Nanofibrillated Cellulose Templated Membranes with High Permeance.

PubMed

Orsolini, Paola; Marchesi D'Alvise, Tommaso; Boi, Cristiana; Geiger, Thomas; Caseri, Walter R; Zimmermann, Tanja

2016-12-14

One of the most challenging aspects of using nanofibrillated cellulose (NFC) for membranes production is their limited permeance. When NFC membranes are produced from aqueous suspensions, depending on their grammage, the permeances are in the range of a few decades of L/(hm 2 MPa) not matching satisfactory filtration times. We present a fast and sustainable solution to increase the permeances of such membranes through a combination of solvent exchange of the NFC suspension with ethanol and the use of a removable template, a mixture of calcium compounds (CC). The effect of the CC/NFC ratio was screened for various concentrations. The permeance of water could be increased by as much as 2-3 times as compared to nontemplated membranes. Further, the membranes showed the ability for penetration of water-soluble macromolecules, contaminant rejection of suspended solid particles, and thus fluids (such as orange juice) could be concentrated, with a view to applications in food industry.

Evaluation of γ-cyclodextrin effect on permeation of lipophilic drugs: application of cellophane/fused octanol membrane.

PubMed

Muankaew, Chutimon; Jansook, Phatsawee; Loftsson, Thorsteinn

2017-06-01

According to the Biopharmaceutics Classification System, oral bioavailability of drugs is determined by their aqueous solubility and the ability of the dissolved drug molecules to permeate lipophilic biological membranes. Similarly topical bioavailability of ophthalmic drugs is determined by their solubility in the aqueous tear fluid and their ability to permeate the lipophilic cornea. Enabling pharmaceutical excipients such as cyclodextrins can have profound effect on the drug bioavailability. However, to fully appreciate such enabling excipients, the relationship between their effects and the physicochemical properties of the permeating drug needs to be known. In this study, the permeation enhancing effect of γ-cyclodextrin (γCD) on saturated drug solutions containing hydrocortisone (HC), irbesartan (IBS), or telmisartan (TEL) was evaluated using cellophane and fused cellulose-octanol membranes in a conventional Franz diffusion cell system. The flux (J), the flux ratio (J R ) and the apparent permeability coefficients (P app ) demonstrate that γCD increases drug permeability. However, its efficacy depends on the drug properties. Addition of γCD increased P app of HC (unionized) and IBS (partially ionized) through the dual membrane but decreased the P app of TEL (fully ionized) that displays low complexation efficacy. The dual cellophane-octanol membrane system was simple to use and gave reproducible results.

Microfabrication of hybrid fluid membrane for microengines

NASA Astrophysics Data System (ADS)

Chutani, R.; Formosa, F.; de Labachelerie, M.; Badel, A.; Lanzetta, F.

2015-12-01

This paper describes the microfabrication and dynamic characterization of thick membranes providing a technological solution for microengines. The studied membranes are called hybrid fluid-membrane (HFM) and consist of two thin membranes that encapsulate an incompressible fluid. This work details the microelectromechanical system (MEMS) scalable fabrication and characterization of HFMs. The membranes are composite structures based on Silicon spiral springs embedded in a polymer (RTV silicone). The anodic bonding of multiple stacks of Si/glass structures, the fluid filling and the sealing have been demonstrated. Various HFMs were successfully fabricated and their dynamic characterization demonstrates the agreement between experimental and theoretical results.

Membrane materials for storing biological samples intended for comparative nanotoxicological testing

NASA Astrophysics Data System (ADS)

Metelkin, A.; Kuznetsov, D.; Kolesnikov, E.; Chuprunov, K.; Kondakov, S.; Osipov, A.; Samsonova, J.

2015-11-01

The study is aimed at identifying the samples of most promising membrane materials for storing dry specimens of biological fluids (Dried Blood Spots, DBS technology). Existing sampling systems using cellulose fiber filter paper have a number of drawbacks such as uneven distribution of the sample spot, dependence of the spot spreading area on the individual biosample properties, incomplete washing-off of the sample due to partially inconvertible sorption of blood components on cellulose fibers, etc. Samples of membrane materials based on cellulose, polymers and glass fiber with applied biosamples were studied using methods of scanning electron microscopy, FT-IR spectroscopy and surface-wetting measurement. It was discovered that cellulose-based membrane materials sorb components of biological fluids inside their structure, while membranes based on glass fiber display almost no interaction with the samples and biological fluid components dry to films in the membrane pores between the structural fibers. This characteristic, together with the fact that membrane materials based on glass fiber possess sufficient strength, high wetting properties and good storage capacity, attests them as promising material for dry samples of biological fluids storage systems.

In silico and in vitro prediction of gastrointestinal absorption from potential drug eremantholide C.

PubMed

Caldeira, Tamires G; Saúde-Guimarães, Dênia A; Dezani, André B; Serra, Cristina Helena Dos Reis; de Souza, Jacqueline

2017-11-01

Analysis of the biopharmaceutical properties of eremantholide C, sesquiterpene lactone with proven pharmacological activity and low toxicity, is required to evaluate its potential to become a drug. Preliminary analysis of the physicochemical characteristics of eremantholide C was performed in silico. Equilibrium solubility was evaluated using the shake-flask method, at 37.0 °C, 100 rpm during 72 h in biorelevant media. The permeability was analysed using parallel artificial membrane permeability assay, at 37.0 °C, 50 rpm for 5 h. The donor compartment was composed of an eremantholide C solution in intestinal fluid simulated without enzymes, while the acceptor compartment consisted of phosphate buffer. Physicochemical characteristics predicted in silico indicated that eremantholide C has a low solubility and high permeability. In-vitro data of eremantholide C showed low solubility, with values for the dose/solubility ratio (ml): 9448.82, 10 389.61 e 15 000.00 for buffers acetate (pH 4.5), intestinal fluid simulated without enzymes (pH 6.8) and phosphate (pH 7.4), respectively. Also, it showed high permeability, with effective permeability of 30.4 × 10 -6 cm/s, a higher result compared with propranolol hydrochloride (9.23 × 10 -6 cm/s). The high permeability combined with its solubility, pharmacological activity and low toxicity demonstrate the importance of eremantholide C as a potential drug candidate. © 2017 Royal Pharmaceutical Society.

A fluid membrane enhances the velocity of cargo transport by small teams of kinesin-1

NASA Astrophysics Data System (ADS)

Li, Qiaochu; Tseng, Kuo-Fu; King, Stephen J.; Qiu, Weihong; Xu, Jing

2018-03-01

Kinesin-1 (hereafter referred to as kinesin) is a major microtubule-based motor protein for plus-end-directed intracellular transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized "motile fraction" to overcome this challenge and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro and employed optical trapping to quantify the transport of membrane-enclosed cargos versus traditional membrane-free cargos under identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins. Importantly, enclosing a cargo in a fluid lipid membrane did not impact single-kinesin transport, indicating that membrane-dependent velocity enhancement for team-based transport arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for fast delivery of cargos in live cells.

Permeabilization assay for antimicrobial peptides based on pore-spanning lipid membranes on nanoporous alumina.

PubMed

Neubacher, Henrik; Mey, Ingo; Carnarius, Christian; Lazzara, Thomas D; Steinem, Claudia

2014-04-29

Screening tools to study antimicrobial peptides (AMPs) with the aim to optimize therapeutic delivery vectors require automated and parallelized sampling based on chip technology. Here, we present the development of a chip-based assay that allows for the investigation of the action of AMPs on planar lipid membranes in a time-resolved manner by fluorescence readout. Anodic aluminum oxide (AAO) composed of cylindrical pores with a diameter of 70 nm and a thickness of up to 10 μm was used as a support to generate pore-spanning lipid bilayers from giant unilamellar vesicle spreading, which resulted in large continuous membrane patches sealing the pores. Because AAO is optically transparent, fluid single lipid bilayers and the underlying pore cavities can be readily observed by three-dimensional confocal laser scanning microscopy (CLSM). To assay the membrane permeabilizing activity of the AMPs, the translocation of the water-soluble dyes into the AAO cavities and the fluorescence of the sulforhodamine 101 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanol-l-amine triethylammonium salt (Texas Red DHPE)-labeled lipid membrane were observed by CLSM in a time-resolved manner as a function of the AMP concentration. The effect of two different AMPs, magainin-2 and melittin, was investigated, showing that the concentrations required for membrane permeabilization and the kinetics of the dye entrance differ significantly. Our results are discussed in light of the proposed permeabilization models of the two AMPs. The presented data demonstrate the potential of this setup for the development of an on-chip screening platform for AMPs.

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

PubMed

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

2016-04-01

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

Advances in Constraining Solubilities of H-O-C-S-Cl-bearing Fluids in Silicate Melts

NASA Astrophysics Data System (ADS)

Webster, J. D.

2009-12-01

Magmatic-hydrothermal fluids that are variably enriched in the volatile components H2O, CO2/CH4, H2S/SO2, Cl, F, ± B alter rock; dissolve, transport, and deposit ore metals, and drive volcanism. The efficacy of these processes varies directly with the compositions and quantities, and in particular, with the molar volumes of the fluids involved. Although natural hydrothermal fluids are geochemically diverse, experimental constraints on volatile solubilities in silicate melts are largely limited to two volatiles. Recent experimental research, however, has begun to address mutual solubility relationships of three and four volatiles in felsic to intermediate aluminosilicate melts at shallow crustal pressures. Following well-established correlations demonstrating that as little as a few hundred to thousand ppm CO2 or Cl reduce H2O solubility in melts, and hence enhance the tendency for magma to exsolve one or two fluid phases, recent work shows fundamentally important solubility relationships involving H2O, S, and Cl. Research on rhyodacitic (Botcharnikov et al., 2004) and phonolitic melts at 200 MPa reveals that hundreds to thousands of ppm S will reduce Cl solubility in these melts. Thus, S reduces Cl solubility, which in turn reduces H2O solubility in melts. Other investigations have determined that CaSO4 solubility in oxidizing hydrothermal fluids varies directly with the concentrations of NaCl ± KCl in these fluids (Newton and Manning, 2005; Webster et al., 2009). The CaSO4 contents in the most alkali chloride-enriched fluids exceed 60 wt.%. It follows that some mineralizing saline magmatic fluids are strongly enriched in Ca, Na, K, Cl, SO4, and reduced S species. Research on H2O-, CO2-, and Cl-bearing melts at 200 MPa also highlights critical reciprocal volatile solubility behavior. Work at 1200°C on andesitic melts saturated in two fluids determines that the presence of CO2 enlarges the immiscibility gap for vapor plus brine and increases the activities of H2O and Cl (Botcharnikov et al. 2007). Conversely, other work involving Cl-enriched phonolitic melts plus two fluids at 900°C observes that the presence of Cl strongly reduces CO2 solubility in the melt. In fact, for runs containing as much as 80 mole percent CO2 in the fluid, the CO2/CO3 contents of the melts were reduced to values below the limit of detection for FTIR (< ca. 30-40 ppm). Thus, Cl works to reduce CO2 solubility, which in turn reduces H2O solubility in phonolitic melts. Current work on the solubility of H-O-C-S in haplogranitic melts at 200 MPa demonstrates that the addition of C reduces the (fluid/melt) partition coefficient for S. In addition, these experimentally determined partition coefficients decrease in the order CO2 > S > H2O, and their ranges are virtually identical to and thus confirm modeled values computed (Scaillet and Pichavant, 2003) for pre-eruptive magmatic fluids based on volatile fugacities of volcanic gases of arc-related magmas. Botcharnikov R et al (2004) Chem. Geol. 213, 207-225. Botcharnikov R, Holtz F, Behrens H (2007) Eur. J. Mineral. 19, 671-680. Newton R, Manning C (2005) J. Petrol. 46, 701-716. Scaillet B, Pichavant M (2003) Volcanic Degassing, Geol. Soc. Spec. Pub. 213, 23-52. Webster J, Sintoni M, De Vivo B (2009) Chem. Geol. 263, 19-36.

Thermodynamic Modeling of Gas Transport in Glassy Polymeric Membranes.

PubMed

Minelli, Matteo; Sarti, Giulio Cesare

2017-08-19

Solubility and permeability of gases in glassy polymers have been considered with the aim of illustrating the applicability of thermodynamically-based models for their description and prediction. The solubility isotherms are described by using the nonequilibrium lattice fluid (NELF) (model, already known to be appropriate for nonequilibrium glassy polymers, while the permeability isotherms are described through a general transport model in which diffusivity is the product of a purely kinetic factor, the mobility coefficient, and a thermodynamic factor. The latter is calculated from the NELF model and mobility is considered concentration-dependent through an exponential relationship containing two parameters only. The models are tested explicitly considering solubility and permeability data of various penetrants in three glassy polymers, PSf, PPh and 6FDA-6FpDA, selected as the reference for different behaviors. It is shown that the models are able to calculate the different behaviors observed, and in particular the permeability dependence on upstream pressure, both when it is decreasing as well as when it is increasing, with no need to invoke the onset of additional plasticization phenomena. The correlations found between polymer and penetrant properties with the two parameters of the mobility coefficient also lead to the predictive ability of the transport model.

Thermodynamic Modeling of Gas Transport in Glassy Polymeric Membranes

PubMed Central

Minelli, Matteo; Sarti, Giulio Cesare

2017-01-01

Solubility and permeability of gases in glassy polymers have been considered with the aim of illustrating the applicability of thermodynamically-based models for their description and prediction. The solubility isotherms are described by using the nonequilibrium lattice fluid (NELF) (model, already known to be appropriate for nonequilibrium glassy polymers, while the permeability isotherms are described through a general transport model in which diffusivity is the product of a purely kinetic factor, the mobility coefficient, and a thermodynamic factor. The latter is calculated from the NELF model and mobility is considered concentration-dependent through an exponential relationship containing two parameters only. The models are tested explicitly considering solubility and permeability data of various penetrants in three glassy polymers, PSf, PPh and 6FDA-6FpDA, selected as the reference for different behaviors. It is shown that the models are able to calculate the different behaviors observed, and in particular the permeability dependence on upstream pressure, both when it is decreasing as well as when it is increasing, with no need to invoke the onset of additional plasticization phenomena. The correlations found between polymer and penetrant properties with the two parameters of the mobility coefficient also lead to the predictive ability of the transport model. PMID:28825619

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

PubMed

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

2018-04-15

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

The Toxicological Geochemistry of Dusts, Soils, and Other Earth Materials: Insights From In Vitro Physiologically-based Geochemical Leach Tests

NASA Astrophysics Data System (ADS)

Plumlee, G. S.; Ziegler, T. L.; Lamothe, P.; Meeker, G. P.; Sutley, S.

2003-12-01

Exposure to mineral dusts, soils, and other earth materials results in chemical reactions between the materials and different body fluids that include, depending upon the exposure route, lung fluids, gastrointestinal fluids, and perspiration. In vitro physiologically-based geochemical leach tests provide useful insights into these chemical reactions and their potential toxicological implications. We have conducted such leach tests on a variety of earth materials, including asbestos, volcanic ash, dusts from dry lake beds, mine wastes, wastes left from the roasting of mercury ores, mineral processing wastes, coal dusts and coal fly ash, various soils, and complex dusts generated by the World Trade Center collapse. Size-fractionated samples of earth materials that have been well-characterized mineralogically and chemically are reacted at body temperature (37 C) for periods from 2 hours up to multiple days with various proportions of simulated lung, gastric, intestinal, and/or plasma-based fluids. Results indicate that different earth materials may have quite different solubility and dissolution behavior in vivo, depending upon a) the mineralogic makeup of the material, and b) the exposure route. For example, biodurable minerals such as asbestos and volcanic ash particles, whose health effects result because they dissolve very slowly in vivo, bleed off low levels of trace metals into the simulated lung fluids; these include metals such as Fe and Cr that are suspected by health scientists of contributing to the generation of reactive oxygen species and resulting DNA damage in vivo. In contrast, dry lake bed dusts and concrete-rich dusts are highly alkaline and bioreactive, and cause substantial pH increases and other chemical changes in the simulated body fluids. Many of the earth materials tested contain a variety of metals that can be quite soluble (bioaccessible), depending upon the material and the simulated body fluid composition. For example, due to their acidic pH and high chloride concentrations, simulated gastric fluids are most efficient at solubilizing metals such as Hg, Pb, Zn, and others that form strong chloride complexes; although these metals tend to partially reprecipitate in the near-neutral simulated intestinal fluids, complexes with organic ligands (i.e., amino and carboxylic acids) enhance their solubility. These metals are also quite soluble in near-neutral, protein-rich plasma-based fluids because they form strong complexes with the proteins. In contrast, metalloids that form oxyanion species (such as As, Cr, Mo, W) are commonly more soluble in near-neutral pH simulated lung fluids than in simulated gastric fluids.

Aspirin Increases the Solubility of Cholesterol in Lipid Membranes

NASA Astrophysics Data System (ADS)

Alsop, Richard; Barrett, Matthew; Zheng, Sonbo; Dies, Hannah; Rheinstadter, Maikel

2014-03-01

Aspirin (ASA) is often prescribed for patients with high levels of cholesterol for the secondary prevention of myocardial events, a regimen known as the Low-Dose Aspirin Therapy. We have recently shown that Aspirin partitions in lipid bilayers. However, a direct interplay between ASA and cholesterol has not been investigated. Cholesterol is known to insert itself into the membrane in a dispersed state at moderate concentrations (under ~37.5%) and decrease fluidity of membranes. We prepared model lipid membranes containing varying amounts of both ASA and cholesterol molecules. The structure of the bilayers as a function of ASA and cholesterol concentration was determined using high-resolution X-ray diffraction. At cholesterol levels of more than 40mol%, immiscible cholesterol plaques formed. Adding ASA to the membranes was found to dissolve the cholesterol plaques, leading to a fluid lipid bilayer structure. We present first direct evidence for an interaction between ASA and cholesterol on the level of the cell membrane.

Mass Transport through Nanostructured Membranes: Towards a Predictive Tool

PubMed Central

Darvishmanesh, Siavash; Van der Bruggen, Bart

2016-01-01

This study proposes a new mechanism to understand the transport of solvents through nanostructured membranes from a fundamental point of view. The findings are used to develop readily applicable mathematical models to predict solvent fluxes and solute rejections through solvent resistant membranes used for nanofiltration. The new model was developed based on a pore-flow type of transport. New parameters found to be of fundamental importance were introduced to the equation, i.e., the affinity of the solute and the solvent for the membrane expressed as the hydrogen-bonding contribution of the solubility parameter for the solute, solvent and membrane. A graphical map was constructed to predict the solute rejection based on the hydrogen-bonding contribution of the solubility parameter. The model was evaluated with performance data from the literature. Both the solvent flux and the solute rejection calculated with the new approach were similar to values reported in the literature. PMID:27918434

Solubility of gases and liquids in glassy polymers.

PubMed

De Angelis, Maria Grazia; Sarti, Giulio C

2011-01-01

This review discusses a macroscopic thermodynamic procedure to calculate the solubility of gases, vapors, and liquids in glassy polymers that is based on the general procedure provided by the nonequilibrium thermodynamics for glassy polymers (NET-GP) method. Several examples are presented using various nonequilibrium (NE) models including lattice fluid (NELF), statistical associating fluid theory (NE-SAFT), and perturbed hard sphere chain (NE-PHSC). Particular applications illustrate the calculation of infinite-dilution solubility coefficients in different glassy polymers and the prediction of solubility isotherms for different gases and vapors in pure polymers as well as in polymer blends. The determination of model parameters is discussed, and the predictive abilities of the models are illustrated. Attention is also given to the solubility of gas mixtures and solubility isotherms in nanocomposite mixed matrices. The fractional free volume determined from solubility data can be used to correlate solute diffusivities in mixed matrices.

Copper Solubility and Speciation in Mineral-Buffered Fluids at Crust to Upper Mantle Conditions

NASA Astrophysics Data System (ADS)

Hack, A. C.; Mavrogenes, J. A.; Berry, A. J.

2003-12-01

Fluid inclusions, synthesised in a piston-cylinder apparatus, were used to trap representative high P-T fluid samples under mineral-buffered conditions in the systems Cu2O-MgO-SiO2-HCl-H2O and Cu-K2O-Al2O3-SiO2-Fe3O4-Fe2O3-HCl-H2O at up to 850° C and 1.7 GPa, and as a function of salinity to 11 mol/kg Cl. Copper solubility and speciation were obtained by analysing individual fluid inclusions by excimer laser ablation inductively coupled mass spectrometry (LA-ICP-MS), proton induced X-ray emission (PIXE) and Cu K-edge X-ray absorption near edge structure (XANES) spectroscopy. Quenched capsule fluids were also analysed. At 710° C copper-cuprite-talc-quartz solubility in aqueous fluid containing 1 mol/kg Cl increases with P to at least 1.7 GPa. Conspicuously, with increasing P (> ˜ 0.5 GPa) talc solubility increases and molal Cu concentrations exceed those of Cl. Isothermal Cu solubility appears to mimic the solubility isopleths in the SiO2-H2O system. Solubility trends suggest that the stability field of copper(I) hydroxide complexes (e.g. Cu(OH)aq) expands to higher salinities such that H2O may become an effective ligand at high-P. At constant P (e.g. 0.35 GPa) solubility decreases with increasing T (i.e. > 525° C). High-T Cu K-edge XANES spectra of single homogenised synthetic fluid inclusions indicate that highly coordinated chlorocopper(I) complexes (e.g. Cu:Cl, 1:3 to 4) predominate at high salinity, whereas lower-order linear Cu-Cl coordination predominates at lower salinities, in fluids buffered by quartz-talc-copper-cuprite. This is consistent with the interpretation of the solubility data. At equivalent salinity, T and P conditions, spectra for fluids buffered by native copper-orthoclase-sillimanite-quartz-magnetite-hematite show no evidence for higher-order chlorocopper(I) complexes. Preliminary extended X-ray absorption fine structure data for these latter inclusions indicate that [CuCl2]- predominates. The stability of higher-order complexes is strongly coupled to HCl concentrations, which at constant P and T is determined by both the specific mineral assemblage and total salinity. This is the first spectroscopic evidence for highly coordinated chlorocopper(I) complexes in supercritical fluids. Furthermore, the speciation dependence on the buffering mineral assemblage has not been recognized previously. Similarly, this is the first experimental confirmation that copper concentrations in mineral-buffered fluids can be extremely high, e.g. ˜ 10 wt%, substantiating inferences based on natural fluid inclusions associated with porphyry copper ore deposits.

Influence of fermentation liquid from waste activated sludge on anoxic/oxic- membrane bioreactor performance: Nitrogen removal, membrane fouling and microbial community.

PubMed

Han, Xiaomeng; Zhou, Zhen; Mei, Xiaojie; Ma, Yan; Xie, Zhenfang

2018-02-01

In order to investigate effects of waste activated sludge (WAS) fermentation liquid on anoxic/oxic- membrane bioreactor (A/O-MBR), two A/O-MBRs with and without WAS fermentation liquid addition were operated in parallel. Results show that addition of WAS fermentation liquid clearly improved denitrification efficiency without deterioration of nitrification, while severe membrane fouling occurred. WAS fermentation liquid resulted in an elevated production of proteins and humic acids in bound extracellular polymeric substance (EPS) and release of organic matter with high MW fractions in soluble microbial product (SMP) and loosely bound EPS (LB-EPS). Measurement of deposition rate and fluid structure confirmed increased fouling potential of SMP and LB-EPS. γ-Proteobacteria and Ferruginibacter, which can secrete and export EPS, were also found to be abundant in the MBR with WAS fermentation liquid. It is implied that when WAS fermentation liquid was applied, some operational steps to control membrane fouling should be employed. Copyright © 2017 Elsevier Ltd. All rights reserved.

DEMONSTRATION OF PILOT-SCALE PERVAPORATION SYSTEMS FOR VOLATILE ORGANIC COMPOUND REMOVAL FROM A SURFACTANT ENHANCED AQUIFER REMEDIATION FLUID. II. HOLLOW FIBER MEMBRANE MODULES

EPA Science Inventory

Pilot-scale demonstration of pervaporation-based removal of volatile organic compounds from a surfactant enhanced aquifer remediation (SEAR) fluid has been conducted at USEPA's Test & Evaluation Facility using hollow fiber membrane modules. The membranes consisted of microporous...

Soluble ST2, a Modulator of the Inflammatory Response, in Preterm and Term Labor

PubMed Central

Stampalija, Tamara; Chaiworapongsa, Tinnakorn; Romero, Roberto; Tarca, Adi L.; Bhatti, Gaurav; Chiang, Po Jen; Than, Nandor Gabor; Ferrazzi, Enrico; Hassan, Sonia S.; Yeo, Lami

2014-01-01

Objective Intra-amniotic infection/inflammation (IAI) is causally linked with spontaneous preterm labor and delivery. The ST2L receptor and its soluble form (sST2) are capable of binding to interleukin (IL)-33, a member of the IL-1 superfamily. Members of this cytokine family have been implicated in the onset of spontaneous preterm labor in the context of infection. Soluble ST2 has anti-inflammatory properties, and plasma concentrations are elevated in systemic inflammation, such as sepsis, acute pyelonephritis in pregnancy and the fetal inflammatory response syndrome. The aims of this study were to examine: 1) whether amniotic fluid concentrations of sST2 change with IAI, preterm, and term parturition; and 2) if mRNA expression of ST2 in the chorioamniotic membranes changes with acute histologic chorioamnionitis in women who deliver preterm. Methods A cross-sectional study was conducted to determine amniotic fluid concentrations of sST2 in: 1) women with preterm labor (PTL) who delivered at term (n=49); 2) women with PTL who delivered preterm without IAI (n=21); 3) women with PTL who delivered preterm with IAI (n=31); 4) term pregnancies not in labor (n=13); and 5) term pregnancies in labor (n=43). The amniotic fluid concentration of sST2 was determined by ELISA. The mRNA expression of ST2 in the chorioamniotic membranes of women who delivered preterm with (n=24), and without acute histologic chorioamnionitis (n=19) was determined by qRT-PCR. Results 1) Patients with PTL who delivered preterm with IAI had a lower median amniotic fluid concentration of sST2 compared to those with PTL who delivered preterm without IAI [median 410 ng/mL, inter-quartile range (IQR) 152-699 ng/mL vs. median 825 ng/mL, IQR 493-1216 ng/mL; p=0.0003] and those with PTL who delivered at term [median 410 ng/mL, IQR 152-699 ng/mL vs. median 673 ng/mL, IQR 468-1045ng/mL; p=0.0003]; 2) no significant differences in the median amniotic fluid concentration of sST2 were observed between patients with PTL who delivered at term and those who delivered preterm without IAI (p=0.4), and between women at term in labor and those at term not in labor (p=0.9); 3) the mean mRNA expression of ST2 was 4-fold lower in women who delivered preterm with acute histologic chorioamnionitis than in those without this lesion (p=0.008). Conclusions The median sST2 amniotic fluid concentration and mRNA expression of ST2 by chorioamniotic membranes is lower in PTL associated with IAI and acute histologic chorioamnionitis than in PTL without these conditions. Changes in the median amniotic fluid sST2 concentration are not observed in preterm and term parturition without IAI. Thus, amniotic fluid sST2 in the presence of IAI behaves differently when compared to sST2 in the plasma of individuals affected by fetal inflammatory response syndrome, acute pyelonephritis in pregnancy, and adult sepsis. Decreased concentrations of sST2 in IAI are likely to promote a pro-inflammatory response, which is important for parturition in the context of infection. PMID:23688338

Activation of the receptor for advanced glycation end products system in women with severe preeclampsia.

PubMed

Oliver, Emily A; Buhimschi, Catalin S; Dulay, Antonette T; Baumbusch, Margaret A; Abdel-Razeq, Sonya S; Lee, Sarah Y; Zhao, Guomao; Jing, Shichu; Pettker, Christian M; Buhimschi, Irina A

2011-03-01

Activation of the receptor for advanced glycation end products (RAGE) mediates cellular injury. Soluble forms of RAGE [soluble RAGE (sRAGE), endogenous secretory (esRAGE)] bind RAGE ligands, thereby preventing downstream signaling and damage. The objective of the study was to characterize the changes in maternal serum, amniotic fluid, and cord blood soluble receptor for advanced glycation end products (sRAGE) during physiological gestation and to provide insight into mechanisms responsible for RAGE activation in preeclampsia. This was a cross-sectional study at a tertiary university hospital. We studied 135 women in the following groups: nonpregnant controls (n = 16), healthy pregnant controls (n = 68), pregnant women with chronic hypertension (n = 13), or pregnant women with severe preeclampsia (sPE; n = 38). sRAGE and esRAGE levels were evaluated in vivo by ELISA in maternal serum, amniotic fluid, and cord blood and in vitro after stimulation of the amniochorion and placental explants with lipopolysaccharide or xanthine/xanthine oxidase. Placenta and amniochorion were immunostained for RAGE. Real-time quantitative PCR measured RAGE mRNA. Pregnant women had significantly decreased serum sRAGE compared with nonpregnant subjects (P < 0.001). sPE women had higher serum and amniotic fluid sRAGE and esRAGE relative to those expected for gestational age (P < 0.001). Cord blood sRAGE remained unaffected by sPE. RAGE immunoreactivity and mRNA expression appeared elevated in the amniochorion of sPE women. Xanthine/xanthine oxidase (but not lipopolysaccharide) significantly up-regulated the release of sRAGE (P < 0.001) in the amniochorion explant system. Fetal membranes are a rich source of sRAGE. Elevated maternal serum and amniotic fluid sRAGE and esRAGE, paralleled by increased RAGE expression in the amniochorion, suggest activation of this system in sPE.

Transport of water and solutes in reverse osmosis and nanofiltration membranes

NASA Astrophysics Data System (ADS)

Cahill, David

2009-03-01

The polyamide active layers of reverse osmosis and nanofiltration membranes used for water purification are real-world examples of nanoscale functional materials: the active layer is only ˜100 nm thick. Because the active layer is formed by a process of interfacial polymerization, the structure and composition of the membrane is highly inhomogeneous and even such basic physical and chemical properties as the atomic density, swelling in water, the distribution of charged species between water and membrane, and the mobility of water and ions, are poorly understood. We are using Rutherford backscattering spectrometry (RBS) to determine the composition, roughness, and thickness of the membrane; reveal the surprisingly high solubility of salt ions in the polymer active layer; analyze the acid-base chemistry of charged functional groups; and determine the degree of polymer cross-linking. Measurements of mass-uptake and adsorption-induced mechanical stress of membranes in humid air enable us to determine the water solubility, specific volume of water, and the mechanical strength of the membrane. Comparisons between these equilibrium data and the permeability of the membrane to water and salts show that the mobility of water molecules in the membrane approaches the mobility of bulk water, and that the rejection of salt ions is accomplished by low mobility, not low solubility. My collaborators in this work are Xijing Zhang, Orlando Coronell, and Prof. Benito Mariñas.

Fabrication, Characterization, In vitro Evaluation of Solid Lipid Nanoemulsion of Flunarizine dihydrochloride for Nasal Delivery.

PubMed

Newton, Maria J; Harjot, Kaur

2017-01-01

Flunarizine dihydrochloride (FHC) is used for the prophylaxis to migraine. Flunarizine has solubility problems which is practically insoluble in water and alcohol. Nanoemulsion is the approach to increase the solubility of the insoluble drugs. Nanoemulsions of FHC was prepared which can be given through the alternate route such as nasal drug delivery for migraine. In this research work the solubility of the poorly soluble FHC was successfully improved by preparing it as a nano emulsion. Nanoemulsions can pass through the biological membrane easily so it can be delivered through nasal mucosa by which it may provide a quicker onset of action. The currently available dosage forms are in the form of tablet. The formulations were prepared by using Glycerl Monostearate (GMS), Tween 80 as surfactant and PEG 400: Ethanol as co-surfactant in the distilled water. Nanoemulsions were prepared by step by step procedure. The prepared nanoemulsions were analyzed preliminarily by Master Sizer followed by Zeta Sizer by using the technique Dynamic Photon Correlation Spectroscopy. The best nanoemulsion was subjected to Zeta Potential study. The TEM analysis was carried out on the best formulation to gain the detailed information about the formulation. The best formulation was selected based on the physical appearance, homogenecity of the preparation, Preliminary Master Sizer analysis report, Secondary Zeta Sizer analysis report with Zeta Potential and TEM. The best formulation demonstrated the size in nano range with improved solubility. The FHC nano emulsion was prepared successfully which improved the solubility of the drug. The drug release study on simulated nasal fluid revealed that the preparation is suitable to be delivered through the nasal route. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Theory of Ion and Water Transport in Reverse-Osmosis Membranes

NASA Astrophysics Data System (ADS)

Oren, Y. S.; Biesheuvel, P. M.

2018-02-01

We present a theory for ion and water transport through reverse-osmosis (RO) membranes based on a Maxwell-Stefan framework combined with hydrodynamic theory for the reduced motion of particles in thin pores. We take into account all driving forces and frictions both on the fluid (water) and on the ions including ion-fluid friction and ion-wall friction. By including the acid-base characteristic of the carbonic acid system, the boric acid system, H3O+/OH- , and the membrane charge, we locally determine p H , the effective charge of the membrane, and the dissociation degree of carbonic acid and boric acid. We present calculation results for an experiment with fixed feed concentration, where effluent composition is a self-consistent function of fluxes through the membrane. A comparison with experimental results from literature for fluid flow vs pressure, and for salt and boron rejection, shows that our theory agrees very well with the available data. Our model is based on realistic assumptions for the effective size of the ions and makes use of a typical pore size of a commercial RO membrane.

Tissue Specificity of Human Angiotensin I-Converting Enzyme

PubMed Central

Kryukova, Olga V.; Tikhomirova, Victoria E.; Golukhova, Elena Z.; Evdokimov, Valery V.; Kalantarov, Gavreel F.; Trakht, Ilya N.; Schwartz, David E.; Dull, Randal O.; Gusakov, Alexander V.; Uporov, Igor V.; Kost, Olga A.; Danilov, Sergei M.

2015-01-01

Background Angiotensin-converting enzyme (ACE), which metabolizes many peptides and plays a key role in blood pressure regulation and vascular remodeling, as well as in reproductive functions, is expressed as a type-1 membrane glycoprotein on the surface of endothelial and epithelial cells. ACE also presents as a soluble form in biological fluids, among which seminal fluid being the richest in ACE content - 50-fold more than that in blood. Methods/Principal Findings We performed conformational fingerprinting of lung and seminal fluid ACEs using a set of monoclonal antibodies (mAbs) to 17 epitopes of human ACE and determined the effects of potential ACE-binding partners on mAbs binding to these two different ACEs. Patterns of mAbs binding to ACEs from lung and from seminal fluid dramatically differed, which reflects difference in the local conformations of these ACEs, likely due to different patterns of ACE glycosylation in the lung endothelial cells and epithelial cells of epididymis/prostate (source of seminal fluid ACE), confirmed by mass-spectrometry of ACEs tryptic digests. Conclusions Dramatic differences in the local conformations of seminal fluid and lung ACEs, as well as the effects of ACE-binding partners on mAbs binding to these ACEs, suggest different regulation of ACE functions and shedding from epithelial cells in epididymis and prostate and endothelial cells of lung capillaries. The differences in local conformation of ACE could be the base for the generation of mAbs distingushing tissue-specific ACEs. PMID:26600189

Weak bases and formation of a less soluble lauryl sulfate salt/complex in sodium lauryl sulfate (SLS) containing media.

PubMed

Bhattachar, Shobha N; Risley, Donald S; Werawatganone, Pornpen; Aburub, Aktham

2011-06-30

This work reports on the solubility of two weakly basic model compounds in media containing sodium lauryl sulfate (SLS). Results clearly show that the presence of SLS in the media (e.g. simulated gastric fluid or dissolution media) can result in an underestimation of solubility of some weak bases. We systematically study this phenomenon and provide evidence (chromatography and pXRD) for the first time that the decrease in solubility is likely due to formation of a less soluble salt/complex between the protonated form of the weak base and lauryl sulfate anion. Copyright © 2011 Elsevier B.V. All rights reserved.

Membrane Proteins Are Dramatically Less Conserved than Water-Soluble Proteins across the Tree of Life

PubMed Central

Sojo, Victor; Dessimoz, Christophe; Pomiankowski, Andrew; Lane, Nick

2016-01-01

Membrane proteins are crucial in transport, signaling, bioenergetics, catalysis, and as drug targets. Here, we show that membrane proteins have dramatically fewer detectable orthologs than water-soluble proteins, less than half in most species analyzed. This sparse distribution could reflect rapid divergence or gene loss. We find that both mechanisms operate. First, membrane proteins evolve faster than water-soluble proteins, particularly in their exterior-facing portions. Second, we demonstrate that predicted ancestral membrane proteins are preferentially lost compared with water-soluble proteins in closely related species of archaea and bacteria. These patterns are consistent across the whole tree of life, and in each of the three domains of archaea, bacteria, and eukaryotes. Our findings point to a fundamental evolutionary principle: membrane proteins evolve faster due to stronger adaptive selection in changing environments, whereas cytosolic proteins are under more stringent purifying selection in the homeostatic interior of the cell. This effect should be strongest in prokaryotes, weaker in unicellular eukaryotes (with intracellular membranes), and weakest in multicellular eukaryotes (with extracellular homeostasis). We demonstrate that this is indeed the case. Similarly, we show that extracellular water-soluble proteins exhibit an even stronger pattern of low homology than membrane proteins. These striking differences in conservation of membrane proteins versus water-soluble proteins have important implications for evolution and medicine. PMID:27501943

Levels of soluble delta-like ligand 1 in the serum and cerebrospinal fluid of tuberculous meningitis patients.

PubMed

Li, Jinghong; Li, Jinyi; Jia, Yanjie

2012-04-15

In this study, the levels of soluble delta-like ligand 1 in cerebrospinal fluid and serum of 50 patients with tuberculous meningitis, 30 patients with viral meningitis, 20 patients with purulent meningitis and 40 subjects without central nervous system disease were determined using an enzyme-linked immunosorbent assay. The mean levels of soluble delta-like ligand 1 in both cerebrospinal fluid and serum from patients with tuberculous meningitis were significantly higher compared with those from patients with viral meningitis or purulent meningitis or from subjects without central nervous system disease. Meanwhile, the level of soluble delta-like ligand 1 gradually decreased as tuberculous meningitis patients recovered. If patients deteriorated after treatment, the level of soluble delta-like ligand 1 in cerebrospinal fluid gradually increased. There was no correlation between the level of soluble delta-like ligand 1 and the protein level/cell number in cerebrospinal fluid. Our findings indicate that the levels of soluble delta-like ligand 1 in cerebrospinal fluid and serum are reliable markers for the diagnosis of tuberculous meningitis and for monitoring treatment progress. At the same time, this index is not influenced by protein levels or cell numbers in cerebrospinal fluid.

Endocytosis of GPI-linked membrane folate receptor-alpha

PubMed Central

1996-01-01

GPI-linked membrane folate receptors (MFRs) have been implicated in the receptor-mediated uptake of reduced folate cofactors and folate-based chemotherapeutic drugs. We have studied the biosynthetic transport to and internalization of MFR isoform alpha in KB-cells. MFR-alpha was synthesized as a 32-kD protein and converted in a maturely glycosylated 36-38-kD protein 1 h after synthesis. 32-kD MFR-alpha was completely soluble in Triton X-100 at 0 degree C. In contrast, only 33% of the 36- 38-kD species could be solubilized at these conditions whereas complete solubilization was obtained in Triton X-100 at 37 degrees C or in the presence of saponin at 0 degree C. Similar solubilization characteristics were found when MFR-alpha at the plasma membrane was labeled with a crosslinkable 125I-labeled photoaffinity-analog of folic acid as a ligand. Triton X-100-insoluble membrane domains containing MFR-alpha could be separated from soluble MFR-alpha on sucrose flotation gradients. Only Triton X-100 soluble MFR-alpha was internalized from the plasma membrane. The reduced-folate-carrier, an integral membrane protein capable of translocating (anti-)folates across membranes, was completely excluded from the Triton X-100- resistant membrane domains. Internalized MFR-alpha recycled slowly to the cell surface during which it remained soluble in Triton X-100 at 0 degree C. Using immunoelectron microscopy, we found MFR-alpha along the entire endocytic pathway: in clathrin-coated buds and vesicles, and in small and large endosomal vacuoles. In conclusion, our data indicate that a large fraction, if not all, of internalizing MFR-alpha bypasses caveolae. PMID:8567728

Endocytosis of GPI-linked membrane folate receptor-alpha.

PubMed

Rijnboutt, S; Jansen, G; Posthuma, G; Hynes, J B; Schornagel, J H; Strous, G J

1996-01-01

GPI-linked membrane folate receptors (MFRs) have been implicated in the receptor-mediated uptake of reduced folate cofactors and folate-based chemotherapeutic drugs. We have studied the biosynthetic transport to and internalization of MFR isoform alpha in KB-cells. MFR-alpha was synthesized as a 32-kD protein and converted in a maturely glycosylated 36-38-kD protein 1 h after synthesis. 32-kD MFR-alpha was completely soluble in Triton X-100 at 0 degree C. In contrast, only 33% of the 36-38-kD species could be solubilized at these conditions whereas complete solubilization was obtained in Triton X-100 at 37 degrees C or in the presence of saponin at 0 degree C. Similar solubilization characteristics were found when MFR-alpha at the plasma membrane was labeled with a crosslinkable 125I-labeled photoaffinity-analog of folic acid as a ligand. Triton X-100-insoluble membrane domains containing MFR-alpha could be separated from soluble MFR-alpha on sucrose flotation gradients. Only Triton X-100 soluble MFR-alpha was internalized from the plasma membrane. The reduced-folate-carrier, an integral membrane protein capable of translocating (anti-)folates across membranes, was completely excluded from the Triton X-100-resistant membrane domains. Internalized MFR-alpha recycled slowly to the cell surface during which it remained soluble in Triton X-100 at 0 degree C. Using immunoelectron microscopy, we found MFR-alpha along the entire endocytic pathway: in clathrin-coated buds and vesicles, and in small and large endosomal vacuoles. In conclusion, our data indicate that a large fraction, if not all, of internalizing MFR-alpha bypasses caveolae.

Optimization of Machining Parameters of Milling Operation by Application of Semi-synthetic oil based Nano cutting Fluids

NASA Astrophysics Data System (ADS)

Giri Prasad, M. J.; Abhishek Raaj, A. S.; Rishi Kumar, R.; Gladson, Frank; M, Gautham

2016-09-01

The present study is concerned with resolving the problems pertaining to the conventional cutting fluids. Two samples of nano cutting fluids were prepared by dispersing 0.01 vol% of MWCNTs and a mixture of 0.01 vol% of MWCNTs and 0.01 vol% of nano ZnO in the soluble oil. The thermophysical properties such as the kinematic viscosity, density, flash point and the tribological properties of the prepared nano cutting fluid samples were experimentally investigated and were compared with those of plain soluble oil. In addition to this, a milling process was carried by varying the process parameters and by application of different samples of cutting fluids and an attempt was made to determine optimal cutting condition using the Taguchi optimization technique.

The design, fabrication and characterization of fluidic membranes for micro-engines with the aim of frequency lowering

NASA Astrophysics Data System (ADS)

Chutani, R.; Formosa, F.; de Labachelerie, M.; Badel, A.; Lanzetta, F.

2016-12-01

This paper describes the design, microfabrication and linear dynamic characterization of low frequency thick membranes as a potential technological solution for resonant micro-engines, for which classical pistons cannot be used. The proposed structure is called a hybrid fluid-membrane and consists of two thin flexible membranes that encapsulate an incompressible fluid. Lower frequency structures, compared to geometrically equivalent single layer membranes, are thus obtained. Each flexible membrane is based on a composite structure which comprises a silicon planar logarithmic spiral spring embedded in a room temperature vulcanization silicone polymer. Thus, the stiffness and sealing features are dissociated for a better design control. The developed realization and assembly process is demonstrated at the wafer level. The process involves the anodic bonding of multiple stacks of silicon/glass structures, fluid filling and sealing. Various dimensions of hybrid fluid-membranes are successfully fabricated. Their dynamic characterization underlines the agreement between experimental and theoretical results. The results provide the opportunity for the design and fabrication of low frequency membranes to match the dynamics requirements of micro-engines.

Oxazine-based sensor for contaminant detection, fabrication method therefor, and uses thereof

DOEpatents

Nnanna, Agbai Agwu; Jalal, Ahmed Hasnian

2014-05-27

A sensor, a method for its fabrication, and a method for its use to detect contaminants, for example, ammonia, in stagnant and dynamic fluid media, especially liquid media. The sensor is an opto-chemical sensor that includes a polymer optical fiber, a sensing layer comprising oxazine 170 perchlorate on the polymer optical fiber, and a membrane layer on the sensing layer. The membrane layer is gas permeable and not permeable to the fluid in the fluid system, and moisture is entrapped by and between the sensing and membrane layers.

Nonlinear analysis of a shock-loaded membrane.

NASA Technical Reports Server (NTRS)

Madden, R.; Remington, P. J.

1973-01-01

Results from a computer method for analyzing the unsteady interaction of a fluid stream and a flat circular elastic membrane are presented. The loading on the membrane is assumed to be caused by the firing of a shock tube. The fluid pressures and velocities are determined from a scheme based on the numerical method of characteristics, and the membrane is analyzed using exact relations for membrane strain. The interactive solution is found to give peak stresses 40% lower than a solution which assumes a pressure invariant in space and time.

The occupational exposure limit for fluid aerosol generated in metalworking operations: limitations and recommendations.

PubMed

Park, Donguk

2012-03-01

The aim of this review was to assess current knowledge related to the occupational exposure limit (OEL) for fluid aerosols including either mineral or chemical oil that are generated in metalworking operations, and to discuss whether their OEL can be appropriately used to prevent several health risks that may vary among metalworking fluid (MWF) types. The OEL (time-weighted average; 5 mg/m(3), short-term exposure limit ; 15 mg/m(3)) has been applied to MWF aerosols without consideration of different fluid aerosol-size fractions. The OEL, is also based on the assumption that there are no significant differences in risk among fluid types, which may be contentious. Particularly, the health risks from exposure to water-soluble fluids may not have been sufficiently considered. Although adoption of The National Institute for Occupational Safety and Health's recommended exposure limit for MWF aerosol (0.5 mg/m(3)) would be an effective step towards minimizing and evaluating the upper respiratory irritation that may be caused by neat or diluted MWF, this would fail to address the hazards (e.g., asthma and hypersensitivity pneumonitis) caused by microbial contaminants generated only by the use of water-soluble fluids. The absence of an OEL for the water-soluble fluids used in approximately 80-90 % of all applicants may result in limitations of the protection from health risks caused by exposure to those fluids.

Membrane Proteins Are Dramatically Less Conserved than Water-Soluble Proteins across the Tree of Life.

PubMed

Sojo, Victor; Dessimoz, Christophe; Pomiankowski, Andrew; Lane, Nick

2016-11-01

Membrane proteins are crucial in transport, signaling, bioenergetics, catalysis, and as drug targets. Here, we show that membrane proteins have dramatically fewer detectable orthologs than water-soluble proteins, less than half in most species analyzed. This sparse distribution could reflect rapid divergence or gene loss. We find that both mechanisms operate. First, membrane proteins evolve faster than water-soluble proteins, particularly in their exterior-facing portions. Second, we demonstrate that predicted ancestral membrane proteins are preferentially lost compared with water-soluble proteins in closely related species of archaea and bacteria. These patterns are consistent across the whole tree of life, and in each of the three domains of archaea, bacteria, and eukaryotes. Our findings point to a fundamental evolutionary principle: membrane proteins evolve faster due to stronger adaptive selection in changing environments, whereas cytosolic proteins are under more stringent purifying selection in the homeostatic interior of the cell. This effect should be strongest in prokaryotes, weaker in unicellular eukaryotes (with intracellular membranes), and weakest in multicellular eukaryotes (with extracellular homeostasis). We demonstrate that this is indeed the case. Similarly, we show that extracellular water-soluble proteins exhibit an even stronger pattern of low homology than membrane proteins. These striking differences in conservation of membrane proteins versus water-soluble proteins have important implications for evolution and medicine. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Rutile solubility in NaF–NaCl–KCl-bearing aqueous fluids at 0.5–2.79GPa and 250–650°C

DOE PAGES

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; ...

2016-01-14

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Rutile solubility in NaF-NaCl-KCl-bearing aqueous fluids at 0.5-2.79 GPa and 250-650 °C

NASA Astrophysics Data System (ADS)

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue; Chow, Paul; Xiao, Yuming; Hanchar, John M.; Tschauner, Oliver; Shen, Guoyin

2016-03-01

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nb and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 °C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at ∼300 °C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 °C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log DZr ∼10-25 m2/s at 650 °C and ∼10-30 m2/s at 250 °C) with diffusion length-scales of <0.2 μm in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility.

Hierarchy of stroma-derived factors in supporting growth of stroma-dependent hemopoietic cells: membrane-bound SCF is sufficient to confer stroma competence to epithelial cells.

PubMed

Friel, Jutta; Itoh, Katsuhiko; Bergholz, Ulla; Jücker, Manfred; Stocking, Carol; Harrison, Paul; Ostertag, Wolfram

2002-03-01

Hemopoiesis takes place in a microenvironment where hemopoietic cells are closely associated with stroma by various interactions. Stroma coregulates the proliferation and differentiation of hemopoietic cells. Stroma-hemopoietic-cell contact can be supported by locally produced membrane associated growth factors. The stroma derived growth factor, stem cell factor (SCF) is important in hemopoiesis. We examined the different biological interactions of membrane bound and soluble SCF with human hemopoietic cells expressing the SCF receptor, c-kit. To analyze the function of the SCF isoforms in inducing the proliferation of hemopoietic TF1 or Cord blood (CB) CD34+ cells we used stroma cell lines that differ in their presentation of no SCF, membrane SCF, or soluble SCF. We established a new coculture system using an epithelial cell line that excludes potential interfering effects with other known stroma encoded hemopoietic growth factors. We show that soluble SCF, in absence of membrane-bound SCF, inhibits long term clonal growth of primary or established CD34+ hemopoietic cells, whereas membrane-inserted SCF "dominantly" induces long term proliferation of these cells. We demonstrate a hierarchy of these SCF isoforms in the interaction of stroma with hemopoietic TF1 cells. Membrane-bound SCF is "dominant" over soluble SCF, whereas soluble SCF acts epistatically in interacting with hemopoietic cells compared with other stroma derived factors present in SCF deficient stroma. A hierarchy of stroma cell lines can be arranged according to their presentation of membrane SCF or soluble SCF. In our model system, membrane-bound SCF expression is sufficient to confer stroma properties to an epithelial cell line but soluble SCF does not.

Modeling of Fluid-Membrane Interaction in Cellular Microinjection Process

NASA Astrophysics Data System (ADS)

Karzar-Jeddi, Mehdi; Diaz, Jhon; Olgac, Nejat; Fan, Tai-Hsi

2009-11-01

Cellular microinjection is a well-accepted method to deliver matters such as sperm, nucleus, or macromolecules into biological cells. To improve the success rate of in vitro fertilization and to establish the ideal operating conditions for a novel computer controlled rotationally oscillating intracytoplasmic sperm injection (ICSI) technology, we investigate the fluid-membrane interactions in the ICSI procedure. The procedure consists of anchoring the oocyte (a developing egg) using a holding pipette, penetrating oocyte's zona pellucida (the outer membrane) and the oolemma (the plasma or inner membrane) using an injection micropipette, and finally to deliver sperm into the oocyte for fertilization. To predict the large deformation of the oocyte membranes up to the piercing of the oolemma and the motion of fluids across both membranes, the dynamic fluid-pipette-membrane interactions are formulated by the coupled Stokes' equations and the continuum membrane model based on Helfrich's energy theory. A boundary integral model is developed to simulate the transient membrane deformation and the local membrane stress induced by the longitudinal motion of the injection pipette. The model captures the essential features of the membranes shown on optical images of ICSI experiments, and is capable of suggesting the optimal deformation level of the oolemma to start the rotational oscillations for piercing into the oolemma.

Cochlear potential difference between endolymph fluid and the hair cell's interior: a retold interpretation based on the Goldman equation.

PubMed

Kurbel, Sven; Borzan, Vladimir; Golem, Hilda; Dinjar, Kristijan

2017-02-01

Reported cochlear potential values of near 150 mV are often attributed to endolymph itself, although membrane potentials result from ion fluxes across the adjacent semipermeable membranes due to concentration gradients. Since any two fluids separated by a semipermeable membrane develop potential due to differences in solute concentrations, a proposed interpretation here is that positive potential emanates from the Reissner membrane due to small influx of sodium from perilymph to endolymph. Basolateral hair cell membranes leak potassium into the interstitial fluid and this negative potential inside hair cells further augments the electric gradient of cochlear potential. Taken together as a sum, these two potentials are near the reported values of cochlear potential. This is based on reported data for cochlear fluids used for the calculation of Nernst and Goldman potentials. The reported positive potential of Reissner membrane can be explained almost entirely by the traffic of Na+ that enters endolymph through this membrane. At the apical membrane of hair cells, acoustic stimulation modulates stereocillia permeability to potassium. Potassium concentration gradients on the apical membrane are low (the calculated Nernst value is <+3 mV), suggesting that the potassium current is not caused by the local potassium concentration gradient, but an electric field between the positive sodium generated potential on the Reissner membrane and negative inside hair cells. Potassium is forced by this overall electric field to enter hair cells when stereocilia are permeable due to mechanical bending. Copyright© by the Medical Assotiation of Zenica-Doboj Canton.

The solubility-permeability interplay and its implications in formulation design and development for poorly soluble drugs.

PubMed

Dahan, Arik; Miller, Jonathan M

2012-06-01

While each of the two key parameters of oral drug absorption, the solubility and the permeability, has been comprehensively studied separately, the relationship and interplay between the two have been largely ignored. For instance, when formulating a low-solubility drug using various solubilization techniques: what are we doing to the apparent permeability when we increase the solubility? Permeability is equal to the drug's diffusion coefficient through the membrane times the membrane/aqueous partition coefficient divided by the membrane thickness. The direct correlation between the intestinal permeability and the membrane/aqueous partitioning, which in turn is dependent on the drug's apparent solubility in the GI milieu, suggests that the solubility and the permeability are closely associated, exhibiting a certain interplay between them, and the current view of treating the one irrespectively of the other may not be sufficient. In this paper, we describe the research that has been done thus far, and present new data, to shed light on this solubility-permeability interplay. It has been shown that decreased apparent permeability accompanies the solubility increase when using different solubilization methods. Overall, the weight of the evidence indicates that the solubility-permeability interplay cannot be ignored when using solubility-enabling formulations; looking solely at the solubility enhancement that the formulation enables may be misleading with regards to predicting the resulting absorption, and hence, the solubility-permeability interplay must be taken into account to strike the optimal solubility-permeability balance, in order to maximize the overall absorption.

Transport of Zn(OH4)(2-) Ions Across a Polyolefin Microporous Membrane

DTIC Science & Technology

1992-12-22

studied using polarography and conductometry . Soluble Nafion as an ion exchange modifying agent was applied to the membrane by several techniques. The...polypropylene membranes was studied using polarography and conductometry . Soluble Nafion as an ion exchange modifying agent was applied to the membrane by

Natural Poly- and Oligosaccharides as Novel Delivery Systems for Plant Protection Compounds.

PubMed

Selyutina, O Yu; Apanasenko, I E; Khalikov, S S; Polyakov, N E

2017-08-09

To increase the bioavailability of plant protection products, we have applied a new approach based on noncovalent association with natural water-soluble polysaccharides and oligosaccharides as delivery systems (DSs). The mechanochemical technique has been applied to prepare the solid-state nanodispersed compositions of antidote 1,8-naphthalic anhydride (NA) with arabinogalactan, sodium salt of carboxymethylcellulose, and glycyrrhizin as DSs. The effect of DSs on the solubility and the penetration of NA into the seeds of barley and wheat has been investigated by various physicochemical techniques. All DSs considerably enhance the solubility of NA and improve its penetration into the grain. The influence of polysaccharides and oligosaccharides on artificial lipid membranes was studied by the NMR relaxation method. It was concluded that the effect of polysaccharides and oligosaccharides on the penetration efficacy of plant protection products might be associated with the detected solubility enhancement and the affinity of DSs to the surface of cell membranes.

A reaction limited in vivo dissolution model for the study of drug absorption: Towards a new paradigm for the biopharmaceutic classification of drugs.

PubMed

Macheras, Panos; Iliadis, Athanassios; Melagraki, Georgia

2018-05-30

The aim of this work is to develop a gastrointestinal (GI) drug absorption model based on a reaction limited model of dissolution and consider its impact on the biopharmaceutic classification of drugs. Estimates for the fraction of dose absorbed as a function of dose, solubility, reaction/dissolution rate constant and the stoichiometry of drug-GI fluids reaction/dissolution were derived by numerical solution of the model equations. The undissolved drug dose and the reaction/dissolution rate constant drive the dissolution rate and determine the extent of absorption when high-constant drug permeability throughout the gastrointestinal tract is assumed. Dose is an important element of drug-GI fluids reaction/dissolution while solubility exclusively acts as an upper limit for drug concentrations in the lumen. The 3D plots of fraction of dose absorbed as a function of dose and reaction/dissolution rate constant for highly soluble and low soluble drugs for different "stoichiometries" (0.7, 1.0, 2.0) of the drug-reaction/dissolution with the GI fluids revealed that high extent of absorption was found assuming high drug- reaction/dissolution rate constant and high drug solubility. The model equations were used to simulate in vivo supersaturation and precipitation phenomena. The model developed provides the theoretical basis for the interpretation of the extent of drug's absorption on the basis of the parameters associated with the drug-GI fluids reaction/dissolution. A new paradigm emerges for the biopharmaceutic classification of drugs, namely, a model independent biopharmaceutic classification scheme of four drug categories based on either the fulfillment or not of the current dissolution criteria and the high or low % drug metabolism. Copyright © 2018. Published by Elsevier B.V.

Characterizing metal(loid) solubility in airborne PM10, PM2.5 and PM1 in Frankfurt, Germany using simulated lung fluids

NASA Astrophysics Data System (ADS)

Wiseman, Clare L. S.; Zereini, Fathi

2014-06-01

The purpose of this study is to assess the solubility of traffic-related metal(loid)s associated with airborne PM of human health concern, employing a physiologically-based extraction test with simulated lung fluids (artificial lysosomal fluid (ALF) and Gamble's solution). Airborne PM (PM10, PM2.5 and PM1) samples were collected in Frankfurt am Main, Germany, using a high volume sampler. Following extraction of the soluble metal(loid) fractions, sample filters were digested with a high pressure asher. Metal(loid) concentrations (As, Ce, Co, Cr, Cu, Mn, Ni, Pb, Sb, Ti and V) were determined in extracts and digests per ICP-Q-MS. All metal(loid)s occurred at detectable concentrations in the three airborne PM fractions. Copper was the most abundant element in mass terms, with mean concentrations of 105 and 53 ng/m3 in PM10 and PM2.5, respectively. Many of the metal(loid)s were observed to be soluble in simulated lung fluids, with Cu, As, V and Sb demonstrating the highest overall mobility in airborne PM. For instance, all four elements associated with PM10 had a solubility of >80% in ALF (24 h). Clearly, solubility is strongly pH dependent, as reflected by the higher relative mobility of samples extracted with the acidic ALF. Given their demonstrated solubility, this study provides indirect evidence that a number of toxic metal(loid)s are likely to possess an enhanced pulmonary toxic potential upon their inhalation. The co-presence of many toxic elements of concern in airborne PM suggests an assessment of health risk must consider the possible interactive impacts of multi-element exposures.

Relationship between theoretical molecular weight and blister fluid/serum ratio of cytokines and five other molecules evaluated in patients with bullous pemphigoid.

PubMed

D'Auria, L; Pimpinelli, F; Ferraro, C; D'Ambrogio, G; Giacalone, B; Bellocci, M; Ameglio, F

1998-01-01

Bullous pemphigoid (BP) blisters contain several molecules, some of which spread into the blisters from the interstitial fluid, while others are produced locally and migrate into the circulation. The calculation of the ratios between blister/serum concentrations may help to distinguish between these two types of molecules. The rules regulating the diffusion of the molecules have been described only in suction blisters, where the theoretical molecular weight (MW) represents one of the principal influencing factors. The aim of the present study was to analyse the relationship between theoretical MWs and the ratios of concentrations of several molecules evaluated both in sera and in blister fluids. Eight cytokines (interleukin-2, interleukin-3, interleukin-4, interleukin-5, interleukin-10, tumor necrosis factor-alpha, oncostatin-M and vascular endothelial growth factor), two acute phase reactants (alpha-1 acid glycoprotein, haptoglobin), albumin, one soluble membrane molecule with adhesion functions (sICAM-1) and the eosinophil cathionic protein (ECP) were measured in samples from 15 patients affected with BP by means of commercially available tests. The data suggest that the MW may influence the rate of diffusion throughout the blister, both in input and output directions, despite the discontinuity observed at the basement membrane level on the BP blister floor.

[Membrane technologies in medicine and ecology].

PubMed

Makarov, D A; Malyshev, V V; Kononova, S V

2010-01-01

The paper considers the state-of-the-art of membrane technologies, as applied to the needs of medicine and ecology, the major benefits of membranes for microfiltration and ultrafiltration, and perspectives for the application of new membranes based on new materials. A number of membranes based on aromatic polyamide imides (PAs) have been investigated using rotavirus models. Due to the good solubility of PAs in amide solvents, their based asymmetric membranes can be formed in one step, by applying a water setting bath. The one-stage procedure developed at the Institute of High Molecular Compounds, Russian Academy of Sciences, for the synthesis of aromatic PAs allows one to prepare polymers with required viscosity and strength characteristics. This gives rise to a membrane as porous films of digitiform morphology and asymmetric porous structure.

Biochemical characterization of detergent-resistant membranes: a systematic approach

PubMed Central

Babiychuk, Eduard B.; Draeger, Annette

2006-01-01

Lateral segregation of cholesterol- and sphingomyelin-rich rafts and glycerophospholipid-containing non-raft microdomains has been proposed to play a role in a variety of biological processes. The most compelling evidence for membrane segregation is based on the observation that extraction with non-ionic detergents leads to solubilization of a subset of membrane components only. However, one decade later, a large body of inconsistent detergent-extraction data is threatening the very concept of membrane segregation. We have assessed the validity of the existing paradigms and we show the following. (i) The localization of a membrane component within a particular fraction of a sucrose gradient cannot be taken as a yardstick for its solubility: a variable localization of the DRMs (detergent-resistant membranes) in sucrose gradients is the result of complex associations between the membrane skeleton and the lipid bilayer. (ii) DRMs of variable composition can be generated by using a single detergent, the increasing concentration of which gradually extracts one protein/lipid after another. Therefore any extraction pattern obtained by a single concentration experiment is bound to be ‘investigator-specific’. It follows that comparison of DRMs obtained by different detergents in a single concentration experiment is prone to misinterpretations. (iii) Depletion of cholesterol has a graded effect on membrane solubility. (iv) Differences in detergent solubility of the members of the annexin protein family arise from their association with chemically different membrane compartments; however, these cannot be attributed to the ‘brick-like’ raft-building blocks of fixed size and chemical composition. Our findings demonstrate a need for critical re-evaluation of the accumulated detergent-extraction data. PMID:16608442

Biochemical characterization of detergent-resistant membranes: a systematic approach.

PubMed

Babiychuk, Eduard B; Draeger, Annette

2006-08-01

Lateral segregation of cholesterol- and sphingomyelin-rich rafts and glycerophospholipid-containing non-raft microdomains has been proposed to play a role in a variety of biological processes. The most compelling evidence for membrane segregation is based on the observation that extraction with non-ionic detergents leads to solubilization of a subset of membrane components only. However, one decade later, a large body of inconsistent detergent-extraction data is threatening the very concept of membrane segregation. We have assessed the validity of the existing paradigms and we show the following. (i) The localization of a membrane component within a particular fraction of a sucrose gradient cannot be taken as a yardstick for its solubility: a variable localization of the DRMs (detergent-resistant membranes) in sucrose gradients is the result of complex associations between the membrane skeleton and the lipid bilayer. (ii) DRMs of variable composition can be generated by using a single detergent, the increasing concentration of which gradually extracts one protein/lipid after another. Therefore any extraction pattern obtained by a single concentration experiment is bound to be 'investigator-specific'. It follows that comparison of DRMs obtained by different detergents in a single concentration experiment is prone to misinterpretations. (iii) Depletion of cholesterol has a graded effect on membrane solubility. (iv) Differences in detergent solubility of the members of the annexin protein family arise from their association with chemically different membrane compartments; however, these cannot be attributed to the 'brick-like' raft-building blocks of fixed size and chemical composition. Our findings demonstrate a need for critical re-evaluation of the accumulated detergent-extraction data.

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

Tanis, Elizabeth A.; Simon, Adam; Zhang, Youxue

The complex nature of trace element mobility in subduction zone environments is thought to be primarily controlled by fluid-rock interactions, episodic behavior of fluids released, mineral assemblages, and element partitioning during phase transformations and mineral breakdown throughout the transition from hydrated basalt to blueschist to eclogite. Quantitative data that constrain the partitioning of trace elements between fluid(s) and mineral(s) are required in order to model trace element mobility during prograde and retrograde metamorphic fluid evolution in subduction environments. The stability of rutile has been proposed to control the mobility of HFSE during subduction, accounting for the observed depletion of Nbmore » and Ta in arc magmas. Recent experimental studies demonstrate that the solubility of rutile in aqueous fluids at temperatures >700 degrees C and pressures <2 GPa increases by several orders of magnitude relative to pure H2O as the concentrations of ligands (e.g., F and Cl) in the fluid increase. Considering that prograde devolatilization in arcs begins at similar to 300 degrees C, there is a need for quantitative constraints on rutile solubility and the partitioning of HFSE between rutile and aqueous fluid over a wider range of temperature and pressure than is currently available. In this study, new experimental data are presented that quantify the solubility of rutile in aqueous fluids from 0.5 to 2.79 GPa and 250 to 650 degrees C. Rutile solubility was determined by using synchrotron X-ray fluorescence to measure the concentration of Zr in an aqueous fluid saturated with a Zr-bearing rutile crystal within a hydrothermal diamond anvil cell. At the PT conditions of the experiments, published diffusion data indicate that Zr is effectively immobile (log D-Zr similar to 10(-25) m(2)/s at 650 degrees C and similar to 10(-30) m(2)/s at 250 degrees C) with diffusion length-scales of <0.2 mu m in rutile for our run durations (<10 h). Hence, the Zr/Ti ratio of the starting rutile, which was quantified, does not change during the experiment, and the measured concentration of Zr in the fluid was used to calculate the concentration of Ti (i.e., the solubility of rutile) in the fluid. The salts NaF, NaCl, and KCl were systematically added to the aqueous fluid, and the relative effects of fluid composition, pressure, and temperature on rutile solubility were quantified. The results indicate that fluid composition exerts the greatest control on rutile solubility in aqueous fluid, consistent with previous studies, and that increasing temperature has a positive, albeit less pronounced, effect. The solubility of Zr-rutile in aqueous fluid increases with the addition of halides in the following order: 2 wt% NaF < 30 wt% KCl < 30 wt% NaCl < 3 wt% NaF < (10 wt% NaCl + 2 wt% NaF) < 4 wt% NaF. The solubility of rutile in the fluid increases with the 2nd to 3rd power of the Cl- concentration, and the 3rd to 4th power of the F- concentration. These new data are consistent with observations from field studies of exhumed terranes that indicate that rutile is soluble in complex aqueous fluids, and that fluid composition is the primary control on rutile solubility and HFSE mobility« less

Solubility and stability of dalcetrapib in vehicles and biological media.

PubMed

Gross, Günter; Tardio, Joseph; Kuhlmann, Olaf

2012-11-01

Dalcetrapib solubility was determined in aqueous and in non-aqueous vehicles and in biorelevant media. In a pure aqueous environment the solubility was low but could be increased by addition of surfactants or complexing agents. This was also reflected in the solubility seen in simulated gastrointestinal (GI) fluids, with almost no solubility in simulated gastric fluid, but reasonable solubilisation in simulated intestinal fluids containing lecithin and bile salt. Additionally, the stability of dalcetrapib was determined in simulated GI fluids with and without pancreatic lipase. In solutions without lipase, dalcetrapib was slowly hydrolysed, but in the presence of lipase the hydrolysis rate was significantly faster depending on pH and enzyme activity. In biological fluids, dissolved dalcetrapib appeared to behave similarly being rapidly hydrolysed in human intestinal fluids with a half-life below 20s with no degradation observed in human gastric fluids at low pH. The results provide supportive evidence that absorption is higher under fed conditions and indicate lipase inhibitors might interfere with oral absorption of dalcetrapib. Copyright © 2012 Elsevier B.V. All rights reserved.

Vesicular perylene dye nanocapsules as supramolecular fluorescent pH sensor systems.

PubMed

Zhang, Xin; Rehm, Stefanie; Safont-Sempere, Marina M; Würthner, Frank

2009-11-01

Water-soluble, self-assembled nanocapsules composed of a functional bilayer membrane and enclosed guest molecules can provide smart (that is, condition responsive) sensors for a variety of purposes. Owing to their outstanding optical and redox properties, perylene bisimide chromophores are interesting building blocks for a functional bilayer membrane in a water environment. Here, we report water-soluble perylene bisimide vesicles loaded with bispyrene-based energy donors in their aqueous interior. These loaded vesicles are stabilized by in situ photopolymerization to give nanocapsules that are stable over the entire aqueous pH range. On the basis of pH-tunable spectral overlap of donors and acceptors, the donor-loaded polymerized vesicles display pH-dependent fluorescence resonance energy transfer from the encapsulated donors to the bilayer dye membrane, providing ultrasensitive pH information on their aqueous environment with fluorescence colour changes covering the whole visible light range. At pH 9.0, quite exceptional white fluorescence could be observed for such water-soluble donor-loaded perylene vesicles.

Production of okara and soy protein concentrates using membrane technology.

PubMed

Vishwanathan, K H; Govindaraju, K; Singh, Vasudeva; Subramanian, R

2011-01-01

Microfiltration (MF) membranes with pore sizes of 200 and 450 nm and ultrafiltration (UF) membranes with molecular weight cut off of 50, 100, and 500 kDa were assessed for their ability to eliminate nonprotein substances from okara protein extract in a laboratory cross-flow membrane system. Both MF and UF improved the protein content of okara extract to a similar extent from approximately 68% to approximately 81% owing to the presence of protein in the feed leading to the formation of dynamic layer controlling the performance rather than the actual pore size of membranes. Although normalized flux in MF-450 (117 LMH/MPa) was close to UF-500 (118 LMH/MPa), the latter was selected based on higher average flux (47 LMH) offering the advantage of reduced processing time. Membrane processing of soy extract improved the protein content from 62% to 85% much closer to the target value. However, the final protein content in okara (approximately 80%) did not reach the target value (90%) owing to the greater presence of soluble fibers that were retained by the membrane. Solubility curve of membrane okara protein concentrate (MOPC) showed lower solubility than soy protein concentrate and a commercial isolate in the entire pH range. However, water absorption and fat-binding capacities of MOPC were either superior or comparable while emulsifying properties were in accordance with its solubility. The results of this study showed that okara protein concentrate (80%) could be produced using membrane technology without loss of any true proteins, thus offering value addition to okara, hitherto underutilized. Practical Application: Okara, a byproduct obtained during processing soybean for soymilk, is either underutilized or unutilized in spite of the fact that its protein quality is as good as that of soy milk and tofu. Membrane-processed protein products have been shown to possess superior functional properties compared to conventionally produced protein products. However, the potential of membrane technology has not been exploited for the recovery of okara protein. Our study showed that protein content of okara extract could be improved from approximately 68% to approximately 81% without losing any true proteins in the process.

Confined semiflexible polymers suppress fluctuations of soft membrane tubes.

PubMed

Mirzaeifard, Sina; Abel, Steven M

2016-02-14

We use Monte Carlo computer simulations to investigate tubular membrane structures with and without semiflexible polymers confined inside. At small values of membrane bending rigidity, empty fluid and non-fluid membrane tubes exhibit markedly different behavior, with fluid membranes adopting irregular, highly fluctuating shapes and non-fluid membranes maintaining extended tube-like structures. Fluid membranes, unlike non-fluid membranes, exhibit a local maximum in specific heat as their bending rigidity increases. The peak is coincident with a transition to extended tube-like structures. We further find that confining a semiflexible polymer within a fluid membrane tube reduces the specific heat of the membrane, which is a consequence of suppressed membrane shape fluctuations. Polymers with a sufficiently large persistence length can significantly deform the membrane tube, with long polymers leading to localized bulges in the membrane that accommodate regions in which the polymer forms loops. Analytical calculations of the energies of idealized polymer-membrane configurations provide additional insight into the formation of polymer-induced membrane deformations.

Identification of structural and secretory lectin-binding glycoproteins of normal and cancerous human prostate.

PubMed

Lad, P M; Cooper, J F; Learn, D B; Olson, C V

1984-12-07

We have utilized the technique of lectin-loading of SDS gels with iodinated concanavalin A and wheat germ agglutinin to identify glycoproteins in prostatic and seminal fluids as well as in prostate tissue fractions. The following subunits which bound both lectins were detected: (a) 50, 43 and 38 kDa subunits common to prostatic and seminal fluids, and an additional 55 kDa subunit which predominates only in prostatic fluid; (b) 78, 55, 50 and 43 kDa subunits in prostatic tissue cytosol and (c) 195, 170, 135, 116 and 95 kDa subunits present in the particulate fractions of prostatic tissue. Immunoblotting using specific rabbit antibodies revealed the 50 kDa band to be prostatic acid phosphatase and the 38 kDa band to be prostate-specific antigen. Interestingly, antibodies directed toward prostatic acid phosphatase were found to cross-react with the 43 kDa band. Fractionation on sucrose gradients showed that several of these particulate glycoproteins were associated with a vesicle fraction enriched in adenylate cyclase activity, implying that they are plasma membrane glycoproteins. Comparison of soluble and particulate fractions of normal and cancerous tissue homogenates was made by densitometric scanning of autoradiograms of lectin-loaded gels. Similar relative intensities of lectin-binding were obtained for corresponding proteins in normal and cancerous tissue fractions. Also, immunoblotting showed no differences in prostatic acid phosphatase or prostate-specific antigen between normal and cancerous soluble homogenate fractions. Our results suggest that major lectin-binding proteins are conserved in the transition from normal to cancerous tissue. These results may be useful in developing a multiple-marker profile of metastatic prostate cancer and for the design of imaging agents, such as monoclonal antibodies, to prominent soluble and particulate prostate glycoproteins.

Evaluation of the membrane permeability (PAMPA and skin) of benzimidazoles with potential cannabinoid activity and their relation with the Biopharmaceutics Classification System (BCS).

PubMed

Alvarez-Figueroa, M Javiera; Pessoa-Mahana, C David; Palavecino-González, M Elisa; Mella-Raipán, Jaime; Espinosa-Bustos, Cristián; Lagos-Muñoz, Manuel E

2011-06-01

The permeability of five benzimidazole derivates with potential cannabinoid activity was determined in two models of membranes, parallel artificial membrane permeability assay (PAMPA) and skin, in order to study the relationship of the physicochemical properties of the molecules and characteristics of the membranes with the permeability defined by the Biopharmaceutics Classification System. It was established that the PAMPA intestinal absorption method is a good predictor for classifying these molecules as very permeable, independent of their thermodynamic solubility, if and only if these have a Log P(oct) value <3.0. In contrast, transdermal permeability is conditioned on the solubility of the molecule so that it can only serve as a model for classifying the permeability of molecules that possess high solubility (class I: high solubility, high permeability; class III: high solubility, low permeability).

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

Brommage, Jr., Robert J.

The skeleton is recognized as a crucial organ in the minute-to-minute regulation of the blood levels of calcium and phosphate. The fluxes of calcium and phosphate to and from bone greatly exceed the entry and exit of these ions occurring in the intestine and kidneys. Parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D 3 (1,25-(OH) 2D 3 are known to influence the transfer of calcium and phosphate from bone to blood. Three mechanisms have been proposed to explain the hormonal control of the calcium and phosphate effluxes from bone. The concept of a bone membrane maintaining a distinct bone extracellular fluid compositionmore » has led to the pump and pH gradient theories. An alternate solubilizer theory proposes that bone cells secrete a substance which increases the solubility of the bone mineral. The bone membrane concept was originally proposed to explain the presence of the apparent anomalously high concentrations of potassium in the bone extracellular fluid. However, the available evidence does not allow an unambiguous decision concerning the presence of a bone membrane. Calvarial lactate production was unaltered by 1,25-(OH) 2D 3 treatment and consequently 1,25-(OH) 2D 3 does not appear to promote the mobilization of bone mineral through a lactate-mediated pH gradient mechanism. 1,25-(OH) 2D 3 did increase the solubility of non-vital bone, clearly demonstrating that the solubilizer mechanism is at least partially responsible for the mobilization of bone mineral and the regulation of blood levels of calcium and phosphate. Vitamin D-deficient female rats fed a 0.2% calcium, 0.4% phosphorous diet and supplemented with daily injections of 0.75 pmole of 1,25-(OH) 2D 3 were shown to be capable of bearing young. When the injections of 1,25-(OH) 2D 3 were terminated at delivery, the dams and pups showed signs of vitamin D deficiency approximately one week later.« less

Amniotic Fluid Soluble HLA-G in Term and Preterm Parturition, and Intra-amniotic Infection/Inflammation

PubMed Central

Kusanovic, Juan Pedro; Romero, Roberto; Jodicke, Cristiano; Mazaki-Tovi, Shali; Vaisbuch, Edi; Erez, Offer; Mittal, Pooja; Gotsch, Francesca; Chaiworapongsa, Tinnakorn; Edwin, Sam S.; Pacora, Percy; Hassan, Sonia S.

2012-01-01

Objective Circulating soluble HLA-G (sHLA-G) has been associated with pregnancy complications, and determination of sHLA-G concentrations in amniotic fluid (AF) has been reported in normal pregnancies. Our aim was to determine if the AF concentrations of sHLA-G change with advancing gestation, spontaneous labor at term, and in patients with spontaneous preterm labor (PTL) with intact membranes, as well as in those with preterm prelabor rupture of membranes (PROM), in the presence or absence of intraamniotic infection/inflammation (IAI). Study design This cross-sectional study included the following groups: 1) midtrimester (n=55); 2) normal pregnancy at term with (n=50) and without (n=50) labor; 3) spontaneous PTL with intact membranes divided into: a) PTL who delivered at term (n=153); b) PTL who delivered preterm without IAI (n=108); and c) PTL with IAI (n=84); and 4) preterm PROM with (n=46) and without (n=44) IAI. sHLA-G concentrations were determined by ELISA. Non-parametric statistics were used for analysis. Results 1) Among patients with PTL, the median AF sHLA-G concentration was higher in patients with IAI than in those without IAI or women that delivered at term (p<0.001 for both comparisons); 2) Similarly, patients with preterm PROM and IAI had higher median AF sHLA-G concentrations than those without IAI (p=0.004); 3) Among patients with PTL and delivery, those with histologic chorioamnionitis and/or funisitis had a higher median AF sHLA-G concentration than those without histologic inflammation (p<0.001); and 4) The median AF sHLA-G concentration did not change with advancing gestational age. Conclusions AF sHLA-G concentrations are elevated in preterm parturition associated to IAI as well as in histologic chorioamnionitis. We propose that sHLA-G may participate in the regulation of the host immune response against intra-amniotic infection. PMID:19916713

Zircon solubility and of Zr species in subduction zone fluids

NASA Astrophysics Data System (ADS)

Wilke, M.; Schmidt, C.; Rickers, K.; Pascarelli, S.; Manning, C. E.; Stechern, A.

2009-12-01

The geochemical signature of igneous rocks at convergent plate margins is thought to result from complex melt formation processes involving aqueous solutions derived from dehydration of the subducted slab. In these processes, the depletion of high-field-strength elements (HFSE) may be controlled by the presence of accessory phases such as zircon and rutile, which can strongly fractionate these elements; however, the stability and solubility of these phases depends strongly on the fluid composition, including concentration and stoichiometry of Na-Al silicate components. Here we present new data on the influence of the fluid composition on zircon solubility as well as data on the Zr complexation in these fluids at P&T. Experiments were conducted using a modified hydrothermal diamond-anvil cell (HDAC). Zr contents at P&T were determined using SR-µXRF spectra. Zr K-edge X-ray Absorption Fine Structure (XAFS) spectra were acquired to investigate the Zr complexation in-situ at P&T. A grain of synthetic crystalline zircon was equilibrated with an aqueous fluid containing Na2Si2O5 or Na2Si2O5 + Al2O3 components. XAFS and SR-µXRF spectra were taken at the dispersive beamline ID24 of the ESRF, Grenoble, France. Some additional SR-µXRF spectra were taken at HASYLAB, Hamburg, beamline L. The observed Zr concentrations in fluids containing 7-33 wt% Na2Si2O5 and variable Al contents were between 75 and 720 ppm at 500 to 750°C and ~300 MPa to ~700 MPa. These values match expected solubilities calculated from linear interpolation of the maximum solubility in pure H2O (from the detection limit) and the solubility in the most alkaline high-silica melts reported by Ellison and Hess (1986, CMP, 94, 343). The high Zr solubility in sodium silicate-bearing solutions signifies that aqueous fluids with alkali silicates offer an efficient mechanism for HFSE transport. This can be explained by complexation of HFSE with Si, Na, and perhaps also Al, via formation of polymerized solutes. The XAFS results show clear differences between spectra of Zr in an HCl solution and in H2O-Na2Si2O5 (±Al2O3) aqueous fluid, implying considerable differences in Zr complexation. The latter spectra display similarities to spectra of Zr in Na2Si2O5 glass. This may indicate a similar structural environment for the two examined states, and thus point to Zr in (alumino)-silicate-based polymeric units in the aqueous solutions.

Broad spectrum antibacterial and antifungal polymeric paint materials: synthesis, structure-activity relationship, and membrane-active mode of action.

PubMed

Hoque, Jiaul; Akkapeddi, Padma; Yadav, Vikas; Manjunath, Goutham B; Uppu, Divakara S S M; Konai, Mohini M; Yarlagadda, Venkateswarlu; Sanyal, Kaustuv; Haldar, Jayanta

2015-01-28

Microbial attachment and subsequent colonization onto surfaces lead to the spread of deadly community-acquired and hospital-acquired (nosocomial) infections. Noncovalent immobilization of water insoluble and organo-soluble cationic polymers onto a surface is a facile approach to prevent microbial contamination. In the present study, we described the synthesis of water insoluble and organo-soluble polymeric materials and demonstrated their structure-activity relationship against various human pathogenic bacteria including drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and beta lactam-resistant Klebsiella pneumoniae as well as pathogenic fungi such as Candida spp. and Cryptococcus spp. The polymer coated surfaces completely inactivated both bacteria and fungi upon contact (5 log reduction with respect to control). Linear polymers were more active and found to have a higher killing rate than the branched polymers. The polymer coated surfaces also exhibited significant activity in various complex mammalian fluids such as serum, plasma, and blood and showed negligible hemolysis at an amount much higher than minimum inhibitory amounts (MIAs). These polymers were found to have excellent compatibility with other medically relevant polymers (polylactic acid, PLA) and commercial paint. The cationic hydrophobic polymer coatings disrupted the lipid membrane of both bacteria and fungi and thus showed a membrane-active mode of action. Further, bacteria did not develop resistance against these membrane-active polymers in sharp contrast to conventional antibiotics and lipopeptides, thus the polymers hold great promise to be used as coating materials for developing permanent antimicrobial paint.

Dietary fiber content influences soluble carbohydrate levels in ruminal fluids.

PubMed

Pinder, R S; Patterson, J A; O'Bryan, C A; Crandall, P G; Ricke, S C

2012-01-01

The soluble carbohydrate concentration of ruminal fluid, as affected by dietary forage content (DFC) and/or ruminally undegradable intake protein content (UIPC), was determined. Four ruminally cannulated steers, in a 4 × 4 Latin square design, were offered diets containing high (75 % of DM) or low (25 % of DM) DFC and high (6 % of DM) or low (5 % of DM) UIPC, in a 2 × 2 factorial arrangement. Zinc-treated SBM was the primary UIP source. Soluble hexose concentration (145.1 μM) in ruminal fluid (RF) of steers fed low DFC diets exhibited a higher trend (P = 0.08) than that (124.5 μM) of steers fed high DFC diets. UIPC did not modulate (P = 0.54) ruminal soluble hexose concentrations. Regardless of diet, soluble hexose concentration declined immediately after feeding and did not rise until 3 h after feeding (P < 0.0001). Cellobiose (≈90 %) and glucose (≈10 %) were the major soluble hexoses present in RF. Maltose was not detected. Soluble glucose concentration (13.0 μM) was not modified by either UIPC (P = 0.40) nor DFC (P = 0.61). However, a DFC by post-prandial time interaction was detected (P = 0.02). Pentose concentrations were greater (P = 0.02) in RF of steers fed high DFC (100.2 μM) than steers fed low DFC (177.0 μM). UIPC did not influence (P = 0.35) soluble pentose concentration. The identity of soluble pentoses in ruminal fluid could not be determined. However, unsubstituted xylose and arabinose were excluded. These data indicate that: (i) soluble carbohydrate concentrations remain in ruminal fluid during digestion and fermentation; (ii) slight diurnal changes began after feeding; (iii) DFC influences the soluble carbohydrate concentration in RF; and (iv) UIPC of these diets does not affect the soluble carbohydrate concentration of RF.

Atomic elucidation of the cyclodextrin effects on DDT solubility and biodegradation.

PubMed

Ren, Baiping; Zhang, Mingzhen; Gao, Huipeng; Zheng, Jie; Jia, Lingyun

2016-07-14

DDT (1,1,1-trichloro-2.2-bis(p-chlorophenyl)ethane), one of the most abused insecticides, is a highly hazardous component for both human health and environmental applications. The biodegradation of DDT into non-toxic, environmentally benign components is strongly limited by the poor bioavailability of DDT. In this work, we combined experiments and molecular simulations to examine the effect of three cyclodextrins (α-, β-, and γ-CD) on their structure-specific interactions with DDT, specifically in relation to DDT solubility and biodegradability. It was found that all three CDs were able to bind to DDT with their inner hydrophobic cavity and different binding affinities and orientations, demonstrating their ability to improve DDT solubility. Different from the strong binding between DDT and β-/γ-CDs via a fully DDT bury mode, α-CD had a relatively weak binding with DDT via a partial DDT bury mode, which allowed DDT to be readily disassociated from α-CD at the lipid membrane interface, followed by DDT permeation into and across the cell membrane. The different binding modes between DDT and CDs explain why only α-CD can promote the bioavailability and biodegradation of DDT by simultaneously increasing its aqueous solubility and membrane interaction. This work provides structural-based binding information for the further modification and optimization of these three CDs to enhance their solubility and biodegradability of DDT.

Removal of glyphosate herbicide from water using biopolymer membranes.

PubMed

Carneiro, Rafael T A; Taketa, Thiago B; Gomes Neto, Reginaldo J; Oliveira, Jhones L; Campos, Estefânia V R; de Moraes, Mariana A; da Silva, Camila M G; Beppu, Marisa M; Fraceto, Leonardo F

2015-03-15

Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. The adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. The membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. The results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). The AG membrane did not show any adsorption capacity for this herbicide. The pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. The SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. The results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to treat a water sample contaminated with glyphosate. Biopolymer membranes therefore potentially offer a versatile method to eliminate agricultural chemicals from water supplies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Lamellar Biogels: Fluid-Membrane-Based Hydrogels Containing Polymer Lipids

NASA Astrophysics Data System (ADS)

Warriner, Heidi E.; Idziak, Stefan H. J.; Slack, Nelle L.; Davidson, Patrick; Safinya, Cyrus R.

1996-02-01

A class of lamellar biological hydrogels comprised of fluid membranes of lipids and surfactants with small amounts of low molecular weight poly(ethylene glycol)-derived polymer lipids (PEG-lipids) were studied by x-ray diffraction, polarized light microscopy, and rheometry. In contrast to isotropic hydrogels of polymer networks, these membrane-based birefringent liquid crystalline biogels, labeled Lα,g, form the gel phase when water is added to the liquid-like lamellar L_α phase, which reenters a liquid-like mixed phase upon further dilution. Furthermore, gels with larger water content require less PEG-lipid to remain stable. Although concentrated (~50 weight percent) mixtures of free PEG (molecular weight, 5000) and water do not gel, gelation does occur in mixtures containing as little as 0.5 weight percent PEG-lipid. A defining signature of the Lα,g regime as it sets in from the fluid lamellar L_α phase is the proliferation of layer-dislocation-type defects, which are stabilized by the segregation of PEG-lipids to the defect regions of high membrane curvature that connect the membranes.

Method to separate lignin-rich solid phase from acidic biomass suspension at an acidic pH

DOEpatents

Yasarla, Kumar Lakshmi Rakesh; Ramarao, Bandaru V; Amidon, Thomas

2017-09-05

A method of separating a lignin-rich solid phase from a solution suspension, by pretreating a lignocellulosic biomass with a pretreatment fluid having remove soluble components, colloidal material and primarily lignin containing particles; separating the pretreated lignocellulosic biomass from the pretreatment fluid with soluble components, colloidal material and primarily lignin containing particles; flocculating the separated pretreatment fluid with soluble components, colloidal material and primarily lignin containing particles using polyethylene oxide (i.e., PEO) or cationic Poly acrylamide (i.e., CPAM) as a flocculating agent; and filtering the flocculated separated pretreatment fluid with soluble components, colloidal material and primarily lignin containing particles to remove agglomerates.

Measurement of soluble CD59 in CSF in demyelinating disease: Evidence for an intrathecal source of soluble CD59.

PubMed

Zelek, Wioleta M; Watkins, Lewis M; Howell, Owain W; Evans, Rhian; Loveless, Sam; Robertson, Neil P; Beenes, Marijke; Willems, Loek; Brandwijk, Ricardo; Morgan, B Paul

2018-02-01

CD59, a broadly expressed glycosylphosphatidylinositol-anchored protein, is the principal cell inhibitor of complement membrane attack on cells. In the demyelinating disorders, multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), elevated complement protein levels, including soluble CD59 (sCD59), were reported in cerebrospinal fluid (CSF). We compared sCD59 levels in CSF and matched plasma in controls and patients with MS, NMOSD and clinically isolated syndrome (CIS) and investigated the source of CSF sCD59 and whether it was microparticle associated. sCD59 was quantified using enzyme-linked immunosorbent assay (ELISA; Hycult; HK374-02). Patient and control CSF was subjected to western blotting to characterise anti-CD59-reactive materials. CD59 was localised by immunostaining and in situ hybridisation. CSF sCD59 levels were double those in plasma (CSF, 30.2 ng/mL; plasma, 16.3 ng/mL). Plasma but not CSF sCD59 levels differentiated MS from NMOSD, MS from CIS and NMOSD/CIS from controls. Elimination of microparticles confirmed that CSF sCD59 was not membrane anchored. CSF levels of sCD59 are not a biomarker of demyelinating diseases. High levels of sCD59 in CSF relative to plasma suggest an intrathecal source; CD59 expression in brain parenchyma was low, but expression was strong on choroid plexus (CP) epithelium, immediately adjacent the CSF, suggesting that this is the likely source.

Evaluation of detergents for the soluble expression of alpha-helical and beta-barrel-type integral membrane proteins by a preparative scale individual cell-free expression system.

PubMed

Klammt, Christian; Schwarz, Daniel; Fendler, Klaus; Haase, Winfried; Dötsch, Volker; Bernhard, Frank

2005-12-01

Cell-free expression has become a highly promising tool for the fast and efficient production of integral membrane proteins. The proteins can be produced as precipitates that solubilize in mild detergents usually without any prior denaturation steps. Alternatively, membrane proteins can be synthesized in a soluble form by adding detergents to the cell-free system. However, the effects of a representative variety of detergents on the production, solubility and activity of a wider range of membrane proteins upon cell-free expression are currently unknown. We therefore analyzed the cell-free expression of three structurally very different membrane proteins, namely the bacterial alpha-helical multidrug transporter, EmrE, the beta-barrel nucleoside transporter, Tsx, and the porcine vasopressin receptor of the eukaryotic superfamily of G-protein coupled receptors. All three membrane proteins could be produced in amounts of several mg per one ml of reaction mixture. In general, the detergent 1-myristoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] was found to be most effective for the resolubilization of membrane protein precipitates, while long chain polyoxyethylene-alkyl-ethers proved to be most suitable for the soluble expression of all three types of membrane proteins. The yield of soluble expressed membrane protein remained relatively stable above a certain threshold concentration of the detergents. We report, for the first time, the high-level cell-free expression of a beta-barrel type membrane protein in a functional form. Structural and functional variations of the analyzed membrane proteins are evident that correspond with the mode of expression and that depend on the supplied detergent.

Array of planar membrane modules for producing hydrogen

DOEpatents

Vencill, Thomas R [Albuquerque, NM; Chellappa, Anand S [Albuquerque, NM; Rathod, Shailendra B [Hillsboro, OR

2012-05-08

A shared or common environment membrane reactor containing a plurality of planar membrane modules with top and bottom thin foil membranes supported by both an intermediary porous support plate and a central base which has both solid extended members and hollow regions or a hollow region whereby the two sides of the base are in fluid communication. The membrane reactor operates at elevate temperatures for generating hydrogen from hydrogen rich feed fuels.

Controlling the Release of Indomethacin from Glass Solutions Layered with a Rate Controlling Membrane Using Fluid-Bed Processing. Part 1: Surface and Cross-Sectional Chemical Analysis.

PubMed

Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy

2017-04-03

Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer remains amorphous after coating of the rate controlling membrane, whether formed from an ethanol solution or an aqueous dispersion.

How Lipid Membranes Affect Pore Forming Toxin Activity.

PubMed

Rojko, Nejc; Anderluh, Gregor

2015-12-15

Pore forming toxins (PFTs) evolved to permeate the plasma membrane of target cells. This is achieved in a multistep mechanism that usually involves binding of soluble protein monomer to the lipid membrane, oligomerization at the plane of the membrane, and insertion of part of the polypeptide chain across the lipid membrane to form a conductive channel. Introduced pores allow uncontrolled transport of solutes across the membrane, inflicting damage to the target cell. PFTs are usually studied from the perspective of structure-function relationships, often neglecting the important role of the bulk membrane properties on the PFT mechanism of action. In this Account, we discuss how membrane lateral heterogeneity, thickness, and fluidity influence the pore forming process of PFTs. In general, lipid molecules are more accessible for binding in fluid membranes due to steric reasons. When PFT specifically binds ordered domains, it usually recognizes a specific lipid distribution pattern, like sphingomyelin (SM) clusters or SM/cholesterol complexes, and not individual lipid species. Lipid domains were also suggested to act as an additional concentration platform facilitating PFT oligomerization, but this is yet to be shown. The last stage in PFT action is the insertion of the transmembrane segment across the membranes to build the transmembrane pore walls. Conformational changes are a spontaneous process, and sufficient free energy has to be available for efficient membrane penetration. Therefore, fluid bilayers are permeabilized more readily in comparison to highly ordered and thicker liquid ordered lipid phase (Lo). Energetically more costly insertion into the Lo phase can be driven by the hydrophobic mismatch between the thinner liquid disordered phase (Ld) and large protein complexes, which are unable to tilt like single transmembrane segments. In the case of proteolipid pores, membrane properties can directly modulate pore size, stability, and even selectivity. Finally, events associated with pore formation can modulate properties of the lipid membrane and affect its organization. Model membranes do not necessarily reproduce the physicochemical properties of the native cellular membrane, and caution is needed when transferring results from model to native lipid membranes. In this context, the utilization of novel approaches that enable studying PFTs on living cells at a single molecule level should reveal complex protein-lipid membrane interactions in greater detail.

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

Code of Federal Regulations, 2012 CFR

2012-04-01

... an aqueous solution which contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine dihydrochloride equivalent to 3.98 grams of piperazine base. (2) The drug is a soluble powder which when reconstituted with water contains in each fluid ounce 0.45 gram of levamisole hydrochloride...

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

Code of Federal Regulations, 2014 CFR

2014-04-01

... an aqueous solution which contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine dihydrochloride equivalent to 3.98 grams of piperazine base. (2) The drug is a soluble powder which when reconstituted with water contains in each fluid ounce 0.45 gram of levamisole hydrochloride...

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

Code of Federal Regulations, 2011 CFR

2011-04-01

... an aqueous solution which contains in each fluid ounce 0.36 gram of levamisole hydrochloride and piperazine dihydrochloride equivalent to 3.98 grams of piperazine base. (2) The drug is a soluble powder which when reconstituted with water contains in each fluid ounce 0.45 gram of levamisole hydrochloride...

Redox flow cell energy storage systems

NASA Technical Reports Server (NTRS)

Thaller, L. H.

1979-01-01

NASA-Redox systems are electrochemical storage devices that use two fully soluble Redox couples, anode and cathode fluids, as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of Redox flow cells where the electrochemical reactions (reduction and oxidation) take place at porous carbon felt electrodes. A string or stack of these power producing cells is connected in series in a bipolar manner. Redox energy storage systems promise to be inexpensive and possess many features that provide for flexible design, long life, high reliability and minimal operation and maintenance costs. These features include independent sizing of power and storage capacity requirements and inclusion within the cell stack of a cell that monitors the state of charge of the system as a whole, and a rebalance cell which permits continuous correction to be made for minor side reactions that would tend to result in the anode fluid and cathode fluids becoming electrochemically out of balance. These system features are described and discussed.

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.

IUPAC-NIST Solubility Data Series 70. The Solubility of Gases in Glassy Polymers

NASA Astrophysics Data System (ADS)

Paterson, Russell; Yampol'Skii, Yuri P.; Fogg, Peter G. T.; Bokarev, Alexandre; Bondar, Valerii; Ilinich, Oleg; Shishatskii, Sergey

1999-09-01

Solubility of gases in polymers is an important property of polymeric materials relevant to many practical applications. Sorption of small molecules in polymers is a fundamental concern in such areas as food packaging, beverage storage, and polymer processing. However, by far the main interest in the solubility of gases in polymers, and especially in glassy polymers, is related to development of novel advanced materials for gas separation membranes. This is because the concentration gradient of a dissolved gas is the driving force of membrane processes. Development of these novel separation methods resulted in a rapid accumulation, in the recent literature, of thermodynamic data related to the solubility of gases in polymers at different temperatures and pressures. Polymers can be regarded as special cases of media intermediate between liquids and solids. As a consequence, modeling of gas sorption in polymers is very difficult and presents a permanent challenge to theoreticians and experimenters. The collection and critical evaluation of solubility data for various gas-polymer systems is relevant to both practical aspects of polymer applications and to fundamental studies of polymer behavior. This volume of the IUPAC-NIST Solubility Data Series summarizes the compilations and critical evaluations of the data on solubility of gases in glassy polymers. It is implied in this edition that "gases" are the components that are either permanent gases (supercitical fluids) or have saturated vapor pressure more than 1 atm at ambient conditions (298 K). The polymeric components of compilations and critical evaluations are primarily high molecular mass, amorphous, linear (noncross-linked) compounds that have the glass transition temperatures above ambient temperature. The data for each gas-polymer system have been evaluated, if the results of at least three independent and reliable studies have been reported. Where the data of sufficient accuracy and reliability are available, values are recommended, and in some cases smoothing equations are given to represent variations of solubility with changes in gas pressure and temperature. Referenced works are presented in the standard IUPAC-NIST Solubility Data Series format. Depending on the gas-polymer system, reported data are given in tabular form or in the form of sorption isotherms. The data included in the volume comprise solubilities of 30 different gases in more than 80 primarily amorphous homo and copolymers. Where available, the compilation or critical evaluation sheets include enthalpies of sorption and parameters for sorption isotherms. Throughout the volume, SI conventions have been employed as the customary units in addition to the units used in original publications.

Synthetic Molecular Evolution of Membrane-Active Peptides

NASA Astrophysics Data System (ADS)

Wimley, William

The physical chemistry of membrane partitioning largely determines the function of membrane active peptides. Membrane-active peptides have potential utility in many areas, including in the cellular delivery of polar compounds, cancer therapy, biosensor design, and in antibacterial, antiviral and antifungal therapies. Yet, despite decades of research on thousands of known examples, useful sequence-structure-function relationships are essentially unknown. Because peptide-membrane interactions within the highly fluid bilayer are dynamic and heterogeneous, accounts of mechanism are necessarily vague and descriptive, and have little predictive power. This creates a significant roadblock to advances in the field. We are bypassing that roadblock with synthetic molecular evolution: iterative peptide library design and orthogonal high-throughput screening. We start with template sequences that have at least some useful activity, and create small, focused libraries using structural and biophysical principles to design the sequence space around the template. Orthogonal high-throughput screening is used to identify gain-of-function peptides by simultaneously selecting for several different properties (e.g. solubility, activity and toxicity). Multiple generations of iterative library design and screening have enabled the identification of membrane-active sequences with heretofore unknown properties, including clinically relevant, broad-spectrum activity against drug-resistant bacteria and enveloped viruses as well as pH-triggered macromolecular poration.

Polymide gas separation membranes

DOEpatents

Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz

2004-09-14

Soluble polyamic acid salt (PAAS) precursors comprised of tertiary and quaternary amines, ammonium cations, sulfonium cations, or phosphonium cations, are prepared and fabricated into membranes that are subsequently imidized and converted into rigid-rod polyimide articles, such as membranes with desirable gas separation properties. A method of enhancing solubility of PAAS polymers in alcohols is also disclosed.

A Versatile System for High-Throughput In Situ X-ray Screening and Data Collection of Soluble and Membrane-Protein Crystals

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

Broecker, Jana; Klingel, Viviane; Ou, Wei-Lin

In recent years, in situ data collection has been a major focus of progress in protein crystallography. Here, we introduce the Mylar in situ method using Mylar-based sandwich plates that are inexpensive, easy to make and handle, and show significantly less background scattering than other setups. A variety of cognate holders for patches of Mylar in situ sandwich films corresponding to one or more wells makes the method robust and versatile, allows for storage and shipping of entire wells, and enables automated crystal imaging, screening, and goniometerbased X-ray diffraction data-collection at room temperature and under cryogenic conditions for soluble andmore » membrane-protein crystals grown in or transferred to these plates. We validated the Mylar in situ method using crystals of the water-soluble proteins hen egg-white lysozyme and sperm whale myoglobin as well as the 7-transmembrane protein bacteriorhodopsin from Haloquadratum walsbyi. In conjunction with current developments at synchrotrons, this approach promises high-resolution structural studies of membrane proteins to become faster and more routine.« less

Apparatus and method for selectively channeling a fluid

DOEpatents

Rightley, Michael Joseph [Albuquerque, NM

2008-01-01

An apparatus for selectively channeling a high temperature fluid without chemically reacting with the fluid. The apparatus includes an inlet and a membrane positioned adjacent to the inlet, each composed of a chemically inert material. The membrane is formed by compressive preloading techniques. The apparatus further includes a seat disposed on the inlet adjacent to the membrane. The seat is composed of a heat resistant and chemically inert material. Operation of the apparatus requires that the temperature of the fluid remains below the chemical characteristic melting point of the seat. The apparatus further includes an actuator coupled to the membrane for rendering the membrane in an open and a closed position with respect to the seat. Specifically, the actuator supplies a load in the normal direction to the membrane to selectively engage the membrane in a plurality of predetermined configurations. Operatively, the apparatus receives the fluid at the inlet. The fluid is received at a high temperature and is directed from the inlet to the membrane. In the closed position, the actuator engages the membrane to prevent the fluid from flowing from the inlet between the membrane and the seat. Alternatively, in the open position, the actuator engages the membrane to permit fluid flow from the inlet between the membrane and the seat to at least one outlet provided by the apparatus. In one exemplary embodiment, the fluid may be discharged from the at least one outlet to a sensor in fluid communication with the at least one outlet. Accordingly, the sensor may measure the fluid channeled through the heat resistant and chemically inert environment provided by the apparatus.

Effect of hydrothermal pretreatment on solubility and formation of kenaf cellulose membrane and hydrogel.

PubMed

Gan, Sinyee; Zakaria, Sarani; Chia, Chin Hua; Padzil, Farah Nadia Mohammad; Ng, Peivun

2015-01-22

The hydrothermal pretreatment on kenaf core pulp (KCP) was carried out using an autoclave heated in a oil bath at 140°C for 0.5/1/3/5h. The hydrothermal pretreated kenaf (HPK) was dissolved in a LiOH/urea aqueous solution and subsequently used to produce cellulose membrane and hydrogel. The effects of hydrothermal pretreatment time on solubility, viscosity, crystallinity and morphology of the cellulose membrane and hydrogel were investigated. The hydrothermal pretreatment leads to higher cellulose solubility and higher viscosity of the cellulose solution. The formation of cellulose II and crystallinity index of the cellulose membrane and hydrogel were examined by X-ray diffraction (XRD). The pore size of the cellulose membrane and hydrogel displayed an upward trend with respect to the hydrothermal pretreatment period observed under a field emission scanning electron microscope (FESEM). This finding provides an efficient procedure to improve the solubility, viscosity and properties of regenerated cellulose products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fouling analysis of membrane bioreactor treating antibiotic production wastewater at different hydraulic retention times.

PubMed

Yu, Dawei; Chen, Yutao; Wei, Yuansong; Wang, Jianxing; Wang, Yawei; Li, Kun

2017-04-01

Membrane fouling, including foulants and factors, was investigated during hydraulic retention time (HRT) optimization of a membrane bioreactor (MBR) that treated wastewater from the production of antibiotics. The results showed that HRT played an important role in membrane fouling. Trans-membrane pressure (TMP), membrane flux, and resistance were stable at -6 kPa, 76 L m -2  h -1  bar -1 , and 4.5 × 10 12  m -1 when HRT was at 60, 48, and 36 h, respectively. Using Fourier transform infrared spectroscopy, foulants were identified as carbohydrates and proteins, which correlated with effluent organic matter and effluent chemical oxygen demand (COD) compounds. Therefore, membrane fouling trends would benefit from low supernatant COD (378 mg L -1 ) and a low membrane removal rate (26 %) at a HRT of 36 h. Serious membrane fouling at 72 and 24 h was related to soluble microbial products and extracellular polymeric substances in mixed liquor, respectively. Based on the TMP decrease and flux recovery after physical and chemical cleaning, irremovable fouling aggravation was related to extracellular polymeric substances' increase and soluble microbial products' decrease. According to changes in the specific oxygen uptake rate (SOUR) and mixed liquor suspended solids (MLSSs) during HRT optimization in this study, antibiotic production wastewater largely inhibited MLSS growth, which only increased from 4.5 to 5.0 g L -1 when HRT was decreased from 72 to 24 h, but did not limit sludge activity. The results of a principal component analysis highlighted both proteins and carbohydrates in extracellular polymeric substances as the primary foulants. Membrane fouling associated with the first principal component was positively related to extracellular polymeric substances and negatively related to soluble microbial products. Principal component 2 was primarily related to proteins in the influent. Additional membrane fouling factors included biomass characteristics, operational conditions, and feed characteristics.

Activation status-coupled transient S acylation determines membrane partitioning of a plant Rho-related GTPase.

PubMed

Sorek, Nadav; Poraty, Limor; Sternberg, Hasana; Bar, Enat; Lewinsohn, Efraim; Yalovsky, Shaul

2007-03-01

ROPs or RACs are plant Rho-related GTPases implicated in the regulation of a multitude of signaling pathways that function at the plasma membrane by virtue of posttranslational lipid modifications. The relationship between ROP activation status and membrane localization has not been established. Here we demonstrate that endogenous ROPs, as well as a transgenic His(6)-green fluorescent protein (GFP)-AtROP6 fusion protein, were partitioned between Triton X-100-soluble and -insoluble membranes. In contrast, an activated His(6)-GFP-Atrop6(CA) mutant protein accumulated exclusively in detergent-resistant membranes. GDP induced accumulation of ROPs in Triton-soluble membranes, whereas GTPgammaS induced accumulation of ROPs in detergent-resistant membranes. Recombinant wild-type and constitutively active AtROP6 isoforms were purified from Arabidopsis plants, and their lipids were cleaved and analyzed by gas chromatography-coupled mass spectrometry. In Triton-soluble membranes, wild-type AtROP6 was only prenylated, primarily by geranylgeranyl. The activated AtROP6 that accumulated in detergent-resistant membranes was modified by prenyl and acyl lipids. The acyl lipids were identified as palmitic and stearic acids. In agreement, activated His(6)-GFP-Atrop6(CA)mS(156) in which cysteine(156) was mutated into serine accumulated in Triton-soluble membranes. These findings show that upon GTP binding and activation, AtROP6 and possibly other ROPs are transiently S acylated, which induces their partitioning into detergent-resistant membranes.

Corrected and Republished from: Activation Status-Coupled Transient S-Acylation Determines Membrane Partitioning of a Plant Rho-Related GTPase.

PubMed

Sorek, Nadav; Poraty, Limor; Sternberg, Hasana; Buriakovsky, Ella; Bar, Einat; Lewinsohn, Efraim; Yalovsky, Shaul

2017-12-01

ROPs or RACs are plant Rho-related GTPases implicated in the regulation of a multitude of signaling pathways that function at the plasma membrane via posttranslational lipid modifications. The relationships between ROP activation status and membrane localization has not been established. Here, we show that endogenous ROPs, as well as a transgenic His 6 -green fluorescent protein (GFP)- Arabidopsis thaliana ROP6 (AtROP6) fusion protein, were partitioned between Triton X-100-soluble and -insoluble membranes. In contrast, the His 6 -GFP-Atrop6 CA activated mutant accumulated exclusively in detergent-resistant membranes. GDP induced accumulation of ROPs in Triton-soluble membranes, whereas GTPγS induced accumulation of ROPs in detergent-resistant membranes. Recombinant wild-type and constitutively active AtROP6 proteins were purified from Arabidopsis plants, and in turn, their lipids were cleaved and analyzed by gas chromatography-coupled mass spectrometry. In Triton-soluble membranes, the wild-type AtROP6 was only prenylated, primarily by geranylgeranyl. The activated AtROP6 that accumulated in detergent-resistant membranes was modified by prenyl and acyl lipids, identified as palmitic and stearic acids. Consistently, activated His 6 -GFP-Atrop6 CA mS 156 , in which C156 was mutated into serine, accumulated in Triton-soluble membranes. These findings show that upon GTP binding and activation, AtROP6, and possibly other ROPs, are transiently S-acylated, inducing their partitioning into detergent-resistant membranes. Copyright © 2017 American Society for Microbiology.

Corrected and Republished from: Activation Status-Coupled Transient S-Acylation Determines Membrane Partitioning of a Plant Rho-Related GTPase

PubMed Central

Sorek, Nadav; Poraty, Limor; Sternberg, Hasana; Buriakovsky, Ella; Bar, Einat; Lewinsohn, Efraim

2017-01-01

ABSTRACT ROPs or RACs are plant Rho-related GTPases implicated in the regulation of a multitude of signaling pathways that function at the plasma membrane via posttranslational lipid modifications. The relationships between ROP activation status and membrane localization has not been established. Here, we show that endogenous ROPs, as well as a transgenic His6-green fluorescent protein (GFP)-Arabidopsis thaliana ROP6 (AtROP6) fusion protein, were partitioned between Triton X-100-soluble and -insoluble membranes. In contrast, the His6-GFP-Atrop6CA activated mutant accumulated exclusively in detergent-resistant membranes. GDP induced accumulation of ROPs in Triton-soluble membranes, whereas GTPγS induced accumulation of ROPs in detergent-resistant membranes. Recombinant wild-type and constitutively active AtROP6 proteins were purified from Arabidopsis plants, and in turn, their lipids were cleaved and analyzed by gas chromatography-coupled mass spectrometry. In Triton-soluble membranes, the wild-type AtROP6 was only prenylated, primarily by geranylgeranyl. The activated AtROP6 that accumulated in detergent-resistant membranes was modified by prenyl and acyl lipids, identified as palmitic and stearic acids. Consistently, activated His6-GFP-Atrop6CAmS156, in which C156 was mutated into serine, accumulated in Triton-soluble membranes. These findings show that upon GTP binding and activation, AtROP6, and possibly other ROPs, are transiently S-acylated, inducing their partitioning into detergent-resistant membranes. PMID:28894027

Expression of membrane-bound and cytosolic guanylyl cyclases in the rat inner ear.

PubMed

Seebacher, T; Beitz, E; Kumagami, H; Wild, K; Ruppersberg, J P; Schultz, J E

1999-01-01

Membrane-bound guanylyl cyclases (GCs) are peptide hormone receptors whereas the cytosolic isoforms are receptors for nitric oxide. In the inner ear, the membrane-bound GCs may be involved in the regulation of fluid homeostasis and the cytosolic forms possibly play a role in signal processing and regulation of local blood flow. In this comprehensive study, we examined, qualitatively and quantitatively, the transcription pattern of all known GC isoforms in the inner ear from rat by RT-PCR. The tissues used were endolymphatic sac, stria vascularis, organ of Corti, organ of Corti outer hair cells, cochlear nerve, Reissner's membrane, vestibular dark cells, and vestibular sensory cells. We show that multiple particulate (GC-A, GC-B, GC-D, GC-E, GC-F and GC-G) and several subunits of the heterodimeric cytosolic GCs (alpha1, alpha2, beta1 and beta2) are expressed, albeit at highly different levels. GC-C was not found. GC-A and the soluble subunits alpha1 and beta1 were transcribed ubiquitously. GC-B was present in all tissues except stria vascularis, which contained GC-A and traces of GC-E and GC-G. GC-B was by far the predominant membrane-bound isoform in the organ of Corti (86%), Reissner's membrane (75%) and the vestibulum (80%). Surprisingly, GC-E, a retinal isoform, was detected in significant amounts in the cochlear nerve (8%) and in the organ of Corti (4%). Although the cytosolic GC is a heterodimer composed of an alpha and a beta subunit, the mRNA transcription of these subunits was not stoichiometric. Particularly in the vestibulum, the transcription of the beta1 subunits was at least four-fold higher than of the alpha1 subunit. The data are compatible with earlier suggestions that membrane receptor GCs may be involved in the control of inner ear electrolyte and fluid composition whereas NO-stimulated GC isoforms mainly participate in the regulation of blood flow and supporting cell physiology.

MStern Blotting-High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates.

PubMed

Berger, Sebastian T; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

2015-10-01

We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used membrane-based proteomic sample processing method. We validated our approach on whole-cell lysate and urine and cerebrospinal fluid as clinically relevant body fluids. Without compromising peptide and protein identification, our method uses a vacuum manifold and circumvents the need for digest desalting, making our processing method compatible with standard liquid handling robots. In summary, our new method maintains the strengths of FASP and simultaneously overcomes one of the major limitations of FASP without compromising protein identification and quantification. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

MStern Blotting–High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates*

PubMed Central

Berger, Sebastian T.; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

2015-01-01

We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used membrane-based proteomic sample processing method. We validated our approach on whole-cell lysate and urine and cerebrospinal fluid as clinically relevant body fluids. Without compromising peptide and protein identification, our method uses a vacuum manifold and circumvents the need for digest desalting, making our processing method compatible with standard liquid handling robots. In summary, our new method maintains the strengths of FASP and simultaneously overcomes one of the major limitations of FASP without compromising protein identification and quantification. PMID:26223766

Low aqueous solubility of 11-cis-retinal limits the rate of pigment formation and dark adaptation in salamander rods.

PubMed

Frederiksen, Rikard; Boyer, Nicholas P; Nickle, Benjamin; Chakrabarti, Kalyan S; Koutalos, Yiannis; Crouch, Rosalie K; Oprian, Daniel; Cornwall, M Carter

2012-06-01

We report experiments designed to test the hypothesis that the aqueous solubility of 11-cis-retinoids plays a significant role in the rate of visual pigment regeneration. Therefore, we have compared the aqueous solubility and the partition coefficients in photoreceptor membranes of native 11-cis-retinal and an analogue retinoid, 11-cis 4-OH retinal, which has a significantly higher solubility in aqueous medium. We have then correlated these parameters with the rates of pigment regeneration and sensitivity recovery that are observed when bleached intact salamander rod photoreceptors are treated with physiological solutions containing these retinoids. We report the following results: (a) 11-cis 4-OH retinal is more soluble in aqueous buffer than 11-cis-retinal. (b) Both 11-cis-retinal and 11-cis 4-OH retinal have extremely high partition coefficients in photoreceptor membranes, though the partition coefficient of 11-cis-retinal is roughly 50-fold greater than that of 11-cis 4-OH retinal. (c) Intact bleached isolated rods treated with solutions containing equimolar amounts of 11-cis-retinal or 11-cis 4-OH retinal form functional visual pigments that promote full recovery of dark current, sensitivity, and response kinetics. However, rods treated with 11-cis 4-OH retinal regenerated on average fivefold faster than rods treated with 11-cis-retinal. (d) Pigment regeneration from recombinant and wild-type opsin in solution is slower when treated with 11-cis 4-OH retinal than with 11-cis-retinal. Based on these observations, we propose a model in which aqueous solubility of cis-retinoids within the photoreceptor cytosol can place a limit on the rate of visual pigment regeneration in vertebrate photoreceptors. We conclude that the cytosolic gap between the plasma membrane and the disk membranes presents a bottleneck for retinoid flux that results in slowed pigment regeneration and dark adaptation in rod photoreceptors.

A Novel Domain Assembly Routine for Creating Full-Length Models of Membrane Proteins from Known Domain Structures.

PubMed

Koehler Leman, Julia; Bonneau, Richard

2018-04-03

Membrane proteins composed of soluble and membrane domains are often studied one domain at a time. However, to understand the biological function of entire protein systems and their interactions with each other and drugs, knowledge of full-length structures or models is required. Although few computational methods exist that could potentially be used to model full-length constructs of membrane proteins, none of these methods are perfectly suited for the problem at hand. Existing methods require an interface or knowledge of the relative orientations of the domains or are not designed for domain assembly, and none of them are developed for membrane proteins. Here we describe the first domain assembly protocol specifically designed for membrane proteins that assembles intra- and extracellular soluble domains and the transmembrane domain into models of the full-length membrane protein. Our protocol does not require an interface between the domains and samples possible domain orientations based on backbone dihedrals in the flexible linker regions, created via fragment insertion, while keeping the transmembrane domain fixed in the membrane. For five examples tested, our method mp_domain_assembly, implemented in RosettaMP, samples domain orientations close to the known structure and is best used in conjunction with experimental data to reduce the conformational search space.

Ultraselective Carbon Molecular Sieve Membranes with Tailored Synergistic Sorption Selective Properties.

PubMed

Zhang, Chen; Koros, William J

2017-09-01

Membrane-based separations can reduce the energy consumption and the CO 2 footprint of large-scale fluid separations, which are traditionally practiced by energy-intensive thermally driven processes. Here, a new type of membrane structure based on nanoporous carbon is reported, which, according to this study, is best referred to as carbon/carbon mixed-matrix (CCMM) membranes. The CCMM membranes are formed by high-temperature (up to 900 °C) pyrolysis of polyimide precursor hollow-fiber membranes. Unprecedentedly high permselectivities are seen in CCMM membranes for CO 2 /CH 4 , N 2 /CH 4 , He/CH 4 , and H 2 /CH 4 separations. Analysis of permeation data suggests that the ultrahigh selectivities result from substantially increased sorption selectivities, which is hypothetically owing to the formation of ultraselective micropores that selectively exclude the bulkier CH 4 molecules. With tunable sorption selectivities, the CCMM membranes outperform flexible polymer membranes and traditional rigid molecular-sieve membranes. The capability to increase sorption selectivities is a powerful tool to leverage diffusion selectivities, and has opened the door to many challenging and economically important fluid separations that require ultrafine differentiation of closely sized molecules. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Generalized Boussinesq-Scriven surface fluid model with curvature dissipation for liquid surfaces and membranes.

PubMed

Aguilar Gutierrez, Oscar F; Herrera Valencia, Edtson E; Rey, Alejandro D

2017-10-01

Curvature dissipation is relevant in synthetic and biological processes, from fluctuations in semi-flexible polymer solutions, to buckling of liquid columns, tomembrane cell wall functioning. We present a micromechanical model of curvature dissipation relevant to fluid membranes and liquid surfaces based on a parallel surface parameterization and a stress constitutive equation appropriate for anisotropic fluids and fluid membranes.The derived model, aimed at high curvature and high rate of change of curvature in liquid surfaces and membranes, introduces additional viscous modes not included in the widely used 2D Boussinesq-Scriven rheological constitutive equation for surface fluids.The kinematic tensors that emerge from theparallel surface parameterization are the interfacial rate of deformation and the surface co-rotational Zaremba-Jaumann derivative of the curvature, which are used to classify all possibledissipative planar and non-planar modes. The curvature dissipation function that accounts for bending, torsion and twist rates is derived and analyzed under several constraints, including the important inextensional bending mode.A representative application of the curvature dissipation model to the periodic oscillation in nano-wrinkled outer hair cells show how and why curvature dissipation decreases with frequency, and why the 100kHz frequency range is selected. These results contribute to characterize curvature dissipation in membranes and liquid surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

CO2 adsorption using TiO2 composite polymeric membranes: A kinetic study.

PubMed

Hafeez, Sarah; Fan, X; Hussain, Arshad; Martín, C F

2015-09-01

CO2 is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO2. Membrane gas separation is a fast growing CO2 capture technique, particularly gas separation by composite membranes. The separation of CO2 by a membrane is not just a process to physically sieve out of CO2 through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO2. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO2 in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO2 through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO2) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO2 membrane adsorbed more quantity of CO2 gas as compared to pure CA membrane. The high CO2 adsorption capacity may enhance the diffusion and solubility of CO2 in the CA-TiO2 composite membrane, which results in a better CO2 separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R(2), the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion. Copyright © 2015. Published by Elsevier B.V.

Social disparities in heart disease risk and survivor bias among autoworkers: an examination based on survival models and g-estimation.

PubMed

Costello, Sadie; Picciotto, Sally; Rehkopf, David H; Eisen, Ellen A

2015-02-01

To examine gender and racial disparities in ischaemic heart disease (IHD) mortality related to metalworking fluid exposures and in the healthy worker survivor effect. A cohort of white and black men and women autoworkers in the USA was followed from 1941 to 1995 with quantitative exposure to respirable particulate matter from water-based metalworking fluids. Separate analyses used proportional hazards models and g-estimation. The HR for IHD among black men was 3.29 (95% CI 1.49 to 7.31) in the highest category of cumulative synthetic fluid exposure. The HR for IHD among white women exposed to soluble fluid reached 2.44 (95% CI 0.96 to 6.22). However, no increased risk was observed among white men until we corrected for the healthy worker survivor effect. Results from g-estimation indicate that if white male cases exposed to soluble or synthetic fluid had been unexposed to that fluid type, then 1.59 and 1.20 years of life would have been saved on average, respectively. We leveraged the strengths of two different analytic approaches to examine the IHD risks of metalworking fluids. All workers may have the same aetiological risk; however, black and female workers may experience more IHD from water-based metalworking fluid exposure because of a steeper exposure-response or weaker healthy worker survivor effect. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Octopus microvasculature: permeability to ferritin and carbon.

PubMed

Browning, J

1979-01-01

The permeability of Octopus microvasculature was investigated by intravascular injection of carbon and ferritin. Vessels were tight to carbon while ferritin penetrated the pericyte junction, and was found extravascularly 1-2 min after its introduction. Vesicles occurred rarely in pericytes; fenestrae were absent. The discontinuous endothelial layer did not consitute a permeability barrier. The basement membrane, although retarding the movement of ferritin, was permeable to it; carbon did not penetrate the basement membrane. Evidence indicated that ferritin, and thus similarly sized and smaller water soluble materials, traverse the pericyte junction as a result of bulk fluid flow. Comparisons are made with the convective (or junctional) and slower, diffusive (or vesicular) passage of materials known to occur across the endothelium of continuous capillaries in mammals. Previous macrophysiological determinations concerning the permeability of Octopus vessels are questioned in view of these findings. Possible reasons for some major structural differences in the microcirculatory systems of cephalopods and vertebrates are briefly discussed.

Preparations and properties of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials.

PubMed

Watanabe, Shoji

2008-01-01

This short review describes various types of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials. It is concerned with synthetic additives classified according to their functional groups; silicone compounds, carboxylic acids and dibasic acids, esters, Diels-Alder adducts, various polymers, nitrogen compounds, phosphoric esters, phosphonic acids, and others. Testing methods for water-soluble metal working fluids for aluminum alloy materials are described for a practical application in a laboratory.

A Novel Soluble Peptide with pH-Responsive Membrane Insertion.

PubMed

Nguyen, Vanessa P; Alves, Daiane S; Scott, Haden L; Davis, Forrest L; Barrera, Francisco N

2015-11-03

Several diseases, such as cancer, are characterized by acidification of the extracellular environment. Acidosis can be employed as a target to specifically direct therapies to the diseased tissue. We have used first principles to design an acidity-triggered rational membrane (ATRAM) peptide with high solubility in solution that is able to interact with lipid membranes in a pH-dependent fashion. Biophysical studies show that the ATRAM peptide binds to the surface of lipid membranes at pH 8.0. However, acidification leads to the peptide inserting into the lipid bilayer as a transmembrane α-helix. The insertion of ATRAM into membranes occurs at a moderately acidic pH (with a pK of 6.5), similar to the extracellular pH found in solid tumors. Studies with human cell lines showed a highly efficient pH-dependent membrane targeting, without causing toxicity. Here we show that it is possible to rationally design a soluble peptide that selectively targets cell membranes in acidic environments.

Mutants in three novel complementation groups inhibit membrane protein insertion into and soluble protein translocation across the endoplasmic reticulum membrane of Saccharomyces cerevisiae

PubMed Central

1992-01-01

We have isolated mutants that inhibit membrane protein insertion into the ER membrane of Saccharomyces cerevisiae. The mutants were contained in three complementation groups, which we have named SEC70, SEC71, and SEC72. The mutants also inhibited the translocation of soluble proteins into the lumen of the ER, indicating that they pleiotropically affect protein transport across and insertion into the ER membrane. Surprisingly, the mutants inhibited the translocation and insertion of different proteins to drastically different degrees. We have also shown that mutations in SEC61 and SEC63, which were previously isolated as mutants inhibiting the translocation of soluble proteins, also affect the insertion of membrane proteins into the ER. Taken together our data indicate that the process of protein translocation across the ER membrane involves a much larger number of gene products than previously appreciated. Moreover, different translocation substrates appear to have different requirements for components of the cellular targeting and translocation apparatus. PMID:1730771

APPLICATION OF VARIOUS POLYMERS AND POLYMERS BASED TECHNIQUES USED TO IMPROVE SOLUBILITY OF POORLY WATER SOLUBLE DRUGS: A REVIEW.

PubMed

Muhammad Sarfraz, Rai; Bashir, Sajid; Mahmood, Asif; Ahsan, Haseeb; Riaz, Humayun; Raza, Hina; Rashid, Zermina; Atif Raza, Syed; Asad Abrar, Muhammad; Abbas, Khawar; Yasmeen, Tahira

2017-03-01

Solubility is concerned with solute and solvent to form a homogenous mixture. If solubility of a drug is low, then usually it is difficult to achieve desired therapeutic level of drug. Most of the newly developed entities have solubility problems and encounter difficulty in dissolution. Basic aim of solubility enhancement is to achieve desired therapeutic'level of drug to produce required pharmacological response. Different techniques are being used to enhance the solubility of water insoluble drugs. These techniques include particle size reduction, spray drying, kneading method, solvent evaporation method, salt formation, microemulsions, co-solven- cy, hydrosols, prodrug approach, supercritical fluid process, hydrogel micro particles etc. Selection of solubility improving method depends on drug properties, site of absorption, and required dosage form characteristics. Variety of polymers are also used to enhance solubility of these drugs like polyethylene glycol 300, polyvinyl pyrrolidone, chitosan, β-cyclodextrins etc.

Bioinspired model of mechanical energy harvesting based on flexoelectric membranes.

PubMed

Rey, Alejandro D; Servio, P; Herrera-Valencia, E E

2013-02-01

Membrane flexoelectricity is an electromechanical coupling process that describes membrane electrical polarization due to bending and membrane bending under electric fields. In this paper we propose, formulate, and characterize a mechanical energy harvesting system consisting of a deformable soft flexoelectric thin membrane subjected to harmonic forcing from contacting bulk fluids. The key elements of the energy harvester are formulated and characterized, including (i) the mechanical-to-electrical energy conversion efficiency, (ii) the electromechanical shape equation connecting fluid forces with membrane curvature and electric displacement, and (iii) the electric power generation and efficiency. The energy conversion efficiency is cast as the ratio of flexoelectric coupling to the product of electric and bending elasticity. The device is described by a second-order curvature dynamics coupled to the electric displacement equation and as such results in mechanical power absorption with a resonant peak whose amplitude decreases with bending viscosity. The electric power generation is proportional to the conversion factor and the power efficiency decreases with frequency. Under high bending viscosity, the power efficiency increases with the conversion factor and under low viscosities it decreases with the conversion factor. The theoretical results presented contribute to the ongoing experimental efforts to develop mechanical energy harvesting from fluid flow energy through solid-fluid interactions and electromechanical transduction.

Formulation, functional evaluation and ex vivo performance of thermoresponsive soluble gels - A platform for therapeutic delivery to mucosal sinus tissue.

PubMed

Pandey, Preeti; Cabot, Peter J; Wallwork, Benjamin; Panizza, Benedict J; Parekh, Harendra S

2017-01-01

Mucoadhesive in situ gelling systems (soluble gels) have received considerable attention recently as effective stimuli-transforming vectors for a range of drug delivery applications. Considering this fact, the present work involves systematic formulation development, optimization, functional evaluation and ex vivo performance of thermosensitive soluble gels containing dexamethasone 21-phosphate disodium salt (DXN) as the model therapeutic. A series of in situ gel-forming systems comprising the thermoreversible polymer poloxamer-407 (P407), along with hydroxypropyl methyl cellulose (HPMC) and chitosan were first formulated. The optimized soluble gels were evaluated for their potential to promote greater retention at the mucosal surface, for improved therapeutic efficacy, compared to existing solution/suspension-based steroid formulations used clinically. Optimized soluble gels demonstrated a desirable gelation temperature with Newtonian fluid behaviour observed under storage conditions (4-8°C), and pseudoplastic fluid behaviour recorded at nasal cavity/sinus temperature (≈34°C). The in vitro characterization of formulations including rheological evaluation, textural analysis and mucoadhesion studies of the gel form were investigated. Considerable improvement in mechanical properties and mucoadhesion was observed with incorporation of HPMC and chitosan into the gelling systems. The lead poloxamer-based soluble gels, PGHC4 and PGHC7, which were carried through to ex vivo permeation studies displayed extended drug release profiles in conditions mimicking the human nasal cavity, which indicates their suitability for treating a range of conditions affecting the nasal cavity/sinuses. Copyright © 2016 Elsevier B.V. All rights reserved.

In Vitro Reconstitution of Autophagosome-Lysosome Fusion.

PubMed

Diao, J; Li, L; Lai, Y; Zhong, Q

2017-01-01

SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) proteins are a highly regulated class of membrane proteins lying in the center of membrane fusion. In conjunction with accessory proteins, SNAREs drive efficient merger of two distinct lipid bilayers into one interconnected structure. This chapter describes our fluorescence resonance energy transfer (FRET)-based proteoliposome fusion assays for the roles of various SNARE proteins, accessory proteins, and effects of different lipid compositions on membrane fusion involved in autophagy. © 2017 Elsevier Inc. All rights reserved.

An Animal Model to Investigate the Potential for Breast Cancer Metastatic Dissemination Following Surgery Intervention on the Primitive Tumor

DTIC Science & Technology

2010-09-01

cancer cells at the plasma membrane level were measured by cell surface biotinylation, using a dedicated kit (cat. #89881) obtained from Pierce...each form of the receptor at the plasma membrane of transfected cells was confirmed by isolation of cell surface proteins obtained by biotinylation...this receptor to interact with both plasma membrane-bound and soluble FKN. Based on our study, it seems reasonable to postulate that the dissemination

Matrix Metalloproteinase-8 Inactivates Macrophage Inflammatory Protein-1α to Reduce Acute Lung Inflammation and Injury in Mice

PubMed Central

Quintero, Pablo A.; Knolle, Martin D.; Cala, Luisa F.; Zhuang, Yuehong; Owen, Caroline A.

2010-01-01

To determine the role of matrix metalloproteinase-8 (MMP-8) in acute lung injury (ALI), we delivered LPS or bleomycin by the intratracheal route to MMP-8−/− mice versus WT mice or subjected the mice to hyperoxia (95% O2) and measured lung inflammation and injury at intervals. MMP-8−/− mice with ALI had greater increases in lung PMN and macrophage counts, measures of alveolar capillary barrier injury, lung elastance, and mortality than WT mice with ALI. Bronchoalveolar lavage fluid (BALF) from LPS-treated MMP-8−/− mice had more macrophage inflammatory protein-1α (MIP-1α) than BALF from LPS-treated WT mice, but similar levels of other pro- and anti-inflammatory mediators. MIP-1α−/− mice with ALI had less acute lung inflammation and injury than WT mice with ALI, confirming that MIP-1α promotes acute lung inflammation and injury in mice. Genetically deleting MIP-1α in MMP-8−/− mice abrogated the increased lung inflammation and injury and mortality in MMP-8−/− mice with ALI. Soluble MMP-8 cleaved and inactivated MIP-1α in vitro, but membrane-bound MMP-8 on activated PMNs had greater MIP-1α-degrading activity than soluble MMP-8. High levels of membrane-bound MMP-8 were detected on lung PMNs from LPS-treated WT mice, but soluble, active MMP-8 was not detected in BALF samples. Thus, MMP-8 has novel roles in restraining lung inflammation and in limiting alveolar capillary barrier injury during ALI in mice by inactivating MIP-1α. In addition, membrane-bound MMP-8 on activated lung PMNs is likely to be the key bioactive form of the enzyme that limits lung inflammation and alveolar capillary barrier injury during ALI. PMID:20042585

Global Membrane Protein Interactome Analysis using In vivo Crosslinking and Mass Spectrometry-based Protein Correlation Profiling*

PubMed Central

Larance, Mark; Kirkwood, Kathryn J.; Tinti, Michele; Brenes Murillo, Alejandro; Ferguson, Michael A. J.; Lamond, Angus I.

2016-01-01

We present a methodology using in vivo crosslinking combined with HPLC-MS for the global analysis of endogenous protein complexes by protein correlation profiling. Formaldehyde crosslinked protein complexes were extracted with high yield using denaturing buffers that maintained complex solubility during chromatographic separation. We show this efficiently detects both integral membrane and membrane-associated protein complexes,in addition to soluble complexes, allowing identification and analysis of complexes not accessible in native extracts. We compare the protein complexes detected by HPLC-MS protein correlation profiling in both native and formaldehyde crosslinked U2OS cell extracts. These proteome-wide data sets of both in vivo crosslinked and native protein complexes from U2OS cells are freely available via a searchable online database (www.peptracker.com/epd). Raw data are also available via ProteomeXchange (identifier PXD003754). PMID:27114452

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.

Systems, compositions, and methods for fluid purification

DOEpatents

Ho, W.S. Winston; Verweij, Hendrik; Shqau, Krenar; Ramasubranian, Kartik

2015-12-22

Disclosed herein are membranes comprising a substrate, a support layer, and a selective layer. In some embodiments the membrane may further comprise a permeable layer. Methods of forming membranes are also disclosed comprising forming a support layer on a substrate, removing adsorbed species from the support layer, preparing a solution containing inorganic materials of a selective layer, contacting the support layer with the solution, drying the membrane, and exposing the membrane to rapid thermal processing. Also disclosed are methods of fluid purification comprising providing a membrane having a feed side and a permeable side, passing a fluid mixture across the feed side of the membrane, providing a driving force for transmembrane permeation, removing from the permeate side a permeate stream enriched in a purified fluid, and withdrawing from the feed side a fluid that is depleted in a purified fluid.

Integrin-associated protein (CD47) is a putative mediator for soluble fibrinogen interaction with human red blood cells membrane.

PubMed

De Oliveira, S; Vitorino de Almeida, V; Calado, A; Rosário, H S; Saldanha, C

2012-03-01

Fibrinogen is a multifunctional plasma protein that plays a crucial role in several biological processes. Elevated fibrinogen induces erythrocyte hyperaggregation, suggesting an interaction between this protein and red blood cells (RBCs). Several studies support the concept that fibrinogen interacts with RBC membrane and this binding, due to specific and non-specific mechanisms, may be a trigger to RBC hyperaggregation in inflammation. The main goals of our work were to prove that human RBCs are able to specifically bind soluble fibrinogen, and identify membrane molecular targets that could be involved in this process. RBCs were first isolated from blood of healthy individuals and then separated in different age fractions by discontinuous Percoll gradients. After isolation RBC samples were incubated with human soluble fibrinogen and/or with a blocking antibody against CD47 followed by fluorescence confocal microscopy, flow cytometry acquisitions and zeta potential measurements. Our data show that soluble fibrinogen interacts with the human RBC membrane in an age-dependent manner, with younger RBCs interacting more with soluble fibrinogen than the older cells. Importantly, this interaction is abrogated in the presence of a specific antibody against CD47. Our results support a specific and age-dependent interaction of soluble fibrinogen with human RBC membrane; additionally we present CD47 as a putative mediator in this process. This interaction may contribute to RBC hyperaggregation in inflammation. Copyright © 2011 Elsevier B.V. All rights reserved.

Water-soluble metal working fluids additives derived from the esters of acid anhydrides with higher alcohols for aluminum alloy materials.

PubMed

Yamamoto, Syutaro; Tomoda, Hideyuki; Watanabe, Shoji

2007-01-01

Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short article describes properties of new additives in water-soluble metal working fluids for aluminum alloy materials. Many half esters or diesters were prepared from the reactions of higher alcohols with acid anhydrides. Interestingly, diesters of PTMG (tetrahydrofuran oligomer, MW = 650 and 1000) and polybutylene oxide (MW = 650) with maleic anhydride and succinic anhydride showed both of an excellent anti-corrosion property for aluminum alloy and a good hard water tolerance. The industrial soluble type processing oils including these additives also showed anti-corrosion property and hard water tolerance.

The infiltration-centrifugation technique for extraction of apoplastic fluid from plant leaves using Phaseolus vulgaris as an example.

PubMed

O'Leary, Brendan M; Rico, Arantza; McCraw, Sarah; Fones, Helen N; Preston, Gail M

2014-12-19

The apoplast is a distinct extracellular compartment in plant tissues that lies outside the plasma membrane and includes the cell wall. The apoplastic compartment of plant leaves is the site of several important biological processes, including cell wall formation, cellular nutrient and water uptake and export, plant-endophyte interactions and defence responses to pathogens. The infiltration-centrifugation method is well established as a robust technique for the analysis of the soluble apoplast composition of various plant species. The fluid obtained by this method is commonly known as apoplast washing fluid (AWF). The following protocol describes an optimized vacuum infiltration and centrifugation method for AWF extraction from Phaseolus vulgaris (French bean) cv. Tendergreen leaves. The limitations of this method and the optimization of the protocol for other plant species are discussed. Recovered AWF can be used in a wide range of downstream experiments that seek to characterize the composition of the apoplast and how it varies in response to plant species and genotype, plant development and environmental conditions, or to determine how microorganisms grow in apoplast fluid and respond to changes in its composition.

The Infiltration-centrifugation Technique for Extraction of Apoplastic Fluid from Plant Leaves Using Phaseolus vulgaris as an Example

PubMed Central

O'Leary, Brendan M.; Rico, Arantza; McCraw, Sarah; Fones, Helen N.; Preston, Gail M.

2014-01-01

The apoplast is a distinct extracellular compartment in plant tissues that lies outside the plasma membrane and includes the cell wall. The apoplastic compartment of plant leaves is the site of several important biological processes, including cell wall formation, cellular nutrient and water uptake and export, plant-endophyte interactions and defence responses to pathogens. The infiltration-centrifugation method is well established as a robust technique for the analysis of the soluble apoplast composition of various plant species. The fluid obtained by this method is commonly known as apoplast washing fluid (AWF). The following protocol describes an optimized vacuum infiltration and centrifugation method for AWF extraction from Phaseolus vulgaris (French bean) cv. Tendergreen leaves. The limitations of this method and the optimization of the protocol for other plant species are discussed. Recovered AWF can be used in a wide range of downstream experiments that seek to characterize the composition of the apoplast and how it varies in response to plant species and genotype, plant development and environmental conditions, or to determine how microorganisms grow in apoplast fluid and respond to changes in its composition. PMID:25549068

Characterization of a membrane-based, electrochemically driven pumping system using aqueous electrolyte solutions.

PubMed

Norman, Mya A; Evans, Christine E; Fuoco, Anthony R; Noble, Richard D; Koval, Carl A

2005-10-01

Electrokinetic flow provides a mechanism for a variety of fluid pumping schemes. The design and characterization of an electrochemically driven pump that utilizes porous carbon electrodes, iodide/triiodide redox electrolytes, and Nafion membranes is described. Fluid pumping by the cell is reversible and controlled by the cell current. Chronopotentiometry experiments indicate that the total available fluid that can be pumped in a single electrolysis without gas evolution is determined solely by the initial concentration of electrolyte and the applied current. The magnitude of the fluid flow at a given current is determined by the nature of the cation in the electrolyte and by the water absorption properties of the Nafion membrane. For 1 M aqueous electrolytes, pumping rates ranging from 1 to 14 microL/min were obtained for current densities of 10-30 mA/cm2 of membrane area. Molar volume changes for the I3-/I- redox couple and for the alkali cation migration contribute little to the observed volumetric flow rates; the magnitude of the flow is dominated by the migration-induced flow of water.

21 CFR 349.3 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... of acids or bases from such sources as drugs, body fluids, tears, etc. (d) Demulcent. An agent... membrane surfaces and relieve dryness and irritation. (e) Emollient. An agent, usually a fat or oil, which... present in body tissues and fluids, so that water is drawn from the body tissues and fluids across...

21 CFR 349.3 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... of acids or bases from such sources as drugs, body fluids, tears, etc. (d) Demulcent. An agent... membrane surfaces and relieve dryness and irritation. (e) Emollient. An agent, usually a fat or oil, which... present in body tissues and fluids, so that water is drawn from the body tissues and fluids across...

21 CFR 349.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... of acids or bases from such sources as drugs, body fluids, tears, etc. (d) Demulcent. An agent... membrane surfaces and relieve dryness and irritation. (e) Emollient. An agent, usually a fat or oil, which... present in body tissues and fluids, so that water is drawn from the body tissues and fluids across...

Solubility of Aragonite in Subduction Water-Rich Fluids

NASA Astrophysics Data System (ADS)

Daniel, I.; Facq, S.; Petitgirard, S.; Cardon, H.; Sverjensky, D. A.

2017-12-01

Carbonate dissolution in subduction zone fluids is critical to the carbon budget in subduction zones. Depending on the solubility of carbonate minerals in aqueous fluids, the subducting lithosphere may be either strongly depleted and the mantle metasomatized if the solubility is high, as recently suggested by natural samples or transport carbon deeper into the Earth's mantle if the solubility is low enough [1, 2]. Dissolution of carbonate minerals strongly depends on pressure and temperature as well as on the chemistry of the fluid, leading to a highly variable speciation of aqueous carbon. Thanks to recent advances in theoretical aqueous geochemistry [3, 4], combined experimental and theoretical efforts now allow the investigation of speciation and solubility of carbonate minerals in aqueous fluids at PT conditions higher than previously feasible [4, 5]. In this study, we present new in situ X-ray fluorescence measurements of aragonite dissolution up to 5 GPa and 500°C and the subsequent thermodynamic model of aragonite solubility in aqueous fluids thanks to the Deep Earth Water model. The amount of dissolved aragonite in the fluid was calculated from challenging and unprecedented measurements of the Ca fluorescence K-lines at low-energy. Experiments were performed at the ESRF, beamline ID27 using a dedicated design of an externally-heated diamond anvil cell and an incident high-flux and highly focused monochromatic X-Ray beam at 20 keV. The results show a spectacularly high solubility of aragonite at HP-HT in water, further enhanced in presence of NaCl and silica in the solution. [1] Frezzotti, M. L. et al. (2011) doi:10.1038/ngeo1246. [2] Ague, J. J. and Nicolescu, S. (2014) doi:10.1038/ngeo2143. [3] Pan, D. et al. (2013) doi: 10.1073/pnas.1221581110. [4] Sverjensky, D. A et al. (2014) doi: 10.1016/j.gca.2013.12.019. [5] Facq, S. et al. (2014) doi: 10.1016/j.gca.2014.01.030.

Single DNA molecules on freestanding and supported cationic lipid bilayers: diverse conformational dynamics controlled by the local bilayer properties

NASA Astrophysics Data System (ADS)

Herold, Christoph; Schwille, Petra; Petrov, Eugene P.

2016-02-01

We present experimental results on the interaction of DNA macromolecules with cationic lipid membranes with different properties, including freestanding membranes in the fluid and gel state, and supported lipid membranes in the fluid state and under conditions of fluid-gel phase coexistence. We observe diverse conformational dynamics of membrane-bound DNA molecules controlled by the local properties of the lipid bilayer. In case of fluid-state freestanding lipid membranes, the behaviour of DNA on the membrane is controlled by the membrane charge density: whereas DNA bound to weakly charged membranes predominantly behaves as a 2D random coil, an increase in the membrane charge density leads to membrane-driven irreversible DNA collapse and formation of subresolution-sized DNA globules. On the other hand, electrostatic binding of DNA macromolecules to gel-state freestanding membranes leads to completely arrested diffusion and conformational dynamics of membrane-adsorbed DNA. A drastically different picture is observed in case of DNA interaction with supported cationic lipid bilayers: When the supported bilayer is in the fluid state, membrane-bound DNA molecules undergo 2D translational Brownian motion and conformational fluctuations, irrespectively of the charge density of the supported bilayer. At the same time, when the supported cationic membrane shows fluid-gel phase coexistence, membrane-bound DNA molecules are strongly attracted to micrometre-sized gel-phase domains enriched with the cationic lipid, which results in 2D compaction of the membrane-bound macromolecules. This DNA compaction, however, is fully reversible, and disappears as soon as the membrane is heated above the fluid-gel coexistence. We also discuss possible biological implications of our experimental findings.

Retention of prominin in microvilli reveals distinct cholesterol-based lipid micro-domains in the apical plasma membrane.

PubMed

Röper, K; Corbeil, D; Huttner, W B

2000-09-01

Membrane cholesterol-sphingolipid 'rafts', which are characterized by their insolubility in the non-ionic detergent Triton X-100 in the cold, have been implicated in the sorting of certain membrane proteins, such as placental alkaline phosphatase (PLAP), to the apical plasma membrane domain of epithelial cells. Here we show that prominin, an apically sorted pentaspan membrane protein, becomes associated in the trans-Golgi network with a lipid raft that is soluble in Triton X-100 but insoluble in another non-ionic detergent, Lubrol WX. At the cell surface, prominin remains insoluble in Lubrol WX and is selectively associated with microvilli, being largely segregated from the membrane subdomains containing PLAP. Cholesterol depletion results in the loss of prominin's microvillus-specific localization but does not lead to its complete intermixing with PLAP. We propose the coexistence within a membrane domain, such as the apical plasma membrane, of different cholesterol-based lipid rafts, which underlie the generation and maintenance of membrane subdomains.

Dual Level Statistical Investigation of Equilibrium Solubility in Simulated Fasted and Fed Intestinal Fluid

PubMed Central

2017-01-01

The oral route is the preferred option for drug administration but contains the inherent issue of drug absorption from the gastro-intestinal tract (GIT) in order to elicit systemic activity. A prerequisite for absorption is drug dissolution, which is dependent upon drug solubility in the variable milieu of GIT fluid, with poorly soluble drugs presenting a formulation and biopharmaceutical challenge. Multiple factors within GIT fluid influence solubility ranging from pH to the concentration and ratio of amphiphilic substances, such as phospholipid, bile salt, monoglyceride, and cholesterol. To aid in vitro investigation simulated intestinal fluids (SIF) covering the fasted and fed state have been developed. SIF media is complex and statistical design of experiment (DoE) investigations have revealed the range of solubility values possible within each state due to physiological variability along with the media factors and factor interactions which influence solubility. However, these studies require large numbers of experiments (>60) and are not feasible or sensible within a drug development setting. In the current study a smaller dual level, reduced experimental number (20) DoE providing three arms covering the fasted and fed states along with a combined analysis has been investigated. The results indicate that this small scale investigation is feasible and provides solubility ranges that encompass published data in human and simulated fasted and fed fluids. The measured fasted and fed solubility ranges are in agreement with published large scale DoE results in around half of the cases, with the differences due to changes in media composition between studies. Indicating that drug specific behaviors are being determined and that careful media factor and concentration level selection is required in order to determine a physiologically relevant solubility range. The study also correctly identifies the major single factor or factors which influence solubility but it is evident that lower significance factors (for example bile salt) are not picked up due to the lower sample number employed. A similar issue is present with factor interactions with only a limited number available for study and generally not determined to have a significant solubility impact due to the lower statistical power of the study. The study indicates that a reduced experimental number DoE is feasible, will provide solubility range results with identification of major solubility factors however statistical limitations restrict the analysis. The approach therefore represents a useful initial screening tool that can guide further in depth analysis of a drug’s behavior in gastrointestinal fluids. PMID:29072917

Transport relaxation processes in supercritical fluids

NASA Astrophysics Data System (ADS)

Jonas, J.

The technique for solubility measurements of solids in compressed supercritical fluids using NMR and theoretical analysis of experimental data on collision induced scattering were examined. Initial tests for a determination of solid solubilities in supercritical fluids without mixing were previously described and these preparations have continued. Super critical carbon dioxide dissolving naphthalene, for which solubility data is already available (M. McHugh, M.E. Paulaitis, J. Chem. Eng. Data, Vol. 25 (4), 1980) is being studied. This initial testing of the NMR technique for measuring solubilities in a well characterized system should prove very valuable for our later determinations with the proposed mixing probe. Systematic experimental studies of collision induced spectra in several supercritical fluids using both Raman and Rayleigh scattering are continued. The experimental work on SF6 and CH4 was finished and the experimental data testing of the various theoretical models for collision induced scattering is being analyzed.

Comparison of sVCAM-1 and sICAM-1 levels in maternal serum and vaginal secretion between pregnant women with preterm prelabour ruptures of membranes and healthy pregnant women.

PubMed

Sak, Sibel; Barut, Mert; Incebiyik, Adnan; Ağaçayak, Elif; Kirmit, Adnan; Koyuncu, Ismail; Sak, Muhammet

2017-11-02

The study aims to evaluate the maternal serum and the vaginal fluid levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble intercellular adhesion molecular (sICAM-1) in pregnant women complicated by preterm prelabour ruptures of membranes (PPROM). The prospective case control study included 34 pregnant women with PPROM and 34 healthy pregnant women. Patients with additional diseases, a smoking habit and vaginal bleeding, as well as those using antibiotics, during the study period were not included in the study. Cervicovaginal fluid and serum samples were taken during the patients' admission. The demographic data, maternal serum and vaginal fluid sVCAM-1 and sICAM-1, C reactive protein (CRP) and leukocyte counts were noted for all pregnant women included in the study. The sVCAM-1 and sICAM-1 levels were measured by enzyme-linked immunosorbent assay kits. In pregnant women with PPROM, the serum leukocyte (mean ± SD =11.41 ± 1.067 versus 9.18 ± 1.56, p < .0001), serum sVCAM-1 (median 771.20 versus 704.60 ng/ml, p < .001), sICAM-1 (mean ± SD 213.10 ± 35.59 ng/ml versus 188.11 ± 37.35 ng/ml, p = .06), vaginal sVCAM-1 (median 208.00 versus 140.20 ng/ml, p = .014) and sICAM-1 (mean ± SD 32.32 ± 6.49 ng/ml versus 24.87 ± 6.79 ng/ml, p < .001) values were found to be significantly higher in pregnant women with PPROM than in healthy pregnant women. A positive and significant correlation was observed between the leukocyte count and the vaginal sVCAM-1 level (r = 0.850; p < .001). To the best of our knowledge, this is the first study evaluating the levels of sICAM-1 in maternal serum in pregnant women with PPROM. The maternal serum and vaginal fluid sVCAM-1 and sICAM-1 levels can be used as biochemical markers supporting the PPROM diagnosis because of the increase in both maternal serum and vaginal fluid sVCAM-1 and sICAM-1 levels in pregnant women with PPROM.

Influence of type and level of water-soluble additives on drug release and surface and mechanical properties of Surelease films.

PubMed

Rohera, Bhagwan D; Parikh, Nilesh H

2002-11-01

Ethylcellulose in combination with water-soluble additives has been used in the development of microporous membrane-coated dosage forms. In the present study, application of three types of water-soluble additives, namely polyethylene glycols (PEG 400, 3350, and 8000), maltodextrins (Maltrin M150, M100, and M040 in the order of lower to higher average polymer size and molecular weight; dextrose equivalence 16.9, 11.1, and 4.8, respectively), and xylitol, as porosity modifiers in the films of a commercially available aqueous ethylcellulose dispersion (Surelease/E-7-7060 plasticized with glyceryl tricaprylate/caprate) was investigated. The effect of type and level of these additives on drug release characteristics and surface and mechanical properties of the polymeric films was studied. Each additive was incorporated at 20 and 30% levels in the polymeric dispersion based on its solids content. Ibuprofen tablets were coated using the polymeric dispersion with and without additive at 3% w/w coat level in a fluid-bed equipment. The coated tablets were evaluated for their drug release rate, coat reflectivity (gloss), Brinell hardness, and elastic modulus. Differential scanning calorimetric analysis of the films was performed to determine the physico-chemical changes in the applied film-coats. The rate of drug release, hence film porosity, was observed to be dependent on the type and level of the additive added. The molecular weight of the additive and its concentration in the polymeric dispersion had significant influence on the rate of drug release, hardness, and elasticity of the film-coats.

Characterization of the association of nitrate reductase with barley (Hordeum vulgare L.) root membranes

NASA Technical Reports Server (NTRS)

Meyerhoff, P. A.; Fox, T. C.; Travis, R. L.; Huffaker, R. C.

1994-01-01

The nature of the association between nitrate reductase (NR) and membranes was examined. Nitrate reductase activity (NRA) associated with the microsomal fraction of barley (Hordeum vulgare L.) roots amounted to 0.6 to 0.8% of soluble NRA following sonication in the presence of 250 mM KI and repeated osmotic shock. This treatment removed all contaminating soluble NRA from microsomes of uninduced barley roots that had been homogenized in a soluble extract from roots of NO3(-)-induced plants. On continuous sucrose gradients, NRA co-migrated specifically with VO4(-)-sensitive ATPase activity, a plasma membrane (PM) marker; activity of glucose-6-phosphate dehydrogenase, assayed as cytosolic marker, co-migrated with NRA. Microsomal NRA was absent in barley deficient in soluble NR. Perturbation and trypsinolysis experiments with PM vesicles isolated by aqueous two-phase partitioning indicated that NR is associated with the periphery of the cytoplasmic face of the bilayer. These results demonstrate that PM and soluble NRs are essentially the same protein but that the membrane-associated form is tightly bound. Although it is possible that PM-associated NR exists in vivo, unequivocal evidence for this has yet to be shown. However, PM NR is definitely present in vitro.

Applications of the second virial coefficient: protein crystallization and solubility

PubMed Central

Wilson, William W.; DeLucas, Lawrence J.

2014-01-01

This article begins by highlighting some of the ground-based studies emanating from NASA’s Microgravity Protein Crystal Growth (PCG) program. This is followed by a more detailed discussion of the history of and the progress made in one of the NASA-funded PCG investigations involving the use of measured second virial coefficients (B values) as a diagnostic indicator of solution conditions conducive to protein crystallization. A second application of measured B values involves the determination of solution conditions that improve or maximize the solubility of aqueous and membrane proteins. These two important applications have led to several technological improvements that simplify the experimental expertise required, enable the measurement of membrane proteins and improve the diagnostic capability and measurement throughput. PMID:24817708

Hormone purification by isoelectric focusing in space

NASA Technical Reports Server (NTRS)

Bier, M.

1988-01-01

The objective of the program was the definition and development of optimal methods for electrophoretic separations in microgravity. The approach is based on a triad consisting of ground based experiments, mathematical modeling and experiments in microgravity. Zone electrophoresis is a rate process, where separation is achieved in uniform buffers on the basis of differences in electrophoretic mobilities. Optimization and modeling of continuous flow electrophoresis mainly concern the hydrodynamics of the flow process, including gravity dependent fluid convection due to density gradients and gravity independent electroosmosis. Optimization of focusing requires a more complex model describing the molecular transport processes involved in electrophoresis of interacting systems. Three different focusing instruments were designed, embodying novel principles of fluid stabilization. Fluid stability was achieved by: (1) flow streamlining by means of membrane elements in combination with rapid fluid recycling; (2) apparatus rotation in combination with said membrane elements; and (3) shear stress induced by rapid recycling through a narrow gap channel.

Evaporative Cooling Membrane Device

NASA Technical Reports Server (NTRS)

Lomax, Curtis (Inventor); Moskito, John (Inventor)

1999-01-01

An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

Prostate cancer incidence in relation to time windows of exposure to metalworking fluids in the auto industry.

PubMed

Agalliu, Ilir; Kriebel, David; Quinn, Margaret M; Wegman, David H; Eisen, Ellen A

2005-09-01

Exposure to metalworking fluids has been previously associated with prostate cancer mortality in a cohort of autoworkers. Our objective was to further explore this finding in a study of prostate cancer incidence in the same cohort, with reduced misclassification of outcome. We conducted a nested case-control study in the General Motors cohort of autoworkers. Incident cases of prostate cancer (n = 872) were identified via the Michigan Cancer Registry from 1985 through 2000. Controls were selected using incidence-density sampling with 5:1 ratio. Using cumulative exposure (mg/m-years) as the dose metric, we first examined varying lengths of lags (0-25 years). Then, we evaluated consecutive windows of exposure: 25 or more years before risk age, and fewer than 25 years. We used penalized splines to model the relative risk as a smooth function of exposure, and adjusted for race and calendar year of diagnosis in a Cox model. Risk of prostate cancer increased with exposure to soluble and straight fluids 25 years or more before risk age but not with exposure in the last 25 years. The relationship with soluble fluids was piecewise linear, with a small increase in risk at lower exposures followed by a steeper rise. By contrast, the relationship with straight fluids was linear, with a relative risk of 1.12 per 10mg/m-years of exposure (95% confidence interval = 1.04-1.20). Exposure to oil-based fluids, soluble and straight, is modestly associated with prostate cancer risk among autoworkers, with a latency period of at least 25 years.

Carbon Dioxide: The Other Planetary Fluid

NASA Astrophysics Data System (ADS)

Glaser, S.; Gamez, D.; Shock, E.

2016-12-01

Cometary and interstellar ices have carbon dioxide to water mole ratios of up to 0.3. When melted, such high levels of carbon dioxide cannot all be dissolved in the aqueous phase and instead partition into a CO2-rich (carbonic) fluid. This implies that during the accretion and formation of planetary systems carbonic fluids are not only possible, but common. In fact, they make up the atmosphere of Venus, are found bubbling out of Champagne Vent in the Pacific Ocean, and are documented by metamorphic fluid inclusions. Examination of phase diagrams reveals the conditions where carbonic fluids will exist or predominate. Carbonic fluids are predicted to exist in Earth's subduction zones and under the ice of small ocean worlds. CO2 had previously been shown to completely dissolve into NH­­3­-H­­2O oceans on small icy bodies by forming ammonium carbonate, but the newer measurements of CO2­ abundances indicate that not all of the CO2 can partition into the aqueous fluid as ammonium carbonate. The remaining CO2 would necessarily form a separate carbonic fluid making it likely that liquid CO2 would be a major oceanic component on some small icy bodies. The enhanced solubility of nonpolar and slightly polar organic compounds in carbonic fluids relative to aqueous fluids means that generation, transport, and deposition processes can be greatly enhanced in those cases where carbonic fluids occur. As an example, the solubility of benzoic acid, a polar compound, is about an order of magnitude greater in carbonic than in aqueous fluids, which is surprising given that water is a polar solvent and carbon dioxide is a nonpolar solvent. Anthracene, a nonpolar compound, has an even greater solubility difference between carbonic and aqueous fluids at approximately four orders of magnitude. Highly polar compounds, including most of the building blocks of life, are more soluble in aqueous fluids than in carbonic fluids. The solubility difference of organic molecules in carbonic fluids relative to aqueous fluids determines the distribution of the building blocks of life in planetary systems. Partitioning of organics into a carbonic fluid may be the mechanism of removing biochemically irrelevant molecules from the aqueous phase and enabling the emergence of life.

Cleaning a semipermeable membrane in a papermaking machine

DOEpatents

Beck, David A.

2004-01-06

A method of cleaning a semipermeable membrane, the semipermeable membrane being configured for carrying a fiber web, includes the steps of providing a cleaning fluid and applying the cleaning fluid on the semipermeable membrane. Further, an air press configured for carrying the semipermeable membrane therethrough is provided, and the air press has pressurized air therein. The semipermeable membrane is conveyed through the air press and is subjected to the pressurized air within the air press. The pressurized air thereby flushes the cleaning fluid through the semipermeable membrane.

Soluble Megalin is Reduced in Cerebrospinal Fluid Samples of Alzheimer's Disease Patients.

PubMed

Spuch, Carlos; Antequera, Desireé; Pascual, Consuelo; Abilleira, Soledad; Blanco, María; Moreno-Carretero, María José; Romero-López, Jesús; Ishida, Tetsuya; Molina, Jose Antonio; Villarejo, Alberto; Bermejo-Pareja, Felix; Carro, Eva

2015-01-01

Megalin or low-density lipoprotein receptor-related protein-2 is a member of the low-density lipoprotein receptor family, which has been linked to Alzheimer's disease (AD) by clearing brain amyloid β-peptide (Aβ) across the blood-cerebrospinal fluid barrier at the choroid plexus. Here, we found a soluble form of megalin secreted from choroid plexus epithelial cells. Soluble megalin levels were also localized in the human cerebrospinal fluid (CSF), being reduced in AD patients. We have also shown that soluble megalin binding to Aβ is decreased in the CSF of AD patients, suggesting that decreased sequestration of Aβ in the CSF could be associated with defective clearance of Aβ and an increase of brain Aβ levels. Thus, therapies, which increase megalin expression, at the choroid plexus and/or enhance circulating soluble megalin hold potential to control brain Aβ-related pathologies in AD.

Soluble Megalin is Reduced in Cerebrospinal Fluid Samples of Alzheimer’s Disease Patients

PubMed Central

Spuch, Carlos; Antequera, Desireé; Pascual, Consuelo; Abilleira, Soledad; Blanco, María; Moreno-Carretero, María José; Romero-López, Jesús; Ishida, Tetsuya; Molina, Jose Antonio; Villarejo, Alberto; Bermejo-Pareja, Felix; Carro, Eva

2015-01-01

Megalin or low-density lipoprotein receptor-related protein-2 is a member of the low-density lipoprotein receptor family, which has been linked to Alzheimer’s disease (AD) by clearing brain amyloid β-peptide (Aβ) across the blood–cerebrospinal fluid barrier at the choroid plexus. Here, we found a soluble form of megalin secreted from choroid plexus epithelial cells. Soluble megalin levels were also localized in the human cerebrospinal fluid (CSF), being reduced in AD patients. We have also shown that soluble megalin binding to Aβ is decreased in the CSF of AD patients, suggesting that decreased sequestration of Aβ in the CSF could be associated with defective clearance of Aβ and an increase of brain Aβ levels. Thus, therapies, which increase megalin expression, at the choroid plexus and/or enhance circulating soluble megalin hold potential to control brain Aβ-related pathologies in AD. PMID:25926771

Solubility of 238U radionuclide from various types of soil in synthetic gastrointestinal fluids using "US in vitro" digestion method

NASA Astrophysics Data System (ADS)

Rashid, Nur Shahidah Abdul; Sarmani, Sukiman; Majid, Amran Ab.; Mohamed, Faizal; Siong, Khoo Kok

2015-04-01

238U radionuclide is a naturally occuring radioactive material that can be found in soil. In this study, the solubility of 238U radionuclide obtained from various types of soil in synthetic gastrointestinal fluids was analysed by "US P in vitro" digestion method. The synthetic gastrointestinal fluids were added to the samples with well-ordered, mixed throughly and incubated according to the human physiology digestive system. The concentration of 238U radionuclide in the solutions extracted from the soil was measured using Induced Coupling Plasma Mass Spectrometer (ICP-MS). The concentration of 238U radionuclide from the soil samples in synthetic gastrointestinal fluids showed different values due to different homogenity of soil types and chemical reaction of 238U radionuclide. In general, the solubility of 238U radionuclide in gastric fluid was higher (0.050 - 0.209 ppm) than gastrointestinal fluids (0.024 - 0.050 ppm). It could be concluded that the US P in vitro digestion method is practicle for estimating the solubility of 238U radionuclide from soil materials and could be useful for monitoring and risk assessment purposes applying to environmental, health and contaminated soil samples.

Bipolar membranes with fluid distribution passages

NASA Technical Reports Server (NTRS)

Hitchens, G. Duncan (Inventor); Archer, Shivaun (Inventor); Tennakoon, Charles L. (Inventor); Gonzalez-Martin, Anuncia (Inventor); Cisar, Alan J. (Inventor)

1999-01-01

The present invention provides a bipolar membrane and methods for making and using the membrane. The bipolar membrane comprises a cation-selective region, an anion-selective region, an interfacial region between the anion-selective region and the cation-selective region, and means for delivering fluid directly into the interfacial region. The means for delivering fluid includes passages that may comprise a fluid-permeable material, a wicking material, an open passage disposed within the membrane or some combination thereof. The passages may be provided in many shapes, sizes and configurations, but preferably deliver fluid directly to the interfacial region so that the rate of electrodialysis is no longer limited by the diffusion of fluid through the cation- or anion-selective regions to the interfacial region.

Differential distribution of proteins and lipids in detergent-resistant and detergent-soluble domains in rod outer segment plasma membranes and disks.

PubMed

Elliott, Michael H; Nash, Zack A; Takemori, Nobuaki; Fliesler, Steven J; McClellan, Mark E; Naash, Muna I

2008-01-01

Membrane heterogeneity plays a significant role in regulating signal transduction and other cellular activities. We examined the protein and lipid components associated with the detergent-resistant membrane (DRM) fractions from retinal rod outer segment (ROS) disk and plasma membrane-enriched preparations. Proteomics and correlative western blot analysis revealed the presence of alpha and beta subunits of the rod cGMP-gated ion channel and glucose transporter type 1, among other proteins. The glucose transporter was present exclusively in ROS plasma membrane (not disks) and was highly enriched in DRMs, as was the cGMP-gated channel beta-subunit. In contrast, the majority of rod opsin and ATP-binding cassette transporter A4 was localized to detergent-soluble domains in disks. As expected, the cholesterol : fatty acid mole ratio was higher in DRMs than in the corresponding parent membranes (disk and plasma membranes, respectively) and was also higher in disks compared to plasma membranes. Furthermore, the ratio of saturated : polyunsaturated fatty acids was also higher in DRMs compared to their respective parent membranes (disk and plasma membranes). These results confirm that DRMs prepared from both disks and plasma membranes are enriched in cholesterol and in saturated fatty acids compared to their parent membranes. The dominant fatty acids in DRMs were 16 : 0 and 18 : 0; 22 : 6n3 and 18 : 1 levels were threefold higher and twofold lower, respectively, in disk-derived DRMs compared to plasma membrane-derived DRMs. We estimate, based on fatty acid recovery that DRMs account for only approximately 8% of disks and approximately 12% of ROS plasma membrane.

A Multi-Phase Based Fluid-Structure-Microfluidic interaction sensor for Aerodynamic Shear Stress

NASA Astrophysics Data System (ADS)

Hughes, Christopher; Dutta, Diganta; Bashirzadeh, Yashar; Ahmed, Kareem; Qian, Shizhi

2014-11-01

A novel innovative microfluidic shear stress sensor is developed for measuring shear stress through multi-phase fluid-structure-microfluidic interaction. The device is composed of a microfluidic cavity filled with an electrolyte liquid. Inside the cavity, two electrodes make electrochemical velocimetry measurements of the induced convection. The cavity is sealed with a flexible superhydrophobic membrane. The membrane will dynamically stretch and flex as a result of direct shear cross-flow interaction with the seal structure, forming instability wave modes and inducing fluid motion within the microfluidic cavity. The shear stress on the membrane is measured by sensing the induced convection generated by membrane deflections. The advantages of the sensor over current MEMS based shear stress sensor technology are: a simplified design with no moving parts, optimum relationship between size and sensitivity, no gaps such as those created by micromachining sensors in MEMS processes. We present the findings of a feasibility study of the proposed sensor including wind-tunnel tests, microPIV measurements, electrochemical velocimetry, and simulation data results. The study investigates the sensor in the supersonic and subsonic flow regimes. Supported by a NASA SBIR phase 1 contract.

Separator for alkaline electric batteries and method of making

NASA Technical Reports Server (NTRS)

Pfluger, H. L. (Inventor); Hoyt, H. E.

1970-01-01

Battery separator membranes of high electrolytic conductivity comprising a cellulose ether and a compatible metallic salt of water soluble aliphatic acids and their hydroxy derivatives are described. It was found that methyl cellulose can be modified by another class of materials, nonpolymeric in nature, to form battery separator membranes of low electrolytic resistance but which have the flexibility of membranes made of unmodified methyl cellulose, and which in many cases enhance flexibility over membranes made with unmodified methyl cellulose. Separator membranes for electrochemical cells comprising a cellulose ether and a modified selected from the group consisting of metallic salts of water soluble alphatic acids and their hydroxy derivatives and to electrochemical cells utilizing said membranes are described.

High quality NMR structures: a new force field with implicit water and membrane solvation for Xplor-NIH.

PubMed

Tian, Ye; Schwieters, Charles D; Opella, Stanley J; Marassi, Francesca M

2017-01-01

Structure determination of proteins by NMR is unique in its ability to measure restraints, very accurately, in environments and under conditions that closely mimic those encountered in vivo. For example, advances in solid-state NMR methods enable structure determination of membrane proteins in detergent-free lipid bilayers, and of large soluble proteins prepared by sedimentation, while parallel advances in solution NMR methods and optimization of detergent-free lipid nanodiscs are rapidly pushing the envelope of the size limit for both soluble and membrane proteins. These experimental advantages, however, are partially squandered during structure calculation, because the commonly used force fields are purely repulsive and neglect solvation, Van der Waals forces and electrostatic energy. Here we describe a new force field, and updated energy functions, for protein structure calculations with EEFx implicit solvation, electrostatics, and Van der Waals Lennard-Jones forces, in the widely used program Xplor-NIH. The new force field is based primarily on CHARMM22, facilitating calculations with a wider range of biomolecules. The new EEFx energy function has been rewritten to enable OpenMP parallelism, and optimized to enhance computation efficiency. It implements solvation, electrostatics, and Van der Waals energy terms together, thus ensuring more consistent and efficient computation of the complete nonbonded energy lists. Updates in the related python module allow detailed analysis of the interaction energies and associated parameters. The new force field and energy function work with both soluble proteins and membrane proteins, including those with cofactors or engineered tags, and are very effective in situations where there are sparse experimental restraints. Results obtained for NMR-restrained calculations with a set of five soluble proteins and five membrane proteins show that structures calculated with EEFx have significant improvements in accuracy, precision, and conformation, and that structure refinement can be obtained by short relaxation with EEFx to obtain improvements in these key metrics. These developments broaden the range of biomolecular structures that can be calculated with high fidelity from NMR restraints.

Instabilities and diffusion in a hydrodynamic model of a fluid membrane coupled to a thin active fluid layer.

PubMed

Sarkar, N; Basu, A

2012-11-01

We construct a coarse-grained effective two-dimensional (2d hydrodynamic theory as a theoretical model for a coupled system of a fluid membrane and a thin layer of a polar active fluid in its ordered state that is anchored to the membrane. We show that such a system is prone to generic instabilities through the interplay of nonequilibrium drive, polar order and membrane fluctuation. We use our model equations to calculate diffusion coefficients of an inclusion in the membrane and show that their values depend strongly on the system size, in contrast to their equilibrium values. Our work extends the work of S. Sankararaman and S. Ramaswamy (Phys. Rev. Lett., 102, 118107 (2009)) to a coupled system of a fluid membrane and an ordered active fluid layer. Our model is broadly inspired by and should be useful as a starting point for theoretical descriptions of the coupled dynamics of a cell membrane and a cortical actin layer anchored to it.

Method of separating organic contaminants from fluid feedstreams with polyphosphazene membranes

DOEpatents

McCaffrey, Robert R.; Cummings, Daniel G.

1991-01-01

A method is provided for separating halogenated hydrocarbons from a fluid feedstream. The fluid feedstream is flowed across a first surface of a polyphosphazene semipermeable membrane. At least one halogenated hydrocarbon from the fluid feedstream permeates through the polyphosphazene semipermeable membrane to a second opposed surface of the semipermeable membrane. Then the permeated polar hydrocarbon is removed from the second opposed surface of the polyphosphazene semipermeable membrane. Outstanding and unexpected separation selectivities on the order of 10,000 were obtained for methylene chloride when a methylene chloride in water feedstream was flowed across the polyphosphazene semipermeable membrane in the invented method.

Flow over a membrane-covered, fluid-filled cavity.

PubMed

Thomson, Scott L; Mongeau, Luc; Frankel, Steven H

2007-01-01

The flow-induced response of a membrane covering a fluid-filled cavity located in a section of a rigid-walled channel was explored using finite element analysis. The membrane was initially aligned with the channel wall and separated the channel fluid from the cavity fluid. As fluid flowed over the membrane-covered cavity, a streamwise-dependent transmural pressure gradient caused membrane deformation. This model has application to synthetic models of the vocal fold cover layer used in voice production research. In this paper, the model is introduced and responses of the channel flow, the membrane, and the cavity flow are summarized for a range of flow and membrane parameters. It is shown that for high values of cavity fluid viscosity, the intracavity pressure and the beam deflection both reached steady values. For combinations of low cavity viscosity and sufficiently large upstream pressures, large-amplitude membrane vibrations resulted. Asymmetric conditions were introduced by creating cavities on opposing sides of the channel and assigning different stiffness values to the two membranes. The asymmetry resulted in reduction in or cessation of vibration amplitude, depending on the degree of asymmetry, and in significant skewing of the downstream flow field.

Comparison of nickel release in solutions used for the identification of water-soluble nickel exposures and in synthetic lung fluids.

PubMed

Oller, Adriana R; Cappellini, Danielle; Henderson, Rayetta G; Bates, Hudson K

2009-04-01

Chemical speciation of workplace nickel exposures is critical because nickel-containing substances often differ in toxicological properties. Exposure matrices based on leaching methods have been used to ascertain which chemical forms of nickel are primarily associated with adverse respiratory effects after inhalation. Misjudgments in the relative proportion of each of the main fractions of nickel in workplace exposures could translate into possible misattributions of risk to the various forms of nickel. This preliminary study looked at the efficiency of the first step of the Zatka leaching method for accurately assessing the 'water-soluble' fraction of several substances present in nickel production operations, compared to leaching in synthetic lung fluid. The present results demonstrate that for nickel sulfate or chloride, the current Zatka solution is adequate to assess the 'water-soluble' fraction. However, when sparingly water-soluble compounds like nickel carbonates or water-insoluble substances like nickel subsulfide and fine metallic nickel powders are present, the first step of the Zatka method can greatly over estimate the amount of nickel that could be released in pure water. In contrast, the releases of nickel from nickel carbonate, nickel subsulfide, and nickel metal powders in pure water are consistent with their releases in synthetic lung fluid, indicating that deionized water is a better leaching solution to estimate the biologically relevant 'water-soluble' nickel fraction of workplace exposures. Exposure matrices relying mostly on the Zatka speciation method to estimate the main forms of nickel need to be re-evaluated to account for any possible misattributions of risk.

Choline- versus imidazole-based ionic liquids as functional ingredients in topical delivery systems: cytotoxicity, solubility, and skin permeation studies.

PubMed

Santos de Almeida, Tânia; Júlio, Ana; Saraiva, Nuno; Fernandes, Ana Sofia; Araújo, Maria Eduarda M; Baby, André Rolim; Rosado, Catarina; Mota, Joana Portugal

2017-11-01

Poor drug solubility represents a problem for the development of topical formulations. Since ionic liquids (ILs) can be placed in either lipophilic or hydrophilic solutions, they may be advantageous vehicles in such delivery systems. Nonetheless, it is vital to determine their usefulness when used at concentrations were cell viability is maintained, which was considered herein. Five different ILs were prepared-three imidazole-based ILs: [C2mim][Br], [C4mim][Br], and [C6mim][Br]; and two choline-based ILs: [Cho][Phe] and [Cho][Glu]. Their cytotoxicity in human keratinocytes (HaCat cells), their influence in drug solubility and in percutaneous permeation, using pig skin membranes, was evaluated. Caffeine and salicylic acid were used as model actives. Choline-based ILs proved to be more suitable as functional ingredients, since they showed higher impact on drug solubility and a lower cytotoxicity. The major solubility enhancement was observed for caffeine and further solubility studies were carried out with this active in several concentrations of the choline-based ILs (0.1; 0.2; 0.5; 1.0; 3.0 and 5.0%, w/w) at 25 °C and 32 °C. Solubility was greatly influenced by concentrations up to 0.5%. The choline-based ILs showed no significant impact on the skin permeation, for both actives. The size of the imidazole-based ILs alkyl chain enhances the caffeine solubility and permeation, but also the ILs cytotoxicity. Stable O/W emulsions and gels were prepared containing the less toxic choline-based ILs and caffeine. Our results indicate that the choline-based ILs were effective functional ingredients, since, when used at nontoxic concentrations, they allowed a higher drug loading, while maintaining the stability of the formulations.

Membrane-spanning α-helical barrels as tractable protein-design targets.

PubMed

Niitsu, Ai; Heal, Jack W; Fauland, Kerstin; Thomson, Andrew R; Woolfson, Derek N

2017-08-05

The rational ( de novo ) design of membrane-spanning proteins lags behind that for water-soluble globular proteins. This is due to gaps in our knowledge of membrane-protein structure, and experimental difficulties in studying such proteins compared to water-soluble counterparts. One limiting factor is the small number of experimentally determined three-dimensional structures for transmembrane proteins. By contrast, many tens of thousands of globular protein structures provide a rich source of 'scaffolds' for protein design, and the means to garner sequence-to-structure relationships to guide the design process. The α-helical coiled coil is a protein-structure element found in both globular and membrane proteins, where it cements a variety of helix-helix interactions and helical bundles. Our deep understanding of coiled coils has enabled a large number of successful de novo designs. For one class, the α-helical barrels-that is, symmetric bundles of five or more helices with central accessible channels-there are both water-soluble and membrane-spanning examples. Recent computational designs of water-soluble α-helical barrels with five to seven helices have advanced the design field considerably. Here we identify and classify analogous and more complicated membrane-spanning α-helical barrels from the Protein Data Bank. These provide tantalizing but tractable targets for protein engineering and de novo protein design.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'. © 2017 The Author(s).

Passive Membrane Permeability: Beyond the Standard Solubility-Diffusion Model.

PubMed

Parisio, Giulia; Stocchero, Matteo; Ferrarini, Alberta

2013-12-10

The spontaneous diffusion of solutes through lipid bilayers is still a challenge for theoretical predictions. Since permeation processes remain beyond the capabilities of unbiased molecular dynamics simulations, an alternative strategy is currently adopted to gain insight into their mechanism and time scale. This is based on a monodimensional description of the translocation process only in terms of the position of the solute along the normal to the lipid bilayer, which is formally expressed in the solubility-diffusion model. Actually, a role of orientational and conformational motions has been pointed out, and the use of advanced simulation techniques has been proposed to take into account their effect. Here, we discuss the limitations of the standard solubility-diffusion approach and propose a more general description of membrane translocation as a diffusion process on a free energy surface, which is a function of the translational and rotational degrees of freedom of the molecule. Simple expressions for the permeability coefficient are obtained under suitable conditions. For fast solute reorientation, the classical solubility-diffusion equation is recovered. Under the assumption that well-defined minima can be identified on the free energy landscape, a mechanistic interpretation of the permeability coefficient in terms of all possible permeation paths is given.

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

PubMed

Keeler, Geoffrey D; Durdik, Jeannine M; Stenken, Julie A

2014-06-16

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration. While these perfusion fluid additives are commonly used during microdialysis sampling, the tissue response to the loss of these compounds across the membrane is poorly understood. Tissue reactions to implanted microdialysis sampling probes containing different microdialysis perfusion fluids were compared over a 7-day time period in rats. The base perfusion fluid was Ringer's solution supplemented with either bovine serum albumin (BSA), rat serum albumin (RSA), Dextran-70, or Dextran-500. A significant inflammatory response to Dextran-70 was observed. No differences in the tissue response between BSA and RSA were observed. Among these agents, the BSA, RSA, and Dextran-500 produced a significantly reduced inflammatory response compared to the Dextran-70. This work demonstrates that use of Dextran-70 in microdialysis sampling perfusion fluids should be eliminated and replaced with Dextran-500 or other alternatives. Copyright © 2013 Elsevier B.V. All rights reserved.

Water-soluble polymers bearing phosphorylcholine group and other zwitterionic groups for carrying DNA derivatives.

PubMed

Lin, Xiaojie; Ishihara, Kazuhiko

2014-01-01

Water-soluble polymers with equal positive and negative charges in the same monomer unit, such as the phosphorylcholine group and other zwitterionic groups, exhibit promising potential in gene delivery with appreciable transfection efficiency, compared with the traditional poly(ethylene glycol)-based polycation-gene complexes. These zwitterionic polymers with various architectural structures and properties have been synthesized by various polymerization methods, such as conventional radical polymerization, atom-transfer radical-polymerization, reversible addition-fragmentation chain-transfer polymerization, and nitroxide-mediated radical polymerization. These techniques have been used to efficiently facilitate gene therapy by fabrication of non-viral vectors with high cytocompatibility, large gene-carrying capacity, effective cell-membrane permeability, and in vivo gene-loading/releasing functionality. Zwitterionic polymer-based gene delivery vectors systems can be categorized into soluble-polymer/gene mixing, molecular self-assembly, and polymer-gene conjugation systems. This review describes the preparation and characterization of various zwitterionic polymer-based gene delivery vectors, specifically water-soluble phospholipid polymers for carrying gene derivatives.

Silica-coated flexible liposomes as a nanohybrid delivery system for enhanced oral bioavailability of curcumin

PubMed Central

Li, Chong; Zhang, Yan; Su, Tingting; Feng, Lianlian; Long, Yingying; Chen, Zhangbao

2012-01-01

We investigated flexible liposomes as a potential oral drug delivery system. However, enhanced membrane fluidity and structural deformability may necessitate liposomal surface modification when facing the harsh environment of the gastrointestinal tract. In the present study, silica-coated flexible liposomes loaded with curcumin (CUR-SLs) having poor water solubility as a model drug were prepared by a thin-film method with homogenization, followed by the formation of a silica shell by the sol-gel process. We systematically investigated the physical properties, drug release behavior, pharmacodynamics, and bioavailability of CUR-SLs. CUR-SLs had a mean diameter of 157 nm and a polydispersity index of 0.14, while the apparent entrapment efficiency was 90.62%. Compared with curcumin-loaded flexible liposomes (CUR-FLs) without silica-coatings, CUR-SLs had significantly higher stability against artificial gastric fluid and showed more sustained drug release in artificial intestinal fluid as determined by in vitro release assays. The bioavailability of CUR-SLs and CUR-FLs was 7.76- and 2.35-fold higher, respectively, than that of curcumin suspensions. Silica coating markedly improved the stability of flexible liposomes, and CUR-SLs exhibited a 3.31-fold increase in bioavailability compared with CUR-FLs, indicating that silica-coated flexible liposomes may be employed as a potential carrier to deliver drugs with poor water solubility via the oral route with improved bioavailability. PMID:23233804

Silica-coated flexible liposomes as a nanohybrid delivery system for enhanced oral bioavailability of curcumin.

PubMed

Li, Chong; Zhang, Yan; Su, Tingting; Feng, Lianlian; Long, Yingying; Chen, Zhangbao

2012-01-01

We investigated flexible liposomes as a potential oral drug delivery system. However, enhanced membrane fluidity and structural deformability may necessitate liposomal surface modification when facing the harsh environment of the gastrointestinal tract. In the present study, silica-coated flexible liposomes loaded with curcumin (CUR-SLs) having poor water solubility as a model drug were prepared by a thin-film method with homogenization, followed by the formation of a silica shell by the sol-gel process. We systematically investigated the physical properties, drug release behavior, pharmacodynamics, and bioavailability of CUR-SLs. CUR-SLs had a mean diameter of 157 nm and a polydispersity index of 0.14, while the apparent entrapment efficiency was 90.62%. Compared with curcumin-loaded flexible liposomes (CUR-FLs) without silica-coatings, CUR-SLs had significantly higher stability against artificial gastric fluid and showed more sustained drug release in artificial intestinal fluid as determined by in vitro release assays. The bioavailability of CUR-SLs and CUR-FLs was 7.76- and 2.35-fold higher, respectively, than that of curcumin suspensions. Silica coating markedly improved the stability of flexible liposomes, and CUR-SLs exhibited a 3.31-fold increase in bioavailability compared with CUR-FLs, indicating that silica-coated flexible liposomes may be employed as a potential carrier to deliver drugs with poor water solubility via the oral route with improved bioavailability.

Mega-solubility of quartz resulting from highly alkaline fluids produced by dissolved albite in H2O at deep crustal conditions

NASA Astrophysics Data System (ADS)

Makhluf, A. R.; Manning, C. E.

2017-12-01

Models of H2O-rich fluids equilibrated with rocks at high P and T fail to predict the high solubilities observed experimentally, chiefly because thermodynamic data for the most abundant solutes is lacking. We investigated the effects of dissolved albite (Ab) on the solubility of quartz (Qz) at 1.0 GPa and 675-900 °C using a piston-cylinder apparatus to quantify possible mineral buffering or enhancement effects. We found a very large enhancement effect on the solubility of Qz when dissolved in dilute aqueous Ab solutions. SiO2 concentrations are similar to Qz solubility in strongly alkaline KOH solutions. At the highest temperature of 900 °C, we found that the solubility of Qz in 1.0 molal Ab solution increases by of factor of 4.5 over that in pure H2O, which corresponds to 10.7 molal SiO2. The nearly identical solubility of Qz in KOH(aq) and Ab solutions of the same concentration, P, and T, strongly suggest that NaOH(aq) liberated from NaAlSi3O8 in H2O fluids effects SiO2 solubility in a similar manner to that of KOH(aq). The deprotonated silica dimer was found to be a key species responsible for the high solubility of Qz in KOH(aq) and is likely responsible for the high solubility of Qz in Ab solutions. While the binaries Qz-H2O, Ab-H2O, and Qz-Ab are well known at 1.0 GPa, little data exists on the ternary system. The new results help quantify the ternary relations in the Ab-Qz-H2O system, which can be used as a simple model for liquid-vapor immiscibility granitic magmas. In addition, these highly alkaline solute-rich aqueous fluids suggest a mechanism for Ab-Qz metasomatism in subduction zones, such as in the Catalina schist (Bebout and Barton 1993), which provides an alternative to high P-T magmas. Our results show that subduction zone and metasomatic fluids may be much more alkaline and have significantly higher dissolving power than previously thought.

Solubility of gold in oxidized, sulfur-bearing fluids at 500-850 °C and 200-230 MPa: A synthetic fluid inclusion study

NASA Astrophysics Data System (ADS)

Guo, Haihao; Audétat, Andreas; Dolejš, David

2018-02-01

Although Au solubility in magmatic-hydrothermal fluids has been investigated by numerous previous studies, there is a dearth of data on oxidized (log fO2 > FMQ+2.5; FMQ - fayalite-magnetite-quartz buffer), sulfur-bearing fluids such as those that formed porphyry Cu-Au (-Mo) deposits. We performed experiments to constrain the effects of fluid salinity, HCl content, sulfur content, fO2 and temperature on Au solubility in such oxidized, sulfur-bearing fluids. For this purpose, small aliquots of fluids equilibrated with Au metal were trapped at high pressure and temperature in the form of synthetic fluid inclusions in quartz and were subsequently analyzed by LA-ICP-MS. Additionally, Raman spectra were collected from quartz-hosted fluid inclusions at up to 600 °C to help to identify the nature of dissolved gold and sulfur species. Gold solubility was found to be affected most strongly by the HCl content of the fluid, followed by fO2, fluid salinity and temperature. Compared to these factors the sulfur content of the fluid has relatively little influence. At 600 °C and 100 MPa, fluids with geologically realistic HCl contents (∼1.1 wt%) and salinities (7-50 wt% NaClequiv) dissolve ∼1000-3000 ppm Au at oxygen fugacities controlled by the magnetite-hematite buffer. At even more oxidized conditions (three log units above the hematite-magnetite fO2 buffer), HCl-, NaCl- and H2SO4-rich fluids can dissolve up to 5 wt% Au at 800 °C and 200 MPa. The observed Au solubility trends are controlled by HCl0 species in the Na-H-Cl-SO4 fluid and are quantitatively reproduced by existing thermodynamic data for Au-Cl complexes. In all experiments, AuCl0 and AuCl2- species are predicted to occur in comparable although variable concentrations, and account for more than 95% of Au solutes. Natural, high-temperature (>500 °C) brine inclusions from porphyry Cu-Au (-Mo) deposits contain significantly less Au than gold-saturated brines that were synthesized experimentally, implying that the natural brines were Au-undersaturated. Consequently, gold grades in Au-rich porphyries were not controlled by the precipitation of native Au, but rather by factors that caused the precipitation of Au-bearing hydrothermal sulfides such as bornite.

Membrane technology for treating of waste nanofluids coolant: A review

NASA Astrophysics Data System (ADS)

Mohruni, Amrifan Saladin; Yuliwati, Erna; Sharif, Safian; Ismail, Ahmad Fauzi

2017-09-01

The treatment of cutting fluids wastes concerns a big number of industries, especially from the machining operations to foster environmental sustainability. Discharging cutting fluids, waste through separation technique could protect the environment and also human health in general. Several methods for the separation emulsified oils or oily wastewater have been proposed as three common methods, namely chemical, physicochemical and mechanical and membrane technology application. Membranes are used into separate and concentrate the pollutants in oily wastewater through its perm-selectivity. Meanwhile, the desire to compensate for the shortcomings of the cutting fluid media in a metal cutting operation led to introduce the using of nanofluids (NFs) in the minimum quantity lubricant (MQL) technique. NFs are prepared based on nanofluids technology by dispersing nanoparticles (NPs) in liquids. These fluids have potentially played to enhance the performance of traditional heat transfer fluids. Few researchers have studied investigation of the physical-chemical, thermo-physical and heat transfer characteristics of NFs for heat transfer applications. The use of minimum quantity lubrication (MQL) technique by NFs application is developed in many metal cutting operations. MQL did not only serve as a better alternative to flood cooling during machining operation and also increases better-finished surface, reduces impact loads on the environment and fosters environmental sustainability. Waste coolant filtration from cutting tools using membrane was treated by the pretreated process, coagulation technique and membrane filtration. Nanomaterials are also applied to modify the membrane structure and morphology. Polyvinylidene fluoride (PVDF) is the better choice in coolant wastewater treatment due to its hydrophobicity. Using of polyamide nanofiltration membranes BM-20D and UF-PS-100-100, 000, it resulted in the increase of permeability of waste coolant filtration. Titanium dioxide is nanomaterials additive to modify the Nanopores of the surface membrane. Contact angle and average pore size were used in the investigation of the surface morphology of membranes. An adequate choice in modifying the membrane surface in waste coolant filtration may bring a promised alternative as a solution in waste coolant remediation.

Design of porous microparticles with single-micron size by novel spray freeze-drying technique using four-fluid nozzle.

PubMed

Niwa, Toshiyuki; Shimabara, Hiroko; Kondo, Masahiro; Danjo, Kazumi

2009-12-01

Spray freeze-drying (SFD) process, which is a novel particle design technique previously developed by authors, has been improved by using four-fluid nozzle (4N) instead of conventional two-fluid nozzle (2N) to expand its application in pharmaceutical industry. Aqueous spray solutions of the drug and the polymeric carrier were separately supplied into 4N, and atomized while colliding with each other at the tip of nozzle. The droplets of mixed solutions were directly immersed into liquid nitrogen and immediately frozen to form a suspension. Then, the iced droplets were lyophilized by freeze-dryer to prepare the composite particles of the drug and carrier. This process has been used in the present study to modify and enhance the dissolution profiles of poorly water-soluble drug, phenytoin. Water-soluble and enteric polymeric carriers in pharmaceutical use were used as a dissolution modifier. The SFD composite particles prepared by using 4N were fully characterized compared to those using 2N from morphological and physicochemical perspectives. It was found that the particles have fine porous structure producing vast specific surface area. Further, phenytoin was completely dispersed as amorphous state in the polymeric matrix with higher carrier ratio than phenytoin:carrier = 1:3. The dissolution of phenytoin from the water-soluble carrier-based particles was greatly enhanced because of large effective surface area and disappearance of crystalline. On the other hand, the release profiles from enteric carrier-based particles showed the typical enteric patterns, that is, delayed in acidic medium and accelerated in neutral pH. The results demonstrated that SFD technique using 4N has potential to develop the novel solubilized formulation for poorly water-soluble APIs.

Characterization of two polymorphs of salmeterol xinafoate crystallized from supercritical fluids.

PubMed

Tong, H H; Shekunov, B Y; York, P; Chow, A H

2001-06-01

To characterize two polymorphs of salmeterol xinafoate (SX-I and SX-II) produced by supercritical fluid crystallization. SX-I and SX-II were crystallized as fine powders using Solution Enhanced Dispersion by Supercritical Fluids (SEDS). The two polymorphs and a reference micronized SX sample (MSX) were characterized using powder X-ray diffractometry (PXRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), aqueous solubility (and dissolution) determination at 5-40 degrees C, BET adsorption analysis, and inverse gas chromatography (IGC). Compared with SX-I, SX-II exhibited a lower enthalpy of fusion, a higher equilibrium solubility, a higher intrinsic dissolution rate, a lower enthalpy of solution (based on van't Hoff solubility plots), and a different FTIR spectrum (reflecting differences in intermolecular hydrogen bonding). Solubility ratio plot yielded a transition temperature (-99 degrees C) below the melting points of both polymorphs. MSX showed essentially the same crystal form as SX-I (confirmed by PXRD and FTIR), but a distinctly different thermal behaviour. Mild trituration of SX-I afforded a similar DSC profile to MSX while prolonged grinding of SX-I gave rise to an endotherm at -109 degrees C, corresponding to solid-solid transition of SX-I to SX-II. Surface analysis of MSX, SX-I, and SX-II by IGC revealed significant differences in surface free energy in terms of both dispersive (nonpolar) interactions and specific (polar) acid-base properties. The SEDS-processed SX-I and SX-II display high polymorphic purity and distinctly different physical and surface properties. The polymorphs are related enantiotropically with SX-I being the thermodynamically stable form at room temperature.

Method for separating metal chelates from other materials based on solubilities in supercritical fluids

DOEpatents

Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

2001-01-01

A method for separating a desired metal or metalloi from impurities using a supercritical extraction process based on solubility differences between the components, as well as the ability to vary the solvent power of the supercritical fluid, is described. The use of adduct-forming agents, such as phosphorous-containing ligands, to separate metal or metalloid chelates in such processes is further disclosed. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones; phosphine oxides, such as trialkylphosphine oxides, triarylphosphine oxides and alkylarylphosphine oxides; phosphinic acids; carboxylic acids; phosphates, such as trialkylphosphates, triarylphosphates and alkylarylphosphates; crown ethers; dithiocarbamates; phosphine sulfides; phosphorothioic acids; thiophosphinic acids; halogenated analogs of these chelating agents; and mixtures of these chelating agents. In especially preferred embodiments, at least one of the chelating agents is fluorinated.

H2O-CO2-S-Cl partitioning and mixing in rhyolitic melts and fluid - Implications on closed-system degassing in rhyolite

NASA Astrophysics Data System (ADS)

Ding, S.; Webster, J. D.

2017-12-01

Magmatic degassing involving multiple volatile components (C, O, H, S, Cl, etc.) is one of the key factors influencing the timing and nature of volcanic eruptions, and the chemistry of volcanic gases released to the surface. In particular, exsolution of these volatiles from silicic magma during ascent could trigger explosive volcanic eruptions, which can exert strong impacts on surface temperature, ecology and human health. However, quantitative evaluation of this process in silicic magma remains ambiguous due to the lack of experiments in such chemically complex systems. Rhyolite-fluid(s) equilibria experiments were conducted in an IHPVat 100-300 MPa and 800 ° C to determine the solubilities, fluid-melt partitioning, and mixing properties of H2O, CO2, S, and Cl in the oxygen fugacity (fO2) range of FMQ to FMQ+3. The integrated bulk fluids contain up to 94 mol% H2O, 32 mol% CO2, 1 mol% S and 1mol% Cl. Rhyolite melt dissolved 20- 770 ppm CO2 and 4-7 wt.% H2O, varying with pressure, fluid composition, and fO2. Concentrations of H2O and CO2 in melt from C-O-H-S-Cl- bearing experiments at 100 and 200 MPa, and from C-O-H only experiments are generally consistent with the predictions of existing CO2-H2O solubility models based on the C-O-H only system [1-4], while the solubilities of H2O and CO2 in melt with addition of S±Cl at 300 MPa are less than those of the C-O-H- only system. This reduction in H2O and CO2 solubilities exceeds the effects of simple dilution of the coexisting fluid owing to addition of other volatiles, and rather, reflects complex mixing relations. Rhyolite melt also dissolved 20-150 ppm S and 850-2000 ppm Cl, varying with pressure. At 300 MPa, S concentrations in the melt change with fO2. The partitioning of CO2 and S between fluid and melt varies as a function of fluid composition and fO2. Solubilities and complex mixing relationships of CO2, H2O, S and Cl revealed in our experiments can be applied to massive rhyolitic eruptions like those of the Bishop tuff, Toba tuff and Pinatubo to better understand the degassing process, to estimate fluid compositions, and thus, to evaluate the potential environmental impacts of these super eruptions. [1] Ghiorso amd Gualda, 2015, CMP; [2] Liu et al., 2005, J. Volcanol. Geotherm. Res.; [3] Newman and Lowenstern, 2002, Comput. Geosci.; [3] Tamic et al., 2001, Chem. Geol..

Accumulation of sphingoid bases and sphingoid base 1-phosphates: A possible mechanism for Fusarium verticillioides corn-seedling disease

USDA-ARS?s Scientific Manuscript database

Sphingolipids are important structural components of membranes involved in signaling pathways that regulate cell growth and death. Fumonisins (FB) are water soluble mycotoxins produced by F. verticillioides, which is parasitic to corn. FBs are inhibitors of ceramide synthase (CS), a key enzyme in sp...

Hybrid microfluidic and nanofluidic system

DOEpatents

Bohn, Paul W [Champaign, IL; Sweedler, Jonathan V [Urbana, IL; Shannon, Mark A [Champaign, IL; Kuo, Tzu-chi [Savoy, IL

2007-05-22

A fluid circuit includes a membrane having a first side, a second side opposite the first side, and a pore extending from the first side to the second side. The circuit also includes a first channel containing fluid extending along the first side of the membrane and a second channel containing fluid extending along the second side of the membrane and crossing the first channel. The circuit also includes an electrical source in electrical communication with at least one of the first fluid and second fluid for selectively developing an electrical potential between fluid in the first channel and fluid in the second channel. This causes at least one component of fluid to pass through the pore in the membrane from one of the first channel and the second channel to the other of the first channel and the second channel.

Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: II. Some general geologic applications

USGS Publications Warehouse

Hemley, J.J.; Hunt, J.P.

1992-01-01

The experimental metal solubilities for rock-buffered hydrothermal systems provide important insights into the acquisition, transport, and deposition of metals in real hydrothermal systems that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in hydrothermal systems occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors

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.

The Solubility of Diopside in Water at 10 to 15 kbar and 650 to 900 C

NASA Astrophysics Data System (ADS)

Macris, C. A.; Manning, C. E.

2005-12-01

Subduction zone fluids play a critical role in mass transfer and mantle-wedge metasomatism, yet little is known about their composition and chemical behavior. One way to better understand these important fluids is to investigate the solubility of minerals at subduction zone conditions. The solubility of diopside in H2O was measured at 10 to 15 kbar, 650 to 900 °C using a piston-cylinder apparatus with NaCl-graphite furnaces. A single gem-quality diopside crystal was placed in an inner Pt capsule, which then was perforated to allow fluid ingress and added with H2O to an outer Pt capsule, which was then sealed. The solubility was determined by the weight loss of the diopside crystals. All charges were carefully examined by SEM for composition and textural characteristics of quench material. SEM analysis revealed that in several experiments small diopside crystals nucleated and grew in the outer capsule or on the walls of the inner capsule due to fluid convection within the charge. These experiments yielded erroneously high solubilities and were omitted from final plots and equation calculations. Diopside was found to dissolve incongruently to forsterite + dissolved species at all conditions investigated. The forsterite occurs as euhedral crystals in pits etched from the diopside grain covering less than 5% of its surface. In addition, long thin wollastonite blades and a layer of SiO2 "mud" form upon quenching of the run. Experiments at 700 °C and varying times showed that diopside plus forsterite plus fluid reached equilibrium by 12 hours. The solubility of diopside + forsterite in H2O increases with increasing pressure and temperature. At 10 kbar, solubility increases from 0.004 molal at 650 °C to 0.012 molal at 900 °C. At 800 °C and 10 to 15 kbar, solubility increases from 0.008 to 0.015 molal. These preliminary data yield the equation: log mdi+fo = -0.7539 + -2135.7/T + 0.6355P, where T is in K and P is in GPa. Because temperature enhances solubility more than pressure in this system, we can predict that as a fluid moves from slab to wedge, which leads to decompression and heating, di+fo solubility will increase. The resulting fluid will be enriched in Ca and Si, but low in Mg. These results are consistent with theoretical predictions on the composition of fluids in equilibrium with eclogites (Manning 1998), experimental investigations on fluid compositions in equilibrium with high-pressure mantle rocks (Schneider and Eggler 1986; Ayers et al. 1997), and vein-mineral assemblages in blueschists and eclogites (e.g., Gao and Klemd 2001; Becker et al. 1999). Ayers J., Dittmer S.K., Layne G.D. (1997) Earth Planet. Sci. Lett. 150:381-398; Becker H., Jockum K.P., Carlson R.W. (1999) Chem. Geol. 160:291-308; Gao J., Klemd R. (2001) Contrib. Mineral. Petrol. 142:1-14; Manning C.E. (1998) Swiss Bull. Mineral. Petrol. 78:225-242; Schneider M.E., Eggler D.H. (1986) Geochim. Cosmochim. Acta 50:711-724

Development of a Compact, Efficient Cooling Pump for Space Suit Life Support Systems

NASA Technical Reports Server (NTRS)

van Boeyen, Roger; Reeh, Jonathan; Trevino, Luis

2009-01-01

A compact, low-power electrochemically-driven fluid cooling pump is currently being developed by Lynntech, Inc. With no electric motor and minimal lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness is achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit primary life support systems (PLSSs). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops is discussed.

Preventing cleavage of Mer promotes efferocytosis and suppresses acute lung injury in bleomycin treated mice

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

Lee, Ye-Ji; Tissue Injury Defense Research Center, School of Medicine, Ewha Womans University, Seoul; Lee, Seung-Hae

2012-08-15

Mer receptor tyrosine kinase (Mer) regulates macrophage activation and promotes apoptotic cell clearance. Mer activation is regulated through proteolytic cleavage of the extracellular domain. To determine if membrane-bound Mer is cleaved during bleomycin-induced lung injury, and, if so, how preventing the cleavage of Mer enhances apoptotic cell uptake and down-regulates pulmonary immune responses. During bleomycin-induced acute lung injury in mice, membrane-bound Mer expression decreased, but production of soluble Mer and activity as well as expression of disintegrin and metalloproteinase 17 (ADAM17) were enhanced . Treatment with the ADAM inhibitor TAPI-0 restored Mer expression and diminished soluble Mer production. Furthermore, TAPI-0more » increased Mer activation in alveolar macrophages and lung tissue resulting in enhanced apoptotic cell clearance in vivo and ex vivo by alveolar macrophages. Suppression of bleomycin-induced pro-inflammatory mediators, but enhancement of hepatocyte growth factor induction were seen after TAPI-0 treatment. Additional bleomycin-induced inflammatory responses reduced by TAPI-0 treatment included inflammatory cell recruitment into the lungs, levels of total protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, as well as caspase-3 and caspase-9 activity and alveolar epithelial cell apoptosis in lung tissue. Importantly, the effects of TAPI-0 on bleomycin-induced inflammation and apoptosis were reversed by coadministration of specific Mer-neutralizing antibodies. These findings suggest that restored membrane-bound Mer expression by TAPI-0 treatment may help resolve lung inflammation and apoptosis after bleomycin treatment. -- Highlights: ►Mer expression is restored by TAPI-0 treatment in bleomycin-stimulated lung. ►Mer signaling is enhanced by TAPI-0 treatment in bleomycin-stimulated lung. ►TAPI-0 enhances efferocytosis and promotes resolution of lung injury.« less

Membrane-entrapped microperoxidase as a 'solid-state' promoter in the electrochemistry of soluble metalloproteins.

PubMed Central

Brunori, M; Santucci, R; Campanella, L; Tranchida, G

1989-01-01

Immobilization of biological systems in solid matrices is presently of great interest, in view of the many potential advantages associated with both the higher stability of the immobilized macromolecules and the potential utilization for biotechnology. In the present paper the electrochemical behaviour of the undecapeptide from cytochrome c (called microperoxidase) tightly entrapped in cellulose triacetate membrane is reported; its utilization as 'solid-state' promoter in the electrochemistry of soluble metalloproteins is presented. The results obtained indicate that: (i) membrane-entrapped microperoxidase undergoes rapid reversible electron transfer at a glassy carbon electrode; (ii) the electrochemical process is diffusion-controlled; (iii) entrapped microperoxidase acts as 'solid-state' promoter in the electrochemistry of soluble cytochrome c and of azurin. PMID:2557833

Characterization of the liver tissue interstitial fluid (TIF) proteome indicates potential for application in liver disease biomarker discovery.

PubMed

Sun, Wei; Ma, Jie; Wu, Songfeng; Yang, Dong; Yan, Yujuan; Liu, Kehui; Wang, Jinglan; Sun, Longqin; Chen, Ning; Wei, Handong; Zhu, Yunping; Xing, Baocai; Zhao, Xiaohang; Qian, Xiaohong; Jiang, Ying; He, Fuchu

2010-02-05

Tissue interstitial fluid (TIF) forms the interface between circulating body fluids and intracellular fluid. Pathological alterations of liver cells could be reflected in TIF, making it a promising source of liver disease biomarkers. Mouse liver TIF was extracted, separated by SDS-PAGE, analyzed by linear ion trap mass spectrometer, and 1450 proteins were identified. These proteins may be secreted, shed from membrane vesicles, or represent cellular breakdown products. They show different profiling patterns, quantities, and possibly modification/cleavage of intracellular proteins. The high solubility and even distribution of liver TIF supports its suitability for proteome analysis. Comparison of mouse liver TIF data with liver tissue and plasma proteome data identified major proteins that might be released from liver to plasma and serve as blood biomarkers of liver origin. This result was partially supported by comparison of human liver TIF data with human liver and plasma proteome data. Paired TIFs from tumor and nontumor liver tissues of a hepatocellular carcinoma patient were analyzed and the profile of subtracted differential proteins supports the potential for biomarker discovery in TIF. This study is the first analysis of the liver TIF proteome and provides a foundation for further application of TIF in liver disease biomarker discovery.

Interactions of surfactants with lipid membranes.

PubMed

Heerklotz, Heiko

2008-01-01

Surfactants are surface-active, amphiphilic compounds that are water-soluble in the micro- to millimolar range, and self-assemble to form micelles or other aggregates above a critical concentration. This definition comprises synthetic detergents as well as amphiphilic peptides and lipopeptides, bile salts and many other compounds. This paper reviews the biophysics of the interactions of surfactants with membranes of insoluble, naturally occurring lipids. It discusses structural, thermodynamic and kinetic aspects of membrane-water partitioning, changes in membrane properties induced by surfactants, membrane solubilisation to micelles and other phases formed by lipid-surfactant systems. Each section defines and derives key parameters, mentions experimental methods for their measurement and compiles and discusses published data. Additionally, a brief overview is given of surfactant-like effects in biological systems, technical applications of surfactants that involve membrane interactions, and surfactant-based protocols to study biological membranes.

Head-To-Head Comparison of Different Solubility-Enabling Formulations of Etoposide and Their Consequent Solubility-Permeability Interplay.

PubMed

Beig, Avital; Miller, Jonathan M; Lindley, David; Carr, Robert A; Zocharski, Philip; Agbaria, Riad; Dahan, Arik

2015-09-01

The purpose of this study was to conduct a head-to-head comparison of different solubility-enabling formulations, and their consequent solubility-permeability interplay. The low-solubility anticancer drug etoposide was formulated in several strengths of four solubility-enabling formulations: hydroxypropyl-β-cyclodextrin, the cosolvent polyethylene glycol 400 (PEG-400), the surfactant sodium lauryl sulfate, and an amorphous solid dispersion formulation. The ability of these formulations to increase the solubility of etoposide was investigated, followed by permeability studies using the parallel artificial membrane permeability assay (PAMPA) and examination of the consequent solubility-permeability interplay. All formulations significantly increased etoposide's apparent solubility. The cyclodextrin-, surfactant-, and cosolvent-based formulations resulted in a concomitant decreased permeability that could be modeled directly from the proportional increase in the apparent solubility. On the contrary, etoposide permeability remained constant when using the ASD formulation, irrespective of the increased apparent solubility provided by the formulation. In conclusion, supersaturation resulting from the amorphous form overcomes the solubility-permeability tradeoff associated with other formulation techniques. Accounting for the solubility-permeability interplay may allow to develop better solubility-enabling formulations, thereby maximizing the overall absorption of lipophilic orally administered drugs. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Regulation and therapeutic targeting of peptide-activated receptor guanylyl cyclases

PubMed Central

Potter, Lincoln R.

2016-01-01

Cyclic GMP is a ubiquitous second messenger that regulates a wide array of physiologic processes such as blood pressure, long bone growth, intestinal fluid secretion, phototransduction and lipolysis. Soluble and single-membrane-spanning enzymes called guanylyl cyclases (GC) synthesize cGMP. In humans, the latter group consists of GC-A, GC-B, GC-C, GC-E and GC-F, which are also known as NPR-A, NPR-B, StaR, Ret1-GC and Ret2-GC, respectively. Membrane GCs are activated by peptide ligands such as atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP), guanylin, uroguanylin, heat stable enterotoxin and GC-activating proteins. Nesiritide and carperitide are clinically approved peptide-based drugs that activate GC-A. CD-NP is an experimental heart failure drug that primarily activates GC-B but also activates GC-A at high concentrations and is resistant to degradation. Inactivating mutations in GC-B cause acromesomelic dysplasia type Maroteaux dwarfism and chromosomal mutations that increase CNP concentrations are associated with Marfanoid-like skeletal overgrowth. Pump-based CNP infusions increase skeletal growth in a mouse model of the most common type of human dwarfism, which supports CNP/GC-B-based therapies for short stature diseases. Linaclotide is a peptide activator of GC-C that stimulates intestinal motility and is in late-stage clinical trials for the treatment of chronic constipation. This review discusses the discovery of cGMP, guanylyl cyclases, the general characteristics and therapeutic applications of GC-A, GC-B and GC-C, and emphasizes the regulation of transmembrane guanylyl cyclases by phosphorylation and ATP. PMID:21185863

Microfluidic device and methods for focusing fluid streams using electroosmotically induced pressures

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2010-06-01

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either electric current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to electrokinetically inducing fluid flow to confine a selected material in a region of a microchannel that is not influenced by an electric field. Other structures for inducing fluid flow in accordance with this invention include nanochannel bridging membranes and alternating current fluid pumping devices. Applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Evaluation of a competitive enzyme-linked immunosorbent assay for measurements of soluble HLA-G protein.

PubMed

Rasmussen, M; Dahl, M; Buus, S; Djurisic, S; Ohlsson, J; Hviid, T V F

2014-08-01

The human leukocyte antigen (HLA) class Ib molecule, HLA-G, has gained increased attention because of its assumed important role in immune regulation. The HLA-G protein exists in several soluble isoforms. Most important are the actively secreted HLA-G5 full-length isoform generated by alternative splicing retaining intron 4 with a premature stop codon, and the cleavage of full-length membrane-bound HLA-G1 from the cell surface, so-called soluble HLA-G1 (sHLA-G1). A specific and sensitive immunoassay for measurements of soluble HLA-G is mandatory for conceivable routine testing and research projects. We report a novel method, a competitive immunoassay, for measuring HLA-G5/sHLA-G1 in biological fluids. The sHLA-G immunoassay is based upon a competitive enzyme-linked immunosorbent assay (ELISA) principle. It includes a recombinant sHLA-G1 protein in complex with β2-microglobulin and a peptide as a standard, biotinylated recombinant sHLA-G1 as an indicator, and the MEM-G/9 anti-HLA-G monoclonal antibody (mAb) as the capture antibody. The specificity and sensitivity of the assay were evaluated. Testing with different recombinant HLA class I proteins and different anti-HLA class I mAbs showed that the sHLA-G immunoassay was highly specific. Optimal combinations of competitor sHLA-G1 and capture mAb concentrations were determined. Two versions of the assay were tested. One with a relatively wide dynamic range from 3.1 to 100.0 ng/ml, and another more sensitive version ranging from 1.6 to 12.5 ng/ml. An intra-assay coefficient of variation (CV) of 15.5% at 88 ng/ml and an inter-assay CV of 23.1% at 39 ng/ml were determined. An assay based on the competitive sHLA-G ELISA may be important for measurements of sHLA-G proteins in several conditions: assisted reproduction, organ transplantation, cancer, and certain pregnancy complications, both in research studies and possibly in the future also for clinical routine use. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Membrane-Based Characterization of a Gas Component — A Transient Sensor Theory

PubMed Central

Lazik, Detlef

2014-01-01

Based on a multi-gas solution-diffusion problem for a dense symmetrical membrane this paper presents a transient theory of a planar, membrane-based sensor cell for measuring gas from both initial conditions: dynamic and thermodynamic equilibrium. Using this theory, the ranges for which previously developed, simpler approaches are valid will be discussed; these approaches are of vital interest for membrane-based gas sensor applications. Finally, a new theoretical approach is introduced to identify varying gas components by arranging sensor cell pairs resulting in a concentration independent gas-specific critical time. Literature data for the N2, O2, Ar, CH4, CO2, H2 and C4H10 diffusion coefficients and solubilities for a polydimethylsiloxane membrane were used to simulate gas specific sensor responses. The results demonstrate the influence of (i) the operational mode; (ii) sensor geometry and (iii) gas matrices (air, Ar) on that critical time. Based on the developed theory the case-specific suitable membrane materials can be determined and both operation and design options for these sensors can be optimized for individual applications. The results of mixing experiments for different gases (O2, CO2) in a gas matrix of air confirmed the theoretical predictions. PMID:24608004

Soluble Epidermal Growth Factor Receptors (sEGFRs) in Cancer: Biological Aspects and Clinical Relevance.

PubMed

Maramotti, Sally; Paci, Massimiliano; Manzotti, Gloria; Rapicetta, Cristian; Gugnoni, Mila; Galeone, Carla; Cesario, Alfredo; Lococo, Filippo

2016-04-19

The identification of molecules that can reliably detect the presence of a tumor or predict its behavior is one of the biggest challenges of research in cancer biology. Biological fluids are intriguing mediums, containing many molecules that express the individual health status and, accordingly, may be useful in establishing the potential risk of cancer, defining differential diagnosis and prognosis, predicting the response to treatment, and monitoring the disease progression. The existence of circulating soluble growth factor receptors (sGFRs) deriving from their membrane counterparts has stimulated the interest of researchers to investigate the use of such molecules as potential cancer biomarkers. But what are the origins of circulating sGFRs? Are they naturally occurring molecules or tumor-derived products? Among these, the epidermal growth factor receptor (EGFR) is a cell-surface molecule significantly involved in cancer development and progression; it can be processed into biological active soluble isoforms (sEGFR). We have carried out an extensive review of the currently available literature on the sEGFRs and their mechanisms of regulation and biological function, with the intent to clarify the role of these molecules in cancer (and other pathological conditions) and, on the basis of the retrieved evidences, speculate about their potential use in the clinical setting.

Discovery of Dual-Action Membrane-Anchored Modulators of Incretin Receptors

PubMed Central

Fortin, Jean-Philippe; Chinnapen, Daniel; Beinborn, Martin; Lencer, Wayne; Kopin, Alan S.

2011-01-01

Background The glucose-dependent insulinotropic polypeptide (GIP) and the glucagon-like peptide-1 (GLP-1) receptors are considered complementary therapeutic targets for type 2 diabetes. Using recombinant membrane-tethered ligand (MTL) technology, the present study focused on defining optimized modulators of these receptors, as well as exploring how local anchoring influences soluble peptide function. Methodology/Principal Findings Serial substitution of residue 7 in membrane-tethered GIP (tGIP) led to a wide range of activities at the GIP receptor, with [G7]tGIP showing enhanced efficacy compared to the wild type construct. In contrast, introduction of G7 into the related ligands, tGLP-1 and tethered exendin-4 (tEXE4), did not affect signaling at the cognate GLP-1 receptor. Both soluble and tethered GIP and GLP-1 were selective activators of their respective receptors. Although soluble EXE4 is highly selective for the GLP-1 receptor, unexpectedly, tethered EXE4 was found to be a potent activator of both the GLP-1 and GIP receptors. Diverging from the pharmacological properties of soluble and tethered GIP, the newly identified GIP-R agonists, (i.e. [G7]tGIP and tEXE4) failed to trigger cognate receptor endocytosis. In an attempt to recapitulate the dual agonism observed with tEXE4, we conjugated soluble EXE4 to a lipid moiety. Not only did this soluble peptide activate both the GLP-1 and GIP receptors but, when added to receptor expressing cells, the activity persists despite serial washes. Conclusions These findings suggest that conversion of a recombinant MTL to a soluble membrane anchored equivalent offers a means to prolong ligand function, as well as to design agonists that can simultaneously act on more than one therapeutic target. PMID:21935440

Intra-articular corticosteroid preparations: different characteristics and their effect during inflammation induced by monosodium urate crystals in the rat subcutaneous air pouch.

PubMed

Rull, M; Clayburne, G; Sieck, M; Schumacher, H R

2003-09-01

To examine the effects of three commonly used intra-articular depot corticosteroid preparations tested in a rat air pouch model and their effect against monosodium urate (MSU) crystal-induced inflammation. Rheumatologists use intra-articular corticosteroid preparations to relieve pain and inflammation of acute monoarthritis without really knowing their effects on the synovial fluid and membrane or the differences between distinct preparations. This work compares the effect of three commonly used corticosteroid preparations in vivo, showing that they behave differently. A subcutaneous air pouch was formed in male Sprague-Dawley rats. A first group of 6-day-old air pouches were injected with 10 ml of 6 mg/ml normal saline solution, 6 mg/ml betamethasone containing both depot betamethasone acetate and soluble betamethasone phosphate (Celestone) in 9 ml of normal saline solution, 20 mg/ml of prednisolone tebutate (Hydeltra) in 9 ml of normal saline solution or 20 mg/ml of triamcinolone hexacetonide (Aristospan) in 9 ml of normal saline solution. A second group (group 2) of air pouches were injected with 15 mg of synthetic MSU crystals and 24 h later they were reinjected with 1 ml of the same three corticosteroid suspensions. For each condition four rats were killed at 6, 24, 48 h and 7 days. Pouch fluid and tissue were analysed. In the first 6 h after normal saline solution or corticosteroid injection into the air pouch there were mildly increased leucocyte counts in the air pouch fluid. Betamethasone-injected pouches showed no cells in the fluid after 6 h and no crystals after 24 h, triamcinolone-injected pouches still showed rare cells at 7 days. Both triamcinolone and prednisolone crystals persisted in higher numbers and lasted longer in the fluid than did betamethasone (P<0.05). In group 2 MSU crystal phagocytosis in the fluid was decreased in the betamethasone- (P<0.01), prednisolone- (P<0.003) and triamcinolone- (P<0.006) injected pouches when compared with the MSU crystal-injected pouches alone. Pouches injected with MSU crystals alone showed the most intense tissue inflammation at all times. After MSU, betamethasone-injected pouches had a rapid but mild decrease in the number of lining cells and inflammation. In contrast, triamcinolone- and prednisolone-injected pouches showed a very thin tissue with few or no vessels and almost no inflammation at 7 days. The pouches injected with MSU crystals and any of the corticoid preparations had three times more tophus-like structures and persistent crystals identified than the ones injected with MSU crystals alone. Each of the corticosteroid preparations by themselves produced very mild transient inflammation. The betamethasone preparation with a soluble steroid component had a quicker but milder anti-inflammatory effect on MSU crystal-induced inflammation. In contrast to the doses used, prednisolone tebutate and triamcinolone hexacetonide preparations dramatically suppressed urate crystal-induced inflammation at 7 days, but both produced atrophy and necrosis of the membrane, yielding a very thin membrane with almost no vessels. When used for MSU crystal-induced inflammation these corticosteroid preparations suppressed some aspects of inflammation but may actually promote the persistence of MSU crystals and the formation of tophi.

Estimation of the probability of exposure to metalworking fluids in a population-based case-control study

PubMed Central

Park, Dong-Uk; Colt, Joanne S.; Baris, Dalsu; Schwenn, Molly; Karagas, Margaret R.; Armenti, Karla R.; Johnson, Alison; Silverman, Debra T; Stewart, Patricia A

2014-01-01

We describe here an approach for estimating the probability that study subjects were exposed to metalworking fluids (MWFs) in a population-based case-control study of bladder cancer. Study subject reports on the frequency of machining and use of specific MWFs (straight, soluble, and synthetic/semi-synthetic) were used to estimate exposure probability when available. Those reports also were used to develop estimates for job groups, which were then applied to jobs without MWF reports. Estimates using both cases and controls and controls only were developed. The prevalence of machining varied substantially across job groups (10-90%), with the greatest percentage of jobs that machined being reported by machinists and tool and die workers. Reports of straight and soluble MWF use were fairly consistent across job groups (generally, 50-70%). Synthetic MWF use was lower (13-45%). There was little difference in reports by cases and controls vs. controls only. Approximately, 1% of the entire study population was assessed as definitely exposed to straight or soluble fluids in contrast to 0.2% definitely exposed to synthetic/semi-synthetics. A comparison between the reported use of the MWFs and the US production levels by decade found high correlations (r generally >0.7). Overall, the method described here is likely to have provided a systematic and reliable ranking that better reflects the variability of exposure to three types of MWFs than approaches applied in the past. PMID:25256317

Binding constants of membrane-anchored receptors and ligands depend strongly on the nanoscale roughness of membranes.

PubMed

Hu, Jinglei; Lipowsky, Reinhard; Weikl, Thomas R

2013-09-17

Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics simulations. We find that the binding constant of the anchored proteins strongly decreases with the membrane roughness caused by thermally excited membrane shape fluctuations on nanoscales. We present a theory that explains the roughness dependence of the binding constant for the anchored proteins from membrane confinement and that relates this constant to the binding constant of soluble proteins without membrane anchors. Because the binding constant of soluble proteins is readily accessible in experiments, our results provide a useful route to compute the binding constant of membrane-anchored receptor and ligand proteins.

The "high solubility" definition of the current FDA Guidance on Biopharmaceutical Classification System may be too strict for acidic drugs.

PubMed

Yazdanian, Mehran; Briggs, Katherine; Jankovsky, Corinne; Hawi, Amale

2004-02-01

The purpose of this study was to assess if the definition of high solubility as proposed in the FDA Guidance on Biopharmaceutical Classification System (BCS) is too strict for highly permeable acidic drugs. The solubility and permeability values of 20 (18 acidic and 2 non-acidic) nonsteroidal anti-inflammatory drugs (NSAID) were determined. The NSAIDs were grouped into three different sets having acetic acid, propionic acid, or other acidic moieties such as fenamate, oxicam, and salicylate. Two nonacidic NSAIDs (celecoxib and rofecoxib) were also included for comparison purposes. Equilibrium solubility values were determined at pH 1.2, 5.0, 7.4, and in biorelevant media simulating fed intestinal fluid at pH 5.0. For a select number of acids, we also measured solubility values in media simulating gastric and fasted intestinal fluids. Permeability classification was established relative to that of reference drugs in the Caco-2 cell permeability model. Permeability coefficients for all drugs were measured at concentrations corresponding to the lowest and highest marketed dose strengths dissolved in 250 ml volume, and their potential interaction with cellular efflux pumps was investigated. All NSAIDs with different acidic functional groups were classified as highly permeable based on their Caco-2 cell permeability. Only ketorolac appeared to have a potential for interaction with cellular efflux pumps. Solubility classification was based on comparison of equilibrium solubility at pH 1.2, 5.0. and 7.4 relative to marketed dose strengths in 250 ml. The pKa values for the acidic NSAIDs studied were between 3.5 and 5.1. and, as expected, their solubility increased dramatically at pH 7.4 compared to pH 1.2. Only three NSAIDs, ketorolac, ketoprofen. and acetyl salicylic acid, meet the current criteria for high solubility over the entire pH range. However, with the exception of ibuprofen, oxaprozin, and mefenamic acid, the remaining compounds can be classified as Class I drugs (high solubility-high permeability) relative to solubility at pH 7.4. The use of bio-relevant media simulating gastric and intestinal milieu for solubility measurements or increasing the dose volume to 500 ml did not provide for a better boundary for solubility classification. Based on the current definition of solubility, 15 of the 18 acidic NSAIDs in this study will be classified as Class II compounds as the solubility criteria applies to the entire pH range of 1.2 to 7.4, although the low solubility criteria does not hold true over the entire pH range. Whence, of the 18 acidic drugs, 15 can be classified as Class I based on the pH 7.4 solubility alone. This finding is intriguing because these drugs exhibit Class I behavior as their absorption does not seem to be dissolution or solubility limited. It could then be argued that for acidic drugs, the boundaries for solubility are too restrictive. Solubility at pH > 5 (pH in duodenum) may be more appropriate because most compounds are mainly absorbed in the intestinal region. Consideration for an intermediate solubility classification for highly permeable ionizable compounds that reflects physiological conditions seems warranted.

Opto-mechanical analysis of nonlinear elastomer membrane deformation under hydraulic pressure for variable-focus liquid-filled microlenses.

PubMed

Choi, Seung Tae; Son, Byeong Soo; Seo, Gye Won; Park, Si-Young; Lee, Kyung-Sick

2014-03-10

Nonlinear large deformation of a transparent elastomer membrane under hydraulic pressure was analyzed to investigate its optical performance for a variable-focus liquid-filled membrane microlens. In most membrane microlenses, actuators control the hydraulic pressure of optical fluid so that the elastomer membrane together with the internal optical fluid changes its shape, which alters the light path of the microlens to adapt its optical power. A fluid-structure interaction simulation was performed to estimate the transient behavior of the microlens under the operation of electroactive polymer actuators, demonstrating that the viscosity of the optical fluid successfully stabilizes the fluctuations within a fairly short period of time during dynamic operations. Axisymmetric nonlinear plate theory was used to calculate the deformation profile of the membrane under hydrostatic pressure, with which optical characteristics of the membrane microlens were estimated. The effects of gravitation and viscoelastic behavior of the elastomer membrane on the optical performance of the membrane microlens were also evaluated with finite element analysis.

Molecular Dynamics Simulation of WSK-3, a Computationally Designed, Water-Soluble Variant of the Integral Membrane Protein KcsA

PubMed Central

Bronson, Jonathan; Lee, One-Sun; Saven, Jeffery G.

2006-01-01

Poor solubility and low expression levels often make membrane proteins difficult to study. An alternative to the use of detergents to solubilize these aggregation-prone proteins is the partial redesign of the sequence so as to confer water solubility. Recently, computationally assisted membrane protein solubilization (CAMPS) has been reported, where exposed hydrophobic residues on a protein's surface are computationally redesigned. Herein, the structure and fluctuations of a designed, water-soluble variant of KcsA (WSK-3) were studied using molecular dynamics simulations. The root mean square deviation of the protein from its starting structure, where the backbone coordinates are those of KcsA, was 1.8 Å. The structure of salt bridges involved in structural specificity and solubility were examined. The preferred configuration of ions and water in the selectivity filter of WSK-3 was consistent with the reported preferences for KcsA. The structure of the selectivity filter was maintained, which is consistent with WSK-3 having an affinity for agitoxin2 comparable to that of wild-type KcsA. In contrast to KcsA, the central cavity's side chains were observed to reorient, allowing water diffusion through the side of the cavity wall. These simulations provide an atomistic analysis of the CAMPS strategy and its implications for further investigations of membrane proteins. PMID:16299086

Electrospinning of calcium phosphate-poly (d,l-lactic acid) nanofibers for sustained release of water-soluble drug and fast mineralization

PubMed Central

Fu, Qi-Wei; Zi, Yun-Peng; Xu, Wei; Zhou, Rong; Cai, Zhu-Yun; Zheng, Wei-Jie; Chen, Feng; Qian, Qi-Rong

2016-01-01

Calcium phosphate-based biomaterials have been well studied in biomedical fields due to their outstanding chemical and biological properties which are similar to the inorganic constituents in bone tissue. In this study, amorphous calcium phosphate (ACP) nanoparticles were prepared by a precipitation method, and used for preparation of ACP-poly(d,l-lactic acid) (ACP-PLA) nanofibers and water-soluble drug-containing ACP-PLA nanofibers by electrospinning. Promoting the encapsulation efficiency of water-soluble drugs in electrospun hydrophobic polymer nanofibers is a common problem due to the incompatibility between the water-soluble drug molecules and hydrophobic polymers solution. Herein, we used a native biomolecule of lecithin as a biocompatible surfactant to overcome this problem, and successfully prepared water-soluble drug-containing ACP-PLA nanofibers. The lecithin and ACP nanoparticles played important roles in stabilizing water-soluble drug in the electrospinning composite solution. The electrospun drug-containing ACP-PLA nanofibers exhibited fast mineralization in simulated body fluid. The ACP nanoparticles played the key role of seeds in the process of mineralization. Furthermore, the drug-containing ACP-PLA nanofibers exhibited sustained drug release which simultaneously occurred with the in situ mineralization in simulated body fluid. The osteoblast-like (MG63) cells with spreading filopodia were well observed on the as-prepared nanofibrous mats after culturing for 24 hours, indicating a high cytocompatibility. Due to the high biocompatibility, sustained drug release, and fast mineralization, the as-prepared composite nanofibers may have potential applications in water-soluble drug loading and release for tissue engineering. PMID:27785016

The solubility-permeability interplay and oral drug formulation design: Two heads are better than one.

PubMed

Dahan, Arik; Beig, Avital; Lindley, David; Miller, Jonathan M

2016-06-01

Poor aqueous solubility is a major challenge in today's biopharmaceutics. While solubility-enabling formulations can significantly increase the apparent solubility of the drug, the concomitant effect on the drug's apparent permeability has been largely overlooked. The mathematical equation to describe the membrane permeability of a drug comprises the membrane/aqueous partition coefficient, which in turn is dependent on the drug's apparent solubility in the GI milieu, suggesting that the solubility and the permeability are closely related, exhibit a certain interplay between them, and treating the one irrespectively of the other may be insufficient. In this article, an overview of this solubility-permeability interplay is provided, and the available data is analyzed in the context of the effort to maximize the overall drug exposure. Overall, depending on the type of solubility-permeability interplay, the permeability may decrease, remain unchanged, and even increase, in a way that may critically affect the formulation capability to improve the overall absorption. Therefore, an intelligent design of solubility-enabling formulation needs to consider both the solubility afforded by the formulation and the permeability in the new luminal environment resulting from the formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Statistical investigation of simulated intestinal fluid composition on the equilibrium solubility of biopharmaceutics classification system class II drugs.

PubMed

Khadra, Ibrahim; Zhou, Zhou; Dunn, Claire; Wilson, Clive G; Halbert, Gavin

2015-01-25

A drug's solubility and dissolution behaviour within the gastrointestinal tract is a key property for successful administration by the oral route and one of the key factors in the biopharmaceutics classification system. This property can be determined by investigating drug solubility in human intestinal fluid (HIF) but this is difficult to obtain and highly variable, which has led to the development of multiple simulated intestinal fluid (SIF) recipes. Using a statistical design of experiment (DoE) technique this paper has investigated the effects and interactions on equilibrium drug solubility of seven typical SIF components (sodium taurocholate, lecithin, sodium phosphate, sodium chloride, pH, pancreatin and sodium oleate) within concentration ranges relevant to human intestinal fluid values. A range of poorly soluble drugs with acidic (naproxen, indomethacin, phenytoin, and piroxicam), basic (aprepitant, carvedilol, zafirlukast, tadalafil) or neutral (fenofibrate, griseofulvin, felodipine and probucol) properties have been investigated. The equilibrium solubility results determined are comparable with literature studies of the drugs in either HIF or SIF indicating that the DoE is operating in the correct space. With the exception of pancreatin, all of the factors individually had a statistically significant influence on equilibrium solubility with variations in magnitude of effect between the acidic and basic or neutral compounds and drug specific interactions were evident. Interestingly for the neutral compounds pH was the factor with the second largest solubility effect. Around one third of all the possible factor combinations showed a significant influence on equilibrium solubility with variations in interaction significance and magnitude of effect between the acidic and basic or neutral compounds. The least number of significant media component interactions were noted for the acidic compounds with three and the greatest for the neutral compounds at seven, with again drug specific effects evident. This indicates that a drug's equilibrium solubility in SIF is influenced depending upon drug type by between eight to fourteen individual or combinations of media components with some of these drug specific. This illustrates the complex nature of these fluids and provides for individual drugs a visualisation of the possible solubility envelope within the gastrointestinal tract, which may be of importance for modelling in vivo behaviour. In addition the results indicate that the design of experiment approach can be employed to provide greater detail of drug solubility behaviour, possible drug specific interactions and influence of variations in gastrointestinal media components due to disease. The approach is also feasible and amenable to adaptation for high throughput screening of drug candidates. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular Dynamics Simulations of Hydration Effects on Solvation, Diffusivity, and Permeability in Chitosan/Chitin Films.

PubMed

McDonnell, Marshall T; Greeley, Duncan A; Kit, Kevin M; Keffer, David J

2016-09-01

The effects of hydration on the solvation, diffusivity, solubility, and permeability of oxygen molecules in sustainable, biodegradable chitosan/chitin food packaging films were studied via molecular dynamics and confined random walk simulations. With increasing hydration, the membrane has a more homogeneous water distribution with the polymer chains being fully solvated. The diffusivity increased by a factor of 4 for oxygen molecules and by an order of magnitude for water with increasing the humidity. To calculate the Henry's constant and solubility of oxygen in the membranes with changing hydration, the excess chemical potential was calculated via free energy perturbation, thermodynamic integration and direct particle deletion methods. The simulations predicted a higher solubility and permeability for the lower humidity, in contradiction to experimental results. All three methods for calculating the solubility were in good agreement. It was found that the Coulombic interactions in the potential caused the oxygen to bind too strongly to the protonated amine group. Insight from this work will help guide molecular modeling of chitosan/chitin membranes, specifically permeability measurements for small solute molecules. Efforts to chemically tailor chitosan/chitin membranes to favor discrete as opposed to continuous aqueous domains could reduce oxygen permeability.

Canine intestinal contents vs. simulated media for the assessment of solubility of two weak bases in the human small intestinal contents.

PubMed

Kalantzi, Lida; Persson, Eva; Polentarutti, Britta; Abrahamsson, Bertil; Goumas, Konstantinos; Dressman, Jennifer B; Reppas, Christos

2006-06-01

This study was conducted to assess the relative usefulness of canine intestinal contents and simulated media in the prediction of solubility of two weak bases (dipyridamole and ketoconazole) in fasted and fed human intestinal aspirates that were collected under conditions simulating those in bioavailability/bioequivalence studies. After administration of 250 mL of water or 500 mL of Ensure plus [both containing 10 mg/mL polyethylene glycol (PEG) 4000 as nonabsorbable marker], intestinal aspirates were collected from the fourth part of the duodenum of 12 healthy adults and from the mid-jejunum of four Labradors. Pooled samples were analyzed for PEG, pH, buffer capacity, osmolality, surface tension, pepsin, total carbohydrates, total protein content, bile salts, phospholipids, and neutral lipids. The shake-flask method was used to measure the solubility of dipyridamole and ketoconazole in pooled human and canine intestinal contents and in fasted-state-simulating intestinal fluid (FaSSIF) and fed-state-simulating intestinal fluid (FeSSIF) containing various bile salts and pH-buffering agents. For both compounds, solubility in canine contents may be predictive of human intralumenal solubility in the fasting state but not in the fed state. The poor agreement of results in canine and human aspirates can be attributed to the higher bile salt content in canine bile. Solubility in FaSSIF containing a mixture of bile salts from crude bile predicted satisfactorily the intralumenal solubility of both drugs in the fasted state in humans. Solubility in FeSSIF, regardless of the identity of bile salts or of the buffering species, deviated from intralumenal values in the fed human aspirates by up to 40%. This was attributed to the lack of lipolytic products in FeSSIF, the higher bile salt content of FeSSIF, and the lower pH of FeSSIF. FaSSIF containing a mixture of bile salts from crude bile, and FeSSIF containing lipolytic products and, perhaps, having lower bile salt content but slightly higher pH, should be more useful than canine intestinal aspirates for predicting intralumenal solubilities in humans.

Architecture for Absorption Based Heaters

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

Moghaddam, Saeed; Chugh, Devesh

An absorption based heater is constructed on a fluid barrier heat exchanging plate such that it requires little space in a structure. The absorption based heater has a desorber, heat exchanger, and absorber sequentially placed on the fluid barrier heat exchanging plate. The vapor exchange faces of the desorber and the absorber are covered by a vapor permeable membrane that is permeable to a refrigerant vapor but impermeable to an absorbent. A process fluid flows on the side of the fluid barrier heat exchanging plate opposite the vapor exchange face through the absorber and subsequently through the heat exchanger. Themore » absorption based heater can include a second plate with a condenser situated parallel to the fluid barrier heat exchanging plate and opposing the desorber for condensation of the refrigerant for additional heating of the process fluid.« less

Drug delivery strategies for poorly water-soluble drugs.

PubMed

Fahr, Alfred; Liu, Xiangli

2007-07-01

The drug candidates coming from combinatorial chemistry research and/or the drugs selected from biologically based high-throughput screening are quite often very lipophilic, as these drug candidates exert their pharmacological action at or in biological membranes or membrane-associated proteins. This challenges drug delivery institutions in industry or academia to develop carrier systems for the optimal oral and parenteral administration of these drugs. To mention only a few of the challenges for this class of drugs: their oral bioavailability is poor and highly variable, and carrier development for parenteral administration is faced with problems, including the massive use of surface-active excipients for solubilisation. Formulation specialists are confronted with an even higher level of difficulties when these drugs have to be delivered site specifically. This article addresses the emerging formulation designs for delivering of poorly water-soluble drugs.

Novel Ordered Crown Ether-Containing Polyimides for Ion Conduction

NASA Technical Reports Server (NTRS)

Irvin, Jennifer A.; Stasko, Daniel; Fallis, Stephen; Guenthner, Andrew J.; Webber, Cynthia; Blackwell, John; Chvalun, Sergei N.

2003-01-01

We report the synthesis and characterization of thermally-stable polyimides for use as battery and fuel cell electrolyte membranes. Dianhydrides used were 1,4,5,8- naphthalenetetracarboxylic dianhydride and/or 4,4'-(hexafluoroisopropylidene)diphthalic anhydride. Diamines used were anti-4,4-diaminodibenzo-l8-crown-6, 4,4'- diaminodibenzo-24-crown-8, 2,2-bis(4-aminophenyl)hexafluoropropane, and/or 2,5- diaminobenzenesulfonic acid. The polymers were characterized using electrochemical impedance spectroscopy (EIS), thermal analysis and X-ray diffraction. Polymers containing the hexafluoroisopropylidene (HFIP) group were soluble in common organic solvents, while polymers without the HFIP group were very poorly soluble. Sulfonation yields polymers that are sparingly soluble in aqueous base and/or methanol. Degree of sulfonation, determined by titration, was between one and three sulfonate groups per repeat unit. Proton conductivity was determined as a function of water content, with a maximum conductivity of l x 10(exp -2) per centimeter when fully hydrated. Crown ether-containing polymers exhibit a high degree of order that may be indicative of crown ether channel formation, which may facilitate Li(+) transport for use in battery membranes.

Myosin-1C uses a novel phosphoinositide-dependent pathway for nuclear localization.

PubMed

Nevzorov, Ilja; Sidorenko, Ekaterina; Wang, Weihuan; Zhao, Hongxia; Vartiainen, Maria K

2018-02-01

Accurate control of macromolecule transport between nucleus and cytoplasm underlines several essential biological processes, including gene expression. According to the canonical model, nuclear import of soluble proteins is based on nuclear localization signals and transport factors. We challenge this view by showing that nuclear localization of the actin-dependent motor protein Myosin-1C (Myo1C) resembles the diffusion-retention mechanism utilized by inner nuclear membrane proteins. We show that Myo1C constantly shuttles in and out of the nucleus and that its nuclear localization does not require soluble factors, but is dependent on phosphoinositide binding. Nuclear import of Myo1C is preceded by its interaction with the endoplasmic reticulum, and phosphoinositide binding is specifically required for nuclear import, but not nuclear retention, of Myo1C. Our results therefore demonstrate, for the first time, that membrane association and binding to nuclear partners is sufficient to drive nuclear localization of also soluble proteins, opening new perspectives to evolution of cellular protein sorting mechanisms. © 2018 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

Transdermal Delivery of Iron Using Soluble Microneedles: Dermal Kinetics and Safety.

PubMed

Modepalli, Naresh; Shivakumar, H Nanjappa; McCrudden, Maeliosa T C; Donnelly, Ryan F; Banga, Ajay; Murthy, S Narasimha

2016-03-01

Currently, the iron compounds are administered via oral and parenteral routes in patients of all ages, to treat iron deficiency. Despite continued efforts to supplement iron via these conventional routes, iron deficiency still remains the most prevalent nutritional disorder all over the world. Transdermal replenishment of iron is a novel, potential approach of iron replenishment. Ferric pyrophosphate (FPP) was found to be a suitable source of iron for transdermal replenishment. The safety of FPP was assessed in this project by challenging the dermal fibroblast cells with high concentration of FPP. The cell viability assay and reactive oxygen species assay were performed. The soluble microneedle array was developed, incorporated with FPP and the kinetics of free iron in the skin; extracellular fluid following dermal administration of microneedle array was investigated in hairless rats. From the cell based assays, FPP was selected as one of the potential iron sources for transdermal delivery. The microneedles were found to dissolve in the skin fluid within 3 hours of administration. The FPP concentration in the dermal extracellular fluid declined after complete dissolution of the microneedle array. Overall, the studies demonstrated the safety of FPP for dermal delivery and the feasibility of soluble microneedle approach for transdermal iron replenishment therapy. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

The effect of oxygen fugacity on the solubility of carbon-oxygen fluids in basaltic melt

NASA Technical Reports Server (NTRS)

Pawley, Alison R.; Holloway, John R.; Mcmillan, Paul F.

1992-01-01

The solubility of CO2-CO fluids in a midocean ridge basalt have been measured at 1200 C, 500-1500 bar, and oxygen fugacities between NNO and NNO-4. In agreement with results of previous studies, the results reported here imply that, at least at low pressures, CO2 dissolves in basaltic melt only in the form of carbonate groups. The dissolution reaction is heterogeneous, with CO2 molecules in the fluid reacting directly with reactive oxygens in the melt to produce CO3(2-). CO, on the other hand, is insoluble, dissolving neither as carbon, molecular CO, nor CO3(2-). It is shown that, for a given pressure and temperature, the concentration of dissolved carbon-bearing species in basaltic melt in equilibrium with a carbon-oxygen fluid is proportional to the mole fraction of CO2 in the fluid, which is a function of fO2. At low pressures CO2 solubility is a linear function of CO2 fugacity at constant temperatures.

Computer Simulations of Small Molecules in Membranes: Insights from Computer Simulations into the Interactions of Small Molecules with Lipid Bilayers

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; New, Michael H.; Schweighofer, Karl; Wilson, Michael A.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Two of Ernest Overton's lasting contributions to biology are the Meyer-Overton relationship between the potency of an anesthetic and its solubility in oil, and the Overton rule which relates the permeability of a membrane to the oil-water partition coefficient of the permeating molecule. A growing body of experimental evidence, however, cannot be reconciled with these theories. In particular, the molecular nature of membranes, unknown to Overton, needs to be included in any description of these phenomena. Computer simulations are ideally suited for providing atomic-level information about the behavior of small molecules in membranes. The authors discuss simulation studies relevant to Overton's ideas. Through simulations it was found that anesthetics tend to concentrate at interfaces and their anesthetic potency correlates better with solubility at the water-membrane interface than with solubility in oil. Simulation studies of membrane permeation revealed the anisotropic nature of the membranes, as evidenced, for example, by the highly nonuniform distribution of free volume in the bilayer. This, in turn, influences the diffusion rates of solutes, which increase with the depth in the membrane. Small solutes tend to move by hopping between voids in the bilayer, and this hopping motion may be responsible for the deviation from the Overton rule of the permeation rates of these molecules.

Fouling potential evaluation of soluble microbial products (SMP) with different membrane surfaces in a hybrid membrane bioreactor using worm reactor for sludge reduction.

PubMed

Li, Zhipeng; Tian, Yu; Ding, Yi; Chen, Lin; Wang, Haoyu

2013-07-01

The fouling characteristics of soluble microbial products (SMP) in the membrane bioreactor coupled with Static Sequencing Batch Worm Reactor (SSBWR-MBR) were tested with different types of membranes. It was noted that the flux decrements of S-SMP (SMP in SSBWR-MBR) with cellulose acetate (CA), polyvinylidene fluoride (PVDF) and polyether sulfones (PES) membranes were respectively 6.7%, 8.5% and 9.5% lower compared to those of C-SMP (SMP in Control-MBR) with corresponding membranes. However, for both the filtration of the C-SMP and S-SMP, the CA membrane exhibited the fastest diminishing rate of flux among the three types of membranes. The surface morphology analysis showed that the CA membrane exhibited more but smaller protuberances compared to the PVDF and PES. The second minimums surrounding each protruding asperity on CA membrane were more than those on the PVDF and PES membranes, enhancing the attachment of SMP onto the membrane surface. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rationalising polymer selection for supersaturated film forming systems produced by an aerosol spray for the transdermal delivery of methylphenidate.

PubMed

Edwards, A; Qi, S; Liu, F; Brown, M B; McAuley, W J

2017-05-01

Film forming systems offer a number of advantages for topical and transdermal drug delivery, in particular enabling production of a supersaturated state which can greatly improve drug absorption and bioavailability. However the suitability of individual film forming polymers to stabilise the supersaturated state and optimise delivery of drugs is not well understood. This study reports the use of differential scanning calorimetry (DSC) to measure the solubility of methylphenidate both as the free base and as the hydrochloride salt in two polymethacrylate copolymers, Eudragit RS (EuRS) and Eudragit E (EuE) and relates this to the ability of films formed using these polymers to deliver methylphenidate across a model membrane. EuRS provided greater methylphenidate delivery when the drug was formulated as the free base in comparison EuE because the lower solubility of the drug in EuRS provided a higher degree of drug saturation in the polymeric film. In contrast EuE provided greater delivery of methylphenidate hydrochloride as EuRS could not prevent its crystallisation from a supersaturated state. Methylphenidate flux across the membrane could be directly related to degree of saturation of the drug in the film formulation as estimated by the drug solubility in the individual polymers demonstrating the importance of drug solubility in the polymer included in film forming systems for topical/transdermal drug delivery. In addition DSC has been demonstrated to be a useful tool for determining the solubility of drugs in polymers used in film forming systems and the approaches outlined here are likely to be useful for predicting the suitability of polymers for particular drugs in film forming transdermal drug delivery systems. Copyright © 2017. Published by Elsevier B.V.

Variation in Extracellular Detoxification Is a Link to Different Carcinogenicity among Chromates in Rodent and Human Lungs.

PubMed

Krawic, Casey; Luczak, Michal W; Zhitkovich, Anatoly

2017-09-18

Inhalation of soluble chromium(VI) is firmly linked with higher risks of lung cancer in humans. However, comparative studies in rats have found a high lung tumorigenicity for moderately soluble chromates but no tumors for highly soluble chromates. These major species differences remain unexplained. We investigated the impact of extracellular reducers on responses of human and rat lung epithelial cells to different Cr(VI) forms. Extracellular reduction of Cr(VI) is a detoxification process, and rat and human lung lining fluids contain different concentrations of ascorbate and glutathione. We found that reduction of chromate anions in simulated lung fluids was principally driven by ascorbate with only minimal contribution from glutathione. The addition of 500 μM ascorbate (∼rat lung fluid concentration) to culture media strongly inhibited cellular uptake of chromate anions and completely prevented their cytotoxicity even at otherwise lethal doses. While proportionally less effective, 50 μM extracellular ascorbate (∼human lung fluid concentration) also decreased uptake of chromate anions and their cytotoxicity. In comparison to chromate anions, uptake and cytotoxicity of respirable particles of moderately soluble CaCrO 4 and SrCrO 4 were much less sensitive to suppression by extracellular ascorbate, especially during early exposure times and in primary bronchial cells. In the absence of extracellular ascorbate, chromate anions and CaCrO 4 /SrCrO 4 particles produced overall similar levels of DNA double-stranded breaks, with less soluble particles exhibiting a slower rate of breakage. Our results indicate that a gradual extracellular dissolution and a rapid internalization of calcium chromate and strontium chromate particles makes them resistant to detoxification outside the cells, which is extremely effective for chromate anions in the rat lung fluid. The detoxification potential of the human lung fluid is significant but much lower and insufficient to provide a threshold-type dose dependence for soluble chromates.

Bidirectional Transformation of a Metamorphic Protein between the Water-Soluble and Transmembrane Native States.

PubMed

Tanaka, Koji; Caaveiro, Jose M M; Tsumoto, Kouhei

2015-11-24

The bidirectional transformation of a protein between its native water-soluble and integral transmembrane conformations is demonstrated for FraC, a hemolytic protein of the family of pore-forming toxins. In the presence of biological membranes, the water-soluble conformation of FraC undergoes a remarkable structural reorganization generating cytolytic transmembrane nanopores conducive to cell death. So far, the reverse transformation from the native transmembrane conformation to the native water-soluble conformation has not been reported. We describe the use of detergents with different physicochemical properties to achieve the spontaneous conversion of transmembrane pores of FraC back into the initial water-soluble state. Thermodynamic and kinetic stability data suggest that specific detergents cause an asymmetric change in the energy landscape of the protein, allowing the bidirectional transformation of a membrane protein.

Premature rupture of membranes

MedlinePlus

... is fluid leaking from the vagina. It may leak slowly, or it may gush out. Some of ... the membranes break. The membranes may continue to leak. Sometimes when fluid leaks out slowly, women mistake ...

Soluble adenylyl cyclase is an acid-base sensor in epithelial base-secreting cells.

PubMed

Roa, Jinae N; Tresguerres, Martin

2016-08-01

Blood acid-base regulation by specialized epithelia, such as gills and kidney, requires the ability to sense blood acid-base status. Here, we developed primary cultures of ray (Urolophus halleri) gill cells to study mechanisms for acid-base sensing without the interference of whole animal hormonal regulation. Ray gills have abundant base-secreting cells, identified by their noticeable expression of vacuolar-type H(+)-ATPase (VHA), and also express the evolutionarily conserved acid-base sensor soluble adenylyl cyclase (sAC). Exposure of cultured cells to extracellular alkalosis (pH 8.0, 40 mM HCO3 (-)) triggered VHA translocation to the cell membrane, similar to previous reports in live animals experiencing blood alkalosis. VHA translocation was dependent on sAC, as it was blocked by the sAC-specific inhibitor KH7. Ray gill base-secreting cells also express transmembrane adenylyl cyclases (tmACs); however, tmAC inhibition by 2',5'-dideoxyadenosine did not prevent alkalosis-dependent VHA translocation, and tmAC activation by forskolin reduced the abundance of VHA at the cell membrane. This study demonstrates that sAC is a necessary and sufficient sensor of extracellular alkalosis in ray gill base-secreting cells. In addition, this study indicates that different sources of cAMP differentially modulate cell biology. Copyright © 2016 the American Physiological Society.

The role of carbon dioxide in the transport and fractionation of metals by geological fluids

NASA Astrophysics Data System (ADS)

Kokh, Maria A.; Akinfiev, Nikolay N.; Pokrovski, Gleb S.; Salvi, Stefano; Guillaume, Damien

2017-01-01

Although carbon dioxide is one of the major components of crustal fluids responsible for ore deposit formation, its effect on transport and precipitation of metals remains unknown, due to a lack of direct experimental data and physical-chemical models for CO2-rich fluids. To fill this gap, we combined laboratory experiments and thermodynamic modeling to systematically quantify the role played by CO2 for the solubility of economically important metals such as Fe, Cu, Zn, Au, Mo, Pt, Sn under hydrothermal conditions. Solubility measurements of common ore minerals of these metals (FeS2, CuFeS2, ZnS, Au, MoS2, PtS, SnO2) were performed, using a flexible-cell reactor equipped with a rapid sampling device, in a single-phase fluid (CO2-H2O-KCl) at 350-450 °C and 600-750 bar, buffered with iron sulfide and oxide and alkali-aluminosilicate mineral assemblages. In addition, another type of experiments was conducted to measure gold solubility in more sulfur-rich supercritical CO2-H2O-S-NaOH fluids at 450 °C and 700 bar using a batch reactor that allows fluid quenching. Our results show that the solubilities of Si, Au, Mo, Pt and Cu either decrease (within <1 log unit) or remain constant upon CO2 increase, whereas those of Fe, Zn and Sn increase significantly (>1 log unit) with CO2 contents in the fluid increasing from 0 to 50 wt%. These data were interpreted using a simple model that does not require any new adjustable parameters, and is based on the dielectric constant of the H2O-CO2 solvent and on the Born solvation parameter for the dominant metal-bearing species in an aqueous fluid. Our predictions using this model suggest that in a supercritical CO2-H2O-S-salt fluid typical of metamorphic Au deposits, in equilibrium with pyrite and chalcopyrite, the Cu/Fe ratio decreases by up to 2 orders of magnitude with an increase of CO2 content from 0 to 70 wt%. This effect is due to the decrease of the fluid dielectric constant in the presence of CO2, which favors the stability of neutral species (FeCl20) compared to charged ones (CuCl2-). Our results explain the Fe enrichment and Cu depletion in metamorphic gold deposits formed by CO2-rich fluids. The transport of gold is unfavorable in the presence of CO2 only in S-rich (>0.5 wt% S) fluids in which Au forms the negatively charged Au(HS)2- and Au(HS)S3- complexes. By contrast, it is only weakly affected in S-poor (<0.1 wt% S) acidic-to-neutral fluids in which the uncharged Au(HS)0 complex predominates. Thus, even at very high CO2 contents (>50 wt% CO2), the capacity of such fluids to transport gold (up to 100s ppb Au) remains comparable to that of aqueous fluids. These findings are in agreement with analyses of natural fluid inclusions in metamorphic deposits. In more saline oxidizing and S-rich fluids such as those in magmatic porphyry Cu-Au deposits, the Fe, Cu, and Au solubilities in the presence of CO2 decrease by ∼1 order of magnitude with CO2 increasing to 20-30 wt%, following the decrease in the stability of their dominant charged species (FeCl42-, CuCl2-, Au(HS)2- and Au(HS)S3-), but stay almost constant at higher CO2 contents (30-70 wt%) as controlled by the neutral species (FeCl20, Cu(HS)0 and Au(HS)0). Such solubility trends suggest a new potential trigger of ore precipitation in porphyry systems by CO2 pulses from the magmatic chamber, which may operate along with commonly admitted depositional mechanisms such as cooling, vapor-brine immiscibility, and water-rock interaction. The direct effect of CO2 on the mobility of Pt and Mo, metals that likely form hydrogen sulfide and oxy-hydroxide complexes, respectively, is expected to be weak in most settings. Among the studied elements, Sn is the only one whose solubility may be favored at high CO2 content (>20 wt%) due to carbonate complexing. This study demonstrates, for the first time, that, contrary to common belief, the presence of CO2 in a supercritical fluid may lead to enhanced mobility or, on contrary, to massive precipitation of some metals, depending on salinity and sulfur content, and, more generally, to significant fractionations between different metals.

Properties of the glucose phosphotransferase system of Clostridium acetobutylicum NCIB 8052

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

Mitchell, W.J.; Shaw, J.E.; Andrews, L.

1991-09-01

Acetone-butanol-ethanol fermentation by Clostridium acetobutylicum has been exploited on an industrial scale in the past, but for economic reasons the process has declined. However, with an increased understanding of solvent formation and the potential for genetic manipulation of the organism, this fermentation is once again receiving attention. An economical process would be founded on the use of cheap, renewable substrates, ideally carbohydrate-based waste materials. However, little is known about the mechanism and regulation of carbohydrate accumulation by C. acetobutylicum. The glucose phosphotransferase system (PTS) of C. acetobutylicum was studied by using cell extracts. The system exhibited a K{sub m} formore » glucose of 34 {mu}M, and glucose phosphorylation was inhibited competitively by mannose and 2-deoxyglucose. The analogs 3-O-methylglucoside and methyl {alpha}-glucoside did not inhibit glucose phosphorylation significantly. Activity showed no dependence on Mg{sup 2+} ions or on pH in the range 6.0 to 8.0. The PTS comprised both soluble and membrane-bound proteins, which interacted functionally with the PTSs of Clostridium pasteurianum, Bacillus subtilis, and Escherichia coli. In addition to a membrane-bound enzyme II{sup Glc}, sugar phosphorylation assays in heterologous systems incorporating extracts of pts mutants of other organisms provided evidence for enzyme I, HPr, and III{sup Glc} components. The HPr was found in the soluble fraction of C. acetobutylicum extracts, whereas enzyme I, and probably also III{sup Glc}, was present in both the soluble and membrane fractions, suggesting a membrane location in the intact cell.« less

Motion through a non-homogeneous porous medium: Hydrodynamic permeability of a membrane composed of cylindrical particles

NASA Astrophysics Data System (ADS)

Yadav, Pramod Kumar

2018-01-01

The present problem is concerned with the flow of a viscous steady incompressible fluid through a non-homogeneous porous medium. Here, the non-homogeneous porous medium is a membrane built up by cylindrical particles. The flow outside the membrane is governed by the Stokes equation and the flow through the non-homogeneous porous membrane composed by cylindrical particles is governed by Darcy's law. In this work, we discussed the effect of various fluid parameters like permeability parameter k0, discontinuity coefficient at fluid-non homogeneous porous interface, viscosity ratio of viscous incompressible fluid region and non-homogeneous porous region, etc. on hydrodynamic permeability of a membrane, stress and on velocity profile. The comparative study for hydrodynamic permeability of membrane built up by non-homogeneous porous cylindrical particles and porous cylindrical shell enclosing a cylindrical cavity has been studied. The effects of various fluid parameters on the streamlines flow patterns are also discussed.

Lipid-protein nanodiscs for cell-free production of integral membrane proteins in a soluble and folded state: comparison with detergent micelles, bicelles and liposomes.

PubMed

Lyukmanova, E N; Shenkarev, Z O; Khabibullina, N F; Kopeina, G S; Shulepko, M A; Paramonov, A S; Mineev, K S; Tikhonov, R V; Shingarova, L N; Petrovskaya, L E; Dolgikh, D A; Arseniev, A S; Kirpichnikov, M P

2012-03-01

Production of integral membrane proteins (IMPs) in a folded state is a key prerequisite for their functional and structural studies. In cell-free (CF) expression systems membrane mimicking components could be added to the reaction mixture that promotes IMP production in a soluble form. Here lipid-protein nanodiscs (LPNs) of different lipid compositions (DMPC, DMPG, POPC, POPC/DOPG) have been compared with classical membrane mimicking media such as detergent micelles, lipid/detergent bicelles and liposomes by their ability to support CF synthesis of IMPs in a folded and soluble state. Three model membrane proteins of different topology were used: homodimeric transmembrane (TM) domain of human receptor tyrosine kinase ErbB3 (TM-ErbB3, 1TM); voltage-sensing domain of K(+) channel KvAP (VSD, 4TM); and bacteriorhodopsin from Exiguobacterium sibiricum (ESR, 7TM). Structural and/or functional properties of the synthesized proteins were analyzed. LPNs significantly enhanced synthesis of the IMPs in a soluble form regardless of the lipid composition. A partial disintegration of LPNs composed of unsaturated lipids was observed upon co-translational IMP incorporation. Contrary to detergents the nanodiscs resulted in the synthesis of ~80% active ESR and promoted correct folding of the TM-ErbB3. None of the tested membrane mimetics supported CF synthesis of correctly folded VSD, and the protocol of the domain refolding was developed. The use of LPNs appears to be the most promising approach to CF production of IMPs in a folded state. NMR analysis of (15)N-Ile-TM-ErbB3 co-translationally incorporated into LPNs shows the great prospects of this membrane mimetics for structural studies of IMPs produced by CF systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same

NASA Technical Reports Server (NTRS)

Cisar, Alan J. (Inventor); Murphy, Oliver J. (Inventor); Gonzalez-Martin, Anuncia (Inventor); Hitchens, G. Duncan (Inventor)

1997-01-01

The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface, an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane for purposes of hydration.

Overcoming bottlenecks in the membrane protein structural biology pipeline.

PubMed

Hardy, David; Bill, Roslyn M; Jawhari, Anass; Rothnie, Alice J

2016-06-15

Membrane proteins account for a third of the eukaryotic proteome, but are greatly under-represented in the Protein Data Bank. Unfortunately, recent technological advances in X-ray crystallography and EM cannot account for the poor solubility and stability of membrane protein samples. A limitation of conventional detergent-based methods is that detergent molecules destabilize membrane proteins, leading to their aggregation. The use of orthologues, mutants and fusion tags has helped improve protein stability, but at the expense of not working with the sequence of interest. Novel detergents such as glucose neopentyl glycol (GNG), maltose neopentyl glycol (MNG) and calixarene-based detergents can improve protein stability without compromising their solubilizing properties. Styrene maleic acid lipid particles (SMALPs) focus on retaining the native lipid bilayer of a membrane protein during purification and biophysical analysis. Overcoming bottlenecks in the membrane protein structural biology pipeline, primarily by maintaining protein stability, will facilitate the elucidation of many more membrane protein structures in the near future. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Interaction of Corundum, Wollastonite and Quartz With H2O-NaCl Solutions at 800 C and 10 Kbar

NASA Astrophysics Data System (ADS)

Newton, R. C.; Manning, C. E.

2005-12-01

Aqueous fluids are potentially important transport agents in subduction zones and other high-P metamorphic environments. Recent studies indicate that at high P and T, the solubilities of major rock-forming elements are strongly enhanced by the formation of metal-chloride complexes, metal-hydroxide complexes and polynuclear metal-hydroxide clusters. However, the relative abundances of these species and the energetics of their interactions in high-pressure environments remains largely unknown. We measured the solubilities of corundum (Al2O3) and wollastonite (CaSiO3) at 800 °C and 10 kbar in H2O-NaCl solutions to halite saturation (XNaCl = 0.6) . Both minerals show marked enhancement of solubility with increasing salinity. Al2O3 mol fraction rises rapidly to XNaCl = 0.1, and then declines slowly towards halite saturation. Quenched experimental fluids have neutral pH. Modeling based on ideal solution of ions and molecules leads to a simple dissolution reaction and corresponding molality (m=mol/kg H2O) expression: Al2O3(cor) + Na+ + 3H2O = NaAl(OH)4 + Al(OH)2+ and mAl2O3 = [0.0232(aNaCl)1/4(aH2O)3/2+0.00123][1+2XNaCl/(1-XNaCl)] where H2O and NaCl activities are given by aH2O = (2-XNaCl)/(2+XNaCl) and aNaCl = 4(XNaCl)2/(1 + XNaCl)2. Wollastonite solubility in NaCl solutions is accurately described by: mCaSiO3 = 0.6734XNaCl + 0.1183(XNaCl)1/2 + 0.0204. There is a roughly 50-fold enhancement of dissolved wollastonite at halite saturation. Quenched experimental fluids are strongly basic (pH=11). A consistent dissolution reaction must therefore be similar to: CaSiO3(wo) + Na+ + Cl- = CaCl+ + OH- + HNaSiO3 Quartz solubility declines monotonically from mSiO2 = 1.248 in pure H2O to 0.20 at halite saturation. Quenched fluids are neutral, indicating that quartz does not react with solvent NaCl. The only salinity control on solubility is decrease of H2O activity. The simple dissolution behaviors to be deduced from measurements on these minerals suggest that fluid-rock interaction in deep-crust/upper mantle metamorphic processes may be generally understandable in terms of quasi-ideal mixing models.

A Circular Dichroism Reference Database for Membrane Proteins

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

Wallace,B.; Wien, F.; Stone, T.

2006-01-01

Membrane proteins are a major product of most genomes and the target of a large number of current pharmaceuticals, yet little information exists on their structures because of the difficulty of crystallising them; hence for the most part they have been excluded from structural genomics programme targets. Furthermore, even methods such as circular dichroism (CD) spectroscopy which seek to define secondary structure have not been fully exploited because of technical limitations to their interpretation for membrane embedded proteins. Empirical analyses of circular dichroism (CD) spectra are valuable for providing information on secondary structures of proteins. However, the accuracy of themore » results depends on the appropriateness of the reference databases used in the analyses. Membrane proteins have different spectral characteristics than do soluble proteins as a result of the low dielectric constants of membrane bilayers relative to those of aqueous solutions (Chen & Wallace (1997) Biophys. Chem. 65:65-74). To date, no CD reference database exists exclusively for the analysis of membrane proteins, and hence empirical analyses based on current reference databases derived from soluble proteins are not adequate for accurate analyses of membrane protein secondary structures (Wallace et al (2003) Prot. Sci. 12:875-884). We have therefore created a new reference database of CD spectra of integral membrane proteins whose crystal structures have been determined. To date it contains more than 20 proteins, and spans the range of secondary structures from mostly helical to mostly sheet proteins. This reference database should enable more accurate secondary structure determinations of membrane embedded proteins and will become one of the reference database options in the CD calculation server DICHROWEB (Whitmore & Wallace (2004) NAR 32:W668-673).« less

Enhanced Aqueous Solubility of Long Wavelength Voltage-Sensitive Dyes by Covalent Attachment of Polyethylene Glycol

PubMed Central

Patrick, Michael J.; Ernst, Lauren A.; Waggoner, Alan S.; Thai, Dung; Salama, Guy

2011-01-01

Long wavelength voltage-sensitive dyes (VSDs) called Pittsburgh (PGH) dyes were recently synthesized by coupling various heterocyclic groups to a styryl-thiophene intermediate forming extended, partially rigidized chromophores. Unlike most styryl VSDs, dyes with a sulfonic acid anchor directly attached to the chromophore showed no solvatochromic absorption shifts. The limited water solubility of many long wavelength VSDs requires the use of surfactants to transport the dye through aqueous media and effectively label biological membranes. Here, we tested the chemical substitution of the sulfonic acid moiety with polyethyleneglycol (PEG) chains ranging from MW 750 to 5000, to overcome the poor solubility of VSDs while retaining their properties as VSDs. The chemical synthesis of PGH dyes and their PEG derivatives are described. The PEG-derivatives were soluble in aqueous solutions (> 1 mM) and still reported membrane potential changes. In frog and mouse hearts, the voltage sensitivity (ΔF/F per action potential) and spectral properties of PEG dyes were the same as the sulfonated analogs. Thus, the solubility of VSDs can be considerably improved with small polyethyleneglycol chains and can provide an effective approach to improve staining of excitable tissues and optical recordings of membrane potential. PMID:17912389

Chymase Cleavage of Stem Cell Factor Yields a Bioactive, Soluble Product

NASA Astrophysics Data System (ADS)

Longley, B. Jack; Tyrrell, Lynda; Ma, Yongsheng; Williams, David A.; Halaban, Ruth; Langley, Keith; Lu, Hsieng S.; Schechter, Norman M.

1997-08-01

Stem cell factor (SCF) is produced by stromal cells as a membrane-bound molecule, which may be proteolytically cleaved at a site close to the membrane to produce a soluble bioactive form. The proteases producing this cleavage are unknown. In this study, we demonstrate that human mast cell chymase, a chymotrypsin-like protease, cleaves SCF at a novel site. Cleavage is at the peptide bond between Phe-158 and Met-159, which are encoded by exon 6 of the SCF gene. This cleavage results in a soluble bioactive product that is 7 amino acids shorter at the C terminus than previously identified soluble SCF. This research shows the identification of a physiologically relevant enzyme that specifically cleaves SCF. Because mast cells express the KIT protein, the receptor for SCF, and respond to SCF by proliferation and degranulation, this observation identifies a possible feedback loop in which chymase released from mast cell secretory granules may solubilize SCF bound to the membrane of surrounding stromal cells. The liberated soluble SCF may in turn stimulate mast cell proliferation and differentiated functions; this loop could contribute to abnormal accumulations of mast cells in the skin and hyperpigmentation at sites of chronic cutaneous inflammation.

Effects of recombinant protein misfolding and aggregation on bacterial membranes.

PubMed

Ami, D; Natalello, A; Schultz, T; Gatti-Lafranconi, P; Lotti, M; Doglia, S M; de Marco, A

2009-02-01

The expression of recombinant proteins is known to induce a metabolic rearrangement in the host cell. We used aggregation-sensitive model systems to study the effects elicited in Escherichia coli cells by the aggregation of recombinant glutathione-S-transferase and its fusion with the green fluorescent protein that, according to the expression conditions, accumulate intracellularly as soluble protein, or soluble and insoluble aggregates. We show that the folding state of the recombinant protein and the complexity of the intracellular aggregates critically affect the cell response. Specifically, protein misfolding and aggregation induce changes in specific host proteins involved in lipid metabolism and oxidative stress, a reduction in the membrane permeability, as well as a rearrangement of its lipid composition. The temporal evolution of the host cell response and that of the aggregation process pointed out that the misfolded protein and soluble aggregates are responsible for the membrane modifications and the changes in the host protein levels. Interestingly, native recombinant protein and large insoluble aggregates do not seem to activate stress markers and membrane rearrangements.

Effect of sparging rate on permeate quality in a submerged anaerobic membrane bioreactor (SAMBR) treating leachate from the organic fraction of municipal solid waste (OFMSW).

PubMed

Trzcinski, Antoine P; Stuckey, David C

2016-03-01

This paper focuses on the treatment of leachate from the organic fraction of municipal solid waste (OFMSW) in a submerged anaerobic membrane bioreactor (SAMBR). Operation of the SAMBR for this type of high strength wastewater was shown to be feasible at 5 days hydraulic retention time (HRT), 10 L min(-1) (LPM) biogas sparging rate and membrane fluxes in the range of 3-7 L m(-2) hr(-1) (LMH). Under these conditions, more than 90% COD removal was achieved during 4 months of operation without chemical cleaning the membrane. When the sparging rate was reduced to 2 LPM, the transmembrane pressure increased dramatically and the bulk soluble COD concentration increased due to a thicker fouling layer, while permeate soluble COD remained constant. Permeate soluble COD concentration increased by 20% when the sparging rate increased to 10 LPM. Copyright © 2015 Elsevier Ltd. All rights reserved.

Wheat germ cell-free expression: Two detergents with a low critical micelle concentration allow for production of soluble HCV membrane proteins.

PubMed

Fogeron, Marie-Laure; Badillo, Aurélie; Jirasko, Vlastimil; Gouttenoire, Jérôme; Paul, David; Lancien, Loick; Moradpour, Darius; Bartenschlager, Ralf; Meier, Beat H; Penin, François; Böckmann, Anja

2015-01-01

Membrane proteins are notoriously difficult to express in a soluble form. Here, we use wheat germ cell-free expression in the presence of various detergents to produce the non-structural membrane proteins 2, 4B and 5A of the hepatitis C virus (HCV). We show that lauryl maltose neopentyl glycol (MNG-3) and dodecyl octaethylene glycol ether (C12E8) detergents can yield essentially soluble membrane proteins at detergent concentrations that do not inhibit the cell-free reaction. This finding can be explained by the low critical micelle concentration (CMC) of these detergents, which keeps the monomer concentrations low while at the same time providing the necessary excess of detergent concentration above CMC required for full target protein solubilization. We estimate that a tenfold excess of detergent micelles with respect to the protein concentration is sufficient for solubilization, a number that we propose as a guideline for detergent screening assays. Copyright © 2014 Elsevier Inc. All rights reserved.

[Dialysate and biocompatibility in hemodialysis].

PubMed

Berland, Y

1998-01-01

This article summarise the main data in the literature on the role of bacteriological contamination of the dialysate fluid in inflammatory reactions in hemodialysis. Pyrogenic substances of small molecular weight from Gram-negative bacteria grown in dialysate can pass across intact dialyzer membrane to stimulate cytokine production by peripheral blood mononuclear cells. Cellulosic hemodialysis membranes are more permeable to endotoxins than synthetic membranes. Polysulfone membranes and polyamide membranes are able to adsorb bacterial toxins on the dialysate side. The diffusive transfer of bacterial products across dialysis membrane from dialysate fluid was demonstrated. Transmembrane passage of cytokine-inducing bacterial products across reprocessed dialyzers is greater than across new dialyzers. Bacteriological contamination of the dialysate fluid is a problem which must be considered with much more care by nephrologists, especially as LAL test is unable to detect all the bacterial products which can contaminate the dialysate fluid.

Hydrogen Production by a Hyperthermophilic Membrane-Bound Hydrogenase in Soluble Nanolipoprotein Particles

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

Baker, S E; Hopkins, R C; Blanchette, C

Hydrogenases constitute a promising class of enzymes for ex vivo hydrogen production. Implementation of such applications is currently hindered by oxygen sensitivity and, in the case of membrane-bound hydrogenases (MBH), poor water solubility. Nanolipoprotein particles (NLPs), formed from apolipoproteins and phospholipids, offer a novel means to incorporate MBH into in a well-defined water-soluble matrix that maintains the enzymatic activity and is amenable to incorporation into more complex architectures. We report the synthesis, hydrogen-evolving activity and physical characterization of the first MBH-NLP assembly. This may ultimately lead to the development of biomimetic hydrogen production devices.

New water-soluble metal working fluids additives from phosphonic acid derivatives for aluminum alloy materials.

PubMed

Kohara, Ichitaro; Tomoda, Hideyuki; Watanabe, Shoji

2007-01-01

Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short paper describes properties of new additives for water-soluble cutting fluids for aluminum alloy materials. Some alkyldiphosphonic acids were prepared with known method. Amine salts of these phosphonic acids showed anti-corrosion property for aluminum alloy materials. However, they have no hard water tolerance. Monoesters of octylphosphonic acid were prepared by the reaction of octylphosphonic acid dichloride with various alcohols in the presence of triethylamine. Amine salts of monoester of octylphosphonic acid with diethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether and triethyleneglycol monomethyl ether showed both of a good anti-corrosion property for aluminum alloy materials and hard water tolerance.

Exploiting the Phenomenon of Liquid-Liquid Phase Separation for Enhanced and Sustained Membrane Transport of a Poorly Water-Soluble Drug.

PubMed

Indulkar, Anura S; Gao, Yi; Raina, Shweta A; Zhang, Geoff G Z; Taylor, Lynne S

2016-06-06

Recent studies on aqueous supersaturated lipophilic drug solutions prepared by methods including antisolvent addition, pH swing, or dissolution of amorphous solid dispersions (ASDs) have demonstrated that when crystallization is slow, these systems undergo liquid-liquid phase separation (LLPS) when the concentration of the drug in the medium exceeds its amorphous solubility. Following LLPS, a metastable equilibrium is formed where the concentration of drug in the continuous phase corresponds to the amorphous solubility while the dispersed phase is composed of a nanosized drug-rich phase. It has been reasoned that the drug-rich phase may act as a reservoir, enabling the rate of passive transport of the drug across a membrane to be maintained at the maximum value for an extended period of time. Herein, using clotrimazole as a model drug, and a flow-through diffusion cell, the reservoir effect is demonstrated. Supersaturated clotrimazole solutions at concentrations below the amorphous solubility show a linear relationship between the maximum flux and the initial concentration. Once the concentration exceeds the amorphous solubility, the maximum flux achieved reaches a plateau. However, the duration for which the high flux persists was found to be highly dependent on the number of drug-rich nanodroplets present in the donor compartment. Macroscopic amorphous particles of clotrimazole did not lead to the same reservoir effect observed with the nanodroplets formed through the process of LLPS. A first-principles mathematical model was developed which was able to fit the experimental receiver concentration-time profiles for concentration regimes both below and above amorphous solubility, providing support for the contention that the nanodroplet phase does not directly diffuse across the membrane but, instead, rapidly replenishes the drug in the aqueous phase that has been removed by transport across the membrane. This study provides important insight into the properties of supersaturated solutions and how these might in turn impact oral absorption through effects on passive membrane transport rates.

Stabilization of NaCl-containing cuttings wastes in cement concrete by in situ formed mineral phases.

PubMed

Filippov, Lev; Thomas, Fabien; Filippova, Inna; Yvon, Jacques; Morillon-Jeanmaire, Anne

2009-11-15

Disposal of NaCl-containing cuttings is a major environmental concern due to the high solubility of chlorides. The present work aims at reducing the solubility of chloride by encapsulation in low permeability matrix as well as lowering its solubility by trapping into low-solubility phases. Both the studied materials were cuttings from an oil-based mud in oil drillings containing about 50% of halite, and cuttings in water-based mud from gas drilling containing 90% of halite. A reduction in the amount of dissolved salt from 41 to 19% according to normalized leaching tests was obtained by addition of potassium ortho-phosphate in the mortar formula of oil-based cuttings, while the aluminium dihydrogeno-phosphate is even more efficient for the stabilization of water-based cuttings with a NaCl content of 90%. Addition of ortho-phosphate leads to form a continuous and weakly soluble network in the cement matrix, which reduces the release of salt. The formed mineralogical phases were apatite and hydrocalumite. These phases encapsulate the salt grains within a network, thus lowering its interaction with water or/and trap chloride into low-solubility phases. The tested approaches allow to develop a confinement process of NaCl-containing waste of various compositions that can be applied to wastes, whatever the salt content and the nature of the drilling fluids (water or oil).

In Vitro Studies Evaluating Leaching of Mercury from Mine Waste Calcine Using Simulated Human Body Fluids

PubMed Central

2010-01-01

In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almadén, Spain, and Terlingua, Texas, contain Hg sulfide, elemental Hg, and soluble Hg compounds, which constitute primary ore or compounds formed during Hg retorting. Elevated leachate Hg concentrations were found during calcine leaching using a simulated gastric fluid (as much as 6200 μg of Hg leached/g sample). Elevated Hg concentrations were also found in calcine leachates using a simulated lung fluid (as much as 9200 μg of Hg leached/g), serum-based fluid (as much as 1600 μg of Hg leached/g), and water of pH 5 (as much as 880 μg of Hg leached/g). The leaching capacity of Hg is controlled by calcine mineralogy; thus, calcines containing soluble Hg compounds contain higher leachate Hg concentrations. Results indicate that ingestion or inhalation of Hg mine-waste calcine may lead to increased Hg concentrations in the human body, especially through the ingestion pathway. PMID:20491469

In vitro studies evaluating leaching of mercury from mine waste calcine using simulated human body fluids.

PubMed

Gray, John E; Plumlee, Geoffrey S; Morman, Suzette A; Higueras, Pablo L; Crock, James G; Lowers, Heather A; Witten, Mark L

2010-06-15

In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almaden, Spain, and Terlingua, Texas, contain Hg sulfide, elemental Hg, and soluble Hg compounds, which constitute primary ore or compounds formed during Hg retorting. Elevated leachate Hg concentrations were found during calcine leaching using a simulated gastric fluid (as much as 6200 microg of Hg leached/g sample). Elevated Hg concentrations were also found in calcine leachates using a simulated lung fluid (as much as 9200 microg of Hg leached/g), serum-based fluid (as much as 1600 microg of Hg leached/g), and water of pH 5 (as much as 880 microg of Hg leached/g). The leaching capacity of Hg is controlled by calcine mineralogy; thus, calcines containing soluble Hg compounds contain higher leachate Hg concentrations. Results indicate that ingestion or inhalation of Hg mine-waste calcine may lead to increased Hg concentrations in the human body, especially through the ingestion pathway.

In vitro studies evaluating leaching of mercury from mine waste calcine using simulated human body fluids

USGS Publications Warehouse

Gray, John E.; Plumlee, Geoffrey S.; Morman, Suzette A.; Higueras, Pablo L.; Crock, James G.; Lowers, Heather A.; Witten, Mark L.

2010-01-01

In vitro bioaccessibility (IVBA) studies were carried out on samples of mercury (Hg) mine-waste calcine (roasted Hg ore) by leaching with simulated human body fluids. The objective was to estimate potential human exposure to Hg due to inhalation of airborne calcine particulates and hand-to-mouth ingestion of Hg-bearing calcines. Mine waste calcines collected from Hg mines at Almadén, Spain, and Terlingua, Texas, contain Hg sulfide, elemental Hg, and soluble Hg compounds, which constitute primary ore or compounds formed during Hg retorting. Elevated leachate Hg concentrations were found during calcine leaching using a simulated gastric fluid (as much as 6200 μg of Hg leached/g sample). Elevated Hg concentrations were also found in calcine leachates using a simulated lung fluid (as much as 9200 μg of Hg leached/g), serum-based fluid (as much as 1600 μg of Hg leached/g), and water of pH 5 (as much as 880 μg of Hg leached/g). The leaching capacity of Hg is controlled by calcine mineralogy; thus, calcines containing soluble Hg compounds contain higher leachate Hg concentrations. Results indicate that ingestion or inhalation of Hg mine-waste calcine may lead to increased Hg concentrations in the human body, especially through the ingestion pathway.

Raman spectroscopy of dried synovial fluid droplets as a rapid diagnostic for knee joint damage

NASA Astrophysics Data System (ADS)

Esmonde-White, Karen A.; Mandair, Gurjit S.; Raaii, Farhang; Roessler, Blake J.; Morris, Michael D.

2008-02-01

Human synovial fluid droplets were investigated using drop deposition in combination with Raman spectroscopy. Following informed consent, synovial fluid was obtained from forty human patients with various severities of knee pain and/or osteoarthritis at the time of knee arthroscopy or total joint replacement. Synovial fluid was aspirated from the knee joint of each patient and stored at -80°C until examination by near-infrared Raman spectroscopy. Synovial fluid aspirates from the knee joint of each patient were deposited onto a clean fused silica microscope slide and the droplet dried under ambient laboratory conditions. Each droplet was illuminated by a line-focused or a ring-focused 785 nm laser. As the droplet dries, biofluid components segregated based on solubility differences and a deposit that is spatially heterogeneous was made. Spectra taken from the droplet edges and center were dominated by protein bands and showed the presence of at least two protein moieties in the droplet. Band area and band height ratios (1410 cm -1/1450 cm -1) showed the greatest change between specimens from patients with mild/early osteoarthritis compared to those with severe/late stage osteoarthritis. The greatest differences were found in the center of the droplet, which contains more soluble protein components than the edges.

First Implantation of Silicon Nanopore Membrane Hemofilters

PubMed Central

Kensinger, Clark; Karp, Seth; Kant, Rishi; Chui, Benjamin W.; Goldman, Kenneth; Yeager, Torin; Gould, Edward R.; Buck, Amanda; Laneve, David C.; Groszek, Joseph J.; Roy, Shuvo; Fissell, William H.

2016-01-01

An implantablehemofilter for the treatment of kidney failure depends critically on the transport characteristics of the membrane and the biocompatibility of the membrane, cartridge, and blood conduits. A novel membrane with slit-shaped pores optimizes the trade-off between permeability and selectivity, enabling implanted therapy. Sustained (3–8) day function of an implanted parallel-plate hemofilter with minimal anticoagulation was achieved by considering biocompatibility at the subnanometer scale of chemical interactions and the millimeter scale of blood fluid dynamics. A total of 400 nm-thick polysilicon flat sheet membranes with 5–8 nm 2 micron slit-shaped pores were surface-modified with polyethylene glycol. Hemofilter cartridge geometries were refined based on computational fluid dynamics predictions of blood flow. In an uncontrolled pilot study, silicon filters were implanted in six class A dogs. Cartridges were connected to the cardiovascular system by anastamoses to the aorta and inferior vena cava and filtrate was drained to collection pouches positioned in the peritoneum. Pain medicine and acetylsalicylic acid were administered twice daily until the hemofilters were harvested on postoperative days 3 (n = 2), 4 (n = 2), 5 (n = 1), and 8 (n = 1). No hemofilters were thrombosed. Animals treated for 5 and 8 days had microscopic fractures in the silicon nanopore membranes and 20–50 ml of transudative (albumin sieving coefficient 0.5 – 0.7) fluid in the collection pouches at the time of explant. Shorter experimental durations (3–4 days) resulted in filtration volumes similar to predictions based on mean arterial pressures and membrane hydraulic permeability and (∼ 0.2 – 0.3), similar to preimplantation measurements. In conclusion, a detailed mechanistic and materials science attention to blood–material interactions allows implanted hemofilters to resist thrombosis. Additional testing is needed to determine optimal membrane characteristics and identify limiting factors in long-term implantation. PMID:26978710

Effects of bamboo charcoal on fouling and microbial diversity in a flat-sheet ceramic membrane bioreactor.

PubMed

Zhang, Wenjie; Liu, Xiaoning; Wang, Dunqiu; Jin, Yue

2017-11-01

Membrane fouling is a problem in full-scale membrane bioreactors. In this study, bamboo charcoal (BC) was evaluated for its efficacy in alleviating membrane fouling in flat-sheet membrane bioreactors treating municipal wastewater. The results showed that BC addition markedly improved treatment performance based on COD, NH 4 + -N, total nitrogen, and total phosphorus levels. Adding BC slowed the increase in the trans-membrane pressure rate and resulted in lower levels of soluble microbial products and extracellular polymeric substances detected in the flat-sheet membrane bioreactor. BC has a porous structure, and a large quantity of biomass was detected using scanning electron microscopy. The microbial community analysis results indicated that BC increased the microbial diversity and Aminomonas, Anaerofustis, uncultured Anaerolineaceae, Anaerolinea, and Anaerotruncus were found in higher abundances in the reactor with BC. BC addition is an effective method for reducing membrane fouling, and can be applied to full-scale flat-sheet membrane bioreactors to improve their function. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of excitation direction on cochlear macro-mechanics during bone conduction stimulation

NASA Astrophysics Data System (ADS)

Kamieniecki, Konrad; Tudruj, Sylwester; Piechna, Janusz; Borkowski, Paweł

2018-05-01

In many instances of hearing loss, audiological improvement can be made via direct excitation of a temporal bone (i.e., bone conduction). In order to design better and more efficient devices, the macro-mechanics of the bone conduction hearing pathway must be better understood. Based on previous empirical work, numerical models are useful. In this work, we present results of a time-domain Fluid Structure Interaction model that describes stimulation of the bone conduction pathway. The cochlea was modelled as uncoiled and consisted of an oval window, a round window, a basilar membrane and a helicotrema. In order to monitor pressure waves in the perilymph, the fluid was considered compressible. The excitation, in form of sinusoidal velocity, was applied to the cochlea bony walls. The system was excited in three perpendicular directions: along the basilar membrane, perpendicularly to the membrane and transversely to the membrane. The numerical simulation examined which stimulation direction maximally excited the basilar membrane, the pressure distributions for each excitation direction, and the associated mechanics.

Inositol trisphosphate metabolism in carrot (Daucus carota L. ) cells

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

Memon, A.R.; Rincon, M.; Boss, W.F.

1989-10-01

The metabolism of exogenously added D-myo-(1-{sup 3}H)inositol 1,4,5-trisphosphate (IP{sub 3}) has been examined in microsomal membrane and soluble fractions of carrot cells grown in suspension culture. When ({sup 3}H)IP{sub 3} was added to a microsomal membrane fraction, ({sup 3}H)IP{sub 2} was the primary metabolite consisting of approximately 83% of the total recovered ({sup 3}H) by electrophoresis. ({sup 3}H)IP was only 6% of the ({sup 3}H) recovered, and 10% of the ({sup 3}H)IP{sub 3} was not further metabolized. In contrast, when ({sup 3}H)IP{sub 3} was added to the soluble fraction, approximately equal amounts of ({sup 3}H)IP{sub 2} and ({sup 3}H)IP weremore » recovered. Ca{sup 2+} (100 micromolar) tended to enhance IP{sub 3} dephosphorylation but inhibited the IP{sub 2} dephosphorylation in the soluble fraction by about 20%. MoO{sub 4}{sup 2{minus}} (1 millimolar) inhibited the dephosphorylation of IP{sub 3} by the microsomal fraction and the dephosphorylation of IP{sub 2} by the soluble fraction. MoO{sub 4}{sup 2{minus}}, however, did not inhibit the dephosphorylation of IP{sub 3} by the soluble fraction. Li{sup +} (10 and 50 millimolar) had no effect on IP{sub 3} metabolism in either the soluble or membrane fraction; however, Li{sup +} (50 millimolar) inhibited IP{sub 2} dephosphorylation in the soluble fraction about 25%.« less

Effects of soy-soluble fiber and flaxseed gum on the glycemic and insulinemic responses to glucose solutions and dairy products in healthy adult males.

PubMed

Au, Marco M C; Goff, H Douglas; Kisch, Julie A; Coulson, Alex; Wright, Amanda J

2013-01-01

Soy-soluble polysaccharides and flaxseed gum are underutilized dietary fibers of interest to the food industry. However, because the ability of soluble fibers to modulate postprandial glucose and insulin metabolism has been related to their viscous effects, the utility of these and other low-viscosity soluble fibers remains unproven. The objective of this study was to examine the associations between soy-soluble polysaccharides and flaxseed gum concentration, product viscosity, and the postprandial glycemic and insulinemic responses in the context of glucose solutions as well as fluid and gelled dairy products. Twelve healthy males participated in a randomized crossover postprandial study in which they visited the laboratory following overnight fasts on 11 occasions to consume one of 11 study treatments, each consisting of 50 g available carbohydrates. The study treatments included a glucose reference (in duplicate), glucose solutions containing soy-soluble polysaccharides (6%), flaxseed gum (0.7%), or guar gum (0.23%), all matched for an apparent viscosity of 61 mPa·s at 50 s⁻¹, as well as dairy-based beverages and puddings with 0% or 1% soluble fiber added. Blood samples were collected at fasting and up to 2 hours postprandially for determination of glucose and insulin concentrations. Area under the curve (AUC), peak concentration, and time-to-peak values as well as glycemic index (GI) and insulinemic index (II) were calculated. Fiber fortification of a 50 g glucose solution had no effect on postprandial blood glucose or insulin levels, even at a high concentration (i.e., 6% soy-soluble polysaccharides). Glucose AUC and GI values for the dairy-based beverage (p < 0.05) and pudding (p < 0.01) controls were significantly lower than the glucose reference. Glucose AUC and GI values for the soy-soluble polysaccharide-fortified dairy products (p < 0.01) and flaxseed gum-fortified dairy products (p < 0.001) were significantly lower than the glucose reference. No significant differences were observed between the fiber-fortified fluid and gelled dairy-based study treatments and no significant differences were observed in terms of the insulin AUC, II, and peak insulin concentration between any of the dairy products. All dairy products had lower glycemic responses relative to the reference, with no effect of beverage versus pudding matrix observed and minimal impact of 1% flaxseed gum or soy-soluble polysaccharides. Product apparent viscosity, but not fiber concentration, was significantly and inversely correlated with glucose AUC and GI.

Influence of Physiological Gastrointestinal Surfactant Ratio on the Equilibrium Solubility of BCS Class II Drugs Investigated Using a Four Component Mixture Design

PubMed Central

2017-01-01

The absorption of poorly water-soluble drugs is influenced by the luminal gastrointestinal fluid content and composition, which control solubility. Simulated intestinal fluids have been introduced into dissolution testing including endogenous amphiphiles and digested lipids at physiological levels; however, in vivo individual variation exists in the concentrations of these components, which will alter drug absorption through an effect on solubility. The use of a factorial design of experiment and varying media by introducing different levels of bile, lecithin, and digested lipids has been previously reported, but here we investigate the solubility variation of poorly soluble drugs through more complex biorelevant amphiphile interactions. A four-component mixture design was conducted to understand the solubilization capacity and interactions of bile salt, lecithin, oleate, and monoglyceride with a constant total concentration (11.7 mM) but varying molar ratios. The equilibrium solubility of seven low solubility acidic (zafirlukast), basic (aprepitant, carvedilol), and neutral (fenofibrate, felodipine, griseofulvin, and spironolactone) drugs was investigated. Solubility results are comparable with literature values and also our own previously published design of experiment studies. Results indicate that solubilization is not a sum accumulation of individual amphiphile concentrations, but a drug specific effect through interactions of mixed amphiphile compositions with the drug. This is probably due to a combined interaction of drug characteristics; for example, lipophilicity, molecular shape, and ionization with amphiphile components, which can generate specific drug–micelle affinities. The proportion of each component can have a remarkable influence on solubility with, in some cases, the highest and lowest points close to each other. A single-point solubility measurement in a fixed composition simulated media or human intestinal fluid sample will therefore provide a value without knowledge of the surrounding solubility topography meaning that variability may be overlooked. This study has demonstrated how the amphiphile ratios influence drug solubility and highlights the importance of the envelope of physiological variation when simulating in vivo drug behavior. PMID:28749696

Estimation of intragastric solubility of drugs: in what medium?

PubMed

Vertzoni, Maria; Pastelli, Eleni; Psachoulias, Dimitris; Kalantzi, Lida; Reppas, Christos

2007-05-01

To measure the solubility of four drugs in human gastric aspirates, canine gastric aspirates (CGF) and simulated gastric fluids in order to propose a medium for estimating intragastric drug solubility relevant to a bioavailability study in the fasted state. Intragastric environment after administration of water to healthy fasted adults and to healthy fasted dogs (this study) was initially characterized. Solubilities were then measured with the shake-flask method in gastric fluid aspirated after the administration of water to healthy fasted adults and to healthy fasted dogs, in various simulated gastric fluids, i.e. SGF(SLS), SGF(Triton), FaSSGF, FaSSGF(NaCl), and in various HCl solutions with pH values ranging from 1.2 to 2.9. In all cases, FaSSGF performed better than canine aspirates, SGF(SLS), SGF(Triton), or FaSSGF(NaCl) in predicting solubility in HGF. However, its superiority over HCl pH 1.6 was not clear. For ketoconazole, dipyridamole, miconazole, and felodipine deviations of solubility data in FaSSGF from solubility data in HGF were non-significant, 34, -39 and 252%, respectively, whereas the corresponding deviations of data in HCl pH 1.6 from data in HGF were non-significant, 24, 70, and 130%, respectively. Combining data in FaSSGF and HCl pH 1.6 is comparatively the most efficient way to get an estimate of drug solubility in the fasting gastric contents during a bioavailability study. However, accurate estimation of intragastric solubility is limited by the changing environment during intragastric residence of solid particles and the degree of simulation of intragastric composition.

Absence of first-order unbinding transitions of fluid and polymerized membranes

NASA Technical Reports Server (NTRS)

Grotehans, Stefan; Lipowsky, Reinhard

1990-01-01

Unbinding transitions of fluid and polymerized membranes are studied by renormalization-group (RG) methods. Two different RG schemes are used and found to give rather consistent results. The fixed-point structure of both RG's exhibits a complex behavior as a function of the decay exponent tau for the fluctuation-induced interaction of the membranes. For tau greater than tau(S2) interacting membranes can undergo first-order transitions even in the strong-fluctuation regime. These estimates for tau(S2) imply, however, that both fluid and polymerized membranes unbind in a continuous way in the absence of lateral tension.

Hyaluronidase 2: A Novel Germ Cell Hyaluronidase with Epididymal Expression and Functional Roles in Mammalian Sperm1

PubMed Central

Modelski, Mark J.; Menlah, Gladys; Wang, Yipei; Dash, Soma; Wu, Kathie; Galileo, Deni S.; Martin-DeLeon, Patricia A.

2014-01-01

ABSTRACT To initiate the crucial cell adhesion events necessary for fertilization, sperm must penetrate extracellular matrix barriers containing hyaluronic acid (HA), a task thought to be accomplished by neutral-active hyaluronidases. Here we report that the ∼57 kDa hyaluronidase 2 (HYAL2) that in somatic tissues has been highly characterized to be acid-active is present in mouse and human sperm, as detected by Western blot, flow cytometric, and immunoprecipitation assays. Immunofluorescence revealed its presence on the plasma membrane over the acrosome, the midpiece, and proximal principal piece in mice where protein fractionation demonstrated a differential distribution in subcellular compartments. It is significantly more abundant in the acrosome-reacted (P = 0.04) and soluble acrosomal fractions (P = 0.006) (microenvironments where acid-active hyaluronidases function) compared to that of the plasma membrane where neutral hyaluronidases mediate cumulus penetration. Using HA substrate gel electrophoresis, immunoprecipitated HYAL 2 was shown to have catalytic activity at pH 4.0. Colocalization and coimmunoprecipitation assays reveal that HYAL2 is associated with its cofactor, CD44, consistent with CD44-dependent HYAL2 activity. HYAL2 is also present throughout the epididymis, where Hyal2 transcripts were detected, and in the epididymal luminal fluids. In vitro assays demonstrated that HYAL2 can be acquired on the sperm membrane from epididymal luminal fluids, suggesting that it plays a role in epididymal maturation. Because similar biphasic kinetics are seen for HYAL2 and SPAM1 (Sperm adhesion molecule 1), it is likely that HYAL2 plays a redundant role in the catalysis of megadalton HA to its 20 kDa intermediate during fertilization. PMID:25232017

In vitro dynamic solubility test: influence of various parameters.

PubMed Central

Thélohan, S; de Meringo, A

1994-01-01

This article discusses the dissolution of mineral fibers in simulated physiological fluids (SPF), and the parameters that affect the solubility measurement in a dynamic test where an SPF runs through a cell containing fibers (Scholze and Conradt test). Solutions simulate either the extracellular fluid (pH 7.6) or the intracellular fluid (pH 4.5). The fibers have various chemical compositions and are either continuously drawn or processed as wool. The fiber solubility is determined by the amount of SiO2 (and occasionally other ions) released in the solution. Results are stated as percentage of the initial silica content released or as dissolution rate v in nm/day. The reproducibility of the test is higher with the less soluble fibers (10% solubility), than with highly soluble fibers (20% solubility). The influence of test parameters, including SPF, test duration, and surface area/volume (SA/V), has been studied. The pH and the inorganic buffer salts have a major influence: industrial glasswool composition is soluble at pH 7.6 but not at pH 4.5. The opposite is true for rock- (basalt) wool composition. For slightly soluble fibers, the dissolution rate v remains constant with time, whereas for highly soluble fibers, the dissolution rate decreases rapidly. The dissolution rates believed to occur are v1, initial dissolution rate, and v2, dissolution rate of the residual fibers. The SA of fibers varies with the mass of the fibers tested, or with the fiber diameter at equal mass. Volume, V, is the chosen flow rate. An increase in the SA/V ratio leads to a decrease in the dissolution rate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7882964

In vitro dynamic solubility test: influence of various parameters.

PubMed

Thélohan, S; de Meringo, A

1994-10-01

This article discusses the dissolution of mineral fibers in simulated physiological fluids (SPF), and the parameters that affect the solubility measurement in a dynamic test where an SPF runs through a cell containing fibers (Scholze and Conradt test). Solutions simulate either the extracellular fluid (pH 7.6) or the intracellular fluid (pH 4.5). The fibers have various chemical compositions and are either continuously drawn or processed as wool. The fiber solubility is determined by the amount of SiO2 (and occasionally other ions) released in the solution. Results are stated as percentage of the initial silica content released or as dissolution rate v in nm/day. The reproducibility of the test is higher with the less soluble fibers (10% solubility), than with highly soluble fibers (20% solubility). The influence of test parameters, including SPF, test duration, and surface area/volume (SA/V), has been studied. The pH and the inorganic buffer salts have a major influence: industrial glasswool composition is soluble at pH 7.6 but not at pH 4.5. The opposite is true for rock- (basalt) wool composition. For slightly soluble fibers, the dissolution rate v remains constant with time, whereas for highly soluble fibers, the dissolution rate decreases rapidly. The dissolution rates believed to occur are v1, initial dissolution rate, and v2, dissolution rate of the residual fibers. The SA of fibers varies with the mass of the fibers tested, or with the fiber diameter at equal mass. Volume, V, is the chosen flow rate. An increase in the SA/V ratio leads to a decrease in the dissolution rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase relations in the system NaCl-KCl-H 2O. III: Solubilities of halite in vapor-saturated liquids above 445°C and redetermination of phase equilibrium properties in the system NaCl-H 2O to 1000°C and 1500 bars

NASA Astrophysics Data System (ADS)

Chou, I.-Ming

1987-07-01

Halite solubilities along the three-phase curve in the binary system NaCl-H 2O determined by DTA experiment can be represented by the equation Wt.% NaCl (±0.2) = 19.39 - 0.0364 t + 3.553 × 10 -4T2 - 2.298 × 10 -7T3, where 447≦ T ≦ 800° C. Even though these halite solubilities are up to ~7 wt.% higher than those reported in literature, extrapolated values at temperatures below 447°C merge with the literature values. It is considered that the equation adequately describes halite solubilities between 382 and 800°C. The newly established solubility data are believed to be more reliable because they are compatible with data obtained by using synthetic fluid inclusions and with the observed DTA signals and also because they were measured in a relatively corrosion-free system. In an earlier publication (GUNTER et al., 1983), we were puzzled greatly by multiple and rather unreproducible DTA peaks appearing during isobaric cooling (heating experiments were nondefinitive) at pressures below about 500 bars. These DTA signals apparently suggested that the "halite liquidus" swung sharply upward in temperature as pressure decreased from about 500 bars to that of the halite-saturated boiling curve. Further analysis of the data and helpful discussions with several individuals have revealed that the behavior is a consequence of the initial (precooling) separation of the fluid into NaCl-poor gas and NaCl-rich liquid that failed to homogenize in the short time encompassed by the DTA experiments. The present analysis is based on extrapolations of the dP/dT slopes from pressures above 500 bars. Through use of these new halite solubility data and the data from synthetic fluid inclusions [formed by healing fractures in inclusion-free Brazilian quartz in the presence of two coexisting, immiscible NaCl-H 2O fluids at various temperatures and pressures (Bodnar et al., 1985)], phase equilibria in the system NaCl-H 2O have been redetermined to 1000°C and 1500 bars.

Impact of tuning CO 2-philicity in polydimethylsiloxane-based membranes for carbon dioxide separation

DOE PAGES

Hong, Tao; Chatterjee, Sabornie; Mahurin, Shannon M.; ...

2017-02-22

Amidoxime-functionalized polydimethylsiloxane (AO-PDMSPNB) membranes with various amidoxime compositions were synthesized via ring-opening metathesis polymerization followed by post-polymerization modification. Compared to other previously reported PDMS-based membranes, the amidoxime-functionalized membranes show enhanced CO 2 permeability and CO 2/N 2 selectivity. The overall gas separation performance (CO 2 permeability 6800 Barrer; CO 2/N 2 selectivity 19) of the highest performing membrane exceeds the Robeson upper bound line, and the excellent permeability of the copolymer itself provides great potential for real world applications where huge volumes of gases are separated. This study details how tuning the CO 2-philicity within rubbery polymer matrices influences gasmore » transport properties. Key parameters for tuning gas transport properties are discussed, and the experimental results show good consistency with theoretical calculations. Finally, this study provides a roadmap to enhancing gas separation performance in rubbery polymers by tuning gas solubility selectivity.« less

Elastic moduli of a smectic membrane: a rod-level scaling analysis

NASA Astrophysics Data System (ADS)

Wensink, H. H.; Morales Anda, L.

2018-02-01

Chiral rodlike colloids exposed to strong depletion attraction may self-assemble into chiral membranes whose twisted director field differs from that of a 3D bulk chiral nematic. We formulate a simple microscopic variational theory to determine the elastic moduli of rods assembled into a bidimensional smectic membrane. The approach is based on a simple Onsager-Straley theory for a non-uniform director field that we apply to describe rod twist within the membrane. A microscopic approach enables a detailed estimate of the individual Frank elastic moduli (splay, twist and bend) as well as the twist penetration depth of the smectic membrane in relation to the rod density and shape. We find that the elastic moduli are distinctly different from those of a bulk nematic fluid, with the splay elasticity being much stronger and the curvature elasticity much weaker than for rods assembled in a three-dimensional nematic fluid. We argue that the use of the simplistic one-constant approximation in which all moduli are assumed to be of equal magnitude is not appropriate for modelling the structure-property relation of smectic membranes.

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

Chance, Ronald; Koros, William J.; McCool, Benjamin

The invention provides systems and methods for the delivery of carbon to photoautotrophs. The invention utilizes low energy regeneration of adsorbent for CO.sub.2 capture and provides for effective CO.sub.2 loading into liquids useful for photoautotroph growth and/or production of photosynthetic products, such as biofuels, via photoautotrophic culture media. The inventive system comprises a fluid/membrane/fluid contactor that provides selective transfer of molecular CO.sub.2 via a dense (non-porous) membrane from a carbonate-based CO.sub.2 snipping solution to a culture medium where the CO.sub.2 is consumed by a photoautotroph for the production of biofuels, biofuel precursors or other commercial products.

Cooling system with automated seasonal freeze protection

DOEpatents

Campbell, Levi A.; Chu, Richard C.; David, Milnes P.; Ellsworth, Jr., Michael J.; Iyengar, Madhusudan K.; Simons, Robert E.; Singh, Prabjit; Zhang, Jing

2016-05-24

An automated multi-fluid cooling system and method are provided for cooling an electronic component(s). The cooling system includes a coolant loop, a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

Cooling method with automated seasonal freeze protection

DOEpatents

Cambell, Levi; Chu, Richard; David, Milnes; Ellsworth, Jr, Michael; Iyengar, Madhusudan; Simons, Robert; Singh, Prabjit; Zhang, Jing

2016-05-31

An automated multi-fluid cooling method is provided for cooling an electronic component(s). The method includes obtaining a coolant loop, and providing a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

Membrane with supported internal passages

NASA Technical Reports Server (NTRS)

Gonzalez-Martin, Anuncia (Inventor); Salinas, Carlos E. (Inventor); Cisar, Alan J. (Inventor); Hitchens, G. Duncan (Inventor); Murphy, Oliver J. (Inventor)

2000-01-01

The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface comprising permanent tubes preferably placed at the ends of the fluid passages. The invention also provides an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane.

CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007)

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

J.R. Klaehn; C.J. Orme; E.S. Peterson

2008-03-01

This is a complete (Fiscal Years 2000–2006) collection of the Idaho National Laboratory’s (INL) research and development contributions to the project, “CO2 Separation Using Thermally Optimized Membranes.” The INL scientific contribution to the project has varied due to the fluctuations in funding from year to year. The focus of the project was polybenzimidazole (PBI) membranes and developing PBI compounds (both substitution and blends) that provide good film formation and gas separation membranes. The underlying problem with PBI is its poor solubility in common solvents. Typically, PBI is dissolved in “aggressive” solvents, like N,N-dimethylacetamide (DMAc) and N methylpyrrolidone (NMP). The INLmore » FY-03 research was directed toward making soluble N-substituted PBI polymers, where INL was very successful. Many different types of modified PBI polymers were synthesized; however, film formation proved to be a big problem with both unsubstituted and N-substituted PBIs. Therefore, INL researchers directed their attention to using plasticizers or additives to make the membranes more stable and workable. During the course of these studies, other high-performance polymers (like polyamides and polyimides) were found to be better materials, which could be used either by themselves or blends with PBI. These alternative high-performance polymers provided the best pathway forward for soluble high-temperature polymers with good stable film formation properties. At present, the VTEC polyimides (product of RBI, Inc.) are the best film formers that exhibit high-temperature resistance. INL’s gas testing results show VTEC polyimides have very good gas selectivities for both H2/CO2 and CO2/CH4. Overall, these high-performance polymers pointed towards new research areas where INL has gained a greater understanding of polymer film formation and gas separation. These studies are making possible a direct approach to stable polymer-based high-temperature gas separation membranes. This report is separated into several sections due to the complexity of the research and the variation with the development of better high-temperature, gas separation membranes. Several fiscal years are combined because the research and development efforts within those areas crossed fiscal year boundaries.« less

CO2 Separation Using Thermally Optimized Membranes: A Comprehensive Project Report (2000 - 2007)

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

N /A

2008-03-04

This is a complete (Fiscal Years 2000–2006) collection of the Idaho National Laboratory’s (INL) research and development contributions to the project, “CO2 Separation Using Thermally Optimized Membranes.” The INL scientific contribution to the project has varied due to the fluctuations in funding from year to year. The focus of the project was polybenzimidazole (PBI) membranes and developing PBI compounds (both substitution and blends) that provide good film formation and gas separation membranes. The underlying problem with PBI is its poor solubility in common solvents. Typically, PBI is dissolved in “aggressive” solvents, like N,N-dimethylacetamide (DMAc) and N methylpyrrolidone (NMP). The INLmore » FY-03 research was directed toward making soluble N-substituted PBI polymers, where INL was very successful. Many different types of modified PBI polymers were synthesized; however, film formation proved to be a big problem with both unsubstituted and N-substituted PBIs. Therefore, INL researchers directed their attention to using plasticizers or additives to make the membranes more stable and workable. During the course of these studies, other high-performance polymers (like polyamides and polyimides) were found to be better materials, which could be used either by themselves or blends with PBI. These alternative high-performance polymers provided the best pathway forward for soluble high-temperature polymers with good stable film formation properties. At present, the VTEC polyimides (product of RBI, Inc.) are the best film formers that exhibit high-temperature resistance. INL’s gas testing results show VTEC polyimides have very good gas selectivities for both H2/CO2 and CO2/CH4. Overall, these high-performance polymers pointed towards new research areas where INL has gained a greater understanding of polymer film formation and gas separation. These studies are making possible a direct approach to stable polymer-based high-temperature gas separation membranes. This report is separated into several sections due to the complexity of the research and the variation with the development of better high-temperature, gas separation membranes. Several fiscal years are combined because the research and development efforts within those areas crossed fiscal year boundaries.« less

Solubility and dissolution improvement of ketoprofen by emulsification ionic gelation

NASA Astrophysics Data System (ADS)

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

2018-02-01

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

Degradation of neurotensin by rat brain synaptic membranes: involvement of a thermolysin-like metalloendopeptidase (enkephalinase), angiotensin-converting enzyme, and other unidentified peptidases.

PubMed

Checler, F; Vincent, J P; Kitabgi, P

1983-08-01

Neurotensin was inactivated by membrane-bound and soluble degrading activities present in purified preparations of rat brain synaptic membranes. Degradation products were identified by HPLC and amino acid analysis. The major points of cleavage of neurotensin were the Arg8-Arg9, Pro10-Tyr11, and Tyr11-Ile12 peptide bonds with the membrane-bound activity and the Arg8-Arg9 and Pro10-Tyr11 bonds with the soluble activity. Several lines of evidence indicated that the cleavage of the Arg8-Arg9 bond by the membrane-bound activity resulted mainly from the conversion of neurotensin1-10 to neurotensin1-8 by a dipeptidyl carboxypeptidase. In particular, captopril inhibited this cleavage with an IC50 (5.7 nM) close to its K1 (7 nM) for angiotensin-converting enzyme. Thiorphan inhibited the cleavage at the Tyr11-Ile12 bond by the membrane-bound activity with an IC50 (17 nM) similar to its K1 (4.7 nM) for enkephalinase. Both cleavages were inhibited by 1,10-phenanthroline. These and other data suggested that angiotensin-converting enzyme and a thermolysin-like metalloendopeptidase (enkephalinase) were the membrane-bound peptidases responsible for cleavages at the Arg8-Arg9 and Tyr11-Ile12 bonds, respectively. In contrast, captopril had no effect on the cleavage at the Arg8-Arg9 bond by the soluble activity, indicating that the enzyme responsible for this cleavage was different from angiotensin-converting enzyme. The cleavage at the Pro10-Tyr11 bond by both the membrane-bound and the soluble activities appeared to be catalyzed by an endopeptidase different from known brain proline endopeptidases. The possibility is discussed that the enzymes described here participate in physiological mechanisms of neurotensin inactivation at the synaptic level.

Structure-function insights of membrane and soluble proteins revealed by electron crystallography.

PubMed

Dreaden, Tina M; Devarajan, Bharanidharan; Barry, Bridgette A; Schmidt-Krey, Ingeborg

2013-01-01

Electron crystallography is emerging as an important method in solving protein structures. While it has found extensive applications in the understanding of membrane protein structure and function at a wide range of resolutions, from revealing oligomeric arrangements to atomic models, electron crystallography has also provided invaluable information on the soluble α/β-tubulin which could not be obtained by any other method to date. Examples of critical insights from selected structures of membrane proteins as well as α/β-tubulin are described here, demonstrating the vast potential of electron crystallography that is first beginning to unfold.

ATP-binding cassette transporters are enriched in non-caveolar detergent-insoluble glycosphingolipid-enriched membrane domains (DIGs) in human multidrug-resistant cancer cells.

PubMed

Hinrichs, John W J; Klappe, Karin; Hummel, Ina; Kok, Jan W

2004-02-13

In this study we show that P-glycoprotein in multidrug-resistant 2780AD human ovarian carcinoma cells and multidrug resistance-associated protein 1 in multidrug-resistant HT29col human colon carcinoma cells are predominantly located in Lubrol-based detergent-insoluble glycosphingolipid-enriched membrane domains. This localization is independent of caveolae, since 2780AD cells do not express caveolin-1. Although HT29col cells do express caveolin-1, the ATP-binding cassette transporter and caveolin-1 were dissociated on the basis of differential solubility in Triton X-100 and absence of microscopical colocalization. While both the multidrug resistance-associated protein 1 and caveolin-1 are located in Lubrol-based membrane domains, they occupy different regions of these domains.

Two-compartment passive frequency domain cochlea model allowing independent fluid coupling to the tectorial and basilar membranes

PubMed Central

Cormack, John; Liu, Yanju; Nam, Jong-Hoon; Gracewski, Sheryl M.

2015-01-01

The cochlea is a spiral-shaped, liquid-filled organ in the inner ear that converts sound with high frequency selectivity over a wide pressure range to neurological signals that are eventually interpreted by the brain. The cochlear partition, consisting of the organ of Corti supported below by the basilar membrane and attached above to the tectorial membrane, plays a major role in the frequency analysis. In early fluid-structure interaction models of the cochlea, the mechanics of the cochlear partition were approximated by a series of single-degree-of-freedom systems representing the distributed stiffness and mass of the basilar membrane. Recent experiments suggest that the mechanical properties of the tectorial membrane may also be important for the cochlea frequency response and that separate waves may propagate along the basilar and tectorial membranes. Therefore, a two-dimensional two-compartment finite difference model of the cochlea was developed to investigate the independent coupling of the basilar and tectorial membranes to the surrounding liquid. Responses are presented for models using two- or three-degree-of-freedom stiffness, damping, and mass parameters derived from a physiologically based finite element model of the cochlear partition. Effects of changes in membrane and organ of Corti stiffnesses on the individual membrane responses are investigated. PMID:25786927

Caterpillar locomotion-inspired valveless pneumatic micropump using a single teardrop-shaped elastomeric membrane.

PubMed

So, Hongyun; Pisano, Albert P; Seo, Young Ho

2014-07-07

This paper presents a microfluidic pump operated by an asymmetrically deformed membrane, which was inspired by caterpillar locomotion. Almost all mechanical micropumps consist of two major components of fluid halting and fluid pushing parts, whereas the proposed caterpillar locomotion-inspired micropump has only a single, bilaterally symmetric membrane-like teardrop shape. A teardrop-shaped elastomeric membrane was asymmetrically deformed and then consecutively touched down to the bottom of the chamber in response to pneumatic pressure, thus achieving fluid pushing. Consecutive touchdown motions of the teardrop-shaped membrane mimicked the propagation of a caterpillar's hump during its locomotory gait. The initial touchdown motion of the teardrop-shaped membrane at the centroid worked as a valve that blocked the inlet channel, and then, the consecutive touchdown motions pushed fluid in the chamber toward the tail of the chamber connected to the outlet channel. The propagation of the touchdown motion of the teardrop-shaped membrane was investigated using computational analysis as well as experimental studies. This caterpillar locomotion-inspired micropump composed of only a single membrane can provide new opportunities for simple integration of microfluidic systems.

The role of soluble and insoluble gastric fluid components in the pathogenesis of obliterative bronchiolitis in rat lung allografts.

PubMed

Leung, Jason H; Chang, Jui-Chih; Bell, Sadé M; Holzknecht, Zoie E; Thomas, Samantha M; Everett, Mary Lou; Parker, William; Davis, R Duane; Lin, Shu S

2016-02-01

Repetitive gastric fluid aspirations have been shown to lead to obliterans bronchiolitis (OB), but the component or components of gastric fluid that are responsible are unknown. This study investigates the role of particulates and, separately, soluble material in gastric fluid during the development of OB. Whole gastric fluid (WGF) was collected from male Fischer 344 (F344) rats and separated by centrifugation into particle reduced gastric fluid (PRGF) and particulate components resuspended in normal saline (PNS). Orthotopic left lung transplants from male Wistar-Kyoto rats into F344 rats were performed using a modification of the nonsuture external cuff technique with prolonged cold ischemia. Rats were subjected to weekly aspiration of 0.5 ml/kg of WGF (n = 9), PRGF (n = 10), PNS (n = 9), or normal saline (control, NS; n = 9) for 8 weeks following transplantation. Lung allografts treated with WGF, PRGF, or PNS developed a significantly greater percentage of OB-like lesions compared with the control. No statistical difference was observed when comparing the fibrosis grades or the percentage of OB lesions of WGF, PRGF, and PNS groups, suggesting that both soluble and insoluble components of gastric fluid can promote the development of aspiration-induced OB and fibrosis in lung allografts. © 2015 Steunstichting ESOT.

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

Rashid, Nur Shahidah Abdul; Sarmani, Sukiman; Majid, Amran Ab.

238U radionuclide is a naturally occuring radioactive material that can be found in soil. In this study, the solubility of 238U radionuclide obtained from various types of soil in synthetic gastrointestinal fluids was analysed by “US P in vitro” digestion method. The synthetic gastrointestinal fluids were added to the samples with well-ordered, mixed throughly and incubated according to the human physiology digestive system. The concentration of 238U radionuclide in the solutions extracted from the soil was measured using Induced Coupling Plasma Mass Spectrometer (ICP-MS). The concentration of 238U radionuclide from the soil samples in synthetic gastrointestinal fluids showed different valuesmore » due to different homogenity of soil types and chemical reaction of 238U radionuclide. In general, the solubility of 238U radionuclide in gastric fluid was higher (0.050 – 0.209 ppm) than gastrointestinal fluids (0.024 – 0.050 ppm). It could be concluded that the US P in vitro digestion method is practicle for estimating the solubility of 238U radionuclide from soil materials and could be useful for monitoring and risk assessment purposes applying to environmental, health and contaminated soil samples.« less

Actuation of flexoelectric membranes in viscoelastic fluids with applications to outer hair cells

PubMed Central

Herrera-Valencia, E. E.; Rey, Alejandro D.

2014-01-01

Liquid crystal flexoelectric actuation uses an imposed electric field to create membrane bending, and it is used by the outer hair cells (OHCs) located in the inner ear, whose role is to amplify sound through generation of mechanical power. Oscillations in the OHC membranes create periodic viscoelastic flows in the contacting fluid media. A key objective of this work on flexoelectric actuation relevant to OHCs is to find the relations and impact of the electromechanical properties of the membrane, the rheological properties of the viscoelastic media, and the frequency response of the generated mechanical power output. The model developed and used in this work is based on the integration of: (i) the flexoelectric membrane shape equation applied to a circular membrane attached to the inner surface of a circular capillary and (ii) the coupled capillary flow of contacting viscoelastic phases, such that the membrane flexoelectric oscillations drive periodic viscoelastic capillary flows, as in OHCs. By applying the Fourier transform formalism to the governing equation, analytical expressions for the transfer function associated with the curvature and electrical field and for the power dissipation of elastic storage energy were found. PMID:25332388

Microgravity Transport Phenomena Experiment (MTPE) Overview

NASA Technical Reports Server (NTRS)

Mason, Larry W.

1999-01-01

The Microgravity Transport Phenomena Experiment (MTPE) is a fluids experiment supported by the Fundamentals in Biotechnology program in association with the Human Exploration and Development of Space (BEDS) initiative. The MTP Experiment will investigate fluid transport phenomena both in ground based experiments and in the microgravity environment. Many fluid transport processes are affected by gravity. Osmotic flux kinetics in planar membrane systems have been shown to be influenced by gravimetric orientation, either through convective mixing caused by unstably stratified fluid layers, or through a stable fluid boundary layer structure that forms in association with the membrane. Coupled transport phenomena also show gravity related effects. Coefficients associated with coupled transport processes are defined in terms of a steady state condition. Buoyancy (gravity) driven convection interferes with the attainment of steady state, and the measurement of coupled processes. The MTP Experiment measures the kinetics of molecular migration that occurs in fluids, in response to the application of various driving potentials. Three separate driving potentials may be applied to the MTP Experiment fluids, either singly or in combination. The driving potentials include chemical potential, thermal potential, and electrical potential. Two separate fluid arrangements are used to study membrane mediated and bulk fluid transport phenomena. Transport processes of interest in membrane mediated systems include diffusion, osmosis, and streaming potential. Bulk fluid processes of interest include coupled phenomena such as the Soret Effect, Dufour Effect, Donnan Effect, and thermal diffusion potential. MTP Experiments are performed in the Microgravity Transport Apparatus (MTA), an instrument that has been developed specifically for precision measurement of transport processes. Experiment fluids are contained within the MTA fluid cells, designed to create a one dimensional flow geometry of constant cross sectional area, and to facilitate fluid filling and draining operations in microgravity. The fluid cells may be used singly for bulk solutions, or in a Stokes diaphragm configuration to investigate membrane mediated phenomena. Thermal and electrical driving potentials are applied to the experiment fluids through boundary plates located at the ends of the fluid cells. In the ground based instrument, two constant temperature baths circulate through reservoirs adjacent to the boundary plates, and establish the thermal environment within the fluid cells. The boundary plates also serve as electrodes for measurement and application of electrical potentials. The Fluid Manipulation System associated with the MTA is a computer controlled system that enables storage and transfer of experiment fluids during on orbit operations. The system is used to automatically initiate experiments and manipulate fluids by orchestrating pump and valve operations through scripted sequences. Unique technologies are incorporated in the MTA for measurement of fluid properties. Volumetric Flow Sensors have been developed for precision measurement of total fluid volume contained within the fluid cells over time. This data is most useful for measuring the kinetics of osmosis, where fluid is transported from one fluid cell to another through a semipermeable membrane. The MicroSensor Array has been designed to perform in situ measurement of several important fluid parameters, providing simultaneous measurement of solution composition at multiple locations within the experiment fluids. Micromachined sensors and interface electronics have been developed to measure temperature, electrical conductivity, pH, cation activity, and anion activity. The Profile Refractometer uses a laser optical system to directly image the fluid Index of Refraction profile that exists along the MTA fluid cell axis. A video system acquires images of the RI profile over time, and records the transport kinetics that occur upon application of chemical, thermal, or electrical driving potentials. Image processing algorithms have been developed to analyze the refractometer images on a pixel by pixel basis, calibrating and scaling the measured Index of Refraction profile to correlated solution properties of interest such as density, concentration, and temperature. Additional software has been developed to compile the processed images into a three dimensional matrix that contains fluid composition data as a function of experiment time and position in the fluid cell. These data are combined with data from the other sensor systems, and analyzed in the context of transport coefficients associated with the various transport phenomena. Analysis protocols have been developed to measure the transient kinetics, and steady state distribution of fluid components that occur in response to the applied driving potentials. The results are expressed in terms of effective transport coefficients. Experiments have been performed using a variety of solutes, and results generated are that are in agreement with published transport coefficient values.

Temperature effect on nickel release in ammonium citrate.

PubMed

Oller, Adriana R; Cappellini, Danielle; Henderson, Rayetta G; Bates, Hudson K

2009-09-01

Leaching in ammonium citrate has been extensively used to assess the fraction of water-soluble nickel compounds present in nickel producing and using workplace aerosols. Leaching in ammonium citrate according to the first step of the Zatka protocol was found to overestimate the water-soluble nickel fraction by more than ten-fold compared to synthetic lung fluid (37 degrees C), when nickel carbonate and subsulfide were present. These results suggest that exposure matrices based on this method should be reexamined. Leaching studies of refinery particles are needed to further clarify this important issue.

Multiscale Particle-Based Modeling of Flowing Platelets in Blood Plasma Using Dissipative Particle Dynamics and Coarse Grained Molecular Dynamics

PubMed Central

Zhang, Peng; Gao, Chao; Zhang, Na; Slepian, Marvin J.; Deng, Yuefan; Bluestein, Danny

2014-01-01

We developed a multiscale particle-based model of platelets, to study the transport dynamics of shear stresses between the surrounding fluid and the platelet membrane. This model facilitates a more accurate prediction of the activation potential of platelets by viscous shear stresses - one of the major mechanisms leading to thrombus formation in cardiovascular diseases and in prosthetic cardiovascular devices. The interface of the model couples coarse-grained molecular dynamics (CGMD) with dissipative particle dynamics (DPD). The CGMD handles individual platelets while the DPD models the macroscopic transport of blood plasma in vessels. A hybrid force field is formulated for establishing a functional interface between the platelet membrane and the surrounding fluid, in which the microstructural changes of platelets may respond to the extracellular viscous shear stresses transferred to them. The interaction between the two systems preserves dynamic properties of the flowing platelets, such as the flipping motion. Using this multiscale particle-based approach, we have further studied the effects of the platelet elastic modulus by comparing the action of the flow-induced shear stresses on rigid and deformable platelet models. The results indicate that neglecting the platelet deformability may overestimate the stress on the platelet membrane, which in turn may lead to erroneous predictions of the platelet activation under viscous shear flow conditions. This particle-based fluid-structure interaction multiscale model offers for the first time a computationally feasible approach for simulating deformable platelets interacting with viscous blood flow, aimed at predicting flow induced platelet activation by using a highly resolved mapping of the stress distribution on the platelet membrane under dynamic flow conditions. PMID:25530818

High throughput atmospheric pressure plasma-induced graft polymerization for identifying protein-resistant surfaces.

PubMed

Gu, Minghao; Kilduff, James E; Belfort, Georges

2012-02-01

Three critical aspects of searching for and understanding how to find highly resistant surfaces to protein adhesion are addressed here with specific application to synthetic membrane filtration. They include the (i) discovery of a series of previously unreported monomers from a large library of monomers with high protein resistance and subsequent low fouling characteristics for membrane ultrafiltration of protein-containing fluids, (ii) development of a new approach to investigate protein-resistant mechanisms from structure-property relationships, and (iii) adaptation of a new surface modification method, called atmospheric pressure plasma-induced graft polymerization (APP), together with a high throughput platform (HTP), for low cost vacuum-free synthesis of anti-fouling membranes. Several new high-performing chemistries comprising two polyethylene glycol (PEG), two amines and one zwitterionic monomers were identified from a library (44 commercial monomers) of five different classes of monomers as strong protein-resistant monomers. Combining our analysis here, using the Hansen solubility parameters (HSP) approach, and data from the literature, we conclude that strong interactions with water (hydrogen bonding) and surface flexibility are necessary for producing the highest protein resistance. Superior protein-resistant surfaces and subsequent anti-fouling performance was obtained with the HTP-APP as compared with our earlier HTP-photo graft-induced polymerization (PGP). Copyright © 2011 Elsevier Ltd. All rights reserved.

A novel solubility-modulated granules through porosity osmotic pump for controlled carvedilol delivery.

PubMed

Song, Qun-Li; Li, Ping; Li, Yu-Min

2012-01-01

A method for the preparation of porosity osmotic pump granules was obtained by modulating carvedilol solubility with tartaric acid. Controlled porosity of the membrane was accomplished by the use of pore-forming agent in the coating. In this study, carvedilol was chosen as a model drug with an aim to develop a zero-order release system; tartaric acid was used as the solubility promoter; NaCl was used as the osmotic agent; cellulose acetate (CA) was used as the materials of semipermeable membrane; and PEG-400 was used as the pore-forming agent in the semipermeable membrane. The influence of different factors or levels on the in vitro release was studied. In order to simulate the gastrointestinal tract environments, two kinds of pH media (pH 1.5 and 6.8) on drug release were studied in this research, respectively. This porosity osmotic pump was optimized by single factor design experiments, and it was found to deliver carvedilol at a zero-order rate within 12 h and controlled release for 24 h. We drew a conclusion that the solubility-modulated porosity osmotic pump system is simple to prepare and might be used for the preparation of osmotic pump system of other poorly water-soluble drugs with alkaline or acid groups.

Pyrene-Labeled Amphiphiles: Dynamic And Structural Probes Of Membranes And Lipoproteins

NASA Astrophysics Data System (ADS)

Pownall, Henry J.; Homan, Reynold; Massey, John B.

1987-01-01

Lipids and proteins are important functional and structural components of living organisms. Although proteins are frequently found as soluble components of plasma or the cell cytoplasm, many lipids are much less soluble and separate into complex assemblies that usually contain proteins. Cell membranes and plasma lipoproteins' are two important macro-molecular assemblies that contain both lipids and proteins. Cell membranes are composed of a variety of lipids and proteins that form an insoluble bilayer array that has relatively little curvature over distances of several nm. Plasma lipoproteins are different in that they are much smaller, water-soluble, and have highly curved surfaces. A model of a high density lipoprotein (HDL) is shown in Figure 1. This model (d - 10 nm) contains a surface of polar lipids and proteins that surrounds a small core of insoluble lipids, mostly triglycerides and cholesteryl esters. The low density (LDL) (d - 25 nm) and very low density (VLDL) (d 90 nm) lipoproteins have similar architectures, except the former has a cholesteryl ester core and the latter a core that is almost exclusively triglyceride (Figure 1). The surface proteins of HDL are amphiphilic and water soluble; the single protein of LDL is insoluble, whereas VLDL contains both soluble and insoluble proteins. The primary structures of all of these proteins are known.

Method for culturing mammalian cells in a horizontally rotated bioreactor

NASA Technical Reports Server (NTRS)

Schwarz, Ray P. (Inventor); Wolf, David A. (Inventor); Trinh, Tinh T. (Inventor)

1992-01-01

A bio-reactor system where cell growth microcarrier beads are suspended in a zero head space fluid medium by rotation about a horizontal axis and where the fluid is continuously oxygenated from a tubular membrane which rotates on a shaft together with rotation of the culture vessel. The oxygen is continuously throughput through the membrane and disbursed into the fluid medium along the length of the membrane.

Elevated Fecal Candida Counts in Patients with Antibiotic-Associated Diarrhea: Role of Soluble Fecal Substances

PubMed Central

Krause, Robert; Krejs, Günter J.; Wenisch, Christoph; Reisinger, Emil C.

2003-01-01

To assess the role of soluble fecal substances in the elevation of fecal Candida counts in patients with antibiotic-associated diarrhea (AAD), we investigated the growth of Candida albicans in vitro in serially diluted stool fluids from patients with AAD and healthy subjects. There were significantly higher Candida albicans counts in stool fluids diluted 1:10 from AAD patients than in healthy subjects and the phosphate-buffered saline growth control, which may be due to reduced soluble Candida inhibitors and increased availability of growth factors and nutrients. PMID:12522055

Methods and options in vitro dialyzability; benefits and limitations.

PubMed

Sandberg, Ann-Sofie

2005-11-01

In vitro dialyzability methods involve a two-step digestion process simulating the gastric and intestinal phase, and dialysis through a semi-permeable membrane with a selected molecular weight cut-off. Dialyzable iron/zinc is used as an estimation of available mineral. Final pH adjustment and use of a strict time schedule were found to be critical factors for standardization. In addition the selected cut-off of the dialysis membrane and the method used for iron and zinc determination influence the results. For screening purposes, simple solubility or dialyzability methods seem preferable to the more sophisticated computer-controlled gastrointestinal model. This is likely more valuable in studies of different transit times and sites of dialyzability. In vitro solubility/dialyzability methods correlate in most cases with human absorption studies in ranking iron and zinc availability from different meals. Exceptions may be that effects of milk, certain proteins, tea, and organic acids cannot be predicted. The dialyzability methods exclude iron bound to large molecules, which in some cases is available and include iron bound to small molecules, which is not always available. In vitro experiments based on solubility/dialyzability are tools to understand factors that may affect subsequent mineral absorption.

Ammonium in aqueous fluids to 600 °C, 1.3 GPa: A spectroscopic study on the effects on fluid properties, silica solubility, and K-feldspar to muscovite reactions

NASA Astrophysics Data System (ADS)

Schmidt, Christian; Watenphul, Anke

2010-12-01

The behavior of ammonium, NH 4+, in aqueous systems was studied based on Raman spectroscopic experiments to 600 °C and about 1.3 GPa. Spectra obtained at ambient conditions revealed a strong reduction of the dynamic three-dimensional network of water with addition of ammonium chloride, particularly at small solute concentrations. The differential scattering cross section of the ν 1-NH 4+ Raman band in these solutions was found to be similar to that of salammoniac. The Raman band of silica monomers at ˜780 cm -1 was present in all spectra of the fluid at high temperatures in hydrothermal diamond-anvil cell experiments with H 2O ± NH 4Cl and quartz or the assemblage quartz + kyanite + K-feldspar ± muscovite/tobelite. However, these spectra indicated that dissolved silica is less polymerized in ammonium chloride solutions than in comparable experiments with water. Quantification based on the normalized integrated intensity of the H 4SiO 40 band showed that the silica solubility in experiments with H 2O + NH 4Cl was significantly lower than that in equimolal NaCl solutions. This suggests that ammonium causes a stronger decrease in the activity of water in chloridic solutions than sodium. The Raman spectra of the fluid also showed that a significant fraction of ammonium was converted to ammonia, NH 3, in all experiments at temperatures above 300 °C. This indicates a shift towards acidic conditions for experiments without a buffering mineral assemblage. The estimated pH of the fluid was ˜2 at 600 °C, 0.26 GPa, 6.6 m initial NH 4Cl, based on the ratio of the integrated ν 1-NH 3 and ν 1-NH 4+ intensities and the HCl 0 dissociation constant. The NH 3/NH 4+ ratio increased with temperature and decreased with pressure. This implies that more ammonium should be retained in K-bearing minerals coexisting with chloridic fluids upon high- P low- T metamorphism. At 500 °C, 0.73 GPa, ammonium partitions preferentially into the fluid, as constrained from infrared spectroscopy on the muscovite and from mass balance. The conversion of K-feldspar to muscovite proceeded much faster in experiments with NH 4Cl solutions than in comparable experiments with water. This is interpreted as being caused by enhancement of the rate-limiting alumina solubility, suggesting complexation of Al with NH 4. Nucleation and growth of mica at the expense of K-feldspar and NH 4+/K + exchange between fluid and K-feldspar occurred simultaneously, but incorporation of NH 4+ into K-feldspar was distinctly faster than K-feldspar consumption.

Effect of Monomer Structure on Curing Behavior, CO2 Solubility, and Gas Permeability of Ionic Liquid-Based Epoxy-Amine Resins and Ion-Gels

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

McDanel, WM; Cowan, MG; Barton, JA

2015-04-29

New imidazolium- and pyrrolidinium-based bis(epoxide)-functionalized ionic liquid (IL) monorners were synthesized: and reacted with multifunctional amine monomers to produce cross-linked, epoxy-amine poly(ionic liquid) (PIL) resins and PIL/IL ion-gel membranes. The length and chemical nature (i.e., alkyl versus ether) between the irrildazolium group and epokitie groups were studied to determine their effects on CO2 affinity. The CO2 uptake (millimoles per gram) of the epoxy amine resins (between 0.1 and 1 mmol/g) was found to depend predominately on the epoxide-to-amine ratio and the bis(epoxide) IL molecular weight. The effect of using a primary versus a secondary amine-containing multifunctional monoiner was also assessedmore » for the resin-synthesis. Secondary amines can increase CO2 permeability but also increase the iime required for biS(epoxide) coriversion. When either the epoxide or athine monomer structure is changed, the CO2 solubility and permeability of the resulting PIL resins and ion-sel membranes can be tuned.« less

Numerical computations of the dynamics of fluidic membranes and vesicles

NASA Astrophysics Data System (ADS)

Barrett, John W.; Garcke, Harald; Nürnberg, Robert

2015-11-01

Vesicles and many biological membranes are made of two monolayers of lipid molecules and form closed lipid bilayers. The dynamical behavior of vesicles is very complex and a variety of forms and shapes appear. Lipid bilayers can be considered as a surface fluid and hence the governing equations for the evolution include the surface (Navier-)Stokes equations, which in particular take the membrane viscosity into account. The evolution is driven by forces stemming from the curvature elasticity of the membrane. In addition, the surface fluid equations are coupled to bulk (Navier-)Stokes equations. We introduce a parametric finite-element method to solve this complex free boundary problem and present the first three-dimensional numerical computations based on the full (Navier-)Stokes system for several different scenarios. For example, the effects of the membrane viscosity, spontaneous curvature, and area difference elasticity (ADE) are studied. In particular, it turns out, that even in the case of no viscosity contrast between the bulk fluids, the tank treading to tumbling transition can be obtained by increasing the membrane viscosity. Besides the classical tank treading and tumbling motions, another mode (called the transition mode in this paper, but originally called the vacillating-breathing mode and subsequently also called trembling, transition, and swinging mode) separating these classical modes appears and is studied by us numerically. We also study how features of equilibrium shapes in the ADE and spontaneous curvature models, like budding behavior or starfish forms, behave in a shear flow.

Glomeruli of Dense Deposit Disease contain components of the alternative and terminal complement pathway

PubMed Central

Sethi, Sanjeev; Gamez, Jeffrey D.; Vrana, Julie A.; Theis, Jason D.; Bergen, H. Robert; Zipfel, Peter F.; Dogan, Ahmet; Smith, Richard J. H.

2009-01-01

Dense Deposit Disease (DDD), or membranoproliferative glomerulonephritis type II, is a rare renal disease characterized by dense deposits in the mesangium and along the glomerular basement membranes that can be seen by electron microscopy. Although these deposits contain complement factor C3, as determined by immunofluorescence microscopy, their precise composition remains unknown. To address this question, we used mass spectrometry to identify the proteins in laser microdissected glomeruli isolated from paraffin-embedded tissue of eight confirmed cases of DDD. Compared to glomeruli from five control patients, we found that all of the glomeruli from patients with DDD contain components of the alternative pathway and terminal complement complex. Factor C9 was uniformly present as well as the two fluid-phase regulators of terminal complement complex clusterin and vitronectin. In contrast, in nine patients with immune complex–mediated membranoproliferative glomerulonephritis, glomerular samples contained mainly immunoglobulins and complement factors C3 and C4. Our study shows that in addition to fluid-phase dysregulation of the alternative pathway, soluble components of the terminal complement complex contribute to glomerular lesions found in DDD. PMID:19177158

Generic instabilities in a fluid membrane coupled to a thin layer of ordered active polar fluid.

PubMed

Sarkar, Niladri; Basu, Abhik

2013-08-01

We develop an effective two-dimensional coarse-grained description for the coupled system of a planar fluid membrane anchored to a thin layer of polar ordered active fluid below. The macroscopic orientation of the active fluid layer is assumed to be perpendicular to the attached membrane. We demonstrate that activity or nonequilibrium drive of the active fluid makes such a system generically linearly unstable for either signature of a model parameter [Formula: see text] [Formula: see text] that characterises the strength of activity. Depending upon boundary conditions and within a range of the model parameters, underdamped propagating waves may be present in our model. We discuss the phenomenological significance of our results.

Sulfur radical species form gold deposits on Earth

PubMed Central

Pokrovski, Gleb S.; Kokh, Maria A.; Guillaume, Damien; Borisova, Anastassia Y.; Gisquet, Pascal; Hazemann, Jean-Louis; Lahera, Eric; Del Net, William; Proux, Olivier; Testemale, Denis; Haigis, Volker; Jonchière, Romain; Seitsonen, Ari P.; Ferlat, Guillaume; Vuilleumier, Rodolphe; Saitta, Antonino Marco; Boiron, Marie-Christine; Dubessy, Jean

2015-01-01

Current models of the formation and distribution of gold deposits on Earth are based on the long-standing paradigm that hydrogen sulfide and chloride are the ligands responsible for gold mobilization and precipitation by fluids across the lithosphere. Here we challenge this view by demonstrating, using in situ X-ray absorption spectroscopy and solubility measurements, coupled with molecular dynamics and thermodynamic simulations, that sulfur radical species, such as the trisulfur ion S3−, form very stable and soluble complexes with Au+ in aqueous solution at elevated temperatures (>250 °C) and pressures (>100 bar). These species enable extraction, transport, and focused precipitation of gold by sulfur-rich fluids 10–100 times more efficiently than sulfide and chloride only. As a result, S3− exerts an important control on the source, concentration, and distribution of gold in its major economic deposits from magmatic, hydrothermal, and metamorphic settings. The growth and decay of S3− during the fluid generation and evolution is one of the key factors that determine the fate of gold in the lithosphere. PMID:26460040

Effect of antimicrobial peptide on dynamics of phosphocholine membrane: role of cholesterol and physical state of bilayer

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

Sharma, Veerendra K.; Mamontov, Eugene; Anunciado, Divina B.

Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fallmore » in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol % cholesterol. Thus, our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol.« less

Effect of antimicrobial peptide on dynamics of phosphocholine membrane: role of cholesterol and physical state of bilayer

DOE PAGES

Sharma, Veerendra K.; Mamontov, Eugene; Anunciado, Divina B.; ...

2015-06-24

Antimicrobial peptides are universal in all forms of life and are well known for their strong interaction with the cell membrane. This makes them a popular target for investigation of peptide-lipid interactions. Here we report the effect of melittin, an important antimicrobial peptide, on the dynamics of membranes based on 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid in both the solid gel and fluid phases. To probe the phase transition, elastic neutron intensity temperature scans have been carried out on DMPC-based unilamellar vesicles (ULV) with and without melittin. We have found that addition of a small amount (0.2 mol%) melittin eliminates the steep fallmore » in the elastic intensity at 296 K associated with the solid gel to fluid phase transition, which is observed for pure DMPC vesicles. Quasielastic neutron scattering (QENS) experiments have been carried out on DMPC ULV in the solid gel and fluid phases with and without 0.2 mol % melittin. The data analysis invariably shows the presence of lateral and internal motions of the DMPC molecule. We found that melittin does have a profound effect on the dynamics of lipid molecules, especially on the lateral motion, and affects it in a different way, depending on the phase of the bilayers. In the solid gel phase, it acts as a plasticizer, enhancing the lateral motion of DMPC. However, in the fluid phase it acts as a stiffening agent, restricting the lateral motion of the lipid molecules. These observations are consistent with the mean squared displacements extracted from the elastic intensity temperature scans. Cholesterol is a vital component of eukaryotic membrane, which is a natural target for melittin. To investigate the effect of melittin on vesicles supplemented with cholesterol, QENS experiments have also been carried out on DMPC ULV with 20 mol% cholesterol in the presence and absence of 0.2 mol% melittin. Remarkably, the effects of melittin on the membrane dynamics disappear in the presence of 20 mol % cholesterol. Thus, our measurements indicate that the destabilizing effect of the peptide melittin on membranes can be mitigated by the presence of cholesterol.« less

Supercritical fluid particle design for poorly water-soluble drugs (review).

PubMed

Sun, Yongda

2014-01-01

Supercritical fluid particle design (SCF PD) offers a number of routes to improve solubility and dissolution rate for enhancing the bioavailability of poorly water-soluble drugs, which can be adopted through an in-depth knowledge of SCF PD processes and the molecular properties of active pharmaceutical ingredients (API) and drug delivery system (DDS). Combining with research experiences in our laboratory, this review focuses on the most recent development of different routes (nano-micron particles, polymorphic particles, composite particles and bio-drug particles) to improve solubility and dissolution rate of poorly water-soluble drugs, covering the fundamental concept of SCF and the principle of SCF PD processes which are typically used to control particle size, shape, morphology and particle form and hence enable notable improvement in the dissolution rate of the poorly water-soluble drugs. The progress of the industrialization of SCF PD processes in pharmaceutical manufacturing environment with scaled-up plant under current good manufacturing process (GMP) specification is also considered in this review.

Biphasic catalysis in water/carbon dioxide micellar systems

DOEpatents

Jacobson, Gunilla B.; Tumas, William; Johnston, Keith P.

2002-01-01

A process is provided for catalyzing an organic reaction to form a reaction product by placing reactants and a catalyst for the organic reaction, the catalyst of a metal complex and at least one ligand soluble within one of the phases of said aqueous biphasic system, within an aqueous biphasic system including a water phase, a dense phase fluid, and a surfactant adapted for forming an emulsion or microemulsion within the aqueous biphasic system, the reactants soluble within one of the phases of the aqueous biphasic system and convertible in the presence of the catalyst to a product having low solubility in the phase in which the catalyst is soluble; and, maintaining the aqueous biphasic system under pressures, at temperatures, and for a period of time sufficient for the organic reaction to occur and form the reaction product and to maintain sufficient density on the dense phase fluid, the reaction product characterized as having low solubility in the phase in which the catalyst is soluble.

Single-step preparation of selected biological fluids for the high performance liquid chromatographic analysis of fat-soluble vitamins and antioxidants.

PubMed

Lazzarino, Giacomo; Longo, Salvatore; Amorini, Angela Maria; Di Pietro, Valentina; D'Urso, Serafina; Lazzarino, Giuseppe; Belli, Antonio; Tavazzi, Barbara

2017-12-08

Fat-soluble vitamins and antioxidants are of relevance in health and disease. Current methods to extract these compounds from biological fluids mainly need use of multi-steps and multi organic solvents. They are time-consuming and difficult to apply to treat simultaneously large sample number. We here describe a single-step, one solvent extraction of fat-soluble vitamins and antioxidants from biological fluids, and the chromatographic separation of all-trans-retinoic acid, 25-hydroxycholecalciferol, all-trans-retinol, astaxanthin, lutein, zeaxanthin, trans-β-apo-8'-carotenal, γ-tocopherol, β-cryptoxanthin, α-tocopherol, phylloquinone, lycopene, α-carotene, β-carotene and coenzyme Q 10 . Extraction is obtained by adding one volume of biological fluid to two acetonitrile volumes, vortexing for 60s and incubating for 60min at 37°C under agitation. HPLC separation occurs in 30min using Hypersil C18, 100×4.6mm, 5μm particle size column, gradient from 70% methanol+30% H 2 O to 100% acetonitrile, flow rate of 1.0ml/min and 37°C column temperature. Compounds are revealed using highly sensitive UV-VIS diode array detector. The HPLC method suitability was assessed in terms of sensitivity, reproducibility and recovery. Using the present extraction and chromatographic conditions we obtained values of the fat-soluble vitamins and antioxidants in serum from 50 healthy controls similar to those found in literature. Additionally, the profile of these compounds was also measured in seminal plasma from 20 healthy fertile donors. Results indicate that this simple, rapid and low cost sample processing is suitable to extract fat-soluble vitamins and antioxidants from biological fluids and can be applied in clinical and nutritional studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface functionalization of a polymeric lipid bilayer for coupling a model biological membrane with molecules, cells, and microstructures.

PubMed

Morigaki, Kenichi; Mizutani, Kazuyuki; Saito, Makoto; Okazaki, Takashi; Nakajima, Yoshihiro; Tatsu, Yoshiro; Imaishi, Hiromasa

2013-02-26

We describe a stable and functional model biological membrane based on a polymerized lipid bilayer with a chemically modified surface. A polymerized lipid bilayer was formed from a mixture of two diacetylene-containing phospholipids, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC) and 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphoethanolamine (DiynePE). DiynePC formed a stable bilayer structure, whereas the ethanolamine headgroup of DiynePE enabled functional molecules to be grafted onto the membrane surface. Copolymerization of DiynePC and DiynePE resulted in a robust bilayer. Functionalization of the polymeric bilayer provided a route to a robust and biomimetic surface that can be linked with biomolecules, cells, and three-dimensional (3D) microstructures. Biotin and peptides were grafted onto the polymeric bilayer for attaching streptavidin and cultured mammalian cells by molecular recognition, respectively. Nonspecific adsorption of proteins and cells on polymeric bilayers was minimum. DiynePE was also used to attach a microstructure made of an elastomer (polydimethylsiloxan: PDMS) onto the membrane, forming a confined aqueous solution between the two surfaces. The microcompartment enabled us to assay the activity of a membrane-bound enzyme (cyochrome P450). Natural (fluid) lipid bilayers were incorporated together with membrane-bound proteins by lithographically polymerizing DiynePC/DiynePE bilayers. The hybrid membrane of functionalized polymeric bilayers and fluid bilayers offers a novel platform for a wide range of biomedical applications including biosensor, bioassay, cell culture, and cell-based assay.

Nonperturbative Renormalization Group Approach to Polymerized Membranes

NASA Astrophysics Data System (ADS)

Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

2014-03-01

Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

Application research of computational mass-transfer differential equation in MBR concentration field simulation.

PubMed

Li, Chunqing; Tie, Xiaobo; Liang, Kai; Ji, Chanjuan

2016-01-01

After conducting the intensive research on the distribution of fluid's velocity and biochemical reactions in the membrane bioreactor (MBR), this paper introduces the use of the mass-transfer differential equation to simulate the distribution of the chemical oxygen demand (COD) concentration in MBR membrane pool. The solutions are as follows: first, use computational fluid dynamics to establish a flow control equation model of the fluid in MBR membrane pool; second, calculate this model by adopting direct numerical simulation to get the velocity field of the fluid in membrane pool; third, combine the data of velocity field to establish mass-transfer differential equation model for the concentration field in MBR membrane pool, and use Seidel iteration method to solve the equation model; last but not least, substitute the real factory data into the velocity and concentration field model to calculate simulation results, and use visualization software Tecplot to display the results. Finally by analyzing the nephogram of COD concentration distribution, it can be found that the simulation result conforms the distribution rule of the COD's concentration in real membrane pool, and the mass-transfer phenomenon can be affected by the velocity field of the fluid in membrane pool. The simulation results of this paper have certain reference value for the design optimization of the real MBR system.

Fluctuation of Ultrafiltration Coefficient of Hemodialysis Membrane During Reuse

NASA Astrophysics Data System (ADS)

Arif, Idam; Christin

2010-12-01

Hemodialysis treatment for patient with kidney failure is to regulate body fluid and to excrete waste products of metabolism. The patient blood and the dialyzing solution (dialysate) are flowed counter currently in a dialyzer to allow volume flux of fluid and diffusion of solutes from the blood to the dialysate through a semipermiable membrane. The volume flux of fluid depends on the hydrostatic and the osmotic pressure difference between the blood and the dialysate. It also depends on the membrane parameter that represents how the membrane allows the fluid and the solutes to move across as a result of the pressure difference, known as the ultrafiltration coefficient Kuf. The coefficient depends on the number and the radius of membrane pores for the movement of the fluids and the solutes across the membrane. The measured membrane ultrafiltration coefficient of reused dialyzer shows fluctuation between one uses to another without any significant trend of change. This indicates that the cleaning process carried out before reuse does not cause perfect removal of clots that happen in the previous use. Therefore the unblocked pores are forced to work hardly to obtain targeted volume flux in a certain time of treatment. This may increase the unblocked pore radius. Reuse is stopped when there is indication of blood leakage during the hemodialysis treatment.

Isomeric Detergent Comparison for Membrane Protein Stability: Importance of Inter-Alkyl-Chain Distance and Alkyl Chain Length

PubMed Central

Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S.; Du, Yang; Nielsen, Anne K.; Byrne, Bernadette; Kobilka, Brian K.; Loland, Claus J.; Guan, Lan

2017-01-01

Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C12 alkyl chain was most effective at maintaining solubility/stability of the membrane proteins. We propose that interplay between the hydrophile–lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane proteins. PMID:27981750

Improving the performance of membrane bioreactors by powdered activated carbon dosing with cost considerations.

PubMed

Yang, W; Paetkau, M; Cicek, N

2010-01-01

Effects of powdered activated carbon (PAC) dosing on the overall performance of membrane bioreactors (MBR) were investigated in two bench-scale submerged MBRs. Positive impacts of PAC dosing on membrane fouling and the removal of 17beta-estradiol (E2) and 17alpha-ethyinylestradiol (EE2) were demonstrated over a six-month stable operational period. PAC dosing in the MBR increased the removal rates of E2 and EE2 by 3.4% and 15.8%, respectively. The average soluble extracellular polymeric substances (EPS) and colloidal total organic carbon (TOC) concentrations in the PAC-MBR sludge was 60.1% and 61.8% lower than the control MBR sludge, respectively. Lower soluble EPS and colloidal TOC concentrations in the PAC-MBR sludge resulted in a slower rate of trans-membrane pressure (TMP) increase during MBRs operation, which could prolong the lifespan of membranes. Cost assessment showed that PAC dosing could reduce the operating cost for membrane cleaning and/or membrane replacement by about 25%. The operating cost for PAC dosing could be offset by the benefit from its reducing the cost for membrane maintenance.

Membrane Transport Phenomena (MTP)

NASA Technical Reports Server (NTRS)

Mason, Larry W.

1996-01-01

The development of the seal between the membrane and the Fluid Optical Cells (FOC) has been a high priority activity. This seal occurs at an interface in the instrument where three key functions must be realized: (1) physical membrane support, (2) fluid sealing, and (3) unobscured optical transmission.

Mechanical membrane for the separation of a paramagnetic constituent from a fluid

DOEpatents

Maurice, David

2017-05-02

The disclosure provides an apparatus and method for the separation of a paramagnetic component from a mixture using a mechanical membrane apparatus. The mechanical membrane comprises a supporting material having a plurality of pores where each pore is surrounded by a plurality of magnetic regions. The magnetic regions augment a magnetic field on one side of the supporting material while mitigating the field to near zero on the opposite side. In operation, a flow of fluid such as air comprising a paramagnetic component such as O.sub.2 is directed toward the mechanical membrane, and the paramagnetic component is typically attracted toward a magnetic field surrounding a pore while dimagnetic components such as N.sub.2 are generally repelled. As some portion of the fluid passes through the plurality of magnetic apertures to the opposite side of the mechanical membrane, the mechanical membrane generates a fluid enriched in the paramagnetic component. Alternately, the magnetic field may act to repel the paramagnetic component while diamagnetic components such as N.sub.2 are generally unaffected and pass to the opposite side of the mechanical membrane.

Smart membranes for nitrate removal, water purification, and selective ion transportation

DOEpatents

Wilson, William D [Pleasanton, CA; Schaldach, Charlene M [Pleasanton, CA; Bourcier, William L [Livermore, CA; Paul, Phillip H [Livermore, CA

2009-12-15

A computer designed nanoengineered membrane for separation of dissolved species. One embodiment provides an apparatus for treatment of a fluid that includes ions comprising a microengineered porous membrane, a system for producing an electrical charge across the membrane, and a series of nanopores extending through the membrane. The nanopores have a pore size such that when the fluid contacts the membrane, the nanopores will be in a condition of double layer overlap and allow passage only of ions opposite to the electrical charge across the membrane.

Design and Implementation of Energized Fracture Treatment in Tight Gas Sands

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

Mukul Sharma; Kyle Friehauf

2009-12-31

Hydraulic fracturing is essential for producing gas and oil at an economic rate from low permeability sands. Most fracturing treatments use water and polymers with a gelling agent as a fracturing fluid. The water is held in the small pore spaces by capillary pressure and is not recovered when drawdown pressures are low. The un-recovered water leaves a water saturated zone around the fracture face that stops the flow of gas into the fracture. This is a particularly acute problem in low permeability formations where capillary pressures are high. Depletion (lower reservoir pressures) causes a limitation on the drawdown pressuremore » that can be applied. A hydraulic fracturing process can be energized by the addition of a compressible, sometimes soluble, gas phase into the treatment fluid. When the well is produced, the energized fluid expands and gas comes out of solution. Energizing the fluid creates high gas saturation in the invaded zone, thereby facilitating gas flowback. A new compositional hydraulic fracturing model has been created (EFRAC). This is the first model to include changes in composition, temperature, and phase behavior of the fluid inside the fracture. An equation of state is used to evaluate the phase behavior of the fluid. These compositional effects are coupled with the fluid rheology, proppant transport, and mechanics of fracture growth to create a general model for fracture creation when energized fluids are used. In addition to the fracture propagation model, we have also introduced another new model for hydraulically fractured well productivity. This is the first and only model that takes into account both finite fracture conductivity and damage in the invaded zone in a simple analytical way. EFRAC was successfully used to simulate several fracture treatments in a gas field in South Texas. Based on production estimates, energized fluids may be required when drawdown pressures are smaller than the capillary forces in the formation. For this field, the minimum CO{sub 2} gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flow rate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO{sub 2} outperforms N{sub 2} as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid's ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO{sub 2}. N{sub 2} should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.« less

Risk assessment of bioaccessible trace elements in smoke haze aerosols versus urban aerosols using simulated lung fluids

NASA Astrophysics Data System (ADS)

Huang, Xian; Betha, Raghu; Tan, Li Yun; Balasubramanian, Rajasekhar

2016-01-01

Smoke-haze episodes, caused by uncontrolled peat and forest fires, occur almost every year in the South-East Asian region with increased concentrations of PM2.5 (airborne particulate matter (PM) with diameter ≤ 2.5 μm). Particulate-bound trace elements (TrElems), especially carcinogenic and toxic elements, were measured during smoke haze as well as non-haze periods in 2014 as they are considered to be indicators of potential health effects. The bioaccessibilities of 13 TrElems were investigated using two types of simulated lung fluids (SLFs), Gamble's solution and artificial lysosomal fluid (ALF), instead of the commonly used leaching agent (water). The dissolution kinetics was also examined for these TrElems. Many TrElems showed higher solubility in SLFs, and were more soluble in ALF compared to the Gamble's solution. Cu, Mn and Cd were observed to be the most soluble trace elements in ALF, while in Gamble's solution the most soluble trace elements were Cu, Mn and Zn. The dissolution rates were highly variable among the elements. Health risk assessment was conducted based on the measured concentrations of TrElems and their corresponding toxicities for three possible scenarios involving interactions between carcinogenic and toxic TrElems and SLFs, using the United States Environmental Protection Agency (USEPA) human health risk assessment model. The cumulative cancer risks exceeded the acceptable level (1 in a million i.e. 1 × 10-6). However, the estimation of health quotient (HQ) indicated no significant chronic toxic health effects. The risk assessment results revealed that the assessment of bioaccessibility of particulate-bound TrElems using water as the leaching agent may underestimate the health risk.

Evidence for Different Reaction Pathways for Liquid and Granular Micronutrients in a Calcareous Soil

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

Hettiarachchi, Ganga M.; McLaughlin, Mike J.; Scheckel, Kirk G.

2008-06-16

The benefits of Mn and Zn fluid fertilizers over conventional granular products in calcareous sandy loam soils have been agronomically demonstrated. We hypothesized that the differences in the effectiveness between granular and fluid Mn and Zn fertilizers is due to different Mn and Zn reaction processes in and around fertilizer granules and fluid fertilizer bands. We used a combination of several synchrotron-based x-ray techniques, namely, spatially resolved micro-x-ray fluorescence (?-XRF), micro-x-ray absorption near edge structure spectroscopy (?-XANES), and bulk-XANES and -extended x-ray absorption fine structure (EXAFS) spectroscopy, along with several laboratory-based x-ray techniques to speciate different fertilizer-derived Mn and Znmore » species in highly calcareous soils to understand the chemistry underlying the observed differential behavior of fluid and granular micronutrient forms. Micro-XRF mapping of soil-fertilizer reactions zones indicated that the mobility of Mn and Zn from liquid fertilizer was greater than that observed for equivalent granular sources of these micronutrients in soil. After application of these micronutrient fertilizers to soil, Mn and Zn from liquid fertilizers were found to remain in comparatively more soluble solid forms, such as hydrated Mn phosphate-like, Mn calcite-like, adsorbed Zn-like, and Zn silicate-like phases, whereas Mn and Zn from equivalent granular sources tended to transform into comparatively less soluble solid forms such as Mn oxide-like, Mn carbonate-like, and Zn phosphate-like phases.« less

CO2/pH-Controllable Viscoelastic Nanostructured Fluid Based on Stearic Acid Soap and Bola-Type Quaternary Ammonium Salt.

PubMed

Zhang, Yongmin; Kong, Weiwei; An, Pengyun; He, Shuai; Liu, Xuefeng

2016-03-15

Fatty acid soaps such as sodium stearate (NaOSA) represent a class of cheap, environmentally friendly surfactants; however, their poor solubility seriously challenges their application in various fields. Herein, we describe a CO2/pH-controllable viscoelastic nanostructured fluid, which was developed by simple mixing of the commodity soap NaOSA with a bola-type quaternary ammonium salt (Bola2be) in a 2:1 molar ratio without the need for complex organic synthesis. The introduction of Bola2be increased NaOSA solubility and promoted micelle growth by forming a noncovalent pseudo-Gemini structure, 2NaOSA-Bola2be. Long aggregates are formed with increases in concentration, and these become entangled into a three-dimensional network at 10 times that of the critical micelle concentration (0.057 mM), showing strong thickening ability. Micellar branching occurs above 22.38 mM, as deduced by rheology and verified by cryo-transmission electron microscopy. The worm-based fluid formed from the noncovalent pseudo-Gemini surfactant is highly thermosensitive, and features a higher flow activation energy of 399.76 kJ·mol(-1) compared with common worm systems. Because of the pH-sensitivity of NaOSA, the viscoelastic fluid can respond to common pH stimuli or green CO2 gas, and shows a transition between a gel-like wormlike micellar network and a water-like dispersion with precipitate. However, the CO2-responsive behavior is irreversible.

Improved computational fluid dynamic simulations of blood flow in membrane oxygenators from X-ray imaging.

PubMed

Jones, Cameron C; McDonough, James M; Capasso, Patrizio; Wang, Dongfang; Rosenstein, Kyle S; Zwischenberger, Joseph B

2013-10-01

Computational fluid dynamics (CFD) is a useful tool in characterizing artificial lung designs by providing predictions of device performance through analyses of pressure distribution, perfusion dynamics, and gas transport properties. Validation of numerical results in membrane oxygenators has been predominantly based on experimental pressure measurements with little emphasis placed on confirmation of the velocity fields due to opacity of the fiber membrane and limitations of optical velocimetric methods. Biplane X-ray digital subtraction angiography was used to visualize flow of a blood analogue through a commercial membrane oxygenator at 1-4.5 L/min. Permeability and inertial coefficients of the Ergun equation were experimentally determined to be 180 and 2.4, respectively. Numerical simulations treating the fiber bundle as a single momentum sink according to the Ergun equation accurately predicted pressure losses across the fiber membrane, but significantly underestimated velocity magnitudes in the fiber bundle. A scaling constant was incorporated into the numerical porosity and reduced the average difference between experimental and numerical values in the porous media regions from 44 ± 4% to 6 ± 5%.

Mechanisms of action of particles used for fouling mitigation in membrane bioreactors.

PubMed

Loulergue, P; Weckert, M; Reboul, B; Cabassud, C; Uhl, W; Guigui, C

2014-12-01

Adding chemicals to the biofluid is an option to mitigate membrane fouling in membrane bioreactors. In particular, previous studies have shown that the addition of particles could enhance activated sludge filterability. Nevertheless, the mechanisms responsible for the improved filtration performance when particles are added are still unclear. Two main mechanisms might occur: soluble organic matter adsorption onto the particles and/or cake structure modification. To date, no studies have clearly dissociated the impact of these two phenomena as a method was needed for the in-line characterization of the cake structure during filtration. The objective of this study was thus to apply, for the first time, an optical method for in-situ, non-invasive, characterization of cake structure during filtration of a real biofluid in presence of particles. This method was firstly used to study local cake compressibility during the biofluid filtration. It was found that the first layers of the cake were incompressible whereas the cake appeared to be compressible at global scale. This questions the global scale analysis generally used to study cake compressibility and highlights the interest of coupling local characterization with overall process performance analysis. Secondly, the impact of adding submicronic melamine particles into the biofluid was studied. It appears that particles added into the biofluid strongly influence the cake properties, making it thicker and more permeable. Furthermore, by using liquid chromatography with an organic carbon detector to determine the detailed characteristics of the feed and permeate, it was shown that the modification of cake structure also affected the retention of soluble organic compounds by the membrane and thus the cake composition. Simultaneous use of a method for in-situ characterization of the cake structure with a detailed analysis of the fluid composition and monitoring of the global performance is thus a powerful method for evaluating cake structure and composition and their impact on global process performance. The use of this methodology should allow "cake engineering" to be developed so that cake properties (structure, composition) can be controlled and process performance optimized. Copyright © 2014 Elsevier Ltd. All rights reserved.

Alumino-silicate speciation in aqueous fluids at deep crustal conditions

NASA Astrophysics Data System (ADS)

Mookherjee, M.; Keppler, H.; Manning, C. E.

2014-12-01

Alumina and silica are major oxides in most crustal rocks. While SiO2 is quite soluble in aqueous fluids at metamorphic conditions, behavior of Al2O3 in crustal metamorphic fluids has been poorly understood. It is known that alumina is dramatically less soluble in aqueous fluids and hence it is difficult to explain the common occurrence of quartz with aluminous minerals in metamorphic veins. In order to understand this complex behavior of alumina, we investigated aluminum speciation in aqueous fluids in equilibrium with corundum using in situ Raman spectroscopy in hydrothermal diamond anvil cells to 20 kbar and 1000 oC. In order to better understand the spectral features of the aqueous fluids, we used first principles simulations based on density functional theory to calculate and predict the energetics and vibrational spectra for various aluminum species that are likely to be present in aqueous solutions. The Raman spectra of pure water in equilibrium with Al2O3 are devoid of any characteristic spectral features. In contrast, aqueous fluids with KOH solution in equilibrium with Al2O3 show a sharp band at ~620 cm-1 which could be attributed to the [Al(OH)4]1- species. The band grows in intensity with temperature along an isochore. In the limited pressure, temperature and density explored in the present study, we do not find any evidence for the polymerization of the [Al(OH)4]1- species to dimers [(OH)2-Al-O2-Al(OH)2]2- or [(OH)3-Al-O-Al(OH)3]2-. This is likely due to the relatively low concentration of Al in the solutions and does not rule out significant polymerization at higher pressures and temperatures. We are also investigating the effect of SiO2 on the solubility of Al2O3 and the relative energetics of formation of pure alumina dimer [(OH)3-Al-O-Al(OH)3]2- vs. the aluminosilicate dimers, [(OH)3-Al-O-Si(OH)3]2- at deep crustal conditions. Acknowledgement- MM is supported by the US National Science Foundation grant (EAR-1250477).

Cocrystals of Hydrochlorothiazide: Solubility and Diffusion/Permeability Enhancements through Drug-Coformer Interactions.

PubMed

Sanphui, Palash; Devi, V Kusum; Clara, Deepa; Malviya, Nidhi; Ganguly, Somnath; Desiraju, Gautam R

2015-05-04

Hydrochlorothiazide (HCT) is a diuretic and a BCS class IV drug with low solubility and low permeability, exhibiting poor oral absorption. The present study attempts to improve the physicochemical properties of the drug using a crystal engineering approach with cocrystals. Such multicomponent crystals of HCT with nicotinic acid (NIC), nicotinamide (NCT), 4-aminobenzoic acid (PABA), succinamide (SAM), and resorcinol (RES) were prepared using liquid-assisted grinding, and their solubilities in pH 7.4 buffer were evaluated. Diffusion and membrane permeability were studied using a Franz diffusion cell. Except for the SAM and NIC cocrystals, all other binary systems exhibited improved solubility. All of the cocrystals showed improved diffusion/membrane permeability compared to that of HCT with the exception of the SAM cocrystal. When the solubility was high, as in the case of PABA, NCT, and RES cocrystals, the flux/permeability dropped slightly. This is in agreement with the expected interplay between solubility and permeability. Improved solubility/permeability is attributed to new drug-coformer interactions. Cocrystals of SAM, however, showed poor solubility and flux. This cocrystal contains a primary sulfonamide dimer synthon similar to that of HCT polymorphs, which may be a reason for its unusual behavior. Hirshfeld surface analysis was carried out in all cases to determine whether a correlation exists between cocrystal permeability and drug-coformer interactions.

Highly water-soluble BODIPY-based fluorescent probe for sensitive and selective detection of nitric oxide in living cells.

PubMed

Vegesna, Giri K; Sripathi, Srinivas R; Zhang, Jingtuo; Zhu, Shilei; He, Weilue; Luo, Fen-Tair; Jahng, Wan Jin; Frost, Megan; Liu, Haiying

2013-05-22

A highly water-soluble BODIPY dye bearing electron-rich o-diaminophenyl groups at 2,6-positions was prepared as a highly sensitive and selective fluorescent probe for detection of nitric oxide (NO) in living cells. The fluorescent probe displays an extremely weak fluorescence with fluorescence quantum yield of 0.001 in 10 mM phosphate buffer (pH 7.0) in the absence of NO as two electron-rich o-diaminophenyl groups at 2,6-positions significantly quench the fluorescence of the BODIPY dye via photoinduced electron transfer mechanism. The presence of NO in cells enhances the dye fluorescence dramatically. The fluorescent probe demonstrates excellent water solubility, membrane permeability, and compatibility with living cells for sensitive detection of NO.

Quantitative analysis of the effect of supersaturation on in vivo drug absorption.

PubMed

Takano, Ryusuke; Takata, Noriyuki; Saito, Ryoichi; Furumoto, Kentaro; Higo, Shoichi; Hayashi, Yoshiki; Machida, Minoru; Aso, Yoshinori; Yamashita, Shinji

2010-10-04

The purpose of this study is to clarify the effects of intestinal drug supersaturation on solubility-limited nonlinear absorption. Oral absorption of a novel farnesyltransferase inhibitor (FTI-2600) from its crystalline free base and its HCl salt was determined in dogs. To clarify the contribution of supersaturation on improving drug absorption, in vivo intraluminal concentration of FTI-2600 after oral administration was estimated from the pharmacokinetics data using a physiologically based model. Dissolution and precipitation characteristics of FTI-2600 in a biorelevant media were investigated in vitro using a miniscale dissolution test and powder X-ray diffraction analysis. In the in vitro study, the HCl salt immediately dissolved but precipitated rapidly. The metastable amorphous free base precipitant, which did not convert into the stable crystalline free base in the simulated intestinal fluids for several hours, generated a 5-fold increase in dissolved concentration compared to the equilibrium solubility of the crystalline free base. By computer simulation, the intraluminal drug concentration after administration of the free base was estimated to reach the saturated solubility, indicating solubility-limited absorption. On the other hand, administration of the HCl salt resulted in an increased intraluminal concentration and the plasma concentration was 400% greater than that after administration of the free base. This in vivo/in vitro correlation of the increased drug concentrations in the small intestine provide clear evidence that not only the increase in the dissolution rate, but also the supersaturation phenomenon, improved the solubility-limited absorption of FTI-2600. These results indicate that formulation technologies that can induce supersaturation may be of great assistance to the successful development of poorly water-soluble drugs.

Characterizing membrane foulants in MBR with addition of polyferric chloride to enhance phosphorus removal.

PubMed

Yang, Xiao-Li; Song, Hai-Liang; Chen, Ming; Cheng, Bing

2011-10-01

The effect of polymeric ferric chloride (PFC) addition on phosphorus removal and membrane fouling were investigated in an anoxic/oxic submerged membrane bioreactor. The total phosphorus concentration in effluent averaged at 0.26 mg/L with PFC addition of 10-15 mg/L, while the rate of membrane fouling increased 1.6 times over the control MBR (without PFC addition). Three-dimensional excitation-emission matrix fluorescence spectroscopy and Gel Filtration Chromatography analysis indicated that soluble microbial byproduct-like materials and large molecules (M(W)>100 kDa) were one of the main contributors of biofouling. Fourier transform infrared spectrum confirmed that the major components of the cake layer were proteins and polysaccharides materials. Scanning electron microscopy demonstrated that membrane surfaces were covered with compact gel layer formed by organic substances and Energy Dispersive X-ray analysis indicated that ferric metals were the most important inorganic pollutants. Consequently, soluble organic substances and dose of PFC should be controlled to minimize membrane fouling. Copyright © 2011 Elsevier Ltd. All rights reserved.

Changes in characteristics of soluble microbial products and extracellular polymeric substances in membrane bioreactor coupled with worm reactor: relation to membrane fouling.

PubMed

Tian, Yu; Li, Zhipeng; Lu, Yaobin

2012-10-01

The study focused on the membrane fouling mitigation observed in a membrane bioreactor (MBR) coupled with worm reactor system. During the operation time of 100 days, the transmembrane pressure (TMP) in the combined system was maintained less than 5 kPa, while the final TMP in the Control-MBR increased to 30 kPa. The changes in properties of soluble microbial products (SMP) and extracellular polymeric substances (EPS) after worm predation were investigated by means of various analytical techniques. It was found that due to the worm predation, the reduced amount of EPS was far more than the increased amount of SMP leading to a significant decrease of protein-like substances which were dominant in the membrane foulants. Except for the content decrease, worm predation destroyed the functional groups of simple aromatic proteins and tryptophan protein-like substances in EPS, making them have lower tendency attaching to the membrane in the combined system. Copyright © 2012 Elsevier Ltd. All rights reserved.

Exosomal miRNAs as potential biomarkers of cardiovascular risk in children

PubMed Central

2014-01-01

Intercellular interactions are essential for basic cellular activities and errors in either receiving or transferring these signals have shown to cause pathological conditions. These signals are not only regulated by membrane surface molecules but also by soluble secreted proteins, thereby allowing for an exquisite coordination of cell functions. Exosomes are released by cells upon fusion of multivesicular bodies (MVB) with the plasma membrane. Their envelope reflects their cellular origin and their surface and internal contents include important signaling components. Exosomes contain a wide variety of proteins, lipids, RNAs, non-transcribed RNAs, miRNAs and small RNAs that are representative to their cellular origin and shuttle from donor cells to recipient cells. The exosome formation cargo content and delivery is of immense biological interest because exosomes are believed to play major roles in various pathological conditions, and therefore provide unique opportunities for biomarker discovery and development of non-invasive diagnostics when examined in biological fluids such as urine and blood plasma. For example, circulating miRNAs in exosomes have been applied as functional biomarkers for diagnosis and outcomes prediction, while synthetic miRNAs in polymer-based nanoparticles are applicable for therapeutics. This review provides insights into the composition and functional properties of exosomes, and focuses on their potential value as diagnostic markers in the context of cardiovascular disease risk estimates in children who suffer from conditions associated with heightened prevalence of adverse cardiovascular disease, namely obesity and sleep-disordered-breathing. PMID:24912806

Enhancing Membrane Protein Identification Using a Simplified Centrifugation and Detergent-Based Membrane Extraction Approach.

PubMed

Zhou, Yanting; Gao, Jing; Zhu, Hongwen; Xu, Jingjing; He, Han; Gu, Lei; Wang, Hui; Chen, Jie; Ma, Danjun; Zhou, Hu; Zheng, Jing

2018-02-20

Membrane proteins may act as transporters, receptors, enzymes, and adhesion-anchors, accounting for nearly 70% of pharmaceutical drug targets. Difficulties in efficient enrichment, extraction, and solubilization still exist because of their relatively low abundance and poor solubility. A simplified membrane protein extraction approach with advantages of user-friendly sample processing procedures, good repeatability and significant effectiveness was developed in the current research for enhancing enrichment and identification of membrane proteins. This approach combining centrifugation and detergent along with LC-MS/MS successfully identified higher proportion of membrane proteins, integral proteins and transmembrane proteins in membrane fraction (76.6%, 48.1%, and 40.6%) than in total cell lysate (41.6%, 16.4%, and 13.5%), respectively. Moreover, our method tended to capture membrane proteins with high degree of hydrophobicity and number of transmembrane domains as 486 out of 2106 (23.0%) had GRAVY > 0 in membrane fraction, 488 out of 2106 (23.1%) had TMs ≥ 2. It also provided for improved identification of membrane proteins as more than 60.6% of the commonly identified membrane proteins in two cell samples were better identified in membrane fraction with higher sequence coverage. Data are available via ProteomeXchange with identifier PXD008456.

Hybrid microneedles devices for diagnostic and therapeutic applications: fabrication and preliminary results

NASA Astrophysics Data System (ADS)

Dardano, P.; Caliò, A.; Politi, J.; Di Palma, V.; Bevilacqua, M. F.; Rea, I.; Casalino, M.; Di Matteo, A.; Rendina, I.; De Stefano, L.

2015-06-01

Microneedles are newly developed biomedical devices, whose advantages are mainly in the non-invasiveness, discretion and versatility of use both as diagnostics and as therapeutics tool. In fact, they can be used both for drugs delivery in the interstitial fluids and for the analysis of the interstitial fluid. In this work we present the preliminary results for two devices based on micro needles in PolyEthylene (Glycol). The first for the drugs delivery includes a membrane whose optical reflected wavelength is related to the concentration of drug. Here, we present our preliminary result in diffusion of drugs between the membrane and the microneedles. The second device is gold coated and it works as electrode for the electrochemical detection of species in the interstitial fluid. A preliminary result in detection of glucose will be shown.

Fluid Mosaic Membranes and the Light Reactions of Photosynthesis.

ERIC Educational Resources Information Center

Hannay, Jack

1985-01-01

Discusses: (1) the fluid mosaic membrane structure and light reactions of photosynthesis as exemplified by the Hill and Bendall "Z-scheme"; (2) the arrangement of light-harvesting pigments, electron transport components, and ATP synthesis on chloroplast membranes; and (3) how these topics are treated in A-level textbooks. (JN)

Amyloid-β(1–42) Protofibrils Formed in Modified Artificial Cerebrospinal Fluid Bind and Activate Microglia

PubMed Central

Paranjape, Geeta S.; Terrill, Shana E.; Gouwens, Lisa K.; Ruck, Benjamin M.; Nichols, Michael R.

2012-01-01

Soluble aggregated forms of amyloid-β protein (Aβ) have garnered significant attention recently for their role in Alzheimer’s disease (AD). Protofibrils are a subset of these soluble species and are considered intermediates in the aggregation pathway to mature Aβ fibrils. Biological studies have demonstrated that protofibrils exhibit both toxic and inflammatory activities. It is important in these in vitro studies to prepare protofibrils using solution conditions that are appropriate for cellular studies as well as conducive to biophysical characterization of protofibrils. Here we describe the preparation and characterization of Aβ(1–42) protofibrils in modified artificial cerebrospinal fluid (aCSF) and demonstrate their prominent binding and activation of microglial cells. A simple phosphate/bicarbonate buffer system was prepared that maintained the ionic strength and cell compatibility of F-12 medium but did not contain numerous supplements that interfere with spectroscopic analyses of Aβ protofibrils. Reconstitution of Aβ(1–42) in aCSF and isolation with size exclusion chromatography (SEC) revealed curvilinear β-sheet protofibrils <100 nm in length and hydrodynamic radii of 21 nm. Protofibril concentration determination by BCA assay, which was not possible in F-12 medium, was more accurately measured in aCSF. Protofibrils formed and isolated in aCSF, but not monomers, markedly stimulated TNFα production in BV-2 and primary microglia and bound in significant amounts to microglial membranes. This report demonstrates the suitability of a modified aCSF system for preparing SEC-isolated Aβ(1–42) protofibrils and underscores the unique ability of protofibrils to functionally interact with microglia. PMID:23242692

Association of gas hydrate formation in fluid discharges with anomalous hydrochemical profiles

NASA Astrophysics Data System (ADS)

Matveeva, T.

2009-04-01

Numerous investigations worldwide have shown that active underwater fluid discharge produces specific structures on the seafloor such as submarine seepages, vents, pockmarks, and collapse depressions. Intensive fluxes of fluids, especially of those containing hydrocarbon gases, result in specific geochemical and physical conditions favorable for gas hydrate (GH) formation. GH accumulations associated with fluid discharge are usually controlled by fluid conduits such as mud volcanoes, diapirs or faults. During last decade, subaqueous GHs become the subject of the fuel in the nearest future. However, the expediency of their commercial development can be proved solely by revealing conditions and mechanisms of GH formation. Kinetic of GH growth (although it is incompletely understood) is one of the important parameters controlling their formation among with gas solubility, pressure, temperature, gas quantity and others. Original large dataset on hydrate-related interstitial fluids obtained from different fluid discharge areas at the Sea of Okhotsk, Black Sea, Gulf of Cadiz, Lake Baikal (Eastern Siberia) allow to suggest close relation of the subaqueous GH formation process to anomalous hydrochemical profiles. We have studied the chemical and isotopic composition of interstitial fluids from GH-bearing and GH-free sediments obtained at different GH accumulations. Most attention was paid to possible influence of the interstitial fluid chemistry on the kinetic of GH formation in a porous media. The influence of salts on methane solubility within hydrate stability zones was considered by Handa (1990), Zatsepina & Buffet (1998), and later by Davie et al. (2004) from a theoretical point of view. Our idea is based on the experimentally proved fact that fugacity coefficient of methane dissolved in saline gas-saturated water which is in equilibrium with hydrates, is higher than that in more fresh water though the solubility is lower. Therefore, if a gradient of water salinity exist under conditions of hydrate stability, diffusion of methane induces hydrate formation by segregation on the outside a boundary fresher/saline water. Geochemical analysis of the interstitial fluids was used to define the mechanisms of GH accumulation and spatial distribution pattern of GHs in sediments from gas seeps abundant off NE Sakhaline Island (Sea of Okhotsk) (Matveeva et al., 2005; Mazurenko et al., submitted). A model of the ascending fluid discharge along one of the seeps named CHAOS was made based on the measured chlorinity (salinity function) of the pore waters and calculated chlorinity gradients. The chloride ion distributionprofiles with depth at the CHAOS site represent alike increasing and decreasing trends both in hydrate-bearing and hydrate-free cores. The model testifies an upward water infiltration of more saline water in vicinity of coring stations recovered GHs and relatively desalinated water mostly around those hydrate-free. It was established that GH formation at the CHAOS site is focused at the locations of intensive ascending flow of water enriched by salts that is probably function of gas solubility in water in the equilibrium with hydrate supposing that the feature is responsible for the hydrate formation just at the locations of the saline water up flows (other conditions being equal). Another case study supporting direct relation of GH formation with anomalous fluids and possible GH formation just on the interface of water flows with different salinity (defining chemical potentials of the water) is fresh-water GH accumulation at the Malenkiy fluid vent in the southern basin of Lake Baikal (Matveeva et al., 2003). The GH accumulation characterizes by heterogeneity in the spatial distribution of GH within a very small vent area. The spatial distribution of the GH-bearing and gas-saturated sediments suggests that several small fluid vents exist within the Malenkiy structure. Based on coring results, the size of these vents should not exceed a few meters. Interstitial water chemistry data indicates that water discharged within the Malenkiy vent is enriched with salts, especially Ca, Cl, and SO4 ions. The ascending water delivering gas into the GH stability zone is thought to be the main GH-forming fluid. Geochemical data suggest that the GH in the subsurface sediments of Lake Baikal originated from a deep source of water with anomalous composition assumed to be derived from buried paleolakes. As a whole, the GH accumulation corresponds to the area of the Malenkiy structure and is represented by several small scale GH occurrences coincident with local fluid discharge manifestations. The data obtained may serve as useful tool for development of geological and hydrogeochemical models of separate GH accumulations forming in the fluid discharge areas. The models on may also serve as a base for the gas inventory of the GH accumulations.

NDELA and nickel modulation of triazine disposition in skin.

PubMed

Baynes, Ronald E; Brooks, James D; Barlow, Beth M; Riviere, Jim E

2005-10-01

Cutting fluids can become contaminated with metals (e.g., nickel, Ni) and nitrosamines (e.g., N-nitrosodiethanolamine, NDELA) and there is concern that these classes of contaminants can modulate dermal disposition and ultimately the toxicity of cutting fluid additives, such as irritant biocides (e.g., triazine). Biocides are added to these formulations to prevent bacterial degradation of commercial cutting fluids. The purpose of this study was to assess the dermal absorption and skin deposition of 14C-triazine when topically applied to porcine skin in an in vitro flow-through diffusion cell system as aqueous soluble oil (mineral oil, MO) or aqueous synthetic (polyethylene glycol, PEG) mixtures. 14C-Triazine mixtures were formulated with NDELA and/or Ni, or with a combination of three additional cutting fluid additives; namely, 5% linear alkylbenzene sulfonate (LAS), 5% triethanolamine (TEA) and 5% sulfurized ricinoleic acid. Neither Ni nor NDELA was absorbed during these 8-h studies. However, 14C-triazine absorption ranged from 2.72 to 3.29% dose in MO and 2.29-2.88% dose in PEG with significantly greater triazine absorption in MO than PEG when all additives and contaminates were present. The difference between these two diluents was most pronounced when NDELA and/or Ni were present in cutting fluids. These contaminants also enhanced triazine deposition on the skin surface and skin tissues especially with PEG-based mixtures. In essence, the dermal disposition of irritant biocides could be dependent on whether the worker is exposed to a soluble oil or synthetic fluid when these contaminants are present. Workers should therefore not only be concerned about dermatotoxicity of these contaminants, but also the modulated dermal disposition of cutting fluid additives when these contaminants are present in cutting fluid formulations.

Rocky core solubility in Jupiter and giant exoplanets.

PubMed

Wilson, Hugh F; Militzer, Burkhard

2012-03-16

Gas giants are believed to form by the accretion of hydrogen-helium gas around an initial protocore of rock and ice. The question of whether the rocky parts of the core dissolve into the fluid H-He layers following formation has significant implications for planetary structure and evolution. Here we use ab initio calculations to study rock solubility in fluid hydrogen, choosing MgO as a representative example of planetary rocky materials, and find MgO to be highly soluble in H for temperatures in excess of approximately 10,000 K, implying the potential for significant redistribution of rocky core material in Jupiter and larger exoplanets.

Pressure Swing Absorption Device and Process for Separating CO{sub 2} from Shifted Syngas and its Capture for Subsequent Storage

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

Sirkar, Kamalesh; Jie, Xingming; Chau, John

Using the ionic liquid (IL) 1-butyl-3-methylimidazolium dicyanamide ([bmim][DCA]) as the absorbent on the shell side of a membrane module containing either a porous hydrophobized ceramic tubule or porous hydrophobized polyether ether ketone (PEEK) hollow fiber membranes, studies for CO{sub 2} removal from hot simulated pre-combustion shifted syngas were carried out by a novel pressure swing membrane absorption (PSMAB) process. Helium was used as a surrogate for H{sub 2} in a simulated shifted syngas with CO{sub 2} around 40% (dry gas basis). In this cyclic separation process, the membrane module was used to achieve non-dispersive gas absorption from a high-pressure feedmore » gas (689-1724 kPag; 100-250 psig) at temperatures between 25-1000C into a stationary absorbent liquid on the module shell side during a certain part of the cycle followed by among other cycle steps controlled desorption of the absorbed gases from the liquid in the rest of the cycle. Two product streams were obtained, one He-rich and the other CO{sub 2}-rich. Addition of polyamidoamine (PAMAM) dendrimer of generation 0 to IL [bmim][DCA] improved the system performance at higher temperatures. The solubilities of CO{sub 2} and He were determined in the ionic liquid with or without the dendrimer in solution as well as in the presence or absence of moisture; polyethylene glycol (PEG) 400 was also studied as a replacement for the IL. The solubility selectivity of the ionic liquid containing the dendrimer for CO{sub 2} over helium was considerably larger than that for the pure ionic liquid. The solubility of CO{sub 2} and CO{sub 2}-He solubility selectivity of PEG 400 and a solution of the dendrimer in PEG 400 were higher than the corresponding ones in the IL, [bmim][DCA]. A mathematical model was developed to describe the PSMAB process; a numerical solution of the governing equations described successfully the observed performance of the PSMAB process for the pure ionic liquid-based system.« less

Concentrations of anesthetics across the water-membrane interface; the Meyer-Overton hypothesis revisited

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.; New, M. H.; Chipot, C.

1998-01-01

The free energies of transferring a variety of anesthetic and nonanesthetic compounds across water-oil and water-membrane interfaces were obtained using computer simulations. Anesthetics exhibit greatly enhanced concentrations at these interfaces, compared to nonanesthetics. The substitution of the interfacial solubilites of the anesthetics for their bulk lipid solubilities in the Meyer-Overton relation, was found to give a better correlation, indicating that the potency of an anesthetic is directly proportional to its solubility at the interface.

Nebulization Reflux Concentrator

NASA Technical Reports Server (NTRS)

Cofer, Wesley R., III; Collins, V. G.

1986-01-01

Nebulization reflux concentrator extracts and concentrates trace quantities of water-soluble gases for subsequent chemical analysis. Hydrophobic membrane and nebulizing nozzles form scrubber for removing trace quantities of soluble gases or other contaminants from atmosphere. Although hydrophobic membrane virtually blocks all transport of droplets, it offers little resistance to gas flow; hence, device permits relatively large volumes of gas scrubbed efficiently with very small volumes of liquid. This means analyzable quantities of contaminants concentrate in extracting solutions in much shorter times than with conventional techniques.

Fluid-Structure interaction analysis and performance evaluation of a membrane blade

NASA Astrophysics Data System (ADS)

Saeedi, M.; Wüchner, R.; Bletzinger, K.-U.

2016-09-01

Examining the potential of a membrane blade concept is the goal of the current work. In the sailwing concept the surface of the wing, or the blade in this case, is made from pre-tensioned membranes which meet at the pre-tensioned edge cable at the trailing edge. Because of the dependency between membrane deformation and applied aerodynamic load, two-way coupled fluid-structure interaction analysis is necessary for evaluation of the aerodynamic performance of such a configuration. The in-house finite element based structural solver, CARAT++, is coupled with OpenFOAM in order to tackle the multi-physics problem. The main aerodynamic characteristics of the membrane blade including lift coefficient, drag coefficient and lift to drag ratio are compared with its rigid counterpart. A single non-rotating NREL phase VI blade is studied here as a first step towards analyzing the concept for the rotating case. Compared with the rigid blade, the membrane blade has a higher slope of the lift curve. For higher angles of attack, lift and drag coefficients as well as the lift to drag ratio is higher for the membrane blade. A single non-rotating blade is studied here as a first step towards analyzing the concept for the rotating case.

Suspended microfluidics.

PubMed

Casavant, Benjamin P; Berthier, Erwin; Theberge, Ashleigh B; Berthier, Jean; Montanez-Sauri, Sara I; Bischel, Lauren L; Brakke, Kenneth; Hedman, Curtis J; Bushman, Wade; Keller, Nancy P; Beebe, David J

2013-06-18

Although the field of microfluidics has made significant progress in bringing new tools to address biological questions, the accessibility and adoption of microfluidics within the life sciences are still limited. Open microfluidic systems have the potential to lower the barriers to adoption, but the absence of robust design rules has hindered their use. Here, we present an open microfluidic platform, suspended microfluidics, that uses surface tension to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. We developed a simple and ubiquitous model predicting fluid flow in suspended microfluidic systems and show that it encompasses many known capillary phenomena. Suspended microfluidics was used to create arrays of collagen membranes, mico Dots (μDots), in a horizontal plane separating two fluidic chambers, demonstrating a transwell platform able to discern collective or individual cellular invasion. Further, we demonstrated that μDots can also be used as a simple multiplexed 3D cellular growth platform. Using the μDot array, we probed the combined effects of soluble factors and matrix components, finding that laminin mitigates the growth suppression properties of the matrix metalloproteinase inhibitor GM6001. Based on the same fluidic principles, we created a suspended microfluidic metabolite extraction platform using a multilayer biphasic system that leverages the accessibility of open microchannels to retrieve steroids and other metabolites readily from cell culture. Suspended microfluidics brings the high degree of fluidic control and unique functionality of closed microfluidics into the highly accessible and robust platform of open microfluidics.

Suspended microfluidics

PubMed Central

Casavant, Benjamin P.; Berthier, Erwin; Theberge, Ashleigh B.; Berthier, Jean; Montanez-Sauri, Sara I.; Bischel, Lauren L.; Brakke, Kenneth; Hedman, Curtis J.; Bushman, Wade; Keller, Nancy P.; Beebe, David J.

2013-01-01

Although the field of microfluidics has made significant progress in bringing new tools to address biological questions, the accessibility and adoption of microfluidics within the life sciences are still limited. Open microfluidic systems have the potential to lower the barriers to adoption, but the absence of robust design rules has hindered their use. Here, we present an open microfluidic platform, suspended microfluidics, that uses surface tension to fill and maintain a fluid in microscale structures devoid of a ceiling and floor. We developed a simple and ubiquitous model predicting fluid flow in suspended microfluidic systems and show that it encompasses many known capillary phenomena. Suspended microfluidics was used to create arrays of collagen membranes, mico Dots (μDots), in a horizontal plane separating two fluidic chambers, demonstrating a transwell platform able to discern collective or individual cellular invasion. Further, we demonstrated that μDots can also be used as a simple multiplexed 3D cellular growth platform. Using the μDot array, we probed the combined effects of soluble factors and matrix components, finding that laminin mitigates the growth suppression properties of the matrix metalloproteinase inhibitor GM6001. Based on the same fluidic principles, we created a suspended microfluidic metabolite extraction platform using a multilayer biphasic system that leverages the accessibility of open microchannels to retrieve steroids and other metabolites readily from cell culture. Suspended microfluidics brings the high degree of fluidic control and unique functionality of closed microfluidics into the highly accessible and robust platform of open microfluidics. PMID:23729815

Ectodomain shedding of TβRIII is required for TβRIII-mediated suppression of TGF-β signaling and breast cancer migration and invasion

PubMed Central

Elderbroom, Jennifer L.; Huang, Jennifer J.; Gatza, Catherine E.; Chen, Jian; How, Tam; Starr, Mark; Nixon, Andrew B.; Blobe, Gerard C.

2014-01-01

The type III transforming growth factor β (TGF-β) receptor (TβRIII), also known as betaglycan, is the most abundantly expressed TGF-β receptor. TβRIII suppresses breast cancer progression by inhibiting migration, invasion, metastasis, and angiogenesis. TβRIII binds TGF-β ligands, with membrane-bound TβRIII presenting ligand to enhance TGF-β signaling. However, TβRIII can also undergo ectodomain shedding, releasing soluble TβRIII, which binds and sequesters ligand to inhibit downstream signaling. To investigate the relative contributions of soluble and membrane-bound TβRIII on TGF-β signaling and breast cancer biology, we defined TβRIII mutants with impaired (ΔShed-TβRIII) or enhanced ectodomain shedding (SS-TβRIII). Inhibiting ectodomain shedding of TβRIII increased TGF-β responsiveness and abrogated TβRIII's ability to inhibit breast cancer cell migration and invasion. Conversely, expressing SS-TβRIII, which increased soluble TβRIII production, decreased TGF-β signaling and increased TβRIII-mediated inhibition of breast cancer cell migration and invasion. Of importance, SS-TβRIII–mediated increases in soluble TβRIII production also reduced breast cancer metastasis in vivo. Taken together, these studies suggest that the ratio of soluble TβRIII to membrane-bound TβRIII is an important determinant for regulation of TβRIII- and TGF-β–mediated signaling and biology. PMID:24966170

Identification of a novel splice variant isoform of TREM-1 in human neutrophil granules1

PubMed Central

Baruah, Sankar; Keck, Kathy; Vrenios, Michelle; Pope, Marshall; Pearl, Merideth; Doerschug, Kevin; Klesney-Tait, Julia

2015-01-01

Triggering receptor expressed on myeloid cells-1 (TREM-1) is critical for inflammatory signal amplification. Humans have two forms of TREM-1: a membrane receptor (mbTREM-1), associated with the adaptor DAP12, and a soluble receptor detected at times of infection. The membrane receptor isoform acts synergistically with the TLR pathway to promote cytokine secretion and neutrophil migration while the soluble receptor functions as a counter regulatory molecule. In multiple models of sepsis, exogenous administration of soluble forms of TREM-1 attenuates inflammation and markedly improves survival. Despite intense interest in soluble TREM-1 both as a clinical predictor of survival and as a therapeutic tool, the origin of native soluble TREM-1 remains controversial. Utilizing human neutrophils, we identified a 15 kDa TREM-1 isoform in primary (azurophilic) and secondary (specific) granules. Mass spectrometric analysis, ELISA, and immunoblot confirm that the 15 kD protein is a novel splice variant of TREM-1 (TREM-1sv). Neutrophil stimulation with P. aeruginosa, LPS, or PAM(3)Cys4 resulted in degranulation and release of TREM-1sv. The addition of exogenous TREM-1sv inhibited TREM-1 receptor mediated proinflammatory cytokine production. Thus these data reveal that TREM-1 isoforms simultaneously activate and inhibit inflammation via the canonical membrane TREM-1 molecule and this newly discovered granular isoform, TREM-1sv. PMID:26561551

Identification of a Novel Splice Variant Isoform of TREM-1 in Human Neutrophil Granules.

PubMed

Baruah, Sankar; Keck, Kathy; Vrenios, Michelle; Pope, Marshall R; Pearl, Merideth; Doerschug, Kevin; Klesney-Tait, Julia

2015-12-15

Triggering receptor expressed on myeloid cells-1 (TREM-1) is critical for inflammatory signal amplification. Humans have two forms of TREM-1: a membrane receptor, associated with the adaptor DAP12, and a soluble receptor detected at times of infection. The membrane receptor isoform acts synergistically with the TLR pathway to promote cytokine secretion and neutrophil migration, whereas the soluble receptor functions as a counterregulatory molecule. In multiple models of sepsis, exogenous administration of soluble forms of TREM-1 attenuates inflammation and markedly improves survival. Despite intense interest in soluble TREM-1, both as a clinical predictor of survival and as a therapeutic tool, the origin of native soluble TREM-1 remains controversial. Using human neutrophils, we identified a 15-kDa TREM-1 isoform in primary (azurophilic) and secondary (specific) granules. Mass spectrometric analysis, ELISA, and immunoblot confirm that the 15-kDa protein is a novel splice variant form of TREM-1 (TREM-1sv). Neutrophil stimulation with Pseudomonas aeruginosa, LPS, or PAM(3)Cys4 resulted in degranulation and release of TREM-1sv. The addition of exogenous TREM-1sv inhibited TREM-1 receptor-mediated proinflammatory cytokine production. Thus, these data reveal that TREM-1 isoforms simultaneously activate and inhibit inflammation via the canonical membrane TREM-1 molecule and this newly discovered granular isoform, TREM-1sv. Copyright © 2015 by The American Association of Immunologists, Inc.

Apparatus for Pumping a Fluid

NASA Technical Reports Server (NTRS)

van Boeyen, Roger W. (Inventor); Reeh, Jonathan A. (Inventor); Kesmez, Mehmet (Inventor); Heselmeyer, Eric A. (Inventor); Parkey, Jeffrey S. (Inventor)

2016-01-01

An electrochemically actuated pump and an electrochemical actuator for use with a pump. The pump includes one of various stroke volume multiplier configurations with the pressure of a pumping fluid assisting actuation of a driving fluid bellows. The electrochemical actuator has at least one electrode fluidically coupled to the driving fluid chamber of the first pump housing and at least one electrode fluidically coupled to the driving fluid chamber of the second pump housing. Accordingly, the electrochemical actuator selectively pressurizes hydrogen gas within a driving fluid chamber. The actuator may include a membrane electrode assembly including an ion exchange membrane with first and second catalyzed electrodes in contact with opposing sides of the membrane, and first and second hydrogen gas chambers in fluid communication with the first and second electrodes, respectively. A controller may reverse the polarity of a voltage source electrically coupled to the current collectors.

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.

Modification of HTPB-based polyurethane with temperature-sensitive poly(N-isopropyl acrylamide) for biomaterial usage.

PubMed

Yang, Jen Ming; Yang, Shu Jyuan; Lin, Hao Tzu; Chen, Jan Kan

2007-01-01

Hydroxyl-terminated polybutadiene (HTPB)-based polyurethane with dimethyol propionic acid (DPA) as chain extender was synthesized by solution polymerization. The HTPB-based polyurethane was modified by UV radiation with N-isopropyl acrylamide monomer to get poly(N-isopropyl acrylamide)-modified polyurethane (PUDPANIPAAm). The cohesive energy (E(coh)), molar volume (V), solubility parameter (delta), molecular weight (W(M)), volume per gram (V(g)), and the density (1/V(g)) of PUDPANIPAAm were calculated by group contribution methods. To evaluate the application of PUDPANIPAAm for wound dressing and transplantation of cell sheet, the measurement of water content, water vapor transmission rate, and gas permeation on the PUDPANIPAAm membrane was evaluated. The biocompatibility of these membranes, cell adhesion, and proliferation assay were conducted in the cell culture. The effect of thermosensitivity of poly(N-isopropyl acrylamide) on cell detachment was also evaluated in the primary study. The results showed that these PUDPANIPAAm membranes are thermosensitive. The modification of PU with poly(N-isopropyl acrylamide) reduced the water vapor transmission rate and permeability of gas through PUDPANIPAAm membrane. PUDPANIPAAm membranes could support cell adhesion and growth. Owing to the thermosensitive nature of poly(N-isopropyl acrylamide), the relative cell numbers detached from PUDPANIPAAm membranes were larger than those detached from the polystyrene dish. 2006 Wiley Periodicals, Inc.

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation.

PubMed

Casado-Coterillo, Clara; Del Mar López-Guerrero, María; Irabien, Angel

2014-06-19

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials.

Zinc speciation in proximity to phosphate application points in a lead/zinc smelter-contaminated soil.

PubMed

Baker, Lucas R; Pierzynski, Gary M; Hettiarachchi, Ganga M; Scheckel, Kirk G; Newville, Matthew

2012-01-01

The use of P to immobilize Pb in contaminated soils has been well documented. However, the influence of P on Zn speciation in soils has not been extensively examined, and these two metals often occur as co-contaminants. We hypothesized that additions of P to a Pb/Zn-contaminated soil would induce Zn phosphate mineral formation and fluid P sources would be more effective than granular P amendments. A combination of different synchrotron-based techniques, namely, spatially resolved micro-X-ray fluorescence (μ-XRF), micro-extended X-ray absorption fine structure spectroscopy (μ-EXAFS), and micro-X-ray diffraction (μ-XRD), were used to speciate Zn at two incubation times in the proximity of application points (0 to 4 mm) for fluid and granular P amendments in a Pb/Zn smelter-contaminated soil. Phosphate rock (PR), triple super phosphate (TSP), monoammonium phosphate (MAP), and fluid ammonium polyphosphate induced Zn phosphate formation. Ammonium polyphosphate was more effective at greater distances (up to 3.7 mm) from the point of P application. Phosphoric acid increased the presence of soluble Zn species because of increased acidity. Soluble Zn has implications with respect to Zn bioavailability, which may negatively impact vegetation and other sensitive organisms. Although additions of P immobilize Pb, this practice needs close monitoring due to potential increases in Zn solubility in a Pb/Zn smelter-contaminated soil. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Lysenin Toxin Membrane Insertion Is pH-Dependent but Independent of Neighboring Lysenins.

PubMed

Munguira, Ignacio L B; Takahashi, Hirohide; Casuso, Ignacio; Scheuring, Simon

2017-11-07

Pore-forming toxins form a family of proteins that act as virulence factors of pathogenic bacteria, but similar proteins are found in all kingdoms of life, including the vertebrate immune system. They are secreted as soluble monomers that oligomerize on target membranes in the so-called prepore state; after activation, they insert into the membrane and adopt the pore state. Lysenin is a pore-forming toxin from the earthworm Eisenida foetida, of which both the soluble and membrane-inserted structures are solved. However, the activation and membrane-insertion mechanisms have remained elusive. Here, we used high-speed atomic force microscopy to directly visualize the membrane-insertion mechanism. Changing the environmental pH from pH 7.5 to below pH 6.0 favored membrane insertion. We detected a short α-helix in the soluble structure that comprised three glutamic acids (Glu92, Glu94, and Glu97) that we hypothesized may represent a pH-sensor (as in similar toxins, e.g., Listeriolysin). Mutant lysenin still can form pores, but mutating these glutamic acids to glutamines rendered the toxin pH-insensitive. On the other hand, toxins in the pore state did not favor insertion of neighboring prepores; indeed, pore insertion breaks the hexagonal ordered domains of prepores and separates from neighboring molecules in the membrane. pH-dependent activation of toxins may represent a common feature of pore-forming toxins. High-speed atomic force microscopy with single-molecule resolution at high temporal resolution and the possibility of exchanging buffers during the experiments presents itself as a unique tool for the study of toxin-state conversion. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Flexible Charged Macromolecules on Mixed Fluid Lipid Membranes: Theory and Monte Carlo Simulations

PubMed Central

Tzlil, Shelly; Ben-Shaul, Avinoam

2005-01-01

Fluid membranes containing charged lipids enhance binding of oppositely charged proteins by mobilizing these lipids into the interaction zone, overcoming the concomitant entropic losses due to lipid segregation and lower conformational freedom upon macromolecule adsorption. We study this energetic-entropic interplay using Monte Carlo simulations and theory. Our model system consists of a flexible cationic polyelectrolyte, interacting, via Debye-Hückel and short-ranged repulsive potentials, with membranes containing neutral lipids, 1% tetravalent, and 10% (or 1%) monovalent anionic lipids. Adsorption onto a fluid membrane is invariably stronger than to an equally charged frozen or uniform membrane. Although monovalent lipids may suffice for binding rigid macromolecules, polyvalent counter-lipids (e.g., phosphatidylinositol 4,5 bisphosphate), whose entropy loss upon localization is negligible, are crucial for binding flexible macromolecules, which lose conformational entropy upon adsorption. Extending Rosenbluth's Monte Carlo scheme we directly simulate polymer adsorption on fluid membranes. Yet, we argue that similar information could be derived from a biased superposition of quenched membrane simulations. Using a simple cell model we account for surface concentration effects, and show that the average adsorption probabilities on annealed and quenched membranes coincide at vanishing surface concentrations. We discuss the relevance of our model to the electrostatic-switch mechanism of, e.g., the myristoylated alanine-rich C kinase substrate protein. PMID:16126828

Microfluidic Cell Culture Device

NASA Technical Reports Server (NTRS)

Takayama, Shuichi (Inventor); Cabrera, Lourdes Marcella (Inventor); Heo, Yun Seok (Inventor); Smith, Gary Daniel (Inventor)

2014-01-01

Microfluidic devices for cell culturing and methods for using the same are disclosed. One device includes a substrate and membrane. The substrate includes a reservoir in fluid communication with a passage. A bio-compatible fluid may be added to the reservoir and passage. The reservoir is configured to receive and retain at least a portion of a cell mass. The membrane acts as a barrier to evaporation of the bio-compatible fluid from the passage. A cover fluid may be added to cover the bio-compatible fluid to prevent evaporation of the bio-compatible fluid.

Origin of Toughness in Dispersion-Cast Nafion Membranes

DOE PAGES

Kim, Yu Seung; Welch, Cynthia F.; Hjelm, Rex Paul; ...

2015-03-23

In this study, the gelation behavior of Nafion dispersions was investigated using small-angle neutron scattering to better understand the mechanical toughness of dispersion-cast Nafion membranes. Three types of gelation were observed, depending on dispersing fluids: (i) homogeneous, thermally reversible gelation that was present in most aprotic polar dispersing fluids; (ii) inhomogeneous, thermally irreversible gelation as films, found in alcohols; and (iii) inhomogeneous, thermally irreversible gelation which precipitates in water/monohydric alcohol mixtures. The mechanical toughness of dispersion-cast Nafion membranes depends on the dispersing fluid, varying by more than 4 orders of magnitude. Excellent correlation between the critical gelation concentration and mechanicalmore » toughness was demonstrated with the Nafion membranes cast at 140 °C. Additional thermal effects among Nafion membranes cast at 190 °C were qualitatively related to the boiling point of dispersing fluids. Little correlation between mechanical toughness and percent crystalline area of Nafion was observed, suggesting that the origin of mechanical toughness of dispersion-cast Nafion membranes is due to chain entanglements rather than crystallinity. Finally, the correlation between critical gelation concentration and mechanical toughness is a new way of predicting mechanical behavior in dispersion-cast polymer systems in which both polymer-dispersing fluid and polymer–polymer interactions play a significant role in the formation of polymer chain entanglements.« less

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.

Metazoans evolved by taking domains from soluble proteins to expand intercellular communication network

PubMed Central

Nam, Hyun-Jun; Kim, Inhae; Bowie, James U.; Kim, Sanguk

2015-01-01

A central question in animal evolution is how multicellular animals evolved from unicellular ancestors. We hypothesize that membrane proteins must be key players in the development of multicellularity because they are well positioned to form the cell-cell contacts and to provide the intercellular communication required for the creation of complex organisms. Here we find that a major mechanism for the necessary increase in membrane protein complexity in the transition from non-metazoan to metazoan life was the new incorporation of domains from soluble proteins. The membrane proteins that have incorporated soluble domains in metazoans are enriched in many of the functions unique to multicellular organisms such as cell-cell adhesion, signaling, immune defense and developmental processes. They also show enhanced protein-protein interaction (PPI) network complexity and centrality, suggesting an important role in the cellular diversification found in complex organisms. Our results expose an evolutionary mechanism that contributed to the development of higher life forms. PMID:25923201

Stapled Golgi cisternae remain in place as cargo passes through the stack

PubMed Central

Lavieu, Gregory; Zheng, Hong; Rothman, James E

2013-01-01

We have designed a membrane ‘staple’, which consists of membrane-anchored repeats of the trans-aggregating FM domain that face the lumen of the secretory pathway. In the presence of the disaggregating drug these proteins transit the secretory pathway. When the drug is removed these proteins form electron-dense plaques which we term staples. Unexpectedly, when initially positioned within the cis-Golgi, staples remained at the cis face of the Golgi even after many hours. By contrast, soluble FM-aggregates transited the Golgi. Staples and soluble aggregates placed in cis-Golgi cisternae therefore have different fates. Whereas the membrane staples are located in the flattened, stacked central regions of the cisternae, the soluble aggregates are in the dilated rims. This suggests that while the cisternae are static on the time scale of protein traffic, the dilated rims are mobile and progress in the cis → trans direction via a mechanism that we term ‘Rim Progression’. DOI: http://dx.doi.org/10.7554/eLife.00558.001 PMID:23755362

Pharmacological hypothesis: Nitric oxide-induced inhibition of ADAM-17 activity as well as vesicle release can in turn prevent the production of soluble endothelin-converting enzyme.

PubMed

Kuruppu, Sanjaya; Rajapakse, Niwanthi W; Parkington, Helena C; Smith, Ian

2017-10-01

Endothelin-1 (ET-1) and nitric oxide (NO) are two highly potent vasoactive molecules with opposing effects on the vasculature. Endothelin-converting enzyme (ECE) and nitric oxide synthase (NOS) catalyse the production of ET-1 and NO, respectively. It is well established that these molecules play a crucial role in the initiation and progression of cardiovascular diseases and have therefore become targets of therapy. Many studies have examined the mechanism(s) by which NO regulates ET-1 production. Expression and localization of ECE-1 is a key factor that determines the rate of ET-1 production. ECE-1 can either be membrane bound or be released from the cell surface to produce a soluble form. NO has been shown to reduce the expression of both membrane-bound and soluble ECE-1. Several studies have examined the mechanism(s) behind NO-mediated inhibition of ECE expression on the cell membrane. However, the precise mechanism(s) behind NO-mediated inhibition of soluble ECE production are unknown. We hypothesize that both exogenous and endogenous NO, inhibits the production of soluble ECE-1 by preventing its release via extracellular vesicles (e.g., exosomes), and/or by inhibiting the activity of A Disintegrin and Metalloprotease-17 (ADAM17). If this hypothesis is proven correct in future studies, these pathways represent targets for the therapeutic manipulation of soluble ECE-1 production. © 2017 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.

Low-cost method for fabricating palladium and palladium-alloy thin films on porous supports

DOEpatents

Lee, Tae H; Park, Chan Young; Lu, Yunxiang; Dorris, Stephen E; Balachandran, Uthamalingham

2013-11-19

A process for forming a palladium or palladium alloy membrane on a ceramic surface by forming a pre-colloid mixture comprising a powder palladium source, carrier fluid, dispersant and a pore former and a binder. Ultrasonically agitating the precolloid mixture and applying to a substrate with an ultrasonic nozzle and heat curing the coating form a palladium-based membrane.

Unearthing the Antibacterial Mechanism of Medicinal Clay: A Geochemical Approach to Combating Antibiotic Resistance

DOE PAGES

Morrison, Keith D.; Misra, Rajeev; Williams, Lynda B.

2016-01-08

Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe 2+ and Al 3+ that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply. This geochemical process is more effective than metal solutions alone and provides an alternative antibacterial strategy to traditional antibiotics. Advanced bioimaging methods and genetic show thatmore » Al 3+ misfolds cell membrane proteins, while Fe 2+ evokes membrane oxidation and enters the cytoplasm inflicting hydroxyl radical attack on intracellular proteins and DNA. The lethal reaction precipitates Fe 3+-oxides as biomolecular damage proceeds. In conclusion, discovery of this bactericidal mechanism demonstrated by natural clays should guide designs of new mineral-based antibacterial agents.« less

Unearthing the Antibacterial Mechanism of Medicinal Clay: A Geochemical Approach to Combating Antibiotic Resistance

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

Morrison, Keith D.; Misra, Rajeev; Williams, Lynda B.

Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe 2+ and Al 3+ that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply. This geochemical process is more effective than metal solutions alone and provides an alternative antibacterial strategy to traditional antibiotics. Advanced bioimaging methods and genetic show thatmore » Al 3+ misfolds cell membrane proteins, while Fe 2+ evokes membrane oxidation and enters the cytoplasm inflicting hydroxyl radical attack on intracellular proteins and DNA. The lethal reaction precipitates Fe 3+-oxides as biomolecular damage proceeds. In conclusion, discovery of this bactericidal mechanism demonstrated by natural clays should guide designs of new mineral-based antibacterial agents.« less

Unearthing the Antibacterial Mechanism of Medicinal Clay: A Geochemical Approach to Combating Antibiotic Resistance

PubMed Central

Morrison, Keith D.; Misra, Rajeev; Williams, Lynda B.

2016-01-01

Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe2+ and Al3+ that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply. This geochemical process is more effective than metal solutions alone and provides an alternative antibacterial strategy to traditional antibiotics. Advanced bioimaging methods and genetic show that Al3+ misfolds cell membrane proteins, while Fe2+ evokes membrane oxidation and enters the cytoplasm inflicting hydroxyl radical attack on intracellular proteins and DNA. The lethal reaction precipitates Fe3+-oxides as biomolecular damage proceeds. Discovery of this bactericidal mechanism demonstrated by natural clays should guide designs of new mineral-based antibacterial agents. PMID:26743034

Release of carrot plasma membrane-associated phosphatidylinositol kinase by phospholipase A2 and activation by a 70 kDa protein.

PubMed

Gross, W; Yang, W; Boss, W F

1992-02-19

Plasma membranes were isolated from carrot (Daucus carota L.) cells grown in suspension culture and treated with phospholipase A2 from snake or bee venom for 10 min. As a result of this treatment, phosphatidylinositol kinase activity was recovered in the soluble fraction. There was no detectable diacylglycerol kinase or phosphatidylinositol monophosphate kinase activity released from the membranes after the phospholipase A2 treatment. Treating the plasma membranes with phospholipase C or D did not release PI kinase activity. The phospholipase A2-released PI kinase was activated over 2-fold by a heat stable, soluble 70 kDa protein. The partially purified 70 kDa activator increases the Vmax but does not affect the Km of the phospholipase A2-released PI kinase.

Demonstration of a sensory rhodopsin in eubacteria.

PubMed

Jung, Kwang-Hwan; Trivedi, Vishwa D; Spudich, John L

2003-03-01

We report the first sensory rhodopsin observed in the eubacterial domain, a green light-activated photoreceptor in Anabaena (Nostoc) sp. PCC7120, a freshwater cyanobacterium. The gene encoding the membrane opsin protein of 261 residues (26 kDa) and a smaller gene encoding a soluble protein of 125 residues (14 kDa) are under the same promoter in a single operon. The opsin expressed heterologously in Escherichia coli membranes bound all-trans retinal to form a pink pigment (lambda max 543 nm) with a photochemical reaction cycle of 110 ms half-life (pH 6.8, 18 degrees C). Co-expression with the 14 kDa protein increased the rate of the photocycle, indicating physical interaction with the membrane-embedded rhodopsin, which we confirmed in vitro by affinity enrichment chromatography and Biacore interaction. The pigment lacks the proton donor carboxylate residue in helix C conserved in known retinylidene proton pumps and did not exhibit detectable proton ejection activity. We detected retinal binding to the protein in Anabaena membranes by SDS-PAGE and autofluorography of 3H-labelled all-trans retinal of reduced membranes from the organism. We conclude that Anabaena rhodopsin functions as a photosensory receptor in its natural environment, and suggest that the soluble 14 kDa protein transduces a signal from the receptor. Therefore, unlike the archaeal sensory rhodopsins, which transmit signals by transmembrane helix-helix interactions with membrane-embedded transducers, the Anabaena sensory rhodopsin may signal through a soluble cytoplasmic protein, analogous to higher animal visual pigments.

Nano- and microparticles at fluid and biological interfaces.

PubMed

Dasgupta, S; Auth, T; Gompper, G

2017-09-20

Systems with interfaces are abundant in both technological applications and biology. While a fluid interface separates two fluids, membranes separate the inside of vesicles from the outside, the interior of biological cells from the environment, and compartmentalize cells into organelles. The physical properties of interfaces are characterized by interface tension, those of membranes are characterized by bending and stretching elasticity. Amphiphilic molecules like surfactants that are added to a system with two immiscible fluids decrease the interface tension and induce a bending rigidity. Lipid bilayer membranes of vesicles can be stretched or compressed by osmotic pressure; in biological cells, also the presence of a cytoskeleton can induce membrane tension. If the thickness of the interface or the membrane is small compared with its lateral extension, both can be described using two-dimensional mathematical surfaces embedded in three-dimensional space. We review recent work on the interaction of particles with interfaces and membranes. This can be micrometer-sized particles at interfaces that stabilise emulsions or form colloidosomes, as well as typically nanometer-sized particles at membranes, such as viruses, parasites, and engineered drug delivery systems. In both cases, we first discuss the interaction of single particles with interfaces and membranes, e.g. particles in external fields, non-spherical particles, and particles at curved interfaces, followed by interface-mediated interaction between two particles, many-particle interactions, interface and membrane curvature-induced phenomena, and applications.

Nano- and microparticles at fluid and biological interfaces

NASA Astrophysics Data System (ADS)

Dasgupta, S.; Auth, T.; Gompper, G.

2017-09-01

Systems with interfaces are abundant in both technological applications and biology. While a fluid interface separates two fluids, membranes separate the inside of vesicles from the outside, the interior of biological cells from the environment, and compartmentalize cells into organelles. The physical properties of interfaces are characterized by interface tension, those of membranes are characterized by bending and stretching elasticity. Amphiphilic molecules like surfactants that are added to a system with two immiscible fluids decrease the interface tension and induce a bending rigidity. Lipid bilayer membranes of vesicles can be stretched or compressed by osmotic pressure; in biological cells, also the presence of a cytoskeleton can induce membrane tension. If the thickness of the interface or the membrane is small compared with its lateral extension, both can be described using two-dimensional mathematical surfaces embedded in three-dimensional space. We review recent work on the interaction of particles with interfaces and membranes. This can be micrometer-sized particles at interfaces that stabilise emulsions or form colloidosomes, as well as typically nanometer-sized particles at membranes, such as viruses, parasites, and engineered drug delivery systems. In both cases, we first discuss the interaction of single particles with interfaces and membranes, e.g. particles in external fields, non-spherical particles, and particles at curved interfaces, followed by interface-mediated interaction between two particles, many-particle interactions, interface and membrane curvature-induced phenomena, and applications.

Aqueous alkali metal hydroxide insoluble cellulose ether membrane

NASA Technical Reports Server (NTRS)

Hoyt, H. E.; Pfluger, H. L. (Inventor)

1969-01-01

A membrane that is insoluble in an aqueous alkali metal hydroxide medium is described. The membrane is a resin which is a water-soluble C2-C4 hydroxyalkyl cellulose ether polymer and an insolubilizing agent for controlled water sorption, a dialytic and electrodialytic membrane. It is particularly useful as a separator between electrodes or plates in an alkaline storage battery.

Membrane-induced Allosteric Control of Phospholipase C-β Isozymes*

PubMed Central

Charpentier, Thomas H.; Waldo, Gary L.; Barrett, Matthew O.; Huang, Weigang; Zhang, Qisheng; Harden, T. Kendall; Sondek, John

2014-01-01

All peripheral membrane proteins must negotiate unique constraints intrinsic to the biological interface of lipid bilayers and the cytosol. Phospholipase C-β (PLC-β) isozymes hydrolyze the membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP2) to propagate diverse intracellular responses that underlie the physiological action of many hormones, neurotransmitters, and growth factors. PLC-β isozymes are autoinhibited, and several proteins, including Gαq, Gβγ, and Rac1, directly engage distinct regions of these phospholipases to release autoinhibition. To understand this process, we used a novel, soluble analog of PIP2 that increases in fluorescence upon cleavage to monitor phospholipase activity in real time in the absence of membranes or detergents. High concentrations of Gαq or Gβ1γ2 did not activate purified PLC-β3 under these conditions despite their robust capacity to activate PLC-β3 at membranes. In addition, mutants of PLC-β3 with crippled autoinhibition dramatically accelerated the hydrolysis of PIP2 in membranes without an equivalent acceleration in the hydrolysis of the soluble analog. Our results illustrate that membranes are integral for the activation of PLC-β isozymes by diverse modulators, and we propose a model describing membrane-mediated allosterism within PLC-β isozymes. PMID:25193662

Isomeric Detergent Comparison for Membrane Protein Stability: Importance of Inter-Alkyl-Chain Distance and Alkyl Chain Length.

PubMed

Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S; Du, Yang; Nielsen, Anne K; Byrne, Bernadette; Kobilka, Brian K; Loland, Claus J; Guan, Lan; Chae, Pil Seok

2016-12-14

Membrane proteins encapsulated by detergent micelles are widely used for structural study. Because of their amphipathic property, detergents have the ability to maintain protein solubility and stability in an aqueous medium. However, conventional detergents have serious limitations in their scope and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C 12 alkyl chain was most effective at maintaining solubility/stability of the membrane proteins. We propose that interplay between the hydrophile-lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane proteins. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

NMR studies of a channel protein without membranes: structure and dynamics of water-solubilized KcsA.

PubMed

Ma, Dejian; Tillman, Tommy S; Tang, Pei; Meirovitch, Eva; Eckenhoff, Roderic; Carnini, Anna; Xu, Yan

2008-10-28

Structural studies of polytopic membrane proteins are often hampered by the vagaries of these proteins in membrane mimetic environments and by the difficulties in handling them with conventional techniques. Designing and creating water-soluble analogues with preserved native structures offer an attractive alternative. We report here solution NMR studies of WSK3, a water-soluble analogue of the potassium channel KcsA. The WSK3 NMR structure (PDB ID code 2K1E) resembles the KcsA crystal structures, validating the approach. By more stringent comparison criteria, however, the introduction of several charged residues aimed at improving water solubility seems to have led to the possible formations of a few salt bridges and hydrogen bonds not present in the native structure, resulting in slight differences in the structure of WSK3 relative to KcsA. NMR dynamics measurements show that WSK3 is highly flexible in the absence of a lipid environment. Reduced spectral density mapping and model-free analyses reveal dynamic characteristics consistent with an isotropically tumbling tetramer experiencing slow (nanosecond) motions with unusually low local ordering. An altered hydrogen-bond network near the selectivity filter and the pore helix, and the intrinsically dynamic nature of the selectivity filter, support the notion that this region is crucial for slow inactivation. Our results have implications not only for the design of water-soluble analogues of membrane proteins but also for our understanding of the basic determinants of intrinsic protein structure and dynamics.

Development of an implantable synthetic membrane for the treatment of preterm premature rupture of fetal membranes.

PubMed

Roman, Sabiniano; Bullock, Anthony J; Anumba, Dilly O; MacNeil, Sheila

2016-02-01

Preterm premature rupture of fetal membranes is a very common condition leading to premature labour of a non viable fetus. Significant morbidities may occur when preterm premature rupture of fetal membranes management is attempted to prolong the pregnancy for fetal maturation. Reducing the rate of loss of amniotic fluid and providing a barrier to bacterial entry may allow the pregnancy to continue to term, avoiding complications. Our aim is to develop a synthetic biocompatible membrane to form a distensible barrier for cervical closure which acts to reduce fluid loss and provide a surface for epithelial ingrowth to help repair the damaged membranes. Therefore, a bilayer membrane was developed using an electrospinning technique of combining two FDA-approved polymers, poly-L-lactic acid (PLA) and polyurethane (Z3) polymer. This was compared to a plain electrospun Z3 membrane. The physical and mechanical properties were assessed using scanning electron microscope images and a BOSE tensiometer, respectively, and compared to native fetal membranes. The performance of the membranes in preventing fluid loss was assessed by measuring their ability to support a column of water. Finally the ability of the membranes to support cell ingrowth was assessed by culturing adipose-derived stem cells on the membranes for two weeks and assessing metabolic activity after 7 and 14 days. The physical properties of the bilayer were similar to that of the native fetal membranes and it was resistant to fluid penetration. This bilayer membrane presented mechanical properties close to those for fetal membranes and showed elastic distention, which may be crucial for progress of the pregnancy. The membrane was also able to retain surgical sutures. In addition, it also supported the attachment and growth of adipose-derived stem cells for two weeks. In conclusion, this membrane may prove a useful approach in the treatment of preterm premature rupture of fetal membranes and now merits further investigation. © The Author(s) 2015.

Substituted polyacetylene separation membrane

DOEpatents

Pinnau, Ingo; Morisato, Atsushi

1998-01-13

A separation membrane useful for gas separation, particularly separation of C.sub.2+ hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula: ##STR1## wherein R.sub.1 is chosen from the group consisting of C.sub.1 -C.sub.4 alkyl and phenyl, and wherein R.sub.2 is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) ›PMP!. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations.

Membrane of Functionalized Reduced Graphene Oxide Nanoplates with Angstrom-Level Channels

PubMed Central

Lee, Byeongho; Li, Kunzhou; Yoon, Hong Sik; Yoon, Jeyong; Mok, Yeongbong; Lee, Yan; Lee, Hong H.; Kim, Yong Hyup

2016-01-01

Membranes with atomic level pores or constrictions are valuable for separation and catalysis. We report a graphene-based membrane with an interlayer spacing of 3.7 angstrom (Å). When graphene oxide nanoplates are functionalized and then reduced, the laminated reduced graphene oxide (rGO) nanoplates or functionalized rGO membrane is little affected by an intercalated fluid, and the interlayer spacing of 3.7 Å increases only to 4.4 Å in wetted state, in contrast to the graphene oxide (GO) membrane whose interlayer spacing increases from 9 Å to 13 Å in wetted state. When applied to ion separation, this membrane reduced the permeation rate of small ions such as K+ and Na+ by three orders of magnitude compared to the GO membrane. PMID:27306853

Human Intestinal Fluid Layer Separation: The Effect On Colloidal Structures & Solubility Of Lipophilic Compounds.

PubMed

Danny, Riethorst; Amitava, Mitra; Filippos, Kesisoglou; Wei, Xu; Jan, Tack; Joachim, Brouwers; Patrick, Augustijns

2018-05-23

In addition to individual intestinal fluid components, colloidal structures are responsible for enhancing the solubility of lipophilic compounds. The present study investigated the link between as well as the variability in the ultrastructure of fed state human intestinal fluids (FeHIF) and their solubilizing capacity for lipophilic compounds. For this purpose, FeHIF samples from 10 healthy volunteers with known composition and ultrastructure were used to determine the solubility of four lipophilic compounds. In light of the focus on solubility and ultrastructure, the study carefully considered the methodology of solubility determination in relation to colloid composition and solubilizing capacity of FeHIF. To determine the solubilizing capacity of human and simulated intestinal fluids, the samples were saturated with the compound of interest, shaken for 24 h, and centrifuged. When using FeHIF, solubilities were determined in the micellar layer of FeHIF, i.e. after removing the upper (lipid) layer (standard procedure), as well as in 'full' FeHIF (without removal of the upper layer). Compound concentrations were determined using HPLC-UV/fluorescence. To link the solubilizing capacity with the ultrastructure, all human and simulated fluids were imaged using transmission electron microscopy (TEM) before and after centrifugation and top layer (lipid) removal. Comparing the ultrastructure and solubilizing capacity of individual FeHIF samples demonstrated a high intersubject variability in postprandial intestinal conditions. Imaging of FeHIF after removal of the upper layer clearly showed that only micellar structures remain in the lower layer. This observation suggests that larger colloids such as vesicles and lipid droplets are contained in the upper, lipid layer. The solubilizing capacity of most FeHIF samples substantially increased with inclusion of this lipid layer. The relative increase in solubilizing capacity upon inclusion of the lipid layer was most pronounced in samples that contained mainly vesicles alongside the micelles. Current fed state simulated intestinal fluids do not contain the larger colloids observed in the lipid layer of FeHIF and can only simulate the solubilizing capacity of the micellar layer of FeHIF. While the importance of drug molecules solubilized in the micellar layer of postprandial intestinal fluids for absorption has been extensively demonstrated previously, the in-vivo relevance of drug solubilization in the lipid layer is currently unclear. In the dynamic environment of the human gastrointestinal tract, drug initially entrapped in larger postprandial colloids may become available for absorption upon lipid digestion and uptake. The current study, demonstrating the substantial solubilization of lipophilic compounds in the larger colloids of postprandial intestinal fluids, warrants further research in this field. Copyright © 2018. Published by Elsevier B.V.

Dynamics of vesicles in electric fields

NASA Astrophysics Data System (ADS)

Vlahovska, Petia; Gracia, Ruben

2007-11-01

Electromechanical forces are widely used for cell manipulation. Knowledge of the physical mechanisms underlying the interaction of cells and external fields is essential for practical applications. Vesicles are model cells made of a lipid bilayer membrane. They are examples of ``soft'' particles, i.e., their shape when subjected to flow or electric field is not given a priori but it is governed by the balance of membrane, fluid and electrical stresses. This generic ``softness'' gives rise to a very complex vesicle dynamics in external fields. In an AC electric field, as the frequency is increased, vesicles filled with a fluid less conducting than the surrounding fluid undergo shape transition from prolate to oblate ellipsoids. The opposite effect is observed with drops. We present an electro- hydrodynamic theory based on the leaky dielectric model that quantitatively describes experimental observations. We compare drops and vesicles, and show how their distinct behavior stems from different interfacial properties.

Nitroxide free radicals protect macular carotenoids against chemical destruction (bleaching) during lipid peroxidation

PubMed Central

Zareba, M.; Widomska, J.; Burke, J. M.; Subczynski, W. K.

2016-01-01

Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including filtration of phototoxic blue light and quenching of singlet oxygen and triplet states of photosensitizers. These physical protective mechanisms require that MXs be in their intact structure. Here, we investigated the protection of the intact structure of zeaxanthin incorporated into model membranes subjected to oxidative modification by water- and/or membrane-soluble small nitroxide free radicals. Model membranes were formed from saturated, monounsaturated, and polyunsaturated phosphatidylcholines (PCs). Oxidative modification involved autoxidation, iron-mediated, and singlet oxygen-mediated lipid peroxidation. The extent of chemical destruction (bleaching) of zeaxanthin was evaluated from its absorption spectra and compared with the extent of lipid peroxidation evaluated using the thiobarbituric acid assay. Nitroxide free radicals with different polarity (membrane/water partition coefficients) were used. The extent of zeaxanthin bleaching increased with membrane unsaturation and correlated with the rate of PC oxidation. Protection of the intact structure of zeaxanthin by membrane-soluble nitroxides was much stronger than that by water-soluble nitroxides. The combination of zeaxanthin and lipid-soluble nitroxides exerted strong synergistic protection against singlet oxygen-induced lipid peroxidation. The synergistic effect may be explained in terms of protection of the intact zeaxanthin structure by effective scavenging of free radicals by nitroxides, therefore allowing zeaxanthin to quench the primary oxidant, singlet oxygen, effectively by the physical protective mechanism. The redox state of nitroxides was monitored using electron paramagnetic resonance spectroscopy. Both nitroxide free radicals and their reduced form, hydroxylamines, were equally effective. Obtained data were compared with the protective effects of α-tocopherol, which is the natural antioxidant and protector of MXs within the retina. The new strategies employed here to maintain the intact structure of MXs may enhance their protective potential against AMD. PMID:27840316

Nitroxide free radicals protect macular carotenoids against chemical destruction (bleaching) during lipid peroxidation.

PubMed

Zareba, M; Widomska, J; Burke, J M; Subczynski, W K

2016-12-01

Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including filtration of phototoxic blue light and quenching of singlet oxygen and triplet states of photosensitizers. These physical protective mechanisms require that MXs be in their intact structure. Here, we investigated the protection of the intact structure of zeaxanthin incorporated into model membranes subjected to oxidative modification by water- and/or membrane-soluble small nitroxide free radicals. Model membranes were formed from saturated, monounsaturated, and polyunsaturated phosphatidylcholines (PCs). Oxidative modification involved autoxidation, iron-mediated, and singlet oxygen-mediated lipid peroxidation. The extent of chemical destruction (bleaching) of zeaxanthin was evaluated from its absorption spectra and compared with the extent of lipid peroxidation evaluated using the thiobarbituric acid assay. Nitroxide free radicals with different polarity (membrane/water partition coefficients) were used. The extent of zeaxanthin bleaching increased with membrane unsaturation and correlated with the rate of PC oxidation. Protection of the intact structure of zeaxanthin by membrane-soluble nitroxides was much stronger than that by water-soluble nitroxides. The combination of zeaxanthin and lipid-soluble nitroxides exerted strong synergistic protection against singlet oxygen-induced lipid peroxidation. The synergistic effect may be explained in terms of protection of the intact zeaxanthin structure by effective scavenging of free radicals by nitroxides, therefore allowing zeaxanthin to quench the primary oxidant, singlet oxygen, effectively by the physical protective mechanism. The redox state of nitroxides was monitored using electron paramagnetic resonance spectroscopy. Both nitroxide free radicals and their reduced form, hydroxylamines, were equally effective. Obtained data were compared with the protective effects of α-tocopherol, which is the natural antioxidant and protector of MXs within the retina. The new strategies employed here to maintain the intact structure of MXs may enhance their protective potential against AMD. Copyright © 2016 Elsevier Inc. All rights reserved.

Method and apparatus for determining the hydraulic conductivity of earthen material

DOEpatents

Sisson, James B.; Honeycutt, Thomas K.; Hubbell, Joel M.

1996-01-01

An earthen material hydraulic conductivity determining apparatus includes, a) a semipermeable membrane having a fore earthen material bearing surface and an opposing rear liquid receiving surface; b) a pump in fluid communication with the semipermeable membrane rear surface, the pump being capable of delivering liquid to the membrane rear surface at a plurality of selected variable flow rates or at a plurality of selected variable pressures; c) a liquid reservoir in fluid communication with the pump, the liquid reservoir retaining a liquid for pumping to the membrane rear surface; and d) a pressure sensor in fluid communication with the membrane rear surface to measure pressure of liquid delivered to the membrane by the pump. Preferably, the pump comprises a pair of longitudinally opposed and aligned syringes which are operable to simultaneously fill one syringe while emptying the other. Methods of determining the hydraulic conductivity of earthen material are also disclosed.

Method and apparatus for determining the hydraulic conductivity of earthen material

DOEpatents

Sisson, J.B.; Honeycutt, T.K.; Hubbell, J.M.

1996-05-28

An earthen material hydraulic conductivity determining apparatus includes: (a) a semipermeable membrane having a fore earthen material bearing surface and an opposing rear liquid receiving surface; (b) a pump in fluid communication with the semipermeable membrane rear surface, the pump being capable of delivering liquid to the membrane rear surface at a plurality of selected variable flow rates or at a plurality of selected variable pressures; (c) a liquid reservoir in fluid communication with the pump, the liquid reservoir retaining a liquid for pumping to the membrane rear surface; and (d) a pressure sensor in fluid communication with the membrane rear surface to measure pressure of liquid delivered to the membrane by the pump. Preferably, the pump comprises a pair of longitudinally opposed and aligned syringes which are operable to simultaneously fill one syringe while emptying the other. Methods of determining the hydraulic conductivity of earthen material are also disclosed. 15 figs.

Effect of ammonia-generating diet on ovine serum and follicular fluid ammonia and urea levels, serum oestrogen and progesterone concentrations and granulosa cell functions.

PubMed

Nandi, S; Mondal, S; Pal, D T; Gupta, P S P

2016-04-01

This study was undertaken to elucidate the effect of ammonia-generating diet on serum and follicular fluid ammonia and urea levels, serum oestrogen and progesterone concentrations and granulosa cell growth and secretion parameters in ewes (Ovis aries). Ewes were fed with 14% CP diet (control) or ammonia-generating diet or ammonia-generating diet plus soluble sugar. The serum and follicular fluid ammonia and urea level, serum oestrogen and progesterone levels and granulosa cell (obtained from ovaries of slaughtered ewes) growth parameters and secretory activities were estimated. Ammonia-generating diet (high-protein diet) increased the serum ammonia and urea concentration. Supplementation of soluble sugar significantly reduced the ammonia concentration in serum with comparable levels as in control group; however, the urea level in the same group was higher than that observed in control group. Supplementation of soluble sugar significantly reduced the follicular fluid ammonia concentration; however, the level was significantly higher compared to control group. Supplementation of soluble sugar brought down the follicular fluid urea level comparable to that observed in control group. Oestrogen and progesterone levels remained unchanged in ewes fed with different types of diet. Oestrogen and progesterone secretion were significantly lowered from granulosa cells recovered from ewes fed with high ammonia-generating diet. Low metabolic activity and high incidence of apoptosis were observed in granulosa cells obtained from ovaries of ewes fed with ammonia-generating diet. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

Composite perfluorohydrocarbon membranes, their preparation and use

DOEpatents

Ding, Yong; Bikson, Benjamin

2017-04-04

Composite porous hydrophobic membranes are prepared by forming a perfluorohydrocarbon layer on the surface of a preformed porous polymeric substrate. The substrate can be formed from poly (aryl ether ketone) and a perfluorohydrocarbon layer can be chemically grafted to the surface of the substrate. The membranes can be utilized for a broad range of fluid separations, such as microfiltration, nanofiltration, ultrafiltration as membrane contactors for membrane distillation and for degassing and dewatering of fluids. The membranes can further contain a dense ultra-thin perfluorohydrocarbon layer superimposed on the porous poly (aryl ether ketone) substrate and can be utilized as membrane contactors or as gas separation. membranes for natural gas treatment and gas dehydration.

Supercritical Fluid Fractionation of JP-8

DTIC Science & Technology

1991-12-26

applications, such as coffee decaffeination , spice extraction, and lipids purification. The processing principles have also long been well known and ipracticed...PRINCIPLES OF SUPERCRITICAL FLUID EXTRACTION 8 A. Background on Supercritical Fluid Solubility 8 B. Supercritical Fluid Extraction Process ...Operation I0 1. Batch Extraction of Solid Materials 10 2. Counter-Current Continuous SCF Processing of Liquid 15 Products 3. Supercritical Fluid Extraction vs

Entropic elasticity based coarse-grained model of lipid membranes

NASA Astrophysics Data System (ADS)

Feng, Shuo; Hu, Yucai; Liang, Haiyi

2018-04-01

Various models for lipid bilayer membranes have been presented to investigate their morphologies. Among them, the aggressive coarse-grained models, where the membrane is represented by a single layer of particles, are computationally efficient and of practical importance for simulating membrane dynamics at the microscopic scale. In these models, soft potentials between particle pairs are used to maintain the fluidity of membranes, but the underlying mechanism of the softening requires further clarification. We have analyzed the membrane area decrease due to thermal fluctuations, and the results demonstrate that the intraparticle part of entropic elasticity is responsible for the softening of the potential. Based on the stretching response of the membrane, a bottom-up model is developed with an entropic effect explicitly involved. The model reproduces several essential properties of the lipid membrane, including the fluid state and a plateau in the stretching curve. In addition, the area compressibility modulus, bending rigidity, and spontaneous curvature display linear dependence on model parameters. As a demonstration, we have investigated the closure and morphology evolution of membrane systems driven by spontaneous curvature, and vesicle shapes observed experimentally are faithfully reproduced.

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.

Hybrid polymer composite membrane for an electromagnetic (EM) valveless micropump

NASA Astrophysics Data System (ADS)

Said, Muzalifah Mohd; Yunas, Jumril; Bais, Badariah; Azlan Hamzah, Azrul; Yeop Majlis, Burhanuddin

2017-07-01

In this paper, we report on a hybrid membrane used as an actuator in an electromagnetically driven valveless micropump developed using MEMS processes. The membrane structure consists of the combination of a magnetic polymer composite membrane and an attached bulk permanent magnet which is expected to have a compact structure and a strong magnetic force with maintained membrane flexibility. A soft polymeric material made of polydimethylsiloxane (PDMS) is initially mixed with neodymium magnetic particles (NdFeB) to form a magnetic polymer composite membrane. The membrane is then bonded with the PDMS based microfluidic part, developed using soft lithography process. The developed micropump was tested in terms of the actuator membrane deflection capability and the fluidic flow of the injected fluid sample through the microfluidic channel. The experimental results show that the magnetic composite actuator membrane with an attached bulk permanent magnet is capable of producing a maximum membrane deflection of up to 106 µm. The functionality test of the electromagnetic (EM) actuator for fluid pumping purposes was done by supplying an AC voltage with various amplitudes, signal waves and frequencies. A wide range of sample injection rates from a few µl min-1 to tens of nl min-1 was achieved with a maximum flow rate of 6.6 µl min-1. The injection flow rate of the EM micropump can be controlled by adjusting the voltage amplitude and frequency supplied to the EM coil, to control the membrane deflection in the pump chamber. The designed valveless EM micropump has a very high potential to enhance the drug delivery system capability in biomedical applications.

Manufacturing methods and applications of membranes in microfluidics.

PubMed

Chen, Xueye; Shen, Jienan; Hu, Zengliang; Huo, Xuyao

2016-12-01

Applications of membranes in microfluidics solved many thorny problems for analytical chemistry and bioscience, so that the use of membranes in microfluidics has been a topic of growing interest. Many different examples have been reported, demonstrating the versatile use of membranes. This work reviews a lot of applications of membranes in microfluidics. Membranes in microfluidics for applications including chemical reagents detection, gas detection, drug screening, cell, protein, microreactor, electrokinetical fluid, pump and valve and fluid transport control and so on, have been analyzed and discussed. In addition, the definition and basic concepts of membranes are summed up. And the methods of manufacturing membranes in microfluidics are discussed. This paper will provide a helpful reference to researchers who want to study applications of membranes in microfluidics.

Cochlear fluid space dimensions for six species derived from reconstructions of three-dimensional magnetic resonance images.

PubMed

Thorne, M; Salt, A N; DeMott, J E; Henson, M M; Henson, O W; Gewalt, S L

1999-10-01

To establish the dimensions and volumes of the cochlear fluid spaces. Fluid space volumes, lengths, and cross-sectional areas were derived for the cochleas from six species: human, guinea pig, bat, rat, mouse, and gerbil. Three-dimensional reconstructions of the fluid spaces were made from magnetic resonance microscopy (MRM) images. Consecutive serial slices composed of isotropic voxels (25 microm3) representing the entire volume of fixed, isolated cochleas were obtained. The boundaries delineating the fluid spaces, including Reissner's membrane, were resolved for all specimens, except for the human, in which Reissner's membrane was not consistently resolved. Three-dimensional reconstructions of the endolymphatic and perilymphatic fluid spaces were generated. Fluid space length and variation of cross-sectional area with distance were derived by an algorithm that followed the midpoint of the space along the length of the spiral. The total volume of each fluid space was derived from a voxel count for each specimen. Length, volume, and cross-sectional areas are provided for six species. In all cases, the length of the endolymphatic fluid space was consistently longer than that of either perilymphatic scala, primarily as a result of a greater radius of curvature. For guinea pig specimens, the measured volumes of the fluid spaces were considerably lower than those suggested by previous reports based on histological data. The quantification of cochlear fluid spaces provided by this study will enable the more accurate calculation of drug and other solute movements in fluids of the inner ear during experimental or clinical manipulations.

Redox storage systems for solar applications

NASA Technical Reports Server (NTRS)

Hagedorn, N. H.; Thaller, L. H.

1980-01-01

The NASA Redox energy storage system is described. The system is based on soluble aqueous iron and chromium chloride redox couples. The needed technology advances in the two elements (electrodes and membranes) that are key to its technological feasibility have been achieved and system development has begun. The design, construction, and test of a 1 kilowatt system integrated with a solar photovoltaic array is discussed.

Process of forming compounds using reverse micelle or reverse microemulsion systems

DOEpatents

Linehan, John C.; Fulton, John L.; Bean, Roger M.

1998-01-01

The present invention is directed to a process for producing a nanometer-sized metal compound. The process comprises forming a reverse micelle or reverse microemulsion system comprising a polar fluid in a non-polar or low-polarity fluid. A first reactant comprising a multi-component, water-soluble metal compound is introduced into the polar fluid in a non-polar or low-polarity fluid. This first reactant can be introduced into the reverse micelle or reverse microemulsion system during formation thereof or subsequent to the formation of the reverse micelle or microemulsion system. The water-soluble metal compound is then reacted in the reverse micelle or reverse microemulsion system to form the nanometer-sized metal compound. The nanometer-sized metal compound is then precipitated from the reverse micelle or reverse microemulsion system.

Carbon dioxide in magmas and implications for hydrothermal systems

USGS Publications Warehouse

Lowenstern, J. B.

2001-01-01

This review focuses on the solubility, origin, abundance, and degassing of carbon dioxide (CO2) in magma-hydrothermal systems, with applications for those workers interested in intrusion-related deposits of gold and other metals. The solubility of CO2 increases with pressure and magma alkalinity. Its solubility is low relative to that of H2O, so that fluids exsolved deep in the crust tend to have high CO2/H2O compared with fluids evolved closer to the surface. Similarly, CO2/H2O will typically decrease during progressive decompression- or crystallization-induced degassing. The temperature dependence of solubility is a function of the speciation of CO2, which dissolves in molecular form in rhyolites (retrograde temperature solubility), but exists as dissolved carbonate groups in basalts (prograde). Magnesite and dolomite are stable under a relatively wide range of mantle conditions, but melt just above the solidus, thereby contributing CO2 to mantle magmas. Graphite, diamond, and a free CO2-bearing fluid may be the primary carbon-bearing phases in other mantle source regions. Growing evidence suggests that most CO2 is contributed to arc magmas via recycling of subducted oceanic crust and its overlying sediment blanket. Additional carbon can be added to magmas during magma-wallrock interactions in the crust. Studies of fluid and melt inclusions from intrusive and extrusive igneous rocks yield ample evidence that many magmas are vapor saturated as deep as the mid crust (10-15 km) and that CO2 is an appreciable part of the exsolved vapor. Such is the case in both basaltic and some silicic magmas. Under most conditions, the presence of a CO2-bearing vapor does not hinder, and in fact may promote, the ascent and eruption of the host magma. Carbonic fluids are poorly miscible with aqueous fluids, particularly at high temperature and low pressure, so that the presence of CO2 can induce immiscibility both within the magmatic volatile phase and in hydrothermal systems. Because some metals, including gold, can be more volatile in vapor phases than coexisting liquids, the presence of CO2 may indirectly aid the process of metallogenesis by inducing phase separation.

Correlations between trans-membrane pressure (TMP) and sludge properties in submerged membrane electro-bioreactor (SMEBR) and conventional membrane bioreactor (MBR).

PubMed

Hasan, Shadi W; Elektorowicz, Maria; Oleszkiewicz, Jan A

2012-09-01

The influence of sludge properties in SMEBR and conventional MBR pilot systems on membrane fouling was investigated. Generated data were analyzed using statistical analysis Pearson's product momentum correlation coefficient (r(p)). Analysis showed that TMP had strong direct (r(p)=0.9182) and inverse (r(p)=-0.9205) correlations to mean particle size diameter in MBR and SMEBR, respectively. TMP in SMEBR had a strong direct correlation to the sludge mixed liquor suspended solids concentration (MLSS) (r(p)=0.7757) while a weak direct correlation (r(p)=0.1940) was observed in MBR. SMEBR showed a moderate inverse correlation (r(p)=-0.6118) between TMP and soluble carbohydrates (EPS(c)) and a very weak direct correlation (r(p)=0.3448) to soluble proteins (EPS(p)). Conversely, EPS(p) in MBR had more significant impact (r(p)=0.4856) on membrane fouling than EPS(c) (r(p)=0.3051). The results provide insight into optimization of operational conditions in SMEBR system to overcome membrane fouling. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cocrystal solubilization in biorelevant media and its prediction from drug solubilization

PubMed Central

Lipert, Maya P.; Roy, Lilly; Childs, Scott L.

2015-01-01

This work examines cocrystal solubility in biorelevant media, (FeSSIF, fed state simulated intestinal fluid), and develops a theoretical framework that allows for the simple and quantitative prediction of cocrystal solubilization from drug solubilization. The solubilities of four hydrophobic drugs and seven cocrystals containing these drugs were measured in FeSSIF and in acetate buffer at pH 5.00. In all cases, the cocrystal solubility (Scocrystal) was higher than the drug solubility (Sdrug) in both buffer and FeSSIF; however, the solubilization ratio of drug, SRdrug = (SFeSSIF/Sbuffer)drug, was not the same as the solubilization ratio of cocrystal, SRcocrystal = (SFeSSIF/Sbuffer)cocrystal, meaning drug and cocrystal were not solubilized to the same extent in FeSSIF. This highlights the potential risk of anticipating cocrystal behavior in biorelevant media based on solubility studies in water. Predictions of SRcocrystal from simple equations based only on SRdrug were in excellent agreement with measured values. For 1:1 cocrystals, the cocrystal solubilization ratio can be obtained from the square root of the drug solubilization ratio. For 2:1 cocrystals, SRcocrystal is found from (SRdrug)2/3. The findings in FeSSIF can be generalized to describe cocrystal behavior in other systems involving preferential solubilization of a drug such as surfactants, lipids, and other drug solubilizing media. PMID:26390213

Water based drilling mud additive

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

McCrary, J.L.

1983-12-13

A water based fluid additive useful in drilling mud used during drilling of an oil or gas well is disclosed, produced by reacting water at temperatures between 210/sup 0/-280/sup 0/ F. with a mixture comprising in percent by weight: gilsonite 25-30%, tannin 7-15%, lignite 25-35%, sulfonating compound 15-25%, water soluble base compound 5-15%, methylene-yielding compound 1-5%, and then removing substantially all of the remaining water to produce a dried product.

Electrically actuatable doped polymer flakes and electrically addressable optical devices using suspensions of doped polymer flakes in a fluid host

DOEpatents

Trajkovska-Petkoska, Anka; Jacobs, Stephen D.; Marshall, Kenneth L.; Kosc, Tanya Z.

2010-05-11

Doped electrically actuatable (electrically addressable or switchable) polymer flakes have enhanced and controllable electric field induced motion by virtue of doping a polymer material that functions as the base flake matrix with either a distribution of insoluble dopant particles or a dopant material that is completely soluble in the base flake matrix. The base flake matrix may be a polymer liquid crystal material, and the dopants generally have higher dielectric permittivity and/or conductivity than the electrically actuatable polymer base flake matrix. The dopant distribution within the base flake matrix may be either homogeneous or non-homogeneous. In the latter case, the non-homogeneous distribution of dopant provides a dielectric permittivity and/or conductivity gradient within the body of the flakes. The dopant can also be a carbon-containing material (either soluble or insoluble in the base flake matrix) that absorbs light so as to reduce the unpolarized scattered light component reflected from the flakes, thereby enhancing the effective intensity of circularly polarized light reflected from the flakes when the flakes are oriented into a light reflecting state. Electro-optic devices contain these doped flakes suspended in a host fluid can be addressed with an applied electric field, thus controlling the orientation of the flakes between a bright reflecting state and a non-reflecting dark state.

Regional differences in the morphological and functional effects of aging on cerebral basement membranes and perivascular drainage of amyloid-β from the mouse brain.

PubMed

Hawkes, Cheryl A; Gatherer, Maureen; Sharp, Matthew M; Dorr, Adrienne; Yuen, Ho Ming; Kalaria, Rajesh; Weller, Roy O; Carare, Roxana O

2013-04-01

Development of cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) is associated with failure of elimination of amyloid-β (Aβ) from the brain along perivascular basement membranes that form the pathways for drainage of interstitial fluid and solutes from the brain. In transgenic APP mouse models of AD, the severity of cerebral amyloid angiopathy is greater in the cerebral cortex and hippocampus, intermediate in the thalamus, and least in the striatum. In this study we test the hypothesis that age-related regional variation in (1) vascular basement membranes and (2) perivascular drainage of Aβ contribute to the different regional patterns of CAA in the mouse brain. Quantitative electron microscopy of the brains of 2-, 7-, and 23-month-old mice revealed significant age-related thickening of capillary basement membranes in cerebral cortex, hippocampus, and thalamus, but not in the striatum. Results from Western blotting and immunocytochemistry experiments showed a significant reduction in collagen IV in the cortex and hippocampus with age and a reduction in laminin and nidogen 2 in the cortex and striatum. Injection of soluble Aβ into the hippocampus or thalamus showed an age-related reduction in perivascular drainage from the hippocampus but not from the thalamus. The results of the study suggest that changes in vascular basement membranes and perivascular drainage with age differ between brain regions, in the mouse, in a manner that may help to explain the differential deposition of Aβ in the brain in AD and may facilitate development of improved therapeutic strategies to remove Aβ from the brain in AD. © 2013 The Authors Aging Cell © 2013 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

High-performance liquid chromatography separation and intact mass analysis of detergent-solubilized integral membrane proteins

PubMed Central

Berridge, Georgina; Chalk, Rod; D’Avanzo, Nazzareno; Dong, Liang; Doyle, Declan; Kim, Jung-In; Xia, Xiaobing; Burgess-Brown, Nicola; deRiso, Antonio; Carpenter, Elisabeth Paula; Gileadi, Opher

2011-01-01

We have developed a method for intact mass analysis of detergent-solubilized and purified integral membrane proteins using liquid chromatography–mass spectrometry (LC–MS) with methanol as the organic mobile phase. Membrane proteins and detergents are separated chromatographically during the isocratic stage of the gradient profile from a 150-mm C3 reversed-phase column. The mass accuracy is comparable to standard methods employed for soluble proteins; the sensitivity is 10-fold lower, requiring 0.2–5 μg of protein. The method is also compatible with our standard LC–MS method used for intact mass analysis of soluble proteins and may therefore be applied on a multiuser instrument or in a high-throughput environment. PMID:21093405

Impact of a Low-Glucose Peritoneal Dialysis Regimen on Fibrosis and Inflammation Biomarkers

PubMed Central

Yung, Susan; Lui, Sing Leung; Ng, Chris K.F.; Yim, Andrew; Ma, Maggie K.M.; Lo, Kin Yee; Chow, Chik Cheung; Chu, Kwok Hong; Chak, Wai Leung; Lam, Man Fai; Yung, Chun Yu; Yip, Terence P.S.; Wong, Sunny; Tang, Colin S.O.; Ng, Flora S.K.; Chan, Tak Mao

2015-01-01

♦ Background: The impact of a low-glucose peritoneal dialysis (PD) regimen on biomarkers of peritoneal inflammation, fibrosis and membrane integrity remains to be investigated. ♦ Methods: In a randomized, prospective study, 80 incident PD patients received either a low-glucose regimen comprising Physioneal (P), Extraneal (E) and Nutrineal (N) (Baxter Healthcare Corporation, Deerfield, IL, USA) (PEN group), or Dianeal (control group) for 12 months, after which both groups continued with Dianeal dialysis for 6 months. Serum and dialysate levels of vascular endothelial growth factor (VEGF), decorin, hepatocyte growth factor (HGF), interleukin-6 (IL-6), macrophage migration inhibitory factor (MIF), hyaluronan (HA), adiponectin, soluble-intracellular adhesion molecule (s-ICAM), vascular cell adhesion molecule-1 (VCAM-1) and P-selectin, and dialysate cancer antigen 125 (CA125), were measured after 12 and 18 months. This paper focuses on results after 12 months, when patients in the PEN group changed to glucose-based PD fluid (PDF). ♦ Results: At the end of 12 months, effluent dialysate levels of CA125, decorin, HGF, IL-6, adiponectin and adhesion molecules were significantly higher in the PEN group compared to controls, but all decreased after patients switched to glucose-based PDF. Macrophage migration inhibitory factor level was lower in the PEN group but increased after changing to glucose-based PDF and was similar to controls at 18 months. Serum adiponectin level was higher in the PEN group at 12 months, but was similar in the 2 groups at 18 months. Body weight, residual renal function, ultrafiltration volume and total Kt/V did not differ between both groups. Dialysate-to-plasma creatinine ratio at 4 h was higher in the PEN group at 12 months and remained so after switching to glucose-based PDF. ♦ Conclusion: Changes in the biomarkers suggest that the PEN PD regimen may be associated with better preservation of peritoneal membrane integrity and reduced systemic vascular endothelial injury. PMID:25904773

Microdomains of endoplasmic reticulum within the sarcoplasmic reticulum of skeletal myofibers

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

Kaakinen, Mika; Papponen, Hinni; Metsikkoe, Kalervo

2008-01-15

The relationship between the endoplasmic reticulum (ER) and the sarcoplasmic reticulum (SR) of skeletal muscle cells has remained obscure. In this study, we found that ER- and SR-specific membrane proteins exhibited diverse solubility properties when extracted with mild detergents. Accordingly, the major SR-specific protein Ca{sup 2+}-ATPase (SERCA) remained insoluble in Brij 58 and floated in sucrose gradients while typical ER proteins were partially or fully soluble. Sphingomyelinase treatment rendered SERCA soluble in Brij 58. Immunofluorescence staining for resident ER proteins revealed dispersed dots over I bands contrasting the continuous staining pattern of SERCA. Infection of isolated myofibers with enveloped virusesmore » indicated that interfibrillar protein synthesis occurred. Furthermore, we found that GFP-tagged Dad1, able to incorporate into the oligosaccharyltransferase complex, showed the dot-like structures but the fusion protein was also present in membranes over the Z lines. This behaviour mimics that of cargo proteins that accumulated over the Z lines when blocked in the ER. Taken together, the results suggest that resident ER proteins comprised Brij 58-soluble microdomains within the insoluble SR membrane. After synthesis and folding in the ER-microdomains, cargo proteins and non-incorporated GFP-Dad1 diffused into the Z line-flanking compartment which likely represents the ER exit sites.« less

Protein mobilities and P-selectin storage in Weibel-Palade bodies.

PubMed

Kiskin, Nikolai I; Hellen, Nicola; Babich, Victor; Hewlett, Lindsay; Knipe, Laura; Hannah, Matthew J; Carter, Tom

2010-09-01

Using fluorescence recovery after photobleaching (FRAP) we measured the mobilities of EGFP-tagged soluble secretory proteins in the endoplasmic reticulum (ER) and in individual Weibel-Palade bodies (WPBs) at early (immature) and late (mature) stages in their biogenesis. Membrane proteins (P-selectin, CD63, Rab27a) were also studied in individual WPBs. In the ER, soluble secretory proteins were mobile; however, following insertion into immature WPBs larger molecules (VWF, Proregion, tPA) and P-selectin became immobilised, whereas small proteins (ssEGFP, eotaxin-3) became less mobile. WPB maturation led to further decreases in mobility of small proteins and CD63. Acute alkalinisation of mature WPBs selectively increased the mobilities of small soluble proteins without affecting larger molecules and the membrane proteins. Disruption of the Proregion-VWF paracrystalline core by prolonged incubation with NH(4)Cl rendered P-selectin mobile while VWF remained immobile. FRAP of P-selectin mutants revealed that immobilisation most probably involves steric entrapment of the P-selectin extracellular domain by the Proregion-VWF paracrystal. Significantly, immobilisation contributed to the enrichment of P-selectin in WPBs; a mutation of P-selectin preventing immobilisation led to a failure of enrichment. Together these data shed new light on the transitions that occur for soluble and membrane proteins following their entry and storage into post-Golgi-regulated secretory organelles.

Stiffening of fluid membranes due to thermal undulations: density-matrix renormalization-group study.

PubMed

Nishiyama, Yoshihiro

2002-12-01

It has been considered that the effective bending rigidity of fluid membranes should be reduced by thermal undulations. However, recent thorough investigation by Pinnow and Helfrich revealed the significance of measure factors for the partition sum. Accepting the local curvature as a statistical measure, they found that fluid membranes are stiffened macroscopically. In order to examine this remarkable idea, we performed extensive ab initio simulations for a fluid membrane. We set up a transfer matrix that is diagonalized by means of the density-matrix renormalization group. Our method has an advantage, in that it allows us to survey various statistical measures. As a consequence, we found that the effective bending rigidity flows toward strong coupling under the choice of local curvature as a statistical measure. On the contrary, for other measures such as normal displacement and tilt angle, we found a clear tendency toward softening.

Highly CO2-Selective Gas Separation Membranes Based on Segmented Copolymers of Poly(Ethylene oxide) Reinforced with Pentiptycene-Containing Polyimide Hard Segments.

PubMed

Luo, Shuangjiang; Stevens, Kevin A; Park, Jae Sung; Moon, Joshua D; Liu, Qiang; Freeman, Benny D; Guo, Ruilan

2016-01-27

Poly(ethylene oxide) (PEO)-containing polymer membranes are attractive for CO2-related gas separations due to their high selectivity toward CO2. However, the development of PEO-rich membranes is frequently challenged by weak mechanical properties and a high crystallization tendency of PEO that hinders gas transport. Here we report a new series of highly CO2-selective, amorphous PEO-containing segmented copolymers prepared from commercial Jeffamine polyetheramines and pentiptycene-based polyimide. The copolymers are much more mechanically robust than the nonpentiptycene containing counterparts due to the molecular reinforcement mechanism of supramolecular chain threading and interlocking interactions induced by the pentiptycene structures, which also effectively suppresses PEO crystallization leading to a completely amorphous structure even at 60% PEO weight content. Membrane transport properties are sensitively affected by both PEO weight content and PEO chain length. A nonlinear correlation between CO2 permeability with PEO weight content was observed due to the competition between solubility and diffusivity contributions, whereby the copolymers change from being size-selective to solubility-selective when PEO content reaches 40%. CO2 selectivities over H2 and N2 increase monotonically with both PEO content and chain length, indicating strong CO2-philicity of the copolymers. The copolymer film with the longest PEO sequence (PEO2000) and highest PEO weight content (60%) showed a measured CO2 pure gas permeability of 39 Barrer, and ideal CO2/H2 and CO2/N2 selectivities of 4.1 and 46, respectively, at 35 °C and 3 atm, making them attractive for hydrogen purification and carbon capture.

Identification of the membrane remnants of transferrin receptor with domain-specific antibodies.

PubMed

Baynes, R D; Shih, Y J; Hudson, B G; Cook, J D

1994-03-01

Tissue culture studies with K562 and HL60 cells have demonstrated the production of a soluble form of transferrin receptor identical to that identified in human serum. The present study was undertaken to search for membrane remnants of the truncated receptor with peptide antibodies specific for the extracellular and cytoplasmic domain of transferrin receptor. In cell membranes, a 105K remnant was identified that is consistent with truncation of one extracellular domain monomer of the transferrin receptor. In the exosomal fraction of the culture supernatant, a smaller 20K remnant consistent with truncation of both extracellular domains was also demonstrated. These findings provide evidence that soluble receptor is the product of proteolytic cleavage of intact membrane-bound transferrin receptor. Prior studies showing that the concentration of the extracellular domain in exosomes remained stable during incubation in culture supernatant suggest that this cleavage possibly occurs intracellularly.

Evidence for a plasma-membrane-bound nitrate reductase involved in nitrate uptake of Chlorella sorokiniana

NASA Technical Reports Server (NTRS)

Tischner, R.; Ward, M. R.; Huffaker, R. C.

1989-01-01

Anti-nitrate-reductase (NR) immunoglobulin-G (IgG) fragments inhibited nitrate uptake into Chlorella cells but had no affect on nitrate uptake. Intact anti-NR serum and preimmune IgG fragments had no affect on nitrate uptake. Membrane-associated NR was detected in plasma-membrane (PM) fractions isolated by aqueous two-phase partitioning. The PM-associated NR was not removed by sonicating PM vesicles in 500 mM NaCl and 1 mM ethylenediaminetetraacetic acid and represented up to 0.8% of the total Chlorella NR activity. The PM NR was solubilized by Triton X-100 and inactivated by Chlorella NR antiserum. Plasma-membrane NR was present in ammonium-grown Chlorella cells that completely lacked soluble NR activity. The subunit sizes of the PM and soluble NRs were 60 and 95 kDa, respectively, as determined by sodium-dodecyl-sulfate electrophoresis and western blotting.

Blood SC5b-9 complement levels increase at parturition during term and preterm labor.

PubMed

Segura-Cervantes, Enrique; Mancilla-Ramirez, Javier; Zurita, Luis; Paredes, Yuriria; Arredondo, José Luis; Galindo-Sevilla, Norma

2015-06-01

We explored the hypothesis that complement, an innate and adaptive immune effector, is active in the plasma of parturient women and is deposited on fetal membranes collected after delivery. A cross-sectional study was designed to evaluate complement activity at parturition. Pregnant women (n = 97) between 15 and 41 years of age were enrolled in a hospital protocol during the perinatal period to assess both SC5b-9 complement activity in blood and complement deposition on fetal membranes during parturition. Soluble SC5b-9 complement activity in plasma fractions was measured using a standard enzyme-linked immunosorbent assay (ELISA) that included specific anti-complement antibodies. Complement deposition on membranes was analyzed using immuno-dot blots and immunohistochemistry. Soluble SC5b-9 complement complex levels were increased in the plasma of women during term labor (TL; median 3361; range 1726-5670 ng/mL), preterm labor (PL; median 2958; range 1552-7092 ng/mL), and preterm premature rupture of membranes (PPROM; median 2272; range 167-6540 ng/mL) compared with pregnant women who were not in labor (P; median 1384; range 174-4570 ng/mL; P < 0.001, Kruskal-Wallis test). Active complement, as assessed by the C9 neo-antigen in C5b-9 complexes, was deposited on fetal membranes, with no difference between term and preterm delivery. The deposition of active complement on fetal membranes was confirmed by immunohistochemistry. Women who underwent non-labor-indicated Cesarean sections did not exhibit complement deposition. Soluble SC5b-9 complement complex levels increased in the plasma of women during parturition, and complement C5b-9 complexes were deposited on fetal membranes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Hydration induced material transfer in membranes of osmotic pump tablets measured by synchrotron radiation based FTIR.

PubMed

Wu, Li; Yin, Xianzhen; Guo, Zhen; Tong, Yajun; Feng, Jing; York, Peter; Xiao, Tiqiao; Chen, Min; Gu, Jingkai; Zhang, Jiwen

2016-03-10

Osmotic pump tablets are reliable oral controlled drug delivery systems based on their semipermeable membrane coating. This research used synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy and imaging to investigate the hydration induced material transfer in the membranes of osmotic pump tablets. SR-FTIR was applied to record and map the chemical information of a micro-region of the membranes, composed of cellulose acetate (CA, as the water insoluble matrix) and polyethylene glycol (PEG, as the soluble pore forming agent and plasticizing agent). The microstructure and chemical change of membranes hydrated for 0, 5, 10 and 30min were measured using SR-FTIR, combined with scanning electronic microscopy and atom force microscopy. The SR-FTIR microspectroscopy results indicated that there was a major change at the absorption range of 2700-3100cm(-1) in the membranes after different periods of hydration time. The absorption bands at 2870-2880cm(-1) and 2950-2960cm(-1) were assigned to represent CA and PEG, respectively. The chemical group signal distribution illustrated by the ratio of PEG to CA demonstrated that the trigger of drug release in the preliminary stage was due to the rapid transfer of PEG into liquid medium with a sharp decrease of PEG in the membranes. The SR-FTIR mapping results have demonstrated the hydration induced material transfer in the membranes of osmotic pump tablets and enabled reassessment of the drug release mechanism of membrane controlled osmotic pump systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Dissolution of biogenic ooze over basement edifices in the equatorial Pacific with implications for hydrothermal ventilation of the oceanic crust

USGS Publications Warehouse

Bekins, B.A.; Spivack, A.J.; Davis, E.E.; Mayer, L.A.

2007-01-01

Recent observations indicate that curious closed depressions in carbonate sediments overlying basement edifices are widespread in the equatorial Pacific. A possible mechanism for their creation is dissolution by fluids exiting basement vents from off-axis hydrothermal flow. Quantitative analysis based on the retrograde solubility of calcium carbonate and cooling of basement fluids during ascent provides an estimate for the dissolution capacity of the venting fluids. Comparison of the dissolution capacity and fluid flux with typical equatorial Pacific carbonate mass accumulation rates shows that this mechanism is feasible. By maintaining sediment-free basement outcrops, the process may promote widespread circulation of relatively unaltered seawater in the basement in an area where average sediment thicknesses are 300-500 m. The enhanced ventilation can explain several previously puzzling observations in this region, including anomalously low heat flux, relatively unaltered seawater in the basement, and aerobic and nitrate-reducing microbial activity at the base of the sediments. ?? 2007 The Geological Society of America.

Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

PubMed Central

Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

2016-01-01

New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas. PMID:27498607

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

Hong, Tao; Chatterjee, Sabornie; Mahurin, Shannon M.

Amidoxime-functionalized polydimethylsiloxane (AO-PDMSPNB) membranes with various amidoxime compositions were synthesized via ring-opening metathesis polymerization followed by post-polymerization modification. Compared to other previously reported PDMS-based membranes, the amidoxime-functionalized membranes show enhanced CO 2 permeability and CO 2/N 2 selectivity. The overall gas separation performance (CO 2 permeability 6800 Barrer; CO 2/N 2 selectivity 19) of the highest performing membrane exceeds the Robeson upper bound line, and the excellent permeability of the copolymer itself provides great potential for real world applications where huge volumes of gases are separated. This study details how tuning the CO 2-philicity within rubbery polymer matrices influences gasmore » transport properties. Key parameters for tuning gas transport properties are discussed, and the experimental results show good consistency with theoretical calculations. Finally, this study provides a roadmap to enhancing gas separation performance in rubbery polymers by tuning gas solubility selectivity.« less

Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

NASA Astrophysics Data System (ADS)

Chernova, Ekaterina; Petukhov, Dmitrii; Boytsova, Olga; Alentiev, Alexander; Budd, Peter; Yampolskii, Yuri; Eliseev, Andrei

2016-08-01

New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

Manninotriose is a major carbohydrate in red deadnettle (Lamium purpureum, Lamiaceae)

PubMed Central

dos Santos, Raquel; Vergauwen, Rudy; Pacolet, Pieter; Lescrinier, Eveline; Van den Ende, Wim

2013-01-01

Background and Aims There is a great need to search for natural compounds with superior prebiotic, antioxidant and immunostimulatory properties for use in (food) applications. Raffinose family oligosaccharides (RFOs) show such properties. Moreover, they contribute to stress tolerance in plants, acting as putative membrane stabilizers, antioxidants and signalling agents. Methods A large-scale soluble carbohydrate screening was performed within the plant kingdom. An unknown compound accumulated to a high extent in early-spring red deadnettle (Lamium purpureum) but not in other RFO plants. The compound was purified and its structure was unravelled with NMR. Organs and organ parts of red deadnettle were carefully dissected and analysed for soluble sugars. Phloem sap content was analysed by a common EDTA-based method. Key Results Early-spring red deadnettle stems and roots accumulate high concentrations of the reducing trisaccharide manninotriose (Galα1,6Galα1,6Glc), a derivative of the non-reducing RFO stachyose (Galα1,6Galα1,6Glcα1,2βFru). Detailed soluble carbohydrate analyses on dissected stem and leaf sections, together with phloem sap analyses, strongly suggest that stachyose is the main transport compound, but extensive hydrolysis of stachyose to manninotriose seems to occur along the transport path. Based on the specificities of the observed carbohydrate dynamics, the putative physiological roles of manninotriose in red deadnettle are discussed. Conclusions It is demonstrated for the first time that manninotriose is a novel and important player in the RFO metabolism of red dead deadnettle. It is proposed that manninotriose represents a temporary storage carbohydrate in early-spring deadnettle, at the same time perhaps functioning as a membrane protector and/or as an antioxidant in the vicinity of membranes, as recently suggested for other RFOs and fructans. This novel finding urges further research on this peculiar carbohydrate on a broader array of RFO accumulators. PMID:23264235

Consideration of some dilute-solution phenomena based on an expression for the Gibbs free energy

NASA Astrophysics Data System (ADS)

Jonah, D. A.

1986-07-01

Rigorous expressions based on the Lennard-Jones (6 12) potential, are presented for the Gibbs and Helmholtz free energy of a dilute mixture. These expressions give the free energy of the mixture in terms of the thermodynamic properties of the pure solvent, thereby providing a convenient means of correlating dilute mixture behavior with that of the pure solvent. Expressions for the following dilute binary solution properties are derived: Henry's constant, limiting activity coefficients with their derivatives, solid solubilities in supercritical gases, and mixed second virial coefficients. The Henry's constant expression suggests a linear temperature dependence; application to solubility data for various gases in methane and water shows a good agreement between theory and experiment. In the thermodynamic modeling of supercritical fluid extraction, we have demonstrated how to predict new solubility-pressure isotherms from a given isotherm, with encouraging results. The mixed second virial coefficient expression has also been applied to experimental data; the agreement with theory is good.

Identification of AQP5 in lipid rafts and its translocation to apical membranes by activation of M3 mAChRs in interlobular ducts of rat parotid gland.

PubMed

Ishikawa, Yasuko; Yuan, Zhenfang; Inoue, Noriko; Skowronski, Mariusz T; Nakae, Yoshiko; Shono, Masayuki; Cho, Gota; Yasui, Masato; Agre, Peter; Nielsen, Søren

2005-11-01

Aquaporin-5 (AQP5), an apical plasma membrane (APM) water channel in salivary glands, lacrimal glands, and airway epithelium, has an important role in fluid secretion. M(3) muscarinic acetylcholine receptor (mAChR)-induced changes in AQP5 localization in rat parotid glands were investigated with immunofluorescence or immunoelectron microscopy, detergent solubility, and gradient density floatation assays. Confocal microscopy revealed AQP5 localization in intracellular vesicles of interlobular duct cells in rat parotid glands and AQP5 trafficking to the APM 10 min after injection of the mAChR agonist cevimeline. Conversely, 60 min after injection, there was a diffuse pattern of AQP5 staining in the cell cytoplasm. The calcium ionophore A-23187 mimicked the effects of cevimeline. Immunoelectron microscopic studies confirmed that cevimeline induced AQP5 trafficking from intracellular structures to APMs in the interlobular duct cells of rat parotid glands. Lipid raft markers flotillin-2 and GM1 colocalized with AQP5 and moved with AQP5 in response to cevimeline. Under control conditions, the majority of AQP5 localized in the Triton X-100-insoluble fraction and floated to the light-density fraction on discontinuous density gradients. After 10-min incubation of parotid tissue slices with cevimeline or A-23187, AQP5 levels decreased in the Triton X-100-insoluble fraction and increased in the Triton X-100-soluble fraction. Thus AQP5 localizes in the intracellular lipid rafts, and M(3) mAChR activation induces AQP5 trafficking to the APM with lipid rafts via intracellular Ca(2+) signaling and induces AQP5 dissociation from lipid rafts to nonrafts on the APM in the interlobular duct cells of rat parotid glands.

Peritoneal Fluid Transport rather than Peritoneal Solute Transport Associates with Dialysis Vintage and Age of Peritoneal Dialysis Patients.

PubMed

Waniewski, Jacek; Antosiewicz, Stefan; Baczynski, Daniel; Poleszczuk, Jan; Pietribiasi, Mauro; Lindholm, Bengt; Wankowicz, Zofia

2016-01-01

During peritoneal dialysis (PD), the peritoneal membrane undergoes ageing processes that affect its function. Here we analyzed associations of patient age and dialysis vintage with parameters of peritoneal transport of fluid and solutes, directly measured and estimated based on the pore model, for individual patients. Thirty-three patients (15 females; age 60 (21-87) years; median time on PD 19 (3-100) months) underwent sequential peritoneal equilibration test. Dialysis vintage and patient age did not correlate. Estimation of parameters of the two-pore model of peritoneal transport was performed. The estimated fluid transport parameters, including hydraulic permeability (LpS), fraction of ultrasmall pores (α u), osmotic conductance for glucose (OCG), and peritoneal absorption, were generally independent of solute transport parameters (diffusive mass transport parameters). Fluid transport parameters correlated whereas transport parameters for small solutes and proteins did not correlate with dialysis vintage and patient age. Although LpS and OCG were lower for older patients and those with long dialysis vintage, αu was higher. Thus, fluid transport parameters--rather than solute transport parameters--are linked to dialysis vintage and patient age and should therefore be included when monitoring processes linked to ageing of the peritoneal membrane.

Sulfur Speciation and Extraction in Jet A (Briefing Charts)

DTIC Science & Technology

2015-08-16

Extraction fluid: denatured ethanol from Fisher Scientific and deionized water – Jet A fuel , approximately 500-800 ppm sulfur by weight – Data...Outline • Background • Experimental Setup – Extraction of sulfur compounds from fuel to alcohol/water extraction fluid – Each rinse is...Hydrophobic / Oleophillic Membrane Oleophobic / Hydrophillic Membrane Emulsion Phase Fuel Phase Water (Extraction Fluid) Phase DISTRIBUTION A

The effect of acid hydrolysis pretreatment on crystallinity and solubility of kenaf cellulose membrane

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

Saidi, Anis Syuhada Mohd; Zakaria, Sarani; Chia, Chin Hua

2015-09-25

Cellulose was extracted from kenaf core pulp (KCP) by series of bleaching steps in the sequence (DEED) where D and E are referred as acid and alkali treatment. The bleached kenaf pulp (BKCP) is then pretreated with acid hydrolysis at room temperature for 1 and 3 h respectively. The pretreated cellulose is dissolved in lithium hydroxide/urea (LiOH/urea) and cellulose solution produced was immersed in distilled water bath. BKCP without treatment was also conducted for comparison purpose. The effects of acid hydrolysis pretreatment on solubility and crystallinity are investigated. Higher solubility of cellulose solution is achieved for treated samples. Cellulose II formationmore » and crystallinity index of the cellulose membrane were determined by X-ray diffraction (XRD)« less

Computational fluid dynamics simulation of pressure and velocity distribution inside Meniere’s diseased vestibular system

NASA Astrophysics Data System (ADS)

Shamsuddin, N. F. H.; Isa, N. M.; Taib, I.; Mohammed, A. N.

2017-09-01

Meniere’s disease or known as endolymphatic hydrops is an incurable vestibular disorder of the inner ear. This is due to the excessive fluid build-up in the endolymphatic sac which causing the vestibular endolymphatic membrane to start stretching. Although this mechanism has been widely accepted as the likely mechanism of Meniere’s syndrome, the reason for its occurrence remains unclear. Thus, the aims of this study to investigate the critical parameters of fluid flow in membranous labyrinth that is influencing instability of vestibular system. In addition, to visualise the flow behaviour between a normal membranous labyrinth and dilated membranous labyrinth in Meniere’s disease in predicting instability of vestibular system. Three dimensional geometry of endolymphatic sac is obtained from Magnetic Resonance Images (MRI) and reconstructed using commercial software. As basis of comparison the two different model of endolymphatic sac is considered in this study which are normal membranous labyrinth for model I and dilated membranous labyrinth for model II. Computational fluid dynamics (CFD) method is used to analyse the behaviour of pressure and velocity flow in the endolymphatic sac. The comparison was made in terms of pressure distribution and velocity profile. The results show that the pressure for dilated membranous labyrinth is greater than normal membranous labyrinth. Due to abnormally pressure in the vestibular system, it leads to the increasing value of the velocity at dilated membranous labyrinth while at the normal membranous labyrinth the velocity values decreasing. As a conclusion by changing the parameters which is pressure and velocity can significantly affect to the instability of vestibular system for Meniere’s disease.

Bioinspired co-crystals of Imatinib providing enhanced kinetic solubility.

PubMed

Reggane, Maude; Wiest, Johannes; Saedtler, Marco; Harlacher, Cornelius; Gutmann, Marcus; Zottnick, Sven H; Piechon, Philippe; Dix, Ina; Müller-Buschbaum, Klaus; Holzgrabe, Ulrike; Meinel, Lorenz; Galli, Bruno

2018-05-04

Realizing the full potential of co-crystals enhanced kinetic solubility demands a comprehensive understanding of the mechanisms of dissolution, phase conversion, nucleation and crystal growth, and of the complex interplay between the active pharmaceutical ingredient (API), the coformer and co-existing forms in aqueous media. One blueprint provided by nature to keep poorly water-soluble bases in solution is the complexation with phenolic acids. Consequently, we followed a bioinspired strategy for the engineering of co-crystals of a poorly water-soluble molecule - Imatinib - with a phenolic acid, syringic acid (SYA). The dynamics of dissolution and solution-mediated phase transformations were monitored by Nuclear Magnetic Resonance (NMR) spectroscopy, providing mechanistic insights into the 60 fold-increased long lasting concentrations achieved by the syringate co-crystals as compared to Imatinib base and Imatinib mesylate. This lasting effect was linked to SYA's ability to delay the formation and nucleation of Imatinib hydrate - the thermodynamically stable form in aqueous media - through a metastable association of SYA with Imatinib in solution. Results from permeability studies evidenced that SYA did not impact Imatinib's permeability across membranes while suggesting improved bioavailability through higher kinetic solubility at the biological barriers. These results reflect that some degree of hydrophobicity of the coformer might be key to extend the kinetic solubility of co-crystals with hydrophobic APIs. Understanding how kinetic supersaturation can be shaped by the selection of an interactive coformer may help achieving the needed performance of new forms of poorly water-soluble, slowly dissolving APIs. Copyright © 2018. Published by Elsevier B.V.

Ex vivo study of transdermal permeation of four diclofenac salts from different vehicles.

PubMed

Minghetti, Paola; Cilurzo, Francesco; Casiraghi, Antonella; Montanari, Luisa; Fini, Adamo

2007-04-01

The ex vivo permeation of diclofenac was studied using four different salts (sodium, potassium, diethylamine, and epolamine) dissolved in four different solvents (water, propylene glycol (PG), Transcutol, and oleic acid (OA)) as donor phases through a human skin membrane. The four salts show different solubility values and different behavior in the four solvents, which are also permeation enhancers and this fact further is connected to the permeation results. The same order of magnitude of fluxes through the membrane as those previously reported for acidic diclofenac released from buffer solutions of pH >7 were found, taking into account differences originated by different membranes and other parameters tested in the experiments. Saturation concentration for the four salts in different solvents, necessary to calculate permeation coefficients, was critically evaluated; a short discussion made it possible to explain that corrections in the solubility values must be considered, related to the complex behavior in solution of these salts. Statistical processing of the experimental data suggests that differences between the four salts in promoting absorption of the drug is unproven; while differences are evident between the solvents, water is the most effective enhancing vehicle. Aqueous formulations containing diclofenac salt with an organic base appear to be the best combination to promote permeation in topical applications. (c) 2007 Wiley-Liss, Inc.

Thermal precipitation fluorescence assay for protein stability screening.

PubMed

Fan, Junping; Huang, Bo; Wang, Xianping; Zhang, Xuejun C

2011-09-01

A simple and reliable method of protein stability assessment is desirable for high throughput expression screening of recombinant proteins. Here we described an assay termed thermal precipitation fluorescence (TPF) which can be used to compare thermal stabilities of recombinant protein samples directly from cell lysate supernatants. In this assay, target membrane proteins are expressed as recombinant fusions with a green fluorescence protein tag and solubilized with detergent, and the fluorescence signals are used to report the quantity of the fusion proteins in the soluble fraction of the cell lysate. After applying a heat shock, insoluble protein aggregates are removed by centrifugation. Subsequently, the amount of remaining protein in the supernatant is quantified by in-gel fluorescence analysis and compared to samples without a heat shock treatment. Over 60 recombinant membrane proteins from Escherichia coli were subject to this screening in the presence and absence of a few commonly used detergents, and the results were analyzed. Because no sophisticated protein purification is required, this TPF technique is suitable to high throughput expression screening of recombinant membrane proteins as well as soluble ones and can be used to prioritize target proteins based on their thermal stabilities for subsequent large scale expression and structural studies. Copyright © 2011 Elsevier Inc. All rights reserved.

Intracochlear drug injections through the round window membrane: Measures to improve drug retention

PubMed Central

Plontke, Stefan K.; Hartsock, Jared J.; Gill, Ruth M.; Salt, Alec N.

2016-01-01

The goal of this study was to develop appropriate methodology to apply drugs quantitatively to perilymph of the ear. Intratympanic applications of drugs to the inner ear often result in variable drug levels in perilymph and can only be used for molecules that readily permeate the round window (RW) membrane. Direct intracochlear and intralabyrinthine application procedures for drugs, genes or cell-based therapies by-pass the tight boundaries at the round window, oval window, otic capsule and the blood-labyrinth barrier. However, perforations can release inner ear pressure, allowing cerebrospinal fluid to enter through the cochlear aqueduct, displacing the injected drug solution into the middle ear. Two markers, fluorescein or fluorescein isothiocyanate (FITC)-labeled dextran, were used to quantify how much of an injected substance was retained in cochlear perilymph following an intracochlear injection. We evaluated whether procedures to mitigate fluid leaks improved marker retention in perilymph. Almost all procedures to reduce volume efflux, including the use of gel for internal sealing and glue for external sealing of the injection site, resulted in improved retention of the marker in perilymph. Adhesive on the RW membrane effectively prevented leaks but also influenced fluid exchange between CSF and perilymph. We conclude that drugs can be delivered to the ear in a consistent, quantitative manner using intracochlear injections if care is taken to control the fluid leaks that result from cochlear perforation. PMID:26905306

Substituted polyacetylene separation membrane

DOEpatents

Pinnau, I.; Morisato, Atsushi

1998-01-13

A separation membrane is described which is useful for gas separation, particularly separation of C{sub 2+} hydrocarbons from natural gas. The invention encompasses the membrane itself, methods of making it and processes for using it. The membrane comprises a polymer having repeating units of a hydrocarbon-based, disubstituted polyacetylene, having the general formula shown in the accompanying diagram, wherein R{sub 1} is chosen from the group consisting of C{sub 1}-C{sub 4} alkyl and phenyl, and wherein R{sub 2} is chosen from the group consisting of hydrogen and phenyl. In the most preferred embodiment, the membrane comprises poly(4-methyl-2-pentyne) [PMP]. The membrane exhibits good chemical resistance and has super-glassy properties with regard to separating certain large, condensable permeant species from smaller, less-condensable permeant species. The membranes may also be useful in other fluid separations. 4 figs.

Architectures of Lipid Transport Systems for the Bacterial Outer Membrane.

PubMed

Ekiert, Damian C; Bhabha, Gira; Isom, Georgia L; Greenan, Garrett; Ovchinnikov, Sergey; Henderson, Ian R; Cox, Jeffery S; Vale, Ronald D

2017-04-06

How phospholipids are trafficked between the bacterial inner and outer membranes through the hydrophilic space of the periplasm is not known. We report that members of the mammalian cell entry (MCE) protein family form hexameric assemblies with a central channel capable of mediating lipid transport. The E. coli MCE protein, MlaD, forms a ring associated with an ABC transporter complex in the inner membrane. A soluble lipid-binding protein, MlaC, ferries lipids between MlaD and an outer membrane protein complex. In contrast, EM structures of two other E. coli MCE proteins show that YebT forms an elongated tube consisting of seven stacked MCE rings, and PqiB adopts a syringe-like architecture. Both YebT and PqiB create channels of sufficient length to span the periplasmic space. This work reveals diverse architectures of highly conserved protein-based channels implicated in the transport of lipids between the membranes of bacteria and some eukaryotic organelles. Copyright © 2017 Elsevier Inc. All rights reserved.

New saliva secretion model based on the expression of Na+-K+ pump and K+ channels in the apical membrane of parotid acinar cells.

PubMed

Almássy, János; Siguenza, Elias; Skaliczki, Marianna; Matesz, Klara; Sneyd, James; Yule, David I; Nánási, Péter P

2018-04-01

The plasma membrane of parotid acinar cells is functionally divided into apical and basolateral regions. According to the current model, fluid secretion is driven by transepithelial ion gradient, which facilitates water movement by osmosis into the acinar lumen from the interstitium. The osmotic gradient is created by the apical Cl - efflux and the subsequent paracellular Na + transport. In this model, the Na + -K + pump is located exclusively in the basolateral membrane and has essential role in salivary secretion, since the driving force for Cl - transport via basolateral Na + -K + -2Cl - cotransport is generated by the Na + -K + pump. In addition, the continuous electrochemical gradient for Cl - flow during acinar cell stimulation is maintained by the basolateral K + efflux. However, using a combination of single-cell electrophysiology and Ca 2+ -imaging, we demonstrate that photolysis of Ca 2+ close to the apical membrane of parotid acinar cells triggered significant K + current, indicating that a substantial amount of K + is secreted into the lumen during stimulation. Nevertheless, the K + content of the primary saliva is relatively low, suggesting that K + might be reabsorbed through the apical membrane. Therefore, we investigated the localization of Na + -K + pumps in acinar cells. We show that the pumps appear evenly distributed throughout the whole plasma membrane, including the apical pole of the cell. Based on these results, a new mathematical model of salivary fluid secretion is presented, where the pump reabsorbs K + from and secretes Na + to the lumen, which can partially supplement the paracellular Na + pathway.

Si-F complexing in aqueous fluids: experimental study and implications for transport of immobile elements

NASA Astrophysics Data System (ADS)

Dolejš, David

2014-05-01

Intepretation of fluid-mineral interaction mechanisms and hydrothermal fluxes requires knowledge of predominant solubility and speciation reactions and their thermodynamic properties. Fluorine represents a hard electron donor, capable of complexing and transporting high-field strength elements, which are traditionally considered to be immobile. Reactions responsible for element mobility have general form MOx + y HF (aq) + x - y H2O = M(OH)2x-yFy (aq), and their extent and transport efficiency relies on hydrogen fluoride activity. In natural fluids, a[HF] is controlled by various fluorination equilibria including neutralization of silicates with consequent formation of silicohydroxyfluoride complexes. Quartz solubility in HF-H2O fluids was experimentally determined at 400-800 oC and 100-200 MPa using rapid-quench cold-seal pressure vessels and the mineral weight-loss method. Quartz solubility significantly increases in the presence of hydrogen fluoride: at 400 oC and 100 MPa, dissolved SiO2 ranges from 0.18 wt. % in pure H2O to 12.2 wt. % at 8.3 wt. % F in the fluid, whereas at 800 oC and 200 MPa it rises from 1.51 wt. % in pure H2O to 15.3 wt. % at 8.0 wt. % F in the fluid. The isobaric solubilities of quartz appear to be temperature-independent, i.e., effects of temperature vs. fluid density on the solubility are counteracting. The experimental data are described by the density model: log m[SiO2] = a + blog ρ + clog m[F] + dT , where a = -1.049 mol kg-1, b = 0.816 mol cm-3, c = 0.802 and d = 1.256 · 10-3 mol kg-1 K-1. Solubility isotherms have similar d(log m[SiO2])/d(log m[F]) slopes over the entire range of conditions indicating that Si(OH)2F2 is the major aqueous species. Several factors promote breakdown of silicohydroxyfluoride complexes and precipitation of silica solute: (i) decreasing temperature and pressure, i.e., fluid ascent and cooling and/or (ii) neutralization and increase in the alkali/H ratio of fluids during alteration reactions or removal of hydrogen halides by fluid boiling. Thermodynamic analysis of mineral equilibria in the system SiO2-Al2O3-FeO-MgO-CaO-Na2O-K2O-H2O-F2O-1 indicates that cryolite, topaz, fluorite and sellaite represent fluoride buffers with decreasing chemical potential of F2O-1 or a[HF], in a sequence from peralkaline to peraluminous silicic, intermediate to progressively Ca-rich mafic and, finally, ultramafic environments. Corresponding a[HF] decrease from 100.2 to 10-1 and from 10-1.6 to 10-3.0 mol kg-1 at 800 and 400 oC, respectively, and 100 MPa. These results imply that: (i) silicohydroxyfluoride and aluminumhydroxyfluoride complexes transport Si and Al in quantities appreciably greater than SiO2 (aq) and aluminate species in peraluminous granite and greisen environments only, and (ii) significant transport (10-100 ppm) of high-field strength (e.g., Ti, Zr) and rare earth elements in aqueous fluids is predicted when formation constants of metal-fluoride complexes exceed 101-2 under hydrothermal conditions. This study concludes that in fluorine-bearing environments the transport of Si and Al remains little affected, but HFSE and REE are largely mobile.

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

Rouyer-Fessard, P.; Garel, M.C.; Domenget, C.

The soluble pool of alpha hemoglobin chains present in blood or bone marrow cells was measured with a new affinity method using a specific probe, beta A hemoglobin chain labeled with ({sup 3}H)N-ethylmaleimide. This pool of soluble alpha chains was 0.067 {plus minus} 0.017% of hemoglobin in blood of normal adult, 0.11 {plus minus} 0.03% in heterozygous beta thalassemia and ranged from 0.26 to 1.30% in homozygous beta thalassemia intermedia. This elevated pool of soluble alpha chains observed in human beta thalassemia intermedia decreased 33-fold from a value of 10% of total hemoglobin in bone marrow cells to 0.3% inmore » the most dense red blood cells. The amount of insoluble alpha chains was measured by using the polyacrylamide gel electrophoresis in urea and Triton X-100. In beta thalassemia intermedia the amount of insoluble alpha chains was correlated with the decreased spectrin content of red cell membrane and was associated with a decrease in ankyrin and with other abnormalities of the electrophoretic pattern of membrane proteins. The loss and topology of the reactive thiol groups of membrane proteins was determined by using ({sup 3}H)N-ethylmaleimide added to membrane ghosts prior to urea and Triton X-100 electrophoresis. Spectrin and ankyrin were the major proteins with the most important decrease of thiol groups.« less

A new oil/membrane approach for integrated sweat sampling and sensing: sample volumes reduced from μL's to nL's and reduction of analyte contamination from skin.

PubMed

Peng, R; Sonner, Z; Hauke, A; Wilder, E; Kasting, J; Gaillard, T; Swaille, D; Sherman, F; Mao, X; Hagen, J; Murdock, R; Heikenfeld, J

2016-11-01

Wearable sweat biosensensing technology has dominantly relied on techniques which place planar-sensors or fluid-capture materials directly onto the skin surface. This 'on-skin' approach can result in sample volumes in the μL regime, due to the roughness of skin and/or due to the presence of hair. Not only does this increase the required sampling time to 10's of minutes or more, but it also increases the time that sweat spends on skin and therefore increases the amount of analyte contamination coming from the skin surface. Reported here is a first demonstration of a new paradigm in sweat sampling and sensing, where sample volumes are reduced from the μL's to nL's regime, and where analyte contamination from skin is reduced or even eliminated. A micro-porous membrane is constructed such that it is porous to sweat only. To complete a working device, first placed onto skin is a cosmetic-grade oil, secondly this membrane, and thirdly the sensors. As a result, spreading of sweat is isolated to only regions above the sweat glands before it reaches the sensors. Best case sampling intervals are on the order of several minutes, and the majority of hydrophilic (low oil solubility) contaminants from the skin surface are blocked. In vitro validation of this new approach is performed with an improved artificial skin including human hair. In vivo tests show strikingly consistent results, and reveal that the oil/membrane is robust enough to even allow horizontal sliding of a sensor.

Fabrication and flow characterization of vertically aligned carbon-nanotube/polymer membranes

NASA Astrophysics Data System (ADS)

Castellano, Richard; Meshot, Eric; Fornasiero, Francesco; Shan, Jerry

2017-11-01

Membranes with well-controlled nanopores are of interest for applications as diverse as chemical separations, water purification, and ``green'' power generation. In particular, membranes incorporating carbon nanotubes (CNTs) as through-pores have been shown to pass fluids at rates orders-of-magnitude faster than predicted by continuum theory. However, cost-effective and scalable solutions for fabricating such membranes are still an area of research. We describe a solution-based fabrication technique for creating polymer composite membranes from bulk nanotubes using electric-field alignment and electrophoretic concentration. We then focus on flow characterization of membranes with single-wall nanotube (SWNT) pores. We demonstrate membrane quality by size-exclusion testing and showing that the flowrate of different gasses scales as the square root of molecular weight. The gas flowrates and moisture-vapor-transmission rates are compared with theoretical predictions and with composite membranes -fabricated from CVD-grown SWNT arrays. Funded by DTRA Grant BA12PHM123.

Identification of proteins capable of metal reduction from the proteome of the Gram-positive bacterium Desulfotomaculum reducens MI-1 using an NADH-based activity assay

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

Otwell, Annie E.; Sherwood, Roberts; Zhang, Sheng

Metal reduction capability has been found in numerous species of environmentally abundant Gram-positive bacteria. However, understanding of microbial metal reduction is based almost solely on studies of Gram-negative organisms. In this study, we focus on Desulfotomaculum reducens MI-1, a Gram-positive metal reducer whose genome lacks genes with similarity to any characterized metal reductase. D. reducens has been shown to reduce not only Fe(III), but also the environmentally important contaminants U(VI) and Cr(VI). By extracting, separating, and analyzing the functional proteome of D. reducens, using a ferrozine-based assay in order to screen for chelated Fe(III)-NTA reduction with NADH as electron donor,more » we have identified proteins not previously characterized as iron reductases. Their function was confirmed by heterologous expression in E. coli. These are the protein NADH:flavin oxidoreductase (Dred_2421) and a protein complex composed of oxidoreductase FAD/NAD(P)-binding subunit (Dred_1685) and dihydroorotate dehydrogenase 1B (Dred_1686). Dred_2421 was identified in the soluble proteome and is predicted to be a cytoplasmic protein. Dred_1685 and Dred_1686 were identified in both the soluble as well as the insoluble (presumably membrane) protein fraction, suggesting a type of membrane-association, although PSORTb predicts both proteins are cytoplasmic. Furthermore, we show that these proteins have the capability to reduce soluble Cr(VI) and U(VI) with NADH as electron donor. This study is the first functional proteomic analysis of D. reducens, and one of the first analyses of metal and radionuclide reduction in an environmentally relevant Gram-positive bacterium.« less

Determination of fat- and water-soluble vitamins by supercritical fluid chromatography: A review.

PubMed

Tyśkiewicz, Katarzyna; Dębczak, Agnieszka; Gieysztor, Roman; Szymczak, Tomasz; Rój, Edward

2018-01-01

Vitamins are compounds that take part in all basic functions of an organism but also are subject of number of studies performed by different researchers. Two groups of vitamins are distinguished taking into consideration their solubility. Chromatography with supercritical CO 2 has found application in the determination, separation, and quantitative analyses of both fat- and water-soluble vitamins. The methods of vitamins separation have developed and improved throughout the years. Both groups of compounds were separated using supercritical fluid chromatography with different detection on different stationary phases. The main aim of this review is to provide an overview of the studies of vitamins separation that have been determined so far. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Novel Architecture for Carbon Nanotube Membranes towards Fast and Efficient Oil/water Separation.

PubMed

Saththasivam, Jayaprakash; Yiming, Wubulikasimu; Wang, Kui; Jin, Jian; Liu, Zhaoyang

2018-05-09

Carbon nanotubes (CNT) are robust and proven as promising building blocks for oil/water separating membranes. However, according to classic fluid dynamic theory, achieving high permeation flux without sacrificing other membrane properties is a formidable challenge for CNT membranes, because of the trade-off nature among key membrane parameters. Herein, to relieve the trade-off between permeation fluxes, oil rejection rate, and membrane thickness, we present a new concept to engineer CNT membranes with a three-dimensional (3D) architecture. Apart from achieving high oil separation efficiency (>99.9%), these new oil/water separating membranes can achieve water flux as high as 5,500 L/m 2 .h.bar, which is one order of magnitude higher than pristine CNT membranes. Most importantly, these outstanding properties can be achieved without drastically slashing membrane thickness down to nanoscale. The present study sheds a new light for the adoption of CNT-based membranes in oil/water separation industry.

Lysimeter apparatus

DOEpatents

Clark, Don T.; Erickson, Eugene E.; Casper, William L.; Everett, David M.; Hubbell, Joel M.; Sisson, James B.

2005-09-06

A suction lysimeter for sampling subsurface liquids includes a lysimeter casing having a drive portion, a reservoir portion, and a tip portion, the tip portion including a membrane through which subsurface liquids may be sampled; a fluid conduit coupled in fluid flowing relation relative to the membrane, and which in operation facilitates the delivery of the sampled subsurface liquids from the membrane to the reservoir portion; and a plurality of tubes coupled in fluid flowing relation relative to the reservoir portion, the tubes in operation facilitating delivery of the sampled subsurface liquids from the reservoir portion for testing. A method of sampling subsurface liquids comprises using this lysimeter.

Study of Dynamic Membrane Behavior in Applied DC Electric Field

NASA Astrophysics Data System (ADS)

Dutta, Prashanta; Morshed, Adnan; Hossan, Mohammad

2017-11-01

Electrodeformation of vesicles can be used as a useful tool to understand the characteristics of biological soft matter, where vesicles immersed in a fluid medium are subjected to an applied electric field. The complex response of the vesicle membrane strongly depends on the conductivity of surrounding fluid, vesicle size and shape, and applied electric field We studied the electrodeformation of vesicles immersed in a fluid media under a short DC electric pulse. An immersed interface method is used to solve the electric field over the domain with conductive or non-conductive vesicles while an immersed boundary scheme is employed to solve fluid flow, fluid-solid interaction, membrane mechanics and vesicle movement. Force analysis on the membrane surface reveals almost linear relation with vesicle size, but highly nonlinear influence of applied field as well as the conductivity ratios inside and outside of the vesicle. Results also point towards an early linear deformation regime followed by an equilibrium stage for the membranes. Moreover, significant influence of the initial aspect ratio of the vesicle on the force distribution is observed across a range of conductivity ratios. Research reported in this publication was supported by the National Institute of General Medical Sciences of the National Institutes of Health under Award Number R01GM122081.

Subcellular Distribution of S-Nitrosylated H-Ras in Differentiated and Undifferentiated PC12 Cells during Hypoxia.

PubMed

Barbakadze, Tamar; Goloshvili, Galina; Narmania, Nana; Zhuravliova, Elene; Mikeladze, David

2017-10-01

Hypoxia or exposure to excessive reactive oxygen or nitrogen species could induce S-nitrosylation of various target proteins, including GTPases of the Ras-superfamily. Under hypoxic conditions, the Ras-protein is translocated to the cytosol and interacts with the Golgi complex, endoplasmic reticulum, mitochondria. The mobility/translocation of Ras depend on the cells oxidative status. However, the importance of relocated Snitrosylated- H-Ras (NO-H-Ras) in proliferation/differentiation processes is not completely understood. We have determined the content of soluble- and membrane-bound-NO-HRas in differentiated (D) and undifferentiated (ND) rat pheochromocytoma (PC12) cells under hypoxic and normoxic conditions. In our experimental study, we analyzed NO-H-Ras levels under hypoxic/normoxic conditions in membrane and soluble fractions of ND and D PC12 cells with/without nitric oxide donor, sodium nitroprusside (SNP) treatment. Cells were analyzed by the S-nitrosylated kit, immunoprecipitation, and Western blot. We assessed the action of NO-H-Ras on oxidative metabolism of isolated mitochondria by determining mitochondrial hydrogen peroxide generation via the scopoletin oxidation method and ATPproduction as estimated by the luminometric method. Hypoxia did not influence nitrosylation of soluble H-Ras in ND PC12 cells. Under hypoxic conditions, the nitrosylation of soluble-H-Ras greatly decreased in D PC12 cells. SNP didn't change the levels of nitrosylation of soluble-H-Ras, in either hypoxic or normoxic conditions. On the other hand, hypoxia, per se, did not affect the nitrosylation of membrane-bound-H-Ras in D and ND PC12 cells. SNP-dependent nitrosylation of membrane-bound-H-Ras greatly increased in D PC12 cells. Both unmodified normal and mutated H-Ras enhanced the mitochondrial synthesis of ATP, whereas the stimulatory effects on ATP synthesis were eliminated after S-nitrosylation of H-Ras. According to the results, it may be proposed that hypoxia can decrease S-nitrosylation of soluble-H-Ras in D PC12 cells and abolish the inhibitory effect of NO-HRas in mitochondrial oxidative metabolism. Copyright© by Royan Institute. All rights reserved.

Solubility of small-chain carboxylic acids in supercritical carbon dioxide

DOE PAGES

Sparks, Darrell L.; Estevez, L. Antonio; Hernandez, Rafael; ...

2010-07-08

The solubility of heptanoic acid and octanoic acid in supercritical carbon dioxide has been determined at temperatures of (313.15, 323.15, and 333.15) K over a pressure range of (8.5 to 30.0) MPa, depending upon the solute. The solubility of heptanoic acid ranged from a solute concentration of (0.08 ± 0.03) kg • m -3 (T = 323.15 K, p = 8.5 MPa) to (147 ± 0.2) kg • m -3 (T = 323.15 K, p = 20.0 MPa). The lowest octanoic acid solubility obtained was a solute concentration of (0.40 ± 0.1) kg • m -3 (T = 333.15 K,more » p = 10.0 MPa), while the highest solute concentration was (151 ± 2) kg • m -3 (T = 333.15 K, p = 26.7 MPa). In addition, solubility experiments were performed for nonanoic acid in supercritical carbon dioxide at 323.15 K and pressures of (10.0 to 30.0) MPa to add to the solubility data previously published by the authors. In general, carboxylic acid solubility increased with increasing solvent density. The results also showed that the solubility of the solutes decreased with increasing molar mass at constant supercritical-fluid density. Additionally, the efficacy of Chrastil's equation and other density-based models was evaluated for each fatty acid.« less

The importance of geochemical processes for the sustainability of deep geothermal systems: insights from coupled thermal-hydraulic-chemical modeling of the geothermal system at Bad Blumau, Austria

NASA Astrophysics Data System (ADS)

Alt-Epping, P.; Waber, H. N.; Eichinger, L.; Diamond, L. W.

2009-04-01

We use reactive-transport models patterned after the geothermal system at Bad Blumau, Austria, to track the fate of a fluid during its ascent from the geothermal reservoir to the surface, where it undergoes heat- and CO2-extraction, and during its subsequent reinjection into the deep aquifer. The fluid in the reservoir is in equilibrium with the carbonate-dominated mineralogy of the aquifer rock at local temperature and pressure conditions. Pressure and conductive temperature changes during ascent and descent of the fluid induce changes in mineral solubilities. Subsequent mineral precipitation within the borehole changes the fluid composition and gradually clogs the borehole, thereby obstructing fluid flow. Because different minerals exhibit different solubilities as a function of temperature, the mineral assemblages that precipitate in the production well are distinct from those in the injection well. For instance, if the fluid in the reservoir is saturated in quartz, then the prograde solubility behaviour of quartz favours its precipitation in the production well. Conversely, carbonate minerals tend to precipitate in the injection well owing to their retrograde solubility functions. However, calculating the distribution of mineral phases is complicated by the fact that the precipitation of some minerals is kinetically controlled, such that they may continue to precipitate far into the injection well (e.g. quartz). The strongest modification of the fluid composition and the greatest potential for mineral precipitation occurs during heat extraction, and, in the particular case of Bad Blumau, during the extraction of CO2 at the surface. The extraction of CO2 entails a dramatic increase in the pH and leads to massive precipitation of carbonate minerals. Simulations suggest that, in the worst case, the extraction of CO2 can cause the borehole to be sealed by carbonate minerals within a few weeks. Thus, the use of chemical additives to inhibit carbonate precipitation is imperative in the Bad Blumau system. Furthermore, any modification of the fluid composition caused by mineral precipitation along the fluid's pathway means that the reinjected fluid is no longer in equilibrium with the aquifer rock. Consequently, rock-water interaction and fluid mixing at the base of the injection well drive chemical reactions that cause changes in porosity and permeability of the aquifer, potentially compromising the efficiency of the geothermal system. One concern during geothermal energy production is that of chemical corrosion of the borehole casing. For a range of "what-if" scenarios we explore the effect of corrosion on the fluid composition and on mineral precipitation to identify chemical fingerprints that could be used as corrosion indicators. Once suitable indicators are identified, incipient corrosion could be detected early on during regular chemical monitoring. Corrosion of the casing is typically associated with the release of Fe and H2 into the circulating fluid. However, the implications of this release depend on the local chemical conditions where corrosion occurs. For instance, elevated H2 in the fluid is a corrosion indicator only if it is not involved in subsequent redox reactions. Similarly, low H2 concentrations do not rule out possible corrosion. In general, the interpretation of a fluid or a mineral sample requires the understanding of chemical processes that occur along the flowpath throughout the geothermal system. If direct observations are not possible, then this understanding can only be achieved through numerical simulations that integrate and couple fluid flow, heat transport and chemical reactions within one theoretical framework. Our simulations demonstrate that these models are useful for quantifying the impact and minimizing the risk that chemical reactions may have on the productivity and sustainability of a geothermal system.

Insight into the effect of organic and inorganic draw solutes on the flux stability and sludge characteristics in the osmotic membrane bioreactor.

PubMed

Siddique, Muhammad Saboor; Khan, Sher Jamal; Shahzad, Muhammad Aamir; Nawaz, Muhammad Saqib; Hankins, Nicholas P

2018-02-01

In this study, chloride based (CaCl 2 and MgCl 2 ) and acetate based (NaOAc and MgOAc) salts in comparison with NaCl were investigated as draw solutions (DS) to evaluate their viability in the osmotic membrane bioreactor (OMBR). Membrane distillation was coupled with an OMBR setup to develop a hybrid OMBR-MD system, for the production of clean water and DS recovery. Results demonstrate that organic DS were able to mitigate the salinity buildup in the bioreactor as compared to inorganic salts. Prolonged filtration runs were observed with MgCl 2 and MgOAc in contrast with other draw solutes at the same molar concentration. Significant membrane fouling was observed with NaOAc while rapid flux decline due to increased salinity build-up was witnessed with NaCl and CaCl 2 . Improved characteristics of mixed liquor in terms of sludge filterability, particle size, and biomass growth along with the degradation of soluble microbial products (SMP) were found with organic DS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Proceedings of the Conference on Toxicology Held in Dayton, Ohio on 28- 30 October 1986

DTIC Science & Technology

1987-12-01

paints (3). TBT is released from the painted surfaces by hydrolysis , forming species such as TBT hydroxide and TBT chloride. Several organotin-based...postfixation, and followed by dehydration through an increasing series of ethanol concentrations, lacked the electron-dense intramembranous...observed in osmium-fixed preparations. Presumably, the ethanol dehydration extracted any tin aggregates from the membranes because of the solubility

In vitro growth of Vibrio cholerae in cholera stool fluid leads to differential expression of virulence factors.

PubMed

Sánchez, J; Castillo, G; Medrano, A I; Martinez-Palomo, A; Rodríguez, M H

1995-01-01

We report on the physiological response of Vibrio cholerae upon growth on bacteria-free intestinal fluids prepared from feces of individuals in the acute phase of cholera. Sterilized stool fluids supported growth of V. cholerae to reach 0.3-0.4 O.D. units (600 nm) at 37 degrees C. Scanning electron microscopy showed vibrios to be slender and elongated as compared to bacteria in synthetic media. Growth in stool fluid apparently induced expression of several immunoreactive proteins using cholera convalescent sera. Supernatants of fluid-grown vibrios had undetectable cholera toxin (CT) concentrations. Soluble hemagglutinins and soluble proteases were much less reduced when compared to cultures in Syncase or AKI media while cell-associated mannose-sensitive hemagglutinin (MSHA) was expressed at good levels. Lack of production of CT in fluid devoid of tissue may be due to absence of stimulating elements in intact intestine. Alternatively, culturing V. cholerae in stool fluid might resemble a late proliferation stage where downregulation of toxin might occur. Irrespectively, concomitant production of other virulence factors represents a phenomenon of differential regulation by fluid. Efforts are now underway to determine if this response depends upon factors in stool fluid acting through known genetic regulatory cascades or other. Attempts are also geared to identify fluid-induced proteins and their genes.

Amniotic fluid cathepsin-G in pregnancies complicated by the preterm prelabor rupture of membranes.

PubMed

Musilova, Ivana; Andrys, Ctirad; Drahosova, Marcela; Soucek, Ondrej; Pliskova, Lenka; Stepan, Martin; Bestvina, Tomas; Maly, Jan; Jacobsson, Bo; Kacerovsky, Marian

2017-09-01

The aim of this study was to evaluate the amniotic fluid cathepsin-G concentrations in women with preterm prelabor rupture of membranes (PPROM) based on the presence of the microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation (IAI). A total of 154 women with singleton pregnancies complicated by PPROM were included in this study. Amniotic fluid samples were obtained by transabdominal amniocentesis. Amniotic fluid cathepsin-G concentrations were assessed by ELISA. MIAC was determined using a non-cultivation approach. IAI was defined as an amniotic fluid bedside interleukin-6 concentration ≥ 745 pg/mL. Women with MIAC had higher amniotic fluid cathepsin-G concentrations than women without MIAC (with MIAC: median 82.7 ng/mL, versus without MIAC: median 64.7 ng/mL; p = 0.0003). Women with IAI had higher amniotic fluid cathepsin-G concentrations than women without this complication (with IAI: median 103.0 ng/mL, versus without IAI: median 66.2 ng/mL; p < 0.0001). Women with microbial-associated (with both MIAC and IAI) IAI and sterile (IAI without MIAC) IAI had higher amniotic fluid cathepsin-G concentrations than women with colonization (MIAC without IAI) and women without both MIAC and IAI (p < 0.0001). The presence of either microbial-associated or sterile IAI was associated with increased amniotic fluid cathepsin-G concentrations in pregnancies complicated by PPROM. Amniotic fluid cathepsin-G appears to be a potential marker of IAI.

Triacylglycerol mimetics regulate membrane interactions of glycogen branching enzyme: implications for therapy.

PubMed

Alvarez, Rafael; Casas, Jesús; López, David J; Ibarguren, Maitane; Suari-Rivera, Ariadna; Terés, Silvia; Guardiola-Serrano, Francisca; Lossos, Alexander; Busquets, Xavier; Kakhlon, Or; Escribá, Pablo V

2017-08-01

Adult polyglucosan body disease (APBD) is a neurological disorder characterized by adult-onset neurogenic bladder, spasticity, weakness, and sensory loss. The disease is caused by aberrant glycogen branching enzyme (GBE) (GBE1Y329S) yielding less branched, globular, and soluble glycogen, which tends to aggregate. We explore here whether, despite being a soluble enzyme, GBE1 activity is regulated by protein-membrane interactions. Because soluble proteins can contact a wide variety of cell membranes, we investigated the interactions of purified WT and GBE1Y329S proteins with different types of model membranes (liposomes). Interestingly, both triheptanoin and some triacylglycerol mimetics (TGMs) we have designed (TGM0 and TGM5) markedly enhance GBE1Y329S activity, possibly enough for reversing APBD symptoms. We show that the GBE1Y329S mutation exposes a hydrophobic amino acid stretch, which can either stabilize and enhance or alternatively, reduce the enzyme activity via alteration of protein-membrane interactions. Additionally, we found that WT, but not Y329S, GBE1 activity is modulated by Ca 2+ and phosphatidylserine, probably associated with GBE1-mediated regulation of energy consumption and storage. The thermal stabilization and increase in GBE1Y329S activity induced by TGM5 and its omega-3 oil structure suggest that this molecule has a considerable therapeutic potential for treating APBD. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

Effect of the Dialysis Fluid Buffer on Peritoneal Membrane Function in Children

PubMed Central

Nau, Barbara; Gemulla, Gita; Bonzel, Klaus E.; Hölttä, Tuula; Testa, Sara; Fischbach, Michel; John, Ulrike; Kemper, Markus J.; Sander, Anja; Arbeiter, Klaus; Schaefer, Franz

2013-01-01

Summary Background and objectives Double-chamber peritoneal dialysis fluids exert less toxicity by their neutral pH and reduced glucose degradation product content. The role of the buffer compound (lactate and bicarbonate) has not been defined in humans. Design, setting, participants, & measurements A multicenter randomized controlled trial in 37 children on automated peritoneal dialysis was performed. After a 2-month run-in period with conventional peritoneal dialysis fluids, patients were randomized to neutral-pH, low-glucose degradation product peritoneal dialysis fluids with 35 mM lactate or 34 mM bicarbonate content. Clinical and biochemical monitoring was performed monthly, and peritoneal equilibration tests and 24-hour clearance studies were performed at 0, 3, 6, and 10 months. Results No statistically significant difference in capillary blood pH, serum bicarbonate, or oral buffer supplementation emerged during the study. At baseline, peritoneal solute equilibration and clearance rates were similar. During the study, 4-hour dialysis to plasma ratio of creatinine tended to increase, and 24-hour dialytic creatinine and phosphate clearance increased with lactate peritoneal dialysis fluid but not with bicarbonate peritoneal dialysis fluid. Daily net ultrafiltration, which was similar at baseline (lactate fluid=5.4±2.6 ml/g glucose exposure, bicarbonate fluid=4.9±1.9 ml/g glucose exposure), decreased to 4.6±1.0 ml/g glucose exposure in the lactate peritoneal dialysis fluid group, whereas it increased to 5.1±1.7 ml/g glucose exposure in the bicarbonate content peritoneal dialysis fluid group (P=0.006 for interaction). Conclusions When using biocompatible peritoneal dialysis fluids, equally good acidosis control is achieved with lactate and bicarbonate buffers. Improved long-term preservation of peritoneal membrane function may, however, be achieved with bicarbonate-based peritoneal dialysis fluids. PMID:23124784

Disposable and removable nucleic acid extraction and purification cartridges for automated flow-through systems

DOEpatents

Regan, John Frederick

2014-09-09

Removable cartridges are used on automated flow-through systems for the purpose of extracting and purifying genetic material from complex matrices. Different types of cartridges are paired with specific automated protocols to concentrate, extract, and purifying pathogenic or human genetic material. Their flow-through nature allows large quantities sample to be processed. Matrices may be filtered using size exclusion and/or affinity filters to concentrate the pathogen of interest. Lysed material is ultimately passed through a filter to remove the insoluble material before the soluble genetic material is delivered past a silica-like membrane that binds the genetic material, where it is washed, dried, and eluted. Cartridges are inserted into the housing areas of flow-through automated instruments, which are equipped with sensors to ensure proper placement and usage of the cartridges. Properly inserted cartridges create fluid- and air-tight seals with the flow lines of an automated instrument.

MEMBRANES FOR TREATMENT OF HAZARDOUS WASTEWATER

EPA Science Inventory

Various types of membrane processes have been applied to separating soluble and particulate matters from aqueous streams of numerous descriptions. The extent of separation required depends on the ultimate use of produced water, which may need to be potable, recyclable, or dispos...

Method to Estimate the Dissolved Air Content in Hydraulic Fluid

NASA Technical Reports Server (NTRS)

Hauser, Daniel M.

2011-01-01

In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated temperatures.

In meso in situ serial X-ray crystallography of soluble and membrane proteins at cryogenic temperatures

PubMed Central

Huang, Chia-Ying; Olieric, Vincent; Ma, Pikyee; Howe, Nicole; Vogeley, Lutz; Liu, Xiangyu; Warshamanage, Rangana; Weinert, Tobias; Panepucci, Ezequiel; Kobilka, Brian; Diederichs, Kay; Wang, Meitian; Caffrey, Martin

2016-01-01

Here, a method for presenting crystals of soluble and membrane proteins growing in the lipid cubic or sponge phase for in situ diffraction data collection at cryogenic temperatures is introduced. The method dispenses with the need for the technically demanding and inefficient crystal-harvesting step that is an integral part of the lipid cubic phase or in meso method of growing crystals. Crystals are dispersed in a bolus of mesophase sandwiched between thin plastic windows. The bolus contains tens to hundreds of crystals, visible with an in-line microscope at macromolecular crystallography synchrotron beamlines and suitably disposed for conventional or serial crystallographic data collection. Wells containing the crystal-laden boluses are removed individually from hermetically sealed glass plates in which crystallization occurs, affixed to pins on goniometer bases and excess precipitant is removed from around the mesophase. The wells are snap-cooled in liquid nitrogen, stored and shipped in Dewars, and manually or robotically mounted on a goniometer in a cryostream for diffraction data collection at 100 K, as is performed routinely with standard, loop-harvested crystals. The method is a variant on the recently introduced in meso in situ serial crystallography (IMISX) method that enables crystallo­graphic measurements at cryogenic temperatures where crystal lifetimes are enormously enhanced whilst reducing protein consumption dramatically. The new approach has been used to generate high-resolution crystal structures of a G-protein-coupled receptor, α-helical and β-barrel transporters and an enzyme as model integral membrane proteins. Insulin and lysozyme were used as test soluble proteins. The quality of the data that can be generated by this method was attested to by performing sulfur and bromine SAD phasing with two of the test proteins. PMID:26894538

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation

PubMed Central

Casado-Coterillo, Clara; López-Guerrero, María del Mar; Irabien, Ángel

2014-01-01

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials. PMID:24957178

Comparative research of effectiveness of cellulose and fiberglass porous membrane carriers for bio sampling in veterinary and food industry monitoring

NASA Astrophysics Data System (ADS)

Gusev, Alexander; Vasyukova, Inna; Zakharova, Olga; Altabaeva, Yuliya; Saushkin, Nikolai; Samsonova, Jeanne; Kondakov, Sergey; Osipov, Alexander; Snegin, Eduard

2017-11-01

The aim of proposed research is to study the applicability of fiberglass porous membrane materials in a new strip format for dried blood storage in food industry monitoring. A comparative analysis of cellulosic and fiberglass porous membrane materials was carried out to obtain dried samples of serum or blood and the possibility of further species-specific analysis. Blood samples of Sus scrofa were used to study the comparative effectiveness of cellulose and fiberglass porous membrane carriers for long-term biomaterial storage allowing for further DNA detection by real-time polymerase chain reaction (PCR) method. Scanning electron microscopy of various membranes - native and with blood samples - indicate a fundamental difference in the form of dried samples. Membranes based on cellulosic materials sorb the components of the biological fluid on the surface of the fibers of their structure, partially penetrating the cellulose fibers, while in the case of glass fiber membranes the components of the biological fluid dry out as films in the pores of the membrane between the structural filaments. This fundamental difference in the retention mechanisms affects the rate of dissolution of the components of dry samples and contributes to an increase in the efficiency of the desorption process of the sample before subsequent analysis. Detecting of pig DNA in every analyzed sample under the performed Real-time PCR as well as good state of the biomaterial preservation on the glass fiber membranes was clearly demonstrated. Good biomaterials preservation has been revealed on the test cards for 4 days as well as for 1 hour.

A proteomics dissection of Arabidopsis thaliana vacuoles isolated from cell culture

PubMed Central

Jaquinod, Michel; Villiers, Florent; Kieffer-Jaquinod, Sylvie; Hugouvieux, Véronique; Bruley, Christophe; Garin, Jérôme; Bourguignon, Jacques

2007-01-01

To better understand the mechanisms governing cellular traffic, storage of various metabolites and their ultimate degradation, Arabidopsis thaliana vacuoles proteomes were established. To this aim, a procedure was developed to prepare highly purified vacuoles from protoplasts isolated from Arabidopsis cell cultures using Ficoll density gradients. Based on the specific activity of the vacuolar marker α-mannosidase, the enrichment factor of the vacuoles was estimated at approximately 42 fold with an average yield of 2.1%. Absence of significant contamination by other cellular compartments was validated by western blot using antibodies raised against specific markers of chloroplasts, mitochondria, plasma membrane and endoplasmic reticulum. Based on these results, vacuole preparations showed the necessary degree of purity for proteomic study. Therefore, a proteomic approach was developed in order to identify the protein components present in both the membrane and soluble fractions of the Arabidopsis cell vacuoles. This approach includes: (i) a mild oxidation step leading to the transformation of cysteine residues into cysteic acid and methionine to methionine sulfoxide, (ii) an in-solution proteolytic digestion of very hydrophobic proteins, (iii) a pre-fractionation of proteins by short migration on SDS-PAGE followed by analysis by liquid chromatography coupled to tandem mass spectrometry. This procedure allowed the identification of more than 650 proteins, 2/3 of which copurify with the membrane hydrophobic fraction and 1/3 with the soluble fraction. Among the 416 proteins identified from the membrane fraction, 195 were considered integral membrane proteins based on the presence of one or more predicted transmembrane domains, and 110 transporters and related proteins were identified (91 putative transporters and 19 proteins related to the V-ATPase pump). With regard to function, about 20% of the proteins identified were previously known to be associated with vacuolar activities. The proteins identified are involved in: ion and metabolite transport (26%), stress response (9%), signal transduction (7%), metabolism (6%) or have been described to be involved in typical vacuolar activities, such as protein- and sugar-hydrolysis. The sub-cellular localization of several putative vacuolar proteins was confirmed by transient expression of GFP-fusion constructs. PMID:17151019

Recovery of Minerals in Martian Soils Via Supercritical Fluid Extraction

NASA Astrophysics Data System (ADS)

Debelak, Kenneth A.; Roth, John A.

2001-03-01

We are investigating the use of supercritical fluids to extract mineral and/or carbonaceous material from Martian surface soils and its igneous crust. Two candidate supercritical fluids are carbon dioxide and water. The Martian atmosphere is composed mostly of carbon dioxide (approx. 95.3%) and could therefore provide an in-situ source of carbon dioxide. Water, although present in the Martian atmosphere at only approx. 0.03%, is also a candidate supercritical solvent. Previous work done with supercritical fluids has focused primarily on their solvating properties with organic compounds. Interestingly, the first work reported by Hannay and Hogarth at a meeting of the Royal Society of London in 1879 observed that increasing or decreasing the pressure caused several inorganic salts e.g., cobalt chloride, potassium iodide, and potassium bromide, to dissolve or precipitate in supercritical ethanol. In high-pressure boilers, silica, present in most boiler feed waters, is dissolved in supercritical steam and transported as dissolved silica to the turbine blades. As the pressure is reduced the silica precipitates onto the turbine blades eventually requiring the shutdown of the generator. In supercritical water oxidation processes for waste treatment, dissolved salts present a similar problem. The solubility of silicon dioxide (SiO2) in supercritical water is shown. The solubility curve has a shape characteristic of supercritical systems. At a high pressure (greater than 1750 atmospheres) increasing the temperature results in an increase in solubility of silica, while at low pressures, less than 400 atm., the solubility decreases as temperature increases. There are only a few studies in the literature where supercritical fluids are used in extractive metallurgy. Bolt modified the Mond process in which supercritical carbon monoxide was used to produce nickel carbonyl (Ni(CO)4). Tolley and Tester studied the solubility of titanium tetrachloride (TiCl4) in supercritical CO2. They reported complete miscibility of TiCl4 with supercritical CO2 (infinite solubility). At 1500 psig, TiCl4 and CO2 form a single liquid phase below 50 C. Tolley et al. also reported on the solubility and thermodynamics of tin tetrachloride in supercritical CO2. Some of their data for TiC14 are shown. Three criteria have been suggested to predict which materials are suitable for supercritical extraction: 1) Hydrocarbons or lipophilic compounds of low molecular weight and polarity are easily extracted with supercritical CO2. 2) Compounds with polar groups are not easily extracted with supercritical CO2. 3) Separation of mixtures is facilitated if components differing mass, vapor pressure, or polarity.

Solubilization and Stabilization of Isolated Photosystem I Complex with Lipopeptide Detergents

PubMed Central

Wang, Xiaoqiang; Huang, Guihong; Yu, Daoyong; Ge, Baosheng; Wang, Jiqian; Xu, Fengxi; Huang, Fang; Xu, Hai; Lu, Jian R.

2013-01-01

It is difficult to maintain a target membrane protein in a soluble and functional form in aqueous solution without biological membranes. Use of surfactants can improve solubility, but it remains challenging to identify adequate surfactants that can improve solubility without damaging their native structures and biological functions. Here we report the use of a new class of lipopeptides to solubilize photosystem I (PS-I), a well known membrane protein complex. Changes in the molecular structure of these surfactants affected their amphiphilicity and the goal of this work was to exploit a delicate balance between detergency and biomimetic performance in PS-I solubilization via their binding capacity. Meanwhile, the effects of these surfactants on the thermal and structural stability and functionality of PS-I in aqueous solution were investigated by circular dichroism, fluorescence spectroscopy, SDS-PAGE analysis and O2 uptake measurements, respectively. Our studies showed that the solubility of PS-I depended on both the polarity and charge in the hydrophilic head of the lipopeptides and the length of its hydrophobic tail. The best performing lipopeptides in favour of PS-I solubility turned out to be C14DK and C16DK, which were comparable to the optimal amphiphilicity of the conventional chemical surfactants tested. Lipopeptides showed obvious advantages in enhancing PS-I thermostability over sugar surfactant DDM and some full peptide amphiphiles reported previously. Fluorescence spectroscopy along with SDS-PAGE analysis demonstrated that lipopeptides did not undermine the polypeptide composition and conformation of PS-I after solubilization; instead they showed better performance in improving the structural stability and integrity of this multi-subunit membrane protein than conventional detergents. Furthermore, O2 uptake measurements indicated that PS-I solubilized with lipopeptides maintained its functionality. The underlying mechanism for the favorable actions of lipopeptide in PS-I solubilization and stabilization is discussed. PMID:24098786

Characterization of soluble and membrane-bound alkaline phosphatase in Nilaparvata lugens and their potential relation to development and insecticide resistance.

PubMed

Wang, Zengxia; Liu, Shuhua; Yang, Baojun; Liu, Zewen

2011-09-01

Two forms (soluble and membrane-bound) of alkaline phosphatases (ALPs) were found in the brown planthopper, Nilaparvata lugens. In order to further study ALPs in N. lugens, two putative ALP genes (Nl-ALP1 and Nl-ALP2) were identified in this pest. Both Nl-ALP1 and Nl-ALP2 show approximately the same degree of sequence identity (40-50%) to other insect soluble and membrane-bound forms of ALP. Correlation of ALP activity and mRNA levels at different developmental stages, or following application of 20-hydroxyecdysone (20E) and insecticide fenvalerate, suggests that Nl-ALP1 and Nl-ALP2 might encode a soluble (sALP) and a membrane-bound ALP (mALP), respectively. Nl-ALP1-specific antibody Nl1-I detected only a specific band in soluble protein preparations and Nl-ALP2 specific antibody Nl2-I only detected a specific band in insoluble protein preparations, which provided conclusive linkages between Nl-ALP1 and a sALP and between Nl-ALP2 and a m ALP. Then, Nl-ALP1 was denoted as Nl-sALP for a sALP and Nl-ALP2 was denoted as Nl-mALP for a mALP. Only sALP activity and Nl-sALP mRNA level were induced by 20E and fenvalerate, which was confirmed by the density of specific band detected by Nl1-I in Sus strain with or without fenvalerate treatment. Additionally, the sALP activity, as well as Nl-sALP mRNA level, was significantly higher in a fenvalerate resistant population, compared with Sus strain. These results indicate that the sALP is more responsive to chemical stimulus, such as hormone and insecticide, and might play dual roles in development and insecticide tolerance. © 2011 Wiley Periodicals, Inc.

Protective Efficacy of Newcastle Disease Virus Expressing Soluble Trimeric Hemagglutinin against Highly Pathogenic H5N1 Influenza in Chickens and Mice

PubMed Central

Cornelissen, Lisette A. H. M.; de Leeuw, Olav S.; Tacken, Mirriam G.; Klos, Heleen C.; de Vries, Robert P.; de Boer-Luijtze, Els A.; van Zoelen-Bos, Diana J.; Rigter, Alan; Rottier, Peter J. M.; Moormann, Rob J. M.; de Haan, Cornelis A. M.

2012-01-01

Background Highly pathogenic avian influenza virus (HPAIV) causes a highly contagious often fatal disease in poultry, resulting in significant economic losses in the poultry industry. HPAIV H5N1 also poses a major public health threat as it can be transmitted directly from infected poultry to humans. One effective way to combat avian influenza with pandemic potential is through the vaccination of poultry. Several live vaccines based on attenuated Newcastle disease virus (NDV) that express influenza hemagglutinin (HA) have been developed to protect chickens or mammalian species against HPAIV. However, the zoonotic potential of NDV raises safety concerns regarding the use of live NDV recombinants, as the incorporation of a heterologous attachment protein may result in the generation of NDV with altered tropism and/or pathogenicity. Methodology/Principal Findings In the present study we generated recombinant NDVs expressing either full length, membrane-anchored HA of the H5 subtype (NDV-H5) or a soluble trimeric form thereof (NDV-sH53). A single intramuscular immunization with NDV-sH53 or NDV-H5 fully protected chickens against disease after a lethal challenge with H5N1 and reduced levels of virus shedding in tracheal and cloacal swabs. NDV-sH53 was less protective than NDV-H5 (50% vs 80% protection) when administered via the respiratory tract. The NDV-sH53 was ineffective in mice, regardless of whether administered oculonasally or intramuscularly. In this species, NDV-H5 induced protective immunity against HPAIV H5N1, but only after oculonasal administration, despite the poor H5-specific serum antibody response it elicited. Conclusions/Significance Although NDV expressing membrane anchored H5 in general provided better protection than its counterpart expressing soluble H5, chickens could be fully protected against a lethal challenge with H5N1 by using the latter NDV vector. This study thus provides proof of concept for the use of recombinant vector vaccines expressing a soluble form of a heterologous viral membrane protein. Such vectors may be advantageous as they preclude the incorporation of heterologous membrane proteins into the viral vector particles. PMID:22952980

A Proteomic View at the Biochemistry of Syntrophic Butyrate Oxidation in Syntrophomonas wolfei

PubMed Central

Schmidt, Alexander; Müller, Nicolai; Schink, Bernhard; Schleheck, David

2013-01-01

In syntrophic conversion of butyrate to methane and CO2, butyrate is oxidized to acetate by secondary fermenting bacteria such as Syntrophomonas wolfei in close cooperation with methanogenic partner organisms, e.g., Methanospirillum hungatei. This process involves an energetically unfavourable shift of electrons from the level of butyryl-CoA oxidation to the substantially lower redox potential of proton and/or CO2 reduction, in order to transfer these electrons to the methanogenic partner via hydrogen and/or formate. In the present study, all prominent membrane-bound and soluble proteins expressed in S. wolfei specifically during syntrophic growth with butyrate, in comparison to pure-culture growth with crotonate, were examined by one- and two-dimensional gel electrophoresis, and identified by peptide fingerprinting-mass spectrometry. A membrane-bound, externally oriented, quinone-linked formate dehydrogenase complex was expressed at high level specifically during syntrophic butyrate oxidation, comprising a selenocystein-linked catalytic subunit with a membrane-translocation pathway signal (TAT), a membrane-bound iron-sulfur subunit, and a membrane-bound cytochrome. Soluble hydrogenases were expressed at high levels specifically during growth with crotonate. The results were confirmed by native protein gel electrophoresis, by formate dehydrogenase and hydrogenase-activity staining, and by analysis of formate dehydrogenase and hydrogenase activities in intact cells and cell extracts. Furthermore, constitutive expression of a membrane-bound, internally oriented iron-sulfur oxidoreductase (DUF224) was confirmed, together with expression of soluble electron-transfer flavoproteins (EtfAB) and two previously identified butyryl-CoA dehydrogenases. Our findings allow to depict an electron flow scheme for syntrophic butyrate oxidation in S. wolfei. Electrons derived from butyryl-CoA are transferred through a membrane-bound EtfAB:quinone oxidoreductase (DUF224) to a menaquinone cycle and further via a b-type cytochrome to an externally oriented formate dehydrogenase. Hence, an ATP hydrolysis-driven proton-motive force across the cytoplasmatic membrane would provide the energy input for the electron potential shift necessary for formate formation. PMID:23468890

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

Code of Federal Regulations, 2013 CFR

2013-04-01

... (Oxyuris equii). (2) Limitations. Aqueous solution: administer by stomach tube or drench 1 fluid ounce per 100 pounds of body weight. Reconstituted soluble powder: administer by stomach tube 1 fluid ounce per...

21 CFR 520.1242c - Levamisole hydrochloride and piperazine dihydrochloride.

Code of Federal Regulations, 2010 CFR

2010-04-01

... (Oxyuris equii). (2) Limitations. Aqueous solution: administer by stomach tube or drench 1 fluid ounce per 100 pounds of body weight. Reconstituted soluble powder: administer by stomach tube 1 fluid ounce per...

Combined Effect of Fluid and Pressure on Middle Ear Function

PubMed Central

Dai, Chenkai; Wood, Mark W.; Gan, Rong Z.

2008-01-01

In our previous studies, the effects of effusion and pressure on sound transmission were investigated separately. The aim of this study is to investigate the combined effect of fluid and pressure on middle ear function. An otitis media with effusion model was created by injecting saline solution and air pressure simultaneously into the middle ear of human temporal bones. Tympanic membrane displacement in response to 90 dB SPL sound input was measured by a laser vibrometer and the compliance of the middle ear was measured by a tympanometer. The movement of the tympanic membrane at the umbo was reduced up to 17 dB by the combination of fluid and pressure in the middle ear over the auditory frequency range. The fluid and pressure effects on the umbo movement in the fluid-pressure combination are not additive. The combined effect of fluid and pressure on the umbo movement is different compared with that of only fluid or pressure change in the middle ear. Negative pressure in fluid-pressure combination had more effect on middle ear function than positive pressure. Tympanometry can detect the middle ear pressure of the fluid-pressure combination. This study provides quantitative information for analysis of the combined effect of fluid and pressure on tympanic membrane movement. PMID:18162348

Immobilized fluid membranes for gas separation

DOEpatents

Liu, Wei; Canfield, Nathan L; Zhang, Jian; Li, Xiaohong Shari; Zhang, Jiguang

2014-03-18

Provided herein are immobilized liquid membranes for gas separation, methods of preparing such membranes and uses thereof. In one example, the immobilized membrane includes a porous metallic host matrix and an immobilized liquid fluid (such as a silicone oil) that is immobilized within one or more pores included within the porous metallic host matrix. The immobilized liquid membrane is capable of selective permeation of one type of molecule (such as oxygen) over another type of molecule (such as water). In some examples, the selective membrane is incorporated into a device to supply oxygen from ambient air to the device for electrochemical reactions, and at the same time, to block water penetration and electrolyte loss from the device.

Effective tension and fluctuations in active membranes.

PubMed

Loubet, Bastien; Seifert, Udo; Lomholt, Michael Andersen

2012-03-01

We calculate the fluctuation spectrum of the shape of a lipid vesicle or cell exposed to a nonthermal source of noise. In particular, we take constraints on the membrane area and the volume of fluid that it encapsulates into account when obtaining expressions for the dependency of the membrane tension on the noise. We then investigate three possible origins of the nonthermal noise taken from the literature: A direct force, which models an external medium pushing on the membrane, a curvature force, which models a fluctuating spontaneous curvature, and a permeation force coming from an active transport of fluid through the membrane. For the direct force and curvature force cases, we compare our results to existing experiments on active membranes.

Hydrotropic Solubilization of Lipophilic Drugs for Oral Delivery: The Effects of Urea and Nicotinamide on Carbamazepine Solubility–Permeability Interplay

PubMed Central

Beig, Avital; Lindley, David; Miller, Jonathan M.; Agbaria, Riad; Dahan, Arik

2016-01-01

Hydrotropy refers to increasing the water solubility of otherwise poorly soluble compound by the presence of small organic molecules. While it can certainly increase the apparent solubility of a lipophilic drug, the effect of hydrotropy on the drugs’ permeation through the intestinal membrane has not been studied. The purpose of this work was to investigate the solubility–permeability interplay when using hydrotropic drug solubilization. The concentration-dependent effects of the commonly used hydrotropes urea and nicotinamide, on the solubility and the permeability of the lipophilic antiepileptic drug carbamazepine were studied. Then, the solubility–permeability interplay was mathematically modeled, and was compared to the experimental data. Both hydrotropes allowed significant concentration-dependent carbamazepine solubility increase (up to ∼30-fold). A concomitant permeability decrease was evident both in vitro and in vivo (∼17-fold for nicotinamide and ∼9-fold for urea), revealing a solubility–permeability tradeoff when using hydrotropic drug solubilization. A relatively simplified simulation approach based on proportional opposite correlation between the solubility increase and the permeability decrease at a given hydrotrope concentration allowed excellent prediction of the overall solubility–permeability tradeoff. In conclusion, when using hydrotropic drug solubilization it is prudent to not focus solely on solubility, but to account for the permeability as well; achieving optimal solubility–permeability balance may promote the overall goal of the formulation to maximize oral drug exposure. PMID:27826241

Soluble TL1A is sufficient for activation of death receptor 3.

PubMed

Bittner, Sebastian; Knoll, Gertrud; Füllsack, Simone; Kurz, Maria; Wajant, Harald; Ehrenschwender, Martin

2016-01-01

Death receptor 3 (DR3) is a typical member of the tumor necrosis factor receptor family, and was initially identified as a T-cell co-stimulatory molecule. However, further studies revealed a more complex and partly dichotomous role for DR3 and its ligand TL1A under (patho)physiological conditions. TL1A and DR3 are not only a driving force in the development of autoimmune and inflammatory diseases, but also play an important role in counteracting these processes through an increase in the number of regulatory T cells. Ligands of the tumor necrosis factor family typically occur in two forms, membrane-bound and soluble, that can differ strikingly with respect to their efficacy in activating their corresponding receptor(s). Ligand-based approaches to activate the TL1A-DR3 pathway therefore require understanding of the molecular prerequisites of TL1A-based DR3 activation. To date, this has not been addressed. Here, we show that recombinant soluble trimeric TL1A is fully sufficient to strongly activate DR3-associated pro- and anti-apoptotic signaling pathways. In contrast to the TRAIL death receptors, which are much better activated by soluble TRAIL upon secondary ligand oligomerization, but similarly to the death receptor tumor necrosis factor receptor 1, DR3 is efficiently activated by soluble TL1A trimers. Additionally, we have measured the affinity of TL1A-DR3 interaction in a cell-based system, and demonstrated TL1A-induced DR3 internalization. Identification of DR3 as a tumor necrosis factor receptor that responds to soluble ligand trimers without further oligomerization provides a basis for therapeutic exploitation of the TL1A-DR3 pathway. © 2015 FEBS.

Comparing side chain packing in soluble proteins, protein-protein interfaces, and transmembrane proteins.

PubMed

Gaines, J C; Acebes, S; Virrueta, A; Butler, M; Regan, L; O'Hern, C S

2018-05-01

We compare side chain prediction and packing of core and non-core regions of soluble proteins, protein-protein interfaces, and transmembrane proteins. We first identified or created comparable databases of high-resolution crystal structures of these 3 protein classes. We show that the solvent-inaccessible cores of the 3 classes of proteins are equally densely packed. As a result, the side chains of core residues at protein-protein interfaces and in the membrane-exposed regions of transmembrane proteins can be predicted by the hard-sphere plus stereochemical constraint model with the same high prediction accuracies (>90%) as core residues in soluble proteins. We also find that for all 3 classes of proteins, as one moves away from the solvent-inaccessible core, the packing fraction decreases as the solvent accessibility increases. However, the side chain predictability remains high (80% within 30°) up to a relative solvent accessibility, rSASA≲0.3, for all 3 protein classes. Our results show that ≈40% of the interface regions in protein complexes are "core", that is, densely packed with side chain conformations that can be accurately predicted using the hard-sphere model. We propose packing fraction as a metric that can be used to distinguish real protein-protein interactions from designed, non-binding, decoys. Our results also show that cores of membrane proteins are the same as cores of soluble proteins. Thus, the computational methods we are developing for the analysis of the effect of hydrophobic core mutations in soluble proteins will be equally applicable to analyses of mutations in membrane proteins. © 2018 Wiley Periodicals, Inc.

Development of new dyes for use in integrated optical sensors.

PubMed

Citterio, D; Rásonyi, S; Spichiger, U E

1996-03-01

New chromoionophores have been developed, focused on NIR applications so that optode membranes may be used in monolithically integrated optical sensors. The wavelength of maximum absorbance has been estimated for a new model compound by the Pariser-Parr-Pople (PPP) method. Several cyanine type dyes have been tested as membrane chromoionophores. Membrane composition has been altered to overcome solubility problems. In this way, simple pH-sensitive optode membranes have been produced.

Crystal structure of a soluble form of human monoglyceride lipase in complex with an inhibitor at 1.35 Å resolution

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

Schalk-Hihi, Céline; Schubert, Carsten; Alexander, Richard

2011-12-22

A high-resolution structure of a ligand-bound, soluble form of human monoglyceride lipase (MGL) is presented. The structure highlights a novel conformation of the regulatory lid-domain present in the lipase family as well as the binding mode of a pharmaceutically relevant reversible inhibitor. Analysis of the structure lacking the inhibitor indicates that the closed conformation can accommodate the native substrate 2-arachidonoyl glycerol. A model is proposed in which MGL undergoes conformational and electrostatic changes during the catalytic cycle ultimately resulting in its dissociation from the membrane upon completion of the cycle. In addition, the study outlines a successful approach to transformmore » membrane associated proteins, which tend to aggregate upon purification, into a monomeric and soluble form.« less

A soluble acid invertase is directed to the vacuole by a signal anchor mechanism.

PubMed

Rae, Anne L; Casu, Rosanne E; Perroux, Jai M; Jackson, Mark A; Grof, Christopher P L

2011-06-15

Enzyme activities in the vacuole have an important impact on the net concentration of sucrose. In sugarcane (Saccharum hybrid), immunolabelling demonstrated that a soluble acid invertase (β-fructofuranosidase; EC 3.2.1.26) is present in the vacuole of storage parenchyma cells during sucrose accumulation. Examination of sequences from sugarcane, barley and rice showed that the N-terminus of the invertase sequence contains a signal anchor and a tyrosine motif, characteristic of single-pass membrane proteins destined for lysosomal compartments. The N-terminal peptide from the barley invertase was shown to be capable of directing the green fluorescent protein to the vacuole in sugarcane cells. The results suggest that soluble acid invertase is sorted to the vacuole in a membrane-bound form. Copyright © 2010 Elsevier GmbH. All rights reserved.

A STUDY OF THE COMPONENTS OF THE CORNIFIED EPITHELIUM OF HUMAN SKIN

PubMed Central

Matoltsy, A. Gedeon; Balsamo, Constance A.

1955-01-01

Pulverized cornified epithelium of human skin was divided into a "soluble fraction" and a "residue." About half of the "soluble fraction" proved to be soluble epidermal keratin (keratin A); the remainder, dialyzable substances of low molecular weight. The "residue" contained epidermal keratin and resistant cell membranes of cornified cells. Epidermal keratin was found to form an oriented and dense submicroscopic structure in the cornified cells. It showed high resistance toward strong acid and moderately strong alkali solutions as well as concentrated urea. In strong alkali, reducing substances, alkaline urea, and mixtures of reducing substance with alkali, epidermal keratin dissociated and yielded a non-dialyzable derivative of high molecular weight (keratin B) which resembled true proteins. The cell membranes of cornified cells showed higher resistance toward strong alkali and reducing substance than did epidermal keratin. PMID:13242598

The Chemical Behavior of Fluids Released during Deep Subduction Based on Fluid Inclusions

NASA Astrophysics Data System (ADS)

Frezzotti, M. L.; Ferrando, S.

2014-12-01

We present a review of current research on fluid inclusions in (HP-) UHP metamorphic rocks that, combined with existing experimental research and thermodynamic models, allow us to investigate the chemical and physical properties of fluids released during deep subduction, their solvent and element transport capacity, and the subsequent implications for the element recycling in the mantle wedge. An impressive number of fluid inclusion studies indicate three main populations of fluid inclusions in HP and UHP metamorphic rocks: i) aqueous and/or non-polar gaseous fluid inclusions (FI), ii) multiphase solid inclusions (MSI), and iii) melt inclusions (MI). Chemical data from preserved fluid inclusions in rocks match with and implement "model" fluids by experiments and thermodynamics, revealing a continuity behind the extreme variations of physico-chemical properties of subduction-zone fluids. From fore-arc to sub-arc depths, fluids released by progressive devolatilization reactions from slab lithologies change from relatively diluted chloride-bearing aqueous solutions (± N2), mainly influenced by halide ligands, to (alkali) aluminosilicate-rich aqueous fluids, in which polymerization probably governs the solubility and transport of major (e.g., Si and Al) and trace elements (including C). Fluid inclusion data implement the petrological models explaining deep volatile liberation in subduction zones, and their flux into the mantle wedge.

Low cost, microcontroller based heating device for multi-wavelength differential scanning fluorimetry.

PubMed

Hoeser, Jo; Gnandt, Emmanuel; Friedrich, Thorsten

2018-01-23

Differential scanning fluorimetry is a popular method to estimate the stability of a protein in distinct buffer conditions by determining its 'melting point'. The method requires a temperature controlled fluorescence spectrometer or a RT-PCR machine. Here, we introduce a low-budget version of a microcontroller based heating device implemented into a 96-well plate reader that is connected to a standard fluorescence spectrometer. We demonstrate its potential to determine the 'melting point' of soluble and membranous proteins at various buffer conditions.

Biointerfacing polymeric microcapsules for in vivo near-infrared light-triggered drug release

NASA Astrophysics Data System (ADS)

Shao, Jingxin; Xuan, Mingjun; Si, Tieyan; Dai, Luru; He, Qiang

2015-11-01

Seeking safe and effective water-soluble drug carriers is of great significance in nanomedicine. To achieve this goal, we present a novel drug delivery system based on biointerfacing hollow polymeric microcapsules for effectively encapsulating water-soluble antitumor drug and gold nanorod (GNR) functionalization for triggered release of therapeutic drugs on-demand using low power near-infrared (NIR) radiation. The surface of polymeric microcapsules is covered with fluidic lipid bilayers to decrease the permeability of the wall of polymeric capsules. The temperature increase upon NIR illumination deconstructs the structure of the lipid membrane and polyelectrolyte multilayers, which in turn results in the rapid release of encapsulated water-soluble drug. In vivo antitumor tests demonstrate that this microcapsule has the effective ability of inhibiting tumor growth and preventing metastases. Real time in vivo fluorescence imaging results confirm that capsules can be excreted gradually from the animal body which in turn demonstrates the biocompatibility and biodegradation of these biointerfacing GNR-microcapsules. This intelligent system provides a novel anticancer platform with the advantages of controlled release, biological friendliness and credible biosafety.Seeking safe and effective water-soluble drug carriers is of great significance in nanomedicine. To achieve this goal, we present a novel drug delivery system based on biointerfacing hollow polymeric microcapsules for effectively encapsulating water-soluble antitumor drug and gold nanorod (GNR) functionalization for triggered release of therapeutic drugs on-demand using low power near-infrared (NIR) radiation. The surface of polymeric microcapsules is covered with fluidic lipid bilayers to decrease the permeability of the wall of polymeric capsules. The temperature increase upon NIR illumination deconstructs the structure of the lipid membrane and polyelectrolyte multilayers, which in turn results in the rapid release of encapsulated water-soluble drug. In vivo antitumor tests demonstrate that this microcapsule has the effective ability of inhibiting tumor growth and preventing metastases. Real time in vivo fluorescence imaging results confirm that capsules can be excreted gradually from the animal body which in turn demonstrates the biocompatibility and biodegradation of these biointerfacing GNR-microcapsules. This intelligent system provides a novel anticancer platform with the advantages of controlled release, biological friendliness and credible biosafety. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06350g

Cell-free system for synthesizing membrane proteins cell free method for synthesizing membrane proteins

DOEpatents

Laible, Philip D; Hanson, Deborah K

2013-06-04

The invention provides an in vitro method for producing proteins, membrane proteins, membrane-associated proteins, and soluble proteins that interact with membrane-associated proteins for assembly into an oligomeric complex or that require association with a membrane for proper folding. The method comprises, supplying intracytoplasmic membranes from organisms; modifying protein composition of intracytoplasmic membranes from organism by modifying DNA to delete genes encoding functions of the organism not associated with the formation of the intracytoplasmic membranes; generating appropriate DNA or RNA templates that encode the target protein; and mixing the intracytoplasmic membranes with the template and a transcription/translation-competent cellular extract to cause simultaneous production of the membrane proteins and encapsulation of the membrane proteins within the intracytoplasmic membranes.

Diamine-Appended Mg 2 (dobpdc) Nanorods as Phase-Change Fillers in Mixed-Matrix Membranes for Efficient CO 2/N 2 Separations

DOE PAGES

Maserati, Lorenzo; Meckler, Stephen M.; Bachman, Jonathan E.; ...

2017-10-18

Despite the availability of chemistries to tailor the pore architectures of microporous polymer membranes for chemical separations, trade-offs in permeability and selectivity with functional group manipulations nevertheless persist, which ultimately places an upper bound on membrane performance. We introduce a new design strategy to uncouple these attributes of the membrane. Key to our success is the incorporation of phase-change metal-organic frameworks (MOFs) into the polymer matrix, which can be used to increase the solubility of a specific gas in the membrane, and thereby its permeability. We further show that it is necessary to scale the size of the phase-change MOFmore » to nanoscopic dimensions, in order to take advantage of this effect in a gas separation. Our observation of an increase in solubility and permeability of only one of the gases during steady-state permeability measurements suggests fast exchange between free and chemisorbed gas molecules within the MOF pores. While the kinetics of this exchange in phase-change MOFs are not yet fully understood, their role in enhancing the efficacy and efficiency of the separation is clearly a compelling new direction for membrane technology.« less

Chemical synthesis of membrane proteins by the removable backbone modification method.

PubMed

Tang, Shan; Zuo, Chao; Huang, Dong-Liang; Cai, Xiao-Ying; Zhang, Long-Hua; Tian, Chang-Lin; Zheng, Ji-Shen; Liu, Lei

2017-12-01

Chemical synthesis can produce membrane proteins bearing specifically designed modifications (e.g., phosphorylation, isotope labeling) that are difficult to obtain through recombinant protein expression approaches. The resulting homogeneously modified synthetic membrane proteins are valuable tools for many advanced biochemical and biophysical studies. This protocol describes the chemical synthesis of membrane proteins by condensation of transmembrane peptide segments through native chemical ligation. To avoid common problems encountered due to the poor solubility of transmembrane peptides in almost any solvent, we describe an effective procedure for the chemical synthesis of membrane proteins through the removable-backbone modification (RBM) strategy. Two key steps of this protocol are: (i) installation of solubilizing Arg4-tagged RBM groups into the transmembrane peptides at any primary amino acid through Fmoc (9-fluorenylmethyloxycarbonyl) solid-phase peptide synthesis and (ii) native ligation of the full-length sequence, followed by removal of the RBM tags by TFA (trifluoroacetic acid) cocktails to afford the native protein. The installation of RBM groups is achieved by using 4-methoxy-5-nitrosalicyladehyde by reduction amination to incorporate an activated O-to-N acyl transfer auxiliary. The Arg4-tag-modified membrane-spanning peptide segments behave like water-soluble peptides to facilitate their purification, ligation and mass characterization.

High-throughput Cloning and Expression of Integral Membrane Proteins in Escherichia coli

PubMed Central

Bruni, Renato

2014-01-01

Recently, several structural genomics centers have been established and a remarkable number of three-dimensional structures of soluble proteins have been solved. For membrane proteins, the number of structures solved has been significantly trailing those for their soluble counterparts, not least because over-expression and purification of membrane proteins is a much more arduous process. By using high throughput technologies, a large number of membrane protein targets can be screened simultaneously and a greater number of expression and purification conditions can be employed, leading to a higher probability of successfully determining the structure of membrane proteins. This unit describes the cloning, expression and screening of membrane proteins using high throughput methodologies developed in our laboratory. Basic Protocol 1 deals with the cloning of inserts into expression vectors by ligation-independent cloning. Basic Protocol 2 describes the expression and purification of the target proteins on a miniscale. Lastly, for the targets that express at the miniscale, basic protocols 3 and 4 outline the methods employed for the expression and purification of targets at the midi-scale, as well as a procedure for detergent screening and identification of detergent(s) in which the target protein is stable. PMID:24510647

A Monomeric Membrane Peptide that Lives in Three Worlds: In Solution, Attached to, and Inserted across Lipid Bilayers

PubMed Central

Reshetnyak, Yana K.; Segala, Michael; Andreev, Oleg A.; Engelman, Donald M.

2007-01-01

The membrane peptide pH (low) insertion peptide (pHLIP) lives in three worlds, being soluble in aqueous solution at pH 7.4, binding to the surface of lipid bilayers, and inserting as a transbilayer helix at low pH. With low pH driving the process, pHLIP can translocate cargo molecules attached to its C-terminus via a disulfide and release them in the cytoplasm of a cell. Here we examine a key aspect of the mechanism, showing that pHLIP is monomeric in each of its three major states: soluble in water near neutral pH (state I), bound to the surface of a membrane near neutral pH (state II), and inserted across the membrane as an α-helix at low pH (state III). The peptide does not induce fusion or membrane leakage. The unique properties of pHLIP made it attractive for the biophysical investigation of membrane protein folding in vitro and for the development of a novel class of delivery peptides for the transport of therapeutic and diagnostic agents to acidic tissue sites associated with various pathological processes in vivo. PMID:17557792

Unconventional Transport Routes of Soluble and Membrane Proteins and Their Role in Developmental Biology

PubMed Central

Pompa, Andrea; De Marchis, Francesca; Pallotta, Maria Teresa; Benitez-Alfonso, Yoselin; Jones, Alexandra; Schipper, Kerstin; Moreau, Kevin; Žárský, Viktor; Di Sansebastiano, Gian Pietro; Bellucci, Michele

2017-01-01

Many proteins and cargoes in eukaryotic cells are secreted through the conventional secretory pathway that brings proteins and membranes from the endoplasmic reticulum to the plasma membrane, passing through various cell compartments, and then the extracellular space. The recent identification of an increasing number of leaderless secreted proteins bypassing the Golgi apparatus unveiled the existence of alternative protein secretion pathways. Moreover, other unconventional routes for secretion of soluble or transmembrane proteins with initial endoplasmic reticulum localization were identified. Furthermore, other proteins normally functioning in conventional membrane traffic or in the biogenesis of unique plant/fungi organelles or in plasmodesmata transport seem to be involved in unconventional secretory pathways. These alternative pathways are functionally related to biotic stress and development, and are becoming more and more important in cell biology studies in yeast, mammalian cells and in plants. The city of Lecce hosted specialists working on mammals, plants and microorganisms for the inaugural meeting on “Unconventional Protein and Membrane Traffic” (UPMT) during 4–7 October 2016. The main aim of the meeting was to include the highest number of topics, summarized in this report, related to the unconventional transport routes of protein and membranes. PMID:28346345

Stable Membrane-Association of mRNAs in Etiolated, Greening and Mature Plastids.

PubMed

Legen, Julia; Schmitz-Linneweber, Christian

2017-08-31

Chloroplast genes are transcribed as polycistronic precursor RNAs that give rise to a multitude of processing products down to monocistronic forms. Translation of these mRNAs is realized by bacterial type 70S ribosomes. A larger fraction of these ribosomes is attached to chloroplast membranes. This study analyzed transcriptome-wide distribution of plastid mRNAs between soluble and membrane fractions of purified plastids using microarray analyses and validating RNA gel blot hybridizations. To determine the impact of light on mRNA localization, we used etioplasts, greening plastids and mature chloroplasts from Zea mays as a source for membrane and soluble extracts. The results show that the three plastid types display an almost identical distribution of RNAs between the two organellar fractions, which is confirmed by quantitative RNA gel blot analyses. Furthermore, they reveal that different RNAs processed from polycistronic precursors show transcript-autonomous distribution between stroma and membrane fractions. Disruption of ribosomes leads to release of mRNAs from membranes, demonstrating that attachment is likely a direct consequence of translation. We conclude that plastid mRNA distribution is a stable feature of different plastid types, setting up rapid chloroplast translation in any plastid type.

Influence of pollution control on lead inhalation bioaccessibility in PM2.5: A case study of 2014 Youth Olympic Games in Nanjing.

PubMed

Li, Shi-Wei; Li, Hong-Bo; Luo, Jun; Li, Hui-Ming; Qian, Xin; Liu, Miao-Miao; Bi, Jun; Cui, Xin-Yi; Ma, Lena Q

2016-09-01

Pollution controls were implemented to improve the air quality for the 2014 Youth Olympic Games (YOG) in Nanjing. To investigate the influence of pollution control on Pb inhalation bioaccessibility in PM2.5, samples were collected before, during, and after YOG. The objectives were to identify Pb sources in PM2.5 using stable isotope fingerprinting technique and compare Pb inhalation bioaccessibility in PM2.5 using two simulated lung fluids. While artificial lysosomal fluid (ALF) simulates interstitial fluid at pH 7.4, Gamble's solution simulates fluid in alveolar macrophages at pH 4.5. The Pb concentration in PM2.5 samples during YOG (88.2ngm(-3)) was 44-48% lower than that in non-YOG samples. Based on stable Pb isotope ratios, Pb in YOG samples was mainly from coal combustion while Pb in non-YOG samples was from coal combustion and smelting activities. While Pb bioaccessibility in YOG samples was lower than those in non-YOG samples (59-79% vs. 55-87%) by ALF, it was higher than those in non-YOG samples (11-29% vs. 5.3-21%) based on Gamble's solution, attributing to the lower pH and organic acids in ALF. Different Pb bioaccessibility in PM2.5 between samples resulted from changes in Pb species due to pollution control. PbSO4 was the main Pb species in PM2.5 from coal combustion, which was less soluble in ALF than PbO from smelting activities, but more soluble in Gamble's solution. This study showed it is important to consider Pb bioaccessibility during pollution control as source control not only reduced Pb contamination in PM2.5 but also influenced Pb bioaccessibility. Published by Elsevier Ltd.

A membrane filtering method for the purification of giant unilamellar vesicles.

PubMed

Tamba, Yukihiro; Terashima, Hiroaki; Yamazaki, Masahito

2011-07-01

The use of giant unilamellar vesicles (GUVs) for investigating the properties of biomembranes is advantageous compared to the use of small-sized vesicles such as large unilamellar vesicles (LUVs). Experimental methods using GUVs, such as the single GUV method, would benefit if there was a methodology for obtaining a large population of similar-sized GUVs composed of oil-free membranes. We here describe a new membrane filtering method for purifying GUVs prepared by the natural swelling method and demonstrate that, following purification of GUVs composed of dioleoylphosphatidylglycerol (DOPG)/dioleoylphosphatidylcholine (DOPC) membranes suspended in a buffer, similar-sized GUVs with diameters of 10-30 μm are obtained. Moreover, this method enabled GUVs to be separated from water-soluble fluorescent probes and LUVs. These results suggest that the membrane filtering method can be applied to GUVs prepared by other methods to purify larger-sized GUVs from smaller GUVs, LUVs, and various water-soluble substances such as proteins and fluorescent probes. This method can also be used for concentration of dilute GUV suspensions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Optimisation of cosolvent concentration for topical drug delivery III--influence of lipophilic vehicles on ibuprofen permeation.

PubMed

Watkinson, R M; Guy, R H; Oliveira, G; Hadgraft, J; Lane, M E

2011-01-01

Previously, we have reported the effects of water, ethanol, propylene glycol and various binary and ternary mixtures of these solvents on the permeation of ibuprofen in model membranes and in skin. The present study investigates the influence of lipophilic vehicles on the transport of ibuprofen in silicone membrane and in human skin. The permeation of ibuprofen was measured from mineral oil (MO), Miglyol® 812 (MG) and binary mixtures of MO and MG. The solubility of ibuprofen was 5-fold higher in MG than in MO, however, the permeation of ibuprofen from the pure vehicles and combinations of both was comparable in silicone membrane. Additionally, there were no significant differences in skin permeation for MO and MG vehicles. When the permeation of various hydrophilic and lipophilic vehicles is considered, a trend between flux values for the model membrane and skin is evident (r(2) = 0.71). The findings suggest that silicone membrane may provide information on qualitative trends in skin permeation for vehicles of diverse solubility and partition characteristics. Copyright © 2010 S. Karger AG, Basel.

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

Maserati, Lorenzo; Meckler, Stephen M.; Bachman, Jonathan E.

Despite the availability of chemistries to tailor the pore architectures of microporous polymer membranes for chemical separations, trade-offs in permeability and selectivity with functional group manipulations nevertheless persist, which ultimately places an upper bound on membrane performance. We introduce a new design strategy to uncouple these attributes of the membrane. Key to our success is the incorporation of phase-change metal-organic frameworks (MOFs) into the polymer matrix, which can be used to increase the solubility of a specific gas in the membrane, and thereby its permeability. We further show that it is necessary to scale the size of the phase-change MOFmore » to nanoscopic dimensions, in order to take advantage of this effect in a gas separation. Our observation of an increase in solubility and permeability of only one of the gases during steady-state permeability measurements suggests fast exchange between free and chemisorbed gas molecules within the MOF pores. While the kinetics of this exchange in phase-change MOFs are not yet fully understood, their role in enhancing the efficacy and efficiency of the separation is clearly a compelling new direction for membrane technology.« less

Beryllium chemical speciation in elemental human biological fluids.

PubMed

Sutton, Mark; Burastero, Stephen R

2003-09-01

The understanding of beryllium chemistry in human body fluids is important for understanding the prevention and treatment of chronic beryllium disease. Thermodynamic modeling has traditionally been used to study environmental contaminant migration and rarely in the examination of metal (particularly beryllium) toxicology. In this work, a chemical thermodynamic speciation code (MINTEQA2) has been used to model and understand the chemistry of beryllium in simulated human biological fluids such as intracellular, interstitial, and plasma fluids, a number of airway surface fluids for patients with lung conditions, saliva, sweat, urine, bile, gastric juice, and pancreatic fluid. The results show that predicted beryllium solubility and speciation vary markedly between each simulated biological fluid. Formation of beryllium hydroxide and/or phosphate was observed in most of the modeled fluids, and results support the postulation that beryllium absorption in the gastrointestinal tract may be limited by the formation of beryllium phosphate solids. It is also postulated that beryllium is potentially 13% less soluble in the airway surface fluid of a patient with asthma when compared to a "normal" case. The results of this work, supported by experimental validation, can aid in the understanding of beryllium toxicology. Our results can potentially be applied to assessing the feasibility of biological monitoring or chelation treatment of beryllium body burden.

The presence of vaginal Lactobacillus species does not contribute to a measureable difference in amniotic fluid lactate levels collected from the vaginal tract of laboring women.

PubMed

Hall, Beverley; Wong, Diana; Healy, Clare; Tracy, Mark B; Tracy, Sally K; Rawlinson, William D

2017-04-01

Amniotic fluid lactate research is based on the hypothesis that a relationship exists between fatigued uterine muscles and raised concentrations of the metabolite lactate, which is excreted into the amniotic fluid during labor. To assess potentially confounding effects of lactate-producing organisms on amniotic fluid lactate measurements, we aimed to determine if the presence of vaginal Lactobacillus species was associated with elevated levels of amniotic fluid lactate, measured from the vaginal tract of women in labor. Results from this study contribute to a large prospective longitudinal study of amniotic fluid lactate at a teaching hospital in Sydney, Australia. Amniotic fluid lactate measurement was assessed at the time of routine vaginal examination, after membranes had ruptured, using a hand-held lactate meter StatStripXPress (Nova Biomedical). Vaginal swab samples were collected at the time of the first amniotic fluid lactate measurement and stored for later detection and quantification of Lactobacillus species using a TaqMan real-time PCR assay. Swab sample and amniotic fluid lactate results were paired and analyzed. The PCR assay detected Lactobacillus species in 48 of 388 (12%) vaginal swab specimens (8% positive, 4% low positive) collected from women in labor after membranes had ruptured. There was no significant difference in median and mean (respectively) amniotic fluid lactate levels with (8.35 mmol/L; 8.95 mmol/L) or without (8.5 mmol/L; 9.08 mmol/L) Lactobacillus species detected. There was no association between the presence or level of vaginal Lactobacillus species and the measurement of amniotic fluid lactate collected from the vaginal tract of women during labor. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

Fabrication of Polyimide Membrane Incorporated with Functional Graphene Oxide for CO2 Separation: The Effects of GO Surface Modification on Membrane Performance.

PubMed

Wang, Ting; Cheng, Cheng; Wu, Li-Guang; Shen, Jiang-Nan; Van der Bruggen, Bart; Chen, Qian; Chen, Di; Dong, Chun-Ying

2017-06-06

Two kinds of isocyanate were used to modify graphene oxide (GO) samples. Then, polyimide (PI) hybrid membranes containing GO and modified GO were prepared by in situ polymerization. The permeation of CO 2 and N 2 was studied using these novel membranes. The morphology experiments showed that the isocyanate groups were successfully grafted on the surface of GO by replacement of the oxygen-containing functional groups. After modification, the surface polarity of the GO increased, and more defect structures were introduced into the GO surface. This resulted in a good distribution of more modified GO samples in the PI polymer matrix. Thus, the PI hybrid membranes incorporated by modified GO samples showed a high gas permeability and ideal selectivity of membranes. In addition, enhancement of the selectivity due to the solubility of CO 2 played a major role in the increase in the separation performance of the hybrid membranes for CO 2 , although the diffusion coefficients for CO 2 also increased. Both the higher condensability and the strong affinity between CO 2 molecules and GO in the polymer matrix caused an enhancement of the solubility selectivity higher than the diffusion selectivity after GO surface modification.

Cervical fluid interleukin 6 and intra-amniotic complications of preterm prelabor rupture of membranes.

PubMed

Musilova, Ivana; Andrys, Ctirad; Drahosova, Marcela; Soucek, Ondrej; Pliskova, Lenka; Jacobsson, Bo; Kacerovsky, Marian

2018-04-01

To determine if cervical fluid interleukin (IL)-6 concentrations in women with preterm prelabor rupture of membranes (PPROM) allows identification of microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation (IAI). One hundred forty-four women with singleton pregnancies complicated by PPROM were included in this prospective cohort study. Cervical and amniotic fluids were collected at the time of admission and concentrations of IL-6 were measured using an ELISA and point-of-care test, respectively. Cervical fluid was obtained using a Dacron polyester swab and amniotic fluid was obtained by transabdominal amniocentesis. MIAC was diagnosed based on a positive PCR result for Ureaplasma species, M. hominis, and/or C. trachomatis and/or by positivity for the 16 S rRNA gene. IAI was defined as amniotic fluid point-of-care IL-6 concentrations ≥745 pg/mL. The women were assigned to four subgroups based on the presence of MIAC and/or IAI: microbial-associated IAI (both MIAC and IAI), sterile IAI (IAI alone), MIAC alone, and without either MIAC or IAI. (1) Women with microbial-associated IAI had higher cervical fluid IL-6 concentrations (median 560 pg/mL) than did women with sterile IAI (median 303 pg/mL; p = .001), women with MIAC alone (median 135 pg/mL; p = .0004), and women without MIAC and IAI (median 180 pg/mL; p = .0001). (2) No differences were found in cervical fluid IL-6 concentrations among women with sterile IAI, with MIAC alone, and without MIAC and IAI. (3) A positive correlation was observed between cervical fluid IL-6 concentrations and the amount of Ureaplasma species in amniotic fluid (copies DNA/mL; rho = 0.57, p < .0001). (4) A weak positive correlation was detected between cervical and amniotic fluid IL-6 concentrations (rho = 0.33, p < .0001). The presence of microbial-associated IAI is associated with the highest cervical fluid IL-6 concentrations. Cervical IL-6 can be helpful in the identification of microbial-associated IAI.

Lysimeter methods and apparatus

DOEpatents

Clark, Don T.; Erickson, Eugene E.; Casper, William L.; Everett, David M.; Hubbell, Joel M.; Sisson, James B.

2004-12-07

A suction lysimeter for sampling subsurface liquids includes a lysimeter casing having a drive portion, a reservoir portion, and a tip portion, the tip portion including a membrane through which subsurface liquids may be sampled; a fluid conduit coupled in fluid flowing relation relative to the membrane, and which in operation facilitates the delivery of the sampled subsurface liquids from the membrane to the reservoir portion; and a plurality of tubes coupled in fluid flowing relation relative to the reservoir portion, the tubes in operation facilitating delivery of the sampled subsurface liquids from the reservoir portion for testing. A method of sampling subsurface liquids comprises using this lysimeter.

Systems and methods for selective hydrogen transport and measurement

DOEpatents

Glatzmaier, Gregory C

2013-10-29

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

Convective influx/glymphatic system: tracers injected into the CSF enter and leave the brain along separate periarterial basement membrane pathways.

PubMed

Albargothy, Nazira J; Johnston, David A; MacGregor-Sharp, Matthew; Weller, Roy O; Verma, Ajay; Hawkes, Cheryl A; Carare, Roxana O

2018-05-12

Tracers injected into CSF pass into the brain alongside arteries and out again. This has been recently termed the "glymphatic system" that proposes tracers enter the brain along periarterial "spaces" and leave the brain along the walls of veins. The object of the present study is to test the hypothesis that: (1) tracers from the CSF enter the cerebral cortex along pial-glial basement membranes as there are no perivascular "spaces" around cortical arteries, (2) tracers leave the brain along smooth muscle cell basement membranes that form the Intramural Peri-Arterial Drainage (IPAD) pathways for the elimination of interstitial fluid and solutes from the brain. 2 μL of 100 μM soluble, fluorescent fixable amyloid β (Aβ) were injected into the CSF of the cisterna magna of 6-10 and 24-30 month-old male mice and their brains were examined 5 and 30 min later. At 5 min, immunocytochemistry and confocal microscopy revealed Aβ on the outer aspects of cortical arteries colocalized with α-2 laminin in the pial-glial basement membranes. At 30 min, Aβ was colocalised with collagen IV in smooth muscle cell basement membranes in the walls of cortical arteries corresponding to the IPAD pathways. No evidence for drainage along the walls of veins was found. Measurements of the depth of penetration of tracer were taken from 11 regions of the brain. Maximum depths of penetration of tracer into the brain were achieved in the pons and caudoputamen. Conclusions drawn from the present study are that tracers injected into the CSF enter and leave the brain along separate periarterial basement membrane pathways. The exit route is along IPAD pathways in which Aβ accumulates in cerebral amyloid angiopathy (CAA) in Alzheimer's disease. Results from this study suggest that CSF may be a suitable route for delivery of therapies for neurological diseases, including CAA.

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.

An elevated amniotic fluid prostaglandin F2α concentration is associated with intra-amniotic inflammation/infection, and clinical and histologic chorioamnionitis, as well as impending preterm delivery in patients with preterm labor and intact membranes.

PubMed

Park, Jee Yoon; Romero, Roberto; Lee, JoonHo; Chaemsaithong, Piya; Chaiyasit, Noppadol; Yoon, Bo Hyun

2016-01-01

To determine whether an elevated amniotic fluid concentration of prostaglandin F2α (PGF2α) is associated with intra-amniotic inflammation/infection and adverse pregnancy outcomes in patients with preterm labor and intact membranes. The retrospective cohort study included 132 patients who had singleton pregnancies with preterm labor (< 35 weeks of gestation) and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as for genital mycoplasmas. Intra-amniotic inflammation was defined by an elevated amniotic fluid matrix metalloproteinase-8 (MMP-8) concentration (>23 ng/mL). PGF2α was measured with a sensitive and specific immunoassay. The amniotic fluid PGF2α concentration was considered elevated when it was above the 95th percentile among pregnant women at 15-36 weeks of gestation who were not in labor (≥170 pg/mL). (1) The prevalence of an elevated amniotic fluid PGF2α concentration was 40.2% (53/132) in patients with preterm labor and intact membranes; (2) patients with an elevated amniotic fluid PGF2α concentration had a significantly higher rate of positive amniotic fluid culture [19% (10/53) versus 5% (4/79); p = 0.019], intra-amniotic inflammation/infection [49% (26/53) versus 20% (16/79); p = 0.001], spontaneous preterm delivery, clinical and histologic chorioamnionitis, and funisitis, as well as a higher median amniotic fluid MMP-8 concentration and amniotic fluid white blood cell count and a shorter amniocentesis-to-delivery interval than those without an elevated concentration of amniotic fluid PGF2α (p < 0.05 for each); and (3) an elevated amniotic fluid PGF2α concentration was associated with a shorter amniocentesis-to-delivery interval after adjustment for the presence of intra-amniotic inflammation/infection [hazard ratio 2.1, 95% confidence interval (CI) 1.4-3.1; p = 0.001]. The concentration of PGF2α was elevated in the amniotic fluid of 40.2% of patients with preterm labor and intact membranes and is an independent risk factor for intra-amniotic inflammation/infection, impending preterm delivery, chorioamnionitis, and funisitis.

Cocrystal Solubilization in Biorelevant Media and its Prediction from Drug Solubilization.

PubMed

Lipert, Maya P; Roy, Lilly; Childs, Scott L; Rodríguez-Hornedo, Naír

2015-12-01

This work examines cocrystal solubility in biorelevant media (FeSSIF, fed-state simulated intestinal fluid), and develops a theoretical framework that allows for the simple and quantitative prediction of cocrystal solubilization from drug solubilization. The solubilities of four hydrophobic drugs and seven cocrystals containing these drugs were measured in FeSSIF and in acetate buffer at pH 5.00. In all cases, the cocrystal solubility (Scocrystal ) was higher than the drug solubility (Sdrug ) in both buffer and FeSSIF; however, the solubilization ratio of drug, SRdrug = (SFeSSIF /Sbuffer )drug , was not the same as the solubilization ratio of cocrystal, SRcocrystal = (SFeSSIF /Sbuffer )cocrystal , meaning drug and cocrystal were not solubilized to the same extent in FeSSIF. This highlights the potential risk of anticipating cocrystal behavior in biorelevant media based on solubility studies in water. Predictions of SRcocrystal from simple equations based only on SRdrug were in excellent agreement with measured values. For 1:1 cocrystals, the cocrystal solubilization ratio (SR) can be obtained from the square root of the drug SR. For 2:1 cocrystals, SRcocrystal is found from (SRdrug )(2/3) . The findings in FeSSIF can be generalized to describe cocrystal behavior in other systems involving preferential solubilization of a drug such as surfactants, lipids, and other drug solubilizing media. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Influence of chemical and mechanical polishing on water sorption and solubility of denture base acrylic resins.

PubMed

Rahal, Juliana Saab; Mesquita, Marcelo Ferraz; Henriques, Guilherme Elias Pessanha; Nóbilo, Mauro Antonio Arruda

2004-01-01

Influence of polishing methods on water sorption and solubility of denture base acrylic resins was studied. Eighty samples were divided into groups: Classico (CL), and QC 20 (QC) - hot water bath cured; Acron MC (AC), and Onda Cryl (ON) - microwave cured; and submitted to mechanical polishing (MP) - pumice slurry, chalk powder, soft brush and felt cone in a bench vise; or chemical polishing (CP) - heated monomer fluid in a chemical polisher. The first desiccation process was followed by storage in distilled water at 37 +/- 1 degrees C for 1 h, 1 day, 1, 2, 3 and 4 weeks. Concluding each period, water sorption was measured. After the fourth week, a second desiccation process was done to calculate solubility. Data were submitted to analysis of variance, followed by Tukey test (p

Origins of saline fluids at convergent margins

NASA Astrophysics Data System (ADS)

Martin, Jonathan B.; Kastner, Miriam; Egeberg, Per Kr.

The compositions of pore and venting fluids at convergent margins differ from seawater values, reflecting mixing and diagenesis. Most significantly, the concentration of Cl-, assumed to be a conservative ion, differs from its seawater value. Chloride concentrations could be elevated by four processes, although two, the formation of gas hydrate and ion filtration by clay membranes, are insignificant in forming saline fluids at convergent margins. During the formation of gas hydrate, the resulting Cl--rich fluids, estimated to contain an average excess of ˜140 mM Cl- over seawater value, probably would be flushed from the sediment when the pore fluids vent to seawater. Ion filtration by clay membranes requires compaction pressures typical of >2 km burial depths. Even at these depths, the efficiency of ion filtration will be negligible because (1) fluids will flow through fractures, thereby bypassing clay membranes, (2) concentrations of clay minerals are diluted by other phases, and (3) during burial, smectite converts to illite, which has little capacity for ion filtration. A third process, mixing with subaerially evaporated seawater, elevates Cl- concentrations to 1043 mM in forearc basins along the Peru margin. Evaporation of seawater, however, will be important only in limited geographic regions that are characterized by enclosed basins, arid climates, and permeable sediments. At the New Hebrides and Izu-Bonin margins, Cl- concentrations are elevated to a maximum of 1241 mM. The process responsible for this increase is the alteration of volcanic ash to hydrous clay and zeolite minerals. Mass balance calculations, based on the decrease in δ18O values to -9.5‰ (SMOW), suggest that the Cl- concentrations could increase solely from the formation of smectite in a closed system. The diagenesis of volcanic ash also alters the concentrations of most dissolved species in addition to Cl-. Depending on the volume of this altered fluid, it could influence seawater chemistry when vented from the sediment.

Prediction of the translocon-mediated membrane insertion free energies of protein sequences.

PubMed

Park, Yungki; Helms, Volkhard

2008-05-15

Helical membrane proteins (HMPs) play crucial roles in a variety of cellular processes. Unlike water-soluble proteins, HMPs need not only to fold but also get inserted into the membrane to be fully functional. This process of membrane insertion is mediated by the translocon complex. Thus, it is of great interest to develop computational methods for predicting the translocon-mediated membrane insertion free energies of protein sequences. We have developed Membrane Insertion (MINS), a novel sequence-based computational method for predicting the membrane insertion free energies of protein sequences. A benchmark test gives a correlation coefficient of 0.74 between predicted and observed free energies for 357 known cases, which corresponds to a mean unsigned error of 0.41 kcal/mol. These results are significantly better than those obtained by traditional hydropathy analysis. Moreover, the ability of MINS to reasonably predict membrane insertion free energies of protein sequences allows for effective identification of transmembrane (TM) segments. Subsequently, MINS was applied to predict the membrane insertion free energies of 316 TM segments found in known structures. An in-depth analysis of the predicted free energies reveals a number of interesting findings about the biogenesis and structural stability of HMPs. A web server for MINS is available at http://service.bioinformatik.uni-saarland.de/mins

Layer-by-layer structured polysaccharides-based multilayers on cellulose acetate membrane: Towards better hemocompatibility, antibacterial and antioxidant activities

NASA Astrophysics Data System (ADS)

Peng, Lincai; Li, Hui; Meng, Yahong

2017-04-01

The development of multifunctional cellulose acetate (CA) membranes with enhanced hemocompatibility and antibacterial and antioxidant activities is extremely important for biomedical applications. In this work, significant improvements in hemocompatibility and antibacterial and antioxidant activities of cellulose acetate (CA) membranes were achieved via layer-by-layer (LBL) deposition of chitosan (CS) and water-soluble heparin-mimicking polysaccharides (i.e., sulfated Cantharellus cibarius polysaccharides, SCP) onto their surface. The surface chemical compositions, growth manner, surface morphologies, and wetting ability of CS/SCP multilayer-modified CA membranes were characterized, respectively. The systematical evaluation of hemocompatibility revealed that CS/SCP multilayer-modified CA membranes significantly improved blood compatibility including resistance to non-specific protein adsorption, suppression of platelet adhesion and activation, prolongation of coagulation times, inhibition of complement activation, as well as reduction in blood hemolysis. Meanwhile, CS/SCP multilayer-modified CA membranes exhibited strong growth inhibition against Escherichia coli and Staphylococcus aureus, as well as high scavenging abilities against superoxide and hydroxyl radicals. In summary, the CS/SCP multilayers could confer CA membranes with integrated hemocompatibility and antibacterial and antioxidant activities, which might have great potential application in the biomedical field.

p38 Signaling and Receptor Recycling Events in a Microfluidic Endothelial Cell Adhesion Assay

PubMed Central

Vickers, Dwayne A. L.; Chory, Emma J.; Harless, Megan C.; Murthy, Shashi K.

2013-01-01

Adhesion-based microfluidic cell separation has proven to be very useful in applications ranging from cancer diagnostics to tissue engineering. This process involves functionalizing microchannel surfaces with a capture molecule. High specificity and purity capture can be achieved using this method. Despite these advances, little is known about the mechanisms that govern cell capture within these devices and their relationships to basic process parameters such as fluid shear stress and the presence of soluble factors. This work examines how the adhesion of human endothelial cells (ECs) is influenced by a soluble tetrapeptide, Arg-Glu-Asp-Val (REDV) and fluidic shear stress. The ability of these ECs to bind within microchannels coated with REDV is shown to be governed by shear- and soluble-factor mediated changes in p38 mitogen-activated protein kinase expression together with recycling of adhesion receptors from the endosome. PMID:23762436

Bioaccessibility of metals in alloys: Evaluation of three surrogate biofluids

PubMed Central

Hillwalker, Wendy E.; Anderson, Kim A.

2014-01-01

Bioaccessibility in vitro tests measure the solubility of materials in surrogate biofluids. However, the lack of uniform methods and the effects of variable test parameters on material solubility limit interpretation. One aim of this study was to measure and compare bioaccessibility of selected economically important alloys and metals in surrogate physiologically based biofluids representing oral, inhalation and dermal exposures. A second aim was to experimentally test different biofluid formulations and residence times in vitro. A third aim was evaluation of dissolution behavior of alloys with in vitro lung and dermal biofluid surrogates. This study evaluated the bioaccessibility of sixteen elements in six alloys and 3 elemental/metal powders. We found that the alloys/metals, the chemical properties of the surrogate fluid, and residence time all had major impacts on metal solubility. The large variability of bioaccessibility indicates the relevancy of assessing alloys as toxicologically distinct relative to individual metals. PMID:24212234

Cell-Based Selection Expands the Utility of DNA-Encoded Small-Molecule Library Technology to Cell Surface Drug Targets: Identification of Novel Antagonists of the NK3 Tachykinin Receptor.

PubMed

Wu, Zining; Graybill, Todd L; Zeng, Xin; Platchek, Michael; Zhang, Jean; Bodmer, Vera Q; Wisnoski, David D; Deng, Jianghe; Coppo, Frank T; Yao, Gang; Tamburino, Alex; Scavello, Genaro; Franklin, G Joseph; Mataruse, Sibongile; Bedard, Katie L; Ding, Yun; Chai, Jing; Summerfield, Jennifer; Centrella, Paolo A; Messer, Jeffrey A; Pope, Andrew J; Israel, David I

2015-12-14

DNA-encoded small-molecule library technology has recently emerged as a new paradigm for identifying ligands against drug targets. To date, this technology has been used with soluble protein targets that are produced and used in a purified state. Here, we describe a cell-based method for identifying small-molecule ligands from DNA-encoded libraries against integral membrane protein targets. We use this method to identify novel, potent, and specific inhibitors of NK3, a member of the tachykinin family of G-protein coupled receptors (GPCRs). The method is simple and broadly applicable to other GPCRs and integral membrane proteins. We have extended the application of DNA-encoded library technology to membrane-associated targets and demonstrate the feasibility of selecting DNA-tagged, small-molecule ligands from complex combinatorial libraries against targets in a heterogeneous milieu, such as the surface of a cell.

Membranes for nanometer-scale mass fast transport

DOEpatents

Bakajin, Olgica [San Leandro, CA; Holt, Jason [Berkeley, CA; Noy, Aleksandr [Belmont, CA; Park, Hyung Gyu [Oakland, CA

2011-10-18

Nanoporous membranes comprising single walled, double walled, and multiwalled carbon nanotubes embedded in a matrix material were fabricated for fluid mechanics and mass transfer studies on the nanometer scale and commercial applications. Average pore size can be 2 nm to 20 nm, or seven nm or less, or two nanometers or less. The membrane can be free of large voids spanning the membrane such that transport of material such as gas or liquid occurs exclusively through the tubes. Fast fluid, vapor, and liquid transport are observed. Versatile micromachining methods can be used for membrane fabrication. A single chip can comprise multiple membranes. These membranes are a robust platform for the study of confined molecular transport, with applications in liquid and gas separations and chemical sensing including desalination, dialysis, and fabric formation.

Parameters influencing the course of passive drug loading into lipid nanoemulsions.

PubMed

Göke, Katrin; Bunjes, Heike

2018-05-01

Passive drug loading can be used to effectively identify suitable colloidal lipid carrier systems for poorly water-soluble drugs. This method comprises incubation of preformed carrier systems with drug powder and subsequent determination of the resulting drug load of the carrier particles. Until now, the passive loading mechanism is unknown, which complicates reliable routine use. In this work, the influence of drug characteristics on the course of passive loading was investigated systematically varying drug surface area and drug solubility. Fenofibrate and flufenamic acid were used as model drugs; the carrier system was a trimyristin nanodispersion. Loading progress was analyzed by UV spectroscopy or by a novel method based on differential scanning calorimetry. While increasing drug solubility by micelle incorporation did not speed up passive loading, a large drug surface area and high water solubility were key parameters for fast loading. Since both factors are crucial in drug dissolution as described by the Noyes-Whitney equation, these findings point to a dissolution-diffusion-based passive loading mechanism. Accordingly, passive loading also occurred when drug and carrier particles were separated by a dialysis membrane. Knowledge of the loading mechanism allows optimizing the conditions for future passive loading studies and assessing the limitations of the method. Copyright © 2017 Elsevier B.V. All rights reserved.

Design of Fusion Proteins for Efficient and Soluble Production of Immunogenic Ebola Virus Glycoprotein in Escherichia coli.

PubMed

Ji, Yang; Lu, Yuan; Yan, Yishu; Liu, Xinxin; Su, Nan; Zhang, Chong; Bi, Shengli; Xing, Xin-Hui

2018-03-03

The Ebola hemorrhagic fever caused by Ebola virus is an extremely dangerous disease, and effective therapeutic agents are still lacking. Platforms for the efficient production of vaccines are crucial to ensure quick response against an Ebola virus outbreak. Ebola virus glycoprotein (EbolaGP) on the virion surface is responsible for membrane binding and virus entry, thus becoming the key target for vaccine development. However, heterologous expression of this protein still faces engineering challenges such as low production levels and insoluble aggregation. Here, the authors design and compare various fusion strategies, attaching great importance to the solubility-enhancing effect, and tag removal process. It is found that a C-terminal intein-based tag greatly enhances the solubility of EbolaGP and allows one-step chromatographic purification of the untagged EbolaGP through thiol-catalyzed self-cleavage. The purified untagged EbolaGP alone or with Freund's adjuvant are highly immunogenic, as confirmed in a mouse model. Consequently, the present study puts forward a new strategy for the efficient and soluble expression of untagged immunogenic EbolaGP. The intein-based protein fusion approach may be of importance for the large-scale production of Ebola virus subunit vaccine. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Soluble and Membrane-Bound β-Glucosidases Are Involved in Trimming the Xyloglucan Backbone.

PubMed

Sampedro, Javier; Valdivia, Elene R; Fraga, Patricia; Iglesias, Natalia; Revilla, Gloria; Zarra, Ignacio

2017-02-01

In many flowering plants, xyloglucan is a major component of primary cell walls, where it plays an important role in growth regulation. Xyloglucan can be degraded by a suite of exoglycosidases that remove specific sugars. In this work, we show that the xyloglucan backbone, formed by (1→4)-linked β-d-glucopyranosyl residues, can be attacked by two different Arabidopsis (Arabidopsis thaliana) β-glucosidases from glycoside hydrolase family 3. While BGLC1 (At5g20950; for β-glucosidase active against xyloglucan 1) is responsible for all or most of the soluble activity, BGLC3 (At5g04885) is usually a membrane-anchored protein. Mutations in these two genes, whether on their own or combined with mutations in other exoglycosidase genes, resulted in the accumulation of partially digested xyloglucan subunits, such as GXXG, GXLG, or GXFG. While a mutation in BGLC1 had significant effects on its own, lack of BGLC3 had only minor effects. On the other hand, double bglc1 bglc3 mutants revealed a synergistic interaction that supports a role for membrane-bound BGLC3 in xyloglucan metabolism. In addition, bglc1 bglc3 was complemented by overexpression of either BGLC1 or BGLC3 In overexpression lines, BGLC3 activity was concentrated in a microsome-enriched fraction but also was present in soluble form. Finally, both genes were generally expressed in the same cell types, although, in some cases, BGLC3 was expressed at earlier stages than BGLC1 We propose that functional specialization could explain the separate localization of both enzymes, as a membrane-bound β-glucosidase could specifically digest soluble xyloglucan without affecting the wall-bound polymer. © 2017 American Society of Plant Biologists. All Rights Reserved.

Pathways of fluid transport and reabsorption across the peritoneal membrane.

PubMed

Asghar, R B; Davies, S J

2008-05-01

The three-pore model of peritoneal fluid transport predicts that once the osmotic gradient has dissipated, fluid reabsorption will be due to a combination of small-pore reabsorption driven by the intravascular oncotic pressure, and an underlying disappearance of fluid from the cavity by lymphatic drainage. Our study measured fluid transport by these pathways in the presence and absence of an osmotic gradient. Paired hypertonic and standard glucose-dwell studies were performed using radio-iodinated serum albumin as an intraperitoneal volume marker and changes in intraperitoneal sodium mass to determine small-pore versus transcellular fluid transport. Disappearance of iodinated albumin was considered to indicate lymphatic drainage. Variability in transcellular ultrafiltration was largely explained by the rate of small-solute transport across the membrane. In the absence of an osmotic gradient, fluid reabsorption occurred via the small-pore pathway, the rate being proportional to the small-solute transport characteristics of the membrane. In most cases, fluid removal from the peritoneal cavity by this pathway was faster than by lymphatic drainage. Our study shows that the three-pore model describes the pathways of peritoneal fluid transport well. In the presence of high solute transport, poor transcellular ultrafiltration was due to loss of the osmotic gradient and an enhanced small-pore reabsorption rate after this gradient dissipated.

High levels of the soluble form of CD30 molecule in rheumatoid arthritis (RA) are expression of CD30+ T cell involvement in the inflamed joints.

PubMed Central

Gerli, R; Muscat, C; Bistoni, O; Falini, B; Tomassini, C; Agea, E; Tognellini, R; Biagini, P; Bertotto, A

1995-01-01

The CD30 is a surface molecule expressed by Th2-type lymphokine-producing T cells upon activation. CD30-expressing activated T cells release a soluble form of the molecule, which can be detectable both in vitro and in vivo. In the present study, high levels of soluble CD30 were found in peripheral blood and synovial fluid from patients with RA. However, CD30+ CD3+ cells, either CD4+ or CD8+, were significantly present in synovial fluid, but not in peripheral blood, of RA patients. Serum values of soluble CD30 were higher in active than inactive RA patients and directly correlated with rheumatoid factor serum titres. These data strongly support an involvement of CD30+ T cells in the immune processes of rheumatoid synovitis, and may suggest a relationship between Th2-type cytokine-secreting T cells and the pathological response in RA. PMID:8536371

A novel method for high-pressure annealing experiments in a water-rich environment: hydrogen solubility and speciation in natural, gem-quality diopside

NASA Astrophysics Data System (ADS)

Bromiley, G. D.; Keppler, H.; Bromiley, F. A.; Jacobsen, S. D.

2003-04-01

Previous experimental invesitgations on the incorporation of structurally-bound hydrogen in nominally anhydrous minerals have either involved synthesis experiments or annealing of natural samples under hydrothermal conditions. For investigation of hydrogen incorporation using FTIR, large, good quality crystals are required. Because of experimental difficulties, synthesis experiments are limited to the investigation of end-member systems. Annealing experiments may be used to investigate chemically more complex systems. However, in previous investigations problems have arisen due to reaction of samples with chemical buffers and fluids at elevated pressures and temperatures, and run times have been limited to less than 48 hours, raising questions regarding attainment of equilbrium. In the present study, a novel method for conducting long duration (100 s of hours) annealing experiments to investigate hydrogen incorporation in samples at high-pressure has been developed. The method relies on the use of a semi-permeable platinum membrane, which protects the sample during the experiment. Samples, cut into 1×2×3 mm blocks, are surrounded by a thin platinum jacket, which is "shrink-wrapped" around the samples. The samples are then loaded into larger Pt10%Rh capsules with a buffer mixture of the same composition as the Cr-diopside, a large amount of excess water, excess silica and a Ni-NiO buffer to control oxygen fugacity. At elevated pressures and temperatures, hydrogen can diffuse freely through the platinum membrane, but the samples are protected from reaction with the surrounding buffer material and fluid. Capsules are loaded into a specially designed low-friction NaCl cells for use in piston-cylinder apparatus. Samples are recovered completely intact and crack-free. Several experiments have been performed at 1.5 GPa, with increasing run duration, to demonstrate the attainment of equilibrium hydrogen contents in the sample. Experiments have been performed at pressures from 0.5 to 4.0 GPa, 1000 to 1100^oC, with run times of several hundred hours. The effects of increasing pressure and oxygen fugacity on hydeogen solubility, and hydrogen speciation in the diopside have been fully characterised using polarised FTIR spectoscopy. The high-quality of recovered samples means that further investigations on the effects of increasing water contents on other physical properties in the samples should be possible.

Anesthetic diffusion through lipid membranes depends on the protonation rate.

PubMed

Pérez-Isidoro, Rosendo; Sierra-Valdez, F J; Ruiz-Suárez, J C

2014-12-18

Hundreds of substances possess anesthetic action. However, despite decades of research and tests, a golden rule is required to reconcile the diverse hypothesis behind anesthesia. What makes an anesthetic to be local or general in the first place? The specific targets on proteins, the solubility in lipids, the diffusivity, potency, action time? Here we show that there could be a new player equally or even more important to disentangle the riddle: the protonation rate. Indeed, such rate modulates the diffusion speed of anesthetics into lipid membranes; low protonation rates enhance the diffusion for local anesthetics while high ones reduce it. We show also that there is a pH and membrane phase dependence on the local anesthetic diffusion across multiple lipid bilayers. Based on our findings we incorporate a new clue that may advance our understanding of the anesthetic phenomenon.

Comparison of the physicochemical properties of the N-(2-hydroxyethyl) pyrrolidine, diethylamine and sodium salt forms of diclofenac.

PubMed

O'Connor, K M; Corrigan, O I

2001-07-17

Non steroidal anti-inflammatory agents (NSAIDs) such as diclofenac have very low aqueous solubilities and consequently salt formation may be used to enhance solubility and dissolution rate. In this study, we examined the physicochemical properties of three diclofenac salts, diclofenac sodium (DNa), diclofenac N-(2-hydroxyethyl)pyrrolidine (DHEP) and diclofenac diethylamine (DDEA), and their different solid state forms to determine the influence of salt form on solubility, dissolution rate and membrane transport. The equilibrium solubility of DDEA at 25 degrees C was determined as 33 mM, lower than the solubilities of DHEP (273 mM) and DNa (66 mM) previously reported (Ledwidge and Corrigan, 1998). In addition to the dihydrate form of DHEP previously characterised, monohydrate forms of DHEP and DDEA were identified. Intrinsic dissolution rate studies were used to determine the solubility ratios of the hydrated and anhydrous forms. The monohydrate form of DHEP was found to be 1.8 times less soluble than the anhydrate, whereas DDEA anhydrate was approximately 1.7 times as soluble as the monohydrate form. On investigation of the pH-solubility profile (25 degrees C) of DDEA, appreciable supersaturation (76 mM) relative to the theoretical profile, was detected at the pH(max). This contrasts with values of >800 and 67 mM for DHEP and DNa, respectively. The transport of salt solutions through a porous membrane (Visking) was investigated. A linear relationship between concentration (mM) and rate of transport (mmol/h) was established for DNa and DHEP solutions. The mass transfer coefficient determined for DHEP was lower than that for the other two salts. Nevertheless, the maximum transport rate obtained for DHEP is almost six times higher than that obtained for DDEA.

Synthesis of kenaf cellulose carbamate using microwave irradiation for preparation of cellulose membrane.

PubMed

Gan, Sinyee; Zakaria, Sarani; Chia, Chin Hua; Kaco, Hatika; Padzil, Farah Nadia Mohammad

2014-06-15

Cellulose carbamate (CCs) was produced from kenaf core pulp (KCP) using microwave reactor-assisted method. The effects of urea concentration and reaction time on the formation of nitrogen content in CCs were investigated. The CCs' solubility in LiOH/urea system was determined and its membranes were characterized. As the urea content and reaction time increased, the nitrogen content form in CCs increased which enhanced the CCs' solubility. The formation of CCs was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nitrogen content analysis. The CCs' morphology was examined using Scanning electron microscopy (SEM). The cellulose II and crystallinity index of the membranes were confirmed by X-ray diffraction (XRD). The pore size of the membrane displayed upward trend with respect to the urea content observed under Field emission scanning electron microscope (FESEM). This investigation provides a simple and efficient procedure of CCs determination which is useful in producing environmental friendly regenerated CCs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Conformational alteration in alpha-toxin from Staphylococcus aureus concomitant with the transformation of the water-soluble monomer to the membrane oligomer.

PubMed

Ikigai, H; Nakae, T

1985-07-16

The membrane-damaging alpha-toxin aggregate of Staphylococcus aureus was characterized physicochemically. The aggregate weight of the toxin formed by various methods appeared to be 6 times higher than the molecular weight of the monomer as determined by the laser light scattering technique, suggesting the presence of a hexamer in the membrane. The aggregates fluoresced 20 to 50% more than the monomer at 336 nm. Circular dichroism measurements revealed that both the monomer and the oligomer showed essentially beta-sheet structure with the maximum ellipticity about -8,400 deg.cm2.dmol-1 at 215 nm. Circular dichroism spectrum of the oligomers showed ellipticity difference of -6,600, -44 and +84 deg.cm2.dmol-1, at 200, 250 and 280 nm, respectively, compared with the monomer. All these results suggest that the conformational change in the toxin molecule occurs concomitant with the transformation of the water-soluble monomer to the membrane-embedded hexamer.

Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products.

PubMed

Duan, Liang; Tian, Zhiyong; Song, Yonghui; Jiang, Wei; Tian, Yuan; Li, Shan

2015-01-01

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (<1 kDa) and fewer high-MW compounds (>100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.

The characteristics of extracellular polymeric substances and soluble microbial products in moving bed biofilm reactor-membrane bioreactor.

PubMed

Duan, Liang; Jiang, Wei; Song, Yonghui; Xia, Siqing; Hermanowicz, Slawomir W

2013-11-01

The characteristics of extracellular polymeric substances (EPS) and soluble microbial products (SMP) in conventional membrane bioreactor (MBR) and in moving bed biofilm reactor-membrane bioreactors (MBBR-MBR) were investigated in long-term (170 days) experiments. The results showed that all reactors had high removal efficiency of ammonium and COD, despite very different fouling conditions. The MBBR-MBR with media fill ratio of 26.7% had much lower total membrane resistance and no obvious fouling were detected during the whole operation. In contrast, MBR and MBBR-MBR with lower and higher media fill experienced more significant fouling. Low fouling at optimum fill ratio may be due to the higher percentage of small molecular size (<1 kDa) and lower percentage of large molecular size (>100 kDa) of EPS and SMP in the reactor. The composition of EPS and SMP affected fouling due to different O-H bonds in hydroxyl functional groups, and less polysaccharides and lipids. Copyright © 2013 Elsevier Ltd. All rights reserved.

Up-Regulation of Soluble Axl and Mer Receptor Tyrosine Kinases Negatively Correlates with Gas6 in Established Multiple Sclerosis Lesions

PubMed Central

Weinger, Jason G.; Omari, Kakuri M.; Marsden, Kurt; Raine, Cedric S.; Shafit-Zagardo, Bridget

2009-01-01

Multiple sclerosis is a disease that is characterized by inflammation, demyelination, and axonal damage; it ultimately forms gliotic scars and lesions that severely compromise the function of the central nervous system. Evidence has shown previously that altered growth factor receptor signaling contributes to lesion formation, impedes recovery, and plays a role in disease progression. Growth arrest-specific protein 6 (Gas6), the ligand for the TAM receptor tyrosine kinase family, consisting of Tyro3, Axl, and Mer, is important for cell growth, survival, and clearance of debris. In this study, we show that levels of membrane-bound Mer (205 kd), soluble Mer (∼150 kd), and soluble Axl (80 kd) were all significantly elevated in homogenates from established multiple sclerosis lesions comprised of both chronic active and chronic silent lesions. Whereas in normal tissue Gas6 positively correlated with soluble Axl and Mer, there was a negative correlation between Gas6 and soluble Axl and Mer in established multiple sclerosis lesions. In addition, increased levels of soluble Axl and Mer were associated with increased levels of mature ADAM17, mature ADAM10, and Furin, proteins that are associated with Axl and Mer solubilization. Soluble Axl and Mer are both known to act as decoy receptors and block Gas6 binding to membrane-bound receptors. These data suggest that in multiple sclerosis lesions, dysregulation of protective Gas6 receptor signaling may prolong lesion activity. PMID:19541935

Reinvestigation of the Steady-State Kinetics and Physiological Function of the Soluble NiFe-Hydrogenase I of Pyrococcus furiosus▿

PubMed Central

van Haaster, Daan J.; Silva, Pedro J.; Hagedoorn, Peter-Leon; Jongejan, Jaap A.; Hagen, Wilfred R.

2008-01-01

Pyrococcus furiosus has two types of NiFe-hydrogenases: a heterotetrameric soluble hydrogenase and a multimeric transmembrane hydrogenase. Originally, the soluble hydrogenase was proposed to be a new type of H2 evolution hydrogenase, because, in contrast to all of the then known NiFe-hydrogenases, the hydrogen production activity at 80°C was found to be higher than the hydrogen consumption activity and CO inhibition appeared to be absent. NADPH was proposed to be the electron donor. Later, it was found that the membrane-bound hydrogenase exhibits very high hydrogen production activity sufficient to explain cellular H2 production levels, and this seems to eliminate the need for a soluble hydrogen production activity and therefore leave the soluble hydrogenase without a physiological function. Therefore, the steady-state kinetics of the soluble hydrogenase were reinvestigated. In contrast to previous reports, a low Km for H2 (∼20 μM) was found, which suggests a relatively high affinity for hydrogen. Also, the hydrogen consumption activity was 1 order of magnitude higher than the hydrogen production activity, and CO inhibition was significant (50% inhibition with 20 μM dissolved CO). Since the Km for NADP+ is ∼37 μM, we concluded that the soluble hydrogenase from P. furiosus is likely to function in the regeneration of NADPH and thus reuses the hydrogen produced by the membrane-bound hydrogenase in proton respiration. PMID:18156274

Embedding objects during 3D printing to add new functionalities.

PubMed

Yuen, Po Ki

2016-07-01

A novel method for integrating and embedding objects to add new functionalities during 3D printing based on fused deposition modeling (FDM) (also known as fused filament fabrication or molten polymer deposition) is presented. Unlike typical 3D printing, FDM-based 3D printing could allow objects to be integrated and embedded during 3D printing and the FDM-based 3D printed devices do not typically require any post-processing and finishing. Thus, various fluidic devices with integrated glass cover slips or polystyrene films with and without an embedded porous membrane, and optical devices with embedded Corning(®) Fibrance™ Light-Diffusing Fiber were 3D printed to demonstrate the versatility of the FDM-based 3D printing and embedding method. Fluid perfusion flow experiments with a blue colored food dye solution were used to visually confirm fluid flow and/or fluid perfusion through the embedded porous membrane in the 3D printed fluidic devices. Similar to typical 3D printed devices, FDM-based 3D printed devices are translucent at best unless post-polishing is performed and optical transparency is highly desirable in any fluidic devices; integrated glass cover slips or polystyrene films would provide a perfect optical transparent window for observation and visualization. In addition, they also provide a compatible flat smooth surface for biological or biomolecular applications. The 3D printed fluidic devices with an embedded porous membrane are applicable to biological or chemical applications such as continuous perfusion cell culture or biocatalytic synthesis but without the need for any post-device assembly and finishing. The 3D printed devices with embedded Corning(®) Fibrance™ Light-Diffusing Fiber would have applications in display, illumination, or optical applications. Furthermore, the FDM-based 3D printing and embedding method could also be utilized to print casting molds with an integrated glass bottom for polydimethylsiloxane (PDMS) device replication. These 3D printed glass bottom casting molds would result in PDMS replicas with a flat smooth bottom surface for better bonding and adhesion.

Aqueous Silicate Polymers: An Alternative to `Supercritical' Fluids as Transport Agents in Subduction Zones

NASA Astrophysics Data System (ADS)

Mannig, C. E.

2005-12-01

The chemistry of subduction-zone fluids is complicated by melt-vapor miscibility and the existence of critical end-points in rock-H2O systems. It is commonly assumed that fluids in subduction zones attain properties intermediate in composition between hydrous silicate liquid and H2O, and that such fluids possess enhanced material transport capabilities. However, the relevance of supercritical, intermediate fluids to subduction zones presents four problems. (1) Albite-H2O is typically used as an analogue system, but the favorable position of its critical curve is not representative; critical curves for polymineralic subduction-zone lithologies lie at substantially higher P. (2) Even if albite-H2O is relevant, jadeite may interfere because of its different solubility and the positive clapeyron slope of its solidus, which points to liquid-structure changes that could cause reappearance of the liquid+vapor field. (3) Critical curves are features of very H2O-rich compositions; low-porosity, H2O-poor natural systems will coexist with intermediate fluids only over a narrow PT interval. (4) Intermediate fluids are expected only over short length scales because their migration will likely result in compositional shifts via reaction and mineral precipitation in the mantle wedge. Although supercritical, intermediate fluids are probably relatively unimportant in subduction zones, they reflect a chemical process that may hold the key to understanding high- P mass transfer. Miscibility in melt-vapor systems is a consequence of polymerization of dissolved components, primarily Si ± Al, Na and Ca. This behavior yields, e.g., aqueous Si-Si, Si-Al, Si-Na-Al, and Si-Ca oxide dimers and other multimers of varying stoichiometry (silicate polymers), even in subcritical, dilute, H2O-rich vapor. Silicate polymers in subcritical aqueous solutions have been inferred from high- P mineral-solubility experiments. The abundance of these species at high P shows that the chemistry of aqueous fluids in subduction-zones differs fundamentally from the more familiar ionic solutions of the upper crust. This has important consequences for minor element transport. Measurements of Fe, phosphorous and Ti solubility reveal that dissolved concentrations rise with increased aqueous albite content at fixed P and T, with maximum enhancements exceeding 10X at melt saturation. Subcritical silicate polymerization thus permits transport of low solubility components via their substitution into sites on aqueous multimers constructed of "polymer formers" such as Na, Al, and Si, even in dilute solutions. The partitioning of elements between the bulk fluid, the polymer network, and the rock matrix likely controls the overall compositional evolution of subduction-zone fluids. Because they form over a wider PT and bulk X range, subcritical silicate polymers in dilute solutions are likely responsible for more mass transfer in subduction zones than intermediate, supercritical fluids.

Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria1[OPEN

PubMed Central

Lea-Smith, David J.; Nürnberg, Dennis J.; Baers, Laura L.; Davey, Matthew P.; Parolini, Lucia; Huber, Roland G.; Cotton, Charles A. R.; Mastroianni, Giulia; Bombelli, Paolo; Ungerer, Petra; Stevens, Tim J.; Howe, Christopher J.

2016-01-01

Cyanobacteria are intricately organized, incorporating an array of internal thylakoid membranes, the site of photosynthesis, into cells no larger than other bacteria. They also synthesize C15-C19 alkanes and alkenes, which results in substantial production of hydrocarbons in the environment. All sequenced cyanobacteria encode hydrocarbon biosynthesis pathways, suggesting an important, undefined physiological role for these compounds. Here, we demonstrate that hydrocarbon-deficient mutants of Synechococcus sp. PCC 7002 and Synechocystis sp. PCC 6803 exhibit significant phenotypic differences from wild type, including enlarged cell size, reduced growth, and increased division defects. Photosynthetic rates were similar between strains, although a minor reduction in energy transfer between the soluble light harvesting phycobilisome complex and membrane-bound photosystems was observed. Hydrocarbons were shown to accumulate in thylakoid and cytoplasmic membranes. Modeling of membranes suggests these compounds aggregate in the center of the lipid bilayer, potentially promoting membrane flexibility and facilitating curvature. In vivo measurements confirmed that Synechococcus sp. PCC 7002 mutants lacking hydrocarbons exhibit reduced thylakoid membrane curvature compared to wild type. We propose that hydrocarbons may have a role in inducing the flexibility in membranes required for optimal cell division, size, and growth, and efficient association of soluble and membrane bound proteins. The recent identification of C15-C17 alkanes and alkenes in microalgal species suggests hydrocarbons may serve a similar function in a broad range of photosynthetic organisms. PMID:27707888

Membrane-based actuation for high-speed single molecule force spectroscopy studies using AFM.

PubMed

Sarangapani, Krishna; Torun, Hamdi; Finkler, Ofer; Zhu, Cheng; Degertekin, Levent

2010-07-01

Atomic force microscopy (AFM)-based dynamic force spectroscopy of single molecular interactions involves characterizing unbinding/unfolding force distributions over a range of pulling speeds. Owing to their size and stiffness, AFM cantilevers are adversely affected by hydrodynamic forces, especially at pulling speeds >10 microm/s, when the viscous drag becomes comparable to the unbinding/unfolding forces. To circumvent these adverse effects, we have fabricated polymer-based membranes capable of actuating commercial AFM cantilevers at speeds >or=100 microm/s with minimal viscous drag effects. We have used FLUENT, a computational fluid dynamics (CFD) software, to simulate high-speed pulling and fast actuation of AFM cantilevers and membranes in different experimental configurations. The simulation results support the experimental findings on a variety of commercial AFM cantilevers and predict significant reduction in drag forces when membrane actuators are used. Unbinding force experiments involving human antibodies using these membranes demonstrate that it is possible to achieve bond loading rates >or=10(6) pN/s, an order of magnitude greater than that reported with commercial AFM cantilevers and systems.

Fluid electrodes for submersible robotics based on dielectric elastomer actuators

NASA Astrophysics Data System (ADS)

Christianson, Caleb; Goldberg, Nathaniel; Cai, Shengqiang; Tolley, Michael T.

2017-04-01

Recently, dielectric elastomer actuators (DEAs) have gathered interest for soft robotics due to their low cost, light weight, large strain, low power consumption, and high energy density. However, developing reliable, compliant electrodes for DEAs remains an ongoing challenge due to issues with fabrication, uniformity of the conductive layer, and mechanical stiffening of the actuators caused by conductive materials with large Young's moduli. In this work, we present a method for preparing, patterning, and utilizing conductive fluid electrodes. Further, when we submerse the DEAs in a bath containing a conductive fluid connected to ground, the bath serves as a second electrode, obviating the need for depositing a conductive layer to serve as either of the electrodes required of most DEAs. When we apply a positive electrical potential to the conductive fluid in the actuator with respect to ground, the electric field across the dielectric membrane causes charge carriers in the solution to apply an electrostatic force on the membrane, which compresses the membrane and causes the actuator to deform. We have used this process to develop a tethered submersible robot that can swim in a tank of saltwater at a maximum measured speed of 9.2 mm/s. Since saltwater serves as the electrode, we overcome buoyancy issues that may be a challenge for pneumatically actuated soft robots and traditional, rigid robotics. This research opens the door to low-power underwater robots for search and rescue and environmental monitoring applications.

Jobelyn® exhibited anti-inflammatory, antioxidant, and membrane-stabilizing activities in experimental models.

PubMed

Umukoro, Solomon; Oluwole, Oluwafemi Gabriel; Eduviere, Anthony T; Adrian, Omogbiya Itievere; Ajayi, Abayomi M

2015-09-01

Jobelyn® (JB) is an African sorghum-based food supplement claimed to be efficacious for the treatment of rheumatoid arthritis (RA). Although in vitro studies confirmed its anti-inflammatory property, no study had shown the effect of JB using in vivo animal models of inflammation. Thus, its effects on acute and chronic inflammation in rats were evaluated in this study. Its effect on rat red blood cell (RBC) lysis was also assessed. Acute inflammation was induced with intraplanter injection of carrageenan and increase in rat paw volume was measured using plethysmometer. The volume of fluid exudates, number of leukocytes, concentrations of malondialdehyde (MDA), and glutathione (GSH) in the fluid were measured on day 5 after induction of chronic inflammation with carrageenan in the granuloma air pouch model. RBC lysis induced by hypotonic medium as determined by release of hemoglobin was measured spectrophotometerically. JB (50-200 mg/kg) given orally produced a significant inhibition of acute inflammation induced by carrageenan in rats. It reduced the volume and number of leukocytes in inflammatory fluid in the granuloma air pouch model of chronic inflammation. It further decreased the levels of MDA in the fluid suggesting antioxidant property. JB elevated the concentrations of GSH in inflammatory exudates indicating free radical scavenging activity. It also significantly inhibited RBC lysis caused by hypotonic medium, suggesting membrane-stabilizing property. JB has in vivo anti-inflammatory activity, which may be related to its antioxidant and membrane-stabilizing properties, supporting its use for the treatment of arthritic disorder.

Recent progress on lipid lateral heterogeneity in plasma membranes: from rafts to submicrometric domains

PubMed Central

Carquin, Mélanie; D'Auria, Ludovic; Pollet, Hélène; Bongarzone, Ernesto R.; Tyteca, Donatienne

2016-01-01

The concept of transient nanometric domains known as lipid rafts has brought interest to reassess the validity of the Singer-Nicholson model of a fluid bilayer for cell membranes. However, this new view is still insufficient to explain the cellular control of surface lipid diversity or membrane deformability. During the past decade, the hypothesis that some lipids form large (submicrometric/mesoscale vs nanometric rafts) and stable (> min vs sec) membrane domains has emerged, largely based on indirect methods. Morphological evidence for stable submicrometric lipid domains, well-accepted for artificial and highly specialized biological membranes, was further reported for a variety of living cells from prokaryotes to yeast and mammalian cells. However, results remained questioned based on limitations of available fluorescent tools, use of poor lipid fixatives, and imaging artifacts due to non-resolved membrane projections. In this review, we will discuss recent evidence generated using powerful and innovative approaches such as lipid-specific toxin fragments that support the existence of submicrometric domains. We will integrate documented mechanisms involved in the formation and maintenance of these domains, and provide a perspective on their relevance on membrane deformability and regulation of membrane protein distribution. PMID:26738447

In-Situ pH Measurements in Mid-Ocean Ridge Hydrothermal Vent Fluids: Constraints on Subseafloor Alteration Processes at Crustal Depths

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Ding, K.; Seyfried, W. E.

2013-12-01

Developments in electrochemistry and material science have facilitated the construction of ceramic (YSZ) based chemical sensor systems that can be used to measure and monitor pH and redox in aqueous fluids at elevated temperatures and pressures. In recent years, these sensor systems have been deployed to acquire real-time and time series in-situ data for high-temperature hydrothermal vent fluids at the Main Endeavour Field (Juan de Fuca Ridge), 9oN (East Pacific Rise), and at the ultramafic-hosted Rainbow field (36oN, Mid-Atlantic Ridge). Here we review in-situ pH data measured at these sites and apply these data to estimate the pH of fluids ascending to the seafloor from hydrothermal alteration zones deeper in the crust. In general, in-situ pH measured at virtually all vent sites is well in excess of that measured shipboard owing to the effects of temperature on the distribution of aqueous species and the solubility of metal sulfides, especially Cu and Zn, originally dissolved in the vent fluids. In situ pH measurements determined at MEF (Sully vent) and EPR 9oN (P-vent) in 2005 and 2008 were 4.4 ×0.02 and 5.05×0.05, respectively. The temperature and pressure (seafloor) of the vent fluids at each of the respective sites were 356oC and 220 bar, and 380oC and 250 bar. Plotting these data with respect to fluid density reveals that the in-situ pH of each vent fluid is approximately 1.5 pH units below neutrality. The density-pH (in-situ) correlation, however, is important because it provides a means from which the vent fluids were derived. Using dissolved silica and chloride from fluid samples at the MEF (Sully) suggest T/P conditions of approximately 435oC, 380 bar, based on quartz-fluid and NaCl-H2O systems. At the fluid density calculated for these conditions, pH (in-situ) is predicted to be ~6.2. Attempts are presently underway to assess the effect of the calculated pH on metal sulfide and silicate (e.g., plagioclase, chlorite) solubility in comparison with constraints imposed by the full range of chemical components in the vent fluids sampled and analyzed in association with pH (in-situ) measurements. Since pH is a master variable in all geochemical systems, the novel approach proposed here may provide new insight on hydrothermal alteration processes at conditions difficult or impossible to assess by more traditional means, ultimately influencing hydrothermal fluid fluxes.