Thermal Response Analysis of Phospholipid Bilayers Using Ellipsometric Techniques.

PubMed

González-Henríquez, Carmen M; Villegas-Opazo, Vanessa A; Sagredo-Oyarce, Dallits H; Sarabia-Vallejos, Mauricio A; Terraza, Claudio A

2017-08-18

Biomimetic planar artificial membranes have been widely studied due to their multiple applications in several research fields. Their humectation and thermal response are crucial for reaching stability; these characteristics are related to the molecular organization inside the bilayer, which is affected by the aliphatic chain length, saturations, and molecule polarity, among others. Bilayer stability becomes a fundamental factor when technological devices are developed-like biosensors-based on those systems. Thermal studies were performed for different types of phosphatidylcholine (PC) molecules: two pure PC bilayers and four binary PC mixtures. These analyses were carried out through the detection of slight changes in their optical and structural parameters via Ellipsometry and Surface Plasmon Resonance (SPR) techniques. Phospholipid bilayers were prepared by Langmuir-Blodgett technique and deposited over a hydrophilic silicon wafer. Their molecular inclination degree, mobility, and stability of the different phases were detected and analyzed through bilayer thickness changes and their optical phase-amplitude response. Results show that certain binary lipid mixtures-with differences in its aliphatic chain length-present a co-existence of two thermal responses due to non-ideal mixing.

Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment

ERIC Educational Resources Information Center

Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

2011-01-01

Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

On hydrodynamic phase field models for binary fluid mixtures

NASA Astrophysics Data System (ADS)

Yang, Xiaogang; Gong, Yuezheng; Li, Jun; Zhao, Jia; Wang, Qi

2018-05-01

Two classes of thermodynamically consistent hydrodynamic phase field models have been developed for binary fluid mixtures of incompressible viscous fluids of possibly different densities and viscosities. One is quasi-incompressible, while the other is incompressible. For the same binary fluid mixture of two incompressible viscous fluid components, which one is more appropriate? To answer this question, we conduct a comparative study in this paper. First, we visit their derivation, conservation and energy dissipation properties and show that the quasi-incompressible model conserves both mass and linear momentum, while the incompressible one does not. We then show that the quasi-incompressible model is sensitive to the density deviation of the fluid components, while the incompressible model is not in a linear stability analysis. Second, we conduct a numerical investigation on coarsening or coalescent dynamics of protuberances using the two models. We find that they can predict quite different transient dynamics depending on the initial conditions and the density difference although they predict essentially the same quasi-steady results in some cases. This study thus cast a doubt on the applicability of the incompressible model to describe dynamics of binary mixtures of two incompressible viscous fluids especially when the two fluid components have a large density deviation.

Theories of binary fluid mixtures: from phase-separation kinetics to active emulsions

NASA Astrophysics Data System (ADS)

Cates, Michael E.; Tjhung, Elsen

2018-02-01

Binary fluid mixtures are examples of complex fluids whose microstructure and flow are strongly coupled. For pairs of simple fluids, the microstructure consists of droplets or bicontinuous demixed domains and the physics is controlled by the interfaces between these domains. At continuum level, the structure is defined by a composition field whose gradients which are steep near interfaces drive its diffusive current. These gradients also cause thermodynamic stresses which can drive fluid flow. Fluid flow in turn advects the composition field, while thermal noise creates additional random fluxes that allow the system to explore its configuration space and move towards the Boltzmann distribution. This article introduces continuum models of binary fluids, first covering some well-studied areas such as the thermodynamics and kinetics of phase separation, and emulsion stability. We then address cases where one of the fluid components has anisotropic structure at mesoscopic scales creating nematic (or polar) liquid-crystalline order; this can be described through an additional tensor (or vector) order parameter field. We conclude by outlining a thriving area of current research, namely active emulsions, in which one of the binary components consists of living or synthetic material that is continuously converting chemical energy into mechanical work.

Secreted and intracellular phospholipases A2 inhibition by 1-decyl 2-octyl-glycerophosphocholine in rat peritoneal macrophages.

PubMed

Boucrot, P; Bobin-Dubigeon, C; Elkihel, L; Letourneux, Y; Jugé, M; Gandemer, G; Petit, J Y

1998-01-01

Compounds able to inhibit phospholipases A2 can be considered as potential anti-inflammatory drugs. In this respect, the inhibitory effect of the phospholipid analogue 1-decyl 2-octyl-rac-glycero-3-phosphocholine (decyloctyl-GPC) added to the culture medium of rat peritoneal macrophages stimulated with ionophore A23187 was determined. (a) The substrate of phospholipase A2 1-octadecanoyl 2-[14C]eicosatetraenoyl-sn-glycero-3-phosphocholine ([14C]20:4-GPC) was added to the culture medium. In macrophages + extracellular fluids, its hydrolysis at the 2-position, produced [14C]non-phosphorous lipids which reached 12% of the dose at 0.14 microM, 73% at 0.9 and > 90% at 1.6 microM; in experiments where macrophages and extracellular fluids were analyzed separately, decyloctyl-GPC initially added at 4 microM, significantly inhibited the release of [14C]fatty acids and the eicosanoid synthesis, demonstrating its ability to inhibit secreted and/or intracellular phospholipases A2. (b) Extracellular fluids were separated from the macrophages and incubated with [14C]20:4-GPC: 48% of the dose was hydrolyzed by extracellular fluid-associated secreted phospholipase A2 and decyloctyl-GPC at 3 microM, reduced this hydrolysis by 50%. (c) [3H]arachidonic acid ([3H]20:4) was added to the culture medium and was esterified in the macrophage membrane phospholipids. Activation of intracellular phospholipase A2 induced the release of [3H] fatty acids and eicosanoid synthesis. These releases were inhibited by 50% with decyloctyl-GPC added at 4 microM. (d) [3H]20:4 and [14C]20:4-GPC were added to the culture medium of the macrophages. [3H] and [14C] fatty acids and eicosanoids were released in macrophages or extracellular fluids. They were significantly reduced by the phospholipid analogue added at 4 microM. It is concluded that secreted and intracellular phospholipases A2 were both inhibited by decyloctyl-GPC which extensively reduced the 20:4 release from exogenous and membrane phospholipids and therefore eicosanoid synthesis.

Free choline and phospholipid-bound choline concentrations in serum and dialysate during peritoneal dialysis in children and adults.

PubMed

Ilcol, Yesim Ozarda; Dönmez, Osman; Yavuz, Mahmut; Dilek, Kamil; Yurtkuran, Mustafa; Ulus, Ismail H

2002-06-01

This study tested whether continuous ambulatory peritoneal dialysis (CAPD) changes free or phospholipid-bound choline concentrations in serum or peritoneal dialysis fluid of patients with end stage renal disease (ESRD). Serum and dialysate choline and phospholipid-bound choline were measured before, during and after 6 h CAPD. Serum choline concentrations were higher in patients with ESRD compared with age-matched controls. CAPD lowered serum choline concentrations significantly although it did not influence phospholipid-bound choline. Choline accumulated in the dialysate, reaching 28.4 +/- 2.7 microM in children and 18.2 +/- 1.4 microM in adults, during six hours CAPD; phospholipid-bound choline increased to 22.9 +/- 2.5 microM and 10.8 +/- 1.4 microM in children and adults, respectively. The total daily loss of choline into the dialysate was 181 +/- 20 micromoles in children and 260 +/- 18 micromoles in adults. CAPD causes a substantial loss of choline into peritoneal dialysates and reduces serum choline concentrations significantly.

Communication: Virial coefficients and demixing in highly asymmetric binary additive hard-sphere mixtures.

PubMed

López de Haro, Mariano; Tejero, Carlos F; Santos, Andrés

2013-04-28

The problem of demixing in a binary fluid mixture of highly asymmetric additive hard spheres is revisited. A comparison is presented between the results derived previously using truncated virial expansions for three finite size ratios with those that one obtains with the same approach in the extreme case in which one of the components consists of point particles. Since this latter system is known not to exhibit fluid-fluid segregation, the similarity observed for the behavior of the critical constants arising in the truncated series in all instances, while not being conclusive, may cast serious doubts as to the actual existence of a demixing fluid-fluid transition in disparate-sized binary additive hard-sphere mixtures.

Harnessing Active Fins to Segregate Nanoparticles from Binary Mixtures

NASA Astrophysics Data System (ADS)

Liu, Ya; Kuksenok, Olga; Bhattacharya, Amitabh; Ma, Yongting; He, Ximin; Aizenberg, Joanna; Balazs, Anna

2014-03-01

One of the challenges in creating high-performance polymeric nanocomposites for optoelectronic applications, such as bilayer solar cells, is establishing effective and facile routes for controlling the properties of interface and segregation of binary particles with hole conductor particles and electron conductor particles. We model nanocomposites that encompass binary particles and binary blends in a microchannel. An array of oscillating microfins is immersed in the fluid and tethered to the floor of the microchannel; the fluid containing mixture of nanoparticles is driven along the channel by an imposed pressure gradient. During the oscillations, the fins with the specific chemical wetting reach the upper fluid when they are upright and are entirely within the lower stream when they are tilted. We introduce specific interaction between the fins and particulates in the solution. Fins can selectively ``catch'' target nanoparticles within the upper fluid stream and then release them into the lower stream. We focus on different modes of fins motion to optimize selective segregation of particles within binary mixture. Our approach provides an effective means of tailoring the properties and ultimate performance of the composites.

Active microrheology and simultaneous visualization of sheared phospholipid monolayers

PubMed Central

Choi, S.Q.; Steltenkamp, S.; Zasadzinski, J.A.; Squires, T.M.

2011-01-01

Two-dimensional films of surface-active agents—from phospholipids and proteins to nanoparticles and colloids—stabilize fluid interfaces, which are essential to the science, technology and engineering of everyday life. The 2D nature of interfaces present unique challenges and opportunities: coupling between the 2D films and the bulk fluids complicates the measurement of surface dynamic properties, but allows the interfacial microstructure to be directly visualized during deformation. Here we present a novel technique that combines active microrheology with fluorescence microscopy to visualize fluid interfaces as they deform under applied stress, allowing structure and rheology to be correlated on the micron-scale in monolayer films. We show that even simple, single-component lipid monolayers can exhibit viscoelasticity, history dependence, a yield stress and hours-long time scales for elastic recoil and aging. Simultaneous visualization of the monolayer under stress shows that the rich dynamical response results from the cooperative dynamics and deformation of liquid-crystalline domains and their boundaries. PMID:21587229

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.

Widom Lines in Binary Mixtures of Supercritical Fluids.

PubMed

Raju, Muralikrishna; Banuti, Daniel T; Ma, Peter C; Ihme, Matthias

2017-06-08

Recent experiments on pure fluids have identified distinct liquid-like and gas-like regimes even under supercritical conditions. The supercritical liquid-gas transition is marked by maxima in response functions that define a line emanating from the critical point, referred to as Widom line. However, the structure of analogous state transitions in mixtures of supercritical fluids has not been determined, and it is not clear whether a Widom line can be identified for binary mixtures. Here, we present first evidence for the existence of multiple Widom lines in binary mixtures from molecular dynamics simulations. By considering mixtures of noble gases, we show that, depending on the phase behavior, mixtures transition from a liquid-like to a gas-like regime via distinctly different pathways, leading to phase relationships of surprising complexity and variety. Specifically, we show that miscible binary mixtures have behavior analogous to a pure fluid and the supercritical state space is characterized by a single liquid-gas transition. In contrast, immiscible binary mixture undergo a phase separation in which the clusters transition separately at different temperatures, resulting in multiple distinct Widom lines. The presence of this unique transition behavior emphasizes the complexity of the supercritical state to be expected in high-order mixtures of practical relevance.

In-situ observation of switchable nanoscale topography for y-shaped binary brushes in fluids.

PubMed

Lin, Yen-Hsi; Teng, Jing; Zubarev, Eugene R; Shulha, Hennady; Tsukruk, Vladimir V

2005-03-01

Direct, in-fluid observation of the surface morphology and nanomechanical properties of the mixed brushes composed of Y-shaped binary molecules PS-PAA revealed nanoscale network-like surface topography formed by coexisting stretched soluble PAA arms and collapsed insoluble PS chains in water. Placement of Y-shaped brushes in different fluids resulted in dramatic reorganization ranging from soft repellent layer covered by swollen PS arms in toluene to an adhesive, mixed layer composed of coexisting swollen PAA and collapsed PS arms in water. These binary layers with the overall nanoscale thickness can serve as adaptive nanocoatings with stimuli-responsive properties.

Calculating Mass Diffusion in High-Pressure Binary Fluids

NASA Technical Reports Server (NTRS)

Bellan, Josette; Harstad, Kenneth

2004-01-01

A comprehensive mathematical model of mass diffusion has been developed for binary fluids at high pressures, including critical and supercritical pressures. Heretofore, diverse expressions, valid for limited parameter ranges, have been used to correlate high-pressure binary mass-diffusion-coefficient data. This model will likely be especially useful in the computational simulation and analysis of combustion phenomena in diesel engines, gas turbines, and liquid rocket engines, wherein mass diffusion at high pressure plays a major role.

Investigation of waste heat recovery of binary geothermal plants using single component refrigerants

NASA Astrophysics Data System (ADS)

Unverdi, M.

2017-08-01

In this study, the availability of waste heat in a power generating capacity of 47.4 MW in Germencik Geothermal Power Plant has been investigated via binary geothermal power plant. Refrigerant fluids of 7 different single components such as R-134a, R-152a, R-227ea, R-236fa, R-600, R-143m and R-161 have been selected. The binary cycle has been modeled using the waste heat equaling to mass flow rate of 100 kg/s geothermal fluid. While the inlet temperature of the geothermal fluid into the counter flow heat exchanger has been accepted as 110°C, the outlet temperature has been accepted as 70°C. The inlet conditions have been determined for the refrigerants to be used in the binary cycle. Finally, the mass flow rate of refrigerant fluid and of cooling water and pump power consumption and power generated in the turbine have been calculated for each inlet condition of the refrigerant. Additionally, in the binary cycle, energy and exergy efficiencies have been calculated for 7 refrigerants in the availability of waste heat. In the binary geothermal cycle, it has been found out that the highest exergy destruction for all refrigerants occurs in the heat exchanger. And the highest and lowest first and second law efficiencies has been obtained for R-600 and R-161 refrigerants, respectively.

Equilibrium, stability, and orbital evolution of close binary systems

NASA Technical Reports Server (NTRS)

Lai, Dong; Rasio, Frederic A.; Shapiro, Stuart L.

1994-01-01

We present a new analytic study of the equilibrium and stability properties of close binary systems containing polytropic components. Our method is based on the use of ellipsoidal trial functions in an energy variational principle. We consider both synchronized and nonsynchronized systems, constructing the compressible generalizations of the classical Darwin and Darwin-Riemann configurations. Our method can be applied to a wide variety of binary models where the stellar masses, radii, spins, entropies, and polytropic indices are all allowed to vary over wide ranges and independently for each component. We find that both secular and dynamical instabilities can develop before a Roche limit or contact is reached along a sequence of models with decreasing binary separation. High incompressibility always makes a given binary system more susceptible to these instabilities, but the dependence on the mass ratio is more complicated. As simple applications, we construct models of double degenerate systems and of low-mass main-sequence star binaries. We also discuss the orbital evoltuion of close binary systems under the combined influence of fluid viscosity and secular angular momentum losses from processes like gravitational radiation. We show that the existence of global fluid instabilities can have a profound effect on the terminal evolution of coalescing binaries. The validity of our analytic solutions is examined by means of detailed comparisons with the results of recent numerical fluid calculations in three dimensions.

[The significance of vaginal fluid substances as growth media in genital mycosis].

PubMed

Neumann, G; Gartzke, J; Böhme, H; Spitzbart, H

1984-01-01

By means of thin layer chromatography amino acids, lipids and phospholipids were detected in the vaginal fluids of pregnant and nonpregnant women with and without vaginal yeast colonization. Though pregnancy and/or yeast colonization do not seem to alter qualitatively the spectrum of amino acids and lipids of the vaginal fluid, an influence is supposed of these substances - like that of glucose - on growth and metabolism of the yeasts and on the clinical manifestation of vaginal candidosis.

Thermodynamics of Indomethacin Adsorption to Phospholipid Membranes.

PubMed

Fearon, Amanda D; Stokes, Grace Y

2017-11-22

Using second-harmonic generation, we directly monitored adsorption of indomethacin, a nonsteroidal anti-inflammatory drug, to supported lipid bilayers composed of phospholipids of varying phase, cholesterol content, and head group charge without the use of extrinsic labels at therapeutically relevant aqueous concentrations. Indomethacin adsorbed to gel-phase lipids with a high binding affinity, suggesting that like other arylacetic acid-containing drugs, it preferentially interacts with ordered lipid domains. We discovered that adsorption of indomethacin to gel-phase phospholipids was endothermic and entropically driven, whereas adsorption to fluid-phase phospholipids was exothermic and enthalpically driven. As temperature increased from 19 to 34 °C, binding affinities to gel-phase lipids increased by 7-fold but relative surface concentration decreased to one-fifth of the original value. We also compared our results to the entropies reported for indomethacin adsorbed to surfactant micelles, which are used in drug delivery systems, and assert that adsorbed water molecules in the phospholipid bilayer may be buried deeper into the acyl chains and less accessible for disruption. The thermodynamic studies reported here provide mechanistic insight into indomethacin interactions with mammalian plasma membranes in the gastrointestinal tract and inform studies of drug delivery, where indomethacin is commonly used as a prototypical, hydrophobic small-molecule drug.

Organic–inorganic binary mixture matrix for comprehensive laser-desorption ionization mass spectrometric analysis and imaging of medium-size molecules including phospholipids, glycerolipids, and oligosaccharides

DOE PAGES

Feenstra, Adam D.; Ames Lab., Ames, IA; O'Neill, Kelly C.; ...

2016-10-13

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a widely adopted, versatile technique, especially in high-throughput analysis and imaging. However, matrix-dependent selectivity of analytes is often a severe limitation. In this work, a mixture of organic 2,5-dihydroxybenzoic acid and inorganic Fe 3O 4 nanoparticles is developed as a binary MALDI matrix to alleviate the well-known issue of triacylglycerol (TG) ion suppression by phosphatidylcholine (PC). In application to lipid standards and maize seed cross-sections, the binary matrix not only dramatically reduced the ion suppression of TG, but also efficiently desorbed and ionized a wide variety of lipids such as cationic PC, anionicmore » phosphatidylethanolamine (PE) and phosphatidylinositol (PI), and neutral digalactosyldiacylglycerol (DGDG). The binary matrix was also very efficient for large polysaccharides, which were not detected by either of the individual matrices. As a result, the usefulness of the binary matrix is demonstrated in MS imaging of maize seed sections, successfully visualizing diverse medium-size molecules and acquiring high-quality MS/MS spectra for these compounds.« less

Multi-stage flash degaser

DOEpatents

Rapier, P.M.

1980-06-26

A multi-stage flash degaser is incorporated in an energy conversion system having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger in order that the heat exchanger and a turbine and condenser of the system can operate at optimal efficiency.

Refractive index and solubility control of para-cymene solutions for index-matched fluid-structure interaction studies

NASA Astrophysics Data System (ADS)

Fort, Charles; Fu, Christopher D.; Weichselbaum, Noah A.; Bardet, Philippe M.

2015-12-01

To deploy optical diagnostics such as particle image velocimetry or planar laser-induced fluorescence (PLIF) in complex geometries, it is beneficial to use index-matched facilities. A binary mixture of para-cymene and cinnamaldehyde provides a viable option for matching the refractive index of acrylic, a common material for scaled models and test sections. This fluid is particularly appropriate for large-scale facilities and when a low-density and low-viscosity fluid is sought, such as in fluid-structure interaction studies. This binary solution has relatively low kinematic viscosity and density; its use enables the experimentalist to select operating temperature and to increase fluorescence signal in PLIF experiments. Measurements of spectral and temperature dependence of refractive index, density, and kinematic viscosity are reported. The effect of the binary mixture on solubility control of Rhodamine 6G is also characterized.

Molecular Dynamic Analysis of Hyaluronic Acid and Phospholipid Interaction in Tribological Surgical Adjuvant Design for Osteoarthritis.

PubMed

Siódmiak, Jacek; Bełdowski, Piotr; Augé, Wayne K; Ledziński, Damian; Śmigiel, Sandra; Gadomski, Adam

2017-09-04

Tribological surgical adjuvants constitute a therapeutic discipline made possible by surgical advances in the treatment of damaged articular cartilage beyond palliative care. The purpose of this study is to analyze interactions between hyaluronic acid and phospholipid molecules, and the formation of geometric forms, that play a role in the facilitated lubrication of synovial joint organ systems. The analysis includes an evaluation of the pathologic state to detail conditions that may be encountered by adjuvants during surgical convalescence. The synovial fluid changes in pH, hyaluronic acid polydispersity, and phospholipid concentration associated with osteoarthritis are presented as features that influence the lubricating properties of adjuvant candidates. Molecular dynamic simulation studies are presented, and the Rouse model is deployed, to rationalize low molecular weight hyaluronic acid behavior in an osteoarthritic environment of increased pH and phospholipid concentration. The results indicate that the hyaluronic acid radius of gyration time evolution is both pH- and phospholipid concentration-dependent. Specifically, dipalmitoylphosphatidylcholine induces hydrophobic interactions in the system, causing low molecular weight hyaluronic acid to shrink and at high concentration be absorbed into phospholipid vesicles. Low molecular weight hyaluronic acid appears to be insufficient for use as a tribological surgical adjuvant because an increased pH and phospholipid concentration induces decreased crosslinking that prevents the formation of supramolecular lubricating forms. Dipalmitoylphosphatidylcholine remains an adjuvant candidate for certain clinical situations. The need to reconcile osteoarthritic phenotypes is a prerequisite that should serve as a framework for future adjuvant design and subsequent tribological testing.

Phospholipid hydrolysis in a pharmaceutical emulsion assessed by physicochemical parameters and a new analytical method.

PubMed

Rabinovich-Guilatt, Laura; Dubernet, Catherine; Gaudin, Karen; Lambert, Gregory; Couvreur, Patrick; Chaminade, Pierre

2005-09-01

The aim of this work was to develop a simple high-performance liquid chromatography (HPLC) technique with evaporative light scattering detection (ELSD) for the separation and quantification of the major phospholipid (PL) and lysophospholipid (LPL) classes contained in a pharmaceutical phospholipid-based emulsion. In the established method, phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyeline (SM), lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) were separated with a PVA-Sil stationary phase and a binary gradient from pure chloroform to methanol:water (94:6 v/v) at 3.4%/min. The ELSD detection was enhanced using 0.1% triethylamine and formic acid in each gradient mobile phases. Factors such as stationary phase and ELSD drift tube temperature were optimized, concluding in optimal temperatures of 25 degrees C for separation and 50 degrees C for evaporation. This HPLC-ELSD method was then applied to a PL-emulsion exposed to autoclaving and accelerated thermal conditions at 50 degrees C. Hydrolysis of PC and PE followed first-order kinetics, representing only 45% of the total lipid mass after 3 months. The chemical stability was correlated to commonly measured formulation physical and physico-chemical parameters such as droplet size, emulsion pH and zeta-potential.

Slaved diffusion in phospholipid bilayers

PubMed Central

Zhang, Liangfang; Granick, Steve

2005-01-01

The translational diffusion of phospholipids in supported fluid bilayers splits into two populations when polyelectrolytes adsorb at incomplete surface coverage. Spatially resolved measurements using fluorescence correlation spectroscopy show that a slow mode, whose magnitude scales inversely with the degree of polymerization of the adsorbate, coexists with a fast mode characteristic of naked lipid diffusion. Inner and outer leaflets of the bilayer are affected nearly equally. Mobility may vary from spot to spot on the membrane surface, despite the lipid composition being the same. This work offers a mechanism to explain how nanosized domains with reduced mobility arise in lipid membranes. PMID:15967988

Multi-stage flash degaser

DOEpatents

Rapier, Pascal M.

1982-01-01

A multi-stage flash degaser (18) is incorporated in an energy conversion system (10) having a direct-contact, binary-fluid heat exchanger to remove essentially all of the noncondensable gases from geothermal brine ahead of the direct-contact binary-fluid heat exchanger (22) in order that the heat exchanger (22) and a turbine (48) and condenser (32) of the system (10) can operate at optimal efficiency.

Process parameters and morphology in puerarin, phospholipids and their complex microparticles generation by supercritical antisolvent precipitation.

PubMed

Li, Ying; Yang, Da-Jian; Chen, Shi-Lin; Chen, Si-Bao; Chan, Albert Sun-Chi

2008-07-09

The aim of the study was to develop and evaluate a new method for the production of puerarin phospholipids complex (PPC) microparticles. The advanced particle formation method, solution enhanced dispersion by supercritical fluids (SEDS), was used for the preparation of puerarin (Pur), phospholipids (PC) and their complex particles for the first time. Evaluation of the processing variables on PPC particle characteristics was also conducted. The processing variables included temperature, pressure, solution concentration, the flow rate of supercritical carbon dioxide (SC-CO2) and the relative flow rate of drug solution to CO2. The morphology, particle size and size distribution of the particles were determined. Meanwhile Pur and phospholipids were separately prepared by gas antisolvent precipitation (GAS) method and solid characterization of particles by the two supercritical methods was also compared. Pur formed by GAS was more orderly, purer crystal, whereas amorphous Pur particles between 0.5 and 1microm were formed by SEDS. The complex was successfully obtained by SEDS exhibiting amorphous, partially agglomerated spheres comprised of particles sized only about 1microm. SEDS method may be useful for the processing of other pharmaceutical preparations besides phospholipids complex particles. Furthermore adopting a GAS process to recrystallize pharmaceuticals will provide a highly versatile methodology to generate new polymorphs of drugs in addition to conventional techniques.

Asymmetric or symmetric bilayer formation during oblique drop impact depends on rheological properties of saturated and unsaturated lipid monolayers.

PubMed

Vranceanu, Marcel; Terinte, Nicoleta; Nirschl, Hermann; Leneweit, Gero

2011-02-01

Bilayer structures are formed by approaching two liquid surfaces with phospholipid monolayers, which are brought into contact by oblique drop impact on a liquid surface. Asymmetric bilayers can be produced by the coupling of drop and target monolayers. In contrast, symmetric bilayers or multilayers are formed by collapse of the compressed target monolayer. We show that under all studied conditions bilayer/multilayer synthesis takes place. The experimental conditions for the synthesis of asymmetric or symmetric bilayers are described quantitatively in terms of the surface rheological (surface elasticity and dilational viscosity) and the hydrodynamical parameters (Weber number and impact angle). The composition and mechanical properties of the phospholipid monolayers strongly influences the patterns of drop impact and the bilayer/multilayer formation. Cholesterol stiffens unsaturated phospholipid monolayers and fluidifies saturated monolayers. All monolayers form asymmetric vesicle-like structures, which are stable in the aqueous medium. Additionally, unsaturated phospholipid monolayers without cholesterol form symmetric vesicles by folding parts of the target monolayer. Sufficient presence of cholesterol in unsaturated phospholipid monolayers inhibits the folding of the target monolayer and the subsequent formation of symmetric bilayers. The rheological properties of saturated and unsaturated phospholipid monolayers and their mixtures with cholesterol are discussed. Based on drop impact results it is shown that the state of a so far undefined region in the DPPC/cholesterol phase diagram is a fluid phase. Copyright © 2010 Elsevier Inc. All rights reserved.

Dynamics of phase separation of binary fluids

NASA Technical Reports Server (NTRS)

Ma, Wen-Jong; Maritan, Amos; Banavar, Jayanth R.; Koplik, Joel

1992-01-01

The results of molecular-dynamics studies of surface-tension-dominated spinodal decomposition of initially well-mixed binary fluids in the absence and presence of gravity are presented. The growth exponent for the domain size and the decay exponent of the potential energy of interaction between the two species with time are found to be 0.6 +/- 0.1, inconsistent with scaling arguments based on dimensional analysis.

The Lung Surfactant System in Adult Respiratory Distress Syndrome.

DTIC Science & Technology

1979-12-01

jfugation. No significant differences in phospholipid distribution or phosphatidyl- choline (PC) fatty acid composition can be detected in...the fact that amniotic fluid from uncomplicated term pregnancies could be readily used as the source for normal surfactant. During the course of our

Differential scanning calorimetric and Fourier transform infrared spectroscopic studies of the effects of cholesterol on the thermotropic phase behavior and organization of a homologous series of linear saturated phosphatidylserine bilayer membranes.

PubMed Central

McMullen, T P; Lewis, R N; McElhaney, R N

2000-01-01

We have examined the effects of cholesterol on the thermotropic phase behavior and organization of aqueous dispersions of a homologous series of linear disaturated phosphatidylserines by high-sensitivity differential scanning calorimetry and Fourier transform infrared spectroscopy. We find that the incorporation of increasing quantities of cholesterol progressively reduces the temperature, enthalpy, and cooperativity of the gel-to-liquid-crystalline phase transition of the host phosphatidylserine bilayer, such that a cooperative chain-melting phase transition is completely or almost completely abolished at 50 mol % cholesterol, in contrast to the results of previous studies. We are also unable to detect the presence of a separate anhydrous cholesterol or cholesterol monohydrate phase in our binary mixtures, again in contrast to previous reports. We further show that the magnitude of the reduction in the phase transition temperature induced by cholesterol addition is independent of the hydrocarbon chain length of the phosphatidylserine studied. This result contrasts with our previous results with phosphatidylcholine bilayers, where we found that cholesterol increases or decreases the phase transition temperature in a chain length-dependent manner (1993. Biochemistry, 32:516-522), but is in agreement with our previous results for phosphatidylethanolamine bilayers, where no hydrocarbon chain length-dependent effects were observed (1999. Biochim. Biophys. Acta, 1416:119-234). However, the reduction in the phase transition temperature by cholesterol is of greater magnitude in phosphatidylethanolamine as compared to phosphatidylserine bilayers. We also show that the addition of cholesterol facilitates the formation of the lamellar crystalline phase in phosphatidylserine bilayers, as it does in phosphatidylethanolamine bilayers, whereas the formation of such phases in phosphatidylcholine bilayers is inhibited by the presence of cholesterol. We ascribe the limited miscibility of cholesterol in phosphatidylserine bilayers reported previously to a fractional crystallization of the cholesterol and phospholipid phases during the removal of organic solvent from the binary mixture before the hydration of the sample. In general, the results of our studies to date indicate that the magnitude of the effect of cholesterol on the thermotropic phase behavior of the host phospholipid bilayer, and its miscibility in phospholipid dispersions generally, depend on the strength of the attractive interactions between the polar headgroups and the hydrocarbon chains of the phospholipid molecule, and not on the charge of the polar headgroups per se. PMID:11023909

Fluids in porous media. IV. Quench effect on chemical potential.

PubMed

Qiao, C Z; Zhao, S L; Liu, H L; Dong, W

2017-06-21

It appears to be a common sense to measure the crowdedness of a fluid system by the densities of the species constituting it. In the present work, we show that this ceases to be valid for confined fluids under some conditions. A quite thorough investigation is made for a hard sphere (HS) fluid adsorbed in a hard sphere matrix (a quench-annealed system) and its corresponding equilibrium binary mixture. When fluid particles are larger than matrix particles, the quench-annealed system can appear much more crowded than its corresponding equilibrium binary mixture, i.e., having a much higher fluid chemical potential, even when the density of each species is strictly the same in both systems, respectively. We believe that the insight gained from this study should be useful for the design of functionalized porous materials.

Cutin and suberin monomers are membrane perturbants.

PubMed

Douliez, Jean-Paul

2004-03-15

The interaction between cutin and suberin monomers, i.e., omega -hydroxylpalmitic acid, alpha, omega -hexadecanedioic acid, alpha, omega --hexadecanediol, 12-hydroxylstearic acid, and phospholipid vesicles biomimicking the lipid structure of plant cell membranes has been studied by optical and transmission electron microscopy, quasielastic light scattering, differential scanning calorimetry, and (31)P solid-state NMR. Monomers were shown to penetrate model membranes until a molar ratio of 30%, modulating their gel to fluid-phase transition, after which monomer crystals also formed in solution. These monomers induced a decrease of the phospholipid vesicle size from several micrometers to about 300 nm. The biological implications of these findings are discussed.

Binary centrifugal microfluidics enabling novel, digital addressable functions for valving and routing.

PubMed

Wang, Guanghui; Tan, Jie; Tang, Minghui; Zhang, Changbin; Zhang, Dongying; Ji, Wenbin; Chen, Junhao; Ho, Ho-Pui; Zhang, Xuping

2018-03-16

Centrifugal microfluidics or lab-on-a-disc (LOAD) is a promising branch of lab-on-a-chip or microfluidics. Besides effective fluid transportation and inherently available density-based sample separation in centrifugal microfluidics, uniform actuation of flow on the disc makes the platform compact and scalable. However, the natural radially outward centrifugal force in a LOAD system limits its capacity to perform complex fluid manipulation steps. In order to increase the fluid manipulation freedom and integration capacity of the LOAD system, we propose a binary centrifugal microfluidics platform. With the help of Euler force, our platform allows free switching of both left and right states based on a rather simple mechanical structure. The periodical switching of state would provide a "clock" signal for a sequence of droplet binary logic operations. With the binary state platform and the "clock" signal, we can accurately handle the droplet separately in each time step with a maximum main frequency of about 10 S s-1 (switching per second). Apart from droplet manipulations such as droplet generation and metering, we also demonstrate a series of droplet logic operations, such as binary valving, droplet routing and digital addressable droplet storage. Furthermore, complex bioassays such as the Bradford assay and DNA purification assay are demonstrated on a binary platform, which is totally impossible for a traditional LOAD system. Our binary platform largely improves the capability for logic operation on the LOAD platform, and it is a simple and promising approach for microfluidic lab-on-a-disc large-scale integration.

Lipid chain saturation and the cholesterol in the phospholipid membrane affect the spectroscopic properties of lipophilic dye nile red

NASA Astrophysics Data System (ADS)

Halder, Animesh; Saha, Baishakhi; Maity, Pabitra; Kumar, Gopinatha Suresh; Sinha, Deepak Kumar; Karmakar, Sanat

2018-02-01

We have studied the effect of composition and the phase state of phospholipid membranes on the emission spectrum, anisotropy and lifetime of a lipophilic fluorescence probe nile red. Fluorescence spectrum of nile red in membranes containing cholesterol has also been investigated in order to get insights into the influence of cholesterol on the phospholipid membranes. Maximum emission wavelength (λem) of nile red in the fluid phase of saturated and unsaturated phospholipids was found to differ by 10 nm. The λem was also found to be independent of chain length and charge of the membrane. However, the λem is strongly dependent on the temperature in the gel phase. The λem and rotational diffusion rate decrease, whereas the anisotropy and lifetime increase markedly with increasing cholesterol concentration for saturated phosoholipids, such as, dimyristoyl phosphatidylcholine (DMPC) in the liquid ordered phase. However, these spectroscopic properties do not alter significantly in case of unsaturated phospholipids, such as, dioleoyl phosphatidylcholine (DOPC) in liquid disordered phase. Interestingly, red edge excitation shift (REES) in the presence of lipid-cholesterol membranes is the direct consequences of change in rotational diffusion due to motional restriction of lipids in the presence of cholesterol. This study provides correlations between the membrane compositions and fluorescence spectral features which can be utilized in a wide range of biophysical fields as well the cell biology.

Utilizing Chemo-mechanically Functionalized Oscillating Fins to ``Catch and Release'' Nanoparticles in Binary Flow

NASA Astrophysics Data System (ADS)

Liu, Ya; Kuksenok, Olga; Bhattacharya, Amitabh; Ma, Yongting; He, Ximin; Aizenberg4, Joanna; Balazs, Anna

2014-03-01

In biomimetics, designing an effective ``catch and release'' device for the selective removal of target species from the surrounding solution is critical for developing autonomous sensors and sorters. Using computer simulations, we model an array of oscillating fins that are tethered on the floor of a microchannel and immersed in a mixture of binary fluid stream and binary nanoparticles. During the oscillation, the fins with the specific chemical wetting reach the upper fluid when they are upright and are entirely immersed within the lower stream when they are tilted. We introduce specific interaction between the fins and particulates in the solution and determine conditions where the oscillating fins can selectively ?catch? target nanoparticles within the upper fluid stream and then release these particles into the lower stream. We isolate the effects of wetting contact angle between fins and fluid and the mode of fins' oscillations that lead to the efficient extraction of target species from the upper stream and their placement into the lower fluid. These studies provide fundamental insights into the system's complex dynamics and mechanism for detection, separation, and purification of multi-component mixtures.

Solidification of a binary alloy: Finite-element, single-domain simulation and new benchmark solutions

NASA Astrophysics Data System (ADS)

Le Bars, Michael; Worster, M. Grae

2006-07-01

A finite-element simulation of binary alloy solidification based on a single-domain formulation is presented and tested. Resolution of phase change is first checked by comparison with the analytical results of Worster [M.G. Worster, Solidification of an alloy from a cooled boundary, J. Fluid Mech. 167 (1986) 481-501] for purely diffusive solidification. Fluid dynamical processes without phase change are then tested by comparison with previous numerical studies of thermal convection in a pure fluid [G. de Vahl Davis, Natural convection of air in a square cavity: a bench mark numerical solution, Int. J. Numer. Meth. Fluids 3 (1983) 249-264; D.A. Mayne, A.S. Usmani, M. Crapper, h-adaptive finite element solution of high Rayleigh number thermally driven cavity problem, Int. J. Numer. Meth. Heat Fluid Flow 10 (2000) 598-615; D.C. Wan, B.S.V. Patnaik, G.W. Wei, A new benchmark quality solution for the buoyancy driven cavity by discrete singular convolution, Numer. Heat Transf. 40 (2001) 199-228], in a porous medium with a constant porosity [G. Lauriat, V. Prasad, Non-darcian effects on natural convection in a vertical porous enclosure, Int. J. Heat Mass Transf. 32 (1989) 2135-2148; P. Nithiarasu, K.N. Seetharamu, T. Sundararajan, Natural convective heat transfer in an enclosure filled with fluid saturated variable porosity medium, Int. J. Heat Mass Transf. 40 (1997) 3955-3967] and in a mixed liquid-porous medium with a spatially variable porosity [P. Nithiarasu, K.N. Seetharamu, T. Sundararajan, Natural convective heat transfer in an enclosure filled with fluid saturated variable porosity medium, Int. J. Heat Mass Transf. 40 (1997) 3955-3967; N. Zabaras, D. Samanta, A stabilized volume-averaging finite element method for flow in porous media and binary alloy solidification processes, Int. J. Numer. Meth. Eng. 60 (2004) 1103-1138]. Finally, new benchmark solutions for simultaneous flow through both fluid and porous domains and for convective solidification processes are presented, based on the similarity solutions in corner-flow geometries recently obtained by Le Bars and Worster [M. Le Bars, M.G. Worster, Interfacial conditions between a pure fluid and a porous medium: implications for binary alloy solidification, J. Fluid Mech. (in press)]. Good agreement is found for all tests, hence validating our physical and numerical methods. More generally, the computations presented here could now be considered as standard and reliable analytical benchmarks for numerical simulations, specifically and independently testing the different processes underlying binary alloy solidification.

Enzymatic hydrolysis of short-chain lecithin/long-chain phospholipid unilamellar vesicles: sensitivity of phospholipases to matrix phase state.

PubMed

Gabriel, N E; Agman, N V; Roberts, M F

1987-11-17

Short-chain lecithin/long-chain phospholipid unilamellar vesicles (SLUVs), unlike pure long-chain lecithin vesicles, are excellent substrates for water-soluble phospholipases. Hemolysis assays show that greater than 99.5% of the short-chain lecithin is partitioned in the bilayer. In these binary component vesicles, the short-chain species is the preferred substrate, while the long-chain phospholipid can be treated as an inhibitor (phospholipase C) or poor substrate (phospholipase A2). For phospholipase C Bacillus cereus, apparent Km and Vmax values show that bilayer-solubilized diheptanoylphosphatidylcholine (diheptanoyl-PC) is nearly as good a substrate as pure micellar diheptanoyl-PC, although the extent of short-chain lecithin hydrolysis depends on the phase state of the long-chain lipid. For phospholipase A2 Naja naja naja, both Km and Vmax values show a greater range: in a gel-state matrix, diheptanoyl-PC is hydrolyzed with micellelike kinetic parameters; in a liquid-crystalline matrix, the short-chain lecithin becomes comparable to the long-chain component. Both enzymes also show an anomalous increase in specific activity toward diheptanoyl-PC around the phase transition temperature of the long-chain phospholipid. Since the short-chain lecithin does not exhibit a phase transition, this must reflect fluctuations in head-group area or vertical motions of the short-chain lecithin caused by surrounding long-chain lecithin molecules. These results are discussed in terms of a specific model for SLUV hydrolysis and a general explanation for the "interfacial activation" observed with water-soluble phospholipases.

Pulmonary phospholipids in amniotic fluid of pathologic pregnancies: relationship with clinical status of the newborn.

PubMed

Zapata, A; Hernandez-Garcia, J M; Grande, C; Martinez, I; Perez, J; de la Fuente, P; Usandizaga, J A

1989-06-01

We evaluated phospholipids, C-peptide and cortisol levels in amniotic fluid of 203 pathologic pregnancies (63, class A, B and C diabetics; 11 class D, F and H diabetics; 44 preclampsia and 85 Rh-isoimmunization); the control group was 82 normal pregnant women. There was an acceleration of fetal pulmonary maturation in women with preclampsia and severe Rh-isoimmunization in class D, F and H diabetics (at 34 weeks gestation the incidence of mature surfactant (lecithin/sphingomyelin greater than or equal to 2.7 and presence of phosphatidyl-glycerol) in these groups was 30%, 50% and 100%, respectively, while it was zero in the control group). At 37 and 38 weeks only 44.4% of the class A, B and C diabetics had mature surfactant and there was a significant difference with respect to the control group (x2 = 4.9; p less than 0.05); C-peptide levels in these diabetics (class A, B and C) were higher than in controls (p less than 0.001); in pregnant women with accelerated fetal lung maturation they were lower. We demonstrated a close relationship between fetal pulmonary maturity and the type of surfactant in amniotic fluid, which was independent of gestational age.

Phospholipids and their degrading enzyme in the tears of soft contact lens wearers.

PubMed

Yamada, Masakazu; Mochizuki, Hiroshi; Kawashima, Motoko; Hata, Seiichiro

2006-12-01

Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.

Effect of composition of simulated intestinal media on the solubility of poorly soluble compounds investigated by design of experiments.

PubMed

Madsen, Cecilie Maria; Feng, Kung-I; Leithead, Andrew; Canfield, Nicole; Jørgensen, Søren Astrup; Müllertz, Anette; Rades, Thomas

2018-01-01

The composition of the human intestinal fluids varies both intra- and inter-individually. This will influence the solubility of orally administered drug compounds, and hence, the absorption and efficacy of compounds displaying solubility limited absorption. The purpose of this study was to assess the influence of simulated intestinal fluid (SIF) composition on the solubility of poorly soluble compounds. Using a Design of Experiments (DoE) approach, a set of 24 SIF was defined within the known compositions of human fasted state intestinal fluid. The SIF were composed of phospholipid, bile salt, and different pH, buffer capacities and osmolarities. On a small scale semi-robotic system, the solubility of 6 compounds (aprepitant, carvedilol, felodipine, fenofibrate, probucol, and zafirlukast) was determined in the 24 SIF. Compound specific models, describing key factors influencing the solubility of each compound, were identified. Although all models were different, the level of phospholipid and bile salt, the pH, and the interactions between these, had the biggest influences on solubility overall. Thus, a reduction of the DoE from five to three factors was possible (11-13 media), making DoE solubility studies feasible compared to single SIF solubility studies. Applying this DoE approach will lead to a better understanding of the impact of intestinal fluid composition on the solubility of a given drug compound. Copyright © 2017 Elsevier B.V. All rights reserved.

Detection and quantification of microparticles from different cellular lineages using flow cytometry. Evaluation of the impact of secreted phospholipase A2 on microparticle assessment.

PubMed

Rousseau, Matthieu; Belleannee, Clemence; Duchez, Anne-Claire; Cloutier, Nathalie; Levesque, Tania; Jacques, Frederic; Perron, Jean; Nigrovic, Peter A; Dieude, Melanie; Hebert, Marie-Josee; Gelb, Michael H; Boilard, Eric

2015-01-01

Microparticles, also called microvesicles, are submicron extracellular vesicles produced by plasma membrane budding and shedding recognized as key actors in numerous physio(patho)logical processes. Since they can be released by virtually any cell lineages and are retrieved in biological fluids, microparticles appear as potent biomarkers. However, the small dimensions of microparticles and soluble factors present in body fluids can considerably impede their quantification. Here, flow cytometry with improved methodology for microparticle resolution was used to detect microparticles of human and mouse species generated from platelets, red blood cells, endothelial cells, apoptotic thymocytes and cells from the male reproductive tract. A family of soluble proteins, the secreted phospholipases A2 (sPLA2), comprises enzymes concomitantly expressed with microparticles in biological fluids and that catalyze the hydrolysis of membrane phospholipids. As sPLA2 can hydrolyze phosphatidylserine, a phospholipid frequently used to assess microparticles, and might even clear microparticles, we further considered the impact of relevant sPLA2 enzymes, sPLA2 group IIA, V and X, on microparticle quantification. We observed that if enriched in fluids, certain sPLA2 enzymes impair the quantification of microparticles depending on the species studied, the source of microparticles and the means of detection employed (surface phosphatidylserine or protein antigen detection). This study provides analytical considerations for appropriate interpretation of microparticle cytofluorometric measurements in biological samples containing sPLA2 enzymes.

Stationary and oscillatory convection of binary fluids in a porous medium.

PubMed

Augustin, M; Umla, R; Huke, B; Lücke, M

2010-11-01

We investigate numerically stationary convection and traveling wave structures of binary fluid mixtures with negative separation ratio in the Rayleigh-Bénard system filled with a porous medium. The bifurcation behavior of these roll structures is elucidated as well as the properties of the velocity, temperature, and concentration fields. Moreover, we discuss lateral averaged currents of temperature and concentration. Finally, we investigate the influence of the Lewis number, of the separation ratio, and of the normalized porosity on the bifurcation branches.

Nanoscopic dynamics of phospholipid in unilamellar vesicles: Effect of gel to fluid phase transition

DOE PAGES

Sharma, V. K.; Mamontov, E.; Anunciado, D. B.; ...

2015-03-04

Dynamics of phospholipids in unilamellar vesicles (ULV) is of interest in biology, medical, and food sciences since these molecules are widely used as biocompatible agents and a mimic of cell membrane systems. We have investigated the nanoscopic dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipid in ULV as a function of temperature using elastic and quasielastic neutron scattering (QENS). The dependence of the signal on the scattering momentum transfer, which is a critical advantage of neutron scattering techniques, allows the detailed analysis of the lipid motions that cannot be carried out by other means. In agreement with a differential scanning calorimetry measurement, amore » sharp rise in the elastic scattering intensity below ca. 296 K indicates a phase transition from the high-temperature fluid phase to the low-temperature solid gel phase. The microscopic lipid dynamics exhibits qualitative differences between the solid gel phase (in a measurement at 280 K) and the fluid phase (in a measurement at a physiological temperature of 310 K). The data analysis invariably shows the presence of two distinct motions: the whole lipid molecule motion within a monolayer, or lateral diffusion, and the relatively faster internal motion of the DMPC molecule. The lateral diffusion of the whole lipid molecule is found to be Fickian in character, whereas the internal lipid motions are of localized character, consistent with the structure of the vesicles. The lateral motion slows down by an order of magnitude in the solid gel phase, whereas for the internal motion not only the time scale, but also the character of the motion changes upon the phase transition. In the solid gel phase, the lipids are more ordered and undergo uniaxial rotational motion. However, in the fluid phase, the hydrogen atoms of the lipid tails undergo confined translation diffusion rather than uniaxial rotational diffusion. The localized translational diffusion of the hydrogen atoms of the lipid tails is a manifestation of the flexibility of the chains acquired in the fluid phase. Because of this flexibility, both the local diffusivity and the confinement volume for the hydrogen atoms increase linearly from near the lipid s polar head group to the end of its hydrophobic tail. Our results present a quantitative and detailed picture of the effect of the gel-fluid phase transition on the nanoscopic lipid dynamics in ULV. Lastly, the data analysis approach developed here has a potential for probing the dynamic response of lipids to the presence of additional cell membrane components.« less

The onset of convection in a binary fluid mixture with temperature dependent viscosity and Coriolis force with Soret presence

NASA Astrophysics Data System (ADS)

Abidin, Nurul Hafizah Zainal; Mokhtar, Nor Fadzillah Mohd; Majid, Zanariah Abdul; Ghani, Siti Salwa Abd

2017-11-01

Temperature dependent viscosity and Coriolis force were applied to the steady Benard-Marangoni convection where the lower boundary of a horizontal layer of the binary mixture is heated from below and cooled from above. The purpose of this paper is to study in detail the onset of convection with these effects. Few cases of boundary conditions are studied which are rigid-rigid, rigid-free and free-free representing the lower-upper boundaries. A detailed numerical calculation of the marginal stability curves was performed by using the Galerkin method and it is showed that temperature dependent viscosity and Soret number destabilize the binary fluid layer system and Taylor number act oppositely.

Label free detection of phospholipids by infrared absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ahmed, Tahsin; Foster, Erick; Vigil, Genevieve; Khan, Aamir A.; Bohn, Paul; Howard, Scott S.

2014-08-01

We present our study on compact, label-free dissolved lipid sensing by combining capillary electrophoresis separation in a PDMS microfluidic chip online with mid-infrared (MIR) absorption spectroscopy for biomarker detection. On-chip capillary electrophoresis is used to separate the biomarkers without introducing any extrinsic contrast agent, which reduces both cost and complexity. The label free biomarker detection could be done by interrogating separated biomarkers in the channel by MIR absorption spectroscopy. Phospholipids biomarkers of degenerative neurological, kidney, and bone diseases are detectable using this label free technique. These phospholipids exhibit strong absorption resonances in the MIR and are present in biofluids including urine, blood plasma, and cerebrospinal fluid. MIR spectroscopy of a 12-carbon chain phosphatidic acid (PA) (1,2-dilauroyl-snglycero- 3-phosphate (sodium salt)) dissolved in N-methylformamide, exhibits a strong amide peak near wavenumber 1660 cm-1 (wavelength 6 μm), arising from the phosphate headgroup vibrations within a low-loss window of the solvent. PA has a similar structure to many important phospholipids molecules like phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and phosphatidylserine (PS), making it an ideal molecule for initial proof-of-concept studies. This newly proposed detection technique can lead us to minimal sample preparation and is capable of identifying several biomarkers from the same sample simultaneously.

Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi.

PubMed

Turk, Martina; Méjanelle, Laurence; Sentjurc, Marjeta; Grimalt, Joan O; Gunde-Cimerman, Nina; Plemenitas, Ana

2004-02-01

The halophilic melanized yeast-like fungi Hortaea werneckii, Phaeotheca triangularis, and the halotolerant Aureobasidium pullulans, isolated from salterns as their natural environment, were grown at different NaCl concentrations and their membrane lipid composition and fluidity were examined. Among sterols, besides ergosterol, which was the predominant one, 23 additional sterols were identified. Their total content did not change consistently or significantly in response to raised NaCl concentrations in studied melanized fungi. The major phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, followed by anionic phospholipids. The most abundant fatty acids in phospholipids contained C16 and C18 chain lengths with a high percentage of C18:2Delta9,12. Salt stress caused an increase in the fatty acid unsaturation in the halophilic H. werneckii and halotolerant A. pullulans but a slight decrease in halophilic P. triangularis. All the halophilic fungi maintained their sterol-to-phospholipid ratio at a significantly lower level than did the salt-sensitive Saccharomyces cerevisiae and halotolerant A. pullulans. Electron paramagnetic resonance (EPR) spectroscopy measurements showed that the membranes of all halophilic fungi were more fluid than those of the halotolerant A. pullulans and salt-sensitive S. cerevisiae, which is in good agreement with the lipid composition observed in this study.

Analysis of bronchoalveolar lavage fluid (Balf) from patients with adult respiratory distress syndrome (ARDS)

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

Henderson, R.F.; Baughman, R.P.; Waide, J.J.

1995-12-01

The pathogenesis of ARDS is largely unknown, but many factors are known to predispose one to ARDS: sepsis, aspiration of gastric contents, pneumonia, fracture, multiple transfusions, cardiopulmonary bypass, burn, dissemination intravascular coagulation, pulmonary contusion, near drowning, and pancreatitis. ARDS is characterized by severe hypoxemia, diffuse pulmonary infiltrates, and decreased pulmonary compliance. Current treatment methods still result in 50% mortality. Studies are underway at the University of Cincinnati to determine if treatment with a synthetic pulmonary surfactant, Exosurf{sup {reg_sign}} (contains dipalmitoyl phosphatidyl choline, Burroughs-Wellcome), improves the prognosis of these patients. BALF from these patients, before and after treatment, was analyzed tomore » determine if the treatment resulted in an increase in disaturated phospholipids (surfactant phospholipids) in the epithelial lining fluid and if the treatments reduced the concentration of markers of inflammation and toxicity in the BALF. This study indicates that the method of administering Exosurf{sup {reg_sign}} did not lead to an increase in surfactant lipid or protein in the bronchoalveolar region of the respiratory tract.« less

Elastic response of binary hard-sphere fluids

NASA Astrophysics Data System (ADS)

Rickman, J. M.; Ou-Yang, H. Daniel

2011-07-01

We derive expressions for the high-frequency, wave-number-dependent elastic constants of a binary hard-sphere fluid and employ Monte Carlo computer simulation to evaluate these constants in order to highlight the impact of composition and relative sphere diameter on the elastic response of this system. It is found that the elastic constant c11(k) exhibits oscillatory behavior as a function of k whereas the high-frequency shear modulus, for example, does not. This behavior is shown to be dictated by the angular dependence (in k⃗ space) of derivatives of the interatomic force at contact. The results are related to recent measurements of the compressibility of colloidal fluids in laser trapping experiments.

Turbidity of a binary fluid mixture: Determining eta

NASA Technical Reports Server (NTRS)

Jacobs, Donald T.

1994-01-01

A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to the critical point. By covering the range of reduced temperatures t is equivalent to (T-T(sub c))/T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Interpreting the turbidity correctly is important if future NASA flight experiments use turbidity as an indirect measurement of relative temperature in shuttle experiments on critical phenomena in fluids.

Membrane Modulates Affinity for Calcium Ion to Create an Apparent Cooperative Binding Response by Annexin a5

PubMed Central

Gauer, Jacob W.; Knutson, Kristofer J.; Jaworski, Samantha R.; Rice, Anne M.; Rannikko, Anika M.; Lentz, Barry R.; Hinderliter, Anne

2013-01-01

Isothermal titration calorimetry was used to characterize the binding of calcium ion (Ca2+) and phospholipid to the peripheral membrane-binding protein annexin a5. The phospholipid was a binary mixture of a neutral and an acidic phospholipid, specifically phosphatidylcholine and phosphatidylserine in the form of large unilamellar vesicles. To stringently define the mode of binding, a global fit of data collected in the presence and absence of membrane concentrations exceeding protein saturation was performed. A partition function defined the contribution of all heat-evolving or heat-absorbing binding states. We find that annexin a5 binds Ca2+ in solution according to a simple independent-site model (solution-state affinity). In the presence of phosphatidylserine-containing liposomes, binding of Ca2+ differentiates into two classes of sites, both of which have higher affinity compared with the solution-state affinity. As in the solution-state scenario, the sites within each class were described with an independent-site model. Transitioning from a solution state with lower Ca2+ affinity to a membrane-associated, higher Ca2+ affinity state, results in cooperative binding. We discuss how weak membrane association of annexin a5 prior to Ca2+ influx is the basis for the cooperative response of annexin a5 toward Ca2+, and the role of membrane organization in this response. PMID:23746516

Biomimetic materials for protein storage and transport

DOEpatents

Firestone, Millicent A [Elmhurst, IL; Laible, Philip D [Villa Park, IL

2012-05-01

The invention provides a method for the insertion of protein in storage vehicles and the recovery of the proteins from the vehicles, the method comprising supplying isolated protein; mixing the isolated protein with a fluid so as to form a mixture, the fluid comprising saturated phospholipids, lipopolymers, and a surfactant; cycling the mixture between a first temperature and a second temperature; maintaining the mixture as a solid for an indefinite period of time; diluting the mixture in detergent buffer so as to disrupt the composition of the mixture, and diluting to disrupt the fluid in its low viscosity state for removal of the guest molecules by, for example, dialysis, filtering or chromatography dialyzing/filtering the emulsified solid.

Hydrodynamical processes in coalescing binary stars

NASA Astrophysics Data System (ADS)

Lai, Dong

1994-01-01

Coalescing neutron star binaries are considered to be the most promising sources of gravitational waves that could be detected by the planned laser-interferometer LIGO/VIRGO detectors. Extracting gravity wave signals from noisy data requires accurate theoretical waveforms in the frequency range 10-1000 Hz end detailed understanding of the dynamics of the binary orbits. We investigate the quasi-equilibrium and dynamical tidal interactions in coalescing binary stars, with particular focus on binary neutron stars. We develop a new formalism to study the equilibrium and dynamics of fluid stars in binary systems. The stars are modeled as compressible ellipsoids, and satisfy polytropic equation of state. The hydrodynamic equations are reduced to a set of ordinary differential equations for the evolution of the principal axes and other global quantities. The equilibrium binary structure is determined by a set of algebraic equations. We consider both synchronized and nonsynchronized systems, obtaining the generalizations to compressible fluid of the classical results for the ellipsoidal binary configurations. Our method can be applied to a wide variety of astrophysical binary systems containing neutron stars, white dwarfs, main-sequence stars and planets. We find that both secular and dynamical instabilities can develop in close binaries. The quasi-static (secular) orbital evolution, as well as the dynamical evolution of binaries driven by viscous dissipation and gravitational radiation reaction are studied. The development of the dynamical instability accelerates the binary coalescence at small separation, leading to appreciable radial infall velocity near contact. We also study resonant excitations of g-mode oscillations in coalescing binary neutron stars. A resonance occurs when the frequency of the tidal driving force equals one of the intrinsic g-mode frequencies. Using realistic microscopic nuclear equations of state, we determine the g-modes in a cold neutron atar. Resonant excitations of these g-modes during the last few minutes of the binary coalescence result in energy transfer and angular momentum transfer from the binary orbit to the neutron star. Because of the weak coupling between the g-modes and the tidal potential, the induced orbital phase errors due to resonances are small. However, resonant excitations of the g-modes play an important role in the tidal heating of binary neutron stars.

Binary Mixture of Perfect Fluid and Dark Energy in Modified Theory of Gravity

NASA Astrophysics Data System (ADS)

Shaikh, A. Y.

2016-07-01

A self consistent system of Plane Symmetric gravitational field and a binary mixture of perfect fluid and dark energy in a modified theory of gravity are considered. The gravitational field plays crucial role in the formation of soliton-like solutions, i.e., solutions with limited total energy, spin, and charge. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., p = γρ with γ∈ [0, 1] whereas, the dark energy is considered to be either the quintessence like equation of state or Chaplygin gas. The exact solutions to the corresponding field equations are obtained for power-law and exponential volumetric expansion. The geometrical and physical parameters for both the models are studied.

Small-scale Geothermal Power Plants Using Hot Spring Water

NASA Astrophysics Data System (ADS)

Tosha, T.; Osato, K.; Kiuchi, T.; Miida, H.; Okumura, T.; Nakashima, H.

2013-12-01

The installed capacity of the geothermal power plants has been summed up to be about 515MW in Japan. However, the electricity generated by the geothermal resources only contributes to 0.2% of the whole electricity supply. After the catastrophic earthquake and tsunami devastated the Pacific coast of north-eastern Japan on Friday, March 11, 2011, the Japanese government is encouraging the increase of the renewable energy supply including the geothermal. It needs, however, more than 10 years to construct the geothermal power plant with more than 10MW capacity since the commencement of the development. Adding the problem of the long lead time, high temperature fluid is mainly observed in the national parks and the high quality of the geothermal resources is limited. On the other hand hot springs are often found. The utilisation of the low temperature hot water becomes worthy of notice. The low temperature hot water is traditionally used for bathing and there are many hot springs in Japan. Some of the springs have enough temperature and enthalpy to turn the geothermal turbine but a new technology of the binary power generation makes the lower temp fluid to generate electricity. Large power generators with the binary technology are already installed in many geothermal fields in the world. In the recent days small-scale geothermal binary generators with several tens to hundreds kW capacity are developed, which are originally used by the waste heat energy in an iron factory and so on. The newly developed binary unit is compact suitable for the installation in a Japanese inn but there are the restrictions for the temperature of the hot water and the working fluid. The binary power unit using alternatives for chlorofluorocarbon as the working fluid is relatively free from the restriction. KOBELCO, a company of the Kobe Steel Group, designed and developed the binary power unit with an alternative for chlorofluorocarbon. The unit has a 70 MW class electric generator. Three units have been installed in Obama Hot Spring area, Nagasaki Prefecture, where about 15,000 tonnes of hot water are produced in a day and more than 35% of the hot water flow directly to the sea. Another demonstration experiments are also conducted in several hot spring areas. In this study we will review several examples to utilise low temperature hot springs in Japan. Binary Power Unit at Obama (Fujino, 2013)

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.

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.

Stability of binaries. Part 1: Rigid binaries

NASA Astrophysics Data System (ADS)

Sharma, Ishan

2015-09-01

We consider the stability of binary asteroids whose members are possibly granular aggregates held together by self-gravity alone. A binary is said to be stable whenever each member is orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability test for rotating granular aggregates introduced by Sharma (Sharma, I. [2012]. J. Fluid Mech., 708, 71-99; Sharma, I. [2013]. Icarus, 223, 367-382; Sharma, I. [2014]. Icarus, 229, 278-294) to the case of binary systems comprised of rubble members. In part I, we specialize to the case of a binary with rigid members subjected to full three-dimensional perturbations. Finally, we employ the stability test to critically appraise shape models of four suspected binary systems, viz., 216 Kleopatra, 25143 Itokawa, 624 Hektor and 90 Antiope.

Dynamics of dense granular flows of small-and-large-grain mixtures in an ambient fluid.

PubMed

Meruane, C; Tamburrino, A; Roche, O

2012-08-01

Dense grain flows in nature consist of a mixture of solid constituents that are immersed in an ambient fluid. In order to obtain a good representation of these flows, the interaction mechanisms between the different constituents of the mixture should be considered. In this article, we study the dynamics of a dense granular flow composed of a binary mixture of small and large grains immersed in an ambient fluid. In this context, we extend the two-phase approach proposed by Meruane et al. [J. Fluid Mech. 648, 381 (2010)] to the case of flowing dense binary mixtures of solid particles, by including in the momentum equations a constitutive relation that describes the interaction mechanisms between the solid constituents in a dense regime. These coupled equations are solved numerically and validated by comparing the numerical results with experimental measurements of the front speed of gravitational granular flows resulting from the collapse, in ambient air or water, of two-dimensional granular columns that consisted of mixtures of small and large spherical particles of equal mass density. Our results suggest that the model equations include the essential features that describe the dynamics of grains flows of binary mixtures in an ambient fluid. In particular, it is shown that segregation of small and large grains can increase the front speed because of the volumetric expansion of the flow. This increase in flow speed is damped by the interaction forces with the ambient fluid, and this behavior is more pronounced in water than in air.

Enhanced bactericidal potency of nanoliposomes by modification of the fusion activity between liposomes and bacterium.

PubMed

Ma, Yufan; Wang, Zhao; Zhao, Wen; Lu, Tingli; Wang, Rutao; Mei, Qibing; Chen, Tao

2013-01-01

Pseudomonas aeruginosa represents a good model of antibiotic resistance. These organisms have an outer membrane with a low level of permeability to drugs that is often combined with multidrug efflux pumps, enzymatic inactivation of the drug, or alteration of its molecular target. The acute and growing problem of antibiotic resistance of Pseudomonas to conventional antibiotics made it imperative to develop new liposome formulations to overcome these mechanisms, and investigate the fusion between liposome and bacterium. The rigidity, stability and charge properties of phospholipid vesicles were modified by varying the cholesterol, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE), and negatively charged lipids 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol sodium salt (DMPG), 1,2-dimyristoyl-sn-glycero-3-phopho-L-serine sodium salt (DMPS), 1,2-dimyristoyl-sn-glycero-3-phosphate monosodium salt (DMPA), nature phosphatidylserine sodium salt from brain and nature phosphatidylinositol sodium salt from soybean concentrations in liposomes. Liposomal fusion with intact bacteria was monitored using a lipid-mixing assay. It was discovered that the fluid liposomes-bacterium fusion is not dependent on liposomal size and lamellarity. A similar degree of fusion was observed for liposomes with a particle size from 100 to 800 nm. The fluidity of liposomes is an essential pre-request for liposomes fusion with bacteria. Fusion was almost completely inhibited by incorporation of cholesterol into fluid liposomes. The increase in the amount of negative charges in fluid liposomes reduces fluid liposomes-bacteria fusion when tested without calcium cations due to electric repulsion, but addition of calcium cations brings the fusion level of fluid liposomes to similar or higher levels. Among the negative phospholipids examined, DMPA gave the highest degree of fusion, DMPS and DMPG had intermediate fusion levels, and PI resulted in the lowest degree of fusion. Furthermore, the fluid liposomal encapsulated tobramycin was prepared, and the bactericidal effect occurred more quickly when bacteria were cultured with liposomal encapsulated tobramycin. The bactericidal potency of fluid liposomes is dramatically enhanced with respect to fusion ability when the fusogenic lipid, DOPE, is included. Regardless of changes in liposome composition, fluid liposomes-bacterium fusion is universally enhanced by calcium ions. The information obtained in this study will increase our understanding of fluid liposomal action mechanisms, and help in optimizing the new generation of fluid liposomal formulations for the treatment of pulmonary bacterial infections.

Enhanced bactericidal potency of nanoliposomes by modification of the fusion activity between liposomes and bacterium

PubMed Central

Ma, Yufan; Wang, Zhao; Zhao, Wen; Lu, Tingli; Wang, Rutao; Mei, Qibing; Chen, Tao

2013-01-01

Background Pseudomonas aeruginosa represents a good model of antibiotic resistance. These organisms have an outer membrane with a low level of permeability to drugs that is often combined with multidrug efflux pumps, enzymatic inactivation of the drug, or alteration of its molecular target. The acute and growing problem of antibiotic resistance of Pseudomonas to conventional antibiotics made it imperative to develop new liposome formulations to overcome these mechanisms, and investigate the fusion between liposome and bacterium. Methods The rigidity, stability and charge properties of phospholipid vesicles were modified by varying the cholesterol, 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE), and negatively charged lipids 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol sodium salt (DMPG), 1,2-dimyristoyl-sn-glycero-3-phopho-L-serine sodium salt (DMPS), 1,2-dimyristoyl-sn-glycero-3-phosphate monosodium salt (DMPA), nature phosphatidylserine sodium salt from brain and nature phosphatidylinositol sodium salt from soybean concentrations in liposomes. Liposomal fusion with intact bacteria was monitored using a lipid-mixing assay. Results It was discovered that the fluid liposomes-bacterium fusion is not dependent on liposomal size and lamellarity. A similar degree of fusion was observed for liposomes with a particle size from 100 to 800 nm. The fluidity of liposomes is an essential pre-request for liposomes fusion with bacteria. Fusion was almost completely inhibited by incorporation of cholesterol into fluid liposomes. The increase in the amount of negative charges in fluid liposomes reduces fluid liposomes-bacteria fusion when tested without calcium cations due to electric repulsion, but addition of calcium cations brings the fusion level of fluid liposomes to similar or higher levels. Among the negative phospholipids examined, DMPA gave the highest degree of fusion, DMPS and DMPG had intermediate fusion levels, and PI resulted in the lowest degree of fusion. Furthermore, the fluid liposomal encapsulated tobramycin was prepared, and the bactericidal effect occurred more quickly when bacteria were cultured with liposomal encapsulated tobramycin. Conclusion The bactericidal potency of fluid liposomes is dramatically enhanced with respect to fusion ability when the fusogenic lipid, DOPE, is included. Regardless of changes in liposome composition, fluid liposomes-bacterium fusion is universally enhanced by calcium ions. The information obtained in this study will increase our understanding of fluid liposomal action mechanisms, and help in optimizing the new generation of fluid liposomal formulations for the treatment of pulmonary bacterial infections. PMID:23847417

Phospholipid order in gel- and fluid-phase cell-size liposomes measured by digitized video fluorescence polarization microscopy.

PubMed Central

Florine-Casteel, K

1990-01-01

Low-light digitized video fluorescence microscopy has been utilized to measure the steady-state polarized fluorescence from the membrane probe diphenylhexatriene (DPH) and its cationic and phosphatidylcholine derivatives 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and 2-[3-(diphenylhexatrienyl)propanoyl]-3-palmitoyl-L-alpha-phosphati dylcholine (DPH-PC), respectively, in cell-size (10-70 microns) unilamellar vesicles composed of gel-or fluid-phase phospholipid. Using an inverted microscope with epi-illumination optics and an intensified silicon intensified target camera interfaced to a minicomputer, fluorescence images of single vesicles were obtained at emission polarizer orientations of 0 degrees, 45 degrees, 90 degrees, and 135 degrees relative to the excitation light polarization direction. Fluorescence intensity ratios F90 degrees/F0 degrees (= F perpendicular/F parallel) and F135 degrees/F45 degrees were calculated on a pixel-by-pixel basis from digitized image pairs. Theoretical expressions were derived for collected polarized fluorescence as a function of position on the membrane surface as well as the degree of lipid order, in terms of the fluorophore's maximum angular motional freedom in the bilayer (identical to theta max), using a modification of the method of D. Axelrod (1979. Biophys. J. 26:557-574) together with the "wobbling-in-a-cone" model of probe rotational diffusion. Comparison of experimental polarization ratios with theoretical ratios yielded the following results. In gel-phase dipalmitoyl-phosphatidylcholine, the data for all three probes correspond to a model in which the cone angle theta max = 17 +/- 2 degrees and there exists a collective tilt of the phospholipid acyl chains of 30 degrees relative to the bilayer normal. In addition, approximately 5% of DPH and TMA-DPH molecules are aligned parallel to the plane of the bilayer. In fluid-phase palmitoyloleoyl-phosphatidylcholine, the data are well fit by models in which theta max = 60 +/- 2 degrees for DPH and DPH-PC and 32 +/- 4 degrees for TMA-DPH, with approximately 20% of DPH molecules and 10% of TMA-DPH molecules aligned parallel to the bilayer plane, and a net phospholipid tilt at or near the headgroup region of approximately 30 degrees. The results demonstrate that lipid order can be measured with a spatial resolution of approximately 1 micron2 in cell-size vesicles even with high aperture observation through a microscope. Images FIGURE 4 FIGURE 7 FIGURE 10 PMID:2393705

Heat and mass transfer in unsteady rotating fluid flow with binary chemical reaction and activation energy.

PubMed

Awad, Faiz G; Motsa, Sandile; Khumalo, Melusi

2014-01-01

In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous fluid in presence of binary chemical reaction and Arrhenius activation energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations.

Heat and Mass Transfer in Unsteady Rotating Fluid Flow with Binary Chemical Reaction and Activation Energy

PubMed Central

Awad, Faiz G.; Motsa, Sandile; Khumalo, Melusi

2014-01-01

In this study, the Spectral Relaxation Method (SRM) is used to solve the coupled highly nonlinear system of partial differential equations due to an unsteady flow over a stretching surface in an incompressible rotating viscous fluid in presence of binary chemical reaction and Arrhenius activation energy. The velocity, temperature and concentration distributions as well as the skin-friction, heat and mass transfer coefficients have been obtained and discussed for various physical parametric values. The numerical results obtained by (SRM) are then presented graphically and discussed to highlight the physical implications of the simulations. PMID:25250830

Supercritical Fluid Extraction of Bacterial and Archaeal Lipid Biomarkers from Anaerobically Digested Sludge

PubMed Central

Hanif, Muhammad; Atsuta, Yoichi; Fujie, Koichi; Daimon, Hiroyuki

2012-01-01

Supercritical fluid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. Bacterial RQ were determined using ultra performance liquid chromatography (UPLC). Determination of bacterial PLFA and archaeal PLEL was simultaneously performed using gas chromatography-mass spectrometry (GC-MS). The effects of pressure, temperature, and modifier concentration on the total amounts of RQ, PLFA, and PLEL were investigated by 23 experiments with five settings chosen for each variable. The optimal extraction conditions that were obtained through a multiple-response optimization included a pressure of 23.6 MPa, temperature of 77.6 °C, and 10.6% (v/v) of methanol as the modifier. Thirty nine components of microbial lipid biomarkers were identified in the anaerobically digested sludge. Overall, the SFE method proved to be more effective, rapid, and quantitative for simultaneously extracting bacterial and archaeal lipid biomarkers, compared to conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile. PMID:22489140

Adsorption of GST-PI3Kgamma at the air-buffer interface and at substrate and nonsubstrate phospholipid monolayers.

PubMed

Hermelink, Antje; Kirsch, Cornelia; Klinger, Reinhard; Reiter, Gerald; Brezesinski, Gerald

2009-02-01

The recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kgamma is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kgamma to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kgamma to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change.

Adsorption of GST-PI3Kγ at the Air-Buffer Interface and at Substrate and Nonsubstrate Phospholipid Monolayers

PubMed Central

Hermelink, Antje; Kirsch, Cornelia; Klinger, Reinhard; Reiter, Gerald; Brezesinski, Gerald

2009-01-01

The recruitment of phosphoinositide 3-kinase γ (PI3Kγ) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kγ is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kγ to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kγ to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change. PMID:19186139

Lethal H1N1 influenza A virus infection alters the murine alveolar type II cell surfactant lipidome.

PubMed

Woods, Parker S; Doolittle, Lauren M; Rosas, Lucia E; Joseph, Lisa M; Calomeni, Edward P; Davis, Ian C

2016-12-01

Alveolar type II (ATII) epithelial cells are the primary site of influenza virus replication in the distal lung. Development of acute respiratory distress syndrome in influenza-infected mice correlates with significant alterations in ATII cell function. However, the impact of infection on ATII cell surfactant lipid metabolism has not been explored. C57BL/6 mice were inoculated intranasally with influenza A/WSN/33 (H1N1) virus (10,000 plaque-forming units/mouse) or mock-infected with virus diluent. ATII cells were isolated by a standard lung digestion protocol at 2 and 6 days postinfection. Levels of 77 surfactant lipid-related compounds of known identity in each ATII cell sample were measured by ultra-high-performance liquid chromatography-mass spectrometry. In other mice, bronchoalveolar lavage fluid was collected to measure lipid and protein content using commercial assay kits. Relative to mock-infected animals, ATII cells from influenza-infected mice contained reduced levels of major surfactant phospholipids (phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine) but increased levels of minor phospholipids (phosphatidylserine, phosphatidylinositol, and sphingomyelin), cholesterol, and diacylglycerol. These changes were accompanied by reductions in cytidine 5'-diphosphocholine and 5'-diphosphoethanolamine (liponucleotide precursors for ATII cell phosphatidylcholine and phosphatidylethanolamine synthesis, respectively). ATII cell lamellar bodies were ultrastructurally abnormal after infection. Changes in ATII cell phospholipids were reflected in the composition of bronchoalveolar lavage fluid, which contained reduced amounts of phosphatidylcholine and phosphatidylglycerol but increased amounts of sphingomyelin, cholesterol, and protein. Influenza infection significantly alters ATII cell surfactant lipid metabolism, which may contribute to surfactant dysfunction and development of acute respiratory distress syndrome in influenza-infected mice. Copyright © 2016 the American Physiological Society.

Lethal H1N1 influenza A virus infection alters the murine alveolar type II cell surfactant lipidome

PubMed Central

Woods, Parker S.; Doolittle, Lauren M.; Rosas, Lucia E.; Joseph, Lisa M.; Calomeni, Edward P.

2016-01-01

Alveolar type II (ATII) epithelial cells are the primary site of influenza virus replication in the distal lung. Development of acute respiratory distress syndrome in influenza-infected mice correlates with significant alterations in ATII cell function. However, the impact of infection on ATII cell surfactant lipid metabolism has not been explored. C57BL/6 mice were inoculated intranasally with influenza A/WSN/33 (H1N1) virus (10,000 plaque-forming units/mouse) or mock-infected with virus diluent. ATII cells were isolated by a standard lung digestion protocol at 2 and 6 days postinfection. Levels of 77 surfactant lipid-related compounds of known identity in each ATII cell sample were measured by ultra-high-performance liquid chromatography-mass spectrometry. In other mice, bronchoalveolar lavage fluid was collected to measure lipid and protein content using commercial assay kits. Relative to mock-infected animals, ATII cells from influenza-infected mice contained reduced levels of major surfactant phospholipids (phosphatidylcholine, phosphatidylglycerol, and phosphatidylethanolamine) but increased levels of minor phospholipids (phosphatidylserine, phosphatidylinositol, and sphingomyelin), cholesterol, and diacylglycerol. These changes were accompanied by reductions in cytidine 5′-diphosphocholine and 5′-diphosphoethanolamine (liponucleotide precursors for ATII cell phosphatidylcholine and phosphatidylethanolamine synthesis, respectively). ATII cell lamellar bodies were ultrastructurally abnormal after infection. Changes in ATII cell phospholipids were reflected in the composition of bronchoalveolar lavage fluid, which contained reduced amounts of phosphatidylcholine and phosphatidylglycerol but increased amounts of sphingomyelin, cholesterol, and protein. Influenza infection significantly alters ATII cell surfactant lipid metabolism, which may contribute to surfactant dysfunction and development of acute respiratory distress syndrome in influenza-infected mice. PMID:27836900

Interfacial molecular interactions based on the conformation recognition between the insoluble antitumor drug AD-1 and DSPC.

PubMed

Yin, Tian; Cao, Xiuxiu; Liu, Xiaolin; Wang, Jian; Shi, Caihong; Su, Jia; Zhang, Yu; Gou, Jingxin; He, Haibing; Guo, Haiyan; Tang, Xing; Zhao, Yuqing

2016-10-01

In this study, molecular interactions between the anti-cancer agent 20(R)-25-methoxyl-dammarane-3β, 12β, 20-triol (AD-1) and phospholipid 1,2-Distearoyl-sn-glycero-3-phosphocholine (DSPC) were investigated using the Langmuir film balance technique. The characteristics of binary Langmuir monolayers consisting of DSPC and AD-1 were conducted on the basis of the surface pressure-area per molecule (π-A) isotherms. It was found that the drug was able to become efficiently inserted into preformed DSPC monolayers, indicating a preferential interaction between AD-1 and DSPC. For the examined lateral pressure at 20mN/m, the largest negative values of ΔGex were found for the AD-1/DSPC monolayer, which should be the most stable. Based on the calculated values of ΔGex, we found that the AD-1/DSPC systems exhibited the best mixed characteristics when the molar fraction of the AD-1 was 0.8; at that relative concentration, the AD-1 molecules can mix better and interact with the phospholipid molecules. In addition, the drug-DSPC binary supramolecular structure was also deposited on the mica plates as shown by atomic force microscopy (AFM). Finally, molecular docking calculations explained satisfactorily that, based on the conformations interactions (conformation recognition), even at an AD-1/DSPC molar ratio as high as 8:2, the interfacial stabilization of the AD-1/DSPC system was fairly strong due to hydrophobic interactions. A higher loading capacity of DSPC might be possible, as it is associated with a more flexible geometrical environment, which allows these supramolecular structures to accept larger increases in drug loading upon steric binding. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase-field-based lattice Boltzmann model for incompressible binary fluid systems with density and viscosity contrasts.

PubMed

Zu, Y Q; He, S

2013-04-01

A lattice Boltzmann model (LBM) is proposed based on the phase-field theory to simulate incompressible binary fluids with density and viscosity contrasts. Unlike many existing diffuse interface models which are limited to density matched binary fluids, the proposed model is capable of dealing with binary fluids with moderate density ratios. A new strategy for projecting the phase field to the viscosity field is proposed on the basis of the continuity of viscosity flux. The new LBM utilizes two lattice Boltzmann equations (LBEs): one for the interface tracking and the other for solving the hydrodynamic properties. The LBE for interface tracking can recover the Chan-Hilliard equation without any additional terms; while the LBE for hydrodynamic properties can recover the exact form of the divergence-free incompressible Navier-Stokes equations avoiding spurious interfacial forces. A series of 2D and 3D benchmark tests have been conducted for validation, which include a rigid-body rotation, stationary and moving droplets, a spinodal decomposition, a buoyancy-driven bubbly flow, a layered Poiseuille flow, and the Rayleigh-Taylor instability. It is shown that the proposed method can track the interface with high accuracy and stability and can significantly and systematically reduce the parasitic current across the interface. Comparisons with momentum-based models indicate that the newly proposed velocity-based model can better satisfy the incompressible condition in the flow fields, and eliminate or reduce the velocity fluctuations in the higher-pressure-gradient region and, therefore, achieve a better numerical stability. In addition, the test of a layered Poiseuille flow demonstrates that the proposed scheme for mixture viscosity performs significantly better than the traditional mixture viscosity methods.

Lateral Diffusion in a DMPC:DMPE-EO Binary Monolayer at the Air/Water Interface

NASA Astrophysics Data System (ADS)

Adalsteinsson, Thorsteinn; Porter, Ryan; Yu, Hyuk

2002-03-01

Polyethylene glycol tethered phospholipids (lipo-polymers) have recently attracted attention for improving the stability of liposomes and other bilayer delivery systems. Here, we report a study of surface pressure measurement and diffusion measurements of a probe lipid (NBD-DMPC) in a binary monolayer of DMPC and DMPE-EO at the Air/Water interface. Our findings are that the DMPE-EO lipo-polymer desorbs from the interface at intermediate surface pressures if the EO tail is sufficiently large (i.e. EO_45) and does not interfere with the diffusion of the probe thereafter. In the case where the EO tail is short (i.e. EO_17) the lipo-polymer retards the diffusion of the probe, but as the surface pressure increases, the diffusion behavior approaches that of pure DMPC monolayer independent of lipo-polymer. Thus, we conclude that the surface pressure and EO molar mass dependent desorption of the lipo-polymer modulates the probe diffusion retardation.

Crossover in growth laws for phase-separating binary fluids: molecular dynamics simulations.

PubMed

Ahmad, Shaista; Das, Subir K; Puri, Sanjay

2012-03-01

Pattern and dynamics during phase separation in a symmetrical binary (A+B) Lennard-Jones fluid are studied via molecular dynamics simulations after quenching homogeneously mixed critical (50:50) systems to temperatures below the critical one. The morphology of the domains, rich in A or B particles, is observed to be bicontinuous. The early-time growth of the average domain size is found to be consistent with the Lifshitz-Slyozov law for diffusive domain coarsening. After a characteristic time, dependent on the temperature, we find a clear crossover to an extended viscous hydrodynamic regime where the domains grow linearly with time. Pattern formation in the present system is compared with that in solid binary mixtures, as a function of temperature. Important results for the finite-size and temperature effects on the small-wave-vector behavior of the scattering function are also presented.

Uniform phases in fluids of hard isosceles triangles: One-component fluid and binary mixtures

NASA Astrophysics Data System (ADS)

Martínez-Ratón, Yuri; Díaz-De Armas, Ariel; Velasco, Enrique

2018-05-01

We formulate the scaled particle theory for a general mixture of hard isosceles triangles and calculate different phase diagrams for the one-component fluid and for certain binary mixtures. The fluid of hard triangles exhibits a complex phase behavior: (i) the presence of a triatic phase with sixfold symmetry, (ii) the isotropic-uniaxial nematic transition is of first order for certain ranges of aspect ratios, and (iii) the one-component system exhibits nematic-nematic transitions ending in critical points. We found the triatic phase to be stable not only for equilateral triangles but also for triangles of similar aspect ratios. We focus the study of binary mixtures on the case of symmetric mixtures: equal particle areas with aspect ratios (κi) symmetric with respect to the equilateral one, κ1κ2=3 . For these mixtures we found, aside from first-order isotropic-nematic and nematic-nematic transitions (the latter ending in a critical point): (i) a region of triatic phase stability even for mixtures made of particles that do not form this phase at the one-component limit, and (ii) the presence of a Landau point at which two triatic-nematic first-order transitions and a nematic-nematic demixing transition coalesce. This phase behavior is analogous to that of a symmetric three-dimensional mixture of rods and plates.

Microfluidic mixing using orbiting magnetic microbeads

NASA Astrophysics Data System (ADS)

Ballard, Matthew; Owen, Drew; Mao, Wenbin; Hesketh, Peter; Alexeev, Alexander

2013-11-01

Using three-dimensional simulations and experiments, we examine mixing in a microfluidic channel that incorporates a hybrid passive-active micromixer. The passive part of the mixer consists of a series of angled parallel ridges lining the top microchannel wall. The active component of the mixer is made up of microbeads rotating around small pillars on the bottom of the microchannel. In our simulations, we use a binary fluid lattice Boltzmann model to simulate the system and characterize the microfluidic mixing in the system. We consider the passive and active micromixers separately and evaluate their combined effect on the mixing of binary fluids. We compare our simulations with the experimental results obtained in a microchannel with magnetically actuated microbeads. Our findings guide the design of an efficient micromixer to be used in sampling in complex fluids. Financial support from NSF (CBET-1159726) is gratefully acknowledged.

A Review on Phytosome Technology as a Novel Approach to Improve The Bioavailability of Nutraceuticals

NASA Astrophysics Data System (ADS)

Amin, Tawheed; Bhat, Suman Vikas

2012-08-01

The bioavailability and absorption of water soluble phytoconstituents is erratic due to poor solubility of these constituents in gastrointestinal tract. This can be overcome by a novel delivery system known as phytosome technology in which water soluble phytoconstituents are allowed to react with phospholipids. For better and improved bioavailability, natural phytoconstituents must have a good balance between hydrophilicity (helps in dissolution in gastro-intestinal fluids) and hydrophobicity (helps to cross lipid rich cell membranes). This is achieved through phytosome technology. Phospholipids have a dual solubility and acts as an emulsifier. Phytosome technology acts as a bridge between novel and conventional delivery systems. Many products are available in the market based on this phytosome technology which include popular herbal extracts such as Ginkgo biloba, Silybum marianum, grape seed, olive oil flavonoids etc.

A method to generate small-scale, high-resolution sedimentary bedform architecture models representing realistic geologic facies

DOE PAGES

Meckel, T. A.; Trevisan, L.; Krishnamurthy, P. G.

2017-08-23

Small-scale (mm to m) sedimentary structures (e.g. ripple lamination, cross-bedding) have received a great deal of attention in sedimentary geology. The influence of depositional heterogeneity on subsurface fluid flow is now widely recognized, but incorporating these features in physically-rational bedform models at various scales remains problematic. The current investigation expands the capability of an existing set of open-source codes, allowing generation of high-resolution 3D bedform architecture models. The implemented modifications enable the generation of 3D digital models consisting of laminae and matrix (binary field) with characteristic depositional architecture. The binary model is then populated with petrophysical properties using a texturalmore » approach for additional analysis such as statistical characterization, property upscaling, and single and multiphase fluid flow simulation. One example binary model with corresponding threshold capillary pressure field and the scripts used to generate them are provided, but the approach can be used to generate dozens of previously documented common facies models and a variety of property assignments. An application using the example model is presented simulating buoyant fluid (CO 2) migration and resulting saturation distribution.« less

Electric Field Induced Interfacial Instabilities

NASA Technical Reports Server (NTRS)

Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-Lun; Onuki, Akira

1996-01-01

The study of the interface in a charge-free, nonpolar, critical and near-critical binary fluid in the presence of an externally applied electric field is presented. At sufficiently large fields, the interface between the two phases of the binary fluid should become unstable and exhibit an undulation with a predefined wavelength on the order of the capillary length. As the critical point is approached, this wavelength is reduced, potentially approaching length-scales such as the correlation length or critical nucleation radius. At this point the critical properties of the system may be affected. In zero gravity, the interface is unstable at all long wavelengths in the presence of a field applied across it. It is conjectured that this will cause the binary fluid to break up into domains small enough to be outside the instability condition. The resulting pattern formation, and the effects on the critical properties as the domains approach the correlation length are of acute interest. With direct observation, laser light scattering, and interferometry, the phenomena can be probed to gain further understanding of interfacial instabilities and the pattern formation which results, and dimensional crossover in critical systems as the critical fluctuations in a particular direction are suppressed by external forces.

A method to generate small-scale, high-resolution sedimentary bedform architecture models representing realistic geologic facies

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

Meckel, T. A.; Trevisan, L.; Krishnamurthy, P. G.

Small-scale (mm to m) sedimentary structures (e.g. ripple lamination, cross-bedding) have received a great deal of attention in sedimentary geology. The influence of depositional heterogeneity on subsurface fluid flow is now widely recognized, but incorporating these features in physically-rational bedform models at various scales remains problematic. The current investigation expands the capability of an existing set of open-source codes, allowing generation of high-resolution 3D bedform architecture models. The implemented modifications enable the generation of 3D digital models consisting of laminae and matrix (binary field) with characteristic depositional architecture. The binary model is then populated with petrophysical properties using a texturalmore » approach for additional analysis such as statistical characterization, property upscaling, and single and multiphase fluid flow simulation. One example binary model with corresponding threshold capillary pressure field and the scripts used to generate them are provided, but the approach can be used to generate dozens of previously documented common facies models and a variety of property assignments. An application using the example model is presented simulating buoyant fluid (CO 2) migration and resulting saturation distribution.« less

Different Effects of Long- and Short-Chain Ceramides on the Gel-Fluid and Lamellar-Hexagonal Transitions of Phospholipids: A Calorimetric, NMR, and X-Ray Diffraction Study

PubMed Central

Sot, Jesús; Aranda, Francisco J.; Collado, M.-Isabel; Goñi, Félix M.; Alonso, Alicia

2005-01-01

The effects on dielaidoylphosphatidylethanolamine (DEPE) bilayers of ceramides containing different N-acyl chains have been studied by differential scanning calorimetry small angle x-ray diffraction and 31P-NMR spectroscopy. N-palmitoyl (Cer16), N-hexanoyl (Cer6), and N-acetyl (Cer2) sphingosines have been used. Both the gel-fluid and the lamellar-inverted hexagonal transitions of DEPE have been examined in the presence of the various ceramides in the 0-25 mol % concentration range. Pure hydrated ceramides exhibit cooperative endothermic order-disorder transitions at 93°C (Cer16), 60°C (Cer6), and 54°C (Cer2). In DEPE bilayers, Cer16 does not mix with the phospholipid in the gel phase, giving rise to high-melting ceramide-rich domains. Cer16 favors the lamellar-hexagonal transition of DEPE, decreasing the transition temperature. Cer2, on the other hand, is soluble in the gel phase of DEPE, decreasing the gel-fluid and increasing the lamellar-hexagonal transition temperatures, thus effectively stabilizing the lamellar fluid phase. In addition, Cer2 was peculiar in that no equilibrium could be reached for the Cer2-DEPE mixture above 60°C, the lamellar-hexagonal transition shifting with time to temperatures beyond the instrumental range. The properties of Cer6 are intermediate between those of the other two, this ceramide decreasing both the gel-fluid and lamellar-hexagonal transition temperatures. Temperature-composition diagrams have been constructed for the mixtures of DEPE with each of the three ceramides. The different behavior of the long- and short-chain ceramides can be rationalized in terms of their different molecular geometries, Cer16 favoring negative curvature in the monolayers, thus inverted phases, and the opposite being true of the micelle-forming Cer2. These differences may be at the origin of the different physiological effects that are sometimes observed for the long- and short-chain ceramides. PMID:15695626

From Vesicles to Protocells: The Roles of Amphiphilic Molecules

PubMed Central

Sakuma, Yuka; Imai, Masayuki

2015-01-01

It is very challenging to construct protocells from molecular assemblies. An important step in this challenge is the achievement of vesicle dynamics that are relevant to cellular functions, such as membrane trafficking and self-reproduction, using amphiphilic molecules. Soft matter physics will play an important role in the development of vesicles that have these functions. Here, we show that simple binary phospholipid vesicles have the potential to reproduce the relevant functions of adhesion, pore formation and self-reproduction of vesicles, by coupling the lipid geometries (spontaneous curvatures) and the phase separation. This achievement will elucidate the pathway from molecular assembly to cellular life. PMID:25738256

Stability of binaries. Part II: Rubble-pile binaries

NASA Astrophysics Data System (ADS)

Sharma, Ishan

2016-10-01

We consider the stability of the binary asteroids whose members are granular aggregates held together by self-gravity alone. A binary is said to be stable whenever both its members are orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability analysis of Sharma (Sharma [2015] Icarus, 258, 438-453), that is applicable to binaries with rigid members, to the case of binary systems with rubble members. We employ volume averaging (Sharma et al. [2009] Icarus, 200, 304-322), which was inspired by past work on elastic/fluid, rotating and gravitating ellipsoids. This technique has shown promise when applied to rubble-pile ellipsoids, but requires further work to settle some of its underlying assumptions. The stability test is finally applied to some suspected binary systems, viz., 216 Kleopatra, 624 Hektor and 90 Antiope. We also see that equilibrated binaries that are close to mobilizing their maximum friction can sustain only a narrow range of shapes and, generally, congruent shapes are preferred.

Method and apparatus for removing non-condensible gas from a working fluid in a binary power system

DOEpatents

Mohr, Charles M.; Mines, Gregory L.; Bloomfield, K. Kit

2002-01-01

Apparatus for removing non-condensible gas from a working fluid utilized in a thermodynamic system comprises a membrane having an upstream side operatively connected to the thermodynamic system so that the upstream side of the membrane receives a portion of the working fluid. The first membrane separates the non-condensible gas from the working fluid. A pump operatively associated with the membrane causes the portion of the working fluid to contact the membrane and to be returned to the thermodynamic system.

Comparison of surfactant lipids between pleural and pulmonary lining fluids.

PubMed

Mills, P C; Chen, Y; Hills, Y C; Hills, B A

2006-01-01

Saturated phospholipids (PCs), particularly dipalmitoylphosphatidylcholine (DPPC), predominate in surfactant lining the alveoli, although little is known about the relationship between saturated and unsaturated PCs on the outer surface of the lung, the pleura. Seven healthy cats were anesthetized and a bronchoalveolar lavage (BAL) was performed, immediately followed by a pleural lavage (PL). Lipid was extracted from lavage fluid and then analyzed for saturated, primarily dipalmitoylphosphatidylcholine (DPPC), and unsaturated PC species using high-performance liquid chromatography (HPLC) with combined fluorescence and ultraviolet detection. Dilution of epithelial lining fluid (ELF) in lavage fluids was corrected for using the urea method. The concentration of DPPC in BAL fluid (85.3+/-15.7 microg/mL) was significantly higher (P=0.021) than unsaturated PCs ( approximately 40 microg/mL). However, unsaturated PCs ( approximately 34 microg/mL), particularly stearoyl-linoleoyl-phosphatidylcholine (SLPC; 17.4+/-6.8), were significantly higher (P=0.021) than DPPC (4.3+/-1.8 microg/mL) in PL fluid. These results show that unsaturated PCs appear functionally more important in the pleural cavity, which may have implications for surfactant replenishment following pleural disease or thoracic surgery.

Orbital Decay in Binaries with Evolved Stars

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Weinberg, Nevin N.; Troup, Nicholas; Majewski, Steven R.

2018-01-01

Two mechanisms are often invoked to explain tidal friction in binary systems. The ``dynamical tide” is the resonant excitation of internal gravity waves by the tide, and their subsequent damping by nonlinear fluid processes or thermal diffusion. The ``equilibrium tide” refers to non-resonant excitation of fluid motion in the star’s convection zone, with damping by interaction with the turbulent eddies. There have been numerous studies of these processes in main sequence stars, but less so on the subgiant and red giant branches. Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), we have performed calculations of both the dynamical and equilibrium tide processes for stars over a range of mass as the star’s cease core hydrogen burning and evolve to shell burning. Even for stars which had a radiative core on the main sequence, the dynamical tide may have very large amplitude in the newly radiative core in post-main sequence, giving rise to wave breaking. The resulting large dynamical tide dissipation rate is compared to the equilibrium tide, and the range of secondary masses and orbital periods over which rapid orbital decay may occur will be discussed, as well as applications to close APOGEE binaries.

Turbidity of a Binary Fluid Mixture: Determining Eta

NASA Technical Reports Server (NTRS)

Jacobs, Donald T.

1996-01-01

A ground based (1-g) experiment is in progress that will measure the turbidity of a density-matched, binary fluid mixture extremely close to its liquid-liquid critical point. By covering the range of reduced temperatures t equivalent to (T-T(sub c)) / T(sub c) from 10(exp -8) to 10(exp -2), the turbidity measurements will allow the critical exponent eta to be determined. No experiment has precisely determined a value of the critical exponent eta, yet its value is significant to theorists in critical phenomena. Relatively simple critical phenomena, as in the liquid-liquid system studied here, serve as model systems for more complex systems near a critical point.

Numerical simulation of three-component multiphase flows at high density and viscosity ratios using lattice Boltzmann methods

NASA Astrophysics Data System (ADS)

Haghani Hassan Abadi, Reza; Fakhari, Abbas; Rahimian, Mohammad Hassan

2018-03-01

In this paper, we propose a multiphase lattice Boltzmann model for numerical simulation of ternary flows at high density and viscosity ratios free from spurious velocities. The proposed scheme, which is based on the phase-field modeling, employs the Cahn-Hilliard theory to track the interfaces among three different fluid components. Several benchmarks, such as the spreading of a liquid lens, binary droplets, and head-on collision of two droplets in binary- and ternary-fluid systems, are conducted to assess the reliability and accuracy of the model. The proposed model can successfully simulate both partial and total spreadings while reducing the parasitic currents to the machine precision.

Utilizing chemo-mechanically functionalized oscillating fins to ``catch and release'' nanoparticles in binary flow

NASA Astrophysics Data System (ADS)

Liu, Ya; Ma, Yongting; Bhattacharya, Amitabh; Kuksenok, Olga; He, Ximin; Aizenberg, Joanna; Balazs, Anna

2013-11-01

In biomimetics, designing an effective ``catch and release'' device for the selective removal of target species from the surrounding solution is critical for developing autonomous sensors and sorters. Using computational simulation, we model an array of oscillating fins that are tethered on the floor of a microchannel and immersed in a binary-fluid stream. During the oscillation, the fins with the specific chemical wetting reach the upper fluid when they are upright and are entirely within the lower stream when they are tilted. We introduce specific adhesive interactions between the fins and particulates in the solution and determine conditions where the oscillating fins can selectively bind (``catch'') target nanoparticles within the upper fluid stream and then release these particles into the lower stream. We isolate the effects of chemical wetting on the fins (e.g., wetting contact angle between fins and fluid) and mechanical parameters (e.g., frequency of fins' oscillations) that lead to the efficient extraction of target species from the upper stream and placement into the lower fluid. Our understanding provides fundamental insights into the system's complex dynamics and mechanism for detection, separation, and purification of multi-component mixtures.

Thermodynamic scaling of the shear viscosity of Mie n-6 fluids and their binary mixtures

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

Delage-Santacreu, Stephanie; Galliero, Guillaume, E-mail: guillaume.galliero@univ-pau.fr; Hoang, Hai

2015-05-07

In this work, we have evaluated the applicability of the so-called thermodynamic scaling and the isomorph frame to describe the shear viscosity of Mie n-6 fluids of varying repulsive exponents (n = 8, 12, 18, 24, and 36). Furthermore, the effectiveness of the thermodynamic scaling to deal with binary mixtures of Mie n-6 fluids has been explored as well. To generate the viscosity database of these fluids, extensive non-equilibrium molecular dynamics simulations have been performed for various thermodynamic conditions. Then, a systematic approach has been used to determine the gamma exponent value (γ) characteristic of the thermodynamic scaling approach formore » each system. In addition, the applicability of the isomorph theory with a density dependent gamma has been confirmed in pure fluids. In both pure fluids and mixtures, it has been found that the thermodynamic scaling with a constant gamma is sufficient to correlate the viscosity data on a large range of thermodynamic conditions covering liquid and supercritical states as long as the density is not too high. Interestingly, it has been obtained that, in pure fluids, the value of γ is directly proportional to the repulsive exponent of the Mie potential. Finally, it has been found that the value of γ in mixtures can be deduced from those of the pure component using a simple logarithmic mixing rule.« less

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

Armstrong, Clare L; Barrett, M; Heiss, Arno

Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q || values (up to q || = 3 1), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer s hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree ofmore » molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be softer than fluid bilayers, but better ordered than bilayers in the gel phase.« less

Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids

NASA Astrophysics Data System (ADS)

Díaz-Herrera, Enrique; Ramírez-Santiago, Guillermo; Moreno Razo, José A.

2004-03-01

We have carried out extensive equilibrium MD simulations to investigate the Liquid-Vapor coexistence in partially miscible binary and ternary mixtures LJ fluids. We have studied in detail the time evolution of the density profiles and the interfacial properties in a temperature region of the phase diagram where the condensed phase is demixed. The composition of the mixtures are fixed, 50% for the binary mixture and 33.33% for the ternary mixture. The results of the simulations clearly indicate that in the range of temperatures 78 < T < 102 ^oK,--in the scale of argon-- the system evolves towards a metastable alternated liquid-liquid lamellar state in coexistence with its vapor phase. These states can be achieved if the initial configuration is fully disordered, that is, when the particles of the fluids are randomly placed on the sites of an FCC crystal or the system is completely mixed. As temperature decreases these states become very well defined and more stable in time. We find that below 90 ^oK, the alternated liquid-liquid lamellar state remains alive for 80 ns, in the scale of argon, the longest simulation we have carried out. Nonetheless, we believe that in this temperature region these states will be alive for even much longer times.

Solubility Limits in Lennard-Jones Mixtures: Effects of Disparate Molecule Geometries.

PubMed

Dyer, Kippi M; Perkyns, John S; Pettitt, B Montgomery

2015-07-23

In order to better understand general effects of the size and energy disparities between macromolecules and solvent molecules in solution, especially for macromolecular constructs self-assembled from smaller molecules, we use the first- and second-order exact bridge diagram extensions of the HNC integral equation theory to investigate single-component, binary, ternary, and quaternary mixtures of Lennard-Jones fluids. For pure fluids, we find that the HNCH3 bridge function integral equation (i.e., exact to third order in density) is necessary to quantitatively predict the pure gas and pure liquid sides of the coexistence region of the phase diagram of the Lennard-Jones fluid. For the mixtures, we find that the HNCH2 bridge function integral equation is sufficient to qualitatively predict solubility in the binary, ternary, and quaternary mixtures, up to the nominal solubility limit. The results, as limiting cases, should be useful to several problems, including accurate phase diagram predictions for complex mixtures, design of self-assembling nanostructures via solvent controls, and the solvent contributions to the conformational behavior of macromolecules in complex fluids.

Evaporative lithographic patterning of binary colloidal films.

PubMed

Harris, Daniel J; Conrad, Jacinta C; Lewis, Jennifer A

2009-12-28

Evaporative lithography offers a promising new route for patterning a broad array of soft materials. In this approach, a mask is placed above a drying film to create regions of free and hindered evaporation, which drive fluid convection and entrained particles to regions of highest evaporative flux. We show that binary colloidal films exhibit remarkable pattern formation when subjected to a periodic evaporative landscape during drying.

Subcritical and supercritical fuel injection and mixing in single and binary species systems

NASA Astrophysics Data System (ADS)

Roy, Arnab

Subcritical and supercritical fluid injection using a single round injector into a quiescent atmosphere comprising single and binary species was investigated using optical diagnostics. Different disintegration and mixing modes are expected for the two cases. In the binary species case, the atmosphere comprised an inert gas of a different composition than that of the injected fluid. In single species case, the atmosphere consisted of the same species as that of the injected fluid. Density values were quantified and density gradient profiles were inferred from the experimental data. A novel method was applied for the detection of detailed structures throughout the entire jet center plane. Various combinations of injectant and chamber conditions were tested and a wide range of density ratios were covered. The subcritical cases demonstrated the importance of surface tension and inertial forces, while the supercritical cases showed no signs of surface tension and, in most situations, resembled the mixing characteristics of a gaseous jet injected into a gaseous environment. A comparison between the single and binary species systems has also been provided. A detailed laser calibration procedure was undertaken to account for the laser absorption through the gas and liquid phases and for fluorescence in the non-linear excitation regime for high laser pulse energy. Core lengths were measured for binary species cases and correlated with visualization results. An eigenvalue approach was taken to determine the location of maximum gradients for determining the core length. Jet divergence angles were also calculated and were found to increase with chamber-to-injectant density ratio for both systems. A model was proposed for the spreading angle dependence on density ratio for both single and binary species systems and was compared to existing theoretical studies and experimental work. Finally, a linear stability analysis was performed for the jet injected into both subcritical and supercritical atmospheres. The subcritical cases showed good correlation with previous and current experimental results. The supercritical solutions, which have not yet been solved earlier by researchers, are found here through an asymptotic solution of the dispersion equation for exceedingly high Weber numbers.

Effect of single and binary combinations of plant-derived molluscicides on reproduction and survival of the snail Achatina fulica.

PubMed

Rao, I G; Singh, D K

2000-11-01

The effects of sublethal treatments (20% and 60% of LC(50)/24 h) with plant-derived molluscicides on the reproduction of the giant African snail Achatina fulica were studied. Azadirachta indica oil, Cedrus deodara oil, Allium sativum bulb powder, and Nerium indicum bark powder singly and binary combinations on reproduction and survival of A. fulica were investigated. Repeated treatment occurred on day 0, day 15, and day 30. These plant-derived molluscicides significantly reduced fecundity, egg viability, and survival of A. fulica within 15 days. Discontinuation of the treatments after day 30 did not lead to a recovery trend in the next 30 days. Day 0 sublethal treatment of all the molluscicides caused a maximum reduction in protein, amino acid, DNA, RNA, and phospholipid levels and simultaneous increase in lipid peroxidation in the ovotestis of treated A. fulica. It is believed that sublethal exposure of these molluscicides on snail reproduction is a complex process, involving more than one factor in reducing the reproductive capacity of A. fulica.

Generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture.

PubMed

Felderhof, B U

2017-08-21

The method employed by Einstein to derive his famous relation between the diffusion coefficient and the friction coefficient of a Brownian particle is used to derive a generalized Einstein relation for the mutual diffusion coefficient of a binary fluid mixture. The expression is compared with the one derived by de Groot and Mazur from irreversible thermodynamics and later by Batchelor for a Brownian suspension. A different result was derived by several other workers in irreversible thermodynamics. For a nearly incompressible solution, the generalized Einstein relation agrees with the expression derived by de Groot and Mazur. The two expressions also agree to first order in solute density. For a Brownian suspension, the result derived from the generalized Smoluchowski equation agrees with both expressions.

Calculation of Macrosegregation in an Ingot

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Maples, A. L.

1986-01-01

Report describes both two-dimensional theoretical model of macrosegregation (separating into regions of discrete composition) in solidification of binary alloy in chilled rectangular mold and interactive computer program embodying model. Model evolved from previous ones limited to calculating effects of interdendritic fluid flow on final macrosegregation for given input temperature field under assumption of no fluid in bulk melt.

Submicrosecond phospholipid dynamics using a long-lived fluorescence emission anisotropy probe.

PubMed Central

Davenport, L; Targowski, P

1996-01-01

The use of the long-lived fluorescence probe coronene (mean value of tau(FL) approximately 200 ns) is described for investigating submicrosecond lipid dynamics in DPPC model bilayer systems occurring below the lipid phase transition. Time-resolved fluorescence emission anisotropy decay profiles, measures as a function of increasing temperature toward the lipid-phase transition temperature (T(C)), for coronene-labeled DPPC small unilamellar vesicles (SUVs), are best described in most cases by three rotational decay components (phi(i = 3)). We have interpreted these data using two dynamic lipid bilayer models. In the first, a compartmental model, the long correlation time (phi(N)) is assigned to immobilized coronene molecules located in "gel-like" or highly ordered lipid phases (S-->1) of the bilayer, whereas a second fast rotational time (phi(F) approximately 2-5 ns) is associated with probes residing in more "fluid-like" regions (with corresponding lower ordering, S-->0). Interests here have focused on the origins of an intermediate correlation time (50-100 ns), the associated amplitude (beta(G)) of which increases with increasing temperature. Such behavior suggests a changing rotational environment surrounding the coronene molecules, arising from fluidization of gel lipid. The observed effective correlation time (phi(EFF)) thus reflects a discrete gel-fluid lipid exchange rate (k(FG)). A refinement of the compartmental model invokes a distribution of gel-fluid exchange rates (d(S,T)) corresponding to a distribution of lipid order parameters and is based on an adapted Landau expression for describing "gated" packing fluctuations. A total of seven parameters (five thermodynamic quantities, defined by the free energy versus temperature expansion; one gating parameter (gamma) defining a cooperative "melting" requirement; one limiting diffusion rate (or frequency factor: d(infinity))) suffice to predict complete anisotropy decay curves measured for coronene at several temperatures below the phospholipid T(C). The thermodynamic quantities are associated with the particular lipid of interest (in this case DPPC) and have been determined previously from ultrasound studies, thus representing fixed constants. Hence resolved variables are r(O), temperature-dependent gate parameters (gamma), and limiting diffusion rates (d(infinity)). This alternative distribution model is attractive because it provides a general probe-independent expression for distributed lipid fluctuation-induced probe rotational rates occurring within bilayer membranes below the phospholipid phase transition on the submicrosecond time scale. PMID:8889160

Binary Colloidal Alloy Test-3 and 4: Critical Point

NASA Technical Reports Server (NTRS)

Weitz, David A.; Lu, Peter J.

2007-01-01

Binary Colloidal Alloy Test - 3 and 4: Critical Point (BCAT-3-4-CP) will determine phase separation rates and add needed points to the phase diagram of a model critical fluid system. Crewmembers photograph samples of polymer and colloidal particles (tiny nanoscale spheres suspended in liquid) that model liquid/gas phase changes. Results will help scientists develop fundamental physics concepts previously cloaked by the effects of gravity.

The Probable Explanation for the Low Friction of Natural Joints.

PubMed

Pawlak, Zenon; Urbaniak, Wieslaw; Hagner-Derengowska, Magdalena; Hagner, Wojciech

2015-04-01

The surface of an articular cartilage, coated with phospholipid (PL) bilayers, plays an important role in its lubrication and movement. Intact (normal) and depleted surfaces of the joint were modelled and the pH influence on the surface interfacial energy, wettability and friction were investigated. In the experiments, the deterioration of the PL bilayer was controlled by its wettability and the applied friction. The surrounding fluid of an undamaged articular cartilage, the synovial fluid, has a pH value of approximately 7.4. Buffer solutions were formulated to represent the synovial fluid with various pH values. It was found that the surface interfacial energy was stabilised at its lowest values when the pH varied between 6.5 and 9.5. These results suggested that as the PL bilayers deteriorated, the hydration repulsion mechanism became less effective as friction increased. The decreased number of bilayers changed the wettability and lowered PL lubricant properties.

Automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid.

PubMed

Bradley, C A; Salhany, K E; Entman, S S; Aleshire, S L; Parl, F F

1987-01-01

We describe methods for automated enzymatic measurement of lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid. Phospholipase C (EC 3.1.4.3) and sphingomyelin phosphodiesterase (EC 3.1.4.12) are reacted with lecithin and sphingomyelin, respectively, to liberate phosphocholine. Phosphocholine is then reacted with alkaline phosphatase, choline oxidase, peroxidase, and 4-aminoantipyrine to form a colored complex, for which the absorbance at 500 nm is measured with a centrifugal analyzer. Phosphatidylglycerol is hydrolyzed by phospholipase D (EC 3.1.4.4) to form glycerol, which is subsequently reacted with ATP and NAD+ in the presence of glycerol kinase and glycerol-3-phosphate dehydrogenase to yield NADH. The absorbance of the NADH formed is measured at 340 nm. These methods provide a simple, rapid, and accurate alternative to thin-layer chromatography for determination of phospholipids in amniotic fluid for assessment of fetal lung maturity.

Lipid profiles of follicular fluid from cows submitted to ovarian superstimulation.

PubMed

Santos, P H; Fontes, P K; Franchi, F F; Nogueira, M F G; Belaz, K R A; Tata, A; Eberlin, M N; Sudano, M J; Barros, C M; Castilho, A C S

2017-05-01

Ovarian superstimulation with exogenous gonadotropins has been extensively used to produce in vivo-derived embryos for embryo transfer in cattle. This process modifies the antral follicle microenvironment and affects oocyte and embryo quality as well the differentiation of granulosa cells. Lipids play significant roles in the cell, such as energy storage, cell structure, and fine-tuning of the physical properties and functions of biological membranes. The phospholipid (PL) contents as well as the effects of superstimulatory treatments on the PL profile of follicular fluid from cows, however, remain unknown. Therefore, to gain insight into the effects of superstimulation with follicle-stimulating hormone (FSH; P-36 protocol) or FSH combined with equine chorionic gonadotropin (eCG; P-36/eCG protocol) on the profile and abundance of PL from cows submitted or not submitted to superstimulatory protocols, were treated with these two superstimulatory protocols. As a control, non-superstimulated cows were only submitted to estrous synchronization. The follicular fluid was aspirated, the remaining cells removed and the follicular fluid stored at -80 °C until extraction. The lipid screening was performed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and this technique allowed the identification of sphingomyelins (SM) and phosphatidylcholines (PC) and phosphoethanolamines (PE). The relative abundance of the ions observed in the three experimental groups was analyzed by multivariate and univariate statistical models. The phospholipid SM (16:0) and PC (36:4) and/or PC (34:1) were less (P < 0.05) abundant in the P-36 group compared to the control or P-36/eCG groups. However, the PC (34:2) was more (P < 0.05) abundant in both group of superstimulated cows compared to the control. In summary, ovarian superstimulation seems to modulate the PL content of bovine follicular fluid with a significant increase in PC (34:2), which jointly with others PC and SM, seems to offer a suitable biomarker involved with reproductive processes successful as ovary superstimulation response and embryo development. Copyright © 2017. Published by Elsevier Inc.

The John Charnley Award Paper. The role of joint fluid in the tribology of total joint arthroplasty.

PubMed

Mazzucco, Daniel; Spector, Myron

2004-12-01

The effect of joint fluid on the tribology (ie, lubrication, friction, and wear) of total hip arthroplasty has not yet been investigated adequately. In the current study, a friction assay was used to assess four hypotheses relating to the effect of human joint fluid and its principal components on the articulation of metal-on-polyethylene. First, joint fluid was found to produce a widely varying amount of friction between cobalt-chromium and polyethylene; this range exceeded the range produced when the articulation was lubricated by water or bovine serum. Second, it was shown that hyaluronic acid, phospholipid, albumin, and gamma-globulin were not acting as boundary lubricants, but that one or more other proteins (as yet unidentified) were responsible for reducing friction in this couple. Third, lower friction was found when oxidized zirconium alloy replaced cobalt-chromium as a bearing surface on polyethylene. Finally, a pilot study suggested that lubricin, which contributes to cartilage-on-cartilage lubrication, is not a protein responsible for the tribological variabiation found among joint fluid samples. The current study showed that joint fluid is a patient factor that influences the tribology of metal-on-polyethylene arthroplasty.

Differences in surfactant lipids collected from pleural and pulmonary lining fluids.

PubMed

Mills, Paul C; Chen, Yi; Hills, Yvette C; Hills, Brian A

2005-11-01

The type and relative importance of saturated and unsaturated phospholipid components of surfactant within the epithelial lining fluid (ELF) of the inner and outer surfaces of the lung is not known. Seven healthy dogs were anesthetized and a bronchoalveolar lavage (BAL) was performed, immediately followed by a pleural lavage (PL). Lipid was extracted from lavage fluid and then analyzed for saturated, primarily dipalmitoylphosphatidylcholine (DPPC), and unsaturated phosphatidylcholine (PC) species using high-performance liquid chromatography (HPLC) with combined fluorescence and ultraviolet detection. Dilution of ELF in lavage fluids was corrected for using the urea method. DPPC (494.7 +/- 213.9 microg/mL) was the predominant PC present in ELF collected from the alveolar surface. In contrast, significantly higher (p = 0.028) proportions of unsaturated PC species were measured in PL fluid (approximately 105 microg/mL), particularly stearoyl-linoleoyl-phosphatidylcholine (SLPC), which could not be measured in fluid collected from the alveoli, compared to DPPC (2.6 +/- 2.0 microg/mL). This study indicates that unsaturated PC species seem to be more important than saturated species, particularly DPPC, in the pleural cavity, which has implications for surfactant replenishment following pleural disease or thoracic surgery.

Role of surfactant protein A (SP-A)/lipid interactions for SP-A functions in the lung.

PubMed

Casals, C

2001-01-01

Surfactant protein A (SP-A), an oligomeric glycoprotein, is a member of a group of proteins named collectins that contain collagen-like and Ca(2+)-dependent carbohydrate recognition domains. SP-A interacts with a broad range of amphipathic lipids (glycerophospholipids, sphingophospholipids, glycosphingolipids, lipid A, and lipoglycans) that are present in surfactant or microbial membranes. This review summarizes SP-A/lipid interaction studies regarding the lipid system used (i.e., phospholipid vesicles, phospholipid monolayers, and lipids immobilized on silica or adsorbed on a solid support). The effect of calcium, ionic strength, and pH on the binding of SP-A to lipids and the subsequent lipid aggregation process is discussed. Current evidence suggests that hydrophobic-binding forces are involved in the peripherical association of SP-A to membranes. It is also proposed that fluid and liquid-ordered phase coexistence in surfactant membranes might favor partition of SP-A into those membranes. The binding of SP-A to surfactant membranes containing hydrophobic surfactant peptides makes possible the formation of a membrane reservoir in the alveolar fluid that is protected by SP-A against inactivation and improves the rate of surfactant film formation. In addition, the interaction of SP-A with membranes might enhance the affinity of SP-A for terminal carbohydrates of glycolipids or glycoproteins on the surface of invading microorganisms.

The economical utilization of geothermal energy

NASA Astrophysics Data System (ADS)

Rose, G.

1982-12-01

The geothermal energy which is stored in hot dry rock could be theoretically utilized for the generation of power. The hot-dry-rock procedure can provide a flow of hot water. The considered binary system can transform the obtained thermal energy into electrical energy. The system makes use of a Rankine cycle with a working fluid having a low boiling point. Heat from the hot water is transferred to the working fluid. The present investigation is concerned with the development of a method for the calculation of the entire process. The results obtained with the computational method are to provide a basis for the determination of the operational characteristics. The development method is used for the study of a process based on the use of carbon dioxide as working fluid. The economics of a use of the hot-dry-rock process with the binary system is also investigated. It is found that the considered procedure is not economical. Economical operation requires, in particular, hot water supplied at a much lower cost.

On the effect of serum on the transport of reactive oxygen species across phospholipid membranes.

PubMed

Szili, Endre J; Hong, Sung-Ha; Short, Robert D

2015-06-24

The transport of plasma generated reactive oxygen species (ROS) across a simple phospholipid membrane mimic of a (real) cell was investigated. Experiments were performed in cell culture media (Dulbecco's modified Eagle's medium, DMEM), with and without 10% serum. A (broad spectrum) ROS reporter dye, 2,7-dichlorodihydrofluorescein (DCFH), was used to detect the generation of ROS by a helium (He) plasma jet in DMEM using free DCFH and with DCFH encapsulated inside phospholipid membrane vesicles dispersed in DMEM. The authors focus on the concentration and on the relative rates (arbitrary units) for oxidation of DCFH [or the appearance of the oxidized product 2,7-dichlorofluorescein (DCF)] both in solution and within vesicles. In the first 1 h following plasma exposure, the concentration of free DCF in DMEM was ~15× greater in the presence of serum (cf. to the serum-free DMEM control). The DCF in vesicles was ~2× greater in DMEM containing serum compared to the serum-free DMEM control. These data show that serum enhances plasma ROS generation in DMEM. As expected, the role of the phospholipid membrane was to reduce the rate of oxidation of the encapsulated DCFH (with and without serum). And the efficiency of ROS transport into vesicles was lower in DMEM containing serum (at 4% efficiency) when compared to serum-free DMEM (at 32% efficiency). After 1 h, the rate of DCFH oxidation was found to have significantly reduced. Based upon a synthesis of these data with results from the open literature, the authors speculate on how the components of biological fluid and cellular membranes might affect the kinetics of consumption of plasma generated ROS.

Diffuse-Interface Methods in Fluid Mechanics

NASA Technical Reports Server (NTRS)

Anderson, D. M.; McFadden, G. B.; Wheeler, A. A.

1997-01-01

The authors review the development of diffuse-interface models of hydrodynamics and their application to a wide variety of interfacial phenomena. The authors discuss the issues involved in formulating diffuse-interface models for single-component and binary fluids. Recent applications and computations using these models are discussed in each case. Further, the authors address issues including sharp-interface analyses that relate these models to the classical free-boundary problem, related computational approaches to describe interfacial phenomena, and related approaches describing fully-miscible fluids.

Traveling waves and chaos in thermosolutal convection

NASA Technical Reports Server (NTRS)

Deane, A. E.; Toomre, J.; Knobloch, E.

1987-01-01

Numerical experiments on two-dimensional thermosolutal convection reveal oscillations in the form of traveling, standing, modulated, and chaotic waves. Transitions between these wave forms and steady convection are investigated and compared with theory. Such rich nonlinear behavior is possible in fluid layers of wide horizontal extent, and provides an explanation for waves observed in recent laboratory experiments with binary fluid mixtures.

Strong shock waves and nonequilibrium response in a one-dimensional gas: a Boltzmann equation approach.

PubMed

Hurtado, Pablo I

2005-10-01

We investigate the nonequilibrium behavior of a one-dimensional binary fluid on the basis of Boltzmann equation, using an infinitely strong shock wave as probe. Density, velocity, and temperature profiles are obtained as a function of the mixture mass ratio mu. We show that temperature overshoots near the shock layer, and that heavy particles are denser, slower, and cooler than light particles in the strong nonequilibrium region around the shock. The shock width omega(mu), which characterizes the size of this region, decreases as omega(mu) approximately mu(1/3) for mu-->0. In this limit, two very different length scales control the fluid structure, with heavy particles equilibrating much faster than light ones. Hydrodynamic fields relax exponentially toward equilibrium: phi(chi) approximately exp[-chi/lambda]. The scale separation is also apparent here, with two typical scales, lambda1 and lambda2, such that lambda1 approximately mu(1/2 as mu-->0, while lambda2, which is the slow scale controlling the fluid's asymptotic relaxation, increases to a constant value in this limit. These results are discussed in light of recent numerical studies on the nonequilibrium behavior of similar one-dimensional binary fluids.

Phase transitions in four-dimensional binary hard hypersphere mixtures

NASA Astrophysics Data System (ADS)

Bishop, Marvin; Whitlock, Paula A.

2013-02-01

Previous Monte Carlo investigations of binary hard hyperspheres in four-dimensional mixtures are extended to higher densities where the systems may solidify. The ratios of the diameters of the hyperspheres examined were 0.4, 0.5, and 0.6. Only the 0.4 system shows a clear two phase, solid-liquid transition and the larger component solidifies into a D4 crystal state. Its pair correlation function agrees with that of a one component fluid at an appropriately scaled density. The 0.5 systems exhibit states that are a mix of D4 and A4 regions. The 0.6 systems behave similarly to a jammed state rather than solidifying into a crystal. No demixing into two distinct fluid phases was observed for any of the simulations.

Dynamical and phase behavior of a phospholipid membrane altered by an antimicrobial peptide at low concentration

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

Mamontov, Eugene; Tyagi, M.; Qian, Shuo

Here we discuss that the mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature nomore » longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides.« less

Dynamical and phase behavior of a phospholipid membrane altered by an antimicrobial peptide at low concentration

DOE PAGES

Mamontov, Eugene; Tyagi, M.; Qian, Shuo; ...

2016-05-27

Here we discuss that the mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature nomore » longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides.« less

Novel Keto-phospholipids Are Generated by Monocytes and Macrophages, Detected in Cystic Fibrosis, and Activate Peroxisome Proliferator-activated Receptor-γ*

PubMed Central

Hammond, Victoria J.; Morgan, Alwena H.; Lauder, Sarah; Thomas, Christopher P.; Brown, Sarah; Freeman, Bruce A.; Lloyd, Clare M.; Davies, Jane; Bush, Andrew; Levonen, Anna-Liisa; Kansanen, Emilia; Villacorta, Luis; Chen, Y. Eugene; Porter, Ned; Garcia-Diaz, Yoel M.; Schopfer, Francisco J.; O'Donnell, Valerie B.

2012-01-01

12/15-Lipoxygenases (LOXs) in monocytes and macrophages generate novel phospholipid-esterified eicosanoids. Here, we report the generation of two additional families of related lipids comprising 15-ketoeicosatetraenoic acid (KETE) attached to four phosphatidylethanolamines (PEs). The lipids are generated basally by 15-LOX in IL-4-stimulated monocytes, are elevated on calcium mobilization, and are detected at increased levels in bronchoalveolar lavage fluid from cystic fibrosis patients (3.6 ng/ml of lavage). Murine peritoneal macrophages generate 12-KETE-PEs, which are absent in 12/15-LOX-deficient mice. Inhibition of 15-prostaglandin dehydrogenase prevents their formation from exogenous 15-hydroxyeicosatetraenoic acid-PE in human monocytes. Both human and murine cells also generated analogous hydroperoxyeicosatetraenoic acid-PEs. The electrophilic reactivity of KETE-PEs is shown by their Michael addition to glutathione and cysteine. Lastly, both 15-hydroxyeicosatetraenoic acid-PE and 15-KETE-PE activated peroxisome proliferator-activated receptor-γ reporter activity in macrophages in a dose-dependent manner. In summary, we demonstrate novel peroxisome proliferator-activated receptor-γ-activating oxidized phospholipids generated enzymatically by LOX and 15-prostaglandin dehydrogenase in primary monocytic cells and in a human Th2-related lung disease. The lipids are a new family of bioactive mediators from the 12/15-LOX pathway that may contribute to its known anti-inflammatory actions in vivo. PMID:23060450

Novel keto-phospholipids are generated by monocytes and macrophages, detected in cystic fibrosis, and activate peroxisome proliferator-activated receptor-γ.

PubMed

Hammond, Victoria J; Morgan, Alwena H; Lauder, Sarah; Thomas, Christopher P; Brown, Sarah; Freeman, Bruce A; Lloyd, Clare M; Davies, Jane; Bush, Andrew; Levonen, Anna-Liisa; Kansanen, Emilia; Villacorta, Luis; Chen, Y Eugene; Porter, Ned; Garcia-Diaz, Yoel M; Schopfer, Francisco J; O'Donnell, Valerie B

2012-12-07

12/15-Lipoxygenases (LOXs) in monocytes and macrophages generate novel phospholipid-esterified eicosanoids. Here, we report the generation of two additional families of related lipids comprising 15-ketoeicosatetraenoic acid (KETE) attached to four phosphatidylethanolamines (PEs). The lipids are generated basally by 15-LOX in IL-4-stimulated monocytes, are elevated on calcium mobilization, and are detected at increased levels in bronchoalveolar lavage fluid from cystic fibrosis patients (3.6 ng/ml of lavage). Murine peritoneal macrophages generate 12-KETE-PEs, which are absent in 12/15-LOX-deficient mice. Inhibition of 15-prostaglandin dehydrogenase prevents their formation from exogenous 15-hydroxyeicosatetraenoic acid-PE in human monocytes. Both human and murine cells also generated analogous hydroperoxyeicosatetraenoic acid-PEs. The electrophilic reactivity of KETE-PEs is shown by their Michael addition to glutathione and cysteine. Lastly, both 15-hydroxyeicosatetraenoic acid-PE and 15-KETE-PE activated peroxisome proliferator-activated receptor-γ reporter activity in macrophages in a dose-dependent manner. In summary, we demonstrate novel peroxisome proliferator-activated receptor-γ-activating oxidized phospholipids generated enzymatically by LOX and 15-prostaglandin dehydrogenase in primary monocytic cells and in a human Th2-related lung disease. The lipids are a new family of bioactive mediators from the 12/15-LOX pathway that may contribute to its known anti-inflammatory actions in vivo.

Effect of phospholipid-based formulations of Boswellia serrata extract on the solubility, permeability, and absorption of the individual boswellic acid constituents present.

PubMed

Hüsch, Jan; Gerbeth, Kathleen; Fricker, Gert; Setzer, Constanze; Zirkel, Jürgen; Rebmann, Herbert; Schubert-Zsilavecz, Manfred; Abdel-Tawab, Mona

2012-10-26

Boswellia serrata gum resin extracts are used widely for the treatment of inflammatory diseases. However, very low concentrations in the plasma and brain were observed for the boswellic acids (1-6, the active constituents of B. serrata). The present study investigated the effect of phospholipids alone and in combination with common co-surfactants (e.g., Tween 80, vitamin E-TPGS, pluronic f127) on the solubility of 1-6 in physiologically relevant media and on the permeability in the Caco-2 cell model. Because of the high lipophilicity of 1-6, the permeability experiments were adapted to physiological conditions using modified fasted state simulated intestinal fluid as apical (donor) medium and 4% bovine serum albumin in the basolateral (receiver) compartment. A formulation composed of extract/phospholipid/pluronic f127 (1:1:1 w/w/w) increased the solubility of 1-6 up to 54 times compared with the nonformulated extract and exhibited the highest mass net flux in the permeability tests. The oral administration of this formulation to rats (240 mg/kg) resulted in 26 and 14 times higher plasma levels for 11-keto-β-boswellic acid (1) and acetyl-11-keto-β-boswellic acid (2), respectively. In the brain, five times higher levels for 2 compared to the nonformulated extract were determined 8 h after oral administration.

Effects of smoke inhalation on alveolar surfactant subtypes in mice.

PubMed Central

Oulton, M. R.; Janigan, D. T.; MacDonald, J. M.; Faulkner, G. T.; Scott, J. E.

1994-01-01

The effects of smoke inhalation on alveolar surfactant subtypes were examined in mice exposed for 30 minutes to smoke generated from the burning of a flexible polyurethane foam. At 4 or 12 hours after the exposure, three surfactant pellets, P10, P60, and P100, and a supernatant, S100, were prepared by sequential centrifugation of lavage fluids at 10,000 g for 30 minutes (P10), 60,000 g for 60 minutes (P60), and 100,000 g for 15 hours (P100 and S100). Phospholipid analysis and electron microscopy were performed on each fraction. Smoke exposure dramatically altered the normal distributions of these fractions: it significantly increased the phospholipid content of the heavier subtype, P10, which is thought to represent newly secreted surfactant; had no effect on the intermediate form, P60; and dramatically increased the phospholipid content (approximately fivefold) of the lighter subtypes, P100 and S100, which are believed to represent catabolic end-products of alveolar surfactant. Only P100 was structurally altered by the smoke. These results represent alterations of the normal metabolic processing of alveolar surfactant. Whereas the mechanism is yet to be defined, it seems to involve a small but significant increase in the newly secreted surfactant, as well as an excessively high accumulation of the structurally altered catabolic forms of the secreted surfactant. Images Figure 3 PMID:7943183

Static and dynamic microscopy of the chemical stability and aggregation state of silver nanowires in components of murine pulmonary surfactant

PubMed Central

Theodorou, Ioannis G.; Botelho, Danielle; Schwander, Stephan; Zhang, Junfeng (Jim); Chung, Kian Fan; Tetley, Teresa D.; Shaffer, Milo S. P.; Gow, Andrew; Ryan, Mary P.; Porter, Alexandra E.

2016-01-01

The increase of production volumes of silver nanowires (AgNWs) and of consumer products incorporating them, may lead to increased health risks from occupational and public exposures. There is currently limited information about the putative toxicity of AgNWs upon inhalation, and incomplete understanding of the properties that control their bioreactivity. The lung lining fluid (LLF), which contains phospholipids and surfactant proteins, represents a first contact site with the respiratory system. In this work, the impact of Dipalmitoylphosphatidylcholine (DPPC), Curosurf® and murine LLF on the stability of AgNWs was examined. Both the phospholipid and protein components of the LLF modified the dissolution kinetics of AgNWs, due to the formation of a lipid corona or aggregation of the AgNWs. Moreover, the hydrophilic, but neither the hydrophobic surfactant proteins nor the phospholipids, induced agglomeration of the AgNWs. Finally, the generation of a secondary population of nano-silver was observed and attributed to the reduction of Ag+ ions by the surface capping of the AgNWs. Our findings highlight that combinations of spatially resolved dynamic and static techniques are required to develop a holistic understanding of which parameters govern AgNW behavior at the point of exposure and to accurately predict their risks on human health and the environment. PMID:26061974

The use of natural and synthetic phospholipids as pharmaceutical excipients*

PubMed Central

van Hoogevest, Peter; Wendel, Armin

2014-01-01

In pharmaceutical formulations, phospholipids obtained from plant or animal sources and synthetic phospholipids are used. Natural phospholipids are purified from, e.g., soybeans or egg yolk using non-toxic solvent extraction and chromatographic procedures with low consumption of energy and minimum possible waste. Because of the use of validated purification procedures and sourcing of raw materials with consistent quality, the resulting products differing in phosphatidylcholine content possess an excellent batch to batch reproducibility with respect to phospholipid and fatty acid composition. The natural phospholipids are described in pharmacopeias and relevant regulatory guidance documentation of the Food and Drug Administration (FDA) and European Medicines Agency (EMA). Synthetic phospholipids with specific polar head group, fatty acid composition can be manufactured using various synthesis routes. Synthetic phospholipids with the natural stereochemical configuration are preferably synthesized from glycerophosphocholine (GPC), which is obtained from natural phospholipids, using acylation and enzyme catalyzed reactions. Synthetic phospholipids play compared to natural phospholipid (including hydrogenated phospholipids), as derived from the number of drug products containing synthetic phospholipids, a minor role. Only in a few pharmaceutical products synthetic phospholipids are used. Natural phospholipids are used in oral, dermal, and parenteral products including liposomes. Natural phospholipids instead of synthetic phospholipids should be selected as phospholipid excipients for formulation development, whenever possible, because natural phospholipids are derived from renewable sources and produced with more ecologically friendly processes and are available in larger scale at relatively low costs compared to synthetic phospholipids. Practical applications: For selection of phospholipid excipients for pharmaceutical formulations, natural phospholipids are preferred compared to synthetic phospholipids because they are available at large scale with reproducible quality at lower costs of goods. They are well accepted by regulatory authorities and are produced using less chemicals and solvents at higher yields. In order to avoid scale up problems during pharmaceutical development and production, natural phospholipid excipients instead of synthetic phospholipids should be selected whenever possible. PMID:25400504

Optical Study of the Critical Behaviour of Pure Fluids and Binary Mixtures.

NASA Astrophysics Data System (ADS)

Narger, Ulrike

1990-01-01

Optical techniques were used to study the critical behaviour of the pure fluids CHF_3, CClF_3 and Xe, and binary mixtures He-Xe and nicotine + water. We find that for all these substances, the order parameter is described by a power law in the reduced temperature t = (T _{c} - T)/T_{c} with a leading exponent beta = 0.327 +/- 0.002. Also, we determine the first correction to scaling exponent to be Delta = 0.43 +/- 0.02 for the pure fluids and Delta = 0.50 +/- 0.02 for the He-Xe system. The coexistence curve diameter in CHF _3 and CClF_3 exhibits a deviation from recti-linear diameter, in agreement with a modern theory which interprets this behaviour as resulting from three-body effects. In contrast, no such deviation is observed in Xe where, according to that theory, it should be more pronounced than in other substances. In the polar fluid CHF_3, the order parameter, isothermal compressibility and the chemical potential along the critical isotherm were simultaneously measured in the same experiment in an effort to ensure self-consistency of the results. From the data, two amplitude ratios which are predicted to be universal are determined: Gamma_sp{0}{+} /Gamma_sp{0}{ -} = 4.8 +/- 0.6 and D_0 Gamma_sp{0}{+ } B_sp{0}{delta-1} = 1.66 +/- 0.14. In the binary liquid system nicotine + water, the diffusivity was measured both by light scattering and by interferometry. The results agree qualitatively, but differ by a factor of ~2. From the light scattering data, the critical exponent of the viscosity is found to be z_{eta } = 0.044 +/- 0.008. The interferometric experiments on Xe and He-Xe furnish a direct way to measure the effects of wetting: From the data, the exponent of the surface tension is found to be n = 1.24 +/- 0.06. The similarity of the order parameter and compressibility in Xe and a He-Xe mixture containing 5% He indicate that the phase transition in this He-Xe mixture is of the liquid -gas type rather than the binary liquid type.

Structure, thermodynamics, and solubility in tetromino fluids.

PubMed

Barnes, Brian C; Siderius, Daniel W; Gelb, Lev D

2009-06-16

To better understand the self-assembly of small molecules and nanoparticles adsorbed at interfaces, we have performed extensive Monte Carlo simulations of a simple lattice model based on the seven hard "tetrominoes", connected shapes that occupy four lattice sites. The equations of state of the pure fluids and all of the binary mixtures are determined over a wide range of density, and a large selection of multicomponent mixtures are also studied at selected conditions. Calculations are performed in the grand canonical ensemble and are analogous to real systems in which molecules or nanoparticles reversibly adsorb to a surface or interface from a bulk reservoir. The model studied is athermal; objects in these simulations avoid overlap but otherwise do not interact. As a result, all of the behavior observed is entropically driven. The one-component fluids all exhibit marked self-ordering tendencies at higher densities, with quite complex structures formed in some cases. Significant clustering of objects with the same rotational state (orientation) is also observed in some of the pure fluids. In all of the binary mixtures, the two species are fully miscible at large scales, but exhibit strong species-specific clustering (segregation) at small scales. This behavior persists in multicomponent mixtures; even in seven-component mixtures of all the shapes there is significant association between objects of the same shape. To better understand these phenomena, we calculate the second virial coefficients of the tetrominoes and related quantities, extract thermodynamic volume of mixing data from the simulations of binary mixtures, and determine Henry's law solubilities for each shape in a variety of solvents. The overall picture obtained is one in which complementarity of both the shapes of individual objects and the characteristic structures of different fluids are important in determining the overall behavior of a fluid of a given composition, with sometimes counterintuitive results. Finally, we note that no sharp phase transitions are observed but that this appears to be due to the small size of the objects considered. It is likely that complex phase behavior may be found in systems of larger polyominoes.

Large effect of membrane tension on the fluid-solid phase transitions of two-component phosphatidylcholine vesicles.

PubMed

Chen, Dong; Santore, Maria M

2014-01-07

Model phospholipid membranes and vesicles have long provided insight into the nature of confined materials and membranes while also providing a platform for drug delivery. The rich thermodynamic behavior and interesting domain shapes in these membranes have previously been mapped in extensive studies that vary temperature and composition; however, the thermodynamic impact of tension on bilayers has been restricted to recent reports of subtly reduced fluid-fluid transition temperatures. In two-component phosphatidylcholine unilamellar vesicles [1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)], we report a dramatic influence of tension on the fluid-solid transition and resulting phases: At fixed composition, systematic variations in tension produce differently shaped solid domains (striped or irregular hexagons), shift fluid-solid transition temperatures, and produce a triple-point-like intersection of coexistence curves at elevated tensions, about 3 mN/m for 30% DOPC/70% DPPC. Tension therefore represents a potential switch of microstructure in responsive engineered materials; it is an important morphology-determining variable in confined systems, and, in biological membranes, it may provide a means to regulate dynamic structure.

Viscous fingering with partially miscible fluids

NASA Astrophysics Data System (ADS)

Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

2017-10-01

Viscous fingering—the fluid-mechanical instability that takes place when a low-viscosity fluid displaces a high-viscosity fluid—has traditionally been studied under either fully miscible or fully immiscible fluid systems. Here we study the impact of partial miscibility (a common occurrence in practice) on the fingering dynamics. Through a careful design of the thermodynamic free energy of a binary mixture, we develop a phase-field model of fluid-fluid displacements in a Hele-Shaw cell for the general case in which the two fluids have limited (but nonzero) solubility into one another. We show, by means of high-resolution numerical simulations, that partial miscibility exerts a powerful control on the degree of fingering: fluid dissolution hinders fingering while fluid exsolution enhances fingering. We also show that, as a result of the interplay between compositional exchange and the hydrodynamic pattern-forming process, stronger fingering promotes the system to approach thermodynamic equilibrium more quickly.

Monte Carlo study of four dimensional binary hard hypersphere mixtures

NASA Astrophysics Data System (ADS)

Bishop, Marvin; Whitlock, Paula A.

2012-01-01

A multithreaded Monte Carlo code was used to study the properties of binary mixtures of hard hyperspheres in four dimensions. The ratios of the diameters of the hyperspheres examined were 0.4, 0.5, 0.6, and 0.8. Many total densities of the binary mixtures were investigated. The pair correlation functions and the equations of state were determined and compared with other simulation results and theoretical predictions. At lower diameter ratios the pair correlation functions of the mixture agree with the pair correlation function of a one component fluid at an appropriately scaled density. The theoretical results for the equation of state compare well to the Monte Carlo calculations for all but the highest densities studied.

Modeling pinchoff and reconnection in a Hele-Shaw cell. I. The models and their calibration

NASA Astrophysics Data System (ADS)

Lee, Hyeong-Gi; Lowengrub, J. S.; Goodman, J.

2002-02-01

This is the first paper in a two-part series in which we analyze two model systems to study pinchoff and reconnection in binary fluid flow in a Hele-Shaw cell with arbitrary density and viscosity contrast between the components. The systems stem from a simplification of a general system of equations governing the motion of a binary fluid (NSCH model [Lowengrub and Truskinovsky, Proc. R. Soc. London, Ser. A 454, 2617 (1998)]) to flow in a Hele-Shaw cell. The system takes into account the chemical diffusivity between different components of a fluid mixture and the reactive stresses induced by inhomogeneity. In one of the systems we consider (HSCH), the binary fluid may be compressible due to diffusion. In the other system (BHSCH), a Boussinesq approximation is used and the fluid is incompressible. In this paper, we motivate, present and calibrate the HSCH/BHSCH equations so as to yield the classical sharp interface model as a limiting case. We then analyze their equilibria, one dimensional evolution and linear stability. In the second paper [paper II, Phys. Fluids 14, 514 (2002)], we analyze the behavior of the models in the fully nonlinear regime. In the BHSCH system, the equilibrium concentration profile is obtained using the classical Maxwell construction [Rowlinson and Widom, Molecular Theory of Capillarity (Clarendon, Oxford, 1979)] and does not depend on the orientation of the gravitational field. We find that the equilibria in the HSCH model are somewhat surprising as the gravitational field actually affects the internal structure of an isolated interface by driving additional stratification of light and heavy fluids over that predicted in the Boussinesq case. A comparison of the linear growth rates indicates that the HSCH system is slightly more diffusive than the BHSCH system. In both, linear convergence to the sharp interface growth rates is observed in a parameter controlling the interface thickness. In addition, we identify the effect that each of the parameters, in the HSCH/BHSCH models, has on the linear growth rates. We then show how this analysis may be used to suggest a set of modified parameters which, when used in the HSCH/BHSCH systems, yield improved agreement with the sharp interface model at a finite interface thickness. Evidence of this improved agreement may be found in paper II.

Predicting mixture phase equilibria and critical behavior using the SAFT-VRX approach.

PubMed

Sun, Lixin; Zhao, Honggang; Kiselev, Sergei B; McCabe, Clare

2005-05-12

The SAFT-VRX equation of state combines the SAFT-VR equation with a crossover function that smoothly transforms the classical equation into a nonanalytical form close to the critical point. By a combinination of the accuracy of the SAFT-VR approach away from the critical region with the asymptotic scaling behavior seen at the critical point of real fluids, the SAFT-VRX equation can accurately describe the global fluid phase diagram. In previous work, we demonstrated that the SAFT-VRX equation very accurately describes the pvT and phase behavior of both nonassociating and associating pure fluids, with a minimum of fitting to experimental data. Here, we present a generalized SAFT-VRX equation of state for binary mixtures that is found to accurately predict the vapor-liquid equilibrium and pvT behavior of the systems studied. In particular, we examine binary mixtures of n-alkanes and carbon dioxide + n-alkanes. The SAFT-VRX equation accurately describes not only the gas-liquid critical locus for these systems but also the vapor-liquid equilibrium phase diagrams and thermal properties in single-phase regions.

Polymer-cushioned bilayers. II. An investigation of interaction forces and fusion using the surface forces apparatus.

PubMed Central

Wong, J Y; Park, C K; Seitz, M; Israelachvili, J

1999-01-01

We have created phospholipid bilayers supported on soft polymer "cushions" which act as deformable substrates (see accompanying paper, Wong, J. Y., J. Majewski, M. Seitz, C. K. Park, J. N. Israelachvili, and G. S. Smith. 1999. Biophys. J. 77:1445-1457). In contrast to "solid-supported" membranes, such "soft-supported" membranes can exhibit more natural (higher) fluidity. Our bilayer system was constructed by adsorption of small unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles onto polyethylenimine (PEI)-supported Langmuir-Blodgett lipid monolayers on mica. We used the surface forces apparatus (SFA) to investigate the long-range forces, adhesion, and fusion of two DMPC bilayers both above and below their main transition temperature (T(m) approximately 24 degrees C). Above T(m), hemi-fusion activation pressures of apposing bilayers were considerably smaller than for solid-supported bilayers, e.g., directly supported on mica. After separation, the bilayers naturally re-formed after short healing times. Also, for the first time, complete fusion of two fluid (liquid crystalline) phospholipid bilayers was observed in the SFA. Below T(m) (gel state), very high pressures were needed for hemi-fusion and the healing process became very slow. The presence of the polymer cushion significantly alters the interaction potential, e.g., long-range forces as well as fusion pressures, when compared to solid-supported systems. These fluid model membranes should allow the future study of integral membrane proteins under more physiological conditions. PMID:10465756

The modelling of heat, mass and solute transport in solidification systems

NASA Technical Reports Server (NTRS)

Voller, V. R.; Brent, A. D.; Prakash, C.

1989-01-01

The aim of this paper is to explore the range of possible one-phase models of binary alloy solidification. Starting from a general two-phase description, based on the two-fluid model, three limiting cases are identified which result in one-phase models of binary systems. Each of these models can be readily implemented in standard single phase flow numerical codes. Differences between predictions from these models are examined. In particular, the effects of the models on the predicted macro-segregation patterns are evaluated.

CRUSTAL FAILURE DURING BINARY INSPIRAL

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

Penner, A. J.; Andersson, N.; Jones, D. I.

2012-04-20

We present the first fully relativistic calculations of the crustal strain induced in a neutron star by a binary companion at the late stages of inspiral, employing realistic equations of state for the fluid core and the solid crust. We show that while the deep crust is likely to fail only shortly before coalescence, there is a large variation in elastic strain, with the outermost layers failing relatively early on in the inspiral. We discuss the significance of the results for both electromagnetic and gravitational-wave astronomy.

Acoustics of marine sediment under compaction: binary grain-size model and viscoelastic extension of Biot's theory.

PubMed

Leurer, Klaus C; Brown, Colin

2008-04-01

This paper presents a model of acoustic wave propagation in unconsolidated marine sediment, including compaction, using a concept of a simplified sediment structure, modeled as a binary grain-size sphere pack. Compressional- and shear-wave velocities and attenuation follow from a combination of Biot's model, used as the general framework, and two viscoelastic extensions resulting in complex grain and frame moduli, respectively. An effective-grain model accounts for the viscoelasticity arising from local fluid flow in expandable clay minerals in clay-bearing sediments. A viscoelastic-contact model describes local fluid flow at the grain contacts. Porosity, density, and the structural Biot parameters (permeability, pore size, structure factor) as a function of pressure follow from the binary model, so that the remaining input parameters to the acoustic model consist solely of the mass fractions and the known mechanical properties of each constituent (e.g., carbonates, sand, clay, and expandable clay) of the sediment, effective pressure, or depth, and the environmental parameters (water depth, salinity, temperature). Velocity and attenuation as a function of pressure from the model are in good agreement with data on coarse- and fine-grained unconsolidated marine sediments.

Individual lipid encapsulated microbubble radial oscillations: Effects of fluid viscosity

PubMed Central

Helfield, Brandon; Chen, Xucai; Qin, Bin; Villanueva, Flordeliza S.

2016-01-01

Ultrasound-stimulated microbubble dynamics have been shown to be dependent on intrinsic bubble properties, including size and shell characteristics. The effect of the surrounding environment on microbubble response, however, has been less investigated. In particular, microbubble optimization studies are generally conducted in water/saline, characterized by a 1 cP viscosity, for application in the vasculature (i.e., 4 cP). In this study, ultra-high speed microscopy was employed to investigate fluid viscosity effects on phospholipid encapsulated microbubble oscillations at 1 MHz, using a single, eight-cycle pulse at peak negative pressures of 100 and 250 kPa. Microbubble oscillations were shown to be affected by fluid viscosity in a size- and pressure-dependent manner. In general, the oscillation amplitudes exhibited by microbubbles between 3 and 6 μm in 1 cP fluid were larger than in 4 cP fluid, reaching a maximum of 1.7-fold at 100 kPa for microbubbles 3.8 μm in diameter and 1.35-fold at 250 kPa for microbubbles 4.8 μm in diameter. Simulation results were in broad agreement at 250 kPa, however generally underestimated the effect of fluid viscosity at 100 kPa. This is the first experimental demonstration documenting the effects of surrounding fluid viscosity on microbubble oscillations, resulting in behavior not entirely predicted by current microbubble models. PMID:26827018

Mixing, diffusion, and percolation in binary supported membranes containing mixtures of lipids and amphiphilic block copolymers.

PubMed

Gettel, Douglas L; Sanborn, Jeremy; Patel, Mira A; de Hoog, Hans-Peter; Liedberg, Bo; Nallani, Madhavan; Parikh, Atul N

2014-07-23

Substrate-mediated fusion of small polymersomes, derived from mixtures of lipids and amphiphilic block copolymers, produces hybrid, supported planar bilayers at hydrophilic surfaces, monolayers at hydrophobic surfaces, and binary monolayer/bilayer patterns at amphiphilic surfaces, directly responding to local measures of (and variations in) surface free energy. Despite the large thickness mismatch in their hydrophobic cores, the hybrid membranes do not exhibit microscopic phase separation, reflecting irreversible adsorption and limited lateral reorganization of the polymer component. With increasing fluid-phase lipid fraction, these hybrid, supported membranes undergo a fluidity transition, producing a fully percolating fluid lipid phase beyond a critical area fraction, which matches the percolation threshold for the immobile point obstacles. This then suggests that polymer-lipid hybrid membranes might be useful models for studying obstructed diffusion, such as occurs in lipid membranes containing proteins.

Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture

NASA Astrophysics Data System (ADS)

Miller, Nicholas A. T.; Daivis, Peter J.; Snook, Ian K.; Todd, B. D.

2013-10-01

Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

The calculation of the phase equilibrium of the multicomponent hydrocarbon systems

NASA Astrophysics Data System (ADS)

Molchanov, D. A.

2018-01-01

Hydrocarbon mixtures filtration process simulation development has resulted in use of cubic equations of state of the van der Waals type to describe the thermodynamic properties of natural fluids under real thermobaric conditions. Binary hydrocarbon systems allow to simulate the fluids of different types of reservoirs qualitatively, what makes it possible to carry out the experimental study of their filtration features. Exploitation of gas-condensate reservoirs shows the possibility of existence of various two-phase filtration regimes, including self-oscillatory one, which occurs under certain values of mixture composition, temperature and pressure drop. Plotting of the phase diagram of the model mixture is required to determine these values. A software package to calculate the vapor-liquid equilibrium of binary systems using cubic equation of state of the van der Waals type has been created. Phase diagrams of gas-condensate model mixtures have been calculated.

Formation of pH-sensitive cationic liposomes from a binary mixture of monoalkylated primary amine and cholesterol.

PubMed

Cui, Zhong-Kai; Bouisse, Anne; Cottenye, Nicolas; Lafleur, Michel

2012-09-25

It has been shown that mixtures of monoalkylated amphiphiles and sterols can form liquid-ordered (lo) lamellar phases. These bilayers can be extruded using conventional methods to obtain large unilamellar vesicles (LUVs) that have very low permeability and a specific response to a given stimulus. For example, pH variations can trigger the release from LUVs formed with palmitic acid and sterols. In the present work, the possibility to form non phospholipid liposomes with mixtures of stearylamine (SA) and cholesterol (Chol) was investigated. The phase behavior of these mixtures was characterized by differential scanning calorimetry, infrared, and (2)H NMR spectroscopy. It is found that this particular mixture can form a lo lamellar phase that is pH-sensitive as the system undergoes a transition from a lo phase to a solid state when pH is increased from 5.5 to 12. LUVs have been successfully extruded from equimolar SA/Chol mixtures. Release experiments as a function of time revealed the relatively low permeability of these systems. The fact that the stability of these liposomes is pH dependent implies that these LUVs display an interesting potential as new cationic carriers for pH-triggered release. This is the first report of non phospholipid liposomes with high sterol content combining an overall positive charge and pH-sensitivity.

[Evaluation of fetal lung maturity using a modified lecithin-sphingomyelin determination and Clements' foam test].

PubMed

Neumann, G; Gartzke, J; Faber, G

1978-01-01

The modified thin layer chromatographic method for the determination of the phospholipids lecithin and sphingomyelin from amniotic fluid is useful in estimating fetal pulmonary maturity. The foam test of Clements is a simple rapid method for screening of suspicious cases of pregnancies at risk and of great value as bed side test even performing by the doctor. In comparing Clements-Test with thin layer chromatographic for L/S-Ratio determination we found a good correlation of 81,8% of all cases.

Surface tension in human pathophysiology and its application as a medical diagnostic tool

PubMed Central

Fathi-Azarbayjani, Anahita; Jouyban, Abolghasem

2015-01-01

Introduction: Pathological features of disease appear to be quite different. Despite this diversity, the common feature of various disorders underlies physicochemical and biochemical factors such as surface tension. Human biological fluids comprise various proteins and phospholipids which are capable of adsorption at fluid interfaces and play a vital role in the physiological function of human organs. Surface tension of body fluids correlates directly to the development of pathological states. Methods: In this review, the variety of human diseases mediated by the surface tension changes of biological phenomena and the failure of biological fluids to remain in their native state are discussed. Results: Dynamic surface tension measurements of human biological fluids depend on various parameters such as sex, age and changes during pregnancy or certain disease. It is expected that studies of surface tension behavior of human biological fluids will provide additional information and might become useful in medical practice. Theoretical background on surface tension measurement and surface tension values of reference fluids obtained from healthy and sick patients are depicted. Conclusion: It is well accepted that no single biomarker will be effective in clinical diagnosis. The surface tension measurement combined with routine lab tests may be a novel non-invasive method which can not only facilitate the discovery of diagnostic models for various diseases and its severity, but also be a useful tool for monitoring treatment efficacy. We therefore expect that studies of surface tension behavior of human biological fluids will provide additional useful information in medical practice. PMID:25901295

Statistical mechanics of homogeneous partly pinned fluid systems.

PubMed

Krakoviack, Vincent

2010-12-01

The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested.

The thermodynamic cycle models for geothermal power plants by considering the working fluid characteristic

NASA Astrophysics Data System (ADS)

Mulyana, Cukup; Adiprana, Reza; Saad, Aswad H.; M. Ridwan, H.; Muhammad, Fajar

2016-02-01

The scarcity of fossil energy accelerates the development of geothermal power plant in Indonesia. The main issue is how to minimize the energy loss from the geothermal working fluid so that the power generated can be increased. In some of geothermal power plant, the hot water which is resulted from flashing is flown to injection well, and steam out from turbine is condensed in condenser, while the temperature and pressure of the working fluid is still high. The aim of this research is how the waste energy can be re-used as energy source to generate electric power. The step of the research is started by studying the characteristics of geothermal fluid out from the well head. The temperature of fluid varies from 140°C - 250°C, the pressure is more than 7 bar and the fluid phase are liquid, gas, or mixing phase. Dry steam power plant is selected for vapor dominated source, single or multiple flash power plant is used for dominated water with temperature > 225°C, while the binary power plant is used for low temperature of fluid < 160°C. Theoretically, the process in the power plant can be described by thermodynamic cycle. Utilizing the heat loss of the brine and by considering the broad range of working fluid temperature, the integrated geothermal power plant has been developed. Started with two ordinary single flash power plants named unit 1 and unit 2, with the temperature 250°C resulting power is W1'+W2'. The power is enhanced by utilizing the steam that is out from first stage of the turbine by inputting the steam to the third stage, the power of the plant increase with W1''+W2" or 10% from the original power. By using flasher, the water from unit 1 and 2 is re-flashed at 200°C, and the steam is used to drive the turbine in unit 3, while the water is re-flashed at the temperature170°C and the steam is flown to the same turbine (unit 3) resulting the power of W3+W4. Using the fluid enthalpy, the calculated power of these double and triple flash power plant are 50% of W1+W2. At the last step, the steam out from the turbine of unit 3 with the temperature 150°C is used as a heat source for binary cycle power plant named unit 4, while the hot water from the flasher is used as a heat source for the other binary cycle named unit 5 resulted power W5+W6 or 15% of W1+W2. Using this integrated model the power increased 75% from the original one.

Enzymatic modification of phospholipids for functional applications and human nutrition.

PubMed

Guo, Zheng; Vikbjerg, Anders F; Xu, Xuebing

2005-05-01

Rapid progress in biochemistry of phospholipids and evolution of modern bioengineering has brought forth a number of novel concepts and technical advancements in the modification of phospholipids for industrial applications and human nutrition. Highlights cover preparation of novel phospholipid analogs based on the latest understanding of pivotal role of phospholipids in manifold biological processes, exploration of remarkable application potentials of phospholipids in meliorating human health, as well as development of new chemical and biotechnological approaches applied to the modification of phospholipids. This work reviews the natural occurrence and structural characteristics of phospholipids, their updated knowledge on manifold biological and nutritional functions, traditional and novel physical and chemical approaches to modify phospholipids as well as their applications to obtain novel phospholipids, and brief introduction of the efforts focusing on de novo syntheses of phospholipids. Special attention is given to the summary of molecular structural characteristics and catalytic properties of multiple phospholipases, which helps to interpret experimental phenomena and to improve reaction design. This will of course provide fundamental bases also for the development of enzymatic technology to produce structured or modified phospholipids.

Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer–leaflet and inter-leaflet coupling

PubMed Central

Hill, Reghan J.; Wang, Chih-Ying

2014-01-01

A variety of observations—sometimes controversial—have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans–Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans–Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer–leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements—including lipids, integral monotopic and polytopic proteins, and lipid rafts—in supported bilayer membranes. PMID:25002822

Self-assembled Lyotropic Liquid Crystalline Phase Behavior of Monoolein-Capric Acid-Phospholipid Nanoparticulate Systems.

PubMed

Zhai, Jiali; Tran, Nhiem; Sarkar, Sampa; Fong, Celesta; Mulet, Xavier; Drummond, Calum J

2017-03-14

We report here the lyotropic liquid crystalline phase behavior of two lipid nanoparticulate systems containing mixtures of monoolein, capric acid, and saturated diacyl phosphatidylcholines dispersed by the Pluronic F127 block copolymer. Synchrotron small-angle X-ray scattering (SAXS) was used to screen the phase behavior of a library of lipid nanoparticles in a high-throughput manner. It was found that adding capric acid and phosphatidylcholines had opposing effects on the spontaneous membrane curvature of the monoolein lipid layer and hence the internal mesophase of the final nanoparticles. By varying the relative concentration of the three lipid components, we were able to establish a library of nanoparticles with a wide range of mesophases including at least the inverse bicontinuous primitive and double diamond cubic phases, the inverse hexagonal phase, the fluid lamellar phase, and possibly other phases. Furthermore, the in vitro cytotoxicity assay showed that the endogenous phospholipid-containing nanoparticles were less toxic to cultured cell lines compared to monoolein-based counterparts, improving the potential of the nonlamellar lipid nanoparticles for biomedical applications.

Vesicle Origami and the Influence of Cholesterol on Lipid Packing.

PubMed

Tanasescu, Radu; Lanz, Martin A; Mueller, Dennis; Tassler, Stephanie; Ishikawa, Takashi; Reiter, Renate; Brezesinski, Gerald; Zumbuehl, Andreas

2016-05-17

The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous curvature. Forced into a vesicular structure, Pad-PC-Pad has faceted geometry, and in its extreme form, tetrahedral vesicles were found as predicted a decade ago. Above the main transition temperature, a noninterdigitated Lα phase with fluid chains has been observed. The addition of cholesterol leads to a slight decrease of the main transition temperature and a gradual decrease in the transition enthalpy until the transition vanishes at 40 mol % cholesterol in the mixture. Additionally, cholesterol pulls the chains apart, and a noninterdigitated gel phase is observed. In monolayers, cholesterol has an ordering effect on liquid-expanded phases and disorders condensed phases. The wavenumbers of the methylene stretching vibration indicate the formation of a liquid-ordered phase in mixtures with 40 mol % cholesterol.

Spontaneous formation of nanometer scale tubular vesicles in aqueous mixtures of lipid and block copolymer amphiphiles.

PubMed

Lim, Seng Koon; Wong, Andrew S W; de Hoog, Hans-Peter M; Rangamani, Padmini; Parikh, Atul N; Nallani, Madhavan; Sandin, Sara; Liedberg, Bo

2017-02-08

Many common amphiphiles self-assemble in water to produce heterogeneous populations of discrete and symmetric but polydisperse and multilamellar vesicles isolating the encapsulated aqueous core from the surrounding bulk. But when mixtures of amphiphiles of vastly different elastic properties co-assemble, their non-uniform molecular organization can stabilize lower symmetries and produce novel shapes. Here, using high resolution electron cryomicroscopy and tomography, we identify the spontaneous formation of a membrane morphology consisting of unilamellar tubular vesicles in dilute aqueous solutions of binary mixtures of two different amphiphiles of vastly different origins. Our results show that aqueous phase mixtures of a fluid-phase phospholipid and an amphiphilic block copolymer spontaneously assume a bimodal polymorphic character in a composition dependent manner: over a broad range of compositions (15-85 mol% polymer component), a tubular morphology co-exists with spherical vesicles. Strikingly, in the vicinity of equimolar compositions, an exclusively tubular morphology (L t ; diameter, ∼15 nm; length, >1 μm; core, ∼2.0 nm; wall, ∼5-6 nm) emerges in an apparent steady state. Theory suggests that the spontaneous stabilization of cylindrical vesicles, unaided by extraneous forces, requires a significant spontaneous bilayer curvature, which in turn necessitates a strongly asymmetric membrane composition. We confirm that such dramatic compositional asymmetry is indeed produced spontaneously in aqueous mixtures of a lipid and polymer through two independent biochemical assays - (1) reduction in the quenching of fluorophore-labeled lipids and (2) inhibition in the activity of externally added lipid-hydrolyzing phospholipase A2, resulting in a significant enrichment of the polymer component in the outer leaflet. Taken together, these results illustrate the coupling of the membrane shape with local composition through spontaneous curvature generation under conditions of asymmetric distribution of mixtures of disparate amphiphiles.

Measurement of diffusion in fluid systems: Applications to the supercritical fluid region

NASA Astrophysics Data System (ADS)

Bruno, Thomas J.

1994-04-01

The experimental procedures that are applicable to the measurement of diffusion in supercritical fluid solutions are reviewed. This topic is of great importance to the proper design of advanced aircraft and turbine fuels, since the fuels on these aircraft may sometimes operate under supercritical fluid conditions. More specifically, we will consider measurements of the binary interaction diffusion coefficient D exp 12 of a solute (species 1) and the solvent (species 2). In this discussion, the supercritical fluid is species 2, and the solute, species 1, will be at a relatively low concentration, sometimes approaching infinite dilution. After a brief introduction to the concept of diffusion, we will discuss in detail the use of chromatographic methods, and then briefly treat light scattering, nuclear magnetic resonance spectra, and physical methods.

Miscibility and Phase Behavior of N-Acylethanolamine/Diacylphosphatidylethanolamine Binary Mixtures of Matched Acyl Chainlengths (n = 14, 16)

PubMed Central

Kamlekar, Ravi Kanth; Satyanarayana, S.; Marsh, Derek; Swamy, Musti J.

2007-01-01

The miscibility and phase behavior of hydrated binary mixtures of two N-acylethanolamines (NAEs), N-myristoylethanolamine (NMEA), and N-palmitoylethanolamine (NPEA), with the corresponding diacyl phosphatidylethanolamines (PEs), dimyristoylphosphatidylethanolamine (DMPE), and dipalmitoylphosphatidylethanolamine (DPPE), respectively, have been investigated by differential scanning calorimetry (DSC), spin-label electron spin resonance (ESR), and 31P-NMR spectroscopy. Temperature-composition phase diagrams for both NMEA/DMPE and NPEA/DPPE binary systems were established from high sensitivity DSC. The structures of the phases involved were determined by 31P-NMR spectroscopy. For both systems, complete miscibility in the fluid and gel phases is indicated by DSC and ESR, up to 35 mol % of NMEA in DMPE and 40 mol % of NPEA in DPPE. At higher contents of the NAEs, extensive solid-fluid phase separation and solid-solid immiscibility occur depending on the temperature. Characterization of the structures of the mixtures formed with 31P-NMR spectroscopy shows that up to 75 mol % of NAE, both DMPE and DPPE form lamellar structures in the gel phase as well as up to at least 65°C in the fluid phase. ESR spectra of phosphatidylcholine spin labeled at the C-5 position in the sn-2 acyl chain present at a probe concentration of 1 mol % exhibit strong spin-spin broadening in the low-temperature region for both systems, suggesting that the acyl chains pack very tightly and exclude the spin label. However, spectra recorded in the fluid phase do not exhibit any spin-spin broadening and indicate complete miscibility of the two components. The miscibility of NAE and diacyl PE of matched chainlengths is significantly less than that found earlier for NPEA and dipalmitoylphosphatidylcholine, an observation that is consistent with the notion that the NAEs are most likely stored as their precursor lipids (N-acyl PEs) and are generated only when the system is subjected to membrane stress. PMID:17369415

Multi-stage mixing in subduction zone: Application to Merapi volcano, Indonesia

NASA Astrophysics Data System (ADS)

Debaille, V.; Doucelance, R.; Weis, D.; Schiano, P.

2003-04-01

Basalts sampling subduction zone volcanism (IAB) often show binary mixing relationship in classical Sr-Nd, Pb-Pb, Sr-Pb isotopic diagrams, generally interpreted as reflecting the involvement of two components in their source. However, several authors have highlighted the presence of minimum three components in such a geodynamical context: mantle wedge, subducted and altered oceanic crust and subducted sediments. The overlying continental crust can also contribute by contamination and assimilation in magma chambers and/or during magma ascent. Here we present a multi-stage model to obtain a two end-member mixing from three components (mantle wedge, altered oceanic crust and sediments). The first stage of the model considers the metasomatism of the mantle wedge by fluids and/or melts released by subducted materials (altered oceanic crust and associated sediments), considering mobility and partition coefficient of trace elements in hydrated fluids and silicate melts. This results in the generation of two distinct end-members, reducing the number of components (mantle wedge, oceanic crust, sediments) from three to two. The second stage of the model concerns the binary mixing of the two end-members thus defined: mantle wedge metasomatized by slab-derived fluids and mantle wedge metasomatized by sediment-derived fluids. This model has been applied on a new isotopic data set (Sr, Nd and Pb, analyzed by TIMS and MC-ICP-MS) of Merapi volcano (Java island, Indonesia). Previous studies have suggested three distinct components in the source of indonesian lavas: mantle wedge, subducted sediments and altered oceanic crust. Moreover, it has been shown that crustal contamination does not significantly affect isotopic ratios of lavas. The multi-stage model proposed here is able to reproduce the binary mixing observed in lavas of Merapi, and a set of numerical values of bulk partition coefficient is given that accounts for the genesis of lavas.

Electric Field Induced Interfacial Instabilities

NASA Technical Reports Server (NTRS)

Kusner, Robert E.; Min, Kyung Yang; Wu, Xiao-lun; Onuki, Akira

1999-01-01

The study of the interface in a charge-free, critical and near-critical binary fluid in the presence of an externally applied electric field is presented. At sufficiently large fields, the interface between the two phases of the binary fluid should become unstable and exhibit an undulation with a predefined wavelength on the order of the capillary length. As the critical point is approached, this wavelength is reduced, potentially approaching length-scales such as the correlation length or critical nucleation radius. At this point the critical properties of the system may be affected. In this paper, the flat interface of a marginally polar binary fluid mixture is stressed by a perpendicular alternating electric field and the resulting instability is characterized by the critical electric field E(sub c) and the pattern observed. The character of the surface dynamics at the onset of instability is found to be strongly dependent on the frequency f of the field applied. The plot of E(sub c) vs. f for a fixed temperature shows a sigmoidal shape, whose low and high frequency limits are well described by a power-law relationship, E(sub c) = epsilon(exp zeta) with zeta = 0.35 and zeta = 0.08, respectively. The low-limit exponent compares well with the value zeta = 4 for a system of conducting and non-conducting fluids. On the other hand, the high-limit exponent coincides with what was first predicted by Onuki. The instability manifests itself as the conducting phase penetrates the non-conducting phase. As the frequency increases, the shape of the pattern changes from an array of bifurcating strings to an array of column-like (or rod-like) protrusions, each of which spans the space between the plane interface and one of the electrodes. For an extremely high frequency, the disturbance quickly grows into a parabolic cone pointing toward the upper plate. As a result, the interface itself changes its shape from that of a plane to that of a high sloping pyramid.

Prediction of fetal lung maturity using the lecithin/sphingomyelin (L/S) ratio analysis with a simplified sample preparation, using a commercial microtip-column combined with mass spectrometric analysis.

PubMed

Kwak, Ho-Seok; Chung, Hee-Jung; Choi, Young Sik; Min, Won-Ki; Jung, So Young

2015-07-01

Fetal lung maturity is estimated using the lecithin/sphingomyelin ratio (L/S ratio) in amniotic fluid and it is commonly measured with thin-layer chromatography (TLC). The TLC method is time consuming and technically difficult; however, it is widely used because there is no alternative. We evaluated a novel method for measuring the L/S ratio, which involves a tip-column with a cation-exchange resin and mass spectrometry. Phospholipids in the amniotic fluid were extracted using methanol and chloroform. Choline-containing phospholipids such as lecithin and sphingomyelin were purified by passing them through the tip-column. LC-MS/MS and MALDI-TOF were used to directly analyze the purified samples. The L/S ratio by mass spectrometry was calculated from the sum peak intensity of the six lecithin, and that of sphingomyelin 34:1. In 20 samples, the L/S ratio determined with TLC was significantly correlated with that obtained by LC-MS/MS and MALDI-TOF. There was a 100% concordance between the L/S ratio by TLC and that by LC-MS/MS (kappa value=1.0). The concordance between the L/S ratio by TLC and that by MALDI-TOF was also 100% (kappa value=1.0). Our method provides a faster, simpler, and more reliable assessment of fetal lung maturity. The L/S ratio measured by LC-MS/MS and MALDI-TOF offers a compelling alternative method to traditional TLC. Copyright © 2015 Elsevier B.V. All rights reserved.

Self-thermophoresis and thermal self-diffusion in liquids and gases.

PubMed

Brenner, Howard

2010-09-01

This paper demonstrates the existence of self-thermophoresis, a phenomenon whereby a virtual thermophoretic force arising from a temperature gradient in a quiescent single-component liquid or gas acts upon an individual molecule of that fluid in much the same manner as a "real" thermophoretic force acts upon a macroscopic, non-Brownian body immersed in that same fluid. In turn, self-thermophoresis acting in concert with Brownian self-diffusion gives rise to the phenomenon of thermal self-diffusion in single-component fluids. The latter furnishes quantitative explanations of both thermophoresis in pure fluids and thermal diffusion in binary mixtures (the latter composed of a dilute solution of a physicochemically inert solute whose molecules are large compared with those of the solvent continuum). Explicitly, the self-thermophoretic theory furnishes a simple expression for both the thermophoretic velocity U of a macroscopic body in a single-component fluid subjected to a temperature gradient ∇T , and the intimately related binary thermal diffusion coefficient D{T} for a two-component colloidal or macromolecular mixture. The predicted expressions U=-D{T}∇T≡-βD{S}∇T and D{T}=βD{S} (with β and D{S} the pure solvent's respective thermal expansion and isothermal self-diffusion coefficients) are each noted to accord reasonably well with experimental data for both liquids and gases. The likely source of systematic deviations of the predicted values of D{T} from these data is discussed. This appears to be the first successful thermodiffusion theory applicable to both liquids and gases, a not insignificant achievement considering that the respective thermal diffusivities and thermophoretic velocities of these two classes of fluids differ by as much as six orders of magnitude.

High Fill-out, Extreme Mass Ratio Overcontact Binary Systems. X. The Newly Discovered Binary XY Leonis Minoris

NASA Astrophysics Data System (ADS)

Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J.; Yang, Y.-G.; Bernasconi, L.

2011-05-01

The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 × 10-7 days yr-1, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

A Loader for Executing Multi-Binary Applications on the Thinking Machines CM-5: It's Not Just for SPMD Anymore

NASA Technical Reports Server (NTRS)

Becker, Jeffrey C.

1995-01-01

The Thinking Machines CM-5 platform was designed to run single program, multiple data (SPMD) applications, i.e., to run a single binary across all nodes of a partition, with each node possibly operating on different data. Certain classes of applications, such as multi-disciplinary computational fluid dynamics codes, are facilitated by the ability to have subsets of the partition nodes running different binaries. In order to extend the CM-5 system software to permit such applications, a multi-program loader was developed. This system is based on the dld loader which was originally developed for workstations. This paper provides a high level description of dld, and describes how it was ported to the CM-5 to provide support for multi-binary applications. Finally, it elaborates how the loader has been used to implement the CM-5 version of MPIRUN, a portable facility for running multi-disciplinary/multi-zonal MPI (Message-Passing Interface Standard) codes.

Electrostatic effects in the collapse transition of phospholiquid monolayer

NASA Astrophysics Data System (ADS)

Nguyen, Toan T.; Gopal, Ajaykumar; Lee, Ka Yee C.; Witten, Thomas A.

2004-03-01

We study the collapse transition of fluidic phospholipid surfactant monolayers under lateral compression. DMPC, DPPC or POPG surfactants and their binary mixtures are used. Various collapsed structures (circular discs, cylinderical tubes and pearls-on-a-string) were observed during the transition. We show that electrostatics plays an important role in the formation of these structures. By changing the composition of charged surfactant (POGP) or the screening condition of the solution, one can change the dominant collapsed structure from discs to tubes to pearls in the order of increasing the strength of electrostatic interactions, in accordance with theoretical estimates. We also study a complimentary electrostatic effect due charge relaxation in the transitions between these structures. It is shown that free energy gained from relaxations of charge molecule is small and can be neglected when considering electrostatics of these systems.

Effect of phospholipid deposits on adhesion of bacteria to contact lenses.

PubMed

Babaei Omali, Negar; Proschogo, Nicholas; Zhu, Hua; Zhao, Zhenjun; Diec, Jennie; Borazjani, Roya; Willcox, Mark D P

2012-01-01

Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses. Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol. The amount of phospholipid was measured by electrospray ionization mass spectrometry. Unworn lenses soaked in phospholipids were exposed to Pseudomonas aeruginosa and Staphylococcus aureus. After 18 h incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. Phospholipid was tested for possible effects on bacterial growth. A broad range of sphingomyelins (SM) and phosphatidylcholines (PC) were detected from both types of worn lenses. SM (16:0) (m/z 703) and PC (34:2) (m/z 758) were the major phospholipids detected in the lens extracts. Phospholipids did not alter the adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). Phospholipids (0.1 mg/mL) showed no effect on the growth of P. aeruginosa 6294 or S. aureus 031. Phospholipids adsorb/absorb to contact lenses during wear, however, the major types of phospholipids adsorbed to lenses do not alter bacterial adhesion or growth.

Turbulent black holes.

PubMed

Yang, Huan; Zimmerman, Aaron; Lehner, Luis

2015-02-27

We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

Corrosion tests in Hawaiian geothermal fluids

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

Larsen-Basse, J.; Lam, Kam-Fai

1984-01-01

Exposure tests were conductd in binary geothermal brine on the island of Hawaii. The steam which flashes from the high pressure, high temperature water as it is brought to ambient pressure contains substantial amounts of H{sub 2}S. In the absence of oxygen this steam is only moderately aggressive but in the aerated state it is highly aggressive to carbon steels and copper alloys. The liquid after flasing is intermediately aggressive. The Hawaiian fluid is unique in chemistry and corrosion behavior; its corrosiveness is relatively mild for a geothermal fluid falling close to the Iceland-type resources. 24 refs., 7 figs., 5more » tabs.« less

Design and optimization of geothermal power generation, heating, and cooling

NASA Astrophysics Data System (ADS)

Kanoglu, Mehmet

Most of the world's geothermal power plants have been built in 1970s and 1980s following 1973 oil crisis. Urgency to generate electricity from alternative energy sources and the fact that geothermal energy was essentially free adversely affected careful designs of plants which would maximize their performance for a given geothermal resource. There are, however, tremendous potentials to improve performance of many existing geothermal power plants by retrofitting, optimizing the operating conditions, re-selecting the most appropriate binary fluid in binary plants, and considering cogeneration such as a district heating and/or cooling system or a system to preheat water entering boilers in industrial facilities. In this dissertation, some representative geothermal resources and existing geothermal power plants in Nevada are investigated to show these potentials. Economic analysis of a typical geothermal resource shows that geothermal heating and cooling may generate up to 3 times as much revenue as power generation alone. A district heating/cooling system is designed for its incorporation into an existing 27 MW air-cooled binary geothermal power plant. The system as designed has the capability to meet the entire heating needs of an industrial park as well as 40% of its cooling needs, generating potential revenues of $14,040,000 per year. A study of the power plant shows that evaporative cooling can increase the power output by up to 29% in summer by decreasing the condenser temperature. The power output of the plant can be increased by 2.8 percent by optimizing the maximum pressure in the cycle. Also, replacing the existing working fluid isobutane by butane, R-114, isopentane, and pentane can increase the power output by up to 2.5 percent. Investigation of some well-known geothermal power generation technologies as alternatives to an existing 12.8 MW single-flash geothermal power plant shows that double-flash, binary, and combined flash/binary designs can increase the net power output by up to 31 percent, 35 percent, and 54 percent, respectively, at optimum operating conditions. An economic comparison of these designs appears to favor the combined flash/binary design, followed by the double-flash design.

Bile Salt Mediated Growth of Reverse Wormlike Micelles in Nonpolar Liquids

NASA Astrophysics Data System (ADS)

Tung, Shih-Huang; Huang, Yi-En; Raghavan, Srinivasa

2006-03-01

We report the growth of reverse wormlike micelles induced by the addition of a bile salt in trace amounts to solutions of the phospholipid, lecithin in nonpolar organic solvents. Previous recipes for reverse wormlike micelles have usually required the addition of water to induce reverse micellar growth; here, we show that bile salts, due to their unique ``facially amphiphilic'' structure, can play a role analogous to water and promote the longitudinal aggregation of lecithin molecules into reverse micellar chains. The formation of transient entangled networks of these reverse micelles transforms low-viscosity lecithin organosols into strongly viscoelastic fluids. The zero-shear viscosity increases by more than five orders of magnitude, and it is the molar ratio of bile salt to lecithin that controls this viscosity enhancement. The growth of reverse wormlike micelles is also confirmed by small-angle neutron scattering (SANS) experiments on these fluids.

Simultaneous microencapsulation of hydrophilic and lipophilic bioactives in liposomes produced by an ecofriendly supercritical fluid process.

PubMed

Tsai, Wen-Chyan; Rizvi, Syed S H

2017-09-01

Organic solvent residues are always a concern with the liposomes produced by traditional techniques. Our objectives were to encapsulate hydrophilic and lipophilic compounds in liposomes using a newly designed supercritical fluid process coupled with vacuum-driven cargo loading. Supercritical carbon dioxide was chosen as the phospholipid-dissolving medium and an ecofriendly substitute for organic solvents. Liposomal microencapsulation was conducted via a 1000-μm expansion nozzle at 12.41MPa, 90°C, and aqueous cargo loading rate of 0.25ml/s. Vitamins C and E were selected as model hydrophilic and lipophilic compounds encapsulated in the integrated liposomes. The average vesicle size was 951.02nm with a zeta potential of -51.87mV. The encapsulation efficiency attained was 32.97% for vitamin C and 99.32% for vitamin E. Good emulsion stability was maintained during storage at 4°C for 20days. Simultaneous microencapsulation in the liposomes was successfully achieved with this supercritical fluid process. Copyright © 2017 Elsevier Ltd. All rights reserved.

An adjoint-based framework for maximizing mixing in binary fluids

NASA Astrophysics Data System (ADS)

Eggl, Maximilian; Schmid, Peter

2017-11-01

Mixing in the inertial, but laminar parameter regime is a common application in a wide range of industries. Enhancing the efficiency of mixing processes thus has a fundamental effect on product quality, material homogeneity and, last but not least, production costs. In this project, we address mixing efficiency in the above mentioned regime (Reynolds number Re = 1000 , Peclet number Pe = 1000) by developing and demonstrating an algorithm based on nonlinear adjoint looping that minimizes the variance of a passive scalar field which models our binary Newtonian fluids. The numerical method is based on the FLUSI code (Engels et al. 2016), a Fourier pseudo-spectral code, which we modified and augmented by scalar transport and adjoint equations. Mixing is accomplished by moving stirrers which are numerically modeled using a penalization approach. In our two-dimensional simulations we consider rotating circular and elliptic stirrers and extract optimal mixing strategies from the iterative scheme. The case of optimizing shape and rotational speed of the stirrers will be demonstrated.

Molecular dynamics simulation of a needle-sphere binary mixture

NASA Astrophysics Data System (ADS)

Raghavan, Karthik

This paper investigates the dynamic behaviour of a hard needle-sphere binary system using a novel numerical technique called the Newton homotopy continuation (NHC) method. This mixture is representative of a polymer melt where both long chain molecules and monomers coexist. Since the intermolecular forces are generated from hard body interactions, the consequence of missed collisions or incorrect collision sequences have a significant bearing on the dynamic properties of the fluid. To overcome this problem, in earlier work NHC was chosen over traditional Newton-Raphson methods to solve the hard body dynamics of a needle fluid in random media composed of overlapping spheres. Furthermore, the simplicity of interactions and dynamics allows us to focus our research directly on the effects of particle shape and density on the transport behaviour of the mixture. These studies are also compared with earlier works that examined molecular chains in porous media primarily to understand the differences in molecular transport in the bulk versus porous systems.

Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

NASA Astrophysics Data System (ADS)

Petsev, Nikolai D.; Leal, L. Gary; Shell, M. Scott

2017-12-01

Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely resolved (e.g., molecular dynamics) and coarse-grained (e.g., continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 084115 (2016)], simulated using a particle-based continuum method known as smoothed dissipative particle dynamics. An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.

Phospholipid Regulation of the Nuclear Receptor Superfamily

PubMed Central

Crowder, Mark K.; Seacrist, Corey D.; Blind, Raymond D.

2016-01-01

Nuclear receptors are ligand-activated transcription factors whose diverse biological functions are classically regulated by cholesterol-based small molecules. Over the past few decades, a growing body of evidence has demonstrated that phospholipids and other similar amphipathic molecules can also specifically bind and functionally regulate the activity of certain nuclear receptors, suggesting a critical role for these non-cholesterol-based molecules in transcriptional regulation. Phosphatidylcholines, phosphoinositides and sphingolipids are a few of the many phospholipid like molecules shown to quite specifically regulate nuclear receptors in mouse models, cell lines and in vitro. More recent evidence has also shown that certain nuclear receptors can “present” a bound phospholipid headgroup to key lipid signaling enzymes, which can then modify the phospholipid headgroup with very unique kinetic properties. Here, we review the broad array of phospholipid / nuclear receptor interactions, from the perspective of the chemical nature of the phospholipid, and the cellular abundance of the phospholipid. We also view the data in the light of well established paradigms for phospholipid mediated transcriptional regulation, as well as newer models of how phospholipids might effect transcription in the acute regulation of complex nuclear signaling pathways. Thus, this review provides novel insight into the new, non-membrane associated roles nuclear phospholipids play in regulating complex nuclear events, centered on the nuclear receptor superfamily of transcription factors. PMID:27838257

A combined fluorescence spectroscopy, confocal and 2-photon microscopy approach to re-evaluate the properties of sphingolipid domains.

PubMed

Pinto, Sandra N; Fernandes, Fábio; Fedorov, Alexander; Futerman, Anthony H; Silva, Liana C; Prieto, Manuel

2013-09-01

The aim of this study is to provide further insight about the interplay between important signaling lipids and to characterize the properties of the lipid domains formed by those lipids in membranes containing distinct composition. To this end, we have used a combination of fluorescence spectroscopy, confocal and two-photon microscopy and a stepwise approach to re-evaluate the biophysical properties of sphingolipid domains, particularly lipid rafts and ceramide (Cer)-platforms. By using this strategy we were able to show that, in binary mixtures, sphingolipids (Cer and sphingomyelin, SM) form more tightly packed gel domains than those formed by phospholipids with similar acyl chain length. In more complex lipid mixtures, the interaction between the different lipids is intricate and is strongly dictated by the Cer-to-Chol ratio. The results show that in quaternary phospholipid/SM/Chol/Cer mixtures, Cer forms gel domains that become less packed as Chol is increased. Moreover, the extent of gel phase formation is strongly reduced in these mixtures, even though Cer molar fraction is increased. These results suggest that in biological membranes, lipid domains such as rafts and ceramide platforms, might display distinctive biophysical properties depending on the local lipid composition at the site of the membrane where they are formed, further highlighting the potential role of membrane biophysical properties as an underlying mechanism for mediating specific biological processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Acyl chain asymmetry and polyunsaturation of brain phospholipids facilitate membrane vesiculation without leakage

PubMed Central

Manni, Marco M; Tiberti, Marion L; Pagnotta, Sophie; Barelli, Hélène; Gautier, Romain

2018-01-01

Phospholipid membranes form cellular barriers but need to be flexible enough to divide by fission. Phospholipids generally contain a saturated fatty acid (FA) at position sn1 whereas the sn2-FA is saturated, monounsaturated or polyunsaturated. Our understanding of the impact of phospholipid unsaturation on membrane flexibility and fission is fragmentary. Here, we provide a comprehensive view of the effects of the FA profile of phospholipids on membrane vesiculation by dynamin and endophilin. Coupled to simulations, this analysis indicates that: (i) phospholipids with two polyunsaturated FAs make membranes prone to vesiculation but highly permeable; (ii) asymmetric sn1-saturated-sn2-polyunsaturated phospholipids provide a tradeoff between efficient membrane vesiculation and low membrane permeability; (iii) When incorporated into phospholipids, docosahexaenoic acid (DHA; omega-3) makes membranes more deformable than arachidonic acid (omega-6). These results suggest an explanation for the abundance of sn1-saturated-sn2-DHA phospholipids in synaptic membranes and for the importance of the omega-6/omega-3 ratio on neuronal functions. PMID:29543154

The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: a comparison of serum, synovial fluid, albumin, EDTA, and water.

PubMed

Lewis, A C; Kilburn, M R; Heard, P J; Scott, T B; Hallam, K R; Allen, G C; Learmonth, I D

2006-08-01

Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition.

Sperry Low Temperature Geothermal Conversion System, Phase 1 and Phase 2. Volume 3: Systems description

NASA Astrophysics Data System (ADS)

Matthews, H. B.

The major fraction of hydrothermal resources with the prospect of economic usefulness for the generation of electricity are in the 300(0)F to 425(0)F temperature range. Cost effective conversion of the geothermal energy to electricity requires new ideas to improve conversion efficiency, enhance brine flow, reduce plant costs, increase plant availability, and shorten the time between investment and return. The problems addressed are those inherent in the geothermal environment, in the binary fluid cycle, in the difficulty of efficiently converting the energy of a low temperature resource, and in geothermal economics some of these problems are explained. The energy expended by the down hole pump; the difficulty in designing reliable down hole equipment; fouling of heat exchanger surfaces by geothermal fluids; the unavailability of condenser cooling water at most geothermal sites; the large portion of the available energy used by the feed pump in a binary system; the pinch effect, a loss in available energy in transferring heat from water to an organic fluid; flow losses in fluids that carry only a small amount of useful energy to begin with; high heat exchanger costs, the lower the temperature interval of the cycle, the higher the heat exchanger costs in $/kW; the complexity and cost of the many auxiliary elements of proposed geothermal plants; and the unfortunate cash flow vs. investment curve caused by the many years of investment required to bring a field into production before any income is realized.

Nonenzymatic Reactions above Phospholipid Surfaces of Biological Membranes: Reactivity of Phospholipids and Their Oxidation Derivatives

PubMed Central

Solís-Calero, Christian; Ortega-Castro, Joaquín; Frau, Juan; Muñoz, Francisco

2015-01-01

Phospholipids play multiple and essential roles in cells, as components of biological membranes. Although phospholipid bilayers provide the supporting matrix and surface for many enzymatic reactions, their inherent reactivity and possible catalytic role have not been highlighted. As other biomolecules, phospholipids are frequent targets of nonenzymatic modifications by reactive substances including oxidants and glycating agents which conduct to the formation of advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs). There are some theoretical studies about the mechanisms of reactions related to these processes on phosphatidylethanolamine surfaces, which hypothesize that cell membrane phospholipids surface environment could enhance some reactions through a catalyst effect. On the other hand, the phospholipid bilayers are susceptible to oxidative damage by oxidant agents as reactive oxygen species (ROS). Molecular dynamics simulations performed on phospholipid bilayers models, which include modified phospholipids by these reactions and subsequent reactions that conduct to formation of ALEs and AGEs, have revealed changes in the molecular interactions and biophysical properties of these bilayers as consequence of these reactions. Then, more studies are desirable which could correlate the biophysics of modified phospholipids with metabolism in processes such as aging and diseases such as diabetes, atherosclerosis, and Alzheimer's disease. PMID:25977746

Development of a Direct Contact Heat Exchanger, Phase 1 Study Report

NASA Technical Reports Server (NTRS)

Manvi, R.

1978-01-01

Electric power generation from geothermal brine requires, first, bringing the hot brine to the surface and then converting the heat to electric power. Binary conversion schemes were proposed, with the heat transfer between the brine and the working organic fluid taking place in a conventional tube and shell heat exchanger. If the brine is heavily laden with dissolved solids, however, solids buildup on the heat exchanger surfaces leads to a considerable degree of fouling and an accompanying drop in performance is experienced. A possible solution to this problem is the use of a direct contact exchanger with the secondary fluid power cycle. The proposed concept involves the formation of fluid sheets and bells as heat angles. Results of a study concerning the fluid mechanics of such surfaces are given.

Metal/ceramic composites with high hydrogen permeability

DOEpatents

Dorris, Stephen E.; Lee, Tae H.; Balachandran, Uthamalingam

2003-05-27

A membrane for separating hydrogen from fluids is provided comprising a sintered homogenous mixture of a ceramic composition and a metal. The metal may be palladium, niobium, tantalum, vanadium, or zirconium or a binary mixture of palladium with another metal such as niobium, silver, tantalum, vanadium, or zirconium.

Two-dimensional Turbulence in Symmetric Binary-Fluid Mixtures: Coarsening Arrest by the Inverse Cascade

NASA Astrophysics Data System (ADS)

Perlekar, Prasad; Pal, Nairita; Pandit, Rahul

2017-03-01

We study two-dimensional (2D) binary-fluid turbulence by carrying out an extensive direct numerical simulation (DNS) of the forced, statistically steady turbulence in the coupled Cahn-Hilliard and Navier-Stokes equations. In the absence of any coupling, we choose parameters that lead (a) to spinodal decomposition and domain growth, which is characterized by the spatiotemporal evolution of the Cahn-Hilliard order parameter ϕ, and (b) the formation of an inverse-energy-cascade regime in the energy spectrum E(k), in which energy cascades towards wave numbers k that are smaller than the energy-injection scale kin j in the turbulent fluid. We show that the Cahn-Hilliard-Navier-Stokes coupling leads to an arrest of phase separation at a length scale Lc, which we evaluate from S(k), the spectrum of the fluctuations of ϕ. We demonstrate that (a) Lc ~ LH, the Hinze scale that follows from balancing inertial and interfacial-tension forces, and (b) Lc is independent, within error bars, of the diffusivity D. We elucidate how this coupling modifies E(k) by blocking the inverse energy cascade at a wavenumber kc, which we show is ≃2π/Lc. We compare our work with earlier studies of this problem.

Two-dimensional Turbulence in Symmetric Binary-Fluid Mixtures: Coarsening Arrest by the Inverse Cascade.

PubMed

Perlekar, Prasad; Pal, Nairita; Pandit, Rahul

2017-03-21

We study two-dimensional (2D) binary-fluid turbulence by carrying out an extensive direct numerical simulation (DNS) of the forced, statistically steady turbulence in the coupled Cahn-Hilliard and Navier-Stokes equations. In the absence of any coupling, we choose parameters that lead (a) to spinodal decomposition and domain growth, which is characterized by the spatiotemporal evolution of the Cahn-Hilliard order parameter ϕ, and (b) the formation of an inverse-energy-cascade regime in the energy spectrum E(k), in which energy cascades towards wave numbers k that are smaller than the energy-injection scale kin j in the turbulent fluid. We show that the Cahn-Hilliard-Navier-Stokes coupling leads to an arrest of phase separation at a length scale Lc, which we evaluate from S(k), the spectrum of the fluctuations of ϕ. We demonstrate that (a) Lc ~ LH, the Hinze scale that follows from balancing inertial and interfacial-tension forces, and (b) Lc is independent, within error bars, of the diffusivity D. We elucidate how this coupling modifies E(k) by blocking the inverse energy cascade at a wavenumber kc, which we show is ≃2π/Lc. We compare our work with earlier studies of this problem.

Binary vapor cycle method of electrical power generation

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

Humiston, G.F.

1982-04-13

A binary vapor cycle method of electrical power generation is disclosed wherein two refrigerant fluids can be used to operate an apparatus for the generation of mechanical power as well as electrical power generation. This method, which is essentially a dual heat pump system, offers an approach to utilizing the advantages of two different refrigerants within a single apparatus. This advantage is particularly advantageous in the ulitization of low specific energy sources, such as two water sources which exist in close proximity to each other, but at different temperatures. Thus, water, which itself is a heat pump fluid, can bemore » used as a means of transmitting heat energy to a second heat pump fluid, or refrigerant, without incurring the disadvantages of water, or water vapors, as a means to produce power, because of its high specific volume and low saturation pressures at low temperatures. Additionally, since the warm water source of energy most commonly available is in the form of reservoirs, such as the ocean waters, and the utilization of barometric legs to bring the warm water into contact with the process, eliminates the use of expensive heat exchangers, which is the case of ocean water, are subject to fouling and loss of efficiency due to clinging microorganisms.« less

Suppression of turbulent energy cascade due to phase separation in homogenous binary mixture fluid

NASA Astrophysics Data System (ADS)

Takagi, Youhei; Okamoto, Sachiya

2015-11-01

When a multi-component fluid mixture becomes themophysically unstable state by quenching from well-melting condition, phase separation due to spinodal decomposition occurs, and a self-organized structure is formed. During phase separation, free energy is consumed for the structure formation. In our previous report, the phase separation in homogenous turbulence was numerically simulated and the coarsening process of phase separation was discussed. In this study, we extended our numerical model to a high Schmidt number fluid corresponding to actual polymer solution. The governing equations were continuity, Navier-Stokes, and Chan-Hiliard equations as same as our previous report. The flow filed was an isotropic homogenous turbulence, and the dimensionless parameters in the Chan-Hilliard equation were estimated based on the thermophysical condition of binary mixture. From the numerical results, it was found that turbulent energy cascade was drastically suppressed in the inertial subrange by phase separation for the high Schmidt number flow. By using the identification of turbulent and phase separation structure, we discussed the relation between total energy balance and the structures formation processes. This study is financially supported by the Grand-in-Aid for Young Scientists (B) (No. T26820045) from the Ministry of Education, Cul-ture, Sports, Science and Technology of Japan.

Two-dimensional Turbulence in Symmetric Binary-Fluid Mixtures: Coarsening Arrest by the Inverse Cascade

PubMed Central

Perlekar, Prasad; Pal, Nairita; Pandit, Rahul

2017-01-01

We study two-dimensional (2D) binary-fluid turbulence by carrying out an extensive direct numerical simulation (DNS) of the forced, statistically steady turbulence in the coupled Cahn-Hilliard and Navier-Stokes equations. In the absence of any coupling, we choose parameters that lead (a) to spinodal decomposition and domain growth, which is characterized by the spatiotemporal evolution of the Cahn-Hilliard order parameter ϕ, and (b) the formation of an inverse-energy-cascade regime in the energy spectrum E(k), in which energy cascades towards wave numbers k that are smaller than the energy-injection scale kin j in the turbulent fluid. We show that the Cahn-Hilliard-Navier-Stokes coupling leads to an arrest of phase separation at a length scale Lc, which we evaluate from S(k), the spectrum of the fluctuations of ϕ. We demonstrate that (a) Lc ~ LH, the Hinze scale that follows from balancing inertial and interfacial-tension forces, and (b) Lc is independent, within error bars, of the diffusivity D. We elucidate how this coupling modifies E(k) by blocking the inverse energy cascade at a wavenumber kc, which we show is ≃2π/Lc. We compare our work with earlier studies of this problem. PMID:28322219

Evaporation of binary mixtures in microgravity

NASA Technical Reports Server (NTRS)

Girgis, Morris; Matta, Nabil; Kolli, Kiran; Brown, Leon; Chubb, Kevin

1995-01-01

The motivation of this research is to obtain a better understanding of phase-change heat transfer within single and binary liquid meniscii, both in 1-g and 0-g environments. During phase 1 and part of phase 2, in a glass test cell with an inclined heated plate, 1-6 experiments on pentane with additions of decane up to 3% were conducted to determine the optimum concentration that will exhibit the maximum heat transfer and stability. During phase 2 emphasis was given to explore fundamental research issues and to ultimately develop a reliable capillary pumped loop (CPL) device for low gravity. In related experimental work, it was found that thermocapillary stresses near the contract line could result in a degraded wettability which ultimately could explain the observed failure of CPL devices in zero-gravity environment. Therefore, the current experimental effort investigates the effect of adding binary constituents in improving the thermocapillary characteristics near the contact line within the loop configuration. Achievements during second phase include: (1) Further enhancement of Central State University's Microgravity Laboratory by adding or improving upon capabilities of photography, video imaging, fluid visualization, and general experimental testing capabilities; (2) Experimental results for the inclined plate cell; (3) Modeling effort with a detailed scaling analysis; (4) Additional testing with a tube loop configuration to extend experimental work by Dickens, et al.; (5) Fabrication of a capillary loop to be tested using binary fluid (pentane/decane). The device that has been recently completed will be set up horizontally so that the effect of gravity on the performance is negligible. Testing will cover a wide range of parameters such as decane/pentane concentration, heat input value, heat input location (below or above meniscus), and loop temperature.

Interaction of human synovial phospholipase A2 with mixed lipid bilayers: a coarse-grain and all-atom molecular dynamics simulation study.

PubMed

Qin, Shan-Shan; Yu, Yang-Xin; Li, Qi-Kai; Yu, Zhi-Wu

2013-02-26

Human secreted phospholipase A2s have been shown to promote inflammation in mammals by catalyzing the first step of the arachidonic acid pathway by breaking down phospholipids, producing fatty acids, including arachidonic acid. They bind to the membrane water interface to access their phospholipid substrates from the membrane. Their binding modes on membrane surfaces are regulated by diverse factors, including membrane charge, fluidity, and heterogeneity. The influence of these factors on the binding modes of the enzymes is not well understood. Here we have studied several human synovial phospholipase A2 (hs-PLA2)/mixed bilayer systems through a combined coarse-grain and all-atom molecular dynamics simulation. It was found that hydrophobic residues Leu2, Val3, Ala18, Leu19, Phe23, Gly30, and Phe63 that form the edge of the entrance of the hydrophobic binding pocket in hs-PLA2 tend to penetrate into the hydrophobic area of lipid bilayers, and more than half of the total amino acid residues make contact with the lipid headgroups. Each enzyme molecule forms 19-38 hydrogen bonds with the bilayer to which it binds, most of which are with the phosphate groups. Analysis of the root-mean-square deviation (rmsd) shows that residues Val30-Thr40, Tyr66-Gln80, and Lys107-Arg118 have relatively large rmsds during all-atom molecular dynamics simulations, in accordance with the observation of an enlarged entrance region of the hydrophobic binding pocket. The amino acid sequences forming the entrance of the binding pocket prefer to interact with lipid molecules that are more fluid or negatively charged, and the opening of the binding pocket would be larger when the lipid components are more fluid.

Atomistic Monte Carlo Simulation of Lipid Membranes

PubMed Central

Wüstner, Daniel; Sklenar, Heinz

2014-01-01

Biological membranes are complex assemblies of many different molecules of which analysis demands a variety of experimental and computational approaches. In this article, we explain challenges and advantages of atomistic Monte Carlo (MC) simulation of lipid membranes. We provide an introduction into the various move sets that are implemented in current MC methods for efficient conformational sampling of lipids and other molecules. In the second part, we demonstrate for a concrete example, how an atomistic local-move set can be implemented for MC simulations of phospholipid monomers and bilayer patches. We use our recently devised chain breakage/closure (CBC) local move set in the bond-/torsion angle space with the constant-bond-length approximation (CBLA) for the phospholipid dipalmitoylphosphatidylcholine (DPPC). We demonstrate rapid conformational equilibration for a single DPPC molecule, as assessed by calculation of molecular energies and entropies. We also show transition from a crystalline-like to a fluid DPPC bilayer by the CBC local-move MC method, as indicated by the electron density profile, head group orientation, area per lipid, and whole-lipid displacements. We discuss the potential of local-move MC methods in combination with molecular dynamics simulations, for example, for studying multi-component lipid membranes containing cholesterol. PMID:24469314

Biomimetic DNA emulsions: specific, thermo-reversible and adjustable binding from a liquid-like DNA layer

NASA Astrophysics Data System (ADS)

Pontani, Lea-Laetitia; Feng, Lang; Dreyfus, Remi; Seeman, Nadrian; Chaikin, Paul; Brujic, Jasna

2013-03-01

We develop micron-sized emulsions coated with specific DNA sequences and complementary sticky ends. The emulsions are stabilized with phospholipids on which the DNA strands are grafted through biotin-streptavidin interactions, which allows the DNA to diffuse freely on the surface. We produce two complementary emulsions: one is functionalized with S sticky ends and dyed with red streptavidin, the other displays the complementary S' sticky ends and green streptavidin. Mixing those emulsions reveals specific adhesion between them due to the short-range S-S' hybridization. As expected this interaction is thermo-reversible: the red-green adhesive droplets dissociate upon heating and reassemble after cooling. Here the fluid phospholipids layer also leads to diffusive adhesion patches, which allows the bound droplets to rearrange throughout the packing structure. We quantify the adhesion strength between two droplets and build a theoretical framework that captures the observed trends through parameters such as the size of the droplets, the DNA surface density, the various DNA constructs or the temperature. This colloidal-scale, specific, thermo-reversible biomimetic emulsion offers a new versatile and powerful tool for the development of complex self-assembled materials.

[The determination of pulmonary phospholipids in the gastric contents for an assessment of the respiratory distress syndrome].

PubMed

Cano-González, R; Udaeta-Mora, E; Sosa-Ceja, R; Fernández-Carrocera, L

1992-06-01

Since hyaline membrane disease (HMD) is an important cause of mortality and morbidity in preterm newborns, we decided to evaluate the utility of pulmonary phospholipid (PP) determination in gastric aspirate for confirmatory diagnosis. For that purpose we studied 31 preterm and 30 term babies and compared the results between them and PP in gastric aspirate and amniotic fluid from their mothers. All the term newborns were normal, with mean weight of 3,221, and 39 weeks of gestational age; the results of phosphatidyl inositol (PI) and phosphatidyl glycerol (PG) were positive. The premature babies had a mean weight of 2,424 g and 35 weeks of gestational age. Thirteen had respiratory distress, 4 transient tachypnea and 9 HMD. In this group the babies with PI present and PG absent developed respiratory distress without HMD. The test had sensibility of 69% and specificity of 100%, and in patients without PG and PI the sensibility and specificity was 100%. We concluded that this test has enough sensibility and specificity for the confirmation of HMD in gastric aspirate when the PI and PG are not present.

[Comparison of long-chain polyunsaturated fatty acids in plasma and erythrocyte phospholipids for biological monitoring].

PubMed

Kawabata, Terue; Nakai, Kunihiko; Hagiwara, Chie; Kurokawa, Naoyuki; Murata, Katsuyuki; Yaginuma, Kozue; Satoh, Hiroshi

2011-01-01

Previous data have indicated that the erythrocyte membrane may be the preferred sample type for assessing long-chain polyunsaturated fatty acid (LCPUFA) contents in cardiac and cerebral membranes. In this epidemiological study, we examined whether plasma phospholipids can be used for accurate biological monitoring of the LCPUFA state or whether analysis of erythrocyte membrane phospholipids is indispensable. (1) The analysis of LCPUFA contents in erythrocyte membrane phospholipids was conducted at baseline and after 1 and 3 days at 4°C, and 21 days at -40°C, after blood drawing, and the changes in LCPUFA content were examined. (2) The LCPUFA compositions of plasma and erythrocyte phospholipids in 133 young women (18-30 years old) were examined and the relationships between the sample type and the levels of LCPUFAs were determined. Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and DHA/arachidonic acid (AA) and (EPA+DHA)/AA ratios in erythrocyte membrane phospholipids after 21 days of blood drawing significantly decreased compared with the corresponding baseline data. Regarding AA, EPA and DHA, a significant positive correlation was shown between levels of erythrocyte membrane phospholipids and plasma phospholipids (AA, r=0.364; EPA, r=0.709; DHA, r=0.653). The predictive value of plasma phospholipids for determining the highest concentration quartile in erythrocyte phospholipids was better in EPA (70%) than in DHA (55%) and AA (42%). The measurement of LCPUFA content in erythrocyte membrane phospholipids is necessary for accurate biological monitoring. We also found that LCPUFA in erythrocyte membrane phospholipids is stable in cold storage (4°C) for 3 days after blood drawing.

'De-watering' capabilities of surfactants in human amniotic fluid.

PubMed Central

Hills, B A

1984-01-01

The phospholipid extracts from each of eleven samples of human amniotic fluid obtained from eleven full-term births were deposited as orientated monolayers adsorbed to glass. The surfaces were found to be rendered hydrophobic with maximum contact angles averaging 54.5 degrees while, upon withdrawing fluid, the edge of the saline pool receded to expose dry surface with minimum contact angles averaging 15.4 degrees. The extracts were found to be surface-active at the liquid-air interface and there was some indication that direct adsorption to solid surfaces was facilitated by calcium ions. It was found that, in all extracts, a continuous layer of saline adjacent to the adsorbed surface would break up spontaneously to expose dry surface when the thickness was reduced to an average of 764 micron, corresponding to several alveolar diameters. This phenomenon is discussed as a possible means of establishing dry patches on the alveolar membrane, especially in the new-born after the fetal alveolar wall has been exposed to the same surfactants in much the same physical form as found in amniotic fluid. Surfactant adsorbed directly to the tissue subphase is suggested as a physical basis for the discontinuity of the aqueous hypophase seen in many electron micrographs of the adult alveolus. This 'de-watering' of the alveolar surface could facilitate gas transfer. PMID:6546947

An adaptive mesh refinement-multiphase lattice Boltzmann flux solver for simulation of complex binary fluid flows

NASA Astrophysics Data System (ADS)

Yuan, H. Z.; Wang, Y.; Shu, C.

2017-12-01

This paper presents an adaptive mesh refinement-multiphase lattice Boltzmann flux solver (AMR-MLBFS) for effective simulation of complex binary fluid flows at large density ratios. In this method, an AMR algorithm is proposed by introducing a simple indicator on the root block for grid refinement and two possible statuses for each block. Unlike available block-structured AMR methods, which refine their mesh by spawning or removing four child blocks simultaneously, the present method is able to refine its mesh locally by spawning or removing one to four child blocks independently when the refinement indicator is triggered. As a result, the AMR mesh used in this work can be more focused on the flow region near the phase interface and its size is further reduced. In each block of mesh, the recently proposed MLBFS is applied for the solution of the flow field and the level-set method is used for capturing the fluid interface. As compared with existing AMR-lattice Boltzmann models, the present method avoids both spatial and temporal interpolations of density distribution functions so that converged solutions on different AMR meshes and uniform grids can be obtained. The proposed method has been successfully validated by simulating a static bubble immersed in another fluid, a falling droplet, instabilities of two-layered fluids, a bubble rising in a box, and a droplet splashing on a thin film with large density ratios and high Reynolds numbers. Good agreement with the theoretical solution, the uniform-grid result, and/or the published data has been achieved. Numerical results also show its effectiveness in saving computational time and virtual memory as compared with computations on uniform meshes.

Modeling the phase behavior of H2S+n-alkane binary mixtures using the SAFT-VR+D approach.

PubMed

dos Ramos, M Carolina; Goff, Kimberly D; Zhao, Honggang; McCabe, Clare

2008-08-07

A statistical associating fluid theory for potential of variable range has been recently developed to model dipolar fluids (SAFT-VR+D) [Zhao and McCabe, J. Chem. Phys. 2006, 125, 104504]. The SAFT-VR+D equation explicitly accounts for dipolar interactions and their effect on the thermodynamics and structure of a fluid by using the generalized mean spherical approximation (GMSA) to describe a reference fluid of dipolar square-well segments. In this work, we apply the SAFT-VR+D approach to real mixtures of dipolar fluids. In particular, we examine the high-pressure phase diagram of hydrogen sulfide+n-alkane binary mixtures. Hydrogen sulfide is modeled as an associating spherical molecule with four off-center sites to mimic hydrogen bonding and an embedded dipole moment (micro) to describe the polarity of H2S. The n-alkane molecules are modeled as spherical segments tangentially bonded together to form chains of length m, as in the original SAFT-VR approach. By using simple Lorentz-Berthelot combining rules, the theoretical predictions from the SAFT-VR+D equation are found to be in excellent overall agreement with experimental data. In particular, the theory is able to accurately describe the different types of phase behavior observed for these mixtures as the molecular weight of the alkane is varied: type III phase behavior, according to the scheme of classification by Scott and Konynenburg, for the H2S+methane system, type IIA (with the presence of azeotropy) for the H2S+ethane and+propane mixtures; and type I phase behavior for mixtures of H2S and longer n-alkanes up to n-decane. The theory is also able to predict in a qualitative manner the solubility of hydrogen sulfide in heavy n-alkanes.

Coarsening dynamics of binary liquids with active rotation.

PubMed

Sabrina, Syeda; Spellings, Matthew; Glotzer, Sharon C; Bishop, Kyle J M

2015-11-21

Active matter comprised of many self-driven units can exhibit emergent collective behaviors such as pattern formation and phase separation in both biological (e.g., mussel beds) and synthetic (e.g., colloidal swimmers) systems. While these behaviors are increasingly well understood for ensembles of linearly self-propelled "particles", less is known about the collective behaviors of active rotating particles where energy input at the particle level gives rise to rotational particle motion. A recent simulation study revealed that active rotation can induce phase separation in mixtures of counter-rotating particles in 2D. In contrast to that of linearly self-propelled particles, the phase separation of counter-rotating fluids is accompanied by steady convective flows that originate at the fluid-fluid interface. Here, we investigate the influence of these flows on the coarsening dynamics of actively rotating binary liquids using a phenomenological, hydrodynamic model that combines a Cahn-Hilliard equation for the fluid composition with a Navier-Stokes equation for the fluid velocity. The effect of active rotation is introduced though an additional force within the Navier-Stokes equations that arises due to gradients in the concentrations of clockwise and counter-clockwise rotating particles. Depending on the strength of active rotation and that of frictional interactions with the stationary surroundings, we observe and explain new dynamical behaviors such as "active coarsening" via self-generated flows as well as the emergence of self-propelled "vortex doublets". We confirm that many of the qualitative behaviors identified by the continuum model can also be found in discrete, particle-based simulations of actively rotating liquids. Our results highlight further opportunities for achieving complex dissipative structures in active materials subject to distributed actuation.

Binary pulsars as probes of a Galactic dark matter disk

NASA Astrophysics Data System (ADS)

Caputo, Andrea; Zavala, Jesús; Blas, Diego

2018-03-01

As a binary pulsar moves through a wind of dark matter particles, the resulting dynamical friction modifies the binary's orbit. We study this effect for the double disk dark matter (DDDM) scenario, where a fraction of the dark matter is dissipative and settles into a thin disk. For binaries within the dark disk, this effect is enhanced due to the higher dark matter density and lower velocity dispersion of the dark disk, and due to its co-rotation with the baryonic disk. We estimate the effect and compare it with observations for two different limits in the Knudsen number (Kn). First, in the case where DDDM is effectively collisionless within the characteristic scale of the binary (Kn ≫ 1) and ignoring the possible interaction between the pair of dark matter wakes. Second, in the fully collisional case (Kn ≪ 1), where a fluid description can be adopted and the interaction of the pair of wakes is taken into account. We find that the change in the orbital period is of the same order of magnitude in both limits. A comparison with observations reveals good prospects to probe currently allowed DDDM models with timing data from binary pulsars in the near future. We finally comment on the possibility of extending the analysis to the intermediate (rarefied gas) case with Kn ∼ 1.

RNA and DNA interactions with zwitterionic and charged lipid membranes - a DSC and QCM-D study.

PubMed

Michanek, Agnes; Kristen, Nora; Höök, Fredrik; Nylander, Tommy; Sparr, Emma

2010-04-01

The aim of the present study is to establish under which conditions tRNA associates with phospholipid bilayers, and to explore how this interaction influences the lipid bilayer. For this purpose we have studied the association of tRNA or DNA of different sizes and degrees of base pairing with a set of model membrane systems with varying charge densities, composed of zwitterionic phosphatidylcholines (PC) in mixtures with anionic phosphatidylserine (PS) or cationic dioctadecyl-dimethyl-ammoniumbromide (DODAB), and with fluid or solid acyl-chains (oleoyl, myristoyl and palmitoyl). To prove and quantify the attractive interaction between tRNA and model-lipid membrane we used quartz crystal microbalance with dissipation (QCM-D) monitoring to study the tRNA adsorption to deposit phospholipid bilayers from solutions containing monovalent (Na(+)) or divalent (Ca(2+)) cations. The influence of the adsorbed polynucleic acids on the lipid phase transitions and lipid segregation was studied by means of differential scanning calorimetry (DSC). The basic findings are: i) tRNA adsorbs to zwitterionic liquid-crystalline and gel-phase phospholipid bilayers. The interaction is weak and reversible, and cannot be explained only on the basis of electrostatic attraction. ii) The adsorbed amount of tRNA is higher for liquid-crystalline bilayers compared to gel-phase bilayers, while the presence of divalent cations show no significant effect on the tRNA adsorption. iii) The adsorption of tRNA can lead to segregation in the mixed 1,2-dimyristoyl-sn-glycerol-3-phosphatidylcholine (DMPC)-1,2-dimyristoyl-sn-glycero-3-phosphatidylserine (DMPS) and DMPC-DODAB bilayers, where tRNA is likely excluded from the anionic DMPS-rich domains in the first system, and associated with the cationic DODAB-rich domains in the second system. iv) The addition of shorter polynucleic acids influence the chain melting transition and induce segregation in a mixed DMPC-DMPS system, while larger polynucleic acids do not influence the melting transition in these system. The results in this study on tRNA-phospholipid interactions can have implications for understanding its biological function in, e.g., the cell nuclei, as well as in applications in biotechnology and medicine. Copyright 2010 Elsevier B.V. All rights reserved.

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

Holser, Ronald A.; King, J. W.; Bost, G.

The genus Hibiscus exhibits great diversity in the production of natural materials with edible and industrial applications. The seeds of twelve varieties of Hibiscus were investigated as a source for triglycerides and phospholipids that could be used in functional foods. Lipid components were extracted from seed samples ground to a nominal particle diameter of 0.1 mm. Extractions were performed with an ISCO model 3560 supercritical fluid extractor using carbon dioxide and a mixture of carbon dioxide modified with ethanol. The neutral lipids were extracted with carbon dioxide at 80 C and 5370 MPa for 45 min. Polar lipids were subsequentlymore » extracted with a mixture of carbon dioxide and 15% ethanol at the same temperature and pressure. High performance liquid chromatography (HPLC) was used to analyze extracts for major neutral and polar lipid classes. A silica column was used with a solvent gradient of hexane/isopropanol/ water and ultraviolet (UV) and evaporative light scattering detectors (ELSD). An aliquot of each triglyceride fraction was trans-methylated with sodium methoxide and analyzed by gas chromatography to obtain the corresponding fatty acid methyl esters. The total lipids extracted ranged from 8.5% for a variety indigenous to Madagascar (H. calyphyllus) to 20% for a hybrid species (Georgia Rose). The average oil yield was 11.4% for the other varieties tested. The fatty acid methyl ester analysis displayed a high degree of unsaturation for all varieties tested, e. g., 75 ' 83%. Oleic, linoleic, and linolenic fatty acids were the predominate unsaturated fatty acids with only minor amounts of C14, C18, and C20 saturated fatty acids measured. Palmitic acid was identified as the predominate saturated fatty acid. The distribution of the major phospholipids, i. e., phosphatidylethanolamine, phosphatidic acid, phosphatidylserine, phosphatidylcholine, and lysophosphatidylcholine, was found to vary significantly among the hibiscus species examined. Phosphatidylcholine and lysophosphatidylcholine were the predominate phospholipids comprising between 50 and 95% of the total phospholipids present. Pressurized extraction techniques provide a rapid method to separate both polar and nonpolar lipids from Hibiscus seeds using carbon dioxide and ethanol mixtures. The seeds require a minimum of processing prior to extraction and the extracts obtained are solvent free and suitable for edible products.« less

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.

Crystallization of pure anhydrous polymorphs of carbamazepine by solution enhanced dispersion with supercritical fluids (SEDS).

PubMed

Edwards, A D; Shekunov, B Y; Kordikowski, A; Forbes, R T; York, P

2001-08-01

Pure anhydrous polymorphs of carbamazepine were prepared by solution-enhanced dispersion with supercritical fluids (SEDS). Crystallization of the polymorphs was studied. Mechanisms are proposed that consider the thermodynamics of carbamazepine, supersaturation in the SEDS process, and the binary phase equilibria of organic solvents and the carbon dioxide antisolvent. alpha-Carbamazepine was crystallized at high supersaturations and low temperatures, beta-carbamazepine crystallized from a methanol-carbon dioxide phase split, and gamma-carbamazepine crystallized via nucleation at high temperatures and low supersaturation. Copyright 2001 Wiley-Liss, Inc.

Dynamical studies of confined fluids and polymers

NASA Astrophysics Data System (ADS)

Grabowski, Christopher A.

Soft matter, a class of materials including polymers, colloids, and surfactant molecules, are ubiquitous in our everyday lives. Plastics, soaps, foods and living organisms are mostly comprised of soft materials. Research conducted to understand soft matter behavior at the molecular level is essential to create new materials with unique properties. Self-healing plastics, targeted drug delivery, and nanowire assemblies have all been further advanced by soft matter research. The author of this dissertation investigates fundamental soft matter systems, including polymer solutions and melts, colloid dispersions in polymer melts, and interfacial fluids. The dynamics of polymers and confined fluids were studied using the single-molecule sensitive technique of fluorescence correlation spectroscopy (FCS). Here, fluorescent dyes are attached to polymer coils or by introducing free dyes directly into the solution/film. Complementary experiments were also performed, utilizing atomic force microscopy (AFM) and ellipsometry. FCS and AFM experiments demonstrated the significant difference in properties of thin fluid films of the nearly spherical, nonpolar molecule TEHOS (tetrakis(2-ethylhexoxy)silane) when compared to its bulk counterpart. AFM experiments confirmed TEHOS orders in layers near a solid substrate. FCS experiments show that free dyes introduced in these thin films do not have a single diffusion coefficient, indicating that these films have heterogeneity at the molecular level. FCS experiments have been applied to study the diffusion of gold colloids. The diffusion of gold colloids in polymer melts was found to dramatically depart from the Stokes-Einstein prediction when colloid size was smaller than the surrounding polymer mesh size. This effect is explained by noting the viscosity experienced by the colloid is not equivalent to the overall bulk viscosity of the polymer melt. The conformational change of polymers immersed in a binary solvent was measured via FCS. This experiment was conducted to test a theory proposed by Brochard and de Gennes, who postulated a polymer chain undergoes a collapse and a dramatic re-swelling as the critical point of the binary mixture is approached. Measuring polymer chain diffusion as a function of temperature, this theory was confirmed. To my knowledge, this was the first experimental evidence of contraction/re-swelling for polymers in critical binary solvents.

Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures

NASA Astrophysics Data System (ADS)

Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans

2009-02-01

For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.

Characterization of potential plasma biomarkers related to cognitive impairment by untargeted profiling of phospholipids using the HILIC-ESI-IT-TOF-MS system.

PubMed

Song, Shuang; Cheong, Ling-Zhi; Man, Qing-Qing; Pang, Shao-Jie; Li, Yue-Qi; Ren, Biao; Zhang, Jian

2018-05-01

Early diagnosis of neural changes causing cognitive impairment is critical for development of preventive therapies for dementia. Biomarkers currently characterized cannot be extensively applied due to the invasive sampling of cerebrospinal fluid. The other imaging approaches are either expensive or require a high technique. Phospholipids (PLs), which are basic constituents of neurons, might be a key variable in the pathogenesis of cognitive impairment. Changes in plasma PL provide the possibility for development of novel biomarkers with minimal invasion and high patient acceptance. In this work, a HILIC-ESI-IT-TOF-MS system was introduced for untargeted profiling of plasma PLs to investigate the relationship between changes of plasma PL profiles and cognitive impairment. A total of 272 types of PL molecular structures were characterized in human plasma and quantified through the internal standard method. Univariate analysis shows 29 PLs were significantly different between the control (n = 41) and the cognitive impairment (CI) group (n = 41). Multivariate analysis (PCA and OPLS-DA) was conducted based on these 29 potential PL biomarkers. Both univariate and multivariate analyses show abnormality of PL metabolism in the CI group, and the downregulation of ethanolamine plasmalogen (pPE) supply, especially those with PUFAs, in the circulation system should be strongly associated with neurodegeneration. A discriminative model was established with satisfied fit (R2) and prediction (Q2) abilities, and the classification test showed better recognition of the CI group than the control group indicating that this model of PL biomarkers could be used as indicators for screening of CI. Graphical abstract Characterization of potential plasma biomarkers related to cognitive impairment by untargeted profiling of phospholipids.

On the structure of contact binaries. I - The contact discontinuity

NASA Technical Reports Server (NTRS)

Shu, F. H.; Lubow, S. H.; Anderson, L.

1976-01-01

The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

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.

Connexin channels and phospholipids: association and modulation

PubMed Central

Locke, Darren; Harris, Andrew L

2009-01-01

Background For membrane proteins, lipids provide a structural framework and means to modulate function. Paired connexin hemichannels form the intercellular channels that compose gap junction plaques while unpaired hemichannels have regulated functions in non-junctional plasma membrane. The importance of interactions between connexin channels and phospholipids is poorly understood. Results Endogenous phospholipids most tightly associated with purified connexin26 or connexin32 hemichannels or with junctional plaques in cell membranes, those likely to have structural and/or modulatory effects, were identified by tandem electrospray ionization-mass spectrometry using class-specific interpretative methods. Phospholipids were characterized by headgroup class, charge, glycerol-alkyl chain linkage and by acyl chain length and saturation. The results indicate that specific endogenous phospholipids are uniquely associated with either connexin26 or connexin32 channels, and some phospholipids are associated with both. Functional effects of the major phospholipid classes on connexin channel activity were assessed by molecular permeability of hemichannels reconstituted into liposomes. Changes to phospholipid composition(s) of the liposome membrane altered the activity of connexin channels in a manner reflecting changes to the surface charge/potential of the membrane and, secondarily, to cholesterol content. Together, the data show that connexin26 and connexin32 channels have a preference for tight association with unique anionic phospholipids, and that these, independent of headgroup, have a positive effect on the activity of both connexin26 and connexin32 channels. Additionally, the data suggest that the likely in vivo phospholipid modulators of connexin channel structure-function that are connexin isoform-specific are found in the cytoplasmic leaflet. A modulatory role for phospholipids that promote negative curvature is also inferred. Conclusion This study is the first to identify (endogenous) phospholipids that tightly associate with connexin channels. The finding that specific phospholipids are associated with different connexin isoforms suggests connexin-specific regulatory and/or structural interactions with lipid membranes. The results are interpreted in light of connexin channel function and cell biology, as informed by current knowledge of lipid-protein interactions and membrane biophysics. The intimate involvement of distinct phospholipids with different connexins contributes to channel structure and/or function, as well as plaque integrity, and to modulation of connexin channels by lipophilic agents. PMID:19686581

Evidence for a membrane defect in Alzheimer disease brain

NASA Technical Reports Server (NTRS)

Nitsch, R. M.; Blusztajn, J. K.; Pittas, A. G.; Slack, B. E.; Growdon, J. H.; Wurtman, R. J.

1992-01-01

To determine whether neurodegeneration in Alzheimer disease brain is associated with degradation of structural cell membrane molecules, we measured tissue levels of the major membrane phospholipids and their metabolites in three cortical areas from postmortem brains of Alzheimer disease patients and matched controls. Among phospholipids, there was a significant (P less than 0.05) decrease in phosphatidylcholine and phosphatidylethanolamine. There were significant (P less than 0.05) decreases in the initial phospholipid precursors choline and ethanolamine and increases in the phospholipid deacylation product glycerophosphocholine. The ratios of glycerophosphocholine to choline and glycerophosphoethanolamine to ethanolamine were significantly increased in all examined Alzheimer disease brain regions. The activity of the glycerophosphocholine-degrading enzyme glycerophosphocholine choline-phosphodiesterase was normal in Alzheimer disease brain. There was a near stoichiometric relationship between the decrease in phospholipids and the increase of phospholipid catabolites. These data are consistent with increased membrane phospholipid degradation in Alzheimer disease brain. Similar phospholipid abnormalities were not detected in brains of patients with Huntington disease, Parkinson disease, or Down syndrome. We conclude that the phospholipid abnormalities described here are not an epiphenomenon of neurodegeneration and that they may be specific for the pathomechanism of Alzheimer disease.

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

Lenné, T.; Kent, B.; Koster, K.L.

Small angle X-ray scattering is used to study the effects of sugars on membranes during dehydration. Previous work has shown that the bilayer and chain-chain repeat spacings of DPPC bilayers are relatively unaffected by the presence of sugars. In this work we present a preliminary analysis of the electron density profiles of DPPC in the presence of sugars at low hydration. The difficulties of determining the correct phasing are discussed. Sugars and other small solutes have been shown to have an important role in improving the tolerance of a range of species to desiccation and freezing. In particular it hasmore » been shown that sugars can stabilize membranes in the fluid membrane phase during dehydration, and in the fully dehydrated state. Equivalently, at a particular hydration, the presence of sugars lowers the transition temperature between the fluid and gel phases. There are two competing models for explaining the effects of sugars on membrane phase transition temperatures. One, designated the water replacement hypothesis (WRH) states that sugars hydrogen bond to phospholipid headgroups, thus hindering the fluid-gel phase transition. One version of this model suggests that certain sugars (such as trehalose) achieve the measured effects by inserting between the phospholipid head groups. An alternative model explains the observed effects of sugars in terms of the sugars effect on the hydration repulsion that develops between opposing membranes during dehydration. The hydration repulsion leads to a lateral compressive stress in the bilayer which squeezes adjacent lipids more closely together, resulting in a transition to the gel phase. When sugars are present, their osmotic and volumetric effects reduce the hydration repulsion, reduce the compressive stress in the membranes, and therefore tend to maintain the average lateral separation between lipids. This model is called the hydration forces explanation (HFE). We recently showed that neither mono- nor di-saccharides affect the average distance between lipid chains in the bilayer, supporting the predictions of the HFE. In this paper we further investigate the effects of sugars on membrane structure by conducting electron density analysis of recent data. This preliminary analysis sheds additional light onto the effects of sugars on membrane structure.« less

Butter making from caprine creams: effect of washing treatment on phospholipids and milk fat globule membrane proteins distribution.

PubMed

Lamothe, Sophie; Robitaille, Gilles; St-Gelais, Daniel; Britten, Michel

2008-11-01

A washing treatment was applied to caprine cream before churning in order to improve phospholipids and MFGM protein purification from buttermilk and butter serum. Cream obtained from a first separation was diluted with water and separated a second time using pilot plant equipment. Regular and washed creams were churned to produce buttermilk and butter, from which butter serum was extracted. The washing treatment allowed a significant decrease of the casein content. As a result, the phospholipids-to-protein ratios in washed buttermilk and butter serum were markedly increased by 2.1 and 1.7-folds respectively, which represents an advantage for the production of phospholipids concentrates. However, when compared with bovine cream, lower phospholipids-to-protein ratios were observed when the washing treatment was applied to caprine cream. A higher concentration of MFGM protein and a lower retention of phospholipids during washing treatment are responsible for the lower phospholipids-to-protein ratios in buttermilk and butter serum obtained from caprine cream. The phospholipids distribution in the butter making process was similar to the one obtained from bovine regular and washed cream. Phospholipids were preferentially concentrated in the butter serum rather than the buttermilk fraction. This simple approach permitted the production of caprine and bovine butter sera extracts containing up to 180 and 240 g phospholipids/kg sera, respectively, on a dry basis.

Octadecyl ferulate behavior in 1,2-Dioleoylphosphocholine liposomes

NASA Astrophysics Data System (ADS)

Evans, Kervin O.; Compton, David L.; Whitman, Nathan A.; Laszlo, Joseph A.; Appell, Michael; Vermillion, Karl E.; Kim, Sanghoon

2016-01-01

Octadecyl ferulate was prepared using solid acid catalyst, monitored using Supercritical Fluid Chromatography and purified to a 42% yield. Differential scanning calorimetry measurements determined octadecyl ferulate to have melting/solidification phase transitions at 67 and 39 °C, respectively. AFM imaging shows that 5-mol% present in a lipid bilayer induced domains to form. Phase behavior measurements confirmed that octadecyl ferulate increased transition temperature of phospholipids. Fluorescence measurements demonstrated that octadecyl ferulate stabilized liposomes against leakage, maintained antioxidant capacity within liposomes, and oriented such that the feruloyl moiety remained in the hydrophilic region of the bilayer. Molecular modeling calculation indicated that antioxidant activity was mostly influenced by interactions within the bilayer.

Supercritical fluid extraction and characterization of lipids from algae Scenedesmus obliquus

NASA Technical Reports Server (NTRS)

Choi, K. J.; Nakhost, Z.; Krukonis, V. J.; Karel, M.

1987-01-01

Lipids were extracted from a protein concentrate of green algae (Scenedesmus obliquus), using a one-step supercritical carbon dioxide extraction procedure in presence of ethanol as an entrainer, and were characterized. The compositions of neutral lipids, glycolipids, and phospholipids, separated into individual components by column, thin-layer, and gas-liquid chromatography procedures, are presented. Fatty acid composition patterns indicated that the major fatty acids were 16:0, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, and 18:3. The lipids of S. obliquus were found to contain relatively high concentrations of polyunsaturated fatty acids and essential fatty acids.

Speciation in experimental C-O-H fluids produced by the thermal dissociation of oxalic acid dihydrate

NASA Astrophysics Data System (ADS)

Morgan, G. B., VI; Chou, I.-Ming; Pasteris, J. D.

1992-01-01

Fluid speciations and their related reaction pathways were studied in C-O-H-system fluids produced by the thermal dissociation of oxalic acid dihydrate (OAD: H 2C 2O 4 · 2H 2O) sealed in silica glass capsules. Experiments were conducted in the temperature range 230-750°C, with bulk fluid densities in the range 0.01-0.53 g/cm 3. Pressure was controlled by temperature and density in the isochoric systems. The quenched products of dissociation experiments were an aqueous liquid and one (supercritical fluid) or, rarely, two (vapor plus liquid) carbonic phase (s). In-situ Raman microanalyses were performed on the quenched carbonic phases at room temperature, at which fluid pressures ranged from about 50 to 340 bars. Bulk fluid speciations were reconstructed from the Raman analyses via mass balance constraints, and appear to monitor the true fluid speciations at run conditions. In experiments from the lowtemperature range (230-350°C), fluid speciations record the dissociation of OAD according to the reaction OAD = CO2 + CO + 3 H2O. A process of the form CO + H2O = CO2 + H2 is driven to the right with increasing temperature. The hydrogen gas produced tends to escape from the sample systems via diffusion into/through the silica glass capsules, shifting bulk compositions toward equimolar binary H 2O-CO 2 mixtures. The speciations of fluids in experiments with minimal hydrogen loss show poor agreement with speciations calculated for equilibrium fluids by the corresponding-states model of SAXENA and FEI (1988). Such disagreement suggests that the formations of CH 4 and graphite are metastably inhibited in the current experiments, which correlates with their absence or trivial abundances in experimental products. Moreover, calculations in which the stabilities of methane and graphite are suppressed suggest that such metastable equilibrium is approached only in experiments at temperatures greater than about 600-650°C. These results have applications to fluid processes in geological environments, in addition to considerations of using oxalate compounds as volatile sources in experimental studies. It is possible that disequilibrium or metastable fluids may be entrapped as inclusions; re-speciation (toward metastable or stable equilibrium) during P-T evolution of a given terrain would place the fluid inclusion on a new isochore that would not project through the original conditions of entrapment. Moreover, the disequilibrium to metastable nature of dissociation reactions, coupled with the diffusional mobility of hydrogen gas observed in the current experiments, suggests that the predominance of binary H 2O-CO 2 fluid mixtures in natural inclusions from medium- to high-grade metamorphic terrains may be more than a coincidence of similar initial bulk compositions.

Speciation in experimental C-O-H fluids produced by the thermal dissociation of oxalic acid dihydrate

USGS Publications Warehouse

Morgan, G.B.; Chou, I.-Ming; Pasteris, J.D.

1992-01-01

Fluid speciations and their related reaction pathways were studied in C-O-H-system fluids produced by the thermal dissociation of oxalic acid dihydrate (OAD: H2C2O4 ?? 2H2O) sealed in silica glass capsules. Experiments were conducted in the temperature range 230-750??C, with bulk fluid densities in the range 0.01-0.53 g/cm3. Pressure was controlled by temperature and density in the isochoric systems. The quenched products of dissociation experiments were an aqueous liquid and one (supercritical fluid) or, rarely, two (vapor plus liquid) carbonic phase (s). In-situ Raman microanalyses were performed on the quenched carbonic phases at room temperature, at which fluid pressures ranged from about 50 to 340 bars. Bulk fluid speciations were reconstructed from the Raman analyses via mass balance constraints, and appear to monitor the true fluid speciations at run conditions. In experiments from the lowtemperature range (230-350??C), fluid speciations record the dissociation of OAD according to the reaction OAD = CO2 + CO + 3H2O. A process of the form CO + H2O = CO2 + H2 is driven to the right with increasing temperature. The hydrogen gas produced tends to escape from the sample systems via diffusion into/through the silica glass capsules, shifting bulk compositions toward equimolar binary H2O-CO2 mixtures. The speciations of fluids in experiments with minimal hydrogen loss show poor agreement with speciations calculated for equilibrium fluids by the corresponding-states model of Saxena and Fei (1988). Such disagreement suggests that the formations of CH4 and graphite are metastably inhibited in the current experiments, which correlates with their absence or trivial abundances in experimental products. Moreover, calculations in which the stabilities of methane and graphite are suppressed suggest that such metastable equilibrium is approached only in experiments at temperatures greater than about 600-650??C. These results have applications to fluid processes in geological environments, in addition to considerations of using oxalate compounds as volatile sources in experimental studies. It is possible that disequilibrium or metastable fluids may be entrapped as inclusions; re-speciation (toward metastable or stable equilibrium) during P-T evolution of a given terrain would place the fluid inclusion on a new isochore that would not project through the original conditions of entrapment. Moreover, the disequilibrium to metastable nature of dissociation reactions, coupled with the diffusional mobility of hydrogen gas observed in the current experiments, suggests that the predominance of binary H2O-CO2 fluid mixtures in natural inclusions from medium- to high-grade metamorphic terrains may be more than a coincidence of similar initial bulk compositions. ?? 1992.

[Effect of decamethoxine, decamine and levorin on the content of cholesterol, phospholipids and triglycerides in albino rat liver].

PubMed

Kovtuniak, N A; Bordiakovskaia, L G; Stadniĭchuk, R F

1983-01-01

It has been shown in experiments that intramuscular injection of guaternary ammonium compounds (decamethoxine and decamine) and levorin changed the content of cholesterol, phospholipids and triglycerides in the liver of white rats. Decamethoxine decreased the content of phospholipids and cholesterol and raised the concentration of triglycerides. Decamine decreased the level of phospholipids and raised the content of cholesterol and triglycerides, while levorin minimized the content of phospholipids, cholesterol and triglycerides.

Microbial diversity in ultra-high-pressure rocks and fluids from the Chinese Continental Scientific Drilling Project in China.

PubMed

Zhang, Gengxin; Dong, Hailiang; Xu, Zhiqin; Zhao, Donggao; Zhang, Chuanlun

2005-06-01

Microbial communities in ultra-high-pressure (UHP) rocks and drilling fluids from the Chinese Continental Scientific Drilling Project were characterized. The rocks had a porosity of 1 to 3.5% and a permeability of approximately 0.5 mDarcy. Abundant fluid and gas inclusions were present in the minerals. The rocks contained significant amounts of Fe2O3, FeO, P2O5, and nitrate (3 to 16 ppm). Acridine orange direct counting and phospholipid fatty acid analysis indicated that the total counts in the rocks and the fluids were 5.2 x 10(3) to 2.4 x 10(4) cells/g and 3.5 x 10(8) to 4.2 x 10(9) cells/g, respectively. Enrichment assays resulted in successful growth of thermophilic and alkaliphilic bacteria from the fluids, and some of these bacteria reduced Fe(III) to magnetite. 16S rRNA gene analyses indicated that the rocks were dominated by sequences similar to sequences of Proteobacteria and that most organisms were related to nitrate reducers from a saline, alkaline, cold habitat; however, some phylotypes were either members of a novel lineage or closely related to uncultured clones. The bacterial communities in the fluids were more diverse and included Proteobacteria, Bacteroidetes, gram-positive bacteria, Planctomycetes, and Candidatus taxa. The archaeal diversity was lower, and most sequences were not related to any known cultivated species. Some archaeal sequences were 90 to 95% similar to sequences recovered from ocean sediments or other subsurface environments. Some archaeal sequences from the drilling fluids were >93% similar to sequences of Sulfolobus solfataricus, and the thermophilic nature was consistent with the in situ temperature. We inferred that the microbes in the UHP rocks reside in fluid and gas inclusions, whereas those in the drilling fluids may be derived from subsurface fluids.

Microbial Diversity in Ultra-High-Pressure Rocks and Fluids from the Chinese Continental Scientific Drilling Project in China

PubMed Central

Zhang, Gengxin; Dong, Hailiang; Xu, Zhiqin; Zhao, Donggao; Zhang, Chuanlun

2005-01-01

Microbial communities in ultra-high-pressure (UHP) rocks and drilling fluids from the Chinese Continental Scientific Drilling Project were characterized. The rocks had a porosity of 1 to 3.5% and a permeability of ∼0.5 mDarcy. Abundant fluid and gas inclusions were present in the minerals. The rocks contained significant amounts of Fe2O3, FeO, P2O5, and nitrate (3 to 16 ppm). Acridine orange direct counting and phospholipid fatty acid analysis indicated that the total counts in the rocks and the fluids were 5.2 × 103 to 2.4 × 104 cells/g and 3.5 × 108 to 4.2 × 109 cells/g, respectively. Enrichment assays resulted in successful growth of thermophilic and alkaliphilic bacteria from the fluids, and some of these bacteria reduced Fe(III) to magnetite. 16S rRNA gene analyses indicated that the rocks were dominated by sequences similar to sequences of Proteobacteria and that most organisms were related to nitrate reducers from a saline, alkaline, cold habitat; however, some phylotypes were either members of a novel lineage or closely related to uncultured clones. The bacterial communities in the fluids were more diverse and included Proteobacteria, Bacteroidetes, gram-positive bacteria, Planctomycetes, and Candidatus taxa. The archaeal diversity was lower, and most sequences were not related to any known cultivated species. Some archaeal sequences were 90 to 95% similar to sequences recovered from ocean sediments or other subsurface environments. Some archaeal sequences from the drilling fluids were >93% similar to sequences of Sulfolobus solfataricus, and the thermophilic nature was consistent with the in situ temperature. We inferred that the microbes in the UHP rocks reside in fluid and gas inclusions, whereas those in the drilling fluids may be derived from subsurface fluids. PMID:15933024

Immunopotentiating reconstituted influenza virus virosome vaccine delivery system for immunization against hepatitis A.

PubMed Central

Glück, R; Mischler, R; Brantschen, S; Just, M; Althaus, B; Cryz, S J

1992-01-01

Hepatitis A virus (HAV) was purified from MRC-5 human diploid cell cultures, inactivated with formalin, and evaluated for safety and immunogenicity in humans. Three vaccine formulations were produced: (a) a fluid preparation containing inactivated HAV, (b) inactivated HAV adsorbed to Al(OH)3, and (c) inactivated HAV coupled to novel immunopotentiating reconstituted influenza virosomes (IRIV). IRIV were prepared by combining phosphatidylcholine, phosphatidylethanolamine, phospholipids originating from the influenza virus envelope, influenza virus hemagglutinin, and neuraminidase. The HAV-IRIV appeared as unilamellar vesicles with a diameter of approximately 150 nm when viewed by transmission electron microscopy. Upon intramuscular injection, the alum-adsorbed vaccine was associated with significantly (P < 0.01) more local adverse reactions than either the fluid or IRIV formulations. 14 d after a single dose of vaccine, all the recipients of the IRIV formulation seroconverted (> or = 20 mIU/ml) versus 30 and 44% for those who received the fluid and alum-adsorbed vaccines, respectively (P < 0.001). The geometric mean anti-HAV antibody titer achieved after immunization with the IRIV-HAV vaccine was also significantly higher (P < 0.005) compared with the other two vaccines. Images PMID:1334977

Activation of Macrophages in vitro by Phospholipids from Brain of Katsuwonus pelamis (Skipjack Tuna).

PubMed

Lu, Hang; Zhang, Li; Zhao, Hui; Li, Jingjing; You, Hailin; Jiang, Lu; Hu, Jianen

2018-03-01

The biological activities of phospholipids (PLs) have attracted people's attention, especially marine phospholipids with omega-3 polyunsaturated fatty acids DHA and EPA. In this study, we investigated the immunity activation of macrophages in vitro by phospholipids from skipjack brain. The phospholipids were extracted with hexane and ethanol ultrasonication instead of the traditional method of methanol and chloroform. The content of phospholipids from Skipjack brain was 19.59 g/kg by the method (the ratio of hexane and ethanol 2:1, 40 min, 35°C, 1:9 of the ratio of material to solvent, ultrasonic power 300W, ultrasonic extraction 2 times). The RAW264.7 macrophages were stimulated by the phospholipids from the Skipjack, by which the volume, viability and phagocytosis of macrophages were increased. The concentration of NO and the activity of SOD of the cells were also enhanced. The gene expressions of IL-1β, IL-6, iNOS and TNF-α mRNA assayed by RT-PCR were up-regulated. Phospholipids from brain of Skipjack Tuna could activate macrophages immunity which displayed to induce pro-inflammatroy cytokines mRNA expression.

Chlamydia trachomatis Relies on Autonomous Phospholipid Synthesis for Membrane Biogenesis*♦

PubMed Central

Yao, Jiangwei; Cherian, Philip T.; Frank, Matthew W.; Rock, Charles O.

2015-01-01

The obligate intracellular parasite Chlamydia trachomatis has a reduced genome and is thought to rely on its mammalian host cell for nutrients. Although several lines of evidence suggest C. trachomatis utilizes host phospholipids, the bacterium encodes all the genes necessary for fatty acid and phospholipid synthesis found in free living Gram-negative bacteria. Bacterially derived phospholipids significantly increased in infected HeLa cell cultures. These new phospholipids had a distinct molecular species composition consisting of saturated and branched-chain fatty acids. Biochemical analysis established the role of C. trachomatis-encoded acyltransferases in producing the new disaturated molecular species. There was no evidence for the remodeling of host phospholipids and no change in the size or molecular species composition of the phosphatidylcholine pool in infected HeLa cells. Host sphingomyelin was associated with C. trachomatis isolated by detergent extraction, but it may represent contamination with detergent-insoluble host lipids rather than being an integral bacterial membrane component. C. trachomatis assembles its membrane systems from the unique phospholipid molecular species produced by its own fatty acid and phospholipid biosynthetic machinery utilizing glucose, isoleucine, and serine. PMID:25995447

Comprehensive analysis of phospholipids in the brain, heart, kidney, and liver: brain phospholipids are least enriched with polyunsaturated fatty acids.

PubMed

Choi, Jaewoo; Yin, Tai; Shinozaki, Koichiro; Lampe, Joshua W; Stevens, Jan F; Becker, Lance B; Kim, Junhwan

2018-05-01

It is commonly accepted that brain phospholipids are highly enriched with long-chain polyunsaturated fatty acids (PUFAs). However, the evidence for this remains unclear. We used HPLC-MS to analyze the content and composition of phospholipids in rat brain and compared it to the heart, kidney, and liver. Phospholipids typically contain one PUFA, such as 18:2, 20:4, or 22:6, and one saturated fatty acid, such as 16:0 or 18:0. However, we found that brain phospholipids containing monounsaturated fatty acids in the place of PUFAs are highly elevated compared to phospholipids in the heart, kidney, and liver. The relative content of phospholipid containing PUFAs is ~ 60% in the brain, whereas it is over 90% in other tissues. The most abundant species of phosphatidylcholine (PC) is PC(16:0/18:1) in the brain, whereas PC(18:0/20:4) and PC(16:0/20:4) are predominated in other tissues. Moreover, several major species of plasmanyl and plasmenyl phosphatidylethanolamine are found to contain monounsaturated fatty acid in the brain only. Overall, our data clearly show that brain phospholipids are the least enriched with PUFAs of the four major organs, challenging the common belief that the brain is highly enriched with PUFAs.

Transverse optic-like modes in binary liquids

NASA Astrophysics Data System (ADS)

Bryk, Taras; Mryglod, Ihor

1999-10-01

Generalized collective mode approach and MD simulations are applied for the study of transverse dynamics in a LJ fluid KrAr and a liquid alloy Mg 70Zn 30. The optic-like excitations, caused by the mass-concentration fluctuations, are found in both mixtures considered. Mode contributions into the total spectral function are investigated.

Intracellular Fixation Buffer Inactivates Newcastle Disease Virus in Chicken Allantoic Fluid, Macrophages and Splenocytes for Immune Assessment During Infection

USDA-ARS?s Scientific Manuscript database

Inactivation of Newcastle disease virus (NDV) has been routinely achieved with heat, ß-propiolactone, binary ethylenimine, ultraviolet light and formalin, however these strategies have not been validated for cell surface ligand or receptor phenotype in viral-infected chicken immune cells. To study ...

Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

DOE PAGES

Petsev, Nikolai Dimitrov; Leal, L. Gary; Shell, M. Scott

2017-12-21

Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely-resolved (e.g. molecular dynamics) and coarse-grained (e.g. continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 84115 (2016)], simulatedmore » using a particle-based continuum method known as smoothed dissipative particle dynamics (SDPD). An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.« less

Exergoeconomic analysis and optimization of an evaporator for a binary mixture of fluids in an organic Rankine cycle

NASA Astrophysics Data System (ADS)

Li, You-Rong; Du, Mei-Tang; Wang, Jian-Ning

2012-12-01

This paper focuses on the research of an evaporator with a binary mixture of organic working fluids in the organic Rankine cycle. Exergoeconomic analysis and performance optimization were performed based on the first and second laws of thermodynamics, and the exergoeconomic theory. The annual total cost per unit heat transfer rate was introduced as the objective function. In this model, the exergy loss cost caused by the heat transfer irreversibility and the capital cost were taken into account; however, the exergy loss due to the frictional pressure drops, heat dissipation to surroundings, and the flow imbalance were neglected. The variation laws of the annual total cost with respect to the number of transfer units and the temperature ratios were presented. Optimal design parameters that minimize the objective function had been obtained, and the effects of some important dimensionless parameters on the optimal performances had also been discussed for three types of evaporator flow arrangements. In addition, optimal design parameters of evaporators were compared with those of condensers.

Coupling discrete and continuum concentration particle models for multiscale and hybrid molecular-continuum simulations

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

Petsev, Nikolai Dimitrov; Leal, L. Gary; Shell, M. Scott

Hybrid molecular-continuum simulation techniques afford a number of advantages for problems in the rapidly burgeoning area of nanoscale engineering and technology, though they are typically quite complex to implement and limited to single-component fluid systems. We describe an approach for modeling multicomponent hydrodynamic problems spanning multiple length scales when using particle-based descriptions for both the finely-resolved (e.g. molecular dynamics) and coarse-grained (e.g. continuum) subregions within an overall simulation domain. This technique is based on the multiscale methodology previously developed for mesoscale binary fluids [N. D. Petsev, L. G. Leal, and M. S. Shell, J. Chem. Phys. 144, 84115 (2016)], simulatedmore » using a particle-based continuum method known as smoothed dissipative particle dynamics (SDPD). An important application of this approach is the ability to perform coupled molecular dynamics (MD) and continuum modeling of molecularly miscible binary mixtures. In order to validate this technique, we investigate multicomponent hybrid MD-continuum simulations at equilibrium, as well as non-equilibrium cases featuring concentration gradients.« less

Population annealing simulations of a binary hard-sphere mixture

NASA Astrophysics Data System (ADS)

Callaham, Jared; Machta, Jonathan

2017-06-01

Population annealing is a sequential Monte Carlo scheme well suited to simulating equilibrium states of systems with rough free energy landscapes. Here we use population annealing to study a binary mixture of hard spheres. Population annealing is a parallel version of simulated annealing with an extra resampling step that ensures that a population of replicas of the system represents the equilibrium ensemble at every packing fraction in an annealing schedule. The algorithm and its equilibration properties are described, and results are presented for a glass-forming fluid composed of a 50/50 mixture of hard spheres with diameter ratio of 1.4:1. For this system, we obtain precise results for the equation of state in the glassy regime up to packing fractions φ ≈0.60 and study deviations from the Boublik-Mansoori-Carnahan-Starling-Leland equation of state. For higher packing fractions, the algorithm falls out of equilibrium and a free volume fit predicts jamming at packing fraction φ ≈0.667 . We conclude that population annealing is an effective tool for studying equilibrium glassy fluids and the jamming transition.

A computational fluid dynamics approach to nucleation in the water-sulfuric acid system.

PubMed

Herrmann, E; Brus, D; Hyvärinen, A-P; Stratmann, F; Wilck, M; Lihavainen, H; Kulmala, M

2010-08-12

This study presents a computational fluid dynamics modeling approach to investigate the nucleation in the water-sulfuric acid system in a flow tube. On the basis of an existing experimental setup (Brus, D.; Hyvärinen, A.-P.; Viisanen, Y.; Kulmala, M.; Lihavainen, H. Atmos. Chem. Phys. 2010, 10, 2631-2641), we first establish the effect of convection on the flow profile. We then proceed to simulate nucleation for relative humidities of 10, 30, and 50% and for sulfuric acid concentration between 10(9) to 3 x 10(10) cm(-3). We describe the nucleation zone in detail and determine how flow rate and relative humidity affect its characteristics. Experimental nucleation rates are compared to rates gained from classical binary and kinetic nucleation theory as well as cluster activation theory. For low RH values, kinetic theory yields the best agreement with experimental results while binary nucleation best reproduces the experimental nucleation behavior at 50% relative humidity. Particle growth is modeled for an example case at 50% relative humidity. The final simulated diameter is very close to the experimental result.

Effects of analogues of ethanolamine and choline on phospholipid metabolism in rat hepatocytes

PubMed Central

Åkesson, Björn

1977-01-01

1. Analogues of ethanolamine and choline were incubated with different labelled precursors of phospholipids and isolated hepatocytes and the effects on phospholipid synthesis were studied. 2. 2-Aminopropan-1-ol and 2-aminobutan-1-ol were the most efficient inhibitors of [14C]ethanolamine incorporation into phospholipids, whereas the incorporation of [3H]choline was inhibited most extensively by NN-diethylethanolamine and NN-dimethylethanolamine. 3. When the analogues were incubated with [3H]glycerol and hepatocytes, the appearance of 3H in unnatural phospholipids indicated that they were incorporated, at least in part, via CDP-derivatives. The distribution of [3H]glycerol among molecular species of phospholipids containing 2-aminopropan-1-ol and 1-aminopropan-2-ol was the same as in phosphatidylethanolamine. In other phospholipid analogues the distribution of 3H was more similar to that in phosphatidylcholine. 4. NN-Diethylethanolamine stimulated both the conversion of phosphatidylethanolamine into phosphatidylcholine and the incorporation of [Me-14C]methionine into phospholipids. Other N-alkyl- or NN-dialkyl-ethanolamines also stimulated [14C]methionine incorporation, but inhibited the conversion of phosphatidylethanolamine into phosphatidylcholine. This indicates that phosphatidyl-NN-diethylethanolamine is a poor methyl acceptor, in contrast with other N-alkylated phosphatidylethanolamines. 5. These results on the regulation of phospholipid metabolism in intact cells are discussed with respect to the possible control points. They also provide guidelines for future experiments on the manipulation of phospholipid polar-headgroup composition in primary cultures of hepatocytes. PMID:606244

Effects of analogles of ethanolamine and choline on phospholipid metabolism in rat hepatocytes.

PubMed

Akesson, B

1977-12-15

1. Analogues of ethanolamine and choline were incubated with different labelled precursors of phospholipids and isolated hepatocytes and the effects on phospholipid synthesis were studied. 2. 2-Aminopropan-1-ol and 2-aminobutan-1-ol were the most efficient inhibitors of [(14)C]ethanolamine incorporation into phospholipids, whereas the incorporation of [(3)H]choline was inhibited most extensively by NN-diethylethanolamine and NN-dimethylethanolamine. 3. When the analogues were incubated with [(3)H]glycerol and hepatocytes, the appearance of (3)H in unnatural phospholipids indicated that they were incorporated, at least in part, via CDP-derivatives. The distribution of [(3)H]glycerol among molecular species of phospholipids containing 2-aminopropan-1-ol and 1-aminopropan-2-ol was the same as in phosphatidylethanolamine. In other phospholipid analogues the distribution of (3)H was more similar to that in phosphatidylcholine. 4. NN-Diethylethanolamine stimulated both the conversion of phosphatidylethanolamine into phosphatidylcholine and the incorporation of [Me-(14)C]methionine into phospholipids. Other N-alkyl- or NN-dialkyl-ethanolamines also stimulated [(14)C]methionine incorporation, but inhibited the conversion of phosphatidylethanolamine into phosphatidylcholine. This indicates that phosphatidyl-NN-diethylethanolamine is a poor methyl acceptor, in contrast with other N-alkylated phosphatidylethanolamines. 5. These results on the regulation of phospholipid metabolism in intact cells are discussed with respect to the possible control points. They also provide guidelines for future experiments on the manipulation of phospholipid polar-headgroup composition in primary cultures of hepatocytes.

A retrospective: Use of Escherichia coli as a vehicle to study phospholipid synthesis and function

PubMed Central

Dowhan, William

2012-01-01

Although the study of individual phospholipids and their synthesis began in the 1920’s first in plants and then mammals, it was not until the early 1960’s that Eugene Kennedy using Escherichia coli initiated studies of bacterial phospholipid metabolism. With the base of information already available from studies of mammalian tissue, the basic blueprint of phospholipid biosynthesis in E. coli was worked out by the late 1960’s. In 1970’s and 1980’s most of the enzymes responsible for phospholipid biosynthesis were purified and many of the genes encoding these enzymes were identified. By the late 1990’s conditional and null mutants were available along with clones of the genes for every step of phospholipid biosynthesis. Most of these genes had been sequenced before the complete E. coli genome sequence was available. Strains of E. coli were developed in which phospholipid composition could be changed in a systematic manner while maintaining cell viability. Null mutants, strains in which phospholipid metabolism was artificially regulated, and strains synthesizing foreign lipids not found in E. coli have been used to this day to define specific roles for individual phospholipid. This review will trace the findings that have led to the development of E. coli as an excellent model system to study mechanisms underlying the synthesis and function of phospholipids that are widely applicable to other prokaryotic and eukaryotic systems. PMID:22925633

Lipomobilization in periparturient dairy cows influences the composition of plasma nonesterified fatty acids and leukocyte phospholipid fatty acids.

PubMed

Contreras, G A; O'Boyle, N J; Herdt, T H; Sordillo, L M

2010-06-01

The periparturient period is characterized by sudden changes in metabolic and immune cell functions that predispose dairy cows to increased incidence of disease. Metabolic changes include alterations in the energy balance that lead to increased lipomobilization with consequent elevation of plasma nonesterified fatty acids (NEFA) concentrations. The objective of this study was to establish the influence of lipomobilization on fatty acid profiles within plasma lipid fractions and leukocyte phospholipid composition. Blood samples from 10 dairy cows were collected at 14 and 7 d before due date, at calving, and at 7, 14, and 30 d after calving. Total lipids and lipid fractions were extracted from plasma and peripheral blood mononuclear cells. The degree of lipomobilization was characterized by measurement of plasma NEFA concentrations. The fatty acid profile of plasma NEFA, plasma phospholipids, and leukocyte phospholipids differed from the composition of total lipids in plasma, where linoleic acid was the most common fatty acid. Around parturition and during early lactation, the proportion of palmitic acid significantly increased in the plasma NEFA and phospholipid fractions with a concomitant increase in the phospholipid fatty acid profile of leukocytes. In contrast, the phospholipid fraction of long-chain polyunsaturated fatty acids in leukocytes was diminished during the periparturient period, especially during the first 2 wk following parturition. This study showed that the composition of total plasma lipids does not necessarily reflect the NEFA and phospholipid fractions in periparturient dairy cows. These findings are significant because it is the plasma phospholipid fraction that contributes to fatty acid composition of membrane phospholipids. Increased availability of certain saturated fatty acids in the NEFA phospholipid fractions may contribute to altered leukocyte functions during the periparturient period. 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Chemistry of phospholipid oxidation.

PubMed

Reis, Ana; Spickett, Corinne M

2012-10-01

The oxidation of lipids has long been a topic of interest in biological and food sciences, and the fundamental principles of non-enzymatic free radical attack on phospholipids are well established, although questions about detail of the mechanisms remain. The number of end products that are formed following the initiation of phospholipid peroxidation is large, and is continually growing as new structures of oxidized phospholipids are elucidated. Common products are phospholipids with esterified isoprostane-like structures and chain-shortened products containing hydroxy, carbonyl or carboxylic acid groups; the carbonyl-containing compounds are reactive and readily form adducts with proteins and other biomolecules. Phospholipids can also be attacked by reactive nitrogen and chlorine species, further expanding the range of products to nitrated and chlorinated phospholipids. Key to understanding the mechanisms of oxidation is the development of advanced and sensitive technologies that enable structural elucidation. Tandem mass spectrometry has proved invaluable in this respect and is generally the method of choice for structural work. A number of studies have investigated whether individual oxidized phospholipid products occur in vivo, and mass spectrometry techniques have been instrumental in detecting a variety of oxidation products in biological samples such as atherosclerotic plaque material, brain tissue, intestinal tissue and plasma, although relatively few have achieved an absolute quantitative analysis. The levels of oxidized phospholipids in vivo is a critical question, as there is now substantial evidence that many of these compounds are bioactive and could contribute to pathology. The challenges for the future will be to adopt lipidomic approaches to map the profile of oxidized phospholipid formation in different biological conditions, and relate this to their effects in vivo. This article is part of a Special Issue entitled: Oxidized phospholipids-their properties and interactions with proteins. Copyright © 2012 Elsevier B.V. All rights reserved.

Changes during hibernation in different phospholipid and free and esterified cholesterol serum levels in black bears

USGS Publications Warehouse

Chauhan, V.; Sheikh, A.; Chauhan, A.; Tsiouris, J.; Malik, M.; Vaughan, M.

2002-01-01

During hibernation, fat is known to be the preferred source of energy. A detailed analysis of different phospholipids, as well as free and esterified cholesterol, was conducted to investigate lipid abnormalities during hibernation. The levels of total phospholipids and total cholesterol in the serum of black bears were found to increase significantly in hibernation as compared with the active state. Both free and esterified cholesterol were increased in the hibernating state in comparison with the active state (P < 0.05). The percentage increase during hibernation was more in free cholesterol (57%) than in esterified cholesterol (27%). Analysis of subclasses of serum phospholipids showed that choline containing phospholipids, i.e., sphingomyelin (SPG) (14%) and phosphatidylcholine (PC) (76%), are the major phospholipids in the serum of bear. The minor phospholipids included 8% of phosphatidylserine (PS) + phosphatidylinositol (PI), while phosphatidylethanolamine (PE) was only 2% of the total phospholipids. A comparison of phospholipid subclasses showed that PC, PS + PI and SPG were significantly increased, while PE was significantly decreased (P < 0.05) in the hibernating state as compared with the active state in black bears. These results suggest that the catabolism of phospholipids and cholesterol is decreased during hibernation in black bears, leading to their increased levels in the hibernating state as compared with the active state. In summary, our results indicate that serum cholesterol and phospholipid fractions (except PE) are increased during hibernation in bears. It is proposed that the increase of these lipids may be due to the altered metabolism of lipoproteins that are responsible for the clearance of the lipids. ?? 2002 E??ditions scientifiques et me??dicales Elsevier SAS and Socie??te?? franc??aise de biochimie et biologie mole??culaire. All rights reserved.

A novel mixed phospholipid functionalized monolithic column for early screening of drug induced phospholipidosis risk.

PubMed

Zhao, XiangLong; Chen, WeiJia; Liu, ZhengHua; Guo, JiaLiang; Zhou, ZhengYin; Crommen, Jacques; Moaddel, Ruin; Jiang, ZhengJin

2014-11-07

Drug-induced phospholipidosis (PLD) is characterized by the excessive accumulation of phospholipids, resulting in multilamellar vesicle structure within lysosomes. In the present study, a novel mixed phospholipid functionalized monolithic column was developed for the first time through a facile one-step co-polymerization approach. The phospholipid composition of the monolith can be adjusted quantitatively and accurately to mimic the mixed phospholipid environment of different biomembranes on a solid matrix. The mixed phospholipid functionalized monolith as a promising immobilized artificial membrane technique was used to study drug-phospholipid interaction. Scanning electron microscopy, elemental analysis, FT-IR spectra, ζ-potential analysis and micro-HPLC were carried out to characterize the physicochemical properties and separation performance of the monolith. Mechanism studies revealed that both hydrophobic and electrostatic interactions play an important role in the retention of analytes. The ratio of their contributions to retention can be easily manipulated by adjusting the composition of the mixed phospholipids, in order to better mimic the interaction between drugs and cell membrane. The obtained mixed phospholipid functionalized monolithic columns were applied to the screening of drug-induced PLD potency. Data from 79 drugs on the market demonstrated that the chromatographic hydrophobicity index referring to the mixed phospholipid functionalized monolith at pH 7.4 (CHI IAM7.4) for the selected drugs were highly correlated with the drug-induced PLD potency data obtained from other in vivo or in vitro assays. Moreover, the effect of the acidic phospholipid phosphatidylserine proportion on prediction accuracy was also investigated. The monolith containing 20% phosphatidylserine and 80% phosphatidylcholine exhibited the best prediction ability for the drug-induced PLD potency of the tested compounds. This research has led to the successful development of a novel and facile approach to prepare a mixed phospholipids functionalized monolith, which offers a reliable, cost-effective and high-throughput screening tool for early prediction of the PLD potency of drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

Phospholipid composition of Dipylidium caninum.

PubMed

Chopra, A K; Jain, S K; Vinayak, V K; Khuller, G K

1978-11-15

The phospholipid composition of Dipylidium caninum has been studied. Chloroform-methanol-soluble fraction amounted to 2.4% and phospholipids to 0.5% of the wet weight of the parasite. Phosphatidyl choline and phosphatidyl ethanolamine represented the bulk of the phospholipids, whereas phosphatidyl serine, phosphatidyl inositol, lysolecithin and lysophosphatidyl ethanolamine were present in minor amounts. Sulfatides were also identified in this parasite.

Monitoring Phosphatidic Acid Signaling in Breast Cancer Cells Using Genetically Encoded Biosensors.

PubMed

Lu, Maryia; Tay, Li Wei Rachel; He, Jingquan; Du, Guangwei

2016-01-01

Phospholipids are important signaling molecules that regulate cell proliferation, death, migration, and metabolism. Many phospholipid signaling cascades are altered in breast cancer. To understand the functions of phospholipid signaling molecules, genetically encoded phospholipid biosensors have been developed to monitor their spatiotemporal dynamics. Compared to other phospholipids, much less is known about the subcellular production and cellular functions of phosphatidic acid (PA), partially due to the lack of a specific and sensitive PA biosensor in the past. This chapter describes the use of a newly developed PA biosensor, PASS, in two applications: regular fluorescent microscopy and fluorescence lifetime imaging microscopy-Förster/fluorescence resonance energy transfer (FLIM-FRET). These protocols can be also used with other phospholipid biosensors.

Microencapsulation and characterization of liposomal vesicles using a supercritical fluid process coupled with vacuum-driven cargo loading.

PubMed

Tsai, Wen-Chyan; Rizvi, Syed S H

2017-06-01

A new technique of liposomal microencapsulation, consisting of supercritical fluid extraction followed by rapid expansion of the supercritical solution and vacuum-driven cargo loading, was successfully developed. It is a continuous flow-through process without usage of any toxic organic solvent. For use as a coating material, the solubility of soy phospholipids in supercritical carbon dioxide was first determined using a dynamic equilibrium system and the data was correlated with the Chrastil model with good agreement. Liposomes were made with D-(+)-glucose as a cargo and their properties were characterized as functions of expansion pressure, temperature, and cargo loading rates. The highest encapsulation efficiency attained was 31.7% at the middle expansion pressure of 12.41MPa, highest expansion temperature of 90°C, and lowest cargo loading rate of 0.25mL/s. The large unilamellar vesicles and multivesicular vesicles were observed to be a majority of the liposomes produced using this eco-friendly process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shear thinning and shear thickening of a confined suspension of vesicles

NASA Astrophysics Data System (ADS)

Nait Ouhra, A.; Farutin, A.; Aouane, O.; Ez-Zahraouy, H.; Benyoussef, A.; Misbah, C.

2018-01-01

Widely regarded as an interesting model system for studying flow properties of blood, vesicles are closed membranes of phospholipids that mimic the cytoplasmic membranes of red blood cells. In this study we analyze the rheology of a suspension of vesicles in a confined geometry: the suspension, bound by two planar rigid walls on each side, is subject to a shear flow. Flow properties are then analyzed as a function of shear rate γ ˙, the concentration of the suspension ϕ , and the viscosity contrast λ =ηin/ηout , where ηin and ηout are the fluid viscosities of the inner and outer fluids, respectively. We find that the apparent (or effective viscosity) of the suspension exhibits both shear thinning (decreasing viscosity with shear rate) or shear thickening (increasing viscosity with shear rate) in the same concentration range. The shear thinning or thickening behaviors appear as subtle phenomena, dependant on viscosity contrast λ . We provide physical arguments on the origins of these behaviors.

Low-gravity fluid dynamics and transport phenomena. Progress in Astronautics and Aeronautics. Vol. 130

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

Koster, J.N.; Sani, R.L.

1990-01-01

Various papers on low-gravity fluid dynamics and transport phenomena are presented. Individual topics addressed include: fluid management in low gravity, nucleate pool boiling in variable gravity, application of energy-stability theory to problems in crystal growth, thermosolutal convection in liquid HgCdTe near the liquidus temperature, capillary surfaces in microgravity, thermohydrodynamic instabilities and capillary flows, interfacial oscillators, effects of gravity jitter on typical fluid science experiments and on natural convection in a vertical cylinder. Also discussed are: double-diffusive convection and its effects under reduced gravity, segregation and convection in dendritic alloys, fluid flow and microstructure development, analysis of convective situations with themore » Soret effect, complex natural convection in low Prandtl number metals, separation physics, phase partitioning in reduced gravity, separation of binary alloys with miscibility gap in the melt, Ostwald ripening in liquids, particle cloud combustion in reduced gravity, opposed-flow flame spread with implications for combustion at microgravity.« less

A symbiotic approach to fluid equations and non-linear flux-driven simulations of plasma dynamics

NASA Astrophysics Data System (ADS)

Halpern, Federico

2017-10-01

The fluid framework is ubiquitous in studies of plasma transport and stability. Typical forms of the fluid equations are motivated by analytical work dating several decades ago, before computer simulations were indispensable, and can be, therefore, not optimal for numerical computation. We demonstrate a new first-principles approach to obtaining manifestly consistent, skew-symmetric fluid models, ensuring internal consistency and conservation properties even in discrete form. Mass, kinetic, and internal energy become quadratic (and always positive) invariants of the system. The model lends itself to a robust, straightforward discretization scheme with inherent non-linear stability. A simpler, drift-ordered form of the equations is obtained, and first results of their numerical implementation as a binary framework for bulk-fluid global plasma simulations are demonstrated. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, Theory Program, under Award No. DE-FG02-95ER54309.

LRH-1 regulates hepatic lipid homeostasis and maintains arachidonoyl phospholipid pools critical for phospholipid diversity

PubMed Central

Miranda, Diego A.; Krause, William C.; Suzawa, Miyuki; Escusa, Hazel; Foo, Juat Chin; Shihadih, Diyala S.; Stahl, Andreas; Nyangau, Edna; Hellerstein, Marc; Wenk, Markus R.; Silver, David L.; Ingraham, Holly A.

2018-01-01

Excess lipid accumulation is an early signature of nonalcoholic fatty liver disease (NAFLD). Although liver receptor homolog 1 (LRH-1) (encoded by NR5A2) is suppressed in human NAFLD, evidence linking this phospholipid-bound nuclear receptor to hepatic lipid metabolism is lacking. Here, we report an essential role for LRH-1 in hepatic lipid storage and phospholipid composition based on an acute hepatic KO of LRH-1 in adult mice (LRH-1AAV8-Cre mice). Indeed, LRH-1–deficient hepatocytes exhibited large cytosolic lipid droplets and increased triglycerides (TGs). LRH-1–deficient mice fed high-fat diet displayed macrovesicular steatosis, liver injury, and glucose intolerance, all of which were reversed or improved by expressing wild-type human LRH-1. While hepatic lipid synthesis decreased and lipid export remained unchanged in mutants, elevated circulating free fatty acid helped explain the lipid imbalance in LRH-1AAV8-Cre mice. Lipidomic and genomic analyses revealed that loss of LRH-1 disrupts hepatic phospholipid composition, leading to lowered arachidonoyl (AA) phospholipids due to repression of Elovl5 and Fads2, two critical genes in AA biosynthesis. Our findings reveal a role for the phospholipid sensor LRH-1 in maintaining adequate pools of hepatic AA phospholipids, further supporting the idea that phospholipid diversity is an important contributor to healthy hepatic lipid storage. PMID:29515023

The anxiolytic activity of n-3 PUFAs enriched egg yolk phospholipids in rat behavioral studies.

PubMed

Rutkowska, M; Słupski, W; Trocha, M; Szandruk, M; Rymaszewska, J

2016-11-02

Phospholipids play an important role in the biochemical and physiological processes of cells. An association between disturbed phospholipids metabolism in neuronal tissue and anxiety it was shown. The aim of this study was to examine the anxiolytic properties of phospholipids obtained from a new generation of eggs enriched in n-3 PUFA and its effect on locomotor activity in rat behavioral studies N-3 PUFA-enriched egg yolk phospholipids ("super lecithin") were added to the standard feed. Rats were fed by chow without (control group) or with (experimental group) addition of phospholipids. After six weeks of supplementation, the effect of phospholipids on locomotor activity in the open field test and anxiolytic properties in elevated plus maze and Vogel conflict test were examined. In the open field test the total distance traveled in the experimental group was similar to the control group. In the elevated plus maze test a six weeks phospholipids' administration significantly prolonged the time spent on the open arms by rats from experimental group compared to control group. The number of entries into the open arms was also increased but the difference was not statistically significant. The number of punished drinking water in the Vogel conflict test increased significantly in experimental versus control group. The obtained results suggest that the phospholipids isolated from n-3 PUFA enriched egg yolk have a specific anxiolytic effect, without general sedative influence.

Phospholipid composition of oligodendroglial cells during normal development and in 18 day old hyperthyroid and malnourished rats.

PubMed

Kreda, S M; Pasquini, J M; Soto, E F

1992-09-01

The phospholipid composition of isolated oligodendroglial cell perikarya was studied in normal rats during development and in 18 day old malnourished and hyperthyroid rats. Phosphatidyl choline and phosphatidyl ethanolamine were found to be the major phospholipid constituents of oligodendroglial cells. Phospholipid content increased during development, mainly due to an increase of the above mentioned phospholipids. The major changes were observed in sphingomyelin, phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine between 18 and 30 days of age. The phospholipid and protein content per cell was significantly decreased in the oligodendroglial cells isolated from malnourished rats as compared to controls. When data were expressed as a function of total proteins, the composition was similar to that of normal animals. In the hyperthyroid rats on the other hand, there were no changes in the amount of phospholipids per cell, while phospholipids per milligram of total oligodendroglial cell protein were markedly decreased. The changes in myelin composition produced by hyperthyroidism that we have previously described, do not follow closely those produced by this experimental condition in oligodendroglial cells, suggesting that the metabolism of myelin might be to a certain extent, independent of that in the parent cell.

Regulation of phospholipid synthesis in phosphatidylserine synthase-deficient (chol) mutants of Saccharomyces cerevisiae

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

Letts, V.A.; Henry, S.A.

1985-08-01

Saccharomyces cerevisiae mutants, chol, are deficient in the synthesis of the phospholipid phosphatidylserine owing to lowered activity of the membrane-associated enzyme phosphatidylserine synthase. These mutants are auxotrophic for ethanolamine or choline and, in the absence of these supplements, cannot synthesize phosphatidylethanolamine or phosphatidylcholine (PC). The authors exploited these characteristics of the chol mutants to examine the regulation of phospholipid metabolism in S. cerevisiae. Macromolecular synthesis and phospholipid metabolism were examined in chol cells starved for ethanolamine. Coupled to the decline in PC biosynthesis was a simultaneous decrease in the overall rate of phospholipid synthesis. In particular, the rate of synthesismore » of phosphatidylinositol decreased in parallel with the decline in PC biosynthesis. However, under conditions of ethanolamine deprivation in chol cells, the cytoplasmic enzyme inositol-1-phosphate synthase could not be repressed by exogenous inositol, and the endogenous synthesis of the phospholipid precursor inositol appeared to be elevated. The implications of these findings with respect to the coordinated regulation of phospholipid synthesis are discussed.« less

Therapy of myeloma in vivo using marine phospholipid in combination with Agaricus blazei Murill as an immune respond activator.

PubMed

Murakawa, Kentaro; Fukunaga, Kenji; Tanouchi, Masatoshi; Hosokawa, Masashi; Hossain, Zakir; Takahashi, Koretaro

2007-01-01

Mushroom (Agaricus blazei Murill) extract has been reported to possess antitumor effects through immune activation. Here, we investigated the beneficial effects of combining A. blazei extract with marine phospholipids in comparison to A. blazei extract alone on myeloma sp2 tumor suppression when orally administrated. The experimental groups designed for sp2 tumor bearing BALB/c nu/nu mice were drinks of: (1)control; (2)1.0 mg/mL squid phospholipid liposome alone; (3)0.5 mg/mL A. blazei Murill water extract alone; (4)1.0 mg/mL squid phospholipid liposome with 0.5 mg/mL A. blazei Murill water extract in the form of those simple mixture; and (5)1.0 mg/mL squid phospholipid liposome with 0.5 mg/mL A. blazei Murill water extract partially encapsulated. Orally administrated volumes amounted to approximately 5 mL per day per mouse for all groups. A. blazei Murill water extract alone and squid phospholipid alone served groups show moderate tumor suppression with total administrations of approximately 105 mg/mouse for squid phospholipid through out the experimental term. When both A. blazei Murill water extract and squid phospholipid were administrated simultaneously in a simple mixture form, promotional effect on cancer tumor suppression was observed. And when A. blazei Murill water extract was partially encapsulated in the squid phospholipid liposomes with total administrations being 105 mg/mouse for squid phospholipid, effect on cancer tumor suppression was more pronounced. Though there was no statistically significant difference in tumor sizes between the simple mixture form administrated group i.e. group (4) and the partially encapsulated form administrated group i.e. group (5), the tumor vanished mouse was seen in the partially encapsulated form administrated group. Thus it was concluded that combinational administration of the A. blazei Murill water extract and the marine phospholipid may be useful in myeloma sp2 therapy.

Evolution of phospholipid contents during the production of quark cheese from buttermilk.

PubMed

Ferreiro, T; Martínez, S; Gayoso, L; Rodríguez-Otero, J L

2016-06-01

We report the evolution of phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS), and sphingomyelin (SM) contents during the production of quark cheese from buttermilk by successive ultrafiltration concentration, enrichment with cream, concurrent homogenization and pasteurization, fermentative coagulation, and separation of quark from whey by further ultrafiltration. Buttermilk is richer than milk itself in phospholipids that afford desirable functional and technological properties, and is widely used in dairy products. To investigate how phospholipid content is affected by end-product production processes such as ultrafiltration, homogenization, pasteurization or coagulation, we measured the phospholipids at several stages of each of 5 industrial-scale quark cheese production runs. In each run, 10,000L of buttermilk was concentrated to half volume by ultrafiltration, enriched with cream, homogenized, pasteurized, inoculated with lactic acid bacteria, incubated to coagulation, and once more concentrated to half volume by ultrafiltration. Phospholipid contents were determined by HPLC with evaporative light scattering detection in the starting buttermilk, concentrated buttermilk, ultrafiltrate, cream-enriched concentrated buttermilk (both before and after concurrent homogenization and pasteurization), coagulate, and quark, and also in the rinsings obtained when the ultrafiltration equipment was washed following initial concentration. The average phospholipid content of buttermilk was approximately 5 times that of milk, and the phospholipid content of buttermilk fat 26 to 29 times that of milk fat. Although phospholipids did not cross ultrafiltration membranes, significant losses occurred during ultrafiltration (due to retention on the membranes) and during the homogenization and pasteurization process. During coagulation, however, phospholipid content rose, presumably as a consequence of the proliferation of the inoculated lactic acid bacteria. In spite of these changes in total phospholipid content, the relative proportions of the phospholipids studied remain fairly stable throughout quark production (PE>PC>SM>PS>PI) and similar to those found in the milk of the region, except that SM content was lower than in milk. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Critical Synergistic Concentration of Lecithin Phospholipids Improves the Antimicrobial Activity of Eugenol against Escherichia coli

PubMed Central

Zhang, Haoshu; Dudley, Edward G.

2017-01-01

ABSTRACT In this study, the effect of individual lecithin phospholipids on the antimicrobial properties of eugenol against Escherichia coli C600 was investigated. We tested five major phospholipids common in soy or egg lecithin (1,2-dihexadecanoyl-sn-glycero-3-phosphocholine [DPPC], 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine [DSPC], 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine [DPPE], 1,2-dihexadecanoyl-sn-glycero-3-phosphate [sodium salt] [DPPA], and 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine [DPPS]) and one synthetic cationic phospholipid (1,2-dioctadecanoyl-sn-glycero-3-ethylphosphocholine [18:0 EPC]). Among the six phospholipids, DPPC, DSPC, DPPE, DPPA, and the cationic 18:0 EPC showed critical synergistic concentrations that significantly improved the inactivation effect of eugenol against E. coli after 30 min of exposure. At the critical synergistic concentration, an additional ca. 0.4 to 1.9 log reduction (ca. 0.66 to 2.17 log CFU/ml reduction) in the microbial population was observed compared to eugenol-only (control) treatments (ca. 0.25 log reduction). In all cases, increasing the phospholipid amount above the critical synergistic concentration (which was different for each phospholipid) resulted in antimicrobial properties similar to those seen with the eugenol-only (control) treatments. DPPS did not affect the antimicrobial properties of eugenol at the tested concentrations. The critical synergistic concentration of phospholipids was correlated with their critical micelle concentrations (CMC). IMPORTANCE Essential oils (EOs) are naturally occurring antimicrobials, with limited use in food due to their hydrophobicity and strong aroma. Lecithin is used as a natural emulsifier to stabilize EOs in aqueous systems. We previously demonstrated that, within a narrow critical-concentration window, lecithin can synergistically enhance the antimicrobial properties of eugenol. Since lecithin is a mixture of different phospholipids, we aimed to identify which phospholipids are crucial for the observed synergistic effect. This research studied the bioactivity of lecithin phospholipids, contributing to a rational design in using lecithin to effectively control foodborne pathogens in foods. PMID:28842540

On the energy dissipation rate at the inner edge of circumbinary discs

NASA Astrophysics Data System (ADS)

Terquem, Caroline; Papaloizou, John C. B.

2017-01-01

We study, by means of numerical simulations and analysis, the details of the accretion process from a disc on to a binary system. We show that energy is dissipated at the edge of a circumbinary disc and this is associated with the tidal torque that maintains the cavity: angular momentum is transferred from the binary to the disc through the action of compressional shocks and viscous friction. These shocks can be viewed as being produced by fluid elements that drift into the cavity and, before being accreted, are accelerated on to trajectories that send them back to impact the disc. The rate of energy dissipation is approximately equal to the product of potential energy per unit mass at the disc's inner edge and the accretion rate, estimated from the disc parameters just beyond the cavity edge, that would occur without the binary. For very thin discs, the actual accretion rate on to the binary may be significantly less. We calculate the energy emitted by a circumbinary disc taking into account energy dissipation at the inner edge and also irradiation arising there from reprocessing of light from the stars. We find that, for tight PMS binaries, the SED is dominated by emission from the inner edge at wavelengths between 1-4 and 10 μm. This may apply to systems like CoRoT 223992193 and V1481 Ori.

AqSo_NaCl: Computer program to calculate p-T-V-x properties in the H2O-NaCl fluid system applied to fluid inclusion research and pore fluid calculation

NASA Astrophysics Data System (ADS)

Bakker, Ronald J.

2018-06-01

The program AqSo_NaCl has been developed to calculate pressure - molar volume - temperature - composition (p-V-T-x) properties, enthalpy, and heat capacity of the binary H2O-NaCl system. The algorithms are designed in BASIC within the Xojo programming environment, and can be operated as stand-alone project with Macintosh-, Windows-, and Unix-based operating systems. A series of ten self-instructive interfaces (modules) are developed to calculate fluid inclusion properties and pore fluid properties. The modules may be used to calculate properties of pure NaCl, the halite-liquidus, the halite-vapourus, dew-point and bubble-point curves (liquid-vapour), critical point, and SLV solid-liquid-vapour curves at temperatures above 0.1 °C (with halite) and below 0.1 °C (with ice or hydrohalite). Isochores of homogeneous fluids and unmixed fluids in a closed system can be calculated and exported to a.txt file. Isochores calculated for fluid inclusions can be corrected according to the volumetric properties of quartz. Microthermometric data, i.e. dissolution temperatures and homogenization temperatures, can be used to calculated bulk fluid properties of fluid inclusions. Alternatively, in the absence of total homogenization temperature the volume fraction of the liquid phase in fluid inclusions can be used to obtain bulk properties.

Some physical aspects of fluid-fluxed melting

NASA Astrophysics Data System (ADS)

Patiño Douce, A.

2012-04-01

Fluid-fluxed melting is thought to play a crucial role in the origin of many terrestrial magmas. We can visualize the fundamental physics of the process as follows. An infinitesimal amount of fluid infiltrates dry rock at the temperature of its dry solidus. In order to restore equilibrium the temperature must drop, so that enthalpy is released and immediately reabsorbed as enthalpy of melting. The amount of melt produced must be such that the energy balance and thermodynamic equilibrium conditions are simultaneously satisfied. We wish to understand how an initially dry rock melts in response to progressive fluid infiltration, under both batch and fractional melting constraints. The simplest physical model for this process is a binary system in which one of the components makes up a pure solid phase and the other component a pure fluid phase, and in which a binary melt phase exists over certain temperature range. Melting point depression is calculated under the assumption of ideal mixing. The equations of energy balance and thermodynamic equilibrium are solved simultaneously for temperature and melt fraction, using an iterative procedure that allows addition of fluid in infinitesimal increments. Batch melting and fractional melting are simulated by allowing successive melt increments to remain in the system (batch) or not (fractional). Despite their simplified nature, these calculations reveal some important aspects of fluid-fluxed melting. The model confirms that, if the solubility of the fluid in the melt is sufficiently high, fluid fluxed melting is an efficient mechanism of magma generation. One might expect that the temperature of the infiltrating fluid would have a significant effect on melt productivity, but the results of the calculations show this not to be the case, because a relatively small mass of low molecular weight fluid has a strong effect on the melting point of minerals with much higher molecular weights. The calculations reveal the somewhat surprising result that fluid infiltration produces more melt during fractional melting than during batch melting. This behavior, which is opposite to that of decompression melting of a dry solid, arises because the melting point depression effect of the added fluid is greater during fractional melting than during batch melting, which results in a greater release of enthalpy and, therefore, greater melt production for fractional melting than for batch melting, for the same total amount of fluid added. The difference may be considerable. As an example, suppose that 0.1 mols of H2O infiltrate 1 mol or silicate rock. Depending on the rock composition this may corresponds to ˜ 1 wt% H2O. For a given choice of model parameters (initial temperature, heat capacity and entropy of fusion), about 28% of the rock melts during fractional melting, versus some 23 % during batch melting. Fluid fluxing is a robust process of melt generation, without which magmatism at Earth's convergent plate margins would be impossible.

Regulation of Phospholipid Synthesis in Escherichia coli by Guanosine Tetraphosphate

PubMed Central

Merlie, John P.; Pizer, Lewis I.

1973-01-01

Phospholipid synthesis has been reported to be subject to stringent control in Escherichia coli. We present evidence that demonstrates a strict correlation between guanosine tetraphosphate accumulation and inhibition of phospholipid synthesis. In vivo experiments designed to examine the pattern of phospholipid labeling with 32P-inorganic phosphate and 32P-sn-glycerol-3-phosphate suggest that regulation must occur at the glycerol-3-phosphate acyltransferase step. Assay of phospholipid synthesis by cell-free extracts and semipurified preparations revealed that guanosine tetraphosphate inhibits at least two enzymes specific for the biosynthetic pathway, sn-glycerol-3-phosphate acyltransferase as well as sn-glycerol-3-phosphate phosphatidyl transferase. These findings provide a biochemical basis for the stringent control of lipid synthesis as well as regulation of steady-state levels of phospholipid in growing cells. Images PMID:4583220

Characterization of Phospholipids in Insulin Secretory Granules and Mitochondria in Pancreatic Beta Cells and Their Changes with Glucose Stimulation*

PubMed Central

MacDonald, Michael J.; Ade, Lacmbouh; Ntambi, James M.; Ansari, Israr-Ul H.; Stoker, Scott W.

2015-01-01

The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. PMID:25762724

Phospholipid composition of cell-derived microparticles determined by one-dimensional high-performance thin-layer chromatography.

PubMed

Weerheim, A M; Kolb, A M; Sturk, A; Nieuwland, R

2002-03-15

Microparticles in the circulation activate the coagulation system and may activate the complement system via C-reactive protein upon conversion of membrane phospholipids by phospholipases. We developed a sensitive and reproducible method to determine the phospholipid composition of microparticles. Samples were applied to horizontal, one-dimensional high-performance thin-layer chromatography (HPTLC). Phospholipids were separated on HPTLC by chloroform:ethyl acetate:acetone:isopropanol:ethanol:methanol:water:acetic acid (30:6:6:6:16:28:6:2); visualized by charring with 7.5% Cu-acetate (w/v), 2.5% CuSO(4) (w/v), and 8% H(3)PO(4) (v/v) in water; and quantified by photodensitometric scanning. Erythrocyte membranes were used to validate the HPTLC system. Microparticles were isolated from plasma of healthy individuals (n = 10). On HPTLC, mixtures of (purified) phospholipids, i.e., lysophosphatidylcholine, phosphatidylcholine (PC), sphingomyelin (SM), lysophosphatidylserine, phosphatidylserine, lysophosphatidylethanolamine, phosphatidylethanolamine (PE), and phosphatidylinositol, could be separated and quantified. All phospholipids were detectable in erythrocyte ghosts, and their quantities fell within ranges reported earlier. Quantitation of phospholipids, including extraction, was highly reproducible (CV < 10%). Microparticles contained PC (59%), SM (20.6%), and PE (9.4%), with relatively minor (<5%) quantities of other phospholipids. HPTLC can be used to study the phospholipid composition of cell-derived microparticles and may also be a useful technique for the analysis of other samples that are available only in minor quantities. (C)2002 Elsevier Science (USA).

Phase diagrams of Janus fluids with up-down constrained orientations

NASA Astrophysics Data System (ADS)

Fantoni, Riccardo; Giacometti, Achille; Maestre, Miguel Ángel G.; Santos, Andrés

2013-11-01

A class of binary mixtures of Janus fluids formed by colloidal spheres with the hydrophobic hemispheres constrained to point either up or down are studied by means of Gibbs ensemble Monte Carlo simulations and simple analytical approximations. These fluids can be experimentally realized by the application of an external static electrical field. The gas-liquid and demixing phase transitions in five specific models with different patch-patch affinities are analyzed. It is found that a gas-liquid transition is present in all the models, even if only one of the four possible patch-patch interactions is attractive. Moreover, provided the attraction between like particles is stronger than between unlike particles, the system demixes into two subsystems with different composition at sufficiently low temperatures and high densities.

Effects of sugars on lipid bilayers during dehydration--SAXS/WAXS measurements and quantitative model.

PubMed

Lenné, Thomas; Garvey, Christopher J; Koster, Karen L; Bryant, Gary

2009-02-26

We present an X-ray scattering study of the effects of dehydration on the bilayer and chain-chain repeat spacings of dipalmitoylphosphatidylcholine bilayers in the presence of sugars. The presence of sugars has no effect on the average spacing between the phospholipid chains in either the fluid or gel phase. Using this finding, we establish that for low sugar concentrations only a small amount of sugar exclusion occurs. Under these conditions, the effects of sugars on the membrane transition temperatures can be explained quantitatively by the reduction in hydration repulsion between bilayers due to the presence of the sugars. Specific bonding of sugars to lipid headgroups is not required to explain this effect.

Phospholipid component volumes: determination and application to bilayer structure calculations.

PubMed

Armen, R S; Uitto, O D; Feller, S E

1998-08-01

We present a new method for the determination of bilayer structure based on a combination of computational studies and laboratory experiments. From molecular dynamics simulations, the volumes of submolecular fragments of saturated and unsaturated phosphatidylcholines in the liquid crystalline state have been extracted with a precision not available experimentally. Constancy of component volumes, both among different lipids and as a function of membrane position for a given lipid, have been examined. The component volumes were then incorporated into the liquid crystallographic method described by Wiener and White (1992. Biophys. J. 61:434-447, and references therein) for determining the structure of a fluid-phase dioleoylphosphatidylcholine bilayer from x-ray and neutron diffraction experiments.

Phospholipid component volumes: determination and application to bilayer structure calculations.

PubMed Central

Armen, R S; Uitto, O D; Feller, S E

1998-01-01

We present a new method for the determination of bilayer structure based on a combination of computational studies and laboratory experiments. From molecular dynamics simulations, the volumes of submolecular fragments of saturated and unsaturated phosphatidylcholines in the liquid crystalline state have been extracted with a precision not available experimentally. Constancy of component volumes, both among different lipids and as a function of membrane position for a given lipid, have been examined. The component volumes were then incorporated into the liquid crystallographic method described by Wiener and White (1992. Biophys. J. 61:434-447, and references therein) for determining the structure of a fluid-phase dioleoylphosphatidylcholine bilayer from x-ray and neutron diffraction experiments. PMID:9675175

[Inhibition of phospholipase A2 of peritoneal macrophages in rats by 1,2-di-O-hexadecyl-rac-glycero-3-phosphocholine].

PubMed

Boucrot, P; Khettab, E N; Petit, J Y; Welin, L

1993-01-01

The 1-O-stearoyl-2-O-[3H] arachidonyl-sn-glycero-3-phosphocholine, introduced in the culture medium, was taken up by the peritoneal macrophages activated by the ionophore A 23187. After intracellular phospholipase A2 activity, the [3H] arachidonic acid was found in cells and in extracellular fluids. It also reached the eicosanoid synthesis. When it was introduced in the culture medium with the tritiated phospholipid, the 1, 2 di-O-hexadecyl-rac-glycero-3-phosphocholine, which has a non hydrolysable alkylated structure in the 2 position of the glycerol, inhibited the intracellular phospholipase A2, then contributed to lower the eicosanoid synthesis.

Heat transfer performance of a pulsating heat pipe charged with acetone-based mixtures

NASA Astrophysics Data System (ADS)

Wang, Wenqing; Cui, Xiaoyu; Zhu, Yue

2017-06-01

Pulsating heat pipes (PHPs) are used as high efficiency heat exchangers, and the selection of working fluids in PHPs has a great impact on the heat transfer performance. This study investigates the thermal resistance characteristics of the PHP charged with acetone-based binary mixtures, where deionized water, methanol and ethanol were added to and mixed with acetone, respectively. The volume mixing ratios were 2:1, 4:1 and 7:1, and the heating power ranged from 10 to 100 W with filling ratios of 45, 55, 62 and 70%. At a low filling ratio (45%), the zeotropic characteristics of the binary mixtures have an influence on the heat transfer performance of the PHP. Adding water, which has a substantially different boiling point compared with that of acetone, can significantly improve the anti-dry-out ability inside the PHP. At a medium filling ratio (55%), the heat transfer performance of the PHP is affected by both phase transition characteristics and physical properties of working fluids. At high heating power, the thermal resistance of the PHP with acetone-water mixture is between that with pure acetone and pure water, whereas the thermal resistance of the PHP with acetone-methanol and acetone-ethanol mixtures at mixing ratios of 2:1 and 4:1 is less than that with the corresponding pure fluids. At high filling ratios (62 and 70%), the heat transfer performance of the PHP is mainly determined by the properties of working fluids that affects the flow resistance. Thus, the PHP with acetone-methanol and acetone-ethanol mixtures that have a lower flow resistance shows better heat transfer performance than that with acetone-water mixture.

Effect of elastic constants of liquid crystals in their electro-optical properties

NASA Astrophysics Data System (ADS)

Parang, Z.; Ghaffary, T.; Gharahbeigi, M. M.

Recently following the success of the density functional theory (DFT) in obtaining the structure and thermodynamics of homogeneous and inhomogeneous classical systems such as simple fluids, dipolar fluid and binary hard spheres, this theory was also applied to obtain the density profile of a molecular fluid in between hard planar walls by Kalpaxis and Rickayzen. In the theory of molecular fluids, the direct correlation function (DCF) can be used to calculate the equation of state, free energy, phase transition, elastic constants, etc. It is well known that the hard core molecular models play an important role in understanding complex liquids such as liquid crystals. In this paper, a classical fluid of nonspherical molecules is studied. The required homogeneous (DCF) is obtained by solving Orenstein-Zernike (OZ) integral equation numerically. Some of the molecules in the liquid crystals have a sphere shape and this kind of molecular fluid is considered here. The DCF sphere of the molecular fluid is calculated and it will be shown that the results are in good agreement with the pervious works and the results of computer simulation. Finally the electro-optical properties of ellipsoid liquid crystal using DCF of these molecules are calculated.

Induction of lactose transport in Escherichia coli during the absence of phospholipid synthesis.

PubMed Central

Weisberg, L J; Cronan, J E; Nunn, W D

1975-01-01

Induction of lactose transport and of beta-galactosidase synthesis was examined in two Escherichia coli strains that require exogenous glycerol for phospholipid synthesis and growth. No preferential inhibition of lactose transport induction was observed when phospholipid synthesis was restricted to 5 to 10% of the normal rate. We conclude that the lactose transport system does not require concurrent phospholipid synthesis for its functional assembly. PMID:1097412

Evaluation of Ultrafiltration Performance for Phospholipid Separation

NASA Astrophysics Data System (ADS)

Aryanti, N.; Wardhani, D. H.; Maulana, Z. S.; Roberto, D.

2017-11-01

Ultrafiltration membrane for degumming of crude palm oil has been applied as an alternative method since the membrane process required less procedure than the conventional degumming. This research focused on the examination of ultrafiltration performance for phospholipid separation from model crude palm oil degumming. Specifically, profile flux and rejection, as well as blocking mechanism, were investigated. Feed consisting of Refined Crude Palm Oil - Isopropanol - Lecithin mixtures were represented as crude palm oil degumming. Lecithin was denoted a phospholipid component, and the concentrations of lecithin in feed were varied to 0.1%, 0.2%, and 0.3%. The concentration of phospholipid was determined as phosphor content. At the concentration of lecithin in feed representing phospholipid concentration of 8,45 mg/kg, 8,45 mg/kg, 24,87 mg/kg and 57,58 mg/kg, respectively. Flux profiles confirmed that there was a flux decline during filtration. In addition, the lecithin concentrations do not significantly effect on further flux decline. Rejection characteristic and phospholipid concentration in the permeate showed that the phospholipid rejections by ultrafiltration were in the range of 23-79,5% representing permeate’s phospholipid concentration of 1,73 - 44,25 mg/kg. Evaluation of fouling mechanism by Hermia’s blocking model confirmed that the standard blocking is the dominant mechanism in the ultrafiltration of lecithin mixture.

The isotropic-nematic and nematic-nematic phase transition of binary mixtures of tangent hard-sphere chain fluids: An analytical equation of state

NASA Astrophysics Data System (ADS)

van Westen, Thijs; Vlugt, Thijs J. H.; Gross, Joachim

2014-01-01

An analytical equation of state (EoS) is derived to describe the isotropic (I) and nematic (N) phase of linear- and partially flexible tangent hard-sphere chain fluids and their mixtures. The EoS is based on an extension of Onsager's second virial theory that was developed in our previous work [T. van Westen, B. Oyarzún, T. J. H. Vlugt, and J. Gross, J. Chem. Phys. 139, 034505 (2013)]. Higher virial coefficients are calculated using a Vega-Lago rescaling procedure, which is hereby generalized to mixtures. The EoS is used to study (1) the effect of length bidispersity on the I-N and N-N phase behavior of binary linear tangent hard-sphere chain fluid mixtures, (2) the effect of partial molecular flexibility on the binary phase diagram, and (3) the solubility of hard-sphere solutes in I- and N tangent hard-sphere chain fluids. By changing the length bidispersity, two types of phase diagrams were found. The first type is characterized by an I-N region at low pressure and a N-N demixed region at higher pressure that starts from an I-N-N triphase equilibrium. The second type does not show the I-N-N equilibrium. Instead, the N-N region starts from a lower critical point at a pressure above the I-N region. The results for the I-N region are in excellent agreement with the results from molecular simulations. It is shown that the N-N demixing is driven both by orientational and configurational/excluded volume entropy. By making the chains partially flexible, it is shown that the driving force resulting from the configurational entropy is reduced (due to a less anisotropic pair-excluded volume), resulting in a shift of the N-N demixed region to higher pressure. Compared to linear chains, no topological differences in the phase diagram were found. We show that the solubility of hard-sphere solutes decreases across the I-N phase transition. Furthermore, it is shown that by using a liquid crystal mixture as the solvent, the solubility difference can by maximized by tuning the composition. Theoretical results for the Henry's law constant of the hard-sphere solute are in good agreement with the results from molecular simulation.

Molecular simulation of fluid mixtures in bulk and at solid-liquid interfaces

NASA Astrophysics Data System (ADS)

Kern, Jesse L.

The properties of a diverse range of mixture systems at interfaces are investigated using a variety of computational techniques. Molecular simulation is used to examine the thermodynamic, structural, and transport properties of heterogeneous systems of theoretical and practical importance. The study of binary hard-sphere mixtures at a hard wall demonstrates the high accuracy of recently developed classical-density functionals. The study of aluminum--gallium solid--liquid heterogeneous interfaces predicts a significant amount of prefreezing of the liquid by adopting the structure of the solid surface. The study of ethylene-expanded methanol within model silica mesopores shows the effect of confinement and surface functionalzation on the mixture composition and transport inside of the pores. From our molecular-dynamics study of binary hard-sphere fluid mixtures at a hard wall, we obtained high-precision calculations of the wall-fluid interfacial free energies, gamma. We have considered mixtures of varying diameter ratio, alpha = 0.7,0.8,0.9; mole fraction, x 1 = 0.25,0.50,0.75; and packing fraction, eta < 0.50. Using Gibbs-Cahn Integration, gamma is calculated from the system pressure, chemical potentials, and density profiles. Recent classical density-functional theory predictions agree very well with our results. Structural, thermodynamic, and transport properties of the aluminum--gallium solid--liquid interface at 368 K are obtained for the (100), (110), and (111) orientations using molecular dynamics. Density, potential energy, stress, and diffusion profiles perpendicular to the interface are calculated. The layers of Ga that form on the Al surface are strongly adsorbed and take the in-plane structure of the underlying crystal layers for all orientations, which results in significant compressive stress on the Ga atoms. Bulk methanol--ethylene mixtures under vapor-liquid equilibrium conditions have been characterized using Monte Carlo and molecular dynamics. The simulated vapor-liquid coexistence curves for the pure-component and binary mixtures agree well with experiment, as do the mixture volumetric expansion results. Using chemical potentials obtained from the bulk simulations, the filling of a number of model silica mesopores with ethylene and methanol is simulated. We report the compositions of the confined fluid mixtures over a range of pressures and for three degrees of nominal pore hydrophobicity.

Recent Advances in Phospholipids from Colostrum, Milk and Dairy By-Products.

PubMed

Verardo, Vito; Gómez-Caravaca, Ana Maria; Arráez-Román, David; Hettinga, Kasper

2017-01-17

Milk is one of the most important foods for mammals, because it is the first form of feed providing energy, nutrients and immunological factors. In the last few years, milk lipids have attracted the attention of researchers due to the presence of several bioactive components in the lipid fraction. The lipid fraction of milk and dairy products contains several components of nutritional significance, such as ω-3 and ω-6 polyunsaturated fatty acids, CLA, short chain fatty acids, gangliosides and phospholipids. Prospective cohort evidence has shown that phospholipids play an important role in the human diet and reinforce the possible relationship between their consumption and prevention of several chronic diseases. Because of these potential benefits of phospholipids in the human diet, this review is focused on the recent advances in phospholipids from colostrum, milk and dairy by-products. Phospholipid composition, its main determination methods and the health activities of these compounds will be addressed.

Beta-adrenergic control of phosphatidylcholine synthesis by transmethylation in hepatocytes from juvenile, adult and adrenalectomized rats.

PubMed Central

Marin-Cao, D; Alvarez Chiva, V; Mato, J M

1983-01-01

Changes in isoprenaline-sensitive phospholipid methyltransferase were studied in hepatocytes isolated from juvenile, mature and adrenalectomized rats. Isoprenaline produced greater stimulation of cyclic AMP accumulation in juvenile and mature adrenalectomized rats than in mature animals. Similarly, isoprenaline stimulated phospholipid methyltransferase in juvenile and mature adrenalectomized rats but had no effect in mature animals. Isoprenaline-mediated activation of phospholipid methyltransferase in adrenalectomized rats was time- and dose-dependent. In hepatocytes isolated from adrenalectomized rats incubated with [Me-3H]methionine or [3H]-ethanolamine the addition of isoprenaline increased the amount of radioactivity incorporated into phosphatidylcholine. The activation by isoprenaline of phospholipid methyltransferase was abolished by the beta-blocker propranolol and by insulin. These results indicate that rat liver the occupation of functional beta-receptors causes a stimulation of phospholipid methylation. It is suggested that, as reported previously, cyclic AMP activates phospholipid methyltransferase. PMID:6320796

Recent Advances in Phospholipids from Colostrum, Milk and Dairy By-Products

PubMed Central

Verardo, Vito; Gómez-Caravaca, Ana Maria; Arráez-Román, David; Hettinga, Kasper

2017-01-01

Milk is one of the most important foods for mammals, because it is the first form of feed providing energy, nutrients and immunological factors. In the last few years, milk lipids have attracted the attention of researchers due to the presence of several bioactive components in the lipid fraction. The lipid fraction of milk and dairy products contains several components of nutritional significance, such as ω-3 and ω-6 polyunsaturated fatty acids, CLA, short chain fatty acids, gangliosides and phospholipids. Prospective cohort evidence has shown that phospholipids play an important role in the human diet and reinforce the possible relationship between their consumption and prevention of several chronic diseases. Because of these potential benefits of phospholipids in the human diet, this review is focused on the recent advances in phospholipids from colostrum, milk and dairy by-products. Phospholipid composition, its main determination methods and the health activities of these compounds will be addressed. PMID:28106745

Absence of a direct role of phospholipid methylation in stimulus-secretion coupling and control of adenylate cyclase in guinea-pig and rat parotid gland.

PubMed Central

Padel, U; Unger, C; Söling, H D

1982-01-01

The present study was undertaken to investigate a possible involvement of phospholipid methyltransferases in the coupling of receptor-mediated stimulation to secretion. Phospholipid methyltransferases were assayed in isolated parotid acini in the presence of carbamoylcholine or isoprenaline. Carbamoylcholine reduced the incorporation of methyl groups into phospholipids, whereas isoprenaline showed no effect. Amylase secretion stimulated either by carbamoylcholine or by isoprenaline could not be affected by inhibitors of methyltransferases (3-deaza-adenosine alone or plus homocysteine thiolactone) under conditions where phospholipid methylation was strongly inhibited. The activity of adenylate cyclase in isolated parotid microsomal membranes was not inhibited or stimulated by S-adenosyl-homocysteine or -methionine respectively. These results indicate that phospholipid methylation does not play an essential role in stimulus-secretion coupling in the parotid gland. PMID:6186246

Development of fat-reduced sausages: Influence of binary and ternary combinations of carrageenan, inulin, and bovine plasma proteins.

PubMed

Baracco, Yanina; Rodriguez Furlán, Laura T; Campderrós, Mercedes E

2017-04-01

The aim of this work was to study the influence of the binary and ternary combinations of bovine plasma proteins (BPP), inulin (I) and κ-carrageenan (C) in the overall quality of fat-reduced sausages. The influence of these components over different properties (chemical composition, weight loss after cooking, emulsion stability, texture profile and sensory analysis of fat-reduced sausages) was studied and compared against two samples, one without fat reduction and another a fat-reduced sample without addition of texturing agents. In this sense, a full factorial experimental design of two levels with central point was used. The samples containing BPP+I and BPP+C showed a synergy in which the binary combinations presented higher values of moisture and protein content than the samples containing the individual components. The reduction of fat content increases the values of hardness and decreases the values of springiness. Samples with 5% BPP (w/w) and binary combinations of BPP+C and BPP+I had the best stability values (low total fluid loss), demonstrating a significant synergistic effect by combining BPP+C. Similar results were obtained from the study of weight loss after cooking. However, both studies showed a destabilization of the sample BPP+I+C as emulsion stability decreased and weight loss increased after cooking compared to binary combinations ( P < 0.05). Samples with a binary combination of BPP+C and BPP+I do not present a statistically significant difference in the chewiness with respect to a not-fat-reduced commercial sample ( P > 0.05). The less acceptable sample for flavor and texture was the one containing only BPP. However, when BPP combined with I or C, a major acceptability was obtained, demonstrating the synergistic effect of these binary combinations. Therefore, our studies revealed that the binary combinations of BPP with I or C are good alternatives for the development of fat-reduced sausage.

Characterization of phospholipids in insulin secretory granules and mitochondria in pancreatic beta cells and their changes with glucose stimulation.

PubMed

MacDonald, Michael J; Ade, Lacmbouh; Ntambi, James M; Ansari, Israr-Ul H; Stoker, Scott W

2015-04-24

The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Products of lipid peroxidation, but not membrane susceptibility to oxidative damage, are conserved in skeletal muscle following temperature acclimation

PubMed Central

Semones, Molly C.; Kuhn, Donald E.; Kriska, Tamas; Keszler, Agnes; Crockett, Elizabeth L.

2014-01-01

Changes in oxidative capacities and phospholipid remodeling accompany temperature acclimation in ectothermic animals. Both responses may alter redox status and membrane susceptibility to lipid peroxidation (LPO). We tested the hypothesis that phospholipid remodeling is sufficient to offset temperature-driven rates of LPO and, thus, membrane susceptibility to LPO is conserved. We also predicted that the content of LPO products is maintained over a range of physiological temperatures. To assess LPO susceptibility, rates of LPO were quantified with the fluorescent probe C11-BODIPY in mitochondria and sarcoplasmic reticulum from oxidative and glycolytic muscle of striped bass (Morone saxatilis) acclimated to 7°C and 25°C. We also measured phospholipid compositions, contents of LPO products [i.e., individual classes of phospholipid hydroperoxides (PLOOH)], and two membrane antioxidants. Despite phospholipid headgroup and acyl chain remodeling, these alterations do not counter the effect of temperature on LPO rates (i.e., LPO rates are generally not different among acclimation groups when normalized to phospholipid content and compared at a common temperature). Although absolute levels of PLOOH are higher in muscles from cold- than warm-acclimated fish, this difference is lost when PLOOH levels are normalized to total phospholipid. Contents of vitamin E and two homologs of ubiquinone are more than four times higher in mitochondria prepared from oxidative muscle of warm- than cold-acclimated fish. Collectively, our data demonstrate that although phospholipid remodeling does not provide a means for offsetting thermal effects on rates of LPO, differences in phospholipid quantity ensure a constant proportion of LPO products with temperature variation. PMID:25519739

Developmentally regulated changes in phospholipid composition in murine molar tooth.

PubMed

Dunglas, C; Septier, D; Carreau, J P; Goldberg, M

1999-08-01

In order to explore the possibility that phospholipids are differently expressed during the cascade of events leading to tooth formation, we decided to carry out simultaneous biochemical, histological and electron histochemical studies. High performance thin-layer chromatography and gas-liquid chromatography were used to compare the composition of embryonic mouse first molar tooth germs at day 18 of gestation (E18) and at birth (D1), erupting teeth at day 7 (D7) and erupted molars at day 21 (D21). For the latter, non-demineralized and EDTA-demineralized lipid extracts were analysed separately. Moreover, an ultrahistochemical study was carried out using the iodoplatinate reaction which retains and visualizes phospholipids. Developmentally regulated changes occurred and were closely correlated with an increase in cell membrane phospholipids. Gradual accumulation of phospholipids was identified in the extracellular matrix, at an early stage of tooth germ development within the basement membrane and later, as predentine/dentine and enamel components participating in mineralization processes. Matrix vesicles transiently present in dentine were partly responsible for the lipids that were detected. A first group of phospholipids including phosphatidylcholine as the major membrane-associated phospholipid and phosphatidylinositol as the intracellular second messenger increased by a factor of 2.3 between E18 and D21. This increase is probably associated with cell lengthening and was relatively modest compared with the higher increase detected for a second group of phospholipids, namely phosphatidylethanolamine (x4.8), phosphatidylserine (x 5.9) and sphingomyelin (x5.4). This second group of extracellular matrix-associated phospholipids constituted 68% of the demineralized lipid extract and, therefore, contributes to the mineralization of dental tissues.

Intracellular Signaling by Hydrolysis of Phospholipids and Activation of Protein Kinase C

NASA Astrophysics Data System (ADS)

Nishizuka, Yasutomi

1992-10-01

Hydrolysis of inositol phospholipids by phospholipase C is initiated by either receptor stimulation or opening of Ca2+ channels. This was once thought to be the sole mechanism to produce the diacylglycerol that links extracellular signals to intracellular events through activation of protein kinase C. It is becoming clear that agonist-induced hydrolysis of other membrane phospholipids, particularly choline phospholipids, by phospholipase D and phospholipase A_2 may also take part in cell signaling. The products of hydrolysis of these phospholipids may enhance and prolong the activation of protein kinase C. Such prolonged activation of protein kinase C is essential for long-term cellular responses such as cell proliferation and differentiation.

Cerebrospinal fluid ferritin and albumin index: potential candidates for scoring system to differentiate between bacterial and viral meningitis in children.

PubMed

Jebamalar, Angelin A; Prabhat; Balakrishnapillai, Agiesh K; Parmeswaran, Narayanan; Dhiman, Pooja; Rajendiran, Soundravally

2016-07-01

To evaluate the diagnostic role of cerebrospinal fluid (CSF) ferritin and albumin index (AI = CSF albumin/serum albumin × 1000) in differentiating acute bacterial meningitis (ABM) from acute viral meningitis (AVM) in children. The study included 42 cases each of ABM and AVM in pediatric age group. Receiver operating characteristic (ROC) analysis was carried out for CSF ferritin and AI. Binary logistic regression was also done. CSF ferritin and AI were found significantly higher in ABM compared to AVM. Model obtained using AI and CSF ferritin along with conventional criteria is better than existing models.

Calculating the surface tension of binary solutions of simple fluids of comparable size

NASA Astrophysics Data System (ADS)

Zaitseva, E. S.; Tovbin, Yu. K.

2017-11-01

A molecular theory based on the lattice gas model (LGM) is used to calculate the surface tension of one- and two-component planar vapor-liquid interfaces of simple fluids. Interaction between nearest neighbors is considered in the calculations. LGM is applied as a tool of interpolation: the parameters of the model are corrected using experimental surface tension data. It is found that the average accuracy of describing the surface tension of pure substances (Ar, N2, O2, CH4) and their mixtures (Ar-O2, Ar-N2, Ar-CH4, N2-CH4) does not exceed 2%.

Buoyancy-Marangoni convection in confined volatile binary fluids subject to a horizontal temperature gradient

NASA Astrophysics Data System (ADS)

Qin, Tongran; Grigoriev, Roman

2017-11-01

We consider convection in a layer of binary fluid with free surface subject to a horizontal temperature gradient in the presence of noncondensable gases, which is driven by a combination of three different forces: buoyancy, thermocapillarity, and solutocapillarity. Unlike buoyancy, both thermo- and solutocapillary stresses depend sensitively on the local phase equilibrium at the liquid-gas interface. In particular, thermocapillarity associated with the interfacial temperature gradient is controlled by the vapors' concentration along the interface, and solutocapillarity associated with the interfacial concentration gradient is controlled by differential phase change of two components of the liquid, which is strongly influenced by the presence of noncondensables. Therefore, flows in both phases, phase change, and effect of noncondensables all have to be considered. Numerical simulations based on a comprehensive model taking these effects into account show qualitative agreement with recent experiments which identified a number of flow regimes at various compositions of both phases. In particular,we find that the composition of both the gas and liquid phase have a significant effect on the observed convection patterns; this dependence can be understood using a simple analytical model. This material is based upon work supported by the National Science Foundation under Grant No. 1511470.

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

Stagg, Alan K; Yoon, Su-Jong

This report describes the Consortium for Advanced Simulation of Light Water Reactors (CASL) work conducted for completion of the Thermal Hydraulics Methods (THM) Level 3 Milestone THM.CFD.P11.02: Hydra-TH Extensions for Multispecies and Thermosolutal Convection. A critical requirement for modeling reactor thermal hydraulics is to account for species transport within the fluid. In particular, this capability is needed for modeling transport and diffusion of boric acid within water for emergency, reactivity-control scenarios. To support this need, a species transport capability has been implemented in Hydra-TH for binary systems (for example, solute within a solvent). A species transport equation is solved formore » the species (solute) mass fraction, and both thermal and solutal buoyancy effects are handled with specification of a Boussinesq body force. Species boundary conditions can be specified with a Dirichlet condition on mass fraction or a Neumann condition on diffusion flux. To enable enhanced species/fluid mixing in turbulent flow, the molecular diffusivity for the binary system is augmented with a turbulent diffusivity in the species transport calculation. The new capabilities are demonstrated by comparison of Hydra-TH calculations to the analytic solution for a thermosolutal convection problem, and excellent agreement is obtained.« less

The effect of insulin deficiency on the plasma clearance and exchange of high-density-lipoprotein phosphatidylcholine in rats.

PubMed Central

Martins, I J; Redgrave, T G

1992-01-01

Triolein/cholesteryl oleate/cholesterol/phosphatidylcholine emulsions designed to model the lipid composition of chylomicrons were injected intravenously into control and streptozotocin-treated insulin-deficient rats. As previously described for lymph chylomicrons, the emulsion triolein was hydrolysed and phosphatidylcholine was transferred to the plasma high-density lipoproteins (HDL). This mechanism was used to introduce a phospholipid label into HDL in vivo. The subsequent clearance of phospholipid radioactivity from the plasma of insulin-deficient rats was significantly slower than in controls (P less than 0.025). Plasma clearance was similarly slower in insulin-deficient rats after injection of HDL that was previously labelled with radioactive phospholipids. After injection, the phospholipid label redistributed rapidly between the large-particle fraction of plasma lipoproteins (very-low- and low-density lipoproteins), and the lighter and heavier fractions of HDL. Compared with control rats, in insulin-deficient rats less of the phospholipid label was distributed to the lighter HDL fraction and more to the heavier HDL fraction, and this difference was not due to changes in activity of lecithin: cholesterol acyltransferase or in the apparent activity of phospholipid transfer protein. In insulin-deficient rats the changes in HDL phospholipid clearance and exchange appeared to be secondary to the associated hypertriglyceridaemia and the related changes in distribution of phospholipids between classes of plasma lipoproteins. PMID:1536661

Tombusviruses upregulate phospholipid biosynthesis via interaction between p33 replication protein and yeast lipid sensor proteins during virus replication in yeast

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

Barajas, Daniel; Xu, Kai; Sharma, Monika

Positive-stranded RNA viruses induce new membranous structures and promote membrane proliferation in infected cells to facilitate viral replication. In this paper, the authors show that a plant-infecting tombusvirus upregulates transcription of phospholipid biosynthesis genes, such as INO1, OPI3 and CHO1, and increases phospholipid levels in yeast model host. This is accomplished by the viral p33 replication protein, which interacts with Opi1p FFAT domain protein and Scs2p VAP protein. Opi1p and Scs2p are phospholipid sensor proteins and they repress the expression of phospholipid genes. Accordingly, deletion of OPI1 transcription repressor in yeast has a stimulatory effect on TBSV RNA accumulation andmore » enhanced tombusvirus replicase activity in an in vitro assay. Altogether, the presented data convincingly demonstrate that de novo lipid biosynthesis is required for optimal TBSV replication. Overall, this work reveals that a (+)RNA virus reprograms the phospholipid biosynthesis pathway in a unique way to facilitate its replication in yeast cells. - Highlights: • Tombusvirus p33 replication protein interacts with FFAT-domain host protein. • Tombusvirus replication leads to upregulation of phospholipids. • Tombusvirus replication depends on de novo lipid synthesis. • Deletion of FFAT-domain host protein enhances TBSV replication. • TBSV rewires host phospholipid synthesis.« less

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

Jope, R.S.; Casebolt, T.L.; Johnson, G.V.

Cortical slices from rat brain were used to study carbachol-stimulated inositol phospholipid hydrolysis. Omission of calcium during incubation of slices with (/sup 3/H)inositol increased its incorporation into receptor-coupled phospholipids. Carbachol-stimulated hydrolysis of (/sup 3/H)inositol phospholipids in slices was dose-dependent, was affected by the concentrations of calcium and lithium present and resulted in the accumulation of mostly (/sup 3/H)inositol-1-phosphate. Incubation of slices with N-ethylmaleimide or a phorbol ester reduced the response to carbachol. Membranes prepared from cortical slices labeled with (/sup 3/H)inositol retained the receptor-stimulated inositol phospholipid hydrolysis reaction. The basal rate of inositol phospholipid hydrolysis was higher than in slicesmore » and addition of carbachol further stimulated the process. Addition of GTP stimulated inositol phospholipid hydrolysis, suggesting the presence of a guanine nucleotide-binding protein coupled to phospholipase C. Carbachol and GTP-stimulated inositol phospholipid hydrolysis in membranes was detectable following a 3 min assay period. In contrast to slices, increased levels of inositol bisphosphate and inositol trisphosphate were detected following incubation of membranes with carbachol. These results demonstrate that agonist-responsive receptors are present in cortical membranes, that the receptors may be coupled to phosphatidylinositol 4, 5-bisphosphate, rather than phosphatidylinositol, hydrolysis and that a guanine nucleotide-binding protein may mediate the coupling of receptor activation to inositol phospholipid hydrolysis in brain.« less

Phospholipase A2 activity-dependent and -independent fusogenic activity of Naja nigricollis CMS-9 on zwitterionic and anionic phospholipid vesicles.

PubMed

Chiou, Yi-Ling; Chen, Ying-Jung; Lin, Shinne-Ren; Chang, Long-Sen

2011-11-01

CMS-9, a phospholipase A(2) (PLA(2)) from Naja nigricollis venom, induced the death of human breast cancer MCF-7 cells accompanied with the formation of cell clumps without clear boundaries between cells. Annexin V-FITC staining indicated that abundant phosphatidylserine appeared on the outer membrane of MCF-7 cell clumps, implying the possibility that CMS-9 may promote membrane fusion via anionic phospholipids. To validate this proposition, fusogenic activity of CMS-9 on vesicles composed of zwitterionic phospholipid alone or a combination of zwitterionic and anionic phospholipids was examined. Although CMS-9-induced fusion of zwitterionic phospholipid vesicles depended on PLA(2) activity, CMS-9-induced fusion of vesicles containing anionic phospholipids could occur without the involvement of PLA(2) activity. Membrane-damaging activity of CMS-9 was associated with its fusogenicity. Moreover, CMS-9 induced differently membrane leakage and membrane fusion of vesicles with different compositions. Membrane fluidity and binding capability with phospholipid vesicles were not related to the fusogenicity of CMS-9. However, membrane-bound conformation and mode of CMS-9 depended on phospholipid compositions. Collectively, our data suggest that PLA(2) activity-dependent and -independent fusogenicity of CMS-9 are closely related to its membrane-bound modes and targeted membrane compositions. Copyright © 2011 Elsevier Ltd. All rights reserved.

Critical Synergistic Concentration of Lecithin Phospholipids Improves the Antimicrobial Activity of Eugenol against Escherichia coli.

PubMed

Zhang, Haoshu; Dudley, Edward G; Harte, Federico

2017-11-01

In this study, the effect of individual lecithin phospholipids on the antimicrobial properties of eugenol against Escherichia coli C600 was investigated. We tested five major phospholipids common in soy or egg lecithin (1,2-dihexadecanoyl-sn-glycero-3-phosphocholine [DPPC], 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine [DSPC], 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine [DPPE], 1,2-dihexadecanoyl-sn-glycero-3-phosphate [sodium salt] [DPPA], and 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine [DPPS]) and one synthetic cationic phospholipid (1,2-dioctadecanoyl-sn-glycero-3-ethylphosphocholine [18:0 EPC]). Among the six phospholipids, DPPC, DSPC, DPPE, DPPA, and the cationic 18:0 EPC showed critical synergistic concentrations that significantly improved the inactivation effect of eugenol against E. coli after 30 min of exposure. At the critical synergistic concentration, an additional ca. 0.4 to 1.9 log reduction (ca. 0.66 to 2.17 log CFU/ml reduction) in the microbial population was observed compared to eugenol-only (control) treatments (ca. 0.25 log reduction). In all cases, increasing the phospholipid amount above the critical synergistic concentration (which was different for each phospholipid) resulted in antimicrobial properties similar to those seen with the eugenol-only (control) treatments. DPPS did not affect the antimicrobial properties of eugenol at the tested concentrations. The critical synergistic concentration of phospholipids was correlated with their critical micelle concentrations (CMC). IMPORTANCE Essential oils (EOs) are naturally occurring antimicrobials, with limited use in food due to their hydrophobicity and strong aroma. Lecithin is used as a natural emulsifier to stabilize EOs in aqueous systems. We previously demonstrated that, within a narrow critical-concentration window, lecithin can synergistically enhance the antimicrobial properties of eugenol. Since lecithin is a mixture of different phospholipids, we aimed to identify which phospholipids are crucial for the observed synergistic effect. This research studied the bioactivity of lecithin phospholipids, contributing to a rational design in using lecithin to effectively control foodborne pathogens in foods. Copyright © 2017 American Society for Microbiology.

The fate and origin of the nuclear envelope during and after mitosis in Amoeba proteus. I. Synthesis and behavior of phospholipids of the nuclear envelope during the cell life cycle

PubMed Central

1975-01-01

The synthesis and behavior of Amoeba proteus nuclear envelope (NE) phospholipids were studied. Most NE phospholipid synthesis occurs during G2 and little during mitosis or S. (A. proteus has no G1 phase). Autoradiographic observations after implantation of [3-H] choline nuclei into unlabeled cells reveal little turnover of NE phospholipid during interphase but during mitosis all the label is dispersed through the cytoplasm. Beginning at telophase all the label is dispersed through the cytoplasm. Beginning at telophase all the NE phospholipid label returns to the daughter NEs. This observation, along with the finding that no NE phospholipid synthesis occurs during mitosis or S, indicates that no de novo NE phospholipid production is required for newly forming NEs. Similarlyemetine, at concentrations that inhibit 97 percent of protein synthesis, does not prevent the post mitotic formation of NEs, suggesting that previously manufactured proteins are used in making new NEs. If a nucleus containing labeled NE phospholipids is transplanted into an unlabeled nucleate cell and the cell is allowed to grow and divide, the resultant four nuclei are equally labeled. This finding supports, but does not prove (see next paragraph), the conclusion that there probably is no continuity of the A. proteus NE during mitosis. When a phospholipid-labeled nucleus is implanted into a cell in mitosis, the grafted nucleus is not induced to enter mitosis. There is, however, a marked increase in the turnover of that nucleus's NE phospholipids with no apparent breakdown of the NE; this indicated that the mitotic cytoplasm possesses a factor that stimulates NE phospholipid exchange with the cytoplasm. That enhanced turnover is not accompanied by visible structural alteration makes less certain the earlier conclusion that no NE continuity exists during mitosis. Perhaps the most important finding in this study is that there are present, at restricted times in the cell cycle, factors capable of inducing accelerated exchange of structural components without microscopically detectable disruptions of structure. PMID:805790

Influence of the physical state of phospholipid monolayers on protein binding.

PubMed

Boisselier, Élodie; Calvez, Philippe; Demers, Éric; Cantin, Line; Salesse, Christian

2012-06-26

Langmuir monolayers were used to characterize the influence of the physical state of phospholipid monolayers on the binding of protein Retinis Pigmentosa 2 (RP2). The binding parameters of RP2 (maximum insertion pressure (MIP), synergy and ΔΠ(0)) in monolayers were thus analyzed in the presence of phospholipids bearing increasing fatty acyl chain lengths at temperatures where their liquid-expanded (LE), liquid-condensed (LC), or solid-condensed (SC) states can be individually observed. The data show that a larger value of synergy is observed in the LC/SC states than in the LE state, independent of the fatty acyl chain length of phospholipids. Moreover, both the MIP and the ΔΠ(0) increase with the fatty acyl chain length when phospholipids are in the LC/SC state, whereas those binding parameters remain almost unchanged when phospholipids are in the LE state. This effect of the phospholipid physical state on the binding of RP2 was further demonstrated by measurements performed in the presence of a phospholipid monolayer showing a phase transition from the LE to the LC state at room temperature. The data collected are showing that very similar values of MIP but very different values of synergy and ΔΠ(0) are obtained in the LE (below the phase transition) and LC (above the phase transition) states. In addition, the binding parameters of RP2 in the LE (below the phase transition) as well as in the LC (above the phase transition) states were found to be indistinguishable from those where single LC and LE states are respectively observed. The preference of RP2 for binding phospholipids in the LC state was then confirmed by the observation of a large modification of the shape of the LC domains in the phase transition. Therefore, protein binding parameters can be strongly influenced by the physical state of phospholipid monolayers. Moreover, measurements performed with the α/β domain of RP2 strongly suggest that the β helix of RP2 plays a major role in the preferential binding of this protein to phospholipids in the LC state.

1H NMR Shows Slow Phospholipid Flip-Flop in Gel and Fluid Bilayers

DOE PAGES

Marquardt, Drew; Heberle, Frederick A.; Miti, Tatiana; ...

2017-01-20

We measured the transbilayer diffusion of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) in large unilamellar vesicles, in both the gel (L β') and fluid (L α) phases. The choline resonance of headgroup-protiated DPPC exchanged into the outer leaflet of headgroup-deuterated DPPC-d13 vesicles was monitored using 1H NMR spectroscopy, coupled with the addition of a paramagnetic shift reagent. This allowed us to distinguish between the inner and outer bilayer leaflet of DPPC, to determine the flip-flop rate as a function of temperature. Flip-flop of fluid-phase DPPC exhibited Arrhenius kinetics, from which we determined an activation energy of 122 kJ mol –1. In gel-phase DPPC vesicles,more » flip-flop was not observed over the course of 250 h. Here, our findings are in contrast to previous studies of solid-supported bilayers, where the reported DPPC translocation rates are at least several orders of magnitude faster than those in vesicles at corresponding temperatures. Finally, we reconcile these differences by proposing a defect-mediated acceleration of lipid translocation in supported bilayers, where long-lived, submicron-sized holes resulting from incomplete surface coverage are the sites of rapid transbilayer movement.« less

Magneto-therapy of human joint cartilage.

PubMed

Wierzcholski, Krzysztof; Miszczak, Andrzej

2017-01-01

The topic of the present paper concerns the human joint cartilage therapy performed by the magnetic induction field. There is proved the thesis that the applied magnetic field for concrete cartilage illness should depend on the proper relative and concrete values of applied magnetic induction, intensity as well the time of treatment duration. Additionally, very important are frequencies and amplitudes of magnetic field as well as magnetic permeability of the synovial fluid. The research methods used in this paper include: magnetic induction field produced by a new Polish and German magneto electronic devices for the therapy of human joint cartilage diseases, stationary and movable magnetic applicators, magnetic bandage, ferrofluid injections, author's experience gained in Germany research institutes and practical results after measurements and information from patients. The results of this paper concern concrete parameters of time dependent electro-magnetic field administration during the joint cartilage therapy duration and additionally concern the corollaries which are implied from reading values gained on the magnetic induction devices. The main conclusions obtained in this paper are as follows: Time dependent magnetic induction field increases the dynamic viscosity of movable synovial fluid and decreases symptoms of cartilage illness for concrete intensity of magnetic field and concrete field line architecture. The ferrofluid therapy and phospholipids bilayer simultaneously with the administrated external electromagnetic field, increases the dynamic viscosity of movable synovial fluid.

Determination of pore sizes and relative porosity in porous nanoshell architectures using dextran retention with single monomer resolution and proton permeation

PubMed Central

Muhandiramlage, Thusitha P.; Cheng, Zhiliang; Roberts, David L.; Keogh, John P.; Hall, Henry K.; Aspinwall, Craig A.

2012-01-01

Unilamellar phospholipid vesicles prepared using the polymerizable lipid bis-sorbylphosphatidylcholine (bis-SorbPC) yield three-dimensional nanoarchitectures that are highly permeable to small molecules. The resulting porous phospholipid nanoshells (PPNs) are potentially useful for a range of biomedical applications including nanosensors and nanodelivery vehicles for cellular assays and manipulations. The uniformity and size distribution of the pores, key properties for sensor design and utilization, has not previously been reported. Fluorophore-assisted carbohydrate electrophoresis (FACE) was utilized to assess the nominal molecular weight cutoff limit (NMCL) of the PPN via analysis of retained dextran with single monomer resolution. The NMCL of PPNs prepared from pure bis-SorbPC was equivalent to a 1800 Da linear dextran, corresponding to a maximum pore diameter of 2.6 nm. Further investigation of PPNs prepared using binary mixtures of bis-SorbPC and dioleylphosphatidylcholine (DOPC) revealed a similar NMCL when the bis-SorbPC content exceeded 30 mol %, whereas different size-dependent permeation was observed below this composition. Below 30 mol % bis-SorbPC, dextran retention provided insufficient mass resolution (162 Da) to observe porosity on the experimental time scale; however, proton permeability showed a marked enhancement for bis-SorbPC ≥ 10 mol %. Combined these data suggest that the NMCL for native pores in bis-SorbPC PPNs results from an inherent property within the lipid assembly that can be partially disrupted by dilution of bis-SorbPC below a critical value for domain formation. Additionally, the analytical method described herein should prove useful for the challenging task of elucidating porosity in a range of three-dimensional nanomaterials. PMID:23083108

Effects of Phenethyl Alcohol on Phospholipid Metabolism in Escherichia coli

PubMed Central

Nunn, William D.; Tropp, Burton E.

1972-01-01

The incorporation of labeled precursors into the deoxyribonucleic acid, ribonucleic acid (RNA), proteins, and phospholipids of Escherichia coli cultured in the presence of phenethyl alcohol (PEA) was determined. PEA inhibited the uptake of labeled uracil to the same extent in cells exhibiting relaxed and stringent control of RNA synthesis. This indicates that PEA does not primarily affect amino acid synthesis or activation. Uptake of labeled acetate into the phospholipid fraction was more sensitive to inhibition by low concentrations of PEA than was the uptake of labeled precursors into the macromolecules. Thymine starvation or the addition of nalidixic acid (10 μg/ml) had no effect on acetate incorporation. Chloramphenicol (25 μg/ml) was a much less effective inhibitor of acetate incorporation than was PEA. The distribution of labeled acetate incorporated into phospholipids was markedly affected by the presence of PEA. The uptake of acetate into phosphatidylethanolamine and phosphatidylglycerol was inhibited, whereas the uptake of acetate into the cardiolipin fraction was unaffected. Since acetate incorporation into phospholipid was quite sensitive to PEA, we suggest that the PEA-sensitive component required for the initiation of replication may be a phospholipid(s). PMID:4550658

Out-of-the-groove transport of lipids by TMEM16 and GPCR scramblases.

PubMed

Malvezzi, Mattia; Andra, Kiran K; Pandey, Kalpana; Lee, Byoung-Cheol; Falzone, Maria E; Brown, Ashley; Iqbal, Rabia; Menon, Anant K; Accardi, Alessio

2018-06-20

Phospholipid scramblases externalize phosphatidylserine to facilitate numerous physiological processes. Several members of the structurally unrelated TMEM16 and G protein-coupled receptor (GPCR) protein families mediate phospholipid scrambling. The structure of a TMEM16 scramblase shows a membrane-exposed hydrophilic cavity, suggesting that scrambling occurs via the ‟credit-card" mechanism where lipid headgroups permeate through the cavity while their tails remain associated with the membrane core. Here we show that afTMEM16 and opsin, representatives of the TMEM16 and GCPR scramblase families, transport phospholipids with polyethylene glycol headgroups whose globular dimensions are much larger than the width of the cavity. This suggests that transport of these large headgroups occurs outside rather than within the cavity. These large lipids are scrambled at rates comparable to those of normal phospholipids and their presence in the reconstituted vesicles promotes scrambling of normal phospholipids. This suggests that both large and small phospholipids can move outside the cavity. We propose that the conformational rearrangements underlying TMEM16- and GPCR-mediated credit-card scrambling locally deform the membrane to allow transbilayer lipid translocation outside the cavity and that both mechanisms underlie transport of normal phospholipids.

Phospholipids and products of their hydrolysis as dietary preventive factors for civilization diseases.

PubMed

Parchem, Karol; Bartoszek, Agnieszka

2016-12-31

The results of numerous epidemiological studies indicate that phospholipids play an important role in the prevention of chronic diseases faced by contemporary society. Firstly, these compounds are responsible for the proper functioning of cell membranes, by ensuring liquidity and permeability, which is pivotal for normal activity of membrane proteins, including receptors. These mechanisms are at the core of prevention of cancer, autoimmune or neurological disorders. Secondly, structure and properties of phospholipids cause that they are highly available source of biologically active fatty acids. Thirdly, also products of endogenous hydrolysis of phospholipids exhibit biological activity. These include lysophospholipids formed as a result of disconnecting free fatty acid from glycerophospholipids in the reaction catalyzed by phospholipase A, phosphatidic acid and hydrophilic subunits released by the activity of phospholipase D. The bioactive products of hydrolysis also include ceramides liberated from phosphosphingolipids after removal of a hydrophilic unit catalyzed by sphingomyelinase. Phospholipids are supplied to the human body with food. A high content of phospholipids is characteristic for egg yolk, liver, pork and poultry, as well as some soy products. Particularly beneficial are phospholipids derived from seafood because they are a rich source of essential fatty acids of the n-3 family.

STRUCTURAL DETERMINATION AND QUANTITATIVE ANALYSIS OF BACTERIAL PHOSPHOLIPIDS USING LIQUID CHROMATOGRAPHY/ELECTROSPRAY IONIZATION/MASS SPECTROMETRY

EPA Science Inventory

This report presents a comprehensive spectral analysis of common bacterial phospholipids using electrospray/mass spectrometry (ESI/MS) under both negative and positive ionization conditions. Phospholipids under positive ionization yield sodium-adduct molecular ions which are mos...

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.

Microfluidic co-flow of Newtonian and viscoelastic fluids for high-resolution separation of microparticles.

PubMed

Tian, Fei; Zhang, Wei; Cai, Lili; Li, Shanshan; Hu, Guoqing; Cong, Yulong; Liu, Chao; Li, Tiejun; Sun, Jiashu

2017-09-12

The microfluidic passive control of microparticles largely relies on the hydrodynamic effects of the carrier media such as Newtonian fluids and viscoelastic fluids. Yet the viscoelastic/Newtonian interfacial effect has been scarcely investigated, especially for high-resolution particle separation. Here we report a microfluidic co-flow of Newtonian (water or PBS) and viscoelastic fluids (PEO) for the size-dependent separation of microparticles. The co-flow condition generates a stable viscoelastic/Newtonian interface, giving rise to the wall-directed elastic lift forces that compete with the center-directed lift forces, and efficiently hinders the migration of microparticles from the Newtonian to the viscoelastic fluid in a size-dependent manner. An almost complete separation of a binary mixture of 1 μm and 2 μm polystyrene particles is achieved by the co-flow of water and a very dilute PEO solution (100 ppm), whereas the sole use of water or PEO could not lead to an efficient separation. This co-flow microfluidic system is also applied for the separation of Staphylococcus aureus (1 μm) from platelets (2-3 μm) with >90% efficiencies and purities.

Advanced statistical analysis of Raman spectroscopic data for the identification of body fluid traces: semen and blood mixtures.

PubMed

Sikirzhytski, Vitali; Sikirzhytskaya, Aliaksandra; Lednev, Igor K

2012-10-10

Conventional confirmatory biochemical tests used in the forensic analysis of body fluid traces found at a crime scene are destructive and not universal. Recently, we reported on the application of near-infrared (NIR) Raman microspectroscopy for non-destructive confirmatory identification of pure blood, saliva, semen, vaginal fluid and sweat. Here we expand the method to include dry mixtures of semen and blood. A classification algorithm was developed for differentiating pure body fluids and their mixtures. The classification methodology is based on an effective combination of Support Vector Machine (SVM) regression (data selection) and SVM Discriminant Analysis of preprocessed experimental Raman spectra collected using an automatic mapping of the sample. This extensive cross-validation of the obtained results demonstrated that the detection limit of the minor contributor is as low as a few percent. The developed methodology can be further expanded to any binary mixture of complex solutions, including but not limited to mixtures of other body fluids. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Nonlinear hydrodynamic stability and transition; Proceedings of the IUTAM Symposium, Nice, France, Sept. 3-7, 1990

NASA Astrophysics Data System (ADS)

Theoretical and experimental research on nonlinear hydrodynamic stability and transition is presented. Bifurcations, amplitude equations, pattern in experiments, and shear flows are considered. Particular attention is given to bifurcations of plane viscous fluid flow and transition to turbulence, chaotic traveling wave covection, chaotic behavior of parametrically excited surface waves in square geometry, amplitude analysis of the Swift-Hohenberg equation, traveling wave convection in finite containers, focus instability in axisymmetric Rayleigh-Benard convection, scaling and pattern formation in flowing sand, dynamical behavior of instabilities in spherical gap flows, and nonlinear short-wavelength Taylor vortices. Also discussed are stability of a flow past a two-dimensional grid, inertia wave breakdown in a precessing fluid, flow-induced instabilities in directional solidification, structure and dynamical properties of convection in binary fluid mixtures, and instability competition for convecting superfluid mixtures.

Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, Pascal M.

1982-01-01

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carry-over through the turbine causes corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, P.M.

1979-12-27

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carryover through the turbine causing corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

Confocal Raman Microscopy for In-situ Measurement of Phospholipid-Water Partitioning into Model Phospholipid Bilayers within Individual Chromatographic Particles

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

Kitt, Jay P.; Bryce, David A.; Minteer, Shelley D.

The phospholipid-water partition coefficient is a commonly measured parameter that correlates with drug efficacy, small-molecule toxicity, and accumulation of molecules in biological systems in the environment. Despite the utility of this parameter, methods for measuring phospholipid-water partition coefficients are limited. This is due to the difficulty of making quantitative measurements in vesicle membranes or supported phospholipid bilayers, both of which are small-volume phases that challenge the sensitivity of many analytical techniques. In this paper, we employ in-situ confocal Raman microscopy to probe the partitioning of a model membrane-active compound, 2-(4-isobutylphenyl) propionic acid or ibuprofen, into both hybrid- and supported-phospholipid bilayersmore » deposited on the pore walls of individual chromatographic particles. The large surface-area-to-volume ratio of chromatographic silica allows interrogation of a significant lipid bilayer area within a very small volume. The local phospholipid concentration within a confocal probe volume inside the particle can be as high as 0.5 M, which overcomes the sensitivity limitations of making measurements in the limited membrane areas of single vesicles or planar supported bilayers. Quantitative determination of ibuprofen partitioning is achieved by using the phospholipid acyl-chains of the within-particle bilayer as an internal standard. This approach is tested for measurements of pH-dependent partitioning of ibuprofen into both hybrid-lipid and supported-lipid bilayers within silica particles, and the results are compared with octanol-water partitioning and with partitioning into individual optically-trapped phospholipid vesicle membranes. Finally and additionally, the impact of ibuprofen partitioning on bilayer structure is evaluated for both within-particle model membranes and compared with the structural impacts of partitioning into vesicle lipid bilayers.« less

Confocal Raman Microscopy for In-situ Measurement of Phospholipid-Water Partitioning into Model Phospholipid Bilayers within Individual Chromatographic Particles

DOE PAGES

Kitt, Jay P.; Bryce, David A.; Minteer, Shelley D.; ...

2018-05-14

The phospholipid-water partition coefficient is a commonly measured parameter that correlates with drug efficacy, small-molecule toxicity, and accumulation of molecules in biological systems in the environment. Despite the utility of this parameter, methods for measuring phospholipid-water partition coefficients are limited. This is due to the difficulty of making quantitative measurements in vesicle membranes or supported phospholipid bilayers, both of which are small-volume phases that challenge the sensitivity of many analytical techniques. In this paper, we employ in-situ confocal Raman microscopy to probe the partitioning of a model membrane-active compound, 2-(4-isobutylphenyl) propionic acid or ibuprofen, into both hybrid- and supported-phospholipid bilayersmore » deposited on the pore walls of individual chromatographic particles. The large surface-area-to-volume ratio of chromatographic silica allows interrogation of a significant lipid bilayer area within a very small volume. The local phospholipid concentration within a confocal probe volume inside the particle can be as high as 0.5 M, which overcomes the sensitivity limitations of making measurements in the limited membrane areas of single vesicles or planar supported bilayers. Quantitative determination of ibuprofen partitioning is achieved by using the phospholipid acyl-chains of the within-particle bilayer as an internal standard. This approach is tested for measurements of pH-dependent partitioning of ibuprofen into both hybrid-lipid and supported-lipid bilayers within silica particles, and the results are compared with octanol-water partitioning and with partitioning into individual optically-trapped phospholipid vesicle membranes. Finally and additionally, the impact of ibuprofen partitioning on bilayer structure is evaluated for both within-particle model membranes and compared with the structural impacts of partitioning into vesicle lipid bilayers.« less

Products of lipid peroxidation, but not membrane susceptibility to oxidative damage, are conserved in skeletal muscle following temperature acclimation.

PubMed

Grim, Jeffrey M; Semones, Molly C; Kuhn, Donald E; Kriska, Tamas; Keszler, Agnes; Crockett, Elizabeth L

2015-03-01

Changes in oxidative capacities and phospholipid remodeling accompany temperature acclimation in ectothermic animals. Both responses may alter redox status and membrane susceptibility to lipid peroxidation (LPO). We tested the hypothesis that phospholipid remodeling is sufficient to offset temperature-driven rates of LPO and, thus, membrane susceptibility to LPO is conserved. We also predicted that the content of LPO products is maintained over a range of physiological temperatures. To assess LPO susceptibility, rates of LPO were quantified with the fluorescent probe C11-BODIPY in mitochondria and sarcoplasmic reticulum from oxidative and glycolytic muscle of striped bass (Morone saxatilis) acclimated to 7°C and 25°C. We also measured phospholipid compositions, contents of LPO products [i.e., individual classes of phospholipid hydroperoxides (PLOOH)], and two membrane antioxidants. Despite phospholipid headgroup and acyl chain remodeling, these alterations do not counter the effect of temperature on LPO rates (i.e., LPO rates are generally not different among acclimation groups when normalized to phospholipid content and compared at a common temperature). Although absolute levels of PLOOH are higher in muscles from cold- than warm-acclimated fish, this difference is lost when PLOOH levels are normalized to total phospholipid. Contents of vitamin E and two homologs of ubiquinone are more than four times higher in mitochondria prepared from oxidative muscle of warm- than cold-acclimated fish. Collectively, our data demonstrate that although phospholipid remodeling does not provide a means for offsetting thermal effects on rates of LPO, differences in phospholipid quantity ensure a constant proportion of LPO products with temperature variation. Copyright © 2015 the American Physiological Society.

Confocal Raman Microscopy for in Situ Measurement of Phospholipid-Water Partitioning into Model Phospholipid Bilayers within Individual Chromatographic Particles.

PubMed

Kitt, Jay P; Bryce, David A; Minteer, Shelley D; Harris, Joel M

2018-06-05

The phospholipid-water partition coefficient is a commonly measured parameter that correlates with drug efficacy, small-molecule toxicity, and accumulation of molecules in biological systems in the environment. Despite the utility of this parameter, methods for measuring phospholipid-water partition coefficients are limited. This is due to the difficulty of making quantitative measurements in vesicle membranes or supported phospholipid bilayers, both of which are small-volume phases that challenge the sensitivity of many analytical techniques. In this work, we employ in situ confocal Raman microscopy to probe the partitioning of a model membrane-active compound, 2-(4-isobutylphenyl) propionic acid or ibuprofen, into both hybrid- and supported-phospholipid bilayers deposited on the pore walls of individual chromatographic particles. The large surface-area-to-volume ratio of chromatographic silica allows interrogation of a significant lipid bilayer area within a very small volume. The local phospholipid concentration within a confocal probe volume inside the particle can be as high as 0.5 M, which overcomes the sensitivity limitations of making measurements in the limited membrane areas of single vesicles or planar supported bilayers. Quantitative determination of ibuprofen partitioning is achieved by using the phospholipid acyl-chains of the within-particle bilayer as an internal standard. This approach is tested for measurements of pH-dependent partitioning of ibuprofen into both hybrid-lipid and supported-lipid bilayers within silica particles, and the results are compared with octanol-water partitioning and with partitioning into individual optically trapped phospholipid vesicle membranes. Additionally, the impact of ibuprofen partitioning on bilayer structure is evaluated for both within-particle model membranes and compared with the structural impacts of partitioning into vesicle lipid bilayers.

Evidence for the Phospholipid Sponge Effect as the Biocidal Mechanism in Surface-Bound Polyquaternary Ammonium Coatings with Variable Cross-Linking Density.

PubMed

Gao, Jing; White, Evan M; Liu, Qiaohong; Locklin, Jason

2017-03-01

Poly quaternary "-oniums" derived from polyethylenimine (PEI), poly(vinyl-N-alkylpyridinium), or chitosan belong to a class of cationic polymers that are efficient antimicrobial agents. When dissolved in solution, the positively charged polycations are able to displace the divalent cations of the cellular phospholipid bilayer and disrupt the ionic cross-links and structural integrity of the membrane. However, when immobilized to a surface where confinement limits diffusion, poly -oniums still show excellent antimicrobial activity, which implies a different biocidal mode of action. Recently, a proposed mechanism, named phospholipid sponge effect, suggested that surface-bound polycationic networks are capable of recruiting negatively charged phospholipids out of the bacterial cell membrane and sequestering them within the polymer matrix.1 However, there has been insufficient evidence to support this hypothesis. In this study, a surface-bound N,N-dodecyl methyl-co-N,N-methylbenzophenone methyl quaternary PEI (DMBQPEI) was prepared to verify the phospholipid sponge effect. By tuning the irradiation time, the cross-linking densities of surface-bound DMBQPEI films were mediated. The modulus of films was measured by PeakForce Quantitative Nanomechanical Mapping (QNM) to indicate the cross-linking density variation with increasing irradiation time. A negative correlation between the film cross-linking density and the absorption of a negatively charged phospholipid (DPhPG) was observed, but no such correlations were observed with a neutral phospholipid (DPhPC), which strongly supported the action of anionic phospholipid suction proposed in the lipid sponge effect. Moreover, the killing efficiency toward S. aureus and E. coli was inversely affected by the cross-linking density of the films, providing evidence for the phospholipid sponge effect. The relationship between killing efficiency and film cross-linking density is discussed.

Cell cycle progression is an essential regulatory component of phospholipid metabolism and membrane homeostasis

PubMed Central

Sanchez-Alvarez, Miguel; Zhang, Qifeng; Finger, Fabian; Wakelam, Michael J. O.; Bakal, Chris

2015-01-01

We show that phospholipid anabolism does not occur uniformly during the metazoan cell cycle. Transition to S-phase is required for optimal mobilization of lipid precursors, synthesis of specific phospholipid species and endoplasmic reticulum (ER) homeostasis. Average changes observed in whole-cell phospholipid composition, and total ER lipid content, upon stimulation of cell growth can be explained by the cell cycle distribution of the population. TORC1 promotes phospholipid anabolism by slowing S/G2 progression. The cell cycle stage-specific nature of lipid biogenesis is dependent on p53. We propose that coupling lipid metabolism to cell cycle progression is a means by which cells have evolved to coordinate proliferation with cell and organelle growth. PMID:26333836

Cell cycle progression is an essential regulatory component of phospholipid metabolism and membrane homeostasis.

PubMed

Sanchez-Alvarez, Miguel; Zhang, Qifeng; Finger, Fabian; Wakelam, Michael J O; Bakal, Chris

2015-09-01

We show that phospholipid anabolism does not occur uniformly during the metazoan cell cycle. Transition to S-phase is required for optimal mobilization of lipid precursors, synthesis of specific phospholipid species and endoplasmic reticulum (ER) homeostasis. Average changes observed in whole-cell phospholipid composition, and total ER lipid content, upon stimulation of cell growth can be explained by the cell cycle distribution of the population. TORC1 promotes phospholipid anabolism by slowing S/G2 progression. The cell cycle stage-specific nature of lipid biogenesis is dependent on p53. We propose that coupling lipid metabolism to cell cycle progression is a means by which cells have evolved to coordinate proliferation with cell and organelle growth. © 2015 The Authors.

Mitochondrial antibodies in primary biliary cirrhosis

PubMed Central

Berg, P. A.; Roitt, I. M.; Doniach, D.; Cooper, H. M.

1969-01-01

The effect on the mitochondrial antigen of different agents known to influence the integrity and structure of membranes has been studied using quantitative complement fixation with autoantibodies from the serum of a patient with primary biliary cirrhosis. The susceptibility to proteolytic enzymes suggests that the antigen is a protein. Activity depends upon an association with phospholipids. Addition of phospholipids prevents loss of antigen during artificial ageing of mitochondria at 37°. Activity is lost after treatment with phospholipases or solvents which extract phospholipids. Antigen is also destroyed by surface active agents which dissociate the link with phospholipid but those which weaken bonds between phospholipids and hydrophobic molecules yield fragments of antigen-containing membrane structures which, nonetheless, still react with the mitochondrial autoantibody. ImagesFIG. 2FIG. 4 PMID:5804537

Monte Carlo simulation of two-component bilayers: DMPC/DSPC mixtures.

PubMed Central

Sugár, I P; Thompson, T E; Biltonen, R L

1999-01-01

In this paper, we describe a relatively simple lattice model of a two-component, two-state phospholipid bilayer. Application of Monte Carlo methods to this model permits simulation of the observed excess heat capacity versus temperature curves of dimyristoylphosphatidylcholine (DMPC)/distearoylphosphatidylcholine (DSPC) mixtures as well as the lateral distributions of the components and properties related to these distributions. The analysis of the bilayer energy distribution functions reveals that the gel-fluid transition is a continuous transition for DMPC, DSPC, and all DMPC/DSPC mixtures. A comparison of the thermodynamic properties of DMPC/DSPC mixtures with the configurational properties shows that the temperatures characteristics of the configurational properties correlate well with the maxima in the excess heat capacity curves rather than with the onset and completion temperatures of the gel-fluid transition. In the gel-fluid coexistence region, we also found excellent agreement between the threshold temperatures at different system compositions detected in fluorescence recovery after photobleaching experiments and the temperatures at which the percolation probability of the gel clusters is 0.36. At every composition, the calculated mole fraction of gel state molecules at the fluorescence recovery after photobleaching threshold is 0.34 and, at the percolation threshold of gel clusters, it is 0.24. The percolation threshold mole fraction of gel or fluid lipid depends on the packing geometry of the molecules and the interchain interactions. However, it is independent of temperature, system composition, and state of the percolating cluster. PMID:10096905

Scaled Particle Theory for Multicomponent Hard Sphere Fluids Confined in Random Porous Media.

PubMed

Chen, W; Zhao, S L; Holovko, M; Chen, X S; Dong, W

2016-06-23

The formulation of scaled particle theory (SPT) is presented for a quite general model of fluids confined in a random porous media, i.e., a multicomponent hard sphere (HS) fluid in a multicomponent hard sphere or a multicomponent overlapping hard sphere (OHS) matrix. The analytical expressions for pressure, Helmholtz free energy, and chemical potential are derived. The thermodynamic consistency of the proposed theory is established. Moreover, we show that there is an isomorphism between the SPT for a multicomponent system and that for a one-component system. Results from grand canonical ensemble Monte Carlo simulations are also presented for a binary HS mixture in a one-component HS or a one-component OHS matrix. The accuracy of various variants derived from the basic SPT formulation is appraised against the simulation results. Scaled particle theory, initially formulated for a bulk HS fluid, has not only provided an analytical tool for calculating thermodynamic properties of HS fluid but also helped to gain very useful insight for elaborating other theoretical approaches such as the fundamental measure theory (FMT). We expect that the general SPT for multicomponent systems developed in this work can contribute to the study of confined fluids in a similar way.

Flow regimes in a T-mixer operating with a binary mixture

NASA Astrophysics Data System (ADS)

Camarri, Simone; Siconolfi, Lorenzo; Galletti, Chiara; Salvetti, Maria Vittoria

2015-11-01

Efficient mixing in small volumes is a key target in many processes. Among the most common micro-devices, passive T-shaped micro-mixers are widely used. For this reason, T-mixers have been studied in the literature and its working flow regimes have been identified. However, in most of the available theoretical studies it is assumed that only one working fluid is used, i.e. that the same fluid at the same thermodynamic conditions is entering the two inlet conduits of the mixer. Conversely, the practical use of micro-devices often involves the mixing of two different fluids or of the same fluid at different thermodynamic conditions. In this case flow regimes significantly different than those observed for a single working fluid may occur. The present work aims at investigating the flow regimes in a T-mixers when water at two different temperatures, i.e. having different viscosity and density, is entering the mixer. The effect of the temperature difference on the flow regimes in a 3D T-mixer is investigated by DNS and stability analysis and the results are compared to the case in which a single working fluid is employed.

Evaluating the Effect from Constructing Binary Geothermal Power Units Based on Spent Petroleum and Gas Boreholes in the South Regions of Russia

NASA Astrophysics Data System (ADS)

Alkhasov, A. B.; Alkhasova, D. A.

2018-02-01

The article substantiates the possibility of efficiently harnessing the geothermal resources available in the North Caucasian region through constructing binary geothermal power plants (GeoTPPs) using idle petroleum and gas wells. The power capacities of GeoTPPs are evaluated, and the basic characteristics of these power plants in case of constructing them in the promising areas are determined. The overall useful GeoTPP capacity equal to approximately 330 MW can be obtained from using the entire fleet of idle wells available in these areas. Diagrams confirming the possibility of reaching the optimal flowrate of geothermal heat carrier circulating in the geothermal circulation system loop are presented. This flowrate corresponds to a binary GeoTPP's maximal useful power output. The article shows, taking the Ternair geothermal field as an example, that it is inefficient to use medium-enthalpy thermal waters for generating energy at a binary GeoTPP involving reinjection of a spent heat carrier. It is shown that good prospects can be expected from applying a hybrid geothermal and combined-cycle technology, by means of which it is possible to use lowenthalpy (80-100°C) thermal waters for generating electricity in a highly efficient manner. In accordance with such technology, geothermal heat is used in the binary GeoTPP cycle for heating low-boiling working fluid to its evaporation temperature. The working fluid is evaporated and superheated by using the heat of exhaust gases from a gas turbine power unit. Owing to combined use of the thermal water heat potential and the heat of exhaust gases from a gas turbine power plant in a hybrid process system, it becomes possible to obtain high power performance indicators of hybrid geothermal and combined-cycle power plants. This conclusion is confirmed by the results from numerical evaluations carried out as applied to the Ternair geothermal field. With the fully harnessed resource potential of the Ternair field, the total capacity of hybrid geothermal and combined-cycle power plants may reach 60 MW, a level that would make it possible to relieve a significant part of energy, environmental, economic, and social problems faced by the city of Makhachkala.

Tyrosol-based liposomal behavior: Size, z-potential, TEM, QCM-D and fluorescence analysis

USDA-ARS?s Scientific Manuscript database

In our continued efforts to create biobased antioxidants for the food industry, we have used phospholipase D from Streptomyces sp. to create hydroxytyrosol and tyrosol phospholipids. Extrusion methods proved that both hydroxytyrosol phospholipids and tyrosol phospholipids each formed liposomes that ...

Salicylic acid induces vanillin synthesis through the phospholipid signaling pathway in Capsicum chinense cell cultures

PubMed Central

Rodas-Junco, Beatriz A; Cab-Guillen, Yahaira; Muñoz-Sanchez, J Armando; Vázquez-Flota, Felipe; Monforte-Gonzalez, Miriam; Hérnandez-Sotomayor, S M Teresa

2013-01-01

Signal transduction via phospholipids is mediated by phospholipases such as phospholipase C (PLC) and D (PLD), which catalyze hydrolysis of plasma membrane structural phospholipids. Phospholipid signaling is also involved in plant responses to phytohormones such as salicylic acid (SA). The relationships between phospholipid signaling, SA, and secondary metabolism are not fully understood. Using a Capsicum chinense cell suspension as a model, we evaluated whether phospholipid signaling modulates SA-induced vanillin production through the activation of phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthetic pathway. Salicylic acid was found to elicit PAL activity and consequently vanillin production, which was diminished or reversed upon exposure to the phosphoinositide-phospholipase C (PI-PLC) signaling inhibitors neomycin and U73122. Exposure to the phosphatidic acid inhibitor 1-butanol altered PLD activity and prevented SA-induced vanillin production. Our results suggest that PLC and PLD-generated secondary messengers may be modulating SA-induced vanillin production through the activation of key biosynthetic pathway enzymes.

Multiplexed biomimetic lipid membranes on graphene by dip-pen nanolithography

PubMed Central

Hirtz, Michael; Oikonomou, Antonios; Georgiou, Thanasis; Fuchs, Harald; Vijayaraghavan, Aravind

2013-01-01

The application of graphene in sensor devices depends on the ability to appropriately functionalize the pristine graphene. Here we show the direct writing of tailored phospholipid membranes on graphene using dip-pen nanolithography. Phospholipids exhibit higher mobility on graphene compared with the commonly used silicon dioxide substrate, leading to well-spread uniform membranes. Dip-pen nanolithography allows for multiplexed assembly of phospholipid membranes of different functionalities in close proximity to each other. The membranes are stable in aqueous environments and we observe electronic doping of graphene by charged phospholipids. On the basis of these results, we propose phospholipid membranes as a route for non-covalent immobilization of various functional groups on graphene for applications in biosensing and biocatalysis. As a proof of principle, we demonstrate the specific binding of streptavidin to biotin-functionalized membranes. The combination of atomic force microscopy and binding experiments yields a consistent model for the layer organization within phospholipid stacks on graphene. PMID:24107937

Extension of the BMCSL equation of state for hard spheres to the metastable disordered region: Application to the SAFT approach

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

Paricaud, P.

2015-07-28

A simple modification of the Boublík-Mansoori-Carnahan-Starling-Leland equation of state is proposed for an application to the metastable disordered region. The new model has a positive pole at the jamming limit and can accurately describe the molecular simulation data of pure hard in the stable fluid region and along the metastable branch. The new model has also been applied to binary mixtures hard spheres, and an excellent description of the fluid and metastable branches can be obtained by adjusting the jamming packing fraction. The new model for hard sphere mixtures can be used as the repulsive term of equations of statemore » for real fluids. In this case, the modified equations of state give very similar predictions of thermodynamic properties as the original models, and one can remove the multiple liquid density roots observed for some versions of the Statistical Associating Fluid Theory (SAFT) at low temperature without any modification of the dispersion term.« less

An exact solution for the Hawking effect in a dispersive fluid

NASA Astrophysics Data System (ADS)

Philbin, T. G.

2016-09-01

We consider the wave equation for sound in a moving fluid with a fourth-order anomalous dispersion relation. The velocity of the fluid is a linear function of position, giving two points in the flow where the fluid velocity matches the group velocity of low-frequency waves. We find the exact solution for wave propagation in the flow. The scattering shows amplification of classical waves, leading to spontaneous emission when the waves are quantized. In the dispersionless limit the system corresponds to a 1 +1 -dimensional black-hole or white-hole binary and there is a thermal spectrum of Hawking radiation from each horizon. Dispersion changes the scattering coefficients so that the quantum emission is no longer thermal. The scattering coefficients were previously obtained by Busch and Parentani in a study of dispersive fields in de Sitter space [Phys. Rev. D 86, 104033 (2012)]. Our results give further details of the wave propagation in this exactly solvable case, where our focus is on laboratory systems.

Many-Body Effects on the Thermodynamics of Fluids, Mixtures, and Nanoconfined Fluids.

PubMed

Desgranges, Caroline; Delhommelle, Jerome

2015-11-10

Using expanded Wang-Landau simulations, we show that taking into account the many-body interactions results in sharp changes in the grand-canonical partition functions of single-component systems, binary mixtures, and nanoconfined fluids. The many-body contribution, modeled with a 3-body Axilrod-Teller-Muto term, results in shifts toward higher chemical potentials of the phase transitions from low-density phases to high-density phases and accounts for deviations of more than, e.g., 20% of the value of the partition function for a single-component liquid. Using the statistical mechanics formalism, we analyze how this contribution has a strong impact on some properties (e.g., pressure, coexisting densities, and enthalpy) and a moderate impact on others (e.g., Gibbs or Helmholtz free energies). We also characterize the effect of the 3-body terms on adsorption isotherms and adsorption thermodynamic properties, thereby providing a full picture of the effect of the 3-body contribution on the thermodynamics of nanoconfined fluids.

Membrane Phospholipid Augments Cytochrome P4501a Enzymatic Activity by Modulating Structural Conformation during Detoxification of Xenobiotics

PubMed Central

Ghosh, Manik C.; Ray, Arun K.

2013-01-01

Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment. PMID:23469105

Optimization of the Electroformation of Giant Unilamellar Vesicles (GUVs) with Unsaturated Phospholipids.

PubMed

Breton, Marie; Amirkavei, Mooud; Mir, Lluis M

2015-10-01

Giant unilamellar vesicles (GUV) are widely used cell membrane models. GUVs have a cell-like diameter and contain the same phospholipids that constitute cell membranes. The most frequently used protocol to obtain these vesicles is termed electroformation, since key steps of this protocol consist in the application of an electric field to a phospholipid deposit. The potential oxidation of unsaturated phospholipids due to the application of an electric field has not yet been considered even though the presence of oxidized lipids in the membrane of GUVs could impact their permeability and their mechanical properties. Thanks to mass spectrometry analyses, we demonstrated that the electroformation technique can cause the oxidation of polyunsaturated phospholipids constituting the vesicles. Then, using flow cytometry, we showed that the amplitude and the duration of the electric field impact the number and the size of the vesicles. According to our results, the oxidation level of the phospholipids increases with their level of unsaturation as well as with the amplitude and the duration of the electric field. However, when the level of lipid oxidation exceeds 25 %, the diameter of the vesicles is decreased and when the level of lipid oxidation reaches 40 %, the vesicles burst or reorganize and their rate of production is reduced. In conclusion, the classical electroformation method should always be optimized, as a function of the phospholipid used, especially for producing giant liposomes of polyunsaturated phospholipids to be used as a cell membrane model.

Membrane phospholipid augments cytochrome P4501a enzymatic activity by modulating structural conformation during detoxification of xenobiotics.

PubMed

Ghosh, Manik C; Ray, Arun K

2013-01-01

Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD) in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment.

STABILITY AND STOICHIOMETRY OF BILAYER PHOSPHOLIPID-CHOLESTEROL COMPLEXES: RELATIONSHIP TO CELLULAR STEROL DISTRIBUTION AND HOMEOSTASIS&

PubMed Central

Lange, Yvonne; Ali Tabei, S. M.; Ye, Jin; Steck, Theodore L.

2013-01-01

Does cholesterol distribute among intracellular compartments by passive equilibration down its chemical gradient? If so, its distribution should reflect the relative cholesterol affinity of the constituent membrane phospholipids as well as their ability to form stoichiometric cholesterol complexes. We tested this hypothesis by analyzing the reactivity to cholesterol oxidase of large unilamellar vesicles (LUVs) containing biological phospholipids plus varied cholesterol. The rates of cholesterol oxidation differed among the various phospholipid environments by roughly four orders of magnitude. Furthermore, accessibility to the enzyme increased by orders of magnitude at cholesterol thresholds that suggested stoichiometries of association of 1:1, 2:3 or 1:2 cholesterol:phospholipid (mol:mol). Cholesterol accessibility above the threshold was still constrained by its particular phospholipid environment. One phospholipid, 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidylserine, exhibited no threshold. The analysis suggested values for the relative stabilities of the cholesterol-phospholipid complexes and for the fractions of bilayer cholesterol not in complexes at the threshold equivalence points; predictably, the saturated phosphorylcholine species had the lowest stoichiometries and the strongest affinities for cholesterol. These results were in general agreement with the equilibrium distribution of cholesterol between the various LUVs and methyl-β-cyclodextrin. In addition, the properties of the cholesterol in intact human red blood cells matched predictions made from LUVs of the corresponding composition. These results support a passive mechanism for the intracellular distribution of cholesterol that can provide a signal for its homeostatic regulation. PMID:24000774

Influence of Development and Dietary Phospholipid Content and Composition on Intestinal Transcriptome of Atlantic Salmon (Salmo salar)

PubMed Central

De Santis, Christian; Taylor, John F.; Martinez-Rubio, Laura; Boltana, Sebastian; Tocher, Douglas R.

2015-01-01

The inclusion of intact phospholipids in the diet is essential during larval development and can improve culture performance of many fish species. The effects of supplementation of dietary phospholipid from marine (krill) or plant (soy lecithin) sources were investigated in Atlantic salmon, Salmo salar. First feeding fry were fed diets containing either krill oil or soybean lecithin supplying phospholipid at 2.6%, 3.2%, 3.6% and 4.2% of diet. Fish were sampled at ~ 2.5 g (~1,990°day post fertilization, dpf) and ~10 g (2,850°dpf). By comparison of the intestinal transcriptome in specifically chosen contrasts, it was determined that by 2,850°dpf fish possessed a profile that resembled that of mature and differentiated intestinal cell types with a number of changes specific to glycerophospholipid metabolism. It was previously shown that intact phospholipids and particularly phosphatidylcholine are essential during larval development and that this requirement is associated with the inability of enterocytes in young fry to endogenously synthesize sufficient phospholipid for the efficient export of dietary lipid. In the immature phase (~1,990°dpf), the dietary phospholipid content as well as its class composition impacted on several biochemical and morphological parameters including growth, but these differences were not associated with differences in intestinal transcriptomes. The results of this study have made an important contribution to our understanding of the mechanisms associated with lipid transport and phospholipid biosynthesis in early life stages of fish. PMID:26488165

Altered phospholipid metabolism in schizophrenia: a phosphorus 31 nuclear magnetic resonance spectroscopy study.

PubMed

Weber-Fahr, Wolfgang; Englisch, Susanne; Esser, Andrea; Tunc-Skarka, Nuran; Meyer-Lindenberg, Andreas; Ende, Gabriele; Zink, Mathias

2013-12-30

Phospholipid (PL) metabolism is investigated by in vivo 31P magnetic resonance spectroscopy (MRS). Inconsistent alterations of phosphocholine (PC), phosphoethanolamine (PE), glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) have been described in schizophrenia, which might be overcome by specific editing techniques. The selective refocused insensitive nuclei-enhanced polarization transfer (RINEPT) technique was applied in a cross-sectional study involving 11 schizophrenia spectrum disorder patients (SZP) on stable antipsychotic monotherapy and 15 matched control subjects. Metabolite signals were found to be modulated by cerebrospinal fluid (CSF) content and gray matter/brain matter ratio. Corrected metabolite concentrations of PC, GPC and PE differed between patients and controls in both subcortical and cortical regions, whereas antipsychotic medication exerted only small effects. Significant correlations were found between the severity of clinical symptoms and the assessed signals. In particular, psychotic symptoms correlated with PC levels in the cerebral cortex, depression with PC levels in the cerebellum and executive functioning with GPC in the insular and temporal cortices. In conclusion, after controlling for age and tissue composition, this investigation revealed alterations of metabolite levels in SZP and correlations with clinical properties. RINEPT 31P MRS should also be applied to at-risk-mental-state patients as well as drug-naïve and chronically treated schizophrenic patients in order to enhance the understanding of longitudinal alterations of PL metabolism in schizophrenia. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Lung inflammatory and oxidative alterations after exogenous surfactant therapy fortified with budesonide in rabbit model of meconium aspiration syndrome.

PubMed

Mikolka, P; Kopincová, J; Košútová, P; Čierny, D; Čalkovská, A; Mokrá, D

2016-12-22

Meconium aspiration syndrome (MAS) triggers inflammatory and oxidative pathways which can inactivate both pulmonary surfactant and therapeutically given exogenous surfactant. Glucocorticoid budesonide added to exogenous surfactant can inhibit inflammation and thereby enhance treatment efficacy. Neonatal meconium (25 mg/ml, 4 ml/kg) was administered intratracheally (i.t.) to rabbits. When the MAS model was prepared, animals were treated with budesonide i.t. (Pulmicort, 0.25 mg/kg, M+B); with surfactant lung lavage (Curosurf®, 10 ml/kg, 5 mg phospholipids/ml, M+S) followed by undiluted Curosurf® i.t. (100 mg phospholipids/kg); with combination of budesonide and surfactant (M+S+B); or were untreated (M); or served as controls with saline i.t. instead of meconium (C). Animals were oxygen-ventilated for additional 5 h. Cell counts in the blood and bronchoalveolar lavage fluid (BAL), lung edema formation (wet/dry weight ratio), oxidative damage of lipids/ proteins and inflammatory expression profiles (IL-2, IL-6, IL-13, TNF-alpha) in the lung homogenate and plasma were determined. Combined surfactant+budesonide therapy was the most effective in reduction of neutrophil counts in BAL, oxidative damage, levels and mRNA expression of cytokines in the lung, and lung edema formation compared to untreated animals. Curosurf fortified with budesonide mitigated lung inflammation and oxidative modifications what indicate the perspectives of this treatment combination for MAS therapy.

Solubility enhancement of BCS Class II drug by solid phospholipid dispersions: Spray drying versus freeze-drying.

PubMed

Fong, Sophia Yui Kau; Ibisogly, Asiye; Bauer-Brandl, Annette

2015-12-30

The poor aqueous solubility of BCS Class II drugs represents a major challenge for oral dosage form development. Using celecoxib (CXB) as model drug, the current study adopted a novel solid phospholipid nanoparticle (SPLN) approach and compared the effect of two commonly used industrial manufacturing methods, spray- and freeze-drying, on the solubility and dissolution enhancement of CXB. CXB was formulated with Phospholipoid E80 (PL) and trehalose at different CXB:PL:trehalose ratios, of which 1:10:16 was the optimal formulation. Spherical amorphous SPLNs with average diameters <1μm were produced by spray-drying; while amorphous 'matrix'-like structures of solid PL dispersion with larger particle sizes were prepared by freeze-drying. Formulations from both methods significantly enhanced the dissolution rates, apparent solubility, and molecularly dissolved concentration of CXB in phosphate buffer (PBS, pH 6.5) and in biorelevant fasted state simulated intestinal fluid (FaSSIF, pH 6.5) (p<0.05). While similar dissolution rates were found, the spray-dried SPLNs had a larger enhancement in apparent solubility (29- to 132-fold) as well as molecular solubility (18-fold) of CXB at equilibrium (p<0.05). The strong capability of the spray-dried SPLNs to attain 'true' supersaturation state makes them a promising approach for bioavailability enhancement of poorly soluble drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

Surfactants: their critical role in enhancing drug delivery to the lungs.

PubMed

Morales, Javier O; Peters, Jay I; Williams, Robert O

2011-05-01

For local lung conditions and diseases, pulmonary drug delivery has been widely used for more than 50 years now. A more recent trend involves the pulmonary route as a systemic drug-delivery target. Advantages such as avoidance of the gastrointestinal environment, different enzyme content compared with the intestine, and avoidance of first-pass metabolism make the lung an alternative route for the systemic delivery of actives. However, the lung offers barriers to absorption such as a surfactant layer, epithelial surface lining fluid, epithelial monolayer, interstitium and basement membrane, and capillary endothelium. Many delivery strategies have been developed in order to overcome these limitations. The use of surfactants is one of these approaches and their role in enhancing pulmonary drug delivery is reviewed in this article. A systematic review of the literature relating to the effect of surfactants on formulations for pulmonary delivery was conducted. Specifically, research reporting enhancement of in vivo performance was focused on. The effect of the addition of surfactants such as phospholipids, bile salts, non-ionic, fatty acids, and liposomes as phospholipid-containing carriers on the enhancement of therapeutic outcomes of drugs for pulmonary delivery was compiled. The main use attributed to surfactants in pulmonary drug delivery is as absorption enhancers by mechanisms of action not yet fully understood. Furthermore, surfactants have been used to improve the delivery of inhaled drugs in various additional strategies discussed herein.

Critical Insights into Cardiovascular Disease from Basic Research on the Oxidation of Phospholipids: the γ-Hydroxyalkenal Phospholipid Hypothesis

PubMed Central

Salomon, Robert G.; Gu, Xiaodong

2011-01-01

Basic research, exploring the hypothesis that γ-hydroxyalkenal phospholipids are generated in vivo through oxidative cleavage of polyunsaturated phospholipids, is delivering a bonanza of molecular mechanistic insights into cardiovascular disease. Rather than targeting a specific pathology, these studies were predicated on the presumption that a fundamental understanding of lipid oxidation is likely to provide critical insights into disease processes. This investigational approach – from the chemistry of biomolecules to disease phenotype – that complements the more common opposite paradigm, is proving remarkably productive. PMID:21870852

Direct investigation of the vectorization properties of amphiphilic cyclodextrins in phospholipid films.

PubMed

Javierre, Isabelle; Nedyalkov, Mickael; Petkova, Vera; Benattar, Jean Jacques; Weisse, Sandrine; Auzély-Velty, Rachel; Djedaïni-Pilard, Florence; Perly, Bruno

2002-10-01

Recently, new cyclodextrin derivatives were synthesized and shown to exhibit strong amphiphilic properties. In this paper, we study the action of these new amphiphilic cyclodextrins on phospholipids. Mixed phospholipid/cyclodextrin derivative films were prepared and studied using X-ray reflectivity for various phospholipid/cyclodextrin ratios. A molar ratio of 3 provides a highly stable film the molecular structure of which has been investigated in detail. The cholesterol tail of the cyclodextrin molecule was found to be anchored into the phospholipid film. The cyclodextrin moieties exposed to the aqueous medium are prone to the addition of the guest molecule Dosulepin, making them of high interest for drug delivery. For this purpose and as an example of a potential application, this cyclodextrin molecular carrier property is also addressed to this complex film architecture.

The interaction of insulin with phospholipids

PubMed Central

Perry, M. C.; Tampion, W.; Lucy, J. A.

1971-01-01

1. A simple two-phase chloroform–aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of 125I-labelled insulin in this system was determined after incubation at 37°C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized 125I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin–phospholipid or insulin–amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin–phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [14C]glucose between the two phases as a monitor of phospholipid–insulin interactions. The ability of phospholipids to solubilize [14C]glucose in chloroform increased in the order phosphatidylcholine

[Determination of residual acetone in soybean phospholipids by headspace gas chromatography].

PubMed

Shen, S C; Zhang, W B; Cui, L X

2000-11-01

Soybean phospholipids have many functions and alimentary actions. In our country, powder soybean phospholipids are generally got by extraction with acetone, followed by vacuum drying. There may be some residual acetone present in the soybean phospholipids, which is harmful to health. So, we must know residual acetone content in the soybean phospholipids. However we have not found a method to determine the residual acetone in the soybean phospholipids. In this paper, headspace GC was used to determine residual acetone in powder soybean phospholipids. The headspace bottle was glass with a volume of 15 milliliters. Certain amounts of water, ammonium sulfate, and sample were added into the bottle. The mixture was made into a brei as soon as possible. The bottle was put into a water bath at 40 degrees C for an hour. The GC column was a 2 m x 3 mm i.d. stainless steel tube packed with GDX-103 stationary phase. Temperatures of both injector and detector were kept at 120 degrees C. Column temperature was 160 degrees C. Injection volume was 1 mL. External standard method was used for quantitation. The RSD was 1.2%. The recoveries in the range of 25.0 micrograms/g-100 micrograms/g were 98.4%-104%.

Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in animal depression model.

PubMed

Depciuch, J; Sowa-Kucma, M; Nowak, G; Papp, M; Gruca, P; Misztak, P; Parlinska-Wojtan, M

2017-04-05

Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression. Copyright © 2016 Elsevier B.V. All rights reserved.

Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in animal depression model

NASA Astrophysics Data System (ADS)

Depciuch, J.; Sowa-Kucma, M.; Nowak, G.; Papp, M.; Gruca, P.; Misztak, P.; Parlinska-Wojtan, M.

2017-04-01

Depression becomes nowadays a high mortality civilization disease with one of the major causes being chronic stress. Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of rats subjected to chronic mild stress, which is a common animal depression model. Moreover, the efficiency of the imipramine treatment was evaluated. It was found that chronic mild stress not only damages the structure of the phospholipids and proteins, but also decreases their level in the blood serum. A 5 weeks imipramine treatment did increase slightly the quantity of proteins, leaving the damaged phospholipids unchanged. Structural information from phospholipids and proteins was obtained by UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of stressed rats was normalized after imipramine therapy, while the impaired structure of phospholipids remained unaffected. These findings strongly suggest that the depression factor, which is chronic mild stress, may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression.

Modelling droplet collision outcomes for different substances and viscosities

NASA Astrophysics Data System (ADS)

Sommerfeld, Martin; Kuschel, Matthias

2016-12-01

The main objective of the present study is the derivation of models describing the outcome of binary droplet collisions for a wide range of dynamic viscosities in the well-known collision maps (i.e. normalised lateral droplet displacement at collision, called impact parameter, versus collision Weber number). Previous studies by Kuschel and Sommerfeld (Exp Fluids 54:1440, 2013) for different solution droplets having a range of solids contents and hence dynamic viscosities (here between 1 and 60 mPa s) revealed that the locations of the triple point (i.e. coincidence of bouncing, stretching separation and coalescence) and the critical Weber number (i.e. condition for the transition from coalescence to separation for head-on collisions) show a clear dependence on dynamic viscosity. In order to extend these findings also to pure liquids and to provide a broader data basis for modelling the viscosity effect, additional binary collision experiments were conducted for different alcohols (viscosity range 1.2-15.9 mPa s) and the FVA1 reference oil at different temperatures (viscosity range 3.0-28.2 mPa s). The droplet size for the series of alcohols was around 365 and 385 µm for the FVA1 reference oil, in each case with fixed diameter ratio at Δ= 1. The relative velocity between the droplets was varied in the range 0.5-3.5 m/s, yielding maximum Weber numbers of around 180. Individual binary droplet collisions with defined conditions were generated by two droplet chains each produced by vibrating orifice droplet generators. For recording droplet motion and the binary collision process with good spatial and temporal resolution high-speed shadow imaging was employed. The results for varied relative velocity and impact angle were assembled in impact parameter-Weber number maps. With increasing dynamic viscosity a characteristic displacement of the regimes for the different collision scenarios was also observed for pure liquids similar to that observed for solutions. This displacement could be described on a physical basis using the similarity number and structure parameter K which was obtained through flow process evaluation and optimal proportioning of momentum and energy by Naue and Bärwolff (Transportprozesse in Fluiden. Deutscher Verlag für Grundstoffindustrie GmbH, Leipzig 1992). Two correlations including the structure parameter K could be derived which describe the location of the triple point and the critical We number. All fluids considered, pure liquids and solutions, are very well fitted by these physically based correlations. The boundary model of Jiang et al. (J Fluid Mech 234:171-190, 1992) for distinguishing between coalescence and stretching separation could be adapted to go through the triple point by the two involved model parameters C a and C b, which were correlated with the relaxation velocity u_{{relax}} = {σ/μ}. Based on the predicted critical Weber number, denoting the onset of reflexive separation, the model of Ashgriz and Poo (J Fluid Mech 221:183-204, 1990) was adapted accordingly. The proper performance of the new generalised models was validated based on the present and previous measurements for a wide range of dynamic viscosities (i.e. 1-60 mPa s) and liquid properties. Although the model for the lower boundary of bouncing (Estrade et al. in J Heat Fluid Flow 20:486-491, 1999) could be adapted through the shape factor, it was found not suitable for the entire range of Weber numbers and viscosities.

Three-dimensional convection of binary mixtures in porous media.

PubMed

Umla, R; Augustin, M; Huke, B; Lücke, M

2011-11-01

We investigate convection patterns of binary mixtures with a positive separation ratio in porous media. As setup, we choose the Rayleigh-Bénard system of a fluid layer heated from below. Results are obtained by a multimode Galerkin method. Using this method, we compute square and crossroll patterns, and we analyze their structural, bifurcation, and stability properties. Evidence is provided that, for a strong enough Soret effect, both structures exist as stable forms of convection. Some of their properties are found to be similar to square and crossroll convection in the system without porous medium. However, there are also qualitative differences. For example, squares can be destabilized by oscillatory perturbations with square symmetry in porous media, and their velocity isolines are deformed in the so-called Soret regime.

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.

Solid-state flurbiprofen and methyl-β-cyclodextrin inclusion complexes prepared using a single-step, organic solvent-free supercritical fluid process.

PubMed

Rudrangi, Shashi Ravi Suman; Kaialy, Waseem; Ghori, Muhammad U; Trivedi, Vivek; Snowden, Martin J; Alexander, Bruce David

2016-07-01

The aim of this study was to enhance the apparent solubility and dissolution properties of flurbiprofen through inclusion complexation with cyclodextrins. Especially, the efficacy of supercritical fluid technology as a preparative technique for the preparation of flurbiprofen-methyl-β-cyclodextrin inclusion complexes was evaluated. The complexes were prepared by supercritical carbon dioxide processing and were evaluated by solubility, differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy, practical yield, drug content estimation and in vitro dissolution studies. Computational molecular docking studies were conducted to study the possibility of molecular arrangement of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin. The studies support the formation of stable molecular inclusion complexes between the drug and cyclodextrin in a 1:1 stoichiometry. In vitro dissolution studies showed that the dissolution properties of flurbiprofen were significantly enhanced by the binary mixtures prepared by supercritical carbon dioxide processing. The amount of flurbiprofen dissolved into solution alone was very low with 1.11±0.09% dissolving at the end of 60min, while the binary mixtures processed by supercritical carbon dioxide at 45°C and 200bar released 99.39±2.34% of the drug at the end of 30min. All the binary mixtures processed by supercritical carbon dioxide at 45°C exhibited a drug release of more than 80% within the first 10min irrespective of the pressure employed. The study demonstrated the single step, organic solvent-free supercritical carbon dioxide process as a promising approach for the preparation of inclusion complexes between flurbiprofen and methyl-β-cyclodextrin in solid-state. Copyright © 2016 Elsevier B.V. All rights reserved.

A diagrammatic formulation of the kinetic theory of fluctuations in equilibrium classical fluids. VI. Binary collision approximations for the memory function for self-correlation functions

NASA Astrophysics Data System (ADS)

Noah-Vanhoucke, Joyce E.; Andersen, Hans C.

2007-08-01

We use computer simulation results for a dense Lennard-Jones fluid for a range of temperatures to test the accuracy of various binary collision approximations for the memory function for density fluctuations in liquids. The approximations tested include the moderate density approximation of the generalized Boltzmann-Enskog memory function (MGBE) of Mazenko and Yip [Statistical Mechanics. Part B. Time-Dependent Processes, edited by B. J. Berne (Plenum, New York, 1977)], the binary collision approximation (BCA) and the short time approximation (STA) of Ranganathan and Andersen [J. Chem. Phys. 121, 1243 (2004); J. Phys. Chem. 109, 21437 (2005)] and various other approximations we derived by using diagrammatic methods. The tests are of two types. The first is a comparison of the correlation functions predicted by each approximate memory function with the simulation results, especially for the self-longitudinal current correlation (SLCC) function. The second is a direct comparison of each approximate memory function with a memory function numerically extracted from the correlation function data. The MGBE memory function is accurate at short times but decays to zero too slowly and gives a poor description of the correlation function at intermediate times. The BCA is exact at zero time, but it predicts a correlation function that diverges at long times. The STA gives a reasonable description of the SLCC but does not predict the correct temperature dependence of the negative dip in the function that is associated with caging at low temperatures. None of the other binary collision approximations is a systematic improvement on the STA. The extracted memory functions have a rapidly decaying short time part, much like the STA, and a much smaller, more slowly decaying part of the type predicted by a mode coupling theory. Theories that use mode coupling commonly include a binary collision term in the memory function but do not discuss in detail the nature of that term. It is clear from the present work that the short time part of the memory function has a behavior associated with brief binary repulsive collisions, such as those described by the STA. Collisions that include attractive as well as repulsive interactions, such as those of the MGBE, have a much longer duration, and theories that include them have memory functions that decay to zero much too slowly to provide a good first approximation of the correlation function. This leads us to speculate that the memory function for density fluctuations can be usefully regarded as a sum of at least three parts: a contribution from repulsive binary collisions (the STA or something similar to it), another short time part that is related to all the other interactions (but whose nature is not understood), and a longer time slowly decaying part that describes caging (of the type predicted by the mode coupling theory).

Composition and metabolism of phospholipids in Octopus vulgaris and Sepia officinalis hatchlings.

PubMed

Reis, Diana B; Acosta, Nieves G; Almansa, Eduardo; Tocher, Douglas R; Andrade, José P; Sykes, António V; Rodríguez, Covadonga

2016-10-01

The objective of the present study was to characterise the fatty acid (FA) profiles of the major phospholipids, of Octopus vulgaris and Sepia officinalis hatchlings, namely phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE); and to evaluate the capability of both cephalopod species on dietary phospholipid remodelling. Thus, O. vulgaris and S. officinalis hatchlings were in vivo incubated with 0.3μM of L-∝-1-palmitoyl-2-[1-(14)C]arachidonyl-PC or L-∝-1-palmitoyl-2-[1-(14)C]arachidonyl-PE. Octopus and cuttlefish hatchlings phospholipids showed a characteristic FA profiles with PC presenting high contents of 16:0 and 22:6n-3 (DHA); PS having high 18:0, DHA and 20:5n-3 (EPA); PI a high content of saturated FA; and PE showing high contents of DHA and EPA. Interestingly, the highest content of 20:4n-6 (ARA) was found in PE rather than PI. Irrespective of the phospholipid in which [1-(14)C]ARA was initially bound (either PC or PE), the esterification pattern of [1-(14)C]ARA in octopus lipids was similar to that found in their tissues with high esterification of this FA into PE. In contrast, in cuttlefish hatchlings [1-(14)C]ARA was mainly recovered in the same phospholipid that was provided. These results showed a characteristic FA profiles in the major phospholipids of the two species, as well as a contrasting capability to remodel dietary phospholipids, which may suggest a difference in phospholipase activities. Copyright © 2016 Elsevier Inc. All rights reserved.

Instability Mechanisms of Water-in-Oil Nanoemulsions with Phospholipids: Temporal and Morphological Structures.

PubMed

Sommerling, Jan-Hendrik; de Matos, Maria B C; Hildebrandt, Ellen; Dessy, Alberto; Kok, Robbert Jan; Nirschl, Hermann; Leneweit, Gero

2018-01-16

Many food preparations, pharmaceuticals, and cosmetics use water-in-oil (W/O) emulsions stabilized by phospholipids. Moreover, recent technological developments try to produce liposomes or lipid coated capsules from W/O emulsions, but are faced with colloidal instabilities. To explore these instability mechanisms, emulsification by sonication was applied in three cycles, and the sample stability was studied for 3 h after each cycle. Clearly identifiable temporal structures of instability provide evidence about the emulsion morphology: an initial regime of about 10 min is shown to be governed by coalescence after which Ostwald ripening dominates. Transport via molecular diffusion in Ostwald ripening is commonly based on the mutual solubility of the two phases and is therefore prohibited in emulsions composed of immiscible phases. However, in the case of water in oil emulsified by phospholipids, these form water-loaded reverse micelles in oil, which enable Ostwald ripening despite the low solubility of water in oil, as is shown for squalene. As is proved for the phospholipid dipalmitoylphosphatidylcholine (DPPC), concentrations below the critical aggregation concentration (CAC) form monolayers at the interfaces and smaller droplet sizes. In contrast, phospholipid concentrations above the CAC create complex multilayers at the interface with larger droplet sizes. The key factors for stable W/O emulsions in classical or innovative applications are first, the minimization of the phospholipids' capacity to form reversed micelles, and second, the adaption of the initial phospholipid concentration to the water content to enable an optimized coverage of phospholipids at the interfaces for the intended drop size.

Role of phosphatidylserine in phospholipid flippase-mediated vesicle transport in Saccharomyces cerevisiae.

PubMed

Takeda, Miyoko; Yamagami, Kanako; Tanaka, Kazuma

2014-03-01

Phospholipid flippases translocate phospholipids from the exoplasmic to the cytoplasmic leaflet of cell membranes to generate and maintain phospholipid asymmetry. The genome of budding yeast encodes four heteromeric flippases (Drs2p, Dnf1p, Dnf2p, and Dnf3p), which associate with the Cdc50 family noncatalytic subunit, and one monomeric flippase Neo1p. Flippases have been implicated in the formation of transport vesicles, but the underlying mechanisms are largely unknown. We show here that overexpression of the phosphatidylserine synthase gene CHO1 suppresses defects in the endocytic recycling pathway in flippase mutants. This suppression seems to be mediated by increased cellular phosphatidylserine. Two models can be envisioned for the suppression mechanism: (i) phosphatidylserine in the cytoplasmic leaflet recruits proteins for vesicle formation with its negative charge, and (ii) phosphatidylserine flipping to the cytoplasmic leaflet induces membrane curvature that supports vesicle formation. In a mutant depleted for flippases, a phosphatidylserine probe GFP-Lact-C2 was still localized to endosomal membranes, suggesting that the mere presence of phosphatidylserine in the cytoplasmic leaflet is not enough for vesicle formation. The CHO1 overexpression did not suppress the growth defect in a mutant depleted or mutated for all flippases, suggesting that the suppression was dependent on flippase-mediated phospholipid flipping. Endocytic recycling was not blocked in a mutant lacking phosphatidylserine or depleted in phosphatidylethanolamine, suggesting that a specific phospholipid is not required for vesicle formation. These results suggest that flippase-dependent vesicle formation is mediated by phospholipid flipping, not by flipped phospholipids.

Wetting phenomenon in the liquid-vapor phase coexistence of a partially miscible Lennard-Jones binary mixture

NASA Astrophysics Data System (ADS)

Ramírez-Santiago, Guillermo; Díaz-Herrera, Enrique; Moreno Razo, José A.

2004-03-01

We have carried out extensive equilibrium MD simulations to study wetting phenomena in the liquid-vapor phase coexistence of a partially miscible binary LJ mixture. We find that in the temperature range 0.60 ≤ T^* < 0.80, the system separates forming a liquid A-liquid B interface in coexistence with the vapor phase. At higher temperatures, 0.80 ≤ T^* < 1.25 the liquid phases are wet by the vapor phase. By studying the behavior of the surface tension as a function of temperature we estimate the wetting transition temperature (WTT) to be T^*_w≃ 0.80. The adsorption of molecules at the liquid-liquid interface shows a discontinuity at about T^*≃ 0.79 suggesting that the wetting transition is a first order phase transition. These results are in agreement with some experiments carried out in fluid binary mixtures. In addition, we estimated the consolute temperature to be T^* _cons≃ 1.25. The calculated phase diagram of the mixture suggest the existence of a tricritical point.

Diffuse interface method for a compressible binary fluid.

PubMed

Liu, Jiewei; Amberg, Gustav; Do-Quang, Minh

2016-01-01

Multicomponent, multiphase, compressible flows are very important in real life, as well as in scientific research, while their modeling is in an early stage. In this paper, we propose a diffuse interface model for compressible binary mixtures, based on the balance of mass, momentum, energy, and the second law of thermodynamics. We show both analytically and numerically that this model is able to describe the phase equilibrium for a real binary mixture (CO_{2} + ethanol is considered in this paper) very well by adjusting the parameter which measures the attraction force between molecules of the two components in the model. We also show that the calculated surface tension of the CO_{2} + ethanol mixture at different concentrations match measurements in the literature when the mixing capillary coefficient is taken to be the geometric mean of the capillary coefficient of each component. Three different cases of two droplets in a shear flow, with the same or different concentration, are simulated, showing that the higher concentration of CO_{2} the smaller the surface tension and the easier the drop deforms.

Microlayered flow structure around an acoustically levitated droplet under a phase-change process.

PubMed

Hasegawa, Koji; Abe, Yutaka; Goda, Atsushi

2016-01-01

The acoustic levitation method (ALM) has found extensive applications in the fields of materials science, analytical chemistry, and biomedicine. This paper describes an experimental investigation of a levitated droplet in a 19.4-kHz single-axis acoustic levitator. We used water, ethanol, water/ethanol mixture, and hexane as test samples to investigate the effect of saturated vapor pressure on the flow field and evaporation process using a high-speed camera. In the case of ethanol, water/ethanol mixtures with initial ethanol fractions of 50 and 70 wt%, and hexane droplets, microlayered toroidal vortexes are generated in the vicinity of the droplet interface. Experimental results indicate the presence of two stages in the evaporation process of ethanol and binary mixture droplets for ethanol content >10%. The internal and external flow fields of the acoustically levitated droplet of pure and binary mixtures are clearly observed. The binary mixture of the levitated droplet shows the interaction between the configurations of the internal and external flow fields of the droplet and the concentration of the volatile fluid. Our findings can contribute to the further development of existing theoretical prediction.

Two-component fluid membranes near repulsive walls: Linearized hydrodynamics of equilibrium and nonequilibrium states.

PubMed

Sankararaman, Sumithra; Menon, Gautam I; Sunil Kumar, P B

2002-09-01

We study the linearized hydrodynamics of a two-component fluid membrane near a repulsive wall, using a model that incorporates curvature-concentration coupling as well as hydrodynamic interactions. This model is a simplified version of a recently proposed one [J.-B. Manneville et al., Phys. Rev. E 64, 021908 (2001)] for nonequilibrium force centers embedded in fluid membranes, such as light-activated bacteriorhodopsin pumps incorporated in phospholipid egg phosphatidyl choline (EPC) bilayers. The pump-membrane system is modeled as an impermeable, two-component bilayer fluid membrane in the presence of an ambient solvent, in which one component, representing active pumps, is described in terms of force dipoles displaced with respect to the bilayer midpoint. We first discuss the case in which such pumps are rendered inactive, computing the mode structure in the bulk as well as the modification of hydrodynamic properties by the presence of a nearby wall. These results should apply, more generally, to equilibrium fluid membranes comprised of two components, in which the effects of curvature-concentration coupling are significant, above the threshold for phase separation. We then discuss the fluctuations and mode structure in the steady state of active two-component membranes near a repulsive wall. We find that proximity to the wall smoothens membrane height fluctuations in the stable regime, resulting in a logarithmic scaling of the roughness even for initially tensionless membranes. This explicitly nonequilibrium result is a consequence of the incorporation of curvature-concentration coupling in our hydrodynamic treatment. This result also indicates that earlier scaling arguments which obtained an increase in the roughness of active membranes near repulsive walls upon neglecting the role played by such couplings may need to be reevaluated.

[Peculiarities of the phospholipid and fatty acid composition of erythrocyte plasma membranes of the Black Sea fish].

PubMed

Silkin, Iu A; Silkina, E N; Zabelinskiĭ, S A

2012-01-01

The phospholipid and the fatty acid composition of the main phospholipids families of erythrocyte plasma membranes was studied in two species of cartilaginous fish: the common thrasher (Raja clavata L.) and the common stingray (Dasyatis pastinaca) and three bony fish species: the scorpion fish (Scorpaena porcus L.), the smarida (Spicara flexuosa Raf.), and the horse mackerel (Trachurus mediterraneus ponticus Aleev). It was shown that in the studied fish, 70.0-80.0 % of all membrane phospholipids were composed of phosphatidylcholine and phosphatidylethanolamine. Phosphatidylserine, monophosphoinositide, and sphingomyelin were minor components whose content in the erythrocyte membrane fluctuated from 3.0 % to 13.0 %. The fatty acid phospholipids composition was represented by a large specter of acids. From saturated acids, basic for plasma membranes are palmitic (C16: 0) and stearic (C18: 0) acids. From unsaturated acids, the larger part belong to mono-, tetra-, penta-, and hexaenoic acids in fish phospholipids. The calculation of the double bond index and of the unsaturation coefficient showed difference in the deformation ability of erythrocyte membranes of the studied fish.

Phospholipid dynamics in graphene of different topologies: predictive modeling

NASA Astrophysics Data System (ADS)

Glukhova, O. E.; Slepchenkov, M. M.

2017-02-01

The subject of our scientific interest is the dynamics of the phospholipid molecules into a corrugated graphene sheet. According to our assumption by changing the topology of graphene properly it is possible to find the ways for management of the selective localization of phospholipid molecules to form the desired configuration of these structures. We considered DPPC (dipalmitoylphosphatidylcholine) phospholipids, which are the part of cell membranes and lipoproteins. We investigated the behavior of the phospholipids on the graphene sheet consisting of 1710 atoms with the size of 6.9 nm along the zigzag edge and 6.25 nm along the armchair edge. The numerical experiment was carried out using the original AMBER/AIREBO hybrid method with Lennard-Jones potential to describe the interaction between unbound atoms of different structures. The temperature was maintained at 300 K during the numerical experiment. All numerical experiments were performed using KVAZAR software system. We considered several cases of corrugated graphene with different width and dept of the corrugation. Special attention in our work was paid to the orientation of the phospholipids in the plane of graphene sheet.

Measurement of Ether Phospholipids in Human Plasma with HPLC-ELSD and LC/ESI-MS After Hydrolysis of Plasma with Phospholipase A1.

PubMed

Mawatari, Shiro; Hazeyama, Seira; Fujino, Takehiko

2016-08-01

Ethanolamine ether phospholipid (eEtnGpl) and choline ether phospholipid (eChoGpl) are present in human plasma or serum, but the relative concentration of the ether phospholipids in plasma is very low as compared to those in other tissues. Nowadays, measurement of ether phospholipids in plasma depends on tandem mass spectrometry (LC/MS/MS), but a system for LC/MS/MS is generally too expensive for usual clinical laboratories. Treatment of plasma with phospholipase A1 (PLA1) causes complete hydrolysis of diacylphospholipids, but ether phospholipids remain intact. After the treatment of plasma with PLA1, both eEtnGpl and eChoGpl are detected as independent peaks by high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD). The same sample used for HPLC-ELSD can be applied to detect eEtnGpl and eChoGpl with electrospray ionization mass spectrometry. Presence of alkylacylphospholipids in both eChoGpl and eEtnGpl in human plasma was indicated by sequential hydrolysis of plasma with PLA1 and hydrochloric acid.

Response of melanoma tumor phospholipid metabolism to chloroethyle nitrosourea: a high resolution proton NMR spectroscopy study.

PubMed

Morvan, Daniel; Demidem, Aïcha; Madelmont, Jean-Claude

2003-07-01

Phospholipid metabolism is tightly involved in tumor growth regulation and tumor cell survival. The response of phospholipid metabolism to chloroethyle nitrosourea treatment is investigated in a murine B16 melanoma model. Measurements of phospholipid derivatives are performed on intact tumor tissue samples using one- and two-dimensional proton NMR spectroscopy. During the tumor growth inhibition phase under treatment, tumors overexpress phosphocholine, phosphoethanolamine, glycerophosphocholine and glycerophosphoethanolamine, whereas phosphatidylcholine and phosphatidylethanolamine levels are maintained to control levels. During re-growth, which remained quantitatively much below control growth, chloroethyle nitrosourea-treated melanoma tumors overexpress phosphocholine and phosphoethanolamine only. In treated melanoma, phosphatidylcholine levels show an inverse relationship with tumor growth rates. In conclusion, chloroethyle nitrosourea-treated melanoma tumors maintain their phosphatidylcholine levels and exhibit transformed phospholipid metabolism phenotype, by mechanisms that could participate in tumor cell survival.

Multi-phase-fluid discrimination with local fibre-optical probes: III. Three-phase flows

NASA Astrophysics Data System (ADS)

Fordham, E. J.; Ramos, R. T.; Holmes, A.; Simonian, S.; Huang, S.-M.; Lenn, C. P.

1999-12-01

Local fibre-optical sensors (or `local probes') for immiscible-fluid discrimination are demonstrated in three-phase (oil/water/gas) flows. The probes are made from standard silica fibres with plane oblique facets polished at the fibre tip, with surface treatment for wettability control. They use total internal reflection to distinguish among drops, bubbles and other regions of fluid in multi-phase flows, on the basis of refractive-index contrast. Dual probes, using two sensors each with a quasi-binary output, are used to determine profiles of three-phase volume fraction in a flow of kerosene, water and air in a pipe. The individual sensors used discriminate oil from `not-oil' and gas from liquid; their logical combination discriminates among the three phases. Companion papers deal with the sensor designs used and quantitative results achieved in the simpler two-phase cases of liquid/liquid flows and gas/liquid flows.

Quantification of fatty acids as methyl esters and phospholipids in cheese samples after separation of triacylglycerides and phospholipids.

PubMed

Hauff, Simone; Vetter, Walter

2009-03-23

Determination of the individual fatty acid composition of neutral- and phospholipids as well as the phospholipid content of dairy food and other foodstuffs are important tasks in life sciences. For these purposes, a method was developed for the separation of lipids (standards of triolein and diacylphosphatidylcholines as well as three cheese samples) by solid-phase extraction using a self-packed column filled with partly deactivated silica. Non-halogenated solvents were used for the elution of the lipid classes. Cyclohexane/ethyl acetate (1:1, v/v) served for the elution of neutral lipids, while polar lipids were eluted with three solvents (ethyl acetate/methanol, methanol, and methanol/water) into one fraction. The separated lipid fractions were transesterified and the individual fatty acids were quantified by using gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode. The recovery rate for standard phosphatidylcholines was approximately 90% and cross-contamination from neutral lipids was negligible. The method was applied to cheese samples. Quantitative amounts of individual fatty acids in the phospholipid fraction were <0.002-0.29% of total lipids from camembert, <0.002-0.12% of total lipids from mozzarella, and <0.002-0.18% of total lipids in a goat cream cheese. Differences in the fatty acid pattern of neutral and polar lipids were detected. The quantity of the fatty acids determined in the phospholipid fraction was divided by the factor 0.7 in order to convert the fatty acid content into the phospholipid content of the cheese samples. This factor is based on the contribution of 16:0 to dipalmitoylphosphatidylcholine (DPPC). The resulting DPPC equivalents (DPPC(eq)) were found to be representative for the average contribution of fatty acids to all classes of phospholipids in dairy products. Using this approach, the phospholipid content of lipids from mozzarella, camembert, and goat cream cheese was 0.60%, 1.42% and 0.79%, respectively.

Apolipoproteins regulate the kinetics of endothelial lipase-mediated hydrolysis of phospholipids in reconstituted high-density lipoproteins.

PubMed

Caiazza, Daniela; Jahangiri, Anisa; Rader, Daniel J; Marchadier, Dawn; Rye, Kerry-Anne

2004-09-21

Endothelial lipase (EL) is a newly identified member of the triglyceride lipase gene family that hydrolyzes high-density lipoprotein (HDL) phospholipids. This study investigates the ability of the major apolipoproteins of rHDL to regulate the kinetics of EL-mediated phospholipid hydrolysis in well-characterized, homogeneous preparations of spherical rHDL. The rHDL contained either apoA-I as the only apolipoprotein, (A-I)rHDL, apoA-II as the only apolipoprotein, (A-II)rHDL, or apoA-I as well as apoA-II, (A-I/A-II)rHDL. The rHDL were comparable in terms of size and lipid composition and contained cholesteryl esters (CE) as their sole core lipid. Phospholipid hydrolysis was quantitated as the mass of nonesterified fatty acids (NEFA) released from the rHDL during incubation with EL. The V(max) of phospholipid hydrolysis for (A-I/A-II)rHDL [391.9 +/- 12.9 nmol of NEFA formed (mL of EL)(-1) h(-1)] was greater than (A-I)rHDL [152.8 +/- 4.7 nmol of NEFA formed (mL of EL)(-1) h(-1)]. The energy of activation (E(a)) for the hydrolysis reactions was calculated to be 52.1 and 34.8 kJ mol(-1) for (A-I)rHDL and (A-I/A-II)rHDL, respectively. Minimal phospholipid hydrolysis was observed for the (A-II)rHDL. Kinetic analysis showed that EL has a higher affinity for the phospholipids in (A-I)rHDL [K(m)(app) = 0.10 +/- 0.01 mM] than in (A-I/A-II)rHDL [K(m)(app) = 0.27 +/- 0.03 mM]. Furthermore, (A-I)rHDL is a competitive inhibitor of the EL-mediated phospholipid hydrolysis of (A-I/A-II)rHDL. These results establish that apolipoproteins are major determinants of the kinetics of EL-mediated phospholipid hydrolysis in rHDL.

Metabolic Effects of n-3 PUFA as Phospholipids Are Superior to Triglycerides in Mice Fed a High-Fat Diet: Possible Role of Endocannabinoids

PubMed Central

Rossmeisl, Martin; Macek Jilkova, Zuzana; Kuda, Ondrej; Jelenik, Tomas; Medrikova, Dasa; Stankova, Barbora; Kristinsson, Björn; Haraldsson, Gudmundur G.; Svensen, Harald; Stoknes, Iren; Sjövall, Peter; Magnusson, Ylva; Balvers, Michiel G. J.; Verhoeckx, Kitty C. M.; Tvrzicka, Eva; Bryhn, Morten; Kopecky, Jan

2012-01-01

Background n-3 polyunsaturated fatty acids, namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), reduce the risk of cardiovascular disease and can ameliorate many of obesity-associated disorders. We hypothesised that the latter effect will be more pronounced when DHA/EPA is supplemented as phospholipids rather than as triglycerides. Methodology/Principal Findings In a ‘prevention study’, C57BL/6J mice were fed for 9 weeks on either a corn oil-based high-fat obesogenic diet (cHF; lipids ∼35% wt/wt), or cHF-based diets in which corn oil was partially replaced by DHA/EPA, admixed either as phospholipids or triglycerides from marine fish. The reversal of obesity was studied in mice subjected to the preceding cHF-feeding for 4 months. DHA/EPA administered as phospholipids prevented glucose intolerance and tended to reduce obesity better than triglycerides. Lipemia and hepatosteatosis were suppressed more in response to dietary phospholipids, in correlation with better bioavailability of DHA and EPA, and a higher DHA accumulation in the liver, white adipose tissue (WAT), and muscle phospholipids. In dietary obese mice, both DHA/EPA concentrates prevented a further weight gain, reduced plasma lipid levels to a similar extent, and tended to improve glucose tolerance. Importantly, only the phospholipid form reduced plasma insulin and adipocyte hypertrophy, while being more effective in reducing hepatic steatosis and low-grade inflammation of WAT. These beneficial effects were correlated with changes of endocannabinoid metabolome in WAT, where phospholipids reduced 2-arachidonoylglycerol, and were more effective in increasing anti-inflammatory lipids such as N-docosahexaenoylethanolamine. Conclusions/Significance Compared with triglycerides, dietary DHA/EPA administered as phospholipids are superior in preserving a healthy metabolic profile under obesogenic conditions, possibly reflecting better bioavalability and improved modulation of the endocannabinoid system activity in WAT. PMID:22701720

A novel matrix dispersion based on phospholipid complex for improving oral bioavailability of baicalein: preparation, in vitro and in vivo evaluations.

PubMed

Zhou, Yang; Dong, Wujun; Ye, Jun; Hao, Huazhen; Zhou, Junzhuo; Wang, Renyun; Liu, Yuling

2017-11-01

Phospholipid complex is one of the most successful approaches for enhancing oral bioavailability of poorly absorbed plant constituents. But the sticky property of phospholipids results in an unsatisfactory dissolution of drugs. In this study, a matrix dispersion of baicalein based on phospholipid complex (BaPC-MD) was first prepared by a discontinuous solvent evaporation method, in which polyvinylpyrrolidone-K30 (PVP-K30) was employed for improving the dispersibility of baicalein phospholipid complex (BaPC) and increasing dissolution of baicalein. The combination ratio of baicalein and phospholipids in BaPC-MD was 99.39% and baicalein was still in a complete complex state with phospholipid in BaPC-MD. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) analyzes demonstrated that baicalein was fully transformed to an amorphous state in BaPC-MD and phospholipid complex formed. The water-solubility and n-octanol solubility of baicalein in BaPC-MD significantly increased compared with those of pure baicalein. Compared with baicalein and BaPC, the cumulative dissolution of BaPC-MD at 120 min increased 2.77- and 1.23-fold, respectively. In vitro permeability study in Caco-2 cells indicated that the permeability of BaPC-MD was remarkably higher than those of baicalein and BaPC. Pharmacokinetic study showed that the average C max of BaPC-MD was significantly increased compared to baicalein and BaPC. AUC 0-14 h of BaPC-MD was 5.01- and 1.91-fold of baicalein and BaPC, respectively. The novel BaPC-MD significantly enhanced the oral bioavailability of baicalein by improving the dissolution and permeability of baicalein without destroying the complexation state of baicalein and phospholipids. The current drug delivery system provided an optimal strategy to significantly enhance oral bioavailability for poorly water-soluble drugs.

Protection by phospholipids of Schistosoma mansoni schistosomula against the action of cytotoxic antibodies and complement.

PubMed

Billecocq, A

1987-09-01

Schistosoma mansoni schistosomula cultured in the presence of phospholipids showed a decreased sensitivity to the lethal complement-mediated action of anti-schistosome antibodies. Phosphatidyl choline, sphingomyelin and phosphatidyl ethanolamine had a protective action on the schistosomula transformed in vitro by passage through the skin or by a mechanical procedure. Phosphatidyl choline acted regardless of its fatty acid composition. Phosphatidyl serine and phosphatidic acid did not protect. Thus, it appears that phospholipids can play a role in parasite resistance to immune attack by cytotoxic antibodies and complement, and that this role is specific to certain phospholipid types.

Effect of Cholesterol on the Structure of a Five-Component Mitochondria-Like Phospholipid Membrane

PubMed Central

Cathcart, Kelly; Patel, Amit; Dies, Hannah; Rheinstädter, Maikel C.; Fradin, Cécile

2015-01-01

Cellular membranes have a complex phospholipid composition that varies greatly depending on the organism, cell type and function. In spite of this complexity, most structural data available for phospholipid bilayers concern model systems containing only one or two different phospholipids. Here, we examine the effect of cholesterol on the structure of a complex membrane reflecting the lipid composition of mitochondrial membranes, with five different types of headgroups (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL)) and a variety of hydrocarbon tails. This particular system was chosen because elevated cholesterol contents in mitochondrial membranes have been linked to a breaking down of Bax-mediated membrane permeabilization and resistance to cancer treatments. High resolution electron density profiles were determined by X-ray reflectivity, while the area per phospholipid chain, Apc, and the chain order parameter, SX-ray, were determined by wide-angle X-ray scattering (WAXS). We show that chain order increases upon the addition of cholesterol, resulting in both a thickening of the lipid bilayer and a reduction in the average surface area per phospholipid chain. This effect, well known as cholesterol’s condensation effect, is similar, but not as pronounced as for single-component phospholipid membranes. We conclude by discussing the relevance of these findings for the insertion of the pro-apoptotic protein Bax in mitochondrial membranes with elevated cholesterol content. PMID:26529029

[The effect of N-stearoylethanolamine on liver phospholipid composition of rats with insulin resistance caused by alimentary obesity].

PubMed

Onopchenko, O V; Kosiakova, H V; Horid'ko, T M; Klimashevskyĭ, V M; Hula, N M

2014-01-01

We used alimentary obesity-induced insulin resistance (IR) model in rats to investigate the influence of N-stearoylethanolamine on the content of phospholipids and their fatty acid composition. Our results show that prolonged high-fat diet triggers considerable aberrations in the composition of main phospholipids in the liver and can be one of the causes of IR in rats. In particular, the increase of phosphatidylcholine, phosphatidylethanolamine and significant decrease of other phospholipids: lysophosphatidylcholine, lysophosphatidylethanolamine, sphingomyelin, phosphatidylinositol, phosphatidylserine and diphosphaglicerol were observed. The levels of monounsaturated (erucic, nervonic, oleic) and polyunsaturated (eicosatrienoic, docosatrienoic, arachidonic) fatty acids were increased; meanwhile the content of diunsaturated acids was decreased. The NSE administration (50 mg/kg of body weight) caused restoration of the phospholipids content in the liver of rats with diet-induced IR that highly correlated with the decrease in plasma insulin level and the improvement of insulin sensitivity. Moreover, the effect of NSE was accompanied by the normalization of fatty acids composition of phospholipids that could be related to modulating influence of NSE on the activity of the main fatty acid desaturases. It is known that the imbalance in phospholipid composition of the rat liver causes substantial metabolic alterations that are associated with the development of IR. Accordingly, the compensations of the imbalance by NSE can help to restore insulin sensitivity, inhibit the development of obesity, IR and type 2 diabetes.

Effect of Cholesterol on the Structure of a Five-Component Mitochondria-Like Phospholipid Membrane.

PubMed

Cathcart, Kelly; Patel, Amit; Dies, Hannah; Rheinstädter, Maikel C; Fradin, Cécile

2015-10-30

Cellular membranes have a complex phospholipid composition that varies greatly depending on the organism, cell type and function. In spite of this complexity, most structural data available for phospholipid bilayers concern model systems containing only one or two different phospholipids. Here, we examine the effect of cholesterol on the structure of a complex membrane reflecting the lipid composition of mitochondrial membranes, with five different types of headgroups (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL)) and a variety of hydrocarbon tails. This particular system was chosen because elevated cholesterol contents in mitochondrial membranes have been linked to a breaking down of Bax-mediated membrane permeabilization and resistance to cancer treatments. High resolution electron density profiles were determined by X-ray reflectivity, while the area per phospholipid chain, Apc, and the chain order parameter, SX-ray, were determined by wide-angle X-ray scattering (WAXS). We show that chain order increases upon the addition of cholesterol, resulting in both a thickening of the lipid bilayer and a reduction in the average surface area per phospholipid chain. This effect, well known as cholesterol's condensation effect, is similar, but not as pronounced as for single-component phospholipid membranes. We conclude by discussing the relevance of these findings for the insertion of the pro-apoptotic protein Bax in mitochondrial membranes with elevated cholesterol content.

Qualitative and quantitative changes in phospholipids and proteins investigated by spectroscopic techniques in olfactory bulbectomy animal depression model.

PubMed

Depciuch, J; Parlinska-Wojtan, M

2018-01-30

Depression becomes nowadays a high mortality civilization disease with one of the potential causes being impaired smell. In this study Raman, Fourier Transform Infra Red (FTIR) and Ultraviolet-Visible (UV-vis) spectroscopies were used to determine the changes in the quantity and structure of phospholipids and proteins in the blood serum of bulbectomized rats (OB_NaCl), which is a common animal depression model. The efficiency of amitriptyline (AMI) treatment was also evaluated. The obtained results show a significant decrease in the phospholipid and protein fractions (as well as changes in their secondary structures) in blood serum of bulbectomized rats. AMI treatment in bulbectomized rats increased protein level and did not affect the level of phospholipids. Structural information from phospholipids and proteins was obtained from UV-vis spectroscopy combined with the second derivative of the FTIR spectra. Indeed, the structure of proteins in blood serum of bulbectomized rats was normalized after amitriptyline therapy, while the damaged structure of phospholipids remained unaffected. These findings strongly suggest that impaired smell could be one of the causes of depression and may induce permanent (irreversible) damages into the phospholipid structure identified as shortened carbon chains. This study shows a possible new application of spectroscopic techniques in the diagnosis and therapy monitoring of depression. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of antiglaucoma drugs on [32P]orthophosphate incorporation into phospholipids of cat iris and ciliary process.

PubMed

Yorio, T; DeLoach, G; Satumtira, N

1985-01-01

The effects of antiglaucoma drugs on [32P]-orthophosphate incorporation into phospholipids of iris and ciliary process were investigated. Both iris and ciliary process rapidly incorporated 32Pi into the major phospholipids, with the acidic phosphoinositides demonstrating a greater labelling than phosphatidylcholine, indicating a greater turnover. The muscarinic agonists, carbachol and pilocarpine, stimulated 32Pi-labelling of phosphatidylinositol (PI) and phosphatidic acid (PA) in both iris and ciliary process. These effects were blocked by atropine, suggesting that the response was mediated through muscarinic receptors. The beta blocking ocular hypotensive drugs, propranolol, timolol and atenolol, produced varying effects on 32P incorporation into phospholipids of iris and ciliary process. Propranolol stimulated 32Pi-labelling into phosphatidylinositol 4', 5' bisphosphate (PIP2), phosphatidylinositol 4' phosphate (PIP), PI and PA. Timolol decreased 32Pi-incorporation into PIP2 and PI, whereas atenolol, a selective beta 1 antagonist, had no significant effect on 32Pi-labelling of phospholipids. The above findings on propranolol agree with previous observations which demonstrated that propranolol redirects glycerolipid metabolism through multiple effects on the enzymes in phospholipid biosynthesis, particularly in stimulating phosphatidylinositol kinases. The results with timolol suggest that this drug may decrease phosphoinositide hydrolysis. The effects of these ocular hypotensive, non-selective beta blocking drugs on phospholipid turnover may ultimately limit the accumulation of breakdown products which could serve as cellular messengers.

Multiphase, multicomponent phase behavior prediction

NASA Astrophysics Data System (ADS)

Dadmohammadi, Younas

Accurate prediction of phase behavior of fluid mixtures in the chemical industry is essential for designing and operating a multitude of processes. Reliable generalized predictions of phase equilibrium properties, such as pressure, temperature, and phase compositions offer an attractive alternative to costly and time consuming experimental measurements. The main purpose of this work was to assess the efficacy of recently generalized activity coefficient models based on binary experimental data to (a) predict binary and ternary vapor-liquid equilibrium systems, and (b) characterize liquid-liquid equilibrium systems. These studies were completed using a diverse binary VLE database consisting of 916 binary and 86 ternary systems involving 140 compounds belonging to 31 chemical classes. Specifically the following tasks were undertaken: First, a comprehensive assessment of the two common approaches (gamma-phi (gamma-ϕ) and phi-phi (ϕ-ϕ)) used for determining the phase behavior of vapor-liquid equilibrium systems is presented. Both the representation and predictive capabilities of these two approaches were examined, as delineated form internal and external consistency tests of 916 binary systems. For the purpose, the universal quasi-chemical (UNIQUAC) model and the Peng-Robinson (PR) equation of state (EOS) were used in this assessment. Second, the efficacy of recently developed generalized UNIQUAC and the nonrandom two-liquid (NRTL) for predicting multicomponent VLE systems were investigated. Third, the abilities of recently modified NRTL model (mNRTL2 and mNRTL1) to characterize liquid-liquid equilibria (LLE) phase conditions and attributes, including phase stability, miscibility, and consolute point coordinates, were assessed. The results of this work indicate that the ϕ-ϕ approach represents the binary VLE systems considered within three times the error of the gamma-ϕ approach. A similar trend was observed for the for the generalized model predictions using quantitative structure-property parameter generalizations (QSPR). For ternary systems, where all three constituent binary systems were available, the NRTL-QSPR, UNIQUAC-QSPR, and UNIFAC-6 models produce comparable accuracy. For systems where at least one constituent binary is missing, the UNIFAC-6 model produces larger errors than the QSPR generalized models. In general, the LLE characterization results indicate the accuracy of the modified models in reproducing the findings of the original NRTL model.

Surface interactions, thermodynamics and topography of binary monolayers of Insulin with dipalmitoylphosphatidylcholine and 1-palmitoyl-2-oleoylphosphatidylcholine at the air/water interface.

PubMed

Grasso, E J; Oliveira, R G; Maggio, B

2016-02-15

The molecular packing, thermodynamics and surface topography of binary Langmuir monolayers of Insulin and DPPC (dipalmitoylphosphatidylcholine) or POCP (1-palmitoyl-2-oleoylphosphatidylcholine) at the air/water interface on Zn(2+) containing solutions were studied. Miscibility and interactions were ascertained by the variation of surface pressure-mean molecular area isotherms, surface compressional modulus and surface (dipole) potential with the film composition. Brewster Angle Microscopy was used to visualize the surface topography of the monolayers. Below 20mN/m Insulin forms stable homogenous films with DPPC and POPC at all mole fractions studied (except for films with XINS=0.05 at 10mN/m where domain coexistence was observed). Above 20mN/m, a segregation process between mixed phases occurred in all monolayers without squeezing out of individual components. Under compression the films exhibit formation of a viscoelastic or kinetically trapped organization leading to considerable composition-dependent hysteresis under expansion that occurs with entropic-enthalpic compensation. The spontaneously unfavorable interactions of Insulin with DPPC are driven by favorable enthalpy that is overcome by unfavorable entropic ordering; in films with POPC both the enthalpic and entropic effects are unfavorable. The surface topography reveals domain coexistence at relatively high pressure showing a striped appearance. The interactions of Insulin with two major membrane phospholipids induces composition-dependent and long-range changes of the surface organization that ought to be considered in the context of the information-transducing capabilities of the hormone for cell functioning. Copyright © 2015 Elsevier Inc. All rights reserved.

Novel Colloidal Microstructures of β-Escin and the Liposomal Components Cholesterol and DPPC.

PubMed

de Groot, Carolin; Müsken, Mathias; Müller-Goymann, Christel C

2018-05-24

The discovery of immunostimulating complex formation by the saponin Quil A from the plant Quillaja saponaria with cholesterol and a phospholipid opened up new avenues for the development of drug delivery systems for vaccine application with additional adjuvant properties. In this study, β -escin, a monodesmosidic triterpene saponin from horse chestnut, was investigated in terms of its interaction with liposomal components (cholesterol, dipalmitoylphosphatidylcholine) by Langmuir film balance studies and with regard to particle formation visualized by transmission electron microscopy. A strong interaction of β -escin with cholesterol was observed by Langmuir isotherms due to the intercalation of the saponin into the monolayer, whereas no interaction occurred with dipalmitoylphosphatidylcholine. Transmission electron microscopy studies also confirmed the strong interaction of β -escin with cholesterol. In aqueous pseudo-ternary systems ( β -escin, dipalmitoylphosphatidylcholine, cholesterol) and in pseudo-binary systems ( β -escin, cholesterol), new colloidal structures built up from ring-like and worm-like subunits were observed with a size of about 100 - 200 nm. These colloidal structures are formed in pseudo-binary systems by aggregation of the subunits, whereas in pseudo-ternary systems, they are formed among others by attacking the liposomal membrane. The rehydration of the liposomal dispersions in NANOpure water or Tris buffer pH 7.4 (140 mM) resulted in the same particle formation. In contrast, the sequence of the dispersions' production process affected the particle formation. Unless adding the saponin to the other components from the beginning, just a liposomal dispersion was formed without any colloidal aggregates of the subunits mentioned above. Georg Thieme Verlag KG Stuttgart · New York.

Options for refractive index and viscosity matching to study variable density flows

NASA Astrophysics Data System (ADS)

Clément, Simon A.; Guillemain, Anaïs; McCleney, Amy B.; Bardet, Philippe M.

2018-02-01

Variable density flows are often studied by mixing two miscible aqueous solutions of different densities. To perform optical diagnostics in such environments, the refractive index of the fluids must be matched, which can be achieved by carefully choosing the two solutes and the concentration of the solutions. To separate the effects of buoyancy forces and viscosity variations, it is desirable to match the viscosity of the two solutions in addition to their refractive index. In this manuscript, several pairs of index matched fluids are compared in terms of viscosity matching, monetary cost, and practical use. Two fluid pairs are studied in detail, with two aqueous solutions (binary solutions of water and a salt or alcohol) mixed into a ternary solution. In each case: an aqueous solution of isopropanol mixed with an aqueous solution of sodium chloride (NaCl) and an aqueous solution of glycerol mixed with an aqueous solution of sodium sulfate (Na_2SO_4). The first fluid pair allows reaching high-density differences at low cost, but brings a large difference in dynamic viscosity. The second allows matching dynamic viscosity and refractive index simultaneously, at reasonable cost. For each of these four solutes, the density, kinematic viscosity, and refractive index are measured versus concentration and temperature, as well as wavelength for the refractive index. To investigate non-linear effects when two index-matched, binary solutions are mixed, the ternary solutions formed are also analyzed. Results show that density and refractive index follow a linear variation with concentration. However, the viscosity of the isopropanol and NaCl pair deviates from the linear law and has to be considered. Empirical correlations and their coefficients are given to create index-matched fluids at a chosen temperature and wavelength. Finally, the effectiveness of the refractive index matching is illustrated with particle image velocimetry measurements performed for a buoyant jet in a linearly stratified environment. The creation of the index-matched solutions and linear stratification in a large-scale experimental facility are detailed, as well as the practical challenges to obtain precise refractive index matching.

Formation of H2-He substellar bodies in cold conditions. Gravitational stability of binary mixtures in a phase transition

NASA Astrophysics Data System (ADS)

Füglistaler, A.; Pfenniger, D.

2016-06-01

Context. Molecular clouds typically consist of 3/4 H2, 1/4 He and traces of heavier elements. In an earlier work we showed that at very low temperatures and high densities, H2 can be in a phase transition leading to the formation of ice clumps as large as comets or even planets. However, He has very different chemical properties and no phase transition is expected before H2 in dense interstellar medium conditions. The gravitational stability of fluid mixtures has been studied before, but these studies did not include a phase transition. Aims: We study the gravitational stability of binary fluid mixtures with special emphasis on when one component is in a phase transition. The numerical results are aimed at applications in molecular cloud conditions, but the theoretical results are more general. Methods: First, we study the gravitational stability of van der Waals fluid mixtures using linearized analysis and examine virial equilibrium conditions using the Lennard-Jones intermolecular potential. Then, combining the Lennard-Jones and gravitational potentials, the non-linear dynamics of fluid mixtures are studied via computer simulations using the molecular dynamics code LAMMPS. Results: Along with the classical, ideal-gas Jeans instability criterion, a fluid mixture is always gravitationally unstable if it is in a phase transition because compression does not increase pressure. However, the condensed phase fraction increases. In unstable situations the species can separate: in some conditions He precipitates faster than H2, while in other conditions the converse occurs. Also, for an initial gas phase collapse the geometry is essential. Contrary to spherical or filamentary collapses, sheet-like collapses starting below 15 K easily reach H2 condensation conditions because then they are fastest and both the increase of heating and opacity are limited. Conclusions: Depending on density, temperature and mass, either rocky H2 planetoids, or gaseous He planetoids form. H2 planetoids are favoured by high density, low temperature and low mass, while He planetoids need more mass and can form at temperature well above the critical value.

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.

Effet d'un champ magnétique uniforme sur les instabilités de Rayleigh-Bénard avec effet Soret

NASA Astrophysics Data System (ADS)

Ben Sassi, Mokhtar; Kaddeche, Slim; Abdennadher, Ali; Henry, Daniel; Hadid, Hamda Ben; Mojtabi, Abdelkader

2016-01-01

The effect of both magnitude and orientation of a uniform magnetic field on the critical transition occurring within an electrically conducting binary fluid layer, stratified in temperature and concentration, taking into account the Soret effect, is investigated numerically. For such a configuration, the results show that the critical thresholds corresponding to an arbitrary orientated magnetic field can be derived from those obtained for a vertical magnetic field and that the axes of the marginal cells are aligned with the horizontal component of the magnetic field. Moreover, an analytical study is conducted to investigate the impact of the magnetic field on long-wavelength instabilities. The effect of the magnetic field on such instabilities reveals a new phenomenon consisting in major changes of the unstable modes that lose their unicellular nature to regain their multi-roll characteristic, as it is the case without magnetic field for ψ <ψℓ0 = 131 Le / (34 - 131 Le). For a binary fluid characterized by a Lewis number Le and a separation factor ψ >ψℓ0, the value of the Hartmann number Haℓ (ψ , Le) corresponding to that transition responsible for a significant change in mass and heat transfer can be determined from the analytical relations derived in this work.

Determination of phospholipid regiochemistry by Ag(I) adduction and tandem mass spectrometry.

PubMed

Yoo, Hyun Ju; Håkansson, Kristina

2011-02-15

Collision-activated dissociation (CAD) and infrared multiphoton dissociation (IRMPD) of Ag-adducted phospholipids were investigated as structural tools. Previously, determination of the acyl chains at the two phospholipid esterification sites has been performed based on the R(1)COO(-)/R(2)COO(-) ratio in negative ion mode CAD tandem mass spectrometry. However, the observed product ion ratio is dependent on the extent of unsaturation of the fatty acyl group at sn-2 as well as on the total chain length. Similarly, in positive ion mode CAD with/without alkaline or alkaline earth metal adduction, the ratio of product ions resulting from either R(1)COOH or R(2)COOH neutral losses is dependent on the nature of the phospholipid polar headgroup. Ag(+) ion chromatography, in which silver ions are part of the stationary phase, can provide information on double bond number/distribution as well as double bond configuration (cis/trans) because of interaction between Ag(+) ions and olefinic π electrons of fatty acids and lipids. We hypothesized that interactions between double bonds and Ag(+) may be utilized to also reveal phospholipid esterification site information in tandem mass spectrometry. CAD and IRMPD of Ag-adducted phospholipids with unsaturated fatty acids (R(x)COOH, x = 1 or 2) provided characteristic product ions, [R(x)COOH + Ag](+), and their neutral losses. The characteristic product ions and their abundances do not depend on the type of polar headgroup or the number of double bonds of unsaturated acyl chains. Tandem mass spectrometry of Cu-adducted phospholipids was also performed for comparison based on the Lewis acid and base properties of Cu(+) and phospholipid double bonds, respectively.

NuA4 Lysine Acetyltransferase Complex Contributes to Phospholipid Homeostasis in Saccharomyces cerevisiae.

PubMed

Dacquay, Louis; Flint, Annika; Butcher, James; Salem, Danny; Kennedy, Michael; Kaern, Mads; Stintzi, Alain; Baetz, Kristin

2017-06-07

Actively proliferating cells constantly monitor and readjust their metabolic pathways to ensure the replenishment of phospholipids necessary for membrane biogenesis and intracellular trafficking. In Saccharomyces cerevisiae , multiple studies have suggested that the lysine acetyltransferase complex NuA4 plays a role in phospholipid homeostasis. For one, NuA4 mutants induce the expression of the inositol-3-phosphate synthase gene, INO1 , which leads to excessive accumulation of inositol, a key metabolite used for phospholipid biosynthesis. Additionally, NuA4 mutants also display negative genetic interactions with sec14-1 ts , a mutant of a lipid-binding gene responsible for phospholipid remodeling of the Golgi. Here, using a combination of genetics and transcriptional profiling, we explore the connections between NuA4, inositol, and Sec14 Surprisingly, we found that NuA4 mutants did not suppress but rather exacerbated the growth defects of sec14-1 ts under inositol-depleted conditions. Transcriptome studies reveal that while loss of the NuA4 subunit EAF1 in sec14-1 ts does derepress INO1 expression, it does not derepress all inositol/choline-responsive phospholipid genes, suggesting that the impact of Eaf1 on phospholipid homeostasis extends beyond inositol biosynthesis. In fact, we find that NuA4 mutants have impaired lipid droplet levels and through genetic and chemical approaches, we determine that the genetic interaction between sec14-1 ts and NuA4 mutants potentially reflects a role for NuA4 in fatty acid biosynthesis. Altogether, our work identifies a new role for NuA4 in phospholipid homeostasis. Copyright © 2017 Dacquay et al.

Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

NASA Astrophysics Data System (ADS)

Schmiele, Martin; Schindler, Torben; Unruh, Tobias; Busch, Sebastian; Morhenn, Humphrey; Westermann, Martin; Steiniger, Frank; Radulescu, Aurel; Lindner, Peter; Schweins, Ralf; Boesecke, Peter

2013-06-01

Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr.JACGAR0021-889810.1107/S0021889807044378 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

Native and dry-heated lysozyme interactions with membrane lipid monolayers: Lipid packing modifications of a phospholipid mixture, model of the Escherichia coli cytoplasmic membrane.

PubMed

Derde, Melanie; Nau, Françoise; Guérin-Dubiard, Catherine; Lechevalier, Valérie; Paboeuf, Gilles; Jan, Sophie; Baron, Florence; Gautier, Michel; Vié, Véronique

2015-04-01

Antimicrobial resistance is currently an important public health issue. The need for innovative antimicrobials is therefore growing. The ideal antimicrobial compound should limit antimicrobial resistance. Antimicrobial peptides or proteins such as hen egg white lysozyme are promising molecules that act on bacterial membranes. Hen egg white lysozyme has recently been identified as active on Gram-negative bacteria due to disruption of the outer and cytoplasmic membrane integrity. Furthermore, dry-heating (7 days and 80 °C) improves the membrane activity of lysozyme, resulting in higher antimicrobial activity. These in vivo findings suggest interactions between lysozyme and membrane lipids. This is consistent with the findings of several other authors who have shown lysozyme interaction with bacterial phospholipids such as phosphatidylglycerol and cardiolipin. However, until now, the interaction between lysozyme and bacterial cytoplasmic phospholipids has been in need of clarification. This study proposes the use of monolayer models with a realistic bacterial phospholipid composition in physiological conditions. The lysozyme/phospholipid interactions have been studied by surface pressure measurements, ellipsometry and atomic force microscopy. Native lysozyme has proved able to absorb and insert into a bacterial phospholipid monolayer, resulting in lipid packing reorganization, which in turn has lead to lateral cohesion modifications between phospholipids. Dry-heating of lysozyme has increased insertion capacity and ability to induce lipid packing modifications. These in vitro findings are then consistent with the increased membrane disruption potential of dry heated lysozyme in vivo compared to native lysozyme. Moreover, an eggPC monolayer study suggested that lysozyme/phospholipid interactions are specific to bacterial cytoplasmic membranes. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of phospholipids and their molecular species on cholesterol solubility and nucleation in human and model biles.

PubMed Central

Halpern, Z; Moshkowitz, M; Laufer, H; Peled, Y; Gilat, T

1993-01-01

Much research in the pathophysiology of gall stones has been devoted to various molecular species of bile salts. Recent findings have shown the importance of phospholipids in biliary pathophysiology. In the present study the addition of increasing doses of egg lecithin to human and model biles progressively prolonged the nucleation time. Concurrently biliary cholesterol was shifted from the vesicular to the non-vesicular carrier(s) while the cholesterol/phospholipid ratio of the remaining vesicles was progressively lowered. Model bile solutions of identical lipid concentration were prepared using phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine as the only phospholipid. With phosphatidylethanolamine most of the cholesterol was shifted to the vesicular carrier while phosphatidylserine shifted most of the cholesterol to the non-vesicular carrier(s). With phosphatidylcholine the cholesterol was distributed in both carriers. Phosphatidyl choline species composed of various acyl fatty acids in the sn-1 and sn-2 positions were used as the sole phospholipid in otherwise identical model bile solutions. With palmitic acid in the sn-1 position and arachidonic acid in the sn-2 position most of the cholesterol was found in the non-vesicular carrier. When stearic acid was used in sn-2 position instead of arachidonic acid most of the cholesterol was found in the vesicular carrier. These and other variations in phospholipid molecular species shifted cholesterol among its carriers and also modified the nucleation time of model biles. Most of these effects were also found upon addition of the various phospholipid species to human biles. These findings show the importance of phospholipid species in biliary pathophysiology and may be useful when trying to manipulate cholesterol carriers and solubility in bile. PMID:8432440

Dietary safflower phospholipid reduces liver lipids in laying hens.

PubMed

An, B K; Nishiyama, H; Tanaka, K; Ohtani, S; Iwata, T; Tsutsumi, K; Kasai, M

1997-05-01

This experiment was conducted to determine the effects of dietary safflower phospholipids (crude safflower phospholipid and purified safflower phospholipid) on performance and lipid metabolism of laying hens. Sixty-week-old Single Comb White Leghorn laying hens were divided into four groups of seven birds each, and were given one of four experimental diets containing 5% beef tallow (served as a control, tallow), a mixture of safflower oil and palm oil (SP-oil), crude safflower phospholipid (Saf-PLcrude), or purified safflower phospholipid (Saf-PL) for 7 wk. Egg production ratio and daily egg mass were significantly higher in hens fed Saf-PLcrude diets than in hens of the other diet groups. There were no significant differences in egg weight among groups. Liver cholesterol and triglyceride contents were significantly decreased in all treated groups as compared with the control. The activity of hepatic 3-hydroxy-3 methylglutaryl coenzyme A reductase was the highest in hens fed the Saf-PLcrude diet. Serum esterified cholesterol concentration was decreased by feeding of SP-oil, Saf-PLcrude, or Saf-PL diets. Serum lecithin-cholesterol acyltransferase activity was highest in hens fed the tallow diet. Excreta neutral steroid excretion was significantly increased in the Saf-PLcrude or Saf-PL diet groups, although acidic steroid excretion was not affected by dietary treatments. Total cholesterol, triglyceride, and phospholipid contents in egg yolks were not different for any dietary treatments. The fatty acid compositions of egg yolks from hens fed Saf-PLcrude diets were not different with those fed the SP-oil diet, although eggs of hens fed the Saf-PL diet showed lower total polyunsaturated fatty acids. These results suggest that dietary safflower phospholipids may be a valuable ingredient to layers for reducing liver triglycerides and serum cholesterol without any adverse effects.

Production of a Health-Beneficial Food Emulsifier by Enzymatic Partial Hydrolysis of Phospholipids Obtained from the Head of Autumn Chum Salmon.

PubMed

Shah, A K M Azad; Nagao, Toshihiro; Kurihara, Hideyuki; Takahashi, Koretaro

2017-02-01

Phospholipids and their partial hydrolysates, namely lysophospholipids (LPLs), have been widely used in food, pharmaceutical, and cosmetic products as highly efficient emulsifiers. This study was conducted to produce docosahexaenoic acid (DHA)-esterified LPLs by enzymatic modification of phospholipids obtained from the head of autumn chum salmon (Oncorhynchus keta). The emulsifying properties of the obtained LPLs were also evaluated. Two different types of substrates of salmon head phospholipids were prepared via silica gel and cold acetone precipitation. Enzymatic partial hydrolysis was carried out using immobilized phospholipase A 1 (PLA 1 ) and Lipozyme RM IM. Results showed that the increase in DHA in the LPLs was much higher in the silica-separated phospholipids than in the acetone-precipitated phospholipids. When silica-separated phospholipids were used as the substrate, the DHA content of the LPLs increased from 23.1% to 40.6% and 42.6% after 8 h of partial hydrolysis with Lipozyme RM IM and immobilized PLA 1 , respectively. The yield of the LPLs was comparatively higher in the Lipozyme RM IM than in the immobilized PLA 1 hydrolysis reaction. The critical micelle concentration values of the LPLs and purified lysophosphatidylcholine (LPC) were 100 mg/L and 5 mg/L, respectively. The surface tension values of the LPLs and LPC were reduced to 30.0 mN/m and 30.5 mN/m, respectively. The hydrophilic-lipophilic balance of the LPLs and LPC were 6.0 and 9.4, respectively. Based on the emulsifying properties observed, we conclude that LPLs derived from the phospholipids of salmon head lipids could be used as a health-beneficial emulsifier in the food industry.

Advanced binary geothermal power plants: Limits of performance

NASA Astrophysics Data System (ADS)

Bliem, C. J.; Mines, G. L.

1991-01-01

The Heat Cycle Research Program is investigating potential improvements to power cycles utilizing moderate temperature geothermal resources to produce electrical power. Investigations have specifically examined Rankine cycle binary power systems. Binary Rankine cycles are more efficient than the flash steam cycles at moderate resource temperature, achieving a higher net brine effectiveness. At resource conditions similar to those at the Heber binary plant, it has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating in a supercritical Rankine cycle gave improved performance over Rankine cycles with the pure working fluids executing single or dual boiling cycles or supercritical cycles. Recently, other types of cycles have been proposed for binary geothermal service. The feasible limits on efficiency of a plant given practical limits on equipment performance is explored and the methods used in these advanced concept plants to achieve the maximum possible efficiency are discussed. (Here feasible is intended to mean reasonably achievable and not cost effective.) No direct economic analysis was made because of the sensitivity of economic results to site specific input. The limit of performance of three advanced plants were considered. The performance predictions were taken from the developers of each concept. The advanced plants considered appear to be approaching the feasible limit of performance. Ultimately, the plant designer must weigh the advantages and disadvantages of the the different cycles to find the best plant for a given service. In addition, a standard is presented of comparison of the work which has been done in the Heat Cycle Research Program and in the industrial sector by Exergy, Inc. and Polythermal Technologies.

Liposomes assembled from a dual drug-tailed phospholipid for cancer therapy.

PubMed

Fang, Shuo; Niu, Yuge; Zhu, Wenjun; Zhang, Yemin; Yu, Liangli; Li, Xinsong

2015-05-01

We report a novel dual drug-tailed phospholipid which can form liposomes as a combination of prodrug and drug carrier. An amphiphilic dual chlorambucil-tailed phospholipid (DCTP) was synthesized by a straightforward esterification. With two chlorambucil molecules as hydrophobic tails and one glycerophosphatidylcholine molecule as a hydrophilic head, the DCTP, a phospholipid prodrug, undergoes assembly to form a liposome without any additives by the thin lipid film technique. The DCTP liposomes, as an effective carrier of chlorambucil, exhibited a very high loading capacity and excellent stability. The liposomes had higher cytotoxic effects to cancer cell lines than free DCTP and chlorambucil. The in vivo antitumor activity assessment indicated that the DCTP liposomes could inhibit the tumor growth effectively. This novel strategy of dual drug-tailed phospholipid liposomes may be also applicable to other hydrophobic anticancer drugs which have great potential in cancer therapy. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vibrational spectroscopy and imaging for concurrent cellular trafficking of co-localized doxorubicin and deuterated phospholipid vesicles

NASA Astrophysics Data System (ADS)

Misra, S. K.; Mukherjee, P.; Ohoka, A.; Schwartz-Duval, A. S.; Tiwari, S.; Bhargava, R.; Pan, D.

2016-01-01

Simultaneous tracking of nanoparticles and encapsulated payload is of great importance and visualizing their activity is arduous. Here we use vibrational spectroscopy to study the in vitro tracking of co-localized lipid nanoparticles and encapsulated drug employing a model system derived from doxorubicin-encapsulated deuterated phospholipid (dodecyl phosphocholine-d38) single tailed phospholipid vesicles.Simultaneous tracking of nanoparticles and encapsulated payload is of great importance and visualizing their activity is arduous. Here we use vibrational spectroscopy to study the in vitro tracking of co-localized lipid nanoparticles and encapsulated drug employing a model system derived from doxorubicin-encapsulated deuterated phospholipid (dodecyl phosphocholine-d38) single tailed phospholipid vesicles. Electronic supplementary information (ESI) available: Raman and confocal images of the Deuto-DOX-NPs in cells, materials and details of methods. See DOI: 10.1039/c5nr07975f

Simultaneous voltammetric determination of dopamine and epinephrine in human body fluid samples using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film.

PubMed

Figueiredo-Filho, Luiz C S; Silva, Tiago A; Vicentini, Fernando C; Fatibello-Filho, Orlando

2014-06-07

A simple and highly selective electrochemical method was developed for the single or simultaneous determination of dopamine (DA) and epinephrine (EP) in human body fluids using a glassy carbon electrode modified with nickel oxide nanoparticles and carbon nanotubes within a dihexadecylphosphate film using square-wave voltammetry (SWV) or differential-pulse voltammetry (DPV). Using DPV with the proposed electrode, a separation of ca. 360 mV between the peak reduction potentials of DA and EP present in binary mixtures was obtained. The analytical curves for the simultaneous determination of dopamine and epinephrine showed an excellent linear response, ranging from 7.0 × 10(-8) to 4.8 × 10(-6) and 3.0 × 10(-7) to 9.5 × 10(-6) mol L(-1) for DA and EP, respectively. The detection limits for the simultaneous determination of DA and EP were 5.0 × 10(-8) mol L(-1) and 8.2 × 10(-8) mol L(-1), respectively. The proposed method was successfully applied in the simultaneous determination of these analytes in human body fluid samples of cerebrospinal fluid, human serum and lung fluid.

Surface tension of dilute alcohol-aqueous binary fluids: n-Butanol/water, n-Pentanol/water, and n-Hexanol/water solutions

NASA Astrophysics Data System (ADS)

Cheng, Kuok Kong; Park, Chanwoo

2017-07-01

Surface tension of pure fluids, inherently decreasing with regard to temperature, creates a thermo-capillary-driven (Marangoni) flow moving away from a hot surface. It has been known that few high-carbon alcohol-aqueous solutions exhibit an opposite behavior of the surface tension increasing with regard to temperature, such that the Marangoni flow moves towards the hot surface (self-rewetting effect). We report the surface tensions of three dilute aqueous solutions of n-Butanol, n-Pentanol and n-Hexanol as self-rewetting fluids measured for ranges of alcohol concentration (within solubility limits) and fluid temperatures (25-85 °C). A maximum bubble pressure method using a leak-tight setup was used to measure the surface tension without evaporation losses of volatile components. It was found from this study that the aqueous solutions with higher-carbon alcohols exhibit a weak self-rewetting behavior, such that the surface tensions remain constant or slightly increases above about 60 °C. These results greatly differ from the previously reported results showing a strong self-rewetting behavior, which is attributed to the measurement errors associated with the evaporation losses of test fluids during open-system experiments.

Benzoic Acid and Chlorobenzoic Acids: Thermodynamic Study of the Pure Compounds and Binary Mixtures With Water.

PubMed

Reschke, Thomas; Zherikova, Kseniya V; Verevkin, Sergey P; Held, Christoph

2016-03-01

Benzoic acid is a model compound for drug substances in pharmaceutical research. Process design requires information about thermodynamic phase behavior of benzoic acid and its mixtures with water and organic solvents. This work addresses phase equilibria that determine stability and solubility. In this work, Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was used to model the phase behavior of aqueous and organic solutions containing benzoic acid and chlorobenzoic acids. Absolute vapor pressures of benzoic acid and 2-, 3-, and 4-chlorobenzoic acid from literature and from our own measurements were used to determine pure-component PC-SAFT parameters. Two binary interaction parameters between water and/or benzoic acid were used to model vapor-liquid and liquid-liquid equilibria of water and/or benzoic acid between 280 and 413 K. The PC-SAFT parameters and 1 binary interaction parameter were used to model aqueous solubility of the chlorobenzoic acids. Additionally, solubility of benzoic acid in organic solvents was predicted without using binary parameters. All results showed that pure-component parameters for benzoic acid and for the chlorobenzoic acids allowed for satisfying modeling phase equilibria. The modeling approach established in this work is a further step to screen solubility and to predict the whole phase region of mixtures containing pharmaceuticals. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Enhanced oral bioavailability of silymarin using liposomes containing a bile salt: preparation by supercritical fluid technology and evaluation in vitro and in vivo

PubMed Central

Yang, Gang; Zhao, Yaping; Zhang, Yongtai; Dang, Beilei; Liu, Ying; Feng, Nianping

2015-01-01

The aim of this investigation was to develop a procedure to improve the dissolution and bioavailability of silymarin (SM) by using bile salt-containing liposomes that were prepared by supercritical fluid technology (ie, solution-enhanced dispersion by supercritical fluids [SEDS]). The process for the preparation of SM-loaded liposomes containing a bile salt (SM-Lip-SEDS) was optimized using a central composite design of response surface methodology with the ratio of SM to phospholipids (w/w), flow rate of solution (mL/min), and pressure (MPa) as independent variables. Particle size, entrapment efficiency (EE), and drug loading (DL) were dependent variables for optimization of the process and formulation variables. The particle size, zeta potential, EE, and DL of the optimized SM-Lip-SEDS were 160.5 nm, −62.3 mV, 91.4%, and 4.73%, respectively. Two other methods to produce SM liposomes were compared to the SEDS method. The liposomes obtained by the SEDS method exhibited the highest EE and DL, smallest particle size, and best stability compared to liposomes produced by the thin-film dispersion and reversed-phase evaporation methods. Compared to the SM powder, SM-Lip-SEDS showed increased in vitro drug release. The in vivo AUC0−t of SM-Lip-SEDS was 4.8-fold higher than that of the SM powder. These results illustrate that liposomes containing a bile salt can be used to enhance the oral bioavailability of SM and that supercritical fluid technology is suitable for the preparation of liposomes. PMID:26543366

Intra-operative on-line discrimination of kidney cancer from normal tissue by IR ATR spectroscopy of extracellular fluid

NASA Astrophysics Data System (ADS)

Urboniene, V.; Velicka, M.; Ceponkus, J.; Pucetaite, M.; Jankevicius, F.; Sablinskas, V.; Steiner, G.

2016-03-01

Determination of cancerous and normal kidney tissues during partial, simple or radical nephrectomy surgery was performed by using differences in the IR absorption spectra of extracellular fluid taken from the corresponding tissue areas. The samples were prepared by stamping of the kidney tissue on ATR diamond crystal. The spectral measurements were performed directly in the OR during surgery for 58 patients. It was found that intensities of characteristic spectral bands of glycogen (880-1200 cm-1) in extracellular fluid are sensitive to the type of the tissue and can be used as spectral markers of tumours. Characteristic spectral band of lactic acid (1730 cm-1) - product of the anaerobic glycolysis, taking place in the cancer cells is not suitable for use as a spectral marker of cancerous tissue, since it overlaps with the band of carbonyl stretch in phospholipids and fatty acids. Results of hierarchical cluster analysis of the spectra show that the spectra of healthy and tumour tissue films can be reliably separated into two groups. On the other hand, possibility to differentiate between tumours of different types and grades remains in question. While the fluid from highly malignant G3 tumour tissue contains highly pronounced glycogen spectral bands and can be well separated from benign and G1 tumours by principal component analysis, the variations between spectra from sample to sample prevent from obtaining conclusive results about the grouping between different tumour types and grades. The proposed method is instant and can be used in situ and even in vivo.

Phospholipids at the Interface: Current Trends and Challenges

PubMed Central

Pichot, Roman; Watson, Richard L.; Norton, Ian T.

2013-01-01

Phospholipids are one of the major structural elements of biological membranes. Due to their amphiphilic character, they can adopt various molecular assemblies when dispersed in water, such as bilayer vesicles or micelles, which give them unique interfacial properties and render them very attractive in terms of foam or emulsion stabilization. This article aims at reviewing the properties of phospholipids at the air/water and oil/water interfaces, as well as the recent advances in using these natural components as stabilizers, alone or in combination with other compounds such as proteins. A discussion regarding the challenges and opportunities offered by phospholipids-stabilized structure concludes the review. PMID:23736688

Effect of the nature of phospholipids on the degree of their interaction with isobornylphenol antioxidants

NASA Astrophysics Data System (ADS)

Marakulina, K. M.; Kramor, R. V.; Lukanina, Yu. K.; Plashchina, I. G.; Polyakov, A. V.; Fedorova, I. V.; Chukicheva, I. Yu.; Kutchin, A. V.; Shishkina, L. N.

2016-02-01

The parameters of complexation between natural phospholipids (lecithin, sphingomyelin, and cephalin) with antioxidants of a new class, isobornylphenols (IBPs), were determined by UV and IR spectroscopy. The self-organization of phospholipids (PLs) was studied depending on the structure of IBPs by dynamic light scattering. The nature of phospholipids and the structure of IBPs was found to produce a substantial effect both on the degree of complexation and on the size of PL aggregates in a nonpolar solvent. Based on the obtained data it was concluded that the structure of biological membranes mainly depends on the complexation of IBP with sphingomyelin.

Investigating the protective properties of milk phospholipids against ultraviolet light exposure in a skin equivalent model

NASA Astrophysics Data System (ADS)

Russell, Ashley; Laubscher, Andrea; Jimenez-Flores, Rafael; Laiho, Lily H.

2010-02-01

Current research on bioactive molecules in milk has documented health advantages of bovine milk and its components. Milk Phospholipids, selected for this study, represent molecules with great potential benefit in human health and nutrition. In this study we used confocal reflectance and multiphoton microscopy to monitor changes in skin morphology upon skin exposure to ultraviolet light and evaluate the potential of milk phospholipids in preventing photodamage to skin equivalent models. The results suggest that milk phospholipids act upon skin cells in a protective manner against the effect of ultraviolet (UV) radiation. Similar results were obtained from MTT tissue viability assay and histology.

Graphene/TiO2 nanocomposite based solid-phase extraction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for lipidomic profiling of avocado (Persea americana Mill.).

PubMed

Shen, Qing; Yang, Mei; Li, Linqiu; Cheung, Hon-Yeung

2014-12-10

Phospholipids possess important physiological, structural and nutritional functions in biological systems. This study described a solid-phase extraction (SPE) method, employing graphene and titanium dioxide (G/TiO2) nanocomposite as sorbent, for the selective isolation and enrichment of phospholipids from avocado (Persea americana Mill.). Based on the principal that the phosphoryl group in the phospholipid can interact with TiO2 via a bridging bidentate mode, an optimum condition was established for SPE, and was successfully applied to prepare avocado samples. The extracts were monitored by matrix-assisted laser desorption ionization time-of-flight/tandem mass spectrometry (MALDI-TOF/MS) in both positive-ion and negative-ion modes. Results showed that phospholipids could be efficiently extracted in a clean manner by G/TiO2 based SPE. In addition, the signals of phospholipids were enhanced while the noise was reduced. Some minor peaks became more obvious. In conclusion, the nanocomposite material of G/TiO2 was proved to be a promising sorbent for selective separation of phospholipids from crude lipid extract. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Ordering in bio-inorganic hybrid nanomaterials probed by in situ scanning transmission X-ray microscopy

DOE PAGES

Lee, Jonathan R. I.; Bagge-Hansen, Michael; Tunuguntla, Ramya; ...

2015-04-15

Here, phospholipid bilayer coated Si nanowires are one-dimensional (1D) composites that provide versatile bio-nanoelectronic functionality via incorporation of a wide variety of biomolecules into the phospholipid matrix. The physiochemical behaviour of the phospholipid bilayer is strongly dependent on its structure and, as a consequence, substantial modelling and experimental efforts have been directed at the structural characterization of supported bilayers and unsupported phospholipid vesicles; nonetheless, the experimental studies conducted to date have exclusively involved volume-averaged techniques, which do not allow for the assignment of spatially resolved structural variations that could critically impact the performance of the 1D phospholipid-Si NW composites. Inmore » this manuscript, we use scanning transmission X-ray microscopy (STXM) to probe bond orientation and bilayer thickness as a function of position with a spatial resolution of ~30 nm for Δ9-cis 1,2-dioleoyl-sn-glycero-3-phosphocholine layers prepared Si NWs. When coupled with small angle X-ray scattering measurements, the STXM data reveal structural motifs of the Si NWs that give rise to multi-bilayer formation and enable assignment of the orientation of specific bonds known to affect the order and rigidity of phospholipid bilayers.« less

Microsomal epoxide hydrolase of rat liver. Purification and characterization of enzyme fractions with different chromatographic characteristics.

PubMed Central

Bulleid, N J; Graham, A B; Craft, J A

1986-01-01

Microsomal epoxide hydrolase was purified from rat liver, and different fractions of the purified enzyme, which varied in their contents of phospholipid, were obtained by ion-exchange chromatography. One fraction (A), which did not bind to CM-cellulose, had a high phospholipid content, and a second fraction (B), which was eluted from CM-cellulose at high ionic strength, had a low phospholipid content. Removal of most of the phospholipid from fraction A altered its chromatographic behaviour. When the delipidated material was re-applied to CM-cellulose, most of the enzyme bound to the cation-exchanger. The specific activities of all the fractions described (with styrene epoxide [(1,2-epoxyethyl)benzene] as substrate) were altered by adding the non-ionic detergent Lubrol PX or phospholipid. Lubrol PX inhibited enzyme activity, and phospholipid reversed this inhibition. The various enzyme fractions isolated appeared to be different forms of the same protein, as judged by their minimum Mr values and immunochemical properties. These results indicate that different fractions of epoxide hydrolase isolated by ion-exchange chromatography probably are not different isoenzyme forms. Images Fig. 2. Fig. 3. PMID:3082328

Nanomechanical properties of phospholipid microbubbles.

PubMed

Buchner Santos, Evelyn; Morris, Julia K; Glynos, Emmanouil; Sboros, Vassilis; Koutsos, Vasileios

2012-04-03

This study uses atomic force microscopy (AFM) force-deformation (F-Δ) curves to investigate for the first time the Young's modulus of a phospholipid microbubble (MB) ultrasound contrast agent. The stiffness of the MBs was calculated from the gradient of the F-Δ curves, and the Young's modulus of the MB shell was calculated by employing two different mechanical models based on the Reissner and elastic membrane theories. We found that the relatively soft phospholipid-based MBs behave inherently differently to stiffer, polymer-based MBs [Glynos, E.; Koutsos, V.; McDicken, W. N.; Moran, C. M.; Pye, S. D.; Ross, J. A.; Sboros, V. Langmuir2009, 25 (13), 7514-7522] and that elastic membrane theory is the most appropriate of the models tested for evaluating the Young's modulus of the phospholipid shell, agreeing with values available for living cell membranes, supported lipid bilayers, and synthetic phospholipid vesicles. Furthermore, we show that AFM F-Δ curves in combination with a suitable mechanical model can assess the shell properties of phospholipid MBs. The "effective" Young's modulus of the whole bubble was also calculated by analysis using Hertz theory. This analysis yielded values which are in agreement with results from studies which used Hertz theory to analyze similar systems such as cells.

Interaction of phospholipid vesicles with cells. Endocytosis and fusion as alternate mechanisms for the uptake of lipid-soluble and water-soluble molecules

PubMed Central

1975-01-01

Depending on their phospholipid composition, liposomes are endocytosed by, or fuse with, the plasma membrane, of Acanthamoeba castellanii. Unilamellar egg lecithin vesicles are endocytosed by amoeba at 28 degrees C with equal uptake of the phospholipid bilayer and the contents of the internal aqueous space of the vesicles. Uptake is inhibited almost completely by incubation at 4 degrees C or in the presence of dinitrophenol. After uptake at 28 degrees C, the vesicle phospholipid can be visualized by electron microscope autoradiography within cytoplasmic vacuoles. In contrast, uptake of unilamellar dipalmitoyl lecithin vesicles and multilamellar dipalmitoyl lecithin liposomes is only partially inhibited at 4 degrees C, by dinitrophenol and by prior fixation of the amoebae with glutaraldehyde, each of which inhibits pinocytosis. Vesicle contents are taken up only about 40% as well as the phospholipid bilayer. Electron micrographs are compatible with the interpretation that dipalmitoyl lecithin vesicles fuse with the amoeba plasma membrane, adding their phospholipid to the cell surface, while their contents enter the cell cytoplasm. Dimyristoyl lecithin vesicles behave like egg lecithin vesicles while distearoyl lecithin vesicles behave like dipalmitoyl lecithin vesicles. PMID:1174130

The surface alloying effect of silicon in a binary NiTi-base alloy on the corrosion resistance and biocompatibility of the material

NASA Astrophysics Data System (ADS)

Psakhie, S. G.; Lotkov, A. I.; Meisner, L. L.; Meisner, S. N.; Matveeva, V. A.

2013-02-01

The corrosion resistance behavior and cytotoxicity of binary NiTi-base alloy specimens subjected to surface modification by silicon ion beams and the proliferative ability of mesenchymal stem cells of rat marrow on an ion-implanted surface of the alloy have been studied. The silicon ion beam processing of specimen surfaces is shown to bring about a nearly two-fold improvement in the corrosion resistance of the material to attack by aqueous solutions of NaCl (artificial body fluid) and human plasma and a drastic decrease in the nickel concentration after immersion of the specimens into the solutions for ˜3400 and ˜6000 h, respectively (for the artificial plasma solution, a nearly 20-fold decrease in the Ni concentration is observed.)

Three-Phase Melting Curves in the Binary System of Carbon Dioxide and Water

NASA Astrophysics Data System (ADS)

Abramson, E. H.

2017-10-01

Invariant, three-phase melting curves, of ice VI in equilibrium with solid CO2, of ice VII in equilibrium with solid CO2, and of solid CO2 in simultaneous equilibrium with a majority aqueous and a majority CO2 fluid, were explored in the binary system of carbon dioxide and water. Diamond-anvil cells were used to develop pressures of 5 GPa. Water exhibits a large melting temperature depression (73°C less than its pure melting temperature of 253°C at 5 GPa) indicative of large concentrations of CO2 in the aqueous solution. The melting point of water-saturated CO2 does not show a measureable departure from that of the pure system at temperatures lower than ∼200°C and only 10°C at 5 GPa (from 327°C).

Carbon Isotopic Compositions in Carbon Dioxide Measured By Micro-Laser Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Li, J.-J.; Li, R.-X.; Dong, H.; Wang, Zh.-H.; Zhao, B.-S.; Wang, N.; Cheng, J.-H.

2017-05-01

We have prepared a series of 12CO2/13CO2 binary mixtures as standard samples at room temperature. Using microlaser Raman spectroscopy, it was found that the relationship between the 12CO2 mole fractions and the peak area ratios of 12CO2/13CO2 in the Raman spectra of CO2 binary mixtures showed a polynomial correlation. The establishment of the experimental working curve paves the way for estimating the mole fractions of each individual fluid inclusion and determining 13C/12C and δ13C u sing micro-Raman spectroscopy. The Raman spectra of 12CO2 and 13CO2 showed a characteristic peak at 1348 cm-1 with an argon laser at 785 nm, which is perhaps due to the formation of dimers.

Hydrodynamic stability of jets produced by mass accreting systems

NASA Technical Reports Server (NTRS)

Hardee, P. E.

1982-01-01

The existing model for pulsed X-ray emission from the source Hercules X-1 is reviewed. A necessary part of this model is a processing accretion disk which turns the source on and off with 35 day cycle. It is usually assumed that precession of the primary star in this binary system, Hz Hercules, slaves the disk to its precession rate. This model can account for the system behavior in a qualitative manner. Precession of Hz Hercules with 35 day period requires precession of the binary orbit. Pulse arrival times from Herc X-1 have been analyzed for orbital precession. The inclusion of precession does not significantly improve the results obtained assuming a non-precessing orbit. The fluid dynamical stability of extra-galactic jets and the possible consequences of Kelvin-Helmholtz instability at the jet surface external medium interface are considered.

Structural basis for maintenance of bacterial outer membrane lipid asymmetry.

PubMed

Abellón-Ruiz, Javier; Kaptan, Shreyas S; Baslé, Arnaud; Claudi, Beatrice; Bumann, Dirk; Kleinekathöfer, Ulrich; van den Berg, Bert

2017-12-01

The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds 1 , 2 . The defining characteristic of the OM is lipid asymmetry, with phospholipids comprising the inner leaflet and lipopolysaccharides comprising the outer leaflet 1-3 . This asymmetry is maintained by the Mla pathway, a six-component system that is widespread in Gram-negative bacteria and is thought to mediate retrograde transport of misplaced phospholipids from the outer leaflet of the OM to the cytoplasmic membrane 4 . The OM lipoprotein MlaA performs the first step in this process via an unknown mechanism that does not require external energy input. Here we show, using X-ray crystallography, molecular dynamics simulations and in vitro and in vivo functional assays, that MlaA is a monomeric α-helical OM protein that functions as a phospholipid translocation channel, forming a ~20-Å-thick doughnut embedded in the inner leaflet of the OM with a central, amphipathic pore. This architecture prevents access of inner leaflet phospholipids to the pore, but allows outer leaflet phospholipids to bind to a pronounced ridge surrounding the channel, followed by diffusion towards the periplasmic space. Enterobacterial MlaA proteins form stable complexes with OmpF/C 5,6 , but the porins do not appear to play an active role in phospholipid transport. MlaA represents a lipid transport protein that selectively removes outer leaflet phospholipids to help maintain the essential barrier function of the bacterial OM.

Specificity of anti-phospholipid antibodies in infectious mononucleosis: a role for anti-cofactor protein antibodies

PubMed Central

Sorice, M; Pittoni, V; Griggi, T; Losardo, A; Leri, O; Magno, M S; Misasi, R; Valesini, G

2000-01-01

The antigen specificity of anti-phospholipid antibodies in infectious mononucleosis (IM) was studied using ELISA for the detection of anti-β2-glycoprotein I (β2-GPI), anti-annexin V, anti-protein S and anti-prothrombin antibodies and TLC immunostaining for the detection of anti-phospholipid antibodies. This technique enabled us to look at antibodies reacting to ‘pure’ phospholipid antigens in the absence of protein contamination. Sera from 46 patients with IM, 18 with systemic lupus erythematosus (SLE), 21 with primary anti-phospholipid antibody syndrome (PAPS), 50 with Helicobacter pylori infection and 30 healthy blood donors were tested. This study highlights anti-phospholipid antibodies in patients with IM as specific ‘pure’ anti-cardiolipin antibodies, while in PAPS and SLE patients anti-phosphatidylserine and anti-phosphatidylethanolamine antibodies were also found. This investigation also shows that the anti-cardiolipin antibodies found in IM can be present with anti-cofactor protein antibodies. The higher prevalence of anti-cofactor antibodies found in IM sera than in Helicobacter pylori sera may be due to the immunostimulatory effect and/or the polyclonal activation often observed in course of Epstein–Barr virus infection. However, anti-β2-GPI and, to a lesser extent, anti-prothrombin antibodies occur with a significantly lower prevalence in IM than in PAPS patients. This finding suggests that these antibodies should be regarded as the expression of the broad autoimmune syndrome involving the phospholipid-binding plasma proteins. PMID:10792380

1-Oleoyl-2-acetylglycerol stimulates 5-lipoxygenase activity via a putative (phospho)lipid binding site within the N-terminal C2-like domain.

PubMed

Hörnig, Christina; Albert, Dana; Fischer, Lutz; Hörnig, Michael; Rådmark, Olof; Steinhilber, Dieter; Werz, Oliver

2005-07-22

5-Lipoxygenase (5-LO) catalysis is positively regulated by Ca2+ ions and phospholipids that both act via the N-terminal C2-like domain of 5-LO. Previously, we have shown that 1-oleoyl-2-acetylglycerol (OAG) functions as an agonist for human polymorphonuclear leukocytes (PMNL) in stimulating 5-LO product formation. Here we have demonstrated that OAG directly stimulates 5-LO catalysis in vitro. In the absence of Ca2+ (chelated using EDTA), OAG strongly and concentration-dependently stimulated crude 5-LO in 100,000 x g supernatants as well as purified 5-LO enzyme from PMNL. Also, the monoglyceride 1-O-oleyl-rac-glycerol and 1,2-dioctanoyl-sn-glycerol were effective, whereas various phospholipids did not stimulate 5-LO. However, in the presence of Ca2+, OAG caused no stimulation of 5-LO. Also, phospholipids or cellular membranes abolished the effects of OAG. As found previously for Ca2+, OAG renders 5-LO activity resistant against inhibition by glutathione peroxidase activity, and this effect of OAG is reversed by phospholipids. Intriguingly, a 5-LO mutant lacking tryptophan residues (Trp-13, -75, and -102) important for the binding of the 5-LO C2-like domain to phospholipids was not stimulated by OAG. We conclude that OAG directly stimulates 5-LO by acting at a phospholipid binding site located within the C2-like domain.

Blistering of langmuir-blodgett bilayers containing anionic phospholipids as observed by atomic force microscopy.

PubMed Central

Rinia, H A; Demel, R A; van der Eerden, J P; de Kruijff, B

1999-01-01

Asymmetric bilayers of different phospholipid compositions have been prepared by the Langmuir-Blodgett (L-B) method, and imaged by atomic force microscopy (AFM). Such bilayers can function as a model for biological membranes. The first leaflet consisted of zwitterionic phospholipids phosphatidylcholine (PC) or phosphatidylethanolamine (PE). The second leaflet consisted of the anionic phospholipid phosphatidylglycerol (PG), in either the condensed or liquid phase or, for comparison, of PC. Different bilayers showed different morphology. In all bilayers defects in the form of holes were present. In some bilayers with a first leaflet consisting of PC, polygonal line-shaped defects were observed, whereas when the first leaflet consisted of PE, mainly round defects were seen. Not only the shape, but also the amount of defects varied, depending on the condition and the composition of the second leaflet. In most of the PG-containing systems the defects were surrounded by elevations, which reversibly disappeared in the presence of divalent cations. This is the first time that such elevations have been observed on phospholipid bilayers. We propose that they are induced by phospholipid exchange between the two leaflets around the defects, leading to the presence of negatively charged phospholipids in the first leaflet. Because the substrate is also negatively charged, the bilayer around the edges is repelled and lifted up. Since it was found that the elevations are indeed detached from the substrate, we refer to this effect as bilayer blistering. PMID:10465778

Chlamydia trachomatis Scavenges Host Fatty Acids for Phospholipid Synthesis via an Acyl-Acyl Carrier Protein Synthetase*

PubMed Central

Yao, Jiangwei; Dodson, V. Joshua; Frank, Matthew W.; Rock, Charles O.

2015-01-01

The obligate intracellular parasite Chlamydia trachomatis has a reduced genome but relies on de novo fatty acid and phospholipid biosynthesis to produce its membrane phospholipids. Lipidomic analyses showed that 8% of the phospholipid molecular species synthesized by C. trachomatis contained oleic acid, an abundant host fatty acid that cannot be made by the bacterium. Mass tracing experiments showed that isotopically labeled palmitic, myristic, and lauric acids added to the medium were incorporated into C. trachomatis-derived phospholipid molecular species. HeLa cells did not elongate lauric acid, but infected HeLa cell cultures elongated laurate to myristate and palmitate. The elongated fatty acids were incorporated exclusively into C. trachomatis-produced phospholipid molecular species. C. trachomatis has adjacent genes encoding the separate domains of the bifunctional acyl-acyl carrier protein (ACP) synthetase/2-acylglycerolphosphoethanolamine acyltransferase gene (aas) of Escherichia coli. The CT775 gene encodes an acyltransferase (LpaT) that selectively transfers fatty acids from acyl-ACP to the 1-position of 2-acyl-glycerophospholipids. The CT776 gene encodes an acyl-ACP synthetase (AasC) with a substrate preference for palmitic compared with oleic acid in vitro. Exogenous fatty acids were elongated and incorporated into phospholipids by Escherichia coli-expressing AasC, illustrating its function as an acyl-ACP synthetase in vivo. These data point to an AasC-dependent pathway in C. trachomatis that selectively scavenges host saturated fatty acids to be used for the de novo synthesis of its membrane constituents. PMID:26195634

Fluid extraction

DOEpatents

Wai, Chien M.; Laintz, Kenneth E.

1999-01-01

A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

Dynamical Tidal Response of a Rotating Neutron Star

NASA Astrophysics Data System (ADS)

Landry, Philippe; Poisson, Eric

2017-01-01

The gravitational wave phase of a neutron star (NS) binary is sensitive to the deformation of the NS that results from its companion's tidal influence. In a perturbative treatment, the tidal deformation can be characterized by a set of dimensionless constants, called Love numbers, which depend on the NS equation of state. For static NSs, one type of Love number encodes the response to gravitoelectric tidal fields (associated with mass multipole moments), while another does likewise for gravitomagnetic fields (associated with mass currents). A NS subject to a gravitomagnetic tidal field develops internal fluid motions through gravitomagnetic induction; the fluid motions are irrotational, provided the star is non-rotating. When the NS is allowed to rotate, the situation is complicated by couplings between the tidal field and the star's spin. The problem becomes tractable in the slow-rotation limit. In this case, the fluid motions induced by an external gravitomagnetic field are fully dynamical, even if the tidal field is stationary: interior metric and fluid variables are time-dependent, and vary on the timescale of the rotation period. Remarkably, the exterior geometry of the NS remains time-independent.

Ternary Free-Energy Entropic Lattice Boltzmann Model with a High Density Ratio

NASA Astrophysics Data System (ADS)

Wöhrwag, M.; Semprebon, C.; Mazloomi Moqaddam, A.; Karlin, I.; Kusumaatmaja, H.

2018-06-01

A thermodynamically consistent free energy model for fluid flows comprised of one gas and two liquid components is presented and implemented using the entropic lattice Boltzmann scheme. The model allows a high density ratio, up to the order of O (103), between the liquid and gas phases, and a broad range of surface tension ratios, covering partial wetting states where Neumann triangles are formed, and full wetting states where complete encapsulation of one of the fluid components is observed. We further demonstrate that we can capture the bouncing, adhesive, and insertive regimes for the binary collisions between immiscible droplets suspended in air. Our approach opens up a vast range of multiphase flow applications involving one gas and several liquid components.

Kinetic Theories for Biofilms (Preprint)

DTIC Science & Technology

2011-01-01

2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Kinetic Theories for Biofilms 5a. CONTRACT NUMBER 5b...binary complex fluids to develop a set of hydrodynamic models for the two-phase mixture of biofilms and solvent (water). It is aimed to model...kinetics along with the intrinsic molecular elasticity of the EPS network strand modeled as an elastic dumbbell. This theory is valid in both the biofilm

Photo-induced electron transfer method

DOEpatents

Wohlgemuth, R.; Calvin, M.

1984-01-24

The efficiency of photo-induced electron transfer reactions is increased and the back transfer of electrons in such reactions is greatly reduced when a photo-sensitizer zinc porphyrin-surfactant and an electron donor manganese porphyrin-surfactant are admixed into phospholipid membranes. The phospholipids comprising said membranes are selected from phospholipids whose head portions are negatively charged. Said membranes are contacted with an aqueous medium in which an essentially neutral viologen electron acceptor is admixed. Catalysts capable of transferring electrons from reduced viologen electron acceptor to hydrogen to produce elemental hydrogen are also included in the aqueous medium. An oxidizable olefin is also admixed in the phospholipid for the purpose of combining with oxygen that coordinates with oxidized electron donor manganese porphyrin-surfactant.

Symmetry breaking in binary mixtures in closed nanoslits.

PubMed

Berim, Gersh O; Ruckenstein, Eli

2008-04-07

The symmetry breaking (SB) of the fluid density distribution (FDD) in closed nanoslits between two identical parallel solid walls described by Berim and Ruckenstein [J. Chem. Phys. 128, 024704 (2008)] for a single component fluid is examined for binary mixtures on the basis of a nonlocal canonical ensemble density functional theory. As in Monte Carlo simulations, the periodicity of the FDD in one of the lateral (parallel to the wall surfaces) directions, denoted as the x direction, was assumed. In the other lateral direction, y direction, the FDD was considered to be uniform. The molecules of the two components have different diameters and their Lennard-Jones interaction potentials have different energy parameters. It was found that depending on the average fluid density in the slit and mixture composition, SB can occur for both or none of the components but never for only one of them. In the direction perpendicular to the walls (h direction), the FDDs of both components can be asymmetrical about the middle plane between walls. In the x direction, the SB occurs as bumps and bridges enriched in one of the components, whereas the composition of the mixture between them is enriched in the other component. The dependence of the SB states on the length Lx of the FDD period at fixed average densities of the two components was examined for Lx in the range from 10 to 120 molecular diameters of the smaller size component. It was shown that for large Lx, the stable state of the system corresponds to a bridge. Because the free energy of that state decreases monotonically with increasing Lx, one can conclude that the real period is very large (infinite) and that a single bridge exists in the slit.

Symmetry breaking in binary mixtures in closed nanoslits

NASA Astrophysics Data System (ADS)

Berim, Gersh O.; Ruckenstein, Eli

2008-04-01

The symmetry breaking (SB) of the fluid density distribution (FDD) in closed nanoslits between two identical parallel solid walls described by Berim and Ruckenstein [J. Chem. Phys. 128, 024704 (2008)] for a single component fluid is examined for binary mixtures on the basis of a nonlocal canonical ensemble density functional theory. As in Monte Carlo simulations, the periodicity of the FDD in one of the lateral (parallel to the wall surfaces) directions, denoted as the x direction, was assumed. In the other lateral direction, y direction, the FDD was considered to be uniform. The molecules of the two components have different diameters and their Lennard-Jones interaction potentials have different energy parameters. It was found that depending on the average fluid density in the slit and mixture composition, SB can occur for both or none of the components but never for only one of them. In the direction perpendicular to the walls (h direction), the FDDs of both components can be asymmetrical about the middle plane between walls. In the x direction, the SB occurs as bumps and bridges enriched in one of the components, whereas the composition of the mixture between them is enriched in the other component. The dependence of the SB states on the length Lx of the FDD period at fixed average densities of the two components was examined for Lx in the range from 10 to 120 molecular diameters of the smaller size component. It was shown that for large Lx, the stable state of the system corresponds to a bridge. Because the free energy of that state decreases monotonically with increasing Lx, one can conclude that the real period is very large (infinite) and that a single bridge exists in the slit.

Application of the Fokker-Planck molecular mixing model to turbulent scalar mixing using moment methods

NASA Astrophysics Data System (ADS)

Madadi-Kandjani, E.; Fox, R. O.; Passalacqua, A.

2017-06-01

An extended quadrature method of moments using the β kernel density function (β -EQMOM) is used to approximate solutions to the evolution equation for univariate and bivariate composition probability distribution functions (PDFs) of a passive scalar for binary and ternary mixing. The key element of interest is the molecular mixing term, which is described using the Fokker-Planck (FP) molecular mixing model. The direct numerical simulations (DNSs) of Eswaran and Pope ["Direct numerical simulations of the turbulent mixing of a passive scalar," Phys. Fluids 31, 506 (1988)] and the amplitude mapping closure (AMC) of Pope ["Mapping closures for turbulent mixing and reaction," Theor. Comput. Fluid Dyn. 2, 255 (1991)] are taken as reference solutions to establish the accuracy of the FP model in the case of binary mixing. The DNSs of Juneja and Pope ["A DNS study of turbulent mixing of two passive scalars," Phys. Fluids 8, 2161 (1996)] are used to validate the results obtained for ternary mixing. Simulations are performed with both the conditional scalar dissipation rate (CSDR) proposed by Fox [Computational Methods for Turbulent Reacting Flows (Cambridge University Press, 2003)] and the CSDR from AMC, with the scalar dissipation rate provided as input and obtained from the DNS. Using scalar moments up to fourth order, the ability of the FP model to capture the evolution of the shape of the PDF, important in turbulent mixing problems, is demonstrated. Compared to the widely used assumed β -PDF model [S. S. Girimaji, "Assumed β-pdf model for turbulent mixing: Validation and extension to multiple scalar mixing," Combust. Sci. Technol. 78, 177 (1991)], the β -EQMOM solution to the FP model more accurately describes the initial mixing process with a relatively small increase in computational cost.

Mechanism of enhanced oral absorption of morin by phospholipid complex based self-nanoemulsifying drug delivery system.

PubMed

Zhang, Jinjie; Li, Jianbo; Ju, Yuan; Fu, Yao; Gong, Tao; Zhang, Zhirong

2015-02-02

Phospholipid complex (PLC) based self-nanoemulsifying drug delivery system (PLC-SNEDDS) has been developed for efficient delivery of drugs with poor solubility and low permeability. In the present study, a BCS class IV drug and a P-glycoprotein (P-gp) substrate, morin, was selected as the model drug to elucidate the oral absorption mechanism of PLC-SNEDDS. PLC-SNEDDS was superior to PLC in protecting morin from degradation by intestinal enzymes in vitro. In situ perfusion study showed increased intestinal permeability by PLC was duodenum-specific. In contrast, PLC-SNEDDS increased morin permeability in all intestinal segments and induced a change in the main absorption site of morin from colon to ileum. Moreover, ileum conducted the lymphatic transport of PLC-SNEDDS, which was proven by microscopic intestinal visualization of Nile red labeled PLC-SNEDDS and lymph fluids in vivo. Low cytotoxicity and increased Caco-2 cell uptake suggested a safe and efficient delivery of PLC-SNEDDS. The increased membrane fluidity and disrupted actin filaments were closely associated with the increased cell uptake of PLC-SNEDDS. PLC-SNEDDS could be internalized into enterocytes as an intact form in a cholesterol-dependent manner via clathrin-mediated endocytosis and macropinocytosis. The enhanced oral absorption of morin was attributed to the P-gp inhibition by Cremophor RH and the intact internalization of M-PLC-SNEDDS into Caco-2 cells bypassing P-gp recognition. Our findings thus provide new insights into the development of novel nanoemulsions for poorly absorbed drugs.

Pulmonary surfactant concentration during transition from high frequency oscillation to conventional mechanical ventilation.

PubMed

Dargaville, P A; South, M; McDougall, P N

1997-12-01

To test the hypothesis that conventional mechanical ventilation (CV) provides a greater stimulus to secretion of pulmonary surfactant than high frequency oscillatory ventilation (HFO). Sequential examination of surfactant indices in lung lavage fluid in a group of six infants with severe lung disease (group 1), ventilated with HFO and then converted back to CV as their lung disease recovered. A similar group of 10 infants (group 2) ventilated conventionally throughout the course of their illness were studied for comparison. In groups 1 and 2, two sequential tracheal aspirate samples were taken, the first once lung disease was noted to be improving, and the second 48-72 h later. Group 1 infants had converted from HFO to CV during this time. A marked increase in concentration of total surfactant phospholipid (PL) and disaturated phosphatidylcholine (DSPC) was seen in group 1 after transition from HFO to CV; the magnitude of this increase was significantly greater than that sequentially observed in group II (total PL: 9.4-fold increase in group 1 vs 1.8-fold in group 2, P = 0.006; DSPC: group 1 6.4-fold increase vs. group 2 1.7-fold, P = 0.02). These findings suggest that intermittent lung inflation during CV produces more secretion of surfactant phospholipid than continuous alveolar distension on HFO, and raise the possibility that conservation and additional maturation of surfactant elements may occur when the injured lung is ventilated with HFO.

Orally administered phosphatidic acids and lysophosphatidic acids ameliorate aspirin-induced stomach mucosal injury in mice.

PubMed

Tanaka, Tamotsu; Morito, Katsuya; Kinoshita, Masafumi; Ohmoto, Mayumi; Urikura, Mai; Satouchi, Kiyoshi; Tokumura, Akira

2013-04-01

Recent investigations revealed that lysophosphatidic acid (LPA), a phospholipid with a growth factor-like activity, plays an important role in the integrity of the gastrointestinal tract epithelium. This paper attempts to clarify the effect of orally administered phosphatidic acid (PA) and LPA on aspirin-induced gastric lesions in mice. Phospholipids, a free fatty acid, a diacylglycerol and a triglyceride at 1 mM (5.7 μmol/kg body weight) or 0.1 mM were orally administered to mice 0.5 h before oral administration of aspirin (1.7 mmol/kg). The total length of lesions formed on the stomach wall was measured as a lesion index. Formation of LPA from PA in the mouse stomach was examined by in vitro (in stomach lavage fluid), ex vivo (in an isolated stomach) and in vivo (in the stomach of a living mouse) examinations of phospholipase activity. Palmitic acid, dioleoyl-glycerol, olive oil and lysophosphatidylcholine did not affect the aspirin-induced lesions. In contrast, phosphatidylcholine (1 mM), LPA (1 mM) and PA (0.1, 1 mM) significantly reduced the lesion index. Evidence for formation of LPA from PA in the stomach by gastric phospholipase A2 was obtained by in vitro, ex vivo and in vivo experiments. An LPA-specific receptor, LPA2, was found to be localized on the gastric surface-lining cells of mice. Pretreatment with PA-rich diets may prevent nonsteroidal anti-inflammatory drug-induced stomach ulcers.

Effect of the interfacial tension and ionic strength on the thermodynamic barrier associated to the benzocaine insertion into a cell membrane.

PubMed

López Cascales, J J; Oliveira Costa, S D

2013-02-01

The insertion of local anaesthetics into a cell membrane is a key aspect for explaining their activity at a molecular level. It has been described how the potency and response time of local anaesthetics is improved (for clinical applications) when they are dissolved in a solution of sodium bicarbonate. With the aim of gaining insight into the physico-chemical principles that govern the action mechanism of these drugs at a molecular level, simulations of benzocaine in binary lipid bilayers formed by DPPC/DPPS were carried out for different ionic strengths of the aqueous solution. From these molecular dynamic simulations, we observed how the thermodynamic barrier associated with benzocaine insertion into the lipid bilayers diminished exponentially as the fraction of DPPS in the bilayer increased, especially when the ionic strength of the aqueous solution increased. In line with these results, we also observed how this thermodynamic barrier diminished exponentially with the phospholipid/water interfacial tension. Copyright © 2012 Elsevier B.V. All rights reserved.

The bovine seminal plasma protein PDC-109 extracts phosphorylcholine-containing lipids from the outer membrane leaflet.

PubMed

Tannert, Astrid; Kurz, Anke; Erlemann, Karl-Rudolf; Müller, Karin; Herrmann, Andreas; Schiller, Jürgen; Töpfer-Petersen, Edda; Manjunath, Puttaswamy; Müller, Peter

2007-04-01

The bovine seminal plasma protein PDC-109 modulates the maturation of bull sperm cells by removing lipids, mainly phosphatidylcholine and cholesterol, from their cellular membrane. Here, we have characterized the process of extraction of endogenous phospholipids and of their respective analogues. By measuring the PDC-109-mediated release of fluorescent phospholipid analogues from lipid vesicles and from biological membranes (human erythrocytes, bovine epididymal sperm cells), we showed that PDC-109 extracts phospholipids with a phosphorylcholine headgroup mainly from the outer leaflet of these membranes. The ability of PDC-109 to extract endogenous phospholipids from epididymal sperm cells was followed by mass spectrometry, which allowed us to characterize the fatty acid pattern of the released lipids. From these cells, PDC-109 extracted phosphatidylcholine and sphingomyelin that contained an enrichment of mono- and di-unsaturated fatty acids as well as short-chain and lyso-phosphatidylcholine species. Based on the results, a model explaining the phospholipid specificity of PDC-109-mediated lipid release is presented.

Herpes simplex virus 1 induces de novo phospholipid synthesis

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

Sutter, Esther; Oliveira, Anna Paula de; Tobler, Kurt

2012-08-01

Herpes simplex virus type 1 capsids bud at nuclear membranes and Golgi membranes acquiring an envelope composed of phospholipids. Hence, we measured incorporation of phospholipid precursors into these membranes, and quantified changes in size of cellular compartments by morphometric analysis. Incorporation of [{sup 3}H]-choline into both nuclear and cytoplasmic membranes was significantly enhanced upon infection. [{sup 3}H]-choline was also part of isolated virions even grown in the presence of brefeldin A. Nuclei expanded early in infection. The Golgi complex and vacuoles increased substantially whereas the endoplasmic reticulum enlarged only temporarily. The data suggest that HSV-1 stimulates phospholipid synthesis, and thatmore » de novo synthesized phospholipids are inserted into nuclear and cytoplasmic membranes to i) maintain membrane integrity in the course of nuclear and cellular expansion, ii) to supply membrane constituents for envelopment of capsids by budding at nuclear membranes and Golgi membranes, and iii) to provide membranes for formation of transport vacuoles.« less

Controlled release of astaxanthin from nanoporous silicified-phospholipids assembled boron nitride complex for cosmetic applications

NASA Astrophysics Data System (ADS)

Lee, Hye Sun; Sung, Dae Kyung; Kim, Sung Hyun; Choi, Won Il; Hwang, Ee Tag; Choi, Doo Jin; Chang, Jeong Ho

2017-12-01

Nanoporous silicified-phospholipids assembled boron nitride (nSPLs@BN) powder was prepared and demonstrated for use in controlled release of anti-oxidant astaxanthin (AX) as a cosmetic application. The nanoporous silicified phospholipids (nSPLs) were obtained by the silicification with tetraethyl orthosilicate (TEOS) of the hydrophilic region of phospholipid bilayers. This process involved the co-assembly of chemically active phospholipid bilayers within the porous silica matrix. In addition, nSPLs@BN was characterized using several analytical techniques and tested to assess their efficiency as drug delivery systems. We calculated the maximum release amounts as a function of time and various pH. The release rate of AX from the nSPLs@BN for the initial 24 h was 10.7 μmol/(h mg) at pH 7.4. Furthermore, we determined the antioxidant activity (KD) for the released AX with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical and the result was 34.6%.

Lipidomic profiling of dried seahorses by hydrophilic interaction chromatography coupled to mass spectrometry.

PubMed

Shen, Qing; Dai, Zhiyuan; Huang, Yao-Wen; Cheung, Hon-Yeung

2016-08-15

Dried seahorse is a precious raw food material for cooking soups. In this study, a lipidomics strategy using the techniques of solid-phase extraction (SPE) and hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-QTOF/MS) was developed for extraction, visualization, and quantification of phospholipids in dried seahorses. The parameters of SPE were optimized, and 1 mL of sample and chloroform/methanol (1:2, v/v) were found to be the best loading volume and eluting solvent, respectively. Afterwards, each phospholipid class was successfully separated on a HILIC column and analyzed by mass spectrometry. A total of 50 phospholipid molecular species were identified and determined, including 15 phosphatidylcholines (PCs), 14 phosphatidylethanolamines (PEs), 12 phosphatidylinositols (PIs) and 9 phosphatidylserines (PSs). In comparison to previously methods, this strategy was robust and efficient in extraction, characterization, and determination of phospholipids. The dried seahorse was found to contain large amounts of polyunsaturated fatty acyl phospholipids which are beneficial to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of sex and dietary fat intake on the fatty acid composition of phospholipids and triacylglycerol in rat heart

PubMed Central

Slater-Jefferies, Joanne L.; Hoile, Samuel P.; Lillycrop, Karen A.; Townsend, Paul A.; Hanson, Mark A.; Burdge, Graham C.

2010-01-01

Variations in the fatty acid composition of lipids in the heart alter its function and susceptibility to ischaemic injury. We investigated the effect of sex and dietary fat intake on the fatty acid composition of phospholipids and triacylglycerol in rat heart. Rats were fed either 40 or 100 g/kg fat (9:1 lard:soybean oil) from weaning until day 105. There were significant interactive effects of sex and fat intake on the proportions of fatty acids in heart phospholipids, dependent on phospholipid classes. 20:4n-6, but not 22:6n-3, was higher in phospholipids in females than males fed a low, but not a high, fat diet. There was no effect of sex on the composition of triacylglycerol. These findings suggest that sex is an important factor in determining the incorporation of dietary fatty acids into cardiac lipids. This may have implications for sex differences in susceptibility to heart disease. PMID:20719489

Fluid overload and kidney failure in children with severe sepsis and septic shock: A cohort study.

PubMed

Naveda Romero, Omar E; Naveda Meléndez, Andrea F

2017-04-01

In children with sepsis, fluid overload as a result of an aggressive fluid replacement or excessive fluid administration may result in kidney impairment and increased mortality. Objective. To determine the association between fluid overload and the rate of kidney failure in a group of children with severe sepsis and septic shock. This was a prospective cohort study conducted in the intensive care unit of Hospital Universitario de Pediatría “Dr. Agustín Zubillaga” (Barquisimeto, Lara State, Venezuela), between March 2013 and May 2016, in children with severe sepsis or septic shock. One hundred and forty-nine patients were included in the analysis. Sepsis predominated in 59.7% of cases; patients' average age was 6.4 ± 3.3 years old, their average weight was 17.8 ± 3.6 kg, 30.2% had fluid overload, and overall mortality was 25.5%. Kidney failure occurred in 16.1% of cases. A binary logistic regression model was used to identify fluid overload (odds ratio [OR]: 1.5; 95% confidence interval [CI]: 1.2-4.9, p = 0.028) and shock for more than 2 days (OR: 1.7; 95% CI: 1.3-6.3, p = 0.039) as independent predictors of kidney failure. In addition, a significant increase in the risk of mortality among children with kidney failure and fluid overload was observed as per the Kaplan-Meier method (p= 0.019). Fluid overload and shock for more than 2 days increase the risk for kidney failure in critically ill children with severe sepsis and septic shock.

Interactions of amelogenin with phospholipids

DOE PAGES

Bekshe Lokappa, Sowmya; Chandrababu, Karthik Balakrishna; Dutta, Kaushik; ...

2014-11-22

Amelogenin protein has the potential to interact with other enamel matrix proteins, mineral, and cell surfaces. In this paper, we investigated the interactions of recombinant amelogenin rP172 with small unilamellar vesicles as model membranes, toward the goal of understanding the mechanisms of amelogenin–cell interactions during amelogenesis. Dynamic light scattering (DLS), fluorescence spectroscopy, circular dichroism (CD), and nuclear magnetic resonance (NMR) were used. In the presence of phospholipid vesicles, a blue shift in the Trp fluorescence emission maxima of rP172 was observed (~334 nm) and the Trp residues of rP172 were inaccessible to the aqueous quencher acrylamide. DLS studies indicated complexationmore » of rP172 and phospholipids, although the possibility of fusion of phospholipids following amelogenin addition cannot be ruled out. NMR and CD studies revealed a disorder–order transition of rP172 in a model membrane environment. Strong fluorescence resonance energy transfer from Trp in rP172 to DNS-bound-phospholipid was observed, and fluorescence polarization studies indicated that rP172 interacted with the hydrophobic core region of model membranes. Finally, our data suggest that amelogenin has ability to interact with phospholipids and that such interactions may play key roles in enamel biomineralization as well as reported amelogenin signaling activities.« less

Polyhydroxyalkanoate (PHA) Granules Have no Phospholipids.

PubMed

Bresan, Stephanie; Sznajder, Anna; Hauf, Waldemar; Forchhammer, Karl; Pfeiffer, Daniel; Jendrossek, Dieter

2016-05-25

Polyhydroxybutyrate (PHB) granules, also designated as carbonosomes, are supra-molecular complexes in prokaryotes consisting of a PHB polymer core and a surface layer of structural and functional proteins. The presence of suspected phospholipids in the surface layer is based on in vitro data of isolated PHB granules and is often shown in cartoons of the PHB granule structure in reviews on PHB metabolism. However, the in vivo presence of a phospholipid layer has never been demonstrated. We addressed this topic by the expression of fusion proteins of DsRed2EC and other fluorescent proteins with the phospholipid-binding domain (LactC2) of lactadherin in three model organisms. The fusion proteins specifically localized at the cell membrane of Ralstonia eutropha but did not co-localize with PHB granules. The same result was obtained for Pseudomonas putida, a species that accumulates another type of polyhydroxyalkanoate (PHA) granules related to PHB. Notably, DsRed2EC-LactC2 expressed in Magnetospirillum gryphiswaldense was detected at the position of membrane-enclosed magnetosome chains and at the cytoplasmic membrane but not at PHB granules. In conclusion, the carbonosomes of representatives of α-proteobacteria, β-proteobacteria and γ-proteobacteria have no phospholipids in vivo and we postulate that the PHB/PHA granule surface layers in natural producers generally are free of phospholipids and consist of proteins only.

Lipid requirement of the membrane sodium-plus-potassium ion-dependent adenosine triphosphatase system.

PubMed Central

Wheeler, K P; Walker, J A; Barker, D M

1975-01-01

The dependence of the (Na-++K-+)-dependent ATPase (adenosine triphosphatase) (EC 3.6.1.3) on lipid has been examined in a number of different ways, with the use of various preparations from kidney tissue. The main findings were as follows. (1) The ATPase activities of the preparations examined were closely correlated with their total phospholipid content. (2) Extraction of the ATPase with deoxycholate or Lubrol W, combined with suitable salt-fractionation and washing procedures, removed phospholipid, cholesterol and enzymic activity in parallel; but activity was completely lost before all lipid had been removed. (3) The loss of activity could not be attributed to inhibition by residual detergent. (4) No selective removal of any particular phospholipid class by detergent could be detected. (5) Consistent reactivation of the Lubrol-extracted enzymes was obtained by adding dispersions of exogenous phospholipid, but only some, bearing a net negative charge, such as phosphatidylserine and phosphatidylglycerol, were effective. (6) The degree of reactivation was correlated with the amount of residual activity remaining after lipid depletion. (7) Partial purification of the ATPase, giving a 50-fold increase in specific activity, was not accompanied by selective enhancement of any particular class of phospholipid. We conclude that although the ATPase is dependent on phospholipid, only the reactivation results provide evidence for specificity. PMID:125082

Impact of Lipid Oxidization on Vertical Structures and Electrostatics of Phospholipid Monolayers Revealed by Combination of Specular X-ray Reflectivity and Grazing-Incidence X-ray Fluorescence.

PubMed

Korytowski, Agatha; Abuillan, Wasim; Makky, Ali; Konovalov, Oleg; Tanaka, Motomu

2015-07-30

The influence of phospholipid oxidization of floating monolayers on the structure perpendicular to the global plane and on the density profiles of ions near the lipid monolayer has been investigated by a combination of grazing incidence X-ray fluorescence (GIXF) and specular X-ray reflectivity (XRR). Systematic variation of the composition of the floating monolayers unravels changes in the thickness, roughness and electron density of the lipid monolayers as a function of molar fraction of oxidized phospholipids. Simultaneous GIXF measurements enable one to qualitatively determine the element-specific density profiles of monovalent (K(+) or Cs(+)) and divalent ions (Ca(2+)) in the vicinity of the interface in the presence and absence of two types of oxidized phospholipids (PazePC and PoxnoPC) with high spatial accuracy (±5 Å). We found the condensation of Ca(2+) near carboxylated PazePC was more pronounced compared to PoxnoPC with an aldehyde group. In contrast, the condensation of monovalent ions could hardly be detected even for pure oxidized phospholipid monolayers. Moreover, pure phospholipid monolayers exhibited almost no ion specific condensation near the interface. The quantitative studies with well-defined floating monolayers revealed how the elevation of lipid oxidization level alters the structures and functions of cell membranes.

Preparation and evaluation of a self-emulsifying drug delivery system of etoposide-phospholipid complex.

PubMed

Wu, Zhongbin; Guo, Dan; Deng, Li; Zhang, Yue; Yang, Qiuxia; Chen, Jianming

2011-01-01

The aim of this study was to develop a new phospholipid complex self-emulsifying drug delivery system (PC-SEDDS) to enhance bioavailability of oral etoposide, a drug with poor water solubility. Etoposide-phospholipid complex (EPC) was prepared by reacting etoposide and phospholipid in tetrahydrofuran and confirmed as a phospholipid compound by differential scanning calorimetry (DSC). Solubility of EPC and etoposide was determined in various vehicles. Pseudoternary phase diagrams were constructed to identify the efficient self-emulsification region of EPC-SEDDS, and the effects of oil concentration, drug loading, and aqueous media on droplet size were investigated. The optimal formulation of EPC-SEDDS was EPC:octyl and decyl monoglyceride (ODO):Cremopher EL:PEG-400 (1:20:48:32) (w/w/w/w). Compared with etoposide-phospholipid complex suspension (EPCS) and etoposide suspension (ES), cumulative release of etoposide from EPC-SEDDS increased by 1.31 and 2.65 fold at 24 hours, respectively. Compared with ES, relative bioavailability of EPC-SEDDS, E-SEDDS, and EPCS after oral administration in rats was enhanced by 60.21-, 44.9-, and 8.44- fold, respectively. The synergistic effect between PC and SEDDS contributed to the enhanced bioavailability of etoposide. It was concluded that PC-SEDDS proved to be a potential system for delivering orally administered hydrophobic compounds including etoposide.

Enhanced incorporation of dietary DHA into lymph phospholipids by altering its molecular carrier

PubMed Central

Subbaiah, Papasani V.; Dammanahalli, Karigowda J.; Yang, Peng; Bi, Jian; O’Donnell, J. Michael

2016-01-01

Several previous studies indicated that for optimal uptake by the brain, docosahexaenoic acid (DHA) should be present as phospholipid in the plasma. However most of dietary DHA is absorbed as triacylglycerol (TAG) because it is released as free fatty acid during digestion of either TAG-DHA (fish oil) or sn-2-DHA phospholipid (krill oil), and subsequently incorporated into TAG of chylomicrons. We tested the hypothesis that the absorption of DHA as phospholipid can be increased if it is present in the sn-1 position of dietary phospholipid or in lysophosphatidylcholine (LPC), because it would escape the hydrolysis by pancreatic phospholipase A2. We infused micelle containing the DHA either as LPC or as free acid, into the duodenum of lymph cannulated rats, and analyzed the chylomicrons and HDL of the lymph for the DHA-containing lipids. The results show that while the total amount of DHA absorbed was comparable from the two types of micelle, the percentage of DHA recovered in lymph phospholipids was 5 times greater with LPC-DHA, compared to free DHA. Furthermore, the amount of DHA recovered in lymph HDL was increased by 2-fold when LPC-DHA micelle was infused. These results could potentially lead to a novel strategy to increase brain DHA levels through the diet. PMID:27178174

Phospholipid epitopes for mouse antibodies against bromelain-treated mouse erythrocytes.

PubMed Central

Kawaguchi, S

1987-01-01

The reactivity of mouse antibodies against bromelain-treated mouse erythrocytes (BrMRBC) with phospholipid epitopes was assessed by ELISA, using four clones of monoclonal anti-BrMRBC antibodies that had idiotypes distinct from one another. The four antibodies could bind to low-density lipoproteins (LDL) from human and chicken, but not to LDL from mouse and rat. As to liposomes of natural phospholipids, all the clones reacted with liposomes of phosphatidylcholine, and some of them could react with liposomes of sphingomyelin, phosphatidylglycerol, phosphatidylic acid or cardiolipin. For liposomes of synthetic phosphatidylcholine with different fatty acids, the length of carbon chains and the number of unsaturated carbon chains of the fatty acids markedly affected the binding of each monoclonal antibody to the liposomes. The addition of dicetyl phosphate or stearylamine to phosphatidylcholine liposomes changed the reactivity of the liposomes. These results support the view that mouse anti-BrMRBC antibodies can recognize appropriately spaced phosphorylcholine residues on the surface of phospholipid liposomes, LDL and cells. The four clones had similar capacities for binding to LDL as well as to BrMRBC, but they had obviously different capacities for binding to phospholipid liposomes; the epitopes on phospholipid liposomes used in the present study were not so perfect as to react well with every anti-BrMRBC antibody. PMID:2443446

Saccharomyces Cerevisiae Cho2 Mutants Are Deficient in Phospholipid Methylation and Cross-Pathway Regulation of Inositol Synthesis

PubMed Central

Summers, E. F.; Letts, V. A.; McGraw, P.; Henry, S. A.

1988-01-01

Five allelic Saccharomyces cerevisiae mutants deficient in the methylation of phosphatidylethanolamine (PE) have been isolated, using two different screening techniques. Biochemical analysis suggested that these mutants define a locus, designated CHO2, that may encode a methyltransferase. Membranes of cho2 mutant cells grown in defined medium contain approximately 10% phosphatidylcholine (PC) and 40-50% PE as compared to wild-type levels of 40-45% PC and 15-20% PE. In spite of this greatly altered phospholipid composition, cho2 mutant cells are viable in defined medium and are not auxotrophic for choline or other phospholipid precursors such as monomethylethanolamine (MME). However, analysis of yeast strains carrying more than one mutation affecting phospholipid biosynthesis indicated that some level of methylated phospholipid is essential for viability. The cho2 locus was shown by tetrad analysis to be unlinked to other loci affecting phospholipid synthesis. Interestingly, cho2 mutants and other mutant strains that produce reduced levels of methylated phospholipids are unable to properly repress synthesis of the cytoplasmic enzyme inositol-1-phosphate synthase. This enzyme was previously shown to be regulated at the level of mRNA abundance in response to inositol and choline in the growth medium. We cloned the CHO2 gene on a 3.6-kb genomic DNA fragment and created a null allele of cho2 by disrupting the CHO2 gene in vivo. The cho2 disruptant, like all other cho2 mutants, is viable, exhibits altered regulation of inositol biosynthesis and is not auxotrophic for choline or MME. PMID:3066687

Milk phospholipid's protective effects against UV damage in skin equivalent models

NASA Astrophysics Data System (ADS)

Dargitz, Carl; Russell, Ashley; Bingham, Michael; Achay, Zyra; Jimenez-Flores, Rafael; Laiho, Lily H.

2012-03-01

Exposure of skin tissue to UV radiation has been shown to cause DNA photodamage. If this damaged DNA is allowed to replicate, carcinogenesis may occur. DNA damage is prevented from being passed on to daughter cells by upregulation of the protein p21. p21 halts the cells cycle allowing the cell to undergo apoptosis, or repair its DNA before replication. Previous work suggested that milk phospholipids may possess protective properties against UV damage. In this study, we observed cell morphology, cell apoptosis, and p21 expression in tissue engineered epidermis through the use of Hematoxylin and Eosin staining, confocal microscopy, and western blot respectively. Tissues were divided into four treatment groups including: a control group with no UV and no milk phospholipid treatment, a group exposed to UV alone, a group incubated with milk phospholipids alone, and a group treated with milk phospholipids and UV. All groups were incubated for twenty-four hours after treatment. Tissues were then fixed, processed, and embedded in paraffin. Performing western blots resulted in visible p21 bands for the UV group only, implying that in every other group, p21 expression was lesser. Numbers of apoptotic cells were determined by observing the tissues treated with Hoechst dye under a confocal microscope, and counting the number of apoptotic and total cells to obtain a percentage of apoptotic cells. We found a decrease in apoptotic cells in tissues treated with milk phospholipids and UV compared to tissues exposed to UV alone. Collectively, these results suggest that milk phospholipids protect cell DNA from damage incurred from UV light.

Effect of intravenous omega-3 fatty acid infusion and hemodialysis on fatty acid composition of free fatty acids and phospholipids in patients with end-stage renal disease.

PubMed

Madsen, Trine; Christensen, Jeppe Hagstrup; Toft, Egon; Aardestrup, Inge; Lundbye-Christensen, Søren; Schmidt, Erik B

2011-01-01

Patients treated with hemodialysis (HD) have been reported to have decreased levels of ω-3 polyunsaturated fatty acids (PUFAs) in plasma and cells. The aim of this study was to investigate the effect of ω-3 PUFAs administered intravenously during HD, as well as the effect of HD treatment, on the fatty acid composition of plasma free fatty acids (FFAs), plasma phospholipids, and platelet phospholipids. Forty-four HD patients were randomized to groups receiving either a single dose of a lipid emulsion containing 4.1 g of ω-3 PUFAs or placebo (saline) administered intravenously during HD. Blood was drawn immediately before (baseline) and after (4 hours) HD and before the next HD session (48 hours). Fatty acid composition was measured using gas chromatography. The increase in ω-3 FFAs was greater in the ω-3 PUFA group compared with the placebo group, whereas the increase in total FFAs was similar between the 2 groups. In the ω-3 PUFA group, ω-3 PUFAs in plasma phospholipids were higher after 48 hours than at baseline, and in platelet phospholipids, ω-3 PUFAs increased after 4 hours. In the placebo group, no changes were observed in ω-3 PUFAs in plasma and platelet phospholipids. Intravenous ω-3 PUFAs administered during HD caused a transient selective increase in ω-3 FFA concentration. Furthermore, ω-3 PUFAs were rapidly incorporated into platelets, and the content of ω-3 PUFAs in plasma phospholipids increased after 48 hours.

Dietary DHA supplementation causes selective changes in phospholipids from different brain regions in both wild type mice and the Tg2576 mouse model of Alzheimer's disease

PubMed Central

Bascoul-Colombo, Cécile; Guschina, Irina A.; Maskrey, Benjamin H.; Good, Mark; O'Donnell, Valerie B.; Harwood, John L.

2016-01-01

Alzheimer's disease (AD) is of major concern in ageing populations and we have used the Tg2576 mouse model to understand connections between brain lipids and amyloid pathology. Because dietary docosahexaenoic acid (DHA) has been identified as beneficial, we compared mice fed with a DHA-supplemented diet to those on a nutritionally-sufficient diet. Major phospholipids from cortex, hippocampus and cerebellum were separated and analysed. Each phosphoglyceride had a characteristic fatty acid composition which was similar in cortex and hippocampus but different in the cerebellum. The biggest changes on DHA-supplementation were within ethanolamine phospholipids which, together with phosphatidylserine, had the highest proportions of DHA. Reciprocal alterations in DHA and arachidonate were found. The main diet-induced alterations were found in ethanolamine phospholipids, (and included their ether derivatives), as were the changes observed due to genotype. Tg mice appeared more sensitive to diet with generally lower DHA percentages when on the standard diet and higher relative proportions of DHA when the diet was supplemented. All four major phosphoglycerides analysed showed age-dependent decreases in polyunsaturated fatty acid contents. These data provide, for the first time, a detailed evaluation of phospholipids in different brain areas previously shown to be relevant to behaviour in the Tg2576 mouse model for AD. The lipid changes observed with genotype are consistent with the subtle alterations found in AD patients, especially for the ethanolamine phospholipid molecular species. They also emphasise the contrasting changes in fatty acid content induced by DHA supplementation within individual phospholipid classes. PMID:26968097

Microlayered flow structure around an acoustically levitated droplet under a phase-change process

PubMed Central

Hasegawa, Koji; Abe, Yutaka; Goda, Atsushi

2016-01-01

The acoustic levitation method (ALM) has found extensive applications in the fields of materials science, analytical chemistry, and biomedicine. This paper describes an experimental investigation of a levitated droplet in a 19.4-kHz single-axis acoustic levitator. We used water, ethanol, water/ethanol mixture, and hexane as test samples to investigate the effect of saturated vapor pressure on the flow field and evaporation process using a high-speed camera. In the case of ethanol, water/ethanol mixtures with initial ethanol fractions of 50 and 70 wt%, and hexane droplets, microlayered toroidal vortexes are generated in the vicinity of the droplet interface. Experimental results indicate the presence of two stages in the evaporation process of ethanol and binary mixture droplets for ethanol content >10%. The internal and external flow fields of the acoustically levitated droplet of pure and binary mixtures are clearly observed. The binary mixture of the levitated droplet shows the interaction between the configurations of the internal and external flow fields of the droplet and the concentration of the volatile fluid. Our findings can contribute to the further development of existing theoretical prediction. PMID:28725723

Diacyl, alkenyl, and alkyl ether phospholipids in ejaculated, in utero-, and in vitro-incubated porcine spermatozoa.

PubMed

Evans, R W; Weaver, D E; Clegg, E D

1980-02-01

The phospholipids of porcine spermatozoa were analyzed by a hydrolytic procedure directly after ejaculation, and after incubation for 120 min in vitro or in ligated uterine segments of females with induced estrus. Total phospholipid content of ejaculated sperm was 65.7 micro g lipid P per 10(9) sperm, of which 41% was alkyl ether and 23% was alkenyl ether glycerophospholipid. All of the ether phospholipids were choline and ethanolamine glycerophospholipids. In order of decreasing amount (% of total phospholipid), the phospholipids were choline and ethanolamine glycerophospholipids (49.9 and 28.2), sphingolipid (10.6), cardiolipin (5.5), phosphatidylinositol (2.3), phosphatidic acid (1.5), phosphatidylserine (1.2), and phosphatidylglycerol (0.8). Phosphorus-containing sphingolipid separated into two components during thin-layer chromatography. Sphingosine was the only long-chain base identified in either band. Major fatty acids in the band with lower R(f) were 16:0 (56%), 20:0 (23%), and 18:0 (11%) plus smaller amounts of 14:0, 18:1, and 22:0, while those in the band with higher R(f) were 14:0 (30%), 16:0 (45%), and 18:1 (12%) plus smaller amounts of 18:0, 20:0, and 22:0. Choline was the only water-soluble base present in the lower R(f) sphingomyelin while ethanolamine was prevalent in the higher R(f) component. Incubation of washed spermatozoa in Ca(2+)-free Ringer-fructose at 37 degrees C for 2 hr produced no significant change in the level of any of the phospholipids. Incubation of washed sperm in the uterus for 2 hr, in the presence of oviductal secretions, produced an increase in phosphatidylcholine from 7.2 to 10.2 micro g lipid P per 10(9) sperm.-Evans, R. W., D. E. Weaver, and E. D. Clegg. Diacyl, alkenyl, and alkyl ether phospholipids in ejaculated, in utero-, and in vitro-incubated porcine spermatozoa.

Pulmonary Surfactant Model Systems Catch the Specific Interaction of an Amphiphilic Peptide with Anionic Phospholipid

PubMed Central

Nakahara, Hiromichi; Lee, Sannamu; Shibata, Osamu

2009-01-01

Interfacial behavior was studied in pulmonary surfactant model systems containing an amphiphilic α-helical peptide (Hel 13-5), which consists of 13 hydrophobic and five hydrophilic amino acid residues. Fully saturated phospholipids of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) were utilized to understand specific interactions between anionic DPPG and cationic Hel 13-5 for pulmonary functions. Surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms of DPPG/Hel 13-5 and DPPC/DPPG (4:1, mol/mol)/Hel 13-5 preparations were measured to obtain basic information on the phase behavior under compression and expansion processes. The interaction leads to a variation in squeeze-out surface pressures against a mole fraction of Hel 13-5, where Hel 13-5 is eliminated from the surface on compression. The phase behavior was visualized by means of Brewster angle microscopy, fluorescence microscopy, and atomic force microscopy. At low surface pressures, the formation of differently ordered domains in size and shape is induced by electrostatic interactions. The domains independently grow upon compression to high surface pressures, especially in the DPPG/Hel 13-5 system. Under the further compression process, protrusion masses are formed in AFM images in the vicinity of squeeze-out pressures. The protrusion masses, which are attributed to the squeezed-out Hel 13-5, grow larger in lateral size with increasing DPPG content in phospholipid compositions. During subsequent expansion up to 35 mN m−1, the protrusions retain their height and lateral diameter for the DPPG/Hel 13-5 system, whereas the protrusions become smaller for the DPPC/Hel 13-5 and DPPC/DPPG/Hel 13-5 systems due to a reentrance of the ejected Hel 13-5 into the surface. In this work we detected for the first time, to our knowledge, a remarkably large hysteresis loop for cyclic ΔV-A isotherms of the binary DPPG/Hel 13-5 preparation. This exciting phenomenon suggests that the specific interaction triggers two completely independent processes for Hel 13-5 during repeated compression and expansion: 1), squeezing-out into the subsolution; and 2), and close packing as a monolayer with DPPG at the interface. These characteristic processes are also strongly supported by atomic force microscopy observations. The data presented here provide complementary information on the mechanism and importance of the specific interaction between the phosphatidylglycerol headgroup and the polarized moiety of native surfactant protein B for biophysical functions of pulmonary surfactants. PMID:19217859

Characterization of fluids and fluid-fluid interaction by fiber optic refractive index sensor measurements

NASA Astrophysics Data System (ADS)

Schmidt-Hattenberger, C.; Weiner, M.; Liebscher, A.; Spangenberg, E.

2009-04-01

A fiber optic refractive index sensor is tested for continuous monitoring of fluid-fluid and fluid-gas interactions within the frame of laboratory investigations of CO2 storage, monitoring and safety technology research (COSMOS project, "Geotechnologien" program). The sensor bases on a Fabry-Perot white light interferometer technique, where the refractive index (RI) of the solution under investigation is measured by variation of the liquid-filled Fabry-Perot optical cavity length. Such sensor system is typically used for measuring and controlling oil composition and also fluid quality. The aim of this study is to test the application of the fiber optic refractive index sensor for monitoring the CO2 dissolution in formation fluids (brine, oil, gas) of CO2 storage sites. Monitoring and knowledge of quantity and especially rate of CO2 dissolution in the formation fluid is important for any assessment of long-term risks of CO2 storage sites. It is also a prerequisite for any precise reservoir modelling. As a first step we performed laboratory experiments in standard autoclaves on a variety of different fluids and fluid mixtures (technical alcohols, pure water, CO2, synthetic brines, natural formation brine from the Ketzin test site). The RI measurements are partly combined with default electrical conductivity and sonic velocity measurements. The fiber optic refractive index sensor system allows for RI measurements within the range 1.0000 to 1.7000 RI with a resolution of approximately 0.0001 RI. For simple binary fluid mixtures first results indicate linear relationships between refractive indices and fluid composition. Within the pressure range investigated (up to 60 bar) the data suggest only minor changes of RI with pressure. Further, planned experiments will focus on the determination of i) the temperature dependency of RI, ii) the combined effects of pressure and temperature on RI, and finally iii) the kinetics of CO2 dissolution in realistic formation fluids.

Phospholipids as Biomarkers for Excessive Alcohol Use

DTIC Science & Technology

2015-10-01

Epub 2015 Apr 23. PubMed PMID: 25960184; PubMed Central PMCID: PMC4495663. 6. Liangpunsakul S. ChREBP, SIRT1 and ethanol metabolism - a complicated...AWARD NUMBER: W81XWH-12-1-0497 TITLE: Phospholipids as Biomarkers for Excessive Alcohol Use PRINCIPAL INVESTIGATOR: Suthat Liangpunsakul...2015 2. REPORT TYPE Annual 3. DATES COVERED 15Sept2014 - 14Sep2015 4. TITLE AND SUBTITLE Phospholipids as Biomarkers for Excessive Alcohol Use 5a

Spectroscopic and calorimetric investigations on the influence of calcium ions on the polyamine negatively charged phospholipid molecular interactions

NASA Astrophysics Data System (ADS)

Bertoluzza, Alessandro; Bonora, S.; Fini, G.; Morelli, M. A.

1993-06-01

Polyamines do not interact with neutral phospholipids (phosphatidylcholines) but they do interact in the presence of bivalent and trivalent cations. The effect of polyvalent cations is explained in terms of dehydration of the bilayer surface. Polyamines interact strongly with negatively charged phospholipids; the presence of bivalent and trivalent cations do not change sensitively the type of interaction between polyamines and phosphatidic acids.

Phosphatidic acid is a major phospholipid class in reproductive organs of Arabidopsis thaliana.

PubMed

Yunus, Ian Sofian; Cazenave-Gassiot, Amaury; Liu, Yu-Chi; Lin, Ying-Chen; Wenk, Markus R; Nakamura, Yuki

2015-01-01

Phospholipids are the crucial components of biological membranes and signal transduction. Among different tissues, flower phospholipids are one of the least characterized features of plant lipidome. Here, we report that floral reproductive organs of Arabidopsis thaliana contain high levels of phosphatidic acid (PA), a known lipid second messenger. By using floral homeotic mutants enriched with specific floral organs, lipidomics study showed increased levels of PA species in ap3-3 mutant with enriched pistils. Accompanied gene expression study for 7 diacylglycerol kinases and 11 PA phosphatases revealed distinct floral organ specificity, suggesting an active phosphorylation/dephosphorylation between PA and diacylglycerol in flowers. Our results suggest that PA is a major phospholipid class in floral reproductive organs of A. thaliana.

Biomass measurement of methane forming bacteria in environmental samples

NASA Technical Reports Server (NTRS)

Martz, R. F.; Sebacher, D. I.; White, D. C.

1983-01-01

Methane-forming bacteria contain unusual phytanylglycerol ether phospholipids which can be extracted from the bacteria in sediments and assayed quantitatively by high performance liquid chromatography (HPLC). In this procedure the lipids were extracted, the phospholipids recovered, hydrolyzed, purified by thin layer chromatography, derivatized and assayed by HPLC. Ether lipids were recovered quantitatively from Methanobacterium thermoautotrophicum and sediments at levels as low as 8 x 10(-14) moles. In freshwater and marine sediments the flux of methane to the atmosphere and the methane levels in the pore water reflects the recovery of the phytanyl glycerol ether lipid 'signature'. The proportion of the ether phospholipid to the total recoverable phospholipid was highest in anaerobic digester sewage sludge and deeper subsurface freshwater sediment horizons.

Photo-induced electron transfer method

DOEpatents

Wohlgemuth, Roland; Calvin, Melvin

1984-01-01

The efficiency of photo-induced electron transfer reactions is increased and the back transfer of electrons in such reactions is greatly reduced when a photo-sensitizer zinc porphyrin-surfactant and an electron donor manganese porphyrin-surfactant are admixed into phospho-lipid membranes. The phospholipids comprising said membranes are selected from phospholipids whose head portions are negatively charged. Said membranes are contacted with an aqueous medium in which an essentially neutral viologen electron acceptor is admixed. Catalysts capable of transfering electrons from reduced viologen electron acceptor to hydrogen to produce elemental hydrogen are also included in the aqueous medium. An oxidizable olefin is also admixed in the phospholipid for the purpose of combining with oxygen that coordinates with oxidized electron donor manganese porphyrin-surfactant.

In situ production of titanium dioxide nanoparticles in molten salt phase for thermal energy storage and heat-transfer fluid applications

NASA Astrophysics Data System (ADS)

Lasfargues, Mathieu; Bell, Andrew; Ding, Yulong

2016-06-01

In this study, TiO2 nanoparticles (average particle size 16 nm) were successfully produced in molten salt phase and were showed to significantly enhance the specific heat capacity of a binary eutectic mixture of sodium and potassium nitrate (60/40) by 5.4 % at 390 °C and 7.5 % at 445 °C for 3.0 wt% of precursors used. The objective of this research was to develop a cost-effective alternate method of production which is potentially scalable, as current techniques utilized are not economically viable for large quantities. Enhancing the specific heat capacity of molten salt would promote more competitive pricing for electricity production by concentrating solar power plant. Here, a simple precursor (TiOSO4) was added to a binary eutectic mixture of potassium and sodium nitrate, heated to 450 °C, and cooled to witness the production of nanoparticles.

In Situ Production of Copper Oxide Nanoparticles in a Binary Molten Salt for Concentrated Solar Power Plant Applications

PubMed Central

Lasfargues, Mathieu; Stead, Graham; Amjad, Muhammad; Ding, Yulong; Wen, Dongsheng

2017-01-01

Seeding nanoparticles in molten salts has been shown recently as a promising way to improve their thermo-physical properties. The prospect of such technology is of interest to both academic and industrial sectors in order to enhance the specific heat capacity of molten salt. The latter is used in concentrated solar power plants as both heat transfer fluid and sensible storage. This work explores the feasibility of producing and dispersing nanoparticles with a novel one pot synthesis method. Using such a method, CuO nanoparticles were produced in situ via the decomposition of copper sulphate pentahydrate in a KNO3-NaNO3 binary salt. Analyses of the results suggested preferential disposition of atoms around produced nanoparticles in the molten salt. Thermal characterization of the produced nano-salt suspension indicated the dependence of the specific heat enhancement on particle morphology and distribution within the salts. PMID:28772910

In Situ Production of Copper Oxide Nanoparticles in a Binary Molten Salt for Concentrated Solar Power Plant Applications.

PubMed

Lasfargues, Mathieu; Stead, Graham; Amjad, Muhammad; Ding, Yulong; Wen, Dongsheng

2017-05-19

Seeding nanoparticles in molten salts has been shown recently as a promising way to improve their thermo-physical properties. The prospect of such technology is of interest to both academic and industrial sectors in order to enhance the specific heat capacity of molten salt. The latter is used in concentrated solar power plants as both heat transfer fluid and sensible storage. This work explores the feasibility of producing and dispersing nanoparticles with a novel one pot synthesis method. Using such a method, CuO nanoparticles were produced in situ via the decomposition of copper sulphate pentahydrate in a KNO₃-NaNO₃ binary salt. Analyses of the results suggested preferential disposition of atoms around produced nanoparticles in the molten salt. Thermal characterization of the produced nano-salt suspension indicated the dependence of the specific heat enhancement on particle morphology and distribution within the salts.

Conjugating binary systems for spacecraft thermal control

NASA Technical Reports Server (NTRS)

Grodzka, Philomena G.; Dean, William G.; Sisk, Lori A.; Karu, Zain S.

1989-01-01

The materials search was directed to liquid pairs which can form hydrogen bonds of just the right strength, i.e., strong enough to give a high heat of mixing, but weak enough to enable phase change to occur. The cursory studies performed in the area of additive effects indicate that Conjugating Binary (CB) performance can probably be fine-tuned by this means. The Fluid Loop Test Systems (FLTS) tests of candidate CBs indicate that the systems Triethylamine (TEA)/water and propionaldehyde/water show close to the ideal, reversible behavior, at least initially. The Quick Screening Tests QSTs and FLTS tests, however, both suffer from rather severe static due either to inadequate stirring or temperature control. Thus it is not possible to adequately evaluate less than ideal CB performers. Less than ideal performers, it should be noted, may have features that make them better practical CBs than ideal performers. Improvement of the evaluation instrumentation is thus indicated.

Amphipathic peptide affects the lateral domain organization of lipid bilayers.

PubMed

Polozov, I V; Polozova, A I; Molotkovsky, J G; Epand, R M

1997-09-04

Using lipid-specific fluorescent probes, we studied the effects of amphipathic helical, membrane active peptides of the A- and L-type on membrane domain organization. In zwitterionic binary systems composed of mixtures of phosphatidylcholine and phosphatidylethanolamine, both types of peptides associated with the fluid phase. While binding with high affinity to fluid membranes, peptides were unable to penetrate into the lipid membrane in the gel state. If trapped kinetically by cooling from the fluid phase, peptides dissociated from the gel membrane on the time scale of several hours. While the geometrical shape of the alpha-helical peptides determines their interactions with membranes with non-bilayer phase propensity, the shape complementarity mechanism by itself is unable to induce lateral phase separation in a fluid membrane. Charge-charge interactions are capable of inducing lateral domain formation in fluid membranes. Both peptides had affinity for anionic lipids which resulted in about 30% enrichment of acidic lipids within several nanometers of the peptide's tryptophan, but there was no long-range order in peptide-induced lipid demixing. Peptide insertion in fluid acidic membranes was accompanied by only a small increase in bilayer surface and a decrease in polarity in the membrane core. Peptide-lipid charge-charge interactions were also capable of modulating existing domain composition in the course of the main phase transition in mixtures of anionic phosphatidylglycerol with zwitterionic phosphatidylcholine.

Design of a Condenser-Boiler for a Binary Mercury-Organic Rankine Cycle Solar Dynamic Space Power System

DTIC Science & Technology

1987-05-15

Velocity and Temp Profiles 64 10 . Specific Heat Spike in Supercritical Fluid 64 11. Toluene Passage Sizing Model 65 12. Finned and Unfinned Tube Bundles 65...4.. 10 inefficiency of thermal -> shaft -> electrical -> thermal power conversions. Fox El] demonstrated that significant savings can be made in...Mercury inlet temperature (turbine) 1033 OK Toluene inlet temperature (turbine) 644 OK Pinch temperature difference 10 OK M ercury turbine efficiency 0.75

Microscale Heat Transfer Enhancement using Spinodal Decomposition of Binary Liquid Mixtures: A Collaborative Modeling/Experimental Approach

DTIC Science & Technology

2013-09-01

heat transfer coefficients due to the high heat of vapor- ization. Many authors ([ Mudawar (2001)], [ Mudawar and Bowers (1999)] and [Kandlikar (2005...Letters, 95, (2005), 1. [Rosales and Meneveau (2006)] C. Rosales and C. Meneveau. Physics of Fluids, 18, (2006), 075104. [ Mudawar and Bowers (1999)] I... Mudawar and M.B. Bowers, Ultra-high crit- ical heat flux (CHF) for subcooled water flow boiling-I: CHF data and parametric effects for small

Nucleation in Polymers and Soft Matter

NASA Astrophysics Data System (ADS)

Xu, Xiaofei; Ting, Christina L.; Kusaka, Isamu; Wang, Zhen-Gang

2014-04-01

Nucleation is a ubiquitous phenomenon in many physical, chemical, and biological processes. In this review, we describe recent progress on the theoretical study of nucleation in polymeric fluids and soft matter, including binary mixtures (polymer blends, polymers in poor solvents, compressible polymer-small molecule mixtures), block copolymer melts, and lipid membranes. We discuss the methodological development for studying nucleation as well as novel insights and new physics obtained in the study of the nucleation behavior in these systems.

Fluctuation-enhanced electric conductivity in electrolyte solutions.

PubMed

Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

2017-10-10

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.

Fluctuation-enhanced electric conductivity in electrolyte solutions

PubMed Central

Péraud, Jean-Philippe; Nonaka, Andrew J.; Bell, John B.; Donev, Aleksandar; Garcia, Alejandro L.

2017-01-01

We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson–Nernst–Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation–anion diffusion coefficient. Specifically, we predict a nonzero cation–anion Maxwell–Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye–Huckel–Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced “giant” velocity fluctuations and reduced fluctuations of salt concentration. PMID:28973890

Evaluation of Thermodynamic Models for Predicting Phase Equilibria of CO2 + Impurity Binary Mixture

NASA Astrophysics Data System (ADS)

Shin, Byeong Soo; Rho, Won Gu; You, Seong-Sik; Kang, Jeong Won; Lee, Chul Soo

2018-03-01

For the design and operation of CO2 capture and storage (CCS) processes, equation of state (EoS) models are used for phase equilibrium calculations. Reliability of an EoS model plays a crucial role, and many variations of EoS models have been reported and continue to be published. The prediction of phase equilibria for CO2 mixtures containing SO2, N2, NO, H2, O2, CH4, H2S, Ar, and H2O is important for CO2 transportation because the captured gas normally contains small amounts of impurities even though it is purified in advance. For the design of pipelines in deep sea or arctic conditions, flow assurance and safety are considered priority issues, and highly reliable calculations are required. In this work, predictive Soave-Redlich-Kwong, cubic plus association, Groupe Européen de Recherches Gazières (GERG-2008), perturbed-chain statistical associating fluid theory, and non-random lattice fluids hydrogen bond EoS models were compared regarding performance in calculating phase equilibria of CO2-impurity binary mixtures and with the collected literature data. No single EoS could cover the entire range of systems considered in this study. Weaknesses and strong points of each EoS model were analyzed, and recommendations are given as guidelines for safe design and operation of CCS processes.

A poroplastic model of structural reorganisation in porous media of biomechanical interest

NASA Astrophysics Data System (ADS)

Grillo, Alfio; Prohl, Raphael; Wittum, Gabriel

2016-03-01

We present a poroplastic model of structural reorganisation in a binary mixture comprising a solid and a fluid phase. The solid phase is the macroscopic representation of a deformable porous medium, which exemplifies the matrix of a biological system (consisting e.g. of cells, extracellular matrix, collagen fibres). The fluid occupies the interstices of the porous medium and is allowed to move throughout it. The system reorganises its internal structure in response to mechanical stimuli. Such structural reorganisation, referred to as remodelling, is described in terms of "plastic" distortions, whose evolution is assumed to obey a phenomenological flow rule driven by stress. We study the influence of remodelling on the mechanical and hydraulic behaviour of the system, showing how the plastic distortions modulate the flow pattern of the fluid, and the distributions of pressure and stress inside it. To accomplish this task, we solve a highly nonlinear set of model equations by elaborating a previously developed numerical procedure, which is implemented in a non-commercial finite element solver.

Dynamic heterogeneities and non-Gaussian behavior in two-dimensional randomly confined colloidal fluids

NASA Astrophysics Data System (ADS)

Schnyder, Simon K.; Skinner, Thomas O. E.; Thorneywork, Alice L.; Aarts, Dirk G. A. L.; Horbach, Jürgen; Dullens, Roel P. A.

2017-03-01

A binary mixture of superparamagnetic colloidal particles is confined between glass plates such that the large particles become fixed and provide a two-dimensional disordered matrix for the still mobile small particles, which form a fluid. By varying fluid and matrix area fractions and tuning the interactions between the superparamagnetic particles via an external magnetic field, different regions of the state diagram are explored. The mobile particles exhibit delocalized dynamics at small matrix area fractions and localized motion at high matrix area fractions, and the localization transition is rounded by the soft interactions [T. O. E. Skinner et al., Phys. Rev. Lett. 111, 128301 (2013), 10.1103/PhysRevLett.111.128301]. Expanding on previous work, we find the dynamics of the tracers to be strongly heterogeneous and show that molecular dynamics simulations of an ideal gas confined in a fixed matrix exhibit similar behavior. The simulations show how these soft interactions make the dynamics more heterogeneous compared to the disordered Lorentz gas and lead to strong non-Gaussian fluctuations.

An investigation into dispersion upon switching between solvents within a microfluidic system using a chemically resistant integrated optical refractive index sensor.

PubMed

Parker, Richard M; Gates, James C; Wales, Dominic J; Smith, Peter G R; Grossel, Martin C

2013-02-07

A planar Bragg grating device has been developed that is capable of detecting changes in the refractive index of a wide range of fluids including solvents, acids and bases. The integration of this high precision refractive index sensor within a chemically resistant microfluidic flow system has enabled the investigation of diverse fluid interactions. By cycling between different solvents, both miscible and immiscible, within the microfluidic system it is shown that the previous solvent determines the nature of the refractive index profile across the transition in composition. This solvent dispersion effect is investigated with particular attention to the methanol-water transition, where transients in refractive index are observed that are an order of magnitude larger in amplitude than the difference between the bulk fluids. The potential complications of such phenomenon are discussed together with an example of a device that exploits this effect for the unambiguous composition measurement of a binary solvent system.

Rhythms of glycerophospholipid synthesis in retinal inner nuclear layer cells.

PubMed

Garbarino-Pico, Eduardo; Valdez, Diego J; Contín, María A; Pasquaré, Susana J; Castagnet, Paula I; Giusto, Norma M; Caputto, Beatriz L; Guido, Mario E

2005-09-01

The present study demonstrates that the biosynthesis of phospholipids in the inner nuclear layer cells of the chicken retina displays daily rhythms under constant illumination conditions. The vertebrate retina contains circadian oscillators and photoreceptors (PRCs) that temporally regulate its own physiology and synchronize the whole organism to the daily environmental changes. We have previously reported that chicken photoreceptors and retinal ganglion cells (RGCs) present significant daily variations in their phospholipid biosynthesis under constant illumination conditions. Herein, we demonstrate that cell preparations highly enriched in inner nuclear layer cells also exhibit a circadian-regulated phospholipid labeling after the in vivo administration of [(32)P]phosphate or [(3)H]glycerol both in animals maintained under constant darkness or light for at least 48h. In constant darkness, there was a significant incorporation of both precursors into phospholipids with the highest levels of labeling around midday and dusk. In constant light, the labeling of (32)P-phospholipids was also significantly higher during the day and early night whereas the incorporation of [(3)H]glycerol into phospholipids, that indicates de novo biosynthesis, was greater during the day but probably reflecting a higher precursor availability at those phases. We also measured the in vitro activity of phosphatidate phosphohydrolase and diacylglycerol lipase in preparations obtained from the dark condition. The two enzymes exhibited the highest activity levels late in the day. When we assessed the in vitro incorporation of [(14)C]oleate into different lysophospholipids from samples collected at different phases in constant darkness, reaction catalyzed by lysophospholipid acyltransferases II, labeling showed a complex pattern of daily activity. Taken together, these results demonstrate that the biosynthesis of phospholipids in cells of the chicken retinal inner nuclear layer exhibits a daily rhythmicity under constant illumination conditions, which is controlled by a circadian clock.

Clinical characteristics and laboratory findings of 252 Chinese patients with anti-phospholipid syndrome: comparison with Euro-Phospholipid cohort.

PubMed

Shi, Hui; Teng, Jia-Lin; Sun, Yue; Wu, Xin-Yao; Hu, Qiong-Yi; Liu, Hong-Lei; Cheng, Xiao-Bing; Yin, Yu-Feng; Ye, Jun-Na; Chen, Pojen P; Yang, Cheng-de

2017-03-01

This study aims to characterize the Chinese Han patients with anti-phospholipid syndrome (APS) and compare the data with those of the Euro-Phospholipid cohort. We conducted a single center study consisting of 252 patients with definite APS from 2000 to 2015. We analyzed the clinical and laboratory characteristics of our cohort and compared the data with those of the Euro-Phospholipid cohort. Our cohort consisted of 216 females and 36 males, with a mean age at entry into this study of 41 years (range 11-74 years). Of these patients, 69 (27.4%) patients had primary APS, and 183 (72.6%) had secondary APS (SAPS), including 163 (64.7%) patients had systemic lupus erythematosus (SLE). Thrombotic events occurred in 190 (75.4%) patients, and the most common ones were deep vein thrombosis (40.1%) and stroke (23.8%), which were similar to the reports of the Euro-Phospholipid cohort. In contrast, our cohort had less pulmonary embolism (6.7%). Among 93 females with 299 pregnancy episodes, the rates of early (<10 weeks) and late fetal loss (≥10 weeks) were, respectively, 37.8% and 24.4%. The latter was significantly higher than that of the Euro-Phospholipid cohort. Moreover, 7 APS nephropathy patients (characterized histopathologically by thrombotic microangiopathy) and 8 catastrophic APS patients were found in our cohort. Anti-cardiolipin antibodies (aCL) were detected in 169 (67.1%) patients, lupus anti-coagulant (LA) was detected in 83 (32.9%), and anti-β2 glycoprotein I antibodies (anti-β2GPI) in 148 (58.7%) patients. These results show that some clinical manifestations of APS may vary among different racial groups.

DNA-mediated self-assembly of artificial vesicles.

PubMed

Hadorn, Maik; Eggenberger Hotz, Peter

2010-03-26

Although multicompartment systems made of single unilamellar vesicles offer the potential to outperform single compartment systems widely used in analytic, synthetic, and medical applications, their use has remained marginal to date. On the one hand, this can be attributed to the binary character of the majority of the current tethering protocols that impedes the implementation of real multicomponent or multifunctional systems. On the other hand, the few tethering protocols theoretically providing multicompartment systems composed of several distinct vesicle populations suffer from the readjustment of the vesicle formation procedure as well as from the loss of specificity of the linking mechanism over time. In previous studies, we presented implementations of multicompartment systems and resolved the readjustment of the vesicle formation procedure as well as the loss of specificity by using linkers consisting of biotinylated DNA single strands that were anchored to phospholipid-grafted biotinylated PEG tethers via streptavidin as a connector. The systematic analysis presented herein provides evidences for the incorporation of phospholipid-grafted biotinylated PEG tethers to the vesicle membrane during vesicle formation, providing specific anchoring sites for the streptavidin loading of the vesicle membrane. Furthermore, DNA-mediated vesicle-vesicle self-assembly was found to be sequence-dependent and to depend on the presence of monovalent salts. This study provides a solid basis for the implementation of multi-vesicle assemblies that may affect at least three distinct domains. (i) Analysis. Starting with a minimal system, the complexity of a bottom-up system is increased gradually facilitating the understanding of the components and their interaction. (ii) Synthesis. Consecutive reactions may be implemented in networks of vesicles that outperform current single compartment bioreactors in versatility and productivity. (iii) Personalized medicine. Transport and targeting of long-lived, pharmacologically inert prodrugs and their conversion to short-lived, active drug molecules directly at the site of action may be accomplished if multi-vesicle assemblies of predefined architecture are used.

Phospholipid composition of the plasma membrane of the green alga, Hydrodictyon africanum.

PubMed Central

Bailey, D S; Northcote, D H

1976-01-01

A plasma-membrane fraction was isolated from the alga Hydrodictyon africanum by micro-dissection and its phospholipid components were analysed. Phosphatidylcholine was the major phospholipid of the preparation. Both phosphatidylserine and diphosphatidylglycerol were enriched in the fraction compared with the whole cell, but the relative amount of phosphatidylglycerol present was less than that in the whole cell. Phosphatidylinositol was absent from the plasma-membrane preparation. Images PLATE 1 PLATE 2 PMID:182144

Rapid Access to Phospholipid Analogs Using Thiol-yne Chemistry

DTIC Science & Technology

2015-05-19

MONITORING AGENCY NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 lipids, membrane, self...functions and material and pharmaceutical applications, straightforward methods to synthesize phospholipids in high yield are limited.10 Phospholipid...This journal is © The Royal Society of Chemistry 2015 Chem. Sci., 2015, 6, 4365–4372 | 4365 Chemical Science EDGE ARTICLE O pe n A cc es s A rt ic le

Multi-Reservoir Phospholipid Shell Encapsulating Protamine Nanocapsules for Co-Delivery of Letrozole and Celecoxib in Breast Cancer Therapy.

PubMed

Elzoghby, Ahmed O; Mostafa, Shaimaa K; Helmy, Maged W; ElDemellawy, Maha A; Sheweita, Salah A

2017-09-01

In the current work, we propose a combined delivery nanoplatform for letrozole (LTZ) and celecoxib (CXB). Multi-reservoir nanocarriers were developed by enveloping protamine nanocapsules (PRM-NCs) within drug-phospholipid complex bilayer. Encapsulation of NCs within phospholipid bilayer was confirmed by both size increase from 109.7 to 179.8 nm and reduction of surface charge from +19.0 to +7.78 mV. The multi-compartmental core-shell structure enabled biphasic CXB release with initial fast release induced by complexation with phospholipid shell followed by prolonged release from oily core. Moreover, phospholipid coating provided protection for cationic PRM-NCs against interaction with RBCs and serum proteins enabling their systemic administration. Pharmacokinetic analysis demonstrated prolonged circulation and delayed clearance of both drugs after intravenous administration into rats. The superior anti-tumor efficacy of multi-reservoir NCs was manifested as powerful cytotoxicity against MCF-7 breast cancer cells and marked reduction in the mammary tumor volume in Ehrlich ascites bearing mice compared with free LTZ-CXB combination. Moreover, the NCs induced apoptotic caspase activation and marked inhibition of aromatase expression and angiogenic marker, VEGF as well as inhibition of both NFκB and TNFα. Multi-reservoir phospholipid shell coating PRM-NCs could serve as a promising nanocarrier for parenteral combined delivery of LTZ and CXB.

Polyhydroxyalkanoate (PHA) Granules Have no Phospholipids

PubMed Central

Bresan, Stephanie; Sznajder, Anna; Hauf, Waldemar; Forchhammer, Karl; Pfeiffer, Daniel; Jendrossek, Dieter

2016-01-01

Polyhydroxybutyrate (PHB) granules, also designated as carbonosomes, are supra-molecular complexes in prokaryotes consisting of a PHB polymer core and a surface layer of structural and functional proteins. The presence of suspected phospholipids in the surface layer is based on in vitro data of isolated PHB granules and is often shown in cartoons of the PHB granule structure in reviews on PHB metabolism. However, the in vivo presence of a phospholipid layer has never been demonstrated. We addressed this topic by the expression of fusion proteins of DsRed2EC and other fluorescent proteins with the phospholipid-binding domain (LactC2) of lactadherin in three model organisms. The fusion proteins specifically localized at the cell membrane of Ralstonia eutropha but did not co-localize with PHB granules. The same result was obtained for Pseudomonas putida, a species that accumulates another type of polyhydroxyalkanoate (PHA) granules related to PHB. Notably, DsRed2EC-LactC2 expressed in Magnetospirillum gryphiswaldense was detected at the position of membrane-enclosed magnetosome chains and at the cytoplasmic membrane but not at PHB granules. In conclusion, the carbonosomes of representatives of α-proteobacteria, β-proteobacteria and γ-proteobacteria have no phospholipids in vivo and we postulate that the PHB/PHA granule surface layers in natural producers generally are free of phospholipids and consist of proteins only. PMID:27222167

Proteaceae from severely phosphorus-impoverished soils extensively replace phospholipids with galactolipids and sulfolipids during leaf development to achieve a high photosynthetic phosphorus-use-efficiency.

PubMed

Lambers, Hans; Cawthray, Gregory R; Giavalisco, Patrick; Kuo, John; Laliberté, Etienne; Pearse, Stuart J; Scheible, Wolf-Rüdiger; Stitt, Mark; Teste, François; Turner, Benjamin L

2012-12-01

Proteaceae species in south-western Australia occur on severely phosphorus (P)-impoverished soils. They have very low leaf P concentrations, but relatively fast rates of photosynthesis, thus exhibiting extremely high photosynthetic phosphorus-use-efficiency (PPUE). Although the mechanisms underpinning their high PPUE remain unknown, one possibility is that these species may be able to replace phospholipids with nonphospholipids during leaf development, without compromising photosynthesis. For six Proteaceae species, we measured soil and leaf P concentrations and rates of photosynthesis of both young expanding and mature leaves. We also assessed the investment in galactolipids, sulfolipids and phospholipids in young and mature leaves, and compared these results with those on Arabidopsis thaliana, grown under both P-sufficient and P-deficient conditions. In all Proteaceae species, phospholipid levels strongly decreased during leaf development, whereas those of galactolipids and sulfolipids strongly increased. Photosynthetic rates increased from young to mature leaves. This shows that these species extensively replace phospholipids with nonphospholipids during leaf development, without compromising photosynthesis. A considerably less pronounced shift was observed in A. thaliana. Our results clearly show that a low investment in phospholipids, relative to nonphospholipids, offers a partial explanation for a high photosynthetic rate per unit leaf P in Proteaceae adapted to P-impoverished soils. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

Distribution of phospholipid based formulations in the skin investigated by combined ATR-FTIR and tape stripping experiments.

PubMed

Wolf, Martin; Halper, Maria; Pribyl, Raffaela; Baurecht, Dieter; Valenta, Claudia

2017-03-15

The spatial distribution of exogenous substances in the stratum corneum (SC) could have an influence on their skin irritation potential. In this study it was possible to monitor the distribution of phospholipids with their phosphatidylcholine scaffold on porcine ear skin by combining tape stripping and in vitro ATR-FTIR spectroscopy. Significant vibrational modes in the spectra could be successfully assigned to the functional groups of the molecules. Thus it was possible to track the phospholipids without the need of their deuterated form by calculating difference spectra from the treated - untreated skin samples. The correlation between four characteristic bands (R 2 ≥0.9909) revealed the excellent suitability of this semi-quantitative method for deep profiling analysis. The penetration capabilities of aqueous suspensions of the different phospholipid compositions as well as two monoacyl-phosphatidylcholine based liposome formulations were investigated using this method. Nevertheless, differences in the distribution of the investigated phospholipid species, having different amounts of monoacyl-phosphatidylcholine, could not be found. It could be clearly shown that the deepest skin penetration was seen in the irritating anionic SDS (sodium dodecyl sulfate) out of the aqueous solution. The aqueous suspensions based on different phospholipid surfactants showed the same range of penetration depth (10-15% of SC), whereas the smallest skin penetration depth was observed after the application of liposomal formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanisms of Phosphorus Acquisition and Lipid Class Remodeling under P Limitation in a Marine Microalga1[OPEN

PubMed Central

Winge, Per; El Assimi, Aimen; Jouhet, Juliette; Vadstein, Olav

2017-01-01

Molecular mechanisms of phosphorus (P) limitation are of great interest for understanding algal production in aquatic ecosystems. Previous studies point to P limitation-induced changes in lipid composition. As, in microalgae, the molecular mechanisms of this specific P stress adaptation remain unresolved, we reveal a detailed phospholipid-recycling scheme in Nannochloropsis oceanica and describe important P acquisition genes based on highly corresponding transcriptome and lipidome data. Initial responses to P limitation showed increased expression of genes involved in P uptake and an expansion of the P substrate spectrum based on purple acid phosphatases. Increase in P trafficking displayed a rearrangement between compartments by supplying P to the chloroplast and carbon to the cytosol for lipid synthesis. We propose a novel phospholipid-recycling scheme for algae that leads to the rapid reduction of phospholipids and synthesis of the P-free lipid classes. P mobilization through membrane lipid degradation is mediated mainly by two glycerophosphoryldiester phosphodiesterases and three patatin-like phospholipases A on the transcriptome level. To compensate for low phospholipids in exponential growth, N. oceanica synthesized sulfoquinovosyldiacylglycerol and diacylglyceroltrimethylhomoserine. In this study, it was shown that an N. oceanica strain has a unique repertoire of genes that facilitate P acquisition and the degradation of phospholipids compared with other stramenopiles. The novel phospholipid-recycling scheme opens new avenues for metabolic engineering of lipid composition in algae. PMID:29051196

The assessment of cold atmospheric plasma treatment of DNA in synthetic models of tissue fluid, tissue and cells

NASA Astrophysics Data System (ADS)

Szili, Endre J.; Gaur, Nishtha; Hong, Sung-Ha; Kurita, Hirofumi; Oh, Jun-Seok; Ito, Masafumi; Mizuno, Akira; Hatta, Akimitsu; Cowin, Allison J.; Graves, David B.; Short, Robert D.

2017-07-01

There is a growing literature database that demonstrates the therapeutic potential of cold atmospheric plasma (herein referred to as plasma). Given the breadth of proposed applications (e.g. from teeth whitening to cancer therapy) and vast gamut of plasma devices being researched, it is timely to consider plasma interactions with specific components of the cell in more detail. Plasma can produce highly reactive oxygen and nitrogen species (RONS) such as the hydroxyl radical (OH•), peroxynitrite (ONOO-) and superoxide (\\text{O}2- ) that would readily modify essential biomolecules such as DNA. These modifications could in principle drive a wide range of biological processes. Against this possibility, the reported therapeutic action of plasmas are not underpinned by a particularly deep knowledge of the potential plasma-tissue, -cell or -biomolecule interactions. In this study, we aim to partly address this issue by developing simple models to study plasma interactions with DNA, in the form of DNA-strand breaks. This is carried out using synthetic models of tissue fluid, tissue and cells. We argue that this approach makes experimentation simpler, more cost-effective and faster than compared to working with real biological materials and cells. Herein, a helium plasma jet source was utilised for these experiments. We show that the plasma jet readily induced DNA-strand breaks in the tissue fluid model and in the cell model, surprisingly without any significant poration or rupture of the phospholipid membrane. In the plasma jet treatment of the tissue model, DNA-strand breaks were detected in the tissue mass after pro-longed treatment (on the time-scale of minutes) with no DNA-strand breaks being detected in the tissue fluid model underneath the tissue model. These data are discussed in the context of the therapeutic potential of plasma.

Subsurface microbial diversity in deep-granitic-fracture water in Colorado

USGS Publications Warehouse

Sahl, J.W.; Schmidt, R.; Swanner, E.D.; Mandernack, K.W.; Templeton, A.S.; Kieft, Thomas L.; Smith, R.L.; Sanford, W.E.; Callaghan, R.L.; Mitton, J.B.; Spear, J.R.

2008-01-01

A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a >1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (Gallionella spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that Nitrosomonadales dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by Firmicutes, Proteobacteria, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This "Henderson candidate division" dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions Proteobacteria (primarily the family Ralstoniaceae) and Firmicutes. Sequences grouping within Ralstoniaceae were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems. Copyright ?? 2008, American Society for Microbiology. All Rights Reserved.

Subsurface Microbial Diversity in Deep-Granitic-Fracture Water in Colorado▿

PubMed Central

Sahl, Jason W.; Schmidt, Raleigh; Swanner, Elizabeth D.; Mandernack, Kevin W.; Templeton, Alexis S.; Kieft, Thomas L.; Smith, Richard L.; Sanford, William E.; Callaghan, Robert L.; Mitton, Jeffry B.; Spear, John R.

2008-01-01

A microbial community analysis using 16S rRNA gene sequencing was performed on borehole water and a granite rock core from Henderson Mine, a >1,000-meter-deep molybdenum mine near Empire, CO. Chemical analysis of borehole water at two separate depths (1,044 m and 1,004 m below the mine entrance) suggests that a sharp chemical gradient exists, likely from the mixing of two distinct subsurface fluids, one metal rich and one relatively dilute; this has created unique niches for microorganisms. The microbial community analyzed from filtered, oxic borehole water indicated an abundance of sequences from iron-oxidizing bacteria (Gallionella spp.) and was compared to the community from the same borehole after 2 weeks of being plugged with an expandable packer. Statistical analyses with UniFrac revealed a significant shift in community structure following the addition of the packer. Phospholipid fatty acid (PLFA) analysis suggested that Nitrosomonadales dominated the oxic borehole, while PLFAs indicative of anaerobic bacteria were most abundant in the samples from the plugged borehole. Microbial sequences were represented primarily by Firmicutes, Proteobacteria, and a lineage of sequences which did not group with any identified bacterial division; phylogenetic analyses confirmed the presence of a novel candidate division. This “Henderson candidate division” dominated the clone libraries from the dilute anoxic fluids. Sequences obtained from the granitic rock core (1,740 m below the surface) were represented by the divisions Proteobacteria (primarily the family Ralstoniaceae) and Firmicutes. Sequences grouping within Ralstoniaceae were also found in the clone libraries from metal-rich fluids yet were absent in more dilute fluids. Lineage-specific comparisons, combined with phylogenetic statistical analyses, show that geochemical variance has an important effect on microbial community structure in deep, subsurface systems. PMID:17981950

Guidelines for the Use of Protein Domains in Acidic Phospholipid Imaging.

PubMed

Platre, Matthieu Pierre; Jaillais, Yvon

2016-01-01

Acidic phospholipids are minor membrane lipids but critically important for signaling events. The main acidic phospholipids are phosphatidylinositol phosphates (PIPs also known as phosphoinositides), phosphatidylserine (PS), and phosphatidic acid (PA). Acidic phospholipids are precursors of second messengers of key signaling cascades or are second messengers themselves. They regulate the localization and activation of many proteins, and are involved in virtually all membrane trafficking events. As such, it is crucial to understand the subcellular localization and dynamics of each of these lipids within the cell. Over the years, several techniques have emerged in either fixed or live cells to analyze the subcellular localization and dynamics of acidic phospholipids. In this chapter, we review one of them: the use of genetically encoded biosensors that are based on the expression of specific lipid binding domains (LBDs) fused to fluorescent proteins. We discuss how to design such sensors, including the criteria for selecting the lipid binding domains of interest and to validate them. We also emphasize the care that must be taken during data analysis as well as the main limitations and advantages of this approach.

Modulation of receptor-mediated gonadotropin action in rat testes by dietary fat.

PubMed

Sebokova, E; Garg, M L; Clandinin, M T

1988-06-01

The effect of feeding diets enriched with 18:2 omega 6, 18:3 omega 3, or saturated fatty acids on lipid composition and receptor-mediated action of luteinizing hormone/human chorionic gonadotropin (LH/hCG) in rat testicular plasma membranes was investigated. Linoleic and alpha-linolenic acid treatments reduced total phospholipid and cholesterol content of the testicular plasma membrane and altered membrane phospholipid composition. Change in phospholipid and cholesterol content after feeding the polyunsaturated fats decreased cholesterol to phospholipid ratios and binding capacity of the LH/hCG receptor in the testicular plasma membrane. LH-stimulated adenylate cyclase activity was decreased in animals fed the linolenic acid-rich diet. NaF-stimulated adenylate cyclase activity was decreased in animals fed diets high in either polyunsaturated fatty acid. Decreased plasma membrane LH/hCG receptor content was associated with decreased testosterone production in Leydig cells in response to LH in the linolenic acid-fed group. It is suggested that change in cholesterol-to-phospholipid ratios alters the physical properties of testicular plasma membranes in a manner that influences accessibility of LH/hCG receptors in testicular tissue.

Phospholipid fingerprints of milk from different mammalians determined by 31P NMR: towards specific interest in human health.

PubMed

Garcia, Cyrielle; Lutz, Norbert W; Confort-Gouny, Sylviane; Cozzone, Patrick J; Armand, Martine; Bernard, Monique

2012-12-01

Our objective was to identify and quantify phospholipids in milk from different species (human HM, cow CoM, camel CaM, and mare MM) using an optimised (31)P NMR spectroscopy procedure. The phospholipid fingerprints were species-specific with a broader variety of classes found in HM and MM; HM and CaM were richer in sphingomyelin (78.3 and 117.5μg/ml) and plasmalogens (27.3 and 24μg/ml), possibly important for infant development. Total phospholipid content was higher in CaM (0.503mM) and lower in MM (0.101mM) compared to HM (0.324mM) or CoM (0.265mM). Our optimised method showed good sensitivity, high resolution, and easy sample preparation with minimal loss of target molecules. It is suitable for determining the accurate composition of a large number of bioactive phospholipids with putative health benefits, including plasmalogens, and should aid in selecting appropriate ingredient sources for infant milk substitutes or fortifiers, and for functional foods dedicated to adults. Copyright © 2012 Elsevier Ltd. All rights reserved.

Impact of Phospholipids and Tocopherols on the Oxidative Stability of Soybean Oil-in-Water Emulsions.

PubMed

Samdani, Gautam K; McClements, D Julian; Decker, Eric A

2018-04-18

Phospholipids have been shown to act synergistically with tocopherols and delay lipid oxidation in bulk oil. The synergistic activity between phospholipids and tocopherols is due to the ability of amino-group-containing phospholipids (e.g., phosphatidylethanolamine (PE) and phosphatidylserine (PS)) to convert oxidized tocopherol back into tocopherols. This study shows the effect of PE and PS on the antioxidant activity of different tocopherol homologues in oil-in-water emulsions. Effect of emulsifier type on the interaction between tocopherols and phospholipids was also studied. δ-Tocopherol and PE exhibited greater antioxidant activity as compared to α-tocopherol and PE. PS displayed 1.5-3 times greater synergism than PE with Tween 20 as emulsifier whereas both PE and PS had a similar antioxidant activity in the presence of α-tocopherol when bovine serum albumin was used as the emulsifier. This study is the first to show that PE and PS can act synergistically with tocopherols to inhibit lipid oxidation in oil-in-water emulsions and can present a new clean label antioxidant strategy for food emulsions.

Blood coagulation reactions on nanoscale membrane surfaces

NASA Astrophysics Data System (ADS)

Pureza, Vincent S.

Blood coagulation requires the assembly of several membrane-bound protein complexes composed of regulatory and catalytic subunits. The biomembranes involved in these reactions not only provide a platform for these procoagulant proteins, but can also affect their function. Increased exposure of acidic phospholipids on the outer leaflet of the plasma membrane can dramatically modulate the catalytic efficiencies of such membrane-bound enzymes. Under physiologic conditions, however, these phospholipids spontaneously cluster into a patchwork of membrane microdomains upon which membrane binding proteins may preferentially assemble. As a result, the membrane composition surrounding these proteins is largely unknown. Through the development and use of a nanometer-scale bilayer system that provides rigorous control of the phospholipid membrane environment, I investigated the role of phosphatidylserine, an acidic phospholipid, in the direct vicinity (within nanometers) of two critical membrane-bound procoagulant protein complexes and their respective natural substrates. Here, I present how the assembly and function of the tissue factor˙factor VIIa and factor Va˙factor Xa complexes, the first and final cofactor˙enzyme complexes of the blood clotting cascade, respectively, are mediated by changes in their immediate phospholipid environments.

Single-molecule height measurements on microsomal cytochrome P450 in nanometer-scale phospholipid bilayer disks

NASA Astrophysics Data System (ADS)

Bayburt, Timothy H.; Sligar, Stephen G.

2002-05-01

The architecture of membrane proteins in their native environment of the phospholipid bilayer is critical for understanding physiological function, but has been difficult to realize experimentally. In this communication we describe the incorporation of a membrane-anchored protein into a supported phospholipid bilayer. Cytochrome P450 2B4 solubilized and purified from the hepatic endoplasmic reticulum was incorporated into phospholipid bilayer nanostructures and oriented on a surface for visualization by atomic force microscopy. Individual P450 molecules were observed protruding from the bilayer surface. Problems associated with deformation of the protein by the atomic force microscopy probe were avoided by analyzing force-dependent height measurements to quantitate the height of the protein above the bilayer surface. Measurements of the atomic force microscopy cantilever deflection as a function of probe-sample separation reveal that the top of the P450 opposite the N-terminal membrane anchor region sits 3.5 nanometers above the phospholipid-water boundary. Models of the orientation of the enzyme are presented and discussed in relation to membrane interactions and interaction with cytochrome P450 reductase.

Long-Acting Phospholipid Gel of Exenatide for Long-Term Therapy of Type II Diabetes.

PubMed

Hu, Mei; Zhang, Yu; Xiang, Nanxi; Zhong, Ying; Gong, Tao; Zhang, Zhi-Rong; Fu, Yao

2016-06-01

This study aimed to develop a sustained-release formulation of exenatide (EXT) for the long-term therapeutic efficacy in the treatment of type II diabetes. In this study, we present an injectable phospholipid gel by mixing biocompatible phospholipid S100, medium chain triglyceride (MCT) with 85% (w/w) ethanol. A systemic pre-formulation study has been carried out to improve the stability of EXT during formulation fabrication. With the optimized formulation, the pharmacokinetic profiles in rats were studied and two diabetic animal models were employed to evaluate the therapeutic effect of EXT phospholipid gel via a single subcutaneous injection versus repeated injections of normal saline and EXT solution. With optimized formulation, sustained release of exenatide in vivo for over three consecutive weeks was observed after one single subcutaneous injection. Moreover, the pharmacodynamic study in two diabetic models justified that the gel formulation displayed a comparable hypoglycemic effect and controlled blood glucose level compared with exenatide solution treated group. EXT-loaded phospholipid gel represents a promising controlled release system for long-term therapy of type II diabetes.

Phospholipids and protein adaptation of Pseudomonas sp. to the xenoestrogen tributyltin chloride (TBT).

PubMed

Bernat, Przemysław; Siewiera, Paulina; Soboń, Adrian; Długoński, Jerzy

2014-09-01

A tributyltin (TBT)-resistant strain of Pseudomonas sp. isolated from an overworked car filter was tested for its adaptation to TBT. The isolate was checked for organotin degradation ability, as well as membrane lipid and cellular protein composition in the presence of TBT. The phospholipid profiles of bacteria, grown with and without increased amounts of TBT, were characterized using liquid chromatography/electrospray ionization/mass spectrometry. The strain reacted to the biocide by changing the composition of its phospholipids. TBT induced a twofold decline in the amounts of many molecular species of phosphatidylglycerol and an increase in the levels of phosphatidic acid (by 58%) and phosphatidylethanolamine (by 70%). An increase in the degree of saturation of phospholipid fatty acids of TBT exposed Pseudomonas sp. was observed. These changes in the phospholipid composition and concentration reflect the mechanisms which support optimal lipid ordering in the presence of toxic xenobiotic. In the presence of TBT the abundances of 16 proteins, including TonB-dependent receptors, porins and peroxidases were modified, which could indicate a contribution of some enzymes to TBT resistance.

Phospholipid composition of chlorophyll-free mitochondria isolated via protoplasts from oat mesophyll cells.

PubMed

Fuchs, R; Haas, R; Wrage, K; Heinz, E

1981-08-01

Mitochondria were isolated from oat primary leaves via mesophyll protoplasts and subjected to phospholipid analysis. In mesophyll cells mitochondria account for only small proportions of cellular phospholipids (in the order of 5%) and proteins (in the order of 2%). Contamination by lipids from other membranes was insignificant as indicated by the absence or very low levels of chlorophyll, galactolipids and steryl glycosides. The absence of 3-trans-hexadecenoic acid in phosphatidylglycerol from mitochondria of green cells serves an an additional criterion of purity. The phospholipid mixture extracted from these mitochondria resembles phospholipids in mitochondria from non-green tissues regarding composition as well as fatty acid profiles. Therefore, mitochondria maintain a rather constant lipid profile and in contrast to plastids do not respond at this level to differences in the physiological status of their housing cell. Palmitic acid in mitochondrial phosphatidylcholine and phosphatidylethanolamine is primarily localized at the C-1 position of the glycerol moiety. Two enzymatic activities so far not described in mitochondria, formation of acylgalactosyl diacylglycerol and hydrolysis of acyl-CoA, were found in the purified mitochondrial fraction.

Information storage and retrieval in a single levitating colloidal particle

NASA Astrophysics Data System (ADS)

Myers, Christopher J.; Celebrano, Michele; Krishnan, Madhavi

2015-10-01

The binary switch is a basic component of digital information. From phase-change alloys to nanomechanical beams, molecules and atoms, new strategies for controlled bistability hold great interest for emerging technologies. We present a generic methodology for precise and parallel spatiotemporal control of nanometre-scale matter in a fluid, and demonstrate the ability to attain digital functionalities such as switching, gating and data storage in a single colloid, with further implications for signal amplification and logic operations. This fluid-phase bit can be arrayed at high densities, manipulated by either electrical or optical fields, supports low-energy, high-speed operation and marks a first step toward ‘colloidal information’. The principle generalizes to any system where spatial perturbation of a particle elicits a differential response amenable to readout.

Information storage and retrieval in a single levitating colloidal particle.

PubMed

Myers, Christopher J; Celebrano, Michele; Krishnan, Madhavi

2015-10-01

The binary switch is a basic component of digital information. From phase-change alloys to nanomechanical beams, molecules and atoms, new strategies for controlled bistability hold great interest for emerging technologies. We present a generic methodology for precise and parallel spatiotemporal control of nanometre-scale matter in a fluid, and demonstrate the ability to attain digital functionalities such as switching, gating and data storage in a single colloid, with further implications for signal amplification and logic operations. This fluid-phase bit can be arrayed at high densities, manipulated by either electrical or optical fields, supports low-energy, high-speed operation and marks a first step toward 'colloidal information'. The principle generalizes to any system where spatial perturbation of a particle elicits a differential response amenable to readout.

Anti-lysophosphatidic acid antibodies improve traumatic brain injury outcomes

PubMed Central

2014-01-01

Background Lysophosphatidic acid (LPA) is a bioactive phospholipid with a potentially causative role in neurotrauma. Blocking LPA signaling with the LPA-directed monoclonal antibody B3/Lpathomab is neuroprotective in the mouse spinal cord following injury. Findings Here we investigated the use of this agent in treatment of secondary brain damage consequent to traumatic brain injury (TBI). LPA was elevated in cerebrospinal fluid (CSF) of patients with TBI compared to controls. LPA levels were also elevated in a mouse controlled cortical impact (CCI) model of TBI and B3 significantly reduced lesion volume by both histological and MRI assessments. Diminished tissue damage coincided with lower brain IL-6 levels and improvement in functional outcomes. Conclusions This study presents a novel therapeutic approach for the treatment of TBI by blocking extracellular LPA signaling to minimize secondary brain damage and neurological dysfunction. PMID:24576351

Mechanics, morphology, and mobility in stratum corneum membranes

NASA Astrophysics Data System (ADS)

Olmsted, Peter; Das, Chinmay; Noro, Massimo

2012-02-01

The stratum corneum is the outermost layer of skin, and serves as a protective barrier against external agents, and to control moisture. It comprises keratin bodies (corneocytes) embedded in a matrix of lipid bilayers. Unlike the more widely studied phospholipid bilayers, the SC bilayers are typically in a gel-like state. Moreover, the SC membrane composition is radically different from more fluid counterparts: it comprises single tailed fatty acids, ceramides, and cholesterol; with many distinct ceramides possessing different lengths of tails, and always with two tails of different lengths. I will present insight from computer simulations into the morphology, mechanical properties, and diffusion (barrier) properties of these highly heterogeneous membranes. Our results provide some clue as to the design principles for the SC membrane, and is an excellent example of the use of wide polydispersity by natural systems.

Effect of lipid emulsions on the plasma lecithin: cholesterol acyltransfer in guinea pigs.

PubMed

Drevon, C A; Norum, K R

1975-01-01

Addition of triglyceride/phospholipid emulsion to adult guinea pig plasma more than doubled the cholesteryl ester (CE) production. Plasma from newborn guinea pigs was stimulated to a lower degree. The increase in CE production was dependant on the type and amount of phospholipids in the lipid emulsions. Egg phospholipids stimulated the cholesterol esterification while partially hydrogenated soy phospholipids (with high content of saturated fatty acids) inhibited the reaction. The stimulation of CE formation was probably due to transfer of phosphatidyl choline (PC) from the emulsion to the high density lipoproteins since the stimulation was: (a) dependant on a preincubation time, (b) less pronounced in newborn animals with high plasma PC levels, and (c) detected in plasma fractions from which the lipid emulsion had been removed.

3D-Quantitative structure-activity relationships of synthetic antileishmanial ring-substituted ether phospholipids.

PubMed

Kapou, Agnes; Benetis, Nikolas P; Avlonitis, Nikos; Calogeropoulou, Theodora; Koufaki, Maria; Scoulica, Efi; Nikolaropoulos, Sotiris S; Mavromoustakos, Thomas

2007-02-01

The application of 2D-NMR spectroscopy and Molecular Modeling in determining the active conformation of flexible molecules in 3D-QSAR was demonstrated in the present study. In particular, a series of 33 flexible synthetic phospholipids, either 2-(4-alkylidene-cyclohexyloxy)ethyl- or omega-cycloalkylidene-substituted ether phospholipids were systematically evaluated for their in vitro antileishmanial activity against the promastigote forms of Leishmania infantum and Leishmania donovani by CoMFA and CoMSIA 3D-QSAR studies. Steric and hydrophobic properties of the phospholipids under study appear to govern their antileishmanial activity against both strains, while the electrostatic properties have no significant contribution. The acknowledgment of these important properties of the pharmacophore will aid in the rational design of new analogues with higher activity.

Enhanced heat transport during phase separation of liquid binary mixtures

NASA Astrophysics Data System (ADS)

Molin, Dafne; Mauri, Roberto

2007-07-01

We show that heat transfer in regular binary fluids is enhanced by induced convection during phase separation. The motion of binary mixtures is simulated using the diffuse interface model, where convection and diffusion are coupled via a nonequilibrium, reversible Korteweg body force. Assuming that the mixture is regular, i.e., its components are van der Waals fluids, we show that the two parameters that describe the mixture, namely the Margules constant and the interfacial thickness, depend on temperature as T-1 and T-1/2, respectively. Two quantities are used to measure heat transfer, namely the heat flux at the walls and the characteristic cooling time. Comparing these quantities with those of very viscous mixtures, where diffusion prevails over convection, we saw that the ratio between heat fluxes, which defines the Nusselt number, NNu, equals that between cooling times and remains almost constant in time. The Nusselt number depends on the following: the Peclet number, NPe, expressing the ratio between convective and diffusive mass fluxes; the Lewis number, NLe, expressing the ratio between thermal and mass diffusivities; the specific heat of the mixture, as it determines how the heat generated by mixing can be stored within the system; and the quenching depth, defined as the distance of the temperature at the wall from its critical value. In particular, the following results were obtained: (a) The Nusselt number grows monotonically with the Peclet number until it reaches an asymptotic value at NNu≈2 when NPe≈106; (b) the Nusselt number increases with NLe when NLe<1, remains constant at 11; (c) the Nusselt number is hardly influenced by the specific heat; (d) the Nusselt number decreases as the quenching rate increases. All these results can be explained by physical considerations. Predictably, considering that convection is within the creeping flow regime, the Nusselt number is always of o(10).

Binary Colloidal Alloy Test Conducted on Mir

NASA Technical Reports Server (NTRS)

Hoffmann, Monica I.; Ansari, Rafat R.

1999-01-01

Colloids are tiny (submicron) particles suspended in fluid. Paint, ink, and milk are examples of colloids found in everyday life. The Binary Colloidal Alloy Test (BCAT) is part of an extensive series of experiments planned to investigate the fundamental properties of colloids so that scientists can make colloids more useful for technological applications. Some of the colloids studied in BCAT are made of two different sized particles (binary colloidal alloys) that are very tiny, uniform plastic spheres. Under the proper conditions, these colloids can arrange themselves in a pattern to form crystals. These crystals may form the basis of new classes of light switches, displays, and optical devices. Windows made of liquid crystals are already in the marketplace. These windows change their appearance from transparent to opaque when a weak electric current is applied. In the future, if the colloidal crystals can be made to control the passage of light through them, such products could be made much more cheaply. These experiments require the microgravity environment of space because good quality crystals are difficult to produce on Earth because of sedimentation and convection in the fluid. The BCAT experiment hardware included two separate modules for two different experiments. The "Slow Growth" hardware consisted of a 35-mm camera with a 250- exposure photo film cartridge. The camera was aimed toward the sample module, which contained 10 separate colloid samples. A rack of small lights provided backlighting for the photographs. The BCAT hardware was launched on the shuttle and was operated aboard the Russian space station Mir by American astronauts John Blaha and David Wolf (launched September 1996 and returned January 1997; reflown September 1997 and returned January 1998). To begin the experiment, one of these astronauts would mix the samples to disperse the colloidal particles and break up any crystals that might have already formed. Once the samples were mixed and the experiment was powered on, the hardware operated autonomously, taking photos of the colloidal samples over a 90-day period.

Orchestrating phospholipid biosynthesis: Phosphatidic acid conducts and Opi1p performs.

PubMed

Salsaa, Michael; Case, Kendall; Greenberg, Miriam L

2017-11-10

Phosphatidic acid (PA) and the conserved integral ER membrane protein Scs2p regulate localization of the transcriptional repressor Opi1p, which controls expression of phospholipid biosynthesis genes, but the mechanisms conducting Opi1p localization are not fully understood. A new study suggests the existence of a distinct pool of PA in the ER that is required for regulation of Opi1p localization and thus phospholipid metabolism in yeast. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Extraction of metals using supercritical fluid and chelate forming legand

DOEpatents

Wai, Chien M.; Laintz, Kenneth E.

1998-01-01

A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

Extraction of metals using supercritical fluid and chelate forming ligand

DOEpatents

Wai, C.M.; Laintz, K.E.

1998-03-24

A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated {beta}-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated {beta}-diketone and a trialkyl phosphate, or a fluorinated {beta}-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated {beta}-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs.

Predicting low-temperature free energy landscapes with flat-histogram Monte Carlo methods

NASA Astrophysics Data System (ADS)

Mahynski, Nathan A.; Blanco, Marco A.; Errington, Jeffrey R.; Shen, Vincent K.

2017-02-01

We present a method for predicting the free energy landscape of fluids at low temperatures from flat-histogram grand canonical Monte Carlo simulations performed at higher ones. We illustrate our approach for both pure and multicomponent systems using two different sampling methods as a demonstration. This allows us to predict the thermodynamic behavior of systems which undergo both first order and continuous phase transitions upon cooling using simulations performed only at higher temperatures. After surveying a variety of different systems, we identify a range of temperature differences over which the extrapolation of high temperature simulations tends to quantitatively predict the thermodynamic properties of fluids at lower ones. Beyond this range, extrapolation still provides a reasonably well-informed estimate of the free energy landscape; this prediction then requires less computational effort to refine with an additional simulation at the desired temperature than reconstruction of the surface without any initial estimate. In either case, this method significantly increases the computational efficiency of these flat-histogram methods when investigating thermodynamic properties of fluids over a wide range of temperatures. For example, we demonstrate how a binary fluid phase diagram may be quantitatively predicted for many temperatures using only information obtained from a single supercritical state.

Unresolved issues in the analysis of F2-isoprostanes, F4-neuroprostanes, isofurans, neurofurans, and F2-dihomo-isoprostanes in body fluids and tissue using gas chromatography/negative-ion chemical-ionization mass spectrometry.

PubMed

Yen, H-C; Wei, H-J; Lin, C-L

2015-01-01

F2-isoprostanes (F2-IsoPs) generated from arachidonic acid (AA) have been recognized as the most reliable marker of nonenzymatic lipid peroxidation in vivo. F2-IsoPs are initially produced in esterified form on phospholipids, and then released into body fluids in free form. The same mechanism can lead to generation of F4-neuroprostanes (F4-NPs) and F2-dihomo-IsoPs from docosahexaenoic acid (DHA) and adrenic acid, respectively. In addition, isofurans (IsoFs) and neurofurans (NFs) may be preferentially produced from AA and DHA, respectively, under high oxygen tension. The detection of F2-IsoPs using gas chromatography/negative-ion chemical-ionization mass spectrometry (GC/NICI-MS) has been widely employed, which is important for human body fluids containing low quantity of free-form F2-IsoPs. F4-NPs have also been detected using GC/NICI-MS, but multiple peaks need to be quantified. In this paper, we summarize the basic workflow of the GC/NICI-MS method for analyzing F2-IsoPs and F4-NPs, and various formats of assays conducted by different groups. We then discuss the feasibility of simultaneous analysis of IsoFs, NFs, and F2-dihomo-IsoPs with F2-IsoPs or F4-NPs. Representative GC chromatograms for analyzing these markers in human body fluids and rat brain tissue are demonstrated. Furthermore, we discuss several factors that may affect the performance of the analysis, such as those related to the sample processing steps, interference from specimens, types of GC liners used, and the addition of electron multiplier voltage in the method setting for the MS detector. Finally, we question the appropriateness of measuring total (free plus esterified) levels of these markers in body fluids.

Phospholipid Fatty Acid Analysis: Past, Present and Future

NASA Astrophysics Data System (ADS)

Findlay, R. H.

2008-12-01

With their 1980 publication, Bobbie and White initiated the use of phospholipid fatty acids for the study of microbial communities. This method, integrated with a previously published biomass assay based on the colorimetric detection of orthophosphate liberated from phospholipids, provided the first quantitative method for determining microbial community structure. The method is based on a quantitative extraction of lipids from the sample matrix, isolation of the phospholipids, conversion of the phospholipid fatty acids to their corresponding fatty acid methyl esters (known by the acronym FAME) and the separation, identification and quantification of the FAME by gas chromatography. Early laboratory and field samples focused on correlating individual fatty acids to particular groups of microorganisms. Subsequent improvements to the methodology include reduced solvent volumes for extractions, improved sensitivity in the detection of orthophosphate and the use of solid phase extraction technology. Improvements in the field of gas chromatography also increased accessibility of the technique and it has been widely applied to water, sediment, soil and aerosol samples. Whole cell fatty acid analysis, a related but not equal technique, is currently used for phenotypic characterization in bacterial species descriptions and is the basis for a commercial, rapid bacterial identification system. In the early 1990ês application of multivariate statistical analysis, first cluster analysis and then principal component analysis, further improved the usefulness of the technique and allowed the development of a functional group approach to interpretation of phospholipid fatty acid profiles. Statistical techniques currently applied to the analysis of phospholipid fatty acid profiles include constrained ordinations and neutral networks. Using redundancy analysis, a form of constrained ordination, we have recently shown that both cation concentration and dissolved organic matter (DOM) quality are determinates of microbial community structure in forested headwater streams. One of the most exciting recent developments in phospholipid fatty acid analysis is the application of compound specific stable isotope analysis. We are currently applying this technique to stream sediments to help determine which microorganisms are involved in the initial processing of DOM and the technique promises to be a useful tool for assigning ecological function to microbial populations.

Fatty Acid Proportions in Plasma Cholesterol Esters and Phospholipids Are Positively Correlated in Various Swedish Populations.

PubMed

Marklund, Matti; Pingel, Ronnie; Rosqvist, Fredrik; Lindroos, Anna Karin; Eriksson, Jan W; Vessby, Bengt; Oscarsson, Jan; Lind, Lars; Risérus, Ulf

2017-11-01

Background: Fatty acid (FA) proportions in cholesterol esters (CEs) and plasma phospholipids are widely used as dietary biomarkers. Information on how proportions in these fractions correlate could have implications for interpretation and use of FA biomarkers in observational and interventional studies. Objective: We investigated correlations between FA proportions in CEs and phospholipids in free-living individuals and assessed how diet-induced alterations of FA proportions correlate between fractions. Methods: Spearman's rank correlation coefficients ( r s ) between FA proportions (percentage of total FAs) in circulating CEs and phospholipids were calculated separately in 8 individual study populations including Swedish females and males ( N = 2052; age range: 11-84 y), and pooled by inverse-variance weighted meta-analysis. In addition, study populations were stratified by age, sex, body mass index (BMI; in kg/m 2 ), and diabetes status, and strata-specific r s were pooled by meta-analysis. In 2 randomized trials ( N = 79) in which dietary saturated FAs were isocalorically replaced with unsaturated FAs, treatment-wise calculations of r s were conducted between FA changes in CEs and phospholipids. Results: Overall, FA proportions in CEs and phospholipids correlated well and especially strongly for polyunsaturated FAs (PUFAs), with pooled r s (95% CIs) ranging from 0.74 (0.72, 0.76) for α-linolenic acid to 0.92 (0.91, 0.93) for eicosapentaenoic acid. Weak correlations (pooled r s < 0.4) were observed only for palmitic acid and stearic acid, with pooled r s (95% CIs): 0.29 (0.24, 0.33) and 0.30 (0.25, 0.34), respectively. Overall, correlations were not affected by age, sex, BMI, or diabetes status. Strong correlations ( r s ≥ 0.6) between diet-induced FA changes in CEs and phospholipids were observed for most PUFAs. Conclusions: Proportions of most FAs in CEs and phospholipids ranked individuals similarly, suggesting that FA proportions in these fractions can be used interchangeably in populations of diverse age, sex, body composition, and diabetes status. Caution is advised, however, when comparing results from studies assessing palmitic acid or stearic acid in different lipid fractions. © 2017 American Society for Nutrition.

[Antibodies to various phospholipids in SLE patients with primary antiphospholipid syndrome].

PubMed

Reshetniak, T M; Boĭtsekhovskaia, B; Alekberova, Z S; Kalashnikova, L A; Mach, E S; Zabek, Ia

1999-01-01

Antiphospholipid antibodies (aPL) represent a heterogeneous population reacting with negatively charged, less frequently neutral phospholipids and/or phospholipid-binding serum proteins. The study was made of antibodies to a wide spectrum of phospholipids: to negatively charged phospholipids such as phosphatide acid (aPA), cardiolipin (aCL), phosphatidylcholine (aPS), phosphatidylinositol (aPI), phosphatidylglycerol (aPG) and to neutrally charged phospholipid--phosphatidylcholine (aPC)--in 54 patients with systemic lupus erythematosus (SLE) and 29 patients with primary antiphospholipid syndrome (PAPS). The test for lupus anticoagulant (LAC) was also made. aPL in SLE patients free of antiphospholipid syndrome were detected in 61, 36 and 9% (aPC, aPS and aPA, aCL, respectively). aPI and aPG did not exceed normal values. 81% of SLE patients with antiphospholipid syndrome were LAC positive and 88% aPL positive. 60, 53, 44, 40, 13 and 17 were positive to aPC, aPA, aPS, aCL, aPG and aPI, respectively. Among patients with PAPS, the highest positivity was by LAC, occurrence of the other aPL was the same as in SLE patients with antiphospholipid syndrome. aCL, aPA, aPC, aPS, aPG and aPI were found in 55, 52, 41, 38, 31 and 21% of cases, respectively. In clinical manifestations of antiphospholipid syndrome and negative tests for LAC and aCL it is advisable to make tests for aPS and aPC. aPC occur in SLE patients more frequently than the other aPL: in 63% of SLE patients free of antiphospholipid syndrome and in 60% of SLE patients with this syndrome. Antibodies to other phospholipids, but not to cardiolipin, were present in SLE + APS in half of the cases but in SLE + PAPS in one third of the patients. Occurrence of aCL in the serum of SLE + PAPS patients is associated with the presence of antibodies to any other phospholipid irrespective of the charge. The severity of vascular changes did not correlate with the number of aPL variant found in the serum.

PHOSPHOLIPID COMPONENTS OF SINDBIS VIRUS,

DTIC Science & Technology

values. In addition to sphingomyelin, phosphatidyl choline , and phosphatidyl ethanolamine, other phospholipids were tentatively identified as phosphatidyl... inositol , phosphatidyl serine, phosphatidyl glycerol, and diphosphatidyl glycerol. Gas chromatographic analysis of the total fatty acids from

Improvements in clathrate modelling: I. The H 2O-CO 2 system with various salts

NASA Astrophysics Data System (ADS)

Bakker, Ronald J.; Dubessy, Jean; Cathelineau, Michel

1996-05-01

The formation of clathrates in fluid inclusions during microthermometric measurements is typical for most natural fluid systems which include a mixture of H 2O, gases, and electrolytes. A general model is proposed which gives a complete description of the CO 2 clathrate stability field between 253-293 K and 0-200 MPa, and which can be applied to NaCl, KCl, and CaCl 2 bearing systems. The basic concept of the model is the equality of the chemical potential of H 2O in coexisting phases, after classical clathrate modelling. None of the original clathrate models had used a complete set of the most accurate values for the many parameters involved. The lack of well-defined standard conditions and of a thorough error analysis resulted in inaccurate estimation of clathrate stability conditions. According to our modifications which include the use of the most accurate parameters available, the semi-empirical model for the binary H 2O-CO 2 system is improved by the estimation of numerically optimised Kihara parameters σ = 365.9 pm and ɛ/k = 174.44 K at low pressures, and σ = 363.92 pm and e/k = 174.46 K at high pressures. Including the error indications of individual parameters involved in clathrate modelling, a range of 365.08-366.52 pm and 171.3-177.8 K allows a 2% accuracy in the modelled CO 2 clathrate formation pressure at selected temperatures below Q 2 conditions. A combination of the osmotic coefficient for binary salt-H 2O systems and Henry's constant for gas-H 2O systems is sufficiently accurate to estimate the activity of H 2O in aqueous solutions and the stability conditions of clathrate in electrolyte-bearing systems. The available data on salt-bearing systems is inconsistent, but our improved clathrate stability model is able to reproduce average values. The proposed modifications in clathrate modelling can be used to perform more accurate estimations of bulk density and composition of individual fluid inclusions from clathrate melting temperatures. Our model is included in several computer programs which can be applied to fluid inclusion studies.

Thermodynamic Parameterization of Subduction-Zone Devolatilization and Application to Quantify Carbon Fluxes from Slab

NASA Astrophysics Data System (ADS)

Tian, M.; Katz, R. F.; Rees Jones, D. W.; May, D.

2017-12-01

Compared with other plate-tectonic boundaries, subduction zones (SZ) host the most drastic mechanical, thermal, and chemical changes. The transport of carbon through this complex environment is crucial to mantle carbon budget but remains the subject of active debate. Synthesis of field studies suggests that carbon subducted with the incoming slab is almost completely returned to the surface environment [Kelemen and Manning, 2015], whereas thermodynamic modelling indicates that a significant portion of carbon is retained in the slab and descends into the deep mantle [Gorman et al., 2006]. To address this controversy and quantify the carbon fluxes within SZs, it is necessary to treat the chemistry of fluid/volatile-rock interaction and the mechanics of porous fluid/volatile migration in a consistent modelling framework. This requirement is met by coupling a thermodynamic parameterization of de/re-volatilization with a two-phase flow model of subduction zones. The two-phase system is assumed to comprise three chemical components: rock containing only non-volatile oxides, H2O and CO2; the fluid phase includes only the latter two. Perple_X is used to map out the binary subsystems rock+H2O and rock+CO2; the results are parameterised in terms of volatile partition coefficients as a function of pressure and temperature. In synthesising the binary subsystems to describe phase equilibria that incorporate all three components, a Margules coefficient is introduced to account for non-ideal mixing of CO2/H2O in the fluid, such that the partition coefficients depend further on bulk composition. This procedure is applied to representative compositions of sediment, MORB, and gabbro for the slab, and peridotite for the mantle. The derived parameterization of each rock type serves as a lightweight thermodynamic module interfaceable with two-phase flow models of SZs. We demonstrate the application of this thermodynamic module through a simple model of carbon flux with a prescribed flow direction through (and out of) the slab. This model allows us to evaluate the effects of flow path and lithology on carbon storage within the slab.

Genetics Home Reference: intrahepatic cholestasis of pregnancy

MedlinePlus

... such as women of Araucanian Indian ancestry in Chile or women of Scandinavian ancestry. This condition is ... reduce the movement of phospholipids into bile. The lack of phospholipids available to bind to bile acids ...

X-ray study of the structure of phospholipid monolayers on the water surface

NASA Astrophysics Data System (ADS)

Asadchikov, V. E.; Tikhonov, A. M.; Volkov, Yu. O.; Roshchin, B. S.; Ermakov, Yu. A.; Rudakova, E. B.; D'yachkova, I. G.; Nuzhdin, A. D.

2017-10-01

The possibility of laboratory X-ray reflectometry study of the structure of dimyristoyl phosphatidylserine (DMPS) phospholipid monolayers on the water surface in various phase states has been demonstrated.

Protein-Phospholipid Interactions in Nonclassical Protein Secretion: Problem and Methods of Study

PubMed Central

Prudovsky, Igor; Kumar, Thallapuranam Krishnaswamy Suresh; Sterling, Sarah; Neivandt, David

2013-01-01

Extracellular proteins devoid of signal peptides use nonclassical secretion mechanisms for their export. These mechanisms are independent of the endoplasmic reticulum and Golgi. Some nonclassically released proteins, particularly fibroblast growth factors (FGF) 1 and 2, are exported as a result of their direct translocation through the cell membrane. This process requires specific interactions of released proteins with membrane phospholipids. In this review written by a cell biologist, a structural biologist and two membrane engineers, we discuss the following subjects: (i) Phenomenon of nonclassical protein release and its biological significance; (ii) Composition of the FGF1 multiprotein release complex (MRC); (iii) The relationship between FGF1 export and acidic phospholipid externalization; (iv) Interactions of FGF1 MRC components with acidic phospholipids; (v) Methods to study the transmembrane translocation of proteins; (vi) Membrane models to study nonclassical protein release. PMID:23396106