Ion relations of haemolymph, palliai fluid, and mucus of Lymnaea stagnalis

1981 ◽  
Vol 59 (4) ◽  
pp. 605-613 ◽  
Author(s):  
L. C. Schlichter
Keyword(s):  
Activity Coefficients ◽  
Lymnaea Stagnalis ◽  
Inorganic Ions ◽  
Pond Water ◽  
Mucus Secretion ◽  
High Concentration ◽  
Hückel Theory ◽  
Ion Relations ◽  
Inorganic Complexes ◽  
Secretion Rates

The concentrations, and where possible, activities of the main inorganic ions were measured in haemolymph, palliai fluid, and mucus of Lymnaea stagnalis appressa Say (Gastropoda: Pulmonata), and in the artificial pond water (APW) in which the snails were stored. Activity coefficients of Na, K, Ca, and Cl in pallial fluid and in APW were compared with values calculated from Debye–Hückel theory. Some Na and Ca in pallial fluid, and Ca in APW are probably bound in organic or inorganic complexes. Comparison of the Nernst potentials with the transepithelial potential difference supports the idea that Na, K, Ca, and Cl must be actively taken up from APW by the snail. Pallial fluid is not identical to haemolymph and is probably a mixture of urine and haemolymph. Pallial fluid contaminates mucus during mucus collection. A method of correcting for this contamination is given. After correction, mucus had higher Ca and K, and possibly higher Mg concentrations than did haemolymph. Mucus had a high concentration of NH4+. Possible sources of ions in mucus are discussed. Mucus secretion rates are low enough that this is not an important cause of ion loss to the snail. Using ether to stimulate mucus secretion alters the water and K content of the mucus.

scholarly journals Synthesis of (Bi,Pb)-2223 superconductor powder by pechini method

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Guilherme Botega Torsoni ◽  
Cícero Rafael Cena ◽  
Gustavo Quereza de Freitas ◽  
Claudio Luis Carvalho
Keyword(s):  
Pechini Method ◽  
Crystallization Kinetic ◽  
Inorganic Ions ◽  
Precursor Solution ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Powder Morphology ◽  
Chemical Reagents ◽  
Different Temperatures ◽  
Xrd Techniques

In this paper, we present a detailed route of synthesis to produce ceramic superconductor Bi1,6Pb0,4Sr2Ca2Cu3Ox (Bi,Pb)-2223 powder by Pechini method. The obtained polymeric precursor solution was produced by using inexpensive chemical reagents, which showed a great stability for three weeks with high concentration of BPSCCO inorganic ions. The crystallization kinetic of BPSCCO powder was investigated by thermal analysis (DSC/TGA) and X-ray diffraction (XRD) techniques. The thermal treatment of the BPSCCO powder at different temperatures showed that complex phase equilibrium occurs to the system. The three superconductor phases seems to coexist in a large range of temperature, the Bi-2201 phase was crystallized around 500 oC and then, after 840 oC the desirable (Bi,Pb)-2223 phase appears with coexistence of the Bi-2212 phase at low quantity. Finally, the powder morphology was characterized by scanning electron microscopy (SEM), the results point to a typical plate like formation of the grains.

scholarly journals Voltage- and Calcium-Dependent Inactivation of Calcium Channels in Lymnaea Neurons

1999 ◽  
Vol 114 (4) ◽  
pp. 535-550 ◽  
Author(s):  
Shalini Gera ◽  
Lou Byerly
Keyword(s):  
Cytochalasin B ◽  
Lymnaea Stagnalis ◽  
Slow Component ◽  
Freshwater Snail ◽  
High Concentration ◽  
Calcium Dependent ◽  
Channel Inactivation ◽  
Dependent Inactivation ◽  
Lymnaea Neurons ◽  
Ca2 Channels

Ca2+ channel inactivation in the neurons of the freshwater snail, Lymnaea stagnalis, was studied using patch-clamp techniques. In the presence of a high concentration of intracellular Ca2+ buffer (5 mM EGTA), the inactivation of these Ca2+ channels is entirely voltage dependent; it is not influenced by the identity of the permeant divalent ions or the amount of extracellular Ca2+ influx, or reduced by higher levels of intracellular Ca2+ buffering. Inactivation measured under these conditions, despite being independent of Ca2+ influx, has a bell-shaped voltage dependence, which has often been considered a hallmark of Ca2+-dependent inactivation. Ca2+-dependent inactivation does occur in Lymnaea neurons, when the concentration of the intracellular Ca2+ buffer is lowered to 0.1 mM EGTA. However, the magnitude of Ca2+-dependent inactivation does not increase linearly with Ca2+ influx, but saturates for relatively small amounts of Ca2+ influx. Recovery from inactivation at negative potentials is biexponential and has the same time constants in the presence of different intracellular concentrations of EGTA. However, the amplitude of the slow component is selectively enhanced by a decrease in intracellular EGTA, thus slowing the overall rate of recovery. The ability of 5 mM EGTA to completely suppress Ca2+-dependent inactivation suggests that the Ca2+ binding site is at some distance from the channel protein itself. No evidence was found of a role for serine/threonine phosphorylation in Ca2+ channel inactivation. Cytochalasin B, a microfilament disrupter, was found to greatly enhance the amount of Ca2+ channel inactivation, but the involvement of actin filaments in this effect of cytochalasin B on Ca2+ channel inactivation could not be verified using other pharmacological compounds. Thus, the mechanism of Ca2+-dependent inactivation in these neurons remains unknown, but appears to differ from those proposed for mammalian L-type Ca2+ channels.

scholarly journals Chemical and geochemical modeling. Thermodynamic models for binary fluoride systems from low to very high concentration (> 35 m) at 298.15 K

2021 ◽  
Vol 8 (2) ◽  
pp. 1-15
Author(s):  
Stanislav Donchev ◽  
Tsvetan V. Tsenov ◽  
Christomir Christov
Keyword(s):  
Activity Coefficients ◽  
Binary Systems ◽  
Geochemical Modeling ◽  
Osmotic Coefficients ◽  
Model Parameters ◽  
Thermodynamic Models ◽  
High Concentration ◽  
Activity Data ◽  
Solubility Products ◽  
Very High

Abstract In this study we developed well validated thermodynamic models for solution behavior and solid-liquid equilibrium for all fluoride binary systems, for which activity data are available. The subject of modeling study are 5 fluoride systems of the type 1-1 (HF-H2O, NaF-H2O, KF-H2O, RbF-H2O, and CsF-H2O) and one of 1-2 type (H2SiF6-H2O) from low to very high concentration at 298.15 K. Models are developed on the basis of Pitzer ion interactions approach. The recommendations on mean activity coefficients (γ±) have been used to construct the model for HF-H2O system. To parameterize models for all other 5 binary systems we used all available raw experimental osmotic coefficients data (φ) for whole concentration range of solutions, and up to saturation point. The predictions of new developed here models are in excellent agreement with experimental osmotic coefficients data, and with recommendations on activity coefficients in binary solutions from low to very high concentration: up to 20 mol. kg−1 in HF-H2O, and up to 35.6 mol.kg−1 in CsF-H2O. The Deliquescence Relative Humidity (DRH (%)) and thermodynamic solubility products (as ln Ko sp) of 4 solid phases [NaF(s), KF.2H2O(s), RbF(s), and CsF(s)] have been determined on the basis of evaluated model parameters and using experimental m(sat) solubility data.

Unstirred Mucus Layers: Ion Exchange Properties and Effect On Ion Regulation in Lymnaea Stagnalis

1982 ◽  
Vol 98 (1) ◽  
pp. 363-372
Author(s):  
L. C. SCHLICHTER
Keyword(s):  
Ion Exchange ◽  
Lymnaea Stagnalis ◽  
Equilibrium Dialysis ◽  
Electrical Potential ◽  
Physiological Saline ◽  
Pond Water ◽  
Freshwater Snail ◽  
Exchange Capacity ◽  
Electrical Potential Difference ◽  
Ion Regulation

Mucus from the footsole of the freshwater snail Lymnaea stagnalis behaves as a weak, negatively charged ion exchanger. Activities and concentrations of Na, K, Ca, and Cl were measured in mucus dialysed to equilibrium against artificial pond water or physiological saline. Observed activity coefficients (activity/concentration) in mucus were compared with those predicted by the Debye-Huckel theory to interpret the effects of electrostatic forces between the polyelectrolyte ions and small ions. The affinity of mucus for small ions decreased in the series, Ca2+, K+, Na+, Cl−. The extent to which mucus can concentrate cations was measured using three different methods: by titrating the fixed acidic groups with K or Ca and by equilibrium dialysis after which the electrical potential difference was either measured directly or was calculated from the Nernst potential for Na. Ion exchange titration indicated a much smaller exchange capacity than did the other two methods. Kinetics of cation uptake by the snail from dilute media were re-interpreted by considering the enhanced concentrations of cations in the mucus layer. It was shown that the presence of mucus in the unstirred layer adjacent to a transporting epithelium can result in an underestimate of the Michaelis constant (Km) determined from influx measurements.

scholarly journals New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

2011 ◽  
Vol 11 (17) ◽  
pp. 9155-9206 ◽  
Author(s):  
A. Zuend ◽  
C. Marcolli ◽  
A. M. Booth ◽  
D. M. Lienhard ◽  
V. Soonsin ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Functional Groups ◽  
Organic Compounds ◽  
Activity Coefficients ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Inorganic Ions ◽  
Aqueous Mixtures ◽  
Organic Functional Groups ◽  
Ether Ester

Abstract. We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl−, Br−, NO3−, HSO4−, and SO42−. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

scholarly journals Effects of uncertainties in the thermodynamic properties of aerosol components in an air quality model – Part 1: Treatment of inorganic electrolytes and organic compounds in the condensed phase

2008 ◽  
Vol 8 (4) ◽  
pp. 1057-1085 ◽  
Author(s):  
S. L. Clegg ◽  
M. J. Kleeman ◽  
R. J. Griffin ◽  
J. H. Seinfeld
Keyword(s):  
Air Quality ◽  
Los Angeles ◽  
Thermodynamic Properties ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Activity Coefficients ◽  
Reaction Products ◽  
Air Quality Model ◽  
Quality Model ◽  
High Concentration

Abstract. Air quality models that generate the concentrations of semi-volatile and other condensable organic compounds using an explicit reaction mechanism require estimates of the physical and thermodynamic properties of the compounds that affect gas/aerosol partitioning: vapour pressure (as a subcooled liquid), and activity coefficients in the aerosol phase. The model of Griffin, Kleeman and co-workers (e.g., Griffin et al., 2003; Kleeman et al., 1999) assumes that aerosol particles consist of an aqueous phase, containing inorganic electrolytes and soluble organic compounds, and a hydrophobic phase containing mainly primary hydrocarbon material. Thirty eight semi-volatile reaction products are grouped into ten surrogate species which partition between the gas phase and both phases in the aerosol. Activity coefficients of the organic compounds are calculated using UNIFAC. In a companion paper (Clegg et al., 2008) we examine the likely uncertainties in the vapour pressures of the semi-volatile compounds and their effects on partitioning over a range of atmospheric relative humidities. In this work a simulation for the South Coast Air Basin surrounding Los Angeles, using lower vapour pressures of the semi-volatile surrogate compounds consistent with estimated uncertainties in the boiling points on which they are based, yields a doubling of the predicted 24-h average secondary organic aerosol concentrations. The dependency of organic compound partitioning on the treatment of inorganic electrolytes in the air quality model, and the performance of this component of the model, are determined by analysing the results of a trajectory calculation using an extended version of the Aerosol Inorganics Model of Wexler and Clegg (2002). Simplifications are identified where substantial efficiency gains can be made, principally: the omission of dissociation of the organic acid surrogates; restriction of aerosol organic compounds to one of the two phases (aqueous or hydrophobic) where equilibrium calculations suggest partitioning strongly in either direction; a single calculation of activity coefficients of the organic compounds for simulations where they are determined by the presence of one component at high concentration in either phase (i.e., water in the aqueous phase, or a hydrocarbon surrogate compound P8 in the hydrophobic phase) and are therefore almost invariant. The implications of the results for the development of aerosol models are discussed.

scholarly journals New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

2011 ◽  
Vol 11 (5) ◽  
pp. 15297-15416 ◽  
Author(s):  
A. Zuend ◽  
C. Marcolli ◽  
A. M. Booth ◽  
D. M. Lienhard ◽  
V. Soonsin ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Functional Groups ◽  
Organic Compounds ◽  
Activity Coefficients ◽  
Atmospheric Aerosols ◽  
Atmospheric Chemistry ◽  
Inorganic Ions ◽  
Aqueous Mixtures ◽  
Organic Functional Groups ◽  
Ether Ester

Abstract. We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl−, Br−, NO3−, HSO4−, and SO42−. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization algorithms. A number of exemplary calculations for systems containing atmospherically relevant aerosol components are shown. Amongst others, we discuss aqueous mixtures of ammonium sulfate with dicarboxylic acids and with levoglucosan. Overall, the new parameterization of AIOMFAC agrees well with a large number of experimental datasets. However, due to various reasons, for certain mixtures important deviations can occur. The new parameterization makes AIOMFAC a versatile thermodynamic tool. It enables the calculation of activity coefficients of thousands of different organic compounds in organic-inorganic mixtures of numerous components. Models based on AIOMFAC can be used to compute deliquescence relative humidities, liquid-liquid phase separations, and gas-particle partitioning of multicomponent mixtures of relevance for atmospheric chemistry or in other scientific fields.

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