Ionic switch controls the DNA state in phage λ

DOE PAGES

Li, Dong; Liu, Ting; Zuo, Xiaobing; ...

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

Ionic switch controls the DNA state in phage λ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Dong; Liu, Ting; Zuo, Xiaobing

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

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.

Vapor-liquid phase behavior of a size-asymmetric model of ionic fluids confined in a disordered matrix: The collective-variables-based approach

NASA Astrophysics Data System (ADS)

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

2018-02-01

We develop a theory based on the method of collective variables to study the vapor-liquid equilibrium of asymmetric ionic fluids confined in a disordered porous matrix. The approach allows us to formulate the perturbation theory using an extension of the scaled particle theory for a description of a reference system presented as a two-component hard-sphere fluid confined in a hard-sphere matrix. Treating an ionic fluid as a size- and charge-asymmetric primitive model (PM) we derive an explicit expression for the relevant chemical potential of a confined ionic system which takes into account the third-order correlations between ions. Using this expression, the phase diagrams for a size-asymmetric PM are calculated for different matrix porosities as well as for different sizes of matrix and fluid particles. It is observed that general trends of the coexistence curves with the matrix porosity are similar to those of simple fluids under disordered confinement, i.e., the coexistence region gets narrower with a decrease of porosity and, simultaneously, the reduced critical temperature Tc* and the critical density ρi,c * become lower. At the same time, our results suggest that an increase in size asymmetry of oppositely charged ions considerably affects the vapor-liquid diagrams leading to a faster decrease of Tc* and ρi,c * and even to a disappearance of the phase transition, especially for the case of small matrix particles.

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.

Nanoscale Ionic Liquids

DTIC Science & Technology

2006-11-01

Technical Report 11 December 2005 - 30 November 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanoscale Ionic Liquids 5b. GRANT NUMBER FA9550-06-1-0012...Title: Nanoscale Ionic Liquids Principal Investigator: Emmanuel P. Giannelis Address: Materials Science and Engineering, Bard Hall, Cornell University...based fluids exhibit high ionic conductivity. The NFs are typically synthesized by grafting a charged, oligomeric corona onto the nanoparticle cores

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.

Calcium and other ions in blood and skeleton of Nicaraguan fresh-water shark.

PubMed

URIST, M R

1962-09-21

The bull shark, Carcharhinus leucas, employing archaic but effective means of regulating the physical-chemical composition of its body fluids, thrives in tropical fresh-water rivers and lakes. The ionic strength of the serum and the concentrations of total solutes, calcium, urea, and other ions are below the levels found in marine elasmobranchs but higher than the levels in teleosts. The patterns of the calcium deposits of the vertebrae are identical in marine and fresh-water subspecies.

Influence of MRI contrast media on histamine release from mast cells.

PubMed

Kun, Tomasz; Jakubowski, Lucjusz

2012-07-01

Mast cells, owing to diversity of secreted mediators, play a crucial role in the regulation of inflammatory response. Together with basophils, mast cells constitute a central pathogenetic element of anaphylactic (IgE-dependent) and anaphylactoid (IgE-independent) reactions. In severe cases, generalized degranulation of mast cells may cause symptoms of anaphylactic shock. The influence of the classical, iodine-based contrast media on mastocyte degranulation has been fully described. Our objective was to determine the influence of the gadolinium-based MRI contrast media on histamine release from mast cells and to compare the activity of ionic and non-ionic preparations of contrast media. To determine the intensity of mast cell degranulation, we used an experimental model based on mastocytes isolated from rat peritoneal fluid. Purified suspensions of mast cells were incubated with various concentrations of Gd-DTPA and Gd-DTPA-BMA, and solutions of PEG 600 which served as a non-toxic osmotic stimulus. The intensity of mast cell activation was presented as mean percentage of histamine released from cells after incubation. The obtained results demonstrate that both ionic and non-ionic preparations of the MRI contrast media are able to induce mast cell degranulation in vitro. It was also proved that the non-ionic MRI contrast media stimulate mast cells markedly more weakly than ionic contrast media at identical concentration. The aforementioned results may suggest a more profitable safety profile of the non-ionic contrast preparations. We may also conclude that triggering of mast cell degranulation after incubation with the solutions of MRI contrast media results from non-specific osmotic stimulation and direct toxicity of free ionic residues.

Brain microdialysis as a tool to explore the ionic profile of the brain extracellular space in neurocritical patients: a methodological approach and feasibility study.

PubMed

Martínez-Valverde, Tamara; Vidal-Jorge, Marian; Montoya, Noelia; Sánchez-Guerrero, Angela; Manrique, Susana; Munar, Francisca; Pellegri, Maria-Dolors; Poca, Maria-Antonia; Sahuquillo, Juan

2015-01-01

Our aim is to determine whether the ionic concentration in brain microdialysate enables calculations of the actual Na(+), K(+), and Cl(-) concentrations in vitro and whether this method can be applied to determine the ionic concentrations in the brain extracellular fluid. We designed an experiment using CMA-71 probes (M Dialysis, Stockholm, Sweden) and the standard conditions used in a clinical setting. Nine CMA-71 probes were inserted in different matrices and perfused with mock cerebrospinal fluid containing 3% albumin at the standard infusion rate used in the clinical setting (0.3 μL/min). Microvials were replaced every 12 h, and the ionic concentrations, both in the dialysate and the matrix, were analyzed. For each ion, scatter plots were built, with [Na(+)], [K(+)], and [Cl(-)] in the dialysate as the predictor variables and the matrix concentrations as the outcome variables. A linear regression model allowed us to calculate the true ionic concentrations in the matrix. To demonstrate the feasibility of the method, we present the calculated ionic profile of one patient with a malignant infarction and a second with a severe traumatic brain injury. Our results confirm that the ionic concentration in microdialysate can be used to calculate the true concentrations of ions in a matrix and the actual concentrations in the extracellular fluid. Microdialysis offers the unique possibility of monitoring the dynamic changes of ions in the brain over time and opens a new avenue to explore the brain's ionic profile, its changes in brain edema, and how this profile can be modified with different therapies.

Conductance valve and pressure-to-conductance transducer method and apparatus

DOEpatents

Schoeniger, Joseph S.; Cummings, Eric B.; Brennan, James S.

2005-01-18

A device for interrupting or throttling undesired ionic transport through a fluid network is disclosed. The device acts as a fluid valve by reversibly generating a fixed "bubble" in the conducting solvent solution carried by the network. The device comprises a porous hydrophobic structure filling a portion of a connecting channel within the network and optionally incorporates flow restrictor elements at either end of the porous structure that function as pressure isolation barriers, and a fluid reservoir connected to the region of the channel containing the porous structure. Also included is a pressure pump connected to the fluid reservoir. The device operates by causing the pump to vary the hydraulic pressure to a quantity of solvent solution held within the reservoir and porous structure. At high pressures, most or all of the pores of the structure are filled with conducting liquid so the ionic conductance is high. At lower pressures, only a fraction of the pores are filled with liquid, so ionic conductivity is lower. Below a threshold pressure, the porous structure contains only vapor, so there is no liquid conduction path. The device therefore effectively throttles ionic transport through the porous structure and acts as a "conductance valve" or "pressure-to-conductance" transducer within the network.

Probing Lipid Bilayers under Ionic Imbalance.

PubMed

Lin, Jiaqi; Alexander-Katz, Alfredo

2016-12-06

Biological membranes are normally under a resting transmembrane potential (TMP), which originates from the ionic imbalance between extracellular fluids and cytosols, and serves as electric power storage for cells. In cell electroporation, the ionic imbalance builds up a high TMP, resulting in the poration of cell membranes. However, the relationship between ionic imbalance and TMP is not clearly understood, and little is known about the effect of ionic imbalance on the structure and dynamics of biological membranes. In this study, we used coarse-grained molecular dynamics to characterize a dipalmitoylphosphatidylcholine bilayer system under ionic imbalances ranging from 0 to ∼0.06 e charges per lipid (e/Lip). We found that the TMP displayed three distinct regimes: 1) a linear regime between 0 and 0.045 e/Lip, where the TMP increased linearly with ionic imbalance; 2) a yielding regime between ∼0.045 and 0.060 e/Lip, where the TMP displayed a plateau; and 3) a poration regime above ∼0.060 e/Lip, where we observed pore formation within the sampling time (80 ns). We found no structural changes in the linear regime, apart from a nonlinear increase in the area per lipid, whereas in the yielding regime the bilayer exhibited substantial thinning, leading to an excess of water and Na + within the bilayer, as well as significant misalignment of the lipid tails. In the poration regime, lipid molecules diffused slightly faster. We also found that the fluid-to-gel phase transition temperature of the bilayer dropped below the normal value with increased ionic imbalances. Our results show that a high ionic imbalance can substantially alter the essential properties of the bilayer, making the bilayer more fluid like, or conversely, depolarization of a cell could in principle lead to membrane stiffening. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Solvophilic and solvophobic surfaces and non-Coulombic surface interactions in charge regulating electric double layers

NASA Astrophysics Data System (ADS)

Vangara, R.; van Swol, F.; Petsev, D. N.

2018-01-01

The properties of electric double layers are governed by the interface between the substrate and the adjacent electrolyte solution. This interface is involved in chemical, Coulombic, and non-Coulombic (e.g., van der Waals or Lennard-Jones) interactions with all components of the fluid phase. We present a detailed study of these interactions using a classical density functional approach. A particular focus is placed on the non-Coulombic interactions and their effect on the surface chemistry and charge regulation. The solution structure near the charged interface is also analyzed and used to offer a thorough interpretation of established concepts such as the Stern and diffuse ionic layers.

Fluid Characteristics and Evolution of Chelungpu fault of Taiwan

NASA Astrophysics Data System (ADS)

Song, S. R.

2017-12-01

We analyzed geochemical characteristics, such as hydrogen and oxygen isotopes, and ionic concentrations, of fluid samples retrieved from various depth along boreholes of the Hole A and Hole B of Taiwan Chelungpu fault Drilling Project(TCDP) to trace the fluid sources. The results show that the source of fluid in the Hole B is mainly the tap water, while there are two probable sources in the Hole A owing to the abrupt shift of ionic concentrations at the depth of 200-300 m. The shallower fluid might be from the leakage above the depth of 300 m and is characteristic of lower ionic concentrations and the isotopic ratios are close to those of adjacent river water. However, the deeper fluid should be the thermal water from Kueichulin formation because of high ionic concentrations, especially HCO3-, and higher oxygen isotope, which suggests higher temperature and more isotope exchange. Two sources of fluid of the Hole A are representative of the fluid systems in the hanging wall and foot wall respectively. The characteristics of fluids in the Hole A imply that the fault zone serves as a barrier in the inter-seismic period, resulting in distinctly different fluid between the Hanging wall and the foot wall. The frequent occurrence and the distribution of calcite veins provide the evidence of the upwelling of HCO3-rich fluid of Kueichulin formation and indicate that the fault served as fluid conduit during faulting and allowed the fluid flow across the fault zone to precipitate calcite veins in fractures of the hanging wall. Thus, we can deduce the mechanism of local groundwater flow during different stages of fault development by evidences such as calcite veins distribution, regional groundwater geology, and fluids characteristics in boreholes of the Hole-A and Hole B. During inter-seismic period, groundwater flows below and above the fault zone are separated by the impermeable fault gouge layer. In co-seismic time, faulting breaks the gouge layer, providing openings that let the over-pressured thermal water which contained high concentration of bicarbonate ion to surge up. After co-seismic period, the gouge layer is sealed again, residual thermal water which contained high concentration of bicarbonate ion in the hanging wall gradually precipitated calcite in fractures and the closer precipitation took place, the more calcite veins.

Thermoelectricity in Heterogeneous Nanofluidic Channels.

PubMed

Li, Long; Wang, Qinggong

2018-05-01

Ionic fluids are essential to energy conversion, water desalination, drug delivery, and lab-on-a-chip devices. Ionic transport in nanoscale confinements and complex physical fields still remain elusive. Here, a nanofluidic system is developed using nanochannels of heterogeneous surface properties to investigate transport properties of ions under different temperatures. Steady ionic currents are observed under symmetric temperature gradients, which is equivalent to generating electricity using waste heat (e.g., electronic chips and solar panels). The currents increase linearly with temperature gradient and nonlinearly with channel size. Contributions to ion motion from temperatures and channel properties are evaluated for this phenomenon. The findings provide insights into the study of confined ionic fluids in multiphysical fields, and suggest applications in thermal energy conversion, temperature sensors, and chip-level thermal management. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Salt, chloride, bleach, and innate host defense

PubMed Central

Wang, Guoshun; Nauseef, William M.

2015-01-01

Salt provides 2 life-essential elements: sodium and chlorine. Chloride, the ionic form of chlorine, derived exclusively from dietary absorption and constituting the most abundant anion in the human body, plays critical roles in many vital physiologic functions, from fluid retention and secretion to osmotic maintenance and pH balance. However, an often overlooked role of chloride is its function in innate host defense against infection. Chloride serves as a substrate for the generation of the potent microbicide chlorine bleach by stimulated neutrophils and also contributes to regulation of ionic homeostasis for optimal antimicrobial activity within phagosomes. An inadequate supply of chloride to phagocytes and their phagosomes, such as in CF disease and other chloride channel disorders, severely compromises host defense against infection. We provide an overview of the roles that chloride plays in normal innate immunity, highlighting specific links between defective chloride channel function and failures in host defense. PMID:26048979

Salt, chloride, bleach, and innate host defense.

PubMed

Wang, Guoshun; Nauseef, William M

2015-08-01

Salt provides 2 life-essential elements: sodium and chlorine. Chloride, the ionic form of chlorine, derived exclusively from dietary absorption and constituting the most abundant anion in the human body, plays critical roles in many vital physiologic functions, from fluid retention and secretion to osmotic maintenance and pH balance. However, an often overlooked role of chloride is its function in innate host defense against infection. Chloride serves as a substrate for the generation of the potent microbicide chlorine bleach by stimulated neutrophils and also contributes to regulation of ionic homeostasis for optimal antimicrobial activity within phagosomes. An inadequate supply of chloride to phagocytes and their phagosomes, such as in CF disease and other chloride channel disorders, severely compromises host defense against infection. We provide an overview of the roles that chloride plays in normal innate immunity, highlighting specific links between defective chloride channel function and failures in host defense. © Society for Leukocyte Biology.

Inorganic nanotubes and electro-fluidic devices fabricated therefrom

DOEpatents

Yang, Peidong [Kensington, CA; Majumdar, Arunava [Orinda, CA; Fan, Rong [Pasadena, CA; Karnik, Rohit [Cambridge, MA

2011-03-01

Nanofluidic devices incorporating inorganic nanotubes fluidly coupled to channels or nanopores for supplying a fluid containing chemical or bio-chemical species are described. In one aspect, two channels are fluidly interconnected with a nanotube. Electrodes on opposing sides of the nanotube establish electrical contact with the fluid therein. A bias current is passed between the electrodes through the fluid, and current changes are detected to ascertain the passage of select molecules, such as DNA, through the nanotube. In another aspect, a gate electrode is located proximal the nanotube between the two electrodes thus forming a nanofluidic transistor. The voltage applied to the gate controls the passage of ionic species through the nanotube selected as either or both ionic polarities. In either of these aspects the nanotube can be modified, or functionalized, to control the selectivity of detection or passage.

Surface deformation and shear flow in ligand mediated cell adhesion.

PubMed

Sircar, Sarthok; Roberts, Anthony J

2016-10-01

We present a unified, multiscale model to study the attachment/detachment dynamics of two deforming, charged, near spherical cells, coated with binding ligands and subject to a slow, homogeneous shear flow in a viscous, ionic fluid medium. The binding ligands on the surface of the cells experience both attractive and repulsive forces in an ionic medium and exhibit finite resistance to rotation via bond tilting. The microscale drag forces and couples describing the fluid flow inside the small separation gap between the cells, are calculated using a combination of methods in lubrication theory and previously published numerical results. For a selected range of material and fluid parameters, a hysteretic transition of the sticking probability curves (i.e., the function [Formula: see text]) between the adhesion phase (when [Formula: see text]) and the fragmentation phase (when [Formula: see text]) is attributed to a nonlinear relation between the total nanoscale binding forces and the separation gap between the cells. We show that adhesion is favoured in highly ionic fluids, increased deformability of the cells, elastic binders and a higher fluid shear rate (until a critical threshold value of shear rate is reached). Within a selected range of critical shear rates, the continuation of the limit points (i.e., the turning points where the slope of [Formula: see text] changes sign) predict a bistable region, indicating an abrupt switching between the adhesion and the fragmentation regimes. Although, bistability in the adhesion-fragmentation phase diagram of two deformable, charged cells immersed in an ionic aqueous environment has been identified by some in vitro experiments, but until now, has not been quantified theoretically.

Preparation of curcumin nanoparticle by using reinforcement ionic gelation technique

NASA Astrophysics Data System (ADS)

Suryani, Halid, Nur Hatidjah Awaliyah; Akib, Nur Illiyyin; Rahmanpiu, Mutmainnah, Nina

2017-05-01

Curcumin, a polyphenolic compound present in curcuma longa has a wide range of activities including anti-inflammatory properties. The potency of curcumin is limited by its poor oral bioavailability because of its poor solubility in aqueous. Various methods have been tried to solve the problem including its encapsulation into nanoparticle. The aim of this study is to develop curcumin nanoparticle by using reinforcement ionic gelation technique and to evaluate the stability of curcumin nanoparticles in gastrointestinal fluid. Curcumin nanoparticles were prepared by using reinforcement ionic gelation technique with different concentrations of chitosan, trypolyphosphate, natrium alginate and calcium chloride. Curcumin nanoparticles were then characterized including particle size and zeta potential by using particle size analyzer and morphology using a transmission electron microscope, entrapment efficiency using UV-Vis Spectrophotometer and chemical structure analysis by Infra Red Spectrophotometer (FTIR). Furthermore, the stability of curcumin nanoparticles were evaluated on artificial gastric fluid and artificial intestinal fluids by measuring the amount of curcumin released in the medium at a time interval. The result revealed that curcumin nanoparticles can be prepared by reinforcement ionic gelation technique, the entrapment efficiency of curcumin nanoparticles were from 86.08 to 91.41%. The average of particle size was 272.9 nm and zeta potential was 12.05 mV. The morphology examination showed that the curcumin nanoparticles have spherical shape. The stability evaluation of curcumin nanoparticles showed that the nanoparticles were stable on artificial gastric fluid and artificial intestinal fluid. This result indicates that curcumin nanoparticles have the potential to be developed for oral delivery.

Feasibility of ion-pair/supercritical fluid extraction of an ionic compound--pseudoephedrine hydrochloride.

PubMed

Eckard, P R; Taylor, L T

1997-02-01

The supercritical fluid extraction (SFE) of an ionic compound, pseudoephedrine hydrochloride, from a spiked-sand surface was successfully demonstrated. The effect of carbon dioxide density (CO2), supercritical fluid composition (pure vs. methanol modified), and the addition of a commonly used reversed-phase liquid chromatographic ion-pairing reagent, 1-heptanesulfonic acid, sodium salt, on extraction efficiency was examined. The extraction recoveries of pseudoephedrine hydrochloride with the addition of the ion-pairing reagent from a spiked-sand surface were shown to be statistically greater than the extraction recoveries without the ion-pairing reagent with both pure and methanol-modified carbon dioxide.

Ionic Liquids in HPLC and CE: A Hope for Future.

PubMed

Ali, Imran; Suhail, Mohd; Sanagi, Mohd Marsin; Aboul-Enein, Hassan Y

2017-07-04

The ionic liquids (ILs) are salts with melting points below 100°C. These are called as ionic fluids, ionic melts, liquid electrolytes, fused salts, liquid salts, ionic glasses, designer solvents, green solvents and solvents of the future. These have a wide range of applications, including medical, pharmaceutical and chemical sciences. Nowadays, their use is increasing greatly in separation science, especially in chromatography and capillary electrophoresis due to their remarkable properties. The present article describes the importance of ILs in high-performance liquid chromatography and capillary electrophoresis. Efforts were also made to highlight the future expectations of ILs.

The effect of water deprivation on the tonicity responsive enhancer binding protein (TonEBP) and TonEBP-regulated genes in the kidney of the Spinifex hopping mouse, Notomys alexis.

PubMed

Bartolo, Ray C; Donald, John A

2008-03-01

In desert rodents, the production of concentrated urine is essential for survival in xeric environments in order to conserve water. Reabsorption of water in the kidney is dependent on large osmotic gradients in the renal medulla. This causes the renal cells to be bathed in a hypertonic extracellular fluid that can compromise cellular function. In response to hypertonicity, kidney cells accumulate compatible, non-ionic osmolytes that lower the ionic strength within the cells to isotonic levels by replacing intracellular ionic electrolytes. The tonicity-responsive enhancer binding protein (TonEBP) is a transcription factor that regulates the expression of genes that encode proteins that catalyse the accumulation of compatible osmolytes. We investigated the expression of TonEBP mRNA and protein and compatible osmolyte genes in the Spinifex hopping mouse, Notomys alexis, an Australian desert rodent that produces a highly concentrated urine. TonEBP mRNA expression was unchanged after 3 days of water deprivation but was significantly increased after 7 and 14 days of water deprivation. Immunohistochemistry showed that during water deprivation TonEBP had translocated from the cytoplasm into the nucleus of cells in the renal medulla and papilla. In addition, 3, 7 and 14 days of water deprivation caused a significant increase in aldose reductase (AR), myo-inositol (SMIT), betaine/GABA (BGT-1) and taurine (TauT) transporter mRNA expression, which is indicative of an increase in TonEBP activity. In desert rodents, TonEBP regulation of gene transcription is probably an important mechanism to protect renal cells in the face of the large corticomedullary gradient that is required to concentrate urine and conserve water.

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

High bulk modulus of ionic liquid and effects on performance of hydraulic system.

PubMed

Kambic, Milan; Kalb, Roland; Tasner, Tadej; Lovrec, Darko

2014-01-01

Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication), and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus), compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systems' dynamic responses.

Recent Development in Chemical Depolymerization of Lignin: A Review

DOE PAGES

Wang, Hai; Tucker, Melvin; Ji, Yun

2013-01-01

This article reviewed recent development of chemical depolymerization of lignins. There were five types of treatment discussed, including base-catalyzed, acid-catalyzed, metallic catalyzed, ionic liquids-assisted, and supercritical fluids-assisted lignin depolymerizations. The methods employed in this research were described, and the important results were marked. Generally, base-catalyzed and acid-catalyzed methods were straightforward, but the selectivity was low. The severe reaction conditions (high pressure, high temperature, and extreme pH) resulted in requirement of specially designed reactors, which led to high costs of facility and handling. Ionic liquids, and supercritical fluids-assisted lignin depolymerizations had high selectivity, but the high costs of ionic liquids recyclingmore » and supercritical fluid facility limited their applications on commercial scale biomass treatment. Metallic catalyzed depolymerization had great advantages because of its high selectivity to certain monomeric compounds and much milder reaction condition than base-catalyzed or acid-catalyzed depolymerizations. It would be a great contribution to lignin conversion if appropriate catalysts were synthesized.« less

Calcium-calmodulin does not alter the anion permeability of the mouse TMEM16A calcium-activated chloride channel

PubMed Central

Yu, Yawei; Kuan, Ai-Seon

2014-01-01

The transmembrane protein TMEM16A forms a Ca2+-activated Cl− channel that is permeable to many anions, including SCN−, I−, Br−, Cl−, and HCO3−, and has been implicated in various physiological functions. Indeed, controlling anion permeation through the TMEM16A channel pore may be critical in regulating the pH of exocrine fluids such as the pancreatic juice. The anion permeability of the TMEM16A channel pore has recently been reported to be modulated by Ca2+-calmodulin (CaCaM), such that the pore of the CaCaM-bound channel shows a reduced ability to discriminate between anions as measured by a shift of the reversal potential under bi-ionic conditions. Here, using a mouse TMEM16A clone that contains the two previously identified putative CaM-binding motifs, we were unable to demonstrate such CaCaM-dependent changes in the bi-ionic potential. We confirmed the activity of CaCaM used in our study by showing CaCaM modulation of the olfactory cyclic nucleotide–gated channel. We suspect that the different bi-ionic potentials that were obtained previously from whole-cell recordings in low and high intracellular [Ca2+] may result from different degrees of bi-ionic potential shift secondary to a series resistance problem, an ion accumulation effect, or both. PMID:24981232

Coulomb interactions in charged fluids.

PubMed

Vernizzi, Graziano; Guerrero-García, Guillermo Iván; de la Cruz, Monica Olvera

2011-07-01

The use of Ewald summation schemes for calculating long-range Coulomb interactions, originally applied to ionic crystalline solids, is a very common practice in molecular simulations of charged fluids at present. Such a choice imposes an artificial periodicity which is generally absent in the liquid state. In this paper we propose a simple analytical O(N(2)) method which is based on Gauss's law for computing exactly the Coulomb interaction between charged particles in a simulation box, when it is averaged over all possible orientations of a surrounding infinite lattice. This method mitigates the periodicity typical of crystalline systems and it is suitable for numerical studies of ionic liquids, charged molecular fluids, and colloidal systems with Monte Carlo and molecular dynamics simulations.

Ionic protein-lipid interaction at the plasma membrane: what can the charge do?

PubMed

Li, Lunyi; Shi, Xiaoshan; Guo, Xingdong; Li, Hua; Xu, Chenqi

2014-03-01

Phospholipids are the major components of cell membranes, but they have functional roles beyond forming lipid bilayers. In particular, acidic phospholipids form microdomains in the plasma membrane and can ionically interact with proteins via polybasic sequences, which can have functional consequences for the protein. The list of proteins regulated by ionic protein-lipid interaction has been quickly expanding, and now includes membrane proteins, cytoplasmic soluble proteins, and viral proteins. Here we review how acidic phospholipids in the plasma membrane regulate protein structure and function via ionic interactions, and how Ca(2+) regulates ionic protein-lipid interactions via direct and indirect mechanisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ionic liquids in chemical engineering.

PubMed

Werner, Sebastian; Haumann, Marco; Wasserscheid, Peter

2010-01-01

The development of engineering applications with ionic liquids stretches back to the mid-1990s when the first examples of continuous catalytic processes using ionic liquids and the first studies of ionic liquid-based extractions were published. Ever since, the use of ionic liquids has seen tremendous progress in many fields of chemistry and engineering, and the first commercial applications have been reported. The main driver for ionic liquid engineering applications is to make practical use of their unique property profiles, which are the result of a complex interplay of coulombic, hydrogen bonding and van der Waals interactions. Remarkably, many ionic liquid properties can be tuned in a wide range by structural modifications at their cation and anion. This review highlights specific examples of ionic liquid applications in catalysis and in separation technologies. Additionally, the application of ionic liquids as working fluids in process machines is introduced.

Assessing the influence of media composition and ionic strength on drug release from commercial immediate-release and enteric-coated aspirin tablets.

PubMed

Karkossa, Frank; Klein, Sandra

2017-10-01

The objective of this test series was to elucidate the importance of selecting the right media composition for a biopredictive in-vitro dissolution screening of enteric-coated dosage forms. Drug release from immediate-release (IR) and enteric-coated (EC) aspirin formulations was assessed in phosphate-based and bicarbonate-based media with different pH, electrolyte composition and ionic strength. Drug release from aspirin IR tablets was unaffected by media composition. In contrast, drug release from EC aspirin formulations was affected by buffer species and ionic strength. In all media, drug release increased with increasing ionic strength, but in bicarbonate-based buffers was delayed when compared with that in phosphate-based buffers. Interestingly, the cation species in the dissolution medium had also a clear impact on drug release. Drug release profiles obtained in Blank CarbSIF, a new medium simulating pH and average ionic composition of small intestinal fluid, were different from those obtained in all other buffer compositions studied. Results from this study in which the impact of various media parameters on drug release of EC aspirin formulations was systematically screened clearly show that when developing predictive dissolution tests, it is important to simulate the ionic composition of intraluminal fluids as closely as possible. © 2017 Royal Pharmaceutical Society.

MDCK cells are capable of water secretion and reabsorption in response to changes in the ionic environment.

PubMed

Capra, Janne P; Eskelinen, Sinikka M

2017-01-01

A prerequisite for tissue electrolyte homeostasis is highly regulated ion and water transport through kidney or intestinal epithelia. In the present work, we monitored changes in the cell and luminal volumes of type II Madin-Darby canine kidney (MDCK) cells grown in a 3D environment in response to drugs, or to changes in the composition of the basal extracellular fluid. Using fluorescent markers and high-resolution spinning disc confocal microscopy, we could show that lack of sodium and potassium ions in the basal fluid (tetramethylammonium chloride (TMACl) buffer) induces a rapid increase in the cell and luminal volumes. This transepithelial water flow could be regulated by inhibitors and agonists of chloride channels. Hence, the driving force for the transepithelial water flow is chloride secretion, stimulated by hyperpolarization. Chloride ion depletion of the basal fluid (using sodium gluconate buffer) induces a strong reduction in the lumen size, indicating reabsorption of water from the lumen to the basal side. Lumen size also decreased following depolarization of the cell interior by rendering the membrane permeable to potassium. Hence, MDCK cells are capable of both absorption and secretion of chloride ions and water; negative potential within the lumen supports secretion, while depolarizing conditions promote reabsorption.

Ion transport in a pH-regulated nanopore.

PubMed

Yeh, Li-Hsien; Zhang, Mingkan; Qian, Shizhi

2013-08-06

Fundamental understanding of ion transport phenomena in nanopores is crucial for designing the next-generation nanofluidic devices. Due to surface reactions of dissociable functional groups on the nanopore wall, the surface charge density highly depends upon the proton concentration on the nanopore wall, which in turn affects the electrokinetic transport of ions, fluid, and particles within the nanopore. Electrokinetic ion transport in a pH-regulated nanopore, taking into account both multiple ionic species and charge regulation on the nanopore wall, is theoretically investigated for the first time. The model is verified by the experimental data of nanopore conductance available in the literature. The results demonstrate that the spatial distribution of the surface charge density at the nanopore wall and the resulting ion transport phenomena, such as ion concentration polarization (ICP), ion selectivity, and conductance, are significantly affected by the background solution properties, such as the pH and salt concentration.

Experimental Studies of Hydrocarbon Flame Phenomena: Enabling Combustion Control

DTIC Science & Technology

2016-07-30

early discussions on the “ionic or electric wind ’ was a term used to describe a fluid flow driven only from the difference in electric potentials at two...locations, Chattock [2] and Robinson [11]. 4 To produce ionic wind , a high potential combined with a favorable electrode geometry, forms an...the secondary electrode. Beyond the formation of the ionic wind , it has been observed that high potentials in ambient air can produce ozone

Modeling electrical double-layer effects for microfluidic impedance spectroscopy from 100 kHz to 110 GHz.

PubMed

Little, Charles A E; Orloff, Nathan D; Hanemann, Isaac E; Long, Christian J; Bright, Victor M; Booth, James C

2017-07-25

Broadband microfluidic-based impedance spectroscopy can be used to characterize complex fluids, with applications in medical diagnostics and in chemical and pharmacological manufacturing. Many relevant fluids are ionic; during impedance measurements ions migrate to the electrodes, forming an electrical double-layer. Effects from the electrical double-layer dominate over, and reduce sensitivity to, the intrinsic impedance of the fluid below a characteristic frequency. Here we use calibrated measurements of saline solution in microfluidic coplanar waveguide devices at frequencies between 100 kHz and 110 GHz to directly measure the double-layer admittance for solutions of varying ionic conductivity. We successfully model the double-layer admittance using a combination of a Cole-Cole response with a constant phase element contribution. Our analysis yields a double-layer relaxation time that decreases linearly with solution conductivity, and allows for double-layer effects to be separated from the intrinsic fluid response and quantified for a wide range of conducting fluids.

A story told by a single nanoparticle in the body fluid: demonstration of dissolution-reprecipitation of nanocrystals in a biological system.

PubMed

Wu, Cheng-Yeu; Young, David; Martel, Jan; Young, John D

2015-01-01

Analysis of the chemical composition of mineral particles found in the body is critical to understand the formation and effects of these entities in vivo. Yet, the possibility that biological fluids may modulate particle composition over time has not been examined. Materials & methods: Mineralo-organic nanoparticles similar to the ones that spontaneously form in human tissues were analyzed using electron microscopy, spectroscopy and proteomic analyses.   We show that the mineralo-organic nanoparticles assimilate various ions and minerals during incubation in ionic solutions simulating body fluids. The particles undergo dissolution-reprecipitation reactions that affect the final protein composition of the particles. The reactions occurring at the mineral-water interface therefore modulate the ionic and organic composition of mineral nanoparticles formed in biological fluids, producing changes that may alter the effects of mineral particles and stones in vivo.

NMR imaging of chitosan and carboxymethyl starch tablets: swelling and hydration of the polyelectrolyte complex.

PubMed

Wang, Y J; Assaad, E; Ispas-Szabo, P; Mateescu, M A; Zhu, X X

2011-10-31

The hydration and swelling properties of the tablets made of chitosan, carboxymethyl starch, and a polyelectrolyte complex of these two polysaccharides have been studied by NMR imaging. We studied the effect of pH and ionic strength on the swelling of the tablets and on the diffusion of fluid into the tablets in water and simulated physiological fluids. The pH value of the fluids exerts a more significant effect than their ionic strengths on the swelling of the tablets. The tablets are compared also with those made of cross-linked high amylose starch. The formation of complex helps to keep the integrity of the tablets in various media and render a slow and restricted swelling similar to that of the tablets of the cross-linked high amylase starch, which is significantly lower than the swelling of chitosan and of carboxymethyl starch. The capacities to modulate the release rate of drugs in different media are discussed by comparing the matrices and evaluating the preparation process of the complex. A sustained release of less soluble drugs such as aspirin in gastrointestinal fluids can be provided by the complex, due to the ionic interaction and hydrogen bonding between the drug and the biopolymer complex. Copyright © 2011 Elsevier B.V. All rights reserved.

Is the boundary layer of an ionic liquid equally lubricating at higher temperature?

PubMed

Hjalmarsson, Nicklas; Atkin, Rob; Rutland, Mark W

2016-04-07

Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.

Ionic fluids with r-6 pair interactions have power-law electrostatic screening

NASA Astrophysics Data System (ADS)

Kjellander, Roland; Forsberg, Björn

2005-06-01

The decay behaviour of radial distribution functions for large distances r is investigated for classical Coulomb fluids where the ions interact with an r-6 potential (e.g. a dispersion interaction) in addition to the Coulombic and the short-range repulsive potentials (e.g. a hard core). The pair distributions and the density-density (NN), charge-density (QN) and charge-charge (QQ) correlation functions are investigated analytically and by Monte Carlo simulations. It is found that the NN correlation function ultimately decays like r-6 for large r, just as it does for fluids of electroneutral particles interacting with an r-6 potential. The prefactor is proportional to the squared compressibility in both cases. The QN correlations decay in general like r-8 and the QQ correlations like r-10 in the ionic fluid. The average charge density around an ion decays generally like r-8 and the average electrostatic potential like r-6. This behaviour is in stark contrast to the decay behaviour for classical Coulomb fluids in the absence of the r-6 potential, where all these functions decay exponentially for large r. The power-law decays are, however, the same as for quantum Coulomb fluids. This indicates that the inclusion of the dispersion interaction as an effective r-6 interaction potential in classical systems yields the same decay behaviour for the pair correlations as in quantum ionic systems. An exceptional case is the completely symmetric binary electrolyte for which only the NN correlation has a power-law decay but not the QQ correlations. These features are shown by an analysis of the bridge function.

Yield stress and scaling of polyelectrolyte multilayer modified suspensions: effect of polyelectrolyte conformation during multilayer assembly.

PubMed

Hess, Andreas; Aksel, Nuri

2013-09-10

The yield stress of polyelectrolyte multilayer modified suspensions exhibits a surprising dependence on the polyelectrolyte conformation of multilayer films. The rheological data scale onto a universal master curve for each polyelectrolyte conformation as the particle volume fraction, φ, and the ionic strength of the background fluid, I, are varied. It is shown that rough films with highly coiled, brushy polyelectrolytes significantly enhance the yield stress. Moreover, via the ionic strength I of the background fluid, the dynamic yield stress of brushy polyelectrolyte multilayers can be finely adjusted over 2 decades.

Ion pairing and phase behaviour of an asymmetric restricted primitive model of ionic liquids

NASA Astrophysics Data System (ADS)

Lu, Hongduo; Li, Bin; Nordholm, Sture; Woodward, Clifford E.; Forsman, Jan

2016-12-01

An asymmetric restricted primitive model (ARPM) of electrolytes is proposed as a simple three parameter (charge q, diameter d, and charge displacement b) model of ionic liquids and solutions. Charge displacement allows electrostatic and steric interactions to operate between different centres, so that orientational correlations arise in ion-ion interactions. In this way the ionic system may have partly the character of a simple ionic fluid/solid and of a polar fluid formed from ion pairs. The present exploration of the system focuses on the ion pair formation mechanism, the relative concentration of paired and free ions and the consequences for the cohesive energy, and the tendency to form fluid or solid phase. In contrast to studies of similar (though not identical) models in the past, we focus on behaviours at room temperature. By MC and MD simulations of such systems composed of monovalent ions of hard-sphere (or essentially hard-sphere) diameter equal to 5 Å and a charge displacement ranging from 0 to 2 Å from the hard-sphere origin, we find that ion pairing dominates for b larger than 1 Å. When b exceeds about 1.5 Å, the system is essentially a liquid of dipolar ion pairs with a small presence of free ions. We also investigate dielectric behaviours of corresponding liquids, composed of purely dipolar species. Many basic features of ionic liquids appear to be remarkably consistent with those of our ARPM at ambient conditions, when b is around 1 Å. However, the rate of self-diffusion and, to a lesser extent, conductivity is overestimated, presumably due to the simple spherical shape of our ions in the ARPM. The relative simplicity of our ARPM in relation to the rich variety of new mechanisms and properties it introduces, and to the numerical simplicity of its exploration by theory or simulation, makes it an essential step on the way towards representation of the full complexity of ionic liquids.

Ion pairing and phase behaviour of an asymmetric restricted primitive model of ionic liquids.

PubMed

Lu, Hongduo; Li, Bin; Nordholm, Sture; Woodward, Clifford E; Forsman, Jan

2016-12-21

An asymmetric restricted primitive model (ARPM) of electrolytes is proposed as a simple three parameter (charge q, diameter d, and charge displacement b) model of ionic liquids and solutions. Charge displacement allows electrostatic and steric interactions to operate between different centres, so that orientational correlations arise in ion-ion interactions. In this way the ionic system may have partly the character of a simple ionic fluid/solid and of a polar fluid formed from ion pairs. The present exploration of the system focuses on the ion pair formation mechanism, the relative concentration of paired and free ions and the consequences for the cohesive energy, and the tendency to form fluid or solid phase. In contrast to studies of similar (though not identical) models in the past, we focus on behaviours at room temperature. By MC and MD simulations of such systems composed of monovalent ions of hard-sphere (or essentially hard-sphere) diameter equal to 5 Å and a charge displacement ranging from 0 to 2 Å from the hard-sphere origin, we find that ion pairing dominates for b larger than 1 Å. When b exceeds about 1.5 Å, the system is essentially a liquid of dipolar ion pairs with a small presence of free ions. We also investigate dielectric behaviours of corresponding liquids, composed of purely dipolar species. Many basic features of ionic liquids appear to be remarkably consistent with those of our ARPM at ambient conditions, when b is around 1 Å. However, the rate of self-diffusion and, to a lesser extent, conductivity is overestimated, presumably due to the simple spherical shape of our ions in the ARPM. The relative simplicity of our ARPM in relation to the rich variety of new mechanisms and properties it introduces, and to the numerical simplicity of its exploration by theory or simulation, makes it an essential step on the way towards representation of the full complexity of ionic liquids.

Notre Dame Geothermal Ionic Liquids Research: Ionic Liquids for Utilization of Geothermal Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennecke, Joan F.

The goal of this project was to develop ionic liquids for two geothermal energy related applications. The first goal was to design ionic liquids as high temperature heat transfer fluids. We identified appropriate compounds based on both experiments and molecular simulations. We synthesized the new ILs, and measured their thermal stability, measured storage density, viscosity, and thermal conductivity. We found that the most promising compounds for this application are aminopyridinium bis(trifluoromethylsulfonyl)imide based ILs. We also performed some measurements of thermal stability of IL mixtures and used molecular simulations to better understand the thermal conductivity of nanofluids (i.e., mixtures of ILsmore » and nanoparticles). We found that the mixtures do not follow ideal mixture theories and that the addition of nanoparticles to ILs may well have a beneficial influence on the thermal and transport properties of IL-based heat transfer fluids. The second goal was to use ionic liquids in geothermally driven absorption refrigeration systems. We performed copious thermodynamic measurements and modeling of ionic liquid/water systems, including modeling of the absorption refrigeration systems and the resulting coefficients of performance. We explored some IL/organic solvent mixtures as candidates for this application, both with experimentation and molecular simulations. We found that the COPs of all of the IL/water systems were higher than the conventional system – LiBr/H2O. Thus, IL/water systems appear very attractive for absorption refrigeration applications.« less

Implementation of perturbed-chain statistical associating fluid theory (PC-SAFT), generalized (G)SAFT+cubic, and cubic-plus-association (CPA) for modeling thermophysical properties of selected 1-alkyl-3-methylimidazolium ionic liquids in a wide pressure range.

PubMed

Polishuk, Ilya

2013-03-14

This study is the first comparative investigation of predicting the isochoric and the isobaric heat capacities, the isothermal and the isentropic compressibilities, the isobaric thermal expansibilities, the thermal pressure coefficients, and the sound velocities of ionic liquids by statistical associating fluid theory (SAFT) equation of state (EoS) models and cubic-plus-association (CPA). It is demonstrated that, taking into account the high uncertainty of the literature data (excluding sound velocities), the generalized for heavy compounds version of SAFT+Cubic (GSAFT+Cubic) appears as a robust estimator of the auxiliary thermodynamic properties under consideration. In the case of the ionic liquids the performance of PC-SAFT seems to be less accurate in comparison to ordinary compounds. In particular, PC-SAFT substantially overestimates heat capacities and underestimates the temperature and pressure dependencies of sound velocities and compressibilities. An undesired phenomenon of predicting high fictitious critical temperatures of ionic liquids by PC-SAFT should be noticed as well. CPA is the less accurate estimator of the liquid phase properties, but it is advantageous in modeling vapor pressures and vaporization enthalpies of ionic liquids. At the same time, the preliminary results indicate that the inaccuracies in predicting the deep vacuum vapor pressures of ionic liquids do not influence modeling of phase equilibria in their mixtures at much higher pressures.

Structural, thermodynamic, and electrical properties of polar fluids and ionic solutions on a hypersphere: Results of simulations

NASA Astrophysics Data System (ADS)

Caillol, J. M.; Levesque, D.

1992-01-01

The reliability and the efficiency of a new method suitable for the simulations of dielectric fluids and ionic solutions is established by numerical computations. The efficiency depends on the use of a simulation cell which is the surface of a four-dimensional sphere. The reliability originates from a charge-charge potential solution of the Poisson equation in this confining volume. The computation time, for systems of a few hundred molecules, is reduced by a factor of 2 or 3 compared to this of a simulation performed in a cubic volume with periodic boundary conditions and the Ewald charge-charge potential.

Ionic basis of membrane potentials of epithelial cells in rat small intestine

PubMed Central

Barry, R. J. C.; Eggenton, Jacqueline

1972-01-01

1. Potentials across the mucosal and serosal membranes of the epithelial cells of rat jejunum together with transmural potentials were recorded using everted sac preparations. 2. Ionic changes in either mucosal or serosal fluids affect mucosal or serosal membrane potentials respectively with comparable changes in the transmural potential. The contralateral membrane potential is relatively unaffected. 3. Replacement of mucosal sodium chloride by potassium chloride or lithium chloride had little effect on potentials, but its replacement by mannitol or Tris chloride increased the negativity of the mucosal potential, giving linear relationships against log10[Na]m with slopes of 41·4 and 30·7 mV respectively for tenfold change in [Na]m. 4. At constant [Na]m, potassium or lithium increased the mucosal potential by 25·7 and 19·8 mV respectively for tenfold concentration changes. 5. Qualitatively similar changes occurred in the serosal potential when the ionic composition of the serosal fluid was varied. 6. Mucosal potential changes in response to modifications of the ionic composition of the mucosal fluid were the same in the presence and absence of galactose. 7. Sodium and potassium diffusion potentials largely determine both the mucosal and serosal membrane potentials. For the mucosal membrane, PK:PNa is 1·26:1, and is probably higher for the serosal membrane. Chloride makes no significant contribution to membrane potentials. 8. Potentials generated by the electrogenic sodium pump are superimposed on diffusion potentials across the serosal membrane. PMID:4646579

Ginzburg criterion for ionic fluids: the effect of Coulomb interactions.

PubMed

Patsahan, O

2013-08-01

The effect of the Coulomb interactions on the crossover between mean-field and Ising critical behavior in ionic fluids is studied using the Ginzburg criterion. We consider the charge-asymmetric primitive model supplemented by short-range attractive interactions in the vicinity of the gas-liquid critical point. The model without Coulomb interactions exhibiting typical Ising critical behavior is used to calibrate the Ginzburg temperature of the systems comprising electrostatic interactions. Using the collective variables method, we derive a microscopic-based effective Hamiltonian for the full model. We obtain explicit expressions for all the relevant Hamiltonian coefficients within the framework of the same approximation, i.e., the one-loop approximation. Then we consistently calculate the reduced Ginzburg temperature t(G) for both the purely Coulombic model (a restricted primitive model) and the purely nonionic model (a hard-sphere square-well model) as well as for the model parameters ranging between these two limiting cases. Contrary to the previous theoretical estimates, we obtain the reduced Ginzburg temperature for the purely Coulombic model to be about 20 times smaller than for the nonionic model. For the full model including both short-range and long-range interactions, we show that t(G) approaches the value found for the purely Coulombic model when the strength of the Coulomb interactions becomes sufficiently large. Our results suggest a key role of Coulomb interactions in the crossover behavior observed experimentally in ionic fluids as well as confirm the Ising-like criticality in the Coulomb-dominated ionic systems.

Structural, thermodynamic, and electrical properties of polar fluids and ionic solutions on a hypersphere: Theoretical aspects

NASA Astrophysics Data System (ADS)

Caillol, J. M.

1992-01-01

We generalize previous work [J. Chem. Phys. 94, 597 (1991)] on an alternative to the Ewald method for the numerical simulations of Coulomb fluids. This new method consists in using as a simulation cell the three-dimensional surface of a four-dimensional sphere, or hypersphere. Here, we consider the case of polar fluids and electrolyte solutions. We derive all the formal expressions which are needed for numerical simulations of such systems. It includes a derivation of the multipolar interactions on a hypersphere, the expansion of the pair-correlation functions on rotational invariants, the expression of the static dielectric constant of a polar liquid, the expressions of the frequency-dependent conductivity and dielectric constant of an ionic solution, and the derivation of the Stillinger-Lovett sum rules for conductive systems.

Fluid breakup in carbon nanotubes: An explanation of ultrafast ion transport

NASA Astrophysics Data System (ADS)

Gao, Xiang; Zhao, Tianshou; Li, Zhigang

2017-09-01

Ultrafast ion transport in carbon nanotubes (CNTs) has been experimentally observed, but the underlying mechanism is unknown. In this work, we investigate ion transport in CNTs through molecular dynamics (MD) simulations. It is found that the flow in CNTs undergoes a transition from the passage of a continuous liquid chain to the transport of isolated ion-water clusters as the CNT length or the external electric filed strength is increased. The breakup of the liquid chain in CNTs greatly reduces the resistance caused by the hydrogen bonds of water and significantly enhances the ionic mobility, which explains the two-order-magnitude enhancement of ionic conductance in CNTs reported in the literature. A theoretical criterion for fluid breakup is proposed, which agrees well with MD results. The fluid breakup phenomenon provides new insights into enhancing ion transport in nanoconfinements.

Ionic Liquids as Quasihydrostatic Pressure Media for Diamond Anvil Cell Experiments

NASA Astrophysics Data System (ADS)

Mayorga, Sierra; Moldowan, Kaela; Dan, Ioana; Forster, Paul; Iota, Valentin

2012-02-01

Ionic liquids (ILs) are salts in which the ions are poorly coordinated to the point where the eutectic mixture remains liquid at room temperature. In general, ILs exhibit high chemical and thermal stability, have extended liquid regions in the pressure-temperature domain, and can be easily obtained. Commercial ionic liquids are relatively inexpensive and custom ionic solutions can be easily synthesized by mixing common reactants. These properties make ionic liquids attractive candidates for high-pressure media in Diamond Anvil Cell (DAC) experiments. In this presentation we explore the use of ionic liquids as DAS quasihydrostatic pressure media for pressures up to 50 GPa. As a measure of hydrostaticity we monitor the splitting and peak-widths of the R1 andR 2 fluorescence lines from small ruby chips (Al2O3 :Cr^3+) imbedded in the pressure medium. We present results on a series of commercially available ionic fluids against standard pressure media: methanol-ethanol mixtures, silicone oil, sodium chloride (NaCl) and noble gases (Ar, Ne, He).

Beneficial reuse of fly ashes in geotechnical engineering with physicochemical and electron microscopic methods.

DOT National Transportation Integrated Search

2013-06-01

The sedimentation behavior of fine grained soil is largely dependent on its pore fluid chemistry. Physicochemical properties of the : pore fluid, such as ionic strength and pH, could greatly influence the micro structure of kaolinite which in turn in...

Criticality in charge-asymmetric hard-sphere ionic fluids.

PubMed

Aqua, Jean-Noël; Banerjee, Shubho; Fisher, Michael E

2005-10-01

Phase separation and criticality are analyzed in z:1 charge-asymmetric ionic fluids of equisized hard spheres by generalizing the Debye-Hückel approach combined with ionic association, cluster solvation by charged ions, and hard-core interactions, following lines developed by Fisher and Levin for the 1:1 case (i.e., the restricted primitive model). Explicit analytical calculations for 2:1 and 3:1 systems account for ionic association into dimers, trimers, and tetramers and subsequent multipolar cluster solvation. The reduced critical temperatures, Tc* (normalized by z), decrease with charge asymmetry, while the critical densities increase rapidly with . The results compare favorably with simulations and represent a distinct improvement over all current theories such as the mean spherical approximation, symmetric Poisson-Boltzmann theory, etc. For z not equal to 1, the interphase Galvani (or absolute electrostatic) potential difference, Deltaphi(T), between coexisting liquid and vapor phases is calculated and found to vanish as absolute value (T-Tc) beta when T-->Tc-with, since our approximations are classical, beta = (1/2). Above Tc, the compressibility maxima and so-called k-inflection loci (which aid the fast and accurate determination of the critical parameters) are found to exhibit a strong z dependence.

Kinetics of electrically and chemically induced swelling in polyelectrolyte gels

NASA Astrophysics Data System (ADS)

Grimshaw, P. E.; Nussbaum, J. H.; Grodzinsky, A. J.; Yarmush, M. L.

1990-09-01

Controlled swelling and shrinking of polyelectrolyte gels is useful for regulating the transport of solutes into, out of, and through these materials. A macroscopic continuum model is presented to predict the kinetics of swelling in polyelectrolyte gel membranes induced by augmentation of electrostatic swelling forces arising from membrane fixed charge groups. The model accounts for ionic transport within the membrane, electrodiffusion phenomena, dissociation of membrane charge groups, intramembrane fluid flow, and mechanical deformation of the membrane matrix. Model predictions are compared with measurements of chemically and electrically induced swelling and shrinking in crosslinked polymethacrylic acid (PMAA) membranes. Large, reversible changes in PMAA membrane hydration were observed after changing the bath pH or by applying an electric field to modify the intramembrane ionic environment and fixed charge density. A relatively slow swelling process and more rapid shrinking for both chemical and electrical modulation of the intramembrane pH are observed. The model indicates that retardation of membrane swelling is dominated by diffusion-limited reaction of H+ ions with membrane charge groups, and that the more rapid shrinking is limited primarily by mechanical processes.

Focus Article: Oscillatory and long-range monotonic exponential decays of electrostatic interactions in ionic liquids and other electrolytes: The significance of dielectric permittivity and renormalized charges

NASA Astrophysics Data System (ADS)

Kjellander, Roland

2018-05-01

A unified treatment of oscillatory and monotonic exponential decays of interactions in electrolytes is displayed, which highlights the role of dielectric response of the fluid in terms of renormalized (effective) dielectric permittivity and charges. An exact, but physically transparent statistical mechanical formalism is thereby used, which is presented in a systematic, pedagogical manner. Both the oscillatory and monotonic behaviors are given by an equation for the decay length of screened electrostatic interactions that is very similar to the classical expression for the Debye length. The renormalized dielectric permittivities, which have similar roles for electrolytes as the dielectric constant has for pure polar fluids, consist in general of several entities with different physical meanings. They are connected to dielectric response of the fluid on the same length scale as the decay length of the screened interactions. Only in cases where the decay length is very long, these permittivities correspond approximately to a dielectric response in the long-wavelength limit, like the dielectric constant for polar fluids. Experimentally observed long-range exponentially decaying surface forces are analyzed as well as the oscillatory forces observed for short to intermediate surface separations. Both occur in some ionic liquids and in concentrated as well as very dilute electrolyte solutions. The coexisting modes of decay are in general determined by the bulk properties of the fluid and not by the solvation of the surfaces; in the present cases, they are given by the behavior of the screened Coulomb interaction of the bulk fluid. The surface-fluid interactions influence the amplitudes and signs or phases of the different modes of the decay, but not their decay lengths and wavelengths. The similarities between some ionic liquids and very dilute electrolyte solutions as regards both the long-range monotonic and the oscillatory decays are analyzed.

Insulated Conducting Cantilevered Nanotips and Two-Chamber Recording System for High Resolution Ion Sensing AFM

PubMed Central

Meckes, Brian; Arce, Fernando Teran; Connelly, Laura S.; Lal, Ratnesh

2014-01-01

Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels. PMID:24663394

Effect of salinity on oxygen consumption in fishes: a review.

PubMed

Ern, R; Huong, D T T; Cong, N V; Bayley, M; Wang, T

2014-04-01

The effect of salinity on resting oxygen uptake was measured in the perch Perca fluviatilis and available information on oxygen uptake in teleost species at a variety of salinities was reviewed. Trans-epithelial ion transport against a concentration gradient requires energy and exposure to salinities osmotically different from the body fluids therefore imposes an energetic demand that is expected to be lowest in brackish water compared to fresh and sea water. Across species, there is no clear trend between oxygen uptake and salinity, and estimates of cost of osmotic and ionic regulation vary from a few per cent to >30% of standard metabolism. © 2014 The Fisheries Society of the British Isles.

Hormonal control of euryhalinity

USGS Publications Warehouse

Takei, Yoshio; McCormick, Stephen D.; McCormick, Stephen D.; Farrell, Anthony Peter; Brauner, Colin J.

2013-01-01

Hormones play a critical role in maintaining body fluid balance in euryhaline fishes during changes in environmental salinity. The neuroendocrine axis senses osmotic and ionic changes, then signals and coordinates tissue-specific responses to regulate water and ion fluxes. Rapid-acting hormones, e.g. angiotensins, cope with immediate challenges by controlling drinking rate and the activity of ion transporters in the gill, gut, and kidney. Slow-acting hormones, e.g. prolactin and growth hormone/insulin-like growth factor-1, reorganize the body for long-term acclimation by altering the abundance of ion transporters and through cell proliferation and differentiation of ionocytes and other osmoregulatory cells. Euryhaline species exist in all groups of fish, including cyclostomes, and cartilaginous and teleost fishes. The diverse strategies for responding to changes in salinity have led to differential regulation and tissue-specific effects of hormones. Combining traditional physiological approaches with genomic, transcriptomic, and proteomic analyses will elucidate the patterns and diversity of the endocrine control of euryhalinity.

Smolt physiology and endocrinology

USGS Publications Warehouse

McCormick, Stephen D.; McCormick, Stephen D.; Farrell, Anthony Peter; Brauner, Colin J.

2013-01-01

Hormones play a critical role in maintaining body fluid balance in euryhaline fishes during changes in environmental salinity. The neuroendocrine axis senses osmotic and ionic changes, then signals and coordinates tissue-specific responses to regulate water and ion fluxes. Rapid-acting hormones, e.g. angiotensins, cope with immediate challenges by controlling drinking rate and the activity of ion transporters in the gill, gut, and kidney. Slow-acting hormones, e.g. prolactin and growth hormone/insulin-like growth factor-1, reorganize the body for long-term acclimation by altering the abundance of ion transporters and through cell proliferation and differentiation of ionocytes and other osmoregulatory cells. Euryhaline species exist in all groups of fish, including cyclostomes, and cartilaginous and teleost fishes. The diverse strategies for responding to changes in salinity have led to differential regulation and tissue-specific effects of hormones. Combining traditional physiological approaches with genomic, transcriptomic, and proteomic analyses will elucidate the patterns and diversity of the endocrine control of euryhalinity.

A computational study on choline benzoate and choline salicylate ionic liquids in the pure state and after CO2 adsorption.

PubMed

Aparicio, Santiago; Atilhan, Mert

2012-08-02

Choline-based ionic liquids show very adequate environmental, toxicological, and economical profiles for their application in many different technological areas. We report in this work a computational study on the properties of choline benzoate and choline salicylate ionic liquids, as representatives of this family of compounds, in the pure state and after CO(2) adsorption. Quantum chemistry calculations using the density functional theory approach for ionic pairs and ions, CO(2) pairs, were carried out, and the results analyzed using natural bond orbital and atoms in a molecule approaches. Classical molecular dynamics simulations of ionic liquids were done as a function of pressure, temperature, and CO(2) concentration. Microscopic structuring and intermolecular forces are analyzed together with the dynamic behavior of the studied fluids.

Anoctamin Calcium-Activated Chloride Channels May Modulate Inhibitory Transmission in the Cerebellar Cortex

PubMed Central

Parthier, Daniel; Frings, Stephan; Möhrlen, Frank

2015-01-01

Calcium-activated chloride channels of the anoctamin (alias TMEM16) protein family fulfill critical functions in epithelial fluid transport, smooth muscle contraction and sensory signal processing. Little is known, however, about their contribution to information processing in the central nervous system. Here we examined the recent finding that a calcium-dependent chloride conductance impacts on GABAergic synaptic inhibition in Purkinje cells of the cerebellum. We asked whether anoctamin channels may underlie this chloride conductance. We identified two anoctamin channel proteins, ANO1 and ANO2, in the cerebellar cortex. ANO1 was expressed in inhibitory interneurons of the molecular layer and the granule cell layer. Both channels were expressed in Purkinje cells but, while ANO1 appeared to be retained in the cell body, ANO2 was targeted to the dendritic tree. Functional studies confirmed that ANO2 was involved in a calcium-dependent mode of ionic plasticity that reduces the efficacy of GABAergic synapses. ANO2 channels attenuated GABAergic transmission by increasing the postsynaptic chloride concentration, hence reducing the driving force for chloride influx. Our data suggest that ANO2 channels are involved in a Ca2+-dependent regulation of synaptic weight in GABAergic inhibition. Thus, in balance with the chloride extrusion mechanism via the co-transporter KCC2, ANO2 appears to regulate ionic plasticity in the cerebellum. PMID:26558388

Ionic requirements of proximal tubular sodium transport. I. Bicarbonate and chloride.

PubMed

Green, R; Giebisch, G

1975-11-01

Simultaneous perfusion of peritubular capillaries and proximal convoluted tubules was used to study the effect of varying transepithelial ionic gradients on ionic fluxes. Results show that net sodium influx and volume flux was one-third of normal when bicarbonate was absent, no chloride gradient existed, and glucose and amino acids were absent. Addition of bicarbonate to the luminal fluid did not restore the flux to normal, but peritubular bicarbonate did restore it. A chloride gradient imposed when no bicarbonate was present could only increase the fluxes slightly, but his flux was significant even after cyanide had poisoned transport. Reversing the chloride concentration gradient decreased the net sodium and volume fluxes whether bicarbonate was present or not. Glucose had no effect on fluxes, but substitution of Na by choline abolished them entirely. It is concluded that sodium is actively transported, that a chloride concentration gradient from lumen to plasma could account for up to 20% of net transport, and that peritubular bicarbonate is necessary for normal rates of sodium and fluid absorption.

Fluids of the lower crust and upper mantle: deep is different

NASA Astrophysics Data System (ADS)

Manning, C. E.

2017-12-01

Deep fluids are important for the evolution and properties of the lower crust and upper mantle in tectonically active settings. Uncertainty about their chemistry has led past workers to use upper crustal fluids as analogues. However, recent results show that fluids at >15 km differ fundamentally from shallow fluids and help explain high-pressure metasomatism and resistivity patterns. Deep fluids are comprised of four components: H2O, non-polar gases (chiefly CO2), salts (mostly alkali chlorides), and rock-derived solutes (dominated by aluminosilicates and related components). The first three generally define the solvent properties of the fluid, and models must account for observations that H2O activity may be quite low. The contrasting behavior of H2O-gas and H2O-salt mixtures yields immiscibility in the ternary system, which can lead to separation of two phases with fundamentally different chemical and transport properties. Thermodynamic modeling of equilibrium between rocks and H2O using simple ionic species known from shallow-crustal systems yields solutions possessing total dissolved solids and ionic strength that are too low to be consistent with experiments and resistivity surveys. Addition of CO2 further lowers bulk solubility and conductivity. Therefore, additional species must be present in H2O, and H2O-salt solutions likely explain much of the evidence for fluid action in high-P settings. At low salinity, H2O-rich fluids are powerful solvents for aluminosilicate rock components that are dissolved as previously unrecognized polymerized clusters. Experiments show that, near H2O-saturated melting, Al-Si polymers comprise >80% of solutes. The stability of these species facilitates critical critical mixing in rock-H2O systems. Addition of salt (e.g., NaCl) changes solubility patterns, but aluminosilicate contents remain high. Thermodynamic models indicate that the ionic strength of fluids with Xsalt = 0.05 to 0.4 and equilibrated with model crustal rocks have predicted bulk conductivities of 10-1.5 to 100 S/m at porosity of 0.001. Such fluids are thus consistent with conductivity anomalies commonly observed in the lower crust (e.g., the "G" anomaly), and are capable of the mass transfer commonly seen in metamorphic rocks exhumed from the lower crust and subduction zones.

Free energy and phase equilibria for the restricted primitive model of ionic fluids from Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Orkoulas, Gerassimos; Panagiotopoulos, Athanassios Z.

1994-07-01

In this work, we investigate the liquid-vapor phase transition of the restricted primitive model of ionic fluids. We show that at the low temperatures where the phase transition occurs, the system cannot be studied by conventional molecular simulation methods because convergence to equilibrium is slow. To accelerate convergence, we propose cluster Monte Carlo moves capable of moving more than one particle at a time. We then address the issue of charged particle transfers in grand canonical and Gibbs ensemble Monte Carlo simulations, for which we propose a biased particle insertion/destruction scheme capable of sampling short interparticle distances. We compute the chemical potential for the restricted primitive model as a function of temperature and density from grand canonical Monte Carlo simulations and the phase envelope from Gibbs Monte Carlo simulations. Our calculated phase coexistence curve is in agreement with recent results of Caillol obtained on the four-dimensional hypersphere and our own earlier Gibbs ensemble simulations with single-ion transfers, with the exception of the critical temperature, which is lower in the current calculations. Our best estimates for the critical parameters are T*c=0.053, ρ*c=0.025. We conclude with possible future applications of the biased techniques developed here for phase equilibrium calculations for ionic fluids.

Hydraulic pressures generated in magnetic ionic liquids by paramagnetic fluid/air interfaces inside of uniform tangential magnetic fields.

PubMed

Scovazzo, Paul; Portugal, Carla A M; Rosatella, Andreia A; Afonso, Carlos A M; Crespo, João G

2014-08-15

Magnetic Ionic Liquid (MILs), novel magnetic molecules that form "pure magnetic liquids," will follow the Ferrohydrodynamic Bernoulli Relationship. Based on recent literature, the modeling of this fluid system is an open issue and potentially controversial. We imposed uniform magnetic fields parallel to MIL/air interfaces where the capillary forces were negligible, the Quincke Problem. The size and location of the bulk fluid as well as the size and location of the fluid/air interface inside of the magnetic field were varied. MIL properties varied included the density, magnetic susceptibility, chemical structure, and magnetic element. Uniform tangential magnetic fields pulled the MILs up counter to gravity. The forces per area were not a function of the volume, the surface area inside of the magnetic field, or the volume displacement. However, the presence of fluid/air interfaces was necessary for the phenomena. The Ferrohydrodynamic Bernoulli Relationship predicted the phenomena with the forces being directly related to the fluid's volumetric magnetic susceptibility and the square of the magnetic field strength. [emim][FeCl4] generated the greatest hydraulic head (64-mm or 910 Pa at 1.627 Tesla). This work could aid in experimental design, when free surfaces are involved, and in the development of MIL applications. Copyright © 2014 Elsevier Inc. All rights reserved.

Ionic interactions in biological and physical systems: a variational treatment.

PubMed

Eisenberg, Bob

2013-01-01

Chemistry is about chemical reactions. Chemistry is about electrons changing their configurations as atoms and molecules react. Chemistry has for more than a century studied reactions as if they occurred in ideal conditions of infinitely dilute solutions. But most reactions occur in salt solutions that are not ideal. In those solutions everything (charged) interacts with everything else (charged) through the electric field, which is short and long range extending to the boundaries of the system. Mathematics has recently been developed to deal with interacting systems of this sort. The variational theory of complex fluids has spawned the theory of liquid crystals (or vice versa). In my view, ionic solutions should be viewed as complex fluids, particularly in the biological and engineering context. In both biology and electrochemistry ionic solutions are mixtures highly concentrated (to approximately 10 M) where they are most important, near electrodes, nucleic ids, proteins, active sites of enzymes, and ionic channels. Ca2+ is always involved in biological solutions because the concentration (really free energy per mole) of Ca2+ in a particular location is the signal that controls many biological functions. Such interacting systems are not simple fluids, and it is no wonder that analysis of interactions, such as the Hofmeister series, rooted in that tradition has not succeeded as one would hope. Here, we present a variational treatment of ard spheres in a frictional dielectric with the hope that such a treatment of an lectrolyte as a complex fluid will be productive. The theory automatically extends to spatially nonuniform boundary conditions and the nonequilibrium systems and flows they produce. The theory is unavoidably self-consistent since differential equations are derived (not assumed) from models of (Helmholtz free) nergy and dissipation of the electrolyte. The origin of the Hofmeister series is (in my view) an inverse problem that becomes well posed when enough data from disjoint experimental traditions are interpreted with a self-consistent theory.

Impact of Carrier Fluid Composition on Recovery of Nanoparticles and Proteins in Flow Field Flow Fractionation

PubMed Central

Schachermeyer, Samantha; Ashby, Jonathan; Kwon, MinJung; Zhong, Wenwan

2012-01-01

Flow field flow fractionation (F4) is an invaluable separation tool for large analytes, including nanoparticles and biomolecule complexes. However, sample loss due to analyte-channel membrane interaction limits extensive usage of F4 at present, which could be strongly affected by the carrier fluid composition. This work studied the impacts of carrier fluid (CF) composition on nanoparticle (NP) recovery in F4, with focus on high ionic strength conditions. Successful analysis of NPs in a biomolecules-friendly environment could expand the applicability of F4 to the developing field of nanobiotechnology. Recovery of the unfunctionalized polystyrene NPs of 199-, 102-, and 45-nm in CFs with various pH (6.2, 7.4 and 8.2), increasing ionic strength (0–0.1 M), and different types of co- and counter-ions, were investigated. Additionally, elution of the 85-nm carboxylate NPs and two proteins, human serum albumin (HSA) and immunoglobulin (IgG), at high ionic strengths (0–0.15 M) was investigated. Our results suggested that; 1) Electrostatic repulsion between the negatively charged NPs and the regenerated cellulose membrane was the main force to avoid particle adsorption on the membrane; 2) Larger particles experienced higher attractive force and thus were influenced more by variation in CF composition; and 3) Buffers containing weak anions or NPs with weak anion as the surface functional groups provided higher tolerance to the increase in ionic strength, owing to more anions being trapped inside the NP porous structure. Protein adsorption onto the membrane was also briefly investigated in salted CFs, using human serum albumin and immunoglobulin. We believe our findings could help to identify the basic carrier fluid composition for higher sample recovery in F4 analysis of nanoparticles in a protein-friendly environment, which will be useful for applying F4 in bioassays and in nanotoxicology studies. PMID:23058938

Synergistic Effects Between Phosphonium-Alkylphosphate Ionic Liquids and Zinc Dialkyldithiophosphate (ZDDP) as Lubricant Additives

DOE PAGES

Qu, Jun; Barnhill, William C.; Luo, Huimin; ...

2015-07-14

Unique synergistic effects between phosphonium-alkylphosphate ionic liquids and zinc dialkyldithiophosphate (ZDDP) are discovered when used together as lubricant additives, resulting in significant friction and wear reduction along with distinct tribofilm composition and mechanical properties. The synergism is attributed to the 30-70× higher-than-nominal concentrations of hypothetical new compounds (via anion exchange between IL and ZDDP) on the fluid surface/interface.

Reciprocal regulation of two G protein-coupled receptors sensing extracellular concentrations of Ca2+ and H+

PubMed Central

Wei, Wei-Chun; Jacobs, Benjamin; Becker, Esther B. E.; Glitsch, Maike D.

2015-01-01

G protein-coupled receptors (GPCRs) are cell surface receptors that detect a wide range of extracellular messengers and convey this information to the inside of cells. Extracellular calcium-sensing receptor (CaSR) and ovarian cancer gene receptor 1 (OGR1) are two GPCRs that sense extracellular Ca2+ and H+, respectively. These two ions are key components of the interstitial fluid, and their concentrations change in an activity-dependent manner. Importantly, the interstitial fluid forms part of the microenvironment that influences cell function in health and disease; however, the exact mechanisms through which changes in the microenvironment influence cell function remain largely unknown. We show that CaSR and OGR1 reciprocally inhibit signaling through each other in central neurons, and that this is lost in their transformed counterparts. Furthermore, strong intracellular acidification impairs CaSR function, but potentiates OGR1 function. Thus, CaSR and OGR1 activities can be regulated in a seesaw manner, whereby conditions promoting signaling through one receptor simultaneously inhibit signaling through the other receptor, potentiating the difference in their relative signaling activity. Our results provide insight into how small but consistent changes in the ionic microenvironment of cells can significantly alter the balance between two signaling pathways, which may contribute to disease progression. PMID:26261299

On wettability of shale rocks.

PubMed

Roshan, H; Al-Yaseri, A Z; Sarmadivaleh, M; Iglauer, S

2016-08-01

The low recovery of hydraulic fracturing fluid in unconventional shale reservoirs has been in the centre of attention from both technical and environmental perspectives in the last decade. One explanation for the loss of hydraulic fracturing fluid is fluid uptake by the shale matrix; where capillarity is the dominant process controlling this uptake. Detailed understanding of the rock wettability is thus an essential step in analysis of loss of the hydraulic fracturing fluid in shale reservoirs, especially at reservoir conditions. We therefore performed a suit of contact angle measurements on a shale sample with oil and aqueous ionic solutions, and tested the influence of different ion types (NaCl, KCl, MgCl2, CaCl2), concentrations (0.1, 0.5 and 1M), pressures (0.1, 10 and 20MPa) and temperatures (35 and 70°C). Furthermore, a physical model was developed based on the diffuse double layer theory to provide a framework for the observed experimental data. Our results show that the water contact angle for bivalent ions is larger than for monovalent ions; and that the contact angle (of both oil and different aqueous ionic solutions) increases with increase in pressure and/or temperature; these increases are more pronounced at higher ionic concentrations. Finally, the developed model correctly predicted the influence of each tested variable on contact angle. Knowing contact angle and therefore wettability, the contribution of the capillary process in terms of water uptake into shale rocks and the possible impairment of hydrocarbon production due to such uptake can be quantified. Copyright © 2016 Elsevier Inc. All rights reserved.

Surfactant/Supercritical Fluid Cleaning of Contaminated Substrates

NASA Technical Reports Server (NTRS)

White, Gary L.

1997-01-01

CFC's and halogenated hydrocarbon solvents have been the solvents of choice to degrease and otherwise clean precision metal parts to allow proper function. Recent regulations have, however, rendered most of these solvents unacceptable for these purposes. New processes which are being used or which have been proposed to replace these solvents usually either fail to remove water soluble contaminants or produce significant aqueous wastes which must then be disposed of. In this work, a new method for cleaning surfaces will be investigated. Solubility of typical contaminants such as lubricating greases and phosphatizing bath residues will be studied in several surfactant/supercritical fluid solutions. The effect of temperature, pressure, and the composition of the cleaning mixture on the solubility of oily, polar, and ionic contaminants will be investigated. A reverse micellar solution in a supercritical light hydrocarbon solvent will be used to clean samples of industrial wastes. A reverse micellar solution is one where water is dissolved into a non-polar solvent with the aid of a surfactant. The solution will be capable of dissolving both water-soluble contaminants and oil soluble contaminants. Once the contaminants have been dissolved into the solution they will be separated from the light hydrocarbon and precipitated by a relatively small pressure drop and the supercritical solvent will be available for recycle for reuse. The process will be compared to the efficacy of supercritical CO2 cleaning by attempting to clean the same types of substrates and machining wastes with the same contaminants using supercritical CO2. It is anticipated that the supercritical CO2 process will not be capable of removing ionic residues.

Self‐Regulative Nanogelator Solid Electrolyte: A New Option to Improve the Safety of Lithium Battery

PubMed Central

Wu, Feng; Chen, Nan; Zhu, Qizhen; Tan, Guoqiang; Li, Li

2016-01-01

The lack of suitable nonflammable electrolytes has delayed battery application in electric vehicles. A new approach to improve the safety performance for lithium battery is proposed here. This technology is based on a nanogelator‐based solid electrolyte made of porous oxides and an ionic liquid. The electrolyte is fabricated using an in situ method and the porous oxides serve as a nonflammable “nanogelator” that spontaneously immobilizes the ionic liquid. The electrolyte exhibits a high liquid‐like apparent ionic conductivity of 2.93 × 10−3 S cm−1 at room temperature. The results show that the nanogelator, which possess self‐regulating ability, is able to immobilize imidazolium‐, pyrrolidinium‐, or piperidinium‐based ionic liquids, simply by adjusting the ion transport channels. Our prototype batteries made of Ti‐nanogeltor solid electrolyte outperform conventional lithium batteries made using ionic liquid and commercial organic liquid electrolytes. PMID:27774385

Self-Regulative Nanogelator Solid Electrolyte: A New Option to Improve the Safety of Lithium Battery.

PubMed

Wu, Feng; Chen, Nan; Chen, Renjie; Zhu, Qizhen; Tan, Guoqiang; Li, Li

2016-01-01

The lack of suitable nonflammable electrolytes has delayed battery application in electric vehicles. A new approach to improve the safety performance for lithium battery is proposed here. This technology is based on a nanogelator-based solid electrolyte made of porous oxides and an ionic liquid. The electrolyte is fabricated using an in situ method and the porous oxides serve as a nonflammable "nanogelator" that spontaneously immobilizes the ionic liquid. The electrolyte exhibits a high liquid-like apparent ionic conductivity of 2.93 × 10 -3 S cm -1 at room temperature. The results show that the nanogelator, which possess self-regulating ability, is able to immobilize imidazolium-, pyrrolidinium-, or piperidinium-based ionic liquids, simply by adjusting the ion transport channels. Our prototype batteries made of Ti-nanogeltor solid electrolyte outperform conventional lithium batteries made using ionic liquid and commercial organic liquid electrolytes.

Microfluidic-based Broadband Measurements of Fluid Permittivity and Permeability to 100 GHz

NASA Astrophysics Data System (ADS)

Little, Charles A. E.

This dissertation concerns the development of unique microfluidic microwave devices and associated microwave calibrations to quantitatively extract the broadband permittivity and permeability of fluids between 100 kHz and 110 GHz. The devices presented here consist of SU-8- and PDMS-based microfluidic channels integrated lithographically with coplanar waveguides (CPWs), measured via an external vector network analyzer (VNA). By applying our hybrid set of microwave calibrations to the raw data we extract distributed circuit parameters, representative of the electromagnetic response of the microfluidic channel. We then correlate these parameters to the permittivity and permeability of the fluid within the channels. We are primarily focused on developing devices, calibrations, and analyses to characterize various chemical and biological systems. The small fluid volumes and overall scale of our devices lends the technique to point-of-care blood and cell analysis, as well as to the analysis of high-value chemicals. Broadband microwave microfluidics is sensitive to three primary categories of phenomena: Ionic, dipolar, and magnetic resonances. All three can occur in complex fluids such as blood, proteins and particle suspensions. In order to make quantitative measurements, we need to be able to model and separate all three types of responses. Here we first measure saline solutions (NaCl and water) as an ideal system to better understanding both the ionic and dipolar response. Specifically, we are targeting the electrical double-layer (EDL) response, an ionic effect, which dominates over the intrinsic fluid response at lower frequencies. We have found that the EDL response for saline obeys a strict Debye-type relaxation model, the frequency response of which is dependent solely on the conductivity of the solution. To develop a better understanding of the magnetic response, we first measure magnetic nanoparticles; showing it is possible to detect the magnetic resonances of magnetic nanoparticle in a fluid environment using the broad-band approach, and that the response matches cavity-based measurements. In addition, we demonstrate the complicated intermixing that occurs between magnetic and electrical responses in CPW-type measurements through both numerical modeling, and empirical measurements of impeded embedded permalloy devices.

Ion-size dependent electroosmosis of viscoelastic fluids in microfluidic channels with interfacial slip

NASA Astrophysics Data System (ADS)

Mukherjee, Siddhartha; Goswami, Prakash; Dhar, Jayabrata; Dasgupta, Sunando; Chakraborty, Suman

2017-07-01

We report a study on the ion-size dependent electroosmosis of viscoelastic fluids in microfluidic channels with interfacial slip. Here, we derive an analytical solution for the potential distribution in a parallel plate microchannel, where the effects of finite sized ionic species are taken into account by invoking the free energy formalism. Following this, a purely electroosmotic flow of a simplified Phan-Thien-Tanner (sPTT) fluid is considered. For the sPTT model, linear, quadratic, and exponential kernels are chosen for the stress coefficient function describing its viscoelastic nature across various ranges of Deborah number. The theoretical framework presented in our analysis has been successfully compared with experimental results available in the literature. We believe that the implications of the considered effects on the net volumetric throughput will not only provide a deeper theoretical insight to interpret the electrokinetic data in the presence of ionic species but also serve as a fundamental design tool for novel electrokinetically driven lab-on-a-chip biofluidic devices.

Ionic regulation of the biosynthesis of NaK-ATPase subunits.

PubMed

McDonough, A A; Tang, M J; Lescale-Matys, L

1990-07-01

In this review we have summarized the work of ourselves and others on ionic and hormonal regulation of synthesis of the sodium pump. No one central theme emerges from this summary. Rather, it appears that abundance can be regulated pre-translationally or posttranslationally. As reviewed recently, regulation of the expression of the beta glycoprotein subunit, which has no described enzymatic function, can regulate holoenzyme expression. In the kidney this is exemplified in our studies in LLC-PK1 cells and proximal tubule cells where pre-translational regulation of beta expression is key to increasing holoenzyme abundance, and also exemplified in the hypothyroid renal cortex where regulation of beta protein abundance post-translationally appears to impact the abundance of enzymatically active NaK-ATPase. Future studies in the field of ionic regulation of NaK-ATPase must be directed at elucidating the signals that mediate the response, and at how these signals alter the NaK-ATPase biosynthetic pathway from expression of alpha and beta genes, through to turnover of the mature NaK-ATPase heterodimer.

Rare earth element distribution in some hydrothermal minerals: evidence for crystallographic control

USGS Publications Warehouse

Morgan, J.W.; Wandless, G.A.

1980-01-01

Rare earth element (REE) abundances were measured by neutron activation analysis in anhydrite (CaSO4), barite (BaSO4), siderite (FeCO3) and galena (PbS). A simple crystal-chemical model qualitatively describes the relative affinities for REE substitution in anhydrite, barite, and siderite. When normalized to 'crustal' abundances (as an approximation to the hydrothermal fluid REE pattern), log REE abundance is a surprisingly linear function of (ionic radius of major cation-ionic radius of REE)2 for the three hydrothermal minerals, individually and collectively. An important exception, however, is Eu, which is anomalously enriched in barite and depleted in siderite relative to REE of neighboring atomic number and trivalent ionic radius. In principle, REE analyses of suitable pairs of co-existing hydrothermal minerals, combined with appropriate experimental data, could yield both the REE content and the temperature of the parental hydrothermal fluid. The REE have only very weak chalcophilic tendencies, and this is reflected by the very low abundances in galena-La, 0.6 ppb; Sm, 0.06 ppb; the remainder are below detection limits. ?? 1980.

Solubility and dissolution improvement of ketoprofen by emulsification ionic gelation

NASA Astrophysics Data System (ADS)

Rachmaniar, Revika; Tristiyanti, Deby; Hamdani, Syarif; Afifah

2018-02-01

Ketoprofen or [2-(3-benzoylphenyl) propionic acid] is non-steroidal anti-inflammatory (NSAID) and an analgesic which has high permeability and low solubility. The purpose of this work was to improve the solubility and dissolution of poorly water-soluble ketoprofen prepared by emulsification ionic gelation method and utilizing polymer (chitosan) and cross linker (tripolyphosphate, TPP) for particles formulation. The results show that increasing pH value of TPP, higher solubility and dissolution of as-prepared ketoprofen-chitosan was obtained. The solubility in water of ketoprofen-chitosan with pH 6 for TPP increased 2.71-fold compared to untreated ketoprofen. While the dissolution of ketoprofen-chitosan with pH 6 of TPP in simulated gastric fluid without enzyme (0.1 N HCl), pH 4.5 buffer and simulated intestinal fluid without enzyme (phosphate buffer pH 6.8) was increased 1.9-fold, 1.6-fold and 1.2-fold compared to untreated ketoprofen for dissolution time of 30 minutes, respectively. It could be concluded that chitosan and TPP in the emulsification ionic gelation method for ketoprofen preparation effectively increases solubility and dissolution of poorly water-soluble ketoprofen.

Stagnation point flow of wormlike micellar solutions in a microfluidic cross-slot device: effects of surfactant concentration and ionic environment.

PubMed

Haward, Simon J; McKinley, Gareth H

2012-03-01

We employ the techniques of microparticle image velocimetry and full-field birefringence microscopy combined with mechanical measurements of the pressure drop to perform a detailed characterization of the extensional rheology and elastic flow instabilities observed for a range of wormlike micellar solutions flowing through a microfluidic cross-slot device. As the flow rate through the device is increased, the flow first bifurcates from a steady symmetric to a steady asymmetric configuration characterized by a birefringent strand of highly aligned micellar chains oriented along the shear-free centerline of the flow field. At higher flow rates the flow becomes three dimensional and time dependent and is characterized by aperiodic spatiotemporal fluctuations of the birefringent strand. The extensional properties and critical conditions for the onset of flow instabilities in the fluids are highly dependent on the fluid formulation (surfactant concentration and ionic strength) and the resulting changes in the linear viscoelasticity and nonlinear shear rheology of the fluids. By combining the measurements of critical conditions for the flow transitions with the viscometric material properties and the degree of shear-thinning characterizing each test fluid, it is possible to construct a stability diagram for viscoelastic flow of complex fluids in the cross-slot geometry.

21 CFR 862.1540 - Osmolality test system.

Code of Federal Regulations, 2011 CFR

2011-04-01

...) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862... measure ionic and nonionic solute concentration in body fluids, such as serum and urine. Osmolality...

21 CFR 862.1540 - Osmolality test system.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862... measure ionic and nonionic solute concentration in body fluids, such as serum and urine. Osmolality...

21 CFR 862.1540 - Osmolality test system.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862... measure ionic and nonionic solute concentration in body fluids, such as serum and urine. Osmolality...

21 CFR 862.1540 - Osmolality test system.

Code of Federal Regulations, 2010 CFR

2010-04-01

...) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862... measure ionic and nonionic solute concentration in body fluids, such as serum and urine. Osmolality...

Sequential Vapor Infiltration Treatment Enhances the Ionic Current Rectification Performance of Composite Membranes Based on Mesoporous Silica Confined in Anodic Alumina.

PubMed

Liang, Yanyan; Liu, Zhengping

2016-12-20

Ionic current rectification of nanofluidic diode membranes has been studied widely in recent years because it is analogous to the functionality of biological ion channels in principle. We report a new method to fabricate ionic current rectification membranes based on mesoporous silica confined in anodic aluminum oxide (AAO) membranes. Two types of mesostructured silica nanocomposites, hexagonal structure and nanoparticle stacked structure, were used to asymmetrically fill nanochannels of AAO membranes by a vapor-phase synthesis (VPS) method with aspiration approach and were further modified via sequence vapor infiltration (SVI) treatment. The ionic current measurements indicated that SVI treatment can modulate the asymmetric ionic transport in prepared membranes, which exhibited clear ionic current rectification phenomenon under optimal conditions. The ionic current rectifying behavior is derived from the asymmetry of surface conformations, silica species components, and hydrophobic wettability, which are created by the asymmetrical filling type, silica depositions on the heterogeneous membranes, and the condensation of silanol groups. This article provides a considerable strategy to fabricate composite membranes with obvious ionic current rectification performance via the cooperation of the VPS method and SVI treatment and opens up the potential of mesoporous silica confined in AAO membranes to mimic fluid transport in biological processes.

Fluid flow sensing with ionic polymer-metal composites

NASA Astrophysics Data System (ADS)

Stalbaum, Tyler; Trabia, Sarah; Shen, Qi; Kim, Kwang J.

2016-04-01

Ionic polymer-metal composite (IPMC) actuators and sensors have been developed and modeled over the last two decades for use as soft-robotic deformable actuators and sensors. IPMC devices have been suggested for application as underwater actuators, energy harvesting devices, and medical devices such as in guided catheter insertion. Another interesting application of IPMCs in flow sensing is presented in this study. IPMC interaction with fluid flow is of interest to investigate the use of IPMC actuators as flow control devices and IPMC sensors as flow sensing devices. An organized array of IPMCs acting as interchanging sensors and actuators could potentially be designed for both flow measurement and control, providing an unparalleled tool in maritime operations. The underlying physics for this system include the IPMC ion transport and charge fundamental framework along with fluid dynamics to describe the flow around IPMCs. An experimental setup for an individual rectangular IPMC sensor with an externally controlled fluid flow has been developed to investigate this phenomenon and provide further insight into the design and application of this type of device. The results from this portion of the study include recommendations for IPMC device designs in flow control.

Methods for applying microchannels to separate methane using liquid absorbents, especially ionic liquid absorbents from a mixture comprising methane and nitrogen

DOEpatents

Tonkovich, Anna Lee Y [Dublin, OH; Litt, Robert D [Westerville, OH; Dongming, Qiu [Dublin, OH; Silva, Laura J [Plain City, OH; Lamont, Micheal Jay [Plain City, OH; Fanelli, Maddalena [Plain City, OH; Simmons, Wayne W [Plain city, OH; Perry, Steven [Galloway, OH

2011-10-04

Methods of using microchannel separation systems including absorbents to improve thermal efficiency and reduce parasitic power loss. Energy is typically added to desorb methane and then energy or heat is removed to absorb methane using a working solution. The working solution or absorbent may comprise an ionic liquid, or other fluids that demonstrate a difference in affinity between methane and nitrogen in a solution.

Global transcriptome response to ionic liquid by a tropical rain forest soil bacterium, Enterobacter lignolyticus.

PubMed

Khudyakov, Jane I; D'haeseleer, Patrik; Borglin, Sharon E; Deangelis, Kristen M; Woo, Hannah; Lindquist, Erika A; Hazen, Terry C; Simmons, Blake A; Thelen, Michael P

2012-08-07

To process plant-based renewable biofuels, pretreatment of plant feedstock with ionic liquids has significant advantages over current methods for deconstruction of lignocellulosic feedstocks. However, ionic liquids are often toxic to the microorganisms used subsequently for biomass saccharification and fermentation. We previously isolated Enterobacter lignolyticus strain SCF1, a lignocellulolytic bacterium from tropical rain forest soil, and report here that it can grow in the presence of 0.5 M 1-ethyl-3-methylimidazolium chloride, a commonly used ionic liquid. We investigated molecular mechanisms of SCF1 ionic liquid tolerance using a combination of phenotypic growth assays, phospholipid fatty acid analysis, and RNA sequencing technologies. Potential modes of resistance to 1-ethyl-3-methylimidazolium chloride include an increase in cyclopropane fatty acids in the cell membrane, scavenging of compatible solutes, up-regulation of osmoprotectant transporters and drug efflux pumps, and down-regulation of membrane porins. These findings represent an important first step in understanding mechanisms of ionic liquid resistance in bacteria and provide a basis for engineering microbial tolerance.

Recent developments in biocatalysis in multiphasic ionic liquid reaction systems.

PubMed

Meyer, Lars-Erik; von Langermann, Jan; Kragl, Udo

2018-06-01

Ionic liquids are well known and frequently used 'designer solvents' for biocatalytic reactions. This review highlights recent achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants in different phases.

Channels, pumps, and exchangers in the gill and kidney of freshwater fishes: their role in ionic and acid-base regulation.

PubMed

Perry, S F; Shahsavarani, A; Georgalis, T; Bayaa, M; Furimsky, M; Thomas, S L Y

2003-11-01

In freshwater fishes, the gill and kidney are intricately involved in ionic and acid-base regulation owing to the presence of numerous ion channels, pumps, or exchangers. This review summarizes recent developments in branchial and renal ion transport physiology and presents several models that integrate epithelial ion and acid-base movements in freshwater fishes. At the gill, three cell types are potentially involved in ionic uptake: pavement cells, mitochondria-rich (MR) PNA(+) cells, and MR PNA(-) cells. The transfer of acidic or basic equivalents between the fish and its environment is accomplished largely by the gill and is appropriately regulated to correct acid-base imbalances. The kidney, while less important than the gill in overall acid or base excretion, has an essential role in regulating systemic acid-base balance by controlling HCO(3) (-) reabsorption from the filtrate. Copyright 2003 Wiley-Liss, Inc.

Assessing the dispersive and electrostatic components of the cohesive energy of ionic liquids using molecular dynamics simulations and molar refraction data.

PubMed

Shimizu, Karina; Tariq, Mohammad; Costa Gomes, Margarida F; Rebelo, Luís P N; Canongia Lopes, José N

2010-05-06

Molecular dynamics simulations were used to calculate the density and the cohesive molar internal energy of seventeen different ionic liquids in the liquid phase. The results were correlated with previously reported experimental density and molar refraction data. The link between the dispersive component of the total cohesive energy of the fluid and the corresponding molar refraction was established in an unequivocal way. The results have shown that the two components of the total cohesive energy (dispersive and electrostatic) exhibit strikingly different trends and ratios along different families of ionic liquids, a notion that may help explain their diverse behavior toward different molecular solutes and solvents.

Microfluidic System Simulation Including the Electro-Viscous Effect

NASA Technical Reports Server (NTRS)

Rojas, Eileen; Chen, C. P.; Majumdar, Alok

2007-01-01

This paper describes a practical approach using a general purpose lumped-parameter computer program, GFSSP (Generalized Fluid System Simulation Program) for calculating flow distribution in a network of micro-channels including electro-viscous effects due to the existence of electrical double layer (EDL). In this study, an empirical formulation for calculating an effective viscosity of ionic solutions based on dimensional analysis is described to account for surface charge and bulk fluid conductivity, which give rise to electro-viscous effect in microfluidics network. Two dimensional slit micro flow data was used to determine the model coefficients. Geometry effect is then included through a Poiseuille number correlation in GFSSP. The bi-power model was used to calculate flow distribution of isotropically etched straight channel and T-junction microflows involving ionic solutions. Performance of the proposed model is assessed against experimental test data.

Chemical Effect on Wellbore Instability of Nahr Umr Shale

PubMed Central

Nie, Zhen

2013-01-01

Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable. PMID:24282391

Ion association at discretely-charged dielectric interfaces: Giant charge inversion

NASA Astrophysics Data System (ADS)

Wang, Zhi-Yong; Wu, Jianzhong

2017-07-01

Giant charge reversal has been identified for the first time by Monte Carlo simulation for a discretely charged surface in contact with a trivalent electrolyte solution. It takes place regardless of the surface charge density under study and the monovalent salt. In stark contrast to earlier predictions based on the 2-dimensional Wigner crystal model to describe strong correlation of counterions at the macroion surface, we find that giant charge reversal reflects an intricate interplay of ionic volume effects, electrostatic correlations, surface charge heterogeneity, and the dielectric response of the confined fluids. While the novel phenomenon is yet to be confirmed with experiment, the simulation results appear in excellent agreement with a wide range of existing observations in the subregime of charge inversion. Our findings may have far-reaching implications to understanding complex electrochemical phenomena entailing ionic fluids under dielectric confinements.

Chemical effect on wellbore instability of Nahr Umr Shale.

PubMed

Yu, Baohua; Yan, Chuanliang; Nie, Zhen

2013-01-01

Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

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

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

2016-08-04

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.

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.

The effect of pH, buffer capacity and ionic strength on quetiapine fumarate release from matrix tablets prepared using two different polymeric blends.

PubMed

Hamed, Rania; AlJanabi, Reem; Sunoqrot, Suhair; Abbas, Aiman

2017-08-01

The objective of this study was to investigate the effect of the different physiological parameters of the gastrointestinal (GI) fluid (pH, buffer capacity, and ionic strength) on the in vitro release of the weakly basic BCS class II drug quetiapine fumarate (QF) from two once-a-day matrix tablet formulations (F1 and F2) developed as potential generic equivalents to Seroquel ® XR. F1 tablets were prepared using blends of high and low viscosity grades of hydroxypropyl methylcellulose (HPMC K4M and K100LV, respectively), while F2 tablets were prepared from HPMC K4M and PEGylated glyceryl behenate (Compritol ® HD5 ATO). The two formulations attained release profiles of QF over 24 h similar to that of Seroquel ® XR using the dissolution medium published by the Food and Drug Administration (FDA). A series of solubility and in vitro dissolution studies was then carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH, buffer capacity and ionic strength range of the GIT. Solubility studies revealed that QF exhibits a typical weak base pH-dependent solubility profile and that the solubility of QF increases with increasing the buffer capacity and ionic strength of the media. The release profiles of QF from F1, F2 and Seroquel ® XR tablets were found to be influenced by the pH, buffer capacity and ionic strength of the dissolution media to varying degrees. Results highlight the importance of studying the physiological variables along the GIT in designing controlled release formulations for more predictive in vitro-in vivo correlations.

ATPase activity and light scattering of acto-heavy meromyosin: dependence on ATP concentration and on ionic strength.

PubMed

Dancker, P

1975-01-01

1. The dependence on ATP concentration of ATPase activity and light scattering decrease of acto-HMM could be described at very low ionic strength by one hyperbolic adsorption isotherm with a dissociation constant of 3 X 10(-6)M. Hence the increase of ATP ase activity was paralleled by a decrease in light scattering. At higher values of ionic strength ATPase activity stopped rising before HMM was completely saturated with ATP. Higher ionic strength prevented ATPase activity from further increasing when the rigor links (links between actin and nucleotide-free myosin), which have formerly protected the ATPase against the suppressing action of higher ionic strength have fallen below a certain amount. This protecting influence of rigor links did not require tropomyosin-troponin. 2. For complete activation of ATPase activity by actin less actin was needed when HMM was incompletely saturated with ATP than when it was completely saturated with ATP. 3. The apparent affinity of ATP to regulated acto-HMM (which contained tropomyosin-troponin) was lower than to unregulated acto-HMM (which was devoid of tropomyosin-troponin). In the presence of rigor complexes (indicated by an incomplete decrease of light scattering) the ATPase activity of regulated acto-HMM was higher than that of unregulated acto-HMM. At increasing ATP concentrations the ATPase activity of regulated acto-HMM stopped rising at a similar degree of saturation with ATP as the ATPase activity of unregulated acto-HMM at the same ionic strength.

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.

Adsorbed Layers of Ferritin at Solid and Fluid Interfaces Studied by Atomic Force Microscopy.

PubMed

Johnson; Yuan; Lenhoff

2000-03-15

The adsorption of the iron storage protein ferritin was studied by liquid tapping mode atomic force microscopy in order to obtain molecular resolution in the adsorbed layer within the aqueous environment in which the adsorption was carried out. The surface coverage and the structure of the adsorbed layer were investigated as functions of ionic strength and pH on two different charged surfaces, namely chemically modified glass slides and mixed surfactant films at the air-water interface, which were transferred to graphite substrates after adsorption. Surface coverage trends with both ionic strength and pH indicate the dominance of electrostatic effects, with the balance shifting between intermolecular repulsion and protein-surface attraction. The resulting behavior is more complex than that seen for larger colloidal particles, which appear to follow a modified random sequential adsorption model monotonically. The structure of the adsorbed layers at the solid surfaces is random, but some indication of long-range order is apparent at fluid interfaces, presumably due to the higher protein mobility at the fluid interface. Copyright 2000 Academic Press.

Dynamics of two interacting active Janus particles.

PubMed

Bayati, Parvin; Najafi, Ali

2016-04-07

Starting from a microscopic model for a spherically symmetric active Janus particle, we study the interactions between two such active motors. The ambient fluid mediates a long range hydrodynamic interaction between two motors. This interaction has both direct and indirect hydrodynamic contributions. The direct contribution is due to the propagation of fluid flow that originated from a moving motor and affects the motion of the other motor. The indirect contribution emerges from the re-distribution of the ionic concentrations in the presence of both motors. Electric force exerted on the fluid from this ionic solution enhances the flow pattern and subsequently changes the motion of both motors. By formulating a perturbation method for very far separated motors, we derive analytic results for the translation and rotational dynamics of the motors. We show that the overall interaction at the leading order modifies the translational and rotational speeds of motors which scale as O[1/D](3) and O[1/D](4) with their separation, respectively. Our findings open up the way for studying the collective dynamics of synthetic micro-motors.

Thermally conductive of nanofluid from surfactant doped polyaniline nanoparticle and deep eutectic ionic liquid

NASA Astrophysics Data System (ADS)

Siong, Chew Tze; Daik, Rusli; Hamid, Muhammad Azmi Abdul

2014-09-01

Nanofluid is a colloidal suspension of nano-size particles in a fluid. Spherical shape dodecylbenzenesulfonic acid doped polyaniline (DBSA-PANI) nanoparticles were synthesized via reverse micellar polymerization in isooctane with average size of 50 nm- 60 nm. The aim of study is to explore the possibility of using deep eutectic ionic liquid (DES) as a new base fluid in heat transfer application. DES was prepared by heating up choline chloride and urea with stirring. DES based nanofluids containing DBSA-PANI nanoparticles were prepared using two-step method. Thermal conductivity of nanofluids was measured using KD2 Pro Thermal Properties Analyzer. When incorporated with DBSA-PANI nanoparticles, DES with water was found to exhibit a bigger increase in thermal conductivity compared to that of the pure DES. The thermal conductivity of DES with water was increased by 4.67% when incorporated with 0.2 wt% of DBSA-PANI nanoparticles at 50°C. The enhancement in thermal conductivity of DES based nanofluids is possibly related to Brownian motion of nanoparticles as well as micro-convection of base fluids and also interaction between dopants and DES ions.

Cystathionine β-Synthase (CBS) Domains 1 and 2 Fulfill Different Roles in Ionic Strength Sensing of the ATP-binding Cassette (ABC) Transporter OpuA*

PubMed Central

Karasawa, Akira; Erkens, Guus B.; Berntsson, Ronnie P.-A.; Otten, Renee; Schuurman-Wolters, Gea K.; Mulder, Frans A. A.; Poolman, Bert

2011-01-01

The cystathionine β-synthase module of OpuA in conjunction with an anionic membrane surface acts as a sensor of internal ionic strength, which allows the protein to respond to osmotic stress. We now show by chemical modification and cross-linking studies that CBS2-CBS2 interface residues are critical for transport activity and/or ionic regulation of transport, whereas CBS1 serves no functional role. We establish that Cys residues in CBS1, CBS2, and the nucleotide-binding domain are more accessible for cross-linking at high than low ionic strength, indicating that these domains undergo conformational changes when transiting between the active and inactive state. Structural analyses suggest that the cystathionine β-synthase module is largely unstructured. Moreover, we could substitute CBS1 by a linker and preserve ionic regulation of transport. These data suggest that CBS1 serves as a linker and the structured CBS2-CBS2 interface forms a hinge point for ionic strength-dependent rearrangements that are transmitted to the nucleotide-binding domain and thereby affect translocation activity. PMID:21878634

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

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

PubMed

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.

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.

K-targeted strategy for isolation of phenolic alkaloids of Nelumbo nucifera Gaertn by counter-current chromatography using lysine as a pH regulator.

PubMed

Wang, Yanyan; Zhang, Lihong; Zhou, Hui; Guo, Xiuyun; Wu, Shihua

2017-03-24

Counter-current chromatography (CCC) is an efficient liquid-liquid partition chromatography technique without support matrix. Despite there are many significant advancements in the CCC separation of natural products especially for non-ionic neutral compounds, CCC isolation of ionic compounds including alkaloids is still a challenging process guide by classical partition coefficients (K) or distribution ratio (K C ) because their partition coefficient could not be equal to distribution ratio in common ionic conditions. Here, taking the extract of embryo of the seed of Nelumbo nucifera Gaertn as sample, we introduced a modified K-targeted strategy for isolation of phenolic alkaloids by use of lysine as a pH regulator. The results indicated that if the mass of basic regulators such as aqueous ammonia and lysine added into the solvent system were high enough to inhibit the ionization of the targeted alkaloids, the distribution ratio of targets with ionic and non-ionic molecular forms got stable and might not been changed as the concentration of the pH regulator. In this case, the distribution ratio of target was almost equal to the partition coefficient. Thus, the targets could be isolated by K-targeted CCC separation through adding a certain amount pH regulators into the solvent system. Further experiments also showed that the sample concentration was an important factor on the distribution ratio of targets. Meanwhile, CCC experiments indicated that lysine was more suitable than aqueous ammonia for the separation of phenolic alkaloids because the chemical property of lysine-target complex in the CCC fractions was more stable. Therefore, the preparative CCC separation was performed using 20mM lysine as a pH regulator with more than 800mg injection mass. After simple back-extraction with dichloromethane, the lysine in the CCC fraction was removed completely and pure isoliensinine and neferine were obtained. In summary, the whole results indicated that the modified K-targeted CCC strategy using lysine as the pH regulator was efficient for isolation of phenolic alkaloids from crude plant extracts. It not only provided a practical strategy for the isolation of neferine and its analogues, but also introduced a powerful method to resolve the peak skewing (leading or tailing) in CCC separation of ionic compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

NASA Astrophysics Data System (ADS)

Sadeghi, Morteza; Saidi, Mohammad Hassan; Sadeghi, Arman

2017-06-01

Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well as to validate the analytical solutions. We show that, with the exception of the migratory ionic conductivity, all the physicochemical parameters are strong functions of the channel aspect ratio. Accordingly, a slit geometry is not a good representative of a rectangular channel when the width is comparable to the height. It is also observed that the distribution of the electrical potential is not uniform over the surface of a charge-regulated channel. In addition, unlike ordinary channels for which an increase in the background salt concentration is always accompanied by higher flow rates, quite the opposite may be true for a pH-regulated duct at higher salt concentrations.

Vector Analysis of Ionic Collision on CaCO3 Precipitation Based on Vibration Time History

NASA Astrophysics Data System (ADS)

Mangestiyono, W.; Muryanto, S.; Jamari, J.; Bayuseno, A. P.

2017-05-01

Vibration effects on the piping system can result from the internal factor of fluid or the external factor of the mechanical equipment operation. As the pipe vibrated, the precipitation process of CaCO3 on the inner pipe could be affected. In the previous research, the effect of vibration on CaCO3 precipitation in piping system was clearly verified. This increased the deposition rate and decreased the induction time. However, the mechanism of vibration control in CaCO3 precipitation process as the presence of vibration has not been recognized yet. In the present research, the mechanism of vibration affecting the CaCO3 precipitation was investigated through vector analysis of ionic collision. The ionic vector force was calculated based on the amount of the activation energy and the vibration force was calculated based on the vibration sensor data. The vector resultant of ionic collision based on the vibration time history was analyzed to prove that vibration brings ionic collision randomly to the planar horizontal direction and its collision model was suspected as the cause of the increasing deposition rate.

Effect of diode-laser and AC magnetic field of bovine serum albumin nanospheres loaded with phthalocyanine and magnetic particles.

PubMed

Simioni, Andreza Ribeiro; Rodrigues, Marcilene M A; Primo, Fernando L; Morais, Paulo C; Tedesco, Antonio Claudio

2011-04-01

This study reports on the development and characterization of bovine serum albumin (BSA) nanospheres containing Silicon(IV) phthalocyanine (NzPc) and/or maghemite nanoparticles (MNP), the latter introduced via ionic magnetic fluid (MF). The nanosized BSA-loaded samples were designed for synergic application while combining Photodynamic Therapy and Hyperthermia. Incorporation of MNP in the albumin-based template, allowing full control of the magnetic content, was accomplished by adding a highly-stable ionic magnetic fluid sample to the albumin suspension, following heat denaturing. The material's evaluation was performed using Zeta potential measurements and scanning electron microscopy. The samples were characterized by steady-state techniques and time-resolved fluorescence. The in vitro assay, using human fibroblasts, revealed no cytotoxic effect in all samples investigated, demonstrating the potential of the tested system as a synergistic drug delivery system.

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

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.

Chirality-selected phase behaviour in ionic polypeptide complexes

DOE PAGES

Perry, Sarah L.; Leon, Lorraine; Hoffmann, Kyle Q.; ...

2015-01-14

In this study, polyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation. Here we demonstrate that chirality determines the state of polyelectrolyte complexes, formed from mixing dilute solutions of oppositely charged polypeptides, via a combination of electrostatic and hydrogen-bonding interactions. Fluid complexes occur when at least one of the polypeptides in the mixture is racemic, which disrupts backbone hydrogen-bonding networks. Pairs of purely chiral polypeptides, of any sense, form compact, fibrillar solids with amore » β-sheet structure. Analogous behaviour occurs in micelles formed from polypeptide block copolymers with polyethylene oxide, where assembly into aggregates with either solid or fluid cores, and eventually into ordered phases at high concentrations, is possible. Chirality is an exploitable tool for manipulating material properties in polyelectrolyte complexation.« less

A review of the structure and dynamics of nanoconfined water and ionic liquids via molecular dynamics simulation.

PubMed

Foroutan, Masumeh; Fatemi, S Mahmood; Esmaeilian, Farshad

2017-02-01

During the past decade, the research on fluids in nanoconfined geometries has received considerable attention as a consequence of their wide applications in different fields. Several nanoconfined systems such as water and ionic liquids, together with an equally impressive array of nanoconfining media such as carbon nanotube, graphene and graphene oxide have received increasingly growing interest in the past years. Water is the first system that has been reviewed in this article, due to its important role in transport phenomena in environmental sciences. Water is often considered as a highly nanoconfined system, due to its reduction to a few layers of water molecules between the extended surface of large macromolecules. The second system discussed here is ionic liquids, which have been widely studied in the modern green chemistry movement. Considering the great importance of ionic liquids in industry, and also their oil/water counterpart, nanoconfined ionic liquid system has become an important area of research with many fascinating applications. Furthermore, the method of molecular dynamics simulation is one of the major tools in the theoretical study of water and ionic liquids in nanoconfinement, which increasingly has been joined with experimental procedures. In this way, the choice of water and ionic liquids in nanoconfinement is justified by applying molecular dynamics simulation approaches in this review article.

Modelling the influence of ionic and fluid transport on rebars corrosion in unsaturated cement systems

NASA Astrophysics Data System (ADS)

Dridi, W.; Dangla, P.; Foct, F.; Petre-Lazar, I.

2006-11-01

This paper deals with numerical modelling of rebar corrosion kinetics in unsaturated concrete structures. The corrosion kinetics is investigated in terms of mechanistic coupling between reaction rates at the steel surface and the ionic transport processes in the concrete pore system. The ionic and mass transport model consists of time-dependent equations for the concentration of dissolved species, the liquid pressure and the electrical potential. The complete set of nonlinear equations is solved using the finite-volume method. The nonlinear boundary conditions dealing with corrosion are introduced at the steel-concrete interface where they are implicitly coupled with the mass transport model in the concrete structure. Both the case of free corrosion and potentiostatic polarisation are discussed in a one dimensional model.

Large Electro-Optic Kerr Effect in Ionic Liquid Crystals: Connecting Features of Liquid Crystals and Polyelectrolytes.

PubMed

Schlick, M Christian; Kapernaum, Nadia; Neidhardt, Manuel M; Wöhrle, Tobias; Stöckl, Yannick; Laschat, Sabine; Giesselmann, Frank

2018-06-06

The electro-optic Kerr effect in simple dipolar fluids such as nitrobenzene has been widely applied in electro-optical phase modulators and light shutters. In 2005, the discovery of the large Kerr effect in liquid-crystalline blue phases (Y. Hisakado et al., Adv. Mater. 2005, 17, 96-98.) gave new directions to the search for advanced Kerr effect materials. Even though the Kerr effect is present in all transparent and optically isotropic media, it is well known that the effect can be anomalously large in complex fluids, namely in the isotropic phase of liquid crystals or in polyelectrolyte solutions. Herein, it is shown that the Kerr effect in the isotropic phase of ionic liquid crystals combines the effective counterion polarization mechanism found in polyelectrolytes and the unique pretransitional growth of the Kerr constant found in the isotropic phase of nematic liquid crystals. Maximum Kerr constants in the order of several 10 -11  m V -2 (ten times higher than the Kerr constant of the toxic nitrobenzene and less temperature sensitive than Kerr constants of nematic liquid crystals) make ionic liquid crystals attractive as new class of functional materials in low-speed Kerr effect applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantifying the thickness of the electrical double layer neutralizing a planar electrode: the capacitive compactness.

PubMed

Guerrero-García, Guillermo Iván; González-Tovar, Enrique; Chávez-Páez, Martín; Kłos, Jacek; Lamperski, Stanisław

2017-12-20

The spatial extension of the ionic cloud neutralizing a charged colloid or an electrode is usually characterized by the Debye length associated with the supporting charged fluid in the bulk. This spatial length arises naturally in the linear Poisson-Boltzmann theory of point charges, which is the cornerstone of the widely used Derjaguin-Landau-Verwey-Overbeek formalism describing the colloidal stability of electrified macroparticles. By definition, the Debye length is independent of important physical features of charged solutions such as the colloidal charge, electrostatic ion correlations, ionic excluded volume effects, or specific short-range interactions, just to mention a few. In order to include consistently these features to describe more accurately the thickness of the electrical double layer of an inhomogeneous charged fluid in planar geometry, we propose here the use of the capacitive compactness concept as a generalization of the compactness of the spherical electrical double layer around a small macroion (González-Tovar et al., J. Chem. Phys. 2004, 120, 9782). To exemplify the usefulness of the capacitive compactness to characterize strongly coupled charged fluids in external electric fields, we use integral equations theory and Monte Carlo simulations to analyze the electrical properties of a model molten salt near a planar electrode. In particular, we study the electrode's charge neutralization, and the maximum inversion of the net charge per unit area of the electrode-molten salt system as a function of the ionic concentration, and the electrode's charge. The behaviour of the associated capacitive compactness is interpreted in terms of the charge neutralization capacity of the highly correlated charged fluid, which evidences a shrinking/expansion of the electrical double layer at a microscopic level. The capacitive compactness and its first two derivatives are expressed in terms of experimentally measurable macroscopic properties such as the differential and integral capacity, the electrode's surface charge density, and the mean electrostatic potential at the electrode's surface.

Bions: A Family of Biomimetic Mineralo-Organic Complexes Derived from Biological Fluids

PubMed Central

Martel, Jan; Young, John D.

2013-01-01

Mineralo-organic nanoparticles form spontaneously in human body fluids when the concentrations of calcium and phosphate ions exceed saturation. We have shown previously that these mineralo-organic nanoparticles possess biomimetic properties and can reproduce the whole phenomenology of the so-called nanobacteria—mineralized entities initially described as the smallest microorganisms on earth. Here, we examine the possibility that various charged elements and ions may form mineral nanoparticles with similar properties in biological fluids. Remarkably, all the elements tested, including sodium, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, copper, zinc, strontium, and barium form mineralo-organic particles with bacteria-like morphologies and other complex shapes following precipitation with phosphate in body fluids. Upon formation, these mineralo-organic particles, which we term bions, invariably accumulate carbonate apatite during incubation in biological fluids; yet, the particles also incorporate additional elements and thus reflect the ionic milieu in which they form. Bions initially harbor an amorphous mineral phase that gradually converts to crystals in culture. Our results show that serum produces a dual inhibition-seeding effect on bion formation. Using a comprehensive proteomic analysis, we identify a wide range of proteins that bind to these mineral particles during incubation in medium containing serum. The two main binding proteins identified, albumin and fetuin-A, act as both inhibitors and seeders of bions in culture. Notably, bions possess several biomimetic properties, including the possibility to increase in size and number and to be sub-cultured in fresh culture medium. Based on these results, we propose that bions represent biological, mineralo-organic particles that may form in the body under both physiological and pathological homeostasis conditions. These mineralo-organic particles may be part of a physiological cycle that regulates the function, transport and disposal of elements and minerals in the human body. PMID:24086546

Bone as an ion exchange system: evidence for a link between mechanotransduction and metabolic needs.

PubMed

Rubinacci, A; Covini, M; Bisogni, C; Villa, I; Galli, M; Palumbo, C; Ferretti, M; Muglia, M A; Marotti, G

2002-04-01

To detect whether the mutual interaction occurring between the osteocytes-bone lining cells system (OBLCS) and the bone extracellular fluid (BECF) is affected by load through a modification of the BECF-extracellular fluid (ECF; systemic extracellular fluid) gradient, mice metatarsal bones immersed in ECF were subjected ex vivo to a 2-min cyclic axial load of different amplitudes and frequencies. The electric (ionic) currents at the bone surface were measured by a vibrating probe after having exposed BECF to ECF through a transcortical hole. The application of different loads and different frequencies increased the ionic current in a dose-dependent manner. The postload current density subsequently decayed following an exponential pattern. Postload increment's amplitude and decay were dependent on bone viability. Dummy and static loads did not induce current density modifications. Because BECF is perturbed by loading, it is conceivable that OBLCS tends to restore BECF preload conditions by controlling ion fluxes at the bone-plasma interface to fulfill metabolic needs. Because the electric current reflects the integrated activity of OBLCS, its evaluation in transgenic mice engineered to possess genetic lesions in channels or matrix constituents could be helpful in the characterization of the mechanical and metabolic functions of bone.

Biology's built-in Faraday cages

NASA Astrophysics Data System (ADS)

Klee, Maurice M.

2014-05-01

Biological fluids are water-based, ionic conductors. As such, they have both high relative dielectric constants and substantial conductivities, meaning they are lossy dielectrics. These fluids contain charged molecules (free charges), whose movements play roles in essentially all cellular processes from metabolism to communication with other cells. Using the problem of a point source in air above a biological fluid of semi-infinite extent, the bound charges in the fluid are shown to perform the function of a fast-acting Faraday cage, which protects the interior of the fluid from external electric fields. Free charges replace bound charges in accordance with the fluid's relaxation time, thereby providing a smooth transition between the initial protection provided by the bound charges and the steady state protection provided by the free charges. The electric fields within the biological fluid are thus small for all times just as they would be inside a classical Faraday cage.

Composition Pulse Time-Of-Flight Mass Flow Sensor

DOEpatents

Mosier, Bruce P.; Crocker, Robert W.; Harnett, Cindy K. l

2004-01-13

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 10,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined

Electrogenic transport and K+ ion channel expression by the human endolymphatic sac epithelium

PubMed Central

Kim, Sung Huhn; Kim, Bo Gyung; Kim, Jin Young; Roh, Kyung Jin; Suh, Michelle J.; Jung, JinSei; Moon, In Seok; Moon, Sung K.; Choi, Jae Young

2015-01-01

The endolymphatic sac (ES) is a cystic organ that is a part of the inner ear and is connected to the cochlea and vestibule. The ES is thought to be involved in inner ear ion homeostasis and fluid volume regulation for the maintenance of hearing and balance function. Many ion channels, transporters, and exchangers have been identified in the ES luminal epithelium, mainly in animal studies, but there has been no functional study investigating ion transport using human ES tissue. We designed the first functional experiments on electrogenic transport in human ES and investigated the contribution of K+ channels in the electrogenic transport, which has been rarely identified, even in animal studies, using electrophysiological/pharmacological and molecular biological methods. As a result, we identified functional and molecular evidence for the essential participation of K+ channels in the electrogenic transport of human ES epithelium. The identified K+ channels involved in the electrogenic transport were KCNN2, KCNJ14, KCNK2, and KCNK6, and the K+ transports via those channels are thought to play an important role in the maintenance of the unique ionic milieu of the inner ear fluid. PMID:26655723

Effect of ionic activity products on the structure and composition of mineral self assembled on three-dimensional poly(lactide-co-glycolide) scaffolds

PubMed Central

Shin, Kyungsup; Jayasuriya, Ambalangodage C.; Kohn, David H.

2009-01-01

A biomimetic approach involving the self-assembly of mineral within the pores of three-dimensional porous polymer scaffolds is a promising strategy to integrate advantages of inorganic and organic phases into a single material for hard tissue engineering. Such a material enhances the ability of progenitor cells to differentiate down an osteoblast lineage in vitro and in vivo, compared with polymer scaffolds. The mechanisms regulating mineral formation in this one-step process, however, are poorly understood, especially the effects of ionic activity products (IP) of the mineralizing solution and incubation time. The aims of this study were to define the structure and composition of mineral formed within the pores of biodegradable polymer scaffolds as a function of IP and time. Three-dimensional poly(lactide-co-glycolide) scaffolds were fabricated by solvent casting/particulate leaching and incubated for 4–16 days in six variants of simulated body fluid whose IPs were varied by adjusting ionic concentrations. Scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy demonstrated the formation of carbonated apatite with sub-micrometer sized crystals that grew into spherical globules extending out of the scaffold pore surfaces. As IP increased, more mineral grew on the scaffold pore surfaces, but the apatite became less crystalline and the Ca/P molar ratio decreased from 1.63 ± 0.005 to 1.51 ± 0.002. Since morphology, composition, and structure of mineral are factors that affect cell function, this study demonstrates that the IP of the mineralizing solution is an important modulator of material properties, potentially leading to enhanced control of cell function. PMID:17584901

Ion distributions in electrolyte confined by multiple dielectric interfaces

NASA Astrophysics Data System (ADS)

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

2014-03-01

The distribution of ions at dielectric interfaces between liquids characterized by different dielectric permittivities is crucial to nanoscale assembly processes in many biological and synthetic materials such as cell membranes, colloids and oil-water emulsions. The knowledge of ionic structure of these systems is also exploited in energy storage devices such as double-layer super-capacitors. The presence of multiple dielectric interfaces often complicates computing the desired ionic distributions via simulations or theory. Here, we use coarse-grained models to compute the ionic distributions in a system of electrolyte confined by two planar dielectric interfaces using Car-Parrinello molecular dynamics simulations and liquid state theory. We compute the density profiles for various electrolyte concentrations, stoichiometric ratios and dielectric contrasts. The explanations for the trends in these profiles and discuss their effects on the behavior of the confined charged fluid are also presented.

Calorimetric Studies and Structural Aspects of Ionic Liquids in Designing Sorption Materials for Thermal Energy Storage.

PubMed

Brünig, Thorge; Krekić, Kristijan; Bruhn, Clemens; Pietschnig, Rudolf

2016-11-02

The thermal properties of a series of twenty-four ionic liquids (ILs) have been determined by isothermal titration calorimetry (ITC) with the aim of simulating processes involving water sorption. For eleven water-free ILs, the molecular structures have been determined by X-ray crystallography in the solid state, which have been used to derive the molecular volumes of the ionic components of the ILs. Moreover, the structures reveal a high prevalence of hydrogen bonding in these compounds. A relationship between the molecular volumes and the experimentally determined energies of dilution could be established. The highest energies of dilution observed in this series were obtained for the acetate-based ILs, which underlines their potential as working fluids in sorption-based thermal energy storage systems. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Integral equation model for warm and hot dense mixtures.

PubMed

Starrett, C E; Saumon, D; Daligault, J; Hamel, S

2014-09-01

In a previous work [C. E. Starrett and D. Saumon, Phys. Rev. E 87, 013104 (2013)] a model for the calculation of electronic and ionic structures of warm and hot dense matter was described and validated. In that model the electronic structure of one atom in a plasma is determined using a density-functional-theory-based average-atom (AA) model and the ionic structure is determined by coupling the AA model to integral equations governing the fluid structure. That model was for plasmas with one nuclear species only. Here we extend it to treat plasmas with many nuclear species, i.e., mixtures, and apply it to a carbon-hydrogen mixture relevant to inertial confinement fusion experiments. Comparison of the predicted electronic and ionic structures with orbital-free and Kohn-Sham molecular dynamics simulations reveals excellent agreement wherever chemical bonding is not significant.

Deionization and desalination using electrostatic ion pumping

DOEpatents

Bourcier, William L.; Aines, Roger D.; Haslam, Jeffery J.; Schaldach, Charlene M.; O& #x27; Brien, Kevin C.; Cussler, Edward

2013-06-11

The present invention provides a new method and apparatus/system for purifying ionic solutions, such as, for example, desalinating water, using engineered charged surfaces to sorb ions from such solutions. Surface charge is applied externally, and is synchronized with oscillatory fluid movements between substantially parallel charged plates. Ions are held in place during fluid movement in one direction (because they are held in the electrical double layer), and released for transport during fluid movement in the opposite direction by removing the applied electric field. In this way the ions, such as salt, are "ratcheted" across the charged surface from the feed side to the concentrate side. The process itself is very simple and involves only pumps, charged surfaces, and manifolds for fluid collection.

Deionization and desalination using electrostatic ion pumping

DOEpatents

Bourcier, William L [Livermore, CA; Aines, Roger D [Livermore, CA; Haslam, Jeffery J [Livermore, CA; Schaldach, Charlene M [Pleasanton, CA; O'Brien, Kevin C [San Ramon, CA; Cussler, Edward [Edina, MN

2011-07-19

The present invention provides a new method and apparatus/system for purifying ionic solutions, such as, for example, desalinating water, using engineered charged surfaces to sorb ions from such solutions. Surface charge is applied externally, and is synchronized with oscillatory fluid movements between substantially parallel charged plates. Ions are held in place during fluid movement in one direction (because they are held in the electrical double layer), and released for transport during fluid movement in the opposite direction by removing the applied electric field. In this way the ions, such as salt, are "ratcheted" across the charged surface from the feed side to the concentrate side. The process itself is very simple and involves only pumps, charged surfaces, and manifolds for fluid collection.

Laboratory comparison of several tests for evaluating the transport properties of concrete.

DOT National Transportation Integrated Search

2006-01-01

The transport properties of concrete are a primary element in determining the durability of concrete. In this study, several new test methods that directly measure aspects of fluid and ionic transport in concrete were examined. ASTM C 1543 and ASTM C...

Solid-to-fluid DNA transition inside HSV-1 capsid close to the temperature of infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sae-Ueng, Udom; Li, Dong; Zuo, Xiaobing

2014-10-01

DNA in the human Herpes simplex virus type 1 (HSV-1) capsid is packaged to a tight density. This leads to tens of atmospheres of internal pressure responsible for the delivery of the herpes genome into the cell nucleus. In this study we show that, despite its liquid crystalline state inside the capsid, the DNA is fluid-like, which facilitates its ejection into the cell nucleus during infection. We found that the sliding friction between closely packaged DNA strands, caused by interstrand repulsive interactions, is reduced by the ionic environment of epithelial cells and neurons susceptible to herpes infection. However, variations inmore » the ionic conditions corresponding to neuronal activity can restrict DNA mobility in the capsid, making it more solid-like. This can inhibit intranuclear DNA release and interfere with viral replication. In addition, the temperature of the human host (37 °C) induces a disordering transition of the encapsidated herpes genome, which reduces interstrand interactions and provides genome mobility required for infection.« less

Ion association at discretely-charged dielectric interfaces: Giant charge inversion [Dielectric response controlled ion association at physically heterogeneous surfaces: Giant charge reversal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhi -Yong; Wu, Jianzhong

2017-07-11

Giant charge reversal has been identified for the first time by Monte Carlo simulation for a discretely charged surface in contact with a trivalent electrolyte solution. It takes place regardless of the surface charge density under study and the monovalent salt. In stark contrast to earlier predictions based on the 2-dimensional Wigner crystal model to describe strong correlation of counterions at the macroion surface, we find that giant charge reversal reflects an intricate interplay of ionic volume effects, electrostatic correlations, surface charge heterogeneity, and the dielectric response of the confined fluids. While the novel phenomenon is yet to be confirmedmore » with experiment, the simulation results appear in excellent agreement with a wide range of existing observations in the subregime of charge inversion. Lastly, our findings may have far-reaching implications to understanding complex electrochemical phenomena entailing ionic fluids under dielectric confinements.« less

A near infrared holographic glucose sensor.

PubMed

Vezouviou, Evangelia; Lowe, Christopher R

2015-06-15

Real-time glucose monitoring has been beneficial in reducing health complications associated with diabetes as well as a decrease in mortality. This report describes a novel holographic platform, fabricated via laser ablation on chitosan hydrogel with gold nanoparticles with a replaying in visible and near IR. The sensor responded with a 12 nm and 7 nm shift in wavelength at glucose concentrations in the 0-70 mM range and in the visible and near IR, respectively, at pH 7.4 and an ionic strength of 154 mM. The sensor did not respond to potential interferences found in the interstitial fluid, such as fructose, vitamin C and lactate, at their respective normal concentrations and was stable to fluctuations in temperature, pH and ionic strength. The characteristics of this sensor suggests that it may be applicable for use as an implanted device for the real time monitoring of glucose concentrations in the interstitial fluid using near IR as the interrogating medium. Copyright © 2015 Elsevier B.V. All rights reserved.

Mesoscale studies of ionic closed membranes with polyhedral geometries

DOE PAGES

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 coassembling 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.

Effect of additives on eremomycin sorbent selectivity in separation of salbutamol enantiomers using supercritical fluid chromatography

NASA Astrophysics Data System (ADS)

Pokrovskiy, O. I.; Kayda, A. S.; Usovich, O. I.; Parenago, O. O.; Lunin, V. V.

2017-11-01

A regime is found in which chiral stationary phase based on macrocyclic glycopeptide eremomycin allows separation of salbutamol sulfate enantiomers in supercritical fluid chromatography. Enantioseparation occurs only when two dynamic modifiers are used simultaneously: isopropylamin + trifluoroacetic acid or isopropylamin + ammonium acetate. Amine molar concentration in mobile phase has to be higher than acid molar concentration, otherwise enantiomers coelute. We suppose that with amine excess a mechanism of enantiorecognition is realized which involves ionic sorbent-sorbate interactions. Such mechanism is well-known for glycopeptide chiral selectors in liquid chromatography, but for supercritical fluid chromatography it is reported for the first time.

Systems and methods for selective hydrogen transport and measurement

DOEpatents

Glatzmaier, Gregory C

2013-10-29

Systems and methods for selectively removing hydrogen gas from a hydrogen-containing fluid volume are disclosed. An exemplary system includes a proton exchange membrane (PEM) selectively permeable to hydrogen by exclusively conducting hydrogen ions. The system also includes metal deposited as layers onto opposite sides or faces of the PEM to form a membrane-electrode assembly (MEA), each layer functioning as an electrode so that the MEA functions as an electrochemical cell in which the ionic conductors are hydrogen ions, and the MEA functioning as a hydrogen selective membrane (HSM) when located at the boundary between a hydrogen-containing fluid volume and a second fluid.

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

Pharmacological characterization of ionic currents that regulate high-frequency spontaneous activity of electromotor neurons in the weakly electric fish, Apteronotus leptorhynchus.

PubMed

Smith, G Troy

2006-01-01

The neural circuit that controls the electric organ discharge (EOD) of the brown ghost knifefish (Apteronotus leptorhynchus) contains two spontaneous oscillators. Both pacemaker neurons in the medulla and electromotor neurons (EMNs) in the spinal cord fire spontaneously at frequencies of 500-1,000 Hz to control the EOD. These neurons continue to fire in vitro at frequencies that are highly correlated with in vivo EOD frequency. Previous studies used channel blocking drugs to pharmacologically characterize ionic currents that control high-frequency firing in pacemaker neurons. The goal of the present study was to use similar techniques to investigate ionic currents in EMNs, the other type of spontaneously active neuron in the electromotor circuit. As in pacemaker neurons, high-frequency firing of EMNs was regulated primarily by tetrodotoxin-sensitive sodium currents and by potassium currents that were sensitive to 4-aminopyridine and kappaA-conotoxin SIVA, but resistant to tetraethylammonium. EMNs, however, differed from pacemaker neurons in their sensitivity to some channel blocking drugs. Alpha-dendrotoxin, which blocks a subset of Kv1 potassium channels, increased firing rates in EMNs, but not pacemaker neurons; and the sodium channel blocker muO-conotoxin MrVIA, which reduced firing rates of pacemaker neurons, had no effect on EMNs. These results suggest that similar, but not identical, ionic currents regulate high-frequency firing in EMNs and pacemaker neurons. The differences in the ionic currents expressed in pacemaker neurons and EMNs might be related to differences in the morphology, connectivity, or function of these two cell types.

Geometry effect on electrokinetic flow and ionic conductance in pH-regulated nanochannels

NASA Astrophysics Data System (ADS)

Sadeghi, Morteza; Saidi, Mohammad Hassan; Moosavi, Ali; Sadeghi, Arman

2017-12-01

Semi-analytical solutions are obtained for the electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties associated with long pH-regulated nanochannels of arbitrary but constant cross-sectional area. The effects of electric double layer overlap, multiple ionic species, and surface association/dissociation reactions are all taken into account, assuming low surface potentials. The method of analysis includes series solutions which the pertinent coefficients are obtained by applying the wall boundary conditions using either of the least-squares or point matching techniques. Although the procedure is general enough to be applied to almost any arbitrary cross section, nine nanogeometries including polygonal, trapezoidal, double-trapezoidal, rectangular, elliptical, semi-elliptical, isosceles triangular, rhombic, and isotropically etched profiles are selected for presentation. For the special case of an elliptic cross section, full analytical solutions are also obtained utilizing the Mathieu functions. We show that the geometrical configuration plays a key role in determination of the ionic conductance, surface charge density, electrical potential and velocity fields, and proton enhancement. In this respect, the net electric charge and convective ionic conductance are higher for channels of larger perimeter to area ratio, whereas the opposite is true for the average surface charge density and mean velocity; the geometry impact on the two latest ones, however, vanishes if the background salt concentration is high enough. Moreover, we demonstrate that considering a constant surface potential equal to the average charge-regulated potential provides sufficiently accurate results for smooth geometries such as an ellipse at medium-high aspect ratios but leads to significant errors for geometries having narrow corners such as a triangle.

Cellular and molecular responses of adult zebrafish after exposure to CuO nanoparticles or ionic copper.

PubMed

Vicario-Parés, Unai; Lacave, Jose M; Reip, Paul; Cajaraville, Miren P; Orbea, Amaia

2018-01-01

Due to their antimicrobial, electrical and magnetic properties, copper nanoparticles (NPs) are suitable for a vast array of applications. Copper can be toxic to biota, making it necessary to assess the potential hazard of copper nanomaterials. Zebrafish (Danio rerio) were exposed to 10 µg Cu/L of CuO NPs of ≈100 nm (CuO-poly) or ionic copper to compare the effects provoked after 3 and 21 days of exposure and at 6 months post-exposure (mpe). At 21 days, significant copper accumulation was only detected in fish exposed to ionic copper. Exposure to both copper forms caused histopathological alterations that could reduce gill functionality, more markedly in the case of ionic copper. Nevertheless, at 6 mpe higher prevalences of gill lesions were detected in fish previously exposed to CuO-poly NPs. No relevant histological alterations were detected in liver, but the lysosomal membrane stability test showed significantly impaired general health status after exposure to both metal forms that lasted up to 6 mpe. 69 transcripts appeared regulated after 3 days of exposure to CuO-poly NPs, suggesting that NPs could produce oxidative stress and reduce metabolism and transport processes. Thirty transcripts were regulated after 21 days of exposure to ionic copper, indicating possible DNA damage. Genes of the circadian clock were identified as the key genes involved in time-dependent differences between the two copper forms. In conclusion, each copper form showed a distinct pattern of liver transcriptome regulation, but both caused gill histopathological alterations and long lasting impaired health status in adult zebrafish.

LABORATORY AND FIELD RESULTS LINKING HIGH BULK CONDUCTIVITIES TO THE MICROBIAL DEGRADATION OF PETROLEUM HYDROCARBONS

EPA Science Inventory

Diesel contaminated layer (i.e. 32-45 cm) was the most geoelectrically conductive and showed the peak microbial activity. Below the saturated zone microbial enhanced mineral weathering increases the ionic concentration of pore fluids, leading to increased bulk electrical conducit...

A classical density functional theory for the asymmetric restricted primitive model of ionic liquids

NASA Astrophysics Data System (ADS)

Lu, Hongduo; Nordholm, Sture; Woodward, Clifford E.; Forsman, Jan

2018-05-01

A new three-parameter (valency, ion size, and charge asymmetry) model, the asymmetric restricted primitive model (ARPM) of ionic liquids, has recently been proposed. Given that ionic liquids generally are composed of monovalent species, the ARPM effectively reduces to a two-parameter model. Monte Carlo (MC) simulations have demonstrated that the ARPM is able to reproduce key properties of room temperature ionic liquids (RTILs) in bulk and at charged surfaces. The relatively modest complexity of the model raises the possibility, which is explored here, that a classical density functional theory (DFT) could resolve its properties. This is relevant because it might generate great improvements in terms of both numerical efficiency and understanding in the continued research of RTILs and their applications. In this report, a DFT for rod-like molecules is proposed as an approximate theoretical tool for an ARPM fluid. Borrowing data on the ion pair fraction from a single bulk simulation, the ARPM is modelled as a mixture of dissociated ions and connected ion pairs. We have specifically studied an ARPM where the hard-sphere diameter is 5 Å, with the charge located 1 Å from the hard-sphere centre. We focus on fluid structure and electrochemical behaviour of this ARPM fluid, into which a model electrode is immersed. The latter is modelled as a perfect conductor, and surface polarization is handled by the method of image charges. Approximate methods, which were developed in an earlier study, to take image interactions into account, are also incorporated in the DFT. We make direct numerical comparisons between DFT predictions and corresponding simulation data. The DFT theory is implemented both in the normal mean field form with respect to the electrostatic interactions and in a correlated form based on hole formation by both steric repulsions and ion-ion Coulomb interactions. The results clearly show that ion-ion correlations play a very important role in the screening of the charged surfaces by our ARPM ionic liquid. We have studied electrostatic potentials and ion density profiles as well the differential capacitance. The mean-field DFT fails to reproduce these properties, but the inclusion of ion-ion correlation by a simple approximate treatment yields quite reasonable agreement with the corresponding simulation results. An interesting finding is that there appears to be a surface phase transition at relatively low surface charge which is readily explored by DFT, but seen also in the MC simulations at somewhat higher asymmetry.

Investigating the development of less-mobile porosity in realistic hyporheic zone sediments with COMSOL Multiphysics

NASA Astrophysics Data System (ADS)

MahmoodPoorDehkordy, F.; Briggs, M. A.; Day-Lewis, F. D.; Bagtzoglou, A. C.

2017-12-01

Although hyporheic zones are often modeled at the reach scale as homogeneous "boxes" of exchange, heterogeneity caused by variations of pore sizes and connectivity is not uncommon. This heterogeneity leads to the creation of more- and less-mobile zones of hydraulic exchange that influence reactive solute transport processes. Whereas fluid sampling is generally sensitive to more-mobile zones, geoelectrical measurement is sensitive to ionic tracer dynamics in both less- and more-mobile zones. Heterogeneity in pore connectivity leads to a lag between fluid and bulk electrical conductivity (EC) resulting in a hysteresis loop, observed during tracer breakthrough tests, that contains information about the less-mobile porosity attributes of the medium. Here, we present a macro-scale model of solute transport and electrical conduction developed using COMSOL Multiphysics. The model is used to simulate geoelectrical monitoring of ionic transport for bed sediments based on (1) a stochastic sand-and-cobble mixture and (2) a dune feature with strong permeability layering. In both of these disparate sediment types, hysteresis between fluid and bulk EC is observed, and depends in part on fluid flux rate through the model domain. Using the hysteresis loop, the ratio of less-mobile to mobile porosity and mass-transfer coefficient are estimated graphically. The results indicate the presence and significance of less-mobile porosity in the hyporheic zones and demonstrate the capability of the proposed model to detect heterogeneity in flow processes and estimate less-mobile zone parameters.

Ionic charge accumulation at microscopic interfaces in filled composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu Yutao; Wang Xinheng; Xie Hengkun

1996-12-31

In this paper the charge accumulation process at microscopic interfaces in insulating materials filled with inorganic fillers is analyzed by using a unit model. Dynamic equations of interfacial ionic charge accumulation are proposed by the authors. The charge accumulation and its regulations are proved by TSC test results obtained on silica filled EPDM samples.

Communication: Modeling electrolyte mixtures with concentration dependent dielectric permittivity

NASA Astrophysics Data System (ADS)

Chen, Hsieh; Panagiotopoulos, Athanassios Z.

2018-01-01

We report a new implicit-solvent simulation model for electrolyte mixtures based on the concept of concentration dependent dielectric permittivity. A combining rule is found to predict the dielectric permittivity of electrolyte mixtures based on the experimentally measured dielectric permittivity for pure electrolytes as well as the mole fractions of the electrolytes in mixtures. Using grand canonical Monte Carlo simulations, we demonstrate that this approach allows us to accurately reproduce the mean ionic activity coefficients of NaCl in NaCl-CaCl2 mixtures at ionic strengths up to I = 3M. These results are important for thermodynamic studies of geologically relevant brines and physiological fluids.

The susceptibility critical exponent for a nonaqueous ionic binary mixture near a consolute point

NASA Technical Reports Server (NTRS)

Zhang, Kai C.; Briggs, Matthew E.; Gammon, Robert W.; Levelt Sengers, J. M. H.

1992-01-01

We report turbidity measurements of a nonaqueous ionic solution of triethyl n-hexylammonium triethyl n-hexylboride in diphenyl ether. A classical susceptibility critical exponent gamma = 1.01 +/- 0.01 is obtained over the reduced temperature range t between values of 0.1 and 0.0001. The best fits of the sample transmission had a standard deviation of 0.39 percent over this range. Ising and spherical model critical exponents are firmly excluded. The correlation length amplitude xi sub 0 from fitting is 1.0 +/- 0.2 nm which is much larger than values found in neutral fluids and some aqueous binary mixtures.

Proton exchange membrane based on chitosan and solvent-free carbon nanotube fluids for fuel cells applications.

PubMed

Wang, Jie; Gong, Chunli; Wen, Sheng; Liu, Hai; Qin, Caiqin; Xiong, Chuanxi; Dong, Lijie

2018-04-15

Poor dispersion and inert ionic conduction are two major obstacles towards using carbon nanotubes (CNTs) to modify polymer electrolyte membranes (PEMs) in energy conversion devices. In this work, solvent-free carbon nanotube fluids (CNT fluids) with liquid-like behavior are prepared through an ion exchange method and incorporated into a chitosan (CS) matrix to fabricate composite membranes. The electrostatic interactions between SO 3 - groups in the CNT fluids and NH 2 groups in the CS matrix, in addition to the unique flow properties of the CNT fluids, promote the uniform dispersion of CNT fluids in the CS matrix. Markedly, the CS/CNT fluid-3 composite membrane is simultaneously reinforced and toughened by 180% and 300% compared to pure CS membrane, respectively. Moreover, the SO 3 - groups in the CNT fluids facilitate the proton transfer such that the proton conductivity of CS/CNT fluid-3 composite membrane reaches a maximum value of 0.044 S cm -1 at 80 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ice Detector and Deicing Fluid Effectiveness Monitoring System

NASA Technical Reports Server (NTRS)

Seegmiller, H. Lee B. (Inventor)

1996-01-01

An ice detector and deicing fluid effectiveness monitoring system for an aircraft is disclosed. The ice detection portion is particularly suited for use in flight to notify the flight crew of an accumulation of ice on an aircraft lifting and control surfaces, or helicopter rotors, whereas the deicing fluid effectiveness monitoring portion is particularly suited for use on the ground to notify the flight crew of the possible loss of the effectiveness of the deicing fluid. The ice detection portion comprises a temperature sensor and a parallel arrangement of electrodes whose coefficient of coupling is indicative of the formation of the ice, as well as the thickness of the formed ice. The fluid effectiveness monitoring portion comprises a temperature sensor and an ionic-conduction cell array that measures the conductivity of the deicing fluid which is indicative of its concentration and, thus, its freezing point. By measuring the temperature and having knowledge of the freezing point of the deicing fluid, the fluid effectiveness monitoring portion predicts when the deicing fluid may lose its effectiveness because its freezing point may correspond to the temperature of the ambient.

Chemistry--The Big Picture

ERIC Educational Resources Information Center

Cassell, Anne

2011-01-01

Chemistry produces materials and releases energy by ionic or electronic rearrangements. Three structure types affect the ease with which a reaction occurs. In the Earth's crust, "solid crystals" change chemically only with extreme heat and pressure, unless their fixed ions touch moving fluids. On the other hand, in living things, "liquid crystals"…

Ether- and Alcohol-Functionalized Task-Specific Ionic Liquids: Attractive Properties and Applications

PubMed Central

Tang, Shaokun; Baker, Gary A.; Zhao, Hua

2012-01-01

In recent years, the designer nature of ionic liquids (ILs) has driven their exploration and exploitation in countless fields among the physical and chemical sciences. A fair measure of the tremendous attention placed on these fluids has been attributed to their inherent designer nature. And yet, there are relatively few examples of reviews which emphasize this vital aspect in an exhaustive or meaningful way. In this critical review, we systematically survey the physicochemical properties of the collective library of ether- and alcohol-functionalized ILs, highlighting the impact of ionic structure on features such as viscosity, phase behavior/transitions, density, thermostability, electrochemical properties, and polarity (e.g., hydrophilicity, hydrogen bonding capability). In the latter portions of this review, we emphasize the attractive applications of these functionalized ILs across a range of disciplines, including their use as electrolytes or functional fluids for electrochemistry, extractions, biphasic systems, gas separations, carbon capture, carbohydrate dissolution (particularly, the (ligno)celluloses), polymer chemistry, antimicrobial and antielectrostatic agents, organic synthesis, biomolecular stabilization and activation, and nanoscience. Finally, this review discusses anion-functionalized ILs, including sulfur- and oxygen-functionalized analogs, as well as choline-based deep eutectic solvents (DESs), an emerging class of fluids which can be sensibly categorized as semi-molecular cousins to the IL. Finally, the toxicity and biodegradability of ether- and alcohol-functionalized ILs are discussed and cautiously evaluated in light of recent reports. By carefully summarizing literature examples on the properties and applications of oxy-functional designer ILs up till now, it is our intent that this review offer a barometer for gauging future advances in the field as well as a trigger to spur further contemplation of these seemingly inexhaustible and—relative to their potential—virtually untouched fluids. It is abundantly clear that these remarkable fluidic materials are here to stay, just as certain design rules are slowly beginning to emerge. However, in fairness, serendipity also still plays an undeniable role, highlighting the need for both expanded in silico studies and a beacon to attract bright, young researchers to the field. PMID:22456483

Structural interactions in ionic liquids linked to higher-order Poisson-Boltzmann equations

NASA Astrophysics Data System (ADS)

Blossey, R.; Maggs, A. C.; Podgornik, R.

2017-06-01

We present a derivation of generalized Poisson-Boltzmann equations starting from classical theories of binary fluid mixtures, employing an approach based on the Legendre transform as recently applied to the case of local descriptions of the fluid free energy. Under specific symmetry assumptions, and in the linearized regime, the Poisson-Boltzmann equation reduces to a phenomenological equation introduced by Bazant et al. [Phys. Rev. Lett. 106, 046102 (2011)], 10.1103/PhysRevLett.106.046102, whereby the structuring near the surface is determined by bulk coefficients.

Osmotic regulation of gene action.

PubMed

Douzou, P

1994-03-01

Most reactions involved in gene translation systems are ionic-dependent and may be explained in electrostatic terms. However, a number of observations of equilibria and rate processes making up the overall reactions clearly indicate that there is still an enormous gap between the rough picture of the mechanism of ionic regulation and the detailed behavior of reactions at the molecular level that hold the key to specific mechanisms. The present paper deals with possible osmotic contributions arising from the gel state of gene systems that are complementary to, and interdependent of, electrostatic contributions. This treatment, although still oversimplified, explains many previous observations by relating them to a general osmotic mechanism and suggests experimental approaches to studying the mechanisms of gene regulation in organelle-free and intact systems.

Implementation of physiological fluids to provide insight into the characterization, fate, and biological interactions of silver nanoparticles.

PubMed

Breitner, Emily K; Burns, Katherine E; Hussain, Saber M; Comfort, Kristen K

2018-06-22

Silver nanoparticles (AgNPs) are being increasingly utilized in consumer and medical applications. However, there remains conflicting reports on their safety, which are evaluated through a combination of in vitro and in vivo exposure models. These discrepancies may arise, in part, due to the inherent differences between cell-based and animal systems. It is well established that nanotoxicological effects are highly dependent on the unique physicochemical properties and behavior of the particle set, including size, surface chemistry, agglomeration, and ionic dissolution. However, recent studies have identified that these properties vary as a function of exposure environment; providing a rationale for the contradictory results between in vitro and in vivo assessments. Artificial physiological fluids are emerging as a powerful tool as they allow for the characterization of NPs in an environment which they would likely encounter in vivo, in addition to having the experimental advantages of flexibility and consistency. Here, we demonstrated that the utilization of artificial fluids provided a mechanism to assess AgNP behavior and induced bioresponses in environments that they would likely encounter in vivo. AgNPs were introduced within an alveolar-based exposure model, which included alveolar epithelial (A549) cells incubated within artificial alveolar fluid (AF). Additionally, the particles underwent extensive characterization within both AF and lysosomal fluid, which the AgNPs would encounter following cellular internalization. Following incubation in physiological environments AgNP properties were significantly modified versus a traditional media environment, including alterations to both extent of agglomeration and rate of ionic dissolution. Moreover, when A549s were exposed to AgNPs in AF, the cells displayed lower cytotoxicity and stress rates, corresponding to a fluid-dependent drop in silver ion production. This work highlights the need for enhanced in vitro models that more closely mimic in vivo exposure environments in order to capture true NP behaviors and cellular interactions.

Implementation of physiological fluids to provide insight into the characterization, fate, and biological interactions of silver nanoparticles

NASA Astrophysics Data System (ADS)

Breitner, Emily K.; Burns, Katherine E.; Hussain, Saber M.; Comfort, Kristen K.

2018-06-01

Silver nanoparticles (AgNPs) are being increasingly utilized in consumer and medical applications. However, there remains conflicting reports on their safety, which are evaluated through a combination of in vitro and in vivo exposure models. These discrepancies may arise, in part, due to the inherent differences between cell-based and animal systems. It is well established that nanotoxicological effects are highly dependent on the unique physicochemical properties and behavior of the particle set, including size, surface chemistry, agglomeration, and ionic dissolution. However, recent studies have identified that these properties vary as a function of exposure environment; providing a rationale for the contradictory results between in vitro and in vivo assessments. Artificial physiological fluids are emerging as a powerful tool as they allow for the characterization of NPs in an environment which they would likely encounter in vivo, in addition to having the experimental advantages of flexibility and consistency. Here, we demonstrated that the utilization of artificial fluids provided a mechanism to assess AgNP behavior and induced bioresponses in environments that they would likely encounter in vivo. AgNPs were introduced within an alveolar-based exposure model, which included alveolar epithelial (A549) cells incubated within artificial alveolar fluid (AF). Additionally, the particles underwent extensive characterization within both AF and lysosomal fluid, which the AgNPs would encounter following cellular internalization. Following incubation in physiological environments AgNP properties were significantly modified versus a traditional media environment, including alterations to both extent of agglomeration and rate of ionic dissolution. Moreover, when A549s were exposed to AgNPs in AF, the cells displayed lower cytotoxicity and stress rates, corresponding to a fluid-dependent drop in silver ion production. This work highlights the need for enhanced in vitro models that more closely mimic in vivo exposure environments in order to capture true NP behaviors and cellular interactions.

Quantifying the effects of altering ambient humidity on ionic composition of vocal fold surface fluid.

PubMed

Sivasankar, M Preeti; Carroll, Thomas L; Kosinski, Aaron M; Rosen, Clark A

2013-07-01

Vocal fold surface fluid (VFSF) is important in hydration and defense of underlying epithelial cells. The objective of this study was to quantify changes in the ionic composition of VFSF after altering the humidity of inhaled air. We tested the hypothesis that low humidity exposure would increase the concentration of VFSF sodium (Na(+)) and chloride (Cl(-)) ions but that high humidity exposure would decrease the concentration of VFSF Na(+) and Cl(-) ions as compared to the low humidity challenge. Prospective design. Eighteen healthy adults participated in this study. VFSF was collected from each subject at baseline and following exposure to low humidity and high humidity environments. VFSF Na(+) concentration was assessed using inductively coupled plasma mass spectrometry. VFSF Cl(-) concentration was measured with indirect potentiometry. All analyses were completed by personnel blinded to the hypothesis being tested. The low humidity environment increased Na(+) concentration in the majority of the subjects. Data for changes in Cl(-) concentrations were variable. Overall the data did not reach statistical significance (P > .05). Subjective impressions suggested that VFSF collection was more difficult in low humidity as compared to the high humidity and baseline conditions. This study is the first attempt to measure the ionic concentration of VFSF. The results from the current study have important implications for future programmatic research quantifying the effects of pollutants and laryngopharyngeal reflux on VFSF composition, epithelial hydration, and vocal fold defense. Copyright © 2012 The American Laryngological, Rhinological and Otological Society, Inc.

Quantifying the Effects of Altering Ambient Humidity on Ionic Composition of Vocal Fold Surface Fluid

PubMed Central

Sivasankar, M. Preeti; Carroll, Thomas L.; Kosinski, Aaron M.; Rosen, Clark A.

2013-01-01

Objective Vocal fold surface fluid (VFSF) is important in hydration and defense of underlying epithelial cells. The objective of this study was to quantify changes in the ionic composition of VFSF after altering the humidity of inhaled air. We tested the hypothesis that low humidity exposure would increase the concentration of VFSF sodium (Na+) and chloride (Cl−) ions but that high humidity exposure would decrease the concentration of VFSF Na+ and Cl− ions as compared to the low humidity challenge. Study Design Prospective design. Methods Eighteen healthy adults participated in this study. VFSF was collected from each subject at baseline, and following exposure to low humidity and high humidity environments. VFSF Na+ concentration was assessed using inductively-coupled plasma mass spectrometry. VFSF Cl− concentration was measured with indirect potentiometry. All analyses were completed by personnel blinded to the hypothesis being tested. Results The low humidity environment increased Na+ concentration in the majority of the subjects. Data for changes in Cl− concentrations were variable. Overall the data did not reach statistical significance (p > 0.05). Subjective impressions suggested that VFSF collection was more difficult in low humidity as compared to the high humidity and baseline conditions. Conclusions This study is the first attempt to measure the ionic concentration of VFSF. The results from the current study have important implications for future programmatic research quantifying the effects of pollutants and laryngopharyngeal reflux on VFSF composition, epithelial hydration, and vocal fold defense. PMID:23529891

A numerical method for electro-kinetic flow with deformable fluid interfaces

NASA Astrophysics Data System (ADS)

Booty, Michael; Ma, Manman; Siegel, Michael

2013-11-01

We consider two-phase flow of ionic fluids whose motion is driven by an imposed electric field. At a fluid interface, a screening cloud of ions develops and forms an electro-chemical double layer or Debye layer. The imposed field acts on this induced charge distribution, resulting in a strong slip flow near the interface. We formulate a ``hybrid'' or multiscale numerical method in the thin Debye layer limit that incorporates an asymptotic analysis of the electrostatic potential and fluid dynamics in the Debye layer into a boundary integral solution of the full moving boundary problem. Results of the method are presented that show time-dependent deformation and steady state drop interface shapes when the timescale for charge-up of the Debye layer is either much less than or comparable to the timescale of the flow.

Metal Complexation in Xylem Fluid 1

PubMed Central

White, Michael C.; Decker, A. Morris; Chaney, Rufus L.

1981-01-01

Xylem fluid was analyzed for numerous solutes to characterize chemically the sap as a medium for forming and transporting metal complexes. The stem exudate was collected hourly for 8 hours from topped 31-day-old soybean (Glycine max L. Merr.) and 46-day-old tomato (Lycopersicon esculentum Mill.) plants grown in normal (0.5 micromolar) and Za-phytotoxic nutrient solutions. Soybean plants were grown in the normal and high-Zn solutions for 24 days; tomato plants were grown for 32 days. The exudate was analyzed for seven organic acids, 22 amino acids, eight inorganic solutes, apparent ionic strength, and pH. Significant changes in many solutes occurred over the 8-hour sampling period. These fluctuations depended on plant species, individual solute, and Zn treatment, and demonstrated that extrapolation of xylem-fluid analyses to whole-plant xylem sap is valid only for sap samples collected shortly after topping a plant. Exudate pH decreased over the 8-hour period for both species; exudate ionic strength increased for tomato and decreased for soybean. At the normal-Zn treatment (0 to 1 hour), the highest acid micromolar concentrations in soybean exudate were: asparagine, 2,583; citric, 1,706; malic, 890; and malonic, 264. Under the same conditions, the highest acid micromolar concentrations in tomato exudate were: maleic, 1,206; malic, 628; glutamine, 522; citric, 301; and asparagine, 242. Cysteine and methionine were above detection limits only in soybean exudate. Zinc phytotoxicity caused significant changes in many solutes. The analyses reported here provide a comprehensive data base for further studies on metal-complex equilibria in xylem fluid. PMID:16661664

Slow dynamics approaching the glass transition in repulsive magnetic fluids

NASA Astrophysics Data System (ADS)

Mériguet, G.; Dubois, E.; Dupuis, V.; Perzynski, R.

2004-04-01

We study the dynamics of concentrated ionic magnetic colloidal dispersions, which are constituted of γ - Fe2O3 nanoparticles dispersed in water, and stabilized with electrostatic interparticle repulsion, using magneto-optical birefringence measurements. By gradually increasing the volume fraction Φ of the particles at constant ionic strength in the repulsive region of the phase diagram, we observe a dramatic increase of the characteristic time associated with the rotation of the particles that we induce by applying a field pulse. This increase is reminiscent of the divergence of the relaxation time observed at the approach of a glass transition and confirms the existence of a glassy phase in these magnetic colloids.

Spatial inhomogeneities in ionic liquids, charged proteins, and charge stabilized colloids from collective variables theory.

PubMed

Patsahan, O; Ciach, A

2012-09-01

Effects of size and charge asymmetry between oppositely charged ions or particles on spatial inhomogeneities are studied for a large range of charge and size ratios. We perform a stability analysis of the primitive model of ionic systems with respect to periodic ordering using the collective variables-based theory. We extend previous studies [Ciach et al., Phys. Rev. E 75, 051505 (2007)] in several ways. First, we employ a nonlocal approximation for the reference hard-sphere fluid which leads to the Percus-Yevick pair direct correlation functions for the uniform case. Second, we use the Weeks-Chandler-Anderson regularization scheme for the Coulomb potential inside the hard core. We determine the relevant order parameter connected with the periodic ordering and analyze the character of the dominant fluctuations along the λ lines. We show that the above-mentioned modifications produce large quantitative and partly qualitative changes in the phase diagrams obtained previously. We discuss possible scenarios of the periodic ordering for the whole range of size and charge ratios of the two ionic species, covering electrolytes, ionic liquids, charged globular proteins or nanoparticles in aqueous solutions, and charge-stabilized colloids.

Novel Fission-Product Separation based on Room-Temperature Ionic Liquids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, Robin D.

2004-12-31

U.S. DOE's underground storage tanks at Hanford, SRS, and INEEL contain liquid wastes with high concentrations of radioactive cesium-137 and strontium-90. Because the primary chemical components of alkaline supernatants are sodium nitrate and sodium hydroxide, the majority of this could be disposed of as low level waste if radioactive cesium-137 and strontium- 90 could be selectively removed. The underlying goal of this project was to investigate the application of ionic liquids as novel solvents for new solvent extraction processes for separation of cesium-137 and strontium-90 from tank wastes. Ionic liquids are a distinct sub-set of liquids, comprising only of cationsmore » and anions they are proving to be increasingly interesting fluids for application in systems from electrochemistry to energetic materials, and are also rapidly establishing their promise as viable media for synthesis and separations operations. Properties including low melting points, electrochemical conductivity, wide liquid ranges, lack of vapor-pressure, and chemical tunability have encouraged researchers to explore the uses of ILs in place of volatile organic solvents. The most promising current developments arise from control of the unique combinations of chemical and physical properties characteristic of ionic liquids.« less

Hydrodynamic model of temperature change in open ionic channels.

PubMed Central

Chen, D P; Eisenberg, R S; Jerome, J W; Shu, C W

1995-01-01

Most theories of open ionic channels ignore heat generated by current flow, but that heat is known to be significant when analogous currents flow in semiconductors, so a generalization of the Poisson-Nernst-Planck theory of channels, called the hydrodynamic model, is needed. The hydrodynamic theory is a combination of the Poisson and Euler field equations of electrostatics and fluid dynamics, conservation laws that describe diffusive and convective flow of mass, heat, and charge (i.e., current), and their coupling. That is to say, it is a kinetic theory of solute and solvent flow, allowing heat and current flow as well, taking into account density changes, temperature changes, and electrical potential gradients. We integrate the equations with an essentially nonoscillatory shock-capturing numerical scheme previously shown to be stable and accurate. Our calculations show that 1) a significant amount of electrical energy is exchanged with the permeating ions; 2) the local temperature of the ions rises some tens of degrees, and this temperature rise significantly alters for ionic flux in a channel 25 A long, such as gramicidin-A; and 3) a critical parameter, called the saturation velocity, determines whether ionic motion is overdamped (Poisson-Nernst-Planck theory), is an intermediate regime (called the adiabatic approximation in semiconductor theory), or is altogether unrestricted (requiring the full hydrodynamic model). It seems that significant temperature changes are likely to accompany current flow in the open ionic channel. PMID:8599638

Composition pulse time-of-flight mass flow sensor

DOEpatents

Harnett, Cindy K [Livermore, CA; Crocker, Robert W [Fremont, CA; Mosier, Bruce P [San Francisco, CA; Caton, Pamela F [Berkeley, CA; Stamps, James F [Livermore, CA

2007-06-05

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 2,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined. A pair of spaced apart electrodes can be used to produce the electrochemical pulse. In those instances where it is desired to measure a wide range of fluid flow rates a three electrode configuration in which the electrodes are spaced at unequal distances has been found to be desirable.

Neural Control Mechanisms and Body Fluid Homeostasis

NASA Technical Reports Server (NTRS)

Johnson, Alan Kim

1998-01-01

The goal of the proposed research was to study the nature of afferent signals to the brain that reflect the status of body fluid balance and to investigate the central neural mechanisms that process this information for the activation of response systems which restore body fluid homeostasis. That is, in the face of loss of fluids from intracellular or extracellular fluid compartments, animals seek and ingest water and ionic solutions (particularly Na(+) solutions) to restore the intracellular and extracellular spaces. Over recent years, our laboratory has generated a substantial body of information indicating that: (1) a fall in systemic arterial pressure facilitates the ingestion of rehydrating solutions and (2) that the actions of brain amine systems (e.g., norepinephrine; serotonin) are critical for precise correction of fluid losses. Because both acute and chronic dehydration are associated with physiological stresses, such as exercise and sustained exposure to microgravity, the present research will aid in achieving a better understanding of how vital information is handled by the nervous system for maintenance of the body's fluid matrix which is critical for health and well-being.

Prediction of ore fluid metal concentrations from solid solution concentrations in ore-stage calcite: Application to the Illinois-Kentucky and Central Tennessee Mississippi Valley-type districts

NASA Astrophysics Data System (ADS)

Smith-Schmitz, Sarah E.; Appold, Martin S.

2018-03-01

Knowledge of the concentrations of Zn and Pb in Mississippi Valley-type (MVT) ore fluids is fundamental to understanding MVT deposit origin. Most previous attempts to quantify the concentrations of Zn and Pb in MVT ore fluids have focused on the analysis of fluid inclusions. However, these attempts have yielded ambiguous results due to possible contamination from secondary fluid inclusions, interferences from Zn and Pb in the host mineral matrix, and uncertainties about whether the measured Zn and Pb signals represent aqueous solute or accidental solid inclusions entrained within the fluid inclusions. The purpose of the present study, therefore, was to try to determine Zn and Pb concentrations in MVT ore fluids using an alternate method that avoids these ambiguities by calculating Zn and Pb concentrations in MVT ore fluids theoretically based on their solid solution concentrations in calcite. This method was applied to the Illinois-Kentucky and Central Tennessee districts, which both contain ore-stage calcite. Experimental partition coefficient (D) values from Rimstidt et al. (1998) and Tsusue and Holland (1966), and theoretical thermodynamic distribution coefficient (KD) values were employed in the present study. Ore fluid concentrations of Zn were likely most accurately predicted by Rimstidt et al. (1998) D values, based on their success in predicting known fluid inclusion concentrations of Mg and Mn, and likely also most accurately predicted ore fluid concentrations of Fe. All four of these elements have a divalent ionic radius smaller than that of Ca2+ and form carbonate minerals with the calcite structure. For both the Illinois-Kentucky and the Central Tennessee district, predicted ore fluid Zn and Fe concentrations were on the order of up to 10's of ppm. Ore fluid concentrations of Pb could only be predicted using Rimstidt et al. (1998) D values. However, these concentrations are unlikely to be reliable, as predicted ore fluid concentrations of Sr and Ba, which like Pb also have a divalent ionic radius larger than that of Ca2+ and form carbonate minerals with the aragonite structure, did not consistently agree well with known concentrations of Sr and Ba in fluid inclusions. The ore fluid Zn concentrations predicted in the present study lie within the range of Zn concentrations typical of modern sedimentary brines and are high enough to allow deposition of the observed amounts of Zn in the Illinois-Kentucky and Central Tennessee districts within ranges of geologically reasonable times and ore fluid flow velocities. If the pH of the Illinois-Kentucky and Central pH ore fluids was as low as current evidence suggests to be possible, then these ore fluids could simultaneously have transported enough sulfide with their Zn to account for the observed amounts of sphalerite in the districts.

Regulation of inward rectifier potassium current ionic channel remodeling by AT1 -Calcineurin-NFAT signaling pathway in stretch-induced hypertrophic atrial myocytes.

PubMed

He, Jionghong; Xu, Yanan; Yang, Long; Xia, Guiling; Deng, Na; Yang, Yongyao; Tian, Ye; Fu, Zenan; Huang, Yongqi

2018-05-02

Previous studies have shown that the activation of angiotensin II receptor type I (AT 1 ) is attributed to cardiac remodeling stimulated by increased heart load, and that it is followed by the activation of the calcineurin-nuclear factor of activated T-cells (NFAT) signaling pathway. Additionally, AT 1 has been found to be a regulator of cardiocyte ionic channel remodeling, and calcineurin-NFAT signals participate in the regulation of cardiocyte ionic channel expression. A hypothesis therefore follows that stretch stimulation may regulate cardiocyte ionic channel remodeling by activating the AT 1 -calcineurin-NFAT pathway. Here, we investigated the role of the AT 1 -calcineurin-NFAT pathway in the remodeling of inward rectifier potassium (I k1 ) channel, in addition to its role in changing action potential, in stretch-induced hypertrophic atrial myocytes of neonatal rats. Our results showed that increased stretch significantly led to atrial myocytes hypertrophy; it also increased the activity of calcineurin enzymatic activity, which was subsequently attenuated by telmisartan or cyclosporine-A. The level of NFAT 3 protein in nuclear extracts, the mRNA and protein expression of Kir2.1 in whole cell extracts, and the density of I k1 were noticeably increased in stretched samples. Stretch stimulation significantly shortened the action potential duration (APD) of repolarization at the 50% and 90% level. Telmisartan, cyclosporine-A, and 11R-VIVIT attenuated stretch-induced alterations in the levels of NFAT 3 , mRNA and protein expression of Kir2.1, the density of I k1 , and the APD. Our findings suggest that the AT 1 -calcineurin-NFAT signaling pathway played an important role in regulating I k1 channel remodeling and APD change in stretch-induced hypertrophic atrial myocytes of neonatal rats. This article is protected by copyright. All rights reserved.

Poly(ethylene glycol)-based ionic liquids: properties and uses as alternative solvents in organic synthesis and catalysis.

PubMed

Cecchini, Martina Maya; Charnay, Clarence; De Angelis, Francesco; Lamaty, Frédéric; Martinez, Jean; Colacino, Evelina

2014-01-01

PEG-based ionic liquids are a new appealing group of solvents making the link between two distinct but very similar fluids: ionic liquids and poly(ethylene glycol)s. They find applications across a range of innumerable disciplines in science, technology, and engineering. In the last years, the possibility to use these as alternative solvents for organic synthesis and catalysis has been increasingly explored. This Review highlights strategies for their synthesis, their physical properties (critical point, glass transition temperature, density, rheological properties), and their application in reactions catalyzed by metals (such as Pd, Cu, W, or Rh) or as organic solvent (for example for multicomponent reactions, organocatalysis, CO2 transformation) with special emphasis on their toxicity, environmental impact, and biodegradability. These aspects, very often neglected, need to be considered in addition to the green criteria usually considered to establish ecofriendly processes. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Na-coupled bicarbonate transporters of the Slc4 family in the nervous system: function, localization, and relevance to neurologic function

PubMed Central

Majumdar, Debeshi; Bevensee, Mark O.

2010-01-01

Many cellular processes including neuronal activity are sensitive to changes in intracellular and/or extracellular pH— both of which are regulated by acid-base transporter activity. HCO3−-dependent transporters are particularly potent regulators of intracellular pH in neurons and astrocytes, and also contribute to the composition of the cerebrospinal fluid (CSF). The molecular physiology of HCO3− transporters has advanced considerably over the past ~14 years as investigators have cloned and characterized the function and localization of many Na-Coupled Bicarbonate Transporters of the Slc4 family (NCBTs). In this review, we provide an updated overview of the function and localization of NCBTs in the nervous system. Multiple NCBTs are expressed in neurons and astrocytes in various brain regions, as well as in epithelial cells of the choroid plexus. Characteristics of human patients with SLC4 gene mutations/deletions and results from recent studies on mice with Slc4 gene disruptions highlight the functional importance of NCBTs in neuronal activity, somatosensory function, and CSF production. Furthermore, energy-deficient states (e.g., hypoxia and ischemia) lead to altered expression and activity of NCBTs. Thus, recent studies expand our understanding of the role of NCBTs in regulating the pH and ionic composition of the nervous system that can modulate neuronal activity. PMID:20884330

CFTR, bicarbonate, and the pathophysiology of cystic fibrosis.

PubMed

Borowitz, Drucy

2015-10-01

The gene that encodes for the cystic fibrosis transmembrane regulator protein (CFTR) was identified in 1989, yet major pathophysiologic questions remain unanswered. There is emerging evidence that CFTR is a bicarbonate channel, a driver of chloride-bicarbonate exchange and through its action on local pH, a regulator of other ion channels and of proteins that function optimally in a neutral environment. In both the respiratory and gastrointestinal (GI) tracts, bicarbonate drives ionic content and fluid on epithelial surfaces, allows mucins to unfold and become slippery, and contributes to innate immunity. In the GI tract bicarbonate neutralizes gastric acid to support digestion and absorption. When CFTR is dysfunctional, lack of bicarbonate secretion disrupts these normal processes and thus leads directly to the clinical symptoms and signs of CF. This article synthesizes evidence from cell, animal, and human investigations that support these concepts. Bicarbonate secretion does not seem to be the same in all tissues and varies with physiologic demand. Thus, tissue type and whether conditions are baseline or stimulated needs to be taken into account when evaluating the evidence concerning the role of bicarbonate in the pathophysiology of CF as a regulator of local pH. Basic and applied research that focuses on the role of CFTR-mediated bicarbonate secretion helps explain many of the diverse clinical manifestations that are CF. © 2015 Wiley Periodicals, Inc.

Self-regulation mechanism for charged point defects in hybrid halide perovskites

DOE PAGES

Walsh, Aron; Scanlon, David O.; Chen, Shiyou; ...

2014-12-11

Hybrid halide perovskites such as methylammonium lead iodide (CH 3NH 3PbI 3) exhibit unusually low free-carrier concentrations despite being processed at low-temperatures from solution. We demonstrate, through quantum mechanical calculations, that an origin of this phenomenon is a prevalence of ionic over electronic disorder in stoichiometric materials. Schottky defect formation provides a mechanism to self-regulate the concentration of charge carriers through ionic compensation of charged point defects. The equilibrium charged vacancy concentration is predicted to exceed 0.4 % at room temperature. Furthermore, this behavior, which goes against established defect conventions for inorganic semiconductors, has implications for photovoltaic performance.

Neuron-Glia Interactions and Nervous System Homeostasis

DTIC Science & Technology

1988-06-01

active neuron states, the mechanisms which glial cells and neurons use to modulate each others metabolic state and the chemical, electrical and... mechanisms by which axons/neurons and their glial cell investments communicate to actively regulate the ionic microenvironment of the nervous system and...of the glial cell in maintenance of the ionic homeostasis of the perineural environment during resting and active neuron states, the mechanisms which

Effects of the recombinant crustacean hyperglycemic hormones rCHH-B1 and rCHH-B2 on the osmo-ionic regulation of the shrimp Litopenaeus vannamei exposed to acute salinity stress.

PubMed

Camacho-Jiménez, Laura; Díaz, Fernando; Sánchez-Castrejón, Edna; Ponce-Rivas, Elizabeth

2018-03-26

The Pacific white shrimp Litopenaeus vannamei is a euryhaline organism that copes with salinity fluctuations in the environment; therefore, its osmotic and ionic regulation abilities are vital. Osmoregulation may be controlled by the crustacean hyperglycemic hormone (CHH), a neuropeptide mainly expressed in the eyestalks. In L. vannamei, CHH-B1 and CHH-B2 are CHH isoforms isolated from the eyestalks whose expression is influenced by environmental salinity. It has been suggested that they are involved in the response to salinity stress. To clarify this, we investigated the effect of the recombinant peptides, rCHH-B1 and rCHH-B2, on the osmo-ionic regulation of shrimp acutely exposed to different salinity conditions (8, 26 and 45‰). Both rCHHs promoted differential effects on the osmoregulatory capacity (OC) and the ionoregulatory capacity (IC) for hemolymph Na + and Cl - during iso-osmotic (26‰) and hyper-osmotic (45‰) transfers. These changes were linked to the changes observed in Na + /K + ATPase and carbonic anhydrase gene expression in gills, especially under high salinity conditions, suggesting that the hormones may regulate the expression of these genes. Glucose and protein levels measured during acute salinity transfer suggest their roles as sources of metabolic energy for osmotic regulation or as organic osmolytes. These results taken together suggest that both the CHH-B1 and CHH-B2 peptides are important regulators of the physiological response of L. vannamei to acute salinity fluctuations.

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Computer Simulations and Theoretical Studies of Complex Systems: from complex fluids to frustrated magnets

NASA Astrophysics Data System (ADS)

Choi, Eunsong

Computer simulations are an integral part of research in modern condensed matter physics; they serve as a direct bridge between theory and experiment by systemactically applying a microscopic model to a collection of particles that effectively imitate a macroscopic system. In this thesis, we study two very differnt condensed systems, namely complex fluids and frustrated magnets, primarily by simulating classical dynamics of each system. In the first part of the thesis, we focus on ionic liquids (ILs) and polymers--the two complementary classes of materials that can be combined to provide various unique properties. The properties of polymers/ILs systems, such as conductivity, viscosity, and miscibility, can be fine tuned by choosing an appropriate combination of cations, anions, and polymers. However, designing a system that meets a specific need requires a concrete understanding of physics and chemistry that dictates a complex interplay between polymers and ionic liquids. In this regard, molecular dynamics (MD) simulation is an efficient tool that provides a molecular level picture of such complex systems. We study the behavior of Poly (ethylene oxide) (PEO) and the imidazolium based ionic liquids, using MD simulations and statistical mechanics. We also discuss our efforts to develop reliable and efficient classical force-fields for PEO and the ionic liquids. The second part is devoted to studies on geometrically frustrated magnets. In particular, a microscopic model, which gives rise to an incommensurate spiral magnetic ordering observed in a pyrochlore antiferromagnet is investigated. The validation of the model is made via a comparison of the spin-wave spectra with the neutron scattering data. Since the standard Holstein-Primakoff method is difficult to employ in such a complex ground state structure with a large unit cell, we carry out classical spin dynamics simulations to compute spin-wave spectra directly from the Fourier transform of spin trajectories. We conclude the study by showing an excellent agreement between the simulation and the experiment.

Science and Technology Text Mining: Electric Power Sources

DTIC Science & Technology

2004-04-01

Transactions of Power Systems), Thermal Engineering (Applied Thermal Engineering, JSME International Journal Series B – Fluids Thermal Engineering...Renewables ( International Journal of Hydrogen Energy, Biomass and Bioenergy, Solar Energy), Electrochemistry (Solid State Ionics, Journal of the...pollutants, with balanced emphasis given to solar and biomass systems. The papers in International Journal of Energy Research focus on performance of total

Porphyrin and bodipy molecular rotors as microviscometers

NASA Astrophysics Data System (ADS)

Kimball, Joseph Daniel, III

Viscosity, a fluid's internal resistance to flow and resist molecular diffusion, is a fundamental property of fluid media. Determining the bulk viscosity of a fluid has been easy to relatively simple to accomplish for many years, yet in the recent decade there has been a focus on techniques to measure a fluid's microviscosity. Microviscosity differs from bulk viscosity such that microviscosity is the friction experienced by a single particle interacting with its micron-sized local environment. Macroscopic methods to evaluate the viscosity are well established, but methods to determine viscosity on the microscale level remains unclear. This work determines the viability of three molecular rotors designed as probes for microviscosity in organic media, ionic liquids, and in the cellular microenvironment. Understanding microviscosity is important because it one of the main properties of any fluid and thus has an effect on any diffusion related processes. A variety of mass and signal transport phenomena as well as intermolecular interactions are often governed by viscosity. Molecular rotors are a subclass of intramolecular charge transfer fluorophores which form a lower energy twisted state. This results in a charge separated species which is highly sensitive to its surrounding microenviroment's viscosity as high viscosity limits its ability to form this twisted state. Once excited, there are deactivation routes which the excited fluorophore can undergo: radiative and non-radiative. Both were studied in this work. In the case of a radiative decay, as seen in porphyrin dimer, the energy is released in the form of a photon and is seen as a shifted band in the emission structure. The conformation of the porphyrin dimer was found to be influenced differently by ionic liquids as compared to molecular solvents, indicating the microheterogenous nature of ionic liquids play a role in the conformation. For non-radiative decays, BODIPY dyads and triads were investigated. The triad has an extinction coefficient in the range of 200,000 M -1 cm-1, making it an extremely useful and sensitive fluorescent molecular rotor. Their fluorescent lifetimes were proven to correlate linearly with viscosity. Thus they were both encapsulated into lipds to determine their viability for cellular studies. The dyes were readily uptaken into three cancer cell lines, SKOV3, Calu 3 and Du 145. The lifetimes were then recorded using FLIM to map the viscosity of the cellular cytoplasm, mitochondria, lysosomes and other various organelles. A longer than expected lifetime in the cytoplasm was observed. This could be due to binding onto cytoplasmic proteins distributed throughout the cytoplasm, not due to viscosity as the theory of molecular rotors predicts..

Regulation of anionic lipids in binary membrane upon the adsorption of polyelectrolyte: A Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Duan, Xiaozheng; Li, Yunqi; Zhang, Ran; Shi, Tongfei; An, Lijia; Huang, Qingrong

2013-06-01

We employ Monte Carlo simulations to investigate the interaction between an adsorbing linear flexible cationic polyelectrolyte and a binary fluid membrane. The membrane contains neutral phosphatidyl-choline, PC) and multivalent anionic (phosphatidylinositol, PIP2) lipids. We systematically study the influences of the solution ionic strength, the chain length and the bead charge density of the polyelectrolyte on the lateral rearrangement and the restricted mobility of the multivalent anionic lipids in the membrane. Our findings show that, the cooperativity effect and the electrostatic interaction of the polyelectrolyte beads can significantly affect the segregation extent and the concentration gradients of the PIP2 molecules, and further cooperate to induce the complicated hierarchical mobility behaviors of PIP2 molecules. In addition, when the polyelectrolyte brings a large amount of charges, it can form a robust electrostatic well to trap all PIP2 and results in local overcharge of the membrane. This work presents a mechanism to explain the membrane heterogeneity formation induced by the adsorption of charged macromolecule.

[Pigment and ion transport in the vestibular organ].

PubMed

Meyer zum Gottesberge-Orsulakova, A

1985-07-01

Pigments are found in various parts of the inner ear, especially in the neighbourhood of epithelia, which are supposed to be involved in the secretion and/or absorbtion of the endolymphatic fluid. Microprobe analysis (laser absorption mass micro analyzer "LAMMA" and X-ray) combined with morphological observations were performed in shock frozen, freeze-dried and plastic embedded inner ear tissue from the vestibular organ of pigmented guinea pig. Disturbance of the endolymphatic ionic composition (increased Na+) due to treatment with metabolic inhibitors (ethacrynic acid, ouabain) stimulated the migration of pigment granules and displacement of the dentritic processes of the melanocytes in a close vicinity to the presumably transporting vestibular epithelia (the dark and light cells and capillaries). The melanosomes obtained full range of metal ions that changed characteristically after treatment with metabolic inhibitors. It could be supposed that melanin presents some kind of reservoir for essential trace elements or compounds and may regulate numerous enzymatic and membrane functions by binding and releasing the metal ions.

Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions.

PubMed

Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

2018-04-14

A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute interactions are implemented using a pseudopotential model. The Nernst-Planck equation, describing the kinetics of dissolved ion species, is solved using a finite difference discretization based on the link-flux method. The colloids are resolved on the lattice and coupled to the hydrodynamics and electrokinetics through appropriate boundary conditions. We present the first full integration of these three elements. The model is validated by comparing with known analytic solutions of ionic distributions at fluid interfaces, dielectric droplet deformations, and the electrophoretic mobility of colloidal suspensions. Its possibilities are explored by considering various physical systems, such as breakup of charged and neutral droplets and colloidal dynamics at either planar or spherical fluid interfaces.

Smart Multifunctional Fluids for Lithium Ion Batteries: Enhanced Rate Performance and Intrinsic Mechanical Protection

NASA Astrophysics Data System (ADS)

Ding, Jie; Tian, Tongfei; Meng, Qing; Guo, Zaiping; Li, Weihua; Zhang, Peng; Ciacchi, Fabio T.; Huang, Jewel; Yang, Wenrong

2013-08-01

Lithium ion batteries are attractive power sources for the consumer electronics market and are being aggressively developed for road transportation. Nevertheless, issues with safety and reliability need to be solved prior to the large-scale uptake of these batteries. There have recently been significant development and assessment of materials with resistance to mechanical abuse, with the aims of reinforcing the battery and preventing puncturing during a crash. Most of the work on battery mechanical safety has concentrated on the external packaging of batteries, with little attention being paid to the enclosed electrolyte. We report on smart multifunctional fluids that act as both highly conductive electrolytes and intrinsic mechanical protectors for lithium ion batteries. These fluids exhibit a shear thickening effect under pressure or impact and thus demonstrate excellent resistance to crushing. Also, the fluids show higher ionic conductivities and comparable redox stability windows to the commercial liquid electrolytes.

Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions

NASA Astrophysics Data System (ADS)

Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

2018-04-01

A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute interactions are implemented using a pseudopotential model. The Nernst-Planck equation, describing the kinetics of dissolved ion species, is solved using a finite difference discretization based on the link-flux method. The colloids are resolved on the lattice and coupled to the hydrodynamics and electrokinetics through appropriate boundary conditions. We present the first full integration of these three elements. The model is validated by comparing with known analytic solutions of ionic distributions at fluid interfaces, dielectric droplet deformations, and the electrophoretic mobility of colloidal suspensions. Its possibilities are explored by considering various physical systems, such as breakup of charged and neutral droplets and colloidal dynamics at either planar or spherical fluid interfaces.

Escherichia coli under Ionic Silver Stress: An Integrative Approach to Explore Transcriptional, Physiological and Biochemical Responses

PubMed Central

Saulou-Bérion, Claire; Gonzalez, Ignacio; Enjalbert, Brice; Audinot, Jean-Nicolas; Fourquaux, Isabelle; Jamme, Frédéric; Cocaign-Bousquet, Muriel; Mercier-Bonin, Muriel; Girbal, Laurence

2015-01-01

For a better understanding of the systemic effect of sub-lethal micromolar concentrations of ionic silver on Escherichia coli, we performed a multi-level characterization of cells under Ag+-mediated stress using an integrative biology approach combining physiological, biochemical and transcriptomic data. Physiological parameters, namely bacterial growth and survival after Ag+ exposure, were first quantified and related to the accumulation of intracellular silver, probed for the first time by nano secondary ion mass spectroscopy at sub-micrometer lateral resolution. Modifications in E. coli biochemical composition were evaluated under Ag+-mediated stress by in situ synchrotron Fourier-transform infrared microspectroscopy and a comprehensive transcriptome response was also determined. Using multivariate statistics, correlations between the physiological parameters, the extracellular concentration of AgNO3 and the intracellular silver content, gene expression profiles and micro-spectroscopic data were investigated. We identified Ag+-dependent regulation of gene expression required for growth (e.g. transporter genes, transcriptional regulators, ribosomal proteins), for ionic silver transport and detoxification (e.g. copA, cueO, mgtA, nhaR) and for coping with various types of stress (dnaK, pspA, metA,R, oxidoreductase genes). The silver-induced shortening of the acyl chain of fatty acids, mostly encountered in cell membrane, was highlighted by microspectroscopy and correlated with the down-regulated expression of genes involved in fatty acid transport (fadL) and synthesis/modification of lipid A (lpxA and arnA). The increase in the disordered secondary structure of proteins in the presence of Ag+ was assessed through the conformational shift shown for amides I and II, and further correlated with the up-regulated expression of peptidase (hfq) and chaperone (dnaJ), and regulation of transpeptidase expression (ycfS and ycbB). Interestingly, as these transpeptidases act on the structural integrity of the cell wall, regulation of their expression may explain the morphological damage reported under Ag+-mediated stress. This result clearly demonstrates that the cell membrane is a key target of ionic silver. PMID:26696268

Identification and function of proteolysis regulators in seminal fluid.

PubMed

Laflamme, Brooke A; Wolfner, Mariana F

2013-02-01

Proteins in the seminal fluid of animals with internal fertilization effect numerous responses in mated females that impact both male and female fertility. Among these proteins is the highly represented class of proteolysis regulators (proteases and their inhibitors). Though proteolysis regulators have now been identified in the seminal fluid of all animals in which proteomic studies of the seminal fluid have been conducted (as well as several other species in which they have not), a unified understanding of the importance of proteolysis to male fertilization success and other reproductive processes has not yet been achieved. In this review, we provide an overview of the identification of proteolysis regulators in the seminal fluid of humans and Drosophila melanogaster, the two species with the most comprehensively known seminal fluid proteomes. We also highlight reports demonstrating the functional significance of specific proteolysis regulators in reproductive and post-mating processes. Finally, we make broad suggestions for the direction of future research into the roles of both active seminal fluid proteolysis regulators and their inactive homologs, another significant class of seminal fluid proteins. We hope that this review aids researchers in pursuing a coordinated study of the functional significance of proteolysis regulators in semen. Copyright © 2012 Wiley Periodicals, Inc.

Vaporization behavior of tetraoctylphosphonium bis(2-ethylhexyl)phosphate ionic liquid

DOE PAGES

McMurray, J. W.; Zhou, Y.; Luo, H. M.; ...

2016-11-18

We determined the equilibrium vapor pressures, p e, of the ionic liquid tetraoctylphosphonium bis(2-ethylhexyl)phosphate ([P 8888][DEHP]) over the temperature range 409–495 K using mass loss Knudsen effusion. The p e versus temperature relationship compares well to 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide ([C 8mim][NTf 2]) but is lower than that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 2mim][NTf 2]) when measured using the same technique. Here, we determined the discrepancies between the p e for [C 8mim][NTf 2] and [C 2mim][NTf 2] with previous studies is discussed. Finally, the enthalpy and entropy of vaporization for all three fluids are estimated from the Clasius-Clapeyron relation.

Room-temperature ionic liquids: slow dynamics, viscosity, and the red edge effect.

PubMed

Hu, Zhonghan; Margulis, Claudio J

2007-11-01

Ionic liquids (ILs) have recently attracted significant attention from academic and industrial sources. This is because, while their vapor pressures are negligible, many of them are liquids at room temperature and can dissolve a wide range of polar and nonpolar organic and inorganic molecules. In this Account, we discuss the progress of our laboratory in understanding the dynamics, spectroscopy, and fluid dynamics of selected imidazolium-based ILs using computational and analytical tools that we have recently developed. Our results indicate that the red edge effect, the non-Newtonian behavior, and the existence of locally heterogeneous environments on a time scale relevant to chemical and photochemical reactivity are closely linked to the viscosity and highly structured character of these liquids.

Vaporization behavior of tetraoctylphosphonium bis(2-ethylhexyl)phosphate ionic liquid

NASA Astrophysics Data System (ADS)

McMurray, J. W.; Zhou, Y.; Luo, H. M.; Qu, J.

2017-01-01

The equilibrium vapor pressures, pe, of the ionic liquid tetraoctylphosphonium bis(2-ethylhexyl)phosphate ([P8888][DEHP]) over the temperature range 409-495 K were determined for the first time using mass loss Knudsen effusion. The pe versus temperature relationship compares well to 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide ([C8mim][NTf2]) but is lower than that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) when measured using the same technique. The discrepancies between the pe determined in this work for [C8mim][NTf2] and [C2mim][NTf2] with previous studies is discussed. The enthalpy and entropy of vaporization for all three fluids are estimated from the Clasius-Clapeyron relation.

Super earth interiors and validity of Birch's Law for ultra-high pressure metals and ionic solids

NASA Astrophysics Data System (ADS)

Ware, Lucas Andrew

2015-01-01

Super Earths, recently detected by the Kepler Mission, expand the ensemble of known terrestrial planets beyond our Solar System's limited group. Birch's Law and velocity-density systematics have been crucial in constraining our knowledge of the composition of Earth's mantle and core. Recently published static diamond anvil cell experimental measurements of sound velocities in iron, a key deep element in most super Earth models, are inconsistent with each other with regard to the validity of Birch's Law. We examine the range of validity of Birch's Law for several metallic elements, including iron, and ionic solids shocked with a two-stage light gas gun into the ultra-high pressure, temperature fluid state and make comparisons to the recent static data.

Effects of CSF hormones and ionic composition on salt/water metabolism

NASA Technical Reports Server (NTRS)

Severs, Walter B.; Keil, Lanny C.

1992-01-01

This collaborative agreement between Drs. Severs and Keil began in 1981, arising from a continuing interest in the issue of what, exactly, are the consequences of headward fluid shifts during manned spaceflight. Such shifts were recognized early by both U.S. and Soviet Scientists because of signs and symptoms referable to the head. Some of these include disturbed vision, puffiness in the face and periorbital areas, headache, vestibular dysfunction and distended jugular veins. We posited that the fluid shift had an immediate effect on the brain, and a long-term action requiring a neural interpretation of the flight environment. This would re-adjust both efferent neural as well as hormonal mechanisms to sustain cardiovascular and fluid/electrolyte balance consonent with survival in microgravity. Work along these lines is summarized.

Objective and Subjective Intra-patient Comparison of Iohexol versus Diatrizoate for Bowel Preparation Quality at CT Colonography

PubMed Central

Johnson, Brandon; Hinshaw, J. Louis; Robbins, Jessica B.; Pickhardt, Perry J.

2017-01-01

Objective To objectively and subjectively compare nonionic iohexol and ionic diatrizoate iodinated oral contrast as part of a cathartic bowel regimen within the same CT colonography (CTC) cohort, with otherwise identical preparations. Materials and Methods In our IRB-approved retrospective study, 46 asymptomatic adults (mean age, 59.4 years; 26M/20F) returning for follow-up CTC over a 9-month interval underwent the same bowel preparation with the exception of 75 ml iohexol 350 (Omnipaque) in place of 60 ml diatrizoate (Gastrografin). All other preparation components (bisacodyl, magnesium citrate, and 2% barium) remained constant. Objective volumetric analysis of residual colonic fluid volume and fluid attenuation was performed. Additionally, two radiologists experienced with CTC, blinded to the specific bowel preparation, scored each of 6 colonic segments for adherent residual solid stool using a previously validated 4-point scale (0 for no stool; 1–3 for increasing residual stool). Paired t-test was used for comparison of the cohorts. Results No clear clinically-meaningful difference was found between the two preparations on overall objective or subjective evaluation. Mean (±SD) residual fluid volume was 173±126 ml with the iohexol preparation and 130±79 ml with the diatrizoate prep (p=0.02). Mean total colonic stool score was 2.5 (0.42/segment) with iohexol and 2.3 (0.38/segment) with diatrizoate (p=0.69). Mean (±SD) fluid attenuation was higher with iohexol (849±270HU) compared with diatrizoate (732±168HU) (p=0.03). Conclusions Based on this direct intra-patient comparison, we found that oral iohexol is a suitable alternative to diatrizoate for fluid tagging as part of a cathartic bowel preparation at CTC. Because this nonionic tagging agent is more palatable, less expensive, and likely safer than ionic diatrizoate, our CTC program now utilizes iohexol as the standard recommended regimen. PMID:27010251

Quantifying particulate and colloidal release of radionuclides in waste-weathered hanford sediments.

PubMed

Perdrial, Nicolas; Thompson, Aaron; LaSharr, Kelsie; Amistadi, Mary Kay; Chorover, Jon

2015-05-01

At the Hanford Site in the state of Washington, leakage of hyperalkaline, high ionic strength wastewater from underground storage tanks into the vadose zone has induced mineral transformations and changes in radionuclide speciation. Remediation of this wastewater will decrease the ionic strength of water infiltrating to the vadose zone and could affect the fate of the radionuclides. Although it was shown that radionuclide host phases are thermodynamically stable in the presence of waste fluids, a decrease in solution ionic strength and pH could alter aggregate stability and remobilize radionuclide-bearing colloids and particulate matter. We quantified the release of particulate, colloidal, and truly dissolved Sr, Cs, and I from hyperalkaline-weathered Hanford sediments during a low ionic strength pore water leach and characterized the released particles and colloids using electron microscopy and X-ray diffraction. Although most of the Sr, Cs, and I was released in dissolved form, between 3 and 30% of the Sr and 4 to 18% of the Cs was associated with a dominantly zeolitic mobile particulate fraction. Thus, the removal of hyperalkaline wastewater will likely induce Sr and Cs mobilization that will be augmented by particulate- and colloid-facilitated transport. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Composition of nasal airway surface liquid in cystic fibrosis and other airway diseases determined by X-ray microanalysis.

PubMed

Vanthanouvong, V; Kozlova, I; Johannesson, M; Nääs, E; Nordvall, S L; Dragomir, A; Roomans, G M

2006-04-01

The ionic composition of the airway surface liquid (ASL) in healthy individuals and in patients with cystic fibrosis (CF) has been debated. Ion transport properties of the upper airway epithelium are similar to those of the lower airways and it is easier to collect nasal ASL from the nose. ASL was collected with ion exchange beads, and the elemental composition of nasal fluid was determined by X-ray microanalysis in healthy subjects, CF patients, CF heterozygotes, patients with rhinitis, and with primary ciliary dyskinesia (PCD). In healthy subjects, the ionic concentrations were approximately isotonic. In CF patients, CF heterozygotes, rhinitis, and PCD patients, [Na] and [Cl] were significantly higher compared when compared with those in controls. [K] was significantly higher in CF and PCD patients compared with that in controls. Severely affected CF patients had higher ionic concentrations in their nasal ASL than in patients with mild or moderate symptoms. Female CF patients had higher levels of Na, Cl, and K than male patients. As higher salt concentrations in the ASL are also found in other patients with airway diseases involving chronic inflammation, it appears likely that inflammation-induced epithelial damage is important in determining the ionic composition of the ASL. Copyright (c) 2006 Wiley-Liss, Inc.

A hybrid, coupled approach for modeling charged fluids from the nano to the mesoscale

DOE PAGES

Cheung, James; Frischknecht, Amalie L.; Perego, Mauro; ...

2017-07-20

Here, we develop and demonstrate a new, hybrid simulation approach for charged fluids, which combines the accuracy of the nonlocal, classical density functional theory (cDFT) with the efficiency of the Poisson–Nernst–Planck (PNP) equations. The approach is motivated by the fact that the more accurate description of the physics in the cDFT model is required only near the charged surfaces, while away from these regions the PNP equations provide an acceptable representation of the ionic system. We formulate the hybrid approach in two stages. The first stage defines a coupled hybrid model in which the PNP and cDFT equations act independentlymore » on two overlapping domains, subject to suitable interface coupling conditions. At the second stage we apply the principles of the alternating Schwarz method to the hybrid model by using the interface conditions to define the appropriate boundary conditions and volume constraints exchanged between the PNP and the cDFT subdomains. Numerical examples with two representative examples of ionic systems demonstrate the numerical properties of the method and its potential to reduce the computational cost of a full cDFT calculation, while retaining the accuracy of the latter near the charged surfaces.« less

A hybrid, coupled approach for modeling charged fluids from the nano to the mesoscale

NASA Astrophysics Data System (ADS)

Cheung, James; Frischknecht, Amalie L.; Perego, Mauro; Bochev, Pavel

2017-11-01

We develop and demonstrate a new, hybrid simulation approach for charged fluids, which combines the accuracy of the nonlocal, classical density functional theory (cDFT) with the efficiency of the Poisson-Nernst-Planck (PNP) equations. The approach is motivated by the fact that the more accurate description of the physics in the cDFT model is required only near the charged surfaces, while away from these regions the PNP equations provide an acceptable representation of the ionic system. We formulate the hybrid approach in two stages. The first stage defines a coupled hybrid model in which the PNP and cDFT equations act independently on two overlapping domains, subject to suitable interface coupling conditions. At the second stage we apply the principles of the alternating Schwarz method to the hybrid model by using the interface conditions to define the appropriate boundary conditions and volume constraints exchanged between the PNP and the cDFT subdomains. Numerical examples with two representative examples of ionic systems demonstrate the numerical properties of the method and its potential to reduce the computational cost of a full cDFT calculation, while retaining the accuracy of the latter near the charged surfaces.

A hybrid, coupled approach for modeling charged fluids from the nano to the mesoscale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, James; Frischknecht, Amalie L.; Perego, Mauro

Here, we develop and demonstrate a new, hybrid simulation approach for charged fluids, which combines the accuracy of the nonlocal, classical density functional theory (cDFT) with the efficiency of the Poisson–Nernst–Planck (PNP) equations. The approach is motivated by the fact that the more accurate description of the physics in the cDFT model is required only near the charged surfaces, while away from these regions the PNP equations provide an acceptable representation of the ionic system. We formulate the hybrid approach in two stages. The first stage defines a coupled hybrid model in which the PNP and cDFT equations act independentlymore » on two overlapping domains, subject to suitable interface coupling conditions. At the second stage we apply the principles of the alternating Schwarz method to the hybrid model by using the interface conditions to define the appropriate boundary conditions and volume constraints exchanged between the PNP and the cDFT subdomains. Numerical examples with two representative examples of ionic systems demonstrate the numerical properties of the method and its potential to reduce the computational cost of a full cDFT calculation, while retaining the accuracy of the latter near the charged surfaces.« less

Parametric study of the physical properties of hydrate-bearing sand, silt, and clay sediments: 1. Electromagnetic properties

USGS Publications Warehouse

Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

2010-01-01

The marked decrease in bulk electrical conductivity of sediments in the presence of gas hydrates has been used to interpret borehole electrical resistivity logs and, to a lesser extent, the results of controlled source electromagnetic surveys to constrain the spatial distribution and predicted concentration of gas hydrate in natural settings. Until now, an exhaustive laboratory data set that could be used to assess the impact of gas hydrate on the electromagnetic properties of different soils (sand, silt, and clay) at different effective stress and with different saturations of hydrate has been lacking. The laboratory results reported here are obtained using a standard geotechnical cell and the hydrate-formed tetrahydrofuran (THF), a liquid that is fully miscible in water and able to produce closely controlled saturations of hydrate from dissolved phase. Both permittivity and electrical conductivity are good indicators of the volume fraction of free water in the sediment, which is in turn dependent on hydrate saturation. Permittivity in the microwave frequency range is particularly predictive of free water content since it is barely affected by ionic concentration, pore structure, and surface conduction. Electrical conductivity (or resistivity) is less reliable for constraining water content or hydrate saturation: In addition to fluid-filled porosity, other factors, such as the ionic concentration of the pore fluid and possibly other conduction effects (e.g., surface conduction in high specific surface soils having low conductivity pore fluid), also influence electrical conductivity.

Miniaturized pressurization system

DOEpatents

Whitehead, John C.; Swink, Don G.

1991-01-01

The invention uses a fluid stored at a low pressure and provides the fluid at a high pressure. The invention allows the low pressure fluid to flow to a fluid bore of a differential pump and from the pump to a fluid pressure regulator. After flowing through the regulator the fluid is converted to a gas which is directed to a gas bore of the differential pump. By controlling the flow of gas entering and being exhausted from the gas bore, the invention provides pressure to the fluid. By setting the regulator, the high pressure fluid can be set at predetermined values. Because the invention only needs a low pressure fluid, the inventive apparatus has a low mass, and therefore would be useful in rocket propulsion systems.

Fluids of the Lower Crust: Deep Is Different

NASA Astrophysics Data System (ADS)

Manning, Craig E.

2018-05-01

Deep fluids are important for the evolution and properties of the lower continental and arc crust in tectonically active settings. They comprise four components: H2O, nonpolar gases, salts, and rock-derived solutes. Contrasting behavior of H2O-gas and H2O-salt mixtures yields immiscibility and potential separation of phases with different chemical properties. Equilibrium thermodynamic modeling of fluid-rock interaction using simple ionic species known from shallow-crustal systems yields solutions too dilute to be consistent with experiments and resistivity surveys, especially if CO2 is added. Therefore, additional species must be present, and H2O-salt solutions likely explain much of the evidence for fluid action in high-pressure settings. At low salinity, H2O-rich fluids are powerful solvents for aluminosilicate rock components that are dissolved as polymerized clusters. Addition of salts changes solubility patterns, but aluminosilicate contents may remain high. Fluids with Xsalt = 0.05 to 0.4 in equilibrium with model crustal rocks have bulk conductivities of 10‑1.5 to 100 S/m at porosity of 0.001. Such fluids are consistent with observed conductivity anomalies and are capable of the mass transfer seen in metamorphic rocks exhumed from the lower crust.

Regulation of Ion Gradients across Myocardial Ischemic Border Zones: A Biophysical Modelling Analysis

PubMed Central

Niederer, Steven

2013-01-01

The myocardial ischemic border zone is associated with the initiation and sustenance of arrhythmias. The profile of ionic concentrations across the border zone play a significant role in determining cellular electrophysiology and conductivity, yet their spatial-temporal evolution and regulation are not well understood. To investigate the changes in ion concentrations that regulate cellular electrophysiology, a mathematical model of ion movement in the intra and extracellular space in the presence of ionic, potential and material property heterogeneities was developed. The model simulates the spatial and temporal evolution of concentrations of potassium, sodium, chloride, calcium, hydrogen and bicarbonate ions and carbon dioxide across an ischemic border zone. Ischemia was simulated by sodium-potassium pump inhibition, potassium channel activation and respiratory and metabolic acidosis. The model predicted significant disparities in the width of the border zone for each ionic species, with intracellular sodium and extracellular potassium having discordant gradients, facilitating multiple gradients in cellular properties across the border zone. Extracellular potassium was found to have the largest border zone and this was attributed to the voltage dependence of the potassium channels. The model also predicted the efflux of from the ischemic region due to electrogenic drift and diffusion within the intra and extracellular space, respectively, which contributed to depletion in the ischemic region. PMID:23577101

Active Aircraft Pylon Noise Control System

NASA Technical Reports Server (NTRS)

Thomas, Russell H. (Inventor); Czech, Michael J (Inventor); Elmiligui, Alaa A. (Inventor)

2015-01-01

An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.

Active Aircraft Pylon Noise Control System

NASA Technical Reports Server (NTRS)

Thomas, Russell H. (Inventor); Czech, Michael J. (Inventor); Elmiligui, Alaa A. (Inventor)

2017-01-01

An active pylon noise control system for an aircraft includes a pylon structure connecting an engine system with an airframe surface of the aircraft and having at least one aperture to supply a gas or fluid therethrough, an intake portion attached to the pylon structure to intake a gas or fluid, a regulator connected with the intake portion via a plurality of pipes, to regulate a pressure of the gas or fluid, a plenum chamber formed within the pylon structure and connected with the regulator, and configured to receive the gas or fluid as regulated by the regulator, and a plurality of injectors in communication with the plenum chamber to actively inject the gas or fluid through the plurality of apertures of the pylon structure.

Allometric relationship of postmolt net ion uptake, ventilation, and circulation in the freshwater crayfish Procambarus clarkii: intraspecific scaling.

PubMed

Zanotto, F P; Wheatly, M G; Reiber, C L; Gannon, A T; Jalles-Filho, E

2004-01-01

There are few intraspecific studies relating physiological parameters to body mass. This study relates scaling of ionic regulation and respiratory parameters with body mass in crayfish (Procambarus clarkii). These animals were chosen because of their direct development, spanning four orders of magnitude in body mass. Usually, these animals are hyperregulators and must maintain hemolymph electrolyte levels above those in the ambient freshwater. This is especially important in the postmolt, when ion imbalance can occur. Maintaining hemolymph ion levels above ambient involves active processes that are independently related to metabolic rate, ventilation, and circulation. Therefore, this study investigates relationships among size and ionic regulation, heart rate, and ventilation in crayfish, spanning a size range of 0.003-24 g. Postmolt net ion uptake of Ca, titratable base, Na, Cl, and NH4 increase with body mass (positive allometry) with slopes of 0.92, 0.79, 0.90, 0.84, and 0.87, respectively. Between 72% and 97% of variation in ionic regulation was related to body mass. The slopes differed from each other for Ca and titratable base but not for Na, Cl, and NH4. For heart rate and ventilation rate, different relationships were derived for animals smaller and larger than 0.01 g (between first and third instar). Animals larger than 0.01 g show a negative allometric relationship between heart rate and body size ([body mass](0.15)), while smaller animals show positive allometry with body size, but only 29% of variation in heart rate is explained by body size alone. For ventilation rates, the negative allometry with body size for animals larger than 0.01 g is present, but less than 15% of variation in ventilation rate is explained by size, while for smaller animals the size dependency disappears. Based on these results, predictions of physiological parameters such as ionic regulation based on body size are useful in crayfish, but estimates of respiratory parameters and body size should be used with caution.

Investigating the Toxicity, Uptake, Nanoparticle Formation and Genetic Response of Plants to Gold

PubMed Central

Taylor, Andrew F.; Rylott, Elizabeth L.; Anderson, Christopher W. N.; Bruce, Neil C.

2014-01-01

We have studied the physiological and genetic responses of Arabidopsis thaliana L. (Arabidopsis) to gold. The root lengths of Arabidopsis seedlings grown on nutrient agar plates containing 100 mg/L gold were reduced by 75%. Oxidized gold was subsequently found in roots and shoots of these plants, but gold nanoparticles (reduced gold) were only observed in the root tissues. We used a microarray-based study to monitor the expression of candidate genes involved in metal uptake and transport in Arabidopsis upon gold exposure. There was up-regulation of genes involved in plant stress response such as glutathione transferases, cytochromes P450, glucosyl transferases and peroxidases. In parallel, our data show the significant down-regulation of a discreet number of genes encoding proteins involved in the transport of copper, cadmium, iron and nickel ions, along with aquaporins, which bind to gold. We used Medicago sativa L. (alfalfa) to study nanoparticle uptake from hydroponic culture using ionic gold as a non-nanoparticle control and concluded that nanoparticles between 5 and 100 nm in diameter are not directly accumulated by plants. Gold nanoparticles were only observed in plants exposed to ionic gold in solution. Together, we believe our results imply that gold is taken up by the plant predominantly as an ionic form, and that plants respond to gold exposure by up-regulating genes for plant stress and down-regulating specific metal transporters to reduce gold uptake. PMID:24736522

Communication: Stiff and soft nano-environments and the "Octopus Effect" are the crux of ionic liquid structural and dynamical heterogeneity

NASA Astrophysics Data System (ADS)

Daly, Ryan P.; Araque, Juan C.; Margulis, Claudio J.

2017-08-01

In a recent set of articles [J. C. Araque et al., J. Phys. Chem. B 119(23), 7015-7029 (2015) and J. C. Araque et al., J. Chem. Phys. 144, 204504 (2016)], we proposed the idea that for small neutral and charged solutes dissolved in ionic liquids, deviation from simple hydrodynamic predictions in translational and rotational dynamics can be explained in terms of diffusion through nano-environments that are stiff (high electrostriction, charge density, and number density) and others that are soft (charge depleted). The current article takes a purely solvent-centric approach in trying to provide molecular detail and intuitive visual understanding of time-dependent local mobility focusing on the most common case of an ionic liquid with well defined polar and apolar nano-domains. We find that at intermediate time scales, apolar regions are fluid, whereas the charge network is much less mobile. Because apolar domains and cationic heads must diffuse as single species, at long time the difference in mobility also necessarily dissipates.

Excess plasma membrane and effects of ionic amphipaths on mechanics of outer hair cell lateral wall.

PubMed

Morimoto, Noriko; Raphael, Robert M; Nygren, Anders; Brownell, William E

2002-05-01

The interaction between the outer hair cell (OHC) lateral wall plasma membrane and the underlying cortical lattice was examined by a morphometric analysis of cell images during cell deformation. Vesiculation of the plasma membrane was produced by micropipette aspiration in control cells and cells exposed to ionic amphipaths that alter membrane mechanics. An increase of total cell and vesicle surface area suggests that the plasma membrane possesses a membrane reservoir. Chlorpromazine (CPZ) decreased the pressure required for vesiculation, whereas salicylate (Sal) had no effect. The time required for vesiculation was decreased by CPZ, indicating that CPZ decreases the energy barrier required for vesiculation. An increase in total volume is observed during micropipette aspiration. A deformation-induced increase in hydraulic conductivity is also seen in response to micropipette-applied fluid jet deformation of the lateral wall. Application of CPZ and/or Sal decreased this strain-induced hydraulic conductivity. The impact of ionic amphipaths on OHC plasma membrane and lateral wall mechanics may contribute to their effects on OHC electromotility and hearing.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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),more » 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 commerically used thermal fluids. Also within the past decade nanofluids have gained attention for thermal conductivity enhancment of fluids, but little analysis has been completed on the heat capacity effects of the nanoparticle addition. The idea of ILs or nanofluids as a HTF is not new, as there are several references that have proposed the idea. However, the use of ionic liquid nanofluids containing nanomaterials other than carbon nanotubes has never before been studied. Here, for the first time, nano-particle enhanced ILs (NEILs) have been shown to increase the heat capacity of the IL with no adverse side effects to the ILs thermal stability and, only at high nanoparticle loading, are the IL physical properties affected. An increase of volumetric heat capacity translates into a better heat transfer fluid as more energy is stored per volumetric unit in the solar concentrating section, thus more efficency in increased steam pressure. Results show that the properties of the NEIL are highly dependant on the suspended nanomaterial and careful materials selection is required to fully optimize the nanofluid properties.« less

Osmoregulation, ionoregulation and acid-base regulation by the gastrointestinal tract after feeding in the elasmobranch (Squalus acanthias).

PubMed

Wood, Chris M; Kajimura, Makiko; Bucking, Carol; Walsh, Patrick J

2007-04-01

In order to study the physiological consequences of voluntary feeding in the gastrointestinal tract of a ureotelic marine elasmobranch, dogfish (fasted for 96 h) were sampled at various times up to 360 h after consuming a 5-6% ration of teleost fish (hake) under natural feeding conditions. Digestion and absorption were completed between 120 and 360 h post-feeding. The tissue masses of different segments of the gastrointestinal tract increased and decreased markedly as the chyme moved through, mainly because of fluid engorgement rather than hyperplasia. In fasted dogfish, the cardiac and pyloric stomachs contained only small volumes of highly acidic fluid (pH 1.77+/-1.12, 2.05+/-0.08) similar in composition to seawater. Feeding resulted in gastric pHs of 3.20+/-0.31 and 3.95+/-0.40 at 6 h, followed by slow declines through 60 h. An alkaline tide in the blood also occurred at 6 h. In the face of large changing masses of highly acidic chyme in the stomachs, the pH (6.50+/-0.10), ionic composition and volume of chyme in the intestine (spiral valve) were precisely regulated from 6 to 60 h post-feeding at very different values from those in the stomachs, and intestinal HCO3(-) remained low (5.12+/-0.83 mmol l(-1)). The colon was usually empty and its pH constant at 7.20+/-0.16 at all times. Despite the ingestion of strongly hypo-osmotic teleost tissue, the osmolality of the chyme remained in equilibrium with that of the blood plasma in all segments at all times after feeding. Much of the osmotic equilibration was because of the secretion of urea into the chyme, particularly in the intestine. After feeding, gastric fluid concentrations of Na(+) and Mg(2+) declined, K(+) and Ca(2+) increased, whereas Cl(-) exhibited little change, indicating that additional drinking of seawater was minimal. Na(+), K(+), water and especially Cl(-) were absorbed in the intestine, whereas Mg(2+) and Ca(2+) were largely excluded. Our results illustrate the complex integration of digestive and ionoregulatory function in the elasmobranch digestive tract, and marked differences from the teleost pattern.

Mathematical modeling of fluid-electrolyte alterations during weightlessness

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1984-01-01

Fluid electrolyte metabolism and renal endocrine control as it pertains to adaptation to weightlessness were studied. The mathematical models that have been particularly useful are discussed. However, the focus of the report is on the physiological meaning of the computer studies. A discussion of the major ground based analogs of weightlessness are included; for example, head down tilt, water immersion, and bed rest, and a comparison of findings. Several important zero g phenomena are described, including acute fluid volume regulation, blood volume regulation, circulatory changes, longer term fluid electrolyte adaptations, hormonal regulation, and body composition changes. Hypotheses are offered to explain the major findings in each area and these are integrated into a larger hypothesis of space flight adaptation. A conceptual foundation for fluid electrolyte metabolism, blood volume regulation, and cardiovascular regulation is reported.

Physicochemical hydrodynamics of porous structures in vascular plants

NASA Astrophysics Data System (ADS)

Ryu, Jeongeun; Ahn, Sungsook; Kim, Seung-Gon; Kim, Taejoo; Lee, Sang Joon

2013-11-01

Transport of sap flow through xylem conduits of vascular plants has been considered as a passive process, because the xylem conduits are regarded as inert, dead wood. However, plants can actively regulate water transport using ion-mediated response for adapting to environmental changes. In order to understand the active regulation mechanism of physicochemical hydrodynamics of porous structures in vascular plants, the effects of specific ion types and their ionic ratios on the water transport were experimentally investigated under in vivocondition. Based on the experimental results, the principle of ionic effects will be explained through in-vitro comparative experiments and theoretical considerations. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government (MSIP) (No. 2008-0061991).

Controlled drug release properties of ionically cross-linked chitosan beads: the influence of anion structure.

PubMed

Shu, X Z; Zhu, K J

2002-02-21

By adopting a novel chitosan cross-linked method, i.e. chitosan/gelatin droplet coagulated at low temperature and then cross-linked by anions (sulfate, citrate and tripolyphosphate (TPP)), the chitosan beads were prepared. Scanning electron microscopy (SEM) observation showed that sulfate/chitosan and citrate/chitosan beads usually had a spherical shape, smooth surface morphology and integral inside structure. Cross-sectional analysis indicated that the cross-linking process of sulfate and citrate to chitosan was much faster than that of TPP due to their smaller molecular size. But, once completely cross-linked, TPP/chitosan beads possessed much better mechanical strength and the force to break the beads was approximately ten times higher than that of sulfate/chitosan or citrate/chitosan beads. Release media pH and ionic strength seriously influenced the controlled drug release properties of the beads, which related to the strength of electrostatic interaction between anions and chitosan. Sulfate and citrate cross-linked chitosan beads swelled and even dissociated in simulated gastric fluid (SGF) and hence, model drug (riboflavin) released completely in 5 h; while in simulated intestinal fluid (SIF), beads remained in a shrinkage state and drug released slowly (release % usually <70% in 24 h). However, swelling and drug release of TPP/chitosan bead was usually insensitive to media pH. Chitosan beads, cross-linked by a combination of TPP and citrate (or sulfate) together, not only had a good shape, but also improved pH-responsive drug release properties. Salt weakened the interaction of citrate, especially sulfate with chitosan and accelerated beads swelling and hence drug release rate, but it was insensitive to that of TPP/chitosan. These results indicate that ionically cross-linked chitosan beads may be useful in stomach specific drug delivery.

Phase transitions and spatially ordered counterion association in ionic-lipid membranes: a statistical model.

PubMed

Tamashiro, M N; Barbetta, C; Germano, R; Henriques, V B

2011-09-01

We propose a statistical model to account for the gel-fluid anomalous phase transitions in charged bilayer- or lamellae-forming ionic lipids. The model Hamiltonian comprises effective attractive interactions to describe neutral-lipid membranes as well as the effect of electrostatic repulsions of the discrete ionic charges on the lipid headgroups. The latter can be counterion dissociated (charged) or counterion associated (neutral), while the lipid acyl chains may be in gel (low-temperature or high-lateral-pressure) or fluid (high-temperature or low-lateral-pressure) states. The system is modeled as a lattice gas with two distinct particle types--each one associated, respectively, with the polar-headgroup and the acyl-chain states--which can be mapped onto an Ashkin-Teller model with the inclusion of cubic terms. The model displays a rich thermodynamic behavior in terms of the chemical potential of counterions (related to added salt concentration) and lateral pressure. In particular, we show the existence of semidissociated thermodynamic phases related to the onset of charge order in the system. This type of order stems from spatially ordered counterion association to the lipid headgroups, in which charged and neutral lipids alternate in a checkerboard-like order. Within the mean-field approximation, we predict that the acyl-chain order-disorder transition is discontinuous, with the first-order line ending at a critical point, as in the neutral case. Moreover, the charge order gives rise to continuous transitions, with the associated second-order lines joining the aforementioned first-order line at critical end points. We explore the thermodynamic behavior of some physical quantities, like the specific heat at constant lateral pressure and the degree of ionization, associated with the fraction of charged lipid headgroups.

Ionic Asymmetry and Solvent Excluded Volume Effects on Spherical Electric Double Layers: A Density Functional Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medasani, Bharat; Ovanesyan, Zaven; Thomas, Dennis G.

In this article we present a classical density functional theory for electrical double layers of spherical macroions that extends the capabilities of conventional approaches by accounting for electrostatic ion correlations, size asymmetry and excluded volume effects. The approach is based on a recent approximation introduced by Hansen-Goos and Roth for the hard sphere excess free energy of inhomogeneous fluids (J. Chem. Phys. 124, 154506). It accounts for the proper and efficient description of the effects of ionic asymmetry and solvent excluded volume, especially at high ion concentrations and size asymmetry ratios including those observed in experimental studies. Additionally, we utilizemore » a leading functional Taylor expansion approximation of the ion density profiles. In addition, we use the Mean Spherical Approximation for multi-component charged hard sphere fluids to account for the electrostatic ion correlation effects. These approximations are implemented in our theoretical formulation into a suitable decomposition of the excess free energy which plays a key role in capturing the complex interplay between charge correlations and excluded volume effects. We perform Monte Carlo simulations in various scenarios to validate the proposed approach, obtaining a good compromise between accuracy and computational cost. We use the proposed computational approach to study the effects of ion size, ion size asymmetry and solvent excluded volume on the ion profiles, integrated charge, mean electrostatic potential, and ionic coordination number around spherical macroions in various electrolyte mixtures. Our results show that both solvent hard sphere diameter and density play a dominant role in the distribution of ions around spherical macroions, mainly for experimental water molarity and size values where the counterion distribution is characterized by a tight binding to the macroion, similar to that predicted by the Stern model.« less

Development of a Physiologically Based Computational Kidney Model to Describe the Renal Excretion of Hydrophilic Agents in Rats

PubMed Central

Niederalt, Christoph; Wendl, Thomas; Kuepfer, Lars; Claassen, Karina; Loosen, Roland; Willmann, Stefan; Lippert, Joerg; Schultze-Mosgau, Marcus; Winkler, Julia; Burghaus, Rolf; Bräutigam, Matthias; Pietsch, Hubertus; Lengsfeld, Philipp

2013-01-01

A physiologically based kidney model was developed to analyze the renal excretion and kidney exposure of hydrophilic agents, in particular contrast media, in rats. In order to study the influence of osmolality and viscosity changes, the model mechanistically represents urine concentration by water reabsorption in different segments of kidney tubules and viscosity dependent tubular fluid flow. The model was established using experimental data on the physiological steady state without administration of any contrast media or drugs. These data included the sodium and urea concentration gradient along the cortico-medullary axis, water reabsorption, urine flow, and sodium as well as urea urine concentrations for a normal hydration state. The model was evaluated by predicting the effects of mannitol and contrast media administration and comparing to experimental data on cortico-medullary concentration gradients, urine flow, urine viscosity, hydrostatic tubular pressures and single nephron glomerular filtration rate. Finally the model was used to analyze and compare typical examples of ionic and non-ionic monomeric as well as non-ionic dimeric contrast media with respect to their osmolality and viscosity. With the computational kidney model, urine flow depended mainly on osmolality, while osmolality and viscosity were important determinants for tubular hydrostatic pressure and kidney exposure. The low diuretic effect of dimeric contrast media in combination with their high intrinsic viscosity resulted in a high viscosity within the tubular fluid. In comparison to monomeric contrast media, this led to a higher increase in tubular pressure, to a reduction in glomerular filtration rate and tubular flow and to an increase in kidney exposure. The presented kidney model can be implemented into whole body physiologically based pharmacokinetic models and extended in order to simulate the renal excretion of lipophilic drugs which may also undergo active secretion and reabsorption. PMID:23355822

Roles of interstitial fluid pH in diabetes mellitus: Glycolysis and mitochondrial function

PubMed Central

Marunaka, Yoshinori

2015-01-01

The pH of body fluids is one the most important key factors regulating various cell function such as enzyme activity and protein-protein interaction via modification of its binding affinity. Therefore, to keep cell function normal, the pH of body fluids is maintained constant by various systems. Insulin resistance is one of the most important, serious factors making the body condition worse in diabetes mellitus. I have recently found that the pH of body (interstitial) fluids is lower in diabetes mellitus than that in non-diabetic control, and that the lowered pH is one of the causes producing insulin resistance. In this review article, I introduce importance of body (interstitial) fluid pH in regulation of body function, evidence on abnormal regulation of body fluid pH in diabetes mellitus, and relationship between the body fluid pH and insulin resistance. Further, this review proposes perspective therapies on the basis of regulation of body fluid pH including propolis (honeybee product) diet. PMID:25685283

The influence of ionic strength on carbonate-based spectroscopic barometry for aqueous fluids: an in-situ Raman study on Na2CO3-NaCl solutions

PubMed Central

Wu, Jia; Wang, Shixia; Zheng, Haifei

2016-01-01

The Raman wavenumber of the symmetric stretching vibration of carbonate ion (ν1-CO32−) was measured in three aqueous solutions containing 2.0 mol·L−1 Na2CO3 and 0.20, 0.42, or 0.92 mol·L−1 NaCl, respectively, from 122 to 1538 MPa at 22 °C using a moissanite anvil cell. The ν1 Raman signal linearly shifted to higher wavenumbers with increasing pressure. Most importantly, the slope of ν1-CO32− Raman frequency shift (∂ν1/∂P)I was independent of NaCl concentration. Moreover, elevated ionic strength was found to shift the apparent outline of the carbonate peak toward low wavenumbers, possibly by increasing the proportion of the contact ion pair NaCO3−. Further investigations revealed no cross-interaction between the pressure effect and the ionic strength effect on the Raman spectra, possibly because the distribution of different ion-pair species in the carbonate equilibrium was largely pressure-independent. These results suggested that the ionic strength should be incorporated as an additional constraint for measuring the internal pressure of various solution-based systems. Combining the ν1-CO32− Raman frequency slope with the pressure herein with the values for the temperature or the ionic strength dependencies determined from previous studies, we developed an empirical equation that can be used to estimate the pressure of carbonate-bearing aqueous solutions. PMID:27982064

Quasi-Chemical PC-SAFT: An Extended Perturbed Chain-Statistical Associating Fluid Theory for Lattice-Fluid Mixtures.

PubMed

Parvaneh, Khalil; Shariati, Alireza

2017-09-07

In this study, a new modification of the perturbed chain-statistical associating fluid theory (PC-SAFT) has been proposed by incorporating the lattice fluid theory of Guggenheim as an additional term to the original PC-SAFT terms. As the proposed model has one more term than the PC-SAFT, a new mixing rule has been developed especially for the new additional term, while for the conventional terms of the PC-SAFT, the one-fluid mixing rule is used. In order to evaluate the proposed model, the vapor-liquid equilibria were estimated for binary CO 2 mixtures with 16 different ionic liquids (ILs) of the 1-alkyl-3-methylimidazolium family with various anions consisting of bis(trifluoromethylsulfonyl) imide, hexafluorophosphate, tetrafluoroborate, and trifluoromethanesulfonate. For a comprehensive comparison, three different modes (different adjustable parameters) of the proposed model were compared with the conventional PC-SAFT. Results indicate that the proposed modification of the PC-SAFT EoS is generally more reliable with respect to the conventional PC-SAFT in all the three proposed modes of vapor-liquid equilibria, giving good agreement with literature data.

Effect of alginate composition on profile release and characteristics of chitosan-alginate microparticles loaded with mangosteen extract

NASA Astrophysics Data System (ADS)

Mulia, Kamarza; Halimah, Nur; Krisanti, Elsa

2017-03-01

Preparation of mangostin-loaded chitosan-alginate microparticles, chemical and physical characterization of the particles, and mangostin release profiles, are described herein. Mangostin rich fraction was obtained from Garcinia mangostana L. pericarp by extraction followed by fractionation. Mangostin-loaded chitosan-alginate microparticles were prepared by ionic gelation method using tripolyphosphate as the linking agent and various concentration of alginate. Mangostin was effectively loaded in all microparticle formulations, resulting in ˜97% encapsulation efficiencies. The loading of mangostin and the in-vitro release profiles in simulated gastrointestinal fluids were affected by the chitosan to alginate ratios used in the preparation of the microparticles. Increased alginate concentration resulted in lowered release of mangostin from microparticles immersed in simulated gastric fluid (pH 1.2) up to two hours. Low release of mangostin in acidic fluid but high release in simulated colon fluid, indicated that the chitosan-alginate microparticles are prospective carrier for extended release of active compound in gastrointestinal system.

Exogenous trehalose largely alleviates ionic unbalance, ROS burst, and PCD occurrence induced by high salinity in Arabidopsis seedlings

PubMed Central

Yang, Lei; Zhao, Xiaoju; Zhu, Hong; Paul, Matthew; Zu, Yuangang; Tang, Zhonghua

2014-01-01

Trehalose (Tre) has been reported to play a critical role in plant response to salinity and the involved mechanisms remain to be investigated in detail. Here, the putative roles of Tre in regulation of ionic balance, cellular redox state, cell death were studied in Arabidopsis under high salt condition. Our results found that the salt-induced restrictions on both vegetative and reproductive growth in salt-stressed plants were largely alleviated by exogenous supply with Tre. The microprobe analysis of ionic dynamics in the leaf and stem of florescence highlighted the Tre ability to retain K and K/Na ratio in plant tissues to improve salt tolerance. The flow cytometry assay of cellular levels of reactive oxygen species and programmed cell death displayed that Tre was able to antagonized salt-induced damages in redox state and cell death and sucrose did not play the same role with Tre. By comparing ionic distribution in leaf and inflorescence stem (IS), we found that Tre was able to restrict Na transportation to IS from leaves since that the ratio of Na accumulation in leaves relative to IS was largely improved due to Tre. The marked decrease of Na ion and improved sucrose level in IS might account for the promoted floral growth when Tre was included in the saline solution. At the same time, endogenous soluble sugars and antioxidant enzyme activities in the salt-stressed plants were also elevated by Tre to counteract high salt stress. We concluded that Tre could improve Arabidopsis salt resistance with respect to biomass accumulation and floral transition in the means of regulating plant redox state, cell death, and ionic distribution. PMID:25400644

Inorganic ion composition in Tardigrada: cryptobionts contain a large fraction of unidentified organic solutes.

PubMed

Halberg, Kenneth Agerlin; Larsen, Kristine Wulff; Jørgensen, Aslak; Ramløv, Hans; Møbjerg, Nadja

2013-04-01

Many species of tardigrades are known to tolerate extreme environmental stress, yet detailed knowledge of the mechanisms underlying the remarkable adaptations of tardigrades is still lacking, as are answers to many questions regarding their basic biology. Here, we present data on the inorganic ion composition and total osmotic concentration of five different species of tardigrades (Echiniscus testudo, Milnesium tardigradum, Richtersius coronifer, Macrobiotus cf. hufelandi and Halobiotus crispae) using high-performance liquid chromatography and nanoliter osmometry. Quantification of the ionic content indicates that Na(+) and Cl(-) are the principal inorganic ions in tardigrade fluids, albeit other ions, i.e. K(+), NH4(+), Ca(2+), Mg(2+), F(-), SO4(2-) and PO4(3-) were also detected. In limno-terrestrial tardigrades, the respective ions are concentrated by a large factor compared with that of the external medium (Na(+), ×70-800; K(+), ×20-90; Ca(2+) and Mg(2+), ×30-200; F(-), ×160-1040, Cl(-), ×20-50; PO4(3-), ×700-2800; SO4(2-), ×30-150). In contrast, in the marine species H. crispae, Na(+), Cl(-) and SO4(2-) are almost in ionic equilibrium with (brackish) salt water, while K(+), Ca(2+), Mg(2+) and F(-) are only slightly concentrated (×2-10). An anion deficit of ~120 mEq l(-1) in M. tardigradum and H. crispae indicates the presence of unidentified ionic components in these species. Body fluid osmolality ranges from 361±49 mOsm kg(-1) in R. coronifer to 961±43 mOsm kg(-1) in H. crispae. Concentrations of most inorganic ions are largely identical between active and dehydrated groups of R. coronifer, suggesting that this tardigrade does not lose large quantities of inorganic ions during dehydration. The large osmotic and ionic gradients maintained by both limno-terrestrial and marine species are indicative of a powerful ion-retentive mechanism in Tardigrada. Moreover, our data indicate that cryptobiotic tardigrades contain a large fraction of unidentified organic osmolytes, the identification of which is expected to provide increased insight into the phenomenon of cryptobiosis.

Time-dependent chemo-electro-mechanical behavior of hydrogel-based structures

NASA Astrophysics Data System (ADS)

Leichsenring, Peter; Wallmersperger, Thomas

2018-03-01

Charged hydrogels are ionic polymer gels and belong to the class of smart materials. These gels are multiphasic materials which consist of a solid phase, a fluid phase and an ionic phase. Due to the presence of bound charges these materials are stimuli-responsive to electrical or chemical loads. The application of electrical or chemical stimuli as well as mechanical loads lead to a viscoelastic response. On the macroscopic scale, the response is governed by a local reversible release or absorption of water which, in turn, leads to a local decrease or increase of mass and a respective volume change. Furthermore, the chemo-electro-mechanical equilibrium of a hydrogel depends on the chemical composition of the gel and the surrounding solution bath. Due to the presence of bound charges in the hydrogel, this system can be understood as an osmotic cell where differences in the concentration of mobile ions in the gel and solution domain lead to an osmotic pressure difference. In the present work, a continuum-based numerical model is presented in order to describe the time-dependent swelling behavior of hydrogels. The numerical model is based on the Theory of Porous Media and captures the fluid-solid, fluid-ion and ion-ion interactions. As a direct consequence of the chemo-electro-mechanical equilibrium, the corresponding boundary conditions are defined following the equilibrium conditions. For the interaction of the hydrogel with surrounding mechanical structures, also respective jump condtions are formulated. Finaly, numerical results of the time-dependent behavior of a hydrogel-based chemo-sensor will be presented.

Wavelet analysis of corneal endothelial electrical potential difference reveals cyclic operation of the secretory mechanism.

PubMed

Cacace, V I; Montalbetti, N; Kusnier, C; Gomez, M P; Fischbarg, J

2011-09-01

The corneal endothelium is a fluid-transporting epithelium. As other similar tissues, it displays an electrical potential of ~1 mV (aqueous side negative) across the entire layer [transendothelial potential difference (TEPD)]. It appears that this electrical potential is mainly the result of the transport of anions across the cell layer (from stroma to aqueous). There is substantial evidence that the TEPD is related linearly to fluid transport; hence, under proper conditions, its measure could serve as a measure of fluid transport. Furthermore, the TEPD is not steady; instead, it displays a spectrum of frequency components (0-15 Hz) recognized recently using Fourier transforms. Such frequency components appear due to charge-separating (electrogenic) processes mediated by epithelial plasma membrane proteins (both ionic channels and ionic cotransporters). In particular, the endothelial TEPD oscillations of the highest amplitude (1-2 Hz) were linked to the operation of so-called sodium bicarbonate cotransporters. However, no time localization of that activity could be obtained with the Fourier methodology utilized. For that reason we now characterize the TEPD using wavelet analysis with the aim to localize in time the variations in TEPD. We find that the mentioned high-amplitude oscillatory components of the TEPD appear cyclically during the several hours that an endothelial preparation survives in vitro. They have a period of 4.6 ± 0.4 s on average (n=4). The wavelet power value at the peak of such oscillations is 1.5 ± 0.1 mV(2) Hz on average (n = 4), and is remarkably narrow in its distribution.

Spatial distribution of mechanical forces and ionic flux in electro-kinetic instability near a permselective membrane

NASA Astrophysics Data System (ADS)

Magnico, Pierre

2018-01-01

This paper is devoted to the numerical investigation of electro-kinetic instability in a polarization layer next to a cation-exchange membrane. An analysis of some properties of the electro-kinetic instability is followed by a detailed description of the fluid flow structure and of the spatial distribution of the ionic flux. In this aim, the Stokes-Poisson-Nernst-Planck equation set is solved until the Debye length scale. The results show that the potential threshold of the marginal instability and the current density depend on the logarithm of the concentration at the membrane surface. The size of the stable vortices seems to be an increasing function of the potential drop. The fluid motion is induced by the electric force along the maximum concentration in the extended space charge (ESC) region and by the pressure force in the region around the inner edge of the ESC layer. Two spots of kinetic energy are located in the ESC region and between the vortices. The cationic motion, controlled by the electric field and the convection, presents counter-rotating vortices in the stagnation zone located in the fluid ejection region. The anion transport is also characterized by two independent layers which contain counter-rotating vortices. The first one is in contact with the stationary reservoir. In the second layer against the membrane, the convection, and the electric field control, the transversal motion, the Fickian diffusion, and the convection are dominant in the longitudinal direction. Finally, the longitudinal disequilibrium of potential and pressure along the membrane is analyzed.

Temperature Effect on Micelle Formation: Molecular Thermodynamic Model Revisited.

PubMed

Khoshnood, Atefeh; Lukanov, Boris; Firoozabadi, Abbas

2016-03-08

Temperature affects the aggregation of macromolecules such as surfactants, polymers, and proteins in aqueous solutions. The effect on the critical micelle concentration (CMC) is often nonmonotonic. In this work, the effect of temperature on the micellization of ionic and nonionic surfactants in aqueous solutions is studied using a molecular thermodynamic model. Previous studies based on this technique have predicted monotonic behavior for ionic surfactants. Our investigation shows that the choice of tail transfer energy to describe the hydrophobic effect between the surfactant tails and the polar solvent molecules plays a key role in the predicted CMC. We modify the tail transfer energy by taking into account the effect of the surfactant head on the neighboring methylene group. The modification improves the description of the CMC and the predicted micellar size for aqueous solutions of sodium n-alkyl sulfate, dodecyl trimethylammonium bromide (DTAB), and n-alkyl polyoxyethylene. The new tail transfer energy describes the nonmonotonic behavior of CMC versus temperature. In the DTAB-water system, we redefine the head size by including the methylene group, next to the nitrogen, in the head. The change in the head size along with our modified tail transfer energy improves the CMC and aggregation size prediction significantly. Tail transfer is a dominant energy contribution in micellar and microemulsion systems. It also promotes the adsorption of surfactants at fluid-fluid interfaces and affects the formation of adsorbed layer at fluid-solid interfaces. Our proposed modifications have direct applications in the thermodynamic modeling of the effect of temperature on molecular aggregation, both in the bulk and at the interfaces.

Electrochemical cell structure and method of making the same

DOEpatents

Schick, Louis Andrew; Libby, Cara Suzanne; Bowen, John Henry; Bourgeois, Richard Scott

2012-09-25

An electrochemical cell structure is provided which includes an anode, a cathode spaced apart from said anode, an electrolyte in ionic communication with each of said anode and said cathode and a nonconductive frame. The nonconductive frame includes at least two components that support each of said anode, said cathode and said electrolyte and define at least one flowpath for working fluids and for products of electrochemical reaction.

Bone regeneration: molecular and cellular interactions with calcium phosphate ceramics

PubMed Central

Barrère, Florence; van Blitterswijk, Clemens A; de Groot, Klaas

2006-01-01

Calcium phosphate bioceramics are widely used in orthopedic and dental applications and porous scaffolds made of them are serious candidates in the field of bone tissue engineering. They have superior properties for the stimulation of bone formation and bone bonding, both related to the specific interactions of their surface with the extracellular fluids and cells, ie, ionic exchanges, superficial molecular rearrangement and cellular activity. PMID:17717972

The Leaky Dielectric Model as a Weak Electrolyte Limit of an Electrodiffusion Model

NASA Astrophysics Data System (ADS)

Mori, Yoichiro; Young, Yuan-Nan

2017-11-01

The Taylor-Melcher (TM) model is the standard model for the electrohydrodynamics of poorly conducting leaky dielectric fluids under an electric field. The TM model treats the fluid as an ohmic conductor, without modeling ion dynamics. On the other hand, electrodiffusion models, which have been successful in describing electokinetic phenomena, incorporates ionic concentration dynamics. Mathematical reconciliation between electrodiffusion and the TM models has been a major issue for electrohydrodynamic theory. Here, we derive the TM model from an electrodiffusion model where we explicitly model the electrochemistry of ion dissociation. We introduce salt dissociation reaction in the bulk and take the limit of weak salt dissociation (corresponding to poor conductors in the TM model.) Assuming small Debye length we derive the TM model with or without the surface charge advection term depending upon the scaling of relevant dimensionless parameters. Our analysis also gives a description of the ionic concentration distribution within the Debye layer, which hints at possible scenarios for electrohydrodynamic singularity formation. In our analysis we also allow for a jump in voltage across the liquid interface which causes a drifting velocity for a liquid drop under an electric field. YM is partially supported by NSF-DMS-1516978 and NSF-DMS-1620316. YNY is partially supported by NSF-DMS-1412789 and NSF-DMS-1614863.

Dielectric properties of classical and quantized ionic fluids.

PubMed

Høye, Johan S

2010-06-01

We study time-dependent correlation functions of classical and quantum gases using methods of equilibrium statistical mechanics for systems of uniform as well as nonuniform densities. The basis for our approach is the path integral formalism of quantum mechanical systems. With this approach the statistical mechanics of a quantum mechanical system becomes the equivalent of a classical polymer problem in four dimensions where imaginary time is the fourth dimension. Several nontrivial results for quantum systems have been obtained earlier by this analogy. Here, we will focus upon the presence of a time-dependent electromagnetic pair interaction where the electromagnetic vector potential that depends upon currents, will be present. Thus both density and current correlations are needed to evaluate the influence of this interaction. Then we utilize that densities and currents can be expressed by polarizations by which the ionic fluid can be regarded as a dielectric one for which a nonlocal susceptibility is found. This nonlocality has as a consequence that we find no contribution from a possible transverse electric zero-frequency mode for the Casimir force between metallic plates. Further, we establish expressions for a leading correction to ab initio calculations for the energies of the quantized electrons of molecules where now retardation effects also are taken into account.

Gas-liquid phase coexistence and crossover behavior of binary ionic fluids with screened Coulomb interactions.

PubMed

Patsahan, O

2014-06-01

We study the effects of an interaction range on the gas-liquid phase diagram and the crossover behavior of a simple model of ionic fluids: an equimolar binary mixture of equisized hard spheres interacting through screened Coulomb potentials which are repulsive between particles of the same species and attractive between particles of different species. Using the collective variables theory, we find explicit expressions for the relevant coefficients of the effective φ{4} Ginzburg-Landau Hamiltonian in a one-loop approximation. Within the framework of this approximation, we calculate the critical parameters and gas-liquid phase diagrams for varying inverse screening length z. Both the critical temperature scaled by the Yukawa potential contact value and the critical density rapidly decrease with an increase of the interaction range (a decrease of z) and then for z<0.05 they slowly approach the values found for a restricted primitive model (RPM). We find that gas-liquid coexistence region reduces with an increase of z and completely vanishes at z≃2.78. Our results clearly show that an increase in the interaction range leads to a decrease of the crossover temperature. For z≃0.01, the crossover temperature is the same as for the RPM.

Thermal management of advanced fuel cell power systems

NASA Technical Reports Server (NTRS)

Vanderborgh, N. E.; Hedstrom, J.; Huff, J.

1990-01-01

It is shown that fuel cell devices are particularly attractive for the high-efficiency, high-reliability space hardware necessary to support upcoming space missions. These low-temperature hydrogen-oxygen systems necessarily operate with two-phase water. In either PEMFCs (proton exchange membrane fuel cells) or AFCs (alkaline fuel cells), engineering design must be critically focused on both stack temperature control and on the relative humidity control necessary to sustain appropriate conductivity within the ionic conductor. Water must also be removed promptly from the hardware. Present designs for AFC space hardware accomplish thermal management through two coupled cooling loops, both driven by a heat transfer fluid, and involve a recirculation fan to remove water and heat from the stack. There appears to be a certain advantage in using product water for these purposes within PEM hardware, because in that case a single fluid can serve both to control stack temperature, operating simultaneously as a heat transfer medium and through evaporation, and to provide the gas-phase moisture levels necessary to set the ionic conductor at appropriate performance levels. Moreover, the humidification cooling process automatically follows current loads. This design may remove the necessity for recirculation gas fans, thus demonstrating the long-term reliability essential for future space power hardware.

Safe Direct Current Stimulation to Expand Capabilities of Neural Prostheses

PubMed Central

Fridman, Gene Y.; Della Santina, Charles C.

2014-01-01

While effective in treating some neurological disorders, neuroelectric prostheses are fundamentally limited because they must employ charge-balanced stimuli to avoid evolution of irreversible electrochemical reactions and their byproducts at the interface between metal electrodes and body fluids. Charge-balancing is typically achieved by using brief biphasic alternating current (AC) pulses, which typically excite nearby neural tissues but cannot efficiently inhibit them. In contrast, direct current (DC) applied via a metal electrode in contact with body fluids can excite, inhibit and modulate sensitivity of neurons; however, DC stimulation is biologically unsafe because it violates “safe charge injection” limits that have long been considered unavoidable constraints. In this report, we describe the design and fabrication of a safe DC stimulator (SDCS) that overcomes this constraint. The SCDS drives DC ionic current into target tissue via salt-bridge micropipette electrodes by switching valves in phase with AC square waves applied to metal electrodes contained within the device. This approach achieves DC ionic flow through tissue while still adhering to charge-balancing constraints at each electrode-saline interface. We show the SDCS’s ability to both inhibit and excite neural activity to achieve improved dynamic range during prosthetic stimulation of the vestibular part of the inner ear in chinchillas. PMID:23476007

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 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. Electronic supplementary information (ESI) available: Experimental procedures, synthesis, and characterization of molecules 1, 2 and 3. Explanation of the electrochemical method for approximating nanopore diameter. Additional XPS spectra. See DOI: 10.1039/C5NR02939B

Mussel adhesion – essential footwork

PubMed Central

2017-01-01

ABSTRACT Robust adhesion to wet, salt-encrusted, corroded and slimy surfaces has been an essential adaptation in the life histories of sessile marine organisms for hundreds of millions of years, but it remains a major impasse for technology. Mussel adhesion has served as one of many model systems providing a fundamental understanding of what is required for attachment to wet surfaces. Most polymer engineers have focused on the use of 3,4-dihydroxyphenyl-l-alanine (Dopa), a peculiar but abundant catecholic amino acid in mussel adhesive proteins. The premise of this Review is that although Dopa does have the potential for diverse cohesive and adhesive interactions, these will be difficult to achieve in synthetic homologs without a deeper knowledge of mussel biology; that is, how, at different length and time scales, mussels regulate the reactivity of their adhesive proteins. To deposit adhesive proteins onto target surfaces, the mussel foot creates an insulated reaction chamber with extreme reaction conditions such as low pH, low ionic strength and high reducing poise. These conditions enable adhesive proteins to undergo controlled fluid–fluid phase separation, surface adsorption and spreading, microstructure formation and, finally, solidification. PMID:28202646

Acid-base physiology, neurobiology and behaviour in relation to CO2-induced ocean acidification.

PubMed

Tresguerres, Martin; Hamilton, Trevor J

2017-06-15

Experimental exposure to ocean and freshwater acidification affects the behaviour of multiple aquatic organisms in laboratory tests. One proposed cause involves an imbalance in plasma chloride and bicarbonate ion concentrations as a result of acid-base regulation, causing the reversal of ionic fluxes through GABA A receptors, which leads to altered neuronal function. This model is exclusively based on differential effects of the GABA A receptor antagonist gabazine on control animals and those exposed to elevated CO 2 However, direct measurements of actual chloride and bicarbonate concentrations in neurons and their extracellular fluids and of GABA A receptor properties in aquatic organisms are largely lacking. Similarly, very little is known about potential compensatory mechanisms, and about alternative mechanisms that might lead to ocean acidification-induced behavioural changes. This article reviews the current knowledge on acid-base physiology, neurobiology, pharmacology and behaviour in relation to marine CO 2 -induced acidification, and identifies important topics for future research that will help us to understand the potential effects of predicted levels of aquatic acidification on organisms. © 2017. Published by The Company of Biologists Ltd.

In vitro bioactivity of novel tricalcium silicate ceramics.

PubMed

Zhao, Wenyuan; Chang, Jiang; Wang, Junying; Zhai, Wanyin; Wang, Zheng

2007-05-01

In this study, bone-like apatite-formation ability of tricalcium silicate (Ca(3)SiO(5)) ceramics in simulated body fluid (SBF) was evaluated and the in vitro degradability was investigated by soaking in Ringer's solution. The effect of ionic products from Ca(3)SiO(5) dissolution on osteobalsts proliferation was investigated. The result indicated that hydroxyapatite (HA) was formed on the surface of the Ca(3)SiO(5) ceramics after soaking in SBF for 1 day, and Ca(3)SiO(5) ceramics could degraded in Ringer's solution. The Si ions from Ca(3)SiO(5) dissolution at certain concentration range significantly stimulated osteoblasts proliferation. Our results show that Ca(3)SiO(5) ceramics possess bone-like apatite-formation ability and degradability, and can release soluble ionic products to stimulate cell proliferation.

Modelling technological process of ion-exchange filtration of fluids in porous media

NASA Astrophysics Data System (ADS)

Ravshanov, N.; Saidov, U. M.

2018-05-01

Solution of an actual problem related to the process of filtration and dehydration of liquid and ionic solutions from gel particles and heavy ionic compounds is considered in the paper. This technological process is realized during the preparation and cleaning of chemical solutions, drinking water, pharmaceuticals, liquid fuels, products for public use, etc. For the analysis, research, determination of the main parameters of the technological process and operating modes of filter units and for support in managerial decision-making, a mathematical model is developed. Using the developed model, a series of computational experiments on a computer is carried out. The results of numerical calculations are illustrated in the form of graphs. Based on the analysis of numerical experiments, the conclusions are formulated that serve as the basis for making appropriate managerial decisions.

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.

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.

Mobile monolithic polymer elements for flow control in microfluidic devices

DOEpatents

Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.

2004-08-31

A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by either fluid or gas pressure against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

Mobile Monolith Polymer Elements For Flow Control In Microfluidic Systems

DOEpatents

Hasselbrink, Jr., Ernest F.; Rehm, Jason E.; Shepodd, Timothy J.; Kirby, Brian J.

2006-01-24

A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

Mobile monolithic polymer elements for flow control in microfluidic devices

DOEpatents

Hasselbrink, Jr., Ernest F.; Rehm, Jason E [Alameda, CA; Shepodd, Timothy J [Livermore, CA; Kirby, Brian J [San Francisco, CA

2005-11-11

A cast-in-place and lithographically shaped mobile, monolithic polymer element for fluid flow control in microfluidic devices and method of manufacture. Microfluid flow control devices, or microvalves that provide for control of fluid or ionic current flow can be made incorporating a cast-in-place, mobile monolithic polymer element, disposed within a microchannel, and driven by fluid pressure (either liquid or gas) against a retaining or sealing surface. The polymer elements are made by the application of lithographic methods to monomer mixtures formulated in such a way that the polymer will not bond to microchannel walls. The polymer elements can seal against pressures greater than 5000 psi, and have a response time on the order of milliseconds. By the use of energetic radiation it is possible to depolymerize selected regions of the polymer element to form shapes that cannot be produced by conventional lithographic patterning and would be impossible to machine.

Methods for forming small-volume electrical contacts and material manipulations with fluid microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-12-27

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Effects of CSF hormones and ionic composition on salt/water metabolism

NASA Technical Reports Server (NTRS)

Severs, Walter B.

1992-01-01

The consequences of headward fluid shifts during manned spaceflight was studied. Such shifts were recognized early by both U.S. and Soviet scientists because of signs and symptoms referable to the head. Some of these include disturbed vision, puffiness in the face and periorbital areas, headache, vestibular dysfunction, and distended jugular veins. We posited that the fluid shift had an immediate effect on the brain and a long-term action requiring a neural interpretation of the flight environment. This would re-adjust both efferent neural as well as hormonal mechanisms to sustain cardiovascular and fluid/electrolyte balance consonent with survival in microgravity. Work along these lines is summarized. A synopsis of some of the main research is presented. The following topics were studied: (1) angiotensin and vasopressin action in the central nervous system; (2) intracranial pressure control; (3) research on subcommissural organ; and (4) research on the eye.

Kirigami artificial muscles with complex biologically inspired morphologies

NASA Astrophysics Data System (ADS)

Sareh, Sina; Rossiter, Jonathan

2013-01-01

In this paper we present bio-inspired smart structures which exploit the actuation of flexible ionic polymer composites and the kirigami design principle. Kirigami design is used to convert planar actuators into active 3D structures capable of large out-of-plane displacement and that replicate biological mechanisms. Here we present the burstbot, a fluid control and propulsion mechanism based on the atrioventricular cuspid valve, and the vortibot, a spiral actuator based on Vorticella campanula, a ciliate protozoa. Models derived from biological counterparts are used as a platform for design optimization and actuator performance measurement. The symmetric and asymmetric fluid interactions of the burstbot are investigated and the effectiveness in fluid transport applications is demonstrated. The vortibot actuator is geometrically optimized as a camera positioner capable of 360° scanning. Experimental results for a one-turn spiral actuator show complex actuation derived from a single degree of freedom control signal.

Identification of Zebrafish Fxyd11a Protein that is Highly Expressed in Ion-Transporting Epithelium of the Gill and Skin and its Possible Role in Ion Homeostasis

PubMed Central

Saito, Kaori; Nakamura, Nobuhiro; Ito, Yusuke; Hoshijima, Kazuyuki; Esaki, Masahiro; Zhao, Boqiang; Hirose, Shigehisa

2010-01-01

FXYD proteins, small single-transmembrane proteins, have been proposed to be auxiliary regulatory subunits of Na+–K+-ATPase and have recently been implied in ion osmoregulation of teleost fish. In freshwater (FW) fish, numerous ions are actively taken up through mitochondrion-rich cells (MRCs) of the gill and skin epithelia, using the Na+ electrochemical gradient generated by Na+–K+-ATPase. In the present study, to understand the molecular mechanism for the regulation of Na+–K+-ATPase in MRCs of FW fish, we sought to identify FXYD proteins expressed in MRCs of zebrafish. Reverse-transcriptase PCR studies of adult zebrafish tissues revealed that, out of eight fxyd genes found in zebrafish database, only zebrafish fxyd11 (zfxyd11) mRNA exhibited a gill-specific expression. Double immunofluorescence staining showed that zFxyd11 is abundantly expressed in MRCs rich in Na+–K+-ATPase (NaK-MRCs) but not in those rich in vacuolar-type H+-transporting ATPase. An in situ proximity ligation assay demonstrated its close association with Na+–K+-ATPase in NaK-MRCs. The zfxyd11 mRNA expression was detectable at 1 day postfertilization, and its expression levels in the whole larvae and adult gills were regulated in response to changes in environmental ionic concentrations. Furthermore, knockdown of zFxyd11 resulted in a significant increase in the number of Na+–K+-ATPase–positive cells in the larval skin. These results suggest that zFxyd11 may regulate the transport ability of NaK-MRCs by modulating Na+–K+-ATPase activity, and may be involved in the regulation of body fluid and electrolyte homeostasis. PMID:21423371

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

Colloidal behavior of aqueous montmorillonite suspensions in the presence of non-ionic polymer

NASA Astrophysics Data System (ADS)

Gareche, M.; Azri, N.; Allal, A.; Zeraibi, N.

2015-04-01

In this paper we characterized at first, the rheological behavior of the bentonite suspensions and the aqueous solutions of polyethylene oxide (PEO), then we were investigated the influence of this polymer in a water-based drilling fluid model (6% of bentonite suspension). The objective is to exhibit how the non ionic polymer with molecular weight 6×103 g/mol. of varying concentration mass (0.7%, 1%, 2% et 3%) significantly alter the rheological properties (yield stress, viscosity, loss and elastic modulus) of the bentonite suspensions. The rheological measurements made in simple shear and in dynamic on the mixture (water-bentonite-PEO), showed rheological properties of bentonite suspensions both in the presence and absence of non-ionic polymer. The PEO presents an affinity for the bentonite particles slowing down their kinetic aggregation. The analysis by X-rays diffraction also allowed understanding the structure of this mixture. It had revealed the intercalation between of the clay platelets on one hand, and the links bridges assured by the chains of polymer between bentonite particles beyond a critical concentration in PEO on the other hand. The Herschel- Bulkley rheological model is used for the correlation of our experimental results.

New laboratory approach to study Titan ionospheric chemistry

NASA Astrophysics Data System (ADS)

Thissen, R.; Dutuit, O.; Pernot, P.; Carrasco, N.; Lilensten, J.; Quirico, E.; Schmitt, B.

The exploration of Titan reveals a very complex chemistry occurring in the ionospheric region of the atmosphere. In order to interpret the observations performed by the Cassini spectrometers, we need to improve our description of the ion molecule chemistry involving nitrogen and hydrocarbons. Up to now, models are based on databases compiled over the years. These are quite complete to describe the major ions, but lack of accuracy for some of them, they totally neglect the questions of isomerization or chemical functionality in the description of ionic species and still miss a lot of inputs for ionic species heavier than 50 daltons. We propose to improve the databases by systematic measurements of ion molecule reaction rates, and further structural description, by means of a high resolution mass spectrometer, allowing for MS/MS structural analysis of the ionic species. A thorough evaluation of nowadays databases by means of uncertainty propagation will lead our choice of the most important reactions to be studied. This study shall also lead to educated choice for chemistry simplification, which is mandatory in order to include the chemistry in 3D or fluid models of the atmosphere. We plan as well to use extracts from tholins as molecular source for our analysis.

Structure of Room Temperature Ionic Liquids on Charged Graphene: An integrated experimental and computational study

NASA Astrophysics Data System (ADS)

Uysal, Ahmet; Zhou, Hua; Lee, Sang Soo; Fenter, Paul; Feng, Guang; Li, Song; Cummings, Peter; Fulvio, Pasquale; Dai, Sheng; McDonough, Jake; Gogotsi, Yury

2014-03-01

Electrical double layer capacitors (EDLCs) with room temperature ionic liquid (RTIL) electrolytes and carbon electrodes are promising candidates for energy storage devices with high power density and long cycle life. We studied the potential and time dependent changes in the electric double layer (EDL) structure of an imidazolium-based room temperature ionic liquid (RTIL) electrolyte at an epitaxial graphene (EG) surface. We used in situ x-ray reflectivity (XR) to determine the EDL structure at static potentials, during cyclic voltammetry (CV) and potential step measurements. The static potential structures were also investigated with fully atomistic molecular dynamics (MD) simulations. Combined XR and MD results show that the EDL structure has alternating anion/cation layers within the first nanometer of the interface. The dynamical response of the EDL to potential steps has a slow component (>10 s) and the RTIL structure shows hysteresis during CV scans. We propose a conceptual model that connects nanoscale interfacial structure to the macroscopic measurements. This material is based upon work supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy

Oxytocin-receptor-expressing neurons in the parabrachial nucleus regulate fluid intake.

PubMed

Ryan, Philip J; Ross, Silvano I; Campos, Carlos A; Derkach, Victor A; Palmiter, Richard D

2017-12-01

Brain regions that regulate fluid satiation are not well characterized, yet are essential for understanding fluid homeostasis. We found that oxytocin-receptor-expressing neurons in the parabrachial nucleus of mice (Oxtr PBN neurons) are key regulators of fluid satiation. Chemogenetic activation of Oxtr PBN neurons robustly suppressed noncaloric fluid intake, but did not decrease food intake after fasting or salt intake following salt depletion; inactivation increased saline intake after dehydration and hypertonic saline injection. Under physiological conditions, Oxtr PBN neurons were activated by fluid satiation and hypertonic saline injection. Oxtr PBN neurons were directly innervated by oxytocin neurons in the paraventricular hypothalamus (Oxt PVH  neurons), which mildly attenuated fluid intake. Activation of neurons in the nucleus of the solitary tract substantially suppressed fluid intake and activated Oxtr PBN neurons. Our results suggest that Oxtr PBN neurons act as a key node in the fluid satiation neurocircuitry, which acts to decrease water and/or saline intake to prevent or attenuate hypervolemia and hypernatremia.

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.

Preparation of nano fluids by mechanical method

NASA Astrophysics Data System (ADS)

Boopathy, J.; Pari, R.; Kavitha, M.; Angelo, P. C.

2012-07-01

Nanofluids are conventional heat transfer fluids that contain nano particles of metals, oxides, carbides, nitrides, or nanotubes. Nanofluids exhibit enhanced thermal conductivity and heat transfer coefficients compared to the base fluids. This paper presents the procedure for preparing nanofluids consisting of Copper and Aluminium nano powders in base fluids. Copper and Aluminium nano powders were produced by planetary ball wet milling at 300rpm for 50hrs. Toluene was added to ensure wet milling. These powders were characterized in XRD and SEM for their purity, particle size and shape. The XRD results confirmed the final particle sizes of Copper and Aluminium in the nano range. Then the 0.01 gm of nano metal powders was added in 150 ml of double distilled water and magnetic stirring was done at 1500 rpm for 15 minutes. Sodium lauryl sulphate (0.05%) was added in water as surfactant to ensure the stability of the dispersion. Ultrasonication in the 3000 watts bath was done for 10 minutes to enhance the uniform dispersion of metal powders in water. The pH, dynamic viscosity, ionic conductivity and the stability of the fluids were determined for further usage of synthesized nanofluids as coolant during grinding operation.

Transport of fluid and solutes in the body I. Formulation of a mathematical model.

PubMed

Gyenge, C C; Bowen, B D; Reed, R K; Bert, J L

1999-09-01

A compartmental model of short-term whole body fluid, protein, and ion distribution and transport is formulated. The model comprises four compartments: a vascular and an interstitial compartment, each with an embedded cellular compartment. The present paper discusses the assumptions on which the model is based and describes the equations that make up the model. Fluid and protein transport parameters from a previously validated model as well as ionic exchange parameters from the literature or from statistical estimation [see companion paper: C. C. Gyenge, B. D. Bowen, R. K. Reed, and J. L. Bert. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1228-H1240, 1999] are used in formulating the model. The dynamic model has the ability to simulate 1) transport across the capillary membrane of fluid, proteins, and small ions and their distribution between the vascular and interstitial compartments; 2) the changes in extracellular osmolarity; 3) the distribution and transport of water and ions associated with each of the cellular compartments; 4) the cellular transmembrane potential; and 5) the changes of volume in the four fluid compartments. The validation and testing of the proposed model against available experimental data are presented in the companion paper.

A complete two-phase model of a porous cathode of a PEM fuel cell

NASA Astrophysics Data System (ADS)

Hwang, J. J.

This paper has developed a complete two-phase model of a proton exchange membrane (PEM) fuel cell by considering fluid flow, heat transfer and current simultaneously. In fluid flow, two momentum equations governing separately the gaseous-mixture velocity (u g) and the liquid-water velocity (u w) illustrate the behaviors of the two-phase flow in a porous electrode. Correlations for the capillary pressure and the saturation level connect the above two-fluid transports. In heat transfer, a local thermal non-equilibrium (LTNE) model accounting for intrinsic heat transfer between the reactant fluids and the solid matrices depicts the interactions between the reactant-fluid temperature (T f) and the solid-matrix temperature (T s). The irreversibility heating due to electrochemical reactions, Joule heating arising from Ohmic resistance, and latent heat of water condensation/evaporation are considered in the present non-isothermal model. In current, Ohm's law is applied to yield the conservations in ionic current (i m) and electronic current (i s) in the catalyst layer. The Butler-Volmer correlation describes the relation of the potential difference (overpotential) and the transfer current between the electrolyte (such as Nafion™) and the catalyst (such as Pt/C).

Elemental maps in human allantochorial placental vessels cells: 1. High K + and acetylcholine effects

NASA Astrophysics Data System (ADS)

Michelet-Habchi, C.; Barberet, Ph.; Dutta, R. K.; Guiet-Bara, A.; Bara, M.; Moretto, Ph.

2003-09-01

Regulation of vascular tone in the fetal extracorporeal circulation most likely depends on circulating hormones, local paracrine mechanisms and changes in membrane potential of vascular smooth muscle cells (VSMCs) and of vascular endothelial cells (VECs). The membrane potential is a function of the physiological activities of ionic channels (particularly, K + and Ca 2+ channels in these cells). These channels regulate the ionic distribution into these cells. Micro-particle induced X-ray emission (PIXE) analysis was applied to determine the ionic composition of VSMC and of VEC in the placental human allantochorial vessels in a physiological survival medium (Hanks' solution) modified by the addition of acetylcholine (ACh: which opens the calcium-sensitive K + channels, K Ca) and of high concentration of K + (which blocks the voltage-sensitive K + channels, K df). In VSMC (media layer), the addition of ACh induced no modification of the Na, K, Cl, P, S, Mg and Ca concentrations and high K + medium increased significantly the Cl and K concentrations, the other ion concentrations remaining constant. In endothelium (VEC), ACh addition implicated a significant increase of Na and K concentration, and high K + medium, a significant increase in Cl and K concentration. These results indicated the importance of K df, K Ca and K ATP channels in the regulation of K + intracellular distribution in VSMC and VEC and the possible intervention of a Na-K-2Cl cotransport and corroborated the previous electrophysiological data.

Role of bundle helices in a regulatory crosstalk in the trimeric betaine transporter BetP.

PubMed

Gärtner, Rebecca M; Perez, Camilo; Koshy, Caroline; Ziegler, Christine

2011-12-02

The Na(+)-coupled betaine symporter BetP regulates transport activity in response to hyperosmotic stress only in its trimeric state, suggesting a regulatory crosstalk between individual protomers. BetP shares the overall fold of two inverted structurally related five-transmembrane (TM) helix repeats with the sequence-unrelated Na(+)-coupled symporters LeuT, vSGLT, and Mhp1, which are neither trimeric nor regulated in transport activity. Conformational changes characteristic for this transporter fold involve the two first helices of each repeat, which form a four-TM-helix bundle. Here, we identify two ionic networks in BetP located on both sides of the membrane that might be responsible for BetP's unique regulatory behavior by restricting the conformational flexibility of the four-TM-helix bundle. The cytoplasmic ionic interaction network links both first helices of each repeat in one protomer to the osmosensing C-terminal domain of the adjacent protomer. Moreover, the periplasmic ionic interaction network conformationally locks the four-TM-helix bundle between the same neighbor protomers. By a combination of site-directed mutagenesis, cross-linking, and betaine uptake measurements, we demonstrate how conformational changes in individual bundle helices are transduced to the entire bundle by specific inter-helical interactions. We suggest that one purpose of bundle networking is to assist crosstalk between protomers during transport regulation by specifically modulating the transition from outward-facing to inward-facing state. Copyright © 2011 Elsevier Ltd. All rights reserved.

Importance of a Lys113–Glu195 Intermonomer Ionic Bond in F-actin Stabilization and Regulation by Yeast Formins Bni1p and Bnr1p*

PubMed Central

Wen, Kuo-Kuang; McKane, Melissa; Rubenstein, Peter A.

2013-01-01

Proper actin cytoskeletal function requires actin's ability to generate a stable filament and requires that this reaction be regulated by actin-binding proteins via allosteric effects on the actin. A proposed ionic interaction in the actin filament interior between Lys113 of one monomer and Glu195 of a monomer in the apposing strand potentially fosters cross-strand stabilization and allosteric communication between the filament interior and exterior. We interrupted the potential interaction by creating either K113E or E195K actin. By combining the two, we also reversed the interaction with a K113E/E195K (E/K) mutant. In all cases, we isolated viable cells expressing only the mutant actin. Either single mutant cell displays significantly decreased growth in YPD medium. This deficit is rescued in the double mutant. All three mutants display abnormal phalloidin cytoskeletal staining. K113E actin exhibits a critical concentration of polymerization 4 times higher than WT actin, nucleates more poorly, and forms shorter filaments. Restoration of the ionic bond, E/K, eliminates most of these problems. E195K actin behaves much more like WT actin, indicating accommodation of the neighboring lysines. Both Bni1 and Bnr1 formin FH1-FH2 fragment accelerate polymerization of WT, E/K, and to a lesser extent E195K actin. Bni1p FH1-FH2 dramatically inhibits K113E actin polymerization, consistent with barbed end capping. However, Bnr1p FH1-FH2 restores K113E actin polymerization, forming single filaments. In summary, the proposed ionic interaction plays an important role in filament stabilization and in the propagation of allosteric changes affecting formin regulation in an isoform-specific fashion. PMID:23653364

pH-Dependent Solubility and Dissolution Behavior of Carvedilol--Case Example of a Weakly Basic BCS Class II Drug.

PubMed

Hamed, Rania; Awadallah, Areeg; Sunoqrot, Suhair; Tarawneh, Ola; Nazzal, Sami; AlBaraghthi, Tamadur; Al Sayyad, Jihan; Abbas, Aiman

2016-04-01

The objective of this study was to investigate the pH-dependent solubility and dissolution of weakly basic Biopharmaceutical Classification Systems (BCS) class II drugs, characterized by low solubility and high permeability, using carvedilol, a weak base with a pK a value of 7.8, as a model drug. A series of solubility and in vitro dissolution studies was carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH range of the GI from 1.2 to 7.8. The effect of ionic strength, buffer capacity, and buffer species of the dissolution media on the solubility and dissolution behavior of carvedilol was also investigated. The study revealed that carvedilol exhibited a typical weak base pH-dependent solubility profile with a high solubility at low pH (545.1-2591.4 μg/mL within the pH range 1.2-5.0) and low solubility at high pH (5.8-51.9 μg/mL within the pH range 6.5-7.8). The dissolution behavior of carvedilol was consistent with the solubility results, where carvedilol release was complete (95.8-98.2% released within 60 min) in media simulating the gastric fluid (pH 1.2-5.0) and relatively low (15.9-86.2% released within 240 min) in media simulating the intestinal fluid (pH 6.5-7.8). It was found that the buffer species of the dissolution media may influence the solubility and consequently the percentage of carvedilol released by forming carvedilol salts of varying solubilities. Carvedilol solubility and dissolution decreased with increasing ionic strength, while lowering the buffer capacity resulted in a decrease in carvedilol solubility and dissolution rate.

Fluidic nanotubes and devices

DOEpatents

Yang, Peidong [Berkeley, CA; He, Rongrui [El Cerrito, CA; Goldberger, Joshua [Berkeley, CA; Fan, Rong [El Cerrito, CA; Wu, Yiying [Albany, CA; Li, Deyu [Albany, CA; Majumdar, Arun [Orinda, CA

2008-04-08

Fluidic nanotube devices are described in which a hydrophilic, non-carbon nanotube, has its ends fluidly coupled to reservoirs. Source and drain contacts are connected to opposing ends of the nanotube, or within each reservoir near the opening of the nanotube. The passage of molecular species can be sensed by measuring current flow (source-drain, ionic, or combination). The tube interior can be functionalized by joining binding molecules so that different molecular species can be sensed by detecting current changes. The nanotube may be a semiconductor, wherein a tubular transistor is formed. A gate electrode can be attached between source and drain to control current flow and ionic flow. By way of example an electrophoretic array embodiment is described, integrating MEMs switches. A variety of applications are described, such as: nanopores, nanocapillary devices, nanoelectrophoretic, DNA sequence detectors, immunosensors, thermoelectric devices, photonic devices, nanoscale fluidic bioseparators, imaging devices, and so forth.

Fluidic nanotubes and devices

DOEpatents

Yang, Peidong; He, Rongrui; Goldberger, Joshua; Fan, Rong; Wu, Yiying; Li, Deyu; Majumdar, Arun

2010-01-10

Fluidic nanotube devices are described in which a hydrophilic, non-carbon nanotube, has its ends fluidly coupled to reservoirs. Source and drain contacts are connected to opposing ends of the nanotube, or within each reservoir near the opening of the nanotube. The passage of molecular species can be sensed by measuring current flow (source-drain, ionic, or combination). The tube interior can be functionalized by joining binding molecules so that different molecular species can be sensed by detecting current changes. The nanotube may be a semiconductor, wherein a tubular transistor is formed. A gate electrode can be attached between source and drain to control current flow and ionic flow. By way of example an electrophoretic array embodiment is described, integrating MEMs switches. A variety of applications are described, such as: nanopores, nanocapillary devices, nanoelectrophoretic, DNA sequence detectors, immunosensors, thermoelectric devices, photonic devices, nanoscale fluidic bioseparators, imaging devices, and so forth.

Bulk and Thin film Properties of Nanoparticle-based Ionic Materials

NASA Astrophysics Data System (ADS)

Fang, Jason

2008-03-01

Nanoparticle-based ionic materials (NIMS) offer exciting opportunities for research at the forefront of science and engineering. NIMS are hybrid particles comprised of a charged oligomeric corona attached to hard, inorganic nanoparticle cores. Because of their hybrid nature, physical properties --rheological, optical, electrical, thermal - of NIMS can be tailored over an unusually wide range by varying geometric and chemical characteristics of the core and canopy and thermodynamic variables such as temperature and volume fraction. On one end of the spectrum are materials with a high core content, which display properties similar to crystalline solids, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form particle-based fluids characterized by transport properties remarkably similar to simple liquids. In this poster I will present our efforts to synthesize NIMS and discuss their bulk and surface properties. In particular I will discuss our work on preparing smart surfaces using NIMS.

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.

Charge ordering in two-dimensional ionic liquids

NASA Astrophysics Data System (ADS)

Perera, Aurélien; Urbic, Tomaz

2018-04-01

The structural properties of model two-dimensional (2D) ionic liquids are examined, with a particular focus on the charge ordering process, with the use of computer simulation and integral equation theories. The influence of the logarithmic form of the Coulomb interaction, versus that of a 3D screened interaction form, is analysed. Charge order is found to hold and to be analogous for both interaction models, despite their very different form. The influence of charge ordering in the low density regime is discussed in relation to well known properties of 2D Coulomb fluids, such as the Kosterlitz-Thouless transition and criticality. The present study suggests the existence of a stable thermodynamic labile cluster phase, implying the existence of a liquid-liquid "transition" above the liquid-gas binodal. The liquid-gas and Kosterlitz-Thouless transitions would then take place inside the predicted cluster phase.

Underwater energy harvesting from a turbine hosting ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Cellini, Filippo; Pounds, Jason; Peterson, Sean D.; Porfiri, Maurizio

2014-08-01

In this study, we explore the possibility of energy harvesting from fluid flow through a turbine hosting ionic polymer metal composites (IPMCs). Specifically, IPMC harvesters are embedded in the blades of a small-scale vertical axis water turbine to convert flow kinetics into electrical power via low-frequency flow-induced IPMC deformations. An in-house fabricated Savonius-Darrieus hybrid active turbine with three IPMCs is tested in a laboratory water tunnel to estimate the energy harvesting capabilities of the device as a function of the shunting electrical load. The turbine is shown to harvest a few nanowatt from a mean flow of 0.43\\;m\\;{{s}^{-1}} for shunting resistances in the range 100-1000\\;\\Omega . To establish a first understanding of the energy harvesting device, we propose a quasi-static hydroelastic model for the bending of the IPMCs and we utilize a black-box model to study their electromechanical response.

Deposition kinetics of colloidal particles at high ionic strengths

NASA Astrophysics Data System (ADS)

Cejas, Cesare; Monti, Fabrice; Truchet, Marine; Burnouf, Jean-Pierre; Tabeling, Patrick

Using microfluidic experiments, we describe the deposition of a fluid suspension of weakly brownian particles transported in a straight channel at small Reynolds numbers under conditions of high ionic strengths. Our studies fall in a regime where electrostatic interactions are neglected and particle-wall van der Waals interactions govern the deposition mechanism on channel walls. We calculate the deposition kinetics analytically for a wide range of physical parameters. We find that the theory agrees with numerical Langevin simulations, which both confirm the experimental results. From this analysis, we demonstrate a universal dimensionless deposition function described by contributions from advection-diffusion transport and adhesion interactions (Hamaker constant). Results show that we accurately confirm the theoretical expression for the deposition kinetics. From a surface science perspective, working in the van der Waals regime enables to measure the Hamaker constant, a task that would take much longer to perform with the standard AFM. Funding from Sanofi Recherche and ESPCI.

Flow-induced voltage generation in non-ionic liquids over monolayer graphene

NASA Astrophysics Data System (ADS)

Ho Lee, Seung; Jung, Yousung; Kim, Soohyun; Han, Chang-Soo

2013-02-01

To clarify the origin of the flow-induced voltage generation in graphene, we prepared a new experimental device whose electrodes were aligned perpendicular to the flow with a non-ionic liquid. We found that significant voltage in our device was generated with increasing flow velocity, thereby confirming that voltage was due to an intrinsic interaction between graphene and the flowing liquid. To understand the mechanism of the observed flow-induced voltage generation, we systematically varied several important experimental parameters: flow velocity, electrode alignment, liquid polarity, and liquid viscosity. Based on these measurements, we suggest that polarity of the fluid is a significant factor in determining the extent of the voltage generated, and the major mechanism can be attributed to instantaneous potential differences induced in the graphene due to an interaction with polar liquids and to the momentum transferred from the flowing liquid to the graphene.

Origin of the Okrouhlá Radouň episyenite-hosted uranium deposit, Bohemian Massif, Czech Republic: fluid inclusion and stable isotope constraints

NASA Astrophysics Data System (ADS)

Dolníček, Zdeněk; René, Miloš; Hermannová, Sylvie; Prochaska, Walter

2014-04-01

The Okrouhlá Radouň shear zone hosted uranium deposit is developed along the contact of Variscan granites and high-grade metasedimentary rocks of the Moldanubian Zone of the Bohemian Massif. The pre-ore pervasive alteration of wall rocks is characterized by chloritization of mafic minerals, followed by albitization of feldspars and dissolution of quartz giving rise to episyenites. The subsequent fluid circulation led to precipitation of disseminated uraninite and coffinite, and later on, post-ore quartz and carbonate mineralization containing base metal sulfides. The fluid inclusion and stable isotope data suggest low homogenization temperatures (˜50-140 °C during pre-ore albitization and post-ore carbonatization, up to 230 °C during pre-ore chloritization), variable fluid salinities (0-25 wt.% NaCl eq.), low fluid δ18O values (-10 to +2 ‰ V-SMOW), low fluid δ13C values (-9 to -15 ‰ V-PDB), and highly variable ionic composition of the aqueous fluids (especially Na/Ca, Br/Cl, I/Cl, SO4/Cl, NO3/Cl ratios). The available data suggest participation of three fluid endmembers of primarily surficial origin during alteration and mineralization at the deposit: (1) local meteoric water, (2) Na-Ca-Cl basinal brines or shield brines, (3) SO4-NO3-Cl-(H)CO3 playa-like fluids. Pre-ore albitization was caused by circulation of alkaline, oxidized, and Na-rich playa fluids, whereas basinal/shield brines and meteoric water were more important during the post-ore stage of alteration.

Implications for metal and volatile cycles from the pH of subduction zone fluids

NASA Astrophysics Data System (ADS)

Galvez, Matthieu E.; Connolly, James A. D.; Manning, Craig E.

2016-11-01

The chemistry of aqueous fluids controls the transport and exchange—the cycles—of metals and volatile elements on Earth. Subduction zones, where oceanic plates sink into the Earth’s interior, are the most important geodynamic setting for this fluid-mediated chemical exchange. Characterizing the ionic speciation and pH of fluids equilibrated with rocks at subduction zone conditions has long been a major challenge in Earth science. Here we report thermodynamic predictions of fluid-rock equilibria that tie together models of the thermal structure, mineralogy and fluid speciation of subduction zones. We find that the pH of fluids in subducted crustal lithologies is confined to a mildly alkaline range, modulated by rock volatile and chlorine contents. Cold subduction typical of the Phanerozoic eon favours the preservation of oxidized carbon in subducting slabs. In contrast, the pH of mantle wedge fluids is very sensitive to minor variations in rock composition. These variations may be caused by intramantle differentiation, or by infiltration of fluids enriched in alkali components extracted from the subducted crust. The sensitivity of pH to soluble elements in low abundance in the host rocks, such as carbon, alkali metals and halogens, illustrates a feedback between the chemistry of the Earth’s atmosphere-ocean system and the speciation of subduction zone fluids via the composition of the seawater-altered oceanic lithosphere. Our findings provide a perspective on the controlling reactions that have coupled metal and volatile cycles in subduction zones for more than 3 billion years7.

A three-scale model for ionic solute transport in swelling clays incorporating ion-ion correlation effects

NASA Astrophysics Data System (ADS)

Le, Tien Dung; Moyne, Christian; Murad, Marcio A.

2015-01-01

A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson-Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi's effective principle. At the macroscale, the electro-chemical-mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of attractive forces between particles for bivalent ions for particular ranges of bulk concentrations. The three-scale model is applied to numerically simulate ion diffusion in a compacted clay liner underneath a sanitary landfill. Owing to the distinct constitutive behavior of the swelling pressure and partition coefficient for each ionic species, different compaction regimes and diffusion/adsorption patterns, with totally different characteristic time scales, are observed for sodium and calcium migration in the clay liner.

The fish gill: site of action and model for toxic effects of environmental pollutants.

PubMed Central

Evans, D H

1987-01-01

The gill epithelium is the site of gas exchange, ionic regulation, acid-base balance, and nitrogenous waste excretion by fishes. The last three processes are controlled by passive and active transport of various solutes across the epithelium. Various environmental pollutants (e.g., heavy metals, acid rain, and organic xenobiotics) have been found to affect the morphology of the gill epithelium. Associated with these morphological pathologies, one finds alterations in blood ionic levels, as well as gill Na,K-activated ATPase activity and ionic fluxes. Such physiological disturbances may underly the toxicities of these pollutants. In addition, the epithelial transport steps which are affected in the fish gill model resemble those described in the human gut and kidney, sites of action of a variety of environmental toxins. Images FIGURE 1. a FIGURE 1. b FIGURE 3. PMID:3297663

Bioassay of body fluids, experiment M073. [biochemical changes caused by space flight conditions

NASA Technical Reports Server (NTRS)

Leach, C. S.; Rambaut, P. C.

1973-01-01

Body fluids were assayed in this experiment to demonstrate changes which might have occurred during the 56-day chamber study in fluid and electrolyte balance, in regulation of calcium metabolism, in overall physiological and emotional adaptation to the environment, and in regulation of metabolic processes.

Aqueous alkali halide solutions: can osmotic coefficients be explained on the basis of the ionic sizes alone?

PubMed

Kalyuzhnyi, Yu V; Vlachy, Vojko; Dill, Ken A

2010-06-21

We use the AMSA, associative mean spherical theory of associative fluids, to study ion-ion interactions in explicit water. We model water molecules as hard spheres with four off-center square-well sites and ions as charged hard spheres with sticky sites that bind to water molecules or other ions. We consider alkali halide salts. The choice of model parameters is based on two premises: (i) The strength of the interaction between a monovalent ion and a water molecule is inversely proportional to the ionic (crystal) diameter sigma(i). Smaller ions bind to water more strongly than larger ions do, taking into account the asymmetry of the cation-water and anion-water interactions. (ii) The number of contacts an ion can make is proportional to sigma2(i). In short, small ions bind waters strongly, but only a few of them. Large ions bind waters weakly, but many of them. When both a monovalent cation and anion are large, it yields a small osmotic coefficient of the salt, since the water molecules avoid the space in between large ions. On the other hand, salts formed from one small and one large ion remain hydrated and their osmotic coefficient is high. The osmotic coefficients, calculated using this model in combination with the integral equation theory developed for associative fluids, follow the experimental trends, including the unusual behavior of caesium salts.

Quantification of surface charge density and its effect on boundary slip.

PubMed

Jing, Dalei; Bhushan, Bharat

2013-06-11

Reduction of fluid drag is important in the micro-/nanofluidic systems. Surface charge and boundary slip can affect the fluid drag, and surface charge is also believed to affect boundary slip. The quantification of surface charge and boundary slip at a solid-liquid interface has been widely studied, but there is a lack of understanding of the effect of surface charge on boundary slip. In this paper, the surface charge density of borosilicate glass and octadecyltrichlorosilane (OTS) surfaces immersed in saline solutions with two ionic concentrations and deionized (DI) water with different pH values and electric field values is quantified by fitting experimental atomic force microscopy (AFM) electrostatic force data using a theoretical model relating the surface charge density and electrostatic force. Results show that pH and electric field can affect the surface charge density of glass and OTS surfaces immersed in saline solutions and DI water. The mechanisms of the effect of pH and electric field on the surface charge density are discussed. The slip length of the OTS surface immersed in saline solutions with two ionic concentrations and DI water with different pH values and electric field values is measured, and their effects on the slip length are analyzed from the point of surface charge. Results show that a larger absolute value of surface charge density leads to a smaller slip length for the OTS surface.

Effect of various pH values, ionic strength, and temperature on papain hydrolysis of salivary film.

PubMed

Yao, Jiang-Wu; Xiao, Yin; Lin, Feng

2012-04-01

Stimulated human whole saliva (WS) was used to study the dynamics of papain hydrolysis at defined pH, ionic strength, and temperature with the view of reducing an acquired pellicle. A quartz crystal microbalance with dissipation (QCM-D) was used to monitor the changes in frequency caused by enzyme hydrolysis of WS films, and the hydrolytic parameters were calculated using an empirical model. The morphological and conformational changes of the salivary films before and after enzymatic hydrolysis were characterized by atomic force microscopy (AFM) imaging and grazing-angle Fourier transform infrared (GA-FTIR ) spectra, respectively. The characteristics of papain hydrolysis of WS films were pH-, ionic strength-, and temperature-dependent. The WS films were partially removed by the action of papain, resulting in thinner and smoother surfaces. The infrared data suggested that hydrolysis-induced deformation did not occur on the remnants of salivary films. The processes of papain hydrolysis of WS films can be controlled by properly regulating pH, ionic strength, and temperature. © 2012 Eur J Oral Sci.

Electrodialytic in-line preconcentration for ionic solute analysis.

PubMed

Ohira, Shin-Ichi; Yamasaki, Takayuki; Koda, Takumi; Kodama, Yuko; Toda, Kei

2018-04-01

Preconcentration is an effective way to improve analytical sensitivity. Many types of methods are used for enrichment of ionic solute analytes. However, current methods are batchwise and include procedures such as trapping and elution. In this manuscript, we propose in-line electrodialytic enrichment of ionic solutes. The method can enrich ionic solutes within seconds by quantitative transfer of analytes from the sample solution to the acceptor solution under an electric field. Because of quantitative ion transfer, the enrichment factor (the ratio of the concentration in the sample and to that in the obtained acceptor solution) only depends on the flow rate ratio of the sample solution to the acceptor solution. The ratios of the concentrations and flow rates are equal for ratios up to 70, 20, and 70 for the tested ionic solutes of inorganic cations, inorganic anions, and heavy metal ions, respectively. The sensitivity of ionic solute determinations is also improved based on the enrichment factor. The method can also simultaneously achieve matrix isolation and enrichment. The method was successively applied to determine the concentrations of trace amounts of chloroacetic acids in tap water. The regulated concentration levels cannot be determined by conventional high-performance liquid chromatography with ultraviolet detection (HPLC-UV) without enrichment. However, enrichment with the present method is effective for determination of tap water quality by improving the limits of detection of HPLC-UV. The standard addition test with real tap water samples shows good recoveries (94.9-109.6%). Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Ionic solubility and solutal advection governed augmented evaporation kinetics of salt solution pendant droplets

NASA Astrophysics Data System (ADS)

Jaiswal, Vivek; Harikrishnan, A. R.; Khurana, Gargi; Dhar, Purbarun

2018-01-01

The presence of dispersed inclusions is known to modify the interfacial characteristics in liquids by adsorption-desorption of the ions at interfaces. The present article reports the influencing role of dissolved ions in a polar fluid on its evaporation dynamics. The evaporation dynamics of pendant droplets of aqueous solutions of variant simple salts and concentrations have been experimentally studied. The presence of salts is observed to enhance the evaporation rate (obeying the classical D2 law), and the enhancement has been found to hold a direct proportionality to the concentration of the dissolved salt. Furthermore, it is observed that the degree of enhancement in the evaporation rate is also directly proportional to the solubility of the salt in question. The phenomenon is explained based on the chemical kinetics and thermodynamics of hydration of the ionic species in the polar fluid. The classical evaporation rate constant formulation is found to be inadequate in modeling the enhanced species transport. Additional probing via particle image velocimetry reveals augmented internal circulation within the evaporating salt based drops compared to pure water. Mapping the dynamic surface tension reveals that a salt concentration gradient is generated between the bulk and periphery of the droplet and it could be responsible for the internal advection cells visualized. A thermo-solutal Marangoni and Rayleigh convection based mathematical formulation has been put forward, and it is shown that the enhanced solute-thermal convection could play a major role in enhanced evaporation. The internal circulation mapped from experiments is found to be in good quantitative agreement with the model predictions. Scaling analysis further reveals that the stability of the solutal Marangoni convection surpasses the thermal counterpart with higher salt concentration and solubility. The present article sheds insight into the possible domineering role of conjugate thermohydraulic and mass transport phenomena on the evaporation kinetics aqueous droplets with ionic inclusions.

Hormonal Regulation of Fluid and Electrolytes: Effects of Heat Exposure and Exercise in the Heat,

DTIC Science & Technology

1988-02-01

F.N. Craig. Effect of potassium depletion on response to acute heat exposure in unacclimatized man. Am. J. % Physi. 211:117-124, 1966.% 22 . Cochrane...AD-RI92 655 HORMONAL REGULATION OF FLUID AND ELECTROLYTES: EFFECTS 1/ OF HEAT EXPOSURE A.. CU) ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA...61102A______________________ MI6102BSI CA DA114 11. TITLE (Include Security Classification) Hormnal Regulation of Fluid and Electrolytes: Effects of

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.

Regulation of intramembranous absorption and amniotic fluid volume by constituents in fetal sheep urine

PubMed Central

Jonker, Sonnet S.; Louey, Samantha; Cheung, Cecilia Y.; Brace, Robert A.

2013-01-01

Our objective was to test the hypothesis that fetal urine contains a substance(s) that regulates amniotic fluid volume by altering the rate of intramembranous absorption of amniotic fluid. In late gestation ovine fetuses, amniotic fluid volumes, urine, and lung liquid production rates, swallowed volumes and intramembranous volume and solute absorption rates were measured over 2-day periods under control conditions and when urine was removed and continuously replaced at an equal rate with exogenous fluid. Intramembranous volume absorption rate decreased by 40% when urine was replaced with lactated Ringer solution or lactated Ringer solution diluted 50% with water. Amniotic fluid volume doubled under both conditions. Analysis of the intramembranous sodium and chloride fluxes suggests that the active but not passive component of intramembranous volume absorption was altered by urine replacement, whereas both active and passive components of solute fluxes were altered. We conclude that fetal urine contains an unidentified substance(s) that stimulates active intramembranous transport of amniotic fluid across the amnion into the underlying fetal vasculature and thereby functions as a regulator of amniotic fluid volume. PMID:23824958

Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+.

PubMed

Michailova, Anushka; Saucerman, Jeffrey; Belik, Mary Ellen; McCulloch, Andrew D

2005-03-01

Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.

Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+

NASA Technical Reports Server (NTRS)

Michailova, Anushka; Saucerman, Jeffrey; Belik, Mary Ellen; McCulloch, Andrew D.

2005-01-01

Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.

Enthalpy-based equation of state for highly porous materials employing modified soft sphere fluid model

NASA Astrophysics Data System (ADS)

Nayak, Bishnupriya; Menon, S. V. G.

2018-01-01

Enthalpy-based equation of state based on a modified soft sphere model for the fluid phase, which includes vaporization and ionization effects, is formulated for highly porous materials. Earlier developments and applications of enthalpy-based approach had not accounted for the fact that shocked states of materials with high porosity (e.g., porosity more than two for Cu) are in the expanded fluid region. We supplement the well known soft sphere model with a generalized Lennard-Jones formula for the zero temperature isotherm, with parameters determined from cohesive energy, specific volume and bulk modulus of the solid at normal condition. Specific heats at constant pressure, ionic and electronic enthalpy parameters and thermal excitation effects are calculated using the modified approach and used in the enthalpy-based equation of state. We also incorporate energy loss from the shock due to expansion of shocked material in calculating porous Hugoniot. Results obtained for Cu, even up to initial porosities ten, show good agreement with experimental data.

Charge fluctuations in nanoscale capacitors.

PubMed

Limmer, David T; Merlet, Céline; Salanne, Mathieu; Chandler, David; Madden, Paul A; van Roij, René; Rotenberg, Benjamin

2013-09-06

The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers, in particular, an efficient, accurate, and physically insightful route to the differential capacitance that is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

Charge Fluctuations in Nanoscale Capacitors

NASA Astrophysics Data System (ADS)

Limmer, David T.; Merlet, Céline; Salanne, Mathieu; Chandler, David; Madden, Paul A.; van Roij, René; Rotenberg, Benjamin

2013-09-01

The fluctuations of the charge on an electrode contain information on the microscopic correlations within the adjacent fluid and their effect on the electronic properties of the interface. We investigate these fluctuations using molecular dynamics simulations in a constant-potential ensemble with histogram reweighting techniques. This approach offers, in particular, an efficient, accurate, and physically insightful route to the differential capacitance that is broadly applicable. We demonstrate these methods with three different capacitors: pure water between platinum electrodes and a pure as well as a solvent-based organic electrolyte each between graphite electrodes. The total charge distributions with the pure solvent and solvent-based electrolytes are remarkably Gaussian, while in the pure ionic liquid the total charge distribution displays distinct non-Gaussian features, suggesting significant potential-driven changes in the organization of the interfacial fluid.

Method and apparatus for ion sequestration and a nanostructured metal phosphate

DOEpatents

Mattigod, Shas V [Richland, WA; Fryxell, Glen E [Kennewic, WA; Li, Xiaohong [Richland, WA; Parker, Kent E [Kennewick, WA; Wellman, Dawn M [West Richland, WA

2010-04-06

A nanostructured substance, a process for sequestration of ionic waste, and an ion-sequestration apparatus are disclosed in the specification. The nanostructured substance can comprise a Lewis acid transition metal bound to a phosphate, wherein the phosphate comprises a primary structural component of the substance and the Lewis acid transition metal is a reducing agent. The nanostructured substance has a Brunner-Emmet-Teller (BET) surface area greater than or equal to approximately 100 m.sup.2/g, and a distribution coefficient for an analyte, K.sub.d, greater than or equal to approximately 5000 ml/g. The process can comprise contacting a fluid and a nanostructured metal phosphate. The apparatus can comprise a vessel and a nanostructured metal phosphate. The vessel defines a volume wherein a fluid contacts the nanostructured metal phosphate.

From Solvent-Free to Dilute Electrolytes: Essential Components for a Continuum Theory.

PubMed

Gavish, Nir; Elad, Doron; Yochelis, Arik

2018-01-04

The increasing number of experimental observations on highly concentrated electrolytes and ionic liquids show qualitative features that are distinct from dilute or moderately concentrated electrolytes, such as self-assembly, multiple-time relaxation, and underscreening, which all impact the emergence of fluid/solid interfaces, and the transport in these systems. Because these phenomena are not captured by existing mean-field models of electrolytes, there is a paramount need for a continuum framework for highly concentrated electrolytes and ionic liquid mixtures. In this work, we present a self-consistent spatiotemporal framework for a ternary composition that comprises ions and solvent employing a free energy that consists of short- and long-range interactions, along with an energy dissipation mechanism obtained by Onsager's relations. We show that the model can describe multiple bulk and interfacial morphologies at steady-state. Thus, the dynamic processes in the emergence of distinct morphologies become equally as important as the interactions that are specified by the free energy. The model equations not only provide insights into transport mechanisms beyond the Stokes-Einstein-Smoluchowski relations but also enable qualitative recovery of three distinct regions in the full range of the nonmonotonic electrical screening length that has been recently observed in experiments in which organic solvent is used to dilute ionic liquids.

Removal forces and adhesion properties of Saccharomyces cerevisiae on glass substrates probed by optical tweezer

NASA Astrophysics Data System (ADS)

Castelain, Mickaël; Pignon, Frédéric; Piau, Jean-Michel; Magnin, Albert; Mercier-Bonin, Muriel; Schmitz, Philippe

2007-10-01

In agroindustry, the hygiene of solid surfaces is of primary importance in order to ensure that products are safe for consumers. To improve safety, one of the major ways consists in identifying and understanding the mechanisms of microbial cell adhesion to nonporous solid surfaces or filtration membranes. In this paper we investigate the adhesion of the yeast cell Saccharomyces cerevisiae (about 5μm in diameter) to a model solid surface, using well-defined hydrophilic glass substrates. An optical tweezer device developed by Piau [J. Non-Newtonian Fluid Mech. 144, 1 (2007)] was applied to yeast cells in contact with well-characterized glass surfaces. Two planes of observation were used to obtain quantitative measurements of removal forces and to characterize the corresponding mechanisms at a micrometer length scale. The results highlight various adhesion mechanisms, depending on the ionic strength, contact time, and type of yeast. The study has allowed to show a considerable increase of adhering cells with the ionic strength and has provided a quantitative measurement of the detachment forces of cultured yeast cells. Force levels are found to grow with ionic strength and differences in mobility are highlighted. The results clearly underline that a microrheological approach is essential for analyzing the adhesion mechanisms of biological systems at the relevant local scales.

Statistical Determinants of Selective Ionic Complexation: Ions in Solvent, Transport Proteins, and Other “Hosts”

PubMed Central

Bostick, David L.; Brooks, Charles L.

2009-01-01

To provide utility in understanding the molecular evolution of ion-selective biomembrane channels/transporters, globular proteins, and ionophoric compounds, as well as in guiding their modification and design, we present a statistical mechanical basis for deconstructing the impact of the coordination structure and chemistry of selective multidentate ionic complexes. The deconstruction augments familiar ideas in liquid structure theory to realize the ionic complex as an open ion-ligated system acting under the influence of an “external field” provided by the host (or surrounding medium). Using considerations derived from this basis, we show that selective complexation arises from exploitation of a particular ion's coordination preferences. These preferences derive from a balance of interactions much like that which dictates the Hofmeister effect. By analyzing the coordination-state space of small family IA and VIIA ions in simulated fluid media, we derive domains of coordinated states that confer selectivity for a given ion upon isolating and constraining particular attributes (order parameters) of a complex comprised of a given type of ligand. We demonstrate that such domains may be used to rationalize the ion-coordinated environments provided by selective ionophores and biological ion channels/transporters of known structure, and that they can serve as a means toward deriving rational design principles for ion-selective hosts. PMID:19486671

Nanoconfined ionic liquids: Disentangling electrostatic and viscous forces

NASA Astrophysics Data System (ADS)

Lhermerout, Romain; Perkin, Susan

2018-01-01

Recent reports of surface forces across nanoconfined ionic liquids have revealed the existence of an anomalously long-ranged interaction apparently of electrostatic origin. Ionic liquids are viscous, and therefore it is important to inspect rigorously whether the observed repulsive forces are indeed equilibrium forces or, rather, arise from the viscous force during drainage of the fluid between two confining surfaces. In this paper we present our direct measurements of surface forces between mica sheets approaching in the ionic liquid [C2C1Im ] [NTf2] , exploring three orders of magnitude in approach velocity. Trajectories are systematically fitted by solving the equation of motion, allowing us to disentangle the viscous and equilibrium contributions. First, we find that the drainage obeys classical hydrodynamics with a negative slip boundary condition in the range of the structural force, implying that a nanometer -thick portion of the liquid in the vicinity of the solid surface is composed of ordered molecules that do not contribute to the flow. Second, we show that a long-range static force must indeed be invoked, in addition to the viscous force, in order to describe the data quantitatively. This equilibrium interaction decays exponentially and with decay length in agreement with the screening length reported for the same system in previous studies. In those studies the decay was simply checked to be independent of velocity and measured at a low approach rate, rather than explicitly taking account of viscous effects: we explain why this gives indistinguishable outcomes for the screening length by noting that the viscous force is linear to very good approximation over a wide range of distances.

Energy harvesting from the tail beating of a carangiform swimmer using ionic polymer-metal composites.

PubMed

Cha, Youngsu; Verotti, Matteo; Walcott, Horace; Peterson, Sean D; Porfiri, Maurizio

2013-09-01

In this paper, we study energy harvesting from the beating of a biomimetic fish tail using ionic polymer-metal composites. The design of the biomimetic tail is based on carangiform swimmers and is specifically inspired by the morphology of the heterocercal tail of thresher sharks. The tail is constituted of a soft silicone matrix molded in the form of the heterocercal tail and reinforced by a steel beam of rectangular cross section. We propose a modeling framework for the underwater vibration of the biomimetic tail, wherein the tail is assimilated to a cantilever beam with rectangular cross section and heterogeneous physical properties. We focus on base excitation in the form of a superimposed rotation about a fixed axis and we consider the regime of moderately large-amplitude vibrations. In this context, the effect of the encompassing fluid is described through a hydrodynamic function, which accounts for inertial, viscous and convective phenomena. The model is validated through experiments in which the base excitation is systematically varied and the motion of selected points on the biomimetic tail tracked in time. The feasibility of harvesting energy from an ionic polymer-metal composite attached to the vibrating structure is experimentally and theoretically assessed. The response of the transducer is described using a black-box model, where the voltage output is controlled by the rate of change of the mean curvature. Experiments are performed to elucidate the impact of the shunting resistance, the frequency of the base excitation and the placement of the ionic polymer-metal composite on energy harvesting from the considered biomimetic tail.

Effect of electrolytes on proteins physisorption on ordered mesoporous silica materials.

PubMed

Salis, Andrea; Medda, Luca; Cugia, Francesca; Monduzzi, Maura

2016-01-01

This short review highlights the effect of electrolytes on the performance of proteins-mesoporous silica conjugates which can open interesting perspectives in biotechnological fields, particularly nanomedicine and biocatalysis. Indeed therapeutic proteins and peptides represent a challenging innovation for several kinds of diseases, but since their self-life in biological fluids is very short, they need a stealth protective carrier. Similarly, enzymes need a solid support to improve thermal stability and to allow for recycling. Ordered mesoporous silica materials represent a valid choice as widely demonstrated. Both proteins and silica mesoporous materials possess charged surfaces, and here, the crucial role of pH, buffer, ionic strength and electrolyte type is posed in relation with loading/release of proteins onto/from the silica support through the analysis of adsorption and release processes. A delicate interplay of electrostatic and van der Waals interactions arises from considering electrolytes' effects on the two different charged surfaces. Clear outcomes concern the effect of pH and ionic strength. Protein loading onto the silica matrix is favored by an adsorbing solution having a pH close to the protein pI, and by a high ionic strength that reduces the Debye length. Release is instead favored by an adsorbing solution characterized by an intermediate ionic strength, close to the physiological values. Significant specific ions effects are shown to affect both proteins and silica matrices, as well as protein adsorption onto silica matrices. Further work is needed to quantify specific ion effects on the preservation of the biological activity, and on the release performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Investigation of the interaction of ferromagnetic fluids with proteins by dynamic light scattering

NASA Astrophysics Data System (ADS)

Velichko, Elena; Nepomnyashchaya, Elina; Dudina, Alina; Pleshakov, Ivan; Aksenov, Evgenii

2018-04-01

In this article the interaction between ionically stabilized magnetic nanoparticles and blood serum albumin proteins in liquid medium are discussed. Some distributions of nanoparticles' agglomerate sizes in solutions of albumin molecules, magnetic nanoparticles and their mixtures both under the influence of magnetic field and free from it are presented. It is shown that magnetic nanoparticles interact with albumin molecules, forming agglomerates. It is also shown that at the influence of magnetic field sizes of agglomerates increase proportionally to the magnetic field density.

Integral equations in the study of polar and ionic interaction site fluids

PubMed Central

Howard, Jesse J.

2011-01-01

In this review article we consider some of the current integral equation approaches and application to model polar liquid mixtures. We consider the use of multidimensional integral equations and in particular progress on the theory and applications of three dimensional integral equations. The IEs we consider may be derived from equilibrium statistical mechanical expressions incorporating a classical Hamiltonian description of the system. We give example including salt solutions, inhomogeneous solutions and systems including proteins and nucleic acids. PMID:22383857

Controlled differential pressure system for an enhanced fluid blending apparatus

DOEpatents

Hallman, Jr., Russell Louis

2009-02-24

A system and method for producing a controlled blend of two or more fluids. Thermally-induced permeation through a permeable tube is used to mix a first fluid from outside the tube with a second fluid flowing through the tube. Mixture ratios may be controlled by adjusting the temperature of the first fluid or by adjusting the pressure drop through the permeable tube. The combination of a back pressure control valve and a differential regulator is used to control the output pressure of the blended fluid. The combination of the back pressure control valve and differential regulator provides superior flow control of the second dry gas. A valve manifold system may be used to mix multiple fluids, and to adjust the volume of blended fluid produced, and to further modify the mixture ratio.

Fuel cell membrane hydration and fluid metering

DOEpatents

Jones, Daniel O.; Walsh, Michael M.

2003-01-01

A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices.

PubMed

Asare-Addo, Kofi; Conway, Barbara R; Larhrib, Hassan; Levina, Marina; Rajabi-Siahboomi, Ali R; Tetteh, John; Boateng, Joshua; Nokhodchi, Ali

2013-11-01

The evaluation of the effects of different media ionic strengths and pH on the release of hydrochlorothiazide, a poorly soluble drug, and diltiazem hydrochloride, a cationic and soluble drug, from a gel forming hydrophilic polymeric matrix was the objective of this study. The drug to polymer ratio of formulated tablets was 4:1. Hydrochlorothiazide or diltiazem HCl extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The ionic strength of the media was varied over a range of 0-0.4M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. Sodium chloride was used for ionic regulation due to its ability to salt out polymers in the midrange of the lyotropic series. The results showed that the ionic strength had a profound effect on the drug release from the diltiazem HCl K100LV matrices. The K4M, K15M and K100M tablets however withstood the effects of media ionic strength and showed a decrease in drug release to occur with an increase in ionic strength. For example, drug release after the 1h mark for the K100M matrices in water was 36%. Drug release in pH 1.2 after 1h was 30%. An increase of the pH 1.2 ionic strength to 0.4M saw a reduction of drug release to 26%. This was the general trend for the K4M and K15M matrices as well. The similarity factor f2 was calculated using drug release in water as a reference. Despite similarity occurring for all the diltiazem HCl matrices in the pH 1.2 media (f2=64-72), increases of ionic strength at 0.2M and 0.4M brought about dissimilarity. The hydrochlorothiazide tablet matrices showed similarity at all the ionic strength tested for all polymers (f2=56-81). The values of f2 however reduced with increasing ionic strengths. DSC hydration results explained the hydrochlorothiazide release from their HPMC matrices. There was an increase in bound water as ionic strengths increased. Texture analysis was employed to determine the gel strength and also to explain the drug release for the diltiazem hydrochloride. This methodology can be used as a valuable tool for predicting potential ionic effects related to in vivo fed and fasted states on drug release from hydrophilic ER matrices. Copyright © 2013 Elsevier B.V. All rights reserved.

Go with the Flow: Cerebrospinal Fluid Flow Regulates Neural Stem Cell Proliferation.

PubMed

Kaneko, Naoko; Sawamoto, Kazunobu

2018-06-01

Adult neural stem cells in the wall of brain ventricles make direct contact with cerebrospinal fluid. In this issue of Cell Stem Cell, Petrik et al. (2018) demonstrate that these neural stem cells sense the flow of cerebrospinal fluid through a transmembrane sodium channel, ENaC, which regulates their proliferation. Copyright © 2018 Elsevier Inc. All rights reserved.

Magnetic timing valves for fluid control in paper-based microfluidics.

PubMed

Li, Xiao; Zwanenburg, Philip; Liu, Xinyu

2013-07-07

Multi-step analytical tests, such as an enzyme-linked immunosorbent assay (ELISA), require delivery of multiple fluids into a reaction zone and counting the incubation time at different steps. This paper presents a new type of paper-based magnetic valves that can count the time and turn on or off a fluidic flow accordingly, enabling timed fluid control in paper-based microfluidics. The timing capability of these valves is realized using a paper timing channel with an ionic resistor, which can detect the event of a solution flowing through the resistor and trigger an electromagnet (through a simple circuit) to open or close a paper cantilever valve. Based on this principle, we developed normally-open and normally-closed valves with a timing period up to 30.3 ± 2.1 min (sufficient for an ELISA on paper-based platforms). Using the normally-open valve, we performed an enzyme-based colorimetric reaction commonly used for signal readout of ELISAs, which requires a timed delivery of an enzyme substrate to a reaction zone. This design adds a new fluid-control component to the tool set for developing paper-based microfluidic devices, and has the potential to improve the user-friendliness of these devices.

[Effects of simulated body fluid flowing rate on bone-like apatite formation on porous calcium phosphate ceramics].

PubMed

Duan, You-rong; Liu, Ke-wei; Chen, Ji-yong; Zhang, Xing-dong

2002-06-01

Objective. Bone-like apatite formation on the surface of calcium phosphate ceramics was believed to be the necessary step that new bone grows on the ceramics and to be relative to the osteoinductivity of the material. This study aimed at investigating the influence of the flow rate of simulated body fluid (SBF) (2 ml/min) in skeletal muscle upon the formation of bone-like apatite on porous calcium phosphate ceramics. Method. The dynamic condition was realized by controlling the SBF flowing in/out of the sample chamber of 100 ml. The flow rate of 2 ml/min is close to that in human muscle environment. The pH and inorganic ionic composition of SBF are close to those of human body fluid. Result. Bone-like apatite formation was relatively easier to occur in static SBF than in dynamic SBF. Experiment with flowing SBF (dynamic SBF) is better in mimicking the living body fluid than static SBF. Conclusion. The results from dynamic SBF may more truly show the relation between apatite layer formation and osteoinduction in biomaterials than that from in vitro experiments before.

Changes in the quaternary structure of phosphoenolpyruvate carboxylase induced by ionic strength affect its catalytic activity.

PubMed

Wagner, R; Gonzalez, D H; Podesta, F E; Andreo, C S

1987-05-04

Phosphoenolpyruvate carboxylase from maize leaves dissociated into dimers and/or monomers when exposed to increasing ionic strength (e.g. 200-400 mM NaCl) as indicated by gel filtration experiments. Changes in the oligomerization state were dependent on pH, time of preincubation with salt and protein concentration. A dissociation into dimers and monomers was observed at pH 8, while at pH 7 dissociation into the dimeric form only was observed. Exposure of the enzyme to higher ionic strength decreased the activity in a time-dependent manner. Turnover conditions and glucose 6-phosphate protected the carboxylase from the decay in activity, which was faster at pH 7 than at pH 8. The results suggest that changes in activity of the enzyme, following exposure to high ionic strength, are the consequence of dissociation. Tetrameric and dimeric forms of the phosphoenolpyruvate carboxylase seemingly reveal different catalytic properties. We suggest that the distinct catalytic properties of the different oligomeric species of phosphoenolpyruvate carboxylase and changes in the equilibrium between them could be the molecular basis for an effective regulation of metabolite levels by this key enzyme of C4 plants.

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 role for H2S in plant priming, and in particular in a fruit crop such as strawberry. PMID:23567865

Statistical field theory description of inhomogeneous polarizable soft matter

NASA Astrophysics Data System (ADS)

Martin, Jonathan M.; Li, Wei; Delaney, Kris T.; Fredrickson, Glenn H.

2016-10-01

We present a new molecularly informed statistical field theory model of inhomogeneous polarizable soft matter. The model is based on fluid elements, referred to as beads, that can carry a net monopole of charge at their center of mass and a fixed or induced dipole through a Drude-type distributed charge approach. The beads are thus polarizable and naturally manifest attractive van der Waals interactions. Beyond electrostatic interactions, beads can be given soft repulsions to sustain fluid phases at arbitrary densities. Beads of different types can be mixed or linked into polymers with arbitrary chain models and sequences of charged and uncharged beads. By such an approach, it is possible to construct models suitable for describing a vast range of soft-matter systems including electrolyte and polyelectrolyte solutions, ionic liquids, polymerized ionic liquids, polymer blends, ionomers, and block copolymers, among others. These bead models can be constructed in virtually any ensemble and converted to complex-valued statistical field theories by Hubbard-Stratonovich transforms. One of the fields entering the resulting theories is a fluctuating electrostatic potential; other fields are necessary to decouple non-electrostatic interactions. We elucidate the structure of these field theories, their consistency with macroscopic electrostatic theory in the absence and presence of external electric fields, and the way in which they embed van der Waals interactions and non-uniform dielectric properties. Their suitability as a framework for computational studies of heterogeneous soft matter systems using field-theoretic simulation techniques is discussed.

Statistical field theory description of inhomogeneous polarizable soft matter.

PubMed

Martin, Jonathan M; Li, Wei; Delaney, Kris T; Fredrickson, Glenn H

2016-10-21

We present a new molecularly informed statistical field theory model of inhomogeneous polarizable soft matter. The model is based on fluid elements, referred to as beads, that can carry a net monopole of charge at their center of mass and a fixed or induced dipole through a Drude-type distributed charge approach. The beads are thus polarizable and naturally manifest attractive van der Waals interactions. Beyond electrostatic interactions, beads can be given soft repulsions to sustain fluid phases at arbitrary densities. Beads of different types can be mixed or linked into polymers with arbitrary chain models and sequences of charged and uncharged beads. By such an approach, it is possible to construct models suitable for describing a vast range of soft-matter systems including electrolyte and polyelectrolyte solutions, ionic liquids, polymerized ionic liquids, polymer blends, ionomers, and block copolymers, among others. These bead models can be constructed in virtually any ensemble and converted to complex-valued statistical field theories by Hubbard-Stratonovich transforms. One of the fields entering the resulting theories is a fluctuating electrostatic potential; other fields are necessary to decouple non-electrostatic interactions. We elucidate the structure of these field theories, their consistency with macroscopic electrostatic theory in the absence and presence of external electric fields, and the way in which they embed van der Waals interactions and non-uniform dielectric properties. Their suitability as a framework for computational studies of heterogeneous soft matter systems using field-theoretic simulation techniques is discussed.

Effect of bodily fluids from honey bee (Apis mellifera) larvae on growth and genome-wide transcriptional response of the causal agent of American Foulbrood disease (Paenibacillus larvae).

PubMed

De Smet, Lina; De Koker, Dieter; Hawley, Alyse K; Foster, Leonard J; De Vos, Paul; de Graaf, Dirk C

2014-01-01

Paenibacillus larvae, the causal agent of American Foulbrood disease (AFB), affects honey bee health worldwide. The present study investigates the effect of bodily fluids from honey bee larvae on growth velocity and transcription for this Gram-positive, endospore-forming bacterium. It was observed that larval fluids accelerate the growth and lead to higher bacterial densities during stationary phase. The genome-wide transcriptional response of in vitro cultures of P. larvae to larval fluids was studied by microarray technology. Early responses of P. larvae to larval fluids are characterized by a general down-regulation of oligopeptide and sugar transporter genes, as well as by amino acid and carbohydrate metabolic genes, among others. Late responses are dominated by general down-regulation of sporulation genes and up-regulation of phage-related genes. A theoretical mechanism of carbon catabolite repression is discussed.

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.

Ionic liquid as a potential solvent for preparation of collagen-alginate-hydroxyapatite beads as bone filler.

PubMed

Iqbal, Bushra; Sarfaraz, Zenab; Muhammad, Nawshad; Ahmad, Pervaiz; Iqbal, Jibran; Khan, Zia Ul Haq; Gonfa, Girma; Iqbal, Farasat; Jamal, Arshad; Rahim, Abdur

2018-07-01

In this study, collagen/alginate/hydroxyapatite beads having different proportions were prepared as bone fillers for the restoration of osteological defects. Ionic liquid was used to dissolve the collagen and subsequently the solution was mixed with sodium alginate solution. Hydroxyapatite was added in different proportions, with the rationale to enhance mechanical as well as biological properties. The prepared solutions were given characteristic bead shapes by dropwise addition into calcium chloride solution. The prepared beads were characterized using FTIR, XRD, TGA and SEM analysis. Microhardness testing was used to evaluate the mechanical properties. The prepared beads were investigated for water adsorption behavior to ascertain its ability for body fluid uptake and adjusted accordingly to the bone cavity. Drug loading and subsequently the antibacterial activity was investigated for the prepared beads. The biocompatibility was assessed using the hemolysis testing and cell proliferation assay. The prepared collagen-alginate-HA beads, having biocompatibility and good mechanical properties, have showed an option of promising biologically active bone fillers for bone regeneration.

Molecular dynamics simulations of polyethers and a quaternary ammonium ionic liquid as CO2 absorbers

NASA Astrophysics Data System (ADS)

Cardoso, Piercarlo Fortunato; Fernandez, Juan S. L. C.; Lepre, Luiz Fernando; Ando, Rômulo Augusto; Costa Gomes, Margarida F.; Siqueira, Leonardo J. A.

2018-04-01

The properties of mixtures of butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N4111][NTf2], with poly(ethyleneglycol) dimethyl ether, PEO, were described as a function of PEO chain size by molecular dynamics simulations. Both PEO chain size and mixture composition revealed to play a significant role in determining the structure and the dynamics of the fluids. The remarkably higher viscosity observed for mixtures composed by 0.25 mole fraction of PEO was attributed to the increase in the gauche population of OCCO dihedral of the polyether of longer chains. The negative solvation enthalpy (ΔsolH < 0) and entropy (ΔsolS < 0) revealed a favorable CO2 absorption by the neat and mixture systems. The CO2 absorption was higher in neat PEO, particularly considering longer chains. The gas solubility in the mixtures presented intermediate values in comparison to the neat PEO and neat ionic liquid. The CO2 solutions had their structures discussed in the light of the calculated radial and spatial distribution functions.

Spherical harmonics analysis of surface density fluctuations of spherical ionic SDS and nonionic C12E8 micelles: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Yoshii, Noriyuki; Nimura, Yuki; Fujimoto, Kazushi; Okazaki, Susumu

2017-07-01

The surface structure and its fluctuation of spherical micelles were investigated using a series of density correlation functions newly defined by spherical harmonics and Legendre polynomials based on the molecular dynamics calculations. To investigate the influence of head-group charges on the micelle surface structure, ionic sodium dodecyl sulfate and nonionic octaethyleneglycol monododecylether (C12E8) micelles were investigated as model systems. Large-scale density fluctuations were observed for both micelles in the calculated surface static structure factor. The area compressibility of the micelle surface evaluated by the surface static structure factor was tens-of-times larger than a typical value of a lipid membrane surface. The structural relaxation time, which was evaluated from the surface intermediate scattering function, indicates that the relaxation mechanism of the long-range surface structure can be well described by the hydrostatic approximation. The density fluctuation on the two-dimensional micelle surface has similar characteristics to that of three-dimensional fluids near the critical point.

Spherical harmonics analysis of surface density fluctuations of spherical ionic SDS and nonionic C12E8 micelles: A molecular dynamics study.

PubMed

Yoshii, Noriyuki; Nimura, Yuki; Fujimoto, Kazushi; Okazaki, Susumu

2017-07-21

The surface structure and its fluctuation of spherical micelles were investigated using a series of density correlation functions newly defined by spherical harmonics and Legendre polynomials based on the molecular dynamics calculations. To investigate the influence of head-group charges on the micelle surface structure, ionic sodium dodecyl sulfate and nonionic octaethyleneglycol monododecylether (C 12 E 8 ) micelles were investigated as model systems. Large-scale density fluctuations were observed for both micelles in the calculated surface static structure factor. The area compressibility of the micelle surface evaluated by the surface static structure factor was tens-of-times larger than a typical value of a lipid membrane surface. The structural relaxation time, which was evaluated from the surface intermediate scattering function, indicates that the relaxation mechanism of the long-range surface structure can be well described by the hydrostatic approximation. The density fluctuation on the two-dimensional micelle surface has similar characteristics to that of three-dimensional fluids near the critical point.

Molecular dynamics simulations of polyethers and a quaternary ammonium ionic liquid as CO2 absorbers.

PubMed

Cardoso, Piercarlo Fortunato; Fernandez, Juan S L C; Lepre, Luiz Fernando; Ando, Rômulo Augusto; Costa Gomes, Margarida F; Siqueira, Leonardo J A

2018-04-07

The properties of mixtures of butyltrimethylammonium bis(trifluoromethylsulfonyl)imide, [N 4111 ][NTf 2 ], with poly(ethyleneglycol) dimethyl ether, PEO, were described as a function of PEO chain size by molecular dynamics simulations. Both PEO chain size and mixture composition revealed to play a significant role in determining the structure and the dynamics of the fluids. The remarkably higher viscosity observed for mixtures composed by 0.25 mole fraction of PEO was attributed to the increase in the gauche population of OCCO dihedral of the polyether of longer chains. The negative solvation enthalpy (Δ sol H < 0) and entropy (Δ sol S < 0) revealed a favorable CO 2 absorption by the neat and mixture systems. The CO 2 absorption was higher in neat PEO, particularly considering longer chains. The gas solubility in the mixtures presented intermediate values in comparison to the neat PEO and neat ionic liquid. The CO 2 solutions had their structures discussed in the light of the calculated radial and spatial distribution functions.

In vitro bioactivity of akermanite ceramics.

PubMed

Wu, Chengtie; Chang, Jiang; Ni, Siyu; Wang, Junying

2006-01-01

In this study, the bone-like apatite-formation ability of akermanite ceramics (Ca2MgSi2O7) in simulated body fluid (SBF) and the effects of ionic products from akermanite dissolution on osteoblasts and mouse fibroblasts (cell line L929) were investigated. In addition, osteoblast morphology and proliferation on the ceramics were evaluated. The results showed that akermanite ceramics possessed bone-like apatite-formation ability comparable with bioactive wollastonite ceramics (CaSiO3) after 20 days of soaking in SBF and the mechanism of bone-like apatite formation on akermanite ceramics is similar to that of wollastonite ceramics. The Ca, Si, and Mg ions from akermanite dissolution at certain ranges of concentration significantly stimulated osteoblast and L929 cell proliferation. Furthermore, osteoblasts spread well on the surface of akermanite ceramics, and proliferated with increasing the culture time. The results showed that akermanite ceramics possess bone-like apatite-formation ability and can release soluble ionic products to stimulate cell proliferation, which indicated good bioactivity. (c) 2005 Wiley Periodicals, Inc

Drainage and Stratification Kinetics of Foam Films

NASA Astrophysics Data System (ADS)

Zhang, Yiran; Sharma, Vivek

2014-03-01

Baking bread, brewing cappuccino, pouring beer, washing dishes, shaving, shampooing, whipping eggs and blowing bubbles all involve creation of aqueous foam films. Foam lifetime, drainage kinetics and stability are strongly influenced by surfactant type (ionic vs non-ionic), and added proteins, particles or polymers modify typical responses. The rate at which fluid drains out from a foam film, i.e. drainage kinetics, is determined in the last stages primarily by molecular interactions and capillarity. Interestingly, for certain low molecular weight surfactants, colloids and polyelectrolyte-surfactant mixtures, a layered ordering of molecules, micelles or particles inside the foam films leads to a stepwise thinning phenomena called stratification. Though stratification is observed in many confined systems including foam films containing particles or polyelectrolytes, films containing globular proteins seem not to show this behavior. Using a Scheludko-type cell, we experimentally study the drainage and stratification kinetics of horizontal foam films formed by protein-surfactant mixtures, and carefully determine how the presence of proteins influences the hydrodynamics and thermodynamics of foam films.

Water-Borne Endovascular Embolics Inspired by the Undersea Adhesive of Marine Sandcastle Worms.

PubMed

Jones, Joshua P; Sima, Monika; O'Hara, Ryan G; Stewart, Russell J

2016-04-06

Transcatheter embolization is used to treat vascular malformations and defects, to control bleeding, and to selectively block blood supply to tissues. Liquid embolics are used for small vessel embolization that require distal penetration. Current liquid embolic agents have serious drawbacks, mostly centered around poor handling characteristics and toxicity. In this work, a water-borne in situ setting liquid embolic agent is described that is based on electrostatically condensed, oppositely charged polyelectrolytes-complex coacervates. At high ionic strengths, the embolic coacervates are injectable fluids that can be delivered through long narrow microcatheters. At physiological ionic strength, the embolic coacervates transition into a nonflowing solid morphology. Transcatheter embolization of rabbit renal arteries demonstrated capillary level penetration, homogeneous occlusion, and 100% devascularization of the kidney, without the embolic crossing into venous circulation. The benign water-borne composition and setting mechanism avoids many of the problems of current liquid embolics, and provides precise temporal and spatial control during endovascular embolization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neural mechanisms of volume regulation.

PubMed

DiBona, G F

1983-05-01

Under steady-state conditions, urinary sodium excretion matches dietary sodium intake. Because extracellular fluid osmolality is tightly regulated, the quantity of sodium in the extracellular fluid determines the volume of this compartment. The left atrial volume receptor mechanism is an example of a neural mechanism of volume regulation. The left atrial mechanoreceptor, which functions as a sensor in the low-pressure vascular system, has a well-defined compliance relating intravascular volume to filling pressure and responds to changes in wall tension by discharging into afferent vagal fibers. These fibers have appropriate central nervous system representation whose related efferent neurohumoral mechanisms regulate thirst, renal excretion of water and sodium, and the redistribution of the extracellular fluid volume.

Crop epigenetics and the molecular hardware of genotype × environment interactions.

PubMed

King, Graham J

2015-01-01

Crop plants encounter thermal environments which fluctuate on a diurnal and seasonal basis. Future climate resilient cultivars will need to respond to thermal profiles reflecting more variable conditions, and harness plasticity that involves regulation of epigenetic processes and complex genomic regulatory networks. Compartmentalization within plant cells insulates the genomic central processing unit within the interphase nucleus. This review addresses the properties of the chromatin hardware in which the genome is embedded, focusing on the biophysical and thermodynamic properties of DNA, histones and nucleosomes. It explores the consequences of thermal and ionic variation on the biophysical behavior of epigenetic marks such as DNA cytosine methylation (5mC), and histone variants such as H2A.Z, and how these contribute to maintenance of chromatin integrity in the nucleus, while enabling specific subsets of genes to be regulated. Information is drawn from theoretical molecular in vitro studies as well as model and crop plants and incorporates recent insights into the role epigenetic processes play in mediating between environmental signals and genomic regulation. A preliminary speculative framework is outlined, based on the evidence of what appears to be a cohesive set of interactions at molecular, biophysical and electrostatic level between the various components contributing to chromatin conformation and dynamics. It proposes that within plant nuclei, general and localized ionic homeostasis plays an important role in maintaining chromatin conformation, whilst maintaining complex genomic regulation that involves specific patterns of epigenetic marks. More generally, reversible changes in DNA methylation appear to be consistent with the ability of nuclear chromatin to manage variation in external ionic and temperature environment. Whilst tentative, this framework provides scope to develop experimental approaches to understand in greater detail the internal environment of plant nuclei. It is hoped that this will generate a deeper understanding of the molecular mechanisms underlying genotype × environment interactions that may be beneficial for long-term improvement of crop performance in less predictable climates.

Crop epigenetics and the molecular hardware of genotype × environment interactions

PubMed Central

King, Graham J.

2015-01-01

Crop plants encounter thermal environments which fluctuate on a diurnal and seasonal basis. Future climate resilient cultivars will need to respond to thermal profiles reflecting more variable conditions, and harness plasticity that involves regulation of epigenetic processes and complex genomic regulatory networks. Compartmentalization within plant cells insulates the genomic central processing unit within the interphase nucleus. This review addresses the properties of the chromatin hardware in which the genome is embedded, focusing on the biophysical and thermodynamic properties of DNA, histones and nucleosomes. It explores the consequences of thermal and ionic variation on the biophysical behavior of epigenetic marks such as DNA cytosine methylation (5mC), and histone variants such as H2A.Z, and how these contribute to maintenance of chromatin integrity in the nucleus, while enabling specific subsets of genes to be regulated. Information is drawn from theoretical molecular in vitro studies as well as model and crop plants and incorporates recent insights into the role epigenetic processes play in mediating between environmental signals and genomic regulation. A preliminary speculative framework is outlined, based on the evidence of what appears to be a cohesive set of interactions at molecular, biophysical and electrostatic level between the various components contributing to chromatin conformation and dynamics. It proposes that within plant nuclei, general and localized ionic homeostasis plays an important role in maintaining chromatin conformation, whilst maintaining complex genomic regulation that involves specific patterns of epigenetic marks. More generally, reversible changes in DNA methylation appear to be consistent with the ability of nuclear chromatin to manage variation in external ionic and temperature environment. Whilst tentative, this framework provides scope to develop experimental approaches to understand in greater detail the internal environment of plant nuclei. It is hoped that this will generate a deeper understanding of the molecular mechanisms underlying genotype × environment interactions that may be beneficial for long-term improvement of crop performance in less predictable climates. PMID:26594221

Quantitative mapping of intracellular cations in the human amniotic membrane

NASA Astrophysics Data System (ADS)

Moretto, Ph.; Llabador, Y.; Simonoff, M.; Razafindrabe, L.; Bara, M.; Guiet-Bara, A.

1993-05-01

The effect of magnesium and taurine on the permeability of cell membranes to monovalent cations has been investigated using the Bordeaux nuclear microprobe. PIXE and RBS techniques have been used to provide quantitative measurements and ion distributions in the isolated amniotic membrane. This physiological model for cellular exchanges allowed us to reveal the distribution of most elements involved in cellular pathways and the modifications under different experimental conditions of incubation in physiological fluids. The PIXE microanalysis provided an original viewpoint on these mechanisms. Following this first study, the amnion compact lamina was found to play a role which was not, up to now, taken into account in the interpretation of electrophysiological experimentations. The release of some ionic species, such as K +, from the epithelial cells, during immersion in isotonic fluids, could have been hitherto underestimated.

Evaluation of the Performance of O-rings Made with Different Elastomeric Polymers in Simulated Geothermal Environments at 300°C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugama, Toshifumi; Pyatina, Tatiana; Redline, Erica Marie

2014-12-01

This paper aims to evaluate the survival of O-rings made with six different elastomeric polymers, EPDM, type I- and II-FKM, FEPM, FFKM, and FSR, in five different simulated geothermal environments at 300°C. It further defines the relative strengths and weaknesses of the materials in each environment. The environments tested were: 1) non-aerated steam-cooling cycles, 2) aerated steam-cooling cycles, 3) water-based drilling fluid, 4) CO2-rich geo-brine fluid, and, 5) heat-cool water quenching cycles. Following exposure, the extent of oxidation, oxidationinduced degradation, thermal behaviors, micro-defects, permeation depths of ionic species present in environments throughout the O-ring, silicate-related scale-deposition, and changes in mechanicalmore » properties were assessed.« less

Changes in membrane conductances and areas associated with bicarbonate secretion in turtle bladder.

PubMed

Rich, A; Dixon, T E; Clausen, C

1990-02-01

Transepithelial impedance-analysis studies were performed in turtle bladder epithelium in order to measure changes in the different epithelial membranes resulting from stimulation of electrogenic bicarbonate secretion. Changes in membrane conductance relate to changes in ionic permeability, whereas changes in membrane capacitance relate to changes in membrane area, since most biological membranes exhibit a specific capacitance of approximately 1 muF/cm2. The results of this investigation are summarized as follows: (i) cAMP and carbachol, agents which have been shown previously to stimulate electrogenic bicarbonate secretion, result in increases in apical-membrane conductance and capacitance; (ii) these changes occur concomitantly with the observed change in transport (measured using the short-circuit-current technique), thereby suggesting that bicarbonate secretion may be regulated in part by changes in the chloride conductance of the apical membrane; (iii) the increase in conductance does not reflect an increase in the membrane's specific conductance, thereby indicating that it results from the addition of membrane possessing similar ionic permeability as the existing apical membrane; (iv) the magnitude of the changes in capacitance indicate that a minor cell population (beta-type carbonic-anhydrase-rich cells) increase their apical-membrane area by several-fold; (v) a lack of transport-associated changes in the basolateral-membrane parameters suggest that transport is not regulated by alterations in basolateral-membrane ionic conductance or area; (vi) a lack of colchicine sensitivity, coupled with the magnitude of the changes in apical-membrane capacitance, indicate that the membrane remodeling processes are different from those involved in the regulation of proton secretion in a different cell population (alpha-type carbonic-anhydrase-rich cells).

Crosslink between calcium and sodium signalling.

PubMed

Verkhratsky, Alexei; Trebak, Mohamed; Perocchi, Fabiana; Khananshvili, Daniel; Sekler, Israel

2018-02-01

What is the topic of this review? This paper overviews the links between Ca 2+ and Na + signalling in various types of cells. What advances does it highlight? This paper highlights the general importance of ionic signalling and overviews the molecular mechanisms linking Na + and Ca 2+ dynamics. In particular, the narrative focuses on the molecular physiology of plasmalemmal and mitochondrial Na + -Ca 2+ exchangers and plasmalemmal transient receptor potential channels. Functional consequences of Ca 2+ and Na + signalling for co-ordination of neuronal activity with astroglial homeostatic pathways fundamental for synaptic transmission are discussed. Transmembrane ionic gradients, which are an indispensable feature of life, are used for generation of cytosolic ionic signals that regulate a host of cellular functions. Intracellular signalling mediated by Ca 2+ and Na + is tightly linked through several molecular pathways that generate Ca 2+ and Na + fluxes and are in turn regulated by both ions. Transient receptor potential (TRP) channels bridge endoplasmic reticulum Ca 2+ release with generation of Na + and Ca 2+ currents. The plasmalemmal Na + -Ca 2+ exchanger (NCX) flickers between forward and reverse mode to co-ordinate the influx and efflux of both ions with membrane polarization and cytosolic ion concentrations. The mitochondrial calcium uniporter channel (MCU) and mitochondrial Na + -Ca 2+ exchanger (NCLX) mediate Ca 2+ entry into and release from this organelle and couple cytosolic Ca 2+ and Na + fluctuations with cellular energetics. Cellular Ca 2+ and Na + signalling controls numerous functional responses and, in the CNS, provides for fast regulation of astroglial homeostatic cascades that are crucial for maintenance of synaptic transmission. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Metaplasticity within the spinal cord: Evidence brain-derived neurotrophic factor (BDNF), tumor necrosis factor (TNF), and alterations in GABA function (ionic plasticity) modulate pain and the capacity to learn.

PubMed

Grau, James W; Huang, Yung-Jen

2018-04-07

Evidence is reviewed that behavioral training and neural injury can engage metaplastic processes that regulate adaptive potential. This issue is explored within a model system that examines how training affects the capacity to learn within the lower (lumbosacral) spinal cord. Response-contingent (controllable) stimulation applied caudal to a spinal transection induces a behavioral modification indicative of learning. This behavioral change is not observed in animals that receive stimulation in an uncontrollable manner. Exposure to uncontrollable stimulation also engages a process that disables spinal learning for 24-48 h. Controllable stimulation has the opposite effect; it engages a process that enables learning and prevents/reverses the learning deficit induced by uncontrollable stimulation. These observations suggest that a learning episode can impact the capacity to learn in future situations, providing an example of behavioral metaplasticity. The protective/restorative effect of controllable stimulation has been linked to an up-regulation of brain-derived neurotrophic factor (BDNF). The disruption of learning has been linked to the sensitization of pain (nociceptive) circuits, which is enabled by a reduction in GABA-dependent inhibition. After spinal cord injury (SCI), the co-transporter (KCC2) that regulates the outward flow of Cl - is down-regulated. This causes the intracellular concentration of Cl - to increase, reducing (and potentially reversing) the inward flow of Cl - through the GABA-A receptor. The shift in GABA function (ionic plasticity) increases neural excitability caudal to injury and sets the stage for nociceptive sensitization. The injury-induced shift in KCC2 is related to the loss of descending serotonergic (5HT) fibers that regulate plasticity within the spinal cord dorsal horn through the 5HT-1A receptor. Evidence is presented that these alterations in spinal plasticity impact pain in a brain-dependent task (place conditioning). The findings suggest that ionic plasticity can affect learning potential, shifting a neural circuit from dampened/hard-wired to excitable/plastic. Copyright © 2018 Elsevier Inc. All rights reserved.

Controls of ionic strength and macromolecule chemistry on calcite nucleation: Salinity and ion hydration as levers for regulating biomineralization

NASA Astrophysics Data System (ADS)

Dove, P. M.; Giuffre, A. J.; Mergelsberg, S. T.; Han, N.; De Yoreo, J. J.

2016-12-01

Organisms form shells and skeletons with remarkable fidelity by controlling the timing and placement of the minerals that nucleate and subsequently grow. An extensive effort has identified features of the organic matrix that regulate this process. Recent measurements from our group show the energy barrier to nucleation onto polysaccharide (PS) substrates is dependent upon hydrophilicity through functional group chemistry and suggest that free energy of the macromolecule-liquid interface influences where and when mineral nucleation occurs (Giuffre et al., 2013, PNAS). The importance of interfacial free energy in regulating nucleation raises the question of whether local changes in salinity or electrolyte composition can be tuned to further modulate the onset of calcite nucleation. Using alginate (negatively charged by carboxyl groups) and chitosan (small positive charge by amine groups), the rate of calcite nucleation was measured at controlled supersaturations and pH as a function of NaCl concentration (65-600 mM). Analyses of the data show the thermodynamic barrier to calcite nucleation onto both types of PS increases with ionic strength. The evidence suggests this effect arises from an increasing concentration of solvated ions at the PS-water interface while also increasing the hydrophilic character of that interface; thus decreasing the substrate-liquid interfacial free energy. To test this explanation, a second group of nucleation experiments used a suite of electrolytes (alkali chlorides for alginate and sodium halides for chitosan) while holding ionic strength constant. Indeed, the nucleation barriers for calcite formation are electrolyte-specific and correlated with the hydration free energy of the ion. This suggests solvated electrolyte ions indirectly regulate calcite nucleation onto substrates through their competition with the substrate for water thereby influencing net interfacial free energy. These effects are consistent with the long-established salting-in phenomena of the Hofmeister series. The new insights from this experimental study reiterate the importance of electrolytes in reactions involving mineral-water interfaces and suggest a role for seemingly inert `spectator' ions in regulating the local timing and placement of minerals during biomineralization.

Rankine cycle condenser pressure control using an energy conversion device bypass valve

DOEpatents

Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

2014-04-01

The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

The effect of pigeon yolk sac fluid on the growth behavior of calcium carbonate crystals.

PubMed

Song, Juan; Cheng, Haixia; Shen, Xinyu; Tong, Hua

2015-03-01

Previous experiments have proved that thermodynamically unstable calcium carbonate vaterite can exist for long periods in the yolk sac of a pigeon embryo. The aim of this article was to demonstrate the effect of in vitro mineralization of yolk sac fluid on calcium carbonate by direct precipitation. Experiments were conducted using pigeon yolk sac fluid and using lecithin extracted from pigeon yolk sac fluid as a control to investigate the regulating effects of the organic components in the embryo on the formation of the calcium carbonate precipitate. Multiple characterization methods were employed to study the various morphological patterns, sizes, crystal growth, and crystal phase transformations of the calcium carbonate precipitates as regulated by the yolk sac fluid extracted at different stages of incubation. The experimental results demonstrate that as the incubation proceeds towards the later stages, the composition and environmental features of the yolk sac fluid become more favorable for the formation of relatively unstable calcium carbonate phases with high energies of the vaterite state. The experiments conducted with extracted lecithin as the template for crystal growth yielded similar results. A large amount of organic molecules with polar functional groups carried by the yolk sac fluid have strong effects and can both initially induce the crystallization and regulate the aggregation of calcium carbonate. Furthermore, this regulation process is found to be closely related to the lecithin contained in yolk sac fluid. These observations confirm the changes in yolk sac fluid composition during incubation have significant effects on the production of vaterite, which implicates the calcium transport during embryo growth. © 2015 Poultry Science Association Inc.

Vibration Induced Osteogenic Commitment of Mesenchymal Stem Cells is Enhanced by Cytoskeletal Remodeling but not Fluid Shear

PubMed Central

Uzer, Gunes; Pongkitwitoon, Suphannee; Chan, M Ete; Judex, Stefan

2013-01-01

Consistent across studies in humans, animals and cells, the application of vibrations can be anabolic and/or anti-catabolic to bone. The physical mechanisms modulating the vibration-induced response have not been identified. Recently, we developed an in vitro model in which candidate parameters including acceleration magnitude and fluid shear can be controlled independently during vibrations. Here, we hypothesized that vibration induced fluid shear does not modulate mesenchymal stem cell (MSC) proliferation and mineralization and that cell’s sensitivity to vibrations can be promoted via actin stress fiber formation. Adipose derived human MSCs were subjected to vibration frequencies and acceleration magnitudes that induced fluid shear stress ranging from 0.04Pa to 5Pa. Vibrations were applied at magnitudes of 0.15g, 1g, and 2g using frequencies of both 100Hz and 30Hz. After 14d and under low fluid shear conditions associated with 100Hz oscillations, mineralization was greater in all vibrated groups than in controls. Greater levels of fluid shear produced by 30Hz vibrations enhanced mineralization only in the 2g group. Over 3d, vibrations led to the greatest increase in total cell number with the frequency/acceleration combination that induced the smallest level of fluid shear. Acute experiments showed that actin remodeling was necessary for early mechanical up-regulation of RUNX-2 mRNA levels. During osteogenic differentiation, mechanically induced up-regulation of actin remodeling genes including Wiskott-Aldrich syndrome (WAS) protein, a critical regulator of Arp2/3 complex, was related to the magnitude of the applied acceleration but not to fluid shear. These data demonstrate that fluid shear does not regulate vibration induced proliferation and mineralization and that cytoskeletal remodeling activity may play a role in MSC mechanosensitivity. PMID:23870506

The role of evaporites in the formation of gems during metamorphism of carbonate platforms: a review

NASA Astrophysics Data System (ADS)

Giuliani, Gaston; Dubessy, Jean; Ohnenstetter, Daniel; Banks, David; Branquet, Yannick; Feneyrol, Julien; Fallick, Anthony E.; Martelat, Jean-Emmanuel

2018-01-01

The mineral and fluid inclusions trapped by gemstones during the metamorphism of carbonate platform successions are precious markers for the understanding of gem genesis. The nature and chemical composition of inclusions highlight the major contribution of evaporites through dissolution or fusion, depending on the temperature of formation from greenschist to granulite facies. The fluids are highly saline NaCl-brines circulating either in an open system in the greenschist facies (Colombian and Afghan emeralds) and with huge fluid-rock metasomatic interactions, or sulphurous fluids (ruby, garnet tsavorite, zoisite tanzanite and lapis-lazuli) or molten salts formed in a closed system with a low fluid mobility (ruby in marble) in the conditions of the amphibolite to granulite facies. These chloride-fluoride-sulphate ± carbonate-rich fluids scavenged the metals essential for gem formation. At high temperature, the anions SO4 2-, NO3 -, BO3 - and F- are powerful fluxes which lower the temperature of chloride- and fluoride-rich ionic liquids. They provided transport over a very short distance of aluminium and/or silica and transition metals which are necessary for gem growth. In summary, the genetic models proposed for these high-value and ornamental gems underline the importance of the metamorphism of evaporites formed on continental carbonate shelves and emphasise the chemical power accompanying metamorphism at moderate to high temperatures of evaporite-rich and organic matter-rich protoliths to form gem minerals.

Nonequilibrium electrokinetic effects in beds of ion-permselective particles.

PubMed

Leinweber, Felix C; Tallarek, Ulrich

2004-12-21

Electrokinetic transport of fluorescent tracer molecules in a bed of porous glass beads was investigated by confocal laser scanning microscopy. Refractive index matching between beads and the saturating fluid enabled a quantitative analysis of intraparticle and extraparticle fluid-side concentration profiles. Kinetic data were acquired for the uptake and release of electroneutral and counterionic tracer under devised conditions with respect to constant pressure-driven flow through the device and the effect of superimposed electrical fields. Transport of neutral tracer is controlled by intraparticle mass transfer resistance which can be strongly reduced by electroosmotic flow, while steady-state distributions and bead-averaged concentrations are unaffected by the externally applied fields. Electrolytes of low ionic strength caused the transport through the charged (mesoporous) beads to become highly ion-permselective, and concentration polarization is induced in the bulk solution due to the superimposed fields. The depleted concentration polarization zone comprises extraparticle fluid-side mass transfer resistance. Ionic concentrations in this diffusion boundary layer decrease at increasing field strength, and the flux densities approach an upper limit. Meanwhile, intraparticle transport of counterions by electromigration and electroosmosis continues to increase and finally exceeds the transport from bulk solution into the beads. A nonequilibrium electrical double layer is induced which consists of mobile and immobile space charge regions in the extraparticle bulk solution and inside a bead, respectively. These electrical field-induced space charges form the basis for nonequilibrium electrokinetic phenomena. Caused by the underlying transport discrimination (intraparticle electrokinetic vs extraparticle boundary-layer mass transfer), the dynamic adsorption capacity for counterions can be drastically reduced. Further, the extraparticle mobile space charge region leads to nonlinear electroosmosis. Flow patterns can become highly chaotic, and electrokinetic instability mixing is shown to increase lateral dispersion. Under these conditions, the overall axial dispersion of counterionic tracer can be reduced by more than 2 orders of magnitude, as demonstrated by pulse injections.

Mechanical and electromagnetic properties of northern Gulf of Mexico sediments with and without THF hydrates

USGS Publications Warehouse

Lee, J.Y.; Santamarina, J.C.; Ruppel, C.

2008-01-01

Using an oedometer cell instrumented to measure the evolution of electromagnetic properties, small strain stiffness, and temperature, we conducted consolidation tests on sediments recovered during drilling in the northern Gulf of Mexico at the Atwater Valley and Keathley Canyon sites as part of the 2005 Chevron Joint Industry Project on Methane Hydrates. The tested specimens include both unremolded specimens (as recovered from the original core liner) and remolded sediments both without gas hydrate and with pore fluid exchanged to attain 100% synthetic (tetrahydrofuran) hydrate saturation at any stage of loading. Test results demonstrate the extent to which the electromagnetic and mechanical properties of hydrate-bearing marine sediments are governed by the vertical effective stress, stress history, porosity, hydrate saturation, fabric, ionic concentration of the pore fluid, and temperature. We also show how permittivity and electrical conductivity data can be used to estimate the evolution of hydrate volume fraction during formation. The gradual evolution of geophysical properties during hydrate formation probably reflects the slow increase in ionic concentration in the pore fluid due to ion exclusion in closed systems and the gradual decrease in average pore size in which the hydrate forms. During hydrate formation, the increase in S-wave velocity is delayed with respect to the decrease in permittivity, consistent with hydrate formation on mineral surfaces and subsequent crystal growth toward the pore space. No significant decementation/debonding occurred in 100% THF hydrate-saturated sediments during unloading, hence the probability of sampling hydrate-bearing sediments without disturbing the original sediment fabric is greatest for samples in which the gas hydrate is primarily responsible for maintaining the sediment fabric and for which the time between core retrieval and restoration of in situ effective stress in the laboratory is minimized. In evaluating the impact of core retrieval on specimen properties, it is also important to consider how far removed hydrate-bearing samples are from hydrate stability conditions. ?? 2008 Elsevier Ltd.

Combination of in situ metathesis reaction with a novel "magnetic effervescent tablet-assisted ionic liquid dispersive microextraction" for the determination of endogenous steroids in human fluids.

PubMed

Wu, Jia; Xu, Zilin; Pan, Yixuan; Shi, Yi; Bao, Xiujie; Li, Jun; Tong, Yu; Tang, Han; Ma, Shuyan; Wang, Xuedong; Lyu, Jianxin

2018-05-01

Herein, a novel magnetic effervescence tablet-assisted microextraction coupled to in situ metathesis reaction of ionic liquid (IS-META-ILDM) is presented for the determination of four endogenous steroids in human urine, pregnant women's blood, and fetal umbilical cord blood. The magnetic effervescent tablets, which were composed of Fe 3 O 4 nanoparticles, sodium carbonate (alkaline source), and tartaric acid (acidic source), were used to disperse the extractant and for convenient magnetic separation. After the effervescent reaction, in situ reaction between NH 4 PF 6 and [C 6 MIM]BF 4 was adopted to change hydrophilic ionic liquid to hydrophobic liquid, which could be separated from the aqueous phase. The newly developed method has three obvious advantages: (1) combination of effervescent dispersion and magnetic nanoparticles' retrieval is cost-effective and the dispersion and collection of the extractant can be completed almost simultaneously; (2) as compared to temperature-controlled ionic liquid dispersive microextraction and cold-induced solidified microextraction, this method avoids a heating and cooling process which significantly reduces the extraction time and energy cost; and (3) the combination of adsorption by magnetic nanoparticles with extraction by in situ metathesis reaction easily produces high recoveries for target analytes. The optimized composition of effervescent tablet and experimental parameters are as follows: 0.64 g mixture of sodium carbonate and tartaric acid, 7 mg of Fe 3 O 4 (20 nm) as magnetic sorbents, 40 μL of [C 6 MIM]BF 4 as the extraction solvent, 0.15 g NH 4 PF 6 , and 300 μL of elution solvent. Under the optimized conditions, the newly developed method provided high extraction recoveries (90.0-118.5%) and low LODs (0.14-0.17 μg L -1 ) in urine and blood samples. In total, this IS-META-ILDM method provided high extraction efficiency, fast and convenient separation, and underutilization of any organic solvent, and thus it has great potential for the determination of trace endogenous steroids in complex human fluids. Graphical abstract The newly developed method has three obvious advantages: combination of effervescent dispersion and magnetic nanoparticles' retrieval is cost-effective and the dispersion and collection of the extractant can be completed almost simultaneously. It avoids a heating and cooling process which significantly reduces the extraction time and energy cost and easily produces high recoveries for target analytes.

Modulation of Molecular Flux Using a Graphene Nanopore Capacitor.

PubMed

Shankla, Manish; Aksimentiev, Aleksei

2017-04-20

Modulation of ionic current flowing through nanoscale pores is one of the fundamental biological processes. Inspired by nature, nanopores in synthetic solid-state membranes are being developed to enable rapid analysis of biological macromolecules and to serve as elements of nanofludic circuits. Here, we theoretically investigate ion and water transport through a graphene-insulator-graphene membrane containing a single, electrolyte-filled nanopore. By means of all-atom molecular dynamics simulations, we show that the charge state of such a graphene nanopore capacitor can regulate both the selectivity and the magnitude of the nanopore ionic current. At a fixed transmembrane bias, the ionic current can be switched from being carried by an equal mixture of cations and anions to being carried almost exclusively by either cationic or anionic species, depending on the sign of the charge assigned to both plates of the capacitor. Assigning the plates of the capacitor opposite sign charges can either increase the nanopore current or reduce it substantially, depending on the polarity of the bias driving the transmembrane current. Facilitated by the changes of the nanopore surface charge, such ionic current modulations are found to occur despite the physical dimensions of the nanopore being an order of magnitude larger than the screening length of the electrolyte. The ionic current rectification is accompanied by a pronounced electro-osmotic effect that can transport neutral molecules such as proteins and drugs across the solid-state membrane and thereby serve as an interface between electronic and chemical signals.

7 CFR 1001.16 - Fluid cream product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid cream product. 1001.16 Section 1001.16 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating...

7 CFR 1001.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1001.15 Section 1001.15 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating...

The Influence of High Drug Loading in Xanthan Tablets and Media with Different Physiological pH and Ionic Strength on Swelling and Release.

PubMed

Mikac, Urša; Sepe, Ana; Baumgartner, Saša; Kristl, Julijana

2016-03-07

The formation of a gel coat around xanthan (Xan) tablets, empty or loaded with pentoxifylline (PF), and its release in media differing in pH and ionic strength by NMR, MR imaging, and two release methods were studied. The T1 and T2 NMR relaxation times in gels depend predominantly on Xan concentration; the presence of PF has negligible influence on them. It is interesting that the matrix swelling is primarily regulated by Xan despite high drug loading (25%, 50%). The gastric pH and high ionic strength of the media do not influence the position of the penetration and swelling fronts but do affect the erosion front and gel thickness. The different release profiles obtained in mixing and nonmixing in vitro methods are the consequence of matrix hydration level and erosion at the surface. In water and in diluted acid medium with low ionic strength, the main release mechanism is erosion, whereas in other media (pH 1.2, μ ≥ 0.20 M), anomalous transport dominates as was found out by fitting of measured data with theoretical model. Besides the in vitro investigation that mimics gastric conditions, mathematical modeling makes the product development more successful.

Fuel cell membrane hydration and fluid metering

DOEpatents

Jones, Daniel O.; Walsh, Michael M.

1999-01-01

A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel in order to mix its respective portion of liquid water with the corresponding portion of the stream. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

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.

Molecular Insights into the Effects of Media-Drug and Carrier-Drug Interactions on pH-Responsive Drug Carriers.

PubMed

Katiyar, Ratna S; Jha, Prateek K

2018-05-10

We have performed two sets of all atom molecular dynamics (MD) simulations of poly(acrylic acid) (PAA) oligomers, considered as a model pH-responsive drug carrier. In the first set, multiple oligomers of PAA are simulated in model gastric and intestinal fluids, where the degree of deprotonation of PAA oligomers is varied with the medium pH. Since the gastric fluid has a pH substantially lower than that of intestinal fluid, PAA is relatively lesser ionized in gastric fluid and forms aggregates. In the second set, we simulated multiple oligomers of PAA with multiple molecules of a cationic anticancer drug, doxorubicin (DOX), for a range of pH values representative of various physiological conditions. The diffusion coefficient of DOX decreases with an increase in pH due to an increase in the ionic complexation of PAA with DOX, despite a decrease in PAA aggregation. Our findings are in agreement with recent experimental reports on pH-triggered targeting of tumor cells by the PAA-DOX system. Results of these two sets of studies establish that both carrier aggregation and carrier-drug interactions are competing influences that together determine the drug release from pH-responsive polymers.

Supercritical Fluid Extraction of Metal Chelate: A Review.

PubMed

Ding, Xin; Liu, Qinli; Hou, Xiongpo; Fang, Tao

2017-03-04

Supercritical fluid extraction (SFE), as a new green extraction technology, has been used in extracting various metal species. The solubilities of chelating agents and corresponding metal chelates are the key factors which influence the efficiency of SFE. Other main properties of them such as stability and selectivity are also reviewed. The extraction mechanisms of mainly used chelating agents are explained by typical examples in this paper. This is the important aspect of SFE of metal ions. Moreover, the extraction efficiencies of metal species also depend on other factors such as temperature, pressure, extraction time and matrix effect. The two main complexation methods namely in-situ and on-line chelating SFE are described in detail. As an efficient chelating agent, tributyl phosphate-nitric acid (TBP-HNO 3 ) complex attracts much attention. The SFE of metal ions, lanthanides and actinides as well as organometallic compounds are also summarized. With the proper selection of ligands, high efficient extraction of metal species can be obtained. As an efficient sample analysis method, supercritical fluid chromatography (SFC) is introduced in this paper. Recently, the extraction method combining ionic liquids (ILs) with supercritical fluid has been becoming a novel technology for treating metal ions. The kinetics related to SFE of metal species is discussed with some specific examples.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-04-26

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microehannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C [Knoxville, TN; Ramsey, J Michael [Knoxville, TN; Culbertson, Christopher T [Oak Ridge, TN; Whitten, William B [Lancing, TN; Foote, Robert S [Oak Ridge, TN

2011-03-22

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2007-11-20

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Methods for forming small-volume electrical contacts and material manipulations with fluidic microchannels

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael; Culbertson, Christopher T.; Whitten, William B.; Foote, Robert S.

2004-02-03

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either ionic current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to a variety of processes, including electrokinetically induced pressure flow in a region of a microchannel that is not influenced by an electric field, sample concentration enhancement and injection, as well as improving the analysis of materials where it is desired to eliminate electrophoretic bias. Other applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Comparison of the nonionic contrast agents, iopromide and iotrolan, for positive-contrast arthrography of the scapulohumeral joint in dogs.

PubMed

van Bree, H; Van Rijssen, B; Tshamala, M; Maenhout, T

1992-09-01

Arthrographic quality and synovial inflammatory response were examined to compare the use of iopromide with that of iotrolan for arthrography of the scapulohumeral joint in 6 dogs. Radiographs obtained 1 and 3 minutes after injection of either nonionic compound were of similar quality, but radiographs obtained 5 minutes after injection of iotrolan were significantly (P less than 0.05) better than those obtained after injection of iopromide. Results of analysis of synovial fluid samples obtained at 1, 3, 7, and 14 days after injection of contrast media were not significantly different between the 2 groups. Histologic examination of synovium and articular cartilage 2 weeks after injection of iopromide or iotrolan revealed minimal inflammatory response for both contrast agents. Injection of iopromide and iotrolan into the scapulohumeral joints of dogs had less effect on synovial fluid than that reported after injection of ionic compounds.

Dynamic bed reactor

DOEpatents

Stormo, Keith E.

1996-07-02

A dynamic bed reactor is disclosed in which a compressible open cell foam matrix is periodically compressed and expanded to move a liquid or fluid through the matrix. In preferred embodiments, the matrix contains an active material such as an enzyme, biological cell, chelating agent, oligonucleotide, adsorbent or other material that acts upon the liquid or fluid passing through the matrix. The active material may be physically immobilized in the matrix, or attached by covalent or ionic bonds. Microbeads, substantially all of which have diameters less than 50 microns, can be used to immobilize the active material in the matrix and further improve reactor efficiency. A particularly preferred matrix is made of open cell polyurethane foam, which adsorbs pollutants such as polychlorophenol or o-nitrophenol. The reactors of the present invention allow unidirectional non-laminar flow through the matrix, and promote intimate exposure of liquid reactants to active agents such as microorganisms immobilized in the matrix.

Computational Reconstruction of Pacemaking and Intrinsic Electroresponsiveness in Cerebellar Golgi Cells

PubMed Central

Solinas, Sergio; Forti, Lia; Cesana, Elisabetta; Mapelli, Jonathan; De Schutter, Erik; D'Angelo, Egidio

2007-01-01

The Golgi cells have been recently shown to beat regularly in vitro (Forti et al., 2006. J. Physiol. 574, 711–729). Four main currents were shown to be involved, namely a persistent sodium current (I Na-p), an h current (I h), an SK-type calcium-dependent potassium current (I K-AHP), and a slow M-like potassium current (I K-slow). These ionic currents could take part, together with others, also to different aspects of neuronal excitability like responses to depolarizing and hyperpolarizing current injection. However, the ionic mechanisms and their interactions remained largely hypothetical. In this work, we have investigated the mechanisms of Golgi cell excitability by developing a computational model. The model predicts that pacemaking is sustained by subthreshold oscillations tightly coupled to spikes. I Na-p and I K-slow emerged as the critical determinants of oscillations. I h also played a role by setting the oscillatory mechanism into the appropriate membrane potential range. I K-AHP, though taking part to the oscillation, appeared primarily involved in regulating the ISI following spikes. The combination with other currents, in particular a resurgent sodium current (I Na-r) and an A-current (I K-A), allowed a precise regulation of response frequency and delay. These results provide a coherent reconstruction of the ionic mechanisms determining Golgi cell intrinsic electroresponsiveness and suggests important implications for cerebellar signal processing, which will be fully developed in a companion paper (Solinas et al., 2008. Front. Neurosci. 2:4). PMID:18946520

A randomised comparison of two postoperative fluid regimens.

PubMed

Cook, J A; Fraser, I A; Sandhu, D; Everson, N W; Rossard, D P

1989-01-01

Postoperative paralytic ileus follows all significant gastrointestinal surgery. Its duration is variable and has led to a variety of empirical and time-consuming oral fluid regimens. We have compared a traditional method of fluid administration with an unstructured, simpler, patient-determined approach. A series of 102 patients on a general surgical ward who required intravenous fluids on the day after surgery were randomised by a closed envelope system to one of two protocols and followed prospectively. Of these, 12 patients were erroneously randomised or unable to fulfil trial requirements. The first, 'regulated' group (n = 41) received hourly aliquots of oral fluid as determined by twice daily ward rounds according to ward routine. The second, 'unregulated' group (n = 49) were given a jug of water and instructed to drink as desired. Patients in the regulated group received less of their postoperative fluids by the oral route at all stages of recovery but there were no significant differences in the mean durations of intravenous therapy, nasogastric intubation or hospital stay. Postoperative complication and mortality rates were also similar. Patients who underwent gastric or duodenal procedures (n = 14) showed a similar pattern of results. We conclude that 'patient-determined' regulation of postoperative oral fluid intake is safe and effective and may greatly simplify ward management.

Rheological Behavior Xanthan and SlurryPro Polymer Solutions Evaluated as Shear Thinning Delivery Fluids for Subsurface Remediation

NASA Astrophysics Data System (ADS)

Zhong, L.; Oostrom, M.; Truex, M.; Vermeul, V.

2011-12-01

Shear thinning fluids can be applied as a delivery means to enhance the uniformity of remedial amendment distribution in heterogeneous aquifers, thereby to improve remediation performance. The rheological behavior of biopolymer xanthan gum and synthetic polymer SlurryPro were tested, and their influence on the amendment delivery performance was evaluated. The impact of polymer concentration, basic water chemistry, salinity (e.g., Br-, Na+, Ca2+ concentrations), remedial amendments (phosphate, sodium lactate, ethyl lactate, lactate oil, whey), sediments, and the mixing approach on the rheological properties of the polymer solutions was determined. The SlurryPro polymer lost shear-thinning properties even at relatively low solution ionic strength. However, the xanthan gum polymer maintained shear-thinning properties under most of the tested conditions, though with some loss in absolute viscosity with increasing ionic strength. Xanthan appeared to be the better candidate for enhanced amendment delivery. Increasing in xanthan concentration not only increased the solution viscosity, but also increased degree of shear thinning. Addition of salt decreased the solution viscosity and the degree of shear thinning, while the influence was diminished when the polymer concentration was higher. After reaching a critical xanthan concentration, addition of salt increased solution viscosity. The degradation of xanthan and SlurryPro in the presence of site aquifer materials and microbes was studied in batch tests in which the field sediment/water ratio was simulated. The viscosity of the polymer solutions dropped 85% or more in the first week, while the solution chemical oxygen demand (COD) decreasing occurred at a much slower rate.

Measurements and theoretical interpretation of points of zero charge/potential of BSA protein.

PubMed

Salis, Andrea; Boström, Mathias; Medda, Luca; Cugia, Francesca; Barse, Brajesh; Parsons, Drew F; Ninham, Barry W; Monduzzi, Maura

2011-09-20

The points of zero charge/potential of proteins depend not only on pH but also on how they are measured. They depend also on background salt solution type and concentration. The protein isoelectric point (IEP) is determined by electrokinetical measurements, whereas the isoionic point (IIP) is determined by potentiometric titrations. Here we use potentiometric titration and zeta potential (ζ) measurements at different NaCl concentrations to study systematically the effect of ionic strength on the IEP and IIP of bovine serum albumin (BSA) aqueous solutions. It is found that high ionic strengths produce a shift of both points toward lower (IEP) and higher (IIP) pH values. This result was already reported more than 60 years ago. At that time, the only available theory was the purely electrostatic Debye-Hückel theory. It was not able to predict the opposite trends of IIP and IEP with ionic strength increase. Here, we extend that theory to admit both electrostatic and nonelectrostatic (NES) dispersion interactions. The use of a modified Poisson-Boltzmann equation for a simple model system (a charge regulated spherical colloidal particle in NaCl salt solutions), that includes these ion specific interactions, allows us to explain the opposite trends observed for isoelectric point (zero zeta potential) and isoionic point (zero protein charge) of BSA. At higher concentrations, an excess of the anion (with stronger NES interactions than the cation) is adsorbed at the surface due to an attractive ionic NES potential. This makes the potential relatively more negative. Consequently, the IEP is pushed toward lower pH. But the charge regulation condition means that the surface charge becomes relatively more positive as the surface potential becomes more negative. Consequently, the IIP (measuring charge) shifts toward higher pH as concentration increases, in the opposite direction from the IEP (measuring potential). © 2011 American Chemical Society

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

EPA Pesticide Factsheets

NMR fluid measurements of commonly used rat strains when subjected to SQ normotonic or hypertonic salines, as well as physiologic comparisons to sedentary and exercised subjects.This dataset is associated with the following publication:Gordon , C., P. Phillips , and A. Johnstone. A Noninvasive Method to Study Regulation of Extracellular Fluid Volume in Rats Using Nuclear Magnetic Resonance. American Journal of Physiology- Renal Physiology. American Physiological Society, Bethesda, MD, USA, 310(5): 426-31, (2016).

Sodium and Potassium Ions in Proteins and Enzyme Catalysis.

PubMed

Vašák, Milan; Schnabl, Joachim

2016-01-01

The group I alkali metal ions Na(+) and K(+) are ubiquitous components of biological fluids that surround biological macromolecules. They play important roles other than being nonspecific ionic buffering agents or mediators of solute exchange and transport. Molecular evolution and regulated high intracellular and extracellular M(+) concentrations led to incorporation of selective Na(+) and K(+) binding sites into enzymes to stabilize catalytic intermediates or to provide optimal positioning of substrates. The mechanism of M(+) activation, as derived from kinetic studies along with structural analysis, has led to the classification of cofactor-like (type I) or allosteric effector (type II) activated enzymes. In the type I mechanism substrate anchoring to the enzyme active site is mediated by M(+), often acting in tandem with a divalent cation like Mg(2+), Mn(2+) or Zn(2+). In the allosteric type II mechanism, M(+) binding enhances enzyme activity through conformational transitions triggered upon binding to a distant site. In this chapter, following the discussion of the coordination chemistry of Na(+) and K(+) ions and the structural features responsible for the metal binding site selectivity in M(+)-activated enzymes, well-defined examples of M(+)-activated enzymes are used to illustrate the structural basis for type I and type II activation by Na(+) and K(+).

Prolonged fasting increases the response of the renin-angiotensin-aldosterone system, but not vasopressin levels, in postweaned northern elephant seal pups

NASA Technical Reports Server (NTRS)

Ortiz, R. M.; Wade, C. E.; Ortiz, C. L.

2000-01-01

The 8- to 12-week postweaning fast exhibited by northern elephant seal pups (Mirounga angustirostris) occurs without any apparent deleterious effects on fluid and electrolyte homeostasis. However, during the fast the role of vasopressin (AVP) has been shown to be inconclusive and the involvement of the renin-angiotensin-aldosterone system (RAAS) has yet to be examined. To examine the effects of prolonged fasting on these osmoregulatory hormones, 15 postweaned pups were serially blood-sampled during the first 49 days of their fast. Fasting did not induce significant changes in ionic or osmotic concentrations, suggesting electrolyte homeostasis. Total proteins were reduced by day 21 of fasting and remained depressed, suggesting a lack of dehydration. Aldosterone and plasma renin activity exhibited a correlated, linear increase over the first 49 days of the fast, suggesting an active RAAS. Aldosterone exhibited a parabolic trend over the fast with a peak at day 35, suggesting a shift in the sensitivity of the kidney to aldosterone later in the fast. AVP was elevated at day 49 only, but concentrations were relatively low. RAAS was modified during the postweaning fast in pups and appears to play a significant role in the regulation of electrolyte and, most likely, water homeostasis during this period. Copyright 2000 Academic Press.

Mechanism of development of ionocytes rich in vacuolar-type H+-ATPase in the skin of zebrafish larvae

PubMed Central

Esaki, Masahiro; Hoshijima, Kazuyuki; Nakamura, Nobuhiro; Munakata, Keijiro; Tanaka, Mikiko; Ookata, Kayoko; Asakawa, Kazuhide; Kawakami, Koichi; Wang, Weiyi; Weinberg, Eric S.; Hirose, Shigehisa

2009-01-01

Mitochondrion-rich cells (MRCs), or ionocytes, play a central role in aquatic species, maintaining body fluid ionic homeostasis by actively taking up or excreting ions. Since their first description in 1932 in eel gills, extensive morphological and physiological analyses have yielded important insights into ionocyte structure and function, but understanding the developmental pathway specifying these cells remains an ongoing challenge. We previously succeeded in identifying a key transcription factor, Foxi3a, in zebrafish larvae by database mining. In the present study, we analyzed a zebrafish mutant, quadro (quo), deficient in foxi1 gene expression and found that foxi1 is essential for development of an MRC subpopulation rich in vacuolar-type H+-ATPase (vH-MRC). foxi1 acts upstream of Delta-Notch signaling that determines sporadic distribution of vH-MRC and regulates foxi3a expression. Through gain- and loss-of-function assays and cell transplantation experiments, we further clarified that (1) the expression level of foxi3a is maintained by a positive feedback loop between foxi3a and its downstream gene gcm2 and (2) Foxi3a functions cell-autonomously in the specification of vH-MRC. These observations provide a better understanding of the differentiation and distribution of the vH-MRC subtype. PMID:19268451

Modeling of charge transport in ion bipolar junction transistors.

PubMed

Volkov, Anton V; Tybrandt, Klas; Berggren, Magnus; Zozoulenko, Igor V

2014-06-17

Spatiotemporal control of the complex chemical microenvironment is of great importance to many fields within life science. One way to facilitate such control is to construct delivery circuits, comprising arrays of dispensing outlets, for ions and charged biomolecules based on ionic transistors. This allows for addressability of ionic signals, which opens up for spatiotemporally controlled delivery in a highly complex manner. One class of ionic transistors, the ion bipolar junction transistors (IBJTs), is especially attractive for these applications because these transistors are functional at physiological conditions and have been employed to modulate the delivery of neurotransmitters to regulate signaling in neuronal cells. Further, the first integrated complementary ionic circuits were recently developed on the basis of these ionic transistors. However, a detailed understanding of the device physics of these transistors is still lacking and hampers further development of components and circuits. Here, we report on the modeling of IBJTs using Poisson's and Nernst-Planck equations and the finite element method. A two-dimensional model of the device is employed that successfully reproduces the main characteristics of the measurement data. On the basis of the detailed concentration and potential profiles provided by the model, the different modes of operation of the transistor are analyzed as well as the transitions between the different modes. The model correctly predicts the measured threshold voltage, which is explained in terms of membrane potentials. All in all, the results provide the basis for a detailed understanding of IBJT operation. This new knowledge is employed to discuss potential improvements of ion bipolar junction transistors in terms of miniaturization and device parameters.

Regulation of body fluid and salt homeostasis--from observations in space to new concepts on Earth.

PubMed

Gerzer, R; Heer, M

2005-08-01

The present manuscript summarizes recent discoveries that were made by studying salt and fluid homeostasis in weightlessness. These data indicate that 1. atrial natriuretic peptide appears not to play an important role in natriuresis in physiology, 2. the distribution of body fluids appears to be tightly coupled with hunger and thirst regulation, 3. intrathoracic pressure may be an important co-regulator of body fluid homeostasis, 4. a so far unknown low-affinity, high capacity osmotically inactive sodium storage mechanism appears to be present in humans that is acting through sodium/hydrogen exchange on glycosaminoglycans and might explain the pathophysiology, e.g., of salt sensitive hypertension. The surprising and unexpected data underline that weightlessness is an excellent tool to investigate the physiology of our human body: If we knew it, we should be able to predict changes that occur when gravity is absent. But, as data from space demonstrate, we do not.

Changes in the Coherent Dynamics of Nanoconfined Room Temperature Ionic Liquids

NASA Astrophysics Data System (ADS)

Vallejo, Kevin; Cano, Melissa; Li, Song; Rotner, Gernot; Faraone, Antonio; Banuelos, Jose

Confinement and temperature effects on the coherent dynamics of the room temperature ionic liquid (RTIL) [C10MPy+] [Tf2N-] were investigated using neutron spin-echo (NSE) in two silica matrices with different pore size. Several intermolecular forces give rise to the bulk molecular structure between anions and cations. NSE provided dynamics (via the coherent intermediate scattering function) in the time range of 0.004 to 10 ns, and at Q-values corresponding to intermediate range ordering and inter- and intra-molecular length scales of the RTIL. Pore wall effects were delineated by comparing bulk RTIL dynamics with those of the confined fluid in 2.8 nm and 8 nm pores. Analytical models were applied to the experimental data to extract decay times and amplitudes of each component. We find a fast relaxation outside the experiment time window, a primary relaxation, and slow, surface-induced dynamics, which all speed up with increased temperature, however, the temperature dependence differs between bulk and confinement. This study sheds light on the structure and dynamics of RTILs and is relevant to the optimization of RTILs for green technologies and applications.

Design of Bioactive Organic-inorganic Hybrid Materials with Self-setting Ability

NASA Astrophysics Data System (ADS)

Miyazaki, T.; Machida, S.; Morita, Y.; Ishida, E.

2011-10-01

Paste-like materials with ability of self-setting are attractive for bone substitutes, since they can be injected from the small hole with minimized invasion to the patient. Although bone cements which set as apatite are clinically used, there is limitation on clinical applications due to their mechanical properties such as high brittleness and low fracture toughness. To overcome this problem, organic-inorganic hybrids based on a flexible polymer are attractive. We have obtained an idea for design of self-setting hybrids using polyion complex fabricated by ionic interaction of anionic and cationic polymers. We aimed at preparation of organic-inorganic hybrids exhibiting self-setting ability and bioactivity. The liquid component was prepared from cationic chitosan aqueous solution. The powder component was prepared by mixing various carrageenans with α-tricalcium phosphate (α-TCP). The obtained cements set within 1 day. Compressive strength showed tendency to increase with increase in α-TCP content in the powder component. The prepared cements formed the apatite in simulated body fluid within 3 days. Novel self-setting materials based on organic-inorganic hybrid can be designed utilizing ionic interaction of polysaccharide.

Sr, Mg cosubstituted HA porous macro-granules: potentialities as resorbable bone filler with antiosteoporotic functions.

PubMed

Landi, Elena; Uggeri, Jacopo; Medri, Valentina; Guizzardi, Stefano

2013-09-01

Porous macro-granules of nanostructured apatite with Ca ions partially cosubstituted with Mg and Sr ions in different ratios (SrMgHAs), were synthesized at 37°C and compared with Mg and/or Sr free apatites (MgHAs and HA). Strontium improved the Mg substitution extent in the apatite and the chemical-physical and thermal stability of the resulting cosubstituted apatite. Porous macro-granules of 400-600 micron with selected composition were tested for the ionic release in synthetic body fluid and the data were related with the results of preliminary cell investigation in vitro. As compared to the corresponding Sr-free granulate, the SrMgHA could be exploited to prolong the beneficial Mg release during the bone regeneration process. In addition the contemporary in situ supply of Sr, an antiosteoporotic and anticarie ion, could influence the quality of new hard tissues. The ionic multirelease created a more favorable environment for human osteoblasts, demonstrated by a proliferative effect for each dose tested in the range 0.1-10 mg/mL. Copyright © 2013 Wiley Periodicals, Inc.

Explaining the differential solubility of flue gas components in ionic liquids from first-principle calculations.

PubMed

Prasad, B Ram; Senapati, Sanjib

2009-04-09

Flue gas is greatly responsible for acid rain formation and global warming. New generation ionic liquids (ILs) have potential in controlling the flue gas emissions, as they acquire high absorptivity for the component gases SO(2), CO(2), etc. The association of the IL-gas interactions to the absorptivity of gas molecules in ILs is, however, poorly understood. In this paper, we present a molecular level description of the interactions of ILs with SO(2), CO(2), and N(2) and show its implications to the differential gas solubility. Our results indicate that the IL anion-gas interactions play a key role in deciding the gas solubility in ILs, particularly for polar gases such as SO(2). On the other hand, regular solution assumption applies to N(2) solubility. In accordance with the previous theoretical and experimental findings, our results also imply that the IL anions dominate the interactions with gas molecules while the cations play a secondary role and the underlying fluid structures of the ILs remain unperturbed by the addition of gas molecules.

Changes in the Molar Ellipticities of HEWL Observed by Circular Dichroism and Quantitated by Time Resolved Fluorescence Anisotropy Under Crystallizing Conditions

NASA Technical Reports Server (NTRS)

Sumida, John

2002-01-01

Fluid models for simple colloids predict that as the protein concentration is increased, crystallization should occur at some sufficiently high concentration regardless of the strength of attraction. However, empirical measurements do not fully support this assertion. Measurements of the second virial coefficient (B22) indicate that protein crystallization occurs only over a discrete range of solution parameters. Furthermore, observations of a strong correlation between protein solubility and B22, has led to an ongoing debate regarding the relationship between the two. Experimental work in our lab, using Hen Egg White Lysozyme (HEWL), previously revealed that the rotational anisotropy of the protein under crystallizing conditions changes systematically with pH, ionic strength and temperature. These observations are now supported by recent work revealing that small changes in the molar ellipticity also occur systematically with changes in ionic strength and temperature. This work demonstrates that under crystallization conditions, the protein native state is characterized by a conformational heterogeneity that may prove fundamental to the relationship between protein crystallization and protein solubility.

Transepithelial glucose transport and Na+/K+ homeostasis in enterocytes: an integrative model

PubMed Central

Drengstig, Tormod; Ruoff, Peter

2014-01-01

The uptake of glucose and the nutrient coupled transcellular sodium traffic across epithelial cells in the small intestine has been an ongoing topic in physiological research for over half a century. Driving the uptake of nutrients like glucose, enterocytes must have regulatory mechanisms that respond to the considerable changes in the inflow of sodium during absorption. The Na-K-ATPase membrane protein plays a major role in this regulation. We propose the hypothesis that the amount of active Na-K-ATPase in enterocytes is directly regulated by the concentration of intracellular Na+ and that this regulation together with a regulation of basolateral K permeability by intracellular ATP gives the enterocyte the ability to maintain ionic Na+/K+ homeostasis. To explore these regulatory mechanisms, we present a mathematical model of the sodium coupled uptake of glucose in epithelial enterocytes. Our model integrates knowledge about individual transporter proteins including apical SGLT1, basolateral Na-K-ATPase, and GLUT2, together with diffusion and membrane potentials. The intracellular concentrations of glucose, sodium, potassium, and chloride are modeled by nonlinear differential equations, and molecular flows are calculated based on experimental kinetic data from the literature, including substrate saturation, product inhibition, and modulation by membrane potential. Simulation results of the model without the addition of regulatory mechanisms fit well with published short-term observations, including cell depolarization and increased concentration of intracellular glucose and sodium during increased concentration of luminal glucose/sodium. Adding regulatory mechanisms for regulation of Na-K-ATPase and K permeability to the model show that our hypothesis predicts observed long-term ionic homeostasis. PMID:24898586

Entrainment Coefficient and Effective Mass for Conduction Neutrons in Neutron Star Crust:. Macroscopic Treatment

NASA Astrophysics Data System (ADS)

Carter, Brandon; Chamel, Nicolas; Haensel, Pawel

Phenomena such as pulsar frequency glitches are believed to be attributable to differential rotation of a current of "free" superfluid neutrons at densities above the "drip" threshold in the ionic crust of a neutron star. Such relative flow is shown to be locally describable by adaption of a canonical two-fluid treatment that emphasizes the role of the momentum covectors constructed by differentiation of action with respect to the currents, with allowance for stratification whereby the ionic number current may be conserved even when the ionic charge number Z is altered by beta processes. It is demonstrated that the gauge freedom to make different choices of the chemical basis determining which neutrons are counted as "free" does not affect their "superfluid" momentum covector, which must locally have the form of a gradient (though it does affect the "normal" momentum covector characterizing the protons and those neutrons that are considered to be "confined" in the nuclei). It is shown how the effect of "entrainment" (whereby the momentum directions deviate from those of the currents) is controlled by the (gauge-independent) mobility coefficient {K}, estimated in recent microscopical quantum mechanical investigations, which suggest that the corresponding (gauge-dependent) "effective mass" m⋆ of the free neutrons can become very large in some layers. The relation between this treatment of the crust layers and related work (using different definitions of "effective mass") intended for the deeper core layers is discussed.

Combination of Cyclodextrin and Ionic Liquid in Analytical Chemistry: Current and Future Perspectives.

PubMed

Hui, Boon Yih; Raoov, Muggundha; Zain, Nur Nadhirah Mohamad; Mohamad, Sharifah; Osman, Hasnah

2017-09-03

The growth in driving force and popularity of cyclodextrin (CDs) and ionic liquids (ILs) as promising materials in the field of analytical chemistry has resulted in an exponentially increase of their exploitation and production in analytical chemistry field. CDs belong to the family of cyclic oligosaccharides composing of α-(1,4) linked glucopyranose subunits and possess a cage-like supramolecular structure. This structure enables chemical reactions to proceed between interacting ions, radical or molecules in the absence of covalent bonds. Conversely, ILs are an ionic fluids comprising of only cation and anion often with immeasurable vapor pressure making them as green or designer solvent. The cooperative effect between CD and IL due to their fascinating properties, have nowadays contributed their footprints for a better development in analytical chemistry nowadays. This comprehensive review serves to give an overview on some of the recent studies and provides an analytical trend for the application of CDs with the combination of ILs that possess beneficial and remarkable effects in analytical chemistry including their use in various sample preparation techniques such as solid phase extraction, magnetic solid phase extraction, cloud point extraction, microextraction, and separation techniques which includes gas chromatography, high-performance liquid chromatography, capillary electrophoresis as well as applications of electrochemical sensors as electrode modifiers with references to recent applications. This review will highlight the nature of interactions and synergic effects between CDs, ILs, and analytes. It is hoped that this review will stimulate further research in analytical chemistry.

Crystal chemistry and the role of ionic radius in rare earth tetrasilicates: Ba2RE2Si4O12F2 (RE = Er3+-Lu3+) and Ba2RE2Si4O13 (RE = La3+-Ho3+).

PubMed

Fulle, Kyle; Sanjeewa, Liurukara D; McMillen, Colin D; Kolis, Joseph W

2017-10-01

Structural variations across a series of barium rare earth (RE) tetrasilicates are studied. Two different formulas are observed, namely those of a new cyclo-silicate fluoride, BaRE 2 Si 4 O 12 F 2 (RE = Er 3+ -Lu 3+ ) and new compounds in the Ba 2 RE 2 Si 4 O 13 (RE = La 3+ -Ho 3+ ) family, covering the whole range of ionic radii for the rare earth ions. The Ba 2 RE 2 Si 4 O 13 series is further subdivided into two polymorphs, also showing a dependence on rare earth ionic radius (space group P{\\overline 1} for La 3+ -Nd 3+ , and space group C2/c for Sm 3+ -Ho 3+ ). Two of the structure types identified are based on dinuclear rare earth units that differ in their crystal chemistries, particularly with respect to the role of fluorine as a structural director. The broad study of rare earth ions provides greater insight into understanding structural variations within silicate frameworks and the nature of f-block incorporation in oxyanion frameworks. The single crystals are grown from high-temperature (ca 953 K) hydrothermal fluids, demonstrating the versatility of the technique to access new phases containing recalcitrant rare earth oxides, enabling the study of structural trends.

Temperature regulated Brønsted acidic ionic liquid-catalyze esterification of oleic acid for biodiesel application

NASA Astrophysics Data System (ADS)

Rafiee, Ezzat; Mirnezami, Fakhrosadat

2017-02-01

By combining phosphotungstic acid (PW) and SO3H- functioned zwitterion, heteropoly anion-based Brønsted acidic ionic liquids (HPA-ILs) were successfully obtained. Scanning electron microscopy and energy dispersive X-ray spectroscopy were provided the morphology and composition of the prepared material. Catalytic performance and reusability of the catalysts were evaluated through an esterification reaction between oleic acid and methanol for production of biodiesel. Relationship between catalytic activities and acidity of the catalysts have been discussed by potentiometric titration. The results showed that HPA-ILs had good activity and reusability. HPA-ILs dissolved in the reaction mixture during the reaction process and could be precipitated and separated from products at lower temperature.

Micellar liquid chromatography

NASA Astrophysics Data System (ADS)

Basova, Elena M.; Ivanov, Vadim M.; Shpigun, Oleg A.

1999-12-01

Background and possibilities of practical applications of micellar liquid chromatography (MLC) are considered. Various retention models in MLC, the effects of the nature and concentration of surfactants and organic modifiers, pH, temperature and ionic strength on the MLC efficiency and selectivity are discussed. The advantages and limitations of MLC are demonstrated. The performance of MLC is critically evaluated in relationship to the reversed-phase HPLC and ion-pair chromatography. The potential of application of MLC for the analysis of pharmaceuticals including that in biological fluids and separation of inorganic anions, transition metal cations, metal chelates and heteropoly compounds is described. The bibliography includes 146 references.

Ceramic component for electrodes

DOEpatents

Marchant, David D.

1979-01-01

A ceramic component suitable for preparing MHD generator electrodes consists of HfO.sub.2 and sufficient Tb.sub.4 O.sub.7 to stabilize at least 60 volume percent of the HfO.sub.2 into the cubic structure. The ceramic component may also contain a small amount of PrO.sub.2, Yb.sub.2 O.sub.3 or a mixture of both to improve stability and electronic conductivity of the electrode. The component is highly resistant to corrosion by molten potassium seed and molten coal slag in the MHD fluid and exhibits both ionic and electronic conductivity.

A review of bioactive silicate ceramics.

PubMed

Wu, Chengtie; Chang, Jiang

2013-06-01

Silicate bioceramics, as a new family of biomaterials, have received significant attention in their application to hard tissue regeneration. Some silicate bioceramics have shown excellent apatite mineralization in simulated body fluids and their ionic products have been shown to enhance the proliferation, osteogenic differentiation and gene expression of stem cells. In this paper, we review the advances in the research of silicate system bioceramics, including preparation methods, mechanical strength, apatite mineralization, dissolution and in vitro and in vivo biological properties. The biological properties and the corresponding mechanism have been highlighted. A look forward to the application of silicate bioceramics to bone regeneration is further suggested.

Temperature responses of exercizing dogs to infusion of electrolytes

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Kozlowski, S.; Nazar, K.; Kaciuba-Uscilko, H.; Brzezinska, Z.

1974-01-01

The effect of infusions with solutions of various ionic and osmotic composition on exercise temperature responses was studied in dogs who do not regulate their temperature by sweating. The results suggest an association between plasma Na+ and Ca++ level within the normal physiological range and the control of body temperature during exercise.

Molecular Responses of the Spiral Ganglion to Aminoglycosides

ERIC Educational Resources Information Center

Balaban, Carey D.

2005-01-01

Aminoglycosides are toxic to both the inner ear hair cells and the ganglion cells that give rise to the eighth cranial nerve. According to recent studies, these cells have a repertoire of molecular responses to aminoglycoside exposure that engages multiple neuroprotective mechanisms. The responses appear to involve regulation of ionic homeostasis,…

Ionic liquids modified graphene oxide composites: a high efficient adsorbent for phthalates from aqueous solution

PubMed Central

Zhou, Xinguang; Zhang, Yinglu; Huang, Zuteng; Lu, Dingkun; Zhu, Anwei; Shi, Guoyue

2016-01-01

In 2015, more than 30% of erasers were found to contain a PAE content that exceeded the 0.1% limit established by the Quality and Technology Supervision Bureau of Jiangsu Province in China. Thus, strengthening the supervision and regulation of the PAE content in foods and supplies, in particular, remains necessary. Graphene oxide (GO) and its composites have drawn great interests as promising adsorbents for polar and nonpolar compounds. However, GO-based adsorbents are typically restricted by the difficult separation after treatment because of the high pressure in filtration and low density in centrifugation. Herein, a series of novel ionic liquids modified graphene oxide composites (GO-ILs) were prepared as adsorbents for phthalates (PAEs) in eraser samples, which overcame the conventional drawbacks. These novel composites have a combination of the high surface area of graphene oxide and the tunability of the ionic liquids. It is expected that the GO-ILs composites can be used as efficient adsorbents for PAEs from aqueous solution. This work also demonstrated a new technique for GO-based materials applied in sample preparation. PMID:27910926

Ionic liquids modified graphene oxide composites: a high efficient adsorbent for phthalates from aqueous solution

NASA Astrophysics Data System (ADS)

Zhou, Xinguang; Zhang, Yinglu; Huang, Zuteng; Lu, Dingkun; Zhu, Anwei; Shi, Guoyue

2016-12-01

In 2015, more than 30% of erasers were found to contain a PAE content that exceeded the 0.1% limit established by the Quality and Technology Supervision Bureau of Jiangsu Province in China. Thus, strengthening the supervision and regulation of the PAE content in foods and supplies, in particular, remains necessary. Graphene oxide (GO) and its composites have drawn great interests as promising adsorbents for polar and nonpolar compounds. However, GO-based adsorbents are typically restricted by the difficult separation after treatment because of the high pressure in filtration and low density in centrifugation. Herein, a series of novel ionic liquids modified graphene oxide composites (GO-ILs) were prepared as adsorbents for phthalates (PAEs) in eraser samples, which overcame the conventional drawbacks. These novel composites have a combination of the high surface area of graphene oxide and the tunability of the ionic liquids. It is expected that the GO-ILs composites can be used as efficient adsorbents for PAEs from aqueous solution. This work also demonstrated a new technique for GO-based materials applied in sample preparation.

Pharmacological and ionic characterizations of the muscarinic receptors modulating (/sup 3/H)acetylcholine release from rat cortical synaptosomes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, E.M.; Otero, D.H.

The muscarinic receptors that modulate acetylcholine release from rat cortical synaptosomes were characterized with respect to sensitivity to drugs that act selectively at M1 or M2 receptor subtypes, as well as to changes in ionic strength and membrane potential. The modulatory receptors appear to be of the M2 type, since they are activated by carbachol, acetylcholine, methacholine, oxotremorine, and bethanechol, but not by pilocarpine, and are blocked by atropine, scopolamine, and gallamine (at high concentrations), but not by pirenzepine or dicyclomine. The ED50S for carbachol, acetylcholine, and oxotremorine are less than 10 microM, suggesting that the high affinity state ofmore » the receptor is functional. High ionic strength induced by raising the NaCl concentration has no effect on agonist (oxotremorine) potency, but increases the efficacy of this compound, which disagrees with receptor-binding studies. On the other hand, depolarization with either KCl or with veratridine (20 microM) reduces agonist potencies by approximately an order of magnitude, suggesting a potential mechanism for receptor regulation.« less

The dual exo/endo-type mode and the effect of ionic strength on the mode of catalysis of chitinase 60 (CHI60) from Serratia sp. TU09 and its mutants.

PubMed

Kuttiyawong, K; Nakapong, S; Pichyangkura, R

2008-11-03

Mutations of the tryptophan residues in the tryptophan-track of the N-terminal domain (W33F/Y and W69F/Y) and in the catalytic domain (W245F/Y) of Serratia sp. TU09 Chitinase 60 (CHI60) were constructed, as single and double point substitutions to either phenylalanine or tyrosine. The enzyme-substrate interaction and mode of catalysis, exo/endo-type, of wild type CHI60 and mutant enzymes on soluble (partially N-acetylated chitin), amorphous (colloidal chitin), and crystalline (β-chitin) substrates were studied. All CHI60 mutants exhibited a reduced substrate binding activity on colloidal chitin. CHI60 possesses a dual mode of catalysis with both exo- and endo-type activities allowing the enzyme to work efficiently on various substrate types. CHI60 preferentially uses the endo-type mode on soluble and amorphous substrates and the exo-type mode on crystalline substrate. However, the prevalent mode of hydrolysis mediated by CHI60 is regulated by ionic strength. Slightly elevated ionic strength, 0.1-0.2M NaCl, which promotes enzyme-substrate interactions, enhances CHI60 hydrolytic activity on amorphous substrate and, interestingly, on partially N-acetylated chitin. High ionic strength, 0.5-2.0M NaCl, prevents the enzyme from dissociating from amorphous substrate, occupying the enzyme in an enzyme-substrate non-productive complex. However, on crystalline substrates, the activity of CHI60 was only inhibited approximately 50% at high ionic strength, suggesting that the enzyme hydrolyzes crystalline substrates with an exo-type mode processively while remaining tightly bound to the substrate. Moreover, substitution of Trp-33 to either phenylalanine or tyrosine reduced the activity of the enzyme at high ionic strength, suggesting an important role of Trp-33 on enzyme processivity.

Adsorption of polyelectrolyte-like proteins to silica surfaces and the impact of pH on the response to ionic strength. A Monte Carlo simulation and ellipsometry study.

PubMed

Hyltegren, Kristin; Skepö, Marie

2017-05-15

The adsorbed amount of the polyelectrolyte-like protein histatin 5 on a silica surface depends on the pH and the ionic strength of the solution. Interestingly, an increase in ionic strength affects the adsorbed amount differently depending on the pH of the solution, as shown by ellipsometry measurements (Hyltegren, 2016). We have tested the hypothesis that the same (qualitative) trends can be found also from a coarse-grained model that takes all charge-charge interactions into account within the frameworks of Gouy-Chapman and Debye-Hückel theories. Using the same coarse-grained model as in our previous Monte Carlo study of single protein adsorption (Hyltegren, 2016), simulations of systems with many histatin 5 molecules were performed and then compared with ellipsometry measurements. The strength of the short-ranged attractive interaction between the protein and the surface was varied. The coarse-grained model does not qualitatively reproduce the pH-dependence of the experimentally observed trends in adsorbed amount as a function of ionic strength. However, the simulations cast light on the balance between electrostatic attraction between protein and surface and electrostatic repulsion between adsorbed proteins, the deficiencies of the Langmuir isotherm, and the implications of protein charge regulation in concentrated systems. Copyright © 2017 Elsevier Inc. All rights reserved.

Ionic tethering contributes to the conformational stability and function of complement C3b.

PubMed

López-Perrote, Andrés; Harrison, Reed E S; Subías, Marta; Alcorlo, Martín; Rodríguez de Córdoba, Santiago; Morikis, Dimitrios; Llorca, Oscar

2017-05-01

C3b, the central component of the alternative pathway (AP) of the complement system, coexists as a mixture of conformations in solution. These conformational changes can affect interactions with other proteins and complement regulators. Here we combine a computational model for electrostatic interactions within C3b with molecular imaging to study the conformation of C3b. The computational analysis shows that the TED domain in C3b is tethered ionically to the macroglobulin (MG) ring. Monovalent counterion concentration affects the magnitude of electrostatic forces anchoring the TED domain to the rest of the C3b molecule in a thermodynamic model. This is confirmed by observing NaCl concentration dependent conformational changes using single molecule electron microscopy (EM). We show that the displacement of the TED domain is compatible with C3b binding to Factor B (FB), suggesting that the regulation of the C3bBb convertase could be affected by conditions that promote movement in the TED domain. Our molecular model also predicts mutations that could alter the positioning of the TED domain, including the common R102G polymorphism, a risk variant for developing age-related macular degeneration. The common C3b isoform, C3bS, and the risk isoform, C3bF, show distinct energetic barriers to displacement in the TED that are related to a network of electrostatic interactions at the interface of the TED and MG-ring domains of C3b. These computational predictions agree with experimental evidence that shows differences in conformation observed in C3b isoforms purified from homozygous donors. Altogether, we reveal an ionic, reversible attachment of the TED domain to the MG ring that may influence complement regulation in some mutations and polymorphisms of C3b. Copyright © 2016 Elsevier Ltd. All rights reserved.

Osmotic regulation of expression of two extracellular matrix-binding proteins and a haemolysin of Leptospira interrogans: differential effects on LigA and Sph2 extracellular release.

PubMed

Matsunaga, James; Medeiros, Marco A; Sanchez, Yolanda; Werneid, Kristian F; Ko, Albert I

2007-10-01

The life cycle of the pathogen Leptospira interrogans involves stages outside and inside the host. Entry of L. interrogans from moist environments into the host is likely to be accompanied by the induction of genes encoding virulence determinants and the concomitant repression of genes encoding products required for survival outside of the host. The expression of the adhesin LigA, the haemolysin Sph2 (Lk73.5) and the outer-membrane lipoprotein LipL36 of pathogenic Leptospira species have been reported to be regulated by mammalian host signals. A previous study demonstrated that raising the osmolarity of the leptospiral growth medium to physiological levels encountered in the host by addition of various salts enhanced the levels of cell-associated LigA and LigB and extracellular LigA. In this study, we systematically examined the effects of osmotic upshift with ionic and non-ionic solutes on expression of the known mammalian host-regulated leptospiral genes. The levels of cell-associated LigA, LigB and Sph2 increased at physiological osmolarity, whereas LipL36 levels decreased, corresponding to changes in specific transcript levels. These changes in expression occurred irrespective of whether sodium chloride or sucrose was used as the solute. The increase of cellular LigA, LigB and Sph2 protein levels occurred within hours of adding sodium chloride. Extracellular Sph2 levels increased when either sodium chloride or sucrose was added to achieve physiological osmolarity. In contrast, enhanced levels of extracellular LigA were observed only with an increase in ionic strength. These results indicate that the mechanisms for release of LigA and Sph2 differ during host infection. Thus, osmolarity not only affects leptospiral gene expression by affecting transcript levels of putative virulence determinants but also affects the release of such proteins into the surroundings.

Differential roles of two delayed rectifier potassium currents in regulation of ventricular action potential duration and arrhythmia susceptibility.

PubMed

Devenyi, Ryan A; Ortega, Francis A; Groenendaal, Willemijn; Krogh-Madsen, Trine; Christini, David J; Sobie, Eric A

2017-04-01

Arrhythmias result from disruptions to cardiac electrical activity, although the factors that control cellular action potentials are incompletely understood. We combined mathematical modelling with experiments in heart cells from guinea pigs to determine how cellular electrical activity is regulated. A mismatch between modelling predictions and the experimental results allowed us to construct an improved, more predictive mathematical model. The balance between two particular potassium currents dictates how heart cells respond to perturbations and their susceptibility to arrhythmias. Imbalances of ionic currents can destabilize the cardiac action potential and potentially trigger lethal cardiac arrhythmias. In the present study, we combined mathematical modelling with information-rich dynamic clamp experiments to determine the regulation of action potential morphology in guinea pig ventricular myocytes. Parameter sensitivity analysis was used to predict how changes in ionic currents alter action potential duration, and these were tested experimentally using dynamic clamp, a technique that allows for multiple perturbations to be tested in each cell. Surprisingly, we found that a leading mathematical model, developed with traditional approaches, systematically underestimated experimental responses to dynamic clamp perturbations. We then re-parameterized the model using a genetic algorithm, which allowed us to estimate ionic current levels in each of the cells studied. This unbiased model adjustment consistently predicted an increase in the rapid delayed rectifier K + current and a drastic decrease in the slow delayed rectifier K + current, and this prediction was validated experimentally. Subsequent simulations with the adjusted model generated the clinically relevant prediction that the slow delayed rectifier is better able to stabilize the action potential and suppress pro-arrhythmic events than the rapid delayed rectifier. In summary, iterative coupling of simulations and experiments enabled novel insight into how the balance between cardiac K + currents influences ventricular arrhythmia susceptibility. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

A Mussel-Derived One-Component Adhesive Coacervate

PubMed Central

Wei, Wei; Tan, Yerpeng; Rodriguez, N. Martinez; Yu, Jing; Israelachvili, Jacob N.; Waite, J. Herbert

2013-01-01

Marine organisms process and deliver many of their underwater coatings and adhesives as complex fluids. In marine mussels, one such fluid, secreted during the formation of adhesive plaques, consists of a concentrated colloidal suspension of a mussel foot protein (mfp) known as Mfp-3S. Results of this study suggest that Mfp-3S becomes a complex fluid by a liquid-liquid phase separation from equilibrium solution at a pH and ionic strength reminiscent of conditions created by the mussel foot during plaque formation. The pH dependence of phase separation and its sensitivity indicate that inter/intra-molecular electrostatic interactions are partially responsible for driving the phase separation. Hydrophobic interactions between the nonpolar Mfp-3S proteins provide another important driving force for coacervation. As complex coacervation typically results from charge-charge interactions between polyanions and polycations, Mfp-3S is thus unique in being the only known protein that coacervates with itself. The Mfp-3S coacervate was shown to have an effective interfacial energy of ≤ 1 mJ/m2 which explains its tendency to spread over or engulf most surfaces. Of particular interest to biomedical applications is the extremely high adsorption capacity of coacervated Mfp-3S on hydroxyapatite. PMID:24060881

New evidence on the health hazards and control of metalworking fluids since completion of the OSHA advisory committee report.

PubMed

Mirer, Franklin E

2010-08-01

Metalworking fluids (MWF) are used in the manufacture of engines, transmissions, chassis parts and other products. In 2003, OSHA denied a union petition to promulgate a standard for MWF. The 3rd Circuit Court of Appeals rejected a union lawsuit to compel OSHA to regulate MWF. OSHA relied exclusively on the 1999 Metal Working Fluids Standards Advisory Committee report, therefore, only evidence available before 1999 was quoted supporting the denial. This review was conducted to identify studies published since 1998. Electronic reference sources were queried for the terms for metalworking fluids, machining fluids, cutting fluids, cutting oils, coolants, machining, and machinist. All items returned were reviewed for relevance to MWF regulation. The review noted 227 reports in the peer reviewed literature directly relevant to regulation of MWF exposures. Of these, 26 addressed cancer; 58 respiratory effects; 32 skin effects or absorption; 45 microbial contaminants; and 76 exposure measurements and controls. Three major studies identified excess cancer including lung, liver, pancreatic, laryngeal, and leukemia associated with MWF exposures. Reports strengthened associations of asthma and hypersensitivity pneumonitis with recent exposure to MWF. Material new evidence demonstrates significant risks to material impairment of health at prevailing exposure levels and feasibility of lower exposure limits. Copyright 2010 Wiley-Liss, Inc.

Laser microprobe analyses of Cl, Br, I, and K in fluid inclusions: Implications for sources of salinity in some ancient hydrothermal fluids

USGS Publications Warehouse

Böhlke, J.K.; Irwin, J.J.

1992-01-01

The relative concentrations of Cl, Br, I, and K in fluid inclusions in hydrothermal minerals were measured by laser microprobe noble gas mass spectrometry on irradiated samples containing 10−10 to 10−8 L of fluid. Distinctive halogen signatures indicate contrasting sources of fluid salinity in fluid inclusions from representative “magmatic” (St. Austell), “metamorphic” (Alleghany), and “geothermal” (Creede, Salton Sea) aqueous systems. Br/Cl mol ratios are lowest at Salton Sea (0.27–0.33 × 10−3), where high salinities are largely due to halite dissolution; intermediate at St. Austell (0.85 × 10−3), possibly representative of magmatic volatiles; and highest (near that of seawater) at Creede (1.5–2.1 × 10−3) and Alleghany (1.2–2.4 × 10−3), where dissolved halogens probably were leached from volcanic and (or) nonevaporitic sedimentary rocks. IC1">IC1 mol ratios are lowest (near that of seawater) at Creede (1–14 × 10−6), possibly because organisms scavenged I during low temperature recharge; intermediate at Salton Sea (24–26 × 10−6) and St. Austell (81× 10−6); and highest at Alleghany (320–940 × 10−6), probably because the fluids interacted with organic-rich sediments at high temperatures before being trapped. KCl">KCl mol ratios indicate disequilibrium with respect to hypothetical feldspathic alkali-Al-silicate mineral buffers at fluid inclusion trapping temperatures at Creede, and large contributions of (Na, K)-bicarbonate to total fluid ionic strength at Alleghany. Significant variations in Cl/Br/I/K ratios among different fluid inclusion types are correlated with previously documented mineralization stages at Creede, and with the apparent oxidation state of dissolved carbon at Alleghany. The new data indicate that Cl/ Br/I ratios in hydrothermal fluid inclusions vary by several orders of magnitude, as they do in modern surface and ground waters. This study demonstrates that halogen signatures of fluid inclusions determined by microanalysis yield important information about sources of fluid salinity and provide excellent definition of fluid reservoirs and tracers of flow and interaction in ancient hydrothermal systems.

The solvent at antigen-binding site regulated C3d-CR2 interactions through the C-terminal tail of C3d at different ion strengths: insights from molecular dynamics simulation.

PubMed

Zhang, Yan; Guo, Jingjing; Li, Lanlan; Liu, Xuewei; Yao, Xiaojun; Liu, Huanxiang

2016-10-01

The interactions of complement receptor 2 (CR2) and the degradation fragment C3d of complement component C3 play important links between the innate and adaptive immune systems. Due to the importance of C3d-CR2 interaction in the design of vaccines and inhibitors, a number of studies have been performed to investigate C3d-CR2 interaction. Many studies have indicated C3d-CR2 interactions are ionic strength-dependent. To investigate the molecular mechanism of C3d-CR2 interaction and the origin of effects of ionic strength, molecular dynamics simulations for C3d-CR2 complex together with the energetic and structural analysis were performed. Our results revealed the increased interactions between charged protein and ions weaken C3d-CR2 association, as ionic strengths increase. Moreover, ion strengths have similar effects on antigen-binding site and CR2 binding site. Meanwhile, Ala17 and Gln20 will transform between the activated and non-activated states mediated by His133 and Glu135 at different ion strengths. Our results reveal the origins of the effects of ionic strengths on C3d-CR2 interactions are due to the changes of water, ion occupancies and distributions. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. Copyright © 2016 Elsevier B.V. All rights reserved.

Efficient production of free fatty acids from ionic liquid-based acid- or enzyme-catalyzed bamboo hydrolysate.

PubMed

Mi, Le; Qin, Dandan; Cheng, Jie; Wang, Dan; Li, Sha; Wei, Xuetuan

2017-03-01

Two engineered Escherichia coli strains, DQ101 (MG1655 fadD - )/pDQTES and DQ101 (MG1655 fadD - )/pDQTESZ were constructed to investigate the free fatty acid production using ionic liquid-based acid- or enzyme-catalyzed bamboo hydrolysate as carbon source in this study. The plasmid, pDQTES, carrying an acyl-ACP thioesterase 'TesA of E. coli in pTrc99A was constructed firstly, and then (3R)-hydroxyacyl-ACP dehydratase was ligated after the TesA to give the plasmid pDQTESZ. These two strains exhibited efficient fatty acid production when glucose was used as the sole carbon source, with a final concentration of 2.45 and 3.32 g/L, respectively. The free fatty acid production of the two strains on xylose is not as efficient as that on glucose, which was 2.32 and 2.96 g/L, respectively. For mixed sugars, DQ101 (MG1655 fadD - )-based strains utilized glucose and pentose sequentially under the carbon catabolite repression (CCR) regulation. The highest total FFAs concentration from the mixed sugar culture reached 2.81 g/L by DQ101 (MG1655 fadD - )/pDQTESZ. Furthermore, when ionic liquid-based enzyme-catalyzed bamboo hydrolysate was used as the carbon source, the strain DQ101 (MG1655 fadD - )/pDQTESZ could produce 1.23 g/L FFAs with a yield of 0.13 g/g, and while it just produced 0.65 g/L free fatty acid with the ionic liquid-based acid-catalyzed bamboo hydrolysate as the feedstock. The results suggested that enzymatic catalyzed bamboo hydrolysate with ionic liquid pretreatment could serve as an efficient feedstock for free fatty acid production.

Effect of Rehydration Fluid Osmolality on Plasma Volume and Vasopressin in Resting Dehydrated Men

NASA Technical Reports Server (NTRS)

Geelen, Ghislaine; Greenleaf, J. E.; Keil, L. C.; Wade, Charles E. (Technical Monitor)

1994-01-01

Elevated plasma vasopressin concentration [PVP], which may act as a dipsogen, decreases promptly following the ingestion of fluids in many mammals including humans. The purpose for this study was to determine whether fluids of varied electrolyte and carbohydrate composition and osmolality (Osm] would modify post-drinking decreases in [PVP] which could be attributed to interaction with plasma volume (PV)- or fluid-electrolyte interactive hormones. Five men (23-41 yr, 78.0 +/- SD 8.2 kg), water deprived for 24 h, drank six fluids (12 ml/kg, at 16.5C in 4.0-6.2 min): water (30 m0sm/kg), NaCl (70 mOsm/kg), NaCl + NaCitrate (270 mOsm/kg), NaCl + 9.7% glucose (650 mOsm/kg), and two commercial drinks containing various ionic and carbohydrate contents (380 and 390 mOsm/kg). Blood (20 ml/sample) was drawn at -5 min before and at +3, +9, +15, +30, and +70 min after drinking. Heart rate, blood pressures, and plasma renin activity, {Na+], [K+], [Osm], aldosterone, atrial natriuretic peptide, and epinephrine concentrations were unchanged after drinking. Post-drinking [PVP] decreased from 1.7 - 3.7 pg/ml within 3 min with all fluids independently of their composition, [Osm], or delta PV; with maximal depression to 0.1-0.7 pg/ml (p<0.05) by 15 min. The continued [PVP] depression with all fluids from 15 to 70 min was accompanied by unchanged plasma (Osm] but 1.8-7.6% increases (p<0.05) in PV with 3) fluids (2 commercial and NaCitrate) and no change with the others. Percent changes in mean [PVP] and plasma norepinephrine concentrations [PNE] at 15 min correlated -0.70 (P<0.10) suggesting that about half the variability in [PVP I I depression was associated with [PNE]. Thus, part of the mechanism for post-drinking [PVP] depression may involve a drinking stimulated norepinephrine (neural) factor.

Miscibility and Speciation in the Water/carbon Dioxide System

NASA Astrophysics Data System (ADS)

Abramson, E.; Bollengier, O.; Brown, J. M.

2017-12-01

We have been exploring fluid-fluid solubilities and speciation in mixed systems of CO2-H2O. Fluid-fluid immiscibility extends to the highest pressures and temperatures yet explored (7 GPa, 700K). In this region, commonly used COH fluid models agree neither with the data nor among themselves. The range of immiscibility is extended by addition of NaCl, but miscibility limits determined in preliminary experiments are not as expected from extrapolation of lower pressure (<0.2 GPa) results. For majority-water systems (XCO2<0.5) an abrupt increase of solubility with pressure is linked to an observed change in speciation as CO2(aq) reacts with water. The identity of the newly formed species is, as of the writing of this abstract, unknown, but presumed to be either H2CO3 or HCO3-. A reasonable match between the observed equilibria and an application of HKF theory suggests that the new species is, indeed, HCO3-, but with a Raman frequency shifted from that found in the dilute aqueous solution. Application of HKF theory to the CO2(f)-CO2(aq) equilibrium suffers from an incompatibility of the usual formulation of the theory with known molar volumes of CO2(f) at higher pressures. On the basis of these studies we conclude that models of CO2-H2O fluids must take into account major changes in speciation, and that simple equations-of-state, of a few fitted parameters, will not afford an adequate description of such fluids. "First principles" models, tested against real data, seem more likely to yield the desired results. This statement extends as well to the calculation of the dielectric constants of these mixed fluids, the basis of ionic solution chemistry. Further, semi-empirical formulations of solution thermodynamics, which function well at pressures of kbars, ought to be re-worked for use over larger pressure ranges.

Volume versus wiring transmission in the brain: a new theoretical frame for neuropsychopharmacology.

PubMed

Agnati, L F; Bjelke, B; Fuxe, K

1995-01-01

A volume transmission mode of communication in brain was implicit already in the early work of Golgi, who postulated the existence of electrical signals in the extracellular fluid (ECF) based on Volta's "wet conductor" made by solutions. The term volume transmission is taken from the term volume conduction describing the flow of ionic currents in the ECF as a basis for the electrocorticogram. The slow VT mode includes also chemical signals and is opposed to the fast synaptic (wiring) transmission. Every neuron may function in a dual mode, the synaptic and the volume transmission mode, when considering the autocrine and synaptic classes of communication. The paracrine- and neuroendocrine-like classes only involve the VT mode in the latter case including the CSF as a route. The chemical signals for VT are the neuropeptides, but also the classical transmitters, the monoamines, acetylcholine, GABA, and glutamate can participate, when they operate via slow, high affinity G protein coupled receptors. Ions such as K+, Ca++, and H+ also function as VT signals. The hypothesis is also introduced that CO2 can act as a multifacit long-distance VT and WT regulator besides being part of the CO2/HCO3 buffer. CO2 via regulating NMDA receptor sensitivity can also regulate NO formation, which represents a paracrine and fast VT signal. The therapy of CNS disorders is also discussed in the frame of the wiring and VT concept. Two therapeutical approaches can therefore be developed, one based on increasing WT and one based on increasing VT. In contrast to the WT therapy, which must preserve the electrotemporal code, the VT therapy can operate also with postsynaptic agonists. Therefore, a therapeutic effect with such a drug indicates that the deficiency in the communication process operates via VT. In view of the lack of very effective negative feedbacks in VT vs. WT, VT therapy may produce less tolerance and drug dependency.

Alkalosis increases muscle K+ release, but lowers plasma [K+] and delays fatigue during dynamic forearm exercise

PubMed Central

Sostaric, Simon M; Skinner, Sandford L; Brown, Malcolm J; Sangkabutra, Termboon; Medved, Ivan; Medley, Tanya; Selig, Steve E; Fairweather, Ian; Rutar, Danny; McKenna, Michael J

2006-01-01

Alkalosis enhances human exercise performance, and reduces K+ loss in contracting rat muscle. We investigated alkalosis effects on K+ regulation, ionic regulation and fatigue during intense exercise in nine untrained volunteers. Concentric finger flexions were conducted at 75% peak work rate (∼3 W) until fatigue, under alkalosis (Alk, NaHCO3, 0.3 g kg−1) and control (Con, CaCO3) conditions, 1 month apart in a randomised, double-blind, crossover design. Deep antecubital venous (v) and radial arterial (a) blood was drawn at rest, during exercise and recovery, to determine arterio-venous differences for electrolytes, fluid shifts, acid–base and gas exchange. Finger flexion exercise barely perturbed arterial plasma ions and acid–base status, but induced marked arterio-venous changes. Alk elevated [HCO3−] and PCO2, and lowered [H+] (P < 0.05). Time to fatigue increased substantially during Alk (25 ± 8%, P < 0.05), whilst both [K+]a and [K+]v were reduced (P < 0.01) and [K+]a-v during exercise tended to be greater (P= 0.056, n = 8). Muscle K+ efflux at fatigue was greater in Alk (21.2 ± 7.6 µmol min−1, 32 ± 7%, P < 0.05, n = 6), but peak K+ uptake rate was elevated during recovery (15 ± 7%, P < 0.05) suggesting increased muscle Na+,K+-ATPase activity. Alk induced greater [Na+]a, [Cl−]v, muscle Cl− influx and muscle lactate concentration ([Lac−]) efflux during exercise and recovery (P < 0.05). The lower circulating [K+] and greater muscle K+ uptake, Na+ delivery and Cl− uptake with Alk, are all consistent with preservation of membrane excitability during exercise. This suggests that lesser exercise-induced membrane depolarization may be an important mechanism underlying enhanced exercise performance with Alk. Thus Alk was associated with improved regulation of K+, Na+, Cl− and Lac−. PMID:16239279

Chemical association in simple models of molecular and ionic fluids. III. The cavity function

NASA Astrophysics Data System (ADS)

Zhou, Yaoqi; Stell, George

1992-01-01

Exact equations which relate the cavity function to excess solvation free energies and equilibrium association constants are rederived by using a thermodynamic cycle. A zeroth-order approximation, derived previously by us as a simple interpolation scheme, is found to be very accurate if the associative bonding occurs on or near the surface of the repulsive core of the interaction potential. If the bonding radius is substantially less than the core radius, the approximation overestimates the association degree and the association constant. For binary association, the zeroth-order approximation is equivalent to the first-order thermodynamic perturbation theory (TPT) of Wertheim. For n-particle association, the combination of the zeroth-order approximation with a ``linear'' approximation (for n-particle distribution functions in terms of the two-particle function) yields the first-order TPT result. Using our exact equations to go beyond TPT, near-exact analytic results for binary hard-sphere association are obtained. Solvent effects on binary hard-sphere association and ionic association are also investigated. A new rule which generalizes Le Chatelier's principle is used to describe the three distinct forms of behaviors involving solvent effects that we find. The replacement of the dielectric-continuum solvent model by a dipolar hard-sphere model leads to improved agreement with an experimental observation. Finally, equation of state for an n-particle flexible linear-chain fluid is derived on the basis of a one-parameter approximation that interpolates between the generalized Kirkwood superposition approximation and the linear approximation. A value of the parameter that appears to be near optimal in the context of this application is obtained from comparison with computer-simulation data.

Sperm motility in fishes. (II) Effects of ions and osmolality: a review.

PubMed

Alavi, Sayyed Mohammad Hadi; Cosson, Jacky

2006-01-01

The spermatozoa of most fish species are immotile in the testis and seminal plasma. Therefore, motility is induced after the spermatozoa are released into the aqueous environment during natural reproduction or into the diluent during artificial reproduction. There are clear relationships between seminal plasma composition and osmolality and the duration of fish sperm motility. Various parameters such as ion concentrations (K+, Na+, and Ca2+), osmotic pressure, pH, temperature and dilution rate affect motility. In the present paper, we review the roles of these ions on sperm motility in Salmonidae, Cyprinidae, Acipenseridae and marine fishes, and their relationship with seminal plasma composition. Results in the literature show that: 1. K+ is a key ion controlling sperm motility in Salmonidae and Acipenseridae in combination with osmotic pressure; this control is more simple in other fish species: sperm motility is prevented when the osmotic pressure is high (Cyprinidae) or low (marine fishes) compared to that of the seminal fluid. 2. Cations (mostly divalent, such as Ca2+) are antagonistic with the inhibitory effect of K+ on sperm motility. 3. In many species, Ca2+ influx and K+ or Na+ efflux through specific ionic channels change the membrane potential and eventually lead to an increase in cAMP concentration in the cell, which constitutes the initiation signal for sperm motility in Salmonidae. 4. Media that are hyper- and hypo-osmotic relative to seminal fluid trigger sperm motility in marine and freshwater fishes, respectively. 5. The motility of fish spermatozoa is controlled through their sensitivity to osmolality and ion concentrations. This phenomenon is related to ionic channel activities in the membrane and governs the motility mechanisms of axonemes.

Proceedings of the First Joint NASA Cardiopulmonary Workshop

NASA Technical Reports Server (NTRS)

Fortney, Suzanne M. (Editor); Hargens, Alan R. (Editor)

1991-01-01

The topics covered include the following: flight echocardiography, pulmonary function, central hemodynamics, glycerol hyperhydration, spectral analysis, lower body negative pressure countermeasures, orthostatic tolerance, autonomic function, cardiac deconditioning, fluid and renal responses to head-down tilt, local fluid regulation, endocrine regulation during bed rest, autogenic feedback, and chronic cardiovascular measurements. The program ended with a general discussion of weightlessness models and countermeasures.

Uranium(VI) Binding Forms in Selected Human Body Fluids: Thermodynamic Calculations versus Spectroscopic Measurements.

PubMed

Osman, Alfatih A A; Geipel, Gerhard; Barkleit, Astrid; Bernhard, Gert

2015-02-16

Human exposure to uranium increasingly becomes a subject of interest in many scientific disciplines such as environmental medicine, toxicology, and radiation protection. Knowledge about uranium chemical binding forms(speciation) in human body fluids can be of great importance to understand not only its biokinetics but also its relevance in risk assessment and in designing decorporation therapy in the case of accidental overexposure. In this study, thermodynamic calculations of uranium speciation in relevant simulated and original body fluids were compared with spectroscopic data after ex-situ uranium addition. For the first time, experimental data on U(VI) speciation in body fluids (saliva, sweat, urine) was obtained by means of cryogenic time-resolved laser-induced fluorescence spectroscopy (cryo-TRLFS) at 153 K. By using the time dependency of fluorescence decay and the band positions of the emission spectra, various uranyl complexes were demonstrated in the studied samples. The variations of the body fluids in terms of chemical composition, pH, and ionic strength resulted in different binding forms of U(VI). The speciation of U(VI) in saliva and in urine was affected by the presence of bioorganic ligands, whereas in sweat, the distribution depends mainly on inorganic ligands. We also elucidated the role of biological buffers, i.e., phosphate (H(2)PO(4−)/HPO(4)(2−)) on U(VI) distribution, and the system Ca(2+)/UO(2)(2+)/PO(4)(3−) was discussed in detail in both saliva and urine. The theoretical speciation calculations of the main U(VI) species in the investigated body fluids were significantly consistent with the spectroscopic data. Laser fluorescence spectroscopy showed success and reliability for direct determination of U(VI) in such biological matrices with the possibility for further improvement.

Modeling the nanoscale viscoelasticity of fluids by bridging non-Markovian fluctuating hydrodynamics and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Voulgarakis, Nikolaos K.; Satish, Siddarth; Chu, Jhih-Wei

2009-12-01

A multiscale computational method is developed to model the nanoscale viscoelasticity of fluids by bridging non-Markovian fluctuating hydrodynamics (FHD) and molecular dynamics (MD) simulations. To capture the elastic responses that emerge at small length scales, we attach an additional rheological model parallel to the macroscopic constitutive equation of a fluid. The widely used linear Maxwell model is employed as a working choice; other models can be used as well. For a fluid that is Newtonian in the macroscopic limit, this approach results in a parallel Newtonian-Maxwell model. For water, argon, and an ionic liquid, the power spectrum of momentum field autocorrelation functions of the parallel Newtonian-Maxwell model agrees very well with those calculated from all-atom MD simulations. To incorporate thermal fluctuations, we generalize the equations of FHD to work with non-Markovian rheological models and colored noise. The fluctuating stress tensor (white noise) is integrated in time in the same manner as its dissipative counterpart and numerical simulations indicate that this approach accurately preserves the set temperature in a FHD simulation. By mapping position and velocity vectors in the molecular representation onto field variables, we bridge the non-Markovian FHD with atomistic MD simulations. Through this mapping, we quantitatively determine the transport coefficients of the parallel Newtonian-Maxwell model for water and argon from all-atom MD simulations. For both fluids, a significant enhancement in elastic responses is observed as the wave number of hydrodynamic modes is reduced to a few nanometers. The mapping from particle to field representations and the perturbative strategy of developing constitutive equations provide a useful framework for modeling the nanoscale viscoelasticity of fluids.

7 CFR 1030.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1030.15 Section 1030.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.15 Fluid milk product. See § 1000.15. ...

7 CFR 1032.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1032.15 Section 1032.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.15 Fluid milk product. See § 1000.15. ...

7 CFR 1001.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1001.15 Section 1001.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating Handling Definitions § 1001.15 Fluid milk product. See § 1000.15. ...

7 CFR 1131.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1131.15 Section 1131.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.15 Fluid milk product. See § 1000.15. ...

7 CFR 1033.15 - Fluid milk products.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk products. 1033.15 Section 1033.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.15 Fluid milk products. See § 1000.15. ...

7 CFR 1126.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1126.15 Section 1126.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.15 Fluid milk product. See § 1000.15. ...

7 CFR 1006.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1006.15 Section 1006.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.15 Fluid milk product. See § 1000.15. ...

7 CFR 1006.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1006.15 Section 1006.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.15 Fluid milk product. See § 1000.15. ...

7 CFR 1030.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1030.15 Section 1030.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.15 Fluid milk product. See § 1000.15. ...

7 CFR 1124.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1124.15 Section 1124.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.15 Fluid milk product. See § 1000.15. ...

7 CFR 1030.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1030.15 Section 1030.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.15 Fluid milk product. See § 1000.15. ...

7 CFR 1006.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1006.15 Section 1006.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.15 Fluid milk product. See § 1000.15. ...

7 CFR 1007.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1007.15 Section 1007.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.15 Fluid milk product. See § 1000.15. ...

7 CFR 1005.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1005.15 Section 1005.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.15 Fluid milk product. See § 1000.15. ...

7 CFR 1007.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1007.15 Section 1007.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.15 Fluid milk product. See § 1000.15. ...

7 CFR 1005.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1005.15 Section 1005.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.15 Fluid milk product. See § 1000.15. ...

7 CFR 1032.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1032.15 Section 1032.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.15 Fluid milk product. See § 1000.15. ...

7 CFR 1001.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1001.15 Section 1001.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating Handling Definitions § 1001.15 Fluid milk product. See § 1000.15. ...

7 CFR 1032.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1032.15 Section 1032.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.15 Fluid milk product. See § 1000.15. ...

7 CFR 1126.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1126.15 Section 1126.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.15 Fluid milk product. See § 1000.15. ...

7 CFR 1005.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1005.15 Section 1005.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.15 Fluid milk product. See § 1000.15. ...

7 CFR 1001.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1001.15 Section 1001.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating Handling Definitions § 1001.15 Fluid milk product. See § 1000.15. ...

7 CFR 1007.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1007.15 Section 1007.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.15 Fluid milk product. See § 1000.15. ...

7 CFR 1124.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1124.15 Section 1124.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.15 Fluid milk product. See § 1000.15. ...

7 CFR 1124.15 - Fluid milk product.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk product. 1124.15 Section 1124.15 Agriculture... AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.15 Fluid milk product. See § 1000.15. ...

7 CFR 1033.15 - Fluid milk products.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk products. 1033.15 Section 1033.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.15 Fluid milk products. See § 1000.15. ...

7 CFR 1126.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1126.15 Section 1126.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.15 Fluid milk product. See § 1000.15. ...

7 CFR 1033.15 - Fluid milk products.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 9 2014-01-01 2013-01-01 true Fluid milk products. 1033.15 Section 1033.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.15 Fluid milk products. See § 1000.15. ...

7 CFR 1131.15 - Fluid milk product.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 9 2012-01-01 2012-01-01 false Fluid milk product. 1131.15 Section 1131.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.15 Fluid milk product. See § 1000.15. ...

7 CFR 1131.15 - Fluid milk product.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 9 2013-01-01 2013-01-01 false Fluid milk product. 1131.15 Section 1131.15... AGREEMENTS AND ORDERS; MILK), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.15 Fluid milk product. See § 1000.15. ...

7 CFR 1005.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1005.15 Section 1005.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.15 Fluid milk product. See § 1000.15. ...

7 CFR 1124.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1124.15 Section 1124.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.15 Fluid milk product. See § 1000.15. ...

7 CFR 1033.15 - Fluid milk products.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk products. 1033.15 Section 1033.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.15 Fluid milk products. See § 1000.15. ...

7 CFR 1030.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1030.15 Section 1030.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.15 Fluid milk product. See § 1000.15. ...

7 CFR 1005.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1005.15 Section 1005.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.15 Fluid milk product. See § 1000.15. ...

7 CFR 1006.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1006.15 Section 1006.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.15 Fluid milk product. See § 1000.15. ...

7 CFR 1030.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1030.15 Section 1030.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.15 Fluid milk product. See § 1000.15. ...

7 CFR 1126.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1126.15 Section 1126.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.15 Fluid milk product. See § 1000.15. ...

7 CFR 1131.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1131.15 Section 1131.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.15 Fluid milk product. See § 1000.15. ...

7 CFR 1007.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1007.15 Section 1007.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.15 Fluid milk product. See § 1000.15. ...

7 CFR 1033.15 - Fluid milk products.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk products. 1033.15 Section 1033.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.15 Fluid milk products. See § 1000.15. ...

7 CFR 1006.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1006.15 Section 1006.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.15 Fluid milk product. See § 1000.15. ...

7 CFR 1032.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1032.15 Section 1032.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.15 Fluid milk product. See § 1000.15. ...

7 CFR 1131.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1131.15 Section 1131.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.15 Fluid milk product. See § 1000.15. ...

7 CFR 1007.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1007.15 Section 1007.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.15 Fluid milk product. See § 1000.15. ...

7 CFR 1126.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1126.15 Section 1126.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.15 Fluid milk product. See § 1000.15. ...

7 CFR 1032.15 - Fluid milk product.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Fluid milk product. 1032.15 Section 1032.15 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.15 Fluid milk product. See § 1000.15. ...

7 CFR 1124.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1124.15 Section 1124.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.15 Fluid milk product. See § 1000.15. ...

7 CFR 1001.15 - Fluid milk product.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 9 2011-01-01 2011-01-01 false Fluid milk product. 1001.15 Section 1001.15... Agreements and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating Handling Definitions § 1001.15 Fluid milk product. See § 1000.15. ...

Hormonal regulation of fluid and electrolytes during prolonged bed rest - Implications for microgravity

NASA Technical Reports Server (NTRS)

Greenleaf, John E.

1989-01-01

The results of studies on the physiological changes of body fluids and electrolytes during bed rest with and without exercise training are overviewed to determine the effect of exercise and to assess the role of hormonal regulation in fluid-electrolyte responses to hypogravity. Special attention is given to fluid shifts observed in spacecraft personnel during space missions. It is concluded that, despite an apparent uncoupling of prominent hormonal interactions during bed-rest deconditioning (and, possibly, during microgravity), the exercise-training-induced hypervolemia helps to counter the hypohydrostatic-induced dehydration. Thus, it was found that, after nearly a year of spaceflight during which one cosmonaut exercised for about 4 hr per day, the water balance and physiological functioning were not disturbed significantly.

Electrolytes and thermoregulation

NASA Technical Reports Server (NTRS)

Nielsen, B.; Greenleaf, J. E.

1977-01-01

The influence of ions on temperature is studied for cases where the changes in ionic concentrations are induced by direct infusion or injection of electrolyte solutions into the cerebral ventricles or into specific areas of brain tissue; intravenous infusion or injection; eating food or drinking solutions of different ionic composition; and heat or exercise dehydration. It is shown that introduction of Na(+) and Ca(++) into the cerebral ventricles or into the venous system affects temperature regulation. It appears that the specific action of these ions is different from their osmotic effects. It is unlikely that their action is localized to the thermoregulatory centers in the brain. The infusion experiments demonstrate that the changes in sodium balance occurring during exercise and heat stress are large enough to affect sweat gland function and vasomotor activity.

CXCL16 contributes to neutrophil recruitment to cerebrospinal fluid in pneumococcal meningitis.

PubMed

Woehrl, Bianca; Klein, Matthias; Rupprecht, Tobias A; Schmetzer, Helga; Angele, Barbara; Häcker, Hans; Häcker, Georg; Pfister, Hans-Walter; Koedel, Uwe

2010-11-01

In this study, we analyzed the expression and function of CXCL16 in pneumococcal meningitis. CXCL16 was found to be up‐regulated in RAW264.7 macrophages (but not in neutrophils and endothelial cells) upon pneumococcal stimulation, in the cerebrospinal fluid of patients, and in the brains as well as the cerebrospinal fluid of mice with pneumococcal meningitis. CXCL16 up‐regulation in vivo was dependent on Toll‐like receptor (TLR) 2/TLR4 and MyD88 signaling. Neutralization of CXCL16 in animals before intracisternal pneumococcal infection (using anti‐CXCL16 antibodies) resulted in reduced cerebrospinal fluid pleocytosis. In vitro, murine neutrophils expressed the CXCL16 receptor CXCR6 and showed dose‐dependant migration toward a CXCL16 gradient. Thus, this study implicates CXCL16 as an additional neutrophil chemoattractant in cerebrospinal fluid in early pneumococcal meningitis.

Genetic defects disrupting glial ion and water homeostasis in the brain.

PubMed

Min, Rogier; van der Knaap, Marjo S

2018-05-01

Electrical activity of neurons in the brain, caused by the movement of ions between intracellular and extracellular compartments, is the basis of all our thoughts and actions. Maintaining the correct ionic concentration gradients is therefore crucial for brain functioning. Ion fluxes are accompanied by the displacement of osmotically obliged water. Since even minor brain swelling leads to severe brain damage and even death, brain ion and water movement has to be tightly regulated. Glial cells, in particular astrocytes, play a key role in ion and water homeostasis. They are endowed with specific channels, pumps and carriers to regulate ion and water flow. Glial cells form a large panglial syncytium to aid the uptake and dispersal of ions and water, and make extensive contacts with brain fluid barriers for disposal of excess ions and water. Genetic defects in glial proteins involved in ion and water homeostasis disrupt brain functioning, thereby leading to neurological diseases. Since white matter edema is often a hallmark disease feature, many of these diseases are characterized as leukodystrophies. In this review we summarize our current understanding of inherited glial diseases characterized by disturbed brain ion and water homeostasis by integrating findings from MRI, genetics, neuropathology and animal models for disease. We discuss how mutations in different glial proteins lead to disease, and highlight the similarities and differences between these diseases. To come to effective therapies for this group of diseases, a better mechanistic understanding of how glial cells shape ion and water movement in the brain is crucial. © 2018 The Authors. Brain Pathology published by John Wiley & Sons Ltd on behalf of International Society of Neuropathology.

Expanding the range of free calcium regulation in biological solutions.

PubMed

Dweck, David; Reyes-Alfonso, Avelino; Potter, James D

2005-12-15

Many biological systems use ethylene glycol bis (beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) to regulate the free calcium concentration ([Ca(2+)](free)) in the presence of physiological levels of free Mg(2+) ([Mg(2+)](free)). Frequently, it is necessary to work at [Ca(2+)](free) beyond EGTA's buffering capabilities. Therefore, we have developed methods to extend the buffering range by adding nitrilotriacetic acid (NTA) to solutions containing EGTA. This extension results from NTA having a lower K'(dCa) than EGTA. Such equilibria are solved by pCa Calculator, a computer program designed to aid in the study of Ca(2+)-dependent physiological processes while accounting for the effects of pH, temperature, and ionic strength. With multiple chelators and pH buffers from which to choose, pCa Calculator calculates the total concentration of each species required to achieve specified free concentrations of Ca(2+), ATP, and Mg(2+). The program is intuitive, user-friendly, and flexible enough to fix or vary the [Mg-ATP(2-)] and ionic strength. Moreover, it can account for increases in experimental volume from calcium addition. A comparative analysis is reported for testing solutions in the presence and absence of NTA by measuring the calcium binding affinity of fluorescent cardiac troponin C. These findings demonstrate that EGTA, when used in conjunction with NTA, improves and expands the regulation of free calcium in solution.

ATP: a vasoactive signal in the pericyte-containing microvasculature of the rat retina

PubMed Central

Kawamura, Hajime; Sugiyama, Tetsuya; Wu, David M; Kobayashi, Masato; Yamanishi, Shigeki; Katsumura, Kozo; Puro, Donald G

2003-01-01

In this study we tested the hypothesis that extracellular ATP regulates the function of the pericyte-containing retinal microvessels. Pericytes, which are more numerous in the retina than in any other tissue, are abluminally located cells that may adjust capillary perfusion by contracting and relaxing. At present, knowledge of the vasoactive molecules that regulate pericyte function is limited. Here, we focused on the actions of extracellular ATP because this nucleotide is a putative glial-to-vascular signal, as well as being a substance released by activated platelets and injured cells. In microvessels freshly isolated from the adult rat retina, we monitored ionic currents via perforated-patch pipettes, measured intracellular calcium levels with the use of fura-2, and visualized microvascular contractions with the aid of time-lapse photography. We found that ATP induced depolarizing changes in the ionic currents, increased calcium levels and caused pericytes to contract. P2X7 receptors and UTP-activated receptors mediated these effects. Consistent with ATP serving as a vasoconstrictor for the pericyte-containing microvasculature of the retina, the microvascular lumen narrowed when an adjacent pericyte contracted. In addition, the sustained activation of P2X7 receptors inhibited cell-to-cell electrotonic transmission within the microvascular networks. Thus, ATP not only affects the contractility of individual pericytes, but also appears to regulate the spatial and temporal dynamics of the vasomotor response. PMID:12876212

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

2012-08-02

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 agreement with the experimental data shows the excellent ability of the soft-SAFT EoS to describe the thermophysical properties of ILs as well as their phase behavior. Results prove that this equation of state can be a valuable tool to assist the design of ILs (in what concerns cation and anion selection) in order to obtain ILs with the desired properties and, consequently, enhancing their potential industrial applications.

Liquid metal batteries - materials selection and fluid dynamics

NASA Astrophysics Data System (ADS)

Weier, T.; Bund, A.; El-Mofid, W.; Horstmann, G. M.; Lalau, C.-C.; Landgraf, S.; Nimtz, M.; Starace, M.; Stefani, F.; Weber, N.

2017-07-01

Liquid metal batteries are possible candidates for massive and economically feasible large-scale stationary storage and as such could be key components of future energy systems based mainly or exclusively on intermittent renewable electricity sources. The completely liquid interior of liquid metal batteries and the high current densities give rise to a multitude of fluid flow phenomena that will primarily influence the operation of future large cells, but might be important for today’s smaller cells as well. The paper at hand starts with a discussion of the relative merits of using molten salts or ionic liquids as electrolytes for liquid metal cells and touches the choice of electrode materials. This excursus into electrochemistry is followed by an overview of investigations on magnetohydrodynamic instabilities in liquid metal batteries, namely the Tayler instability and electromagnetically excited gravity waves. A section on electro-vortex flows complements the discussion of flow phenomena. Focus of the flow related investigations lies on the integrity of the electrolyte layer and related critical parameters.

Applying electric field to charged and polar particles between metallic plates: extension of the Ewald method.

PubMed

Takae, Kyohei; Onuki, Akira

2013-09-28

We develop an efficient Ewald method of molecular dynamics simulation for calculating the electrostatic interactions among charged and polar particles between parallel metallic plates, where we may apply an electric field with an arbitrary size. We use the fact that the potential from the surface charges is equivalent to the sum of those from image charges and dipoles located outside the cell. We present simulation results on boundary effects of charged and polar fluids, formation of ionic crystals, and formation of dipole chains, where the applied field and the image interaction are crucial. For polar fluids, we find a large deviation of the classical Lorentz-field relation between the local field and the applied field due to pair correlations along the applied field. As general aspects, we clarify the difference between the potential-fixed and the charge-fixed boundary conditions and examine the relationship between the discrete particle description and the continuum electrostatics.

Dynamic self-organization of confined autophoretic particles

NASA Astrophysics Data System (ADS)

Medrano, Anthony; Michelin, Sébastien; Kanso, Eva

2016-11-01

We study the behavior of chemically-active Janus particles in microfluidic Hele-Shaw-type confinement. These micron-scale chemical motors, when immersed in a fuel-laden fluid, produce an ionic chemical field which leads to motility and consequently a local fluid flow. In unconfined settings, experimental and computational studies have shown these particles to spontaneously self-organize into crystal structures, and form into asters of two or more particles. Here, we show that geometric confinement alters both the chemical and hydrodynamic signature of the particles in such a way that their far-field effects can be modeled as source dipoles. Each particle moves according to its own self-propelled motion and in response to the chemical and hydrodynamic field created by other particles. Two interaction modes are observed: self-assembly into quasi-static crystals and into dynamically-evolving chains. We discuss the conditions that lead to these modes of interactions and the phase transitions between them for various Janus particle concentrations. The National GEM Consortium.

Endocrine, electrolyte, and fluid volume changes associated with Apollo missions

NASA Technical Reports Server (NTRS)

Leach, C. S.; Alexander, W. C.; Johnson, P. C.

1975-01-01

The endocrine and metabolic results obtained before and after the Apollo missions and the results of the limited in-flight sampling are summarized and discussed. The studies were designed to evaluate the biochemical changes in the returning Apollo crewmembers, and the areas studied included balance of fluids and electrolytes, regulation of calcium metabolism, adaptation to the environment, and regulation of metabolic processes.

Phosphorylation and Ionic Strength Alter the LRAP-HAP Interface in the N-terminus

PubMed Central

Lu, Jun-xia; Xu, Yimin Sharon; Shaw, Wendy J.

2013-01-01

The conditions present during enamel crystallite development change dramatically as a function of time, including the pH, protein concentration, surface type and ionic strength. In this work, we investigate the role that two of these changing conditions, pH and ionic strength, have in modulating the interaction of the amelogenin, LRAP, with hydroxyapatite (HAP). Using solid state NMR dipolar recoupling and chemical shift data, we investigate the structure, orientation and dynamics of three regions in the N-terminus of the protein, L15 to V19, V19 to L23 and K24 to S28. These regions are also near the only phosphorylated residue in the protein, pS16, therefore, changes in the LRAP-HAP interaction as a function of phosphorylation (LRAP(−P) vs. LRAP(+P)) were also investigated. All of the regions and conditions studied for the surface immobilized proteins showed restricted motion, with indications of slightly more mobility under all conditions for L15(+P) and K24(−P). The structure and orientation of the LRAP-HAP interaction in the N-terminus of the phosphorylated protein is very stable to changing solution conditions. From REDOR dipolar recoupling data, the structure and orientation in the region L15V19(−P) did not change significantly as a function of pH or ionic strength. The structure and orientation of the region V19L23(+P) were also stable to changes in pH, with the only significant change observed at high ionic strength, where the region becomes extended, suggesting this may be an important region in regulating mineral development. Chemical shift studies also suggest minimal changes in all three regions studied for both LRAP(−P) and LRAP(+P) as a function of pH or ionic strength and reveal that K24 has multiple resolvable resonance, suggestive of two coexisting structures. Phosphorylation also alters the LRAP-HAP interface. All of the three residues investigated (L15, V19, and K24) are closer to the surface in LRAP(+P), but K24S28 also changes structure as a result of phosphorylation, from a random coil to a largely helical structure, and V19L23 becomes more extended at high ionic strength when phosphorylated. These observations suggest that ionic strength and dephosphorylation may provide switching mechanisms to trigger a change in the function of the N-terminus. PMID:23477367

Thermoacoustic Contrast of Prostate Cancer due to Heating by Very High Frequency Irradiation

PubMed Central

Hull, D; Thomas, M; Griep, SK; Jacobsohn, K; See, WA

2015-01-01

Applying the thermoacoustic (TA) effect to diagnostic imaging was first proposed in the 1980s. The object under test is irradiated by high-power pulses of electromagnetic energy, which heat tissue and cause thermal expansion. Outgoing TA pressure pulses are detected by ultrasound transducers and reconstructed to provide images of the object. The TA contrast mechanism is strongly dependent upon the frequency of the irradiating electromagnetic pulse. When very high frequency (VHF) electromagnetic irradiation is utilized, TA signal production is driven by ionic content. Prostatic fluids contain high levels of ionic metabolites, including citrate, zinc, calcium, and magnesium. Healthy prostate glands produce more ionic metabolites than diseased glands. VHF pulses are therefore expected to generate stronger TA signal in healthy prostate glands than in diseased glands. A benchtop system for performing ex vivo thermoacoustic computed tomography with VHF energy is described and images are presented. The system utilizes irradiation pulses of 700 ns duration exceeding 20 kW power. Reconstructions frequently visualize anatomic landmarks such as the urethra and verumontanum. TA reconstructions from three freshly excised human prostate glands with little, moderate, and severe cancerous involvement are compared with histology. TA signal strength is negatively correlated with percent cancerous involvement in this small sample size. For the 45 regions of interest analyzed, a reconstruction value of 0.4 mV provides 100% sensitivity but only 29% specificity. This sample size is far too small to draw sweeping conclusions, but the results warrant a larger volume study including comparison of TA images to the gold standard, histology. PMID:25554968

Thermoacoustic contrast of prostate cancer due to heating by very high frequency irradiation.

PubMed

Patch, S K; Hull, D; Thomas, M; Griep, S K; Jacobsohn, K; See, W A

2015-01-21

Applying the thermoacoustic (TA) effect to diagnostic imaging was first proposed in the 1980s. The object under test is irradiated by high-power pulses of electromagnetic energy, which heat tissue and cause thermal expansion. Outgoing TA pressure pulses are detected by ultrasound transducers and reconstructed to provide images of the object. The TA contrast mechanism is strongly dependent upon the frequency of the irradiating electromagnetic pulse. When very high frequency (VHF) electromagnetic irradiation is utilized, TA signal production is driven by ionic content. Prostatic fluids contain high levels of ionic metabolites, including citrate, zinc, calcium, and magnesium. Healthy prostate glands produce more ionic metabolites than diseased glands. VHF pulses are therefore expected to generate stronger TA signal in healthy prostate glands than in diseased glands. A benchtop system for performing ex vivo TA computed tomography with VHF energy is described and images are presented. The system utilizes irradiation pulses of 700 ns duration exceeding 20 kW power. Reconstructions frequently visualize anatomic landmarks such as the urethra and verumontanum. TA reconstructions from three freshly excised human prostate glands with little, moderate, and severe cancerous involvement are compared with histology. TA signal strength is negatively correlated with percent cancerous involvement in this small sample size. For the 45 regions of interest analyzed, a reconstruction value of 0.4 mV provides 100% sensitivity but only 29% specificity. This sample size is far too small to draw sweeping conclusions, but the results warrant a larger volume study including comparison of TA images to the gold standard, histology.

Understanding the role of brine ionic composition on oil recovery by assessment of wettability from colloidal forces.

PubMed

Alshakhs, Mohammed J; Kovscek, Anthony R

2016-07-01

The impact of injection brine salinity and ionic composition on oil recovery has been an active area of research for the past 25years. Evidence from laboratory studies and field tests suggests that implementing certain modifications to the ionic composition of the injection brine leads to greater oil recovery. The role of salinity modification is attributed to its ability to shift wettability of a rock surface toward water wetness. The amount of trapped oil released depends on the nature of rock, oil, and brine surface interactions. Reservoir rocks exhibit different affinities to fluids. Carbonates show stronger adsorption of oil films as opposed to the strongly water-wet and mixed-wet sandstones. The concentration of divalent ions and total salinity of the injection brine are other important factors to consider. Accordingly, this paper provides a review of laboratory and field studies of the role of brine composition on oil recovery from carbonaceous rock as well as rationalization of results using DLVO (Derjaguin, Landau, Verwey and Overbeek) theory of surface forces. DLVO evaluates the contribution of each component of the oil/brine/rock system to the wettability. Measuring zeta potential of each pair of surfaces by a charged particle suspension method is used to estimate double layer forces, disjoining pressure, and contact-angle. We demonstrate the applicability of the DLVO approach by showing a comprehensive experimental study that investigates the effect of divalent ions in carbonates, and uses disjoining pressure results to rationalize observations from core flooding and direct contact-angle measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

In Situ Local Contact Angle Measurement in a CO2-Brine-Sand System Using Microfocused X-ray CT.

PubMed

Lv, Pengfei; Liu, Yu; Wang, Zhe; Liu, Shuyang; Jiang, Lanlan; Chen, Junlin; Song, Yongchen

2017-04-11

The wettability of porous media is of major interest in a broad range of natural and engineering applications. The wettability of a fluid on a solid surface is usually evaluated by the contact angle between them. While in situ local contact angle measurements are complicated by the topology of porous media, which can make it difficult to use traditional methods, recent advances in microfocused X-ray computed tomography (micro-CT) and image processing techniques have made it possible to measure contact angles on the scale of the pore sizes in such media. However, the effects of ionic strength, CO 2 phase, and flow pattern (drainage or imbibition) on pore-scale contact angle distribution are still not clear and have not been reported in detail in previous studies. In this study, we employed a micro-CT scanner for in situ investigation of local contact angles in a CO 2 -brine-sand system under various conditions. The effects of ionic strength, CO 2 phase, and flow pattern on the local contact-angle distribution were examined in detail. The results showed that the local contact angles vary over a wide range as a result of the interaction of surface contaminants, roughness, pore topology, and capillarity. The wettability of a porous surface could thus slowly weaken with increasing ionic strength, and the average contact angle could significantly increase when gaseous CO 2 (gCO 2 ) turns into supercritical CO 2 (scCO 2 ). Contact angle hysteresis also occurred between drainage and imbibition procedures, and the hysteresis was more significant under gCO 2 condition.

The interaction of a model active pharmaceutical with cationic surfactant and the subsequent design of drug based ionic liquid surfactants.

PubMed

Qamar, Sara; Brown, Paul; Ferguson, Steven; Khan, Rafaqat Ali; Ismail, Bushra; Khan, Abdur Rahman; Sayed, Murtaza; Khan, Asad Muhammad

2016-11-01

Interactions of active pharmaceutical ingredients (API) with surfactants remain an important research area due to the need to improve drug delivery systems. In this study, UV-Visible spectrophotometry was used to investigate the interactions between a model low molecular weight hydrophilic drug sodium valproate (SV) and cationic surfactant cetyltrimethylammonium bromide (CTAB). Changes in the spectra of SV were observed in pre- and post-micellar concentrations of CTAB. The binding constant (Kb) values and the number of drug molecules encapsulated per micelle were calculated, which posed the possibility of mixed micelle formation and strong complexation between SV and CTAB. These results were compared to those of a novel room temperature surface active ionic liquid, which was synthesized by the removal of inorganic counterions from a 1:1 mixture of CTAB and SV. In this new compound the drug now constitutes a building block of the carrier and, as such, has considerably different surfactant properties to its building blocks. In addition, enhanced solubility in a range of solvents, including simulated gastric fluid, was observed. The study provides valuable experimental evidence concerning the performance of drug based surfactant ionic liquids and how their chemical manipulation, without altering the architecture of the API, leads to control of surfactant behavior and physicochemical properties. In turn, this should feed through to improved and controlled drug release rates and delivery mechanisms, and the prevention of precipitation or formation of polymorphs typical of crystalline form APIs. Copyright © 2016 Elsevier Inc. All rights reserved.

Temperature control system for a J-module heat exchanger

DOEpatents

Basdekas, Demetrios L.; Macrae, George; Walsh, Joseph M.

1978-01-01

The level of primary fluid is controlled to change the effective heat transfer area of a heat exchanger utilized in a liquid metal nuclear power plant to eliminate the need for liquid metal control valves to regulate the flow of primary fluid and the temperature of the effluent secondary fluid.

[Relationship between the ionic composition of blood and urine and the salinity of the external environment of the crab Hemigrapsus sanguineus].

PubMed

Busev, V M; Semen'kov, P G; Mishchenko, T Ia

1977-01-01

Studies have been made on the dependence of sodium, potassium, magnesium and calcium concentrations of the blood and urine on the salinity of the external milieu in the crab H. sanguineus. Effective regulation of sodium and potasssium balance at low salinities was found. Within the salinity range investigated, magnesium level in the blood is maintained at lower level as compared to that in the environment. At low salinities, regulation of potassium and sodium concentrations in the blood is monitored by extrarenal mechanisms. Uber high salinity conditions, regulation of magnesium and potassium concentrations in the blood is accomplished at the expense of the activity of antennal glands. Calcium concentration in the blood is regulated by extra-renal mechanisms. The antennal glands affect regulation of calcium balance.

Production of xanthan gum from a chemically defined medium introduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weisrock, W.P.; Klein, H.S.

1983-02-22

Heteropolysaccharides produced by the action of Xanthomonas bacteria on carbohydrate media have a potential application as film forming agents, as thickeners in oil field drilling fluids and fracturing liquids and as emulsifying, stabilizing, and sizing agents. Heteropolysaccharides, particularly, xanthan gum, have a significant potential as mobility control agents in micellar polymer flooding. Xanthan gum has excellent viscosifying properties at low concentration, is resistant to shear degradation and exhibits only minimal losses in viscosity as a function of temperature, pH, and ionic strength. For these reasons, xanthan gum is an attractive alternative to synthetic polyacrylamides for enhanced oil recovery operations. 15more » claims.« less

Solvents and sustainable chemistry

PubMed Central

Welton, Tom

2015-01-01

Solvents are widely recognized to be of great environmental concern. The reduction of their use is one of the most important aims of green chemistry. In addition to this, the appropriate selection of solvent for a process can greatly improve the sustainability of a chemical production process. There has also been extensive research into the application of so-called green solvents, such as ionic liquids and supercritical fluids. However, most examples of solvent technologies that give improved sustainability come from the application of well-established solvents. It is also apparent that the successful implementation of environmentally sustainable processes must be accompanied by improvements in commercial performance. PMID:26730217

Translocation of single-stranded DNA through single-walled carbon nanotubes.

PubMed

Liu, Haitao; He, Jin; Tang, Jinyao; Liu, Hao; Pang, Pei; Cao, Di; Krstic, Predrag; Joseph, Sony; Lindsay, Stuart; Nuckolls, Colin

2010-01-01

We report the fabrication of devices in which one single-walled carbon nanotube spans a barrier between two fluid reservoirs, enabling direct electrical measurement of ion transport through the tube. A fraction of the tubes pass anomalously high ionic currents. Electrophoretic transport of small single-stranded DNA oligomers through these tubes is marked by large transient increases in ion current and was confirmed by polymerase chain reaction analysis. Each current pulse contains about 10(7) charges, an enormous amplification of the translocated charge. Carbon nanotubes simplify the construction of nanopores, permit new types of electrical measurements, and may open avenues for control of DNA translocation.

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. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Recovery of rhythmic activity in a central pattern generator: analysis of the role of neuromodulator and activity-dependent mechanisms.

PubMed

Zhang, Yili; Golowasch, Jorge

2011-11-01

The pyloric network of decapods crustaceans can undergo dramatic rhythmic activity changes. Under normal conditions the network generates low frequency rhythmic activity that depends obligatorily on the presence of neuromodulatory input from the central nervous system. When this input is removed (decentralization) the rhythmic activity ceases. In the continued absence of this input, periodic activity resumes after a few hours in the form of episodic bursting across the entire network that later turns into stable rhythmic activity that is nearly indistinguishable from control (recovery). It has been proposed that an activity-dependent modification of ionic conductance levels in the pyloric pacemaker neuron drives the process of recovery of activity. Previous modeling attempts have captured some aspects of the temporal changes observed experimentally, but key features could not be reproduced. Here we examined a model in which slow activity-dependent regulation of ionic conductances and slower neuromodulator-dependent regulation of intracellular Ca(2+) concentration reproduce all the temporal features of this recovery. Key aspects of these two regulatory mechanisms are their independence and their different kinetics. We also examined the role of variability (noise) in the activity-dependent regulation pathway and observe that it can help to reduce unrealistic constraints that were otherwise required on the neuromodulator-dependent pathway. We conclude that small variations in intracellular Ca(2+) concentration, a Ca(2+) uptake regulation mechanism that is directly targeted by neuromodulator-activated signaling pathways, and variability in the Ca(2+) concentration sensing signaling pathway can account for the observed changes in neuronal activity. Our conclusions are all amenable to experimental analysis.

Study of pH-responsive microgels containing methacrylic acid: effects of particle composition and added calcium.

PubMed

Dalmont, Helene; Pinprayoon, Orawan; Saunders, Brian R

2008-03-18

pH-responsive microgel dispersions contain cross-linked polymer particles that swell when the pH approaches the pKa of the ionic monomer incorporated within the particles. In recent work from our group, it was demonstrated that the mechanical properties of degenerated intervertebral discs (IVDs) could be restored to normal values by injection of pH-responsive microgel dispersions (Saunders, J. M.; Tong, T.; LeMaitre, C.; Freemont, A. J.; Saunders, B. R. Soft Matter 2007, 3, 486). These dispersions change from a fluid to a gel with increasing pH. The present work investigates the pH-dependent properties of dispersions of microgel particles containing MAA (methacrylic acid) and also the effects of added Ca2+. Two microgels are discussed: microgel A is poly(EA/MAA/AM) (EA and AM are ethyl acrylate and allyl methacrylate), and microgel B is poly(EA/MAA/BDDA) (butanediol diacrylate). The pH-dependent particle properties investigated include hydrodynamic diameters and electrophoretic mobilities. The critical coagulation concentrations (CCC) of dilute dispersions and the elastic modulus (G') of concentrated, gelled microgel dispersions were also investigated. In the absence of added Ca2+, the particle swelling and G' were smallest and largest, respectively, for microgel A. The changes in hydrodynamic diameter and mobility with pH were explained in terms of a core-shell swelling mechanism. Added Ca2+ was found to significantly decrease the CCCs, extents of particle swelling, and magnitude of the electrophoretic mobility. This was attributed to the ionic cross-linking of neighboring RCOO- groups by Ca2+. It is suggested that the formation of ionic cross-links is inefficient within the microgel particles because of the presence of covalent cross-links that oppose the large-scale conformational rearrangement of neighboring RCOO- groups. The effect of Ca2+ on the properties of the gelled dispersions is important from the viewpoint of potential application in vivo. Rheological studies of the gelled microgel dispersions showed that added Ca2+ did not have a specific influence on G'. The differences observed in the presence of Ca2+ were attributed to ionic strength effects (screening). The key parameter that controls G' of the gelled microgel dispersions is pH. The results from this work suggest that the elasticity of the gels would be slightly reduced in vivo as a consequence of the high ionic strength present.

A review of the consequences of fluid and electrolyte shifts in weightlessness

NASA Technical Reports Server (NTRS)

Leach, C. S.

1979-01-01

This review describes the renal-endocrine mechanisms related to the early losses of fluid-electrolytes from the body during weightlessness as well as their contribution to longer term adaptation of fluid-electrolyte balance. The hypotheses presented were generated by a systematic analysis of body fluid and renal dynamics observed under conditions of actual and simulated spaceflight. These have increased our understanding of the effects of acute headward fluid shifts on renal excretion, the factors promoting excess sodium excretion and the regulation of extracellular fluid composition.

A review of the consequences of fluid and electrolyte shifts in weightlessness

NASA Technical Reports Server (NTRS)

Leach, C. S.

1978-01-01

This review describes the renal-endocrine mechanisms related to the early losses of fluid-electrolytes from the body during weightlessness as well as their contribution to longer term adaptation of fluid-electrolyte balance. The hypotheses presented were generated by a systematic analysis of body fluid and renal dynamics observed under conditions of actual and simulated spaceflight. These have increased our understanding of the effects of acute headward fluid shifts on renal excretion, the factors promoting excess sodium excretion and the regulation of extracellular fluid composition.

[MK-801 or DNQX reduces electroconvulsive shock-induced impairment of learning-memory and hyperphosphorylation of Tau in rats].

PubMed

Liu, Chao; Min, Su; Wei, Ke; Liu, Dong; Dong, Jun; Luo, Jie; Liu, Xiao-Bin

2012-08-25

This study explored the effect of the excitatory amino acid receptor antagonists on the impairment of learning-memory and the hyperphosphorylation of Tau protein induced by electroconvulsive shock (ECT) in depressed rats, in order to provide experimental evidence for the study on neuropsychological mechanisms improving learning and memory impairment and the clinical intervention treatment. The analysis of variance of factorial design set up two intervention factors which were the electroconvulsive shock (two level: no disposition; a course of ECT) and the excitatory amino acid receptor antagonists (three level: iv saline; iv NMDA receptor antagonist MK-801; iv AMPA receptor antagonist DNQX). Forty-eight adult Wistar-Kyoto (WKY) rats (an animal model for depressive behavior) were randomly divided into six experimental groups (n = 8 in each group): saline (iv 2 mL saline through the tail veins of WKY rats ); MK-801 (iv 2 mL 5 mg/kg MK-801 through the tail veins of WKY rats) ; DNQX (iv 2 mL 5 mg/kg DNQX through the tail veins of WKY rats ); saline + ECT (iv 2 mL saline through the tail veins of WKY rats and giving a course of ECT); MK-801 + ECT (iv 2 mL 5 mg/kg MK-801 through the tail veins of WKY rats and giving a course of ECT); DNQX + ECT (iv 2 mL 5 mg/kg DNQX through the tail veins of WKY rats and giving a course of ECT). The Morris water maze test started within 1 day after the finish of the course of ECT to evaluate learning and memory. The hippocampus was removed from rats within 1 day after the finish of Morris water maze test. The content of glutamate in the hippocampus of rats was detected by high performance liquid chromatography. The contents of Tau protein which included Tau5 (total Tau protein), p-PHF1(Ser396/404), p-AT8(Ser199/202) and p-12E8(Ser262) in the hippocampus of rats were detected by immunohistochemistry staining (SP) and Western blot. The results showed that ECT and the glutamate ionic receptor blockers (NMDA receptor antagonist MK-801 and AMPA receptor antagonist DNQX) induced the impairment of learning and memory in depressed rats with extended evasive latency time and shortened space exploration time. And the two factors presented a subtractive effect. ECT significantly up-regulated the content of glutamate in the hippocampus of depressed rats which were not affected by the glutamate ionic receptor blockers. ECT and the glutamate ionic receptor blockers did not affect the total Tau protein in the hippocampus of rats. ECT up-regulated the hyperphosphorylation of Tau protein in the hippocampus of depressed rats, while the glutamate ionic receptor blockers down-regulated it, and combination of the two factors presented a subtractive effect. Our results indicate that ECT up-regulates the content of glutamate in the hippocampus of depressed rats, which up-regulates the hyperphosphorylation of Tau protein resulting in the impairment of learning and memory in depressed rats.

The use of a combination of different MR methods to study swelling of hydrophilic xanthan matrix tablets at different pHs.

PubMed

Mikac, U; Sepe, A; Kristl, J; Baumgartner, I

2012-01-01

Modified-release matrix tablets have been extensively used by the pharmaceutical industry as one of the most successful oral drug-delivery systems. The key element in drug release from hydrophilic matrix tablets is the gel layer that regulates the penetration of water and controls drug dissolution and diffusion. Magnetic resonance imaging (MRI) is a powerful, non-invasive technique that can help improve our understanding of the gel layer formed on swellable, polymer-matrix tablets, as well as the layer's properties and its influence on the drug release. The aim was to investigate the effects of pH and ionic strength on swelling and to study the influence of structural changes in xanthan gel on drug release. For this purpose a combination of different MRI methods for accurate determination of penetration, swelling and erosion fronts was used. The position of the penetration and swelling fronts were the same, independently of the different xanthan gel structures formed under different conditions of pH and ionic strength. The position of the erosion front, on the other hand, is strongly dependent on pH and ionic strength, as reflected in different thicknesses of the gel layers.

Electrospinning biopolymers from ionic liquids requires control of different solution properties than volatile organic solvents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zavgorodnya, Oleksandra; Shamshina, Julia L.; Bonner, Jonathan R.

Here, we report the correlation between key solution properties and spinability of chitin from the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C 2mim][OAc]), and the similarities and differences to electrospinning solutions of non-ionic polymers in volatile organic compounds (VOCs). We found that when electrospinning is conducted from ILs, conductivity and surface tension are not the key parameters regulating spinability, while solution viscosity and polymer concentration are. Contrarily, for electrospinning of polymers from VOCs, solution conductivity and viscosity have been reported to be among some of the most important factors controlling fiber formation. For chitin electrospun from [C 2mim][OAc], we found bothmore » a critical chitin concentration required for continuous fiber formation (> 0.20 wt%) and a required viscosity for the spinning solution (between ca. 450 – 1500 cP). The high viscosities of the biopolymer-IL solutions made it possible to electrospin solutions with low, less than 1 wt% of polymer concentration and produce thin fibers without the need to adjust the electrospinning parameters. These results suggest new prospects for the control of fiber architecture in non-woven mats, which is crucial for materials performance.« less

Electrospinning biopolymers from ionic liquids requires control of different solution properties than volatile organic solvents

DOE PAGES

Zavgorodnya, Oleksandra; Shamshina, Julia L.; Bonner, Jonathan R.; ...

2017-04-27

Here, we report the correlation between key solution properties and spinability of chitin from the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C 2mim][OAc]), and the similarities and differences to electrospinning solutions of non-ionic polymers in volatile organic compounds (VOCs). We found that when electrospinning is conducted from ILs, conductivity and surface tension are not the key parameters regulating spinability, while solution viscosity and polymer concentration are. Contrarily, for electrospinning of polymers from VOCs, solution conductivity and viscosity have been reported to be among some of the most important factors controlling fiber formation. For chitin electrospun from [C 2mim][OAc], we found bothmore » a critical chitin concentration required for continuous fiber formation (> 0.20 wt%) and a required viscosity for the spinning solution (between ca. 450 – 1500 cP). The high viscosities of the biopolymer-IL solutions made it possible to electrospin solutions with low, less than 1 wt% of polymer concentration and produce thin fibers without the need to adjust the electrospinning parameters. These results suggest new prospects for the control of fiber architecture in non-woven mats, which is crucial for materials performance.« less

International review of cytology. Volume 109: A survey of cell biology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourne, G.; Jeon, K.W.; Friedlander, M.

1987-01-01

This book's contents are: Local Regulation of Testicular Function;Microtubules and DNA Replication;Differentiation of Spermatogenic Cells from Vertebrates in Vitro;The Developmental Program of Spermiogenesis in Drosophila: A Genetic Analysis;Cell Motility and Ionic Relations in Characean Cells as Revealed by Internal Perfusion and Other Cell Models;and The Culture of Oral Epithelium. Each chapter includes references.

Regulating NH4+, N0-, and K+ concentration and proportions improves in vitro tissue growth.

USDA-ARS?s Scientific Manuscript database

A mixture-amount experiment that simultaneously varied both the ratios and total ionic concentration (from 20-100 mM) of NH4+, NO3+, and K+ was used to maximize sweet orange callus growth cv. ‘Hamlin.’ These experiments were free of ion confounding effects, i.e. ions added via pH adjustments and sa...

The nature of the in vivo sodium and chloride uptake mechanisms through the epithelium against sodium and of bicarbonate against chloride.

PubMed

García Romeu, F; Salibián, A; Pezzani-Hernádez, S

1969-06-01

The Chilean frog, Calyptocephallela gayi, placed in dilute NaCl solutions may pump Na(+) and Cl(-) at very different rates depending on the kind of bath solutions in which it was preadapted. Furthermore, Na(+) and Cl(-) may be absorbed from solutions in which the accompanying coion, such as sulfate and choline, respectively, is impermeant. In all these cases it is obligatory to postulate the existence of two ionic exchange mechanisms, Cl(-) and Na(+), being exchanged against endogenous anions and cations, respectively. It has been determined that Na(+) is exchanged against endogenous H(+) and that Cl(-) is exchanged against HCO(3) (-). In animals pumping Na(+) and Cl(-) from dilute NaCl solutions Na(+) or Cl(-) uptake may be selectively inhibited, while the flux of the accompanying ion remains unchanged. This is considered to be an additional proof that both Na(+) and Cl(-) fluxes are always independent. The role of the ionic exchange mechanisms in the direct regulation of the Na(+) and Cl(-) levels in the internal medium is discussed as well as their relationship in the regulation of the acid-base equilibrium; other physioecological considerations have been treated.

The Nature of the In Vivo Sodium and Chloride Uptake Mechanisms through the Epithelium of the Chilean Frog Calyptocephalella gayi (Dum. et Bibr., 1841)

PubMed Central

Romeu, Federico García; Salibián, Alfredo; Pezzani-Hernandez, Silvia

1969-01-01

The Chilean frog, Calyptocephallela gayi, placed in dilute NaCl solutions may pump Na+ and Cl- at very different rates depending on the kind of bath solutions in which it was preadapted. Furthermore, Na+ and Cl- may be absorbed from solutions in which the accompanying coion, such as sulfate and choline, respectively, is impermeant. In all these cases it is obligatory to postulate the existence of two ionic exchange mechanisms, Cl- and Na+, being exchanged against endogenous anions and cations, respectively. It has been determined that Na+ is exchanged against endogenous H+ and that Cl- is exchanged against HCO3 -. In animals pumping Na+ and Cl- from dilute NaCl solutions Na+ or Cl- uptake may be selectively inhibited, while the flux of the accompanying ion remains unchanged. This is considered to be an additional proof that both Na+ and Cl- fluxes are always independent. The role of the ionic exchange mechanisms in the direct regulation of the Na+ and Cl- levels in the internal medium is discussed as well as their relationship in the regulation of the acid-base equilibrium; other physioecological considerations have been treated. PMID:5822161

The effect of human microtubule-associated-protein tau on the assembly structure of microtubules and its ionic strength dependence

NASA Astrophysics Data System (ADS)

Choi, M. C.; Raviv, U.; Miller, H. P.; Gaylord, M. R.; Kiris, E.; Ventimiglia, D.; Needleman, D. J.; Chung, P. J.; Deek, J.; Lapointe, N.; Kim, M. W.; Wilson, L.; Feinstein, S. C.; Safinya, C. R.

2010-03-01

Microtubules (MTs), 25 nm protein nanotubes, are among the major filamentous elements of the eukaryotic cytoskeleton involved in intracellular trafficking, cell division and the establishment and maintenance of cell shape. Microtubule-associated-protein tau regulates tubulin assembly, MT dynamics and stability. Aberrant tau action has long been correlated with numerous neurodegenerative diseases, including Alzheimer's, and fronto-temporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) Using synchrotron small angle x-ray scattering (SAXS) and binding assay, we examine the effects of tau on the assembly structure of taxol-stabilized MTs. We find that tau regulates the distribution of protofilament numbers in MTs as reflected in the observed increase in the average radius of MTs with increasing the tau/tubulin molar ratio. Additionally, tau-MT interactions are mediated to a large extent via electrostatic interactions: the binding affinity of tau to MTs is ionic strength dependent. Supported by DOE-BES DE-FG02-06ER46314, NSF DMR-0803103, NIH NS35010, NIH NS13560. (Ref) M.C. Choi, S.C. Feinstein, and C.R. Safinya et al. Biophys. J. 97; 519 (2009).

Free-Standing Bilayered Nanoparticle Superlattice Nanosheets with Asymmetric Ionic Transport Behaviors.

PubMed

Rao, Siyuan; Si, Kae Jye; Yap, Lim Wei; Xiang, Yan; Cheng, Wenlong

2015-11-24

Natural cell membranes can directionally and selectively regulate the ion transport, which is critical for the functioning of living cells. Here, we report on the fabrication of an artificial membrane based on an asymmetric nanoparticle superlattice bilayered nanosheet, which exhibits similar ion transport characteristics. The superlattice nanosheets were fabricated via a drying-mediated self-assembly of polystyrene-capped gold nanoparticles at the liquid-air interface. By adopting a layer-by-layer assembly process, an asymmetric nanomembrane could be obtained consisting of two nanosheets with different nanoparticle size. The resulting nanomembranes exhibit an asymmetric ion transport behavior, and diode-like current-voltage curves were observed. The asymmetric ion transport is attributed to the cone-like nanochannels formed within the membranes, upon which a simulation map was established to illustrate the relationship between the channel structure and the ionic selectivity, in consistency with our experimental results. Our superlattice nanosheet-based design presents a promising strategy for the fabrication of next-generation smart nanomembranes for rationally and selectively regulating the ion transport even at a large ion flux, with potential applications in a wide range of fields, including biosensor devices, energy conversion, biophotonics, and bioelectronics.

Microbial induction of vascular pathology in the CNS.

PubMed

Kang, Silvia S; McGavern, Dorian B

2010-09-01

The central nervous system (CNS) is a finely tuned organ that participates in nearly every aspect of our day-to-day function. Neurons lie at the core of this functional unit and maintain an active dialogue with one another as well as their fellow CNS residents (e.g. astrocytes, oligodendrocytes, microglia). Because of this complex dialogue, it is essential that the CNS milieu be tightly regulated in order to permit uninterrupted and efficient neural chemistry. This is accomplished in part by anatomical barriers that segregate vascular components from the cerebral spinal fluid (CSF) and brain parenchyma. These barriers impede entry of noxious materials and enable the CNS to maintain requisite protein and ionic balances for constant electrochemical signaling. Under homeostatic conditions, the CNS is protected by the presence of specialized endothelium/epithelium, the blood brain barrier (BBB), and the blood-CSF barrier. However, following CNS infection these protective barriers can be comprised, sometimes resulting in severe neurological complications triggered by an imbalance or blockage of neural chemistry. In some instances, these disruptions are severe enough to be fatal. This review focuses on a selection of microbes (both viruses and parasites) that compromise vascular barriers and induce neurological complications upon gaining access to the CNS. Emphasis is placed on CNS diseases that result from a pathogenic interplay between host immune defenses and the invading microbe.

Effects of hydration on steric and electric charge-induced interstitial volume exclusion--a model.

PubMed

Øien, Alf H; Justad, Sigrid R; Tenstad, Olav; Wiig, Helge

2013-09-03

The presence of collagen and charged macromolecules like glycosaminoglycans (GAGs) in the interstitial space limits the space available for plasma proteins and other macromolecules. This phenomenon, known as interstitial exclusion, is of importance for interstitial fluid volume regulation. Physical/mathematical models are presented for calculating the exclusion of electrically charged and neutral macromolecules that equilibrate in the interstitium under various degrees of hydration. Here, a central hypothesis is that the swelling of highly electrically charged GAGs with increased hydration shields parts of the neutral collagen of the interstitial matrix from interacting with electrically charged macromolecules, such that exclusion of charged macromolecules exhibits change due to steric and charge effects. GAGs are also thought to allow relatively small neutral, but also charged macromolecules neutralized by a very high ionic strength, diffuse into the interior of GAGs, whereas larger macromolecules may not. Thus, in the model, relatively small electrically charged macromolecules, such as human serum albumin, and larger neutral macromolecules such as IgG, will have quite similar total volume exclusion properties in the interstitium. Our results are in agreement with ex vivo and in vivo experiments, and suggest that the charge of GAGs or macromolecular drugs may be targeted to increase the tissue uptake of macromolecular therapeutic agents. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Electrostatic interactions during acidic phospholipid reactivation of DnaA protein, the Escherichia coli initiator of chromosomal replication.

PubMed

Kitchen, J L; Li, Z; Crooke, E

1999-05-11

The initiation of Escherichia coli chromosomal replication by DnaA protein is strongly influenced by the tight binding of the nucleotides ATP and ADP. Anionic phospholipids in a fluid bilayer promote the conversion of inactive ADP-DnaA protein to replicatively active ATP-DnaA protein in vitro, and thus likely play a key role in regulating DnaA activity. Previous studies have revealed that, during this reactivation, a specific region of DnaA protein inserts into the hydrophobic portion of the lipid bilayer in an acidic phospholipid-dependent manner. To elucidate the requirement for acidic phospholipids in the reactivation process, the contribution of electrostatic forces in the interaction of DnaA and lipid was examined. DnaA-lipid binding required anionic phospholipids, and DnaA-lipid binding as well as lipid-mediated release of DnaA-bound nucleotide were inhibited by increased ionic strength, suggesting the involvement of electrostatic interactions in these processes. As the vesicular content of acidic phospholipids was increased, both nucleotide release and DnaA-lipid binding increased in a linear, parallel manner. Given that DnaA-membrane binding, the insertion of DnaA into the membrane, and the consequent nucleotide release all require anionic phospholipids, the acidic headgroup may be necessary to recruit DnaA protein to the membrane for insertion and subsequent reactivation for replication.

Protons, osmolytes, and fitness of internal milieu for protein function.

PubMed

Somero, G N

1986-08-01

The composition of the intracellular milieu shows striking similarities among widely different species. Only certain values of intracellular pH, values that generally reflect alphastat regulation, and only narrow ranges of inorganic ion concentrations are found in the cytoplasm of the cells of most animals, plants, and microorganisms. In water-stressed organisms only a few types of low-molecular-weight organic molecules (osmolytes) are accumulated. These highly conserved characteristics of the intracellular fluids reflect the need to maintain critical features of macromolecules within narrow ranges optimal for life. For proteins these features include maintaining adequate rates of catalysis, a high level of regulatory responsiveness, and a precise balance between stability and lability of structure (tertiary conformation, subunit assembly, and multiprotein complexes). The optimal values for these functional and structural features of proteins often lie near the midrange of possible values for these properties, and only under specific conditions of intracellular pH, ionic strength, and osmolyte composition are these optimal midrange values conserved. In dormant cells the departure of solution conditions from values that are optimal for protein function and structure may be instrumental in reducing or shutting down metabolic functions. Seen from a broad evolutionary perspective, the evolution of the intracellular milieu is an important complement to macromolecular evolution. In certain instances appropriate modifications of the internal milieu may reduce the need for adaptive amino acid replacements in proteins.

Microbial Induction of Vascular Pathology in the CNS

PubMed Central

Kang, Silvia S.

2016-01-01

The central nervous system (CNS) is a finely tuned organ that participates in nearly every aspect of our day-to-day function. Neurons lie at the core of this functional unit and maintain an active dialogue with one another as well as their fellow CNS residents (e.g. astrocytes, oligodendrocytes, microglia). Because of this complex dialogue, it is essential that the CNS milieu be tightly regulated in order to permit uninterrupted and efficient neural chemistry. This is accomplished in part by anatomical barriers that segregate vascular components from the cerebral spinal fluid (CSF) and brain parenchyma. These barriers impede entry of noxious materials and enable the CNS to maintain requisite protein and ionic balances for constant electrochemical signaling. Under homeostatic conditions, the CNS is protected by the presence of specialized endothelium/epithelium, the blood brain barrier (BBB), and the blood-CSF barrier. However, following CNS infection these protective barriers can be comprised, sometimes resulting in severe neurological complications triggered by an imbalance or blockage of neural chemistry. In some instances, these disruptions are severe enough to be fatal. This review focuses on a selection of microbes (both viruses and parasites) that compromise vascular barriers and induce neurological complications upon gaining access to the CNS. Emphasis is placed on CNS diseases that result from a pathogenic interplay between host immune defenses and the invading microbe. PMID:20401700

Short-Term Synaptic Plasticity Regulation in Solution-Gated Indium-Gallium-Zinc-Oxide Electric-Double-Layer Transistors.

PubMed

Wan, Chang Jin; Liu, Yang Hui; Zhu, Li Qiang; Feng, Ping; Shi, Yi; Wan, Qing

2016-04-20

In the biological nervous system, synaptic plasticity regulation is based on the modulation of ionic fluxes, and such regulation was regarded as the fundamental mechanism underlying memory and learning. Inspired by such biological strategies, indium-gallium-zinc-oxide (IGZO) electric-double-layer (EDL) transistors gated by aqueous solutions were proposed for synaptic behavior emulations. Short-term synaptic plasticity, such as paired-pulse facilitation, high-pass filtering, and orientation tuning, was experimentally emulated in these EDL transistors. Most importantly, we found that such short-term synaptic plasticity can be effectively regulated by alcohol (ethyl alcohol) and salt (potassium chloride) additives. Our results suggest that solution gated oxide-based EDL transistors could act as the platforms for short-term synaptic plasticity emulation.