2015-06-01

    In the current work, two eco-friendly analytical methods based on capillary electrophoresis (CE) and reversed phase liquid chromatography (RPLC) were developed for simultaneous determination of the most commonly used anticancer drugs for Hodgkin's disease: methotrexate (MTX), vinblastine, chlorambucil and dacarbazine. A background electrolyte (BGE) of 12.5 mmol/L phosphate buffer at pH 7.4 and 0.1 µmol/L 1-butyl-3-methyl imidazolium bromide (BMImBr) ionic liquid (IL) was used for CE measurements at 250 nm detection wavelength, 20 kV applied voltage and 25 °C. The rinsing protocol was significantly improved to reduce the adsorption of IL on the interior surface of capillary. Moreover, RPLC method was developed on α-1-acid glycoprotein (AGP) column. Mobile phase was 10 mmol/L phosphate buffer at pH 6.0 (100% v/v) and flow rate at 0.1 mL/min. As AGP is a chiral column, it was successfully separated l-MTX from its enantiomer impurity d-MTX. Good linearity of quantitative analysis was achieved with coefficients of determinations (r(2) ) >0.995. The stability of drugs measurements was investigated with adequate recoveries up to 24 h storage time under ambient temperature. The limits of detection were <50 and 90 ng/mL by CE and RPLC, respectively. The using of short-chain IL as an additive in BGE achieved 600-fold sensitivity enhancement compared with conventional Capillary Zone Electrophoresis (CZE). Therefore, for the first time, the proposed methods were successfully applied to determine simultaneously the analytes in human plasma and urine samples at clinically relevant concentrations with fast and simple pretreatments. Developed IL-assisted CE and RPLC methods were also applied to measure MTX levels in patients' samples over time. PMID:25400220

  18. A Noninvasive Method to Study Regulation of Extracellular Fluid Volume in Rats Using Nuclear Magnetic Resonance

    EPA Science Inventory

    Time-domain nuclear magnetic resonance (TD-NMR)-based measurement of body composition of rodents is an effective method to quickly and repeatedly measure proportions of fat, lean, and fluid without anesthesia. TD-NMR provides a measure of free water in a living animal, termed % f...

  19. Disemployment effects caused by regulation of drilling fluids and produced waters as hazardous under the Resource Conservation and Recovery Act

    SciTech Connect

    Flaim, S.J.

    1988-03-01

    This report reviews and compares several studies of the effects on employment of regulating wastes from oil and natural gas exploration and extraction under the Resource Conservation and Recovery Act (RCRA). The waste management scenarios on which most of the studies were based were developed by the U.S. Environmental Protection Agency. The analyses show that as many as 500,000-700,000 jobs may be lost in the first year if RCRA Subtitle C rules are applied to drilling fluids and produced waters. As a results, unemployment in major oil-producing states could rise by as much as six percentage points. 13 refs., 4 tabs.

  20. Harnessing fluid-structure interactions to design self-regulating acoustic metamaterials

    SciTech Connect

    Casadei, Filippo; Bertoldi, Katia

    2014-01-21

    The design of phononic crystals and acoustic metamaterials with tunable and adaptive wave properties remains one of the outstanding challenges for the development of next generation acoustic devices. We report on the numerical and experimental demonstration of a locally resonant acoustic metamaterial with dispersion characteristics, which autonomously adapt in response to changes of an incident aerodynamic flow. The metamaterial consists of a slender beam featuring a periodic array or airfoil-shaped masses supported by a linear and torsional springs. The resonance characteristics of the airfoils lead to strong attenuation at frequencies defined by the properties of the airfoils and the speed on the incident fluid. The proposed concept expands the ability of existing acoustic bandgap materials to autonomously adapt their dispersion properties through fluid-structure interactions, and has the potential to dramatically impact a variety of applications, such as robotics, civil infrastructures, and defense systems.

  1. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  2. Ionic switch controls the DNA state in phage λ.

    PubMed

    Li, Dong; Liu, Ting; Zuo, Xiaobing; Li, Tao; Qiu, Xiangyun; Evilevitch, Alex

    2015-07-27

    We have recently found that DNA packaged in phage λ undergoes a disordering transition triggered by temperature, which results in increased genome mobility. This solid-to-fluid like DNA transition markedly increases the number of infectious λ particles facilitating infection. However, the structural transition strongly depends on temperature and ionic conditions in the surrounding medium. Using titration microcalorimetry combined with solution X-ray scattering, we mapped both energetic and structural changes associated with transition of the encapsidated λ-DNA. Packaged DNA needs to reach a critical stress level in order for transition to occur. We varied the stress on DNA in the capsid by changing the temperature, packaged DNA length and ionic conditions. We found striking evidence that the intracapsid DNA transition is 'switched on' at the ionic conditions mimicking those in vivo and also at the physiologic temperature of infection at 37°C. This ion regulated on-off switch of packaged DNA mobility in turn affects viral replication. These results suggest a remarkable adaptation of phage λ to the environment of its host bacteria in the human gut. The metastable DNA state in the capsid provides a new paradigm for the physical evolution of viruses. PMID:26092697

  3. Ionic switch controls the DNA state in phage λ

    PubMed Central

    Li, Dong; Liu, Ting; Zuo, Xiaobing; Li, Tao; Qiu, Xiangyun; Evilevitch, Alex

    2015-01-01

    We have recently found that DNA packaged in phage λ undergoes a disordering transition triggered by temperature, which results in increased genome mobility. This solid-to-fluid like DNA transition markedly increases the number of infectious λ particles facilitating infection. However, the structural transition strongly depends on temperature and ionic conditions in the surrounding medium. Using titration microcalorimetry combined with solution X-ray scattering, we mapped both energetic and structural changes associated with transition of the encapsidated λ-DNA. Packaged DNA needs to reach a critical stress level in order for transition to occur. We varied the stress on DNA in the capsid by changing the temperature, packaged DNA length and ionic conditions. We found striking evidence that the intracapsid DNA transition is ‘switched on’ at the ionic conditions mimicking those in vivo and also at the physiologic temperature of infection at 37°C. This ion regulated on-off switch of packaged DNA mobility in turn affects viral replication. These results suggest a remarkable adaptation of phage λ to the environment of its host bacteria in the human gut. The metastable DNA state in the capsid provides a new paradigm for the physical evolution of viruses. PMID:26092697

  4. Ionic switch controls the DNA state in phage λ

    DOE PAGESBeta

    Li, Dong; Liu, Ting; Zuo, Xiaobing; Li, Tao; Qiu, Xiangyun; Evilevitch, Alex

    2015-06-19

    We have recently found that DNA packaged in phage λ undergoes a disordering transition triggered by temperature, which results in increased genome mobility. This solid-to-fluid like DNA transition markedly increases the number of infectious λ particles facilitating infection. However, the structural transition strongly depends on temperature and ionic conditions in the surrounding medium. Using titration microcalorimetry combined with solution X-ray scattering, we mapped both energetic and structural changes associated with transition of the encapsidated λ-DNA. Packaged DNA needs to reach a critical stress level in order for transition to occur. We varied the stress on DNA in the capsid bymore » changing the temperature, packaged DNA length and ionic conditions. We found striking evidence that the intracapsid DNA transition is ‘switched on’ at the ionic conditions mimicking those in vivo and also at the physiologic temperature of infection at 37°C. This ion regulated on-off switch of packaged DNA mobility in turn affects viral replication. The results suggest a remarkable adaptation of phage λ to the environment of its host bacteria in the human gut. The metastable DNA state in the capsid provides a new paradigm for the physical evolution of viruses.« less

  5. Ionic switch controls the DNA state in phage λ

    SciTech Connect

    Li, Dong; Liu, Ting; Zuo, Xiaobing; Li, Tao; Qiu, Xiangyun; Evilevitch, Alex

    2015-06-19

    We have recently found that DNA packaged in phage λ undergoes a disordering transition triggered by temperature, which results in increased genome mobility. This solid-to-fluid like DNA transition markedly increases the number of infectious λ particles facilitating infection. However, the structural transition strongly depends on temperature and ionic conditions in the surrounding medium. Using titration microcalorimetry combined with solution X-ray scattering, we mapped both energetic and structural changes associated with transition of the encapsidated λ-DNA. Packaged DNA needs to reach a critical stress level in order for transition to occur. We varied the stress on DNA in the capsid by changing the temperature, packaged DNA length and ionic conditions. We found striking evidence that the intracapsid DNA transition is ‘switched on’ at the ionic conditions mimicking those in vivo and also at the physiologic temperature of infection at 37°C. This ion regulated on-off switch of packaged DNA mobility in turn affects viral replication. The results suggest a remarkable adaptation of phage λ to the environment of its host bacteria in the human gut. The metastable DNA state in the capsid provides a new paradigm for the physical evolution of viruses.

  6. Monitoring the regulation of gene expression in a growing organ using a fluid mechanics formalism

    PubMed Central

    2010-01-01

    Background Technological advances have enabled the accurate quantification of gene expression, even within single cell types. While transcriptome analyses are routinely performed, most experimental designs only provide snapshots of gene expression. Molecular mechanisms underlying cell fate or positional signalling have been revealed through these discontinuous datasets. However, in developing multicellular structures, temporal and spatial cues, known to directly influence transcriptional networks, get entangled as the cells are displaced and expand. Access to an unbiased view of the spatiotemporal regulation of gene expression occurring during development requires a specific framework that properly quantifies the rate of change of a property in a moving and expanding element, such as a cell or an organ segment. Results We show how the rate of change in gene expression can be quantified by combining kinematics and real-time polymerase chain reaction data in a mechanistic model which considers any organ as a continuum. This framework was applied in order to assess the developmental regulation of the two reference genes Actin11 and Elongation Factor 1-β in the apex of poplar root. The growth field was determined by time-lapse photography and transcript density was obtained at high spatial resolution. The net accumulation rates of the transcripts of the two genes were found to display highly contrasted developmental profiles. Actin11 showed pulses of up and down regulation in the accelerating and decelerating parts of the growth zone while the dynamic of EF1β were much slower. This framework provides key information about gene regulation in a developing organ, such as the location, the duration and the intensity of gene induction/repression. Conclusions We demonstrated that gene expression patterns can be monitored using the continuity equation without using mutants or reporter constructions. Given the rise of imaging technologies, this framework in our view opens a

  7. Ferritin levels in the cerebrospinal fluid predict Alzheimer's disease outcomes and are regulated by APOE

    PubMed Central

    Ayton, Scott; Faux, Noel G.; Bush, Ashley I.; Weiner, Michael W.; Aisen, Paul; Petersen, Ronald; Jack Jr., Clifford R.; Jagust, William; Trojanowki, John Q.; Toga, Arthur W.; Beckett, Laurel; Green, Robert C.; Saykin, Andrew J.; Morris, John; Shaw, Leslie M.; Khachaturian, Zaven; Sorensen, Greg; Kuller, Lew; Raichle, Marc; Paul, Steven; Davies, Peter; Fillit, Howard; Hefti, Franz; Holtzman, Davie; Marcel Mesulam, M.; Potter, William; Snyder, Peter; Schwartz, Adam; Montine, Tom; Thomas, Ronald G.; Donohue, Michael; Walter, Sarah; Gessert, Devon; Sather, Tamie; Jiminez, Gus; Harvey, Danielle; Bernstein, Matthew; Fox, Nick; Thompson, Paul; Schuff, Norbert; Borowski, Bret; Gunter, Jeff; Senjem, Matt; Vemuri, Prashanthi; Jones, David; Kantarci, Kejal; Ward, Chad; Koeppe, Robert A.; Foster, Norm; Reiman, Eric M.; Chen, Kewei; Mathis, Chet; Landau, Susan; Cairns, Nigel J.; Householder, Erin; Taylor-Reinwald, Lisa; Lee, Virginia; Korecka, Magdalena; Figurski, Michal; Crawford, Karen; Neu, Scott; Foroud, Tatiana M.; Potkin, Steven; Shen, Li; Faber, Kelley; Kim, Sungeun; Nho, Kwangsik; Thal, Leon; Buckholtz, Neil; Albert, Marylyn; Frank, Richard; Hsiao, John; Kaye, Jeffrey; Quinn, Joseph; Lind, Betty; Carter, Raina; Dolen, Sara; Schneider, Lon S.; Pawluczyk, Sonia; Beccera, Mauricio; Teodoro, Liberty; Spann, Bryan M.; Brewer, James; Vanderswag, Helen; Fleisher, Adam; Heidebrink, Judith L.; Lord, Joanne L.; Mason, Sara S.; Albers, Colleen S.; Knopman, David; Johnson, Kris; Doody, Rachelle S.; Villanueva-Meyer, Javier; Chowdhury, Munir; Rountree, Susan; Dang, Mimi; Stern, Yaakov; Honig, Lawrence S.; Bell, Karen L.; Ances, Beau; Carroll, Maria; Leon, Sue; Mintun, Mark A.; Schneider, Stacy; Oliver, Angela; Marson, Daniel; Griffith, Randall; Clark, David; Geldmacher, David; Brockington, John; Roberson, Erik; Grossman, Hillel; Mitsis, Effie; deToledo-Morrell, Leyla; Shah, Raj C.; Duara, Ranjan; Varon, Daniel; Greig, Maria T.; Roberts, Peggy; Albert, Marilyn; Onyike, Chiadi; D'Agostino II, Daniel; Kielb, Stephanie; Galvin, James E.; Cerbone, Brittany; Michel, Christina A.; Rusinek, Henry; de Leon, Mony J; Glodzik, Lidia; De Santi, Susan; Murali Doraiswamy, P.; Petrella, Jeffrey R.; Wong, Terence Z.; Arnold, Steven E.; Karlawish, Jason H.; Wolk, David; Smith, Charles D.; Jicha, Greg; Hardy, Peter; Sinha, Partha; Oates, Elizabeth; Conrad, Gary; Lopez, Oscar L.; Oakley, MaryAnn; Simpson, Donna M.; Porsteinsson, Anton P.; Goldstein, Bonnie S.; Martin, Kim; Makino, Kelly M.; Saleem Ismail, M.; Brand, Connie; Mulnard, Ruth A.; Thai, Gaby; Mc-Adams-Ortiz, Catherine; Womack, Kyle; Mathews, Dana; Quiceno, Mary; Diaz-Arrastia, Ramon; King, Richard; Weiner, Myron; Martin-Cook, Kristen; DeVous, Michael; Levey, Allan I.; Lah, James J.; Cellar, Janet S.; Burns, Jeffrey M.; Anderson, Heather S.; Swerdlow, Russell H.; Apostolova, Liana; Tingus, Kathleen; Woo, Ellen; Silverman, Daniel H.S.; Lu, Po H.; Bartzokis, George; Graff-Radford, Neill R; Parfitt, Francine; Kendall, Tracy; Johnson, Heather; Farlow, Martin R.; Hake, Ann Marie; Matthews, Brandy R.; Herring, Scott; Hunt, Cynthia; van Dyck, Christopher H.; Carson, Richard E.; MacAvoy, Martha G.; Chertkow, Howard; Bergman, Howard; Hosein, Chris; Black, Sandra; Stefanovic, Bojana; Caldwell, Curtis; Robin Hsiung, Ging-Yuek; Feldman, Howard; Mudge, Benita; Assaly, Michele; Kertesz, Andrew; Rogers, John; Bernick, Charles; Munic, Donna; Kerwin, Diana; Mesulam, Marek-Marsel; Lipowski, Kristine; Wu, Chuang-Kuo; Johnson, Nancy; Sadowsky, Carl; Martinez, Walter; Villena, Teresa; Scott Turner, Raymond; Johnson, Kathleen; Reynolds, Brigid; Sperling, Reisa A.; Johnson, Keith A.; Marshall, Gad; Frey, Meghan; Lane, Barton; Rosen, Allyson; Tinklenberg, Jared; Sabbagh, Marwan N.; Belden, Christine M.; Jacobson, Sandra A.; Sirrel, Sherye A.; Kowall, Neil; Killiany, Ronald; Budson, Andrew E.; Norbash, Alexander; Johnson, Patricia Lynn; Allard, Joanne; Lerner, Alan; Ogrocki, Paula; Hudson, Leon; Fletcher, Evan; Carmichael, Owen; Olichney, John; DeCarli, Charles; Kittur, Smita; Borrie, Michael; Lee, T-Y; Bartha, Rob; Johnson, Sterling; Asthana, Sanjay; Carlsson, Cynthia M.; Potkin, Steven G.; Preda, Adrian; Nguyen, Dana; Tariot, Pierre; Reeder, Stephanie; Bates, Vernice; Capote, Horacio; Rainka, Michelle; Scharre, Douglas W.; Kataki, Maria; Adeli, Anahita; Zimmerman, Earl A.; Celmins, Dzintra; Brown, Alice D.; Pearlson, Godfrey D.; Blank, Karen; Anderson, Karen; Santulli, Robert B.; Kitzmiller, Tamar J.; Schwartz, Eben S.; Sink, Kaycee M.; Williamson, Jeff D.; Garg, Pradeep; Watkins, Franklin; Ott, Brian R.; Querfurth, Henry; Tremont, Geoffrey; Salloway, Stephen; Malloy, Paul; Correia, Stephen; Rosen, Howard J.; Miller, Bruce L.; Mintzer, Jacobo; Spicer, Kenneth; Bachman, David; Finger, Elizabether; Pasternak, Stephen; Rachinsky, Irina; Drost, Dick; Pomara, Nunzio; Hernando, Raymundo; Sarrael, Antero; Schultz, Susan K.; Boles Ponto, Laura L.; Shim, Hyungsub; Elizabeth Smith, Karen; Relkin, Norman; Chaing, Gloria; Raudin, Lisa; Smith, Amanda; Fargher, Kristin; Ashok Raj, Balebail; Neylan, Thomas; Grafman, Jordan; Davis, Melissa; Morrison, Rosemary; Hayes, Jacqueline; Finley, Shannon; Friedl, Karl; Fleischman, Debra; Arfanakis, Konstantinos; James, Olga; Massoglia, Dino; Jay Fruehling, J.; Harding, Sandra; Peskind, Elaine R.; Petrie, Eric C.; Li, Gail; Yesavage, Jerome A.; Taylor, Joy L.; Furst, Ansgar J.

    2015-01-01

    Brain iron elevation is implicated in Alzheimer's disease (AD) pathogenesis, but the impact of iron on disease outcomes has not been previously explored in a longitudinal study. Ferritin is the major iron storage protein of the body; by using cerebrospinal fluid (CSF) levels of ferritin as an index, we explored whether brain iron status impacts longitudinal outcomes in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. We show that baseline CSF ferritin levels were negatively associated with cognitive performance over 7 years in 91 cognitively normal, 144 mild cognitive impairment (MCI) and 67 AD subjects, and predicted MCI conversion to AD. Ferritin was strongly associated with CSF apolipoprotein E levels and was elevated by the Alzheimer's risk allele, APOE-ɛ4. These findings reveal that elevated brain iron adversely impacts on AD progression, and introduce brain iron elevation as a possible mechanism for APOE-ɛ4 being the major genetic risk factor for AD. PMID:25988319

  8. Ferritin levels in the cerebrospinal fluid predict Alzheimer's disease outcomes and are regulated by APOE.

    PubMed

    Ayton, Scott; Faux, Noel G; Bush, Ashley I

    2015-01-01

    Brain iron elevation is implicated in Alzheimer's disease (AD) pathogenesis, but the impact of iron on disease outcomes has not been previously explored in a longitudinal study. Ferritin is the major iron storage protein of the body; by using cerebrospinal fluid (CSF) levels of ferritin as an index, we explored whether brain iron status impacts longitudinal outcomes in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. We show that baseline CSF ferritin levels were negatively associated with cognitive performance over 7 years in 91 cognitively normal, 144 mild cognitive impairment (MCI) and 67 AD subjects, and predicted MCI conversion to AD. Ferritin was strongly associated with CSF apolipoprotein E levels and was elevated by the Alzheimer's risk allele, APOE-ɛ4. These findings reveal that elevated brain iron adversely impacts on AD progression, and introduce brain iron elevation as a possible mechanism for APOE-ɛ4 being the major genetic risk factor for AD. PMID:25988319

  9. Do genes and environment meet to regulate cerebrospinal fluid dynamics? Relevance for schizophrenia

    PubMed Central

    Palha, Joana A.; Santos, Nadine C.; Marques, Fernanda; Sousa, João; Bessa, João; Miguelote, Rui; Sousa, Nuno; Belmonte-de-Abreu, Paulo

    2012-01-01

    Schizophrenia is a neurodevelopment disorder in which the interplay of genes and environment contributes to disease onset and establishment. The most consistent pathological feature in schizophrenic patients is an enlargement of the brain ventricles. Yet, so far, no study has related this finding with dysfunction of the choroid plexus (CP), the epithelial cell monolayer located within the brain ventricles that is responsible for the production of most of the cerebrospinal fluid (CSF). Enlarged brain ventricles are already present at the time of disease onset (young adulthood) and, of notice, isolated mild ventriculomegaly detected in utero is associated with subsequent mild neurodevelopmental abnormalities similar to those observed in children at high risk of developing schizophrenia. Here we propose that altered CP/CSF dynamics during neurodevelopment may be considered a risk, causative and/or participating factor for development of schizophrenia. PMID:22891052

  10. New insights into the heating mechanisms and self-regulating abilities of manganite perovskite nanoparticles suitable for magnetic fluid hyperthermia

    NASA Astrophysics Data System (ADS)

    Natividad, Eva; Castro, Miguel; Goglio, Graziella; Andreu, Irene; Epherre, Romain; Duguet, Etienne; Mediano, Arturo

    2012-06-01

    The heating and self-regulating abilities of La1-xSrxMnO3+Δ ferromagnetic nanoparticles for magnetic fluid hyperthermia are studied. The samples, synthesized by the Glycine Nitrate Process, present non-agglomerated particles but are partially constituted by polycrystalline nanoparticles, displaying average crystallite diameters ranging from 21 to 31 nm. The strontium content of these nanoparticles, between 0.14 and 0.39, is associated with non-stoichiometry effects in the materials, and both govern their Curie temperatures (TC), which range between 13 and 86 °C, respectively. Heating experiments carried out on samples suspended in an aqueous agarose gel and with different alternating magnetic fields derive unexpected maximum temperatures that cannot be explained on the basis of static magnetization data. The measurement of the thermal dependence of the specific absorption rate (SAR) of nanopowders by adiabatic magnetothermia reveals the existence of a dissipation peak just below TC, which is assigned to a Hopkinson peak. This thermal dependence of SAR, together with a simple thermal model that considers a linear approximation for the heat power losses, is crucial to clarify the behavior observed in heating experiments and also to discuss the possibilities of the samples as self-regulating hyperthermia mediators. This analysis emphasizes that, for the correct design of a self-regulating system, the heat power losses determined by the surrounding conditions must be taken into account as well as the heating capacity of the magnetic nanoparticles.

  11. New insights into the heating mechanisms and self-regulating abilities of manganite perovskite nanoparticles suitable for magnetic fluid hyperthermia.

    PubMed

    Natividad, Eva; Castro, Miguel; Goglio, Graziella; Andreu, Irene; Epherre, Romain; Duguet, Etienne; Mediano, Arturo

    2012-07-01

    The heating and self-regulating abilities of La(1-x)Sr(x)MnO(3+Δ) ferromagnetic nanoparticles for magnetic fluid hyperthermia are studied. The samples, synthesized by the Glycine Nitrate Process, present non-agglomerated particles but are partially constituted by polycrystalline nanoparticles, displaying average crystallite diameters ranging from 21 to 31 nm. The strontium content of these nanoparticles, between 0.14 and 0.39, is associated with non-stoichiometry effects in the materials, and both govern their Curie temperatures (T(C)), which range between 13 and 86 °C, respectively. Heating experiments carried out on samples suspended in an aqueous agarose gel and with different alternating magnetic fields derive unexpected maximum temperatures that cannot be explained on the basis of static magnetization data. The measurement of the thermal dependence of the specific absorption rate (SAR) of nanopowders by adiabatic magnetothermia reveals the existence of a dissipation peak just below T(C), which is assigned to a Hopkinson peak. This thermal dependence of SAR, together with a simple thermal model that considers a linear approximation for the heat power losses, is crucial to clarify the behavior observed in heating experiments and also to discuss the possibilities of the samples as self-regulating hyperthermia mediators. This analysis emphasizes that, for the correct design of a self-regulating system, the heat power losses determined by the surrounding conditions must be taken into account as well as the heating capacity of the magnetic nanoparticles. PMID:22653748

  12. Encapsulated ionic liquids (ENILs): from continuous to discrete liquid phase.

    PubMed

    Palomar, Jose; Lemus, Jesus; Alonso-Morales, Noelia; Bedia, Jorge; Gilarranz, Miguel A; Rodriguez, Juan J

    2012-10-14

    Encapsulated ionic liquid (ENIL) material was developed, consisting of ionic liquid (IL) introduced into carbon submicrocapsules. ENILs contain >85% w/w of IL but discretized in submicroscopic encapsulated drops, drastically increasing the surface contact area with respect to the neat fluid. ENIL materials were here tested for gas separation processes, obtaining a drastic increase in mass transfer rate. PMID:22935733

  13. Role of Microvascular Tone and Extracellular Matrix Contraction in the Regulation of Interstitial Fluid: Implications for Aortic Dissection.

    PubMed

    Mallat, Ziad; Tedgui, Alain; Henrion, Daniel

    2016-09-01

    The pathophysiology of aortic dissection is poorly understood, and its risk is resistant to medical treatment. Most studies have focused on a proposed pathogenic role of transforming growth factor-β in Marfan disease and related thoracic aortic aneurysms and aortic dissections. However, clinical testing of this concept using angiotensin II type 1 receptor antagonists to block transforming growth factor-β signaling fell short of promise. Genetic mutations that predispose to thoracic aortic aneurysms and aortic dissections affect components of the extracellular matrix and proteins involved in cellular force generation. Thus, a role for dysfunctional mechanosensing in abnormal aortic wall remodeling is emerging. However, how abnormal mechanosensing leads to aortic dissection remains a mystery. Here, we review current knowledge about the regulation of interstitial fluid dynamics and myogenic tone and propose that alteration in contractile force reduces vascular tone in the microcirculation (here, aortic vasa vasorum) and leads to elevations of blood flow, transmural pressure, and fluid flux into the surrounding aortic media. Furthermore, reduced contractile force in medial smooth muscle cells coupled with alteration of structural components of the extracellular matrix limits extracellular matrix contraction, further promoting the formation of intramural edema, a critical step in the initiation of aortic dissection. The concept is supported by several pathophysiological and clinical observations. A direct implication of this concept is that drugs that lower blood pressure and limit interstitial fluid accumulation while preserving or increasing microvascular tone would limit the risk of dissection. In contrast, drugs that substantially lower microvascular tone would be ineffective or may accelerate the disease and precipitate aortic dissection. PMID:27444198

  14. Ca(2+) regulates fluid shear-induced cytoskeletal reorganization and gene expression in osteoblasts

    NASA Technical Reports Server (NTRS)

    Chen, N. X.; Ryder, K. D.; Pavalko, F. M.; Turner, C. H.; Burr, D. B.; Qiu, J.; Duncan, R. L.

    2000-01-01

    Osteoblasts subjected to fluid shear increase the expression of the early response gene, c-fos, and the inducible isoform of cyclooxygenase, COX-2, two proteins linked to the anabolic response of bone to mechanical stimulation, in vivo. These increases in gene expression are dependent on shear-induced actin stress fiber formation. Here, we demonstrate that MC3T3-E1 osteoblast-like cells respond to shear with a rapid increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) that we postulate is important to subsequent cellular responses to shear. To test this hypothesis, MC3T3-E1 cells were grown on glass slides coated with fibronectin and subjected to laminar fluid flow (12 dyn/cm(2)). Before application of shear, cells were treated with two Ca(2+) channel inhibitors or various blockers of intracellular Ca(2+) release for 0. 5-1 h. Although gadolinium, a mechanosensitive channel blocker, significantly reduced the [Ca(2+)](i) response, neither gadolinium nor nifedipine, an L-type channel Ca(2+) channel blocker, were able to block shear-induced stress fiber formation and increase in c-fos and COX-2 in MC3T3-E1 cells. However, 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, an intracellular Ca(2+) chelator, or thapsigargin, which empties intracellular Ca(2+) stores, completely inhibited stress fiber formation and c-fos/COX-2 production in sheared osteoblasts. Neomycin or U-73122 inhibition of phospholipase C, which mediates D-myo-inositol 1,4,5-trisphosphate (IP(3))-induced intracellular Ca(2+) release, also completely suppressed actin reorganization and c-fos/COX-2 production. Pretreatment of MC3T3-E1 cells with U-73343, the inactive isoform of U-73122, did not inhibit these shear-induced responses. These results suggest that IP(3)-mediated intracellular Ca(2+) release is required for modulating flow-induced responses in MC3T3-E1 cells.

  15. Osteocytes subjected to pulsating fluid flow regulate osteoblast proliferation and differentiation

    SciTech Connect

    Vezeridis, Peter S.; Chen Qian . E-mail: j.kleinnulend@vumc.nl

    2006-09-29

    Osteocytes are thought to orchestrate bone remodeling, but it is unclear exactly how osteocytes influence neighboring bone cells. Here, we tested whether osteocytes, osteoblasts, and periosteal fibroblasts subjected to pulsating fluid flow (PFF) produce soluble factors that modulate the proliferation and differentiation of cultured osteoblasts and periosteal fibroblasts. We found that osteocyte PFF conditioned medium (CM) inhibited bone cell proliferation, and osteocytes produced the strongest inhibition of proliferation compared to osteoblasts and periosteal fibroblasts. The nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) attenuated the inhibitory effects of osteocyte PFF CM, suggesting that a change in NO release is at least partially responsible for the inhibitory effects of osteocyte PFF CM. Furthermore, osteocyte PFF CM stimulated osteoblast differentiation measured as increased alkaline phosphatase activity, and L-NAME decreased the stimulatory effects of osteocyte PFF CM on osteoblast differentiation. We conclude that osteocytes subjected to PFF inhibit proliferation but stimulate differentiation of osteoblasts in vitro via soluble factors and that the release of these soluble factors was at least partially dependent on the activation of a NO pathway in osteocytes in response to PFF. Thus, the osteocyte appears to be more responsive to PFF than the osteoblast or periosteal fibroblast with respect to the production of soluble signaling molecules affecting osteoblast proliferation and differentiation.

  16. Thermodynamics and micro heterogeneity of ionic liquids.

    PubMed

    Gomes, Margarida F Costa; Lopes, J N Canongia; Padua, A A H

    2010-01-01

    The high degree of organisation in the fluid phase of room-temperature ionic liquids has major consequences on their macroscopic properties, namely on their behaviour as solvents. This nanoscale self-organisation is the result of an interplay between two types of interaction in the liquid phase - Coulomb and van der Waals - that eventually leads to the formation of medium-range structures and the recognition of some ionic liquids as composed of a high-charge density, cohesive network permeated by low-charge density regions.In this chapter, the structure of the ionic liquids will be explored and some of their consequences to the properties of ionic liquids analyzed. PMID:21107797

  17. Evolutionary development of embryonic cerebrospinal fluid composition and regulation: an open research field with implications for brain development and function.

    PubMed

    Bueno, David; Garcia-Fernàndez, Jordi

    2016-01-01

    this review, we draw together existing literature about the formation, function and homeostatic regulation of embryonic cerebrospinal fluid, from the closure of the anterior neuropore to the formation of functional fetal choroid plexuses, from an evolutionary perspective. The relevance of these processes to the normal functions and diseases of adult brain will also be discussed. PMID:26979569

  18. Role of the RVM in Descending Pain Regulation Originating from the Cerebrospinal Fluid-Contacting Nucleus.

    PubMed

    Fei, Yan; Wang, Xin; Chen, Songsong; Zhou, Qiangqiang; Zhang, Chao; Li, Ying; Sun, Lihong; Zhang, Licai

    2016-07-01

    Evidence has suggested that cerebrospinal fluid-contacting nucleus (CSF-contacting nucleus) is correlated with the development and recurrence of pain. A recent research showed that the CSF-contacting nucleus acts as a component of the descending 5-hydroxytryptamine (5-HT) system and plays a role in descending pain inhibition. However, limited studies are conducted to investigate the relationship between the CSF-contacting nucleus and pain. In present study, we explored the effect of CSF-contacting nucleus on nociceptive behaviors in both normal and neuropathic rats via targeted ablation of the CSF-contacting nucleus in the brainstem, using cholera toxin subunit B-saporin (CB-SAP), a cytotoxin coupled to cholera toxin subunit B. The CB-SAP-treated rats showed aggravated thermal hyperalgesia and mechanical allodynia. Also, results from immunohistochemical experiments showed that rostral ventromedial medulla (RVM) received fiber projection from the CSF-contacting nucleus, which disappeared after ablation of the CSF-contacting nucleus, and the CB-SAP treated rats showed downregulation of c-Fos expression in the RVM as compared with the rats receiving i.c.v. injection of phosphate buffer saline (PBS). A significant downregulation of 5-HT-labeled neurons and tryptophan hydroxylase 2 (TPH2) as the marker of 5-HT cells in the RVM, and 5-HT expression in spinal dorsal horn in both normal and chronic constriction injury (CCI) rats after i.c.v. injection of CB-SAP was observed. These results suggested that RVM may be involved in descending pain modulation originating from the CSF-contacting nucleus. PMID:26961890

  19. Acidic Ionic Liquids.

    PubMed

    Amarasekara, Ananda S

    2016-05-25

    Ionic liquid with acidic properties is an important branch in the wide ionic liquid field and the aim of this article is to cover all aspects of these acidic ionic liquids, especially focusing on the developments in the last four years. The structural diversity and synthesis of acidic ionic liquids are discussed in the introduction sections of this review. In addition, an unambiguous classification system for various types of acidic ionic liquids is presented in the introduction. The physical properties including acidity, thermo-physical properties, ionic conductivity, spectroscopy, and computational studies on acidic ionic liquids are covered in the next sections. The final section provides a comprehensive review on applications of acidic ionic liquids in a wide array of fields including catalysis, CO2 fixation, ionogel, electrolyte, fuel-cell, membrane, biomass processing, biodiesel synthesis, desulfurization of gasoline/diesel, metal processing, and metal electrodeposition. PMID:27175515

  20. Fluid Flows and Their Role in the Regulation of Biological Molecules in the Bloodstream

    NASA Astrophysics Data System (ADS)

    Sing, Charles; Alexander-Katz, Alfredo

    2010-03-01

    We use computer simulations to elucidate the physics underlying blood clotting mechanisms. A straightforward and general model for the behavior of proteins such as von Willebrand Factor (vWF) under various flow conditions has been developed. The particular case of vWF is considered in depth, since it demonstrates the counter-intuitive behavior of adsorbing to a surface at higher flow rates. We use the globule-stretch transition of a collapsed polymer to explain this phenomenon, and have identified the conditions necessary to induce this transition. We have also developed a theory to explain the mechanism of this transition, which is based on the nucleation and growth of large thermal protrusions. Upon the consideration of the specific length and time scales present under biological conditions, it is apparent that vWF is strongly regulated by elongational flows. We can show how phenomena from the molecular to physiological levels are supplemented by this understanding of vWF function.

  1. Endothelial mitochondria regulate the intracellular Ca2+ response to fluid shear stress.

    PubMed

    Scheitlin, Christopher G; Julian, Justin A; Shanmughapriya, Santhanam; Madesh, Muniswamy; Tsoukias, Nikolaos M; Alevriadou, B Rita

    2016-03-15

    Shear stress is known to stimulate an intracellular free calcium concentration ([Ca(2+)]i) response in vascular endothelial cells (ECs). [Ca(2+)]i is a key second messenger for signaling that leads to vasodilation and EC survival. Although it is accepted that the shear-induced [Ca(2+)]i response is, in part, due to Ca(2+) release from the endoplasmic reticulum (ER), the role of mitochondria (second largest Ca(2+) store) is unknown. We hypothesized that the mitochondria play a role in regulating [Ca(2+)]i in sheared ECs. Cultured ECs, loaded with a Ca(2+)-sensitive fluorophore, were exposed to physiological levels of shear stress. Shear stress elicited [Ca(2+)]i transients in a percentage of cells with a fraction of them displaying oscillations. Peak magnitudes, percentage of oscillating ECs, and oscillation frequencies depended on the shear level. [Ca(2+)]i transients/oscillations were present when experiments were conducted in Ca(2+)-free solution (plus lanthanum) but absent when ECs were treated with a phospholipase C inhibitor, suggesting that the ER inositol 1,4,5-trisphosphate receptor is responsible for the [Ca(2+)]i response. Either a mitochondrial uncoupler or an electron transport chain inhibitor, but not a mitochondrial ATP synthase inhibitor, prevented the occurrence of transients and especially inhibited the oscillations. Knockdown of the mitochondrial Ca(2+) uniporter also inhibited the shear-induced [Ca(2+)]i transients/oscillations compared with controls. Hence, EC mitochondria, through Ca(2+) uptake/release, regulate the temporal profile of shear-induced ER Ca(2+) release. [Ca(2+)]i oscillation frequencies detected were within the range for activation of mechanoresponsive kinases and transcription factors, suggesting that dysfunctional EC mitochondria may contribute to cardiovascular disease by deregulating the shear-induced [Ca(2+)]i response. PMID:26739489

  2. The effect of skull and dura on brain volume regulation after hypo- and hyperosmolar fluid treatment.

    PubMed

    Kuncz, A; Dóczi, T; Bodosi, M

    1990-10-01

    This study was performed to determine the response of brain water and electrolytes to acute hypo-osmolality and hyperosmolality in animals with intact skulls and dura, in comparison with those subjected to extensive bilateral or unilateral craniectomy and opening of the dura. In rats, 4 to 5 weeks after extensive unilateral or bilateral craniectomy and opening of the dura, a 50-mOsm/kg decrease in plasma osmolality was produced by systemic administration of distilled water ("water intoxication"), or a 28-mOsm/kg increase in plasma osmolality was produced by systemic administration of either 1 M NaCl or 1 M mannitol in 0.34 M NaCl. Tissue water, Na. and K contents were determined after 120 minutes. Tissue water accumulation or water loss was proportional to the decrease or increase in plasma osmolality. The tissue water accumulation after "water intoxication," however, was less (40% of the predicted value) than that predicted for ideal osmotic behavior. The brain tissue was also found to shrink less than predicted on the basis of ideal osmotic behavior (40% of the predicted value after mannitol treatment, and 60% after NaCl administration). This nonideal osmotic response of the brain tissue is consistent with the finding in other studies and indicated a significant degree of volume regulation. Water and electrolyte changes did not differ between animals operated on and those not operated on, a fact which demonstrates that there are no effects of extensive skull and dura defects on tissue volume regulation under hypo- and hyperosmolar conditions encountered under clinical circumstances.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2122273

  3. Ionic electrostatic excitations along biological membranes

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2011-02-01

    A theoretical analysis of ionic electrostatic excitations of a charged biological membrane is presented within the framework of the fluid theory for surface ions inside and outside the cell, in conjunction with the Poisson's equation. General expressions of dispersion relations are obtained for electrostatic oscillations of intrinsic cellular with different shapes and symmetries.

  4. Cerebrospinal fluid protein and glucose examinations and tuberculosis:
Will laboratory safety regulations force a change of practice?

    PubMed Central

    Tormey, William P.; O’Hagan, Christopher

    2015-01-01

    Cerebrospinal fluid (CSF) protein and glucose examinations are usually performed in chemical pathology departments on autoanalysers. Tuberculosis (TB) is a group 3 biological agent under Directive 2000/54/EC of the European Parliament but in the biochemistry laboratory, no extra precautions are taken in its analysis in possible TB cases. The issue of laboratory practice and safety in the biochemical analyses of CSF specimens, when tuberculosis infection is in question is addressed in the context of ambiguity in the implementation of current national and international health and safety regulations. Additional protective measures for laboratory staff during the analysis of CSF TB samples should force a change in current laboratory practice and become a regulatory issue under ISO 15189. Annual Mantoux skin test or an interferon-γ release assay for TB should be mandatory for relevant staff. This manuscript addresses the issue of biochemistry laboratory practice and safety in the biochemical analyses of CSF specimens when tuberculosis infection is in question in the context of the ambiguity of statutory health and safety regulations. PMID:26526598

  5. Extracellular signal-regulated kinase 5 in the cerebrospinal fluid-contacting nucleus contributes to morphine physical dependence in rats.

    PubMed

    Wang, Chun-Guang; Ding, Yan-Ling; Zheng, Tian-Fang; Wei, Jing-Qiu; Liu, He; Chen, Yu-Feng; Wang, Jia-You; Zhang, Li-Cai

    2013-05-01

    The cerebrospinal fluid-contacting nucleus (CSF-CN) may influence actual composition of the CSF for non-synaptic signal transmission via releasing or absorbing bioactive substances, which distributes and localizes in the ventral periaqueductal central gray of the brainstem. Previous studies demonstrated that CSF-CN was involved in neuropathic pain and morphine dependence. Thus, to identify whether extracellular signal-regulated kinase 5 (ERK5) distributed in the CSF-CN and its function on the formation and development of morphine physical dependence, morphine withdrawal-like behavioral test and immunofluorescent technique were used in this research. Morphine was subcutaneously injected by an intermittent and escalating procedure to induce physical dependence, which was measured by withdrawal symptoms. In this study, we found that horseradish peroxidase-conjugated toxin subunit B/p-ERK5 double-labeled neurons expressed in the CSF-CN of normal rats. ERK5 signaling pathway was remarkably activated by naloxone-precipitated withdrawal in the CSF-CN. Moreover, selective attenuation of p-ERK5 expression in the CSF-CN by lateral ventricle injection of BIX02188 could significantly relieve morphine withdrawal symptom. These findings confirmed that the activation of p-ERK5 in the CSF-CN might contribute to morphine physical dependence. PMID:23143893

  6. Ionic Vapor Composition in Critical and Supercritical States of Strongly Interacting Ionic Compounds.

    PubMed

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-05-12

    The critical point, CP (T, P), of the phase diagram quantifies the minimum amount of kinetic energy needed to prevent a substance from existing in a condensed phase. Therefore, the CP is closely related to the properties of the fluid far below the critical temperature. Approaches designed to predict thermophysical properties of a system necessarily aim to provide reliable estimates of the CP. Vice versa, CP estimation is impossible without knowledge of the vapor phase behavior. We report ab initio Born-Oppenheimer molecular dynamics (BOMD) simulations of sodium and potassium chlorides, NaCl and KCl, at and above their expected CPs. We advance the present knowledge regarding the existence of ionic species in the vapor phase by establishing significant percentages of atomic clusters: 29-30% in NaCl and 34-38% in KCl. A neutral pair of counterions is the most abundant cluster in the ionic vapors (ca. 35% of all vaporized ions exist in this form). Unexpectedly, an appreciable fraction of clusters is charged. The ionic vapor composition is determined by the vapor density, rather than the nature of the alkali ion. The previously suggested CPs of NaCl and KCl appear overestimated, based on the present simulations. The reported results offer essential insights into the ionic fluid properties and assist in development of thermodynamic theories. The ab initio BOMD method has been applied to investigate the vapor phase composition of an ionic fluid for the first time. PMID:27100933

  7. Hypercapnia modulates cAMP signalling and cystic fibrosis transmembrane conductance regulator-dependent anion and fluid secretion in airway epithelia.

    PubMed

    Turner, Mark J; Saint-Criq, Vinciane; Patel, Waseema; Ibrahim, Salam H; Verdon, Bernard; Ward, Christopher; Garnett, James P; Tarran, Robert; Cann, Martin J; Gray, Michael A

    2016-03-15

    Hypercapnia is clinically defined as an arterial blood partial pressure of CO2 of above 40 mmHg and is a feature of chronic lung disease. In previous studies we have demonstrated that hypercapnia modulates agonist-stimulated cAMP levels through effects on transmembrane adenylyl cyclase activity. In the airways, cAMP is known to regulate cystic fibrosis transmembrane conductance regulator (CFTR)-mediated anion and fluid secretion, which contributes to airway surface liquid homeostasis. The aim of the current work was to investigate if hypercapnia could modulate cAMP-regulated ion and fluid transport in human airway epithelial cells. We found that acute exposure to hypercapnia significantly reduced forskolin-stimulated elevations in intracellular cAMP as well as both adenosine- and forskolin-stimulated increases in CFTR-dependent transepithelial short-circuit current, in polarised cultures of Calu-3 human airway cells. This CO2 -induced reduction in anion secretion was not due to a decrease in HCO3 (-) transport given that neither a change in CFTR-dependent HCO3 (-) efflux nor Na(+) /HCO3 (-) cotransporter-dependent HCO3 (-) influx were CO2 -sensitive. Hypercapnia also reduced the volume of forskolin-stimulated fluid secretion over 24 h, yet had no effect on the HCO3 (-) content of the secreted fluid. Our data reveal that hypercapnia reduces CFTR-dependent, electrogenic Cl(-) and fluid secretion, but not CFTR-dependent HCO3 (-) secretion, which highlights a differential sensitivity of Cl(-) and HCO3 (-) transporters to raised CO2 in Calu-3 cells. Hypercapnia also reduced forskolin-stimulated CFTR-dependent anion secretion in primary human airway epithelia. Based on current models of airways biology, a reduction in fluid secretion, associated with hypercapnia, would be predicted to have important consequences for airways hydration and the innate defence mechanisms of the lungs. PMID:26574187

  8. FLUID SECRETION BY SUBMUCOSAL GLANDS OF THE TRACHEOBRONCHIAL AIRWAYS

    PubMed Central

    Ballard, Stephen T.; Spadafora, Domenico

    2009-01-01

    Submucosal glands of the tracheobronchial airways provide the important functions of secreting mucins, antimicrobial substances, and fluid. This review focuses on the ionic mechanism and regulation of gland fluid secretion and examines the possible role of gland dysfunction in the lethal disease cystic fibrosis (CF). The fluid component of gland secretion is driven by the active transepithelial secretion of both Cl− and HCO3− by serous cells. Gland fluid secretion is neurally regulated with acetylcholine, substance P, and vasoactive intestinal peptide (VIP) playing prominent roles. The cystic fibrosis transmembrane conductance regulator (CFTR) is present in the apical membrane of gland serous cells and mediates the VIP-induced component of liquid secretion whereas the muscarinic component of liquid secretion appears to be at least partially CFTR-independent. Loss of CFTR function, which occurs in CF disease, reduces the capacity of glands to secrete fluid but not mucins. The possible links between the loss of fluid secretion capability and the complex airway pathology of CF are discussed. PMID:17707699

  9. Noble metal ionic catalysts.

    PubMed

    Hegde, M S; Madras, Giridhar; Patil, K C

    2009-06-16

    Because of growing environmental concerns and increasingly stringent regulations governing auto emissions, new more efficient exhaust catalysts are needed to reduce the amount of pollutants released from internal combustion engines. To accomplish this goal, the major pollutants in exhaust-CO, NO(x), and unburned hydrocarbons-need to be fully converted to CO(2), N(2), and H(2)O. Most exhaust catalysts contain nanocrystalline noble metals (Pt, Pd, Rh) dispersed on oxide supports such as Al(2)O(3) or SiO(2) promoted by CeO(2). However, in conventional catalysts, only the surface atoms of the noble metal particles serve as adsorption sites, and even in 4-6 nm metal particles, only 1/4 to 1/5 of the total noble metal atoms are utilized for catalytic conversion. The complete dispersion of noble metals can be achieved only as ions within an oxide support. In this Account, we describe a novel solution to this dispersion problem: a new solution combustion method for synthesizing dispersed noble metal ionic catalysts. We have synthesized nanocrystalline, single-phase Ce(1-x)M(x)O(2-delta) and Ce(1-x-y)Ti(y)M(x)O(2-delta) (M = Pt, Pd, Rh; x = 0.01-0.02, delta approximately x, y = 0.15-0.25) oxides in fluorite structure. In these oxide catalysts, Pt(2+), Pd(2+), or Rh(3+) ions are substituted only to the extent of 1-2% of Ce(4+) ion. Lower-valent noble metal ion substitution in CeO(2) creates oxygen vacancies. Reducing molecules (CO, H(2), NH(3)) are adsorbed onto electron-deficient noble metal ions, while oxidizing (O(2), NO) molecules are absorbed onto electron-rich oxide ion vacancy sites. The rates of CO and hydrocarbon oxidation and NO(x) reduction (with >80% N(2) selectivity) are 15-30 times higher in the presence of these ionic catalysts than when the same amount of noble metal loaded on an oxide support is used. Catalysts with palladium ion dispersed in CeO(2) or Ce(1-x)Ti(x)O(2) were far superior to Pt or Rh ionic catalysts. Therefore, we have demonstrated that the

  10. Hydrogen sulfide induces systemic tolerance to salinity and non-ionic osmotic stress in strawberry plants through modification of reactive species biosynthesis and transcriptional regulation of multiple defence pathways.

    PubMed

    Christou, Anastasis; Manganaris, George A; Papadopoulos, Ioannis; Fotopoulos, Vasileios

    2013-04-01

    Hydrogen sulfide (H2S) has been recently found to act as a potent priming agent. This study explored the hypothesis that hydroponic pretreatment of strawberry (Fragaria × ananassa cv. Camarosa) roots with a H2S donor, sodium hydrosulfide (NaHS; 100 μM for 48 h), could induce long-lasting priming effects and tolerance to subsequent exposure to 100mM NaCI or 10% (w/v) PEG-6000 for 7 d. Hydrogen sulfide pretreatment of roots resulted in increased leaf chlorophyll fluorescence, stomatal conductance and leaf relative water content as well as lower lipid peroxidation levels in comparison with plants directly subjected to salt and non-ionic osmotic stress, thus suggesting a systemic mitigating effect of H2S pretreatment to cellular damage derived from abiotic stress factors. In addition, root pretreatment with NaHS resulted in the minimization of oxidative and nitrosative stress in strawberry plants, manifested via lower levels of synthesis of NO and H(2)O(2) in leaves and the maintenance of high ascorbate and glutathione redox states, following subsequent salt and non-ionic osmotic stresses. Quantitative real-time RT-PCR gene expression analysis of key antioxidant (cAPX, CAT, MnSOD, GR), ascorbate and glutathione biosynthesis (GCS, GDH, GS), transcription factor (DREB), and salt overly sensitive (SOS) pathway (SOS2-like, SOS3-like, SOS4) genes suggests that H2S plays a pivotal role in the coordinated regulation of multiple transcriptional pathways. The ameliorative effects of H2S were more pronounced in strawberry plants subjected to both stress conditions immediately after NaHS root pretreatment, rather than in plants subjected to stress conditions 3 d after root pretreatment. Overall, H2S-pretreated plants managed to overcome the deleterious effects of salt and non-ionic osmotic stress by controlling oxidative and nitrosative cellular damage through increased performance of antioxidant mechanisms and the coordinated regulation of the SOS pathway, thus proposing a

  11. Hydrogen sulfide induces systemic tolerance to salinity and non-ionic osmotic stress in strawberry plants through modification of reactive species biosynthesis and transcriptional regulation of multiple defence pathways

    PubMed Central

    Christou, Anastasis; Manganaris, George A.; Papadopoulos, Ioannis; Fotopoulos, Vasileios

    2013-01-01

    Hydrogen sulfide (H2S) has been recently found to act as a potent priming agent. This study explored the hypothesis that hydroponic pretreatment of strawberry (Fragaria × ananassa cv. Camarosa) roots with a H2S donor, sodium hydrosulfide (NaHS; 100 μM for 48h), could induce long-lasting priming effects and tolerance to subsequent exposure to 100mM NaCI or 10% (w/v) PEG-6000 for 7 d. Hydrogen sulfide pretreatment of roots resulted in increased leaf chlorophyll fluorescence, stomatal conductance and leaf relative water content as well as lower lipid peroxidation levels in comparison with plants directly subjected to salt and non-ionic osmotic stress, thus suggesting a systemic mitigating effect of H2S pretreatment to cellular damage derived from abiotic stress factors. In addition, root pretreatment with NaHS resulted in the minimization of oxidative and nitrosative stress in strawberry plants, manifested via lower levels of synthesis of NO and H2O2 in leaves and the maintenance of high ascorbate and glutathione redox states, following subsequent salt and non-ionic osmotic stresses. Quantitative real-time RT-PCR gene expression analysis of key antioxidant (cAPX, CAT, MnSOD, GR), ascorbate and glutathione biosynthesis (GCS, GDH, GS), transcription factor (DREB), and salt overly sensitive (SOS) pathway (SOS2-like, SOS3-like, SOS4) genes suggests that H2S plays a pivotal role in the coordinated regulation of multiple transcriptional pathways. The ameliorative effects of H2S were more pronounced in strawberry plants subjected to both stress conditions immediately after NaHS root pretreatment, rather than in plants subjected to stress conditions 3 d after root pretreatment. Overall, H2S-pretreated plants managed to overcome the deleterious effects of salt and non-ionic osmotic stress by controlling oxidative and nitrosative cellular damage through increased performance of antioxidant mechanisms and the coordinated regulation of the SOS pathway, thus proposing a novel

  12. Fluid imbalance

    MedlinePlus

    ... up in the body. This is called fluid overload (volume overload). This can lead to edema (excess fluid in ... Water imbalance; Fluid imbalance - dehydration; Fluid buildup; Fluid overload; Volume overload; Loss of fluids; Edema - fluid imbalance; ...

  13. Electroosmotic flow hysteresis for dissimilar ionic solutions.

    PubMed

    Lim, An Eng; Lim, Chun Yee; Lam, Yee Cheong

    2015-03-01

    Electroosmotic flow (EOF) with two or more fluids is commonly encountered in various microfluidics applications. However, no investigation has hitherto been conducted to investigate the hysteretic or flow direction-dependent behavior during the displacement flow of solutions with dissimilar ionic species. In this investigation, electroosmotic displacement flow involving dissimilar ionic solutions was studied experimentally through a current monitoring method and numerically through finite element simulations. The flow hysteresis can be characterized by the turning and displacement times; turning time refers to the abrupt gradient change of current-time curve while displacement time is the time for one solution to completely displace the other solution. Both experimental and simulation results illustrate that the turning and displacement times for a particular solution pair can be directional-dependent, indicating that the flow conditions in the microchannel are not the same in the two different flow directions. The mechanics of EOF hysteresis was elucidated through the theoretical model which includes the ionic mobility of each species, a major governing parameter. Two distinct mechanics have been identified as the causes for the EOF hysteresis involving dissimilar ionic solutions: the widening/sharpening effect of interfacial region between the two solutions and the difference in ion concentration distributions (and thus average zeta potentials) in different flow directions. The outcome of this investigation contributes to the fundamental understanding of flow behavior in microfluidic systems involving solution pair with dissimilar ionic species. PMID:25945139

  14. Electroosmotic flow hysteresis for dissimilar ionic solutions

    PubMed Central

    Lim, An Eng; Lam, Yee Cheong

    2015-01-01

    Electroosmotic flow (EOF) with two or more fluids is commonly encountered in various microfluidics applications. However, no investigation has hitherto been conducted to investigate the hysteretic or flow direction-dependent behavior during the displacement flow of solutions with dissimilar ionic species. In this investigation, electroosmotic displacement flow involving dissimilar ionic solutions was studied experimentally through a current monitoring method and numerically through finite element simulations. The flow hysteresis can be characterized by the turning and displacement times; turning time refers to the abrupt gradient change of current-time curve while displacement time is the time for one solution to completely displace the other solution. Both experimental and simulation results illustrate that the turning and displacement times for a particular solution pair can be directional-dependent, indicating that the flow conditions in the microchannel are not the same in the two different flow directions. The mechanics of EOF hysteresis was elucidated through the theoretical model which includes the ionic mobility of each species, a major governing parameter. Two distinct mechanics have been identified as the causes for the EOF hysteresis involving dissimilar ionic solutions: the widening/sharpening effect of interfacial region between the two solutions and the difference in ion concentration distributions (and thus average zeta potentials) in different flow directions. The outcome of this investigation contributes to the fundamental understanding of flow behavior in microfluidic systems involving solution pair with dissimilar ionic species. PMID:25945139

  15. Carbon Dioxide and Ionic Liquid Refrigerants: Compact, Efficient Air Conditioning with Ionic Liquid-Based Refrigerants

    SciTech Connect

    2010-10-01

    BEETIT Project: Notre Dame is developing an air-conditioning system with a new ionic liquid and CO2 as the working fluid. Synthetic refrigerants used in air conditioning and refrigeration systems are potent GHGs and can trap 1,000 times more heat in the atmosphere than CO2 alone—making CO2 an attractive alternative for synthetic refrigerants in cooling systems. However, operating cooling systems with pure CO2 requires prohibitively high pressures and expensive hardware. Notre Dame is creating a new fluid made of CO2 and ionic liquid that enables the use of CO2 at low pressures and requires minimal changes to existing hardware and production lines. This new fluid also produces no harmful emissions and can improve the efficiency of air conditioning systems— enabling new use of CO2 as a refrigerant in cooling systems.

  16. Ionic regulation and Na(+)-K(+)-ATPase activity in gills and kidney of the freshwater stingray Paratrygon aiereba living in white and blackwaters in the Amazon Basin.

    PubMed

    Duncan, W P; Costa, O T F; Araújo, M L G; Fernandes, M N

    2009-03-01

    During low-water period, freshwater stingray Paratrygon aiereba collected in the whitewater (WW) of the River Amazon showed higher urea content, osmolality, Na(+) and Cl(-) concentrations in plasma and perivisceral fluid than those caught in blackwater (BW) of the River Negro. Gills and kidney Na(+)-K(+)-ATPase activities were significantly lower in WW than in BW fish. The high level of kidney Na(+)-K(+)-ATPase activity in P. aiereba may minimize ion loss and generate diluted solute-free urine in ion-poor BW environment. PMID:20735610

  17. Neuroendocrine control of ionic balance in zebrafish.

    PubMed

    Kwong, Raymond W M; Kumai, Yusuke; Perry, Steve F

    2016-08-01

    Zebrafish (Danio rerio) is an emerging model for integrative physiological research. In this mini-review, we discuss recent advances in the neuroendocrine control of ionic balance in this species, and identify current knowledge gaps and issues that would benefit from further investigation. Zebrafish inhabit a hypo-ionic environment and therefore are challenged by a continual loss of ions to the water. To maintain ionic homeostasis, they must actively take up ions from the water and reduce passive ion loss. The adult gill or the skin of larvae are the primary sites of ionic regulation. Current models for the uptake of major ions in zebrafish incorporate at least three types of ion transporting cells (also called ionocytes); H(+)-ATPase-rich cells for Na(+) uptake, Na(+)/K(+)-ATPase-rich cells for Ca(2+) uptake, and Na(+)/Cl(-)-cotransporter expressing cells for both Na(+) and Cl(-) uptake. The precise molecular mechanisms regulating the paracellular loss of ions remain largely unknown. However, epithelial tight junction proteins, including claudins, are thought to play a critical role in reducing ion losses to the surrounding water. Using the zebrafish model, several key neuroendocrine factors were identified as regulators of epithelial ion movement, including the catecholamines (adrenaline and noradrenaline), cortisol, the renin-angiotensin system, parathyroid hormone and prolactin. Increasing evidence also suggests that gasotransmitters, such as H2S, are involved in regulating ion uptake. PMID:27179885

  18. Drilling fluid containing crosslinked polysaccharide derivative

    SciTech Connect

    Demott, D.N.; Kucera, C.H.

    1981-03-24

    A drilling fluid having extremely desirable physical properties which comprises an aqueous solution of a hydroxyalkyl polysaccharide derivative and a water soluble ionic aluminum crosslinking agent, preferably sodium aluminate.

  19. Fluid Shear Stress Regulates the Invasive Potential of Glioma Cells via Modulation of Migratory Activity and Matrix Metalloproteinase Expression

    PubMed Central

    Qazi, Henry; Shi, Zhong-Dong; Tarbell, John M.

    2011-01-01

    Background Glioma cells are exposed to elevated interstitial fluid flow during the onset of angiogenesis, at the tumor periphery while invading normal parenchyma, within white matter tracts, and during vascular normalization therapy. Glioma cell lines that have been exposed to fluid flow forces in vivo have much lower invasive potentials than in vitro cell motility assays without flow would indicate. Methodology/Principal Findings A 3D Modified Boyden chamber (Darcy flow through collagen/cell suspension) model was designed to mimic the fluid dynamic microenvironment to study the effects of fluid shear stress on the migratory activity of glioma cells. Novel methods for gel compaction and isolation of chemotactic migration from flow stimulation were utilized for three glioma cell lines: U87, CNS-1, and U251. All physiologic levels of fluid shear stress suppressed the migratory activity of U87 and CNS-1 cell lines. U251 motility remained unaltered within the 3D interstitial flow model. Matrix Metalloproteinase (MMP) inhibition experiments and assays demonstrated that the glioma cells depended on MMP activity to invade, and suppression in motility correlated with downregulation of MMP-1 and MMP-2 levels. This was confirmed by RT-PCR and with the aid of MMP-1 and MMP-2 shRNA constructs. Conclusions/Significance Fluid shear stress in the tumor microenvironment may explain reduced glioma invasion through modulation of cell motility and MMP levels. The flow-induced migration trends were consistent with reported invasive potentials of implanted gliomas. The models developed for this study imply that flow-modulated motility involves mechanotransduction of fluid shear stress affecting MMP activation and expression. These models should be useful for the continued study of interstitial flow effects on processes that affect tumor progression. PMID:21637818

  20. Ionic solutes impact collagen scaffold bioactivity.

    PubMed

    Pawelec, K M; Husmann, A; Wardale, R J; Best, S M; Cameron, R E

    2015-02-01

    The structure of ice-templated collagen scaffolds is sensitive to many factors. By adding 0.5 wt% of sodium chloride or sucrose to collagen slurries, scaffold structure could be tuned through changes in ice growth kinetics and interactions of the solute and collagen. With ionic solutes (sodium chloride) the entanglements of the collagen molecule decreased, leading to fibrous scaffolds with increased pore size and decreased attachment of chondrocytes. With non-ionic solutes (sucrose) ice growth was slowed, leading to significantly reduced pore size and up-regulated cell attachment. This highlights the large changes in structure and biological function stimulated by solutes in ice-templating systems. PMID:25649518

  1. Applications of ionic liquids.

    PubMed

    Patel, Divia Dinesh; Lee, Jong-Min

    2012-06-01

    Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

  2. Ionic liquids as novel solvents for ionic polymer transducers

    NASA Astrophysics Data System (ADS)

    Bennett, Matthew D.; Leo, Donald J.

    2004-07-01

    The use of ionic liquids as solvents for ionic polymer (specifically, Nafion) transducers is demonstrated. Ionic liquids are attractive for this application because of their high inherent stability. Ionic liquids are salts that exist as liquids at room temperature and have no measureable vapor pressure. Therefore, the use of ionic liquids as solvents for ionic polymer transducers can eliminate the traditional problem of water evaporation in these devices. Another benefit of the use of ionic liquids in this way is the reduction or elimination of the characteristic back-relaxation common in water-solvated ionic polymer actuators. The results demonstrate that the viscosity of the ionic liquid and the degree to which the ionic liquid swells the membrane are the important physical parameters to consider. Five ionic liquids were studied, based on substituted pyrrolidinium, phosphonium, or imidazolium cations and fluoroanions. Of these five ionic liquids, transduction is demonstrated in three of them and the best results are obtained with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid. This substance has an electrochemical stability window of 4.1 V, a melting point of -10 °C, and a viscosity of 35-45 cP [19]. Results demonstrate that platinum-plated Nafion transducers solvated with this ionic liquid exhibit sensing and actuation responses and that these transducers are stable in air. Endurance testing of this sample reveals a decrease in the free strain of only 25 % after 250,000 actuation cycles in air.

  3. Exploiting hydrophobic borohydride-rich ionic liquids as faster-igniting rocket fuels.

    PubMed

    Liu, Tianlin; Qi, Xiujuan; Huang, Shi; Jiang, Linhai; Li, Jianling; Tang, Chenglong; Zhang, Qinghua

    2016-02-01

    A family of hydrophobic borohydride-rich ionic liquids was developed, which exhibited the shortest ignition delay times of 1.7 milliseconds and the lowest viscosity (10 mPa s) of hypergolic ionic fluids, demonstrating their great potential as faster-igniting rocket fuels to replace toxic hydrazine derivatives in liquid bipropellant formulations. PMID:26687630

  4. Receptor for advanced glycation end-products regulates lung fluid balance via protein kinase C-gp91(phox) signaling to epithelial sodium channels.

    PubMed

    Downs, Charles A; Kreiner, Lisa H; Johnson, Nicholle M; Brown, Lou Ann; Helms, My N

    2015-01-01

    The receptor for advanced glycation end-products (RAGE), a multiligand member of the Ig family, may play a crucial role in the regulation of lung fluid balance. We quantified soluble RAGE (sRAGE), a decoy isoform, and advanced glycation end-products (AGEs) from the bronchoalveolar lavage fluid of smokers and nonsmokers, and tested the hypothesis that AGEs regulate lung fluid balance through protein kinase C (PKC)-gp91(phox) signaling to the epithelial sodium channel (ENaC). Human bronchoalveolar lavage samples from smokers showed increased AGEs (9.02 ± 3.03 μg versus 2.48 ± 0.53 μg), lower sRAGE (1,205 ± 292 pg/ml versus 1,910 ± 263 pg/ml), and lower volume(s) of epithelial lining fluid (97 ± 14 ml versus 133 ± 17 ml). sRAGE levels did not predict ELF volumes in nonsmokers; however, in smokers, higher volumes of ELF were predicted with higher levels of sRAGE. Single-channel patch clamp analysis of rat alveolar epithelial type 1 cells showed that AGEs increased ENaC activity measured as the product of the number of channels (N) and the open probability (Po) (NPo) from 0.19 ± 0.08 to 0.83 ± 0.22 (P = 0.017) and the subsequent addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.15 ± 0.07 (P = 0.01). In type 2 cells, human AGEs increased ENaC NPo from 0.12 ± 0.05 to 0.53 ± 0.16 (P = 0.025) and the addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.10 ± 0.03 (P = 0.013). Using molecular and biochemical techniques, we observed that inhibition of RAGE and PKC activity attenuated AGE-induced activation of ENaC. AGEs induced phosphorylation of p47(phox) and increased gp91(phox)-dependent reactive oxygen species production, a response that was abrogated with RAGE or PKC inhibition. Finally, tracheal instillation of AGEs promoted clearance of lung fluid, whereas concomitant inhibition of RAGE, PKC, and gp91(phox) abrogated the response. PMID:24978055

  5. Host attachment and fluid shear are integrated into a mechanical signal regulating virulence in Escherichia coli O157:H7

    PubMed Central

    Alsharif, Ghadah; Ahmad, Sadia; Islam, Md Shahidul; Shah, Riddhi; Busby, Stephen J.; Krachler, Anne Marie

    2015-01-01

    Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen causing hemorrhagic colitis and hemolytic uremic syndrome. EHEC colonizes the intestinal tract through a range of virulence factors encoded by the locus of enterocyte effacement (LEE), as well as Shiga toxin. Although the factors involved in colonization and disease are well characterized, how EHEC regulates its expression in response to a host encounter is not well understood. Here, we report that EHEC perceives attachment to host cells as a mechanical cue that leads to expression of LEE-encoded virulence genes. This signal is transduced via the LEE-encoded global regulator of LEE-encoded regulator (Ler) and global regulator of Ler and is further enhanced by levels of shear force similar to peristaltic forces in the intestinal tract. Our data suggest that, in addition to a range of chemical environmental signals, EHEC is capable of sensing and responding to mechanical cues to adapt to its host’s physiology. PMID:25870295

  6. Ionic structure in liquids confined by dielectric interfaces

    NASA Astrophysics Data System (ADS)

    Jing, Yufei; Jadhao, Vikram; Zwanikken, Jos W.; Olvera de la Cruz, Monica

    2015-11-01

    The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as in the design of double-layer supercapacitors for energy storage and in the extraction of metal ions from wastewater. In this article, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics simulations and liquid state theory. We explore the effects of high electrolyte concentrations, multivalent ions, dielectric contrasts, and external electric field on the ionic distributions. We observe the presence of non-monotonic ionic density profiles leading to a layered structure in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of the dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of the effective interaction between the two interfaces.

  7. Ionic structure in liquids confined by dielectric interfaces.

    PubMed

    Jing, Yufei; Jadhao, Vikram; Zwanikken, Jos W; Olvera de la Cruz, Monica

    2015-11-21

    The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as in the design of double-layer supercapacitors for energy storage and in the extraction of metal ions from wastewater. In this article, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics simulations and liquid state theory. We explore the effects of high electrolyte concentrations, multivalent ions, dielectric contrasts, and external electric field on the ionic distributions. We observe the presence of non-monotonic ionic density profiles leading to a layered structure in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of the dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of the effective interaction between the two interfaces. PMID:26590543

  8. Electroplating Using Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Abbott, Andrew P.; Frisch, Gero; Ryder, Karl S.

    2013-07-01

    Electroplating is a key technology in many large-scale industrial applications such as corrosion-resistant and decorative coatings. Issues with current aqueous processes, such as toxicity of reagents and low current efficiencies, can often be overcome by using ionic liquids, and this approach has turned ionometallurgy into a fast-growing area of research. This review outlines the interactions in ionic liquids that are responsible for the advantageous properties of these solvents in electroplating. It summarizes recent research in which these properties have been analyzed or exploited and highlights fundamental issues in research and technology that need to be addressed.

  9. Abundance of Cysteine Endopeptidase Dionain in Digestive Fluid of Venus Flytrap (Dionaea muscipula Ellis) Is Regulated by Different Stimuli from Prey through Jasmonates

    PubMed Central

    Libiaková, Michaela; Floková, Kristýna; Novák, Ondřej; Slováková, L'udmila; Pavlovič, Andrej

    2014-01-01

    The trap of the carnivorous plant Venus flytrap (Dionaea muscipula) catches prey by very rapid closure of its modified leaves. After the rapid closure secures the prey, repeated mechanical stimulation of trigger hairs by struggling prey and the generation of action potentials (APs) result in secretion of digestive fluid. Once the prey's movement stops, the secretion is maintained by chemical stimuli released from digested prey. We investigated the effect of mechanical and chemical stimulation (NH4Cl, KH2PO4, further N(Cl) and P(K) stimulation) on enzyme activities in digestive fluid. Activities of β-D-glucosidases and N-acetyl-β-D-glucosaminidases were not detected. Acid phosphatase activity was higher in N(Cl) stimulated traps while proteolytic activity was higher in both chemically induced traps in comparison to mechanical stimulation. This is in accordance with higher abundance of recently described enzyme cysteine endopeptidase dionain in digestive fluid of chemically induced traps. Mechanical stimulation induced high levels of cis-12-oxophytodienoic acid (cis-OPDA) but jasmonic acid (JA) and its isoleucine conjugate (JA-Ile) accumulated to higher level after chemical stimulation. The concentration of indole-3-acetic acid (IAA), salicylic acid (SA) and abscisic acid (ABA) did not change significantly. The external application of JA bypassed the mechanical and chemical stimulation and induced a high abundance of dionain and proteolytic activity in digestive fluid. These results document the role of jasmonates in regulation of proteolytic activity in response to different stimuli from captured prey. The double trigger mechanism in protein digestion is proposed. PMID:25153528

  10. Mechanism and regulation of peroxidase-catalyzed nitric oxide consumption in physiological fluids: critical protective actions of ascorbate and thiocyanate.

    PubMed

    Rees, Martin D; Maiocchi, Sophie L; Kettle, Anthony J; Thomas, Shane R

    2014-07-01

    Catalytic consumption of nitric oxide (NO) by myeloperoxidase and related peroxidases is implicated as playing a key role in impairing NO bioavailability during inflammatory conditions. However, there are major gaps in our understanding of how peroxidases consume NO in physiological fluids, in which multiple reactive enzyme substrates and antioxidants are present. Notably, ascorbate has been proposed to enhance myeloperoxidase-catalyzed NO consumption by forming NO-consuming substrate radicals. However, we show that in complex biological fluids ascorbate instead plays a critical role in inhibiting NO consumption by myeloperoxidase and related peroxidases (lactoperoxidase, horseradish peroxidase) by acting as a competitive substrate for protein-bound redox intermediates and by efficiently scavenging peroxidase-derived radicals (e.g., urate radicals), yielding ascorbyl radicals that fail to consume NO. These data identify a novel mechanistic basis for how ascorbate preserves NO bioavailability during inflammation. We show that NO consumption by myeloperoxidase Compound I is significant in substrate-rich fluids and is resistant to competitive inhibition by ascorbate. However, thiocyanate effectively inhibits this process and yields hypothiocyanite at the expense of NO consumption. Hypothiocyanite can in turn form NO-consuming radicals, but thiols (albumin, glutathione) readily prevent this. Conversely, where ascorbate is absent, glutathione enhances NO consumption by urate radicals via pathways that yield S-nitrosoglutathione. Theoretical kinetic analyses provide detailed insights into the mechanisms by which ascorbate and thiocyanate exert their protective actions. We conclude that the local depletion of ascorbate and thiocyanate in inflammatory microenvironments (e.g., due to increased metabolism or dysregulated transport) will impair NO bioavailability by exacerbating peroxidase-catalyzed NO consumption. PMID:24704973

  11. Sweating. Fluid and ion losses and replacement.

    PubMed

    McCutcheon, L J; Geor, R J

    1998-04-01

    In the horse, sweat is produced by apocrine glands which are present over most haired and nonhaired skin. Although sweat secretion is initiated under a number of circumstances, the central drive for sweating in response to a thermal stimulus is the primary mechanism for its production. Sweating is an essential and primary mechanism for heat dissipation during exercise or exposure to hot ambient conditions. The rate of sweat production will reflect the interaction of numerous factors, including exercise intensity, ambient conditions, state of hydration, and the training or heat acclimation status of the individual horse. Thus, the sweating rates produced in response to an exercise-induced thermal load can be further increased by high ambient temperature or humidity which reduces evaporative efficiency, thereby contributing to the rate of rise in core body temperature. Equine sweat is an isotonic to slightly hypertonic secretion with sodium, chloride, and potassium contributing the major ionic components. The ionic composition of equine sweat is largely rate dependent and therefore is affected by factors such as ambient conditions and exercise intensity which result in elevations in sodium concentration in response to increases in sweating rate. Large sweat fluid losses associated with prolonged exercise will incur significant ion deficits, leading to alterations in skeletal muscle ion content and the potential for muscular dysfunction. With respect to exercise performance, however, the more important consequence of sweat fluid losses is the impairment of temperature regulation that accompanies severe dehydration. Although it is advantageous to restore a proportion of the fluid and ion losses incurred during prolonged exercise, few strategies will fully and safely replace the electrolyte losses incurred. Nevertheless, daily electrolyte supplementation of a good-quality diet will provide an effective method of replacing sweat ion losses during training and competition

  12. Fun with Ionic Compounds

    ERIC Educational Resources Information Center

    Logerwell, Mollianne G.; Sterling, Donna R.

    2007-01-01

    Ionic bonding is a fundamental topic in high school chemistry, yet it continues to be a concept that students struggle to understand. Even if they understand atomic structure and ion formation, it can be difficult for students to visualize how ions fit together to form compounds. This article describes several engaging activities that help…

  13. Carbenes from ionic liquids.

    PubMed

    Hollóczki, Oldamur; Nyulászi, László

    2014-01-01

    In the last decade an explosive development has been observed in the fields of both ionic liquids (ILs) as potential chemically inert solvents with many possible technical applications, and N-heterocyclic carbenes (NHCs) as catalysts with superb performance. Since the cations of many ILs can be deprotonated by strong bases yielding NHCs, this two fields are inherently connected. It has only recently been recognized that some of the commonly used basic anions of the ILs (such as acetate) are able to deprotonate azolium cations. While the resulting NHC could clearly be observed in the vapor phase, in the liquid - where the mutual electrostatic interactions within the ion network stabilize the ion pairs - the neutral NHC cannot be detected by commonly used analytical techniques; however, from these ionic liquids NHCs can be trapped, e.g., by complex formation, or more importantly these ILs can be directly used as catalysts, since the NHC content is sufficiently large for these applications. Apart from imidazole-2-ylidenes, the formation of other highly reactive neutral species ("abnormal carbenes," 2-alkylideneimidazoles, pyridine-ylidenes or pyridinium-ylides) is feasible in highly basic ionic liquids. The cross-fertilizing overlap between the two fields may provide access to a great advance in both areas, and we give an overview here on the results published so far, and also on the remaining possibilities and challenges in the concept of "carbenes from ionic liquids." PMID:23539381

  14. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng; Luo, Huimin

    2011-11-01

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  15. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

    2008-09-09

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  16. Mesoscale studies of ionic closed membranes with polyhedral geometries

    NASA Astrophysics Data System (ADS)

    Olvera de la Cruz, Monica

    2016-06-01

    Large crystalline molecular shells buckle spontaneously into icosahedra while multicomponent shells buckle into various polyhedra. Continuum elastic theory explains the buckling of closed shells with one elastic component into icosahedra. A generalized elastic model, on the other hand, describes the spontaneous buckling of inhomogeneous shells into regular and irregular polyhedra. By co-assembling water-insoluble anionic (-1) amphiphiles with cationic (3+) amphiphiles, we realized ionic vesicles. Results revealed that surface crystalline domains and the unusual shell shapes observed arise from the competition of ionic correlations with charge-regulation. We explain here the mechanism by which these ionic membranes generate a mechanically heterogeneous vesicle.

  17. Cofactor Regulation of C5a Chemotactic Activity in Physiological Fluids. Requirement for the Vitamin D Binding Protein, Thrombospondin-1 and its Receptors

    PubMed Central

    Trujillo, Glenda; Zhang, Jianhua; Habiel, David M.; Ge, Lingyin; Ramadass, Mahalakshmi; Ghebrehiwet, Berhane; Kew, Richard R.

    2011-01-01

    Factors in physiological fluids that regulate the chemotactic activity of complement activation peptides C5a and C5a des Arg are not well understood. The vitamin D binding protein (DBP) has been shown to significantly enhance chemotaxis to C5a/C5a des Arg. More recently, platelet-derived thrombospondin-1 (TSP-1) has been shown to facilitate the augmentation of C5a-induced chemotaxis by DBP. The objective of this study was to better characterize these chemotactic cofactors and investigate the role that cell surface TSP-1 receptors CD36 and CD47 may play in this process. The chemotactic activity in C-activated normal serum, citrated plasma, DBP-depleted serum or C5 depleted serum was determined for both normal human neutrophils and U937 cell line transfected with the C5a receptor (U937-C5aR). In addition, levels of C5a des Arg, DBP and TSP-1 in these fluids were measured by RIA or ELISA. Results show that there is a clear hierarchy with C5a being the essential primary signal (DBP or TSP-1 will not function in the absence of C5a), DBP the necessary cofactor and TSP-1 a dependent tertiary factor, since it cannot function to enhance chemotaxis to C5a without DBP. Measurement of the C5a-induced intracellular calcium flux confirmed the same hierarchy observed with chemotaxis. Moreover, analysis of bronchoalveolar lavage fluid (BALF) from patients with the adult respiratory distress syndrome (ARDS) demonstrated that C5a-dependent chemotactic activity is significantly decreased after anti-DBP treatment. Finally, results show that TSP-1 utilizes cell surface receptors CD36 and CD47 to augment chemotaxis, but DBP does not bind to TSP-1, CD36 or CD47. The results clearly demonstrate that C5a/C5a des Arg needs both DBP and TSP-1 for maximal chemotactic activity and suggest that the regulation of C5a chemotactic activity in physiological fluids is more complex than previously thought. PMID:22014686

  18. Biocatalytic transformations in ionic liquids.

    PubMed

    van Rantwijk, Fred; Madeira Lau, Rute; Sheldon, Roger A

    2003-03-01

    Room temperature ionic liquids are non-volatile, thermally stable and highly polar; they are also moderately hydrophilic solvents. Here, we discuss their use as reaction media for biocatalysis. Enzymes of widely diverging types are catalytically active in ionic liquids or aqueous biphasic ionic liquid systems. Lipases, in particular, maintain their activity in anhydrous ionic liquid media; the (enantio)selectivity and operational stability are often better than in traditional media. The unconventional solvent properties of ionic liquids have been exploited in biocatalyst recycling and product recovery schemes that are not feasible with traditional solvent systems. PMID:12628370

  19. Dissolving Polymers in Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Harner, John

    2009-03-01

    Dissolution and phase behavior of polymers in ionic liquids have been assessed by solution characterization techniques such as intrinsic viscosity and light scattering (static and dynamic). Elevated viscosity proved the greatest obstacle. As yet, whether principles standard to conventional polymer solutions apply to ionic liquid solutions is uncertain, especially for polymers such as polyelectrolytes and hydrophilic block copolymers that may specifically interact with ionic liquid anions or cations. For flexible polyelectrolytes (polymers releasing counterions into high dielectric solvents), characterization in ionic liquids suggests behaviors more typical of neutral polymer. Coil sizes and conformations are approximately the same as in aqueous buffer. Further, several globular proteins dissolve in a hydrophilic ionic liquid with conformations analogous to those in buffer. General principles of solubility, however, remain unclear, making predictions of which polymer dissolves in which ionic liquid difficult; several otherwise intractable polymers (e.g., cellulose, polyvinyl alcohol) dissolve and can be efficiently functionalized in ionic liquids.

  20. Parameters of hormonal regulation of fluid-electrolyte exchange and camp reception in the rat renal papilla during adaptation to cold

    SciTech Connect

    Selyatitskaya, V.G.; Ivanova, L.N.; Shorin, Y.P.; Solenov, E.I.

    1986-03-01

    The authors study the intracellular reaction of cAMP, which is an important functional component of the action of antidiuretic hormone (ADH) in target tissues, in the renal papilla. The aldosterone concentration of the rats' urine was determined by radioimmunoassay. The experiments showed that specific binding of /sup 3/H-cAMP in the cytosol of the renal papilla in animals adapted to cold was 3.2 +/- 0.6 femtomoles/kg protein. A decrease in the concentration of hormones participating in the regulation of fluid-electrolyte exchange was discovered in these experiments. A significant fall in the ADH concentration was observed in the blood plasma of the experimental animals.

  1. A comparison of hydration effect on body fluid and temperature regulation between Malaysian and Japanese males exercising at mild dehydration in humid heat

    PubMed Central

    2014-01-01

    Background This study investigated the effect of hydration differences on body fluid and temperature regulation between tropical and temperate indigenes exercising in the heat. Methods Ten Japanese and ten Malaysian males with matched physical characteristics (height, body weight, and peak oxygen consumption) participated in this study. Participants performed exercise for 60 min at 55% peak oxygen uptake followed by a 30-min recovery at 32°C and 70% relative air humidity with hydration (4 times each, 3 mL per kg body weight, 37°C) or without hydration. Rectal temperature, skin temperature, heart rate, skin blood flow, and blood pressure were measured continuously. The percentage of body weight loss and total sweat loss were calculated from body weight measurements. The percentage change in plasma volume was estimated from hemoglobin concentration and hematocrit. Results Malaysian participants had a significantly lower rectal temperature, a smaller reduction in plasma volume, and a lower heart rate in the hydrated condition than in the non-hydrated condition at the end of exercise (P <0.05), whereas Japanese participants showed no difference between the two hydration conditions. Hydration induced a greater total sweat loss in both groups (P <0.05), and the percentage of body weight loss in hydrated Malaysians was significantly less than in hydrated Japanese (P <0.05). A significant interaction between groups and hydration conditions was observed for the percentage of mean cutaneous vascular conductance during exercise relative to baseline (P <0.05). Conclusions The smaller reduction in plasma volume and percentage body weight loss in hydrated Malaysians indicated an advantage in body fluid regulation. This may enable Malaysians to reserve more blood for circulation and heat dissipation and thereby maintain lower rectal temperatures in a hydrated condition. PMID:24490869

  2. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  3. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  4. On a basic model of circulatory, fluid, and electrolyte regulation in the human system based upon the model of Guyton

    NASA Technical Reports Server (NTRS)

    White, R. J.

    1973-01-01

    A detailed description of Guyton's model and modifications are provided. Also included are descriptions of several typical experiments which the model can simulate to illustrate the model's general utility. A discussion of the problems associated with the interfacing of the model to other models such as respiratory and thermal regulation models which is prime importance since these stimuli are not present in the current model is also included. A user's guide for the operation of the model on the Xerox Sigma 3 computer is provided and two programs are described. A verification plan and procedure for performing experiments is also presented.

  5. 3-Methylpiperidinium ionic liquids.

    PubMed

    Belhocine, Tayeb; Forsyth, Stewart A; Gunaratne, H Q Nimal; Nieuwenhuyzen, Mark; Nockemann, Peter; Puga, Alberto V; Seddon, Kenneth R; Srinivasan, Geetha; Whiston, Keith

    2015-04-28

    A wide range of room temperature ionic liquids based on the 3-methylpiperdinium cation core were produced from 3-methylpiperidine, which is a derivative of DYTEK® A amine. First, reaction with 1-bromoalkanes or 1-bromoalkoxyalkanes generated the corresponding tertiary amines (Rmβpip, R = alkyl or alkoxyalkyl); further quaternisation reactions with the appropriate methylating agents yielded the quaternary [Rmmβpip]X salts (X(-) = I(-), [CF3CO2](-) or [OTf](-); Tf = -SO2CF3), and [Rmmβpip][NTf2] were prepared by anion metathesis from the corresponding iodides. All [NTf2](-) salts are liquids at room temperature. [Rmmβpip]X (X(-) = I(-), [CF3CO2](-) or [OTf](-)) are low-melting solids when R = alkyl, but room temperature liquids upon introduction of ether functionalities on R. Neither of the 3-methylpiperdinium ionic liquids showed any signs of crystallisation, even well below 0 °C. Some related non-C-substituted piperidinium and pyrrolidinium analogues were prepared and studied for comparison. Crystal structures of 1-hexyl-1,3-dimethylpiperidinium tetraphenylborate, 1-butyl-3-methylpiperidinium bromide, 1-(2-methoxyethyl)-1-methylpiperidinium chloride and 1-(2-methoxyethyl)-1-methylpyrrolidinium bromide are reported. Extensive structural and physical data are collected and compared to literature data, with special emphasis on the systematic study of the cation ring size and/or asymmetry effects on density, viscosity and ionic conductivity, allowing general trends to be outlined. Cyclic voltammetry shows that 3-methylpiperidinium ionic liquids, similarly to azepanium, piperidinium or pyrrolidinium counterparts, are extremely electrochemically stable; the portfolio of useful alternatives for safe and high-performing electrolytes is thus greatly extended. PMID:25669485

  6. Thermodynamic estimation: Ionic materials

    SciTech Connect

    Glasser, Leslie

    2013-10-15

    Thermodynamics establishes equilibrium relations among thermodynamic parameters (“properties”) and delineates the effects of variation of the thermodynamic functions (typically temperature and pressure) on those parameters. However, classical thermodynamics does not provide values for the necessary thermodynamic properties, which must be established by extra-thermodynamic means such as experiment, theoretical calculation, or empirical estimation. While many values may be found in the numerous collected tables in the literature, these are necessarily incomplete because either the experimental measurements have not been made or the materials may be hypothetical. The current paper presents a number of simple and relible estimation methods for thermodynamic properties, principally for ionic materials. The results may also be used as a check for obvious errors in published values. The estimation methods described are typically based on addition of properties of individual ions, or sums of properties of neutral ion groups (such as “double” salts, in the Simple Salt Approximation), or based upon correlations such as with formula unit volumes (Volume-Based Thermodynamics). - Graphical abstract: Thermodynamic properties of ionic materials may be readily estimated by summation of the properties of individual ions, by summation of the properties of ‘double salts’, and by correlation with formula volume. Such estimates may fill gaps in the literature, and may also be used as checks of published values. This simplicity arises from exploitation of the fact that repulsive energy terms are of short range and very similar across materials, while coulombic interactions provide a very large component of the attractive energy in ionic systems. Display Omitted - Highlights: • Estimation methods for thermodynamic properties of ionic materials are introduced. • Methods are based on summation of single ions, multiple salts, and correlations. • Heat capacity, entropy

  7. Cyclic phosphonium ionic liquids

    PubMed Central

    Mukhlall, Joshua A; Romeo, Alicia R; Gohdo, Masao; Ramati, Sharon; Berman, Marc; Suarez, Sophia N

    2014-01-01

    Summary Ionic liquids (ILs) incorporating cyclic phosphonium cations are a novel category of materials. We report here on the synthesis and characterization of four new cyclic phosphonium bis(trifluoromethylsulfonyl)amide ILs with aliphatic and aromatic pendant groups. In addition to the syntheses of these novel materials, we report on a comparison of their properties with their ammonium congeners. These exemplars are slightly less conductive and have slightly smaller self-diffusion coefficients than their cyclic ammonium congeners. PMID:24605146

  8. Cerebrospinal fluid metabolomics implicate bioenergetic adaptation as a neural mechanism regulating shifts in cognitive states of HIV-infected patients

    PubMed Central

    Dickens, Alex M.; Anthony, Daniel C.; Deutsch, Reena; Mielke, Michelle M.; Claridge, Timothy D.W.; Grant, Igor; Franklin, Donald; Rosario, Debra; Marcotte, Thomas; Letendre, Scott; McArthur, Justin C.; Haughey, Norman J.

    2015-01-01

    Objectives To identify prognostic surrogate markers for change in cognitive states of HIV-infected patients. Design Longitudinal cerebrospinal fluid (CSF) samples were collected from 98 HIV+ patients identified by temporal change in cognitive states classified as normal, stably impaired, improving and worsening. Methods The metabolic composition of CSF was analysed using 1HNMR spectroscopy that focused on energy metabolites. Metabolic biomarkers for cognitive states were identified using multivariate partial least squares regression modelling of the acquired spectra, combined with nonparametric analyses of metabolites with clinical features. Results Multivariate modelling and cross-validated recursive partitioning identified several energy metabolites that, when combined with clinical variables, classified patients based on change in neurocognitive states. Prognostic identification for worsening was achieved with four features that included no change in a detectable plasma viral load, elevated citrate and acetate; decreased creatine, to produce a model with a predictive accuracy of 92%, sensitivity of 88% and 96% specificity. Prognosis for improvement contained seven features that included first visit age less than 47 years, new or continued use of antiretrovirals, elevated glutamine and glucose; decreased myo-inositol, β-glucose and creatinine to generate a model with a predictive accuracy of 92%, sensitivity of 100% and specificity of 84%. Conclusion These CSF metabolic results suggest that worsening cognitive status in HIV-infected patients is associated with increased aerobic glycolysis, and improvements in cognitive status are associated with a shift to anaerobic glycolysis. Dietary, lifestyle and pharmacologic interventions that promote anaerobic glycolysis could protect the brain in setting of HIV infection with combined antiretroviral therapy. PMID:25611149

  9. Wnt signaling behaves as a "master regulator" in the osteogenic and adipogenic commitment of human amniotic fluid mesenchymal stem cells.

    PubMed

    D'Alimonte, Iolanda; Lannutti, Angela; Pipino, Caterina; Di Tomo, Pamela; Pierdomenico, Laura; Cianci, Eleonora; Antonucci, Ivana; Marchisio, Marco; Romano, Mario; Stuppia, Liborio; Caciagli, Francesco; Pandolfi, Assunta; Ciccarelli, Renata

    2013-10-01

    Human amniotic fluid mesenchymal stem cells (huAFMSCs) are emerging as a promising therapeutic option in regenerative medicine. Here, we characterized huAFMSC phenotype and multipotentiality. When cultured in osteogenic medium, huAFMSC displayed a significant increase in: Alkaline Phosphatase (ALP) activity and mRNA expression, Alizarin Red S staining and Runx2 mRNA expression; whereas maintaining these cells in an adipogenic culture medium gave a time-dependent increase in PPARγ and FABP4 mRNA expression, glycerol-3-phosphate dehydrogenase (GPDH) activity and positivity to Oil Red Oil staining. These results confirm that huAFMSCs can differentiate toward osteogenic and adipogenic phenotypes. The canonical Wnt/ßcatenin signaling pathway appears to trigger huAFMSC osteoblastogenesis, since during early phases of osteogenic differentiation, the expression of Dishevelled-2 (Dvl-2), of the non-phosphorylated form of ß-catenin, and the phosphorylation of glycogen synthase kinase-3ß (GSK3ß) at serine 9 were upregulated. On the contrary, during adipogenic differentiation Dvl-2 expression decreased, whereas that of ß-catenin remained unchanged. This was associated with a late increase in GSK3ß phosphorylation. Consistent with this scenario, huAFMSCs exposure to Dickkopf-1, a selective inhibitor of the Wnt signaling, abolished Runx2 and ALP mRNA upregulation during huAFMSC osteogenic differentiation, whereas it enhanced FABP4 expression in adipocyte-differentiating cells. Taken together, these results unravel novel molecular determinants of huAFMSC commitment towards osteoblastogenesis, which may represent potential targets for directing the differentiation of these cells and improving their use in regenerative medicine. PMID:23605563

  10. Mixing Enthalpy for Binary Mixtures Containing Ionic Liquids.

    PubMed

    Podgoršek, A; Jacquemin, J; Pádua, A A H; Costa Gomes, M F

    2016-05-25

    A complete review of the published data on the mixing enthalpies of mixtures containing ionic liquids, measured directly using calorimetric techniques, is presented in this paper. The field of ionic liquids is very active and a number of research groups in the world are dealing with different applications of these fluids in the fields of chemistry, chemical engineering, energy, gas storage and separation or materials science. In all these fields, the knowledge of the energetics of mixing is capital both to understand the interactions between these fluids and the different substrates and also to establish the energy and environmental cost of possible applications. Due to the relative novelty of the field, the published data is sometimes controversial and recent reviews are fragmentary and do not represent a set of reliable data. This fact can be attributed to different reasons: (i) difficulties in controlling the purity and stability of the ionic liquid samples; (ii) availability of accurate experimental techniques, appropriate for the measurement of viscous, charged, complex fluids; and (iii) choice of an appropriate clear thermodynamic formalism to be used by an interdisciplinary scientific community. In this paper, we address all these points and propose a critical review of the published data, advise on the most appropriate apparatus and experimental procedure to measure this type of physical-chemical data in ionic liquids as well as the way to treat the information obtained by an appropriate thermodynamic formalism. PMID:27144455

  11. Fluid shear stress as a regulator of gene expression in vascular cells: possible correlations with diabetic abnormalities

    NASA Technical Reports Server (NTRS)

    Papadaki, M.; Eskin, S. G.; Ruef, J.; Runge, M. S.; McIntire, L. V.

    1999-01-01

    Diabetes mellitus is associated with increased frequency, severity and more rapid progression of cardiovascular diseases. Metabolic perturbations from hyperglycemia result in disturbed endothelium-dependent relaxation, activation of coagulation pathways, depressed fibrinolysis, and other abnormalities in vascular homeostasis. Atherosclerosis is localized mainly at areas of geometric irregularity at which blood vessels branch, curve and change diameter, and where blood is subjected to sudden changes in velocity and/or direction of flow. Shear stress resulting from blood flow is a well known modulator of vascular cell function. This paper presents what is currently known regarding the molecular mechanisms responsible for signal transduction and gene regulation in vascular cells exposed to shear stress. Considering the importance of the hemodynamic environment of vascular cells might be vital to increasing our understanding of diabetes.

  12. Do the skull and dura exert influence on brain volume regulation following hypo- and hyperosmolar fluid treatment?

    PubMed

    Dóczi, T; Kuncz, A; Bodosi, M

    1990-01-01

    The present studies were performed to determine the response of the brain water and electrolytes to acute hypoosmolality and hyperosmolality in animals with intact skull and dura, in comparison with those subjected to extensive bilateral or unilateral craniectomy and dural opening. Four to 5 weeks following extensive unilateral or bilateral craniectomy and dural opening in rats, a 50 mosm/kg decrease in plasma osmolality was produced by systemic administration of distilled water ("water intoxication"), or a 28 mosm/kg increase in plasma osmolality was produced by systemic administration of either 1 M NaCl or 1 M mannitol in 0.34 M NaCl. Tissue water, Na, and K contents were determined after 120 minutes. Tissue water accumulation or water loss was proportional to the decrease or increase in plasma osmolality. However, the tissue water accumulation following "water intoxication" was less (40% of the predicted value) than that predicted for ideal osmotic behaviour. The brain tissue was also found to shrink less than predicted on the basis of ideal osmotic behaviour (40% of the predicted value after mannitol treatment, and 60% after NaCl administration). This non-ideal osmotic response of the brain tissue is consistent with the finding in other studies and indicated a significant degree of volume regulation. Water and electrolyte changes were not different in operated and non-operated animals, demonstrating no effects of extensive skull and dura defects on tissue volume regulation under hypo- and hyperosmolar conditions of a degree that may be encountered under clinical circumstances.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2089892

  13. Ionic liquids, electrolyte solutions including the ionic liquids, and energy storage devices including the ionic liquids

    SciTech Connect

    Gering, Kevin L.; Harrup, Mason K.; Rollins, Harry W.

    2015-12-08

    An ionic liquid including a phosphazene compound that has a plurality of phosphorus-nitrogen units and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. One pendant group of the at least one pendant group comprises a positively charged pendant group. Additional embodiments of ionic liquids are disclosed, as are electrolyte solutions and energy storage devices including the embodiments of the ionic liquid.

  14. Molecular solutes in ionic liquids: a structural perspective.

    PubMed

    Pádua, Agílio A H; Costa Gomes, Margarida F; Canongia Lopes, José N A

    2007-11-01

    Understanding physicochemical properties of ionic liquids is important for their rational use in extractions, reactions, and other applications. Ionic liquids are not simple fluids: their ions are generally asymetric, flexible, with delocalized electrostatic charges, and available in a wide variety. It is difficult to capture their subtle properties with models that are too simplistic. Molecular simulation using atomistic force fields, which describe structures and interactions in detail, is an excellent tool to gain insights into their liquid-state organization, how they solvate different compounds, and what molecular factors determine their properties. The identification of certain ionic liquids as self-organized phases, with aggregated nonpolar and charged domains, provides a new way to interpret the solvation and structure of their mixtures. Many advances are the result of a successful interplay between experiment and modeling, possible in this field where none of the two methodologies had a previous advance. PMID:17661440

  15. Ionic imbalance induced self-propulsion of liquid metals

    PubMed Central

    Zavabeti, Ali; Daeneke, Torben; Chrimes, Adam F.; O'Mullane, Anthony P.; Zhen Ou, Jian; Mitchell, Arnan; Khoshmanesh, Khashayar; Kalantar-zadeh, Kourosh

    2016-01-01

    Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems. PMID:27488954

  16. Ionic imbalance induced self-propulsion of liquid metals

    NASA Astrophysics Data System (ADS)

    Zavabeti, Ali; Daeneke, Torben; Chrimes, Adam F.; O'Mullane, Anthony P.; Zhen Ou, Jian; Mitchell, Arnan; Khoshmanesh, Khashayar; Kalantar-Zadeh, Kourosh

    2016-08-01

    Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems.

  17. Ionic imbalance induced self-propulsion of liquid metals.

    PubMed

    Zavabeti, Ali; Daeneke, Torben; Chrimes, Adam F; O'Mullane, Anthony P; Zhen Ou, Jian; Mitchell, Arnan; Khoshmanesh, Khashayar; Kalantar-Zadeh, Kourosh

    2016-01-01

    Components with self-propelling abilities are important building blocks of small autonomous systems and the characteristics of liquid metals are capable of fulfilling self-propulsion criteria. To date, there has been no exploration regarding the effect of electrolyte ionic content surrounding a liquid metal for symmetry breaking that generates motion. Here we show the controlled actuation of liquid metal droplets using only the ionic properties of the aqueous electrolyte. We demonstrate that pH or ionic concentration gradients across a liquid metal droplet induce both deformation and surface Marangoni flow. We show that the Lippmann dominated deformation results in maximum velocity for the self-propulsion of liquid metal droplets and illustrate several key applications, which take advantage of such electrolyte-induced motion. With this finding, it is possible to conceive the propulsion of small entities that are constructed and controlled entirely with fluids, progressing towards more advanced soft systems. PMID:27488954

  18. Amniotic fluid

    MedlinePlus

    Amniotic fluid is a clear, slightly yellowish liquid that surrounds the unborn baby (fetus) during pregnancy. It is ... in the womb, the baby floats in the amniotic fluid. The amount of amniotic fluid is greatest at ...

  19. Fluid handling equipment: A compilation

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Devices and techniques used in fluid-handling and vacuum systems are described. Section 1 presents several articles on fluid lines and tubing. Section 2 describes a number of components such as valves, filters, and regulators. The last section contains descriptions of a number of innovative fluid-handling systems.

  20. Ionic surface electrical conductivity in sandstone

    NASA Astrophysics Data System (ADS)

    Glover, Paul W. J.; Meredith, Philip G.; Sammonds, Peter R.; Murrell, Stanley A. F.

    1994-11-01

    Recent analyses of complex conductivity measurements have indicated that high-frequency dispersions encountered in rocks saturated with low-salinity fluids are due to ionic surface conduction and that the form of these dispersions may be dependent upon the nature of the pore and crack surfaces within the rock (Ruffet et al., 1991). Unfortunately, the mechanisms of surface conduction are not well understood, and no model based on rigorous physical principles exists. This paper is split into two parts: an experimental section followed by the development of a theoretical description of adsorption of ions onto mineral surfaces. We have made complex conductivity measurements upon samples of sandstone saturated with a range of different types and concentrations of aqueous solution with a frequency range of 20 Hz to 1 MHz. The frequency dependence of complex conductivity was analyzed using the empirical model of Cole and Cole (1941). The 'fractal' surface models of Le Mehaute and Crepy (1983), Po Zen Wong (1987), the Ruffet el at. (1991) were used to calculate apparent fractal pore surface dimensions for samples saturated with different solution types and concentrations. These showed a pronounced decrease of apparent fractal surface dimension with decreasing electrolyte concentration and a decrease of apparent fractal dimension with increasing relative ionic radius of the dominant cation in solution. A model for ionic surface concentration (ISCOM I) has been developed as the first step in producing a rigorous physicochemical model of surface conduction in quartz-dominated rocks. The results from ISCOM I show that quartz surfaces are overwhelmingly dominated by adsorbed Na(+) when saturated with NaCl solutions of salinities and pH found in actual geological situations. ISCOM I also shows that the concentration threshold for dominance of surface conduction over bulk conduction is aided by depletion of ions from the bulk fluid as a result of their adsorption onto the mineral

  1. Dynamics of GHRH in third-ventricle cerebrospinal fluid of cattle: relationship with serum concentrations of GH and responses to appetite-regulating peptides

    PubMed Central

    Thomas, M.G.; Amstalden, M.; Hallford, D.M.; Silver, G.A.; Garcia, M.D.; Keisler, D.H.; Williams, G.L.

    2009-01-01

    Objectives were to 1) characterize the relationship of third-ventricle (IIIV) cerebrospinal fluid (CSF) concentrations of growth hormone releasing hormone (GHRH) with concentrations of GH in the peripheral circulation, and 2) assess the influence of acute administration of appetite-regulating peptides, leptin (anti-orexigenic) and neuropeptide Y (NPY; orexigenic) on release of GHRH. Six mature beef cows fitted with IIIV and jugular vein cannulae were treated intracerebroventricularly with saline, and leptin (600 μg) and NPY (500 μg) in saline, in a replicated 3 x 3 Latin square design. Third-ventricle CSF and blood were collected 10 min before and continued 220 min after treatments. Mean concentrations of GHRH and frequency of pulses after treatments were 2.2 ± 0.13 ng/mL and 1.2 ± 0.15 pulses/220 min, respectively. These measures were not influenced by treatments. Concentrations of GHRH in CSF were weakly correlated (r = 0.15; P < 0.03) with serum concentrations of GH; however, 58% of the GH pulses were preceded by a pulse of GHRH and 90% of the GHRH pulses occurred within 20 min preceding a pulse of GH. Leptin tended (P < 0.10) to suppress GH area under the curve (AUC) compared to saline. Concomitantly, NPY tended (P < 0.10) to increase GH AUC, which appeared to be a consequence of increased (P < 0.05) pulse amplitude. Infusion of NPY also increased (P < 0.05) AUC of GHRH relative to saline. No differences were detected among treatments in serum concentrations of IGF-I or its AUC. Sampling CSF from the IIIV appears to be a viable procedure for assessing hypothalamic release of GHRH coincident with anterior pituitary gland secretion of GH in cattle. These data also demonstrate the differential responsiveness of the GH axis to appetite-regulating peptides. PMID:19632078

  2. Enzyme catalysis in ionic liquids.

    PubMed

    Kragl, Udo; Eckstein, Marrit; Kaftzik, Nicole

    2002-12-01

    Ionic liquids offer new possibilities for the application of solvent engineering to biocatalytic reactions. Although in many cases ionic liquids have simply been used to replace organic solvents, they have often led to improved process performance. Unlike conventional organic solvents, ionic liquids possess no vapor pressure, are able to dissolve many compounds, and can be used to form two-phase systems with many solvents. To date, reactions involving lipases have benefited most from the use of ionic liquids, but the use of ionic liquids with other enzymes and in whole-cell processes has also been described. In some cases, remarkable results with respect to yield, (enantio)selectivity or enzyme stability were observed. PMID:12482515

  3. mTORC1 Is Essential for Early Steps during Schwann Cell Differentiation of Amniotic Fluid Stem Cells and Regulates Lipogenic Gene Expression

    PubMed Central

    Schörghofer, David; Kinslechner, Katharina; Schütz, Birgit; Thi Thanh Pham, Ha; Rosner, Margit; Joo, Gabor Jozsef; Röhrl, Clemens; Weichhart, Thomas; Stangl, Herbert; Lubec, Gert; Hengstschläger, Markus; Mikula, Mario

    2014-01-01

    Schwann cell development is hallmarked by the induction of a lipogenic profile. Here we used amniotic fluid stem (AFS) cells and focused on the mechanisms occurring during early steps of differentiation along the Schwann cell lineage. Therefore, we initiated Schwann cell differentiation in AFS cells and monitored as well as modulated the activity of the mechanistic target of rapamycin (mTOR) pathway, the major regulator of anabolic processes. Our results show that mTOR complex 1 (mTORC1) activity is essential for glial marker expression and expression of Sterol Regulatory Element-Binding Protein (SREBP) target genes. Moreover, SREBP target gene activation by statin treatment promoted lipogenic gene expression, induced mTORC1 activation and stimulated Schwann cell differentiation. To investigate mTORC1 downstream signaling we expressed a mutant S6K1, which subsequently induced the expression of the Schwann cell marker S100b, but did not affect lipogenic gene expression. This suggests that S6K1 dependent and independent pathways downstream of mTORC1 drive AFS cells to early Schwann cell differentiation and lipogenic gene expression. In conclusion our results propose that future strategies for peripheral nervous system regeneration will depend on ways to efficiently induce the mTORC1 pathway. PMID:25221943

  4. Novel applications of ionic liquids in materials processing

    NASA Astrophysics Data System (ADS)

    Reddy, Ramana G.

    2009-05-01

    Ionic liquids are mixtures of organic and inorganic salts which are liquids at room temperature. Several potential applications of ionic liquids in the field of materials processing are electrowinning and electrodeposition of metals and alloys, electrolysis of active metals at low temperature, liquid-liquid extraction of metals. Results using 1-butyl-3-methylimidazolium chloride with AlCl3 at low temperatures yielded high purity aluminium deposits (>99.9% pure) and current efficiencies >98%. Titanium and aluminium were co-deposited with/without the addition of TiCl4 with up to 27 wt% Ti in the deposit with current efficiencies in the range of 78-85 %. Certain ionic liquids are potential replacements for thermal oils and molten salts as heat transfer fluids in solar energy applications due to high thermal stability, very low corrosivity and substantial sensible heat retentivity. The calculated storage densities for several chloride and fluoride ionic liquids are in the range of 160-210 MJ/m3. A 3-D mathematical model was developed to simulate the large scale electrowinning of aluminium. Since ionic liquids processing results in their low energy consumption, low pollutant emissions many more materials processing applications are expected in future.

  5. Ionic Vapor Composition in Pyridinium-Based Ionic Liquids.

    PubMed

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-05-26

    Strong electrostatic interactions in ionic compounds make vaporization a complex process. The gas phase can contain a broad range of ionic clusters, and the cluster composition can differ greatly from that in the liquid phase. Room-temperature ionic liquids (RTILs) constitute a complicated case due to their ionic nature, asymmetric structure, and a huge versatility of ions and ionic clusters. This work reports vapor-liquid equilibria and vapor compositions of butylpyridinium (BPY) RTILs formed with hexafluorophosphate (PF6), trifluoromethanesulfonate (TF), and bis(trifluoromethanesulfonyl)imide (TFSI) anions. Unlike inorganic crystals, the pyridinium-based RTILs contain significant percentages of charged clusters in the vapor phase. Ion triplets and ion quadruplets each constitute up to 10% of the vapor phase composition. Triples prevail over quadruples in [BPY][PF6] due to the size difference of the cation and the anion. The percentage of charged ionic clusters in the gas phase is in inverse proportion to the mass of the anion. The largest identified vaporized ionic cluster comprises eight ions, with a formation probability below 1%. Higher temperature fosters formation of larger clusters due to an increase of the saturated vapor density. PMID:27165866

  6. Electrodeposition in Ionic Liquids.

    PubMed

    Zhang, Qinqin; Wang, Qian; Zhang, Suojiang; Lu, Xingmei; Zhang, Xiangping

    2016-02-01

    Due to their attractive physico-chemical properties, ionic liquids (ILs) are increasingly used as deposition electrolytes. This review summarizes recent advances in electrodeposition in ILs and focuses on its similarities and differences with that in aqueous solutions. The electrodeposition in ILs is divided into direct and template-assisted deposition. We detail the direct deposition of metals, alloys and semiconductors in five types of ILs, including halometallate ILs, air- and water-stable ILs, deep eutectic solvents (DESs), ILs with metal-containing cations, and protic ILs. Template-assisted deposition of nanostructures and macroporous structures in ILs is also presented. The effects of modulating factors such as deposition conditions (current density, current density mode, deposition time, temperature) and electrolyte components (cation, anion, metal salts, additives, water content) on the morphology, compositions, microstructures and properties of the prepared materials are highlighted. PMID:26530378

  7. A New Class of Ionic Liquids: Anion Amphiprotic Ionic Liquids.

    PubMed

    Treskow, Marcel; Pitawala, Jagath; Arenz, Sven; Matic, Aleksandar; Johansson, Patrik

    2012-08-16

    We here present a new class of protic ionic liquids, anion amphiprotic ionic liquids (AAILs). These materials are protonation equilibrium free protic ionic liquids and interesting in their own right by not following the classical Brønsted acid-base neutralization concept. Due to the very simple synthesis route applied and their stable basic chemistry, we believe in a potential use for manifold applications. This is supported by the combination of practical material properties, foremost, a general intrinsic stability versus reversal of the formation reaction toward neutral species, broad liquidus ranges, long-term thermal stabilities, high conductivities, protic characteristics, and a general stability versus water. PMID:26295756

  8. Numerical simulation of strongly coupled binary ionic plasmas

    SciTech Connect

    DeWitt, H.; Slattery, W.; Chabrier, G.

    1995-11-01

    New lengthy Monte Carlo simulations of the energy equation of state of binary ionic mixture fluids in a uniform background show that deviations from the linear mixing rule are small, positive, and nearly constant as a function of {Gamma}. Deviations from linear mixing for the Helmholtz free energy are positive and behave as ln{Gamma}. Quantitative results are obtained form the correction to the thermonuclear reaction rate.

  9. Understanding the influence of Coulomb and dispersion interactions on the wetting behavior of ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-11-01

    We study the role of dispersion and electrostatic interactions in the wetting behavior of ionic liquids on non-ionic solid substrates. We consider a simple model of an ionic liquid consisting of spherical ions that interact via Lennard-Jones and Coulomb potentials. Bulk and interfacial properties are computed for five fluids distinguished by the strength of the electrostatic interaction relative to the dispersion interaction. We employ Monte Carlo simulations and an interface-potential-based approach to calculate the liquid-vapor and substrate-fluid interfacial properties. Surface tensions for each fluid are evaluated over a range of temperatures that spans from a reduced temperature of approximately 0.6 to the critical point. Contact angles are calculated at select temperatures over a range of substrate-fluid interaction strengths that spans from the near-drying regime to the wetting regime. We observe that an increase in the relative strength of Coulombic interactions between ions leads to increasing deviation from Guggenheim's corresponding states theory. We show how this deviation is related to lower values of liquid-vapor excess entropies observed for strongly ionic fluids. Our results show that the qualitative nature of wetting behavior is significantly influenced by the competition between dispersion and electrostatic interactions. We discuss the influence of electrostatic interactions on the nature of wetting and drying transitions and corresponding states like behavior observed for contact angles. For all of the fluids studied, we observe a relatively narrow range of substrate-fluid interaction strengths wherein the contact angle is nearly independent of temperature. The influence of the ionic nature of the fluid on the temperature dependence of contact angle is also discussed. PMID:25381536

  10. Novel approaches to ionic chromatography

    SciTech Connect

    Dasgupta, P.K.

    1990-11-01

    Research during this reporting period, continued on ionic chromatography. Major progress has been made towards on-line on-demand generation of ultrapure chemicals by electrochemical means. The concentration of the generated material is governed electrochemically.

  11. Special Report: Solid Ionic Conductors.

    ERIC Educational Resources Information Center

    Shriver, Duward F.; Farrington, Gregory C.

    1985-01-01

    Solid ionic conductors are unusual materials that may find valuable applications in devices ranging from high-energy density batteries to lasers. The nature of these materials and their potential uses are discussed. (JN)

  12. Nonlinear ionic pulses along microtubules.

    PubMed

    Sekulić, D L; Satarić, B M; Tuszynski, J A; Satarić, M V

    2011-05-01

    Microtubules are cylindrically shaped cytoskeletal biopolymers that are essential for cell motility, cell division and intracellular trafficking. Here, we investigate their polyelectrolyte character that plays a very important role in ionic transport throughout the intra-cellular environment. The model we propose demonstrates an essentially nonlinear behavior of ionic currents which are guided by microtubules. These features are primarily due to the dynamics of tubulin C-terminal tails which are extended out of the surface of the microtubule cylinder. We also demonstrate that the origin of nonlinearity stems from the nonlinear capacitance of each tubulin dimer. This brings about conditions required for the creation and propagation of solitonic ionic waves along the microtubule axis. We conclude that a microtubule plays the role of a biological nonlinear transmission line for ionic currents. These currents might be of particular significance in cell division and possibly also in cognitive processes taking place in nerve cells. PMID:21604102

  13. Ionic Liquid Crystals: Versatile Materials.

    PubMed

    Goossens, Karel; Lava, Kathleen; Bielawski, Christopher W; Binnemans, Koen

    2016-04-27

    This Review covers the recent developments (2005-2015) in the design, synthesis, characterization, and application of thermotropic ionic liquid crystals. It was designed to give a comprehensive overview of the "state-of-the-art" in the field. The discussion is focused on low molar mass and dendrimeric thermotropic ionic mesogens, as well as selected metal-containing compounds (metallomesogens), but some references to polymeric and/or lyotropic ionic liquid crystals and particularly to ionic liquids will also be provided. Although zwitterionic and mesoionic mesogens are also treated to some extent, emphasis will be directed toward liquid-crystalline materials consisting of organic cations and organic/inorganic anions that are not covalently bound but interact via electrostatic and other noncovalent interactions. PMID:27088310

  14. Ionic Liquid Epoxy Resin Monomers

    NASA Technical Reports Server (NTRS)

    Paley, Mark S. (Inventor)

    2013-01-01

    Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

  15. Hydrophobic ionic liquids

    DOEpatents

    Koch, V.R.; Nanjundiah, C.; Carlin, R.T.

    1998-10-27

    Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas shown in a diagram wherein R{sub 1}, R{sub 2}, R{sub 3}, R{sub 4}, R{sub 5}, and R{sub 6} are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F-, Cl-, CF{sub 3}-, SF{sub 5}-, CF{sub 3}S-, (CF{sub 3}){sub 2}CHS- or (CF{sub 3}){sub 3}CS-; and X{sup {minus}} is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 {angstrom}{sup 3}. 4 figs.

  16. Hydrophobic ionic liquids

    DOEpatents

    Koch, Victor R.; Nanjundiah, Chenniah; Carlin, Richard T.

    1998-01-01

    Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F--, Cl--, CF.sub.3 --, SF.sub.5 --, CF.sub.3 S--, (CF.sub.3).sub.2 CHS-- or (CF.sub.3).sub.3 CS--; and X.sup.- is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 .ANG..sup.3.

  17. Amniotic fluid

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002220.htm Amniotic fluid To use the sharing features on this page, please enable JavaScript. Amniotic fluid is a clear, slightly yellowish liquid that surrounds ...

  18. Fluid Mechanics.

    ERIC Educational Resources Information Center

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  19. Tunable soft structure in charged fluids confined by dielectric interfaces.

    PubMed

    Zwanikken, Jos W; Olvera de la Cruz, Monica

    2013-04-01

    Fluids of charged particles act as the supporting medium for chemical reactions and physical, dynamical, and biological processes. The local structure in an electrolytic background is deformed by micro- and nanoscopic polarizable objects. Vice versa, the forces between the objects are regulated by the cohesive properties of the background. We study here the range and strength of these forces and the microscopic origin from which they emerge. We find the forces to be sensitively dependent on the material properties of the charged fluid and the immersed solutes. The induced interactions can be varied over decades, offering high tunability and aided by accurate theory, control in experiments and applications. To distinguish correlational effects from simple ionic screening, we describe electrolyte-induced forces between neutral objects. The interplay of thermal motion, short-range repulsions, and electrostatic forces is responsible for a soft structure in the fluid. This structure changes near polarizable interfaces and causes diverse attractions between confining walls that seem well-exploited by microbiological systems. For parameters that correspond to monovalent electrolytes in biologically and technologically relevant aqueous environments, we find induced forces between nanoscopic areas of the order of piconewtons over a few nanometers. PMID:23487798

  20. Dual Ionic and Organic Nature of Ionic Liquids

    PubMed Central

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids—a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs. PMID:26782660

  1. Dual Ionic and Organic Nature of Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids—a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs.

  2. Dual Ionic and Organic Nature of Ionic Liquids.

    PubMed

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids--a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs. PMID:26782660

  3. Ionic dependence of sulphur mustard cytotoxicity

    SciTech Connect

    Sawyer, Thomas W. Nelson, Peggy; Bjarnason, Stephen; Vair, Cory; Shei Yimin; Tenn, Catherine; Lecavalier, Pierre; Burczyk, Andrew

    2010-09-15

    The effect of ionic environment on sulphur mustard (bis 2-chloroethyl sulphide; HD) toxicity was examined in CHO-K1 cells. Cultures were treated with HD in different ionic environments at constant osmolar conditions (320 mOsM, pH 7.4). The cultures were refed with fresh culture medium 1 h after HD exposure, and viability was assessed. Little toxicity was apparent when HD exposures were carried out in ion-free sucrose buffer compared to LC{sub 50} values of {approx} 100-150 {mu}M when the cultures were treated with HD in culture medium. Addition of NaCl to the buffer increased HD toxicity in a salt concentration-dependent manner to values similar to those obtained in culture medium. HD toxicity was dependent on both cationic and anionic species with anionic environment playing a much larger role in determining toxicity. Substitution of NaI for NaCl in the treatment buffers increased HD toxicity by over 1000%. The activity of the sodium hydrogen exchanger (NHE) in recovering from cytosolic acidification in salt-free and in different chloride salts did not correlate with the HD-induced toxicity in these buffers. However, the inhibition by HD of intracellular pH regulation correlated with its toxicity in NaCl, NaI and sucrose buffers. Analytical chemical studies and the toxicity of the iodine mustard derivative ruled out the role of chemical reactions yielding differentially toxic species as being responsible for the differences in HD toxicity observed. This work demonstrates that the early events that HD sets into motion to cause toxicity are dependent on ionic environment, possibly due to intracellular pH deregulation.

  4. Ionic Graphitization of Ultrathin Films of Ionic Compounds.

    PubMed

    Kvashnin, A G; Pashkin, E Y; Yakobson, B I; Sorokin, P B

    2016-07-21

    On the basis of ab initio density functional calculations, we performed a comprehensive investigation of the general graphitization tendency in rocksalt-type structures. In this paper, we determine the critical slab thickness for a range of ionic cubic crystal systems, below which a spontaneous conversion from a cubic to a layered graphitic-like structure occurs. This conversion is driven by surface energy reduction. Using only fundamental parameters of the compounds such as the Allen electronegativity and ionic radius of the metal atom, we also develop an analytical relation to estimate the critical number of layers. PMID:27333810

  5. On the viscosity of pyridinium based ionic liquids: an experimental and computational study.

    PubMed

    Bandrés, Isabel; Alcalde, Rafael; Lafuente, Carlos; Atilhan, Mert; Aparicio, Santiago

    2011-11-01

    A study on the viscosity of eight pyridinium based ionic liquids is reported for wide pressure and temperature ranges. Measurements were performed using an electromagnetic moving piston viscometer. Experimental data were fitted to a Tait-like equation demonstrating good correlations, which was used to calculate pressure/viscosity and temperature/viscosity coefficients. The effect of the involved anions and cation on the ionic liquid viscosity was analyzed from a molecular viewpoint using hole theory, quantum chemistry calculations using density functional theory, and classical molecular dynamics simulations. The analysis of the experimental and computational results shows the complex effects controlling viscosity of studied fluids, including strength of ionic pairs, molecular sizes, and mobility and effects rising from the availability and cavity sizes distributions in pyridinium-based ionic liquids. PMID:21942824

  6. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C.A.; Xu, K.; Liu, C.

    1996-01-16

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100 C or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors. 4 figs.

  7. Lithium ion conducting ionic electrolytes

    DOEpatents

    Angell, C. Austen; Xu, Kang; Liu, Changle

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte is described which has exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature. It comprises molten lithium salts or salt mixtures in which a small amount of an anionic polymer lithium salt is dissolved to stabilize the liquid against recrystallization. Further, a liquid ionic electrolyte which has been rubberized by addition of an extra proportion of anionic polymer, and which has good chemical and electrochemical stability, is described. This presents an attractive alternative to conventional salt-in-polymer electrolytes which are not cationic conductors.

  8. Ionic conductivity studies of gel polyelectrolyte based on ionic liquid

    NASA Astrophysics Data System (ADS)

    Cha, E. H.; Lim, S. A.; Park, J. H.; Kim, D. W.; Macfarlane, D. R.

    Novel lithium polyelectrolyte-ionic liquids have been prepared and characterized of their properties. Poly(lithium 2-acrylamido-2-methyl propanesulfonate) (PAMPSLi) and its copolymer with N-vinyl formamide (VF) also has been prepared as a copolymer. 1-Ethyl-3-methylimidazolium tricyanomethanide (emImTCM) and N, N-dimethyl- N-propyl- N-butyl ammonium tricyanomethanide (N 1134TCM) which are chosen because of the same with the anion of ionic liquid were prepared. The ionic conductivity of copolymer system (PAMPSLi/PVF/emImTCM: 5.43 × 10 -3 S cm -1 at 25 °C) exhibits about over four times higher than that of homopolymer system (PAMPSLi/emImTCM: 1.28 × 10 -3 S cm -1 at 25 °C). Introduction of vinyl formamide into the copolymer type can increase the dissociation of the lithium cations from the polymer backbone. The ionic conductivity of copolymer with emImTCM (PAMPSLi/PVF/emImTCM) exhibits the higher conductivity than that of PAMPSLi/PVF/N 1134TCM (2.48 × 10 -3 S cm -1). Because of using the polymerizable anion it is seen to maintain high flexibility of imidazolium cation effectively to exhibit the higher conductivity. And also the viscosity of emImTCM (19.56 cP) is lower than that of N 1134TCM (28.61 cP). Low viscosity leads to a fast rate of diffusion of redox species.

  9. Nanoporous membranes with electrochemically switchable, chemically stabilized ionic selectivity

    NASA Astrophysics Data System (ADS)

    Small, Leo J.; Wheeler, David R.; Spoerke, Erik D.

    2015-10-01

    Nanopore size, shape, and surface charge all play important roles in regulating ionic transport through nanoporous membranes. The ability to control these parameters in situ provides a means to create ion transport systems tunable in real time. Here, we present a new strategy to address this challenge, utilizing three unique electrochemically switchable chemistries to manipulate the terminal functional group and control the resulting surface charge throughout ensembles of gold plated nanopores in ion-tracked polycarbonate membranes 3 cm2 in area. We demonstrate the diazonium mediated surface functionalization with (1) nitrophenyl chemistry, (2) quinone chemistry, and (3) previously unreported trimethyl lock chemistry. Unlike other works, these chemistries are chemically stabilized, eliminating the need for a continuously applied gate voltage to maintain a given state and retain ionic selectivity. The effect of surface functionalization and nanopore geometry on selective ion transport through these functionalized membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. The nitrophenyl surface allows for ionic selectivity to be irreversibly switched in situ from cation-selective to anion-selective upon reduction to an aminophenyl surface. The quinone-terminated surface enables reversible changes between no ionic selectivity and a slight cationic selectivity. Alternatively, the trimethyl lock allows ionic selectivity to be reversibly switched by up to a factor of 8, approaching ideal selectivity, as a carboxylic acid group is electrochemically revealed or hidden. By varying the pore shape from cylindrical to conical, it is demonstrated that a controllable directionality can be imparted to the ionic selectivity. Combining control of nanopore geometry with stable, switchable chemistries facilitates superior control of molecular transport across the membrane, enabling tunable ion transport systems.Nanopore size, shape, and surface charge all play

  10. Nanoporous membranes with electrochemically switchable, chemically stabilized ionic selectivity

    NASA Astrophysics Data System (ADS)

    Small, Leo J.; Wheeler, David R.; Spoerke, Erik D.

    2015-10-01

    Nanopore size, shape, and surface charge all play important roles in regulating ionic transport through nanoporous membranes. The ability to control these parameters in situ provides a means to create ion transport systems tunable in real time. Here, we present a new strategy to address this challenge, utilizing three unique electrochemically switchable chemistries to manipulate the terminal functional group and control the resulting surface charge throughout ensembles of gold plated nanopores in ion-tracked polycarbonate membranes 3 cm2 in area. We demonstrate the diazonium mediated surface functionalization with (1) nitrophenyl chemistry, (2) quinone chemistry, and (3) previously unreported trimethyl lock chemistry. Unlike other works, these chemistries are chemically stabilized, eliminating the need for a continuously applied gate voltage to maintain a given state and retain ionic selectivity. The effect of surface functionalization and nanopore geometry on selective ion transport through these functionalized membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. The nitrophenyl surface allows for ionic selectivity to be irreversibly switched in situ from cation-selective to anion-selective upon reduction to an aminophenyl surface. The quinone-terminated surface enables reversible changes between no ionic selectivity and a slight cationic selectivity. Alternatively, the trimethyl lock allows ionic selectivity to be reversibly switched by up to a factor of 8, approaching ideal selectivity, as a carboxylic acid group is electrochemically revealed or hidden. By varying the pore shape from cylindrical to conical, it is demonstrated that a controllable directionality can be imparted to the ionic selectivity. Combining control of nanopore geometry with stable, switchable chemistries facilitates superior control of molecular transport across the membrane, enabling tunable ion transport systems.Nanopore size, shape, and surface charge all play

  11. Spacer fluids

    SciTech Connect

    Wilson, W.N.; Bradshaw, R.D.; Wilton, B.S.; Carpenter, R.B.

    1992-05-19

    This patent describes a method for cementing a wellbore penetrating an earth formation into which a conduit extends, the wellbore having a space occupied by a drilling fluid. It comprises displacing the drilling fluid from the space with a spacer fluid comprising: sulfonated styrene-maleic anhydride copolymer, bentonite, welan gum, surfactant and a weighting agent; and displacing the spacer composition and filling the wellbore space with a settable cement composition.

  12. Fluid dynamics of heart development.

    PubMed

    Santhanakrishnan, Arvind; Miller, Laura A

    2011-09-01

    The morphology, muscle mechanics, fluid dynamics, conduction properties, and molecular biology of the developing embryonic heart have received much attention in recent years due to the importance of both fluid and elastic forces in shaping the heart as well as the striking relationship between the heart's evolution and development. Although few studies have directly addressed the connection between fluid dynamics and heart development, a number of studies suggest that fluids may play a key role in morphogenic signaling. For example, fluid shear stress may trigger biochemical cascades within the endothelial cells of the developing heart that regulate chamber and valve morphogenesis. Myocardial activity generates forces on the intracardiac blood, creating pressure gradients across the cardiac wall. These pressures may also serve as epigenetic signals. In this article, the fluid dynamics of the early stages of heart development is reviewed. The relevant work in cardiac morphology, muscle mechanics, regulatory networks, and electrophysiology is also reviewed in the context of intracardial fluid dynamics. PMID:21327946

  13. High-flux ionic diodes, ionic transistors and ionic amplifiers based on external ion concentration polarization by an ion exchange membrane: a new scalable ionic circuit platform.

    PubMed

    Sun, Gongchen; Senapati, Satyajyoti; Chang, Hsueh-Chia

    2016-04-01

    A microfluidic ion exchange membrane hybrid chip is fabricated using polymer-based, lithography-free methods to achieve ionic diode, transistor and amplifier functionalities with the same four-terminal design. The high ionic flux (>100 μA) feature of the chip can enable a scalable integrated ionic circuit platform for micro-total-analytical systems. PMID:26960551

  14. Ionic transport and electrical relaxation in glass

    NASA Astrophysics Data System (ADS)

    Moynihan, C. T.; Barkatt, A.

    1987-09-01

    The basic purpose of the work described was to achieve extensive and quantitative understanding of ionic transport processes in melts and glasses by means of a combination of experimental measurements and theoretical modeling. Two major subjects of the study were the mechanism of dielectric relaxation in ionically conducting glasses and the large retardation of ionic transport in mixed alkali systems.

  15. The hype with ionic liquids as solvents

    NASA Astrophysics Data System (ADS)

    Kunz, Werner; Häckl, Katharina

    2016-09-01

    In this mini review, we give our personal opinion about the present state of the art concerning Ionic Liquids, proposed as alternative solvents. In particular, we consider their different drawbacks and disadvantages and discuss the critical aspects of the research of Ionic Liquids as solvents. Finally, we point out some aspects on potentially promising Ionic Liquid solvents.

  16. Transient streaming potentials under varying pore-water ionic strength

    NASA Astrophysics Data System (ADS)

    Malama, B.

    2014-12-01

    Streaming potentials (SP) are generated when polar fluids such as groundwater flow through porous media that have charged mineral surfaces. This is due to the flow-shearing of the diffuse layer of the electric double layer (EDL), which is known to form in the fluid phase at the fluid-rock interface. Previous works have suggested that the EDL vanishes at high pore-fluid ionic strengths resulting in vanishing SP signals. However, recent observations in sea-water intrusion applications by Jackson and coworkers indicate that measurable SP signals are obtainable in flows of fluids with high ionic strengths through silica sand. We demonstrate the repeatability of these observations through a series of laboratory flow experiments performed on 98% silica sand in a falling-head permeameter with brines of concentrations ranging from 0.001M to about 5 M NaCl. The results of the experiments, which clearly show measurable SP signals even at the highest concentration of 5 M NaCl, are reported. They are also used to estimate the hydraulic conductivity and electrokinetic coupling coefficient. The linearity assumption for the relation between pressure and SP differentials is evaluated for high pore-water NaCl concentrations. Additionally, displacement of one brine by another of different NaCl concentration yields dramatic transient SP responses that may be harnessed in the development of early-detection/warning technologies for sea-water intrusion applications. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. This research is funded by WIPP programs administered by the Office of Environmental Management (EM) of the U.S Department of Energy.

  17. Application of Ionic Liquids in Hydrometallurgy

    PubMed Central

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

  18. Observation of ionic Coulomb blockade in nanopores

    NASA Astrophysics Data System (ADS)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.

  19. Application of ionic liquids in hydrometallurgy.

    PubMed

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

  20. Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

    2008-01-01

    Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

  1. Ionic Transport Coefficients of Dense Plasmas without Molecular Dynamics.

    PubMed

    Daligault, Jérôme; Baalrud, Scott D; Starrett, Charles E; Saumon, Didier; Sjostrom, Travis

    2016-02-19

    We present a theoretical model that allows a fast and accurate evaluation of ionic transport properties of realistic plasmas spanning from warm and dense to hot and dilute conditions, including mixtures. This is achieved by combining a recent kinetic theory based on effective interaction potentials with a model for the equilibrium radial density distribution based on an average atom model and the integral equations theory of fluids. The model should find broad use in applications where nonideal plasma conditions are traversed, including inertial confinement fusion, compact astrophysical objects, solar and extrasolar planets, and numerous present-day high energy density laboratory experiments. PMID:26943540

  2. Ionic Transport Coefficients of Dense Plasmas without Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Daligault, Jérôme; Baalrud, Scott D.; Starrett, Charles E.; Saumon, Didier; Sjostrom, Travis

    2016-02-01

    We present a theoretical model that allows a fast and accurate evaluation of ionic transport properties of realistic plasmas spanning from warm and dense to hot and dilute conditions, including mixtures. This is achieved by combining a recent kinetic theory based on effective interaction potentials with a model for the equilibrium radial density distribution based on an average atom model and the integral equations theory of fluids. The model should find broad use in applications where nonideal plasma conditions are traversed, including inertial confinement fusion, compact astrophysical objects, solar and extrasolar planets, and numerous present-day high energy density laboratory experiments.

  3. Regulation by intracellular Ca sup 2+ and cyclic AMP of the growth factor-induced ruffling membrane formation and stimulation of fluid-phase endocytosis and exocytosis

    SciTech Connect

    Miyata, Yoshihiko Tokyo Metropolitan Inst. of Medical Science ); Nishida, Eisuke; Sakai, Hikoichi ); Koyasu, Shigeo; Yahara, Ichiro )

    1989-04-01

    Insulin, insulin-like growth factor-I (IGF-I), and epidermal growth factor (EGF) induce formation of ruffling membranes and stimulate the fluid-phase endocytosis and exocytosis in human epidermoid carcinoma KB cells. An increase in intracellular Ca{sup 2+} concentration by treatment with A23187, a calcium ionophore, or an increase in intracellular cAMP level by treatment with dibutyryl cAMP or forskolin almost completely inhibited the insulin-, IGF-I-, or EGF-induced formation of ruffling membranes. Increases in Ca{sup 2+} or cAMP concentration also inhibited almost completely the stimulation of fluid-phase endocytosis and exocytosis elicited by these growth factors. These results suggest that the growth factor-induced ruffling membrane formation and the stimulation of fluid-phase endocytosis and exocytosis have a common regulatory mechanism involving intracellular concentrations of Ca{sup 2+} and cAMP. {sup 125}I-EGF binding assays and immunoprecipitation experiments with anti-phosphotyrosine antibody revealed that treatment of KB cells with A23187, dibutyryl cAMP, or forskolin did not inhibit the EGF binding to the cells nor subsequent tyrosine autophosphorylation of its receptors. These results indicate that Ca{sup 2+}- and/or cAMP-sensitive intracellular reactions exist downstream from the receptor kinase activation in the process of these early cellular responses.

  4. Fluid inflation

    SciTech Connect

    Chen, X.; Firouzjahi, H.; Namjoo, M.H.; Sasaki, M. E-mail: firouz@ipm.ir E-mail: misao@yukawa.kyoto-u.ac.jp

    2013-09-01

    In this work we present an inflationary mechanism based on fluid dynamics. Starting with the action for a single barotropic perfect fluid, we outline the procedure to calculate the power spectrum and the bispectrum of the curvature perturbation. It is shown that a perfect barotropic fluid naturally gives rise to a non-attractor inflationary universe in which the curvature perturbation is not frozen on super-horizon scales. We show that a scale-invariant power spectrum can be obtained with the local non-Gaussianity parameter f{sub NL} = 5/2.

  5. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, M.; Hargens, A.; Dulchavsky, S.; Ebert, D.; Lee, S.; Lauriie, S.; Garcia, K.; Sargsyan, A.; Martin, D.; Ribeiro, L.; Lui, J.; Macias, B.; Arbeille, P.; Danielson, R.; Chang, D.; Johnston, S.; Ploutz-Snyder, R.; Smith, S.

    2016-01-01

    NASA is focusing on long-duration missions on the International Space Station (ISS) and future exploration-class missions beyond low-Earth orbit. Visual acuity changes observed after short-duration missions were largely transient, but more than 50% of ISS astronauts experienced more profound, chronic changes with objective structural and functional findings such as papilledema and choroidal folds. Globe flattening, optic nerve sheath dilation, and optic nerve tortuosity also are apparent. This pattern is referred to as the visual impairment and intracranial pressure (VIIP) syndrome. VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) may be associated with the spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. The purpose of this study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight, and to correlate these findings with vision changes and other elements of the VIIP syndrome. We also seek to determine whether the magnitude of fluid shifts during spaceflight, as well as the VIIP-related effects of those shifts, is predicted by the crewmember's preflight conditions and responses to acute hemodynamic manipulations (such as head-down tilt). Lastly, we will evaluate the patterns of fluid distribution in ISS astronauts during acute reversal of fluid shifts through application of lower body negative pressure (LBNP) interventions to characterize and explain general and individual responses. METHODS: We will examine a variety of physiologic variables in 10 long-duration ISS crewmembers using the test conditions and timeline presented in the Figure below. Measures include: (1) fluid compartmentalization (total body water by D2O, extracellular fluid by NaBr, intracellular fluid by calculation, plasma volume by CO rebreathe, interstitial fluid by calculation); (2) forehead/eyelids, tibia, calcaneus tissue thickness (by

  6. Identification of vascular endothelial genes differentially responsive to fluid mechanical stimuli: cyclooxygenase-2, manganese superoxide dismutase, and endothelial cell nitric oxide synthase are selectively up-regulated by steady laminar shear stress.

    PubMed Central

    Topper, J N; Cai, J; Falb, D; Gimbrone, M A

    1996-01-01

    Early atherosclerotic lesions develop in a topographical pattern that strongly suggests involvement of hemodynamic forces in their pathogenesis. We hypothesized that certain endothelial genes, which exhibit differential responsiveness to distinct fluid mechanical stimuli, may participate in the atherogenic process by modulating, on a local level within the arterial wall, the effects of systemic risk factors. A differential display strategy using cultured human endothelial cells has identified two genes, manganese superoxide dismutase and cyclooxygenase-2, that exhibit selective and sustained up-regulation by steady laminar shear stress (LSS). Turbulent shear stress, a nonlaminar fluid mechanical stimulus, does not induce these genes. The endothelial form of nitric oxide synthase also demonstrates a similar LSS-selective pattern of induction. Thus, three genes with potential atheroprotective (antioxidant, antithrombotic, and antiadhesive) activities manifest a differential response to distinct fluid mechanical stimuli, providing a possible mechanistic link between endothelial gene expression and early events in atherogenesis. The activities of these and other LSS-responsive genes may have important implications for the pathogenesis and prevention of atherosclerosis. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8816815

  7. Theoretical Study of Renewable Ionic Liquids in the Pure State and with Graphene and Carbon Nanotubes.

    PubMed

    García, Gregorio; Atilhan, Mert; Aparicio, Santiago

    2015-09-17

    The N-ethyl-N-(furan-2-ylmethyl)ethanaminium dihydrogen phosphate ionic liquid was studied as a model of ionic liquids which can be produced from totally renewable sources. A computational study using both molecular dynamics and density functional theory methods was carried out. The properties, structuring, and intermolecular interactions (hydrogen bonding) of this fluid in the pure state were studied as a function of pressure and temperature. Likewise, the adsorption on graphene and the confinement between graphene sheets was also studied. The solvation of single walled carbon nanotubes in the selected ionic liquid was analyzed together with the behavior of ions confined inside these nanotubes. The reported results show remarkable properties for this fluid, which show that many of the most relevant properties of ionic liquids and their ability to interact with carbon nanosystems may be maintained and even improved using new families of renewable compounds instead of classic types of ionic liquids with worse environmental, toxicological, and economical profiles. PMID:26305599

  8. Radiation-induced solidification of ionic liquid under extreme electric field

    NASA Astrophysics Data System (ADS)

    Terhune, Kurt J.; King, Lyon B.; He, Kai; Cumings, John

    2016-09-01

    An extreme electric field on the order of 1010 V m‑1 was applied to the free surface of an ionic liquid to cause electric-field-induced evaporation of molecular ions from the liquid. The point of ion emission was observed in situ using a TEM. The resulting electrospray emission process was observed to create nanoscale high-aspect-ratio dendritic features that were aligned with the direction of the electric field. Upon removal of the stressing field the features were seen to remain, indicating that the ionic liquid residue was solidified or gelled. Similar electrospray experiments performed in a field-emission scanning electron microscope revealed that the features are created when the high-energy electron beam damages the molecular structure of the ionic liquid. While the electric field does not play a direct role in the fluid modification, the electric stress was critical in detecting the liquid property change. It is only because the electric stress mechanically elongated the fluid during the electrospray process and these obviously non-liquid structures persisted when the field was removed that the damage was evident. This evidence of ionic liquid radiation damage may have significant bearing on electrospray devices where it is possible to produce high-energy secondary electrons through surface impacts of emitted ions downstream of the emitter. Any such impacts that are in close proximity could see reflected secondary electrons impact the emitter causing gelling of the ionic liquid.

  9. Radiation-induced solidification of ionic liquid under extreme electric field.

    PubMed

    Terhune, Kurt J; King, Lyon B; He, Kai; Cumings, John

    2016-09-16

    An extreme electric field on the order of 10(10) V m(-1) was applied to the free surface of an ionic liquid to cause electric-field-induced evaporation of molecular ions from the liquid. The point of ion emission was observed in situ using a TEM. The resulting electrospray emission process was observed to create nanoscale high-aspect-ratio dendritic features that were aligned with the direction of the electric field. Upon removal of the stressing field the features were seen to remain, indicating that the ionic liquid residue was solidified or gelled. Similar electrospray experiments performed in a field-emission scanning electron microscope revealed that the features are created when the high-energy electron beam damages the molecular structure of the ionic liquid. While the electric field does not play a direct role in the fluid modification, the electric stress was critical in detecting the liquid property change. It is only because the electric stress mechanically elongated the fluid during the electrospray process and these obviously non-liquid structures persisted when the field was removed that the damage was evident. This evidence of ionic liquid radiation damage may have significant bearing on electrospray devices where it is possible to produce high-energy secondary electrons through surface impacts of emitted ions downstream of the emitter. Any such impacts that are in close proximity could see reflected secondary electrons impact the emitter causing gelling of the ionic liquid. PMID:27487731

  10. Fluid Shifts

    NASA Technical Reports Server (NTRS)

    Stenger, Michael B.; Hargens, Alan R.; Dulchavsky, Scott A.; Ebert, Douglas J.; Lee, Stuart M. C.; Laurie, Steven S.; Garcia, Kathleen M.; Sargsyan, Ashot E.; Martin, David S.; Liu, John; Macias, Brandon R.; Arbeille, Philippe; Danielson, Richard; Chang, Douglas; Gunga, Hanns-Christian; Johnston, Smith L.; Westby, Christian M.; Ploutz-Snyder, Robert J.; Smith, Scott M.

    2016-01-01

    We hypothesize that microgravity-induced cephalad fluid shifts elevate intracranial pressure (ICP) and contribute to VIIP. We will test this hypothesis and a possible countermeasure in ISS astronauts.