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Sample records for single isolated pores

  1. Lattice density functional theory investigation of pore shape effects. I. Adsorption in single nonperiodic pores.

    Science.gov (United States)

    Malanoski, A P; van Swol, Frank

    2002-10-01

    A fully explicit in three dimensions lattice density functional theory is used to investigate adsorption in single nonperiodic pores. The effect of varying pore shape from the slits and cylinders that are normally simulated was our primary interest. A secondary concern was the results for pores with very large diameters. The shapes investigated were square pores with or without surface roughness, cylinders, right triangle pores, and trapezoidal pores. It was found that pores with very similar shape factors gave similar results but that the introduction of acute angled corners or very large side ratio lengths in rectangular pores gave results that were significantly different. Further, a rectangular pore going towards the limit of infinite side ratio does not approach the results of a slit pore. In all of these cases, the importance of features that are present for only a small portion of the pore is demonstrated.

  2. Diode-like properties of single- and multi-pore asymmetric track membranes

    Science.gov (United States)

    Zielinska, K.; Gapeeva, A. R.; Orelovich, O. L.; Apel, P. Yu.

    2014-05-01

    In this work, we investigated the ionic transport properties of asymmetric polyethylene terephthalate (PET) track membranes with the thickness of 5 μm. The samples containing single pores and arrays of many pores were fabricated by irradiation with accelerated ions and subsequent physicochemical treatment. The method of etching in the presence of a surface-active agent was used to prepare the pores with highly-tapered tip. The transport of monovalent inorganic ions through the nano-scale holes was studied in a conductivity cell. The effective pore radii, electrical conductance and rectification ratios of pores were measured. The geometric characteristics of nanopores were investigated using FESEM.

  3. Blocking of Single α-Hemolysin Pore by Rhodamine Derivatives.

    Science.gov (United States)

    Rokitskaya, Tatyana I; Nazarov, Pavel A; Golovin, Andrey V; Antonenko, Yuri N

    2017-06-06

    Measurements of ion conductance through α-hemolysin pore in a bilayer lipid membrane revealed blocking of the ion channel by a series of rhodamine 19 and rhodamine B esters. The longest dwell closed time of the blocking was observed with rhodamine 19 butyl ester (C4R1), whereas the octyl ester (C8R1) was of poor effect. Voltage asymmetry in the binding kinetics indicated that rhodamine derivatives bound to the stem part of the aqueous pore lumen. The binding frequency was proportional to a quadratic function of rhodamine concentrations, thereby showing that the dominant binding species were rhodamine dimers. Two levels of the pore conductance and two dwell closed times of the pore were found. The dwell closed times lengthened as the voltage increased, suggesting impermeability of the channel for the ligands. Molecular docking analysis revealed two distinct binding sites within the lumen of the stem of the α-hemolysin pore for the C4R1 dimer, but only one binding site for the C8R1 dimer. The blocking of the α-hemolysin nanopore by rhodamines could be utilized in DNA sequencing as additional optical sensing owing to bright fluorescence of rhodamines if used for DNA labeling. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  4. Single Cell Isolation and Analysis

    Directory of Open Access Journals (Sweden)

    Ping Hu

    2016-10-01

    Full Text Available Increasing evidence shows that the heterogeneity of individual cells within a genetically identical population can be critical to their peculiar function and fate. Conventional cell based assays mainly analysis the average responses from a population cells, while the difference within individual cells may often be masked. The cell size, RNA transcripts and protein expression level are quite different within individual cells and these variations are key point to answer the problems in cancer, neurobiology, stem cell biology, immunology and developmental biology. To better understand the cell-to-cell variations, the single cell analysis can provide much more detailed information which may be helpful for therapeutic decisions in an increasingly personalized medicine. In this review, we will focus on the recent development in single cell analysis, including methods used in single cell isolation, analysis and some application examples. The review provides the historical background to single cell analysis, discusses limitations, and current and future possibilities in this exciting field of research.

  5. Invariance of single-file water mobility in gramicidin-like peptidic pores as function of pore length.

    Science.gov (United States)

    Portella, Guillem; Pohl, Peter; de Groot, Bert L

    2007-06-01

    We investigated the structural and energetic determinants underlying water permeation through peptidic nanopores, motivated by recent experimental findings that indicate that water mobility in single-file water channels displays nonlinear length dependence. To address the molecular mechanism determining the observed length dependence, we studied water permeability in a series of designed gramicidin-like channels of different length using atomistic molecular dynamics simulations. We found that within the studied range of length the osmotic water permeability is independent of pore length. This result is at variance with textbook models, where the relationship is assumed to be linear. Energetic analysis shows that loss of solvation rather than specific water binding sites in the pore form the main energetic barrier for water permeation, consistent with our dynamics results. For this situation, we propose a modified expression for osmotic permeability that fully takes into account water motion collectivity and does not depend on the pore length. Different schematic barrier profiles are discussed that explain both experimental and computational interpretations, and we propose a set of experiments aimed at validation of the presented results. Implications of the results for the design of peptidic channels with desired permeation characteristics are discussed.

  6. Electrical trapping mechanism of single-microparticles in a pore sensor

    Directory of Open Access Journals (Sweden)

    Akihide Arima

    2016-11-01

    Full Text Available Nanopore sensing via resistive pulse technique are utilized as a potent tool to characterize physical and chemical property of single –molecules and –particles. In this article, we studied the influence of particle trajectory to the ionic conductance through a pore. We performed the optical/electrical simultaneous sensing of electrophoretic capture dynamics of single-particles at a pore using a microchannel/nanopore system. We detected ionic current drops synchronous to a fluorescently dyed particle being electrophoretically drawn and become immobilized at a pore in the optical imaging. We also identified anomalous trapping events wherein particles were captured at nanoscale pin-holes formed unintentionally in a SiN membrane that gave rise to relatively small current drops. This method is expected to be a useful platform for testing novel nanopore sensor design wherein current behaves in unpredictable manner.

  7. Conductometric determination of single pores in polyethyleneterephthalate irradiated by heavy ions

    International Nuclear Information System (INIS)

    Oganesyan, V.R.; Trofimov, V.V.; Doerschel, B.; Hermsdorf, D.; Vetter, J.; Danziger, M.

    2002-01-01

    Most of the previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7·10 3 ions/cm 2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20μm was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation, we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed model. Thus, the developed 'track-by-track' method can be used effectively for description of the sequential appearance of individual pores in an electrolytic etching process

  8. Conductometric Determination of Single Pores in Polyethyleneterephthalate Irradiated by Heavy Ions

    CERN Document Server

    Oganesyan, V R; Dörschel, B; Vetter, J E; Danziger, M; Hermsdorf, D

    2002-01-01

    Most of previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7\\cdot 10^{3} ions/cm^2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20 m was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed model. Thus, the de...

  9. Conductometric determination of single pores in polyethyleneterephthalate irradiated by heavy ions

    CERN Document Server

    Oganesyan, V R; Dörschel, B; Hermsdorf, D; Trofimov, V V; Vetter, J

    2002-01-01

    Most of the previous works devoted to the problem of track formation processes did not pay enough attention to direct measurement of the appearance of every individual pore in an array of many pores induced by the irradiation of polymer films with ions. Such measurements are not easy to carry out due to the extremely high electric resistance in the moment of pore opening. In this work the analysis of films irradiated with low particle fluences up to 3.7 centre dot 10 sup 3 ions/cm sup 2 is described. Polyethyleneterephthalate (PET) Hostaphan with a thickness of 20 mu m was used. The samples were irradiated with Bi ions of 11.4 MeV/amu energy. Using optimized etching conditions and computer aided data evaluation, we obtained results, which are in good agreement with theoretical predictions and model calculations. The measured increase of conductivity beginning from the breakthrough of a single track up to the next pore opening in dependence on the etching time and the number of opened pores confirm the assumed...

  10. Pore annihilation in a single-crystal nickel-base superalloy during hot isostatic pressing: Experiment and modelling

    International Nuclear Information System (INIS)

    Epishin, Alexander; Fedelich, Bernard; Link, Thomas; Feldmann, Titus; Svetlov, Igor L.

    2013-01-01

    Pore annihilation during hot isostatic pressing (HIP) was investigated in the single-crystal nickel-base superalloy CMSX-4 experimentally by interrupted HIP tests at 1288 °C/103 MPa. The kinetics of pore annihilation was determined by density measurement and quantitative metallography. Transmission electron microscopy of a HIPed specimen showed that the pores shrink via dislocation movement on octahedral glide planes. Theoretically pore closure under HIP condition was modelled by the finite element method using crystal plasticity and large strain theories. The modelling gives a similar kinetics of pore annihilation as observed experimentally, however somewhat higher annihilation rate

  11. Technologies for Single-Cell Isolation.

    Science.gov (United States)

    Gross, Andre; Schoendube, Jonas; Zimmermann, Stefan; Steeb, Maximilian; Zengerle, Roland; Koltay, Peter

    2015-07-24

    The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field.

  12. Technologies for Single-Cell Isolation

    Science.gov (United States)

    Gross, Andre; Schoendube, Jonas; Zimmermann, Stefan; Steeb, Maximilian; Zengerle, Roland; Koltay, Peter

    2015-01-01

    The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting) respectively Flow cytometry (33% usage), laser microdissection (17%), manual cell picking (17%), random seeding/dilution (15%), and microfluidics/lab-on-a-chip devices (12%) are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field. PMID:26213926

  13. Technologies for Single-Cell Isolation

    Directory of Open Access Journals (Sweden)

    Andre Gross

    2015-07-01

    Full Text Available The handling of single cells is of great importance in applications such as cell line development or single-cell analysis, e.g., for cancer research or for emerging diagnostic methods. This review provides an overview of technologies that are currently used or in development to isolate single cells for subsequent single-cell analysis. Data from a dedicated online market survey conducted to identify the most relevant technologies, presented here for the first time, shows that FACS (fluorescence activated cell sorting respectively Flow cytometry (33% usage, laser microdissection (17%, manual cell picking (17%, random seeding/dilution (15%, and microfluidics/lab-on-a-chip devices (12% are currently the most frequently used technologies. These most prominent technologies are described in detail and key performance factors are discussed. The survey data indicates a further increasing interest in single-cell isolation tools for the coming years. Additionally, a worldwide patent search was performed to screen for emerging technologies that might become relevant in the future. In total 179 patents were found, out of which 25 were evaluated by screening the title and abstract to be relevant to the field.

  14. Fabrication and Characterization of Single Phase α-Alumina Membranes with Tunable Pore Diameters

    Science.gov (United States)

    Masuda, Tatsuya; Asoh, Hidetaka; Haraguchi, Satoshi; Ono, Sachiko

    2015-01-01

    Nanoporous and single phase α-alumina membranes with pore diameters tunable over a wide range of approximately 60–350 nm were successfully fabricated by optimizing the conditions for anodizing, subsequent detachment, and heat treatment. The pore diameter increased and the cell diameter shrunk upon crystallization to α-alumina by approximately 20% and 3%, respectively, in accordance with the 23% volume shrinkage resulting from the change in density associated with the transformation from the amorphous state to α-alumina. Nevertheless, flat α-alumina membranes, each with a diameter of 25 mm and a thickness of 50 μm, were obtained without thermal deformation. The α-alumina membranes exhibited high chemical resistance in various concentrated acidic and alkaline solutions as well as when exposed to high temperature steam under pressure. The Young’s modulus and hardness of the single phase α-alumina membranes formed by heat treatment at 1250 °C were notably decreased compared to the corresponding amorphous membranes, presumably because of the nodular crystallite structure of the cell walls and the substantial increase in porosity. Furthermore, when used for filtration, the α-alumina membrane exhibited a level of flux higher than that of the commercial ceramic membrane. PMID:28788005

  15. Fabrication and Characterization of Single Phase α-Alumina Membranes with Tunable Pore Diameters

    Directory of Open Access Journals (Sweden)

    Tatsuya Masuda

    2015-03-01

    Full Text Available Nanoporous and single phase α-alumina membranes with pore diameters tunable over a wide range of approximately 60–350 nm were successfully fabricated by optimizing the conditions for anodizing, subsequent detachment, and heat treatment. The pore diameter increased and the cell diameter shrunk upon crystallization to α-alumina by approximately 20% and 3%, respectively, in accordance with the 23% volume shrinkage resulting from the change in density associated with the transformation from the amorphous state to α-alumina. Nevertheless, flat α-alumina membranes, each with a diameter of 25 mm and a thickness of 50 μm, were obtained without thermal deformation. The α-alumina membranes exhibited high chemical resistance in various concentrated acidic and alkaline solutions as well as when exposed to high temperature steam under pressure. The Young’s modulus and hardness of the single phase α-alumina membranes formed by heat treatment at 1250 °C were notably decreased compared to the corresponding amorphous membranes, presumably because of the nodular crystallite structure of the cell walls and the substantial increase in porosity. Furthermore, when used for filtration, the α-alumina membrane exhibited a level of flux higher than that of the commercial ceramic membrane.

  16. Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

    Science.gov (United States)

    Chen, Shih-Yung; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi; Wang, Yuh-Lin

    2011-09-01

    Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

  17. Morphological evolution of porous nanostructures grown from a single isolated anodic alumina nanochannel

    International Nuclear Information System (INIS)

    Chen, Shih-Yung; Wang, Yuh-Lin; Chang, Hsuan-Hao; Lai, Ming-Yu; Liu, Chih-Yi

    2011-01-01

    Porous anodic aluminum oxide (AAO) membranes have been widely used as templates for growing nanomaterials because of their ordered nanochannel arrays with high aspect ratio and uniform pore diameter. However, the intrinsic growth behavior of an individual AAO nanochannel has never been carefully studied for the lack of a means to fabricate a single isolated anodic alumina nanochannel (SIAAN). In this study, we develop a lithographic method for fabricating a SIAAN, which grows into a porous hemispherical structure with its pores exhibiting fascinating morphological evolution during anodization. We also discover that the mechanical stress affects the growth rate and pore morphology of AAO porous structures. This study helps reveal the growth mechanism of arrayed AAO nanochannels grown on a flat aluminum surface and provides insights to help pave the way to altering the geometry of nanochannels on AAO templates for the fabrication of advanced nanocomposite materials.

  18. Hot isostatic pressing of single-crystal nickel-base superalloys: Mechanism of pore closure and effect on Mechanical properties

    Directory of Open Access Journals (Sweden)

    Epishin Alexander I.

    2014-01-01

    Full Text Available Pore annihilation was investigated in the single-crystal nickel-base superalloy CMSX-4. HIP tests at 1288 °C/103 MPa were interrupted at different times, then the specimens were investigated by TEM, metallography and density measurements. The kinetics of pore annihilation was determined. The pore closure mechanism was identified as plastic deformation on the octahedral slip systems. A model describing the kinetics of pore closure has been developed on the base of crystal plasticity and large strain theory. Mechanical tests with the superalloy CMSX-4 and the Ru-containing superalloy VGM4 showed, that HIP significantly increases the fatigue life at low temperatures but has no effect on creep strength.

  19. Assessment of effectiveness of geologic isolation systems: geostatistical modeling of pore velocity

    International Nuclear Information System (INIS)

    Devary, J.L.; Doctor, P.G.

    1981-06-01

    A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater pore velocity and to characterize the pore velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater pore velocity, a hydrologic parameter required for contaminant transport analyses

  20. Comparative DNA isolation behaviours of silica and polymer based sorbents in batch fashion: monodisperse silica microspheres with bimodal pore size distribution as a new sorbent for DNA isolation.

    Science.gov (United States)

    Günal, Gülçin; Kip, Çiğdem; Eda Öğüt, S; İlhan, Hasan; Kibar, Güneş; Tuncel, Ali

    2018-02-01

    Monodisperse silica microspheres with bimodal pore-size distribution were proposed as a high performance sorbent for DNA isolation in batch fashion under equilibrium conditions. The proposed sorbent including both macroporous and mesoporous compartments was synthesized 5.1 μm in-size, by a "staged shape templated hydrolysis and condensation method". Hydrophilic polymer based sorbents were also obtained in the form of monodisperse-macroporous microspheres ca 5.5 μm in size, with different functionalities, by a developed "multi-stage microsuspension copolymerization" technique. The batch DNA isolation performance of proposed material was comparatively investigated using polymer based sorbents with similar morphologies. Among all sorbents tried, the best DNA isolation performance was achieved with the monodisperse silica microspheres with bimodal pore size distribution. The collocation of interconnected mesoporous and macroporous compartments within the monodisperse silica microspheres provided a high surface area and reduced the intraparticular mass transfer resistance and made easier both the adsorption and desorption of DNA. Among the polymer based sorbents, higher DNA isolation yields were achieved with the monodisperse-macroporous polymer microspheres carrying trimethoxysilyl and quaternary ammonium functionalities. However, batch DNA isolation performances of polymer based sorbents were significantly lower with respect to the silica microspheres.

  1. Nanofluidic Devices with Two Pores in Series for Resistive-Pulse Sensing of Single Virus Capsids

    DEFF Research Database (Denmark)

    Harms, Zachary D.; Mogensen, Klaus Bo; Rodrigues de Sousa Nunes, Pedro André

    2011-01-01

    We report fabrication and characterization of nanochannel devices with two nanopores in series for resistive-pulse sensing of hepatitis B virus (HBV) capsids. The nanochannel and two pores are patterned by electron beam lithography between two microchannels and etched by reactive ion etching....... The two nanopores are 50-nm wide, 50-nm deep, and 40-nm long and are spaced 2.0-μm apart. The nanochannel that brackets the two pores is 20 wider (1 μm) to reduce the electrical resistance adjacent to the two pores and to ensure the current returns to its baseline value between resistive-pulse events...

  2. PolyA Single Strand DNA Translocation Through an Alpha-Hemolysin Pore Stem

    Science.gov (United States)

    OKeeffe, James; Cozmuta, Ioana; Stolc, Viktor

    2003-01-01

    A new model for the polymer-pore interaction energy is introduced, based on an atomic-scale description of coulombic polymer-pore interaction. The enhanced drift velocity, experimentally observed for short polymers, is successfully accounted for, using this interaction energy model. For R/R(sub 0)>4 (R(sub 0)=7 angstroms) the translocation velocity approaches the free space drift velocity v(sub 0). This motivates the need to appropriately derivatize artificial nanopores, where R>R(sub 0).

  3. Synthesis of Mesoporous Single Crystal Co(OH)2 Nanoplate and Its Topotactic Conversion to Dual-Pore Mesoporous Single Crystal Co3O4.

    Science.gov (United States)

    Jia, Bao-Rui; Qin, Ming-Li; Li, Shu-Mei; Zhang, Zi-Li; Lu, Hui-Feng; Chen, Peng-Qi; Wu, Hao-Yang; Lu, Xin; Zhang, Lin; Qu, Xuan-Hui

    2016-06-22

    A new class of mesoporous single crystalline (MSC) material, Co(OH)2 nanoplates, is synthesized by a soft template method, and it is topotactically converted to dual-pore MSC Co3O4. Most mesoporous materials derived from the soft template method are reported to be amorphous or polycrystallined; however, in our synthesis, Co(OH)2 seeds grow to form single crystals, with amphiphilic block copolymer F127 colloids as the pore producer. The single-crystalline nature of material can be kept during the conversion from Co(OH)2 to Co3O4, and special dual-pore MSC Co3O4 nanoplates can be obtained. As the anode of lithium-ion batteries, such dual-pore MSC Co3O4 nanoplates possess exceedingly high capacity as well as long cyclic performance (730 mAh g(-1) at 1 A g(-1) after the 350th cycle). The superior performance is because of the unique hierarchical mesoporous structure, which could significantly improve Li(+) diffusion kinetics, and the exposed highly active (111) crystal planes are in favor of the conversion reaction in the charge/discharge cycles.

  4. Silicon Dioxide Thin Film Mediated Single Cell Nucleic Acid Isolation

    Science.gov (United States)

    Bogdanov, Evgeny; Dominova, Irina; Shusharina, Natalia; Botman, Stepan; Kasymov, Vitaliy; Patrushev, Maksim

    2013-01-01

    A limited amount of DNA extracted from single cells, and the development of single cell diagnostics make it necessary to create a new highly effective method for the single cells nucleic acids isolation. In this paper, we propose the DNA isolation method from biomaterials with limited DNA quantity in sample, and from samples with degradable DNA based on the use of solid-phase adsorbent silicon dioxide nanofilm deposited on the inner surface of PCR tube. PMID:23874571

  5. SINGLE CONVERSION ISOLATED IMPEDANCE TRANSFORMATION AMPLIFIER

    DEFF Research Database (Denmark)

    2003-01-01

    The invention relates to a switch mode power amplifier. A first and a second change-over switch are inserted between a DC voltage supply and a primary side of an isolation transformer. Two secondary windings are connected to a power output terminal. A first and a second secondary side power switc...

  6. Porous Electrodes I: Numerical Simulation Using Random Network and Single Pore Models.

    Science.gov (United States)

    1984-01-31

    characteristic of Zn and ZnO ) and scaling them down to the magnitude of a unit pore size- approximately 10i in diameter. We define a characteristic...supported by the Office of Naval Research under contract N00014-81-K-0339. 11 - 15 - REFERENCES 1. R. de Levis in Advances in Electrochemistry and...P. 3. Hendra Dr. C. E. Mueller Department of Chemistry The Electrochemistry Branch University of Southampton Naval Surface Weapons Center

  7. Toxicity of thallium on isolated rat liver mitochondria: the role of oxidative stress and MPT pore opening.

    Science.gov (United States)

    Eskandari, M R; Mashayekhi, Vida; Aslani, Majid; Hosseini, Mir-Jamal

    2015-02-01

    Thallium(I) is a highly toxic heavy metal; however, up to now, its mechanisms are poorly understood. The authors' previous studies showed that this compound could induce reactive oxygen species (ROS) formation, reduced glutathione (GSH) oxidation, membrane lipid peroxidation, and mitochondrial membrane potential (MMP) collapse in isolated rat hepatocyte. Because the liver is the storage site of thallium, it seems that the liver mitochondria are one of the important targets for hepatotoxicity. In this investigation, the effects of thallium on mitochondria were studied to investigate its mechanisms of toxicity. Mitochondria were isolated from rat liver and incubated with different concentrations of thallium (25-200 µM). Thallium(I)-treated mitochondria showed a marked elevation in oxidative stress parameters accompanied by MMP collapse when compared with the control group. These results showed that different concentrations of thallium (25-200 µM) induced a significant (P thallium(I)-induced liver toxicity is a result of the disruptive effect of this metal on the mitochondrial respiratory complexes (I, II, and IV), which are the obvious causes of metal-induced ROS formation and ATP depletion. The latter two events, in turn, trigger cell death signaling via opening of mitochondrial permeability transition pore and cytochrome c expulsion. © 2013 Wiley Periodicals, Inc.

  8. Production of multi-, oligo- and single-pore membranes using a continuous ion beam

    Czech Academy of Sciences Publication Activity Database

    Apel, P. Yu.; Ivanov, O.; Lizunov, N. E.; Mamonova, T. I.; Nechaev, A. N.; Olejniczak, K.; Vacík, Jiří; Dmitriev, S. N.

    2015-01-01

    Roč. 365, DEC (2015), s. 641-645 ISSN 0168-583X R&D Projects: GA MŠk LG14004 Institutional support: RVO:61389005 Keywords : ion beam * irradiation * ion track * etching * single nanopore Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.389, year: 2015

  9. Single- and two-phase flow simulation based on equivalent pore network extracted from micro-CT images of sandstone core.

    Science.gov (United States)

    Song, Rui; Liu, Jianjun; Cui, Mengmeng

    2016-01-01

    Due to the intricate structure of porous rocks, relationships between porosity or saturation and petrophysical transport properties classically used for reservoir evaluation and recovery strategies are either very complex or nonexistent. Thus, the pore network model extracted from the natural porous media is emphasized as a breakthrough to predict the fluid transport properties in the complex micro pore structure. This paper presents a modified method of extracting the equivalent pore network model from the three-dimensional micro computed tomography images based on the maximum ball algorithm. The partition of pore and throat are improved to avoid tremendous memory usage when extracting the equivalent pore network model. The porosity calculated by the extracted pore network model agrees well with the original sandstone sample. Instead of the Poiseuille's law used in the original work, the Lattice-Boltzmann method is employed to simulate the single- and two- phase flow in the extracted pore network. Good agreements are acquired on relative permeability saturation curves of the simulation against the experiment results.

  10. Single spore isolation and morphological characterization of local Malaysian isolates of rice blast fungus Magnoporthe grisea

    Science.gov (United States)

    Mishra, Ankitta; Ratnam, Wickneswari; Bhuiyan, Md Atiqur Rahman; Ponaya, Ariane; Jena, Khisord K.

    2015-09-01

    Rice blast is a destructive disease, caused by the fungal pathogen Magnaporthe grisea. It causes considerable damage to rice and leads to crop loss in rice growing regions worldwide. Although fungicides can be used to control rice blast, they generate additional cost in rice production and contamination of environment and food. Therefore, the use of resistant varieties is thought to be one of the most economically and environmentally efficient ways of crop protection from the disease. Six new local Malaysian isolates of M. grisea were isolated using single spore isolation method. Five isolates were from infected leaf samples collected from Kompleks Latihan MADA, Kedah and one was from Kelantan. These isolates were identified using morphological characteristics and microscopic studies and later confirmed by ITSequences. These isolates were induced to sporulate and used for greenhouse screening on two differential rice varieties: Mahsuri (susceptible) and Pongsu Seribu 2 (resistant). Among the 6 isolates, isolate number 3 was found to be the most virulent showing high sporulation while isolate number 4 was very slow growing, and the least virulent.

  11. Isolating and moving single atoms using silicon nanocrystals

    Science.gov (United States)

    Carroll, Malcolm S.

    2010-09-07

    A method is disclosed for isolating single atoms of an atomic species of interest by locating the atoms within silicon nanocrystals. This can be done by implanting, on the average, a single atom of the atomic species of interest into each nanocrystal, and then measuring an electrical charge distribution on the nanocrystals with scanning capacitance microscopy (SCM) or electrostatic force microscopy (EFM) to identify and select those nanocrystals having exactly one atom of the atomic species of interest therein. The nanocrystals with the single atom of the atomic species of interest therein can be sorted and moved using an atomic force microscope (AFM) tip. The method is useful for forming nanoscale electronic and optical devices including quantum computers and single-photon light sources.

  12. Computational/experimental studies of isolated, single component droplet combustion

    Science.gov (United States)

    Dryer, Frederick L.

    1993-01-01

    Isolated droplet combustion processes have been the subject of extensive experimental and theoretical investigations for nearly 40 years. The gross features of droplet burning are qualitatively embodied by simple theories and are relatively well understood. However, there remain significant aspects of droplet burning, particularly its dynamics, for which additional basic knowledge is needed for thorough interpretations and quantitative explanations of transient phenomena. Spherically-symmetric droplet combustion, which can only be approximated under conditions of both low Reynolds and Grashof numbers, represents the simplest geometrical configuration in which to study the coupled chemical/transport processes inherent within non-premixed flames. The research summarized here, concerns recent results on isolated, single component, droplet combustion under microgravity conditions, a program pursued jointly with F.A. Williams of the University of California, San Diego. The overall program involves developing and applying experimental methods to study the burning of isolated, single component droplets, in various atmospheres, primarily at atmospheric pressure and below, in both drop towers and aboard space-based platforms such as the Space Shuttle or Space Station. Both computational methods and asymptotic methods, the latter pursued mainly at UCSD, are used in developing the experimental test matrix, in analyzing results, and for extending theoretical understanding. Methanol, and the normal alkanes, n-heptane, and n-decane, have been selected as test fuels to study time-dependent droplet burning phenomena. The following sections summarizes the Princeton efforts on this program, describe work in progress, and briefly delineate future research directions.

  13. Isolating the effect of pore size distribution on electrochemical double-layer capacitance using activated fluid coke

    Science.gov (United States)

    Zuliani, Jocelyn E.; Tong, Shitang; Kirk, Donald W.; Jia, Charles Q.

    2015-12-01

    Electrochemical double-layer capacitors (EDLCs) use physical ion adsorption in the capacitive electrical double layer of high specific surface area (SSA) materials to store electrical energy. Previous work shows that the SSA-normalized capacitance increases when pore diameters are less than 1 nm. However, there still remains uncertainty about the charge storage mechanism since the enhanced SSA-normalized capacitance is not observed in all microporous materials. In previous studies, the total specific surface area and the chemical composition of the electrode materials were not controlled. The current work is the first reported study that systematically compares the performance of activated carbon prepared from the same raw material, with similar chemical composition and specific surface area, but different pore size distributions. Preparing samples with similar SSAs, but different pores sizes is not straightforward since increasing pore diameters results in decreasing the SSA. This study observes that the microporous activated carbon has a higher SSA-normalized capacitance, 14.1 μF cm-2, compared to the mesoporous material, 12.4 μF cm-2. However, this enhanced SSA-normalized capacitance is only observed above a threshold operating voltage. Therefore, it can be concluded that a minimum applied voltage is required to induce ion adsorption in these sub-nanometer micropores, which increases the capacitance.

  14. The use of nylon and glass fiber filter separators with different pore sizes in air-cathode single-chamber microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan

    2010-01-01

    Separators are needed in microbial fuel cells (MFCs) to reduce electrode spacing and preventing electrode short circuiting. The use of nylon and glass fiber filter separators in single-chamber, air-cathode MFCs was examined for their effect on performance. Larger pore nylon mesh were used that had regular mesh weaves with pores ranging from 10 to 160 μm, while smaller pore-size nylon filters (0.2-0.45 μm) and glass fiber filters (0.7-2.0 μm) had a more random structure. The pore size of both types of nylon filters had a direct and predictable effect on power production, with power increasing from 443 ± 27 to 650 ± 7 mW m-2 for pore sizes of 0.2 and 0.45 μm, and from 769 ± 65 to 941 ± 47 mW m-2 for 10 to 160 μm. In contrast, changes in pore sizes of the glass fiber filters resulted in a relatively narrow change in power (732 ± 48 to 779 ± 43 mW m-2) for pore sizes of 0.7 to 2 μm. An ideal separator should increase both power density and Coulombic efficiency (CE). However, CEs measured for the different separators were inversely correlated with power production, demonstrating that materials which reduced the oxygen diffusion into the reactor also hindered proton transport to the cathode, reducing power production through increased internal resistance. Our results highlight the need to develop separators that control oxygen transfer and facilitate proton transfer to the cathode. © 2010 The Royal Society of Chemistry.

  15. Fluoride export (FEX) proteins from fungi, plants and animals are 'single barreled' channels containing one functional and one vestigial ion pore

    Science.gov (United States)

    Berbasova, Tetyana; Nallur, Sunitha; Sells, Taylor; Smith, Kathryn D.; Gordon, Patricia B.; Tausta, Susan Lori

    2017-01-01

    The fluoride export protein (FEX) in yeast and other fungi provides tolerance to fluoride (F-), an environmentally ubiquitous anion. FEX efficiently eliminates intracellular fluoride that otherwise would accumulate at toxic concentrations. The FEX homolog in bacteria, Fluc, is a ‘double-barreled’ channel formed by dimerization of two identical or similar subunits. FEX in yeast and other eukaryotes is a monomer resulting from covalent fusion of the two subunits. As a result, both potential fluoride pores are created from different parts of the same protein. Here we identify FEX proteins from two multicellular eukaryotes, a plant Arabidopsis thaliana and an animal Amphimedon queenslandica, by demonstrating significant fluoride tolerance when these proteins are heterologously expressed in the yeast Saccharomyces cerevisiae. Residues important for eukaryotic FEX function were determined by phylogenetic sequence alignment and functional analysis using a yeast growth assay. Key residues of the fluoride channel are conserved in only one of the two potential fluoride-transporting pores. FEX activity is abolished upon mutation of residues in this conserved pore, suggesting that only one of the pores is functional. The same topology is conserved for the newly identified FEX proteins from plant and animal. These data suggest that FEX family of fluoride channels in eukaryotes are ‘single-barreled’ transporters containing one functional pore and a second non-functional vestigial remnant of a homologous gene fusion event. PMID:28472134

  16. Tetraphenylphosphonium-selective electrode as a tool for evaluating mitochondrial permeability transition pore function in isolated rat hepatocytes

    Czech Academy of Sciences Publication Activity Database

    Lábajová, A.; Kofránek, J.; Křiváková, P.; Červinková, Z.; Drahota, Zdeněk

    2006-01-01

    Roč. 25, č. 3 (2006), s. 325-331 ISSN 0231-5882 R&D Projects: GA ČR(CZ) GD303/03/H065; GA ČR(CZ) GA303/06/1261 Institutional research plan: CEZ:AV0Z50110509 Keywords : hepatocytes * mitochondria * membrane-permeability-transition –pore Subject RIV: CE - Biochemistry Impact factor: 0.771, year: 2006

  17. Can isolated single black holes produce X-ray novae?

    Science.gov (United States)

    Matsumoto, Tatsuya; Teraki, Yuto; Ioka, Kunihito

    2018-03-01

    Almost all black holes (BHs) and BH candidates in our Galaxy have been discovered as soft X-ray transients, so-called X-ray novae. X-ray novae are usually considered to arise from binary systems. Here, we propose that X-ray novae are also caused by isolated single BHs. We calculate the distribution of the accretion rate from interstellar matter to isolated BHs, and find that BHs in molecular clouds satisfy the condition of the hydrogen-ionization disc instability, which results in X-ray novae. The estimated event rate is consistent with the observed one. We also check an X-ray novae catalogue (Corral-Santana et al.) and find that 16/59 ˜ 0.27 of the observed X-ray novae are potentially powered by isolated BHs. The possible candidates include IGR J17454-2919, XTE J1908-094, and SAX J1711.6-3808. Near-infrared photometric and spectroscopic follow-ups can exclude companion stars for a BH census in our Galaxy.

  18. Isolated and Single Pedestrians and Pedestrian Groups on Sidewalks

    Directory of Open Access Journals (Sweden)

    Francesco Pinna

    2017-11-01

    Full Text Available Walking freedom can define the quality of an urban area, but this freedom is conditioned by various factors. The research objective is to study pedestrian behavior on sidewalks. Data are collected during on site surveys by means of concealed camcorders. For each pedestrian many factors are observed, such as gender, age, direction, distractions, transport of objects, etc., which could influence pedestrian behavior. Data processing allows the identification of mathematical models describing the average pedestrian’s behavior, subdivided for user type (isolated, single, group. In general, the mean walking pedestrian speed decreases depending on user type (in a linear manner if age class grows for isolated pedestrians, while with the square of age for other user types, of gender, and of facing type. Models obtained for the different pedestrian types were compared to understand the differences in speeds, underlining that pedestrian interferences play a significant role in defining behavior and, therefore, speed. The results support the idea that, to define a smooth pedestrian speed as an indicator of the “walkability” of a path, in addition to considering the path and user’s characteristics, it is also necessary to define the type of user for which the infrastructure is designed.

  19. Characterization of wide-pore reversed-phase columns for biopolymer separations. I. Single-parametric evaluation

    NARCIS (Netherlands)

    Bede, A; Rippel, G; Szepesy, L; Claessens, H.A.

    1996-01-01

    Nine prepacked wide-pore columns recommended for protein separation were studied. The stationary phases investigated were widely different with respect to the type of ligands. In order to characterize the columns, measurements were made with six different test mixtures containing two different

  20. Isolated Deep Infarcts: Which Size Indicates Single Penetrating Artery Disease?

    Directory of Open Access Journals (Sweden)

    Nilüfer Yeşilot

    2007-06-01

    Full Text Available OBJECTIVE: The relationship between infarction size determined in the acute stage and the probability of the presence of large artery stenosis or cardiac source of emboli in patients with isolated deep infarcts was evaluated. METHODS: Maximum transverse diameters of the infarcts seen in 59 consecutive patients’ T2 weighted MRI scans were prospectively recorded. Receiver operating characteristic curves were generated to analyze the optimal size that discriminate IDI with and without underlying large artery stenosis or cardiac source of emboli (LAS/CSE. RESULTS: Twenty-six IDI were in the medial cerebral artery (MCA territory, 24 in pons and 9 in thalamus. Optimal infarct diameter for MCA IDIs was 25 mm. One of the 10 cases with small (2-14 mm and half of the 14 cases (50% with large (17-25 mm pontine infarcts had LAS/CSE, but only 2 patients, one in each group had severe (≥70% basilar artery stenosis. None had major CSE. None of the 9 cases with thalamic infarcts (8-20 mm had LAS/CSE. CONCLUSION: : IDIs in different anatomical locations should be assessed separately. Middle cerebral artery territory IDIs with a maximum diameter of less than 25 mm are rarely associated with LAS/CSE and possibly develop due to occlusion of single lenticulostriate artery. Large unilateral pontine infarcts are usually not associated with severe basilar artery stenosis or major CSE and are probably caused by basilar artery atheromatous branch occlusion

  1. Single-step direct fabrication of pillar-on-pore hybrid nanostructures in anodizing aluminum for superior superhydrophobic efficiency.

    Science.gov (United States)

    Jeong, Chanyoung; Choi, Chang-Hwan

    2012-02-01

    Conventional electrochemical anodizing processes of metals such as aluminum typically produce planar and homogeneous nanopore structures. If hydrophobically treated, such 2D planar and interconnected pore structures typically result in lower contact angle and larger contact angle hysteresis than 3D disconnected pillar structures and, hence, exhibit inferior superhydrophobic efficiency. In this study, we demonstrate for the first time that the anodizing parameters can be engineered to design novel pillar-on-pore (POP) hybrid nanostructures directly in a simple one-step fabrication process so that superior surface superhydrophobicity can also be realized effectively from the electrochemical anodization process. On the basis of the characteristic of forming a self-ordered porous morphology in a hexagonal array, the modulation of anodizing voltage and duration enabled the formulation of the hybrid-type nanostructures having controlled pillar morphology on top of a porous layer in both mild and hard anodization modes. The hybrid nanostructures of the anodized metal oxide layer initially enhanced the surface hydrophilicity significantly (i.e., superhydrophilic). However, after a hydrophobic monolayer coating, such hybrid nanostructures then showed superior superhydrophobic nonwetting properties not attainable by the plain nanoporous surfaces produced by conventional anodization conditions. The well-regulated anodization process suggests that electrochemical anodizing can expand its usefulness and efficacy to render various metallic substrates with great superhydrophilicity or -hydrophobicity by directly realizing pillar-like structures on top of a self-ordered nanoporous array through a simple one-step fabrication procedure.

  2. A Single Switch Dual Output Non-Isolated Boost Converter

    DEFF Research Database (Denmark)

    Klimczak, Pawel; Munk-Nielsen, Stig

    2008-01-01

    There are many applications for high gain dc-dc converters. In several of these applications galvanic isolation is not required, but there are some safety issues regarding missing isolation and leakage current. Usage of a half-bridge inverter and a dual dc-link may solve this issues. In this paper...

  3. The use of nylon and glass fiber filter separators with different pore sizes in air-cathode single-chamber microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan; Cheng, Shaoan; Huang, Xia; Logan, Bruce E.

    2010-01-01

    on performance. Larger pore nylon mesh were used that had regular mesh weaves with pores ranging from 10 to 160 μm, while smaller pore-size nylon filters (0.2-0.45 μm) and glass fiber filters (0.7-2.0 μm) had a more random structure. The pore size of both types

  4. Single-Molecule Fluorescence Microscopy Reveals Local Diffusion Coefficients in the Pore Network of an Individual Catalyst Particle

    NARCIS (Netherlands)

    Hendriks, Frank|info:eu-repo/dai/nl/412642697; Meirer, Florian; Kubarev, Alexey V.; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Roeffaers, Maarten B J; Vogt, Eelco T. C.|info:eu-repo/dai/nl/073717398; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2017-01-01

    We used single-molecule fluorescence microscopy to study self-diffusion of a feedstock-like probe molecule with nanometer accuracy in the macropores of a micrometer-sized, real-life fluid catalytic cracking (FCC) particle. Movies of single fluorescent molecules allowed their movement through the

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

    Science.gov (United States)

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

    2012-01-01

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

  6. Rapid isolation of high molecular weight DNA from single dried ...

    African Journals Online (AJOL)

    ANAND

    For studying genetic diversity in populations of predatory coccinellid, Cryptolaemus montrouzieri. Mulsant (Coccinellidae: Coleoptera), our attempts to isolate high quality DNA from individual adult beetle using several previously reported protocols and even modifications were quite unsuccessful as the insect size was small ...

  7. Isolation of Kupffer Cells and Hepatocytes from a Single Mouse Liver

    DEFF Research Database (Denmark)

    Aparicio-Vergara, Marcela; Tencerova, Michaela; Morgantini, Cecilia

    2017-01-01

    Liver perfusion is a common technique used to isolate parenchymal and non-parenchymal liver cells for in vitro experiments. This method allows hepatic cells to be separated based on their size and weight, by centrifugation using a density gradient. To date, other methods allow the isolation of only...... one viable hepatic cellular fraction from a single mouse; either parenchymal (hepatocytes) or non-parenchymal cells (i.e., Kupffer cells or hepatic stellate cells). Here, we describe a method to isolate both hepatocytes and Kupffer cells from a single mouse liver, thereby providing the unique...... advantage of studying different liver cell types that have been isolated from the same organism....

  8. Relationships among North American and Japanese Laetiporus isolates inferred from molecular phylogenetics and single-spore incompatibility reactions

    Science.gov (United States)

    Mark T. Banik; Daniel L. Lindner; Yuko Ota; Tsutomu Hattori

    2010-01-01

    Relationships were investigated among North American and Japanese isolates of Laetiporus using phylogenetic analysis of ITS sequences and single-spore isolate incompatibility. Single-spore isolate pairings revealed no significant compatibility between North American and Japanese isolates. ITS analysis revealed 12 clades within the core ...

  9. Isolated single-molecule magnets on native gold.

    Science.gov (United States)

    Zobbi, Laura; Mannini, Matteo; Pacchioni, Mirko; Chastanet, Guillaume; Bonacchi, Daniele; Zanardi, Chiara; Biagi, Roberto; Del Pennino, Umberto; Gatteschi, Dante; Cornia, Andrea; Sessoli, Roberta

    2005-03-28

    The incorporation of thioether groups in the structure of a Mn12 single-molecule magnet, [Mn12(O12)(L)16(H2O)4] with L = 4-(methylthio)benzoate, is a successful route to the deposition of well-separated clusters on native gold surfaces and to the addressing of individual molecules by scanning tunnelling microscopy.

  10. Characterization of single spore isolates of Agaricus bisporus (Lange) Imbach using conventional and molecular methods.

    Science.gov (United States)

    Sharma, Manju; Suman, B C; Gupta, Dharmesh

    2014-10-01

    Strains A-15, S11, S-140, and U3 of Agaricus bisporus (Lange) Imbach, were used as parent strains for raising single spore homokaryotic isolates. Out of total 1,642 single spore isolates, only 36 single spore isolates were homokaryons and exhibited slow mycelial growth rate (≤2.0 mm/day) and appressed colony morphology. All these SSIs failed to produce pinheads in Petri plates even after 65 days of incubation, whereas the strandy slow growing SSIs along with parent strains were able to form the fructification in petriplates after 30 days. Out of 24, six ISSR primers, exhibited scorable bands. In the ISSR fingerprints, single spore isolates, homokaryons, lacked amplification products at multiple loci; they grow slowly and all of them had appressed types of colony morphology. The study revealed losses of ISSR polymorphic patterns in non-fertile homokaryotic single spore isolates compared to the parental control or fertile heterokaryotic single spore isolates.

  11. Dielectrophoretic immobilisation of nanoparticles as isolated singles in regular arrays

    Science.gov (United States)

    Knigge, Xenia; Wenger, Christian; Bier, Frank F.; Hölzel, Ralph

    2018-02-01

    We demonstrate the immobilisation of polystyrene nanoparticles on vertical nano-electrodes by means of dielectrophoresis. The electrodes have diameters of 500 nm or 50 nm, respectively, and are arranged in arrays of several thousand electrodes, allowing many thousands of experiments in parallel. At a frequency of 15 kHz, which is found favourable for polystyrene, several occupation patterns are observed, and both temporary and permanent immobilisation is achieved. In addition, a histogram method is applied, which allows to determine the number of particles occupying the electrodes. These results are validated with scanning electron microscopy images. Immobilising exactly one particle at each electrode tip is achieved for electrode tip diameters with half the particle size. Extension of this system down to the level of single molecules is envisaged, which will avoid ensemble averaging at still statistically large sample sizes.

  12. Living in single person households and the risk of isolation in later life

    Directory of Open Access Journals (Sweden)

    Laura Banks

    2009-10-01

    Full Text Available Data from the International Social Survey Programme (2001 was used to analyse the social networks of older people and whether living in single person households increased the risk of isolation. When comparing respondents with one or more adult children, there was no significant difference in the likelihood of experiencing familial isolation between people living in single person households and those living in larger households. A majority of those living in single person households had at least regular contact with a sibling, adult child or close friend and participated in a social organisation. Friends compensate to some extent for a lack of support from the family, although in southern and eastern European countries, other relatives appeared to be more important in support networks. People living in single person households were more likely to experience isolation, but this was largely related to advanced age and childlessness. Whilst a very small minority in Japan were living in single person households, they were significantly more likely to be severely isolated than those living in single person households in other countries.

  13. Single HIV-1 Imaging Reveals Progression of Infection through CA-Dependent Steps of Docking at the Nuclear Pore, Uncoating, and Nuclear Transport.

    Science.gov (United States)

    Francis, Ashwanth C; Melikyan, Gregory B

    2018-04-11

    The HIV-1 core consists of capsid proteins (CA) surrounding viral genomic RNA. After virus-cell fusion, the core enters the cytoplasm and the capsid shell is lost through uncoating. CA loss precedes nuclear import and HIV integration into the host genome, but the timing and location of uncoating remain unclear. By visualizing single HIV-1 infection, we find that CA is required for core docking at the nuclear envelope (NE), whereas early uncoating in the cytoplasm promotes proteasomal degradation of viral complexes. Only docked cores exhibiting accelerated loss of CA at the NE enter the nucleus. Interestingly, a CA mutation (N74D) altering virus engagement of host factors involved in nuclear transport does not alter the uncoating site at the NE but reduces the nuclear penetration depth. Thus, CA protects HIV-1 complexes from degradation, mediates docking at the nuclear pore before uncoating, and determines the depth of nuclear penetration en route to integration. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. Single Spore Isolation as a Simple and Efficient Technique to obtain fungal pure culture

    Science.gov (United States)

    Noman, E.; Al-Gheethi, AA; Rahman, N. K.; Talip, B.; Mohamed, R.; H, N.; Kadir, O. A.

    2018-04-01

    The successful identification of fungi by phenotypic methods or molecular technique depends mainly on the using an advanced technique for purifying the isolates. The most efficient is the single spore technique due to the simple requirements and the efficiency in preventing the contamination by yeast, mites or bacteria. The method described in the present work is depends on the using of a light microscope to transfer one spore into a new culture medium. The present work describes a simple and efficient procedure for single spore isolation to purify of fungi recovered from the clinical wastes.

  15. Reactive oxygen species formation during tetanic contractions in single isolated Xenopus myofibers

    OpenAIRE

    Zuo, Li; Nogueira, Leonardo; Hogan, Michael C.

    2011-01-01

    Contracting skeletal muscle produces reactive oxygen species (ROS) that have been shown to affect muscle function and adaptation. However, real-time measurement of ROS in contracting myofibers has proven to be difficult. We used amphibian (Xenopus laevis) muscle to test the hypothesis that ROS are formed during contractile activity in isolated single skeletal muscle fibers and that this contraction-induced ROS formation affects fatigue development. Single myofibers were loaded with 5 μM dihyd...

  16. Single Nisoldipine-Sensitive Calcium Channels in Smooth Muscle Cells Isolated from Rabbit Mesenteric Artery

    Science.gov (United States)

    Worley, Jennings F.; Deitmer, Joachim W.; Nelson, Mark T.

    1986-08-01

    Single smooth muscle cells were enzymatically isolated from the rabbit mesenteric artery. At physiological levels of external Ca, these cells were relaxed and contracted on exposure to norepinephrine, caffeine, or high levels of potassium. The patch-clamp technique was used to measure unitary currents through single channels in the isolated cells. Single channels were selective for divalent cations and exhibited two conductance levels, 8 pS and 15 pS. Both types of channels were voltage-dependent, and channel activity occurred at potentials positive to -40 mV. The activity of both channel types was almost completely inhibited by 50 nM nisoldipine. These channels appear to be the pathways for voltage-dependent Ca influx in vascular smooth muscle and may be the targets of the clinically used dihydropyridines.

  17. Quantitative Analysis of Isolated Single-Wall Carbon Nanotubes with Their Molar Absorbance Coefficients

    Directory of Open Access Journals (Sweden)

    Shota Kuwahara

    2014-01-01

    Full Text Available The molar absorbance coefficients of metallic, semiconducting, and (6,5 chirality enriched single-wall carbon nanotubes were evaluated by a spray technique combined with atomic force microscopy. Single-wall carbon nanotubes with isolated and a single predominant electronic type were obtained by using the density-gradient ultracentrifugation technique. In the visible region, all coefficients had similar values around 2–5 × 109/mL mol−1 cm−1, independent of their diameter distribution and the electronic types of single-wall carbon nanotubes, and the εS22/εM11  and εS11/εM11 were estimated to be 1.0 and 4.0, respectively. The coefficient strongly depends on the length of single-wall carbon nanotubes, independent of their electronic types and chirality.

  18. Congenital heart defects in newborns with apparently isolated single gastrointestinal malformation: A retrospective study.

    Science.gov (United States)

    Schierz, Ingrid Anne Mandy; Pinello, Giuseppa; Giuffrè, Mario; La Placa, Simona; Piro, Ettore; Corsello, Giovanni

    2016-12-01

    Congenital gastrointestinal system malformations/abdominal wall defects (GISM) may appear as isolated defects (single or complex), or in association with multiple malformations. The high incidence of association of GISM and congenital heart defects (CHD) in patients with syndromes and malformative sequences is known, but less expected is the association of apparently isolated single GISM and CHD. The aim of this study was to investigate the frequency of CHD in newborns with isolated GISM, and the possibility to modify the diagnostic-therapeutic approach just before the onset of cardiac symptoms or complications. Anamnestic, clinical, and imaging data of newborns requiring abdominal surgery for GISM, between 2009 and 2014, were compared with a control group of healthy newborns. Distribution of GISM and cardiovascular abnormalities were analyzed, and risk factors for adverse outcomes were identified. Seventy-one newborns with isolated GISM were included in this study. More frequent GISM were intestinal rotation and fixation disorders. CHD were observed in 15.5% of patients, augmenting their risk for morbidity. Risk factors for morbidity related to sepsis were identified in central venous catheter, intestinal stoma, and H2-inhibitor-drugs. Moreover, 28.2% of newborns presented only functional cardiac disorders but an unexpectedly higher mortality. The high incidence of congenital heart disease in infants with apparently isolated GISM confirms the need to perform an echocardiographic study before surgery to improve perioperative management and prevent complications such as sepsis and endocarditis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Capillary condensation hysteresis in overlapping spherical pores: a Monte Carlo simulation study.

    Science.gov (United States)

    Gor, Gennady Yu; Rasmussen, Christopher J; Neimark, Alexander V

    2012-08-21

    The mechanisms of hysteretic phase transformations in fluids confined to porous bodies depend on the size and shape of pores, as well as their connectivity. We present a Monte Carlo simulation study of capillary condensation and evaporation cycles in the course of Lennard-Jones fluid adsorption in the system of overlapping spherical pores. This model system mimics pore shape and connectivity in some mesoporous materials obtained by templating cubic surfactant mesophases or colloidal crystals. We show different mechanisms of capillary hysteresis depending on the size of the window between the pores. For the system with a small window, the hysteresis cycle is similar to that in a single spherical pore: capillary condensation takes place upon achieving the limit of stability of adsorption film and evaporation is triggered by cavitation. When the window is large enough, the capillary condensation shifts to a pressure higher than that of the isolated pore, and the possibility for the equilibrium mechanism of desorption is revealed. These finding may have important implications for practical problems of assessment of the pore size distributions in mesoporous materials with cagelike pore networks.

  20. Mesoscale Simulations of Pore Migration in a Nuclear Fuel

    International Nuclear Information System (INIS)

    Radhakrishnan, Balasubramaniam; Gorti, Sarma B.

    2010-01-01

    The evolution of pore and grain structure in a nuclear fuel environment is strongly influenced by the local temperature, and the temperature gradient. The evolution of pore and grain structure in an externally imposed temperature gradient is simulated for a hypothetical material using a Potts model approach that allows for porosity migration by mechanisms similar to surface, grain boundary and volume diffusion, as well as the interaction of migrating pores with stationary grain boundaries. First, the migration of a single pore in a single crystal in the presence of the temperature gradient is simulated. Next, the interaction of a pore moving in a temperature gradient with a grain boundary that is perpendicular to the pore migration direction is simulated in order to capture the force exerted by the pore on the grain boundary. The simulations reproduce the expected variation of pore velocity with pore size as well as the variation of the grain boundary force with pore size.

  1. Improved and Reproducible Flow Cytometry Methodology for Nuclei Isolation from Single Root Meristem

    Directory of Open Access Journals (Sweden)

    Thaís Cristina Ribeiro Silva

    2010-01-01

    Full Text Available Root meristems have increasingly been target of cell cycle studies by flow cytometric DNA content quantification. Moreover, roots can be an alternative source of nuclear suspension when leaves become unfeasible and for chromosome analysis and sorting. In the present paper, a protocol for intact nuclei isolation from a single root meristem was developed. This proceeding was based on excision of the meristematic region using a prototypical slide, followed by short enzymatic digestion and mechanical isolation of nuclei during homogenization with a hand mixer. Such parameters were optimized for reaching better results. Satisfactory nuclei amounts were extracted and analyzed by flow cytometry, producing histograms with reduced background noise and CVs between 3.2 and 4.1%. This improved and reproducible technique was shown to be rapid, inexpensive, and simple for nuclear extraction from a single root tip, and can be adapted for other plants and purposes.

  2. Specific single-cell isolation and genomic amplification of uncultured microorganisms

    DEFF Research Database (Denmark)

    Kvist, Thomas; Ahring, Birgitte Kiær; Lasken, R.S.

    2007-01-01

    We in this study describe a new method for genomic studies of individual uncultured prokaryotic organisms, which was used for the isolation and partial genome sequencing of a soil archaeon. The diversity of Archaea in a soil sample was mapped by generating a clone library using group-specific pri......We in this study describe a new method for genomic studies of individual uncultured prokaryotic organisms, which was used for the isolation and partial genome sequencing of a soil archaeon. The diversity of Archaea in a soil sample was mapped by generating a clone library using group......-specific primers in combination with a terminal restriction fragment length polymorphism profile. Intact cells were extracted from the environmental sample, and fluorescent in situ hybridization probing with Cy3-labeled probes designed from the clone library was subsequently used to detect the organisms...... of interest. Single cells with a bright fluorescent signal were isolated using a micromanipulator and the genome of the single isolated cells served as a template for multiple displacement amplification (MDA) using the Phi29 DNA polymerase. The generated MDA product was afterwards used for 16S rRNA gene...

  3. Dissolution at porous interfaces VI: Multiple pore systems.

    Science.gov (United States)

    Grijseels, H; Crommelin, D J; De Blaey, C J

    1984-12-01

    With the aid of rapidly dissolving sodium chloride particles, cubic pores were made in the surface of a theophylline tablet. The influence of the pores on the dissolution rate of the surface was investigated in a rotating disk apparatus. Like the drilled pores used in earlier studies, downstream on the surface they caused a turbulent flow regimen with the development of a trough due to enhanced erosion. The phenomenon of a critical pore diameter, discovered with single, drilled pores, seems to be applicable to the cubic pores investigated in this study, although a higher degree of surface coverage with pores caused complications, probably due to particles bordering one another and forming larger pores. The behavior of the porous surfaces at different rotation speeds was studied. Due to the presence of pores the laminar character of the boundary layer flow changes to turbulent, which induces locally an increased dissolution flux in the wake of a pore.

  4. Performance of Single Friction Pendulum bearing for isolated buildings subjected to seismic actions in Vietnam

    Science.gov (United States)

    Nguyen, N. V.; Nguyen, C. H.; Hoang, H. P.; Huong, K. T.

    2018-04-01

    Using structural control technology in earthquake resistant design of buildings in Vietnam is very limited. In this paper, a performance evaluation of using Single Friction Pendulum (SFP) bearing for seismically isolated buildings with earthquake conditions in Vietnam is presented. A two-dimensional (2-D) model of the 5-storey building subjected to earthquakes is analyzed in time domain. Accordingly, the model is analyzed for 2 cases: with and without SFP bearing. The ground acceleration data is selected and scaled to suit the design acceleration in Hanoi followed by the Standard TCVN 9386:2012. It is shown that the seismically isolated buildings gets the performance objectives while achieving an 91% reduction in the base shear, a significant decrease in the inter-story drift and absolute acceleration of each story.

  5. CheckM: assessing the quality of microbial genomes recovered from isolates, single cells, and metagenomes

    Science.gov (United States)

    Parks, Donovan H.; Imelfort, Michael; Skennerton, Connor T.; Hugenholtz, Philip; Tyson, Gene W.

    2015-01-01

    Large-scale recovery of genomes from isolates, single cells, and metagenomic data has been made possible by advances in computational methods and substantial reductions in sequencing costs. Although this increasing breadth of draft genomes is providing key information regarding the evolutionary and functional diversity of microbial life, it has become impractical to finish all available reference genomes. Making robust biological inferences from draft genomes requires accurate estimates of their completeness and contamination. Current methods for assessing genome quality are ad hoc and generally make use of a limited number of “marker” genes conserved across all bacterial or archaeal genomes. Here we introduce CheckM, an automated method for assessing the quality of a genome using a broader set of marker genes specific to the position of a genome within a reference genome tree and information about the collocation of these genes. We demonstrate the effectiveness of CheckM using synthetic data and a wide range of isolate-, single-cell-, and metagenome-derived genomes. CheckM is shown to provide accurate estimates of genome completeness and contamination and to outperform existing approaches. Using CheckM, we identify a diverse range of errors currently impacting publicly available isolate genomes and demonstrate that genomes obtained from single cells and metagenomic data vary substantially in quality. In order to facilitate the use of draft genomes, we propose an objective measure of genome quality that can be used to select genomes suitable for specific gene- and genome-centric analyses of microbial communities. PMID:25977477

  6. Shape of isolated domains in lithium tantalate single crystals at elevated temperatures

    International Nuclear Information System (INIS)

    Shur, V. Ya.; Akhmatkhanov, A. R.; Baturin, I. S.; Chezganov, D. S.; Lobov, A. I.; Smirnov, M. M.

    2013-01-01

    The shape of isolated domains has been investigated in congruent lithium tantalate (CLT) single crystals at elevated temperatures and analyzed in terms of kinetic approach. The obtained temperature dependence of the growing domain shape in CLT including circular shape at temperatures above 190 °C has been attributed to increase of relative input of isotropic ionic conductivity. The observed nonstop wall motion and independent domain growth after merging in CLT as opposed to stoichiometric lithium tantalate have been attributed to difference in wall orientation. The computer simulation has confirmed applicability of the kinetic approach to the domain shape explanation

  7. Robust fault detection and isolation technique for single-input/single-output closed-loop control systems that exhibit actuator and sensor faults

    DEFF Research Database (Denmark)

    Izadi-Zamanabadi, Roozbeh; Alavi, S. M. Mahdi; Hayes, M. J.

    2008-01-01

    An integrated quantitative feedback design and frequency-based fault detection and isolation (FDI) approach is presented for single-input/single-output systems. A novel design methodology, based on shaping the system frequency response, is proposed to generate an appropriate residual signal...

  8. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir; Benalia, Atallah; Boukhetala, Djamel; Laleg-Kirati, Taous-Meriem

    2012-01-01

    in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter

  9. Direct isolated single and di-photon production at ATLAS and CMS

    International Nuclear Information System (INIS)

    Kolberg, T.R.

    2014-01-01

    Direct isolated single and di-photon production cross section measurements are a classic test of perturbative QCD and are used to constrain the gluon densities in the proton. The LHC general-purpose experiments ATLAS and CMS have made a number of differential cross section measurements for both the single and di-photon production processes using the 2011 dataset at 7 TeV center-of-mass energy. Overall, good agreement is found with the theoretical predictions, and the measurements are sufficiently precise to constrain the gluon PDF uncertainty for other production processes at the LHC. Some systematic differences between the di-photon data and the NLO (Next-to-Leading Order) theoretical predictions show a need to include higher-order effects in the predictions. (author)

  10. Isolation and functional interrogation of adult human prostate epithelial stem cells at single cell resolution.

    Science.gov (United States)

    Hu, Wen-Yang; Hu, Dan-Ping; Xie, Lishi; Li, Ye; Majumdar, Shyama; Nonn, Larisa; Hu, Hong; Shioda, Toshi; Prins, Gail S

    2017-08-01

    Using primary cultures of normal human prostate epithelial cells, we developed a novel prostasphere-based, label-retention assay that permits identification and isolation of stem cells at a single cell level. Their bona fide stem cell nature was corroborated using in vitro and in vivo regenerative assays and documentation of symmetric/asymmetric division. Robust WNT10B and KRT13 levels without E-cadherin or KRT14 staining distinguished individual stem cells from daughter progenitors in spheroids. Following FACS to isolate label-retaining stem cells from label-free progenitors, RNA-seq identified unique gene signatures for the separate populations which may serve as useful biomarkers. Knockdown of KRT13 or PRAC1 reduced sphere formation and symmetric self-renewal highlighting their role in stem cell maintenance. Pathways analysis identified ribosome biogenesis and membrane estrogen-receptor signaling enriched in stem cells with NF-ĸB signaling enriched in progenitors; activities that were biologically confirmed. Further, bioassays identified heightened autophagy flux and reduced metabolism in stem cells relative to progenitors. These approaches similarly identified stem-like cells from prostate cancer specimens and prostate, breast and colon cancer cell lines suggesting wide applicability. Together, the present studies isolate and identify unique characteristics of normal human prostate stem cells and uncover processes that maintain stem cell homeostasis in the prostate gland. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  11. Isolation and functional interrogation of adult human prostate epithelial stem cells at single cell resolution

    Directory of Open Access Journals (Sweden)

    Wen-Yang Hu

    2017-08-01

    Full Text Available Using primary cultures of normal human prostate epithelial cells, we developed a novel prostasphere-based, label-retention assay that permits identification and isolation of stem cells at a single cell level. Their bona fide stem cell nature was corroborated using in vitro and in vivo regenerative assays and documentation of symmetric/asymmetric division. Robust WNT10B and KRT13 levels without E-cadherin or KRT14 staining distinguished individual stem cells from daughter progenitors in spheroids. Following FACS to isolate label-retaining stem cells from label-free progenitors, RNA-seq identified unique gene signatures for the separate populations which may serve as useful biomarkers. Knockdown of KRT13 or PRAC1 reduced sphere formation and symmetric self-renewal highlighting their role in stem cell maintenance. Pathways analysis identified ribosome biogenesis and membrane estrogen-receptor signaling enriched in stem cells with NF-ĸB signaling enriched in progenitors; activities that were biologically confirmed. Further, bioassays identified heightened autophagy flux and reduced metabolism in stem cells relative to progenitors. These approaches similarly identified stem-like cells from prostate cancer specimens and prostate, breast and colon cancer cell lines suggesting wide applicability. Together, the present studies isolate and identify unique characteristics of normal human prostate stem cells and uncover processes that maintain stem cell homeostasis in the prostate gland.

  12. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir

    2012-06-01

    This paper deals with the problem of detection and isolation of stator short-circuit failure in a single asynchronous machine using a geometric approach. After recalling the basis of the geometric approach for fault detection and isolation in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter structure, both aiming at generating residuals which are sensitive to one fault and insensitive to the other faults. Some numerical tests will be presented to illustrate the efficiency of the method.

  13. Improved isolation of cadmium from paddy soil by novel technology based on pore water drainage with graphite-contained electro-kinetic geosynthetics.

    Science.gov (United States)

    Tang, Xianqiang; Li, Qingyun; Wang, Zhenhua; Hu, Yanping; Hu, Yuan; Scholz, Miklas

    2018-03-10

    Novel soil remediation equipment based on electro-kinetic geosynthetics (EKG) was developed for in situ isolation of metals from paddy soil. Two mutually independent field plot experiments A and B (with and without electric current applied) were conducted. After saturation using ferric chloride (FeCl 3 ) and calcium chloride (CaCl 2 ), soil water drainage capacity, soil cadmium (Cd) removal performance, energy consumption as well as soil residual of iron (Fe) and chloride (Cl) were assessed. Cadmium dissolved in the soil matrix and resulted in a 100% increase of diethylenetriamine-pentaacetic acid (DTPA) extracted phyto-available Cd. The total soil Cd content reductions were 15.20% and 26.58% for groups A and B, respectively, and electric field applications resulted in a 74.87% increase of soil total Cd removal. The electric energy consumption was only 2.17 kWh/m 3 for group B. Drainage by gravity contributed to > 90% of the overall soil dewatering capacity. Compared to conventional electro-kinetic technology, excellent and fast soil water drainage resulted in negligible hydrogen ion (H + ) and hydroxide ion (OH - ) accumulation at nearby electrode zones, which addressed the challenge of anode corrosion and cathode precipitation of soil metals. External addition of FeCl 3 and CaCl 2 caused soil Fe and Cl residuals and led to 4.33-7.59% and 139-172% acceptable augments in soil total Fe and Cl content, correspondingly, if compared to original untreated soils. Therefore, the novel soil remediation equipment developed based on EKG can be regarded as a promising new in situ technology for thoroughly isolating metals from large-scale paddy soil fields.

  14. Electrical characterization of single cells using polysilicon wire ion sensor in an isolation window.

    Science.gov (United States)

    Wu, You-Lin; Hsu, Po-Yen; Hsu, Chung-Ping; Wang, Chih-Cheng; Lee, Li-Wen; Lin, Jing-Jenn

    2011-10-01

    A polysilicon wire (PSW) sensor can detect the H(+) ion density (pH value) of the medium coated on its surface, and different cells produce different extracellular acidification and hence different H(+) ion densities. Based on this, we used a PSW sensor in combination with a mold-cast polydimethylsiloxane (PDMS) isolation window to detect the adhesion, apoptosis and extracellular acidification of single normal cells and single cancer cells. Single living human normal cells WI38, MRC5, and BEAS-2B as well as non-small-cell lung cancer (NSCLC) cells A549, H1299, and CH27 were cultivated separately inside the isolation window. The current flowing through the PSW channel was measured. From the PSW channel current change as a function of time, we determined the cell adhesion time by observing the time required for the current change to saturate, since a stable extracellular ion density was established after the cells were completely adhered to the PSW surface. The apoptosis of cells can also be determined when the channel current change drops to zero. We found that all the NSCLC cells had a higher channel current change and hence a lower pH value than the normal cells anytime after they were seeded. The corresponding average pH values were 5.86 for A549, 6.00 for H1299, 6.20 for CH27, 6.90 for BEAS-2B, 6.96for MRC5, and 7.02 for WI38, respectively, after the cells were completely adhered to the PSW surface. Our results show that NSCLC cells have a stronger cell-substrate adhesion and a higher extracellular acidification rate than normal cells.

  15. An Inert Continuous Microreactor for the Isolation and Analysis of a Single Microbial Cell

    Directory of Open Access Journals (Sweden)

    Katrin Rosenthal

    2015-11-01

    Full Text Available Studying biological phenomena of individual cells is enabled by matching the scales of microbes and cultivation devices. We present a versatile, chemically inert microfluidic lab-on-a-chip (LOC device for biological and chemical analyses of isolated microorganisms. It is based on the Envirostat concept and guarantees constant environmental conditions. A new manufacturing process for direct fusion bonding chips with functional microelectrodes for selective and gentle cell manipulation via negative dielectrophoresis (nDEP was generated. The resulting LOC system offered a defined surface chemistry and exceptional operational stability, maintaining its structural integrity even after harsh chemical treatment. The microelectrode structures remained fully functional after thermal bonding and were proven to be efficient for single-cell trapping via nDEP. The microfluidic network consisted solely of glass, which led to enhanced chip reusability and minimized interaction of the material with chemical and biological compounds. We validated the LOC for single-cell studies with the amino acid secreting bacterium Corynebacterium glutamicum. Intracellular l-lysine production dynamics of individual bacteria were monitored based on a genetically encoded fluorescent nanosensor. The results demonstrate the applicability of the presented LOC for pioneering chemical and biological studies, where robustness and chemically inert surfaces are crucial parameters for approaching fundamental biological questions at a single-cell level.

  16. Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques.

    Science.gov (United States)

    Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

    2014-09-26

    The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND's size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

  17. Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

    Science.gov (United States)

    Bolker, Asaf; Saguy, Cecile; Kalish, Rafi

    2014-09-01

    The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques.

  18. Transfer doping of single isolated nanodiamonds, studied by scanning probe microscopy techniques

    International Nuclear Information System (INIS)

    Bolker, Asaf; Kalish, Rafi; Saguy, Cecile

    2014-01-01

    The transfer doping of diamond surfaces has been applied in various novel two-dimensional electronic devices. Its extension to nanodiamonds (ND) is essential for ND-based applications in many fields. In particular, understanding the influence of the crystallite size on transfer doping is desirable. Here, we report the results of a detailed study of the electronic energetic band structure of single, isolated transfer-doped nanodiamonds with nanometric resolution using a combination of scanning tunneling spectroscopy and Kelvin force microscopy measurements. The results show how the band gap, the valence band maximum, the electron affinity and the work function all depend on the ND’s size and nanoparticle surface properties. The present analysis, which combines information from both scanning tunneling spectroscopy and Kelvin force microscopy, should be applicable to any nanoparticle or surface that can be measured with scanning probe techniques. (paper)

  19. New Method to Disaggregate and Analyze Single Isolated Helminthes Cells Using Flow Cytometry: Proof of Concept

    Directory of Open Access Journals (Sweden)

    Karen Nava-Castro

    2011-01-01

    Full Text Available In parasitology, particularly in helminthes studies, several methods have been used to look for the expression of specific molecules, such as RT-PCR, western blot, 2D-electrophoresis, and microscopy, among others. However, these methods require homogenization of the whole helminth parasite, preventing evaluation of individual cells or specific cell types in a given parasite tissue or organ. Also, the extremely high interaction between helminthes and host cells (particularly immune cells is an important point to be considered. It is really hard to obtain fresh parasites without host cell contamination. Then, it becomes crucial to determine that the analyzed proteins are exclusively from parasitic origin, and not a consequence of host cell contamination. Flow cytometry is a fluorescence-based technique used to evaluate the expression of extra-and intracellular proteins in different type cells, including protozoan parasites. It also allows the isolation and recovery of single-cell populations. Here, we describe a method to isolate and obtain purified helminthes cells.

  20. Typing of canine parvovirus isolates using mini-sequencing based single nucleotide polymorphism analysis.

    Science.gov (United States)

    Naidu, Hariprasad; Subramanian, B Mohana; Chinchkar, Shankar Ramchandra; Sriraman, Rajan; Rana, Samir Kumar; Srinivasan, V A

    2012-05-01

    The antigenic types of canine parvovirus (CPV) are defined based on differences in the amino acids of the major capsid protein VP2. Type specificity is conferred by a limited number of amino acid changes and in particular by few nucleotide substitutions. PCR based methods are not particularly suitable for typing circulating variants which differ in a few specific nucleotide substitutions. Assays for determining SNPs can detect efficiently nucleotide substitutions and can thus be adapted to identify CPV types. In the present study, CPV typing was performed by single nucleotide extension using the mini-sequencing technique. A mini-sequencing signature was established for all the four CPV types (CPV2, 2a, 2b and 2c) and feline panleukopenia virus. The CPV typing using the mini-sequencing reaction was performed for 13 CPV field isolates and the two vaccine strains available in our repository. All the isolates had been typed earlier by full-length sequencing of the VP2 gene. The typing results obtained from mini-sequencing matched completely with that of sequencing. Typing could be achieved with less than 100 copies of standard plasmid DNA constructs or ≤10¹ FAID₅₀ of virus by mini-sequencing technique. The technique was also efficient for detecting multiple types in mixed infections. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Assignment of Streptococcus agalactiae isolates to clonal complexes using a small set of single nucleotide polymorphisms.

    Science.gov (United States)

    Honsa, Erin; Fricke, Thomas; Stephens, Alex J; Ko, Danny; Kong, Fanrong; Gilbert, Gwendolyn L; Huygens, Flavia; Giffard, Philip M

    2008-08-19

    Streptococcus agalactiae (Group B Streptococcus (GBS)) is an important human pathogen, particularly of newborns. Emerging evidence for a relationship between genotype and virulence has accentuated the need for efficient and well-defined typing methods. The objective of this study was to develop a single nucleotide polymorphism (SNP) based method for assigning GBS isolates to multilocus sequence typing (MLST)-defined clonal complexes. It was found that a SNP set derived from the MLST database on the basis of maximization of Simpsons Index of Diversity provided poor resolution and did not define groups concordant with the population structure as defined by eBURST analysis of the MLST database. This was interpreted as being a consequence of low diversity and high frequency horizontal gene transfer. Accordingly, a different approach to SNP identification was developed. This entailed use of the "Not-N" bioinformatic algorithm that identifies SNPs diagnostic for groups of known sequence variants, together with an empirical process of SNP testing. This yielded a four member SNP set that divides GBS into 10 groups that are concordant with the population structure. A fifth SNP was identified that increased the sensitivity for the clinically significant clonal complex 17 to 100%. Kinetic PCR methods for the interrogation of these SNPs were developed, and used to genotype 116 well characterized isolates. A five SNP method for dividing GBS into biologically valid groups has been developed. These SNPs are ideal for high throughput surveillance activities, and combining with more rapidly evolving loci when additional resolution is required.

  2. Genotyping of Single Nucleotide Polymorphisms in DNA Isolated from Serum Using Sequenom MassARRAY Technology.

    Directory of Open Access Journals (Sweden)

    Tess V Clendenen

    Full Text Available Large epidemiologic studies have the potential to make valuable contributions to the assessment of gene-environment interactions because they prospectively collected detailed exposure data. Some of these studies, however, have only serum or plasma samples as a low quantity source of DNA.We examined whether DNA isolated from serum can be used to reliably and accurately genotype single nucleotide polymorphisms (SNPs using Sequenom multiplex SNP genotyping technology. We genotyped 81 SNPs using samples from 158 participants in the NYU Women's Health Study. Each participant had DNA from serum and at least one paired DNA sample isolated from a high quality source of DNA, i.e. clots and/or cell precipitates, for comparison.We observed that 60 of the 81 SNPs (74% had high call frequencies (≥95% using DNA from serum, only slightly lower than the 85% of SNPs with high call frequencies in DNA from clots or cell precipitates. Of the 57 SNPs with high call frequencies for serum, clot, and cell precipitate DNA, 54 (95% had highly concordant (>98% genotype calls across all three sample types. High purity was not a critical factor to successful genotyping.Our results suggest that this multiplex SNP genotyping method can be used reliably on DNA from serum in large-scale epidemiologic studies.

  3. Gating of the two-pore cation channel AtTPC1 in the plant vacuole is based on a single voltage-sensing domain.

    Science.gov (United States)

    Jaślan, D; Mueller, T D; Becker, D; Schultz, J; Cuin, T A; Marten, I; Dreyer, I; Schönknecht, G; Hedrich, R

    2016-09-01

    The two-pore cation channel TPC1 operates as a dimeric channel in animal and plant endomembranes. Each subunit consists of two homologous Shaker-like halves, with 12 transmembrane domains in total (S1-S6, S7-S12). In plants, TPC1 channels reside in the vacuolar membrane, and upon voltage stimulation, give rise to the well-known slow-activating SV currents. Here, we combined bioinformatics, structure modelling, site-directed mutagenesis, and in planta patch clamp studies to elucidate the molecular mechanisms of voltage-dependent channel gating in TPC1 in its native plant background. Structure-function analysis of the Arabidopsis TPC1 channel in planta confirmed that helix S10 operates as the major voltage-sensing site, with Glu450 and Glu478 identified as possible ion-pair partners for voltage-sensing Arg537. The contribution of helix S4 to voltage sensing was found to be negligible. Several conserved negative residues on the luminal site contribute to calcium binding, stabilizing the closed channel. During evolution of plant TPC1s from two separate Shaker-like domains, the voltage-sensing function in the N-terminal Shaker-unit (S1-S4) vanished. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  4. Quantitative and Isolated Measurement of Far-Field Light Scattering by a Single Nanostructure

    Science.gov (United States)

    Kim, Donghyeong; Jeong, Kwang-Yong; Kim, Jinhyung; Ee, Ho-Seok; Kang, Ju-Hyung; Park, Hong-Gyu; Seo, Min-Kyo

    2017-11-01

    Light scattering by nanostructures has facilitated research on various optical phenomena and applications by interfacing the near fields and free-propagating radiation. However, direct quantitative measurement of far-field scattering by a single nanostructure on the wavelength scale or less is highly challenging. Conventional back-focal-plane imaging covers only a limited solid angle determined by the numerical aperture of the objectives and suffers from optical aberration and distortion. Here, we present a quantitative measurement of the differential far-field scattering cross section of a single nanostructure over the full hemisphere. In goniometer-based far-field scanning with a high signal-to-noise ratio of approximately 27.4 dB, weak scattering signals are efficiently isolated and detected under total-internal-reflection illumination. Systematic measurements reveal that the total and differential scattering cross sections of a Au nanorod are determined by the plasmonic Fabry-Perot resonances and the phase-matching conditions to the free-propagating radiation, respectively. We believe that our angle-resolved far-field measurement scheme provides a way to investigate and evaluate the physical properties and performance of nano-optical materials and phenomena.

  5. Characterization of viruses infecting potato plants from a single location in Shetland, an isolated scottish archipelago

    DEFF Research Database (Denmark)

    Mortensen, R.J.; Shen, Xinyi; Reid, Alex

    2010-01-01

    , as were 29 Scottish mainland isolates of the same four potato virus species, and these 58 isolates were compared to previously published sequence data. This has allowed the characterization of viruses from a relatively isolated location, where there is little production of ware potatoes and no seed potato...... production. Phylogenetic homogeneity of the Shetland isolates of PVS and PVV was apparent. PVX was more heterogeneous, and Shetland isolates cluster with the Scottish isolates in a group which includes Asian and European isolates. For PVA, the majority of the Shetland and Scottish mainland isolates formed...... a predominantly Scottish grouping, with the remaining Shetland and Scottish mainland isolates clustering with a previously characterized Scottish isolate. There were three main groups of PVA, of which the Scottish grouping was the only one which did not have a fully characterized representative. To extend...

  6. Load dependency in force-length relations in isolated single cardiomyocytes.

    Science.gov (United States)

    Iribe, Gentaro; Kaneko, Toshiyuki; Yamaguchi, Yohei; Naruse, Keiji

    2014-08-01

    The previously reported pressure-volume (PV) relationship in frog hearts shows that end-systolic PV relation (ESPVR) is load dependent, whereas ESPVR in canine hearts is load independent. To study intrinsic cardiac mechanics in detail, it is desirable to study mechanics in a single isolated cardiomyocyte that is free from interstitial connective tissue. Previous single cell mechanics studies used a pair of carbon fibers (CF) attached to the upper surface of opposite cell ends to stretch cells. These studies showed that end-systolic force-length (FL) relation (ESFLR) is load independent. However, the range of applicable mechanical load using the conventional technique is limited because of weak cell-CF attachment. Therefore, the behavior of ESFLR in single cells under physiologically possible conditions of greater load is not yet well known. To cover wider loading range, we contrived a new method to hold cell-ends more firmly using two pairs of CF attached to both upper and bottom surfaces of cells. The new method allowed stretching cells to 2.2 μm or more in end-diastolic sarcomere length. ESFLR virtually behaves in a load independent manner only with end-diastolic sarcomere length less than 1.95 μm. It exhibited clear load dependency with higher preload, especially with low afterload conditions. Instantaneous cellular elastance curves showed that decreasing afterload enhanced relaxation and slowed time to peak elastance, as previously reported. A simulation study of a mathematical model with detailed description of thin filament activation suggested that velocity dependent thin filament inactivation is crucial for the observed load dependent behaviors and previously reported afterload dependent change in Ca(2+) transient shape. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Assignment of Streptococcus agalactiae isolates to clonal complexes using a small set of single nucleotide polymorphisms

    Directory of Open Access Journals (Sweden)

    Gilbert Gwendolyn L

    2008-08-01

    Full Text Available Abstract Background Streptococcus agalactiae (Group B Streptococcus (GBS is an important human pathogen, particularly of newborns. Emerging evidence for a relationship between genotype and virulence has accentuated the need for efficient and well-defined typing methods. The objective of this study was to develop a single nucleotide polymorphism (SNP based method for assigning GBS isolates to multilocus sequence typing (MLST-defined clonal complexes. Results It was found that a SNP set derived from the MLST database on the basis of maximisation of Simpsons Index of Diversity provided poor resolution and did not define groups concordant with the population structure as defined by eBURST analysis of the MLST database. This was interpreted as being a consequence of low diversity and high frequency horizontal gene transfer. Accordingly, a different approach to SNP identification was developed. This entailed use of the "Not-N" bioinformatic algorithm that identifies SNPs diagnostic for groups of known sequence variants, together with an empirical process of SNP testing. This yielded a four member SNP set that divides GBS into 10 groups that are concordant with the population structure. A fifth SNP was identified that increased the sensitivity for the clinically significant clonal complex 17 to 100%. Kinetic PCR methods for the interrogation of these SNPs were developed, and used to genotype 116 well characterized isolates. Conclusion A five SNP method for dividing GBS into biologically valid groups has been developed. These SNPs are ideal for high throughput surveillance activities, and combining with more rapidly evolving loci when additional resolution is required.

  8. Reliable genotyping of the koala (Phascolarctos cinereus) using DNA isolated from a single faecal pellet.

    Science.gov (United States)

    Wedrowicz, Faye; Karsa, Mawar; Mosse, Jennifer; Hogan, Fiona E

    2013-07-01

    The koala, an Australian icon, has been added to the threatened species list. Rationale for the listing includes proposed declines in population size, threats to populations (e.g. disease) and loss and fragmentation of habitat. There is now an urgent need to obtain accurate data to assess the status of koala populations in Australia, to ensure the long-term viability of this species. Advances in genetic techniques have enabled DNA analysis to study and inform the management of wild populations; however, sampling of individual koalas is difficult in tall, often remote, eucalypt forest. The collection of faecal pellets (scats) from the forest floor presents an opportunistic sampling strategy, where DNA can be collected without capturing or even sighting an individual. Obtaining DNA via noninvasive sampling can be used to rapidly sample a large proportion of a population; however, DNA from noninvasively collected samples is often degraded. Factors influencing DNA quality and quantity include environmental exposure, diet and methods of sample collection, storage and DNA isolation. Reduced DNA quality and quantity can introduce genotyping errors and provide inaccurate DNA profiles, reducing confidence in the ability of such data to inform management/conservation strategies. Here, we present a protocol that produces a reliable individual koala genotype from a single faecal pellet and highlight the importance of optimizing DNA isolation and analysis for the species of interest. This method could readily be adapted for genetic studies of mammals other than koalas, particularly those whose diet contains high proportions of volatile materials that are likely to induce DNA damage. © 2013 John Wiley & Sons Ltd.

  9. Material science studies on the formation and growth of pores in the production and creep of single-crystal nickel-based superalloys; Werkstoffwissenschaftliche Untersuchungen zur Bildung und zum Wachstum von Poren bei der Herstellung und beim Kriechen einkristalliner Nickelbasis-Superlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Heinrich Joergen

    2015-02-20

    Single crystal Ni-base superalloys (SX) are used for blades in fossil fuel fired power plants and aero engines. Here they have to withstand high mechanical stresses at temperatures close to their melting point. The blades are manufactured by a Bridgman type of directional solidification, followed by a multiple step heat treatment. During the dendritic solidification, pores can form due to undissolved gas, macroshrinkage by inadequate gating and microshrinkage caused by poor feeding between dendrites. Additional pores can form in the interdendritic regions during the multiple step heat treatment which follows solidification. It is believed, that these pores form on the basis of a Kirkendall effect which accounts for the fast diffusion of Al atoms away from microstructural regions with non-equilibrium γ/γ' eutectic. During creep, pores can grow and change their shapes. It has been shown, that during creep in the high temperature / low stress regime new pores form, which are smaller than those pores that can be found in the undeformed material. In the present work, the evolution of porosity in the single crystal Ni-base superalloy ERBO/1 during processing and creep is investigated. Quantitative microstructural analyses were performed on metallographic cross sections. Sampling fields of 4500 x 1000 μm{sup 2} were investigated by using a combination of scanning electron microscopy with quantitative image analysis. Interrupted creep tests with a miniature tensile creep specimen were performed with load direction parallel to left angle 100 right angle and left angle 110 right angle direction, respectively. Pore parameters (area, perimeter, Feret's diameter) for individual pores were obtained and two form factors were introduced. The evolution of the compiled statistical distributions of pore parameters and shape factors are discussed. The results are compared to recent findings by Link et al., 2006 and Maelzer et al., 2007. In the present study it was shown

  10. From isolated light-harvesting complexes to the thylakoid membrane: a single-molecule perspective

    Science.gov (United States)

    Gruber, J. Michael; Malý, Pavel; Krüger, Tjaart P. J.; Grondelle, Rienk van

    2018-01-01

    The conversion of solar radiation to chemical energy in plants and green algae takes place in the thylakoid membrane. This amphiphilic environment hosts a complex arrangement of light-harvesting pigment-protein complexes that absorb light and transfer the excitation energy to photochemically active reaction centers. This efficient light-harvesting capacity is moreover tightly regulated by a photoprotective mechanism called non-photochemical quenching to avoid the stress-induced destruction of the catalytic reaction center. In this review we provide an overview of single-molecule fluorescence measurements on plant light-harvesting complexes (LHCs) of varying sizes with the aim of bridging the gap between the smallest isolated complexes, which have been well-characterized, and the native photosystem. The smallest complexes contain only a small number (10-20) of interacting chlorophylls, while the native photosystem contains dozens of protein subunits and many hundreds of connected pigments. We discuss the functional significance of conformational dynamics, the lipid environment, and the structural arrangement of this fascinating nano-machinery. The described experimental results can be utilized to build mathematical-physical models in a bottom-up approach, which can then be tested on larger in vivo systems. The results also clearly showcase the general property of biological systems to utilize the same system properties for different purposes. In this case it is the regulated conformational flexibility that allows LHCs to switch between efficient light-harvesting and a photoprotective function.

  11. Genotyping single spore isolates of a Pasteuria penetrans population occurring in Florida using SNP-based markers

    Science.gov (United States)

    The aim of this study was to examine genotypic variation and virulence characteristics of a population of bacterial parasite of root-knot nematode (RKN), Pasteuria penetrans, isolated from Florida. Six single spore lines (ssp), 16ssp, 17ssp, 18ssp, 25ssp, 26ssp, and 30ssp were generated by infecting...

  12. Observation of Single Isolated Electrons of High Transverse Momentum in Events with Missing Transverse Energy at the CERN pp Collider

    DEFF Research Database (Denmark)

    Banner, M.; Kofoed-Hansen, O.

    1983-01-01

    We report the results of a search for single isolated electrons of high transverse momentum at the CERN collider. Above 15 GeV/c, four events are found having large missing transverse energy along a direction opposite in azimuth to that of the high-pT electron. Both the configuration of the events...

  13. High Performance Harmonic Isolation By Means of The Single-phase Series Active Filter Employing The Waveform Reconstruction Method

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    current sampling delay reduction method (SDRM), a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous reference frame based methods. The analytical, simulation, and experimental studies of a 2...

  14. Single-stage three-phase AC to DC conversion with isolation and Bi-directional power flow

    NARCIS (Netherlands)

    Vermulst, B.J.D.; Duarte, J.L.; Wijnands, C.G.E.; Lomonova, E.A.

    2014-01-01

    An approach for three-phase AC to DC conversion is proposed, which consists of a single-stage while offering galvanic isolation, soft-switching, bi-directional power flow and a significant reduction of inductive and capacitive energy storage. Two elements enable this approach, namely a neutral

  15. Isolation of Microarray-Grade Total RNA, MicroRNA, and DNA from a Single PAXgene Blood RNA Tube

    DEFF Research Database (Denmark)

    Kruhøffer, Mogens; Andersen, Lars Dyrskjøt; Voss, Thorsten

    2007-01-01

    We have developed a procedure for isolation of microRNA and genomic DNA in addition to total RNA from whole blood stabilized in PAXgene Blood RNA tubes. The procedure is based on automatic extraction on a BioRobot MDx and includes isolation of DNA from a fraction of the stabilized blood...... and recovery of small RNA species that are otherwise lost. The procedure presented here is suitable for large-scale experiments and is amenable to further automation. Procured total RNA and DNA was tested using Affymetrix Expression and single-nucleotide polymorphism GeneChips, respectively, and isolated micro......RNA was tested using spotted locked nucleic acid-based microarrays. We conclude that the yield and quality of total RNA, microRNA, and DNA from a single PAXgene blood RNA tube is sufficient for downstream microarray analysis....

  16. Single Cystosorus Isolate Production and Restriction Fragment Length Polymorphism Characterization of the Obligate Biotroph Spongospora subterranea f. sp. subterranea.

    Science.gov (United States)

    Qu, Xinshun; Christ, Barbara J

    2006-10-01

    ABSTRACT Spongospora subterranea f. sp. subterranea causes powdery scab in potatoes and is distributed worldwide. Genetic studies of this pathogen have been hampered due, in part, to its obligate parasitism and the lack of molecular markers for this pathogen. In this investigation, a single cystosorus inoculation technique was developed to produce large amounts of S. subterranea f. sp. subterranea plasmodia or zoosporangia in eastern black nightshade (Solanum ptycanthum) roots from which DNA was extracted. Cryopreservation of zoosporangia was used for long-term storage of the isolates. S. subterranea f. sp. subterranea-specific restriction fragment length polymorphism (RFLP) markers were developed from randomly amplified polymorphic DNA (RAPD) fragments. Cystosori of S. subterranea f. sp. subterranea were used for RAPD assays and putative pathogen-specific RAPD fragments were cloned and sequenced. The fragments were screened for specificity by Southern hybridization and subsequent DNA sequence BLAST search. Four polymorphic S. subterranea f. sp. subterranea-specific probes containing repetitive elements, and one containing single copy DNA were identified. These RFLP probes were then used to analyze 24 single cystosorus isolates derived from eight geographic locations in the United States and Canada. Genetic variation was recorded among, but not within, geographic locations. Cluster analysis separated the isolates into two major groups: group I included isolates originating from western North America, with the exception of those from Colorado, and group II included isolates originating from eastern North America and from Colorado. The techniques developed in this study, i.e., production of single cystosorus isolates of S. subterranea f. sp. subterranea and development of RFLP markers for this pathogen, provide methods to further study the genetic structure of S. subterranea f. sp. subterranea.

  17. Mycobacterium tuberculosis Isolates from Single Outpatient Clinic in Panama City Exhibit Wide Genetic Diversity

    Science.gov (United States)

    Sambrano, Dilcia; Correa, Ricardo; Almengor, Pedro; Domínguez, Amada; Vega, Silvio; Goodridge, Amador

    2014-01-01

    Understanding Mycobacterium tuberculosis biodiversity and transmission is significant for tuberculosis control. This short report aimed to determine the genetic diversity of M. tuberculosis isolates from an outpatient clinic in Panama City. A total of 62 M. tuberculosis isolates were genotyped by 12 loci mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) and Spoligotyping. Forty-five (72.6%) of the isolates showed unique MIRU-VNTR genotypes, and 13 (21%) of the isolates were grouped into four clusters. Four isolates showed polyclonal MIRU-VNTR genotypes. The MIRU-VNTR Hunter-Gaston discriminatory index reached 0.988. The Spoligotyping analysis revealed 16 M. tuberculosis families, including Latin American-Mediterranean, Harlem, and Beijing. These findings suggest a wide genetic diversity of M. tuberculosis isolates at one outpatient clinic. A detailed molecular epidemiology survey is now warranted, especially following second massive immigration for local Panama Canal expansion activities. PMID:24865686

  18. Single step biotransformation of corn oil phytosterols to boldenone by a newly isolated Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Mohamed Eisa

    2016-09-01

    Full Text Available A new potent Pseudomonas aeruginosa isolate capable for biotransformation of corn oil phytosterol (PS to 4-androstene-3, 17-dione (AD, testosterone (T and boldenone (BOL was identified by phenotypic analysis and 16S rRNA gene sequencing. Sequential statistical strategy was used to optimize the biotransformation process mainly concerning BOL using Factorial design and response surface methodology (RSM. The production of BOL in single step microbial biotransformation from corn oil phytosterols by P. aeruginosa was not previously reported. Results showed that the pH concentration of the medium, (NH42SO4 and KH2PO4 were the most significant factors affecting BOL production. By analyzing the statistical model of three-dimensional surface plot, BOL production increased from 36.8% to 42.4% after the first step of optimization, and the overall biotransformation increased to 51.9%. After applying the second step of the sequential statistical strategy BOL production increased to 53.6%, and the overall biotransformation increased to 91.9% using the following optimized medium composition (g/l distilled water (NH42SO4, 2; KH2PO4, 4; Na2HPO4. 1; MgSO4·7H2O, 0.3; NaCl, 0.1; CaCl2·2H2O, 0.1; FeSO4·7H2O, 0.001; ammonium acetate 0.001; Tween 80, 0.05%; corn oil 0.5%; 8-hydroxyquinoline 0.016; pH 8; 200 rpm agitation speed and incubation time 36 h at 30 °C. Validation experiments proved the adequacy and accuracy of model, and the results showed the predicted value agreed well with the experimental values.

  19. Isolation and characterization of anti c-met single chain fragment variable (scFv) antibodies.

    Science.gov (United States)

    Qamsari, Elmira Safaie; Sharifzadeh, Zahra; Bagheri, Salman; Riazi-Rad, Farhad; Younesi, Vahid; Abolhassani, Mohsen; Ghaderi, Sepideh Safaei; Baradaran, Behzad; Somi, Mohammad Hossein; Yousefi, Mehdi

    2017-12-01

    The receptor tyrosine kinase (RTK) Met is the cell surface receptor for hepatocyte growth factor (HGF) involved in invasive growth programs during embryogenesis and tumorgenesis. There is compelling evidence suggesting important roles for c-Met in colorectal cancer proliferation, migration, invasion, angiogenesis, and survival. Hence, a molecular inhibitor of an extracellular domain of c-Met receptor that blocks c-Met-cell surface interactions could be of great thera-peutic importance. In an attempt to develop molecular inhibitors of c-Met, single chain variable fragment (scFv) phage display libraries Tomlinson I + J against a specific synthetic oligopeptide from the extracellular domain of c-Met receptor were screened; selected scFv were then characterized using various immune techniques. Three c-Met specific scFv (ES1, ES2, and ES3) were selected following five rounds of panning procedures. The scFv showed specific binding to c-Met receptor, and significantly inhibited proliferation responses of a human colorectal carcinoma cell line (HCT-116). Moreover, anti- apoptotic effects of selected scFv antibodies on the HCT-116 cell line were also evaluated using Annexin V/PI assays. The results demonstrated rates of apoptotic cell death of 46.0, 25.5, and 37.8% among these cells were induced by use of ES1, ES2, and ES3, respectively. The results demonstrated ability to successfully isolate/char-acterize specific c-Met scFv that could ultimately have a great therapeutic potential in immuno-therapies against (colorectal) cancers.

  20. Isolation of Panels of Llama Single-Domain Antibody Fragments Binding All Nine Neuraminidase Subtypes of Influenza A Virus

    Directory of Open Access Journals (Sweden)

    Guus Koch

    2013-04-01

    Full Text Available Avian influenza A virus comprises sixteen hemagglutinin (HA and nine neuraminidase (NA subtypes (N1–N9. To isolate llama single-domain antibody fragments (VHHs against all N subtypes, four llamas were immunized with mixtures of influenza viruses. Selections using influenza virus yielded predominantly VHHs binding to the highly immunogenic HA and nucleoprotein. However, selection using enzymatically active recombinant NA (rNA protein enabled us to isolate NA binding VHHs. Some isolated VHHs cross-reacted to other N subtypes. These were subsequently used for the capture of N subtypes that could not be produced as recombinant protein (rN6 or were enzymatically inactive (rN1, rN5 in phage display selection, yielding novel VHHs. In total we isolated 188 NA binding VHHs, 64 of which were expressed in yeast. Most VHHs specifically recognize a single N subtype, but some VHHs cross-react with other N-subtypes. At least one VHH bound to all N subtypes, except N4, identifying a conserved antigenic site. Thus, this work (1 describes methods for isolating NA binding VHHs, (2 illustrates the suitability of llama immunization with multiple antigens for retrieving many binders against different antigens and (3 describes 64 novel NA binding VHHs, including a broadly reactive VHH, which can be used in various assays for influenza virus subtyping, detection or serology.

  1. Automated methods for single-stranded DNA isolation and dideoxynucleotide DNA sequencing reactions on a robotic workstation

    International Nuclear Information System (INIS)

    Mardis, E.R.; Roe, B.A.

    1989-01-01

    Automated procedures have been developed for both the simultaneous isolation of 96 single-stranded M13 chimeric template DNAs in less than two hours, and for simultaneously pipetting 24 dideoxynucleotide sequencing reactions on a commercially available laboratory workstation. The DNA sequencing results obtained by either radiolabeled or fluorescent methods are consistent with the premise that automation of these portions of DNA sequencing projects will improve the reproducibility of the DNA isolation and the procedures for these normally labor-intensive steps provides an approach for rapid acquisition of large amounts of high quality, reproducible DNA sequence data

  2. Experimental Investigation of a Base Isolation System Incorporating MR Dampers with the High-Order Single Step Control Algorithm

    Directory of Open Access Journals (Sweden)

    Weiqing Fu

    2017-03-01

    Full Text Available The conventional isolation structure with rubber bearings exhibits large deformation characteristics when subjected to infrequent earthquakes, which may lead to failure of the isolation layer. Although passive dampers can be used to reduce the layer displacement, the layer deformation and superstructure acceleration responses will increase in cases of fortification earthquakes or frequently occurring earthquakes. In addition to secondary damages and loss of life, such excessive displacement results in damages to the facilities in the structure. In order to overcome these shortcomings, this paper presents a structural vibration control system where the base isolation system is composed of rubber bearings with magnetorheological (MR damper and are regulated using the innovative control strategy. The high-order single-step algorithm with continuity and switch control strategies are applied to the control system. Shaking table test results under various earthquake conditions indicate that the proposed isolation method, compared with passive isolation technique, can effectively suppress earthquake responses for acceleration of superstructure and deformation within the isolation layer. As a result, this structural control method exhibits excellent performance, such as fast computation, generic real-time control, acceleration reduction and high seismic energy dissipation etc. The relative merits of the continuity and switch control strategies are also compared and discussed.

  3. Genome sequences of thirty Escherichia coli O157:H7 isolates recovered from a single dairy farm and its associated off-site heifer raising facility

    Science.gov (United States)

    Cattle are the primary reservoir of Escherichia coli O157:H7, the most frequently isolated serotype of enterohemorrhagic E. coli infections among humans in North America. To evaluate the diversity of E. coli O157:H7 isolates within a single dairy herd the genomes of 30 isolates collected over a 7-ye...

  4. Brief communication genotyping of Burkholderia pseudomallei revealed high genetic variability among isolates from a single population group

    OpenAIRE

    Zueter, Abdelrahman Mohammad; Rahman, Zaidah Abdul; Yean, Chan Yean; Harun, Azian

    2015-01-01

    Burkholderia pseudomallei is a soil dwelling Gram-negative bacteria predominates in Southeast Asia zone and the tropical part of Australia. Genetic diversity has been explored among various populations and environments worldwide. To date, little data is available on MLST profiling of clinical B. pseudomallei isolates in peninsular Malaysia. In this brief report, thirteen culture positive B. pseudomallei cases collected from a single population of Terengganu state in the Western Peninsular Mal...

  5. Evaluation of a Single Procedure Allowing the Isolation of Enteropathogenic Yersinia along with Other Bacterial Enteropathogens from Human Stools

    Science.gov (United States)

    Savin, Cyril; Leclercq, Alexandre; Carniel, Elisabeth

    2012-01-01

    Enteropathogenic Yersinia are among the most frequent agents of human diarrhea in temperate and cold countries. However, the incidence of yersiniosis is largely underestimated because of the peculiar growth characteristics of pathogenic Yersinia, which make their isolation from poly-contaminated samples difficult. The use of specific procedures for Yersinia isolation is required, but is expensive and time consuming, and therefore is not systematically performed in clinical pathology laboratories. A means to circumvent this problem would be to use a single procedure for the isolation of all bacterial enteropathogens. Since the Statens Serum Institut enteric medium (SSI) has been reported to allow the growth at 37°C of most Gram-negative bacteria, including Yersinia, our study aimed at evaluating its performances for Yersinia isolation, as compared to the commonly used Yersinia-specific semi-selective Cefsulodin-Irgasan-Novobiocin medium (CIN) incubated at 28°C. Our results show that Yersinia pseudotuberculosis growth was strongly inhibited on SSI at 37°C, and therefore that this medium is not suitable for the isolation of this species. All Yersinia enterocolitica strains tested grew on SSI, while some non-pathogenic Yersinia species were inhibited. The morphology of Y. enterocolitica colonies on SSI allowed their differentiation from various other Gram-negative bacteria commonly isolated from stool samples. However, in artificially contaminated human stools, the recovery of Y. enterocolitica colonies on SSI at 37°C was difficult and was 3 logs less sensitive than on CIN at 28°C. Therefore, despite its limitations, the use of a specific procedure (CIN incubated at 28°C) is still required for an efficient isolation of enteropathogenic Yersinia from stools. PMID:22911756

  6. The pore space scramble

    Science.gov (United States)

    Gormally, Alexandra; Bentham, Michelle; Vermeylen, Saskia; Markusson, Nils

    2015-04-01

    Climate change and energy security continue to be the context of the transition to a secure, affordable and low carbon energy future, both in the UK and beyond. This is reflected in for example, binding climate policy targets at the EU level, the introduction of renewable energy targets, and has also led to an increasing interest in Carbon Capture and Storage (CCS) technology with its potential to help mitigate against the effects of CO2 emissions from fossil fuel burning. The UK has proposed a three phase strategy to integrate CCS into its energy system in the long term focussing on off-shore subsurface storage (DECC, 2014). The potential of CCS therefore, raises a number of challenging questions and issues surrounding the long-term storage of CO2 captured and injected into underground spaces and, alongside other novel uses of the subsurface, contributes to opening a new field for discussion on the governance of the subsurface. Such 'novel' uses of the subsurface have lead to it becoming an increasingly contested space in terms of its governance, with issues emerging around the role of ownership, liability and property rights of subsurface pore space. For instance, questions over the legal ownership of pore space have arisen with ambiguity over the legal standpoint of the surface owner and those wanting to utilise the pore space for gas storage, and suggestions of whether there are depths at which legal 'ownership' becomes obsolete (Barton, 2014). Here we propose to discuss this 'pore space scramble' and provide examples of the competing trajectories of different stakeholders, particularly in the off-shore context given its priority in the UK. We also propose to highlight the current ambiguity around property law of pore space in the UK with reference to approaches currently taken in different national contexts. Ultimately we delineate contrasting models of governance to illustrate the choices we face and consider the ethics of these models for the common good

  7. Immediate primary anastomosis for isolated oesophageal atresia: A single-centre experience

    Directory of Open Access Journals (Sweden)

    Ibrahim Uygun

    2015-01-01

    Full Text Available Background: Isolated oesophageal atresia without tracheo-oesophageal fistula represents a major challenge for most paediatric surgeons. Here, we present our experience with six neonates with isolated oesophageal atresia who successfully underwent immediate primary anastomosis using multiple Livaditis circular myotomy. Materials and Methods: All six neonates were gross type A isolated oesophageal atresia (6%, from among 102 neonates with oesophageal atresia, treated between January 2009 and December 2013. Five neonates were female; one was male. The mean birth weight was 2300 (range 1700-3100 g. Results: All six neonates successfully underwent immediate primary anastomosis using multiple myotomies (mean 3; range 2-4 within 10 (median 3 days after birth. The gap under traction ranged from 6 to 7 cm. One neonate died of a major cardiac anomaly. Another neonate was lost to follow-up after being well for 3 months. Three anastomotic strictures were treated with balloon dilatation, and four anastomotic leaks were treated conservatively. The mean duration of follow-up was 33 months. Conclusions: To treat isolated oesophageal atresia, an immediate primary anastomosis can be achieved using multiple myotomies. Although, this approach is associated with high complication rates, as are other similar approaches, these complications can be overcome.

  8. The Perinatal Outcomes of Asymptomatic Isolated Single Umbilical Artery in Full-term Neonates

    Directory of Open Access Journals (Sweden)

    Shu-Chi Mu

    2008-12-01

    Conclusion: SUA is a relatively rare finding. When a SUA is identified, the routine check of karyotyping and kidney sonography for possible chromosome and associated renal anomalies may be unnecessary. According to lighter placental weight probably causing the higher incidence of small for gestational age (SGA, pregnancies with isolated SUA should be carefully monitored for evidence of fetal growth restriction.

  9. A method for the isolation and characterization of functional murine monoclonal antibodies by single B cell cloning.

    Science.gov (United States)

    Carbonetti, Sara; Oliver, Brian G; Vigdorovich, Vladimir; Dambrauskas, Nicholas; Sack, Brandon; Bergl, Emilee; Kappe, Stefan H I; Sather, D Noah

    2017-09-01

    Monoclonal antibody technologies have enabled dramatic advances in immunology, the study of infectious disease, and modern medicine over the past 40years. However, many monoclonal antibody discovery procedures are labor- and time-intensive, low efficiency, and expensive. Here we describe an optimized mAb discovery platform for the rapid and efficient isolation, cloning and characterization of monoclonal antibodies in murine systems. In this platform, antigen-binding splenic B cells from immunized mice are isolated by FACS and cocultured with CD40L positive cells to induce proliferation and mAb production. After 12days of coculture, cell culture supernatants are screened for antigen, and IgG positivity and RNA is isolated for reverse-transcription. Positive-well cDNA is then amplified by PCR and the resulting amplicons can be cloned into ligation-independent expression vectors, which are then used directly to transfect HEK293 cells for recombinant antibody production. After 4days of growth, conditioned medium can be screened using biolayer interferometry for antigen binding and affinity measurements. Using this method, we were able to isolate six unique, functional monoclonal antibodies against an antigen of the human malaria parasite Plasmodium falciparum. Importantly, this method incorporates several important advances that circumvent the need for single-cell PCR, restriction cloning, and large scale protein production, and can be applied to a wide array of protein antigens. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. High Isolation Single-Pole Four-Throw RF MEMS Switch Based on Series-Shunt Configuration

    Directory of Open Access Journals (Sweden)

    Tejinder Singh

    2014-01-01

    Full Text Available This paper presents a novel design of single-pole four-throw (SP4T RF-MEMS switch employing both capacitive and ohmic switches. It is designed on high-resistivity silicon substrate and has a compact area of 1.06 mm2. The series or ohmic switches have been designed to provide low insertion loss with good ohmic contact. The pull-in voltage for ohmic switches is calculated to be 7.19 V. Shunt or capacitive switches have been used in each port to improve the isolation for higher frequencies. The proposed SP4T switch provides excellent RF performances with isolation better than 70.64 dB and insertion loss less than 0.72 dB for X-band between the input port and each output port.

  11. A Self-Reconstructing Algorithm for Single and Multiple-Sensor Fault Isolation Based on Auto-Associative Neural Networks

    Directory of Open Access Journals (Sweden)

    Hamidreza Mousavi

    2017-01-01

    Full Text Available Recently different approaches have been developed in the field of sensor fault diagnostics based on Auto-Associative Neural Network (AANN. In this paper we present a novel algorithm called Self reconstructing Auto-Associative Neural Network (S-AANN which is able to detect and isolate single faulty sensor via reconstruction. We have also extended the algorithm to be applicable in multiple fault conditions. The algorithm uses a calibration model based on AANN. AANN can reconstruct the faulty sensor using non-faulty sensors due to correlation between the process variables, and mean of the difference between reconstructed and original data determines which sensors are faulty. The algorithms are tested on a Dimerization process. The simulation results show that the S-AANN can isolate multiple faulty sensors with low computational time that make the algorithm appropriate candidate for online applications.

  12. Paired single cell co-culture microenvironments isolated by two-phase flow with continuous nutrient renewal.

    Science.gov (United States)

    Chen, Yu-Chih; Cheng, Yu-Heng; Kim, Hong Sun; Ingram, Patrick N; Nor, Jacques E; Yoon, Euisik

    2014-08-21

    Cancer-stromal cell interactions are a critical process in tumorigenesis. Conventional dish-based assays, which simply mix two cell types, have limitations in three aspects: 1) limited control of the cell microenvironment; 2) inability to study cell behavior in a single-cell manner; and 3) have difficulties in characterizing single cell behavior within a highly heterogeneous cell population (e.g. tumor). An innovative use of microfluidic technology is for improving the spatial resolution for single cell assays. However, it is challenging to isolate the paired interacting cells while maintaining nutrient renewal. In this work, two-phase flow was used as a simple isolation method, separating the microenvironment of each individual chamber. As nutrients in an isolated chamber are consumed by cells, media exchange is required. To connect the cell culture chamber to the media exchange layer, we demonstrated a 3D microsystem integration technique using vertical connections fabricated by deep reactive-ion etching (DRIE). Compared to previous approaches, the presented process allows area reduction of vertical connections by an order of magnitude, enabling compact 3D integration. A semi-permeable membrane was sandwiched between the cell culture layer and the media exchange layer. The selectivity of the semi-permeable membrane results in the retention of the signaling proteins within the chamber while allowing free diffusion of nutrients (e.g., glucose and amino acids). Thus, paracrine signals are accumulated inside the chamber without cross-talk between cells in other chambers. Utilizing these innovations, we co-cultured UM-SCC-1 (head and neck squamous cell carcinoma) cells and endothelial cells to simulate tumor proliferation enhancement in the vascular endothelial niche.

  13. Retrospective analysis of mortality and Candida isolates of 75 patients with candidemia: a single hospital experience

    Directory of Open Access Journals (Sweden)

    Hirano R

    2015-07-01

    Full Text Available Ryuichi Hirano,1 Yuichi Sakamoto,2 Kumiko Kudo,1 Motoki Ohnishi31Department of Pharmacy, Aomori Prefectural Central Hospital, Aomori, Japan; 2Laboratory Medicine and Blood transfusion, Aomori Prefectural Central Hospital, Aomori, Japan; 3General Medicine, Aomori Prefectural Central Hospital, Aomori, JapanAbstract: The mortality rate for candidemia is approximately 30%–60%. However, prognostic factors in patients with candidemia have not yet been elucidated in detail. The aim of the present study was to analyze prognostic factors for candidemia using the mortality rate and Candida isolates of patients with candidemia. Seventy-five patients with candidemia were analyzed between January 2007 and December 2013. The main outcome of this study was the 30-day mortality rate after the diagnosis of candidemia. The acute physiology and chronic health evaluation II score (APACHE II score was measured in 34 patients (45.3%. Odds ratios (ORs for death due to candidemia were analyzed using a multivariate stepwise logistic regression analysis. Twenty (26.6% patients died within 30 days of being diagnosed with candidemia. Non-survivors had a significantly higher APACHE II score (n=7, mean; 18.9±4.5 than that of survivors (n=27, mean; 14.0±5.0. Advanced age (OR =1.1, 95% confidence interval =1.01–1.23, P=0.04 was a significant risk factor for a high mortality rate, whereas removal of a central venous catheter (OR =0.03, 95% confidence interval =0.002–0.3, P=0.01 was associated with a lower mortality rate. Seventy-six Candida spp. were isolated from blood cultures: Candida albicans 28 (36.8%, Candida parapsilosis 23 (30.2%, Candida guilliermondii 16 (21.0%, Candida glabrata four (5.2%, Candida tropicalis two (2.6%, and Candida spp. three (3.9% that could not be identified. C. parapsilosis was the most frequently isolated species in younger patients (<65 years, whereas C. albicans was the most frequently isolated in elderly patients (≥65 years

  14. Stability of cell-free DNA from maternal plasma isolated following a single centrifugation step.

    Science.gov (United States)

    Barrett, Angela N; Thadani, Henna A; Laureano-Asibal, Cecille; Ponnusamy, Sukumar; Choolani, Mahesh

    2014-12-01

    Cell-free fetal DNA can be used for prenatal testing with no procedure-related risk to the fetus. However, yield of fetal DNA is low compared with maternal cell-free DNA fragments, resulting in technical challenges for some downstream applications. To maximize the fetal fraction, careful blood processing procedures are essential. We demonstrate that fetal fraction can be preserved using a single centrifugation step followed by postage of plasma to the laboratory for further processing. Digital PCR was used to quantify copies of total, maternal, and fetal DNA present in single-spun plasma at time points over a two-week period, compared with immediately processed double-spun plasma, with storage at room temperature, 4°C, and -80°C representing different postage scenarios. There was no significant change in total, maternal, or fetal DNA copy numbers when single-spun plasma samples were stored for up to 1 week at room temperature and 2 weeks at -80°C compared with plasma processed within 4 h. Following storage at 4°C no change in composition of cell-free DNA was observed. Single-spun plasma can be transported at room temperature if the journey is expected to take one week or less; shipping on dry ice is preferable for longer journeys. © 2014 John Wiley & Sons, Ltd.

  15. Single nucleotide polymorphism analysis of the enterocin P structural gene of Enterococcus faecium strains isolated from nonfermented animal foods.

    Science.gov (United States)

    Arlindo, Samuel; Calo, Pilar; Franco, Carlos; Prado, Marta; Cepeda, Alberto; Barros-Velázquez, Jorge

    2006-12-01

    The bacteriocins produced by two lactic acid bacteria isolated from nonfermented fresh meat and fish, respectively, and exhibiting a remarkable antilisterial activity, were characterized. Bacteriocinogenic strains were identified as Enterococcus faecium and the maximum bacteriocin production by both strains was detected in the stationary phase of growth. The activity against Listeria monocytogenes was maintained in pH range of 3-7 and was stable in both strains after heating at 100 or 121 degrees C. The genes coding for enterocin P were detected, isolated, and sequenced in both E. faecium strains. They exhibited DNA/DNA homology in the 87.1-97.2% range with respect to the other four enterocin P genes reported so far. Three single nucleotide polymorphism events, silent at the amino acid level, were detected at nucleotide positions 45 (G/A), 75 (A/G), and 90 (T/C) in E. faecium LHICA 28-4 and may explain the differences reported for those loci in other enterocin P-producing E. faecium strains. This work provides the first description of enterocin P-producing E. faecium strains in nonfermented foodstuffs and, in the case of E. faecium LHICA 51, the first report of an enterocin P-producing strain isolated from fish so far.

  16. Genotyping of single spore isolates of a Pasteuria penetrans population occurring in Florida using SNP-based markers.

    Science.gov (United States)

    Joseph, S; Schmidt, L M; Danquah, W B; Timper, P; Mekete, T

    2017-02-01

    To generate single spore lines of a population of bacterial parasite of root-knot nematode (RKN), Pasteuria penetrans, isolated from Florida and examine genotypic variation and virulence characteristics exist within the population. Six single spore lines (SSP), 16SSP, 17SSP, 18SSP, 25SSP, 26SSP and 30SSP were generated. Genetic variability was evaluated by comparing single-nucleotide polymorphisms (SNPs) in six protein-coding genes and the 16S rRNA gene. An average of one SNP was observed for every 69 bp in the 16S rRNA, whereas no SNPs were observed in the protein-coding sequences. Hierarchical cluster analysis of 16S rRNA sequences placed the clones into three distinct clades. Bio-efficacy analysis revealed significant heterogeneity in the level virulence and host specificity between the individual clones. The SNP markers developed to the 5' hypervariable region of the 16S rRNA gene may be useful in biotype differentiation within a population of P. penetrans. This study demonstrates an efficient method for generating single spore lines of P. penetrans and gives a deep insight into genetic heterogeneity and varying level of virulence exists within a population parasitizing a specific Meloidogyne sp. host. The results also suggest that the application of generalist spore lines in nematode management may achieve broad RKN control. © 2016 The Society for Applied Microbiology.

  17. Fe Isolated Single Atoms on S, N Codoped Carbon by Copolymer Pyrolysis Strategy for Highly Efficient Oxygen Reduction Reaction.

    Science.gov (United States)

    Li, Qiheng; Chen, Wenxing; Xiao, Hai; Gong, Yue; Li, Zhi; Zheng, Lirong; Zheng, Xusheng; Yan, Wensheng; Cheong, Weng-Chon; Shen, Rongan; Fu, Ninghua; Gu, Lin; Zhuang, Zhongbin; Chen, Chen; Wang, Dingsheng; Peng, Qing; Li, Jun; Li, Yadong

    2018-06-01

    Heteroatom-doped Fe-NC catalyst has emerged as one of the most promising candidates to replace noble metal-based catalysts for highly efficient oxygen reduction reaction (ORR). However, delicate controls over their structure parameters to optimize the catalytic efficiency and molecular-level understandings of the catalytic mechanism are still challenging. Herein, a novel pyrrole-thiophene copolymer pyrolysis strategy to synthesize Fe-isolated single atoms on sulfur and nitrogen-codoped carbon (Fe-ISA/SNC) with controllable S, N doping is rationally designed. The catalytic efficiency of Fe-ISA/SNC shows a volcano-type curve with the increase of sulfur doping. The optimized Fe-ISA/SNC exhibits a half-wave potential of 0.896 V (vs reversible hydrogen electrode (RHE)), which is more positive than those of Fe-isolated single atoms on nitrogen codoped carbon (Fe-ISA/NC, 0.839 V), commercial Pt/C (0.841 V), and most reported nonprecious metal catalysts. Fe-ISA/SNC is methanol tolerable and shows negligible activity decay in alkaline condition during 15 000 voltage cycles. X-ray absorption fine structure analysis and density functional theory calculations reveal that the incorporated sulfur engineers the charges on N atoms surrounding the Fe reactive center. The enriched charge facilitates the rate-limiting reductive release of OH* and therefore improved the overall ORR efficiency. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Brief communication genotyping of Burkholderia pseudomallei revealed high genetic variability among isolates from a single population group.

    Science.gov (United States)

    Zueter, Abdelrahman Mohammad; Rahman, Zaidah Abdul; Yean, Chan Yean; Harun, Azian

    2015-01-01

    Burkholderia pseudomallei is a soil dwelling Gram-negative bacteria predominates in Southeast Asia zone and the tropical part of Australia. Genetic diversity has been explored among various populations and environments worldwide. To date, little data is available on MLST profiling of clinical B. pseudomallei isolates in peninsular Malaysia. In this brief report, thirteen culture positive B. pseudomallei cases collected from a single population of Terengganu state in the Western Peninsular Malaysia and were confirmed by In-house TTS1-PCR. Isolates were subjected for multi-locus sequence typing (MLST) to explore their genotypic diversity and to investigate for possible clonal clustering of a certain sequence type. Patient's clinical information was examined to investigate for clinical correlation among the different genotypes. In spite of small sample set, MLST results indicated predictive results; considerable genotypic diversity, predominance and novelty among B. pseudomallei collected over a single geographically-located population in Malaysia. Massive genotypic heterogeneity was observed; 8 different sequence types with predominance of sequence type 54 and discovery of two novel sequence types. However, no clear pathogenomic or organ tropism clonal relationships were predicted.

  19. Fluorescence spectra of bithiophene and terthiophene single crystals and of their isolated molecules in cyclodextrin

    International Nuclear Information System (INIS)

    Gombojav, Bold; Namsrai, Nasanbat; Yoshinari, Takehisa; Nagasaka, Shin-ichiro; Itoh, Hiroki; Koyama, Kiyohito

    2004-01-01

    In order to examine the effect of subsumption space of β- and γ-cyclodextrin (CyD) on the photophysics of oligothiophenes, 2, 2'-bithiophene (BT) and 2, 2': 5', 2''-terthiophene (TT), the fluorescence spectra were compared with those of the single crystals (SC) at 15, 77 K and room temperature (RT). Both the numbers of BT included in β- and γ-CyD are twin (BT 2 ). The numbers of TT included in β- and γ-CyD are unit (TT 1 ) and twin (TT 2 ), respectively. Electronic excitation of BT encapsulated in β- and γ-CyD gives similar fluorescence spectra, showing bathochromic shift compared with that of BT single crystal, (BT) SC . The observation that the fluorescence spectra of encapsulated BT 2 are similar to the spectra of its THF solution suggests the configuration of BT 2 in β- and γ-CyD should be face-to-face configuration (BT 2 ) parrallel . On the contrary, TT in β- and in γ-CyD afford quite different fluorescence spectra. Encapsulated TT in β-CyD exhibits the hypsochromic shift of fluorescence maxima compared to that of TT single crystal, (TT) SC . While the bathochromically shifted fluorescence spectra of TT 2 in γ-CyD is also ascribed to the face-to-face configuration (TT 2 ) parallel as in the case of BT 2 in γ-CyD. Fluorescence spectra show the excited ground state complex of BT 2 and TT 2 in γ-CyD

  20. A pore water conductivity sensor

    NARCIS (Netherlands)

    Hilhorst, M.A.

    2001-01-01

    The electrical permittivity and conductivity of the bulk soil are a function of the permittivity and conductivity of the pore water. For soil water contents higher than 0.10 both functions are equal, facilitating in situ conductivity measurements of the pore water. A novel method is described, based

  1. Photochemistry and infrared spectrum of single-bridged diborane(5) anion isolated in solid argon

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Meng-Chen; Chin, Chih-Hao; Chen, Sian-Cong; Huang, Tzu-Ping [National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Chen, Hui-Fen; Huang, Wei-Jie [Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Wu, Yu-Jong, E-mail: yjw@nsrrc.org.tw [National Synchrotron Radiation Research Center (NSRRC), 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Department of Applied Chemistry, National Chiao Tung University, 1001, Ta-Hsueh Road, Hsinchu 30010, Taiwan (China)

    2016-08-21

    Three-center two-electron bonds are important for understanding electron-deficient molecules. To examine such a molecule, we produced a diborane(5) anion with a single-bridged structure upon electron bombardment during matrix deposition of Ar containing a small proportion of diborane(6). The diborane(5) anion was destroyed upon photolysis at 180, 220, 385, and 450 nm, but not at 532 nm. Moreover, the possible formation of neutral diborane(5) was observed upon photolysis at 385 and 450 nm, whereas neutral diborane(3) was observed upon photolysis at 180 and 220 nm. The observed line wavenumbers, relative intensities, and isotopic ratios of the diborane(5) anion agreed satisfactorily with those predicted by density functional theory calculations at the B3LYP/aug-cc-pVTZ level of theory. Thus, this method produced the boron hydride anion of interest with few other fragments, which enabled us to clearly identify the IR spectrum of the diborane(5) anion.

  2. Microencapsulated 3-dimensional sensor for the measurement of oxygen in single isolated pancreatic islets.

    Directory of Open Access Journals (Sweden)

    Wanyu Chen

    Full Text Available Oxygen consumption reflects multiple processes in pancreatic islets including mechanisms contributing to insulin secretion, oxidative stress and viability, providing an important readout in studies of islet function, islet viability and drug testing. Due to the scarcity, heterogeneity, and intrinsic kinetic properties of individual islets, it would be of great benefit to detect oxygen consumption by single islets. We present a novel method we have developed to image oxygen in single islets.Using a microfluidics system, individual islets and a fluorescent oxygen-sensitive dye were encased within a thin alginate polymer layer. Insulin secretion by the encapsulated islets was normal. Fluorescent signal from the encased dye, detected using a standard inverted fluorescence microscope and digital camera, was stable and proportional to the amount of oxygen in the media. When integrated into a perifusion system, the sensing system detected changes in response to metabolic substrates, mitochondrial poisons, and induced-oscillations. Glucose responses averaged 30.1±7.1% of the response to a metabolic inhibitor (cyanide, increases were observed in all cases (n = 6, and the system was able to resolve changes in oxygen consumption that had a period greater than 0.5 minutes. The sensing system operated similarly from 2-48 hours following encapsulation, and viability and function of the islets were not significantly affected by the encapsulation process.An oxygen-dependent dye situated around and within a pancreatic islet encapsulated by a thin layer of alginate was sensitive to changes in oxygen consumption, and was not harmful to the function or viability of islets over the course of two days. The microcapsule-based sensing method is particularly suited to assessing the effects of compounds (dose responses and time courses and chronic changes occurring over the course of days. The approach should be applicable to other cell types and dyes sensitive to other

  3. Peribulbar block in equine isolated heads. Development of a single needle technique and tomographic evaluation

    Directory of Open Access Journals (Sweden)

    vanessa rabbogliatti

    2017-05-01

    Full Text Available Peribulbar block (PPB has been used in humans as a safer alternative to retrobulbar block (RBB. PBB, depends on the diffusion of anaesthetic solution into the muscle across the connective tissue and it is performed introducing the needle within the extraconal space. The advantages are fewer complications and palpebral akinesia. In Veterinary Medicine few studies describe this technique in dogs (Ahn J 2013 and cats (Shilo-Benjamini et al. 2013. Based on literature the aim of the study is to determinate, in equine specimens, feasibility of inferior PBB with single needle injection, by using contrast medium (CM, and to evaluate thought Computed Tomography (CT the distribution around the optic nerve (degrees. PBB was performed in 6 orbits. The mixture injected consisted of 20 ml of physiological solution and iodinated CM at 25%. Each periorbital area underwent three CT scans. A basal acquisition to assess the needle position before the injection, a second and third scan were performed immediately after injection, and after application of pressure on the periorbital surface area to promote CM diffusion. The needle position was measured from the tip to the optic nerve with a mean distance of 2,27 mm ± 0,28. The mean volume distribution before pressure application was 23,56 cm3 ± 2,58 and after pressure application was 27,56 cm3 ± 4,8.  The CM distribution, was defined (Nouvellon et al. 2010 “successful” in 4 orbits (>270° and “inadequate” in 2 orbits (<180°. The present study demonstrates feasibility of inferior PBB by single injection in horses for its simple and practical execution. Inferior PPB is a potential alternative to systemic administration of neuromuscular blocking agents for ophthalmic surgery. However, this approach needs to be evaluate in clinical trials to assess its feasibility and effectiveness in clinical practice for standing procedures.

  4. Microencapsulated 3-Dimensional Sensor for the Measurement of Oxygen in Single Isolated Pancreatic Islets

    Science.gov (United States)

    Khalil, Gamal; Sweet, Ian R.; Shen, Amy Q.

    2012-01-01

    Background Oxygen consumption reflects multiple processes in pancreatic islets including mechanisms contributing to insulin secretion, oxidative stress and viability, providing an important readout in studies of islet function, islet viability and drug testing. Due to the scarcity, heterogeneity, and intrinsic kinetic properties of individual islets, it would be of great benefit to detect oxygen consumption by single islets. We present a novel method we have developed to image oxygen in single islets. Methodology/Principal Findings Using a microfluidics system, individual islets and a fluorescent oxygen-sensitive dye were encased within a thin alginate polymer layer. Insulin secretion by the encapsulated islets was normal. Fluorescent signal from the encased dye, detected using a standard inverted fluorescence microscope and digital camera, was stable and proportional to the amount of oxygen in the media. When integrated into a perifusion system, the sensing system detected changes in response to metabolic substrates, mitochondrial poisons, and induced-oscillations. Glucose responses averaged 30.1±7.1% of the response to a metabolic inhibitor (cyanide), increases were observed in all cases (n = 6), and the system was able to resolve changes in oxygen consumption that had a period greater than 0.5 minutes. The sensing system operated similarly from 2–48 hours following encapsulation, and viability and function of the islets were not significantly affected by the encapsulation process. Conclusions/Significance An oxygen-dependent dye situated around and within a pancreatic islet encapsulated by a thin layer of alginate was sensitive to changes in oxygen consumption, and was not harmful to the function or viability of islets over the course of two days. The microcapsule-based sensing method is particularly suited to assessing the effects of compounds (dose responses and time courses) and chronic changes occurring over the course of days. The approach should be

  5. Isolation and characterization of subgenomic DNAs encapsidated in 'single' T = 1 isometric particles of Maize streak virus

    International Nuclear Information System (INIS)

    Casado, Carolina G.; Javier Ortiz, G.; Padron, Eric; Bean, Samantha J.; McKenna, Robert; Agbandje-McKenna, Mavis; Boulton, Margaret I.

    2004-01-01

    'Single' T = 1 isometric particles of Maize streak virus (MSV) have been isolated from infected maize leaves. Biochemical and genetic characterizations show that these particles contain subgenomic (sg) MSV DNA encapsidated by the MSV coat protein. The largest sg DNA is 1.56 kb, slightly larger than half genome size, although sg DNAs as small as 0.2 kb were also cloned. The sg DNAs are not infectious, and they do not appear to play a role in the pathogenicity of MSV. This is the first report of sg DNAs for MSV and, to our knowledge, the first time that encapsidated sg DNAs have been characterized at the sequence level for any geminivirus. These data will assist in our investigations into the role of genomic DNA in the formation of the unique geminate capsid architecture of the Geminiviridae

  6. Laboratory characterization of shale pores

    Science.gov (United States)

    Nur Listiyowati, Lina

    2018-02-01

    To estimate the potential of shale gas reservoir, one needs to understand the characteristics of pore structures. Characterization of shale gas reservoir microstructure is still a challenge due to ultra-fine grained micro-fabric and micro level heterogeneity of these sedimentary rocks. The sample used in the analysis is a small portion of any reservoir. Thus, each measurement technique has a different result. It raises the question which methods are suitable for characterizing pore shale. The goal of this paper is to summarize some of the microstructure analysis tools of shale rock to get near-real results. The two analyzing pore structure methods are indirect measurement (MIP, He, NMR, LTNA) and direct observation (SEM, TEM, Xray CT). Shale rocks have a high heterogeneity; thus, it needs multiscale quantification techniques to understand their pore structures. To describe the complex pore system of shale, several measurement techniques are needed to characterize the surface area and pore size distribution (LTNA, MIP), shapes, size and distribution of pore (FIB-SEM, TEM, Xray CT), and total porosity (He pycnometer, NMR). The choice of techniques and methods should take into account the purpose of the analysis and also the time and budget.

  7. Single nucleotide polymorphism isolated from a novel EST dataset in garden asparagus (Asparagus officinalis L.).

    Science.gov (United States)

    Mercati, Francesco; Riccardi, Paolo; Leebens-Mack, Jim; Abenavoli, Maria Rosa; Falavigna, Agostino; Sunseri, Francesco

    2013-04-01

    Single nucleotide polymorphisms (SNPs) and simple sequence repeats (SSR) are abundant and evenly distributed co-dominant molecular markers in plant genomes. SSRs are valuable for marker assisted breeding and positional cloning of genes associated traits of interest. Although several high throughput platforms have been developed to identify SNP and SSR markers for analysis of segregant plant populations, breeding in garden asparagus (Asparagus officinalis L.) has been limited by a low content of such markers. In this study massively parallel GS-FLX pyro-sequencing technology (454 Life Sciences) has been used to sequence and compare transcriptome from two genotypes: a rust tolerant male (1770) and a susceptible female (G190). A total of 122,963 and 99,368 sequence reads, with an average length of 245.7bp, have been recovered from accessions 1770 and 190 respectively. A computational pipeline has been used to predict and visually inspect putative SNPs and SSR sequences. Analysis of Gene Ontology (GO) slim annotation assignments for all assembled uniscripts indicated that the 24,403 assemblies represent genes from a broad array of functions. Further, over 1800 putative SNPs and 1000 SSRs were detected. One hundred forty-four SNPs together with 60 selected SSRs were validated and used to develop a preliminary genetic map by using a large BC(1) population, derived from 1770 and G190. The abundance of SNPs and SSRs provides a foundation for the development of saturated genetic maps and their utilization in assisted asparagus breeding programs. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. Methods for isolation and viability assessment of biological organisms

    Science.gov (United States)

    Letant, Sonia Edith; Baker, Sarah Elyse; Bond, Tiziana; Chang, Allan Shih-Ping

    2015-02-03

    Isolation of biological or chemical organisms can be accomplished using a surface enhanced Raman scattering (SERS) system. The SERS system can be a single or a stacked plurality of photonic crystal membranes with noble-metal lined through pores for flowing analyte potentially containing the biological or chemical organisms. The through pores can be adapted to trap individual biological or chemical organisms and emit SERS spectra, which can then be detected by a detector and further analyzed for viability of the biological or chemical organism.

  9. Isolation of anti-toxin single domain antibodies from a semi-synthetic spiny dogfish shark display library

    Directory of Open Access Journals (Sweden)

    Goldman Ellen R

    2007-11-01

    Full Text Available Abstract Background Shark heavy chain antibody, also called new antigen receptor (NAR, consists of one single Variable domain (VH, containing only two complementarity-determining regions (CDRs. The antigen binding affinity and specificity are mainly determined by these two CDRs. The good solubility, excellent thermal stability and complex sequence variation of small single domain antibodies (sdAbs make them attractive alternatives to conventional antibodies. In this report, we construct and characterize a diversity enhanced semi-synthetic NAR V display library based on naturally occurring NAR V sequences. Results A semi-synthetic shark sdAb display library with a complexity close to 1e9 was constructed. This was achieved by introducing size and sequence variations in CDR3 using randomized CDR3 primers of three different lengths. Binders against three toxins, staphylococcal enterotoxin B (SEB, ricin, and botulinum toxin A (BoNT/A complex toxoid, were isolated from panning the display library. Soluble sdAbs from selected binders were purified and evaluated using direct binding and thermal stability assays on the Luminex 100. In addition, sandwich assays using sdAb as the reporter element were developed to demonstrate their utility for future sensor applications. Conclusion We demonstrated the utility of a newly created hyper diversified shark NAR displayed library to serve as a source of thermal stable sdAbs against a variety of toxins.

  10. X-ray CT analysis of pore structure in sand

    Science.gov (United States)

    Mukunoki, Toshifumi; Miyata, Yoshihisa; Mikami, Kazuaki; Shiota, Erika

    2016-06-01

    The development of microfocused X-ray computed tomography (CT) devices enables digital imaging analysis at the pore scale. The applications of these devices are diverse in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, the imaging of the pore space in porous media has contributed to numerical simulations for single-phase and multiphase flows or contaminant transport through the pore structure as three-dimensional image data. These obtained results are affected by the pore diameter; therefore, it is necessary to verify the image preprocessing for the image analysis and to validate the pore diameters obtained from the CT image data. Moreover, it is meaningful to produce the physical parameters in a representative element volume (REV) and significant to define the dimension of the REV. This paper describes the underlying method of image processing and analysis and discusses the physical properties of Toyoura sand for the verification of the image analysis based on the definition of the REV. On the basis of the obtained verification results, a pore-diameter analysis can be conducted and validated by a comparison with the experimental work and image analysis. The pore diameter is deduced from Young-Laplace's law and a water retention test for the drainage process. The results from previous study and perforated-pore diameter originally proposed in this study, called the voxel-percolation method (VPM), are compared in this paper. In addition, the limitations of the REV, the definition of the pore diameter, and the effectiveness of the VPM for an assessment of the pore diameter are discussed.

  11. A stochastic model for filtration of particulate suspensions with incomplete pore plugging

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Santos, A; Bedrikovetsky, P. G.

    2007-01-01

    . A closed system of governing stochastic equations determines the evolution of size distributions for suspended particles and pores. Its averaging results in the closed system of hydrodynamic equations accounting for permeability and porosity reduction due to plugging. The problem of deep bed filtration...... of a single particle size suspension through a single pore size medium where a pore can be completely plugged by two particles allows for an exact analytical solution. The phenomenological deep bed filtration model follows from the analytical solution....

  12. Impact of a single session of intermittent pneumatic leg compressions on skeletal muscle and isolated artery gene expression in rats.

    Science.gov (United States)

    Roseguini, Bruno T; Arce-Esquivel, Arturo A; Newcomer, Sean C; Laughlin, M H

    2011-12-01

    Intermittent pneumatic leg compressions (IPC) have proven to be an effective noninvasive approach for treatment of patients with claudication, but the mechanisms underlying the clinical benefits remain elusive. In the present study, a rodent model of claudication produced by bilateral ligation of the femoral artery was used to investigate the acute impact of a single session of IPC (150 min) on hemodynamics, skeletal muscle (tibialis anterior), and isolated collateral artery (perforating artery) expression of a subset of genes associated with inflammation and vascular remodeling. In addition, the effect of compression frequency (15 vs. 3 compressions/min) on the expression of these factors was studied. In ligated animals, IPC evoked an increase of monocyte chemoattractant protein-1 (MCP-1) and cytokine-induced neutrophil chemoattractant 1 (CXCL1) mRNA (P < 0.01) and immunostaining (P < 0.05), as well as a minor increase in VEGF immunostaining in the muscle endomysium 150 min postintervention. Further, collateral arteries from these animals showed an increased expression of MCP-1 (approximately twofold, P = 0.02). These effects were most evident in the group exposed to the high-frequency protocol (15 compressions/min). In contrast, IPC in sham-operated control animals evoked a modest initial upregulation of VEGF (P = 0.01), MCP-1 (P = 0.02), and CXCL1 (P = 0.03) mRNA in the muscle without concomitant changes in protein levels. No changes in gene expression were observed in arteries isolated from sham animals. In conclusion, IPC acutely up-regulates the expression of important factors involved in vascular remodeling in the compressed muscle and collateral arteries in a model of hindlimb ischemia. These effects appear to be dependent on the compression frequency, such that a high compression frequency (15 compressions/min) evokes more consistent and robust effects compared with the frequency commonly employed clinically to treat patients with claudication (3

  13. Pore formation by actinoporins, cytolysins from sea anemones.

    Science.gov (United States)

    Rojko, Nejc; Dalla Serra, Mauro; Maček, Peter; Anderluh, Gregor

    2016-03-01

    Actinoporins (APs) from sea anemones are ~20 kDa pore forming toxins with a β-sandwich structure flanked by two α-helices. The molecular mechanism of APs pore formation is composed of several well-defined steps. APs bind to membrane by interfacial binding site composed of several aromatic amino acid residues that allow binding to phosphatidylcholine and specific recognition of sphingomyelin. Subsequently, the N-terminal α-helix from the β-sandwich has to be inserted into the lipid/water interphase in order to form a functional pore. Functional studies and single molecule imaging revealed that only several monomers, 3-4, oligomerise to form a functional pore. In this model the α-helices and surrounding lipid molecules build toroidal pore. In agreement, AP pores are transient and electrically heterogeneous. On the contrary, crystallized oligomers of actinoporin fragaceatoxin C were found to be composed of eight monomers with no lipids present between the adjacent α-helices. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Maur Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Effects of anisotropy on the equilibrium shape of nanoscale pores at grain boundaries

    International Nuclear Information System (INIS)

    Wynblatt, Paul; Chatain, Dominique

    2013-01-01

    Molecular dynamics simulations have been performed to study the interaction between a faceted pore and an anisotropic grain boundary (GB). Nickel was chosen as a convenient model system. In order to establish the equilibrium crystal shape (ECS) of the pore, studies were also conducted on isolated pores. Isolated pores were found to be subject to the nucleation inhibition of equilibration that has been predicted by Rohrer et al. (J Am Ceram Soc 2000;83:214, 2001;84: 2099). This work shows that configurations close to the ECS can be obtained if supersaturation within a pore is artificially increased by adding mobile adatoms to the internal surfaces of the pores. In the case of pores located at GBs, the nucleation energy barriers to facet displacement are not present for facets in contact with the GB at the triple line, but may still persist for facets that have no contact with the GB. This problem can be overcome by approaching the equilibrium shape from different initial configurations. The configuration of the GB in the vicinity of the pore has been found to be essentially planar, indicating that GB puckering in the vicinity of anisotropic pores is not generally necessary. The present calculations show that incompatibilities between misoriented pore facets that meet at the triple line with the GB are easily accommodated by local atomic rearrangements at the disordered region of intersection with the GB

  15. Can ash clog soil pores?

    Science.gov (United States)

    Stoof, Cathelijne; Stoof, Cathelijne; Gevaert, Anouk; Gevaert, Anouk; Baver, Christine; Baver, Christine; Hassanpour, Bahareh; Hassanpour, Bahareh; Morales, Veronica; Morales, Veronica; Zhang, Wei; Zhang, Wei; Martin, Deborah; Martin, Deborah; Steenhuis, Tammo; Steenhuis, Tammo

    2015-04-01

    Wildfire can greatly increase a landscape's vulnerability to flooding and erosion events, and ash is thought to play a large role in controlling runoff and erosion processes after wildfire. Although ash can store rainfall and thereby reduce runoff and erosion for a limited period after wildfires, it has also been hypothesized to clog soil pores and reduce infiltration. Several researchers have attributed the commonly observed increase in runoff and erosion after fire to the potential pore-clogging effect of ash. Evidence is however incomplete, as to date, research has solely focused on identifying the presence of ash in the soil, with the actual flow processes associated with the infiltration and pore-clogging of ash remaining a major unknown. In several laboratory experiments, we tested the hypothesis that ash causes pore clogging to the point that infiltration is hampered and ponding occurs. We first visualized and quantified pore-scale infiltration of water and ash in sand of a range of textures and at various infiltration rates, using a digital bright field microscope capturing both photo and video. While these visualization experiments confirm field and lab observation of ash washing into soil pores, we did not observe any clogging of pores, and have not been able to create conditions for which this does occur. Additional electrochemical analysis and measurement of saturated hydraulic conductivity indicate that pore clogging by ash is not plausible. Electrochemical analysis showed that ash and sand are both negatively charged, showing that attachment of ash to sand and any resulting clogging is unlikely. Ash also had quite high saturated conductivity, and systems where ash was mixed in or lying on top of sand had similarly high hydraulic conductivity. Based on these various experiments, we cannot confirm the hypothesis that pore clogging by ash contributes to the frequently observed increase in post-fire runoff, at least for the medium to coarse sands

  16. Biodegradation of benzalkonium chlorides singly and in mixtures by a Pseudomonas sp. isolated from returned activated sludge

    International Nuclear Information System (INIS)

    Khan, Adnan Hossain; Topp, Edward; Scott, Andrew; Sumarah, Mark; Macfie, Sheila M.; Ray, Madhumita B.

    2015-01-01

    Highlights: • Pseudomonas sp. degraded two benzalkonium chlorides: BDDA and BDTA. • Although BDTA biodegraded at low concentration, it inhibited the degradation of BDDA. • For BDDA, two transformation products indicate two sites of bacterial activity. • "1"4C-labelled BDDA was mineralized to "1"4CO_2 within 300 h. - Abstract: Bactericidal cationic surfactants such as quaternary ammonium compounds (QACs) are widely detected in the environment, and found at mg kg"−"1 concentrations in biosolids. Although individual QACs are amenable to biodegradation, it is possible that persistence is increased for mixtures of QACs with varying structure. The present study evaluated the biodegradation of benzyl dimethyl dodecyl ammonium chloride (BDDA) singly and in the presence of benzyl dimethyl tetradecyl ammonium chloride (BDTA) using Pseudomonas sp., isolated from returned activated sludge. Growth was evaluated, as was biodegradation using "1"4C and HPLC-MS methods. BDTA was more toxic to growth of Pseudomonas sp. compared to BDDA, and BDTA inhibited BDDA biodegradation. The benzyl ring of [U-"1"4C-benzyl] BDDA was readily and completely mineralized. The detection of the transformation products benzyl methyl amine and dodecyl dimethyl amine in spent culture liquid was consistent with literature. Overall, this study demonstrates the antagonistic effect of interactions on biodegradation of two widely used QACs suggesting further investigation on the degradation of mixture of QACs in wastewater effluents and biosolids.

  17. Single Cell Oil Production from Hydrolysates of Inulin by a Newly Isolated Yeast Papiliotrema laurentii AM113 for Biodiesel Making.

    Science.gov (United States)

    Wang, Guangyuan; Liu, Lin; Liang, Wenxing

    2018-01-01

    Microbial oils are among the most attractive alternative feedstocks for biodiesel production. In this study, a newly isolated yeast strain, AM113 of Papiliotrema laurentii, was identified as a potential lipid producer, which could accumulate a large amount of intracellular lipids from hydrolysates of inulin. P. laurentii AM113 was able to produce 54.6% (w/w) of intracellular oil in its cells and 18.2 g/l of dry cell mass in a fed-batch fermentation. The yields of lipid and biomass were 0.14 and 0.25 g per gram of consumed sugar, respectively. The lipid productivity was 0.092 g of oil per hour. Compositions of the fatty acids produced were C 14:0 (0.9%), C 16:0 (10.8%), C 16:1 (9.7%), C 18:0 (6.5%), C 18:1 (60.3%), and C 18:2 (11.8%). Biodiesel obtained from the extracted lipids could be burnt well. This study not only provides a promising candidate for single cell oil production, but will also probably facilitate more efficient biodiesel production.

  18. Biodegradation of benzalkonium chlorides singly and in mixtures by a Pseudomonas sp. isolated from returned activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Adnan Hossain, E-mail: akhan462@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada); Topp, Edward, E-mail: Ed.Topp@AGR.GC.CA [Agriculture and Agri-Food Canada, London, ON N5V 4T3 (Canada); Department of Biology, University of Western Ontario, London, ON N6A 5B7 (Canada); Scott, Andrew, E-mail: Andrew.Scott@AGR.GC.CA [Agriculture and Agri-Food Canada, London, ON N5V 4T3 (Canada); Sumarah, Mark, E-mail: Mark.Sumarah@agr.gc.ca [Agriculture and Agri-Food Canada, London, ON N5V 4T3 (Canada); Macfie, Sheila M., E-mail: smacfie@uwo.ca [Department of Biology, University of Western Ontario, London, ON N6A 5B7 (Canada); Ray, Madhumita B., E-mail: mbhowmic@uwo.ca [Department of Chemical and Biochemical Engineering, University of Western Ontario, London, ON N6A 5B9 (Canada)

    2015-12-15

    Highlights: • Pseudomonas sp. degraded two benzalkonium chlorides: BDDA and BDTA. • Although BDTA biodegraded at low concentration, it inhibited the degradation of BDDA. • For BDDA, two transformation products indicate two sites of bacterial activity. • {sup 14}C-labelled BDDA was mineralized to {sup 14}CO{sub 2} within 300 h. - Abstract: Bactericidal cationic surfactants such as quaternary ammonium compounds (QACs) are widely detected in the environment, and found at mg kg{sup −1} concentrations in biosolids. Although individual QACs are amenable to biodegradation, it is possible that persistence is increased for mixtures of QACs with varying structure. The present study evaluated the biodegradation of benzyl dimethyl dodecyl ammonium chloride (BDDA) singly and in the presence of benzyl dimethyl tetradecyl ammonium chloride (BDTA) using Pseudomonas sp., isolated from returned activated sludge. Growth was evaluated, as was biodegradation using {sup 14}C and HPLC-MS methods. BDTA was more toxic to growth of Pseudomonas sp. compared to BDDA, and BDTA inhibited BDDA biodegradation. The benzyl ring of [U-{sup 14}C-benzyl] BDDA was readily and completely mineralized. The detection of the transformation products benzyl methyl amine and dodecyl dimethyl amine in spent culture liquid was consistent with literature. Overall, this study demonstrates the antagonistic effect of interactions on biodegradation of two widely used QACs suggesting further investigation on the degradation of mixture of QACs in wastewater effluents and biosolids.

  19. Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

    Directory of Open Access Journals (Sweden)

    Tae-Jung Ha

    2011-01-01

    Full Text Available Materials with nanosized and well-arranged pores have been researched actively in order to be applied to new technology fields. Especially, mesoporous material containing various pore structures is expected to have different pore structure. To form a mixed pore structure, ordered mesoporous silica films were prepared with a mixture of surfactant; Brij-76 and P-123 block copolymer. In mixed surfactant system, mixed pore structure was observed in the region of P-123/(Brij-76 + P-123 with about 50.0 wt.% while a single pore structure was observed in regions which have large difference in ratio between Brij-76 and P-123 through the X-ray diffraction analysis. Regardless of surfactant ratio, porosity was retained almost the same. It is expected that ordered mesoporous silica film with mixed pore structure can be one of the new materials which has distinctive properties.

  20. Isolated single coronary artery (RII-B type presenting as an inferior wall myocardial infarction: A rare clinical entity

    Directory of Open Access Journals (Sweden)

    Ankur C. Thummar

    2014-09-01

    Full Text Available Isolated single coronary artery without other congenital cardiac anomalies is very rare among the different variations of anomalous coronary patterns. The prognosis in patients with single coronary varies according to the anatomic distribution and associated coronary atherosclerosis. If the left main coronary artery travels between the aorta and pulmonary arteries, it may be a cause of sudden cardiac death. We present multimodality images of a single coronary artery, in which the whole coronary system originated by a single trunk from the right sinus of Valsalva with inter-arterial course of left main coronary artery. This rare type of single coronary artery was classified as RII-B type according to Lipton's scheme of classification. A significant flow-limiting lesions were found in the right coronary artery that was successfully treated with percutaneous coronary intervention.

  1. An investigation into the effects of pore connectivity on T2 NMR relaxation

    Science.gov (United States)

    Ghomeshi, Shahin; Kryuchkov, Sergey; Kantzas, Apostolos

    2018-04-01

    Nuclear Magnetic Resonance (NMR) is a powerful technique used to characterize fluids and flow in porous media. The NMR relaxation curves are closely related to pore geometry, and the inversion of the NMR relaxometry data is known to give useful information with regards to pore size distribution (PSD) through the relative amplitudes of the fluids stored in the small and large pores. While this information is crucial, the main challenge for the successful use of the NMR measurements is the proper interpretation of the measured signals. Natural porous media patterns consist of complex pore structures with many interconnected or "coupled" regions, as well as isolated pores. This connectivity along the throats changes the relaxation distribution and in order to properly interpret this data, a thorough understanding of the effects of pore connectivity on the NMR relaxation distribution is warranted. In this paper we address two main points. The first pertains to the fact that there is a discrepancy between the relaxation distribution obtained from experiments, and the ones obtained from solving the mathematical models of diffusion process in the digitized images of the pore space. There are several reasons that may attribute to this such as the lack of a proper incorporation of surface roughness into the model. However, here we are more interested in the effects of pore connectivity and to understand why the typical NMR relaxation distribution obtained from experiments are wider, while the numerical simulations predict that a wider NMR relaxation distribution may indicate poor connectivity. Secondly, by not taking into account the pore coupling effects, from our experience in interpreting the data, we tend to underestimate the pore volume of small pores and overestimate the amplitudes in the large pores. The role of pore coupling becomes even more prominent in rocks with small pore sizes such as for example in shales, clay in sandstones, and in the microstructures of

  2. Antera 3D capabilities for pore measurements.

    Science.gov (United States)

    Messaraa, C; Metois, A; Walsh, M; Flynn, J; Doyle, L; Robertson, N; Mansfield, A; O'Connor, C; Mavon, A

    2018-04-29

    The cause of enlarged pores remains obscure but still remains of concern for women. To complement subjective methods, bioengineered methods are needed for quantification of pores visibility following treatments. The study objective was to demonstrate the suitability of pore measurements from the Antera 3D. Pore measurements were collected on 22 female volunteers aged 18-65 years with the Antera 3D, the DermaTOP and image analysis on photographs. Additionally, 4 raters graded pore size on photographs on a scale 0-5. Repeatability of Antera 3D parameters was ascertained and the benefit of a pore minimizer product on the cheek was assessed on a sub panel of seven female volunteers. Pore parameters using the Antera were shown to depict pore severity similar to raters on photographs, except for Max Depth. Mean pore volume, mean pore area and count were moderately correlated with DermaTOP parameters (up to r = .50). No relationship was seen between the Antera 3D and pore visibility analysis on photographs. The most repeatable parameters were found to be mean pore volume, mean pore area and max depth, especially for the small and medium filters. The benefits of a pore minimizer product were the most striking for mean pore volume and mean pore area when using the small filter for analysis, rather than the medium/large ones. Pore measurements with the Antera 3D represent a reliable tool for efficacy and field studies, with an emphasis of the small filter for analysis for the mean pore volume/mean pore area parameters. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Concentration Polarization to Measure Nano-pore Accessibility

    NARCIS (Netherlands)

    Solsona, Miguel; Eijkel, Jan C.T.; Olthuis, Wouter; Papadimitriou, Vasileios; van den Berg, Albert; Abelmann, Leon; Weckhuysen, Bert M.; Nieuwelink, A. E.

    2017-01-01

    Understanding the deactivation process in porous catalysts is of tremendous economic significance. We demonstrate the feasibility of using the concentration polarization method to obtain the pore accessibility distribution at single particle level for the first time. By using this technique we could

  4. Coating of silicon pore optics

    DEFF Research Database (Denmark)

    Cooper-Jensen, Carsten P.; Ackermann, M.; Christensen, Finn Erland

    2009-01-01

    For the International X-ray observatory (IXO), a mirror module with an effective area of 3 m2 at 1.25 keV and at least 0.65 m2 at 6 keV has to be realized. To achieve this goal, coated silicon pore optics has been developed over the last years. One of the challenges is to coat the Si plates...

  5. Shake and stew: a non-destructive PCR-ready DNA isolation method from a single preserved fish larva.

    Science.gov (United States)

    Alvarado Bremer, J R; Smith, B L; Moulton, D L; Lu, C-P; Cornic, M

    2014-01-01

    A rapid non-destructive alternative to isolate DNA from an individual fish larva is presented, based on the suspension of epithelial cells through vortex forces, and the release of DNA in a heated alkaline solution. DNA from >6056 fish larvae isolated using this protocol has yielded a high PCR amplification success rate (>93%), suggesting its applicability to other taxonomic groups or sources when tissue amount is the limiting factor. © 2014 The Fisheries Society of the British Isles.

  6. Pore volume is most highly correlated with the visual assessment of skin pores.

    Science.gov (United States)

    Kim, S J; Shin, M K; Back, J H; Koh, J S

    2014-11-01

    Many studies have been focused on evaluating assessment techniques for facial pores amid growing attention on skin care. Ubiquitous techniques used to assess the size of facial pores include visual assessment, cross-section images of the skin surface, and profilometric analysis of silicone replica of the facial skin. In addition, there are indirect assessment methods, including observation of pores based on confocal laser scanning microscopy and the analysis of sebum secretion and skin elasticity. The aim of this study was to identify parameters useful in estimating pore of surface in normal skin. The severity of pores on the cheek area by frontal optical images was divided on a 0-6 scale with '0' being faint and small pore and '6' being obvious and large pore. After the photos of the frontal cheek of 32 women aged between 35 and 49 were taken, the size of their pores was measured on a 0-6 scale; and the correlation between visual grading of pore and various evaluations (pore volume by 3-D image, pore area and number by Optical Image Analyzer) contributing to pore severity investigated using direct, objective, and noninvasive evaluations. The visual score revealed that the size of pores was graded on a 1-6 scale. Visual grading of pore was highly correlated with pore volume measured from 3-D images and pore area measured from 2-D optical images in the order (P pore was also slightly correlated with the number of pores in size of over 0.04 mm(2) (P pore score and pore volume can be explained by 3-D structural characteristics of pores. It is concluded that pore volume and area serve as useful parameters in estimating pore of skin surface. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Protein crystal nucleation in pores.

    Science.gov (United States)

    Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E

    2017-01-16

    The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the pore is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the pore walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.

  8. Silicon pore optics for future x-ray telescopes

    DEFF Research Database (Denmark)

    Wille, Eric; Bavdaz, Marcos; Wallace, Kotska

    2017-01-01

    arcsec or better. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is being developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor...... industry. We present the recent upgrades made to the manufacturing processes and equipment, ranging from the manufacture of single mirror plates towards complete focusing mirror modules mounted in flight configuration, and results from first vibration tests. The performance of the mirror modules is tested...

  9. Gas Adsorption in Novel Environments, Including Effects of Pore Relaxation

    International Nuclear Information System (INIS)

    Cole, Milton W; Gatica, Silvina M; Kim, Hye-Young; Lueking, Angela D; Sircar, Sarmishtha

    2012-01-01

    Adsorption experiments have been interpreted frequently with simplified model geometries, such as ideally flat surfaces and slit or cylindrical pores. Recent explorations of unusual environments, such as fullerenes and metal-organic-framework materials, have led to a broadened scope of experimental, theoretical and simulation investigations. This paper reviews a number of such studies undertaken by our group. Among the topics receiving emphasis are these: universality of gas uptake in pores, relaxation of a porous absorbent due to gas uptake and the novel phases of gases on a single nanotube, all of which studies have been motivated by recent experiments.

  10. Phenotype and envelope gene diversity of nef-deleted HIV-1 isolated from long-term survivors infected from a single source

    Directory of Open Access Journals (Sweden)

    Sullivan John S

    2007-07-01

    Full Text Available Abstract Background The Sydney blood bank cohort (SBBC of long-term survivors consists of multiple individuals infected with attenuated, nef-deleted variants of human immunodeficiency virus type 1 (HIV-1 acquired from a single source. Long-term prospective studies have demonstrated that the SBBC now comprises slow progressors (SP as well as long-term nonprogressors (LTNP. Convergent evolution of nef sequences in SBBC SP and LTNP indicates the in vivo pathogenicity of HIV-1 in SBBC members is dictated by factors other than nef. To better understand mechanisms underlying the pathogenicity of nef-deleted HIV-1, we examined the phenotype and env sequence diversity of sequentially isolated viruses (n = 2 from 3 SBBC members. Results The viruses characterized here were isolated from two SP spanning a three or six year period during progressive HIV-1 infection (subjects D36 and C98, respectively and from a LTNP spanning a two year period during asymptomatic, nonprogressive infection (subject C18. Both isolates from D36 were R5X4 phenotype and, compared to control HIV-1 strains, replicated to low levels in peripheral blood mononuclear cells (PBMC. In contrast, both isolates from C98 and C18 were CCR5-restricted. Both viruses isolated from C98 replicated to barely detectable levels in PBMC, whereas both viruses isolated from C18 replicated to low levels, similar to those isolated from D36. Analysis of env by V1V2 and V3 heteroduplex tracking assay, V1V2 length polymorphisms, sequencing and phylogenetic analysis showed distinct intra- and inter-patient env evolution. Conclusion Independent evolution of env despite convergent evolution of nef may contribute to the in vivo pathogenicity of nef-deleted HIV-1 in SBBC members, which may not necessarily be associated with changes in replication capacity or viral coreceptor specificity.

  11. The Arabidopsis Nuclear Pore and Nuclear Envelope

    OpenAIRE

    Meier, Iris; Brkljacic, Jelena

    2010-01-01

    The nuclear envelope is a double membrane structure that separates the eukaryotic cytoplasm from the nucleoplasm. The nuclear pores embedded in the nuclear envelope are the sole gateways for macromolecular trafficking in and out of the nucleus. The nuclear pore complexes assembled at the nuclear pores are large protein conglomerates composed of multiple units of about 30 different nucleoporins. Proteins and RNAs traffic through the nuclear pore complexes, enabled by the interacting activities...

  12. Relationship between pore structure and compressive strength

    Indian Academy of Sciences (India)

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and ...

  13. Facial Pores: Definition, Causes, and Treatment Options.

    Science.gov (United States)

    Lee, Sang Ju; Seok, Joon; Jeong, Se Yeong; Park, Kui Young; Li, Kapsok; Seo, Seong Jun

    2016-03-01

    Enlarged skin pores refer to conditions that present with visible topographic changes of skin surfaces. Although not a medical concern, enlarged pores are a cosmetic concern for a large number of individuals. Moreover, clear definition and possible causes of enlarged pores have not been elucidated. To review the possible causes and treatment options for skin pores. This article is based on a review of the medical literature and the authors' clinical experience in investigating and treating skin pores. There are 3 major clinical causes of enlarged facial pores, namely high sebum excretion, decreased elasticity around pores, and increased hair follicle volume. In addition, chronic recurrent acne, sex hormones, and skin care regimen can affect pore size. Given the different possible causes for enlarged pores, therapeutic modalities must be individualized for each patient. Potential factors that contribute to enlarged skin pores include excessive sebum, decreased elasticity around pores, and increased hair follicle volume. Because various factors cause enlarged facial pores, it might be useful to identify the underlying causes to be able to select the appropriate treatment.

  14. Pore-scale investigation of biomass plug development and propagation in porous media.

    Science.gov (United States)

    Stewart, Terri L; Scott Fogler, H

    2002-03-05

    Biomass plugging of porous media finds application in enhanced oil recovery and bioremediation. An understanding of biomass plugging of porous media was sought by using a porous glass micromodel through which biomass and nutrient were passed. This study describes the pore-scale physics of biomass plug propagation of Leuconostoc mesenteroides under nutrient-rich conditions. It was found that, as the nutrient flowed through the micromodel, the initial biomass plug occurred at the nutrient-inoculum interface due to growth in the larger pore throats. As growth proceeded, biomass filled and closed these larger pore throats, until only isolated groupings of pore throats with smaller radii remained empty. As nutrient flow continued, a maximum pressure drop was reached. At the maximum pressure drop, the biomass yielded in a manner similar to a Bingham plastic to form a breakthrough channel consisting of a path of interconnected pore throats. The channel incorporated the isolated groupings of empty pore throats that had been present before breakthrough. As the nutrient flow continued, subsequent plugs developed as breakthrough channels refilled with biomass and in situ growth was stimulated in the region just downstream of the previous plug. The downstream plugs had a higher fraction of isolated groupings of empty pore throats, which can be attributed to depletion of nutrient downstream. When the next breakthrough channel formed, it incorporated these isolated groupings, causing the breakthrough channels to be branched. It was observed that the newly formed plug could be less stable with this higher fraction of empty pore throats and that the location of breakthrough channels changed in subsequent plugs. This change in breakthrough channel location could be attributed to the redistribution of nutrient flow and the changes in flowrate in the pore throats. Copyright 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 577-588, 2002; DOI 10.1002/bit.10044

  15. Enhanced Emission from Single Isolated Gold Quantum Dots Investigated Using Two-Photon-Excited Fluorescence Near-Field Scanning Optical Microscopy.

    Science.gov (United States)

    Abeyasinghe, Neranga; Kumar, Santosh; Sun, Kai; Mansfield, John F; Jin, Rongchao; Goodson, Theodore

    2016-12-21

    New approaches in molecular nanoscopy are greatly desired for interrogation of biological, organic, and inorganic objects with sizes below the diffraction limit. Our current work investigates emergent monolayer-protected gold quantum dots (nanoclusters, NCs) composed of 25 Au atoms by utilizing two-photon-excited fluorescence (TPEF) near-field scanning optical microscopy (NSOM) at single NC concentrations. Here, we demonstrate an approach to synthesize and isolate single NCs on solid glass substrates. Subsequent investigation of the NCs using TPEF NSOM reveals that, even when they are separated by distances of several tens of nanometers, we can excite and interrogate single NCs individually. Interestingly, we observe an enhanced two-photon absorption (TPA) cross section for single Au 25 NCs that can be attributed to few-atom local field effects and to local field-induced microscopic cascading, indicating their potential for use in ultrasensitive sensing, disease diagnostics, cancer cell therapy, and molecular computers. Finally, we report room-temperature aperture-based TPEF NSOM imaging of these NCs for the first time at 30 nm point resolution, which is a ∼5-fold improvement compared to the previous best result for the same technique. This report unveils the unique combination of an unusually large TPA cross section and the high photostability of Au NCs to (non-destructively) investigate stable isolated single NCs using TPEF NSOM. This is the first reported optical study of monolayer-protected single quantum clusters, opening some very promising opportunities in spectroscopy of nanosized objects, bioimaging, ultrasensitive sensing, molecular computers, and high-density data storage.

  16. Measuring kinetic drivers of pneumolysin pore structure.

    Science.gov (United States)

    Gilbert, Robert J C; Sonnen, Andreas F-P

    2016-05-01

    Most membrane attack complex-perforin/cholesterol-dependent cytolysin (MACPF/CDC) proteins are thought to form pores in target membranes by assembling into pre-pore oligomers before undergoing a pre-pore to pore transition. Assembly during pore formation is into both full rings of subunits and incomplete rings (arcs). The balance between arcs and full rings is determined by a mechanism dependent on protein concentration in which arc pores arise due to kinetic trapping of the pre-pore forms by the depletion of free protein subunits during oligomerization. Here we describe the use of a kinetic assay to study pore formation in red blood cells by the MACPF/CDC pneumolysin from Streptococcus pneumoniae. We show that cell lysis displays two kinds of dependence on protein concentration. At lower concentrations, it is dependent on the pre-pore to pore transition of arc oligomers, which we show to be a cooperative process. At higher concentrations, it is dependent on the amount of pneumolysin bound to the membrane and reflects the affinity of the protein for its receptor, cholesterol. A lag occurs before cell lysis begins; this is dependent on oligomerization of pneumolysin. Kinetic dissection of cell lysis by pneumolysin demonstrates the capacity of MACPF/CDCs to generate pore-forming oligomeric structures of variable size with, most likely, different functional roles in biology.

  17. Evaluation of Colloid Retention Site Dominance in Variably Saturated Porous Media: An All Pores Pore-Scale Analysis

    Science.gov (United States)

    Morales, Veronica; Perez-Reche, Francisco; Holzner, Markus; Kinzelbach, Wolfgang

    2016-04-01

    It is well accepted that colloid and nanoparticle transport processes in porous media differ substantially between water saturated and unsaturated conditions. Differences are frequently ascribed to particle immobilization by association with interfaces with the gas, as well as to restrictions of the liquid medium through which colloids are transported. Yet, the current understanding of the importance of particle retention at gas interfaces is based on observations of single pores or two-dimensional pore network representations, leaving open the question of their statistical significance when all pores in the medium are considered. In order to address this question, column experiments were performed using a model porous medium of glass beads through which Silver particles were transported for conditions of varying water content and water chemistry. X-ray microtomography was subsequently employed as a non-destructive imaging technique to obtain pore-scale information of the entire column regarding: i) the presence and distribution of the main locations where colloids can become retained (interfaces with the water-solid, air-water, air-solid, and air-water-solid, grain-grain contacts, and the bulk liquid), ii) deposition profiles of colloids along the column classified by the available retention location, and iii) channel widths of 3-dimensional pore-water network representations. The results presented provide a direct statistical evaluation on the significance of colloid retention by attachment to interfaces or by strainig at contact points where multiple interfaces meet.

  18. Study of pore pressure reaction on hydraulic fracturing

    Science.gov (United States)

    Trimonova, Mariia; Baryshnikov, Nikolay; Turuntaev, Sergey; Zenchenko, Evgeniy; Zenchenko, Petr

    2017-04-01

    We represent the results of the experimental study of the hydraulic fracture propagation influence on the fluid pore pressure. Initial pore pressure was induced by injection and production wells. The experiments were carried out according to scaling analysis based on the radial model of the fracture. All required geomechanical and hydrodynamical properties of a sample were derived from the scaling laws. So, gypsum was chosen as a sample material and vacuum oil as a fracturing fluid. The laboratory setup allows us to investigate the samples of cylindrical shape. It can be considered as an advantage in comparison with standard cubic samples, because we shouldn't consider the stress field inhomogeneity induced by the corners. Moreover, we can set 3D-loading by this setting. Also the sample diameter is big enough (43cm) for placing several wells: the fracturing well in the center and injection and production wells on two opposite sides of the central well. The experiment consisted of several stages: a) applying the horizontal pressure; b) applying the vertical pressure; c) water solution injection in the injection well with a constant pressure; d) the steady state obtaining; e) the oil injection in the central well with a constant rate. The pore pressure was recorded in the 15 points along bottom side of the sample during the whole experiment. We observe the pore pressure change during all the time of the experiment. First, the pore pressure changed due to water injection. Then we began to inject oil in the central well. We compared the obtained experimental data on the pore pressure changes with the solution of the 2D single-phase equation of pore-elasticity, and we found significant difference. The variation of the equation parameters couldn't help to resolve the discrepancy. After the experiment, we found that oil penetrated into the sample before and after the fracture initiation. This fact encouraged us to consider another physical process - the oil

  19. Single test isolated lupus anticoagulant positivity is associated with increased plasma levels of inflammatory markers and dyslipidemia

    DEFF Research Database (Denmark)

    Just, S A; Nybo, M; Laustrup, H

    2016-01-01

    OBJECTIVE: To investigate whether a single positive test for lupus anticoagulant (LA) is associated with levels of inflammatory markers and traditional cardiovascular risk factors, independent of autoimmune disease, thrombophilia and occurrence of other antiphospholipid antibodies. METHODS: In a ...

  20. A novel tertiary prep-HPLC method for the isolation of single amino acids for AMS-radiocarbon measurement.

    Science.gov (United States)

    Fernandes, Ricardo; Koudelka, Tomas; Tholey, Andreas; Dreves, Alexander

    2017-07-15

    AMS-radiocarbon measurements of amino acids can potentially provide more reliable radiocarbon dates than bulk collagen analysis. Nonetheless, the applicability of such an approach is often limited by the low-throughput of existing isolation methods and difficulties in determining the contamination introduced during the separation process. A novel tertiary prep-HPLC amino acid isolation method was developed that relies on the combustion of eluted material without requiring any additional chemical steps. Amino acid separation was carried out using a gradient mix of pure water and phosphoric acid with an acetonitrile step in-between runs to remove hydrophobic molecules from the separation column. The amount of contaminant carbon and its 14 C content were determined from two-point measurements of collagen samples of known 14 C content. The amount of foreign carbon due to the isolation process was estimated at 4±1μg and its 14 C content was 0.43±0.01 F 14 C. Radiocarbon values corrected for carbon contamination have only a minor increase in uncertainties. For Holocene samples, this corresponds to an added uncertainty typically smaller than 10 14 Cyears. The developed method can be added to routine AMS measurements without implying significant operational changes and offers a level of measurement uncertainty that is suitable for many archaeological, ecological, environmental, and biological applications. Copyright © 2017. Published by Elsevier B.V.

  1. METHODS FOR PORE WATER EXTRACTION FROM UNSATURATED ZONE TUFF, YUCCA MOUNTAIN, NEVADA

    International Nuclear Information System (INIS)

    K.M. SCOFIELD

    2006-01-01

    Assessing the performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, requires an understanding of the chemistry of the water that moves through the host rock. The uniaxial compression method used to extract pore water from samples of tuffaceous borehole core was successful only for nonwelded tuff. An ultracentrifugation method was adopted to extract pore water from samples of the densely welded tuff of the proposed repository horizon. Tests were performed using both methods to determine the efficiency of pore water extraction and the potential effects on pore water chemistry. Test results indicate that uniaxial compression is most efficient for extracting pore water from nonwelded tuff, while ultracentrifugation is more successful in extracting pore water from densely welded tuff. Pore water splits taken from a single nonwelded tuff core during uniaxial compression tests have shown changes in pore water chemistry with increasing pressure for calcium, chloride, sulfate, and nitrate, while the chemistry of pore water splits from welded and nonwelded tuffs using ultracentrifugation indicates that there is no significant fractionation of solutes

  2. Pore surface engineering in covalent organic frameworks.

    Science.gov (United States)

    Nagai, Atsushi; Guo, Zhaoqi; Feng, Xiao; Jin, Shangbin; Chen, Xiong; Ding, Xuesong; Jiang, Donglin

    2011-11-15

    Covalent organic frameworks (COFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable pore size and geometry; however, pore surface engineering in COFs remains challenging. Here we introduce pore surface engineering to COF chemistry, which allows the controlled functionalization of COF pore walls with organic groups. This functionalization is made possible by the use of azide-appended building blocks for the synthesis of COFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce pore surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in COFs. Therefore, this methodology constitutes a step in the pore surface engineering of COFs to realize pre-designed compositions, components and functions.

  3. A simple and effective protocol for fast isolation of human Tenon's fibroblasts from a single trabeculectomy biopsy - a comparison of cell behaviour in different culture media.

    Science.gov (United States)

    Przekora, Agata; Zarnowski, Tomasz; Ginalska, Grazyna

    2017-01-01

    Human Tenon's fibroblasts (HTFs) play a crucial role in wound healing. They cause postoperative scarring of the filtering bleb and are thus responsible for trabeculectomy failure. This study aimed to find an effective and fast protocol for HTF isolation from trabeculectomy biopsies. The protocol was compared with the commonly recommended HTF isolation procedure, which uses Dulbecco's modified Eagle's medium (DMEM). We used Eagle's minimum essential medium (EMEM) enriched with fibroblast growth factor (FGF), which selectively promoted the proliferation of HTF cells. A secondary goal was to compare HTF morphology, metabolism and growth during parallel cultivation of the isolated cells in FGF-enriched EMEM and DMEM. Standard procedures for HTF isolation from tissue biopsies require a 20- to 30-day culture of the explants to obtain the first monolayer. Our protocol yielded the first monolayer after approx. 15 days. More importantly, the majority of the cells were fibroblasts with only individual epithelium-derived cells present. Using FGF-enriched EMEM allowed 1.3 × 10 6 vimentin-positive fibroblasts to be obtained from a single biopsy within approx. 25 days. Using DMEM resulted in isolation failure and required exchange to FGF-enriched medium to recover the fibroblast culture. HTFs maintained in FGF-enriched EMEM also showed faster proliferation and a different type I collagen production ability compared to HTFs cultured in DMEM. Thus, FGF-enriched EMEM is recommended for fast propagation of HTFs unless the aim of the study is to assess the effect of a tested agent on proliferation ability or type I collagen production. Our fast protocol for HTF isolation allows easy setup of cell banks by researchers under laboratory conditions and could be very useful during testing of novel ophthalmologic anti-fibrotic agents in vitro. Molecular analysis of HTFs isolated from patients with known treatment histories may provide valuable information on the effects of some

  4. Effects of fractal pore on coal devolatilization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongli; He, Rong [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Wang, Xiaoliang; Cao, Liyong [Dongfang Electric Corporation, Chengdu (China). Centre New Energy Inst.

    2013-07-01

    Coal devolatilization is numerically investigated by drop tube furnace and a coal pyrolysis model (Fragmentation and Diffusion Model). The fractal characteristics of coal and char pores are investigated. Gas diffusion and secondary reactions in fractal pores are considered in the numerical simulations of coal devolatilization, and the results show that the fractal dimension is increased firstly and then decreased later with increased coal conversions during devolatilization. The mechanisms of effects of fractal pores on coal devolatilization are analyzed.

  5. Isolation and individual electrical stimulation of single smooth-muscle cells from the urinary bladder of the pig

    NARCIS (Netherlands)

    J.J. Glerum (Jacobus); R. van Mastrigt (Ron); J.C. Romijn (Johannes); D.J. Griffiths (Derek)

    1987-01-01

    textabstractIn contrast to striated muscle, measurements on strips of smooth muscle cannot be uniquely interpreted in terms of an array of contractile units. Therefore scaling down to the single-cell level is necessary to gain detailed understanding of the contractile process in this type of muscle.

  6. Rapid isolation of IgNAR variable single-domain antibody fragments from a shark synthetic library.

    Science.gov (United States)

    Shao, Cui-Ying; Secombes, Chris J; Porter, Andrew J

    2007-01-01

    The immunoglobulin isotype IgNAR (Novel Antigen Receptor) was discovered in the serum of the nurse shark (Ginglymostoma cirratum) and wobbegong shark (Orectolobus maculates) as a homodimer of two protein chains, each composed of a single variable domain (V) domain and five constant domains. The IgNAR variable domain contains an intact antigen-binding site and functions as an independent domain able to react to antigen with both high specificity and affinity. Here we describe the successful construction of a synthetic phage-displayed library based upon a single anti-lysozyme clone HEL-5A7 scaffold, which was previously selected from an immune IgNAR variable domain library. The complementarity-determining region 3 (CDR3) loop of this clone was varied in both length and composition and the derived library was used to pan against two model proteins, lysozyme and leptin. A single anti-lysozyme clone (Ly-X20) and anti-leptin clone (Lep-12E1) were selected for further study. Both clones were shown to be functionally expressed in Escherichia coli, extremely thermostable and bind to corresponding antigens specifically. The results here demonstrate that a synthetic IgNAR variable domain library based on a single framework scaffold can be used as a route to generate antigen binders quickly, easily and without the need of immunization.

  7. Membrane potential and microsecond to millisecond delayed light emission after a single excitation flash in isolated chloroplasts

    International Nuclear Information System (INIS)

    Jursinic, P.; Govindjee; Wraight, C.A.

    1978-01-01

    The effect of light-induced and salt-jump induced membrane potential on microsecond and millisecond delayed light emission from chloroplasts, following a single 10 ns flash, have been studied. Microsecond delayed light emission is shown to be independent of the membrane potential contrary to proposals that the activation energy for delayed light emission can be modulated by transmembrane electric fields. This result is discussed in terms of the possible origin of this short-lived emission. Millisecond delayed light after a single excitation flash is enhanced by membrane potential only if a proton gradient is present. By measuring changes in ms delayed light caused by simultaneous injection of KCl and Na-benzoate (which creates a proton gradient) in the presence of valinomycin, the light-induced potential generated across the thylakoid membrane by a single excitation flash was calibrated and found to be 128 +- 10 mV in agreement with the recent measurements of Zickler and Witt, (FEBS Lett. 66, 142-148 (1976)), based on voltage-dependent ionophores. It is concluded that the secondary charges that give rise to ms delayed light, after a single flash, do not fully span the membrane. (author)

  8. Membranes with functionalized carbon nanotube pores for selective transport

    Science.gov (United States)

    Bakajin, Olgica; Noy, Aleksandr; Fornasiero, Francesco; Park, Hyung Gyu; Holt, Jason K; Kim, Sangil

    2015-01-27

    Provided herein composition and methods for nanoporous membranes comprising single walled, double walled, or multi-walled carbon nanotubes embedded in a matrix material. Average pore size of the carbon nanotube can be 6 nm or less. 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.

  9. Electroosmotic pore transport in human skin.

    Science.gov (United States)

    Uitto, Olivia D; White, Henry S

    2003-04-01

    To determine the pathways and origin of electroosmotic flow in human skin. Iontophoretic transport of acetaminophen in full thickness human cadaver skin was visualized and quantified by scanning electrochemical microscopy. Electroosmotic flow in the shunt pathways of full thickness skin was compared to flow in the pores of excised stratum corneum and a synthetic membrane pore. The penetration of rhodamine 6G into pore structures was investigated by laser scanning confocal microscopy. Electroosmotic transport is observed in shunt pathways in full thickness human skin (e.g., hair follicles and sweat glands), but not in pore openings of freestanding stratum corneum. Absolute values of the diffusive and iontophoretic pore fluxes of acetaminophen in full thickness human skin are also reported. Rhodamine 6G is observed to penetrate to significant depths (approximately 200 microm) along pore pathways. Iontophoresis in human cadaver skin induces localized electroosmotic flow along pore shunt paths. Electroosmotic forces arise from the passage of current through negatively charged mesoor nanoscale pores (e.g., gap functions) within cellular regions that define the pore structure beneath the stratum corneum.

  10. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  11. The hydraulic conductivity of sediments: A pore size perspective

    KAUST Repository

    Ren, X.W.

    2017-12-06

    This article presents an analysis of previously published hydraulic conductivity data for a wide range of sediments. All soils exhibit a prevalent power trend between the hydraulic conductivity and void ratio. Data trends span 12 orders of magnitude in hydraulic conductivity and collapse onto a single narrow trend when the hydraulic conductivity data are plotted versus the mean pore size, estimated using void ratio and specific surface area measurements. The sensitivity of hydraulic conductivity to changes in the void ratio is higher than the theoretical value due to two concurrent phenomena: 1) percolating large pores are responsible for most of the flow, and 2) the larger pores close first during compaction. The prediction of hydraulic conductivity based on macroscale index parameters in this and similar previous studies has reached an asymptote in the range of kmeas/5≤kpredict≤5kmeas. The remaining uncertainty underscores the important role of underlying sediment characteristics such as pore size distribution, shape, and connectivity that are not measured with index properties. Furthermore, the anisotropy in hydraulic conductivity cannot be recovered from scalar parameters such as index properties. Overall, results highlight the robustness of the physics inspired data scrutiny based Hagen–Poiseuille and Kozeny-Carman analyses.

  12. Enhanced water transport and salt rejection through hydrophobic zeolite pores.

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N

    2017-12-15

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  13. Detection of rifampin resistance patterns in Mycobacterium tuberculosis strains isolated in Iran by polymerase chain reaction-single-strand conformation polymorphism and direct sequencing methods

    Directory of Open Access Journals (Sweden)

    Bahram Nasr Isfahani

    2006-09-01

    Full Text Available Mutations in the rpoB locus confer conformational changes leading to defective binding of rifampin (RIF to rpoB and consequently resistance in Mycobacterium tuberculosis. Polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP was established as a rapid screening test for the detection of mutations in the rpoB gene, and direct sequencing has been unambiguously applied to characterize mutations. A total of 37 of Iranian isolates of M. tuberculosis, 16 sensitive and 21 resistant to RIF, were used in this study. A 193-bp region of the rpoB gene was amplified and PCR-SSCP patterns were determined by electrophoresis in 10% acrylamide gel and silver staining. Also, 21 samples of 193-bp rpoB amplicons with different PCR-SSCP patterns from RIFr and 10 from RIFs were sequenced. Seven distinguishable PCR-SSCP patterns were recognized in the 21 Iranian RIFr strains, while 15 out of 16 RIFs isolates demonstrated PCR-SSCP banding patterns similar to that of sensitive standard strain H37Rv. However one of the sensitive isolates demonstrated a different pattern. There were seen six different mutations in the amplified region of rpoB gene: codon 516(GAC/GTC, 523(GGG/GGT, 526(CAC/TAC, 531(TCG/TTG, 511(CTG/TTG, and 512(AGC/TCG. This study demonstrated the high specificity (93.8% and sensitivity (95.2% of PCR-SSCP method for detection of mutation in rpoB gene; 85.7% of RIFr strains showed a single mutation and 14.3% had no mutations. Three strains showed mutations caused polymorphism. Our data support the common notion that rifampin resistance genotypes are generally present mutations in codons 531 and 526, most frequently found in M. tuberculosis populations regardless of geographic origin.

  14. SINGLE CHAIN VARIABLE FRAGMENTS OF ANTIBODIES AGAINST DIPHTHERIA TOXIN B-SUBUNIT ISOLATED FROM PHAGE DISPLAY HUMAN ANTIBODY LIBRARY

    Directory of Open Access Journals (Sweden)

    Oliinyk O. S.

    2014-02-01

    Full Text Available Diphtheria toxin is an exoantigen of Corynebacterium diphtheriae that inhibits protein synthesis and kills sensitive cells. The aim of this study was to obtain human recombinant single-chain variable fragment (scFv antibodies against receptor-binding B subunit of diphtheria toxin. 12 specific clones were selected after three rounds of a phage display naїve (unimmunized human antibody library against recombinant B-subunit. scFv DNA inserts from these 12 clones were digested with MvaI, and 6 unique restriction patterns were found. Single-chain antibodies were expressed in Escherichia coli XL1-blue. The recombinant proteins were characterized by immunoblotting of bacterial extracts and detection with an anti-E-tag antibody. The toxin B-subunit-binding function of the single-chain antibody was shown by ELISA. The affinity constants for different clones were found to be from 106 to 108 М–1. Due to the fact, that these antibody fragments recognized epitopes in the receptor-binding Bsubunit of diphtheria toxin, further studies are interesting to evaluate their toxin neutralization properties and potential for therapeutic applications. Obtained scFv-antibodies can also be used for detection and investigation of biological properties of diphtheria toxin.

  15. Isolation of Single-Domain Antibody Fragments That Preferentially Detect Intact (146S Particles of Foot-and-Mouth Disease Virus for Use in Vaccine Quality Control

    Directory of Open Access Journals (Sweden)

    Michiel M. Harmsen

    2017-08-01

    Full Text Available Intact (146S foot-and-mouth disease virus (FMDVs can dissociate into specific (12S viral capsid degradation products. FMD vaccines normally consist of inactivated virions. Vaccine quality is dependent on 146S virus particles rather than 12S particles. We earlier isolated two llama single-domain antibody fragments (VHHs that specifically recognize 146S particles of FMDV strain O1 Manisa and shown their potential use in quality control of FMD vaccines during manufacturing. These 146S-specific VHHs were specific for particular O serotype strains and did not bind strains from other FMDV serotypes. Here, we describe the isolation of 146S-specific VHHs against FMDV SAT2 and Asia 1 strains by phage display selection from llama immune libraries. VHHs that bind both 12S and 146S particles were readily isolated but VHHs that bind specifically to 146S particles could only be isolated by phage display selection using prior depletion for 12S particles. We obtained one 146S-specific VHH—M332F—that binds to strain Asia 1 Shamir and several VHHs that preferentially bind 146S particles of SAT2 strain SAU/2/00, from which we selected VHH M379F for further characterization. Both M332F and M379F did not bind FMDV strains from other serotypes. In a sandwich enzyme-linked immunosorbent assay (ELISA employing unlabeled and biotinylated versions of the same VHH M332F showed high specificity for 146S particles but M379F showed lower 146S-specificity with some cross-reaction with 12S particles. These ELISAs could detect 146S particle concentrations as low as 2.3–4.6 µg/l. They can be used for FMD vaccine quality control and research and development, for example, to identify virion stabilizing excipients.

  16. The Effect of the Pore Entrance on Particle Motion in Slit Pores: Implications for Ultrathin Membranes.

    Science.gov (United States)

    Delavari, Armin; Baltus, Ruth

    2017-08-10

    Membrane rejection models generally neglect the effect of the pore entrance on intrapore particle transport. However, entrance effects are expected to be particularly important with ultrathin membranes, where membrane thickness is typically comparable to pore size. In this work, a 2D model was developed to simulate particle motion for spherical particles moving at small Re and infinite Pe from the reservoir outside the pore into a slit pore. Using a finite element method, particles were tracked as they accelerated across the pore entrance until they reached a steady velocity in the pore. The axial position in the pore where particle motion becomes steady is defined as the particle entrance length (PEL). PELs were found to be comparable to the fluid entrance length, larger than the pore size and larger than the thickness typical of many ultrathin membranes. Results also show that, in the absence of particle diffusion, hydrodynamic particle-membrane interactions at the pore mouth result in particle "funneling" in the pore, yielding cross-pore particle concentration profiles focused at the pore centerline. The implications of these phenomena on rejection from ultrathin membranes are examined.

  17. Automatic facial pore analysis system using multi-scale pore detection.

    Science.gov (United States)

    Sun, J Y; Kim, S W; Lee, S H; Choi, J E; Ko, S J

    2017-08-01

    As facial pore widening and its treatments have become common concerns in the beauty care field, the necessity for an objective pore-analyzing system has been increased. Conventional apparatuses lack in usability requiring strong light sources and a cumbersome photographing process, and they often yield unsatisfactory analysis results. This study was conducted to develop an image processing technique for automatic facial pore analysis. The proposed method detects facial pores using multi-scale detection and optimal scale selection scheme and then extracts pore-related features such as total area, average size, depth, and the number of pores. Facial photographs of 50 subjects were graded by two expert dermatologists, and correlation analyses between the features and clinical grading were conducted. We also compared our analysis result with those of conventional pore-analyzing devices. The number of large pores and the average pore size were highly correlated with the severity of pore enlargement. In comparison with the conventional devices, the proposed analysis system achieved better performance showing stronger correlation with the clinical grading. The proposed system is highly accurate and reliable for measuring the severity of skin pore enlargement. It can be suitably used for objective assessment of the pore tightening treatments. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  18. Radiative magnetohydrodynamic simulations of solar pores

    NARCIS (Netherlands)

    Cameron, R.; Schuessler, M.; Vögler, A.; Zakharov, V.

    2007-01-01

    Context. Solar pores represent a class of magnetic structures intermediate between small-scale magnetic flux concentrations in intergranular lanes and fully developed sunspots with penumbrae. Aims. We study the structure, energetics, and internal dynamics of pore-like magnetic structures by means of

  19. Cavitation and pore blocking in nanoporous glasses.

    Science.gov (United States)

    Reichenbach, C; Kalies, G; Enke, D; Klank, D

    2011-09-06

    In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean pore widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled pore glass. Since the mean pore width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening pore network can be investigated starting from the narrowest nanopore width. With an increasing mean pore width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by pore blocking can be observed. Furthermore, we find concrete hints for a pore size dependence of the relative pressure of cavitation in highly disordered pore systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided. © 2011 American Chemical Society

  20. FINGERPRINT MATCHING BASED ON PORE CENTROIDS

    Directory of Open Access Journals (Sweden)

    S. Malathi

    2011-05-01

    Full Text Available In recent years there has been exponential growth in the use of bio- metrics for user authentication applications. Automated Fingerprint Identification systems have become popular tool in many security and law enforcement applications. Most of these systems rely on minutiae (ridge ending and bifurcation features. With the advancement in sensor technology, high resolution fingerprint images (1000 dpi pro- vide micro level of features (pores that have proven to be useful fea- tures for identification. In this paper, we propose a new strategy for fingerprint matching based on pores by reliably extracting the pore features The extraction of pores is done by Marker Controlled Wa- tershed segmentation method and the centroids of each pore are con- sidered as feature vectors for matching of two fingerprint images. Experimental results shows that the proposed method has better per- formance with lower false rates and higher accuracy.

  1. A study of single nucleotide polymorphism in the ystB gene of Yersinia enterocolitica strains isolated from various wild animal species.

    Science.gov (United States)

    Bancerz-Kisiel, Agata; Szczerba-Turek, Anna; Platt-Samoraj, Aleksandra; Michalczyk, Maria; Szweda, Wojciech

    2017-03-01

    Y. enterocolitica is the causative agent of yersiniosis. The objective of the article was a study of single nucleotide polymorphism in the ystB gene of Y. enterocolitica strains isolated from various wild animal species. High-resolution melting (HRM) analysis was applied to identify single nucleotide polymorphism (SNP) of ystB gene fragments of 88 Y. enterocolitica biotype 1A strains isolated from wild boar, roe deer, red deer and wild ducks. HRM analysis revealed 14 different melting profiles - 4 of them were defined as regular genotypes (G1, G2, G3, G4), whereas 10 as variations. 24 of the examined Y. enterocolitica strains were classified as G1, 18 strains as a G2, 21 strains as a G3, and 15 strains as a G4. Nucleotide sequences classified as G1 revealed 100% similarity with the Y. enterocolitica D88145.1 sequence (NCBI). Analysis of G2 revealed one point mutation - transition T111A. One mutation was also found in G3, but SNP was placed in a different gene region - transition G193A. Two SNPs - transitions G92C and T111A - were identified in G4. Direct sequencing of 10 variations revealed 5 new variants of the ystB nucleotide sequence: V1 - transition G129A (3 strains); V2 - transitions T111A and G193A (2 strains); V3 - transitions C118T and G193A (1 strain); V4 - transitions C141A and G193A (2 strains); and V5 characterized by 19 SNPs: G83A, T93A, A109G, G114T, C116T, A123G, T134C, T142G, T144C, A150C, G162A, T165G, T170G, T174A, T177G, G178A, A179G, A184G and G193A (2 strains). The predominant genotype in isolates from wild ducks was G1; in red deer G2; in wild boar G3; in roe deer G1 and G4. The proposed HRM method could be used to analyze Y. enterocolitica biotype 1A strains isolated from different sources, including humans.

  2. Polarization-induced local pore-wall functionalization for biosensing: from micropore to nanopore.

    Science.gov (United States)

    Liu, Jie; Pham, Pascale; Haguet, Vincent; Sauter-Starace, Fabien; Leroy, Loïc; Roget, André; Descamps, Emeline; Bouchet, Aurélie; Buhot, Arnaud; Mailley, Pascal; Livache, Thierry

    2012-04-03

    The use of biological-probe-modified solid-state pores in biosensing is currently hindered by difficulties in pore-wall functionalization. The surface to be functionalized is small and difficult to target and is usually chemically similar to the bulk membrane. Herein, we demonstrate the contactless electrofunctionalization (CLEF) approach and its mechanism. This technique enables the one-step local functionalization of the single pore wall fabricated in a silica-covered silicon membrane. CLEF is induced by polarization of the pore membrane in an electric field and requires a sandwich-like composition and a conducting or semiconducting core for the pore membrane. The defects in the silica layer of the micropore wall enable the creation of an electric pathway through the silica layer, which allows electrochemical reactions to take place locally on the pore wall. The pore diameter is not a limiting factor for local wall modification using CLEF. Nanopores with a diameter of 200 nm fabricated in a silicon membrane and covered with native silica layer have been successfully functionalized with this method, and localized pore-wall modification was obtained. Furthermore, through proof-of-concept experiments using ODN-modified nanopores, we show that functionalized nanopores are suitable for translocation-based biosensing.

  3. Validation of model predictions of pore-scale fluid distributions during two-phase flow

    Science.gov (United States)

    Bultreys, Tom; Lin, Qingyang; Gao, Ying; Raeini, Ali Q.; AlRatrout, Ahmed; Bijeljic, Branko; Blunt, Martin J.

    2018-05-01

    Pore-scale two-phase flow modeling is an important technology to study a rock's relative permeability behavior. To investigate if these models are predictive, the calculated pore-scale fluid distributions which determine the relative permeability need to be validated. In this work, we introduce a methodology to quantitatively compare models to experimental fluid distributions in flow experiments visualized with microcomputed tomography. First, we analyzed five repeated drainage-imbibition experiments on a single sample. In these experiments, the exact fluid distributions were not fully repeatable on a pore-by-pore basis, while the global properties of the fluid distribution were. Then two fractional flow experiments were used to validate a quasistatic pore network model. The model correctly predicted the fluid present in more than 75% of pores and throats in drainage and imbibition. To quantify what this means for the relevant global properties of the fluid distribution, we compare the main flow paths and the connectivity across the different pore sizes in the modeled and experimental fluid distributions. These essential topology characteristics matched well for drainage simulations, but not for imbibition. This suggests that the pore-filling rules in the network model we used need to be improved to make reliable predictions of imbibition. The presented analysis illustrates the potential of our methodology to systematically and robustly test two-phase flow models to aid in model development and calibration.

  4. Evaluating lane-by-lane gap-out based signal control for isolated intersection under stop-line, single and multiple advance detection systems

    Directory of Open Access Journals (Sweden)

    Chandan Keerthi Kancharla

    2016-12-01

    Full Text Available In isolated intersection’s actuated signal control, inductive loop detector layout plays a crucial role in providingthe vehicle information to the signal controller. Based on vehicle actuations at the detector, the green time is extended till a pre-defined threshold gap-out occurs. The Federal Highway Administration (FHWA proposed various guidelines for detec-tor layouts on low-speed and high-speed approaches. This paper proposes single and multiple advance detection schemes for low-speed traffic movements, that utilizes vehicle actuations from advance detectors located upstream of the stop-line, which are able to detect spill-back queues. The proposed detection schemes operate with actuated signal control based on lane-by-lane gap-out criteria. The performance of the proposed schemes is compared with FHWA’s stop-line and single advance detection schemes in the VISSIM simulation tool. Results have shown that the proposed single advance detection schemes showed improved performance in reducing travel time delay and average number of stops per vehicle under low volumes while the multiple advance detection scheme performed well under high volumes.

  5. Effect of Pore Size and Pore Connectivity on Unidirectional Capillary Penetration Kinetics in 3-D Porous Media using Direct Numerical Simulation

    Science.gov (United States)

    Fu, An; Palakurthi, Nikhil; Konangi, Santosh; Comer, Ken; Jog, Milind

    2017-11-01

    The physics of capillary flow is used widely in multiple fields. Lucas-Washburn equation is developed by using a single pore-sized capillary tube with continuous pore connection. Although this equation has been extended to describe the penetration kinetics into porous medium, multiple studies have indicated L-W does not accurately predict flow patterns in real porous media. In this study, the penetration kinetics including the effect of pore size and pore connectivity will be closely examined since they are expected to be the key factors effecting the penetration process. The Liquid wicking process is studied from a converging and diverging capillary tube to the complex virtual 3-D porous structures with Direct Numerical Simulation (DNS) using the Volume-Of-Fluid (VOF) method within the OpenFOAM CFD Solver. Additionally Porous Medium properties such as Permeability (k) , Tortuosity (τ) will be also analyzed.

  6. Development of the self-learning machine for creating models of microprocessor of single-phase earth fault protection devices in networks with isolated neutral voltage above 1000 V

    Science.gov (United States)

    Utegulov, B. B.; Utegulov, A. B.; Meiramova, S.

    2018-02-01

    The paper proposes the development of a self-learning machine for creating models of microprocessor-based single-phase ground fault protection devices in networks with an isolated neutral voltage higher than 1000 V. Development of a self-learning machine for creating models of microprocessor-based single-phase earth fault protection devices in networks with an isolated neutral voltage higher than 1000 V. allows to effectively implement mathematical models of automatic change of protection settings. Single-phase earth fault protection devices.

  7. Sequence typing of human adenoviruses isolated from Polish patients subjected to allogeneic hematopoietic stem cell transplantation - a single center experience.

    Science.gov (United States)

    Przybylski, Maciej; Rynans, Sylwia; Waszczuk-Gajda, Anna; Bilinski, Jarosław; Basak, Grzegorz W; Jędrzejczak, Wiesław W; Wróblewska, Marta; Młynarczyk, Grażyna; Dzieciątkowski, Tomasz

    2018-03-28

    Human adenoviruses (HAdV) from species A, B and C are commonly recognized as pathogens causing severe morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. The purpose of the present study was to determine HAdV types responsible for viremia in HSCT recipients at a large tertiary hospital in Poland. Analysis of partial nucleotide sequences of HAdV hexon gene was used to type 40 clinical isolates of HAdV obtained from 40 HSCT recipients. We identified six different HAdV serotypes belonging to species B, C and E. We demonstrated high variability in sequences of detected HAdV types, and patients infected with the same HAdV types were not hospitalized at the same time, which suggests the low possibility of cross-infection. In almost all patients, anti-HAdV antibodies in IgG class were detected, which indicates a history of HAdV infection in the past. Clinical symptoms accompanying HAdV viremia were in 89%, and in 61.5% of individuals, HAdV was a sole pathogen detected. There were no cases with high-level HAdV viremia and severe systemic or organ infections. Graft-versus-host disease (GvHD) was present in patients infected with species B and C, but grade II of GvHD was observed only in patients infected with HAdV-B. The predominance of HAdV-C and common presence of anti-HAdV antibodies in IgG class may strongly suggest that most infections in the present study were reactivations of HAdV persisting into the patient's mucosa-associated lymphoid tissues. Variability of HAdV sequences suggests that cross-infections between patients were very rare. GvHD: graft-versus-host disease; HAdV: human adenoviruses; HSCT: hematopoietic stem cell transplantation.

  8. Use of intradermal botulinum toxin to reduce sebum production and facial pore size.

    Science.gov (United States)

    Shah, Anil R

    2008-09-01

    Review the safety profile and subjective efficacy of intradermal botulinum toxin type A in facial pore size and sebum production. Retrospective analysis of 20 patients. Twenty consecutive patients with a single application of intradermal botulinum toxin type A were examined: Patients (17/20) noted an improvement in sebum production and a decrease in pores size at 1 month after injection. No complications were observed, and 17/20 patients were satisfied with the procedure. Preliminary data suggests that intradermal botulinum toxin may play a role in decreasing sebum production. Further quantitive study may be necessary to determine effects of intradermal botulinum toxin on pore size.

  9. Regulation of Exocytotic Fusion Pores by SNARE Protein Transmembrane Domains

    Directory of Open Access Journals (Sweden)

    Zhenyong Wu

    2017-10-01

    Full Text Available Calcium-triggered exocytotic release of neurotransmitters and hormones from neurons and neuroendocrine cells underlies neuronal communication, motor activity and endocrine functions. The core of the neuronal exocytotic machinery is composed of soluble N-ethyl maleimide sensitive factor attachment protein receptors (SNAREs. Formation of complexes between vesicle-attached v- and plasma-membrane anchored t-SNAREs in a highly regulated fashion brings the membranes into close apposition. Small, soluble proteins called Complexins (Cpx and calcium-sensing Synaptotagmins cooperate to block fusion at low resting calcium concentrations, but trigger release upon calcium increase. A growing body of evidence suggests that the transmembrane domains (TMDs of SNARE proteins play important roles in regulating the processes of fusion and release, but the mechanisms involved are only starting to be uncovered. Here we review recent evidence that SNARE TMDs exert influence by regulating the dynamics of the fusion pore, the initial aqueous connection between the vesicular lumen and the extracellular space. Even after the fusion pore is established, hormone release by neuroendocrine cells is tightly controlled, and the same may be true of neurotransmitter release by neurons. The dynamics of the fusion pore can regulate the kinetics of cargo release and the net amount released, and can determine the mode of vesicle recycling. Manipulations of SNARE TMDs were found to affect fusion pore properties profoundly, both during exocytosis and in biochemical reconstitutions. To explain these effects, TMD flexibility, and interactions among TMDs or between TMDs and lipids have been invoked. Exocytosis has provided the best setting in which to unravel the underlying mechanisms, being unique among membrane fusion reactions in that single fusion pores can be probed using high-resolution methods. An important role will likely be played by methods that can probe single fusion pores

  10. Formation of Isolated Zn Vacancies in ZnO Single Crystals by Absorption of Ultraviolet Radiation: A Combined Study Using Positron Annihilation, Photoluminescence, and Mass Spectroscopy

    Science.gov (United States)

    Khan, Enamul H.; Weber, Marc H.; McCluskey, Matthew D.

    2013-07-01

    Positron annihilation spectra reveal isolated zinc vacancy (VZn) creation in single-crystal ZnO exposed to 193-nm radiation at 100mJ/cm2 fluence. The appearance of a photoluminescence excitation peak at 3.18 eV in irradiated ZnO is attributed to an electronic transition from the VZn acceptor level at ˜100meV to the conduction band. The observed VZn density profile and hyperthermal Zn+ ion emission support zinc vacancy-interstitial Frenkel pair creation by exciting a wide 6.34 eV Zn-O antibonding state at 193-nm photon—a novel photoelectronic process for controlled VZn creation in ZnO.

  11. CFD Prediction on the Pressure Distribution and Streamlines around an Isolated Single-Storey House Considering the Effect of Topographic Characteristics

    Science.gov (United States)

    Abdullah, J.; Zaini, S. S.; Aziz, M. S. A.; Majid, T. A.; Deraman, S. N. C.; Yahya, W. N. W.

    2018-04-01

    Single-storey houses are classified as low rise building and vulnerable to damages under windstorm event. This study was carried out with the aim to investigate the pressure distribution and streamlines around an isolated house by considering the effect of terrain characteristics. The topographic features such as flat, depression, ridge, and valley, are considered in this study. This simulation were analysed with Ansys FLUENT 14.0 software package. The result showed the topography characteristics influence the value of pressure coefficient and streamlines especially when the house was located at ridge terrain. The findings strongly suggested that wind analysis should include all topographic features in the analysis in order to establish the true wind force exerted on any structure.

  12. Isolating the Roles of Different Forcing Agents in Global Stratospheric Temperature Changes Using Model Integrations with Incrementally Added Single Forcings

    Science.gov (United States)

    Aquila, V.; Swartz, W. H.; Waugh, D. W.; Colarco, P. R.; Pawson, S.; Polvani, L. M.; Stolarski, R. S.

    2016-01-01

    Satellite instruments show a cooling of global stratospheric temperatures over the whole data record (1979-2014). This cooling is not linear and includes two descending steps in the early 1980s and mid-1990s. The 1979-1995 period is characterized by increasing concentrations of ozone depleting substances (ODS) and by the two major volcanic eruptions of El Chichon (1982) and Mount Pinatubo (1991). The 1995-present period is characterized by decreasing ODS concentrations and by the absence of major volcanic eruptions. Greenhouse gas (GHG) concentrations increase over the whole time period. In order to isolate the roles of different forcing agents in the global stratospheric temperature changes, we performed a set of AMIP-style simulations using the NASA Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). We find that in our model simulations the cooling of the stratosphere from 1979 to present is mostly driven by changes in GHG concentrations in the middle and upper stratosphere and by GHG and ODS changes in the lower stratosphere. While the cooling trend caused by increasing GHGs is roughly constant over the satellite era, changing ODS concentrations cause a significant stratospheric cooling only up to the mid-1990s, when they start to decrease because of the implementation of the Montreal Protocol. Sporadic volcanic events and the solar cycle have a distinct signature in the time series of stratospheric temperature anomalies but do not play a statistically significant role in the long-term trends from 1979 to 2014. Several factors combine to produce the step-like behavior in the stratospheric temperatures: in the lower stratosphere, the flattening starting in the mid-1990s is due to the decrease in ozone-depleting substances; Mount Pinatubo and the solar cycle cause the abrupt steps through the aerosol-associated warming and the volcanically induced ozone depletion. In the middle and upper stratosphere, changes in solar irradiance are largely

  13. Characterization of three porcine reproductive and respiratory syndrome virus isolates from a single swine farm bearing strong homology to a vaccine strain.

    Science.gov (United States)

    Jiang, Yi-feng; Xia, Tian-qi; Zhou, Yan-jun; Yu, Ling-xue; Yang, Shen; Huang, Qin-feng; Li, Li-wei; Gao, Fei; Qu, Ze-hui; Tong, Wu; Tong, Guang-zhi

    2015-09-30

    Three porcine reproductive and respiratory syndrome viruses (PRRSV), NT1, NT2, and NT3, were isolated from three dying piglets from a single pig farm in Jiangsu Province, China. Whole genome sequencing revealed that the three isolates share the highest homology with JXA1-P80, an attenuated vaccine strain developed by serial passage of highly pathogenic PRRSV JXA1 in MARC-145 cells. More than ten amino acids residues in ORF1a, ORF1b, GP4, and GP5 that were thought to be unique to JXA1 attenuated on MARC-145 cells were each found in the corresponding locations of NT1, NT2, and NT3. In virulence assays, piglets infected with NT1, NT2, or NT3 exhibited clinical signs of disease, including high fever, anorexia, and respiratory distress, leading to the death of the majority of the piglets within two weeks. Collectively, these data indicate that NT1, NT2, and NT3 are highly pathogenic PRRSVs and they are likely to be revertants of the vaccine strain JXA1-P80. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. A single mask process for the realization of fully-isolated, dual-height MEMS metallic structures separated by narrow gaps

    Science.gov (United States)

    Li, Yuan; Kim, Minsoo; Allen, Mark G.

    2018-02-01

    Multi-height metallic structures are of importance for various MEMS applications, including master molds for creating 3D structures by nanoimprint lithography, or realizing vertically displaced electrodes for out-of-plane electrostatic actuators. Normally these types of multi-height structures require a multi-mask process with increased fabrication complexity. In this work, a fabrication technology is presented in which fully-isolated, dual-height MEMS metallic structures separated by narrow gaps can be realized using a self-aligned, single-mask process. The main scheme of this proposed process is through-mold electrodeposition, where two photoresist mold fabrication steps and two electrodeposition steps are sequentially implemented to define the thinner and thicker structures in the dual-height configuration. The process relies on two self-aligned steps enabled by the electrodeposited thinner structures: a wet-etching of the seed layer utilizing the thinner structure as an etch-mask to electrically isolate the thinner and the thicker structures, and a backside UV lithography utilizing the thinner structure as a lithographic mask to create a high-aspect-ratio mold for the thicker structure through-mold electrodeposition. The latter step requires the metallic structures to be fabricated on a transparent substrate. Test structures with differences in aspect ratio are demonstrated to showcase the capability of the process.

  15. Enlarged facial pores: an update on treatments.

    Science.gov (United States)

    Dong, Joanna; Lanoue, Julien; Goldenberg, Gary

    2016-07-01

    Enlarged facial pores remain a common dermatologic and cosmetic concern from acne and rosacea, among other conditions, that is difficult to treat due to the multifactorial nature of their pathogenesis and negative impact on patients' quality of life. Enlarged facial pores are primarily treated through addressing associative factors, such as increased sebum production and cutaneous aging. We review the current treatment modalities for enlarged or dense facial pores, including topical retinoids, chemical peels, oral antiandrogens, and lasers and devices, with a focus on newer therapies.

  16. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias C.; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

    2009-01-01

    Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

  17. Effects of intermediate wettability on entry capillary pressure in angular pores.

    Science.gov (United States)

    Rabbani, Harris Sajjad; Joekar-Niasar, Vahid; Shokri, Nima

    2016-07-01

    Entry capillary pressure is one of the most important factors controlling drainage and remobilization of the capillary-trapped phases as it is the limiting factor against the two-phase displacement. It is known that the entry capillary pressure is rate dependent such that the inertia forces would enhance entry of the non-wetting phase into the pores. More importantly the entry capillary pressure is wettability dependent. However, while the movement of a meniscus into a strongly water-wet pore is well-defined, the invasion of a meniscus into a weak or intermediate water-wet pore especially in the case of angular pores is ambiguous. In this study using OpenFOAM software, high-resolution direct two-phase flow simulations of movement of a meniscus in a single capillary channel are performed. Interface dynamics in angular pores under drainage conditions have been simulated under constant flow rate boundary condition at different wettability conditions. Our results shows that the relation between the half corner angle of pores and contact angle controls the temporal evolution of capillary pressure during the invasion of a pore. By deviating from pure water-wet conditions, a dip in the temporal evolution of capillary pressure can be observed which will be pronounced in irregular angular cross sections. That enhances the pore invasion with a smaller differential pressure. The interplay between the contact angle and pore geometry can have significant implications for enhanced remobilization of ganglia in intermediate contact angles in real porous media morphologies, where pores are very heterogeneous with small shape factors. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Pore network quantification of sandstones under experimental CO2 injection using image analysis

    Science.gov (United States)

    Berrezueta, Edgar; González-Menéndez, Luís; Ordóñez-Casado, Berta; Olaya, Peter

    2015-04-01

    Automated-image identification and quantification of minerals, pores and textures together with petrographic analysis can be applied to improve pore system characterization in sedimentary rocks. Our case study is focused on the application of these techniques to study the evolution of rock pore network subjected to super critical CO2-injection. We have proposed a Digital Image Analysis (DIA) protocol that guarantees measurement reproducibility and reliability. This can be summarized in the following stages: (i) detailed description of mineralogy and texture (before and after CO2-injection) by optical and scanning electron microscopy (SEM) techniques using thin sections; (ii) adjustment and calibration of DIA tools; (iii) data acquisition protocol based on image capture with different polarization conditions (synchronized movement of polarizers); (iv) study and quantification by DIA that allow (a) identification and isolation of pixels that belong to the same category: minerals vs. pores in each sample and (b) measurement of changes in pore network, after the samples have been exposed to new conditions (in our case: SC-CO2-injection). Finally, interpretation of the petrography and the measured data by an automated approach were done. In our applied study, the DIA results highlight the changes observed by SEM and microscopic techniques, which consisted in a porosity increase when CO2 treatment occurs. Other additional changes were minor: variations in the roughness and roundness of pore edges, and pore aspect ratio, shown in the bigger pore population. Additionally, statistic tests of pore parameters measured were applied to verify that the differences observed between samples before and after CO2-injection were significant.

  19. Valve seat pores sealed with thermosetting monomer

    Science.gov (United States)

    Olmore, A. B.

    1966-01-01

    Hard anodic coating provides a smooth wear resistant value seating surface on a cast aluminum alloy valve body. Vacuum impregnation with a thermosetting monomer, diallyl phthalate, seals the pores on the coating to prevent galvanic corrosion.

  20. Estimation of pore pressure from seismic velocities

    International Nuclear Information System (INIS)

    Perez, Zayra; Ojeda, German Y; Mateus, Darwin

    2009-01-01

    On pore pressure calculations it is common to obtain a profile in a well bore, which is then extrapolated toward offset wells. This practice might generate mistakes on pore pressure measurements, since geological conditions may change from a well bore to another, even into the same basin. Therefore, it is important to use other tools which allow engineers not only to detect and estimate in an indirect way overpressure zones, but also to keep a lateral tracking of possible changes that may affect those values in the different formations. Taking into account this situation, we applied a methodology that estimates formation pressure from 3D seismic velocities by using the Eaton method. First, we estimated formation pore pressure; then, we identified possible overpressure zones. Finally, those results obtained from seismic information were analyzed involving well logs and pore pressure tests, in order to compare real data with prediction based on seismic information from the Colombian foothill.

  1. OBSERVATIONS OF SAUSAGE MODES IN MAGNETIC PORES

    International Nuclear Information System (INIS)

    Morton, R. J.; Erdelyi, R.; Jess, D. B.; Mathioudakis, M.

    2011-01-01

    We present here evidence for the observation of the magnetohydrodynamic (MHD) sausage modes in magnetic pores in the solar photosphere. Further evidence for the omnipresent nature of acoustic global modes is also found. The empirical decomposition method of wave analysis is used to identify the oscillations detected through a 4170 A 'blue continuum' filter observed with the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument. Out of phase, periodic behavior in pore size and intensity is used as an indicator of the presence of magnetoacoustic sausage oscillations. Multiple signatures of the magnetoacoustic sausage mode are found in a number of pores. The periods range from as short as 30 s up to 450 s. A number of the magnetoacoustic sausage mode oscillations found have periods of 3 and 5 minutes, similar to the acoustic global modes of the solar interior. It is proposed that these global oscillations could be the driver of the sausage-type magnetoacoustic MHD wave modes in pores.

  2. Discrimination of Single-Copy IS6110 DNA Fingerprints of Mycobacterium tuberculosis Isolates by High-Resolution Minisatellite-Based Typing

    OpenAIRE

    Lee, Ann S. G.; Tang, Lynn L. H.; Lim, Irene H. K.; Bellamy, Richard; Wong, Sin-Yew

    2002-01-01

    Seven isoniazid-resistant isolates with mutations in the NADH dehydrogenase (ndh) gene were molecularly typed by IS6110-based restriction fragment length polymorphism analysis. All seven isolates with the R268H mutation had identical 1.4-kb IS6110 fingerprints. High-resolution minisatellite-based typing discriminated five of these isolates; two isolates were identical.

  3. Discrimination of single-copy IS6110 DNA fingerprints of Mycobacterium tuberculosis isolates by high-resolution minisatellite-based typing.

    Science.gov (United States)

    Lee, Ann S G; Tang, Lynn L H; Lim, Irene H K; Bellamy, Richard; Wong, Sin-Yew

    2002-02-01

    Seven isoniazid-resistant isolates with mutations in the NADH dehydrogenase (ndh) gene were molecularly typed by IS6110-based restriction fragment length polymorphism analysis. All seven isolates with the R268H mutation had identical 1.4-kb IS6110 fingerprints. High-resolution minisatellite-based typing discriminated five of these isolates; two isolates were identical.

  4. Characterization of the Respiration-Induced Yeast Mitochondrial Permeability Transition Pore

    OpenAIRE

    Bradshaw, Patrick C.; Pfeiffer, Douglas R.

    2013-01-01

    When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable throug...

  5. Optimization of single plate-serial dilution spotting (SP-SDS) with sample anchoring as an assured method for bacterial and yeast cfu enumeration and single colony isolation from diverse samples.

    Science.gov (United States)

    Thomas, Pious; Sekhar, Aparna C; Upreti, Reshmi; Mujawar, Mohammad M; Pasha, Sadiq S

    2015-12-01

    We propose a simple technique for bacterial and yeast cfu estimations from diverse samples with no prior idea of viable counts, designated as single plate-serial dilution spotting (SP-SDS) with the prime recommendation of sample anchoring (10 0 stocks). For pure cultures, serial dilutions were prepared from 0.1 OD (10 0 ) stock and 20 μl aliquots of six dilutions (10 1 -10 6 ) were applied as 10-15 micro-drops in six sectors over agar-gelled medium in 9-cm plates. For liquid samples 10 0 -10 5 dilutions, and for colloidal suspensions and solid samples (10% w/v), 10 1 -10 6 dilutions were used. Following incubation, at least one dilution level yielded 6-60 cfu per sector comparable to the standard method involving 100 μl samples. Tested on diverse bacteria, composite samples and Saccharomyces cerevisiae , SP-SDS offered wider applicability over alternative methods like drop-plating and track-dilution for cfu estimation, single colony isolation and culture purity testing, particularly suiting low resource settings.

  6. Pore network modeling of drainage process in patterned porous media: a quasi-static study

    KAUST Repository

    Zhang, Tao; Salama, Amgad; Sun, Shuyu; El-Amin, Mohamed

    2015-01-01

    -saturation relationships, it is quite challenging to isolate its effects explicitly in real porous media applications. However, within the framework of pore network models, it is easy to highlight the effects of wettability conditions on the transport of two-phase systems

  7. Emulsification kinetics during quasi-miscible flow in dead-end pores

    Science.gov (United States)

    Broens, M.; Unsal, E.

    2018-03-01

    Microemulsions have found applications as carriers for the transport of solutes through various porous media. They are commonly pre-prepared in bulk form, and then injected into the medium. The preparation is done by actively mixing the surfactant, water and oil, and then allowing the mixture to stagnate until equilibrium is reached. The resulting microemulsion characteristics of the surfactant/oil/water system are studied at equilibrium conditions, and perfect mixing is assumed. But in applications like subsurface remediation and enhanced oil recovery, microemulsion formation may occur in the pore space. Surfactant solutions are injected into the ground to solubilize and/or mobilize the non-aqueous phase liquids (NAPLs) by in-situ emulsification. Flow dynamics and emulsification kinetics are coupled, which also contributes to in-situ mixing. In this study, we investigated the nature of such coupling for a quasi-miscible fluid system in a conductive channel with dead-end extensions. A microfluidic setup was used, where an aqueous solution of an anionic, internal olefin sulfonate 20-24 (IOS) surfactant was injected into n-decane saturated glass micromodel. The oil phase was coloured using a solvatochromatic dye allowing for direct visualization of the aqueous and oil phases as well as their microemulsions under fluorescent light. Presence of both conductive and stagnant dead-end channels in a single pore system made it possible to isolate different transport mechanisms from each other but also allowed to study the transitions from one to the other. In the conductive channel, the surfactant was carried with flow, and emulsification was controlled by the localized flow dynamics. In the stagnant zones, the driving force of the mass transfer was driven by the chemical concentration gradient. Some of the equilibrium phase behaviour characteristics of the surfactant/oil/water system were recognisable during the quasi-miscible displacement. However, the equilibrium tests

  8. Single- and Multispecies Biofilms by Escherichia coli, Staphylococcus aureus, and Salmonella spp. Isolated from Raw Fish and a Fish Processing Unit

    Directory of Open Access Journals (Sweden)

    Jesieli Braz Frozi

    2017-09-01

    Full Text Available ABSTRACT: The consumption of fish by the Brazilian population is increasing. However, fish and seafood are highly perishable and can be contaminated with several microorganisms. In addition, the possibility of biofilm formation is a greater cause for concern. In this study, biofilm formation was evaluated in single- and multispecies cultures at 25°C for incubation periods of 0, 4, 8, 24, and 48h in stainless steel coupons (size, 1.0×1.0cm immersed in tryptic soy broth. The characteristics of the formed biofilms after sanitizing by immersing the coupons in 200ppm sodium hypochlorite solution for 10min were also evaluated under the same experimental conditions but with some modifications. Biofilm structure was evaluated using scanning electron microscopy. Analysis of single-species biofilms indicated that all bacterial strains formed biofilms at different intervals without any statistically significant difference. However, comparison of the growth of single- and multispecies cultures indicated a significantly higher biofilm formation by the pure cultures. In multispecies biofilms, compared with the other microorganisms, growth of Salmonella spp. was significantly lower for all tested incubation periods; whereas, of Staphylococcus aureus was significantly higher than that of E. coli until 8h of incubation; the differences in growth were not significantly different after this incubation period. Sanitizing with sodium hypochlorite was effective because no cell growth was observed in the coupons that were treated with 200ppm sodium hypochlorite for 10min. This study demonstrated the ability of isolated microorganisms to form biofilms, reinforcing the need for food handling establishments to adopt good manufacturing practices, developing adequate protocols for cleaning and disinfecting surfaces and equipment used in food production, maintaining and replacing equipment when necessary.

  9. Visualization of enzyme activities inside earthworm pores

    Science.gov (United States)

    Hoang, Duyen; Razavi, Bahar S.

    2015-04-01

    In extremely dynamic microhabitats as bio-pores made by earthworm, the in situ enzyme activities are assumed as a footprint of complex biotic interactions. Our study focused on the effect of earthworm on the enzyme activities inside bio-pores and visualizing the differences between bio-pores and earthworm-free soil by zymography technique (Spohn and Kuzyakov, 2013). For the first time, we aimed at quantitative imaging of enzyme activities in bio-pores. Lumbricus terrestris L. was placed into transparent box (15×20×15cm). After two weeks when bio-pore systems were formed by earthworms, we visualized in situ enzyme activities of five hydrolytic enzymes (β-glucosidase, cellobiohydrolase, chitinase, xylanase, leucine-aminopeptidase, and phosphatase. Zymography showed higher activity of β-glucosidase, chitinase, xylanase and phosphatase in biopores comparing to bulk soil. However, the differences in activity of cellobiohydrolase and leucine aminopeptidase between bio-pore and bulk soil were less pronounced. This demonstrated an applicability of zymography approach to monitor and to distinguish the in situ activity of hydrolytic enzymes in soil biopores.

  10. Silicon pore optics for the international x-ray observatory

    Science.gov (United States)

    Wille, E.; Wallace, K.; Bavdaz, M.; Collon, M. J.; Günther, R.; Ackermann, M.; Beijersbergen, M. W.; Riekerink, M. O.; Blom, M.; Lansdorp, B.; de Vreede, L.

    2017-11-01

    Lightweight X-ray Wolter optics with a high angular resolution will enable the next generation of X-ray telescopes in space. The International X-ray Observatory (IXO) requires a mirror assembly of 3 m2 effective area (at 1.5 keV) and an angular resolution of 5 arcsec. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor industry. We present the manufacturing process ranging from single mirror plates towards complete focusing mirror modules mounted in flight configuration. The performance of the mirror modules is tested using X-ray pencil beams or full X-ray illumination. In 2009, an angular resolution of 9 arcsec was achieved, demonstrating the improvement of the technology compared to 17 arcsec in 2007. Further development activities of Silicon Pore Optics concentrate on ruggedizing the mounting system and performing environmental tests, integrating baffles into the mirror modules and assessing the mass production.

  11. Multiscale Pore Throat Network Reconstruction of Tight Porous Media Constrained by Mercury Intrusion Capillary Pressure and Nuclear Magnetic Resonance Measurements

    Science.gov (United States)

    Xu, R.; Prodanovic, M.

    2017-12-01

    Due to the low porosity and permeability of tight porous media, hydrocarbon productivity strongly depends on the pore structure. Effective characterization of pore/throat sizes and reconstruction of their connectivity in tight porous media remains challenging. Having a representative pore throat network, however, is valuable for calculation of other petrophysical properties such as permeability, which is time-consuming and costly to obtain by experimental measurements. Due to a wide range of length scales encountered, a combination of experimental methods is usually required to obtain a comprehensive picture of the pore-body and pore-throat size distributions. In this work, we combine mercury intrusion capillary pressure (MICP) and nuclear magnetic resonance (NMR) measurements by percolation theory to derive pore-body size distribution, following the work by Daigle et al. (2015). However, in their work, the actual pore-throat sizes and the distribution of coordination numbers are not well-defined. To compensate for that, we build a 3D unstructured two-scale pore throat network model initialized by the measured porosity and the calculated pore-body size distributions, with a tunable pore-throat size and coordination number distribution, which we further determine by matching the capillary pressure vs. saturation curve from MICP measurement, based on the fact that the mercury intrusion process is controlled by both the pore/throat size distributions and the connectivity of the pore system. We validate our model by characterizing several core samples from tight Middle East carbonate, and use the network model to predict the apparent permeability of the samples under single phase fluid flow condition. Results show that the permeability we get is in reasonable agreement with the Coreval experimental measurements. The pore throat network we get can be used to further calculate relative permeability curves and simulate multiphase flow behavior, which will provide valuable

  12. Pore REconstruction and Segmentation (PORES) method for improved porosity quantification of nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Van Eyndhoven, G., E-mail: geert.vaneyndhoven@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Kurttepeli, M. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Van Oers, C.J.; Cool, P. [Laboratory of Adsorption and Catalysis, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Bals, S. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Batenburg, K.J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Centrum Wiskunde and Informatica, Science Park 123, NL-1090 GB Amsterdam (Netherlands); Mathematical Institute, Universiteit Leiden, Niels Bohrweg 1, NL-2333 CA Leiden (Netherlands); Sijbers, J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium)

    2015-01-15

    Electron tomography is currently a versatile tool to investigate the connection between the structure and properties of nanomaterials. However, a quantitative interpretation of electron tomography results is still far from straightforward. Especially accurate quantification of pore-space is hampered by artifacts introduced in all steps of the processing chain, i.e., acquisition, reconstruction, segmentation and quantification. Furthermore, most common approaches require subjective manual user input. In this paper, the PORES algorithm “POre REconstruction and Segmentation” is introduced; it is a tailor-made, integral approach, for the reconstruction, segmentation, and quantification of porous nanomaterials. The PORES processing chain starts by calculating a reconstruction with a nanoporous-specific reconstruction algorithm: the Simultaneous Update of Pore Pixels by iterative REconstruction and Simple Segmentation algorithm (SUPPRESS). It classifies the interior region to the pores during reconstruction, while reconstructing the remaining region by reducing the error with respect to the acquired electron microscopy data. The SUPPRESS reconstruction can be directly plugged into the remaining processing chain of the PORES algorithm, resulting in accurate individual pore quantification and full sample pore statistics. The proposed approach was extensively validated on both simulated and experimental data, indicating its ability to generate accurate statistics of nanoporous materials. - Highlights: • An electron tomography reconstruction/segmentation method for nanoporous materials. • The method exploits the porous nature of the scanned material. • Validated extensively on both simulation and real data experiments. • Results in increased image resolution and improved porosity quantification.

  13. Active pore space utilization in nanoporous carbon-based supercapacitors: Effects of conductivity and pore accessibility

    Science.gov (United States)

    Seredych, Mykola; Koscinski, Mikolaj; Sliwinska-Bartkowiak, Malgorzata; Bandosz, Teresa J.

    2012-12-01

    Composites of commercial graphene and nanoporous sodium-salt-polymer-derived carbons were prepared with 5 or 20 weight% graphene. The materials were characterized using the adsorption of nitrogen, SEM/EDX, thermal analysis, Raman spectroscopy and potentiometric titration. The samples' conductivity was also measured. The performance of the carbon composites in energy storage was linked to their porosity and electronic conductivity. The small pores (<0.7) were found as very active for double layer capacitance. It was demonstrated that when double layer capacitance is a predominant mechanism of charge storage, the degree of the pore space utilization for that storage can be increased by increasing the conductivity of the carbons. That active pore space utilization is defined as gravimetric capacitance per unit pore volume in pores smaller than 0.7 nm. Its magnitude is affected by conductivity of the carbon materials. The functional groups, besides pseudocapacitive contribution, increased the wettability and thus the degree of the pore space utilization. Graphene phase, owing to its conductivity, also took part in an insitu increase of the small pore accessibility and thus the capacitance of the composites via enhancing an electron transfer to small pores and thus imposing the reduction of groups blocking the pores for electrolyte ions.

  14. Notice of Violation of IEEE Publication PrinciplesJoint Redundant Residue Number Systems and Module Isolation for Mitigating Single Event Multiple Bit Upsets in Datapath

    Science.gov (United States)

    Li, Lei; Hu, Jianhao

    2010-12-01

    Notice of Violation of IEEE Publication Principles"Joint Redundant Residue Number Systems and Module Isolation for Mitigating Single Event Multiple Bit Upsets in Datapath"by Lei Li and Jianhao Hu,in the IEEE Transactions on Nuclear Science, vol.57, no.6, Dec. 2010, pp. 3779-3786After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE's Publication Principles.This paper contains substantial duplication of original text from the paper cited below. The original text was copied without attribution (including appropriate references to the original author(s) and/or paper title) and without permission.Due to the nature of this violation, reasonable effort should be made to remove all past references to this paper, and future references should be made to the following articles:"Multiple Error Detection and Correction Based on Redundant Residue Number Systems"by Vik Tor Goh and M.U. Siddiqi,in the IEEE Transactions on Communications, vol.56, no.3, March 2008, pp.325-330"A Coding Theory Approach to Error Control in Redundant Residue Number Systems. I: Theory and Single Error Correction"by H. Krishna, K-Y. Lin, and J-D. Sun, in the IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, vol.39, no.1, Jan 1992, pp.8-17In this paper, we propose a joint scheme which combines redundant residue number systems (RRNS) with module isolation (MI) for mitigating single event multiple bit upsets (SEMBUs) in datapath. The proposed hardening scheme employs redundant residues to improve the fault tolerance for datapath and module spacings to guarantee that SEMBUs caused by charge sharing do not propagate among the operation channels of different moduli. The features of RRNS, such as independence, parallel and error correction, are exploited to establish the radiation hardening architecture for the datapath in radiation environments. In the proposed

  15. Pore formation and occurrence in the organic-rich shales of the Triassic Chang-7 Member, Yanchang Formation, Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Chuang Er

    2016-12-01

    Full Text Available Shale-reservoir appraisal depends greatly on its pore characteristics (e.g., diameter, geometry, connectivity. Using a new pore-classification scheme based on the matrix type and occurrence state, four types of pores are identified in the organic-rich shales of the Triassic Chang-7 Member: intergranular, intragranular, organic pore, and microfracture. The intergranular pores are subdivided into primary pores between clastic grains, clay-mineral aggregates, and secondary dissolution pores between clastic grains or clay-mineral aggregates based on their origins, respectively. The intragranular pores are subdivided into secondary dissolved pores in feldspars, intra-clay-mineral aggregates and inter-pyrite. Organic pores include primarily microfractures in the organic matter and isolated organic pores. Microfracture is mainly developed along sandy and muddy laminations. Analysis by integration of data from pore imaging, low-temperature liquid nitrogen absorption, relationships between pore geometry and mineral components and between TOC and maturity of organic matter indicates that depositional environment, diagenesis, and thermal evolution of organic matter controlled the formation and preservation of pores. Organic-rich shales deposited in a deep and semi-deep lake environment contains thinly bedded turbidite sandstones, which are characterized by high content of clastic particles and thus favor the development of primary intergranular and intragranular pores, as well as microfractures along sandy laminations. During the early diagenesis process, precipitation of pyrite favors the development of inter-pyrite pores. However, compaction reduced the diameter and bulk pore volume. Organic pore has been greatly reduced under compaction. Dissolution led to formation of both inter and intra-feldspar pores, which has improved reservoir quality to some extent. Organic pore started to develop after shale maturity reaches a threshold (RO = 0

  16. Single Nucleotide Polymorphisms in Regulator-Encoding Genes Have an Additive Effect on Virulence Gene Expression in a Vibrio cholerae Clinical Isolate.

    Science.gov (United States)

    Carignan, Bailey M; Brumfield, Kyle D; Son, Mike S

    2016-01-01

    Vibrio cholerae is the etiological agent of the infectious disease cholera, which is characterized by vomiting and severe watery diarrhea. Recently, V. cholerae clinical isolates have demonstrated increased virulence capabilities, causing more severe symptoms with a much higher rate of disease progression than previously observed. We have identified single nucleotide polymorphisms (SNPs) in four virulence-regulatory genes (hapR, hns, luxO, and vieA) of a hypervirulent V. cholerae clinical isolate, MQ1795. Herein, all SNPs and SNP combinations of interest were introduced into the prototypical El Tor reference strain N16961, and the effects on the production of numerous virulence-related factors, including cholera toxin (CT), the toxin-coregulated pilus (TCP), and ToxT, were analyzed. Our data show that triple-SNP (hapR hns luxO and hns luxO vieA) and quadruple-SNP combinations produced the greatest increases in CT, TCP, and ToxT production. The hns and hns luxO SNP combinations were sufficient for increased TCP and ToxT production. Notably, the hns luxO vieA triple-SNP combination strain produced TCP and ToxT levels similar to those of MQ1795. Certain SNP combinations (hapR and hapR vieA) had the opposite effect on CT, TCP, and ToxT expression. Interestingly, the hns vieA double-SNP combination strain increased TCP production while decreasing CT production. Our findings suggest that SNPs identified in the four regulatory genes, in various combinations, are associated with increased virulence capabilities observed in V. cholerae clinical isolates. These studies provide insight into the evolution of highly virulent strains. IMPORTANCE Cholera, an infectious disease of the small intestine caused by the aquatic bacterium Vibrio cholerae, often results in vomiting and acute watery diarrhea. If left untreated or if the response is too slow, the symptoms can quickly lead to extreme dehydration and ultimately death of the patient. Recent anecdotal evidence of cholera

  17. Pore and surface diffusion in multicomponent adsorption and liquid chromatography systems

    International Nuclear Information System (INIS)

    Ma, Z.; Whitley, R.D.; Wang, N.H.L.

    1996-01-01

    A generalized parallel pore and surface diffusion model for multicomponent adsorption and liquid chromatography is formulated and solved numerically. Analytical solution for first- and second-order central moments for a pulse on a plateau input is used as benchmarks for the numerical solutions. Theoretical predictions are compared with experimental data for two systems: ion-exchange of strontium, sodium, and calcium in a zeolite and competitive adsorption of two organics on activated carbon. In a linear isotherm region of single-component systems, both surface and pore diffusion cause symmetric spreading in breakthrough curves. In a highly nonlinear isotherm region, however, surface diffusion causes pronounced tailing in breakthrough curves; the larger the step change in concentration, the more pronounced tailing, in contrast to relatively symmetric breakthroughs due to pore diffusion. If only a single diffusion mechanism is assumed in analyzing the data of parallel diffusion systems, a concentration-dependent apparent surface diffusivity or pore diffusivity results; for a convex isotherm, the apparent surface diffusivity increases, whereas the apparent pore diffusivity decreases with increasing concentration. For a multicomponent nonlinear system, elution order can change if pore diffusion dominates for a low-affinity solute, whereas surface diffusion dominates for a high-affinity solute

  18. Facial skin pores: a multiethnic study.

    Science.gov (United States)

    Flament, Frederic; Francois, Ghislain; Qiu, Huixia; Ye, Chengda; Hanaya, Tomoo; Batisse, Dominique; Cointereau-Chardon, Suzy; Seixas, Mirela Donato Gianeti; Dal Belo, Susi Elaine; Bazin, Roland

    2015-01-01

    Skin pores (SP), as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc) that generate many aesthetic concerns or complaints. Despite the prevalence of skin pores, related literature is scarce. With the aim of describing the prevalence of skin pores and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin pores (size, density, coverage) on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 μm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm(2)) and determination of their respective sizes in mm(2). Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage) that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1) were recorded in all studied subjects; 2) varied greatly with ethnicity; 3) plateaued with age in most cases; and 4) globally refected self-assessment by subjects, in particular those who self-declare having "enlarged pores" like Brazilian women. Inversely, Chinese women were clearly distinct from other ethnicities in having very low density and sizes. Analyzing the present results suggests that facial skin pore's morphology as perceived by human eye less result from functional criteria of associated appendages such as sebaceous glands. To what extent skin pores may be viewed as additional criteria of a photo-altered skin is an issue to be further addressed.

  19. Swelling and gas release of grain-boundary pores in uranium dioxide

    International Nuclear Information System (INIS)

    Schrire, D.I.

    1983-12-01

    The swelling and gas release of overpressured grain boundary pores is sintered unirradiated uranium dioxide were investigated under isothermal conditions. The pores became overpressured when the ambient pressure was reduced, and the excess pressure driving force caused growth and interconnection of the pores, leading to eventual gas release. Swelling was measured continuously by a linear variable differential transformer, and open and closed porosity fractions were determined after the tests by immersion density and quantitative microscopy measurements. The sinter porosity consisted of pores situated on grain faces, grain edges, and grain corners. Isolated pores maintained their equilibrium shape while growing, without any measurable change in dihedral angle. Interconnection occurred predominantly along grain edges, without any evidence of pore sharpening or crack propagation at low driving forces. Extensive open porosity occurred at a threshold density of about 85% TD. There was an almost linear dependence of the initial swelling rate on the driving force, with an activation energy of 200+- 8 kJ/mole, in good agreement with published values of the activation energy for grain boundary diffusion

  20. Comparison of single photon emission computed tomography-computed tomography, computed tomography, single photon emission computed tomography and planar scintigraphy for characterization of isolated skull lesions seen on bone scintigraphy in cancer patients

    International Nuclear Information System (INIS)

    Sharma, Punit; Jain, Tarun Kumar; Reddy, Rama Mohan; Faizi, Nauroze Ashgar; Bal, Chandrasekhar; Malhotra, Arun; Kumar, Rakesh

    2014-01-01

    The purpose of this study is to evaluate the added value of single photon emission computed tomography-computed tomography (SPECT-CT) over planar scintigraphy, SPECT and CT alone for characterization of isolated skull lesions in bone scintigraphy (BS) in cancer patients. A total of 32 cancer patients (age: 39.5 ± 21.9; male: female - 1:1) with 36 isolated skull lesions on planar BS, underwent SPECT-CT of skull. Planar BS, SPECT, CT and SPECT-CT images were evaluated in separate sessions to minimize recall bias. A scoring scale of 1-5 was used, where 1 is definitely metastatic, 2 is probably metastatic, 3 is indeterminate, 4 is probably benign and 5 is definitely benign. With receiver operating characteristic analysis area under the curves (AUC) was calculated for each modality. For calculation of sensitivity, specificity and predictive values a Score ≤3 was taken as metastatic. Clinical/imaging follow-up and/or histopathology were taken as reference standard. Of 36 skull lesions 11 lesions each were on frontal, parietal and occipital bone while three lesions were in the temporal bone. Of these 36 lesions, 16 were indeterminate (Score-3) on planar and SPECT, five on CT and none on SPECT-CT. The AUC was largest for SPECT-CT followed by CT, SPECT and planar scintigraphy, respectively. Planar scintigraphy was inferior to SPECT-CT (P = 0.006) and CT (P = 0.012) but not SPECT (P = 0.975). SPECT was also inferior to SPECT-CT (P = 0.007) and CT (P = 0.015). Although no significant difference was found between SPECT-CT and CT (P = 0.469), the former was more specific (100% vs. 94%). SPECT-CT is better than planar scintigraphy and SPECT alone for correctly characterizing isolated skull lesions on BS in cancer patients. It is more specific than CT, but provides no significant advantage over CT alone for this purpose

  1. Percutaneous nephroscopic management of an isolated giant renal hydatid cyst guided by single-incision laparoscopy using conventional instruments: the Santosh-PGI technique.

    Science.gov (United States)

    Kumar, Santosh; Choudhary, Gautam R; Pushkarna, Arawat; Najjapa, Bhuvnesh; Ht, Vatasla

    2013-11-01

    Isolated renal hydatid rarely presents, but when it does occur, it requires surgical treatment. We report our experience with a novel technique involving percutaneous management of a giant renal hydatid cyst with single-incision laparoscopic assistance. First we performed retrograde ureteropyelogram, which did not show any communication between the cyst and the calyceal. A Veress needle was used for pneumoperitoneum. Three conventional laparoscopic trocars used. Under laparoscopic guidance, we punctured the cyst. The scolicidal solution used was 10% povidone-iodine. The endocyst was removed under vision with grasping forceps through the nephroscope. A Portex drain was placed into the cyst cavity. Percutaneous aspiration and instillation of scolicidal agents followed by re-aspiration have been previously reported. This is an attractive procedure because of its acceptable success rates and reduced morbidity. In our case, simple aspiration of the cyst would not have been successful because the cyst was full of daughter cysts. Also, a blind percutaneous puncture of the cyst and dilatation could have perforated the colon or the mesocolon, which is often wrapped over the surface of such giant cysts thereby making laparoscopic guidance and mobilization of the colon imperative. We devised this unique treatment method for this patient involving three conventional ports at a single umbilical site. We believe this is the first reported case of its kind in the world. Not only this technique is minimally invasive, it is also cost-effective, as only conventional laparoscopic ports and instruments are used during the procedure. © 2013 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.

  2. Using BIB-SEM to determine pore morphology and pore size distributions in coal macerals

    Energy Technology Data Exchange (ETDEWEB)

    Giffin, S.; Littke, R. [RWTH Aachen Univ. (Germany). Inst. of Geology and Geochemistry of Petroleum and Coal; Klaver, J.; Urai, J.L. [RWTH Aachen Univ. (Germany). Structural Geology, Tectonics and Geomechanics

    2013-08-01

    The composition of coalbeds is considerably heterogeneous, affecting the transport pathways for fluids within the coal. Transport pathways include cleats and larger pores. However, only a few clues exist as the nature of these pores. This study examines the morphology and distribution of macro- and mesopores in coal samples, using broad ion beam (BIB) milling to prepare relief- and damage-free polished surfaces of coal samples for high-resolution SEM imaging. Broad ion beam milling is advantageous to focused ion beam milling in that a larger surface area can be milled. Combining that with SEM imaging results in a useful tool to study pore morphology and distributions in the size range between 10 nm and 10 {mu}m. Since BIB-sections of a few square millimeters are not large enough to be statistically representative, results cannot be easily interpreted from a coal seam standpoint. Therefore, porosity was investigated as a function of maceral type to characterize pore morphologies. Macerals from the vitrinite and inertinite groups were selected with a known relationship to bedding. BIB-sections were milled parallel to bedding and perpendicular to bedding, and the pores were evaluated in each section. The goal of this study is to (1) qualitatively describe pore morphology with respect to maceral type and (2) quantitatively characterize pore size distributions with respect to maceral and in relationship to bedding. Our results lead to a better understanding of bulk coal porosity due to the visual, spatial representation and quantification of pores in individual macerals. (orig.)

  3. TIG Dressing Effects on Weld Pores and Pore Cracking of Titanium Weldments

    Directory of Open Access Journals (Sweden)

    Hui-Jun Yi

    2016-10-01

    Full Text Available Weld pores redistribution, the effectiveness of using tungsten inert gas (TIG dressing to remove weld pores, and changes in the mechanical properties due to the TIG dressing of Ti-3Al-2.5V weldments were studied. Moreover, weld cracks due to pores were investigated. The results show that weld pores less than 300 μm in size are redistributed or removed via remelting due to TIG dressing. Regardless of the temperature condition, TIG dressing welding showed ductility, and there was a loss of 7% tensile strength of the weldments. Additionally, it was considered that porosity redistribution by TIG dressing was due to fluid flow during the remelting of the weld pool. Weld cracks in titanium weldment create branch cracks around pores that propagate via the intragranular fracture, and oxygen is dispersed around the pores. It is suggested that the pore locations around the LBZ (local brittle zone and stress concentration due to the pores have significant effects on crack initiation and propagation.

  4. Quantifying the effect of water activity and storage temperature on single spore lag times of three moulds isolated from spoiled bakery products.

    Science.gov (United States)

    Dagnas, Stéphane; Gougouli, Maria; Onno, Bernard; Koutsoumanis, Konstantinos P; Membré, Jeanne-Marie

    2017-01-02

    The inhibitory effect of water activity (a w ) and storage temperature on single spore lag times of Aspergillus niger, Eurotium repens (Aspergillus pseudoglaucus) and Penicillium corylophilum strains isolated from spoiled bakery products, was quantified. A full factorial design was set up for each strain. Data were collected at levels of a w varying from 0.80 to 0.98 and temperature from 15 to 35°C. Experiments were performed on malt agar, at pH5.5. When growth was observed, ca 20 individual growth kinetics per condition were recorded up to 35days. Radius of the colony vs time was then fitted with the Buchanan primary model. For each experimental condition, a lag time variability was observed, it was characterized by its mean, standard deviation (sd) and 5 th percentile, after a Normal distribution fit. As the environmental conditions became stressful (e.g. storage temperature and a w lower), mean and sd of single spore lag time distribution increased, indicating longer lag times and higher variability. The relationship between mean and sd followed a monotonous but not linear pattern, identical whatever the species. Next, secondary models were deployed to estimate the cardinal values (minimal, optimal and maximal temperatures, minimal water activity where no growth is observed anymore) for the three species. That enabled to confirm the observation made based on raw data analysis: concerning the temperature effect, A. niger behaviour was significantly different from E. repens and P. corylophilum: T opt of 37.4°C (standard deviation 1.4°C) instead of 27.1°C (1.4°C) and 25.2°C (1.2°C), respectively. Concerning the a w effect, from the three mould species, E. repens was the species able to grow at the lowest a w (aw min estimated to 0.74 (0.02)). Finally, results obtained with single spores were compared to findings from a previous study carried out at the population level (Dagnas et al., 2014). For short lag times (≤5days), there was no difference between lag

  5. Dependence of cell adhesion on extracellular matrix materials formed on pore bridge boundaries by nanopore opening and closing geometry.

    Science.gov (United States)

    Kim, Sueon; Han, Dong Yeol; Chen, Zhenzhong; Lee, Won Gu

    2018-04-30

    In this study, we report experimental results for characterization of the growth and formation of pore bridge materials that modified the adhesion structures of cells cultured on nanomembranes with opening and closing geometry. To perform the proof-of-concept experiments, we fabricated two types of anodized alumina oxide substrates with single-sided opening (i.e., one side open, but closed at the other side) and double-sided opening (i.e., both sides open). In our experiment, we compared the densities of pores formed and of bridge materials which differently act as connective proteins depending on the size of pores. The results show that the pore opening geometry can be used to promote the net contact force between pores, resulting in the growth and formation of pore bridge materials before and after cell culture. The results also imply that the bridge materials can be used to attract the structural protrusion of filopodia that can promote the adhesion of cell-to-cell and cell-to-pore bridge. It is observed that the shape and size of cellular structures of filopodia depend on the presence of pore bridge materials. Overall, this observation brought us a significant clue that cells cultured on nanopore substrates would change the adhesion property depending on not only the formation of nanopores formed on the surface of topological substrates, but also that of pore bridge materials by its morphological growth.

  6. Moving Magnetic Features Around a Pore

    Energy Technology Data Exchange (ETDEWEB)

    Kaithakkal, A. J.; Riethmüller, T. L.; Solanki, S. K.; Lagg, A.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; VanNoort, M. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, Göttingen D-37077 (Germany); Rodríguez, J. Blanco [Grupo de Astronomía y Ciencias del Espacio, Universidad de Valencia, E-46980 Paterna, Valencia (Spain); Iniesta, J. C. Del Toro; Suárez, D. Orozco [Instituto de Astrofísica de Andalucía (CSIC), Apartado de Correos 3004, E-18080 Granada (Spain); Schmidt, W. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg (Germany); Pillet, V. Martínez [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Knölker, M., E-mail: anjali@mps.mpg.de [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States)

    2017-03-01

    Spectropolarimetric observations from Sunrise/IMaX, obtained in 2013 June, are used for a statistical analysis to determine the physical properties of moving magnetic features (MMFs) observed near a pore. MMFs of the same and opposite polarity, with respect to the pore, are found to stream from its border at an average speed of 1.3 km s{sup −1} and 1.2 km s{sup −1}, respectively, with mainly same-polarity MMFs found further away from the pore. MMFs of both polarities are found to harbor rather weak, inclined magnetic fields. Opposite-polarity MMFs are blueshifted, whereas same-polarity MMFs do not show any preference for up- or downflows. Most of the MMFs are found to be of sub-arcsecond size and carry a mean flux of ∼1.2 × 10{sup 17} Mx.

  7. Gas transport and subsoil pore characteristics

    DEFF Research Database (Denmark)

    Berisso, Feto Esimo; Schjønning, Per; Keller, Thomas

    2013-01-01

    Arrangements of elementary soil particles during soil deposition and subsequent biological and physical processes in long-term pedogenesis are expected to lead to anisotropy of the non-tilled subsoil pore system. Soil compaction by agricultural machinery is known to affect soil pore characteristics...... were sampled in vertical and horizontal directions from 0.3, 0.5, 0.7 and 0.9 m depth (the two lower depths only in Sweden). In the laboratory, water retention, air permeability (ka) and gas diffusivity (Ds/D0) were determined. For the sandy clay loam, morphological characteristics of pores (effective......). In the sandy clay loam soil, dB and nB displayed significant anisotropy (FAcharacteristics because of its origin...

  8. Transport of water molecules through noncylindrical pores in multilayer nanoporous graphene.

    Science.gov (United States)

    Shahbabaei, Majid; Kim, Daejoong

    2017-08-09

    In this study, molecular dynamics (MD) simulations are used to examine the water transport properties through asymmetric hourglass-shaped pores in multilayer nanoporous graphene with a constant interlayer separation of 6 Å. The properties of the tested asymmetric hourglass-shaped pores [with the models having long cone (l 1 , -P) and short cone (l 2 , +P) entrances] are compared to a symmetric pore model. The study findings indicate that the water occupancy increases across the asymmetric pore (l 1 , -P) compared to (l 2 , +P), because of the length effect. The asymmetric pore, (l 1 , -P), yields higher flux compared to (l 2 , +P) and even the symmetric model, which can be attributed to the increase in the hydrogen bonds. In addition, the single-file water molecules across the narrowest pore diameter inside the (l 2 , +P) pore exhibit higher viscosity compared to those in the (l 1 , -P) pore because of the increase in the water layering effect. Moreover, it is found that the permeability inside the multilayer hourglass-shaped pore depends on the length of the flow path of the water molecules before approaching the layer with the smallest pore diameter. The probability of dipole orientation exhibits wider distribution inside the (l 1 , -P) system compared to (l 2 , +P), implying an enhanced formation of hydrogen bonding of water molecules. This results in the fast flow of water molecules. The MD trajectory shows that the dipole orientation across the single-layer graphene has frequently flipped compared to the dipole orientation across the pores in multilayer graphene, which is maintained during the whole simulation time (although the dipole orientation has flipped for a few picoseconds at the beginning of the simulation). This can be attributed to the energy barrier induced by the individual layer. The diffusion coefficient of water molecules inside the (l 2 , +P) system increases with pressure difference, however, it decreases inside the (l 1 , -P) system because

  9. Porous media fluid transport and pore structure

    CERN Document Server

    Dullien, F A L

    1992-01-01

    This book examines the relationship between transport properties and pore structure of porous material. Models of pore structure are presented with a discussion of how such models can be used to predict the transport properties of porous media. Portions of the book are devoted to interpretations of experimental results in this area and directions for future research. Practical applications are given where applicable, and are expected to be useful for a large number of different fields, including reservoir engineering, geology, hydrogeology, soil science, chemical process engineering, biomedica

  10. Nuclear pore complex tethers to the cytoskeleton.

    Science.gov (United States)

    Goldberg, Martin W

    2017-08-01

    The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear pore complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear pore complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed. Copyright © 2017. Published by Elsevier Ltd.

  11. Pore water colloid properties in argillaceous sedimentary rocks

    Energy Technology Data Exchange (ETDEWEB)

    Degueldre, Claude, E-mail: c.degueldre@lancaster.ac.uk [Engineering Department, University of Lancaster, LA1 4YW Lancaster (United Kingdom); ChiAM & Institute of Environment, University of Geneva, 1211 Genève 4, Swizerland (Switzerland); Earlier, NES, Paul Scherrer Institute, 5232 Villigen (Switzerland); Cloet, Veerle [NAGRA, Hardstrasse 73, 5430 Wettingen (Switzerland)

    2016-11-01

    The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

  12. Movement of fossil pore fluids in granite basement, Illinois

    International Nuclear Information System (INIS)

    Couture, R.A.; Seitz, M.G.

    1986-01-01

    The compositions of pore fluids in granite cores from the Precambrian basement in northern Illinois were determined. The estimated chloride concentration in the aqueous phase increases from near zero at the upper contact with sandstone to 2.7 M at 624 m below the contact. Traces of aliphatic oil are present in the overlying sandstone and the upper 516 m of granite, and oil occupies most of the pore space in one sample of unaltered granite 176 m below the contact. The oil has a Δ 13 C of -25%, about the same as average petroleum. The high concentrations of salt more than 500 m below the contact imply that little or no fresh water has reached these levels of the granite by flow. Lower concentrations near the contact are consistent with replacement of brine in the sandstone by fresh water at least 11 m.y. ago and subsequent upward diffusion of salt from the granite. Geologic data suggest that the time of replacement was about 130 Ma. The purpose of the investigation is to study the record of movement of intergranular fluids within a granite pluton. The composition and movement of ground waters can determine the extent that hazardous or radioactive wastes disposed in igneous rock will remain isolated

  13. Tailoring particle translocation via dielectrophoresis in pore channels

    Science.gov (United States)

    Tanaka, Shoji; Tsutsui, Makusu; Theodore, Hu; Yuhui, He; Arima, Akihide; Tsuji, Tetsuro; Doi, Kentaro; Kawano, Satoyuki; Taniguchi, Masateru; Kawai, Tomoji

    2016-01-01

    Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore. We created a trap field by applying AC voltage between electrodes embedded in a low-aspect-ratio micropore. We demonstrated a traffic control of particles to go through center or near side surface via the voltage frequency. We also found enhanced capture efficiency along with faster escaping speed of particles by virtue of the AC-mediated electroosmosis. This method is compatible with nanopore sensing and would be widely applied for reducing off-axis effects to achieve single-molecule identification. PMID:27527126

  14. Dynamics of polynucleotide transport through nanometre-scale pores

    CERN Document Server

    Meller, A

    2003-01-01

    The transport of biopolymers through large membrane channels is a ubiquitous process in biology. It is central to processes such as gene transfer by transduction and RNA transport through nuclear pore complexes. The transport of polymers through nanoscopic channels is also of interest to physicists and chemists studying the effects of steric, hydrodynamic, and electrostatic interactions between polymers and confining walls. Single-channel ion current measurements have been recently used to study the transport of biopolymers, and in particular single-stranded DNA and RNA molecules, through nanometre-size channels. Under the influence of an electric field, the negatively charged polynucleotides can be captured and drawn through the channel in a process termed 'translocation'. During translocation, the ion current flowing through the channel is mostly blocked, indicating the presence of the polymer inside the channel. The current blockades were found to be sensitive to the properties of the biopolymers such as t...

  15. Capillary Condensation in Pores with Rough Walls:

    Czech Academy of Sciences Publication Activity Database

    Bryk, P.; Rżysko, W.; Malijevský, Alexandr; Sokołowski, S.

    2007-01-01

    Roč. 313, č. 1 (2007), s. 41-52 ISSN 0021-9797 Grant - others:TOK(XE) 509249 Institutional research plan: CEZ:AV0Z40720504 Source of funding: R - rámcový projekt EK Keywords : adsorption * pore * capillary condensation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.309, year: 2007

  16. Mimicking the nuclear pore complex using nanopores

    NARCIS (Netherlands)

    Ananth, A.N.

    2018-01-01

    Nuclear pore complexes acts as a gatekeeper for molecular transport between the nucleus and the cytoplasm in eukaryotic cells. The central NPC channel is filled with intrinsically disordered FG domains (phenylalanine (F), glycine (G)) that are responsible for the fascinating selectivity of NPCs, for

  17. Induction of nano pore in Agrobacterial hemoglobin

    Directory of Open Access Journals (Sweden)

    Mojtaba Tousheh

    2014-01-01

    Full Text Available Introduction: A variety of oxygen-transport and -binding proteins exist in organisms including bacteria, protozoans, and fungi all have hemoglobin-like proteins. In addition to dealing with transport and sensing of oxygen, they may also deal with NO2, CO2, sulfide compounds, and even O2 scavenging in environments. Also they detoxified chlorinated materials like P450 enzymes and peroxidases and use as a detector of nitrate and hydrogen peroxide. Pore-forming bacterial globins are interested for filtration. Materials and methods: Although there are data for bacterial toxin as a filter, here we used Agrobacterial hem to induce nano pore in the heme structure using point mutation. Results: Investigations showed that three amino acids leucine 76, alanine 83 and histidine 80 are important for pore formation in Agrobacterium hemoglobin. A point mutation on leucine 76 to glycine, histidine 80 to asparagine and alanine 83 to lysine step by step led to create the nano pore 0.7- 0.8 nm in the globin. Discussion and conclusion: These mutations in bacterial hemoglobin increase the stability when mutation is with it’s at pH7. This mutation decreases the aliphatic index however increase the stability index.

  18. Field sampling of soil pore water to evaluate trace element mobility and associated environmental risk

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Jimenez, Eduardo, E-mail: eduardo.moreno@uam.es [Departamento de Quimica Agricola, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Beesley, Luke [James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Lepp, Nicholas W. [35, Victoria Road, Formby, Liverpool L37 7DH (United Kingdom); Dickinson, Nicholas M. [Department of Ecology, Lincoln University, Lincoln 7647, PO Box 84 (New Zealand); Hartley, William [School of Computing, Science and Engineering, University of Salford, Cockcroft Building, Salford, M5 4WT (United Kingdom); Clemente, Rafael [Dep. of Soil and Water Conservation and Organic Waste Management, CEBAS-CSIC, Campus Universitario de Espinardo, PO Box 164, 30100 Espinardo, Murcia (Spain)

    2011-10-15

    Monitoring soil pollution is a key aspect in sustainable management of contaminated land but there is often debate over what should be monitored to assess ecological risk. Soil pore water, containing the most labile pollutant fraction in soils, can be easily collected in situ offering a routine way to monitor this risk. We present a compilation of data on concentration of trace elements (As, Cd, Cu, Pb, and Zn) in soil pore water collected in field conditions from a range of polluted and non-polluted soils in Spain and the UK during single and repeated monitoring, and propose a simple eco-toxicity test using this media. Sufficient pore water could be extracted for analysis both under semi-arid and temperate conditions, and eco-toxicity comparisons could be effectively made between polluted and non-polluted soils. We propose that in-situ pore water extraction could enhance the realism of risk assessment at some contaminated sites. - Highlights: > In situ pore water sampling successfully evaluates trace elements mobility in soils. > Field sampling proved robust for different soils, sites and climatic regimes. > Measurements may be directly related to ecotoxicological assays. > Both short and long-term monitoring of polluted lands may be achieved. > This method complements other widely used assays for environmental risk assessment. - In situ pore water sampling from a wide variety of soils proves to be a beneficial application to monitor the stability of pollutants in soils and subsequent risk through mobility.

  19. Signature and Pathophysiology of Non-canonical Pores in Voltage-Dependent Cation Channels.

    Science.gov (United States)

    Held, Katharina; Voets, Thomas; Vriens, Joris

    2016-01-01

    Opening and closing of voltage-gated cation channels allows the regulated flow of cations such as Na(+), K(+), and Ca(2+) across cell membranes, which steers essential physiological processes including shaping of action potentials and triggering Ca(2+)-dependent processes. Classical textbooks describe the voltage-gated cation channels as membrane proteins with a single, central aqueous pore. In recent years, however, evidence has accumulated for the existence of additional ion permeation pathways in this group of cation channels, distinct from the central pore, which here we collectively name non-canonical pores. Whereas the first non-canonical pores were unveiled only after making specific point mutations in the voltage-sensor region of voltage-gated Na(+) and K(+) channels, recent evidence indicates that they may also be functional in non-mutated channels. Moreover, several channelopathies have been linked to mutations that cause the appearance of a non-canonical ion permeation pathway as a new pathological mechanism. This review provides an integrated overview of the biophysical properties of non-canonical pores described in voltage-dependent cation channels (KV, NaV, Cav, Hv1, and TRPM3) and of the (patho)physiological impact of opening of such pores.

  20. Pore structure and function of synthetic nanopores with fixed charges: tip shape and rectification properties

    Energy Technology Data Exchange (ETDEWEB)

    RamIrez, Patricio [Departament de Fisica Aplicada, Universitat Politecnica de Valencia, E-46022 Valencia (Spain); Apel, Pavel Yu [Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, Joliot-Curie street 6, 141980 Dubna (Russian Federation); Cervera, Javier; Mafe, Salvador [Departament de Fisica de la Terra i Termodinamica, Universitat de Valencia, E-46100 Burjassot (Spain)], E-mail: patraho@fis.upv.es

    2008-08-06

    We present a complete theoretical study of the relationship between the structure (tip shape and dimensions) and function (selectivity and rectification) of asymmetric nanopores on the basis of previous experimental studies. The theoretical model uses a continuum approach based on the Nernst-Planck equations. According to our results, the nanopore transport properties, such as current-voltage (I-V) characteristics, conductance, rectification ratio, and selectivity, are dictated mainly by the shape of the pore tip (we have distinguished bullet-like, conical, trumpet-like, and hybrid shapes) and the concentration of pore surface charges. As a consequence, the nanopore performance in practical applications will depend not only on the base and tip openings but also on the pore shape. In particular, we show that the pore opening dimensions estimated from the pore conductance can be very different, depending on the pore shape assumed. The results obtained can also be of practical relevance for the design of nanopores, nanopipettes, and nanoelectrodes, where the electrical interactions between the charges attached to the nanostructure and the mobile charges confined in the reduced volume of the inside solution dictate the device performance in practical applications. Because single tracks are the elementary building blocks for nanoporous membranes, the understanding and control of their individual properties should also be crucial in protein separation, water desalination, and bio-molecule detection using arrays of identical nanopores.

  1. Pore structure and function of synthetic nanopores with fixed charges: tip shape and rectification properties

    International Nuclear Information System (INIS)

    RamIrez, Patricio; Apel, Pavel Yu; Cervera, Javier; Mafe, Salvador

    2008-01-01

    We present a complete theoretical study of the relationship between the structure (tip shape and dimensions) and function (selectivity and rectification) of asymmetric nanopores on the basis of previous experimental studies. The theoretical model uses a continuum approach based on the Nernst-Planck equations. According to our results, the nanopore transport properties, such as current-voltage (I-V) characteristics, conductance, rectification ratio, and selectivity, are dictated mainly by the shape of the pore tip (we have distinguished bullet-like, conical, trumpet-like, and hybrid shapes) and the concentration of pore surface charges. As a consequence, the nanopore performance in practical applications will depend not only on the base and tip openings but also on the pore shape. In particular, we show that the pore opening dimensions estimated from the pore conductance can be very different, depending on the pore shape assumed. The results obtained can also be of practical relevance for the design of nanopores, nanopipettes, and nanoelectrodes, where the electrical interactions between the charges attached to the nanostructure and the mobile charges confined in the reduced volume of the inside solution dictate the device performance in practical applications. Because single tracks are the elementary building blocks for nanoporous membranes, the understanding and control of their individual properties should also be crucial in protein separation, water desalination, and bio-molecule detection using arrays of identical nanopores

  2. Pore structure and function of synthetic nanopores with fixed charges: tip shape and rectification properties.

    Science.gov (United States)

    Ramírez, Patricio; Apel, Pavel Yu; Cervera, Javier; Mafé, Salvador

    2008-08-06

    We present a complete theoretical study of the relationship between the structure (tip shape and dimensions) and function (selectivity and rectification) of asymmetric nanopores on the basis of previous experimental studies. The theoretical model uses a continuum approach based on the Nernst-Planck equations. According to our results, the nanopore transport properties, such as current-voltage (I-V) characteristics, conductance, rectification ratio, and selectivity, are dictated mainly by the shape of the pore tip (we have distinguished bullet-like, conical, trumpet-like, and hybrid shapes) and the concentration of pore surface charges. As a consequence, the nanopore performance in practical applications will depend not only on the base and tip openings but also on the pore shape. In particular, we show that the pore opening dimensions estimated from the pore conductance can be very different, depending on the pore shape assumed. The results obtained can also be of practical relevance for the design of nanopores, nanopipettes, and nanoelectrodes, where the electrical interactions between the charges attached to the nanostructure and the mobile charges confined in the reduced volume of the inside solution dictate the device performance in practical applications. Because single tracks are the elementary building blocks for nanoporous membranes, the understanding and control of their individual properties should also be crucial in protein separation, water desalination, and bio-molecule detection using arrays of identical nanopores.

  3. Individual pore and interconnection size analysis of macroporous ceramic scaffolds using high-resolution X-ray tomography

    Energy Technology Data Exchange (ETDEWEB)

    Jerban, Saeed, E-mail: saeed.jerban@usherbrooke.ca; Elkoun, Saïd, E-mail: Said.Elkoun@usherbrooke.ca

    2016-08-15

    The pore interconnection size of β-tricalcium phosphate scaffolds plays an essential role in the bone repair process. Although, the μCT technique is widely used in the biomaterial community, it is rarely used to measure the interconnection size because of the lack of algorithms. In addition, discrete nature of the μCT introduces large systematic errors due to the convex geometry of interconnections. We proposed, verified and validated a novel pore-level algorithm to accurately characterize the individual pores and interconnections. Specifically, pores and interconnections were isolated, labeled, and individually analyzed with high accuracy. The technique was verified thoroughly by visually inspecting and verifying over 3474 properties of randomly selected pores. This extensive verification process has passed a one-percent accuracy criterion. Scanning errors inherent in the discretization, which lead to both dummy and significantly overestimated interconnections, have been examined using computer-based simulations and additional high-resolution scanning. Then accurate correction charts were developed and used to reduce the scanning errors. Only after the corrections, both the μCT and SEM-based results converged, and the novel algorithm was validated. Material scientists with access to all geometrical properties of individual pores and interconnections, using the novel algorithm, will have a more-detailed and accurate description of the substitute architecture and a potentially deeper understanding of the link between the geometric and biological interaction. - Highlights: •An algorithm is developed to analyze individually all pores and interconnections. •After pore isolating, the discretization errors in interconnections were corrected. •Dummy interconnections and overestimated sizes were due to thin material walls. •The isolating algorithm was verified through visual inspection (99% accurate). •After correcting for the systematic errors, algorithm was

  4. Age-Related Hearing Impairment (ARHI) associated with GJB2 single mutation IVS1+1G>A in the Yakut population isolate in Eastern Siberia.

    Science.gov (United States)

    Barashkov, Nikolay A; Teryutin, Fedor M; Pshennikova, Vera G; Solovyev, Aisen V; Klarov, Leonid A; Solovyeva, Natalya A; Kozhevnikov, Andrei A; Vasilyeva, Lena M; Fedotova, Elvira E; Pak, Maria V; Lekhanova, Sargylana N; Zakharova, Elena V; Savvinova, Kyunney E; Gotovtsev, Nyurgun N; Rafailo, Adyum M; Luginov, Nikolay V; Alexeev, Anatoliy N; Posukh, Olga L; Dzhemileva, Lilya U; Khusnutdinova, Elza K; Fedorova, Sardana A

    2014-01-01

    Age-Related Hearing Impairment (ARHI) is one of the frequent sensory disorders registered in 50% of individuals over 80 years. ARHI is a multifactorial disorder due to environmental and poor-known genetic components. In this study, we present the data on age-related hearing impairment of 48 heterozygous carriers of mutation IVS1+1G>A (GJB2 gene) and 97 subjects with GJB2 genotype wt/wt in the Republic of Sakha/Yakutia (Eastern Siberia, Russia). This subarctic territory was found as the region with the most extensive accumulation of mutation IVS1+1G>A in the world as a result of founder effect in the unique Yakut population isolate. The GJB2 gene resequencing and detailed audiological analysis in the frequency range 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 kHz were performed in all examined subjects that allowed to investigate genotype-phenotype correlations between the presence of single mutation IVS1+1G>A and hearing of subjects from examined groups. We revealed the linear correlation between increase of average hearing thresholds at speech frequencies (PTA0.5,1.0,2.0,4.0 kHz) and age of individuals with GJB2 genotype IVS1+1G>A/wt (rs = 0.499, p = 0.006860 for males and rs = 0.427, p = 0.000277 for females). Moreover, the average hearing thresholds on high frequency (8.0 kHz) in individuals with genotype IVS1+1G>A/wt (both sexes) were significantly worse than in individuals with genotype wt/wt (pA/wt was estimated to be ∼40 years (rs = 0.504, p = 0.003). These findings demonstrate that the single IVS1+1G>A mutation (GJB2) is associated with age-related hearing impairment (ARHI) of the IVS1+1G>A carriers in the Yakuts.

  5. Age-Related Hearing Impairment (ARHI associated with GJB2 single mutation IVS1+1G>A in the Yakut population isolate in Eastern Siberia.

    Directory of Open Access Journals (Sweden)

    Nikolay A Barashkov

    Full Text Available Age-Related Hearing Impairment (ARHI is one of the frequent sensory disorders registered in 50% of individuals over 80 years. ARHI is a multifactorial disorder due to environmental and poor-known genetic components. In this study, we present the data on age-related hearing impairment of 48 heterozygous carriers of mutation IVS1+1G>A (GJB2 gene and 97 subjects with GJB2 genotype wt/wt in the Republic of Sakha/Yakutia (Eastern Siberia, Russia. This subarctic territory was found as the region with the most extensive accumulation of mutation IVS1+1G>A in the world as a result of founder effect in the unique Yakut population isolate. The GJB2 gene resequencing and detailed audiological analysis in the frequency range 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 kHz were performed in all examined subjects that allowed to investigate genotype-phenotype correlations between the presence of single mutation IVS1+1G>A and hearing of subjects from examined groups. We revealed the linear correlation between increase of average hearing thresholds at speech frequencies (PTA0.5,1.0,2.0,4.0 kHz and age of individuals with GJB2 genotype IVS1+1G>A/wt (rs = 0.499, p = 0.006860 for males and rs = 0.427, p = 0.000277 for females. Moreover, the average hearing thresholds on high frequency (8.0 kHz in individuals with genotype IVS1+1G>A/wt (both sexes were significantly worse than in individuals with genotype wt/wt (pA/wt was estimated to be ∼40 years (rs = 0.504, p = 0.003. These findings demonstrate that the single IVS1+1G>A mutation (GJB2 is associated with age-related hearing impairment (ARHI of the IVS1+1G>A carriers in the Yakuts.

  6. Co-ingestion of carbohydrate and whey protein isolates enhance PGC-1α mRNA expression: a randomised, single blind, cross over study

    Directory of Open Access Journals (Sweden)

    Hill Karen M

    2013-02-01

    Full Text Available Abstract Background Whey protein isolates (WPI supplementation is known to improve resistance training adaptations. However, limited information is available on the effects of WPI plus carbohydrate (CHO supplementation on endurance training adaptations. Method Six endurance trained male cyclists and triathletes (age 29 ± 4 years, weight 74 ± 2 kg, VO2 max 63 ± 3 ml oxygen. kg-1. Min-1, height 183 ± 5 cm; mean ± SEM were randomly assigned to one of two dietary interventions in a single blind cross over design; CHO or CHO + WPI. Each dietary intervention was followed for 16 days which included the last 2 days having increased CHO content, representing a CHO loading phase. The dietary interventions were iso-caloric and carbohydrate content matched. On completion of the dietary intervention, participants performed an exercise bout, consisting of cycling for 60 min at 70% VO2 max, followed by time trial to exhaustion at 90% VO2 max and recovered in the laboratory for 6 hours. Blood samples and muscle biopsies were taken at various time points at rest and through the exercise trial and recovery. Results Compared to CHO, CHO + WPI increased plasma insulin during recovery at 180 mins (P Conclusion This study showed co-ingestion of CHO + WPI may have beneficial effects on recovery and adaptations to endurance exercise via, increased insulin response and up regulation of PGC-1α mRNA expression.

  7. Stimulation of Na+-alanine cotransport activates a voltage-dependent conductance in single proximal tubule cells isolated from frog kidney

    Science.gov (United States)

    Robson, L; Hunter, M

    1999-01-01

    The swelling induced by Na+-alanine cotransport in proximal tubule cells of the frog kidney is followed by regulatory volume decrease (RVD). This RVD is inhibited by gadolinium (Gd3+), an inhibitor of stretch-activated channels, but is independent of extracellular Ca2+. In this study, the whole cell patch clamp technique was utilized to examine the effect of Na+-alanine cotransport on two previously identified volume- and Gd3+-sensitive conductances. One conductance is voltage dependent and anion selective (GVD) whilst the other is voltage independent and cation selective (GVI). Addition of 5 mM L-alanine to the bathing solution increased the whole cell conductance and gave a positive (depolarizing) shift in the reversal potential (Vrev, equivalent to the membrane potential in current-clamped cells) consistent with activation of Na+-alanine cotransport. Vrev shifted from -36 ± 4·9 to +12·9 ± 4·2 mV (n= 15). In the presence of alanine, the total whole cell conductance had several components including the cotransporter conductance and GVD and GVI. These conductances were separated using Gd3+, which inhibits both GVD and GVI, and the time dependency of GVD. Of these two volume-sensitive conductances, L-alanine elicited a specific increase in GVD, whereas GVI was unaffected. The L-alanine-induced activation of GVD was significantly reduced when cells were incubated in a hypertonic bathing solution. In summary, in single proximal tubule cells isolated from frog kidney, on stimulation of Na+-alanine cotransport GVD is activated, while GVI is unaffected. Taken with other evidence, this suggests that GVD is activated by cell swelling, consequent upon alanine entry, and may play a role as an anion efflux pathway during alanine-induced volume regulation. PMID:10226159

  8. X-ray pore optic developments

    Science.gov (United States)

    Wallace, Kotska; Bavdaz, Marcos; Collon, Maximilien; Beijersbergen, Marco; Kraft, Stefan; Fairbend, Ray; Séguy, Julien; Blanquer, Pascal; Graue, Roland; Kampf, Dirk

    2017-11-01

    In support of future x-ray telescopes ESA is developing new optics for the x-ray regime. To date, mass and volume have made x-ray imaging technology prohibitive to planetary remote sensing imaging missions. And although highly successful, the mirror technology used on ESA's XMM-Newton is not sufficient for future, large, x-ray observatories, since physical limits on the mirror packing density mean that aperture size becomes prohibitive. To reduce telescope mass and volume the packing density of mirror shells must be reduced, whilst maintaining alignment and rigidity. Structures can also benefit from a modular optic arrangement. Pore optics are shown to meet these requirements. This paper will discuss two pore optic technologies under development, with examples of results from measurement campaigns on samples. One activity has centred on the use of coated, silicon wafers, patterned with ribs, that are integrated onto a mandrel whose form has been polished to the required shape. The wafers follow the shape precisely, forming pore sizes in the sub-mm region. Individual stacks of mirrors can be manufactured without risk to, or dependency on, each other and aligned in a structure from which they can also be removed without hazard. A breadboard is currently being built to demonstrate this technology. A second activity centres on glass pore optics. However an adaptation of micro channel plate technology to form square pores has resulted in a monolithic material that can be slumped into an optic form. Alignment and coating of two such plates produces an x-ray focusing optic. A breadboard 20cm aperture optic is currently being built.

  9. Type IIA photosensitivity and formation of pores in optical fibers under intense ultraviolet irradiation

    International Nuclear Information System (INIS)

    Kukushkin, S. A.; Shlyagin, M. G.; Swart, P. L.; Chtcherbakov, A. A.; Osipov, A. V.

    2007-01-01

    Formation of the type IIA Bragg gratings in germanosilicate optical fibers is studied. We report the observation of such a type of gratings in the standard single-mode fiber (Corning SMF-28) under different experimental conditions. A mechanism for the type IIA photosensitivity in optical fibers is proposed which is based on nucleation and evolution of pores from vacancy-type defects in fiber areas where a high level of mechanical stress is induced under intense ultraviolet (UV) light. Evolution of fiber core temperature under influence of a single 20 ns light pulse from a KrF excimer laser was measured and compared with theoretical calculations. It was shown that transient thermoinduced stress in the fiber core can achieve a level sufficient for effective nucleation of pores. A theory describing formation of pores in optical fibers has been developed and was used to estimate the pore nucleation rate, concentration, and other parameters of pore evolution for different levels of UV fluence and fiber core stress

  10. Capillary pressure across a pore throat in the presence of surfactants

    KAUST Repository

    Jang, Junbong

    2016-11-22

    Capillarity controls the distribution and transport of multiphase and immiscible fluids in soils and fractured rocks; therefore, capillarity affects the migration of nonaqueous contaminants and remediation strategies for both LNAPLs and DNAPLs, constrains gas and oil recovery, and regulates CO2 injection and geological storage. Surfactants alter interfacial tension and modify the invasion of pores by immiscible fluids. Experiments are conducted to explore the propagation of fluid interfaces along cylindrical capillary tubes and across pore constrictions in the presence of surfactants. Measured pressure signatures reflect the interaction between surface tension, contact angle, and the pore geometry. Various instabilities occur as the interface traverses the pore constriction, consequently, measured pressure signatures differ from theoretical trends predicted from geometry, lower capillary pressures are generated in advancing wetting fronts, and jumps are prone to under-sampling. Contact angle and instabilities are responsible for pronounced differences between pressure signatures recorded during advancing and receding tests. Pressure signatures gathered with surfactant solutions suggest changes in interfacial tension at the constriction; the transient surface tension is significantly lower than the value measured in quasi-static conditions. Interface stiffening is observed during receding fronts for solutions near the critical micelle concentration. Wetting liquids tend to form plugs at pore constrictions after the invasion of a nonwetting fluid; plugs split the nonwetting fluid into isolated globules and add resistance against fluid flow.

  11. Multiscale pore structure and its effect on gas transport in organic-rich shale

    Science.gov (United States)

    Wu, Tianhao; Li, Xiang; Zhao, Junliang; Zhang, Dongxiao

    2017-07-01

    A systematic investigation of multiscale pore structure in organic-rich shale by means of the combination of various imaging techniques is presented, including the state-of-the-art Helium-Ion-Microscope (HIM). The study achieves insight into the major features at each scale and suggests the affordable techniques for specific objectives from the aspects of resolution, dimension, and cost. The pores, which appear to be isolated, are connected by smaller pores resolved by higher-resolution imaging. This observation provides valuable information, from the microscopic perspective of pore structure, for understanding how gas accumulates and transports from where it is generated. A comprehensive workflow is proposed based on the characteristics acquired from the multiscale pore structure analysis to simulate the gas transport process. The simulations are completed with three levels: the microscopic mechanisms should be taken into consideration at level I; the spatial distribution features of organic matter, inorganic matter, and macropores constitute the major issue at level II; and the microfracture orientation and topological structure are dominant factors at level III. The results of apparent permeability from simulations agree well with the values acquired from experiments. By means of the workflow, the impact of various gas transport mechanisms at different scales can be investigated more individually and precisely than conventional experiments.

  12. Pore water colloid properties in argillaceous sedimentary rocks.

    Science.gov (United States)

    Degueldre, Claude; Cloet, Veerle

    2016-11-01

    The focus of this work is to evaluate the colloid nature, concentration and size distribution in the pore water of Opalinus Clay and other sedimentary host rocks identified for a potential radioactive waste repository in Switzerland. Because colloids could not be measured in representative undisturbed porewater of these host rocks, predictive modelling based on data from field and laboratory studies is applied. This approach allowed estimating the nature, concentration and size distributions of the colloids in the pore water of these host rocks. As a result of field campaigns, groundwater colloid concentrations are investigated on the basis of their size distribution quantified experimentally using single particle counting techniques. The colloid properties are estimated considering data gained from analogue hydrogeochemical systems ranging from mylonite features in crystalline fissures to sedimentary formations. The colloid concentrations were analysed as a function of the alkaline and alkaline earth element concentrations. Laboratory batch results on clay colloid generation from compacted pellets in quasi-stagnant water are also reported. Experiments with colloids in batch containers indicate that the size distribution of a colloidal suspension evolves toward a common particle size distribution independently of initial conditions. The final suspension size distribution was found to be a function of the attachment factor of the colloids. Finally, calculations were performed using a novel colloid distribution model based on colloid generation, aggregation and sedimentation rates to predict under in-situ conditions what makes colloid concentrations and size distributions batch- or fracture-size dependent. The data presented so far are compared with the field and laboratory data. The colloid occurrence, stability and mobility have been evaluated for the water of the considered potential host rocks. In the pore water of the considered sedimentary host rocks, the clay

  13. Flow rate through microfilters: Influence of the pore size distribution, hydrodynamic interactions, wall slip, and inertia

    DEFF Research Database (Denmark)

    Jensen, Kaare Hartvig; Valente, Andre X. C. N.; Stone, Howard A.

    2014-01-01

    We examine the fluid mechanics of viscous flow through filters consisting of perforated thin plates. We classify the effects that contribute to the hydraulic resistance of the filter. Classical analyses assume a single pore size and account only for filter thickness. We extend these results to ob...

  14. The presence of INA proteins on the surface of single cells of Pseudomonas syringae R10.79 isolated from rain

    Science.gov (United States)

    Šantl-Temkiv, Tina; Ling, Meilee; Holm, Stine; Finster, Kai; Boesen, Thomas

    2016-04-01

    One of the important open questions in atmospheric ice nucleation is the impact of bioaerosols on the ice content of mix phase clouds (DeMott and Prenni 2010). Biogenic ice nuclei have a unique capacity of facilitating ice formation at temperatures between -1 and -10 °C. The model biogenic ice nuclei are produced by a few species of plant-surface bacteria, such as Pseudomonas syringae, that are commonly transported through the atmosphere. These bacterial species have highly specialized proteins, the so-called ice nucleation active (INA) proteins, which are exposed at the outer membrane surface of the cell where they promote ice particle formation. The mechanisms behind the onset of INA protein synthesis in single bacterial cells are not well understood. We performed a laboratory study in order to (i) investigate the presence of INA proteins on single bacterial cells and (ii) understand the conditions that induce INA protein production. We previously isolated an INA-positive strain of Pseudomonas syringae from rain samples collected in Denmark. Bacterial cells initiated ice nucleation activity at temperatures ≤-2°C and the cell fragments at temperatures ≤-8°C (Šantl-Temkiv et al 2015). We determined the amino-acid sequence of the INA protein and used the sequence to produce custom-made antibodies (GenScript, Germany). These antibodies were used to specifically stain and visualize the INA protein on the surfaces of single cells, which can then be quantified by a technique called flow cytometry. The synthesis of INA proteins by individual cells was followed during a batch growth experiment. An unusually high proportion of cells that were adapting to the new conditions prior to growth produced INA proteins (~4.4% of all cells). A smaller fraction of actively growing cells was carrying INA proteins (~1.2 % of all cells). The cells that stopped growing due to unfavorable conditions had the lowest fraction of cells carrying INA proteins (~0.5 % of all cells). To

  15. The equivalent pore aspect ratio as a tool for pore type prediction in carbonate reservoirs

    OpenAIRE

    FOURNIER , François; Pellerin , Matthieu; Villeneuve , Quentin; Teillet , Thomas; Hong , Fei; Poli , Emmanuelle; Borgomano , Jean; Léonide , Philippe; Hairabian , Alex

    2018-01-01

    International audience; The equivalent pore aspect ratios (EPAR) provide a tool to detect pore types by combining P-and S-wave velocities, porosity, bulk density and mineralogical composition of carbonate rocks. The integration of laboratory measurements, well log data and petrographic analysis of 468 carbonate samples from various depositional and diagenetic settings (Lower Cretaceous pre-salt non-marine carbonates from offshore Brazil, Lower Cretaceous shallow-water platform carbonates from...

  16. Multiscale pore networks and their effect on deformation and transport property alteration associated with hydraulic fracturing

    Science.gov (United States)

    Daigle, Hugh; Hayman, Nicholas; Jiang, Han; Tian, Xiao; Jiang, Chunbi

    2017-04-01

    Multiple lines of evidence indicate that, during a hydraulic fracture stimulation, the permeability of the unfractured matrix far from the main, induced tensile fracture increases by one to two orders of magnitude. This permeability enhancement is associated with pervasive shear failure in a large region surrounding the main induced fracture. We have performed low-pressure gas sorption, mercury intrusion, and nuclear magnetic resonance measurements along with high-resolution scanning electron microscope imaging on several preserved and unpreserved shale samples from North American basins before and after inducing failure in confined compressive strength tests. We have observed that the pore structure in intact samples exhibits multiscale behavior, with sub-micron-scale pores in organic matter connected in isolated, micron-scale clusters which themselves are connected to each other through a network of microcracks. The organic-hosted pore networks are poorly connected due to a significant number of dead-end pores within the organic matter. Following shear failure, we often observe an increase in pore volume in the sub-micron range, which appears to be related to the formation of microcracks that propagate along grain boundaries and other planes of mechanical strength contrast. This is consistent with other experimental and field evidence. In some cases these microcracks cross or terminate in organic matter, intersecting the organic-hosted pores. The induced microcrack networks typically have low connectivity and do not appreciably increase the connectivity of the overall pore network. However, in other cases the shear deformation results in an overall pore volume decrease; samples which exhibit this behavior tend to have more clay minerals. Our interpretation of these phenomena is as follows. As organic matter is converted to hydrocarbons, organic-hosted pores develop, and the hydrocarbons contained in these pores are overpressured. The disconnected nature of these

  17. Enhancement of plasma generation in catalyst pores with different shapes

    Science.gov (United States)

    Zhang, Yu-Ru; Neyts, Erik C.; Bogaerts, Annemie

    2018-05-01

    Plasma generation inside catalyst pores is of utmost importance for plasma catalysis, as the existence of plasma species inside the pores affects the active surface area of the catalyst available to the plasma species for catalytic reactions. In this paper, the electric field enhancement, and thus the plasma production inside catalyst pores with different pore shapes is studied with a two-dimensional fluid model. The results indicate that the electric field will be significantly enhanced near tip-like structures. In a conical pore with small opening, the strongest electric field appears at the opening and bottom corners of the pore, giving rise to a prominent ionization rate throughout the pore. For a cylindrical pore, the electric field is only enhanced at the bottom corners of the pore, with lower absolute value, and thus the ionization rate inside the pore is only slightly enhanced. Finally, in a conical pore with large opening, the electric field is characterized by a maximum at the bottom of the pore, yielding a similar behavior for the ionization rate. These results demonstrate that the shape of the pore has a significantly influence on the electric field enhancement, and thus modifies the plasma properties.

  18. Pores and Void in Asclepiades’ Physical Theory

    Science.gov (United States)

    Leith, David

    2012-01-01

    This paper examines a fundamental, though relatively understudied, aspect of the physical theory of the physician Asclepiades of Bithynia, namely his doctrine of pores. My principal thesis is that this doctrine is dependent on a conception of void taken directly from Epicurean physics. The paper falls into two parts: the first half addresses the evidence for the presence of void in Asclepiades’ theory, and concludes that his conception of void was basically that of Epicurus; the second half focuses on the precise nature of Asclepiadean pores, and seeks to show that they represent void interstices between the primary particles of matter which are the constituents of the human body, and are thus exactly analogous to the void interstices between atoms within solid objects in Epicurus’ theory. PMID:22984299

  19. Active Pore Volume in Danish Peat Soils

    DEFF Research Database (Denmark)

    Forsmann, Ditte M.; Kjærgaard, Charlotte

    2012-01-01

    Phosphorus release within the soil matrix caused by the changed redox conditions due to re-establishment of a riparian wetland can be critical for the aquatic environment. However, phosphorous released in the soil will not always result in an immediate contribution to this loss to the aquatic...... environment. Lowland soils are primarily peat soils, and only a minor part of the total soil volume of peat soils is occupied by macropores (>30 µm). Since water primarily flows in these macropores, the majority of the soil matrix is bypassed (the immobile domain). Phosphorus released in the immobile domain...... is not actively transported out of the system, but is only transported via diffusion, which is a very slow process. Thus it is interesting to investigate the size of the active pore volume in peat soils. The hypothesis of this study is that the active pores volume of a peat soil can be expressed using bulk...

  20. Silicon pore optics for future x-ray telescopes

    Science.gov (United States)

    Wille, Eric; Bavdaz, Marcos; Wallace, Kotska; Shortt, Brian; Collon, Maximilien; Ackermann, Marcelo; Günther, Ramses; Olde Riekerink, Mark; Koelewijn, Arenda; Haneveld, Jeroen; van Baren, Coen; Erhard, Markus; Kampf, Dirk; Christensen, Finn; Krumrey, Michael; Freyberg, Michael; Burwitz, Vadim

    2017-11-01

    Lightweight X-ray Wolter optics with a high angular resolution will enable the next generation of X-ray telescopes in space. The candidate mission ATHENA (Advanced Telescope for High Energy Astrophysics) required a mirror assembly of 1 m2 effective area (at 1 keV) and an angular resolution of 10 arcsec or better. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is being developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor industry. We present the recent upgrades made to the manufacturing processes and equipment, ranging from the manufacture of single mirror plates towards complete focusing mirror modules mounted in flight configuration, and results from first vibration tests. The performance of the mirror modules is tested at X-ray facilities that were recently extended to measure optics at a focal distance up to 20 m.

  1. Efficacy of two hydrogen peroxide vapour aerial decontamination systems for enhanced disinfection of meticillin-resistant Staphylococcus aureus, Klebsiella pneumoniae and Clostridium difficile in single isolation rooms.

    Science.gov (United States)

    Ali, S; Muzslay, M; Bruce, M; Jeanes, A; Moore, G; Wilson, A P R

    2016-05-01

    Hydrogen peroxide vapour (HPV) disinfection systems are being used to reduce patients' exposure to hospital pathogens in the environment. HPV whole-room aerial disinfection systems may vary in terms of operating concentration and mode of delivery. To assess the efficacy of two HPV systems (HPS1 and HPS2) for whole-room aerial disinfection of single isolation rooms (SIRs). Ten SIRs were selected for manual terminal disinfection after patient discharge. Test coupons seeded with biological indicator (BI) organisms [∼10(6) colony-forming units (cfu) of meticillin-resistant Staphylococcus aureus (MRSA) or Klebsiella pneumoniae, or ∼10(5)cfu Clostridium difficile 027 spores] prepared in a soil challenge were placed at five locations per room. For each cycle, 22 high-frequency-touch surfaces in SIRs were sampled with contact plates (∼25cm(2)) before and after HPV decontamination, and BIs were assayed for the persistence of pathogens. Approximately 95% of 214 sites were contaminated with bacteria after manual terminal disinfection, with high numbers present on the SIR floor (238.0-352.5cfu), bed control panel (24.0-33.5cfu), and nurse call button (21.5-7.0cfu). Enhanced disinfection using HPV reduced surface contamination to low levels: HPS1 [0.25cfu, interquartile range (IQR) 0-1.13] and HPS2 (0.5cfu, IQR 0-2.0). Both systems demonstrated similar turnaround times (∼2-2.5h), and no differences were observed in the efficacy of the two systems against BIs (C. difficile ∼5.1log10 reduction; MRSA/K. pneumoniae ∼6.3log10 reduction). Despite different operating concentrations of hydrogen peroxide, MRSA persisted on 27% of coupons after HPV decontamination. Enhanced disinfection with HPV reduces surface contamination left by manual terminal cleaning, minimizing the risks of cross-contamination. The starting concentration and mode of delivery of hydrogen peroxide may not improve the efficacy of decontamination in practice, and therefore the choice of HPV system may

  2. Single nucleotide polymorphisms and genotypes of transient receptor potential ion channel and acetylcholine receptor genes from isolated B lymphocytes in myalgic encephalomyelitis/chronic fatigue syndrome patients.

    Science.gov (United States)

    Marshall-Gradisnik, Sonya; Johnston, Samantha; Chacko, Anu; Nguyen, Thao; Smith, Peter; Staines, Donald

    2016-12-01

    Objective The pathomechanism of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is unknown; however, a small subgroup of patients has shown muscarinic antibody positivity and reduced symptom presentation following anti-CD20 intervention. Given the important roles of calcium (Ca 2+ ) and acetylcholine (ACh) signalling in B cell activation and potential antibody development, we aimed to identify relevant single nucleotide polymorphisms (SNPs) and genotypes in isolated B cells from CFS/ME patients. Methods A total of 11 CFS/ME patients (aged 31.82 ± 5.50 years) and 11 non-fatigued controls (aged 33.91 ± 5.06 years) were included. Flow cytometric protocols were used to determine B cell purity, followed by SNP and genotype analysis for 21 mammalian TRP ion channel genes and nine mammalian ACh receptor genes. SNP association and genotyping analysis were performed using ANOVA and PLINK analysis software. Results Seventy-eight SNPs were identified in nicotinic and muscarinic acetylcholine receptor genes in the CFS/ME group, of which 35 were in mAChM3. The remaining SNPs were identified in nAChR delta (n = 12), nAChR alpha 9 (n = 5), TRPV2 (n = 7), TRPM3 (n = 4), TRPM4 (n = 1) mAChRM3 2 (n = 2), and mAChRM5 (n = 3) genes. Nine genotypes were identified from SNPs in TRPM3 (n = 1), TRPC6 (n = 1), mAChRM3 (n = 2), nAChR alpha 4 (n = 1), and nAChR beta 1 (n = 4) genes, and were located in introns and 3' untranslated regions. Odds ratios for these specific genotypes ranged between 7.11 and 26.67 for CFS/ME compared with the non-fatigued control group. Conclusion This preliminary investigation identified a number of SNPs and genotypes in genes encoding TRP ion channels and AChRs from B cells in patients with CFS/ME. These may be involved in B cell functional changes, and suggest a role for Ca 2+ dysregulation in AChR and TRP ion channel signalling in the pathomechanism of CFS/ME.

  3. Facial skin pores: a multiethnic study

    Directory of Open Access Journals (Sweden)

    Flament F

    2015-02-01

    Full Text Available Frederic Flament,1 Ghislain Francois,1 Huixia Qiu,2 Chengda Ye,2 Tomoo Hanaya,3 Dominique Batisse,3 Suzy Cointereau-Chardon,1 Mirela Donato Gianeti Seixas,4 Susi Elaine Dal Belo,4 Roland Bazin5 1Department of Applied Research and Development, L’Oreal Research and Innovation, Paris, France; 2Department of Applied Research and Development, L’Oreal Research and Innovation, Shanghai, People’s Republic of China; 3Department of Applied Research and Development, L’Oreal Research and Innovation, Tokyo, Japan; 4Department of Applied Research and Development, L’Oreal Research and Innovation, Rio de Janeiro, Brazil; 5RB Consult, Bievres, France Abstract: Skin pores (SP, as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc that generate many aesthetic concerns or complaints. Despite the prevalence of skin pores, related literature is scarce. With the aim of describing the prevalence of skin pores and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin pores (size, density, coverage on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 µm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm2 and determination of their respective sizes in mm2. Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1 were recorded in all studied subjects; 2 varied greatly with ethnicity; 3 plateaued with age in most cases; and 4 globally reflected self-assessment by subjects, in particular those who self-declare having “enlarged pores” like Brazilian women. Inversely, Chinese women were clearly

  4. Micro-computed tomography pore-scale study of flow in porous media: Effect of voxel resolution

    Science.gov (United States)

    Shah, S. M.; Gray, F.; Crawshaw, J. P.; Boek, E. S.

    2016-09-01

    A fundamental understanding of flow in porous media at the pore-scale is necessary to be able to upscale average displacement processes from core to reservoir scale. The study of fluid flow in porous media at the pore-scale consists of two key procedures: Imaging - reconstruction of three-dimensional (3D) pore space images; and modelling such as with single and two-phase flow simulations with Lattice-Boltzmann (LB) or Pore-Network (PN) Modelling. Here we analyse pore-scale results to predict petrophysical properties such as porosity, single-phase permeability and multi-phase properties at different length scales. The fundamental issue is to understand the image resolution dependency of transport properties, in order to up-scale the flow physics from pore to core scale. In this work, we use a high resolution micro-computed tomography (micro-CT) scanner to image and reconstruct three dimensional pore-scale images of five sandstones (Bentheimer, Berea, Clashach, Doddington and Stainton) and five complex carbonates (Ketton, Estaillades, Middle Eastern sample 3, Middle Eastern sample 5 and Indiana Limestone 1) at four different voxel resolutions (4.4 μm, 6.2 μm, 8.3 μm and 10.2 μm), scanning the same physical field of view. Implementing three phase segmentation (macro-pore phase, intermediate phase and grain phase) on pore-scale images helps to understand the importance of connected macro-porosity in the fluid flow for the samples studied. We then compute the petrophysical properties for all the samples using PN and LB simulations in order to study the influence of voxel resolution on petrophysical properties. We then introduce a numerical coarsening scheme which is used to coarsen a high voxel resolution image (4.4 μm) to lower resolutions (6.2 μm, 8.3 μm and 10.2 μm) and study the impact of coarsening data on macroscopic and multi-phase properties. Numerical coarsening of high resolution data is found to be superior to using a lower resolution scan because it

  5. Radial distribution of ions in pores with a surface charge

    NARCIS (Netherlands)

    Stegen, J.H.G. van der; Görtzen, J.; Kuipers, J.A.M.; Hogendoorn, J.A.; Versteeg, G.F.

    2001-01-01

    A sorption model applicable to calculate the radial equilibrium concentrations of ions in the pores of ion-selective membranes with a pore structure is developed. The model is called the radial uptake model. Because the model is applied to a Nafion sulfonic layer with very small pores and the radial

  6. Estimation of adsorption-induced pore pressure and confinement in a nanoscopic slit pore by a density functional theory

    Science.gov (United States)

    Grégoire, David; Malheiro, Carine; Miqueu, Christelle

    2018-03-01

    This study aims at characterising the adsorption-induced pore pressure and confinement in nanoscopic pores by molecular non-local density functional theory (DFT). Considering its important potential industrial applications, the adsorption of methane in graphitic slit pores has been selected as the test case. While retaining the accuracy of molecular simulations at pore scale, DFT has a very low computational cost that allows obtaining highly resolved pore pressure maps as a function of both pore width and thermodynamic conditions. The dependency of pore pressure on these parameters (pore width, pressure and temperature) is carefully analysed in order to highlight the effect of each parameter on the confined fluid properties that impact the solid matrix.

  7. Pore to core scale simulation of the mass transfer with mineral reaction in porous media

    International Nuclear Information System (INIS)

    Bekri, S.; Renard, S.; Delprat-Jannaud, F.

    2015-01-01

    Pore Network Model (PNM) is used to simulate mass transfer with mineral reaction in a single phase flow through porous medium which is here a sandstone sample from the reservoir formation of the Pakoslaw gas field. The void space of the porous medium is represented by an idealized geometry of pore-bodies joined by pore-throats. Parameters defining the pore-bodies and the pore-throats distribution are determined by an optimization process aiming to match the experimental Mercury Intrusion Capillary Pressure (MICP) curve and petrophysical properties of the rock such as intrinsic permeability and formation factor. The generated network is used first to simulate the multiphase flow by solving Kirchhoff's laws. The capillary pressure and relative permeability curves are derived. Then, reactive transport is addressed under asymptotic regime where the solute concentration undergoes an exponential evolution with time. The porosity/ permeability relationship and the three phenomenological coefficients of transport, namely the solute velocity, the dispersion and the mean reaction rate are determined as functions of Peclet and Peclet-Damkohler dimensionless numbers. Finally, the role of the dimensionless numbers on the reactive flow properties is highlighted. (authors)

  8. Energy conversion device with support member having pore channels

    Science.gov (United States)

    Routkevitch, Dmitri [Longmont, CO; Wind, Rikard A [Johnstown, CO

    2014-01-07

    Energy devices such as energy conversion devices and energy storage devices and methods for the manufacture of such devices. The devices include a support member having an array of pore channels having a small average pore channel diameter and having a pore channel length. Material layers that may include energy conversion materials and conductive materials are coaxially disposed within the pore channels to form material rods having a relatively small cross-section and a relatively long length. By varying the structure of the materials in the pore channels, various energy devices can be fabricated, such as photovoltaic (PV) devices, radiation detectors, capacitors, batteries and the like.

  9. Silicon pore optics developments and status

    DEFF Research Database (Denmark)

    Bavdaz, Marcos; Wille, Eric; Wallace, Kotska

    2012-01-01

    Silicon Pore Optics (SPO) is a lightweight high performance X-ray optics technology being developed in Europe, driven by applications in observatory class high energy astrophysics missions. An example of such application is the former ESA science mission candidate ATHENA (Advanced Telescope...... for High Energy Astrophysics), which uses the SPO technology for its two telescopes, in order to provide an effective area exceeding 1 m2 at 1 keV, and 0.5 m2 at 6 keV, featuring an angular resolution of 10" or better [1 to 24]. This paper reports on the development activities led by ESA, and the status...

  10. Fabrication of channeled scaffolds with ordered array of micro-pores through microsphere leaching and indirect Rapid Prototyping technique.

    Science.gov (United States)

    Tan, J Y; Chua, C K; Leong, K F

    2013-02-01

    Advanced scaffold fabrication techniques such as Rapid Prototyping (RP) are generally recognized to be advantageous over conventional fabrication methods in terms architectural control and reproducibility. Yet, most RP techniques tend to suffer from resolution limitations which result in scaffolds with uncontrollable, random-size pores and low porosity, albeit having interconnected channels which is characteristically present in most RP scaffolds. With the increasing number of studies demonstrating the profound influences of scaffold pore architecture on cell behavior and overall tissue growth, a scaffold fabrication method with sufficient architectural control becomes imperative. The present study demonstrates the use of RP fabrication techniques to create scaffolds having interconnected channels as well as controllable micro-size pores. Adopted from the concepts of porogen leaching and indirect RP techniques, the proposed fabrication method uses monodisperse microspheres to create an ordered, hexagonal closed packed (HCP) array of micro-pores that surrounds the existing channels of the RP scaffold. The pore structure of the scaffold is shaped using a single sacrificial construct which comprises the microspheres and a dissolvable RP mold that were sintered together. As such, the size of pores as well as the channel configuration of the scaffold can be tailored based on the design of the RP mold and the size of microspheres used. The fabrication method developed in this work can be a promising alternative way of preparing scaffolds with customized pore structures that may be required for specific studies concerning cell-scaffold interactions.

  11. Performance characterization of silicon pore optics

    Science.gov (United States)

    Collon, M. J.; Kraft, S.; Günther, R.; Maddox, E.; Beijersbergen, M.; Bavdaz, M.; Lumb, D.; Wallace, K.; Krumrey, M.; Cibik, L.; Freyberg, M.

    2006-06-01

    The characteristics of the latest generation of assembled silicon pore X-ray optics are discussed in this paper. These very light, stiff and modular high performance pore optics (HPO) have been developed [1] for the next generation of astronomical X-ray telescopes, which require large collecting areas whilst achieving angular resolutions better than 5 arcseconds. The suitability of 12 inch silicon wafers as high quality optical mirrors and the automated assembly process are discussed elsewhere in this conference. HPOs with several tens of ribbed silicon plates are assembled by bending the plates into an accurate cylindrical shape and directly bonding them on top of each other. The achievable figure accuracy is measured during assembly and in test campaigns at X-ray testing facilities like BESSY-II and PANTER. Pencil beam measurements allow gaining information on the quality achieved by the production process with high spatial resolution. In combination with full beam illumination a complete picture of the excellent performance of these optics can be derived. Experimental results are presented and discussed in detail. The results of such campaigns are used to further improve the production process in order to match the challenging XEUS requirements [2] for imaging resolution and mass.

  12. High Fidelity Computational Analysis of CO2 Trapping at Pore Scales

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vinod

    2013-07-13

    With an alarming rise in carbon dioxide (CO2) emission from anthropogenic sources, CO2 sequestration has become an attractive choice to mitigate the emission. Some popular storage media for CO{sub 2} are oil reservoirs, deep coal-bed, and deep oceanic-beds. These have been used for the long term CO{sub 2} storage. Due to special lowering viscosity and surface tension property of CO{sub 2}, it has been widely used for enhanced oil recovery. The sites for CO{sub 2} sequestration or enhanced oil recovery mostly consist of porous rocks. Lack of knowledge of molecular mobility under confinement and molecule-surface interactions between CO2 and natural porous media results in generally governed by unpredictable absorption kinetics and total absorption capacity for injected fluids, and therefore, constitutes barriers to the deployment of this technology. Therefore, it is important to understand the flow dynamics of CO{sub 2} through the porous microstructures at the finest scale (pore-scale) to accurately predict the storage potential and long-term dynamics of the sequestered CO{sub 2}. This report discusses about pore-network flow modeling approach using variational method and analyzes simulated results this method simulations at pore-scales for idealized network and using Berea Sandstone CT scanned images. Variational method provides a promising way to study the kinetic behavior and storage potential at the pore scale in the presence of other phases. The current study validates variational solutions for single and two-phase Newtonian and single phase non-Newtonian flow through angular pores for special geometries whose analytical and/or empirical solutions are known. The hydraulic conductance for single phase flow through a triangular duct was also validated against empirical results derived from lubricant theory.

  13. [A photographic scale for evaluating facial pores and analysis of factors associated with pore widening in Chengdu].

    Science.gov (United States)

    Wang, Qing; Zhou, Cheng-xia; Meng, Hui-min; Wang, Xi; Li, Li

    2010-09-01

    To develop a photographic scale for grading widening of pores, and to identify the factors associated with pore widening. People with widened pores were recruited, with photographs taken on their nasal tips, nasal alas and cheeks. A questionnaire survey was undertaken by dermatologists to assess the severity of pore widening. A Cumulative Logit Model was established to identify factors that were associated with pore widening. A total of 115 people participated in the study and 562 photographs were taken. The photographic scale was highly consistent with the clinical judgment. Another 1011 residents aged from 18 to 70 years old in Chengdu were surveyed. The logit model revealed that facial pore widening were associated with gender, age, oily skin, sun protection and anti-aging cosmetic. The photographic scale is reliable and easy to use. Gender, age and oily skin are risk factors, and sun protection and anti-aging cosmetic are protective factors with related to pore widening.

  14. Direct Pore Binding as a Mechanism for Isoflurane Inhibition of the Pentameric Ligand-gated Ion Channel ELIC.

    Science.gov (United States)

    Chen, Qiang; Kinde, Monica N; Arjunan, Palaniappa; Wells, Marta M; Cohen, Aina E; Xu, Yan; Tang, Pei

    2015-09-08

    Pentameric ligand-gated ion channels (pLGICs) are targets of general anesthetics, but molecular mechanisms underlying anesthetic action remain debatable. We found that ELIC, a pLGIC from Erwinia chrysanthemi, can be functionally inhibited by isoflurane and other anesthetics. Structures of ELIC co-crystallized with isoflurane in the absence or presence of an agonist revealed double isoflurane occupancies inside the pore near T237(6') and A244(13'). A pore-radius contraction near the extracellular entrance was observed upon isoflurane binding. Electrophysiology measurements with a single-point mutation at position 6' or 13' support the notion that binding at these sites renders isoflurane inhibition. Molecular dynamics simulations suggested that isoflurane binding was more stable in the resting than in a desensitized pore conformation. This study presents compelling evidence for a direct pore-binding mechanism of isoflurane inhibition, which has a general implication for inhibitory action of general anesthetics on pLGICs.

  15. Effect of Pore Pressure on Slip Failure of an Impermeable Fault: A Coupled Micro Hydro-Geomechanical Model

    Science.gov (United States)

    Yang, Z.; Juanes, R.

    2015-12-01

    The geomechanical processes associated with subsurface fluid injection/extraction is of central importance for many industrial operations related to energy and water resources. However, the mechanisms controlling the stability and slip motion of a preexisting geologic fault remain poorly understood and are critical for the assessment of seismic risk. In this work, we develop a coupled hydro-geomechanical model to investigate the effect of fluid injection induced pressure perturbation on the slip behavior of a sealing fault. The model couples single-phase flow in the pores and mechanics of the solid phase. Granular packs (see example in Fig. 1a) are numerically generated where the grains can be either bonded or not, depending on the degree of cementation. A pore network is extracted for each granular pack with pore body volumes and pore throat conductivities calculated rigorously based on geometry of the local pore space. The pore fluid pressure is solved via an explicit scheme, taking into account the effect of deformation of the solid matrix. The mechanics part of the model is solved using the discrete element method (DEM). We first test the validity of the model with regard to the classical one-dimensional consolidation problem where an analytical solution exists. We then demonstrate the ability of the coupled model to reproduce rock deformation behavior measured in triaxial laboratory tests under the influence of pore pressure. We proceed to study the fault stability in presence of a pressure discontinuity across the impermeable fault which is implemented as a plane with its intersected pore throats being deactivated and thus obstructing fluid flow (Fig. 1b, c). We focus on the onset of shear failure along preexisting faults. We discuss the fault stability criterion in light of the numerical results obtained from the DEM simulations coupled with pore fluid flow. The implication on how should faults be treated in a large-scale continuum model is also presented.

  16. Multiple Approaches to Characterizing Pore Structure in Natural Rock

    Science.gov (United States)

    Hu, Q.; Dultz, S.; Hamamoto, S.; Ewing, R. P.

    2012-12-01

    Microscopic characteristics of porous media - pore shape, pore-size distribution, and pore connectivity - control fluid flow and chemical transport, and are important in hydrogeological studies of rock formations in the context of energy, environmental, and water resources management. This presentation discusses various approaches to investigating pore structure of rock, with a particular focus on the Barnett Shale in north Texas used for natural gas production. Approaches include imbibition, tracer diffusion, porosimetry (MIP, vapor adsorption/desorption isotherms, NMR cyroporometry), and imaging (μ-tomography, Wood's metal impregnation, FIB/SEM). Results show that the Barnett Shale pores are predominantly in the nm size range, with a measured median pore-throat diameter of 6.5 nm. But small pore size is not the major contributor to low gas recovery; rather, the low gas diffusivity appears to be caused by low pore connectivity. Chemical diffusion in sparsely-connected pore spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the pore structure characteristics in the Barnett Shale and other natural rocks.

  17. Growing vertical ZnO nanorod arrays within graphite: efficient isolation of large size and high quality single-layer graphene.

    Science.gov (United States)

    Ding, Ling; E, Yifeng; Fan, Louzhen; Yang, Shihe

    2013-07-18

    We report a unique strategy for efficiently exfoliating large size and high quality single-layer graphene directly from graphite into DMF dispersions by growing ZnO nanorod arrays between the graphene layers in graphite.

  18. Six-Year Retrospective Review of Hospital Data on Antimicrobial Resistance Profile of Staphylococcus aureus Isolated from Skin Infections from a Single Institution in Greece

    Directory of Open Access Journals (Sweden)

    Christina Stefanaki

    2017-12-01

    Full Text Available Objective: To determine the prevalence of resistant strains of Staphylococcus aureus (S. aureus isolated from Skin and soft tissue infections (SSTI to various antibiotics. Material and Methods: All culture-positive results for S. aureus from swabs taken from patients presenting at one Greek hospital with a skin infection between the years 2010–2015 were examined retrospectively. Bacterial cultures, identification of S. aureus and antimicrobial susceptibility testing were performed using the disk diffusion method according to Clinical and Laboratory Standards Institute (CLSI guidelines and European Committee on Antimicrobial testing (EUCAST breakpoints. EUCAST breakpoints were applied if no CLSI were available. Results: Of 2069 S. aureus isolates identified, 1845 (88% were resistant to one or more antibiotics. The highest resistance was observed for benzylpenicillin (71.9%, followed by erythromycin (34.3%. Resistant strains to cefoxitin defined as MRSA (methicillin-resistant S. aureus represented 21% of total isolates. Interestingly, resistance to fusidic acid was 22.9% and to mupirocin as high as 12.7%. Low rates were observed for minocycline, rifampicin and trimethoprim/sulfamethoxazole (SXT. Resistance to antibiotics remained relatively stable throughout the six-year period, with the exception of cefoxitin, fusidic acid and SXT. A high percentage of MRSA strains were resistant to erythromycin (60%, fusidic acid (46%, clindamycin (38% and tetracycline (35.5%. Conclusions: Special attention is required in prescribing appropriate antibiotic therapeutic regimens, particularly for MRSA. These data on the susceptibility of S. aureus may be useful for guiding antibiotic treatment.

  19. Engineering a pH responsive pore forming protein.

    Science.gov (United States)

    Kisovec, Matic; Rezelj, Saša; Knap, Primož; Cajnko, Miša Mojca; Caserman, Simon; Flašker, Ajda; Žnidaršič, Nada; Repič, Matej; Mavri, Janez; Ruan, Yi; Scheuring, Simon; Podobnik, Marjetka; Anderluh, Gregor

    2017-02-08

    Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH.

  20. Engineering a pH responsive pore forming protein

    Science.gov (United States)

    Kisovec, Matic; Rezelj, Saša; Knap, Primož; Cajnko, Miša Mojca; Caserman, Simon; Flašker, Ajda; Žnidaršič, Nada; Repič, Matej; Mavri, Janez; Ruan, Yi; Scheuring, Simon; Podobnik, Marjetka; Anderluh, Gregor

    2017-02-01

    Listeriolysin O (LLO) is a cytolysin capable of forming pores in cholesterol-rich lipid membranes of host cells. It is conveniently suited for engineering a pH-governed responsiveness, due to a pH sensor identified in its structure that was shown before to affect its stability. Here we introduced a new level of control of its hemolytic activity by making a variant with hemolytic activity that was pH-dependent. Based on detailed structural analysis coupled with molecular dynamics and mutational analysis, we found that the bulky side chain of Tyr406 allosterically affects the pH sensor. Molecular dynamics simulation further suggested which other amino acid residues may also allosterically influence the pH-sensor. LLO was engineered to the point where it can, in a pH-regulated manner, perforate artificial and cellular membranes. The single mutant Tyr406Ala bound to membranes and oligomerized similarly to the wild-type LLO, however, the final membrane insertion step was pH-affected by the introduced mutation. We show that the mutant toxin can be activated at the surface of artificial membranes or living cells by a single wash with slightly acidic pH buffer. Y406A mutant has a high potential in development of novel nanobiotechnological applications such as controlled release of substances or as a sensor of environmental pH.

  1. Pore size matters for potassium channel conductance

    Science.gov (United States)

    Moldenhauer, Hans; Pincuntureo, Matías

    2016-01-01

    Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K+ channels discriminate K+ over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K+ channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings. In large-conductance K+ channels, the inner vestibule is wide, whereas in small-conductance channels it is narrow. Here we raise the idea that the physical dimensions of the hydrophobic internal vestibule limit ion transport in K+ channels, accounting for their diversity in unitary conductance. PMID:27619418

  2. Pore structure in blended cement pastes

    DEFF Research Database (Denmark)

    Canut, Mariana Moreira Cavalcanti

    Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained by...... on assumptions of degree of reaction and product densities gave for plain cement pastes results comparable to MIP data.......Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...

  3. Conservation agriculture effects on soil pore characteristics

    DEFF Research Database (Denmark)

    Munkholm, Lars Juhl; Abdollahi, Lotfollah

    ploughing to a depth of 20 cm (MP), harrowing to a depth of 8-10 cm (H) and direct drilling (D). Minimally disturbed core samples were taken at 4-8, 12-16 and 18-27 cm depths 11 years after experimental start. Water retention characteristics were measured for a range of matric potential ranging from -10......Conservation tillage in combination with crop rotation, residue management and cover crops are key components of conservation agriculture. A positive long-term effect of applying all components of conservation agriculture on soil structural quality is expected. However, there is a lack...... of quantitative knowledge to support this statement. This study examines the long-term effects of crop rotations, residue management and tillage on soil pore characteristics of two sandy loam soils in Denmark. Results are reported from a split plot field experiment rotation as main plot factor and tillage...

  4. Preferential flow from pore to landscape scales

    Science.gov (United States)

    Koestel, J. K.; Jarvis, N.; Larsbo, M.

    2017-12-01

    In this presentation, we give a brief personal overview of some recent progress in quantifying preferential flow in the vadose zone, based on our own work and those of other researchers. One key challenge is to bridge the gap between the scales at which preferential flow occurs (i.e. pore to Darcy scales) and the scales of interest for management (i.e. fields, catchments, regions). We present results of recent studies that exemplify the potential of 3-D non-invasive imaging techniques to visualize and quantify flow processes at the pore scale. These studies should lead to a better understanding of how the topology of macropore networks control key state variables like matric potential and thus the strength of preferential flow under variable initial and boundary conditions. Extrapolation of this process knowledge to larger scales will remain difficult, since measurement technologies to quantify macropore networks at these larger scales are lacking. Recent work suggests that the application of key concepts from percolation theory could be useful in this context. Investigation of the larger Darcy-scale heterogeneities that generate preferential flow patterns at the soil profile, hillslope and field scales has been facilitated by hydro-geophysical measurement techniques that produce highly spatially and temporally resolved data. At larger regional and global scales, improved methods of data-mining and analyses of large datasets (machine learning) may help to parameterize models as well as lead to new insights into the relationships between soil susceptibility to preferential flow and site attributes (climate, land uses, soil types).

  5. Phase transitions of fluids in heterogeneous pores

    Directory of Open Access Journals (Sweden)

    A. Malijevský

    2016-03-01

    Full Text Available We study phase behaviour of a model fluid confined between two unlike parallel walls in the presence of long range (dispersion forces. Predictions obtained from macroscopic (geometric and mesoscopic arguments are compared with numerical solutions of a non-local density functional theory. Two capillary models are considered. For a capillary comprising two (differently adsorbing walls we show that simple geometric arguments lead to the generalized Kelvin equation locating very accurately capillary condensation, provided both walls are only partially wet. If at least one of the walls is in complete wetting regime, the Kelvin equation should be modified by capturing the effect of thick wetting films by including Derjaguin's correction. Within the second model, we consider a capillary formed of two competing walls, so that one tends to be wet and the other dry. In this case, an interface localized-delocalized transition occurs at bulk two-phase coexistence and a temperature T*(L depending on the pore width L. A mean-field analysis shows that for walls exhibiting first-order wetting transition at a temperature T_{w}, T_{s} > T*(L > T_{w}, where the spinodal temperature Ts can be associated with the prewetting critical temperature, which also determines a critical pore width below which the interface localized-delocalized transition does not occur. If the walls exhibit critical wetting, the transition is shifted below Tw and for a model with the binding potential W(l=A(Tl-2+B(Tl-3+..., where l is the location of the liquid-gas interface, the transition can be characterized by a dimensionless parameter κ=B/(AL, so that the fluid configuration with delocalized interface is stable in the interval between κ=-2/3 and κ ~ -0.23.

  6. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Arthur, Emmanuel; de Jonge, Lis Wollesen

    2014-01-01

    Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm...... pore diameter of 200 and 170 Hm, respectively. Pore shape analysis indicated that CCC and MFC aggregates had an abundance of rounded and elongated pores, respectively, and those of MCC were in-between CCC and MFC. Aggregate pore structure development in the lysimeters was nearly similar irrespective...

  7. Characteristics of Pore Structure and Fractal Dimension of Isometamorphic Anthracite

    Directory of Open Access Journals (Sweden)

    Di Gao

    2017-11-01

    Full Text Available The geologic conditions of No. 3 coal seams are similar to Sihe and Zhaozhuang Collieries, however, the gas production is significantly different. To better understand the effect of pores, by means of experimental measurements and quantitative analysis, the pore properties of high-rank isometamorphic anthracite were thoroughly studied. Our study showed that the pore structures were predominantly adsorptive, accounting for more than 88% of the specific surface area. The coal pores showed typical three-stage fractal characteristics at boundary points of 1 nm and 9 nm (7 nm of coal samples from Zhaozhuang Colliery, and the fractal dimension with 1–9 nm (or 1–7 nm, as being significantly larger than those measured outside the given ranges. Pores in samples from Sihe Colliery were mainly open spherical or ellipsoidal pores in shape; conversely, those from Zhaozhuang Colliery were mainly Y-shaped, V-shaped, or ‘ink-bottle’ type.

  8. Preparation of micro-pored silicone elastomer through radiation crosslinking

    International Nuclear Information System (INIS)

    Gao Xiaoling; Gu Mei; Xie Xubing; Huang Wei

    2013-01-01

    The radiation crosslinking was adopted to prepare the micro-pored silicone elastomer, which was performed by vulcanization and foaming respectively. Radiation crosslinking is a new method to prepare micro-pored material with high performance by use of radiation technology. Silicon dioxide was used as filler, and silicone elastomer was vulcanized by electron beams, then the micro-pored material was made by heating method at a high temperature. The effects of absorbed dose and filler content on the performance and morphology were investigated. The structure and distribution of pores were observed by SEM. The results show that the micro-pored silicon elastomer can be prepared successfully by controlling the absorbed dose and filler content. It has a smooth surface similar to a rubber meanwhile the pores are round and unconnected to each other with the minimum size of 14 μm. And the good mechanical performance can be suitable for further uses. (authors)

  9. Coarse and fine root plants affect pore size distributions differently

    OpenAIRE

    Bodner, G.; Leitner, D.; Kaul, H.-P.

    2014-01-01

    Aims Small scale root-pore interactions require validation of their impact on effective hydraulic processes at the field scale. Our objective was to develop an interpretative framework linking root effects on macroscopic pore parameters with knowledge at the rhizosphere scale. Methods A field experiment with twelve species from different families was conducted. Parameters of Kosugi?s pore size distribution (PSD) model were determined inversely from tension infiltrometer data. Measured root tr...

  10. The effect of scaffold pore size in cartilage tissue engineering.

    Science.gov (United States)

    Nava, Michele M; Draghi, Lorenza; Giordano, Carmen; Pietrabissa, Riccardo

    2016-07-26

    The effect of scaffold pore size and interconnectivity is undoubtedly a crucial factor for most tissue engineering applications. The aim of this study was to examine the effect of pore size and porosity on cartilage construct development in different scaffolds seeded with articular chondrocytes. We fabricated poly-L-lactide-co-trimethylene carbonate scaffolds with different pore sizes, using a solvent-casting/particulate-leaching technique. We seeded primary bovine articular chondrocytes on these scaffolds, cultured the constructs for 2 weeks and examined cell proliferation, viability and cell-specific production of cartilaginous extracellular matrix proteins, including GAG and collagen. Cell density significantly increased up to 50% with scaffold pore size and porosity, likely facilitated by cell spreading on the internal surface of bigger pores, and by increased mass transport of gases and nutrients to cells, and catabolite removal from cells, allowed by lower diffusion barriers in scaffolds with a higher porosity. However, both the cell metabolic activity and the synthesis of cartilaginous matrix proteins significantly decreased by up to 40% with pore size. We propose that the association of smaller pore diameters, causing 3-dimensional cell aggregation, to a lower oxygenation caused by a lower porosity, could have been the condition that increased the cell-specific synthesis of cartilaginous matrix proteins in the scaffold with the smallest pores and the lowest porosity among those tested. In the initial steps of in vitro cartilage engineering, the combination of small scaffold pores and low porosity is an effective strategy with regard to the promotion of chondrogenesis.

  11. Real-Time Pore Pressure Detection: Indicators and Improved Methods

    Directory of Open Access Journals (Sweden)

    Jincai Zhang

    2017-01-01

    Full Text Available High uncertainties may exist in the predrill pore pressure prediction in new prospects and deepwater subsalt wells; therefore, real-time pore pressure detection is highly needed to reduce drilling risks. The methods for pore pressure detection (the resistivity, sonic, and corrected d-exponent methods are improved using the depth-dependent normal compaction equations to adapt to the requirements of the real-time monitoring. A new method is proposed to calculate pore pressure from the connection gas or elevated background gas, which can be used for real-time pore pressure detection. The pore pressure detection using the logging-while-drilling, measurement-while-drilling, and mud logging data is also implemented and evaluated. Abnormal pore pressure indicators from the well logs, mud logs, and wellbore instability events are identified and analyzed to interpret abnormal pore pressures for guiding real-time drilling decisions. The principles for identifying abnormal pressure indicators are proposed to improve real-time pore pressure monitoring.

  12. Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

    Full Text Available The fusion pore is an aqueous channel that is formed upon the fusion of the vesicle membrane with the plasma membrane. Once the pore is open, it may close again (transient fusion or widen completely (full fusion to permit vesicle cargo discharge. While repetitive transient fusion pore openings of the vesicle with the plasma membrane have been observed in the absence of stimulation, their frequency can be further increased using a cAMP-increasing agent that drives the opening of nonspecific cation channels. Our model hypothesis is that the openings and closings of the fusion pore are driven by changes in the local concentration of cations in the connected vesicle. The proposed mechanism of fusion pore dynamics is considered as follows: when the fusion pore is closed or is extremely narrow, the accumulation of cations in the vesicle (increased cation concentration likely leads to lipid demixing at the fusion pore. This process may affect local membrane anisotropy, which reduces the spontaneous curvature and thus leads to the opening of the fusion pore. Based on the theory of membrane elasticity, we used a continuum model to explain the rhythmic opening and closing of the fusion pore.

  13. X-ray microtomography application in pore space reservoir rock.

    Science.gov (United States)

    Oliveira, M F S; Lima, I; Borghi, L; Lopes, R T

    2012-07-01

    Characterization of porosity in carbonate rocks is important in the oil and gas industry since a major hydrocarbons field is formed by this lithology and they have a complex media porous. In this context, this research presents a study of the pore space in limestones rocks by x-ray microtomography. Total porosity, type of porosity and pore size distribution were evaluated from 3D high resolution images. Results show that carbonate rocks has a complex pore space system with different pores types at the same facies. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Role of the synaptobrevin C terminus in fusion pore formation

    DEFF Research Database (Denmark)

    Ngatchou, Annita N; Kisler, Kassandra; Fang, Qinghua

    2010-01-01

    Neurotransmitter release is mediated by the SNARE proteins synaptobrevin II (sybII, also known as VAMP2), syntaxin, and SNAP-25, generating a force transfer to the membranes and inducing fusion pore formation. However, the molecular mechanism by which this force leads to opening of a fusion pore...... stimulation, the SNARE complex pulls the C terminus of sybII deeper into the vesicle membrane. We propose that this movement disrupts the vesicular membrane continuity leading to fusion pore formation. In contrast to current models, the experiments suggest that fusion pore formation begins with molecular...

  15. Extraction of pores from microtomographic reconstructions of intact soil aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Albee, P. B.; Stockman, G. C.; Smucker, A. J. M.

    2000-02-29

    Segmentation of features is often a necessary step in the analysis of volumetric data. The authors have developed a simple technique for extracting voids from irregular volumetric data sets. In this work they look at extracting pores from soil aggregates. First, they identify a threshold that gives good separability of the object from the background. They then segment the object, and perform connected components analysis on the pores within the object. Using their technique pores that break the surface can be segmented along with pores completely contained in the initially segmented object.

  16. High-Quality Draft Single-Cell Genome Sequence Belonging to the Archaeal Candidate Division SA1, Isolated from Nereus Deep in the Red Sea

    KAUST Repository

    Ngugi, David

    2018-05-09

    Candidate division SA1 encompasses a phylogenetically coherent archaeal group ubiquitous in deep hypersaline anoxic brines around the globe. Recently, the genome sequences of two cultivated representatives from hypersaline soda lake sediments were published. Here, we present a single-cell genome sequence from Nereus Deep in the Red Sea that represents a putatively novel family within SA1.

  17. High-Quality Draft Single-Cell Genome Sequence Belonging to the Archaeal Candidate Division SA1, Isolated from Nereus Deep in the Red Sea

    KAUST Repository

    Ngugi, David; Stingl, Ulrich

    2018-01-01

    Candidate division SA1 encompasses a phylogenetically coherent archaeal group ubiquitous in deep hypersaline anoxic brines around the globe. Recently, the genome sequences of two cultivated representatives from hypersaline soda lake sediments were published. Here, we present a single-cell genome sequence from Nereus Deep in the Red Sea that represents a putatively novel family within SA1.

  18. Pore-size Distributions from Nitrogen Adsorption Revisited: Models Comparison with Controlled-pore Glasses

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Matějová, Lenka; Schneider, Petr

    2006-01-01

    Roč. 313, č. 2 (2006), s. 167-176 ISSN 0926-860X R&D Projects: GA ČR(CZ) GA104/04/2116; GA ČR GD203/03/H140; GA AV ČR IAA4072404 Institutional research plan: CEZ:AV0Z40720504 Keywords : pore size distribution * physical adsorption * standard nitrogen isotherm Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.630, year: 2006

  19. Mathematical modeling of deformation of a porous medium, considering its strengthening due to pore collapse

    Energy Technology Data Exchange (ETDEWEB)

    Sadovskii, V. M., E-mail: sadov@icm.krasn.ru; Sadovskaya, O. V., E-mail: o-sadov@icm.krasn.ru [Institute of Computational Modeling, SB RAS, Akademgorodok 50/44, 660036 Krasnoyarsk (Russian Federation)

    2015-10-28

    Based on the generalized rheological method, the mathematical model describing small deformations of a single-phase porous medium without regard to the effects of a fluid or gas in pores is constructed. The change in resistance of a material to the external mechanical impacts at the moment of pore collapse is taken into account by means of the von Mises–Schleicher strength condition. In order to consider irreversible deformations, alongside with the classical yield conditions by von Mises and Tresca– Saint-Venant, the special condition modeling the plastic loss of stability of a porous skeleton is used. The random nature of the pore size distribution is taken into account. It is shown that the proposed mathematical model satisfies the principles of thermodynamics of irreversible processes. Phenomenological parameters of the model are determined on the basis of the approximate calculation of the problem on quasi-static loading of a cubic periodicity cell with spherical voids. In the framework of the obtained model, the process of propagation of plane longitudinal waves of the compression in a homogenous porous medium, accompanied by the plastic deformation of a skeleton and the collapse of pores, is analyzed.

  20. A new model for pore formation by cholesterol-dependent cytolysins.

    Directory of Open Access Journals (Sweden)

    Cyril F Reboul

    2014-08-01

    Full Text Available Cholesterol Dependent Cytolysins (CDCs are important bacterial virulence factors that form large (200-300 Å membrane embedded pores in target cells. Currently, insights from X-ray crystallography, biophysical and single particle cryo-Electron Microscopy (cryo-EM experiments suggest that soluble monomers first interact with the membrane surface via a C-terminal Immunoglobulin-like domain (Ig; Domain 4. Membrane bound oligomers then assemble into a prepore oligomeric form, following which the prepore assembly collapses towards the membrane surface, with concomitant release and insertion of the membrane spanning subunits. During this rearrangement it is proposed that Domain 2, a region comprising three β-strands that links the pore forming region (Domains 1 and 3 and the Ig domain, must undergo a significant yet currently undetermined, conformational change. Here we address this problem through a systematic molecular modeling and structural bioinformatics approach. Our work shows that simple rigid body rotations may account for the observed collapse of the prepore towards the membrane surface. Support for this idea comes from analysis of published cryo-EM maps of the pneumolysin pore, available crystal structures and molecular dynamics simulations. The latter data in particular reveal that Domains 1, 2 and 4 are able to undergo significant rotational movements with respect to each other. Together, our data provide new and testable insights into the mechanism of pore formation by CDCs.

  1. The Impact of Microstructure Geometry on the Mass Transport in Artificial Pores: A Numerical Approach

    Directory of Open Access Journals (Sweden)

    Matthias Galinsky

    2014-01-01

    Full Text Available The microstructure of porous materials used in heterogeneous catalysis determines the mass transport inside networks, which may vary over many length scales. The theoretical prediction of mass transport phenomena in porous materials, however, is incomplete and is still not completely understood. Therefore, experimental data for every specific porous system is needed. One possible experimental technique for characterizing the mass transport in such pore networks is pulse experiments. The general evaluation of experimental outcomes of these techniques follows the solution of Fick’s second law where an integral and effective diffusion coefficient is recognized. However, a detailed local understanding of diffusion and sorption processes remains a challenge. As there is lack of proved models covering different length scales, existing classical concepts need to be evaluated with respect to their ability to reflect local geometries on the nanometer level. In this study, DSMC (Direct Simulation Monte Carlo models were used to investigate the impact of pore microstructures on the diffusion behaviour of gases. It can be understood as a virtual pulse experiment within a single pore or a combination of different pore geometries.

  2. Minimum requirements for predictive pore-network modeling of solute transport in micromodels

    Science.gov (United States)

    Mehmani, Yashar; Tchelepi, Hamdi A.

    2017-10-01

    Pore-scale models are now an integral part of analyzing fluid dynamics in porous materials (e.g., rocks, soils, fuel cells). Pore network models (PNM) are particularly attractive due to their computational efficiency. However, quantitative predictions with PNM have not always been successful. We focus on single-phase transport of a passive tracer under advection-dominated regimes and compare PNM with high-fidelity direct numerical simulations (DNS) for a range of micromodel heterogeneities. We identify the minimum requirements for predictive PNM of transport. They are: (a) flow-based network extraction, i.e., discretizing the pore space based on the underlying velocity field, (b) a Lagrangian (particle tracking) simulation framework, and (c) accurate transfer of particles from one pore throat to the next. We develop novel network extraction and particle tracking PNM methods that meet these requirements. Moreover, we show that certain established PNM practices in the literature can result in first-order errors in modeling advection-dominated transport. They include: all Eulerian PNMs, networks extracted based on geometric metrics only, and flux-based nodal transfer probabilities. Preliminary results for a 3D sphere pack are also presented. The simulation inputs for this work are made public to serve as a benchmark for the research community.

  3. Separating attoliter-sized compartments using fluid pore-spanning lipid bilayers.

    Science.gov (United States)

    Lazzara, Thomas D; Carnarius, Christian; Kocun, Marta; Janshoff, Andreas; Steinem, Claudia

    2011-09-27

    Anodic aluminum oxide (AAO) is a porous material having aligned cylindrical compartments with 55-60 nm diameter pores, and being several micrometers deep. A protocol was developed to generate pore-spanning fluid lipid bilayers separating the attoliter-sized compartments of the nanoporous material from the bulk solution, while preserving the optical transparency of the AAO. The AAO was selectively functionalized by silane chemistry to spread giant unilamellar vesicles (GUVs) resulting in large continuous membrane patches covering the pores. Formation of fluid single lipid bilayers through GUV rupture could be readily observed by fluorescence microscopy and further supported by conservation of membrane surface area, before and after GUV rupture. Fluorescence recovery after photobleaching gave low immobile fractions (5-15%) and lipid diffusion coefficients similar to those found for bilayers on silica. The entrapment of molecules within the porous underlying cylindrical compartments, as well as the exclusion of macromolecules from the nanopores, demonstrate the barrier function of the pore-spanning membranes and could be investigated in three-dimensions using confocal laser scanning fluorescence imaging. © 2011 American Chemical Society

  4. Numerical modeling of pore-scale phenomena during CO2 sequestration in oceanic sediments

    International Nuclear Information System (INIS)

    Kang, Qinjun; Tsimpanogiannis, Ioannis N.; Zhang, Dongxiao; Lichtner, Peter C.

    2005-01-01

    Direct disposal of liquid CO 2 on the ocean floor is one of the approaches considered for sequestering CO 2 in order to reduce its concentration in the atmosphere. At oceanic depths deeper than approximately 3000 m, liquid CO 2 density is higher than the density of seawater and CO 2 is expected to sink and form a pool at the ocean floor. In addition to chemical reactions between CO 2 and seawater to form hydrate, fluid displacement is also expected to occur within the ocean floor sediments. In this work, we consider two different numerical models for hydrate formation at the pore scale. The first model consists of the Lattice Boltzmann (LB) method applied to a single-phase supersaturated solution in a constructed porous medium. The second model is based on the Invasion Percolation (IP) in pore networks, applied to two-phase immiscible displacement of seawater by liquid CO 2 . The pore-scale results are upscaled to obtain constitutive relations for porosity, both transverse and for the entire domain, and for permeability. We examine deposition and displacement patterns, and changes in porosity and permeability due to hydrate formation, and how these properties depend on various parameters including a parametric study of the effect of hydrate formation kinetics. According to the simulations, the depth of CO 2 invasion in the sediments is controlled by changes in the pore-scale porosity close to the hydrate formation front. (author)

  5. Single amino acid changes in the 6K1-CI region can promote the alternative adaptation of Prunus- and Nicotiana-propagated Plum pox virus C isolates to either host.

    Science.gov (United States)

    Calvo, María; Malinowski, Tadeusz; García, Juan Antonio

    2014-02-01

    Plum pox virus (PPV) C is one of the less common PPV strains and specifically infects cherry trees in nature. Making use of two PPV-C isolates that display different pathogenicity features, i.e., SwCMp, which had been adapted to Nicotiana species, and BY101, which had been isolated from cherry rootstock L2 (Prunus lannesiana) and propagated only in cherry species, we have generated two infective full-length cDNA clones in order to determine which viral factors are involved in the adaptation to each host. According to our results, the C-P3(PIPO)/6K1/N-CI (cylindrical inclusion) region contains overlapping but not coincident viral determinants involved in symptoms development, local viral amplification, and systemic movement capacity. Amino acid changes in this region promoting the adaptation to N. benthamiana or P. avium have trade-off effects in the alternative host. In both cases, adaptation can be achieved through single amino acid changes in the NIapro protease recognition motif between 6K1 and CI or in nearby sequences. Thus, we hypothesize that the potyvirus polyprotein processing could depend on specific host factors and the adaptation of PPV-C isolates to particular hosts relies on a fine regulation of the proteolytic cleavage of the 6K1-CI junction.

  6. Impact of patient-prosthesis mismatch following aortic valve replacement on short-term survival: a retrospective single center analysis of 632 consecutive patients with isolated stented biological aortic valve replacement.

    Science.gov (United States)

    Hoffmann, Grischa; Ogbamicael, Selam Abraham; Jochens, Arne; Frank, Derk; Lutter, Georg; Cremer, Jochen; Petzina, Rainer

    2014-09-01

    The impact of patient-prosthesis mismatch (PPM) after aortic valve replacement (AVR) on short-term and long-term mortality remains controversial. The objective of this study was to evaluate the incidence and severity of PPM and its impact on short-term survival in a large cohort of patients treated with isolated stented biological AVR in a single institution. We analyzed retrospectively data of 632 consecutive patients with aortic stenosis undergoing isolated stented biological AVR between January 2007 and February 2012 at our institution. PPM was defined as an indexed effective orifice area ≤ 0.85 cm(2)/m(2). Statistical analyses were performed to identify influencing variables on valve size implanted. Of the 632 patients investigated, 46% were females and mean age was 71.9 ± 10.4 years. PPM was observed in 93.8% (593 of 632 patients). In 71% of the patients, moderate (0.65-0.85 cm(2)/m(2)) PPM was present and in 22.8% severe (body mass index, and body surface area as simultaneous predictors of the valve size implanted (R(2)= 0.39). PPM had no discernable impact on short-term survival, although it was present in 93.8% of our patients following isolated stented biological AVR. Georg Thieme Verlag KG Stuttgart · New York.

  7. Propagation of a plasma streamer in catalyst pores

    Science.gov (United States)

    Zhang, Quan-Zhi; Bogaerts, Annemie

    2018-03-01

    Although plasma catalysis is gaining increasing interest for various environmental applications, the underlying mechanisms are still far from understood. For instance, it is not yet clear whether and how plasma streamers can propagate in catalyst pores, and what is the minimum pore size to make this happen. As this is crucial information to ensure good plasma-catalyst interaction, we study here the mechanism of plasma streamer propagation in a catalyst pore, by means of a two-dimensional particle-in-cell/Monte Carlo collision model, for various pore diameters in the nm-range to μm-range. The so-called Debye length is an important criterion for plasma penetration into catalyst pores, i.e. a plasma streamer can penetrate into pores when their diameter is larger than the Debye length. The Debye length is typically in the order of a few 100 nm up to 1 μm at the conditions under study, depending on electron density and temperature in the plasma streamer. For pores in the range of ∼50 nm, plasma can thus only penetrate to some extent and at very short times, i.e. at the beginning of a micro-discharge, before the actual plasma streamer reaches the catalyst surface and a sheath is formed in front of the surface. We can make plasma streamers penetrate into smaller pores (down to ca. 500 nm at the conditions under study) by increasing the applied voltage, which yields a higher plasma density, and thus reduces the Debye length. Our simulations also reveal that the plasma streamers induce surface charging of the catalyst pore sidewalls, causing discharge enhancement inside the pore, depending on pore diameter and depth.

  8. Nuclear pores and perinuclear expression sites of var and ribosomal DNA genes correspond to physically distinct regions in Plasmodium falciparum.

    Science.gov (United States)

    Guizetti, Julien; Martins, Rafael Miyazawa; Guadagnini, Stéphanie; Claes, Aurélie; Scherf, Artur

    2013-05-01

    The human malaria parasite Plasmodium falciparum modifies the erythrocyte it infects by exporting variant proteins to the host cell surface. The var gene family that codes for a large, variant adhesive surface protein called P. falciparum erythrocyte membrane protein 1 (PfEMP1) plays a particular role in this process, which is linked to pathogenesis and immune evasion. A single member of this gene family is highly transcribed while the other 59 members remain silenced. Importantly, var gene transcription occurs at a spatially restricted, but yet undefined, perinuclear site that is distinct from repressed var gene clusters. To advance our understanding of monoallelic expression, we investigated whether nuclear pores associate with the var gene expression site. To this end, we studied the nuclear pore organization during the asexual blood stage using a specific antibody directed against a subunit of the nuclear pore, P. falciparum Nup116 (PfNup116). Ring and schizont stage parasites showed highly polarized nuclear pore foci, whereas in trophozoite stage nuclear pores redistributed over the entire nuclear surface. Colocalization studies of var transcripts and anti-PfNup116 antibodies showed clear dissociation between nuclear pores and the var gene expression site in ring stage. Similar results were obtained for another differentially transcribed perinuclear gene family, the ribosomal DNA units. Furthermore, we show that in the poised state, the var gene locus is not physically linked to nuclear pores. Our results indicate that P. falciparum does form compartments of high transcriptional activity at the nuclear periphery which are, unlike the case in yeast, devoid of nuclear pores.

  9. Four Weeks in a Single-Leg Weight-Bearing Hip Spica Cast is Sufficient Treatment for Isolated Femoral Shaft Fractures in Children Aged 1 to 3 Years.

    Science.gov (United States)

    Jaafar, Sami; Sobh, Ali; Legakis, Julie E; Thomas, Ronald; Buhler, Kelsey; Jones, Eric T

    2016-01-01

    Hip spica casting regimens for the treatment of femoral shaft fractures in a pediatric population aged 1 to 3 years vary. Patient charts were reviewed to determine if there are any clinical differences between 3 and 4 weeks in an ambulatory single-leg hip spica (SLHS) cast versus 6 to 8 weeks in a standard double-leg, non-weight-bearing hip spica cast. The medical records of 109 patients with femoral shaft fractures treated with a hip spica casting from January 1, 2008 to December 31, 2011 were examined. After exclusions, 94 patients were eligible for inclusion in the study. Patient records were assessed, noting age, weight, type of cast, time in cast, and complications. All casts were applied by senior pediatric orthopaedic surgeons at a single institution. Two groups were evaluated: 59 patients in the SLHS group and 35 in the double-leg hip spica group. The 2 groups were demographically similar with an average age of 2 years, 70.2% of patients were male, 45.7% were black, and 35.1% were white. The average time to cast removal was 4.1 weeks for the single-leg group and 5.3 weeks for the double-leg group (Pshaft fractures in patients less than 4 years old can be treated in a weight-bearing SLHS casts for approximately 4 weeks with fewer alignment and skin complications. Level III-clinical retrospective comparative study.

  10. Primary Infrarenal Aortic Stenting With or Without Iliac Stenting for Isolated and Aortoiliac Stenoses: Single-Centre Experience With Long-Term Follow-Up

    Energy Technology Data Exchange (ETDEWEB)

    Tapping, C. R.; Ahmed, M.; Scott, P. M.; Lakshminarayan, R.; Robinson, G. J.; Ettles, D. F.; Shrivastava, V., E-mail: vivek.shrivastava@hey.nhs.uk [Hull Royal Infirmary, Hull and East Yorkshire Hospitals NHS Trust, Department of Radiology (United Kingdom)

    2013-02-15

    The purpose of this study was to evaluate the technical success, complications, long-term clinical outcome, and patency after primary infrarenal aortic stenting for aortic and aortoiliac stenosis. Between January 1999 and January 2006, 22 consecutive patients underwent endovascular treatment because of infrarenal aortic stenosis with and without common iliac stenosis (10 men; mean age 64 {+-} 14 years). Eleven (11 of 22) patients had an isolated aortic stenosis, whereas 11 of 22 had aortic stenosis that extended into the common iliac arteries (CIAs). Thirteen patients were Rutherford classification type 3, and 9 patients were type 4. Statistical analysis included paired Student t test and Kaplan-Meier life table analysis; p < 0.05 was considered significant. Technical and initial clinical success was achieved in all patients. There were three (14 %) procedure-related complications, which included two access-point pseudoaneurysms and one non-flow-limiting left external iliac dissection. Patients were followed-up for a mean period of 88 months (range 60-132). Mean preprocedure ankle brachial pressure indexes (ABPI) were 0.60 {+-} -0.15 (right) and 0.61 {+-} -0.16 (left). After the procedure they were 0.86 {+-} -0.07 (right) and 0.90 {+-} -0.09 (left). The increase in ABPI was significant (p < 0.05), and this continued throughout follow-up. Four (18 %) patients had recurrence of symptoms during follow-up. These occurred at 36, 48, 48, and 50 months after the original procedure. All four patients were successfully treated with repeat angioplasty procedures. There was a significant difference in primary patency between isolated aortic stenosis (100 %) and aortoiliac stenosis (60 %) (p = 0.031). Cumulative follow-up was 1920 months yielding a reintervention rate of 0.025/events/year. Primary stenting of infrarenal stenosis is safe and successful with a low reintervention rate. It should be considered as first-line treatment for patients with infrarenal aortic stenotic

  11. A novel single-stranded RNA virus isolated from a phytopathogenic filamentous fungus, Rosellinia necatrix, with similarity to hypo-like viruses

    Directory of Open Access Journals (Sweden)

    Rui eZhang

    2014-07-01

    Full Text Available Here we report a biological and molecular characterization of a novel positive-sense RNA virus isolated from a field isolate (NW10 of a filamentous phytopathogenic fungus, the white root rot fungus that is designated as Rosellinia necatrix fusarivirus 1 (RnFV1. A recently developed technology using zinc ions allowed us to transfer RnFV1 to two mycelially incompatible Rosellinia necatrix strains. A biological comparison of the virus-free and -recipient isogenic fungal strains suggested that RnFV1 infects latently and thus has no potential as a virocontrol agent. The virus has an undivided positive-sense RNA genome of 6286 nucleotides excluding a poly (A tail. The genome possesses two non-overlapping open reading frames (ORFs: a large ORF1 that encodes polypeptides with RNA replication functions and a smaller ORF2 that encodes polypeptides of unknown function. A lack of coat protein genes was suggested by the failure of virus particles from infected mycelia. No evidence was obtained by Northern analysis or classical 5'-RACE for the presence of subgenomic RNA for the downstream ORF. Sequence similarities were found in amino-acid sequence between RnFV1 putative proteins and counterparts of a previously reported mycovirus, Fusarium graminearum virus 1 (FgV1. Interestingly, several related sequences were detected by BLAST searches of independent transcriptome assembly databases one of which probably represents an entire virus genome. Phylogenetic analysis based on the conserved RNA-dependent RNA polymerase showed that RnFV1, FgV1, and these similar sequences are grouped in a cluster distinct from distantly related hypoviruses. It is proposed that a new taxonomic family termed Fusariviridae be created to include RnFV1and FgV1.

  12. Physiological functions at single-cell level of Lactobacillus spp. isolated from traditionally fermented cabbage in response to different pH conditions.

    Science.gov (United States)

    Olszewska, Magdalena A; Kocot, Aleksandra M; Łaniewska-Trokenheim, Łucja

    2015-04-20

    Changes in pH are significant environmental stresses that may be encountered by lactobacilli during fermentation processes or passage through the gastrointestinal tract. Here, we report the cell response of Lactobacillus spp. isolated from traditionally fermented cabbage subjected to acid/alkaline treatments at pH 2.5, 7.4 and 8.1, which represented pH conditions of the gastrointestinal tract. Among six isolates, four species of Lactobacillus plantarum and two of Lactobacillus brevis were identified by fluorescence in situ hybridization (FISH). The fluorescence-based strategy of combining carboxyfluorescein diacetate (CFDA) and propidium iodine (PI) into a dual-staining assay was used together with epifluorescence microscopy (EFM) and flow cytometry (FCM) for viability assessment. The results showed that the cells maintained esterase activity and membrane integrity at pH 8.1 and 7.4. There was also no loss of culturability as shown by plate counts. In contrast, the majority of 2.5 pH-treated cells had a low extent of esterase activity, and experienced membrane perturbation. For these samples, an extensive loss of culturability was demonstrated. Comparison of the results of an in situ assessment with that of the conventional culturing method has revealed that although part of the stressed population was unable to grow on the growth media, it was deemed viable using a CFDA/PI assay. However, there was no significant change in the cell morphology among pH-treated lactobacilli populations. These analyses are expected to be useful in understanding the cell response of Lactobacillus strains to pH stress and may facilitate future investigation into functional and industrial aspects of this response. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Spontaneous formation of structurally diverse membrane channel architectures from a single antimicrobial peptide

    Science.gov (United States)

    Wang, Yukun; Chen, Charles H.; Hu, Dan; Ulmschneider, Martin B.; Ulmschneider, Jakob P.

    2016-11-01

    Many antimicrobial peptides (AMPs) selectively target and form pores in microbial membranes. However, the mechanisms of membrane targeting, pore formation and function remain elusive. Here we report an experimentally guided unbiased simulation methodology that yields the mechanism of spontaneous pore assembly for the AMP maculatin at atomic resolution. Rather than a single pore, maculatin forms an ensemble of structurally diverse temporarily functional low-oligomeric pores, which mimic integral membrane protein channels in structure. These pores continuously form and dissociate in the membrane. Membrane permeabilization is dominated by hexa-, hepta- and octamers, which conduct water, ions and small dyes. Pores form by consecutive addition of individual helices to a transmembrane helix or helix bundle, in contrast to current poration models. The diversity of the pore architectures--formed by a single sequence--may be a key feature in preventing bacterial resistance and could explain why sequence-function relationships in AMPs remain elusive.

  14. A Three-Dimensional Pore-Scale Model for Non-Wetting Phase Mobilization with Ferrofluid

    Science.gov (United States)

    Wang, N.; Prodanovic, M.

    2017-12-01

    Ferrofluid, a stable dispersion of paramagnetic nanoparticles in water, can generate a distributed pressure difference across the phase interface in an immiscible two-phase flow under an external magnetic field. In water-wet porous media, this non-uniform pressure difference may be used to mobilize the non-wetting phase, e.g. oil, trapped in the pores. Previous numerical work by Soares et al. of two-dimensional single-pore model showed enhanced non-wetting phase recovery with water-based ferrofluid under certain magnetic field directions and decreased recovery under other directions. However, the magnetic field selectively concentrates in the high magnetic permeability ferrofluid which fills the small corners between the non-wetting phase and the solid wall. The magnetic field induced pressure is proportional to the square of local magnetic field strength and its normal component, and makes a significant impact on the non-wetting phase deformation. The two-dimensional model omitted the effect of most of these corners and is not sufficient to compute the magnetic-field-induced pressure difference or to predict the non-wetting blob deformation. Further, it is not clear that 3D effects on magnetic field in an irregular geometry can be approximated in 2D. We present a three-dimensional immiscible two-phase flow model to simulate the deformation of a non-wetting liquid blob in a single pore filled with a ferrofluid under a uniform external magnetic field. The ferrofluid is modeled as a uniform single phase because the nanoparticles are 104 times smaller than the pore. The open source CFD solver library OpenFOAM is used for the simulations based on the volume of fluid method. Simulations are performed in a converging-diverging channel model on different magnetic field direction, different initial oil saturations, and different pore shapes. Results indicate that the external magnetic field always stretches the non-wetting blob away from the solid channel wall. A magnetic

  15. Performance of multilayer coated silicon pore optics

    Science.gov (United States)

    Ackermann, M. D.; Collon, M. J.; Jensen, C. P.; Christensen, F. E.; Krumrey, M.; Cibik, L.; Marggraf, S.; Bavdaz, M.; Lumb, D.; Shortt, B.

    2010-07-01

    The requirements for the IXO (International X-ray Observatory) telescope are very challenging in respect of angular resolution and effective area. Within a clear aperture with 1.7 m > R > 0.25 m that is dictated by the spacecraft envelope, the optics technology must be developed to satisfy simultaneously requirements for effective area of 2.5 m2 at 1.25 keV, 0.65 m2 at 6 keV and 150 cm2 at 30 keV. The reflectivity of the bare mirror substrate materials does not allow these requirements to be met. As such the IXO baseline design contains a coating layout that varies as a function of mirror radius and in accordance with the variation in grazing incidence angle. The higher energy photon response is enhanced through the use of depth-graded multilayer coatings on the inner radii mirror modules. In this paper we report on the first reflectivity measurements of wedged ribbed silicon pore optics mirror plates coated with a depth graded W/Si multilayer. The measurements demonstrate that the deposition and performance of the multilayer coatings is compatible with the SPO production process.

  16. Current concepts in nuclear pore electrophysiology.

    Science.gov (United States)

    Bustamante, José Omar

    2006-01-01

    Over 4 decades ago, microelectrode studies of in situ nuclei showed that, under certain conditions, the nuclear envelope (NE) behaves as a barrier opposing the nucleocytoplasmic flow of physiological ions. As the nuclear pore complexes (NPCs) of the NE are the only pathways for direct nucleocytoplasmic flow, those experiments implied that the NPCs are capable of restricting ion flow. These early studies validated electrophysiology as a useful approach to quantify some of the mechanisms by which NPCs mediate gene activity and expression. Since electron microscopy (EM) and other non-electrophysiological investigations, showed that the NPC lumen is a nanochannel, the opinion prevailed that the NPC could not oppose the flow of ions and, therefore, that electrophysiological observations resulted from technical artifacts. Consequently, the initial enthusiasm with nuclear electrophysiology faded out in less than a decade. In 1990, nuclear electrophysiology was revisited with patch-clamp, the most powerful electrophysiological technique to date. Patch-clamp has consistently demonstrated that the NE has intrinsic ion channel activity. Direct demonstrations of the NPC on-off ion channel gating behavior were published for artificial conditions in 1995 and for intact living nuclei in 2002. This on-off switching/gating behavior can be interpreted in terms of a metastable energy barrier. In the hope of advancing nuclear electrophysiology, and to complement the other papers contained in this special issue of the journal, here I review some of the main technical, experimental, and theoretical issues of the field, with special focus on NPCs.

  17. The hydraulic conductivity of sediments: A pore size perspective

    KAUST Repository

    Ren, X.W.; Santamarina, Carlos

    2017-01-01

    in the void ratio is higher than the theoretical value due to two concurrent phenomena: 1) percolating large pores are responsible for most of the flow, and 2) the larger pores close first during compaction. The prediction of hydraulic conductivity based

  18. Pore fluids from the argillaceous rocks of the Harwell region

    International Nuclear Information System (INIS)

    Brightman, M.A.; Bath, A.H.; Cave, M.R.; Darling, W.G.

    1985-06-01

    The aim of this work was to obtain samples of pore water from argillaceous formations in the Harwell area for chemical analysis to provide a background for radionuclide migration studies and regional groundwater flow pattern. This report describes the samples, development of a pore-water squeezing cell and its operation. Chemical and analytical studies are summarized. (UK)

  19. Fouling layer characterization and pore-blocking mechanisms in an ...

    African Journals Online (AJOL)

    Fouling layer characterization and pore-blocking mechanisms in an UF membrane externally coupled to a UASB reactor. ... Regarding pore-blocking mechanisms, standard blocking was the predominant mechanism at the beginning of filtration, coexisting at the end of it with cake filtration. In the first filtration cycle (1 h), after ...

  20. Molecular Dynamics Simulations of Hydrophilic Pores in Lipid Bilayers

    NARCIS (Netherlands)

    Leontiadou, Hari; Mark, Alan E.; Marrink, Siewert J.

    Hydrophilic pores are formed in peptide free lipid bilayers under mechanical stress. It has been proposed that the transport of ionic species across such membranes is largely determined by the existence of such meta-stable hydrophilic pores. To study the properties of these structures and understand

  1. The study of the relationship between pore structure and ...

    Indian Academy of Sciences (India)

    Administrator

    The pore structure was determined by the N2 adsorption/desorption method below. 73 K and calculated using the BJH model. TEM characterizations show that the pores are ... Mesoporous TiO2 was obtained by calcination of the gel at 500°C for 6 h in air to remove the surfactant species. The samples were designated as ...

  2. Pore size distribution in tablets measured with a morphological sieve

    NARCIS (Netherlands)

    Wu, Yu San; van Vliet, Lucas J.; Frijlink, Henderik W.; van der Voort Maarschalk, Kees

    2007-01-01

    Porosity and pore structure are important characteristics of tablets, since they influence mechanical strength and many other proper-ties. This paper proposes an alternative method for the characterization of pore structure based on image analysis of SEM micrographs. SEM images were made of sodium

  3. The Pore Structure of Direct Methanol Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    Lund, Peter Brilner

    2005-01-01

    The pore structure and morphology of direct methanol fuel cell electrodes are characterized using mercury intrusion porosimetry and scanning electron microscopy. It is found that the pore size distributions of printed primer and catalyst layers are largely dictated by the powders used to make...

  4. Pore size determination from charged particle energy loss measurement

    International Nuclear Information System (INIS)

    Brady, F.P.; Armitage, B.H.

    1977-01-01

    A new method aimed at measuring porosity and mean pore size in materials has been developed at Harwell. The energy width or variance of a transmitted or backscattered charged particle beam is measured and related to the mean pore size via the assumption that the variance in total path length in the porous material is given by (Δx 2 )=na 2 , where n is the mean number of pores and a the mean pore size. It is shown on the basis of a general and rigorous theory of total path length distribution that this approximation can give rise to large errors in the mean pore size determination particularly in the case of large porosities (epsilon>0.5). In practice it is found that it is not easy to utilize fully the general theory because accurate measurements of the first four moments are required to determine the means and variances of the pore and inter-pore length distributions. Several models for these distributions are proposed. When these are incorporated in the general theory the determinations of mean pore size from experimental measurements on powder samples are in good agreement with values determined by other methods. (Auth.)

  5. A FILTRATION METHOD AND APPARATUS INCLUDING A ROLLER WITH PORES

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention offers a method for separating dry matter from a medium. A separation chamber is at least partly defined by a plurality of rollers (2,7) and is capable of being pressure regulated. At least one of the rollers is a pore roller (7) having a surface with pores allowing permeabi...

  6. Integrative structure and functional anatomy of a nuclear pore complex

    Science.gov (United States)

    Kim, Seung Joong; Fernandez-Martinez, Javier; Nudelman, Ilona; Shi, Yi; Zhang, Wenzhu; Raveh, Barak; Herricks, Thurston; Slaughter, Brian D.; Hogan, Joanna A.; Upla, Paula; Chemmama, Ilan E.; Pellarin, Riccardo; Echeverria, Ignacia; Shivaraju, Manjunatha; Chaudhury, Azraa S.; Wang, Junjie; Williams, Rosemary; Unruh, Jay R.; Greenberg, Charles H.; Jacobs, Erica Y.; Yu, Zhiheng; de La Cruz, M. Jason; Mironska, Roxana; Stokes, David L.; Aitchison, John D.; Jarrold, Martin F.; Gerton, Jennifer L.; Ludtke, Steven J.; Akey, Christopher W.; Chait, Brian T.; Sali, Andrej; Rout, Michael P.

    2018-03-01

    Nuclear pore complexes play central roles as gatekeepers of RNA and protein transport between the cytoplasm and nucleoplasm. However, their large size and dynamic nature have impeded a full structural and functional elucidation. Here we determined the structure of the entire 552-protein nuclear pore complex of the yeast Saccharomyces cerevisiae at sub-nanometre precision by satisfying a wide range of data relating to the molecular arrangement of its constituents. The nuclear pore complex incorporates sturdy diagonal columns and connector cables attached to these columns, imbuing the structure with strength and flexibility. These cables also tie together all other elements of the nuclear pore complex, including membrane-interacting regions, outer rings and RNA-processing platforms. Inwardly directed anchors create a high density of transport factor-docking Phe-Gly repeats in the central channel, organized into distinct functional units. This integrative structure enables us to rationalize the architecture, transport mechanism and evolutionary origins of the nuclear pore complex.

  7. Integrative structure and functional anatomy of a nuclear pore complex.

    Science.gov (United States)

    Kim, Seung Joong; Fernandez-Martinez, Javier; Nudelman, Ilona; Shi, Yi; Zhang, Wenzhu; Raveh, Barak; Herricks, Thurston; Slaughter, Brian D; Hogan, Joanna A; Upla, Paula; Chemmama, Ilan E; Pellarin, Riccardo; Echeverria, Ignacia; Shivaraju, Manjunatha; Chaudhury, Azraa S; Wang, Junjie; Williams, Rosemary; Unruh, Jay R; Greenberg, Charles H; Jacobs, Erica Y; Yu, Zhiheng; de la Cruz, M Jason; Mironska, Roxana; Stokes, David L; Aitchison, John D; Jarrold, Martin F; Gerton, Jennifer L; Ludtke, Steven J; Akey, Christopher W; Chait, Brian T; Sali, Andrej; Rout, Michael P

    2018-03-22

    Nuclear pore complexes play central roles as gatekeepers of RNA and protein transport between the cytoplasm and nucleoplasm. However, their large size and dynamic nature have impeded a full structural and functional elucidation. Here we determined the structure of the entire 552-protein nuclear pore complex of the yeast Saccharomyces cerevisiae at sub-nanometre precision by satisfying a wide range of data relating to the molecular arrangement of its constituents. The nuclear pore complex incorporates sturdy diagonal columns and connector cables attached to these columns, imbuing the structure with strength and flexibility. These cables also tie together all other elements of the nuclear pore complex, including membrane-interacting regions, outer rings and RNA-processing platforms. Inwardly directed anchors create a high density of transport factor-docking Phe-Gly repeats in the central channel, organized into distinct functional units. This integrative structure enables us to rationalize the architecture, transport mechanism and evolutionary origins of the nuclear pore complex.

  8. X-ray microtomography application in pore space reservoir rock

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.F.S.; Lima, I. [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972, Rio de Janeiro (Brazil); Borghi, L. [Geology Department, Geosciences Institute, Federal University of Rio de Janeiro, Brazil. (Brazil); Lopes, R.T., E-mail: ricardo@lin.ufrj.br [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972, Rio de Janeiro (Brazil)

    2012-07-15

    Characterization of porosity in carbonate rocks is important in the oil and gas industry since a major hydrocarbons field is formed by this lithology and they have a complex media porous. In this context, this research presents a study of the pore space in limestones rocks by x-ray microtomography. Total porosity, type of porosity and pore size distribution were evaluated from 3D high resolution images. Results show that carbonate rocks has a complex pore space system with different pores types at the same facies. - Highlights: Black-Right-Pointing-Pointer This study is about porosity parameter in carbonate rocks by 3D X-Ray Microtomography. Black-Right-Pointing-Pointer This study has become useful as data input for modeling reservoir characterization. Black-Right-Pointing-Pointer This technique was able to provide pores, grains and mineralogical differences among the samples.

  9. Measurements of pore-scale flow through apertures

    Energy Technology Data Exchange (ETDEWEB)

    Chojnicki, Kirsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Pore-scale aperture effects on flow in pore networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/pore alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregular cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that pore-scale aperture effects on flow though a pore-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.

  10. Pore-scale modeling of phase change in porous media

    Science.gov (United States)

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

    2017-11-01

    One of the main open challenges in pore-scale modeling is the direct simulation of flows involving multicomponent mixtures with complex phase behavior. Reservoir fluid mixtures are often described through cubic equations of state, which makes diffuse interface, or phase field theories, particularly appealing as a modeling framework. What is still unclear is whether equation-of-state-driven diffuse-interface models can adequately describe processes where surface tension and wetting phenomena play an important role. Here we present a diffuse interface model of single-component, two-phase flow (a van der Waals fluid) in a porous medium under different wetting conditions. We propose a simplified Darcy-Korteweg model that is appropriate to describe flow in a Hele-Shaw cell or a micromodel, with a gap-averaged velocity. We study the ability of the diffuse-interface model to capture capillary pressure and the dynamics of vaporization/condensation fronts, and show that the model reproduces pressure fluctuations that emerge from abrupt interface displacements (Haines jumps) and from the break-up of wetting films.

  11. HYDROXYETHYL METHACRYLATE BASED NANOCOMPOSITE HYDROGELS WITH TUNABLE PORE ARCHITECTURE

    Directory of Open Access Journals (Sweden)

    Erhan Bat

    2016-10-01

    Full Text Available Hydroxyethyl methacrylate (HEMA based hydrogels have found increasing number of applications in areas such as chromatographic separations, controlled drug release, biosensing, and membrane separations. In all these applications, the pore size and pore interconnectivity are crucial for successful application of these materials as they determine the rate of diffusion through the matrix. 2-Hydroxyethyl methacrylate is a water soluble monomer but its polymer, polyHEMA, is not soluble in water. Therefore, during polymerization of HEMA in aqueous media, a porous structure is obtained as a result of phase separation. Pore size and interconnectivity in these hydrogels is a function of several variables such as monomer concentration, cross-linker concentration, temperature etc. In this study, we investigated the effect of monomer concentration, graphene oxide addition or clay addition on hydrogel pore size, pore interconnectivity, water uptake, and thermal properties. PolyHEMA hydrogels have been prepared by redox initiated free radical polymerization of the monomer using ethylene glycol dimethacrylate as a cross-linker. As a nanofiller, a synthetic hectorite Laponite® XLG and graphene oxide were used. Graphene oxide was prepared by the Tour Method. Pore morphology of the pristine HEMA based hydrogels and nanocomposite hydrogels were studied by scanning electron microscopy. The formed hydrogels were found to be highly elastic and flexible. A dramatic change in the pore structure and size was observed in the range between 22 to 24 wt/vol monomer at 0.5 % of cross-linker. In this range, the hydrogel morphology changes from typical cauliflower architecture to continuous hydrogel with dispersed water droplets forming the pores where the pores are submicron in size and show an interconnected structure. Such controlled pore structure is highly important when these hydrogels are used for solute diffusion or when there’s flow through monolithic hydrogels

  12. Surfactant-enhanced control of track-etch pore morphology

    International Nuclear Information System (INIS)

    Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

    2000-01-01

    The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

  13. Primary Infrarenal Aortic Stenting With or Without Iliac Stenting for Isolated and Aortoiliac Stenoses: Single-Centre Experience With Long-Term Follow-Up

    International Nuclear Information System (INIS)

    Tapping, C. R.; Ahmed, M.; Scott, P. M.; Lakshminarayan, R.; Robinson, G. J.; Ettles, D. F.; Shrivastava, V.

    2013-01-01

    The purpose of this study was to evaluate the technical success, complications, long-term clinical outcome, and patency after primary infrarenal aortic stenting for aortic and aortoiliac stenosis. Between January 1999 and January 2006, 22 consecutive patients underwent endovascular treatment because of infrarenal aortic stenosis with and without common iliac stenosis (10 men; mean age 64 ± 14 years). Eleven (11 of 22) patients had an isolated aortic stenosis, whereas 11 of 22 had aortic stenosis that extended into the common iliac arteries (CIAs). Thirteen patients were Rutherford classification type 3, and 9 patients were type 4. Statistical analysis included paired Student t test and Kaplan–Meier life table analysis; p < 0.05 was considered significant. Technical and initial clinical success was achieved in all patients. There were three (14 %) procedure-related complications, which included two access-point pseudoaneurysms and one non–flow-limiting left external iliac dissection. Patients were followed-up for a mean period of 88 months (range 60–132). Mean preprocedure ankle brachial pressure indexes (ABPI) were 0.60 ± −0.15 (right) and 0.61 ± −0.16 (left). After the procedure they were 0.86 ± −0.07 (right) and 0.90 ± −0.09 (left). The increase in ABPI was significant (p < 0.05), and this continued throughout follow-up. Four (18 %) patients had recurrence of symptoms during follow-up. These occurred at 36, 48, 48, and 50 months after the original procedure. All four patients were successfully treated with repeat angioplasty procedures. There was a significant difference in primary patency between isolated aortic stenosis (100 %) and aortoiliac stenosis (60 %) (p = 0.031). Cumulative follow-up was 1920 months yielding a reintervention rate of 0.025/events/year. Primary stenting of infrarenal stenosis is safe and successful with a low reintervention rate. It should be considered as first-line treatment for patients with infrarenal aortic

  14. Molecular basis of usher pore gating in Escherichia coli pilus biogenesis.

    Science.gov (United States)

    Volkan, Ender; Kalas, Vasilios; Pinkner, Jerome S; Dodson, Karen W; Henderson, Nadine S; Pham, Thieng; Waksman, Gabriel; Delcour, Anne H; Thanassi, David G; Hultgren, Scott J

    2013-12-17

    Extracellular fibers called chaperone-usher pathway pili are critical virulence factors in a wide range of Gram-negative pathogenic bacteria that facilitate binding and invasion into host tissues and mediate biofilm formation. Chaperone-usher pathway ushers, which catalyze pilus assembly, contain five functional domains: a 24-stranded transmembrane β-barrel translocation domain (TD), a β-sandwich plug domain (PLUG), an N-terminal periplasmic domain, and two C-terminal periplasmic domains (CTD1 and 2). Pore gating occurs by a mechanism whereby the PLUG resides stably within the TD pore when the usher is inactive and then upon activation is translocated into the periplasmic space, where it functions in pilus assembly. Using antibiotic sensitivity and electrophysiology experiments, a single salt bridge was shown to function in maintaining the PLUG in the TD channel of the P pilus usher PapC, and a loop between the 12th and 13th beta strands of the TD (β12-13 loop) was found to facilitate pore opening. Mutation of the β12-13 loop resulted in a closed PapC pore, which was unable to efficiently mediate pilus assembly. Deletion of the PapH terminator/anchor resulted in increased OM permeability, suggesting a role for the proper anchoring of pili in retaining OM integrity. Further, we introduced cysteine residues in the PLUG and N-terminal periplasmic domains that resulted in a FimD usher with a greater propensity to exist in an open conformation, resulting in increased OM permeability but no loss in type 1 pilus assembly. These studies provide insights into the molecular basis of usher pore gating and its roles in pilus biogenesis and OM permeability.

  15. A statistical image analysis framework for pore-free islands derived from heterogeneity distribution of nuclear pore complexes.

    Science.gov (United States)

    Mimura, Yasuhiro; Takemoto, Satoko; Tachibana, Taro; Ogawa, Yutaka; Nishimura, Masaomi; Yokota, Hideo; Imamoto, Naoko

    2017-11-24

    Nuclear pore complexes (NPCs) maintain cellular homeostasis by mediating nucleocytoplasmic transport. Although cyclin-dependent kinases (CDKs) regulate NPC assembly in interphase, the location of NPC assembly on the nuclear envelope is not clear. CDKs also regulate the disappearance of pore-free islands, which are nuclear envelope subdomains; this subdomain gradually disappears with increase in homogeneity of the NPC in response to CDK activity. However, a causal relationship between pore-free islands and NPC assembly remains unclear. Here, we elucidated mechanisms underlying NPC assembly from a new perspective by focusing on pore-free islands. We proposed a novel framework for image-based analysis to automatically determine the detailed 'landscape' of pore-free islands from a large quantity of images, leading to the identification of NPC intermediates that appear in pore-free islands with increased frequency in response to CDK activity. Comparison of the spatial distribution between simulated and the observed NPC intermediates within pore-free islands showed that their distribution was spatially biased. These results suggested that the disappearance of pore-free islands is highly related to de novo NPC assembly and indicated the existence of specific regulatory mechanisms for the spatial arrangement of NPC assembly on nuclear envelopes.

  16. Buoyancy-driven chaotic regimes during solute dispersion in pore networks

    International Nuclear Information System (INIS)

    Tsakiroglou, C.D.; Theodoropoulou, M.A.; Karoutsos, V.

    2005-01-01

    In an attempt to investigate gravity effects on solute dispersion at the scale of a pore network, single source-solute transport visualization experiments are performed on glass-etched pore networks of varying morphology and degree of pore-scale heterogeneities. The (lighter) low solute concentration aqueous solution flows steadily through the porous medium and the (heavier) high solute concentration solution is injected at a very low and constant flow rate through an inner port. The transient evolution of the solute concentration distribution over various regions of the pore network is determined at different scales by capturing and video-recording snapshots of the dispersion on PC, measuring automatically the spatial variation of the color intensity of the solution, and transforming the color intensities to solute concentrations. Without the action of gravity, the steady-state dispersion regime changes with Peclet (Pe) number, and the longitudinal and transverse dispersivities are estimated by fitting the experimental datasets to approximate analytic solutions of the advection-dispersion equation. Under the action of gravity, multiple of steady-state solute dispersion regimes is developed at each Pe value, and lobe-shaped instabilities of the solute concentration are observed across the pore network, as the downward flow of the denser (higher solute concentration) fluid is counterbalanced by the upward flow of the less dense (lower solute concentration) fluid. The steady-state dispersion regimes may be periodic, quasi-periodic or chaotic depending on the system parameters. The nature of the transient fluctuations of the average solute concentration is analyzed by identifying the periodicity of the fluctuations, determining the autocorrelation function and the statistical moments of the time series, and inspecting the FFT (fast Fourier transform) power spectra. It is found that the mixing zone tends to be stabilized at higher values of the Peclet (Pe) number

  17. Pore Scale Dynamics of Microemulsion Formation.

    Science.gov (United States)

    Unsal, Evren; Broens, Marc; Armstrong, Ryan T

    2016-07-19

    Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

  18. Isolation and partial characterization of Alzheimer neurofibrillary tangles

    International Nuclear Information System (INIS)

    Goni, F.; Alvarez, F.; Gorevic, P.D.; Pons-Estel, F.

    1986-01-01

    Neurofibrillary tangles (NFT) were isolated from cerebral cortex of three cases of Alzheimer's disease (AD) by SDS-βME treatment followed by sucrose gradient ultracentrifugation. This material was predominantly NFT by electron microscopy and was excluded from all pore-sized polyacrylamide gels. It remained insoluble in strong acid and basic conditions, chaotropic and reducing agents. It resisted digestion by trypsin, chymotrypsin, subtilisin, urea-pepsin, collagenase, pronase, hyaluronidase, lipases and phospholipases but yielded a consistent amino acid analysis showing the presence of cysteine and methionine, more than 20% hydrophobic residues and 12% basic residues. Subjected to automated Edman degradation presented a non-reactive amino terminus. Under electron microscopy NFT appeared to be composed mainly by single and double filaments. Single filaments can turn and intertwine with themselves to make the regular arrangement of the double filaments. Purified NFT have been used to raise high titered polyclonal antisera for immunohistological studies. It specifically reacted with isolated NFT, affected neurons in cases of AD, aging brains, postencephalitic Parkinson's disease, Down's syndrome and dementia pugilistica but no reaction was observed with normal brain, cerebrovascular amyloid angiopathy, or the amyloid core from neuritic plaques

  19. Two micron pore size MCP-based image intensifiers

    Science.gov (United States)

    Glesener, John; Estrera, Joseph

    2010-02-01

    Image intensifiers (I2) have many advantages as detectors. They offer single photon sensitivity in an imaging format, they're light in weight and analog I2 systems can operate for hours on a single AA battery. Their light output is such as to exploit the peak in color sensitivity of the human eye. Until recent developments in CMOS sensors, they also were one of the highest resolution sensors available. The closest all solid state solution, the Texas Instruments Impactron chip, comes in a 1 megapixel format. Depending on the level of integration, an Impactron based system can consume 20 to 40 watts in a system configuration. In further investing in I2 technology, L-3 EOS determined that increasing I2 resolution merited a high priority. Increased I2 resolution offers the system user two desirable options: 1) increased detection and identification ranges while maintaining field-of-view (FOV) or 2) increasing FOV while maintaining the original system resolution. One of the areas where an investment in resolution is being made is in the microchannel plate (MCP). Incorporation of a 2 micron MCP into an image tube has the potential of increasing the system resolution of currently fielded systems. Both inverting and non-inverting configurations are being evaluated. Inverting tubes are being characterized in night vision goggle (NVG) and sights. The non-inverting 2 micron tube is being characterized for high resolution I2CMOS camera applications. Preliminary measurements show an increase in the MTF over a standard 5 micron pore size, 6 micron pitch plate. Current results will be presented.

  20. Nanofiltration Membranes with Narrow Pore Size Distribution via Contra-Diffusion-Induced Mussel-Inspired Chemistry.

    Science.gov (United States)

    Du, Yong; Qiu, Wen-Ze; Lv, Yan; Wu, Jian; Xu, Zhi-Kang

    2016-11-02

    Nanofiltration membranes (NFMs) are widely used in saline water desalination, wastewater treatment, and chemical product purification. However, conventional NFMs suffer from broad pore size distribution, which limits their applications for fine separation, especially in complete separation of molecules with slight differences in molecular size. Herein, defect-free composite NFMs with narrow pore size distribution are fabricated using a contra-diffusion method, with dopamine/polyethylenimine solution on the skin side and ammonium persulfate solution on the other side of the ultrafiltration substrate. Persulfate ions can diffuse through the ultrafiltration substrate into the other side and in situ trigger dopamine to form a codeposited coating with polyethylenimine. The codeposition is hindered on those sites completely covered by the polydopamine/polyethylenimine coating, although it is promoted at the defects or highly permeable regions because it is induced by the diffused persulfate ions. Such a "self-completion" process results in NFMs with highly uniform structures and narrow pore size distribution, as determined by their rejection of neutral solutes. These near electrically neutral NFMs show a high rejection of divalent ions with a low rejection of monovalent ions (MgCl 2 rejection = 96%, NaCl rejection = 23%), majorly based on a steric hindrance effect. The as-prepared NFMs can be applied in molecular separation such as isolating cellulose hydrogenation products.

  1. Pore structure and carbonation in blended lime-cement pastes

    Directory of Open Access Journals (Sweden)

    Álvarez, J. I.

    2006-06-01

    Full Text Available The present study aims to gain a fuller understandingof the curing process in lime pastes (100, 90, 80, 70,60, 50 and 40% lime blended with cement by analyzingcarbonation in these materials. A hydrated, airslaked lime powder and CEM II A/L 32.5 Portlandcement were used for the blends. These materialswere singled out for research primarily because theymay be used in the restoration of heritage monuments.Variation in weight was used as an indicator for carbonation.A new parameter, A, was found to vary inverselywith the percentage of the cement because of theprevalence of Knudsen diffusion in the paste, in turndue to the characteristics of the pore structure, whichwas studied by mercury intrusion porosimetry (MIP.The hygroscopic study conducted on the different pastesprovided information on water content at a givenhumidity and its location, i.e., adsorbed on the surfaceof the pores or condensed inside them, obstructing thediffusion of CO2. The conclusion drawn from this studyof the curing process was that neither drying nor C3Shydration retarded lime carbonation.En este trabajo se estudia el proceso de carbonatacionen pastas mixtas de cal y cemento (100, 90, 80, 70, 60,50 y 40% de cal con el objeto de obtener un mejorconocimiento del proceso de curado en estos materiales.Para ello se ha empleado una cal aerea hidratada en polvoy un cemento Portland del tipo CEM II A/L 32,5. Enparticular, este estudio investiga estos materiales ya quepueden ser utilizados en la restauracion del PatrimonioCultural. Se ha utilizado la variacion de peso como indicadordel proceso de carbonatacion. Se ha establecidoun nuevo parametro, A, que varia inversamente con elporcentaje de cemento en la pasta, debido al predominiode la difusion de Knudsen como consecuencia de laestructura porosa, que ha sido estudiada por medio deporosimetria de intrusion de mercurio (PIM. El estudiohigroscopico realizado sobre las diversas pastas permiteconocer el contenido en agua a una

  2. Rapid concentration and dialysis of proteins with single hollow fibers: possible applications in analysis of protein secretion by isolated cells and steroid radioimmunoassays

    International Nuclear Information System (INIS)

    Rommerts, F.F.G.; Clotscher, W.F.; Van der Molen, H.J.

    1977-01-01

    Single hollow fibers were used in specially made cells for fast concentration and dialysis of solutions containing macromolecules. Volumes on the order of 5 ml of diluted protein solutions could be concentrated to 50--100 μl or less within 7 min with a protein recovery of 60--80%. More than 99% of the molecules with a molecular weight less than 500 could be removed in less than 1 hr. A possible application of the rapid dialysis method for the mechanization of radioimmunoassays is indicated. It was shown that in the radioimmunoassay of steriods the unbound steroids could be removed after incubation with antiserum, within 10 min and without a change in volume

  3. AFLP fragment isolation technique as a method to produce random sequences for single nucleotide polymorphism discovery in the green turtle, Chelonia mydas.

    Science.gov (United States)

    Roden, Suzanne E; Dutton, Peter H; Morin, Phillip A

    2009-01-01

    The green sea turtle, Chelonia mydas, was used as a case study for single nucleotide polymorphism (SNP) discovery in a species that has little genetic sequence information available. As green turtles have a complex population structure, additional nuclear markers other than microsatellites could add to our understanding of their complex life history. Amplified fragment length polymorphism technique was used to generate sets of random fragments of genomic DNA, which were then electrophoretically separated with precast gels, stained with SYBR green, excised, and directly sequenced. It was possible to perform this method without the use of polyacrylamide gels, radioactive or fluorescent labeled primers, or hybridization methods, reducing the time, expense, and safety hazards of SNP discovery. Within 13 loci, 2547 base pairs were screened, resulting in the discovery of 35 SNPs. Using this method, it was possible to yield a sufficient number of loci to screen for SNP markers without the availability of prior sequence information.

  4. Isolated galaxies

    International Nuclear Information System (INIS)

    Einasto, Maret

    1990-01-01

    To test for the possible presence of really isolated galaxies, which form a randomly distributed population in voids, we compare the distribution of most isolated galaxies in an observed sample with distributions of the same number of random points using the nearest neighbour test. The results show that the random population of really isolated galaxies does not exist - even the most isolated galaxies are connected with systems of galaxies, forming their outlying parts. (author)

  5. Superplastically foaming method to make closed pores inclusive porous ceramics

    International Nuclear Information System (INIS)

    Kishimoto, Akira; Hayashi, Hidetaka

    2011-01-01

    Porous ceramics incorporates pores to improve several properties including thermal insulation maintaining inherenet ceramic properties such as corrosion resistance and large mechanical strength. Conventional porous ceramics is usually fabricated through an insufficient sintering. Since the sintering accompanies the exclusion of pores, it must be terminated at the early stage to maintain the high porosity, leading to degraded strength and durability. Contrary to this, we have innovated superplastically foaming method to make ceramic foams only in the solid state. In this method, the previously inserted foam agent evaporates after the full densification of matrix at around the sintering temperature. Closed pores expand utilizing the superplastic deformation driven by the evolved gas pressure. The typical features of this superplastically foaming method are listed as follows, 1. The pores are introduced after sintering the solid polycrystal. 2. Only closed pores are introduced, improving the insulation of gas and sound in addition to heat. 3. The pore walls are fully densified expecting a large mechanical strength. 4. Compared with the melt foaming method, this method is practical because the fabrication temperature is far below the melting point and it does not need molds. 5. The size and the location pores can be controlled by the amount and position of the foam agent.

  6. Nuclear Pore-Like Structures in a Compartmentalized Bacterium.

    Directory of Open Access Journals (Sweden)

    Evgeny Sagulenko

    Full Text Available Planctomycetes are distinguished from other Bacteria by compartmentalization of cells via internal membranes, interpretation of which has been subject to recent debate regarding potential relations to Gram-negative cell structure. In our interpretation of the available data, the planctomycete Gemmata obscuriglobus contains a nuclear body compartment, and thus possesses a type of cell organization with parallels to the eukaryote nucleus. Here we show that pore-like structures occur in internal membranes of G.obscuriglobus and that they have elements structurally similar to eukaryote nuclear pores, including a basket, ring-spoke structure, and eight-fold rotational symmetry. Bioinformatic analysis of proteomic data reveals that some of the G. obscuriglobus proteins associated with pore-containing membranes possess structural domains found in eukaryote nuclear pore complexes. Moreover, immunogold labelling demonstrates localization of one such protein, containing a β-propeller domain, specifically to the G. obscuriglobus pore-like structures. Finding bacterial pores within internal cell membranes and with structural similarities to eukaryote nuclear pore complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence.

  7. Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

    Science.gov (United States)

    Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-03-07

    Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance.

  8. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-01-01

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  9. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-04-24

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  10. Pore Structures in the Biomineralized Byssus of Anomia simplex

    DEFF Research Database (Denmark)

    Frølich, Simon; Leemreize, Hanna; Thomsen, Jesper Skovhus

    2016-01-01

    that uses a biomineralized byssus to permanently anchor itself to substrates. The byssus has a highly complex hierarchical structure and contains over 90 wt% CaCO3. The byssus features a complex set of porosities, presumed to be highly important for the function of the attachment system. The pore space...... is the main focus of the present work. We characterize the three dimensional distribution of pore spaces in the byssus using micro-computed tomography (µCT) through a combination of in house CT and high-resolution synchrotron CT. The pore structures are observed to fall into distinct categories in various...

  11. Crystalline mesoporous zirconia catalysts having stable tetragonal pore wall structure

    Science.gov (United States)

    Sachtler, W.M.H.; Huang, Y.Y.

    1998-07-28

    Methods are disclosed for the preparation of new sulfated mesoporous zirconia materials/catalysts with crystalline pore walls of predominantly tetragonal crystal structure, characterized by nitrogen physical sorption measurement, X-ray diffraction, transmission electron microscopy and catalytic tests using n-butane isomerization to iso-butane and alkylation of 1-naphthol with 4-tert-butylstyrene as probe reactions. Sulfate deposition is preferred for the transformation of a mesoporous precursor with amorphous pore walls into a material with crystalline pore walls maintaining the mesoporous characteristics. 17 figs.

  12. Tension-induced vesicle fusion: pathways and pore dynamics

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2008-01-01

    and eventually opens a pore to complete the fusion process. In pathway II, at higher tension, a stalk is formed during the fusion process that is then transformed by transmembrane pore formation into a fusion pore. Whereas the latter pathway II resembles stalk pathways as observed in other simulation studies......, fusion pathway I, which does not involve any stalk formation, has not been described previously to the best of our knowledge. A statistical analysis of the various processes shows that fusion is the dominant pathway for releasing the tension of the vesicles. The functional dependence of the observed...

  13. Time evolution of pore system in lime - Pozzolana composites

    Science.gov (United States)

    Doleželová, Magdaléna; Čáchová, Monika; Scheinherrová, Lenka; Keppert, Martin

    2017-11-01

    The lime - pozzolana mortars and plasters are used in restoration works on building cultural heritage but these materials are also following the trend of energy - efficient solutions in civil engineering. Porosity and pore size distribution is one of crucial parameters influencing engineering properties of porous materials. The pore size distribution of lime based system is changing in time due to chemical processes occurring in the material. The present paper describes time evolution of pore system in lime - pozzolana composites; the obtained results are useful in prediction of performance of lime - pozzolana systems in building structures.

  14. Single Beam Holography.

    Science.gov (United States)

    Chen, Hsuan; Ruterbusch, Paul H.

    1979-01-01

    Discusses how holography can be used as part of undergraduate physics laboratories. The authors propose a single beam technique of holography, which will reduce the recording scheme as well as relax the isolation requirements. (HM)

  15. Sequence Analysis of IncA/C and IncI1 Plasmids Isolated from Multidrug-Resistant Salmonella Newport Using Single-Molecule Real-Time Sequencing.

    Science.gov (United States)

    Cao, Guojie; Allard, Marc; Hoffmann, Maria; Muruvanda, Tim; Luo, Yan; Payne, Justin; Meng, Kevin; Zhao, Shaohua; McDermott, Patrick; Brown, Eric; Meng, Jianghong

    2018-04-05

    Multidrug-resistant (MDR) plasmids play an important role in disseminating antimicrobial resistance genes. To elucidate the antimicrobial resistance gene compositions in A/C incompatibility complex (IncA/C) plasmids carried by animal-derived MDR Salmonella Newport, and to investigate the spread mechanism of IncA/C plasmids, this study characterizes the complete nucleotide sequences of IncA/C plasmids by comparative analysis. Complete nucleotide sequencing of plasmids and chromosomes of six MDR Salmonella Newport strains was performed using PacBio RSII. Open reading frames were assigned using prokaryotic genome annotation pipeline (PGAP). To understand genomic diversity and evolutionary relationships among Salmonella Newport IncA/C plasmids, we included three complete IncA/C plasmid sequences with similar backbones from Salmonella Newport and Escherichia coli: pSN254, pAM04528, and peH4H, and additional 200 draft chromosomes. With the exception of canine isolate CVM22462, which contained an additional IncI1 plasmid, each of the six MDR Salmonella Newport strains contained only the IncA/C plasmid. These IncA/C plasmids (including references) ranged in size from 80.1 (pCVM21538) to 176.5 kb (pSN254) and carried various resistance genes. Resistance genes floR, tetA, tetR, strA, strB, sul, and mer were identified in all IncA/C plasmids. Additionally, bla CMY-2 and sugE were present in all IncA/C plasmids, excepting pCVM21538. Plasmid pCVM22462 was capable of being transferred by conjugation. The IncI1 plasmid pCVM22462b in CVM22462 carried bla CMY-2 and sugE. Our data showed that MDR Salmonella Newport strains carrying similar IncA/C plasmids clustered together in the phylogenetic tree using chromosome sequences and the IncA/C plasmids from animal-derived Salmonella Newport contained diverse resistance genes. In the current study, we analyzed genomic diversities and phylogenetic relationships among MDR Salmonella Newport using complete plasmids and chromosome

  16. Thermodynamics of Pore Filling Metal Clusters in Metal Organic Frameworks: Pd in UiO-66

    DEFF Research Database (Denmark)

    Vilhelmsen, Lasse; Sholl, David S.

    2012-01-01

    Metal organic frameworks (MOFs) have experimentally been demonstrated to be capable of supporting isolated transition-metal clusters, but the stability of these clusters with respect to aggregation is unclear. In this letter we use a genetic algorithm together with density functional theory...... calculations to predict the structure of Pd clusters in UiO-66. The cluster sizes examined are far larger than those in any previous modeling studies of metal clusters in MOFs and allow us to test the hypothesis that the physically separated cavities in UiO-66 could stabilize isolated Pd clusters. Our...... calculations show that Pd clusters in UiO-66 are, at best, metastable and will aggregate into connected pore filling structures at equilibrium....

  17. The effect of pore size on tissue ingrowth and neovascularization in porous bioceramics of controlled architecture in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Bai Feng; Zhang Jinkang; Wang Zhen; Liu Jian; Meng Guolin; Dong Xin [Institute of Orthopedic Surgery, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Lu Jianxi; Chang Jiang, E-mail: baifeng_fmmu@126.com [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2011-02-15

    The purpose of this study was to investigate the role of pore size on tissue ingrowth and neovascularization in porous bioceramics under the accurate control of the pore parameters. For that purpose, {beta}-tricalcium phosphate ({beta}-TCP) cylinders with four different macropore sizes (300-400, 400-500, 500-600 and 600-700 {mu}m) but the same interconnection size (120 {mu}m) and unchangeable porosity were implanted into fascia lumbodorsalis in rabbits. The fibrous tissues and blood vessels formed in scaffolds were observed histologically and histomorphometrically. The vascularization of the porous bioceramics was analyzed by single-photon emission computed tomography (SPECT). It is found that pore size as an important parameter of a porous structure plays an important role in tissue infiltration into porous biomaterial scaffolds. The amount of fibrous tissue ingrowth increases with the decrease of the pore size. In four kinds of scaffolds with different macropore sizes (300-400, 400-500, 500-600 and 600-700 {mu}m) and a constant interconnection size of 120 {mu}m, the areas of fibrous tissue (%) were 60.5%, 52.2%, 41.3% and 37.3%, respectively, representing a significant decrease at 4 weeks (P < 0.01). The pore size of a scaffold is closely related to neovascularization of macroporous biomaterials implanted in vivo. A large pore size is beneficial for the growth of blood vessels, and the diameter of a pore smaller than 400 {mu}m limits the growth of blood vessels and results in a smaller blood vessel diameter.

  18. Salvage Stereotactic Body Radiotherapy for Isolated Lymph Node Recurrent Prostate Cancer: Single Institution Series of 94 Consecutive Patients and 124 Lymph Nodes.

    Science.gov (United States)

    Jereczek-Fossa, Barbara Alicja; Fanetti, Giuseppe; Fodor, Cristiana; Ciardo, Delia; Santoro, Luigi; Francia, Claudia Maria; Muto, Matteo; Surgo, Alessia; Zerini, Dario; Marvaso, Giulia; Timon, Giorgia; Romanelli, Paola; Rondi, Elena; Comi, Stefania; Cattani, Federica; Golino, Federica; Mazza, Stefano; Matei, Deliu Victor; Ferro, Matteo; Musi, Gennaro; Nolè, Franco; de Cobelli, Ottavio; Ost, Piet; Orecchia, Roberto

    2017-08-01

    The purpose of the study was to evaluate the prostate serum antigen (PSA) response, local control, progression-free survival (PFS), and toxicity of stereotactic body radiotherapy (SBRT) for lymph node (LN) oligorecurrent prostate cancer. Between May 2012 and October 2015, 124 lesions were treated in 94 patients with a median dose of 24 Gy in 3 fractions. Seventy patients were treated for a single lesion and 25 for > 1 lesion. In 34 patients androgen deprivation (AD) was combined with SBRT. We evaluated biochemical response according to PSA level every 3 months after SBRT: a 3-month PSA decrease from pre-SBRT PSA of more than 10% identified responder patients. In case of PSA level increase, imaging was performed to evaluate clinical progression. Toxicity was assessed every 6 to 9 months after SBRT. Median follow-up was 18.5 months. In 13 patients (14%) Grade 1 to 2 toxicity was reported without any Grade 3 to 4 toxicity. Biochemical response, stabilization, and progression were observed in 64 (68%), 10 (11%), and 20 (21%) of 94 evaluable patients. Clinical progression was observed in 31 patients (33%) after a median time of 8.1 months. In-field progression occurred in 12 lesions (9.7%). Two-year local control and PFS rates were 84% and 30%, respectively. Age older than 75 years correlated with better biochemical response rate. Age older than 75 years, concomitant AD administered up to 12 months, and pelvic LN involvement correlated with longer PFS. SBRT is safe and offers good in-field control. At 2 years after SBRT, 1 of 3 patients is progression-free. Further investigation is warranted to identify patients who benefit most from SBRT and to define the optimal combination with AD. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Earthworm-Derived Pore-Forming Toxin Lysenin and Screening of Its Inhibitors

    Directory of Open Access Journals (Sweden)

    Neelanun Sukumwang

    2013-08-01

    Full Text Available Lysenin is a pore-forming toxin from the coelomic fluid of earthworm Eisenia foetida. This protein specifically binds to sphingomyelin and induces erythrocyte lysis. Lysenin consists of 297 amino acids with a molecular weight of 41 kDa. We screened for cellular signal transduction inhibitors of low molecular weight from microorganisms and plants. The purpose of the screening was to study the mechanism of diseases using the obtained inhibitors and to develop new chemotherapeutic agents acting in the new mechanism. Therefore, our aim was to screen for inhibitors of Lysenin-induced hemolysis from plant extracts and microbial culture filtrates. As a result, we isolated all-E-lutein from an extract of Dalbergia latifolia leaves. All-E-lutein is likely to inhibit the process of Lysenin-membrane binding and/or oligomer formation rather than pore formation. Additionally, we isolated tyrosylproline anhydride from the culture filtrate of Streptomyces as an inhibitor of Lysenin-induced hemolysis.

  20. Hexadecane trapped in nano-pores of silica-aerogel

    International Nuclear Information System (INIS)

    Slavikova, B.; Jesenak, K.; Iskrova, M.; Majernik, V.; Sausa, O.; Kristiak, J.

    2009-01-01

    Ways of filling of the high-porous silica-aerogel with hydrocarbon C 16 H 34 and its efficient removal from the pores by physical method of the Positron Annihilation Spectroscopy were studied. As the most effective way to fill the SiO 2 aerogel appears through the implementation of a liquid phase, while the most appropriate way of removing of hexadecane is firing at an elevated temperature. Molecular system of hexadecane closed in nano-pores of silica-aerogel behaves otherwise than volume system of the same molecules. In the case of pure hexadecane phase transition was observed at 291 K, while solidification process is gradual with decrease of temperature in cetane trapped in pores of silica-aerogel. The results of the periods of life of o-Ps indicate greater turbidity in the pores of the molecular system compared to the volume sample of hexadecane.

  1. A simulation of earthquake induced undrained pore pressure ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Plains, Kandla River and Gulf of Kachch, between .... We consider the role of induced pore pressure ... location of the Bhuj earthquake epicentre as estimated by US Geological Survey. .... war R 2001 Changes in Ocean; GIS @ development 5.

  2. Microfiltration of distillery stillage: Influence of membrane pore size

    Directory of Open Access Journals (Sweden)

    Vasić Vesna M.

    2012-01-01

    Full Text Available Stillage is one of the most polluted waste products of the food industry. Beside large volume, the stillage contains high amount of suspended solids, high values of chemical oxygen demand and biological oxygen demand, so it should not be discharged in the nature before previous purification. In this work, three ceramic membranes for microfiltration with different pore sizes were tested for stillage purification in order to find the most suitable membrane for the filtration process. Ceramic membranes with a nominal pore size of 200 nm, 450 nm and 800 nm were used for filtration. The influence of pore size on permeate flux and removal efficiency was investigated. A membrane with the pore size of 200 nm showed the best filtration performance so it was chosen for the microfiltration process.

  3. Mesoporous Akaganeite of Adjustable Pore Size Synthesized using Mixed Templates

    Science.gov (United States)

    Zhang, Y.; Ge, D. L.; Ren, H. P.; Fan, Y. J.; Wu, L. M.; Sun, Z. X.

    2017-12-01

    Mesoporous akaganeite with large and adjustable pore size was synthesized through a co-template method, which was achieved by the combined interaction between PEG2000 and alkyl amines with different lengths of the straight carbon chain. The characterized results indicate that the synthesized samples show comparatively narrow BJH pore size distributions and centered at 14.3 nm when PEG and HEPA was used, and it could be enlarged to 16.8 and 19.4 nm respectively through changing the alkyl amines to DDA and HDA. Meanwhile, all the synthesized akaganeite possess relativity high specific surface area ranging from 183 to 281 m2/g and high total pore volume of 0.98 to 1.5 cm3/g. A possible mechanism leading to the pore size changing was also proposed.

  4. Brine and Gas Flow Patterns Between Excavated Areas and Disturbed Rock Zone in the 1996 Performance Assessment for the Waste Isolation Pilot Plant for a Single Drilling Intrusion that Penetrates Repository and Castile Brine Reservoir

    International Nuclear Information System (INIS)

    Economy, Kathleen M.; Helton, Jon Craig; Vaughn, Palmer

    1999-01-01

    The Waste Isolation Pilot Plant (WIPP), which is located in southeastern New Mexico, is being developed for the geologic disposal of transuranic (TRU) waste by the U.S. Department of Energy (DOE). Waste disposal will take place in panels excavated in a bedded salt formation approximately 2000 ft (610 m) below the land surface. The BRAGFLO computer program which solves a system of nonlinear partial differential equations for two-phase flow, was used to investigate brine and gas flow patterns in the vicinity of the repository for the 1996 WIPP performance assessment (PA). The present study examines the implications of modeling assumptions used in conjunction with BRAGFLO in the 1996 WIPP PA that affect brine and gas flow patterns involving two waste regions in the repository (i.e., a single waste panel and the remaining nine waste panels), a disturbed rock zone (DRZ) that lies just above and below these two regions, and a borehole that penetrates the single waste panel and a brine pocket below this panel. The two waste regions are separated by a panel closure. The following insights were obtained from this study. First, the impediment to flow between the two waste regions provided by the panel closure model is reduced due to the permeable and areally extensive nature of the DRZ adopted in the 1996 WIPP PA, which results in the DRZ becoming an effective pathway for gas and brine movement around the panel closures and thus between the two waste regions. Brine and gas flow between the two waste regions via the DRZ causes pressures between the two to equilibrate rapidly, with the result that processes in the intruded waste panel are not isolated from the rest of the repository. Second, the connection between intruded and unintruded waste panels provided by the DRZ increases the time required for repository pressures to equilibrate with the overlying and/or underlying units subsequent to a drilling intrusion. Third, the large and areally extensive DRZ void volumes is a

  5. Brine and Gas Flow Patterns Between Excavated Areas and Disturbed Rock Zone in the 1996 Performance Assessment for the Waste Isolation Pilot Plant for a Single Drilling Intrusion that Penetrates Repository and Castile Brine Reservoir

    Energy Technology Data Exchange (ETDEWEB)

    ECONOMY,KATHLEEN M.; HELTON,JON CRAIG; VAUGHN,PALMER

    1999-10-01

    The Waste Isolation Pilot Plant (WIPP), which is located in southeastern New Mexico, is being developed for the geologic disposal of transuranic (TRU) waste by the U.S. Department of Energy (DOE). Waste disposal will take place in panels excavated in a bedded salt formation approximately 2000 ft (610 m) below the land surface. The BRAGFLO computer program which solves a system of nonlinear partial differential equations for two-phase flow, was used to investigate brine and gas flow patterns in the vicinity of the repository for the 1996 WIPP performance assessment (PA). The present study examines the implications of modeling assumptions used in conjunction with BRAGFLO in the 1996 WIPP PA that affect brine and gas flow patterns involving two waste regions in the repository (i.e., a single waste panel and the remaining nine waste panels), a disturbed rock zone (DRZ) that lies just above and below these two regions, and a borehole that penetrates the single waste panel and a brine pocket below this panel. The two waste regions are separated by a panel closure. The following insights were obtained from this study. First, the impediment to flow between the two waste regions provided by the panel closure model is reduced due to the permeable and areally extensive nature of the DRZ adopted in the 1996 WIPP PA, which results in the DRZ becoming an effective pathway for gas and brine movement around the panel closures and thus between the two waste regions. Brine and gas flow between the two waste regions via the DRZ causes pressures between the two to equilibrate rapidly, with the result that processes in the intruded waste panel are not isolated from the rest of the repository. Second, the connection between intruded and unintruded waste panels provided by the DRZ increases the time required for repository pressures to equilibrate with the overlying and/or underlying units subsequent to a drilling intrusion. Third, the large and areally extensive DRZ void volumes is a

  6. Pore-Scale Investigation on Stress-Dependent Characteristics of Granular Packs and Their Impact on Multiphase Fluid Distribution

    Science.gov (United States)

    Torrealba, V.; Karpyn, Z.; Yoon, H.; Hart, D. B.; Klise, K. A.

    2013-12-01

    The pore-scale dynamics that govern multiphase flow under variable stress conditions are not well understood. This lack of fundamental understanding limits our ability to quantitatively predict multiphase flow and fluid distributions in natural geologic systems. In this research, we focus on pore-scale, single and multiphase flow properties that impact displacement mechanisms and residual trapping of non-wetting phase under varying stress conditions. X-ray micro-tomography is used to image pore structures and distribution of wetting and non-wetting fluids in water-wet synthetic granular packs, under dynamic load. Micro-tomography images are also used to determine structural features such as medial axis, surface area, and pore body and throat distribution; while the corresponding transport properties are determined from Lattice-Boltzmann simulations performed on lattice replicas of the imaged specimens. Results are used to investigate how inter-granular deformation mechanisms affect fluid displacement and residual trapping at the pore-scale. This will improve our understanding of the dynamic interaction of mechanical deformation and fluid flow during enhanced oil recovery and geologic CO2 sequestration. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  7. The efficacy and safety of intense focused ultrasound in the treatment of enlarged facial pores in Asian skin.

    Science.gov (United States)

    Lee, Hee Jung; Lee, Kyung Real; Park, Jae Yang; Yoon, Moon Soo; Lee, Sang Eun

    2015-02-01

    Intense focused ultrasound (IFUS) has been used successfully for skin tightening. To investigate the efficacy of IFUS in treating enlarged pores and to evaluate changes in skin elasticity and sebum production following IFUS. Twenty-two subjects with enlarged pores were randomized to receive a single treatment with IFUS using 1.5-mm transducer on one side of the face, and 3.0-mm transducer on the other. OBJECTIVE clinical assessments were made by blinded photographic evaluation. Subjective satisfaction and adverse effects were evaluated. Measurements of elasticity and sebum were performed at baseline, 3 and 6 weeks post-treatment. Physicians' evaluation showed clinical pore improvements in 86% and 91% of the IFUS-treated sites using 1.5-mm and 3.0-mm transducer, respectively. The mean improvement scores were 1.7 and 1.9 for 1.5-mm and 3.0-mm transducer, respectively, with no statistical differences. Cutometer measurement demonstrated a significant improvement in skin elasticity. Sebum level showed a reduction without statistical significance. There was a positive correlation between improvement in elasticity and pore improvement grades. All treatments were well tolerated without significant side effects. IFUS using 1.5-mm or 3.0-mm transducer was safe and effective for reducing enlarged pores in Asian skin with an improvement in skin elasticity.

  8. Diffusion in the pore water of compacted crushed salt

    Energy Technology Data Exchange (ETDEWEB)

    Fluegge, Judith; Herr, Sebastian; Lauke, Thomas; Meleshyn, Artur; Miehe, Ruediger; Ruebel, Andre

    2016-07-15

    Diffusion of dissolved radionuclides in the pore water of compacted crushed salt in the long-term is the most relevant process for the release of radionuclides from a dedicated repository for high-level waste in a salt formation as has been shown in latest safety assessments and research projects /BUH 16/. So far, diffusion coefficients for free water have been applied for the diffusion in pore water in models for long-term safety assessments. This conservative assumption was used, because data on the diffusion coefficient of dissolved substances in crushed salt have been missing. Furthermore, the diffusion coefficient in the pore water was assumed to be constant and independent from the degree of compaction of the crushed salt. The work presented in this report was intended to contribute to fill this gap of knowledge about how the diffusion of radionuclides takes place in the compacted backfill of a repository in salt. For the first time, the pore diffusion coefficient as well as its dependence on the porosity of the crushed salt was determined experimentally by means of through-diffusion experiments using caesium as tracer. The results achieved in this project suggest that the diffusion in compacted crushed salt is not fully comparable to that in a homogeneous, temporally stable porous medium like sand or clay. The results obtained from four diffusion experiments show a remarkably different behaviour and all yield unique concentration versus time plots which includes highly temporal variable tracer fluxes with even full interruptions of the flux for longer periods of time. This effect cannot be explained by assuming a tracer transport by diffusion in a temporarily invariant pore space and / or under temporally invariant experimental conditions. From our point of view, a restructuring of the pore space seems to lead to closed areas of pore water in the sample which may open up again after some time, leading to a variable pore space and hence variable diffusive

  9. Pore Structure and Fractal Characteristics of Niutitang Shale from China

    Directory of Open Access Journals (Sweden)

    Zhaodong Xi

    2018-04-01

    Full Text Available A suite of shale samples from the Lower Cambrian Niutitang Formation in northwestern Hunan Province, China, were investigated to better understand the pore structure and fractal characteristics of marine shale. Organic geochemistry, mineralogy by X-ray diffraction, porosity, permeability, mercury intrusion and nitrogen adsorption and methane adsorption experiments were conducted for each sample. Fractal dimension D was obtained from the nitrogen adsorption data using the fractal Frenkel-Halsey-Hill (FHH model. The relationships between total organic carbon (TOC content, mineral compositions, pore structure parameters and fractal dimension are discussed, along with the contributions of fractal dimension to shale gas reservoir evaluation. Analysis of the results showed that Niutitang shale samples featured high TOC content (2.51% on average, high thermal maturity (3.0% on average, low permeability and complex pore structures, which are highly fractal. TOC content and mineral compositions are two major factors affecting pore structure but they have different impacts on the fractal dimension. Shale samples with higher TOC content had a larger specific surface area (SSA, pore volume (PV and fractal dimension, which enhanced the heterogeneity of the pore structure. Quartz content had a relatively weak influence on shale pore structure, whereas SSA, PV and fractal dimension decreased with increasing clay mineral content. Shale with a higher clay content weakened pore structure heterogeneity. The permeability and Langmuir volume of methane adsorption were affected by fractal dimension. Shale samples with higher fractal dimension had higher adsorption capacity but lower permeability, which is favorable for shale gas adsorption but adverse to shale gas seepage and diffusion.

  10. Direct Numerical Simulation of Low Capillary Number Pore Scale Flows

    Science.gov (United States)

    Esmaeilzadeh, S.; Soulaine, C.; Tchelepi, H.

    2017-12-01

    The arrangement of void spaces and the granular structure of a porous medium determines multiple macroscopic properties of the rock such as porosity, capillary pressure, and relative permeability. Therefore, it is important to study the microscopic structure of the reservoir pores and understand the dynamics of fluid displacements through them. One approach for doing this, is direct numerical simulation of pore-scale flow that requires a robust numerical tool for prediction of fluid dynamics and a detailed understanding of the physical processes occurring at the pore-scale. In pore scale flows with a low capillary number, Eulerian multiphase methods are well-known to produce additional vorticity close to the interface. This is mainly due to discretization errors which lead to an imbalance of capillary pressure and surface tension forces that causes unphysical spurious currents. At the pore scale, these spurious currents can become significantly stronger than the average velocity in the phases, and lead to unphysical displacement of the interface. In this work, we first investigate the capability of the algebraic Volume of Fluid (VOF) method in OpenFOAM for low capillary number pore scale flow simulations. Afterward, we compare VOF results with a Coupled Level-Set Volume of Fluid (CLSVOF) method and Iso-Advector method. It has been shown that the former one reduces the VOF's unphysical spurious currents in some cases, and both are known to capture interfaces sharper than VOF. As the conclusion, we will investigate that whether the use of CLSVOF or Iso-Advector will lead to less spurious velocities and more accurate results for capillary driven pore-scale multiphase flows or not. Keywords: Pore-scale multiphase flow, Capillary driven flows, Spurious currents, OpenFOAM

  11. Influence of pore structure and chemical properties of supported Mo catalysts on their performance in upgrading heavy coal liquids

    Energy Technology Data Exchange (ETDEWEB)

    Song, C.; Hanaoka, K.; Nomura, M. (Pennsylvania State University, University Park, PA (USA). Dept. of Materials Science and Engineering)

    In the hydroprocessing of solvent-refined coals, both the pore structure and the chemical properties of the catalysts affect the conversion of the heavy materials. Increasing median pore diameter (MPD) of unimodal Ni-Mo/Al[sub 2]O[sub 3] catalysts in the relatively small pore region (up to 150 [angstrom]) enhanced the conversion of both asphaltene and preasphaltene, but further increasing the MPD up to 730 [angstrom] mainly promoted preasphaltene conversion. In the runs of the isolated fractions, however, conversions increased with MPD up to 290 [angstrom] for asphaltene and up to 730 [angstrom] for preasphaltene. The degree of heteroatom removal is also influenced by MPD. There exist preferable pore size ranges for hydrodeoxygenation. Two Mo/SiO[sub 2] and several carbon-coated Ni-Mo/Al[sub 2]O[sub 3] catalysts with different MPD and a commercial Ni-Mo supported on silicated Al[sub 2]O[sub 3] were also compared. The increasing MPD of SiO[sub 2]-supported Mo catalysts increased the conversion of preasphaltene materials. Mo/SiO[sub 2] catalysts are more effective than Ni-Mo supported on Al[sub 2]O[sub 3] and silicated Al[sub 2]O[sub 3] for converting preasphaltene materials, while the latter two are more active for conversion of asphaltene into oil. Another interesting observation is that, for a given MPD range, the carbon-coated Ni-Mo/Al[sub 2]O[sub 3] catalysts gave higher preasphaltene conversions than fresh ones. These results point to the conclusion that larger pore and less acidic hydrogenation catalysts are more effective for preasphaltene conversion, but efficient conversion of asphaltene into oil is facilitated by mild hydrocracking catalysts having appropriate pore size ranges. 43 refs., 8 figs., 9 tabs.

  12. Interactions between bedforms, turbulence and pore flow

    Science.gov (United States)

    Blois, G.; Best, J.; Sambrook Smith, G.; Hardy, R. J.; Lead, J.

    2010-12-01

    A widespread occurrence of flow-form interaction in rivers is represented by subaqueous bedforms such as dunes. Many models have been proposed to explain how bedform generation and evolution are driven by turbulent flow structures that control the incipient motion of cohesionless sediments and later bedform development. However, most of these models have assumed such bedforms to be migrating over an impermeable bed, and that any surface-subsurface flow interaction is negligible. However, for some gravel-bed rivers the porosity can be high, up to 43%, which may result in significant flow both through the permeable bed (hyporheic flow) and across the surface-subsurface interface. The mass and momentum exchange occurring at the interface may have a strong impact on the structure of turbulent flow in the near-bed region. In the case of a dune, its topography induces a local pressure gradient that enhances flow across the interface. This results in a flow structure that may be radically different from that commonly proposed by past work. This paper presents results from a simplified laboratory model akin to a fine-grained bedform generated on top of a coarser sediment bed. Particle imaging velocimetry (PIV) measurements were conducted in order to characterise flow both over and underneath an idealised 2-dimensional dune (0.41 m long, 0.056 m high and having a leeside angle of 27°) overlaying a packed bed of uniform size spheres (D = 0.04 m diameter). Experiments were conducted in free surface flow conditions (Froude number = 0.1; Reynolds number = 25,000) for one bedform height: flow depth ratio (0.31). The flow above the dune was measured using a standard PIV technique while a novel endoscopic PIV (EPIV) system allowed collection of flow data within the pore spaces beneath the dune. The results show that topographically-induced subsurface flow significantly modifies the structure of flow in the leeside of the dune, resulting in a flow field that is radically different

  13. Physiologic upper limits of pore size of different blood capillary types and another perspective on the dual pore theory of microvascular permeability.

    Science.gov (United States)

    Sarin, Hemant

    2010-08-11

    Much of our current understanding of microvascular permeability is based on the findings of classic experimental studies of blood capillary permeability to various-sized lipid-insoluble endogenous and non-endogenous macromolecules. According to the classic small pore theory of microvascular permeability, which was formulated on the basis of the findings of studies on the transcapillary flow rates of various-sized systemically or regionally perfused endogenous macromolecules, transcapillary exchange across the capillary wall takes place through a single population of small pores that are approximately 6 nm in diameter; whereas, according to the dual pore theory of microvascular permeability, which was formulated on the basis of the findings of studies on the accumulation of various-sized systemically or regionally perfused non-endogenous macromolecules in the locoregional tissue lymphatic drainages, transcapillary exchange across the capillary wall also takes place through a separate population of large pores, or capillary leaks, that are between 24 and 60 nm in diameter. The classification of blood capillary types on the basis of differences in the physiologic upper limits of pore size to transvascular flow highlights the differences in the transcapillary exchange routes for the transvascular transport of endogenous and non-endogenous macromolecules across the capillary walls of different blood capillary types. The findings and published data of studies on capillary wall ultrastructure and capillary microvascular permeability to lipid-insoluble endogenous and non-endogenous molecules from the 1950s to date were reviewed. In this study, the blood capillary types in different tissues and organs were classified on the basis of the physiologic upper limits of pore size to the transvascular flow of lipid-insoluble molecules. Blood capillaries were classified as non-sinusoidal or sinusoidal on the basis of capillary wall basement membrane layer continuity or lack thereof

  14. Rock Physics of Reservoir Rocks with Varying Pore Water Saturation and Pore Water Salinity

    DEFF Research Database (Denmark)

    Katika, Konstantina

    experiments, the rock is subjected to high external stresses that resemble the reservoir stresses; 2) the fluid distribution within the pore space changes during the flow through experiments and wettability alterations may occur; 3) different ions, present in the salt water injected in the core, interact......Advanced waterflooding (injection of water with selective ions in reservoirs) is a method of enhanced oil recovery (EOR) that has attracted the interest of oil and gas companies that exploit the Danish oil and gas reservoirs. This method has been applied successfully in oil reservoirs...... and in the Smart Water project performed in a laboratory scale in order to evaluate the EOR processes in selected core plugs. A major step towards this evaluation is to identify the composition of the injected water that leads to increased oil recovery in reservoirs and to define changes in the petrophysical...

  15. Pore volume and pore size distribution of cement samples measured by a modified mercury intrusion porosimeter

    International Nuclear Information System (INIS)

    Zamorani, E.; Blanchard, H.

    1987-01-01

    Important parameters for the characterization of cement specimens are mechanical properties and porosity. This work is carried out at the Ispra Establishment of the Joint Research Centre in the scope of the Radioactive Waste Management programme. A commercial Mercury Intrusion Porosimeter was modified in an attempt to improve the performance of the instrument and to provide fast processing of the recorded values: pressure-volume of pores. The dead volume of the instrument was reduced and the possibility of leakage from the moving parts eliminated. In addition, the modification allows an improvement of data acquisition thus increasing data accuracy and reproducibility. In order to test the improved performance of the modified instrument, physical characterizations of cement forms were carried out. Experimental procedures and results are reported

  16. Final Report for Subcontract B541028,Pore-Scale Modeling to Support 'Pore Connectivity' Research Work

    International Nuclear Information System (INIS)

    Ewing, R.P.

    2008-01-01

    A central concept for the geological barrier at the proposed Yucca Mountain radioactive waste repository is diffusive retardation: solute moving through a fracture diffuses into and out of the rock matrix. This diffusive exchange retards overall solute movement, and retardation both dilutes waste being released, and allows additional decay. The original concept of diffusive retardation required knowledge only of the fracture conductivity and the matrix diffusion. But that simple concept is unavoidably complicated by other issues and processes: contaminants may sorb to the rock matrix, fracture flow may be episodic, a given fracture may or may not flow depending on the volume of flow and the fracture's connection to the overall fracture network, the matrix imbibes water during flow episodes and dries between episodes, and so on. Some of these issues have been examined by other projects. This particular project is motivated by a simple fact: Yucca Mountain tuff has low pore connectivity. This fact is not widely recognized, nor are its implications widely appreciated. Because low pore connectivity affects many processes, it may invalidate many assumptions that are basic (though perhaps not stated) to other investigations. The overall project's objective statement (from the proposal) was: This proposal aims to improve our understanding of diffusive retardation of radionuclides due to fracture/matrix interactions. Results from this combined experimental/modeling work will (1) determine whether the current understanding and model representation of matrix diffusion is valid, (2) provide insights into the upscaling of laboratory-scale diffusion experiments, and (3) evaluate the impact on diffusive retardation of episodic fracture flow and pore connectivity in Yucca Mountain tuffs. An obvious data gap addressed by the project was that there were only a few limited measurements of the diffusion coefficient of the rock at the repository level. That is, at the time we wrote

  17. Impact of Pore-Scale Wettability on Rhizosphere Rewetting

    Directory of Open Access Journals (Sweden)

    Pascal Benard

    2018-04-01

    Full Text Available Vast amounts of water flow through a thin layer of soil around the roots, the rhizosphere, where high microbial activity takes place—an important hydrological and biological hotspot. The rhizosphere was shown to turn water repellent upon drying, which has been interpreted as the effect of mucilage secreted by roots. The effects of such rhizosphere water dynamics on plant and microbial activity are unclear. Furthermore, our understanding of the biophysical mechanisms controlling the rhizosphere water repellency remains largely speculative. Our hypothesis is that the key to describe the emergence of water repellency lies within the microscopic distribution of wettability on the pore-scale. At a critical mucilage content, a sufficient fraction of pores is blocked and the rhizosphere turns water repellent. Here we tested whether a percolation approach is capable to predict the flow behavior near the critical mucilage content. The wettability of glass beads and sand mixed with chia seed mucilage was quantified by measuring the infiltration rate of water drops. Drop infiltration was simulated using a simple pore-network model in which mucilage was distributed heterogeneously throughout the pore space with a preference for small pores. The model approach proved capable to capture the percolation nature of the process, the sudden transition from wettable to water repellent and the high variability in infiltration rates near the percolation threshold. Our study highlights the importance of pore-scale distribution of mucilage in the emergent flow behavior across the rhizosphere.

  18. Pore Scale Analysis of Oil Shale/Sands Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chen-Luh [Univ. of Utah, Salt Lake City, UT (United States); Miller, Jan [Univ. of Utah, Salt Lake City, UT (United States)

    2011-03-01

    There are important questions concerning the quality and volume of pore space that is created when oil shale is pyrolyzed for the purpose of producing shale oil. In this report, 1.9 cm diameter cores of Mahogany oil shale were pyrolyzed at different temperatures and heating rates. Detailed 3D imaging of core samples was done using multiscale X-ray computed tomography (CT) before and after pyrolysis to establish the pore structure. The pore structure of the unreacted material was not clear. Selected images of a core pyrolyzed at 400oC were obtained at voxel resolutions from 39 microns (Οm) to 60 nanometers (nm). Some of the pore space created during pyrolysis was clearly visible at these resolutions and it was possible to distinguish between the reaction products and the host shale rock. The pore structure deduced from the images was used in Lattice Boltzmann simulations to calculate the permeability in the pore space. The permeabilities of the pyrolyzed samples of the silicate-rich zone were on the order of millidarcies, while the permeabilities of the kerogen-rich zone after pyrolysis were very anisotropic and about four orders of magnitude higher.

  19. Pore growth in U-Mo/Al dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeon Soo, E-mail: yskim@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Jeong, G.Y.; Sohn, D.-S. [Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Jamison, L.M. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2016-09-15

    U-Mo/Al dispersion fuel is currently under development in the DOE’s Material Management and Minimization program to convert HEU-fueled research reactors to LEU-fueled reactors. In some demanding conditions in high-power and high-performance reactors, large pores form in the interaction layers between the U-Mo fuel particles and the Al matrix, which pose a potential to cause fuel failure. In this study, comprehension of the formation and growth of these pores was explored. As a product, a model to predict pore growth and porosity increase was developed. The model includes three major topics: fission gas release from the U-Mo and the IL to the pores, stress evolution in the fuel meat, and the effect of amorphous IL growth. Well-characterized in-pile data from reduced-size plates were used to fit the model parameters. A data set from full-sized plates, independent and distinctively different from those used to fit the model parameters, was used to examine the accuracy of the model. The model showed fair agreement with the measured data. The model suggested that the growth of the IL has a critical effect on pore growth, as both its material properties and energetics are favorable to pore formation. Therefore, one area of the current effort, focused on suppressing IL growth, appears to be on the right track to improve the performance of this fuel.

  20. Software Image J to study soil pore distribution

    Directory of Open Access Journals (Sweden)

    Sabrina Passoni

    2014-04-01

    Full Text Available In the soil science, a direct method that allows the study of soil pore distribution is the bi-dimensional (2D digital image analysis. Such technique provides quantitative results of soil pore shape, number and size. The use of specific softwares for the treatment and processing of images allows a fast and efficient method to quantify the soil porous system. However, due to the high cost of commercial softwares, public ones can be an interesting alternative for soil structure analysis. The objective of this work was to evaluate the quality of data provided by the Image J software (public domain used to characterize the voids of two soils, characterized as Geric Ferralsol and Rhodic Ferralsol, from the southeast region of Brazil. The pore distribution analysis technique from impregnated soil blocks was utilized for this purpose. The 2D image acquisition was carried out by using a CCD camera coupled to a conventional optical microscope. After acquisition and treatment of images, they were processed and analyzed by the software Noesis Visilog 5.4® (chosen as the reference program and ImageJ. The parameters chosen to characterize the soil voids were: shape, number and pore size distribution. For both soils, the results obtained for the image total porosity (%, the total number of pores and the pore size distribution showed that the Image J is a suitable software to be applied in the characterization of the soil sample voids impregnated with resin.

  1. Pore opening dynamics in the exocytosis of serotonin

    Science.gov (United States)

    Ramirez-Santiago, Guillermo; Cercos, Montserrat G.; Martinez-Valencia, Alejandro; Salinas Hernandez, Israel; Rodríguez-Sosa, Leonardo; de-Miguel, Francisco F.

    2015-03-01

    The current view of the exocytosis of transmitter molecules is that it starts with the formation of a fusion pore that connects the intravesicular and the extracellular spaces, and is completed by the release of the rest of the transmitter contained in the vesicle upon the full fusion and collapse of the vesicle with the plasma membrane. However, under certain circumstances, a rapid closure of the pore before the full vesicle fusion produces only a partial release of the transmitter. Here we show that whole release of the transmitter occurs through fusion pores that remain opened for tens of milliseconds without vesicle collapse. This was demonstrated through amperometric measurements of serotonin release from electrodense vesicles in the axon of leech Retzius neurons and mathematical modelling. By modeling transmitter release with a diffusion equation subjected to boundary conditions that are defined by the experiment, we showed that those pores with a fast half rise time constant remained opened and allowed the full quantum release without vesicle collapse, whereas pores with a slow rise time constant closed rapidly, thus producing partial release. We conclude that a full transmitter release may occur through the fusion pore in the absence of vesicle collapse. This work was founded by a DGAPA-UNAM grants IN200914 and IN118410 CONACYT GRANT 130031, and CONACyT doctoral fellowships.

  2. Characterizing cellular mechanical phenotypes with mechano-node-pore sensing

    Science.gov (United States)

    Kim, Junghyun; Han, Sewoon; Lei, Andy; Miyano, Masaru; Bloom, Jessica; Srivastava, Vasudha; Stampfer, Martha M.; Gartner, Zev J.; LaBarge, Mark A.; Sohn, Lydia L.

    2018-01-01

    The mechanical properties of cells change with their differentiation, chronological age, and malignant progression. Consequently, these properties may be useful label-free biomarkers of various functional or clinically relevant cell states. Here, we demonstrate mechano-node-pore sensing (mechano-NPS), a multi-parametric single-cell-analysis method that utilizes a four-terminal measurement of the current across a microfluidic channel to quantify simultaneously cell diameter, resistance to compressive deformation, transverse deformation under constant strain, and recovery time after deformation. We define a new parameter, the whole-cell deformability index (wCDI), which provides a quantitative mechanical metric of the resistance to compressive deformation that can be used to discriminate among different cell types. The wCDI and the transverse deformation under constant strain show malignant MCF-7 and A549 cell lines are mechanically distinct from non-malignant, MCF-10A and BEAS-2B cell lines, and distinguishes between cells treated or untreated with cytoskeleton-perturbing small molecules. We categorize cell recovery time, ΔTr, as instantaneous (ΔTr ~ 0 ms), transient (ΔTr ≤ 40ms), or prolonged (ΔTr > 40ms), and show that the composition of recovery types, which is a consequence of changes in cytoskeletal organization, correlates with cellular transformation. Through the wCDI and cell-recovery time, mechano-NPS discriminates between sub-lineages of normal primary human mammary epithelial cells with accuracy comparable to flow cytometry, but without antibody labeling. Mechano-NPS identifies mechanical phenotypes that distinguishes lineage, chronological age, and stage of malignant progression in human epithelial cells. PMID:29780657

  3. PBO Borehole Strainmeters and Pore Pressure Sensors: Recording Hydrological Strain Signals

    Science.gov (United States)

    Gottlieb, M. H.; Hodgkinson, K. M.; Mencin, D.; Henderson, D. B.; Johnson, W.; Van Boskirk, E.; Pyatt, C.; Mattioli, G. S.

    2017-12-01

    UNAVCO operates a network of 75 borehole strainmeters along the west coast of the United States and Vancouver Island, Canada as part of the Plate Boundary Observatory (PBO), the geodetic component of the NSF-funded Earthscope program. Borehole strainmeters are designed to detect variations in the strain field at the nanostrain level and can easily detect transient strains caused by aseismic creep events, Episodic Tremor and Slip (ETS) events and seismically induced co- and post-seimic signals. In 2016, one strainmeter was installed in an Oklahoma oil field to characterize in-situ deformation during CO2 injection. Twenty-three strainmeter sites also have pore pressure sensors to measure fluctuations in groundwater pressure. Both the strainmeter network and the pore pressure sensors provide unique data against which those using water-level measurements, GPS time-series or InSAR data can compare possible subsidence signals caused by groundwater withdrawal or fluid re-injection. Operating for 12 years, the PBO strainmeter and pore pressure network provides a long-term, continuous, 1-sps record of deformation. PBO deploys GTSM21 tensor strainmeters from GTSM Technologies, which consist of four horizontal strain gauges stacked vertically, at different orientations, within a single 2 m-long instrument. The strainmeters are typically installed at depths of 200 to 250 m and grouted into the bottom of 15 cm diameter boreholes. The pore pressure sensors are Digiquartz Depth Sensors from Paros Scientific. These sensors are installed in 2" PVC, sampling groundwater through a screened section 15 m above the co-located strainmeter. These sensors are also recording at 1-sps with a resolution in the hundredths of hPa. High-rate local barometric pressure data and low-rate rainfall data also available at all locations. PBO Strainmeter and pore pressure data are available in SEED, SAC-ASCII and time-stamped ASCII format from the IRIS Data Managements Center. Strainmeter data are

  4. Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores.

    Science.gov (United States)

    Morishige, Kunimitsu; Tateishi, Masayoshi

    2006-04-25

    To examine the theoretical and semiempirical relations between pore size and the pressure of capillary condensation or evaporation proposed so far, we constructed an accurate relation between the pore radius and the capillary condensation and evaporation pressure of nitrogen at 77 K for the cylindrical pores of the ordered mesoporous MCM-41 and SBA-15 silicas. Here, the pore size was determined from a comparison between the experimental and calculated X-ray diffraction patterns due to X-ray structural modeling recently developed. Among the many theoretical relations that differ from each other in the degree of theoretical improvements, a macroscopic thermodynamic approach based on Broekhoff-de Boer equations was found to be in fair agreement with the experimental relation obtained in the present study.

  5. Two-Step Mechanism of Membrane Disruption by Aβ through Membrane Fragmentation and Pore Formation

    Science.gov (United States)

    Sciacca, Michele F.M.; Kotler, Samuel A.; Brender, Jeffrey R.; Chen, Jennifer; Lee, Dong-kuk; Ramamoorthy, Ayyalusamy

    2012-01-01

    Disruption of cell membranes by Aβ is believed to be one of the key components of Aβ toxicity. However, the mechanism by which this occurs is not fully understood. Here, we demonstrate that membrane disruption by Aβ occurs by a two-step process, with the initial formation of ion-selective pores followed by nonspecific fragmentation of the lipid membrane during amyloid fiber formation. Immediately after the addition of freshly dissolved Aβ1–40, defects form on the membrane that share many of the properties of Aβ channels originally reported from single-channel electrical recording, such as cation selectivity and the ability to be blockaded by zinc. By contrast, subsequent amyloid fiber formation on the surface of the membrane fragments the membrane in a way that is not cation selective and cannot be stopped by zinc ions. Moreover, we observed that the presence of ganglioside enhances both the initial pore formation and the fiber-dependent membrane fragmentation process. Whereas pore formation by freshly dissolved Aβ1–40 is weakly observed in the absence of gangliosides, fiber-dependent membrane fragmentation can only be observed in their presence. These results provide insights into the toxicity of Aβ and may aid in the design of specific compounds to alleviate the neurodegeneration of Alzheimer’s disease. PMID:22947931

  6. The Pore-scale modeling of multiphase flows in reservoir rocks using the lattice Boltzmann method

    Science.gov (United States)

    Mu, Y.; Baldwin, C. H.; Toelke, J.; Grader, A.

    2011-12-01

    Digital rock physics (DRP) is a new technology to compute the physical and fluid flow properties of reservoir rocks. In this approach, pore scale images of the porous rock are obtained and processed to create highly accurate 3D digital rock sample, and then the rock properties are evaluated by advanced numerical methods at the pore scale. Ingrain's DRP technology is a breakthrough for oil and gas companies that need large volumes of accurate results faster than the current special core analysis (SCAL) laboratories can normally deliver. In this work, we compute the multiphase fluid flow properties of 3D digital rocks using D3Q19 immiscible LBM with two relaxation times (TRT). For efficient implementation on GPU, we improved and reformulated color-gradient model proposed by Gunstensen and Rothmann. Furthermore, we only use one-lattice with the sparse data structure: only allocate memory for pore nodes on GPU. We achieved more than 100 million fluid lattice updates per second (MFLUPS) for two-phase LBM on single Fermi-GPU and high parallel efficiency on Multi-GPUs. We present and discuss our simulation results of important two-phase fluid flow properties, such as capillary pressure and relative permeabilities. We also investigate the effects of resolution and wettability on multiphase flows. Comparison of direct measurement results with the LBM-based simulations shows practical ability of DRP to predict two-phase flow properties of reservoir rock.

  7. An inverse-source problem for maximization of pore-fluid oscillation within poroelastic formations

    KAUST Repository

    Jeong, C.; Kallivokas, L. F.

    2016-01-01

    This paper discusses a mathematical and numerical modeling approach for identification of an unknown optimal loading time signal of a wave source, atop the ground surface, that can maximize the relative wave motion of a single-phase pore fluid within fluid-saturated porous permeable (poroelastic) rock formations, surrounded by non-permeable semi-infinite elastic solid rock formations, in a one-dimensional setting. The motivation stems from a set of field observations, following seismic events and vibrational tests, suggesting that shaking an oil reservoir is likely to improve oil production rates. This maximization problem is cast into an inverse-source problem, seeking an optimal loading signal that minimizes an objective functional – the reciprocal of kinetic energy in terms of relative pore-fluid wave motion within target poroelastic layers. We use the finite element method to obtain the solution of the governing wave physics of a multi-layered system, where the wave equations for the target poroelastic layers and the elastic wave equation for the surrounding non-permeable layers are coupled with each other. We use a partial-differential-equation-constrained-optimization framework (a state-adjoint-control problem approach) to tackle the minimization problem. The numerical results show that the numerical optimizer recovers optimal loading signals, whose dominant frequencies correspond to amplification frequencies, which can also be obtained by a frequency sweep, leading to larger amplitudes of relative pore-fluid wave motion within the target hydrocarbon formation than other signals.

  8. Pilot Study of Topical Copper Chlorophyllin Complex in Subjects With Facial Acne and Large Pores.

    Science.gov (United States)

    Stephens, Thomas J; McCook, John P; Herndon, James H

    2015-06-01

    Acne vulgaris is one of the most common skin diseases treated by dermatologists. Salts of copper chlorophyllin complex are semi-synthetic naturally-derived compounds with antioxidant, anti-inflammatory and wound healing activity that have not been previously tested topically in the treatment of acne-prone skin with enlarged pores. This single-center pilot study was conducted to assess the efficacy and safety of a liposomal dispersion of topically applied sodium copper chlorophyllin complex in subjects with mild-moderate acne and large, visible pores over a course of 3 weeks. Subjects were supplied with the test product, a topical gel containing a liposomal dispersion of sodium copper chlorophyllin complex (0.1%) with directions to apply a small amount to the facial area twice daily. Clinical assessments were performed at screening/baseline and at week 3. VISIA readings were taken and self-assessment questionnaires were conducted. 10 subjects were enrolled and completed the 3-week study. All clinical efficacy parameters showed statistically significant improvements over baseline at week 3. The study product was well tolerated. Subject questionnaires showed the test product was highly rated. In this pilot study, a topical formulation containing a liposomal dispersion of sodium copper chlorophyllin complex was shown to be clinically effective and well tolerated for the treatment of mild-moderate acne and large, visible pores when used for 3 weeks.

  9. An inverse-source problem for maximization of pore-fluid oscillation within poroelastic formations

    KAUST Repository

    Jeong, C.

    2016-07-04

    This paper discusses a mathematical and numerical modeling approach for identification of an unknown optimal loading time signal of a wave source, atop the ground surface, that can maximize the relative wave motion of a single-phase pore fluid within fluid-saturated porous permeable (poroelastic) rock formations, surrounded by non-permeable semi-infinite elastic solid rock formations, in a one-dimensional setting. The motivation stems from a set of field observations, following seismic events and vibrational tests, suggesting that shaking an oil reservoir is likely to improve oil production rates. This maximization problem is cast into an inverse-source problem, seeking an optimal loading signal that minimizes an objective functional – the reciprocal of kinetic energy in terms of relative pore-fluid wave motion within target poroelastic layers. We use the finite element method to obtain the solution of the governing wave physics of a multi-layered system, where the wave equations for the target poroelastic layers and the elastic wave equation for the surrounding non-permeable layers are coupled with each other. We use a partial-differential-equation-constrained-optimization framework (a state-adjoint-control problem approach) to tackle the minimization problem. The numerical results show that the numerical optimizer recovers optimal loading signals, whose dominant frequencies correspond to amplification frequencies, which can also be obtained by a frequency sweep, leading to larger amplitudes of relative pore-fluid wave motion within the target hydrocarbon formation than other signals.

  10. Piezo proteins are pore-forming subunits of mechanically activated channels.

    Science.gov (United States)

    Coste, Bertrand; Xiao, Bailong; Santos, Jose S; Syeda, Ruhma; Grandl, Jörg; Spencer, Kathryn S; Kim, Sung Eun; Schmidt, Manuela; Mathur, Jayanti; Dubin, Adrienne E; Montal, Mauricio; Patapoutian, Ardem

    2012-02-19

    Mechanotransduction has an important role in physiology. Biological processes including sensing touch and sound waves require as-yet-unidentified cation channels that detect pressure. Mouse Piezo1 (MmPiezo1) and MmPiezo2 (also called Fam38a and Fam38b, respectively) induce mechanically activated cationic currents in cells; however, it is unknown whether Piezo proteins are pore-forming ion channels or modulate ion channels. Here we show that Drosophila melanogaster Piezo (DmPiezo, also called CG8486) also induces mechanically activated currents in cells, but through channels with remarkably distinct pore properties including sensitivity to the pore blocker ruthenium red and single channel conductances. MmPiezo1 assembles as a ∼1.2-million-dalton homo-oligomer, with no evidence of other proteins in this complex. Purified MmPiezo1 reconstituted into asymmetric lipid bilayers and liposomes forms ruthenium-red-sensitive ion channels. These data demonstrate that Piezo proteins are an evolutionarily conserved ion channel family involved in mechanotransduction.

  11. The effect of physically applied alpha hydroxyl acids on the skin pore and comedone.

    Science.gov (United States)

    Kim, S J; Baek, J H; Koh, J S; Bae, M I; Lee, S J; Shin, M K

    2015-10-01

    Alpha hydroxy acids (AHA) have been recognized as commonly used therapy for acne. Our studies examined whether an additional effect of physical treatment using chemical peeling combined with negative pressure and compared with AHA treatment only occurs in acne-prone subjects. The chemical peeling agent used 4% of an AHA solution (mixture of 1000 mL of carbonated water, 20 mL of glycolic acid and 20 mL of lactic acid). All subjects' faces were randomly divided into test and control groups. The test group was treated with chemical peeling combined with a physical effect, and the control group applied chemical peeling alone. For the 23 healthy females (average age: 30.17 ± 5.06 year), we measured sebum output level by light transmission, pore area and number by optical image analyser, and comedone counting before treatment and at 1, 2 and 4 weeks after a single treatment. Compared to the before treatment, whiteheads and blackheads were significantly decreased at 1, 2 and 4 weeks in the test group (P Pore area and number significantly decreased at 1 week (P pore size and seborrhoea. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  12. Effect of sub-pore scale morphology of biological deposits on porous media flow properties

    Science.gov (United States)

    Ghezzehei, T. A.

    2012-12-01

    Biological deposits often influence fluid flow by altering the pore space morphology and related hydrologic properties such as porosity, water retention characteristics, and permeability. In most coupled-processes models changes in porosity are inferred from biological process models using mass-balance. The corresponding evolution of permeability is estimated using (semi-) empirical porosity-permeability functions such as the Kozeny-Carman equation or power-law functions. These equations typically do not account for the heterogeneous spatial distribution and morphological irregularities of the deposits. As a result, predictions of permeability evolution are generally unsatisfactory. In this presentation, we demonstrate the significance of pore-scale deposit distribution on porosity-permeability relations using high resolution simulations of fluid flow through a single pore interspersed with deposits of varying morphologies. Based on these simulations, we present a modification to the Kozeny-Carman model that accounts for the shape of the deposits. Limited comparison with published experimental data suggests the plausibility of the proposed conceptual model.

  13. Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

    Science.gov (United States)

    Torstrick, F Brennan; Evans, Nathan T; Stevens, Hazel Y; Gall, Ken; Guldberg, Robert E

    2016-11-01

    Despite its widespread use in orthopaedic implants such as soft tissue fasteners and spinal intervertebral implants, polyetheretherketone (PEEK) often suffers from poor osseointegration. Introducing porosity can overcome this limitation by encouraging bone ingrowth; however, the corresponding decrease in implant strength can potentially reduce the implant's ability to bear physiologic loads. We have previously shown, using a single pore size, that limiting porosity to the surface of PEEK implants preserves strength while supporting in vivo osseointegration. However, additional work is needed to investigate the effect of pore size on both the mechanical properties and cellular response to PEEK. (1) Can surface porous PEEK (PEEK-SP) microstructure be reliably controlled? (2) What is the effect of pore size on the mechanical properties of PEEK-SP? (3) Do surface porosity and pore size influence the cellular response to PEEK? PEEK-SP was created by extruding PEEK through NaCl crystals of three controlled ranges: 200 to 312, 312 to 425, and 425 to 508 µm. Micro-CT was used to characterize the microstructure of PEEK-SP. Tensile, fatigue, and interfacial shear tests were performed to compare the mechanical properties of PEEK-SP with injection-molded PEEK (PEEK-IM). The cellular response to PEEK-SP, assessed by proliferation, alkaline phosphatase activity, vascular endothelial growth factor production, and calcium content of osteoblast, mesenchymal stem cell, and preosteoblast (MC3T3-E1) cultures, was compared with that of machined smooth PEEK and Ti6Al4V. Micro-CT analysis showed that PEEK-SP layers possessed pores that were 284 ± 35 µm, 341 ± 49 µm, and 416 ± 54 µm for each pore size group. Porosity and pore layer depth ranged from 61% to 69% and 303 to 391 µm, respectively. Mechanical testing revealed tensile strengths > 67 MPa and interfacial shear strengths > 20 MPa for all three pore size groups. All PEEK-SP groups exhibited > 50% decrease

  14. Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 1 of 3: Main report, appendix A

    Energy Technology Data Exchange (ETDEWEB)

    Howarth, S.M.; Christian-Frear, T.

    1997-08-01

    Three groups of core samples from Marker Bed 139 of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) were analyzed to provide data to support the development of numerical models used to predict the long-term hydrologic and structural response of the WIPP repository. These laboratory experiments, part of the FY93 Experimental Scoping Activities of the Salado Two-Phase Flow Laboratory Program, were designed to (1) generate WIPP-specific porosity and single-phase permeability data, (2) provide information needed to design and implement planned tests to measure two-phase flow properties, including threshold pressure, capillary pressure, and relative permeability, and (3) evaluate the suitability of using analog correlations for the Salado Formation to assess the long-term performance of the WIPP. This report contains a description of the boreholes core samples, the core preparation techniques used, sample sizes, testing procedures, test conditions, and results of porosity and single-phase permeability tests performed at three laboratories: TerraTek, Inc. (Salt Lake City, UT), RE/SPEC, Inc. (Rapid City, SD), and Core Laboratories-Special Core Analysis Laboratory (Carrollton, TX) for Rock Physics Associates. In addition, this report contains the only WIPP-specific two-phase-flow capillary-pressure data for twelve core samples. The WIPP-specific data generated in this laboratory study and in WIPP field-test programs and information from suitable analogs will form the basis for specification of single- and two-phase flow parameters for anhydrite markers beds for WIPP performance assessment calculations.

  15. Porosity, single-phase permeability, and capillary pressure data from preliminary laboratory experiments on selected samples from Marker Bed 139 at the Waste Isolation Pilot Plant. Volume 1 of 3: Main report, appendix A

    International Nuclear Information System (INIS)

    Howarth, S.M.; Christian-Frear, T.

    1997-08-01

    Three groups of core samples from Marker Bed 139 of the Salado Formation at the Waste Isolation Pilot Plant (WIPP) were analyzed to provide data to support the development of numerical models used to predict the long-term hydrologic and structural response of the WIPP repository. These laboratory experiments, part of the FY93 Experimental Scoping Activities of the Salado Two-Phase Flow Laboratory Program, were designed to (1) generate WIPP-specific porosity and single-phase permeability data, (2) provide information needed to design and implement planned tests to measure two-phase flow properties, including threshold pressure, capillary pressure, and relative permeability, and (3) evaluate the suitability of using analog correlations for the Salado Formation to assess the long-term performance of the WIPP. This report contains a description of the boreholes core samples, the core preparation techniques used, sample sizes, testing procedures, test conditions, and results of porosity and single-phase permeability tests performed at three laboratories: TerraTek, Inc. (Salt Lake City, UT), RE/SPEC, Inc. (Rapid City, SD), and Core Laboratories-Special Core Analysis Laboratory (Carrollton, TX) for Rock Physics Associates. In addition, this report contains the only WIPP-specific two-phase-flow capillary-pressure data for twelve core samples. The WIPP-specific data generated in this laboratory study and in WIPP field-test programs and information from suitable analogs will form the basis for specification of single- and two-phase flow parameters for anhydrite markers beds for WIPP performance assessment calculations

  16. Confinement stabilises single crystal vaterite rods.

    OpenAIRE

    Schenk, AS; Albarracin, EJ; Kim, YY; Ihli, J; Meldrum, FC

    2014-01-01

    Single-crystals of vaterite, the least-stable anhydrous polymorph of CaCO3, are rare in biogenic and synthetic systems. We here describe the synthesis of high aspect ratio single crystal vaterite rods under additive-free conditions by precipitating CaCO3 within the cylindrical pores of track-etch membranes.

  17. MD simulation of organics adsorption from aqueous solution in carbon slit-like pores. Foundations of the pore blocking effect

    International Nuclear Information System (INIS)

    Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester; Zieliński, Wojciech; Włoch, Jerzy; Kowalczyk, Piotr

    2014-01-01

    The results of systematic studies of organics adsorption from aqueous solutions (at the neutral pH level) in a system of slit-like carbon pores having different sizes and oxygen groups located at the pore mouth are reported. Using molecular dynamics simulations (GROMACS package) the properties of adsorbent–adsorbate (benzene, phenol or paracetamol) as well as adsorbent–water systems are discussed. After the introduction of surface oxygen functionalities, adsorption of organic compounds decreases (in accordance with experimental data) and this is caused by the accumulation of water molecules at pore entrances. The pore blocking effect decreases with the diameter of slits and practically vanishes for widths larger than approx. 0.68 nm. We observed the increase in phenol adsorption with the rise in temperature. Moreover, adsorbed molecules occupy the external surface of the slit pores (the entrances) in the case of oxidized adsorbents. Among the studied molecules benzene, phenol and paracetamol prefer an almost flat orientation and with the rise in the pore width the number of molecules oriented in parallel decreases. The decrease or increase in temperature (with respect to 298 K) leads to insignificant changes of angular orientation of adsorbed molecules. (paper)

  18. dPORE-miRNA: Polymorphic regulation of microRNA genes

    KAUST Repository

    Schmeier, Sebastian

    2011-02-04

    Background: MicroRNAs (miRNAs) are short non-coding RNA molecules that act as post-transcriptional regulators and affect the regulation of protein-coding genes. Mostly transcribed by PolII, miRNA genes are regulated at the transcriptional level similarly to protein-coding genes. In this study we focus on human miRNAs. These miRNAs are involved in a variety of pathways and can affect many diseases. Our interest is on possible deregulation of the transcription initiation of the miRNA encoding genes, which is facilitated by variations in the genomic sequence of transcriptional control regions (promoters). Methodology: Our aim is to provide an online resource to facilitate the investigation of the potential effects of single nucleotide polymorphisms (SNPs) on miRNA gene regulation. We analyzed SNPs overlapped with predicted transcription factor binding sites (TFBSs) in promoters of miRNA genes. We also accounted for the creation of novel TFBSs due to polymorphisms not present in the reference genome. The resulting changes in the original TFBSs and potential creation of new TFBSs were incorporated into the Dragon Database of Polymorphic Regulation of miRNA genes (dPORE-miRNA). Conclusions: The dPORE-miRNA database enables researchers to explore potential effects of SNPs on the regulation of miRNAs. dPORE-miRNA can be interrogated with regards to: a/miRNAs (their targets, or involvement in diseases, or biological pathways), b/SNPs, or c/transcription factors. dPORE-miRNA can be accessed at http://cbrc.kaust.edu.sa/dpore and http://apps.sanbi.ac.za/dpore/. Its use is free for academic and non-profit users. © 2011 Schmeier et al.

  19. dPORE-miRNA: Polymorphic regulation of microRNA genes

    KAUST Repository

    Schmeier, Sebastian; Schaefer, Ulf; MacPherson, Cameron R.; Bajic, Vladimir B.

    2011-01-01

    Background: MicroRNAs (miRNAs) are short non-coding RNA molecules that act as post-transcriptional regulators and affect the regulation of protein-coding genes. Mostly transcribed by PolII, miRNA genes are regulated at the transcriptional level similarly to protein-coding genes. In this study we focus on human miRNAs. These miRNAs are involved in a variety of pathways and can affect many diseases. Our interest is on possible deregulation of the transcription initiation of the miRNA encoding genes, which is facilitated by variations in the genomic sequence of transcriptional control regions (promoters). Methodology: Our aim is to provide an online resource to facilitate the investigation of the potential effects of single nucleotide polymorphisms (SNPs) on miRNA gene regulation. We analyzed SNPs overlapped with predicted transcription factor binding sites (TFBSs) in promoters of miRNA genes. We also accounted for the creation of novel TFBSs due to polymorphisms not present in the reference genome. The resulting changes in the original TFBSs and potential creation of new TFBSs were incorporated into the Dragon Database of Polymorphic Regulation of miRNA genes (dPORE-miRNA). Conclusions: The dPORE-miRNA database enables researchers to explore potential effects of SNPs on the regulation of miRNAs. dPORE-miRNA can be interrogated with regards to: a/miRNAs (their targets, or involvement in diseases, or biological pathways), b/SNPs, or c/transcription factors. dPORE-miRNA can be accessed at http://cbrc.kaust.edu.sa/dpore and http://apps.sanbi.ac.za/dpore/. Its use is free for academic and non-profit users. © 2011 Schmeier et al.

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

    Science.gov (United States)

    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.

  1. A statistical model for the wettability of surfaces with heterogeneous pore geometries

    Science.gov (United States)

    Brockway, Lance; Taylor, Hayden

    2016-10-01

    We describe a new approach to modeling the wetting behavior of micro- and nano-textured surfaces with varying degrees of geometrical heterogeneity. Surfaces are modeled as pore arrays with a Gaussian distribution of sidewall reentrant angles and a characteristic wall roughness. Unlike conventional wettability models, our model considers the fraction of a surface’s pores that are filled at any time, allowing us to capture more subtle dependences of a liquid’s apparent contact angle on its surface tension. The model has four fitting parameters and is calibrated for a particular surface by measuring the apparent contact angles between the surface and at least four probe liquids. We have calibrated the model for three heterogeneous nanoporous surfaces that we have fabricated: a hydrothermally grown zinc oxide, a film of polyvinylidene fluoride (PVDF) microspheres formed by spinodal decomposition, and a polytetrafluoroethylene (PTFE) film with pores defined by sacrificial polystyrene microspheres. These three surfaces show markedly different dependences of a liquid’s apparent contact angle on the liquid’s surface tension, and the results can be explained by considering geometric variability. The highly variable PTFE pores yield the most gradual variation of apparent contact angle with probe liquid surface tension. The PVDF microspheres are more regular in diameter and, although connected in an irregular manner, result in a much sharper transition from non-wetting to wetting behavior as surface tension reduces. We also demonstrate, by terminating porous zinc oxide with three alternative hydrophobic molecules, that a single geometrical model can capture a structure’s wetting behavior for multiple surface chemistries and liquids. Finally, we contrast our results with those from a highly regular, lithographically-produced structure which shows an extremely sharp dependence of wettability on surface tension. This new model could be valuable in designing and

  2. Development of a toxicity-based fractionation approach for the identification of phototoxic PAHs in pore water

    International Nuclear Information System (INIS)

    Kosian, P.A.; Makynen, E.A.; Ankley, G.T.; Monson, P.D.

    1995-01-01

    Environmental matrices often contain complex mixtures of chemical compounds, however, typically only a few chemicals are responsible for observed toxicity. To determine those chemicals responsible for toxicity, a toxicity-based fractionation technique coupled with gas chromatography/mass spectrometry (GC/MS) has been used for the isolation and identification of nonpolar toxicants in aqueous samples. In this study, this technique was modified to separate and identify polycyclic aromatic hydrocarbons (PAHs) responsible for phototoxicity in pore water. Whole pore water, obtained from sediments collected near an oil refinery discharge site, was found to be toxic to Lumbriculus variegatus in the presence of ultraviolet (UV) light. Solid phase extraction disks and high pressure liquid chromatography were used, in conjunction with toxicity tests with L. variegatus, to extract and fractionate phototoxic chemicals from the pore water. GC/MS analysis was performed on the toxic fractions and a tentative list of compound identifications were made based on interpretation of mass spectra and elution information from the chromatographic separation. The compounds identified include PAHs and substituted PAHs that are known or predicted to be phototoxic in the presence of UV light. The results show that a modified toxicity-based fractionation approach can be successfully applied to identify phototoxic PAHs in sediment pore water and therefore used in the assessment of contaminated sediments

  3. Synthesis of Novel Mesoporous Silica Materials with Hierarchical Pore Structures

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Bon; Choi, Wang Kyu; Choi, Byung Seon; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Porous materials with various pore sizes in the range of micropore (< 2 nm), mesopore (2-50 nm), and macropore (> 50 nm) are attractive due to their many emerging applications such as catalysts, separation systems, and low dielectric constant materials. The discovery of new M41S mesoporous silica families with pore sizes larger than 2 nm in diameter in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these silica materials has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Recently, core-shell nanoparticles with a silica core and mesoporous shell under basic conditions were synthesized using the silica nanoparticles as a core, and a silica precursor (TEOS) and cationic surfactant (CTABr) as a material for the formation of the mesoporous shell. The resultant materials were very monodispersive in size and showed a narrow pore size distribution in the range of ca 2-3 nm in diameter, depending on the alkyl-chain length of the surfactants used. In this work, the mesoporous shell coated-fumed silicas (denoted as MS M-5s) were synthesized by using fumed silica instead of the silica nanoparticle as a core based on previous reports. Also, the structural properties of the MS M-5s such as the specific surface area and pore volume were easily controlled by varying the amount of the silica precursor and surfactant. The resultant materials exhibited a BET surface area of ca 279-446 m{sup 2}/g and total pore volume of ca 0.64-0.74 cm{sup 3}/g and showed a narrow pore size distribution (PSD) due to the removal of the organic surfactant molecules

  4. Long-pore Electrostatics in Inward-rectifier Potassium Channels

    Science.gov (United States)

    Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoît

    2008-01-01

    Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (∼85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores. PMID:19001143

  5. The Drainage Consolidation Modeling of Sand Drain in Red Mud Tailing and Analysis on the Change Law of the Pore Water Pressure

    Directory of Open Access Journals (Sweden)

    Chuan-sheng Wu

    2014-01-01

    Full Text Available In order to prevent the occurring of dam failure and leakage, sand-well drainages systems were designed and constructed in red mud tailing. It is critical to focus on the change law of the pore water pressure. The calculation model of single well drainage pore water pressure was established. The pore water pressure differential equation was deduced and the analytical solution of differential equation using Bessel function and Laplace transform was given out. The impact of parameters such as diameter d, separation distance l, loading rate q, and coefficient of consolidation Cv in the function on the pore water pressure is analyzed by control variable method. This research is significant and has great reference for preventing red mud tailings leakage and the follow-up studies on the tailings stability.

  6. Rapid Isolation of a Single-Chain Antibody against the Cyanobacterial Toxin Microcystin-LR by Phage Display and Its Use in the Immunoaffinity Concentration of Microcystins from Water

    Science.gov (United States)

    McElhiney, Jacqui; Drever, Mathew; Lawton, Linda A.; Porter, Andy J.

    2002-01-01

    A naïve (unimmunized) human semisynthetic phage display library was employed to isolate recombinant antibody fragments against the cyanobacterial hepatotoxin microcystin-LR. Selected antibody scFv genes were cloned into a soluble expression vector and expressed in Escherichia coli for characterization against purified microcystin-LR by competition enzyme-linked immunosorbent assay (ELISA). The most sensitive single-chain antibody (scAb) isolated was capable of detecting microcystin-LR at levels below the World Health Organization limit in drinking water (1 μg liter−1) and cross-reacted with three other purified microcystin variants (microcystin-RR, -LW, and -LF) and the related cyanotoxin nodularin. Extracts of the cyanobacterium Microcystis aeruginosa were assayed by ELISA, and quantifications of microcystins in toxic samples showed good correlation with analysis by high-performance liquid chromatography. Immobilized scAb was also used to prepare immunoaffinity columns, which were assessed for the ability to concentrate microcystin-LR from water for subsequent analysis by high-performance liquid chromatography. Anti-microcystin-LR scAb was immobilized on columns via a hexahistidine tag, ensuring maximum exposure of antigen binding sites, and the performance of the columns was evaluated by directly applying 150 ml of distilled water spiked with 4 μg of purified microcystin-LR. The procedure was simple, and a recovery rate of 94% was achieved following elution in 1 ml of 100% methanol. Large-scale, low-cost production of anti-microcystin-LR scAb in E. coli is an exciting prospect for the development of biosensors and on-line monitoring systems for microcystins and will also facilitate a range of immunoaffinity applications for the cleanup and concentration of these toxins from environmental samples. PMID:12406716

  7. Final Report for Subcontract B541028, Pore-Scale Modeling to Support 'Pore Connectivity' Research Work

    International Nuclear Information System (INIS)

    Ewing, R.P.

    2009-01-01

    This report covers modeling aspects of a combined experimental and modeling task in support of the DOE Science and Technology Program (formerly OSTI) within the Office of Civilian Radioactive Waste Management (OCRWM). Research Objectives The research for this project dealt with diffusive retardation: solute moving through a fracture diffuses into and out of the rock matrix. This diffusive exchange retards overall solute movement, and retardation both dilutes waste being released, and allows additional decay. Diffusive retardation involves not only fracture conductivity and matrix diffusion, but also other issues and processes: contaminants may sorb to the rock matrix, fracture flow may be episodic, a given fracture may or may not flow depending on the volume of flow and the fracture's connection to the overall fracture network, the matrix imbibes water during flow episodes and dries between episodes, and so on. The objective of the project was to improve understanding of diffusive retardation of radionuclides due to fracture / matrix interactions. Results from combined experimental/modeling work were to (1) determine whether the current understanding and model representation of matrix diffusion is valid, (2) provide insights into the upscaling of laboratory-scale diffusion experiments, and (3) help in evaluating the impact on diffusive retardation of episodic fracture flow and pore connectivity in Yucca Mountain tuffs. Questions explored included the following: (1) What is the relationship between the diffusion coefficient measured at one scale, to that measured or observed at a different scale? In classical materials this relationship is trivial; in low-connectivity materials it is not. (2) Is the measured diffusivity insensitive to the shape of the sample? Again, in classical materials there should be no sample shape effect. (3) Does sorption affect diffusive exchange in low-connectivity media differently than in classical media? (4) What is the effect of matrix

  8. Acoustic characteristics of sand sediment with circular cylindrical pores

    International Nuclear Information System (INIS)

    Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang

    2004-01-01

    The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.

  9. MODERN ROUTES TO EXPLORE CONCRETE’S COMPLEX PORE SPACE

    Directory of Open Access Journals (Sweden)

    Piet Stroeven

    2011-05-01

    Full Text Available This paper concentrates on discrete element computer-simulation of concrete. It is argued on the basis of stochastic heterogeneity theory that modern concurrent-algorithm-based systems should be employed for the assessment of pore characteristics underlying durability performance of cementitious materials. The SPACE system was developed at Delft University of Technology for producing realistic schematizations of realcrete for a wide range of other particle packing problems, involving aggregate and fresh cement, and for the purpose of exploring characteristics in the hardened state of concrete, including of the pore network structure because of obvious durability problems. Since structure-sensitive properties are involved, schematization of reality should explicitly deal with the configuration of the cement particles in the fresh state. The paper concentrates on the stereological and mathematical morphology operations executed to acquire information on particle size, global porosity, and on distribution of porosity and of the connected pore fraction as a result of the near neighbourhood of aggregate grains. Goal is to provide information obtained along different exploration routes of concrete's pore space for setting up a pore network modelling approach. This type of methodological papers is scarce in concrete technology, if not missing at all. Technical publications that report on obtained results in our investigations are systematically referred to.

  10. An investigation of the effect of pore scale flow on average geochemical reaction rates using direct numerical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Molins, Sergi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division; Steefel, Carl I. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Division; Shen, Chaopeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Computational Research Division

    2012-03-30

    The scale-dependence of geochemical reaction rates hinders their use in continuum scale models intended for the interpretation and prediction of chemical fate and transport in subsurface environments such as those considered for geologic sequestration of CO2. Processes that take place at the pore scale, especially those involving mass transport limitations to reactive surfaces, may contribute to the discrepancy commonly observed between laboratory-determined and continuum-scale or field rates. In this study we investigate the dependence of mineral dissolution rates on the pore structure of the porous media by means of pore scale modeling of flow and multicomponent reactive transport. The pore scale model is composed of high-performance simulation tools and algorithms for incompressible flow and conservative transport combined with a general-purpose multicomponent geochemical reaction code. The model performs direct numerical simulation of reactive transport based on an operator-splitting approach to coupling transport and reactions. The approach is validated with a Poiseuille flow single-pore experiment and verified with an equivalent 1-D continuum-scale model of a capillary tube packed with calcite spheres. Using the case of calcite dissolution as an example, the high-resolution model is used to demonstrate that nonuniformity in the flow field at the pore scale has the effect of decreasing the overall reactivity of the system, even when systems with identical reactive surface area are considered. In conclusion, the effect becomes more pronounced as the heterogeneity of the reactive grain packing increases, particularly where the flow slows sufficiently such that the solution approaches equilibrium locally and the average rate becomes transport-limited.

  11. Physical foundations and experience of application of method of determination of volumes of all group of pore channels in powders and porous bodies

    International Nuclear Information System (INIS)

    Gabelkov, S.V.

    2011-01-01

    Physical foundations of the method of determination of the relative volumes of each group of pore channels that are available in a porous body on removal of work liquid from them at its evaporation were developed. Advantages and disadvantages are given, experience using of this method is extended at creating of ceramic matrix (cubic zirconia and magnesium-aluminium spinel) for isolation of high active waste. This method in combination with method of electronic microscopy has given an ability to investigate destruction of agglomerates and aggregates of xerogels and powders at milling and pressing, agglomeration of powders at its production and evolution of each component of pore spaces at sintering of porous bodies.

  12. Why liquid displacement methods are sometimes wrong in estimating the pore-size distribution

    NARCIS (Netherlands)

    Gijsbertsen-Abrahamse, A.J.; Boom, R.M.; Padt, van der A.

    2004-01-01

    The liquid displacement method is a commonly used method to determine the pore size distribution of micro- and ultrafiltration membranes. One of the assumptions for the calculation of the pore sizes is that the pores are parallel and thus are not interconnected. To show that the estimated pore size

  13. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn

    2011-01-19

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  14. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn; Sai, Hiroaki; Cohen, Roy; Wang, Suntao; Bradbury, Michelle; Baird, Barbara; Gruner, Sol M.; Wiesner, Ulrich

    2011-01-01

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  15. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong

    2015-12-28

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems. © ASCE.

  16. Fines classification based on sensitivity to pore-fluid chemistry

    Science.gov (United States)

    Jang, Junbong; Santamarina, J. Carlos

    2016-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil “electrical sensitivity.” Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.

  17. Influence of crosslinking agents on the pore structure of skin.

    Science.gov (United States)

    Fathima, N Nishad; Dhathathreyan, Aruna; Ramasami, T

    2007-05-15

    Analysis of pore structure of skin is important to understand process of diffusion and adsorption involved during any application of the skin matrix. In this study, the effect of thermal shrinkage on the pore structure of chromium and vegetable treated skin has been analyzed as these tanning agents are known to bring about thermal stability to the matrix. The changes brought about in the pore structure have been studied using mercury intrusion porosimetry and scanning electron microscopy. Response of the chromium treated and vegetable tanning treated skin structure to heat has been found to be quite different from each other. About 41% decrease in porosity is observed for chromium treated skin as against 97% decrease for the skin treated with vegetable tannins. This is primarily attributed to the basic nature of these materials and the nature of interaction of them towards skin.

  18. Semisynthetic protein nanoreactor for single-molecule chemistry

    OpenAIRE

    Lee, Joongoo; Bayley, Hagan

    2015-01-01

    The modulation of ionic current flowing through an individual protein pore provides information at the single-molecule level about chemical reactions occurring within the pore. However, chemistry investigated in this way has been largely confined to the reactions of thiolates, presented by the side chains of cysteine residues. The introduction of unnatural amino acids would provide a large variety of reactive side chains with which additional single-molecule chemistry could be investigated. H...

  19. Pore-Width-Dependent Preferential Interaction of sp2 Carbon Atoms in Cyclohexene with Graphitic Slit Pores by GCMC Simulation

    Directory of Open Access Journals (Sweden)

    Natsuko Kojima

    2011-01-01

    Full Text Available The adsorption of cyclohexene with two sp2 and four sp3 carbon atoms in graphitic slit pores was studied by performing grand canonical Monte Carlo simulation. The molecular arrangement of the cyclohexene on the graphitic carbon wall depends on the pore width. The distribution peak of the sp2 carbon is closer to the pore wall than that of the sp3 carbon except for the pore width of 0.7 nm, even though the Lennard-Jones size of the sp2 carbon is larger than that of the sp3 carbon. Thus, the difference in the interactions of the sp2 and sp3 carbon atoms of cyclohexene with the carbon pore walls is clearly observed in this study. The preferential interaction of sp2 carbon gives rise to a slight tilting of the cyclohexene molecule against the graphitic wall. This is suggestive of a π-π interaction between the sp2 carbon in the cyclohexene molecule and graphitic carbon.

  20. Dispersion upscaling from a pore scale characterization of Lagrangian velocities

    Science.gov (United States)

    Turuban, Régis; de Anna, Pietro; Jiménez-Martínez, Joaquín; Tabuteau, Hervé; Méheust, Yves; Le Borgne, Tanguy

    2013-04-01

    Mixing and reactive transport are primarily controlled by the interplay between diffusion, advection and reaction at pore scale. Yet, how the distribution and spatial correlation of the velocity field at pore scale impact these processes is still an open question. Here we present an experimental investigation of the distribution and correlation of pore scale velocities and its relation with upscaled dispersion. We use a quasi two-dimensional (2D) horizontal set up, consisting of two glass plates filled with cylinders representing the grains of the porous medium : the cell is built by soft lithography technique, wich allows for full control of the system geometry. The local velocity field is quantified from particle tracking velocimetry using microspheres that are advected with the pore scale flow. Their displacement is purely advective, as the particle size is chosen large enough to avoid diffusion. We thus obtain particle trajectories as well as lagrangian velocities in the entire system. The measured velocity field shows the existence of a network of preferential flow paths in channels with high velocities, as well as very low velocity in stagnation zones, with a non Gaussian distribution. Lagrangian velocities are long range correlated in time, which implies a non-fickian scaling of the longitudinal variance of particle positions. To upscale this process we develop an effective transport model, based on correlated continous time random walk, which is entirely parametrized by the pore scale velocity distribution and correlation. The model predictions are compared with conservative tracer test data for different Peclet numbers. Furthermore, we investigate the impact of different pore geometries on the distribution and correlation of Lagrangian velocities and we discuss the link between these properties and the effective dispersion behavior.

  1. Pore-water chemistry explains zinc phytotoxicity in soil.

    Science.gov (United States)

    Kader, Mohammed; Lamb, Dane T; Correll, Ray; Megharaj, Mallavarapu; Naidu, Ravi

    2015-12-01

    Zinc (Zn) is a widespread soil contaminant arising from a numerous anthropogenic sources. However, adequately predicting toxicity of Zn to ecological receptors remains difficult due to the complexity of soil characteristics. In this study, we examined solid-solution partitioning using pore-water data and toxicity of Zn to cucumber (Cucumis sativus L.) in spiked soils. Pore-water effective concentration (ECx, x=10%, 20% and 50% reduction) values were negatively related to pH, indicating lower Zn pore water concentration were needed to cause phytotoxicity at high pH soils. Total dissolved zinc (Znpw) and free zinc (Zn(2+)) in soil-pore water successfully described 78% and 80.3% of the variation in relative growth (%) in the full dataset. When the complete data set was used (10 soils), the estimated EC50pw was 450 and 79.2 µM for Znpw and Zn(2+), respectively. Total added Zn, soil pore water pH (pHpw) and dissolve organic carbon (DOC) were the best predictors of Znpw and Zn(2+) in pore-water. The EC10 (total loading) values ranged from 179 to 5214 mg/kg, depending on soil type. Only pH measurements in soil were related to ECx total Zn data. The strongest relationship to ECx overall was pHca, although pHw and pHpw were in general related to Zn ECx. Similarly, when a solution-only model was used to predict Zn in shoot, DOC was negatively related to Zn in shoot, indicating a reduction in uptake/ translocation of Zn from solution with increasing DOC. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

    Science.gov (United States)

    Chen, M.; Kocar, B. D.

    2016-12-01

    Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).

  3. Capillary filling rules and displacement mechanisms for spontaneous imbibition of CO2 for carbon storage and EOR using micro-model experiments and pore scale simulation

    Science.gov (United States)

    Chapman, E.; Yang, J.; Crawshaw, J.; Boek, E. S.

    2012-04-01

    In the 1980s, Lenormand et al. carried out their pioneering work on displacement mechanisms of fluids in etched networks [1]. Here we further examine displacement mechanisms in relation to capillary filling rules for spontaneous imbibition. Understanding the role of spontaneous imbibition in fluid displacement is essential for refining pore network models. Generally, pore network models use simple capillary filling rules and here we examine the validity of these rules for spontaneous imbibition. Improvement of pore network models is vital for the process of 'up-scaling' to the field scale for both enhanced oil recovery (EOR) and carbon sequestration. In this work, we present our experimental microfluidic research into the displacement of both supercritical CO2/deionised water (DI) systems and analogous n-decane/air - where supercritical CO2 and n-decane are the respective wetting fluids - controlled by imbibition at the pore scale. We conducted our experiments in etched PMMA and silicon/glass micro-fluidic hydrophobic chips. We first investigate displacement in single etched pore junctions, followed by displacement in complex network designs representing actual rock thin sections, i.e. Berea sandstone and Sucrosic dolomite. The n-decane/air experiments were conducted under ambient conditions, whereas the supercritical CO2/DI water experiments were conducted under high temperature and pressure in order to replicate reservoir conditions. Fluid displacement in all experiments was captured via a high speed video microscope. The direction and type of displacement the imbibing fluid takes when it enters a junction is dependent on the number of possible channels in which the wetting fluid can imbibe, i.e. I1, I2 and I3 [1]. Depending on the experiment conducted, the micro-models were initially filled with either DI water or air before the wetting fluid was injected. We found that the imbibition of the wetting fluid through a single pore is primarily controlled by the

  4. Role of scaffold mean pore size in meniscus regeneration.

    Science.gov (United States)

    Zhang, Zheng-Zheng; Jiang, Dong; Ding, Jian-Xun; Wang, Shao-Jie; Zhang, Lei; Zhang, Ji-Ying; Qi, Yan-Song; Chen, Xue-Si; Yu, Jia-Kuo

    2016-10-01

    Recently, meniscus tissue engineering offers a promising management for meniscus regeneration. Although rarely reported, the microarchitectures of scaffolds can deeply influence the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation in meniscus tissue engineering. Herein, a series of three-dimensional (3D) poly(ε-caprolactone) (PCL) scaffolds with three distinct mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The scaffold with the mean pore size of 215μm significantly improved both the proliferation and extracellular matrix (ECM) production/deposition of mesenchymal stem cells compared to all other groups in vitro. Moreover, scaffolds with mean pore size of 215μm exhibited the greatest tensile and compressive moduli in all the acellular and cellular studies. In addition, the relatively better results of fibrocartilaginous tissue formation and chondroprotection were observed in the 215μm scaffold group after substituting the rabbit medial meniscectomy for 12weeks. Overall, the mean pore size of 3D-printed PCL scaffold could affect cell behavior, ECM production, biomechanics, and repair effect significantly. The PCL scaffold with mean pore size of 215μm presented superior results both in vitro and in vivo, which could be an alternative for meniscus tissue engineering. Meniscus tissue engineering provides a promising strategy for meniscus regeneration. In this regard, the microarchitectures (e.g., mean pore size) of scaffolds remarkably impact the behaviors of cells and subsequent tissue formation, which has been rarely reported. Herein, three three-dimensional poly(ε-caprolactone) scaffolds with different mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The results suggested that the mean pore size significantly affected the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation. This study furthers

  5. Dynamics of phase ordering of nematics in a pore

    International Nuclear Information System (INIS)

    Bhattacharya, A.; Chakrabarti, A.

    1994-06-01

    We study the kinetics of phase ordering of a nematic liquid crystal, modeled by a spin-rotor Hamiltonian, confined within a parallel piped pore. The dynamics of the rotor obeys the time-dependent Ginzburg-Landau equation. We study the generation and evolution of a variety of defect structures, and the growth of domains, with different anchoring conditions at the pore surface. Unlike in binary fluids, mere confinement with no anchoring field, does not result in slow dynamics. Homeotropic anchoring, however, leads to slow logarithmic growth. Interestingly, homogeneous anchoring dynamically generates wall defects, resulting in an Ising like structure factor at late times. (author). 27 refs, 4 figs

  6. Effect of pore-size distribution on the collapse behaviour of anthropogenic sandy soil deposits

    Directory of Open Access Journals (Sweden)

    Baille Wiebke

    2016-01-01

    Full Text Available In the former open-pit mines of the Lusatian region in Germany, several liquefaction events have occurred during the recent years in the anthropogenic deposits made of very loose sandy soils. These events are related to the rising ground water table after the stop of controlled ground water lowering. The very loose state is due to the formation of sand aggregates (pseudo-grains during the deposition process. The pseudo-grains enclose larger voids of dimension greater than the single sand grain. Wetting induced collapse of the pseudo-grains is presumed to be one of the possible mechanisms triggering liquefaction. In the present study, the effect of larger voids on the wetting induced deformation behaviour of sandy soils is experimentally investigated by laboratory box tests. The deformation field in the sample during wetting was measured using Digital Image Correlation (DIC technique. The results show that the observed deformations are affected by the pore size distribution, thus the amount of voids between the pseudo-grains (macro-void ratio and the voids inside the pseudo-grains (matrix void ratio. The global void ratio of a sandy soil is not sufficient as single state parameter, but the pore size distribution has to be taken into account, experimentally as well as in modelling.

  7. Pore facies analysis: incorporation of rock properties into pore geometry based classes in a Permo-Triassic carbonate reservoir in the Persian Gulf

    International Nuclear Information System (INIS)

    Rahimpour-Bonab, H; Aliakbardoust, E

    2014-01-01

    Pore facies analysis is a useful method for the classification of reservoir rocks according to pore geometry characteristics. The importance of this method is related to the dependence of the dynamic behaviour of the reservoir rock on the pore geometry. In this study, pore facies analysis was performed by the quantification and classification of the mercury injection capillary pressure (MICP) curves applying the multi-resolution graph-based clustering (MRGC) method. Each pore facies includes a limited variety of rock samples with different depositional fabrics and diagenetic histories, which are representative of one type of pore geometry. The present pore geometry is the result of the interaction between the primary rock fabric and its diagenetic overprint. Thus the variations in petrographic properties can be correlated with the pore geometry characteristics. Accordingly, the controlling parameters in the pore geometry characteristics were revealed by detailed petrographic analysis in each pore facies. The reservoir rock samples were then classified using the determined petrographic properties which control the pore system quality. This method is proposed for the classification of reservoir rocks in complicated carbonate reservoirs, in order to reduce the incompatibility of traditional facies analysis with pore system characteristics. The method is applicable where enough capillary pressure data is not available. (papers)

  8. Monitoring of bentonite pore water with a probe based on solid-state microsensors

    International Nuclear Information System (INIS)

    Orozco, Jahir; Baldi, Antoni; Martin, Pedro L.; Bratov, Andrei; Jimenez, Cecilia

    2006-01-01

    Repositories for the disposal of radioactive waste generally rely on a multi-barrier system to isolate the waste from the biosphere. This multi-barrier system typically comprises Natural geological barrier provided by the repository host rock and its surroundings and an engineered barrier system (EBS). Bentonite is being studied as an appropriated porous material for an EBS to prevent or delay the release and transport of radionuclides towards biosphere. The study of pore water chemistry within bentonite barriers will permit to understand the transport phenomena of radionuclides and obtain a database of the bentonite-water interaction processes. In this work, the measurement of some chemical parameters in bentonite pore water using solid-state microsensors is proposed. Those sensors are well suited for this application since in situ measurements are feasible and they are robust enough for the long periods of time that monitoring is needed in an EBS. A probe containing an ISFET (ion sensitive field effect transistor) for measuring pH, and platinum microelectrodes for measuring conductivity and redox potential was developed, together with the required instrumentation, to study the chemical changes in a test cell with compacted bentonite. Response features of the sensors' probe and instrumentation performance in synthetic samples with compositions similar to those present in bentonite barriers are reported. Measurements of sensors stability in a test cell are also presented

  9. Pore network modeling of drainage process in patterned porous media: a quasi-static study

    KAUST Repository

    Zhang, Tao

    2015-04-17

    This work represents a preliminary investigation on the role of wettability conditions on the flow of a two-phase system in porous media. Since such effects have been lumped implicitly in relative permeability-saturation and capillary pressure-saturation relationships, it is quite challenging to isolate its effects explicitly in real porous media applications. However, within the framework of pore network models, it is easy to highlight the effects of wettability conditions on the transport of two-phase systems. We employ quasi-static investigation in which the system undergo slow movement based on slight increment of the imposed pressure. Several numerical experiments of the drainage process are conducted to displace a wetting fluid with a non-wetting one. In all these experiments the network is assigned different scenarios of various wettability patterns. The aim is to show that the drainage process is very much affected by the imposed pattern of wettability. The wettability conditions are imposed by assigning the value of contact angle to each pore throat according to predefined patterns.

  10. Capillary pressure-saturation relationships for porous granular materials: Pore morphology method vs. pore unit assembly method

    Science.gov (United States)

    Sweijen, Thomas; Aslannejad, Hamed; Hassanizadeh, S. Majid

    2017-09-01

    In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe-Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

  11. Septal Pore Caps in Basidiomycetes, Composition and Ultrastructure

    NARCIS (Netherlands)

    Driel, K.G.A. van

    2007-01-01

    Filamentous fungi, including Ascomycota and Basidiomycota, form mycelia that consist of a network of apical growing hyphae. These hyphae are separated into cellular compartments by septa that have pores of about 70 to 500 nm in diameter. The cytoplasm within the mycelium is thus continuous

  12. Pore-scale uncertainty quantification with multilevel Monte Carlo

    KAUST Repository

    Icardi, Matteo

    2014-01-06

    Computational fluid dynamics (CFD) simulations of pore-scale transport processes in porous media have recently gained large popularity. However the geometrical details of the pore structures can be known only in a very low number of samples and the detailed flow computations can be carried out only on a limited number of cases. The explicit introduction of randomness in the geometry and in other setup parameters can be crucial for the optimization of pore-scale investigations for random homogenization. Since there are no generic ways to parametrize the randomness in the porescale structures, Monte Carlo techniques are the most accessible to compute statistics. We propose a multilevel Monte Carlo (MLMC) technique to reduce the computational cost of estimating quantities of interest within a prescribed accuracy constraint. Random samples of pore geometries with a hierarchy of geometrical complexities and grid refinements, are synthetically generated and used to propagate the uncertainties in the flow simulations and compute statistics of macro-scale effective parameters.

  13. The dimension of the pore space in sponges

    International Nuclear Information System (INIS)

    Silva, L H F; Yamashita, M T

    2009-01-01

    A simple experiment to reveal the dimension of the pore space in sponges is proposed. This experiment is suitable for the first year of a physics or engineering course. The calculated dimension of the void space in a sponge of density 16 mg cm -3 was 2.948± 0.008

  14. Microstructural characterization and pore structure analysis of nuclear graphite

    International Nuclear Information System (INIS)

    Kane, J.; Karthik, C.; Butt, D.P.; Windes, W.E.; Ubic, R.

    2011-01-01

    Graphite will be used as a structural and moderator material in next-generation nuclear reactors. While the overall nature of the production of nuclear graphite is well understood, the historic nuclear grades of graphite are no longer available. This paper reports the virgin microstructural characteristics of filler particles and macro-scale porosity in virgin nuclear graphite grades of interest to the Next Generation Nuclear Plant program. Optical microscopy was used to characterize filler particle size and shape as well as the arrangement of shrinkage cracks. Computer aided image analysis was applied to optical images to quantitatively determine the variation of pore structure, area, eccentricity, and orientation within and between grades. The overall porosity ranged between ∼14% and 21%. A few large pores constitute the majority of the overall porosity. The distribution of pore area in all grades was roughly logarithmic in nature. The average pore was best fit by an ellipse with aspect ratio of ∼2. An estimated 0.6-0.9% of observed porosity was attributed to shrinkage cracks in the filler particles. Finally, a preferred orientation of the porosity was observed in all grades.

  15. Energetics of Transport through the Nuclear Pore Complex

    NARCIS (Netherlands)

    Ghavami, Ali; van der Giessen, Erik; Onck, Patrick R

    2016-01-01

    Molecular transport across the nuclear envelope in eukaryotic cells is solely controlled by the nuclear pore complex (NPC). The NPC provides two types of nucleocytoplasmic transport: passive diffusion of small molecules and active chaperon-mediated translocation of large molecules. It has been shown

  16. On the Mechanism of Pore Formation by Melittin

    NARCIS (Netherlands)

    van den Bogaart, Geert; Guzman, Jeanette Velasquez; Mika, Jacek T.; Poolman, Bert

    2008-01-01

    The mechanism of pore formation of lytic peptides, such as melittin from bee venom, is thought to involve binding to the membrane surface, followed by insertion at threshold levels of bound peptide. We show that in membranes composed of zwitterionic lipids, i.e. phosphatidylcholine, melittin not

  17. Plastic strain caused by contraction of pores in polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, Ikuo; Yoda, Shinichi; Konishi, Takashi.

    1989-01-01

    The effects of porosity on mechanical properties and deformation behavior of four isotropic polycrystalline graphites were studied. The pore size distributions of the graphites were measured using a conventional mercury penetration technique. The average pore radius of ISO-88 graphite was about one-tenth of that of ISEM-1, IG-11 or IG-15 graphites. Young's modulus of the graphites decreased with increasing porosity. The stress-strain curve of each graphite was measured in its lateral and axial directions. Young's modulus of graphite decreased with increasing load. The plastic strain at a given compressive load was calculated from the stress-strain curve and the initial gradient of the unloading curve at the load. The ratio of lateral plastic strain to axial plastic strain for the graphites was less than 0.5, indicating that the volume of the graphites decreased during compressive loading. By assuming that the volume change was caused by contraction of pores, plastic strain associated with contraction of pores was calculated from the axial plastic strain and lateral plastic strain by slips along the basal planes. The plastic strain increased with increasing axial plastic strain and porosity of graphite. (author)

  18. Pore collapse and regrowth in silicon electrodes for rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    DeCaluwe, S. C. [Department of Mechanical Engineering; Colorado School of Mines; USA; Center for Neutron Research; National Institute of Standards and Technology; Dhar, B. M. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Material Measurement Laboratory; Huang, L. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; He, Y. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Department of Physics and Astronomy; Yang, K. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Owejan, J. P. [Department of Mechanical and Electrical Engineering Technology; State University of New York; Alfred; USA; Zhao, Y. [Department of Physics and Astronomy; University of Georgia; Athens; USA; Talin, A. A. [Center for Nanoscale Science and Technology; National Institute of Standards and Technology; Gaithersburg; USA; Sandia National Laboratories; Dura, J. A. [Center for Neutron Research; National Institute of Standards and Technology; Gaithersburg; USA; Wang, H. [Department of Materials Science and Engineering; University of Maryland; College Park; USA; Institute for Materials Research and Dept. of Mechanical Engineering

    2015-01-01

    In-operando Neutron Reflectometry establishes the pore collapse and regrowth (PCRG) mechanism in amorphous Si. Upon lithiation, porosity is first consumed by expansion of solid Si domains, with little thickness increase. After, the whole film expands. Porosity returns upon delithiation.

  19. Alumina ceramics prepared with new pore-forming agents

    Directory of Open Access Journals (Sweden)

    Zuzana Živcová

    2008-06-01

    Full Text Available Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed, which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch to approximately 1 mm (poppy seed, all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds and starch consolidation casting (using metal molds are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry.

  20. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong; Santamarina, Carlos

    2015-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing

  1. Mesoporous templated silicas: stability, pore size engineering and catalytic activation

    International Nuclear Information System (INIS)

    Vansant, Etienne

    2003-01-01

    The Laboratory of Adsorption and Catalysis has focused its research activities on the synthesis and activation of new porous materials. In the past few years, we have succeeded in developing easy and reproducible pathways to synthesize a huge variety of mesoporous crystalline materials. Points of interest in the synthesis of Mesoporous Templated Silicas are (i) stabilization of the structure, to withstand hydrothermal, thermal and mechanical pressure, (ii) pore size engineering to systematically control the pore size, pore volume and the ratio micro/mesopores and (iii) ease and reproducibility of the synthesis procedure, applying green principles, such as template recuperation. By carefully adapting the synthesis conditions and composition of the synthesis gel, using surfactants (long chain quaternary ammonium ions) and co-templates (long chain amines, alcohols or alkanes), the pore size of the obtained materials can be controlled from 1.5 to 7.0 nm, retaining the very narrow pore size distribution. Alternatively, materials with combined micro- and mesoporosity can be synthesized, using neutral surfactants (triblock copolymers). Hereby, the optimization of the SBA-15 and SBA-16 synthesis is being done in order to create mesoporous materials with microporous walls. The second research line is the controlled activation of MTS materials, by grafting or incorporation of catalytic active centers. We have developed for this purpose the Molecular Designed Dispersion method, which uses metal diketonate complexes as precursors. It is shown that in all cases the dispersion of the metal oxides on the surface is much better compared to the conventional grafting techniques. We have studied and published activation with V, Ti, Mo, Fe, Al and Cr species on different MTS materials. The structure and location of the active metal ion is the subject of an extensive spectroscopic investigation, using FT-IR, FT-Raman, UV-Vis DR coupled with selective chemisorption experiments and

  2. Formation and decay of rudimentary penumbra around a pore

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Hiroko [Unit of Synergetic Studies for Space, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Kitai, Reizaburo [Kwasan and Hida Observatories, Kyoto University, Yamashina-ku, Kyoto 607-8417 (Japan); Otsuji, Kenichi, E-mail: watanabe@kwasan.kyoto-u.ac.jp [Solar Observatory, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan)

    2014-12-01

    We analyze the evolution of a pore in the active region NOAA 10940 using the data obtained by the Hinode satellite on 2007 February 3. The pore we analyzed showed the formation of a rudimentary penumbra structure, succeeded by an abrupt disappearance after about 5 hr. The pore had an approximate radius of 3.5 Mm and a total magnetic flux of 3.0 × 10{sup 19} Mx, which is a little smaller than the necessary magnetic flux for penumbral formation supposed by Rucklidge et al. (1-1.5 × 10{sup 20} Mx). Our observation describes a rare phenomenon which was in the unstable phase between a pore and a sunspot. The area of the dark umbra gradually decreased when the rudimentary penumbral filaments formed the penumbral structure, meaning that the penumbra develops at the expense of the umbral magnetic flux. This statement was confirmed by a rough estimation of the magnetic flux variation observed by the Hinode Fe I magnetogram. Five hours after the formation phase, the decay phase began. In this decaying phase, multiple opposite polarity patches are found to appear in the exterior of the pore (a different location from the penumbra formation site). We interpret these opposite polarities as signatures of the horizontal magnetic field, which preferably appears in the course of the unstable reconfiguration of the magnetic field structure. During the course of the disappearance of the penumbra, the horizontal penumbral field seems to become vertical because of the dark umbral area that recovered by about 10%.

  3. Predicting Reactive Transport Dynamics in Carbonates using Initial Pore Structure

    Science.gov (United States)

    Menke, H. P.; Nunes, J. P. P.; Blunt, M. J.

    2017-12-01

    Understanding rock-fluid interaction at the pore-scale is imperative for accurate predictive modelling of carbon storage permanence. However, coupled reactive transport models are computationally expensive, requiring either a sacrifice of resolution or high performance computing to solve relatively simple geometries. Many recent studies indicate that initial pore structure many be the dominant mechanism in determining the dissolution regime. Here we investigate how well the initial pore structure is predictive of distribution and amount of dissolution during reactive flow using particle tracking on the initial image. Two samples of carbonate rock with varying initial pore space heterogeneity were reacted with reservoir condition CO2-saturated brine and scanned dynamically during reactive flow at a 4-μm resolution between 4 and 40 times using 4D X-ray micro-tomography over the course of 1.5 hours using μ-CT. Flow was modelled on the initial binarized image using a Navier-Stokes solver. Particle tracking was then run on the velocity fields, the streamlines were traced, and the streamline density was calculated both on a voxel-by-voxel and a channel-by-channel basis. The density of streamlines was then compared to the amount of dissolution in subsequent time steps during reaction. It was found that for the flow and transport regimes studied, the streamline density distribution in the initial image accurately predicted the dominant pathways of dissolution and gave good indicators of the type of dissolution regime that would later develop. This work suggests that the eventual reaction-induced changes in pore structure are deterministic rather than stochastic and can be predicted with high resolution imaging of unreacted rock.

  4. Boom clay pore water, home of a diverse microbial community

    International Nuclear Information System (INIS)

    Wouters, Katinka; Moors, Hugo; Leys, Natalie

    2012-01-01

    Document available in extended abstract form only. Boom Clay pore water (BCPW) has been studied in the framework of geological disposal of nuclear waste for over two decades, thereby mainly addressing its geochemical properties. A reference composition for synthetic clay water has been derived earlier by modelling and spatial calibration efforts, mainly based on interstitial water sampled from different layers within the Boom clay. However, since microbial activity is found in a range of extreme circumstances, the possibility of microbes interacting with future radioactive waste in a host formation like Boom Clay, cannot be ignored. In this respect, BCPW was sampled from different Boom Clay layers using the Morpheus piezometer and subsequently analysed by a complementary set of microbiological and molecular techniques, in search for overall shared and abundant microorganisms. Similar to the previous characterization of the 'average' BCPW chemical composition, the primary aim of this microbiological study is to determine a representative BCPW microbial community which can be used in laboratory studies. Secondly, the in situ activity and the metabolic properties of members of this community were addressed, aiming to assess their survival and proliferation chances in repository conditions. In a first approach, total microbial DNA of the community was extracted from the BCPW samples. This molecular approach allows a broad insight in the total microbial ecology of the BCPW samples. By polymerase chain reaction (PCR) on the highly conserved 16S rRNA genes in this DNA pool and subsequent sequencing and bio-informatics analysis, operational taxonomic units (OTUs) could be assigned to the microbial community. The bacterial community was found to be quite diverse, with OTUs belonging to 8 different phyla (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chlorobi, Spirochetes, Chloroflexi and Deinococcus-Thermus). These results provide an overall view of the

  5. Boom clay pore water, home of a diverse microbial community

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, Katinka; Moors, Hugo; Leys, Natalie [SCK.CEN, Environment, Health and Safety Institute, B-2400 Mol (Belgium)

    2012-10-15

    Document available in extended abstract form only. Boom Clay pore water (BCPW) has been studied in the framework of geological disposal of nuclear waste for over two decades, thereby mainly addressing its geochemical properties. A reference composition for synthetic clay water has been derived earlier by modelling and spatial calibration efforts, mainly based on interstitial water sampled from different layers within the Boom clay. However, since microbial activity is found in a range of extreme circumstances, the possibility of microbes interacting with future radioactive waste in a host formation like Boom Clay, cannot be ignored. In this respect, BCPW was sampled from different Boom Clay layers using the Morpheus piezometer and subsequently analysed by a complementary set of microbiological and molecular techniques, in search for overall shared and abundant microorganisms. Similar to the previous characterization of the 'average' BCPW chemical composition, the primary aim of this microbiological study is to determine a representative BCPW microbial community which can be used in laboratory studies. Secondly, the in situ activity and the metabolic properties of members of this community were addressed, aiming to assess their survival and proliferation chances in repository conditions. In a first approach, total microbial DNA of the community was extracted from the BCPW samples. This molecular approach allows a broad insight in the total microbial ecology of the BCPW samples. By polymerase chain reaction (PCR) on the highly conserved 16S rRNA genes in this DNA pool and subsequent sequencing and bio-informatics analysis, operational taxonomic units (OTUs) could be assigned to the microbial community. The bacterial community was found to be quite diverse, with OTUs belonging to 8 different phyla (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chlorobi, Spirochetes, Chloroflexi and Deinococcus-Thermus). These results provide an overall view of the

  6. Influence of pore fluid and frequency on elastic properties of greensand as interpreted using NMR data

    DEFF Research Database (Denmark)

    Hossain, Zakir; Mukerj, Tapan; Fabricius, Ida Lykke

    2011-01-01

    dispersion. However, Biot’s theory does not fully explain the frequency dispersion of sedimentary rocks. Greensands are composed of a mixture of quartz and micro-porous glauconite grains. In greensand, it is possible that the contrast between flow in macro-pores and micro-pores within glauconites gives rise....... Biot’s critical frequency and NMR (nuclear magnetic resonance) T2 spectrum were combined to describe the differences in fluid flow within macro-pores and within micro-pores. NMR data show that Biot’s flow should occur only in large pores in the greensand while, Biot’s flow should not occur in micro-pores....... Differences of fluid flow in macro-pores and micro-pores pores are described as high frequency squirt flow in greensand....

  7. Understanding capillary condensation and hysteresis in porous silicon: network effects within independent pores.

    Science.gov (United States)

    Naumov, Sergej; Khokhlov, Alexey; Valiullin, Rustem; Kärger, Jörg; Monson, Peter A

    2008-12-01

    The ability to exert a significant degree of pore structure control in porous silicon materials has made them attractive materials for the experimental investigation of the relationship between pore structure, capillary condensation, and hysteresis phenomena. Using both experimental measurements and a lattice gas model in mean field theory, we have investigated the role of pore size inhomogeneities and surface roughness on capillary condensation of N2 at 77K in porous silicon with linear pores. Our results resolve some puzzling features of earlier experimental work. We find that this material has more in common with disordered materials such as Vycor glass than the idealized smooth-walled cylindrical pores discussed in the classical adsorption literature. We provide strong evidence that this behavior comes from the complexity of the processes within independent linear pores, arising from the pore size inhomogeneities along the pore axis, rather than from cooperative effects between different pores.

  8. An instrument to measure differential pore pressures in deep ocean sediments: Pop-Up-Pore-Pressure-Instrument (PUPPI)

    International Nuclear Information System (INIS)

    Schultheiss, P.J.; McPhail, S.D.; Packwood, A.R.; Hart, B.

    1985-01-01

    A Pop-Up-Pore-Pressure-Instrument (PUPPI) has been developed to measure differential pore pressures in sediments. The differential pressure is the pressure above or below normal hydrostatic pressure at the depth of the measurement. It is designed to operate in water depths up to 6000 metres for periods of weeks or months, if required, and measures differential pore pressures at depths of up to 3 metres into the sediments with a resolution of 0.05 kPa. It is a free-fall device with a lance which penetrates the sediments. This lance and the ballast weight is disposed when the PUPPI is acoustically released from the sea floor. When combined with permeability and porosity values of deep-sea sediments the pore pressure measurements made using the PUPPI suggest advection velocities as low as 8.8 mm/yr. The mechanical, electrical and acoustic systems are described together with data obtained from both shallow and deep water trials. (author)

  9. Monte-Carlo simulation of crystallographical pore growth in III-V-semiconductors

    International Nuclear Information System (INIS)

    Leisner, Malte; Carstensen, Juergen; Foell, Helmut

    2011-01-01

    The growth of crystallographical pores in III-V-semiconductors can be understood in the framework of a simple model, which is based on the assumption that the branching of pores is proportional to the current density at the pore tips. The stochastic nature of this model allows its implementation into a three-dimensional Monte-Carlo-simulation of pore growth. The simulation is able to reproduce the experimentally observed crysto pore structures in III-V-semiconductors in full quantitative detail. The different branching probabilities for different semiconductors, as well as doping levels, can be deduced from the specific passivation behavior of the semiconductor-electrolyte-interface at the pore tips.

  10. Unstable Pore-Water Flow in Intertidal Wetlands

    Science.gov (United States)

    Barry, D. A.; Shen, C.; Li, L.

    2014-12-01

    Salt marshes are important intertidal wetlands strongly influenced by interactions between surface water and groundwater. Bordered by coastal water, the marsh system undergoes cycles of inundation and exposure driven by the tide. This leads to dynamic, complex pore-water flow and solute transport in the marsh soil. Pore-water circulations occur over vastly different spatial and temporal scales with strong link to the marsh topography. These circulations control solute transport between the marsh soil and the tidal creek, and ultimately affect the overall nutrient exchange between the marsh and coastal water. The pore-water flows also dictate the soil condition, particularly aeration, which influences the marsh plant growth. Numerous studies have been carried out to examine the pore-water flow process in the marsh soil driven by tides, focusing on stable flow with the assumption of homogeneity in soil and fluid properties. This assumption, however, is questionable given the actual inhomogeneous conditions in the field. For example, the salinity of surface water in the tidal creek varies temporally and spatially due to the influence of rainfall and evapotranspiration as well as the freshwater input from upland areas to the estuary, creating density gradients across the marsh surface and within the marsh soil. Many marshes possess soil stratigraphy with low-permeability mud typically overlying high-permeability sandy deposits. Macropores such as crab burrows are commonly distributed in salt marsh sediments. All these conditions are prone to the development of non-uniform, unstable preferential pore-water flow in the marsh soil, for example, funnelling and fingering. Here we present results from laboratory experiments and numerical simulations to explore such unstable flow. In particular, the analysis aims to address how the unstable flow modifies patterns of local pore-water movement and solute transport, as well as the overall exchange between the marsh soil and

  11. Pore connectivity effects on solute transport in rocks

    International Nuclear Information System (INIS)

    Hu, Qinhong; Ewing, Robert P.

    2001-01-01

    Retardation of nuclear contaminants in rock matrices can lead to long retention times, allowing substantial radionuclide decay prior to eventual release. Imbibition and diffusion into the rock matrix can move contaminants away from an active fracture, thereby contributing to their retardation. However, diffusive transport in some rocks may behave anomalously because of their sparsely connected porespace, in contrast to diffusion in rocks with denser pore connections. We examined imbibition of weakly sorbing tracers into welded tuff and Indiana sandstone, and water imbibition into metagraywacke and Berea sandstone. Tuff samples were initially equilibrated to 12% and 76% water (v/v) within controlled humidity chambers, while the other rocks were air-dried. For imbibition, one face was exposed to water, with or without tracer, and uptake was measured over time. Following imbibition, tracer concentration measurements were made at fine (1 mm) increments. Three anomalous results were observed: (1) Indiana sandstone and metagraywacke showed mass of imbibed water scaling as time 0.26 , while tuff and Berea sandstone showed the more classical scaling with time 0.5 ; (2) tracer movement into dry (2% initial saturation) Indiana sandstone showed a dispersion pattern similar to that expected during tracer movement into moist (76% initial saturation) tuff; and (3) tracer concentrations at the inlet face of the tuff sample were approximately twice those deeper inside the sample. The experiment was then modeled using random walk methods on a 3-D lattice with different values of pore coordination. Network model simulations that used a pore coordination of 1.49 for Indiana sandstone and 1.56 for metagraywacke showed similar temporal scaling, a result of their porespace being close to the percolation threshold. Tracer concentration profiles in Indiana sandstone and tuff were closely matched by simulations that used pore coordinations of 1.49 and 1.68, respectively, because of how low

  12. Pore Connectivity Effects on Solute Transport in Rocks

    International Nuclear Information System (INIS)

    Oinhong Hu

    2001-01-01

    Retardation of nuclear contaminants in rock matrices can lead to long retention times, allowing substantial radionuclide decay prior to eventual release. Imbibition and diffusion into the rock matrix can move contaminants away from an active fracture, thereby contributing to their retardation. However, diffusive transport in some rocks may behave anomalously because of their sparsely connected porespace, in contrast to diffusion in rocks with denser pore connections. We examined imbibition of weakly sorbing tracers into welded tuff and Indiana sandstone, and water imbibition into metagraywacke and Berea sandstone. Tuff samples were initially equilibrated to 12% and 76% water (v/v) within controlled humidity chambers, while the other rocks were air-dried. For imbibition, one face was exposed to water, with or without tracer, and uptake was measured over time. Following imbibition, tracer concentration measurements were made at fine (1 mm) increments. Three anomalous results were observed: (1) Indiana sandstone and metagraywacke showed mass of imbibed water scaling as time 0.26 , while tuff and Berea sandstone showed the more classical scaling with time 0.05 ; (2) tracer movement into dry (2% initial saturation) Indiana sandstone showed a dispersion pattern similar to that expected during tracer movement into moist (76% initial saturation) tuft and (3) tracer concentrations at the inlet face of the tuff sample were approximately twice those deeper inside the sample. The experiment was then modeled using random walk methods on a 3-D lattice with different values of pore coordination. Network model simulations that used a pore coordination of 1.49 for Indiana sandstone and 1.56 for metagraywacke showed similar temporal scaling, a result of their porespace being close to the percolation threshold. Tracer concentration profiles in Indiana sandstone and tuff were closely matched by simulations that used pore coordinations of 1.49 and 1.68, respectively, because of how low

  13. Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content

    Science.gov (United States)

    Mastalerz, Maria; Drobniak, A.; Strapoc, D.; Solano-Acosta, W.; Rupp, J.

    2008-01-01

    The Seelyville Coal Member of the Linton Formation (Pennsylvanian) in Indiana was studied to: 1) understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations, 2) elaborate on the influence of mineral-matter and maceral composition on mesopore and micropore characteristics, and 3) discuss implications of these variations for coal bed gas content. The coal is high volatile bituminous rank with R0 ranging from 0.57% to 0.60%. BET specific surface areas (determined by nitrogen adsorption) of the coals samples studied range from 1.8 to 22.9??m2/g, BJH adsorption mesopore volumes from 0.0041 to 0.0339??cm3/g, and micropore volumes (determined by carbon dioxide adsorption) from 0.0315 to 0.0540??cm3/g. The coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths, whereas the smallest values for these two parameters occur in the deepest coals. Micropore volumes, in contrast, are not depth-dependent. In the coal samples examined for this study, mineral-matter content influenced both specific surface area as well as mesopore and micropore volumes. It is especially clear in the case of micropores, where an increase in mineral-matter content parallels the decrease of micropore volume of the coal. No obvious relationships were observed between the total vitrinite content and pore characteristics but, after splitting vitrinite into individual macerals, we see that collotelinite influences both meso- and micropore volume positively, whereas collodetrinite contributes to the reduction of mesopore and micropore volumes. There are large variations in gas content within a single coal at a single location. Because of this variability, the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation. ?? 2008 Elsevier B.V. All

  14. Pore-scale Simulation and Imaging of Multi-phase Flow and Transport in Porous Media (Invited)

    Science.gov (United States)

    Crawshaw, J.; Welch, N.; Daher, I.; Yang, J.; Shah, S.; Grey, F.; Boek, E.

    2013-12-01

    We combine multi-scale imaging and computer simulation of multi-phase flow and reactive transport in rock samples to enhance our fundamental understanding of long term CO2 storage in rock formations. The imaging techniques include Confocal Laser Scanning Microscopy (CLSM), micro-CT and medical CT scanning, with spatial resolutions ranging from sub-micron to mm respectively. First, we report a new sample preparation technique to study micro-porosity in carbonates using CLSM in 3 dimensions. Second, we use micro-CT scanning to generate high resolution 3D pore space images of carbonate and cap rock samples. In addition, we employ micro-CT to image the processes of evaporation in fractures and cap rock degradation due to exposure to CO2 flow. Third, we use medical CT scanning to image spontaneous imbibition in carbonate rock samples. Our imaging studies are complemented by computer simulations of multi-phase flow and transport, using the 3D pore space images obtained from the scanning experiments. We have developed a massively parallel lattice-Boltzmann (LB) code to calculate the single phase flow field in these pore space images. The resulting flow fields are then used to calculate hydrodynamic dispersion using a novel scheme to predict probability distributions for molecular displacements using the LB method and a streamline algorithm, modified for optimal solid boundary conditions. We calculate solute transport on pore-space images of rock cores with increasing degree of heterogeneity: a bead pack, Bentheimer sandstone and Portland carbonate. We observe that for homogeneous rock samples, such as bead packs, the displacement distribution remains Gaussian with time increasing. In the more heterogeneous rocks, on the other hand, the displacement distribution develops a stagnant part. We observe that the fraction of trapped solute increases from the beadpack (0 %) to Bentheimer sandstone (1.5 %) to Portland carbonate (8.1 %), in excellent agreement with PFG

  15. Identification and characterization of smallest pore-forming protein in the cell wall of pathogenic Corynebacterium urealyticum DSM 7109.

    Science.gov (United States)

    Abdali, Narges; Younas, Farhan; Mafakheri, Samaneh; Pothula, Karunakar R; Kleinekathöfer, Ulrich; Tauch, Andreas; Benz, Roland

    2018-05-09

    Corynebacterium urealyticum, a pathogenic, multidrug resistant member of the mycolata, is known as causative agent of urinary tract infections although it is a bacterium of the skin flora. This pathogenic bacterium shares with the mycolata the property of having an unusual cell envelope composition and architecture, typical for the genus Corynebacterium. The cell wall of members of the mycolata contains channel-forming proteins for the uptake of solutes. In this study, we provide novel information on the identification and characterization of a pore-forming protein in the cell wall of C. urealyticum DSM 7109. Detergent extracts of whole C. urealyticum cultures formed in lipid bilayer membranes slightly cation-selective pores with a single-channel conductance of 1.75 nS in 1 M KCl. Experiments with different salts and non-electrolytes suggested that the cell wall pore of C. urealyticum is wide and water-filled and has a diameter of about 1.8 nm. Molecular modelling and dynamics has been performed to obtain a model of the pore. For the search of the gene coding for the cell wall pore of C. urealyticum we looked in the known genome of C. urealyticum for a similar chromosomal localization of the porin gene to known porH and porA genes of other Corynebacterium strains. Three genes are located between the genes coding for GroEL2 and polyphosphate kinase (PKK2). Two of the genes (cur_1714 and cur_1715) were expressed in different constructs in C. glutamicum ΔporAΔporH and in porin-deficient BL21 DE3 Omp8 E. coli strains. The results suggested that the gene cur_1714 codes alone for the cell wall channel. The cell wall porin of C. urealyticum termed PorACur was purified to homogeneity using different biochemical methods and had an apparent molecular mass of about 4 kDa on tricine-containing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Biophysical characterization of the purified protein (PorACur) suggested indeed that cur_1714 is the gene

  16. Nonlinear Porous Diffusion Modeling of Hydrophilic Ionic Agrochemicals in Astomatous Plant Cuticle Aqueous Pores: A Mechanistic Approach.

    Science.gov (United States)

    Tredenick, Eloise C; Farrell, Troy W; Forster, W Alison; Psaltis, Steven T P

    2017-01-01

    The agricultural industry requires improved efficacy of sprays being applied to crops and weeds in order to reduce their environmental impact and deliver improved financial returns. Enhanced foliar uptake is one means of improving efficacy. The plant leaf cuticle is known to be the main barrier to diffusion of agrochemicals within the leaf. The usefulness of a mathematical model to simulate uptake of agrochemicals in plant cuticles has been noted previously in the literature, as the results of each uptake experiment are specific to each formulation of active ingredient, plant species and environmental conditions. In this work we develop a mathematical model and numerical simulation for the uptake of hydrophilic ionic agrochemicals through aqueous pores in plant cuticles. We propose a novel, nonlinear, porous diffusion model for ionic agrochemicals in isolated cuticles, which extends simple diffusion through the incorporation of parameters capable of simulating: plant species variations, evaporation of surface droplet solutions, ion binding effects on the cuticle surface and swelling of the aqueous pores with water. We validate our theoretical results against appropriate experimental data, discuss the key sensitivities in the model and relate theoretical predictions to appropriate physical mechanisms. Major influencing factors have been found to be cuticle structure, including tortuosity and density of the aqueous pores, and to a lesser extent humidity and cuticle surface ion binding effects.

  17. Nonlinear Porous Diffusion Modeling of Hydrophilic Ionic Agrochemicals in Astomatous Plant Cuticle Aqueous Pores: A Mechanistic Approach

    Directory of Open Access Journals (Sweden)

    Eloise C. Tredenick

    2017-05-01

    Full Text Available The agricultural industry requires improved efficacy of sprays being applied to crops and weeds in order to reduce their environmental impact and deliver improved financial returns. Enhanced foliar uptake is one means of improving efficacy. The plant leaf cuticle is known to be the main barrier to diffusion of agrochemicals within the leaf. The usefulness of a mathematical model to simulate uptake of agrochemicals in plant cuticles has been noted previously in the literature, as the results of each uptake experiment are specific to each formulation of active ingredient, plant species and environmental conditions. In this work we develop a mathematical model and numerical simulation for the uptake of hydrophilic ionic agrochemicals through aqueous pores in plant cuticles. We propose a novel, nonlinear, porous diffusion model for ionic agrochemicals in isolated cuticles, which extends simple diffusion through the incorporation of parameters capable of simulating: plant species variations, evaporation of surface droplet solutions, ion binding effects on the cuticle surface and swelling of the aqueous pores with water. We validate our theoretical results against appropriate experimental data, discuss the key sensitivities in the model and relate theoretical predictions to appropriate physical mechanisms. Major influencing factors have been found to be cuticle structure, including tortuosity and density of the aqueous pores, and to a lesser extent humidity and cuticle surface ion binding effects.

  18. Nanometer-Scale Pore Characteristics of Lacustrine Shale, Songliao Basin, NE China.

    Directory of Open Access Journals (Sweden)

    Min Wang

    Full Text Available In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale pores or fractures, so the pore types and PSDs (pore size distributions play a major role in the shale oil occurrence (free or absorbed state, amount of oil, and flow features. The pore types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale pores and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope observations, low pressure CO2 and N2 adsorption, and high-pressure mercury injection experiments. Analysis results indicate that: (1 Pore types in the lacustrine shale include inter-matrix pores, intergranular pores, organic matter pores, and dissolution pores, and these pores are dominated by mesopores and micropores; (2 There is no apparent correlation between pore volumes and clay content, however, a weak negative correlation is present between total pore volume and carbonate content; (3 Pores in lacustrine shale are well developed when the organic matter maturity (Ro is >1.0% and the pore volume is positively correlated with the TOC (total organic carbon content. The statistical results suggest that oil in lacustrine shale mainly occurs in pores with diameters larger than 40 nm. However, more research is needed to determine whether this minimum pore diameter for oil occurrence in lacustrine shale is widely applicable.

  19. Soil Pore Network Visualisation and Quantification using ImageJ

    DEFF Research Database (Denmark)

    Garbout, Amin; Pajor, Radoslaw; Otten, Wilfred

    Abstract Soil is one of the most complex materials on the earth, within which many biological, physical and chemical processes that support life and affect climate change take place. A much more detailed knowledge of the soil system is required to improve our ability to develop soil management...... strategies to preserve this limited resource. Many of those processes occur at micro scales. For long our ability to study soils non-destructively at microscopic scales has been limited, but recent developments in the use of X-ray Computed Tomography has offered great opportunities to quantify the 3-D...... geometry of soil pores. In this study we look at how networks that summarize the geometry of pores in soil are affected by soil structure. One of the objectives is to develop a robust and reproducible image analysis technique to produce quantitative knowledge on soil architecture from high resolution 3D...

  20. Design of pore size of macroporous ceramic substrates

    International Nuclear Information System (INIS)

    Szewald, O.; Kotsis, I.

    2000-01-01

    A method has been developed for the design of macro-porous ceramic substrates. Based on geometrical and regression models detailed technology was worked out for producing these 100% open porous filters, which were made using quasi homo-disperse fractions of corundum of diameters of several tens and hundreds microns and glassy binding material. Axial pressing was used as a forming process. Pore networks with size distribution that can be defined by a curve having one maximum were provided applying the above technology. Based on geometrical considerations and measurements it was proved that these maximums are at characteristic pore sizes that depend only on characteristic size of the original grain fractions and on the extent of the axial forming pressure. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  1. Zeolitic imidazolate frameworks with optimized pore structure for olefin/paraffin-separation

    Energy Technology Data Exchange (ETDEWEB)

    Paula, C.; Boehme, U.; Hartmann, M. [Erlangen-Nuernberg Univ. (Germany). Erlangen Catalysis Resource Center

    2013-11-01

    In the chemical industry, the largest part of energy is spent on separation processes such as the separation of olefin/paraffin mixtures from steam cracker effluents by low-temperature rectification. A suitable alternative to this energy and cost intensive process is separation by selective adsorption with suitable microporous adsorbent. In this work, different ZIFs (Zeolitic Imidazolate Frameworks) have been explored with respect to their separation of olefins and paraffins. The studied materials (e.g. ZIF-8 (SOD-Topology), ZIF-71 (RHO-Topology)) were selected because of their low diameter of the largest pore entrance (0.29 to 4.2 nm) which is close to the kinetic diameter of the C{sub 2} to C{sub 4} olefins and paraffins under study. In contrast to other MOF- or zeolite-based adsorbents, in ZIF-8 and ZIF-71, the paraffin is preferentially adsorbed, which is evident from the single-component adsorption isotherms at different temperature. In the corresponding mixture breakthrough curves, the olefin breaks through first and the alkane even displaces the olefin from the pores. Thus, ZIF-8 and ZIF-71 are interesting candidates for the envisaged paraffin/olefin separation. Whether the observed separation behavior is due to the structural properties of the studied ZIFs or a consequence of peculiar chemical properties is subject to further studies. (orig.) (Published in summary form only)

  2. Analyzer for measuring gas contained in the pore space of rocks

    Science.gov (United States)

    Kudasik, Mateusz; Skoczylas, Norbert

    2017-10-01

    In the present paper, the authors discussed the functioning of their own analyzer for measuring gas contained in the pore space of high strength rocks. A sample is placed inside a hermetic measuring chamber, and then undergoes impact milling as a result of colliding with the vibrating blade of a knife which is rotationally driven by a high-speed brushless electric motor. The measuring chamber is equipped with all the necessary sensors, i.e. gas, pressure, and temperature sensors. Trial tests involving the comminution of dolomite and anhydrite samples demonstrated that the constructed device is able to break up rocks into grains so fine that they are measured in single microns, and the sensors used in the construction ensure balancing of the released gas. The tests of the analyzer showed that the metrological concept behind it, together with the way it was built, make it fit for measurements of the content and composition of selected gases from the rock pore space. On the basis of the conducted tests of balancing the gases contained in the two samples, it was stated that the gas content of Sample no. 1 was (0.055  ±  0.002) cm3 g-1, and Sample no. 2 contained gas at atmospheric pressure, composed mostly of air.

  3. Functional Differentiation of Three Pores for Effective Sulfur Confinement in Li-S Battery.

    Science.gov (United States)

    Wang, Qian; Yang, Minghui; Wang, Zhen-Bo; Li, Chao; Gu, Da-Ming

    2018-03-01

    Shuttle effect of the dissolved intermediates is regarded as the primary cause that leads to fast capacity degradation of Li-S battery. Herein, a microporous carbon-coated sulfur composite with novel rambutan shape (R-S@MPC) is synthesized from microporous carbon-coated rambutan-like zinc sulfide (R-ZnS@MPC), via an in situ oxidation process. The R-ZnS is employed as both template and sulfur precursor. The carbon frame of R-S@MPC composite possesses three kinds of pores that are distinctly separated from each other in space and are endowed with the exclusive functions. The central macropore serves as buffer pool to accommodate the dissolved lithium polysulfides (LPSs) and volumetric variation during cycling. The marginal straight-through mesoporous, connected with the central macropore, takes the responsibility of sulfur storage. The micropores, evenly distributed in the outer carbon shell of the as-synthesized R-S@MPC, enable the blockage of LPSs. These pores are expected to perform their respective single function, and collaborate synergistically to suppress the sulfur loss. Therefore, it delivers an outstanding cycling stability, decay rate of 0.013% cycle -1 after 500 cycles at 1 C, when the sulfur loading is kept at 4 mg cm -2 . © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Development of a reactive burn model based upon an explicit visco-plastic pore collapse model

    Science.gov (United States)

    Bouton, Eric; Lefrançois, Alexandre; Belmas, Robert

    2015-06-01

    Our aim in this study is to develop a reactive burn model based upon a microscopic hot spot model to compute the initiation and shock to detonation of pressed TATB explosives. For the sake of simplicity, the hot spots are supposed to result from the viscoplastic collapse of spherical micro-voids inside the composition. Such a model has been incorporated in a lagrangian hydrodynamic code. In our calculations, 8 different pore diameters, ranging from 100 nm to 1.2 μm, have been taken into account and the porosity associated to each pore size has been deduced from the PBX-9502 void distribution derived from the SAXS. The last ingredient of our model is the burn rate that depends on two main variables. The first one is the shock pressure as proposed by the developers of the CREST model. The second one is the number of effective chemical reaction sites calculated by the microscopic model. Furthermore, the function of the reaction progress variable of the burn rate is similar to that in the SURF model proposed by Menikoff. Our burn rate has been calibrated by using pressure profile, material velocities wave forms obtained with embedded particle velocity gauges and run distance to detonation. The comparison between the numerical and experimental results is really good and sufficient to perform a wide variety of simulations including single, double shock waves and the desensitization phenomenon. In conclusion, future works are described.

  5. Amino acid residues involved in membrane insertion and pore formation of Clostridium botulinum C2 toxin.

    Science.gov (United States)

    Lang, Alexander E; Neumeyer, Tobias; Sun, Jianjun; Collier, R John; Benz, Roland; Aktories, Klaus

    2008-08-12

    The actin-ADP-ribosylating Clostridium botulinum C2 toxin consists of the enzymatic component C2I and the binding component C2II. C2II forms heptameric channels involved in translocation of the enzymatic component into the target cell. On the basis of the heptameric toxin channel, we studied functional consequences of mutagenesis of amino acid residues probably lining the lumen of the toxin channel. Substitution of glutamate-399 of C2II with alanine blocked channel formation and cytotoxicity of the holotoxin. Although cytotoxicity and rounding up of cells by C2I were completely blocked by exchange of phenylalanine-428 with alanine, the mutation increased potassium conductance caused by C2II in artificial membranes by about 2-3-fold over that of wild-type toxin. In contrast to its effects on single-channel potassium conductance in artificial membranes, the F428A mutation delayed the kinetics of pore formation in lipid vesicles and inhibited the activity of C2II in promoting (86)Rb (+) release from preloaded intact cells after pH shift of the medium. Moreover, F428A C2II exhibited delayed and diminished formation of C2II aggregates at low pH, indicating major changes of the biophysical properties of the toxin. The data indicate that phenylalanine-428 of C2II plays a major role in conformational changes occurring during pore formation of the binding component of C2II.

  6. Tissue Distribution of a Therapeutic Monoclonal Antibody Determined by Large Pore Microdialysis.

    Science.gov (United States)

    Jadhav, Satyawan B; Khaowroongrueng, Vipada; Fueth, Matthias; Otteneder, Michael B; Richter, Wolfgang; Derendorf, Hartmut

    2017-09-01

    Therapeutic monoclonal antibodies (mAbs) exhibit limited distribution to the target tissues. Determination of target tissue interstitial concentration of mAbs is an important aspect in the assessment of their pharmacokinetic/pharmacodynamics relationship especially for mAbs targeting membrane bound receptors. The pharmacokinetics of R7072, a full length mAb (IgG) targeting human insulin-like growth factor-1 receptor was evaluated following a single intravenous dose at 1, 6.25, and 25 mg/kg in healthy female SCID-beige mice. R7072 showed linear pharmacokinetics over the dose range tested and was characterized by low systemic clearance and long terminal half-life. Furthermore, interstitial distribution of R7072 was evaluated in liver, skin, kidney, and muscle tissues using large pore microdialysis (MD) after intravenous administration of 10 mg/kg dose in mice. The relative recoveries of R7072 were consistent and similar between in vitro and in vivo MD experiments. The tissue and interstitial concentrations were significantly lower compared to serum concentrations and found to be highest in liver and lowest in muscle. The interstitial concentrations of R7072 were approximately 2-fold to 4-fold lower than corresponding total tissue concentrations. Large pore MD appears to be an attractive approach for direct measurement of pharmacologically relevant concentrations of therapeutic mAbs in tissue interstitial fluid. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  7. Numerical estimates of the maximum sustainable pore pressure in anticline formations using the tensor based concept of pore pressure-stress coupling

    Directory of Open Access Journals (Sweden)

    Andreas Eckert

    2015-02-01

    Full Text Available The advanced tensor based concept of pore pressure-stress coupling is used to provide pre-injection analytical estimates of the maximum sustainable pore pressure change, ΔPc, for fluid injection scenarios into generic anticline geometries. The heterogeneous stress distribution for different prevailing stress regimes in combination with the Young's modulus (E contrast between the injection layer and the cap rock and the interbedding friction coefficient, μ, may result in large spatial and directional differences of ΔPc. A single value characterizing the cap rock as for horizontal layered injection scenarios is not obtained. It is observed that a higher Young's modulus in the cap rock and/or a weak mechanical coupling between layers amplifies the maximum and minimum ΔPc values in the valley and limb, respectively. These differences in ΔPc imposed by E and μ are further amplified by different stress regimes. The more compressional the stress regime is, the larger the differences between the maximum and minimum ΔPc values become. The results of this study show that, in general compressional stress regimes yield the largest magnitudes of ΔPc and extensional stress regimes provide the lowest values of ΔPc for anticline formations. Yet this conclusion has to be considered with care when folded anticline layers are characterized by flexural slip and the friction coefficient between layers is low, i.e. μ = 0.1. For such cases of weak mechanical coupling, ΔPc magnitudes may range from 0 MPa to 27 MPa, indicating imminent risk of fault reactivation in the cap rock.

  8. Pore Pressure Distribution and Flank Instability in Hydrothermally Altered Stratovolcanoes

    Science.gov (United States)

    Ball, J. L.; Taron, J.; Hurwitz, S.; Reid, M. E.

    2015-12-01

    Field and geophysical investigations of stratovolcanoes with long-lived hydrothermal systems commonly reveal that initially permeable regions (such as brecciated layers of pyroclastic material) can become both altered and water-bearing. Hydrothermal alteration in these regions, including clay formation, can turn them into low-permeability barriers to fluid flow, which could increase pore fluid pressures resulting in flank slope instability. We examined elevated pore pressure conditions using numerical models of hydrothermal flow in stratovolcanoes, informed by geophysical data about internal structures and deposits. Idealized radially symmetric meshes were developed based on cross-sectional profiles and alteration/permeability structures of Cascade Range stratovolcanoes. We used the OpenGeoSys model to simulate variably saturated conditions in volcanoes heated only by regional heat fluxes, as well as 650°C intrusions at two km depth below the surface. Meteoric recharge was estimated from precipitation rates in the Cascade Range. Preliminary results indicate zones of elevated pore pressures form: 1) where slopes are underlain by continuous low-permeability altered layers, or 2) when the edifice has an altered core with saturated, less permeable limbs. The first scenario might control shallow collapses on the slopes above the altered layers. The second could promote deeper flank collapses that are initially limited to the summit and upper slopes, but could progress to the core of an edifice. In both scenarios, pore pressures can be further elevated by shallow intrusions, or evolve over longer time scales under forcing from regional heat flux. Geometries without confining low-permeability layers do not show these pressure effects. Our initial scenarios use radially symmetric models, but we are also simulating hydrothermal flow under real 3D geometries with asymmetric subsurface structures (Mount Adams). Simulation results will be used to inform 3D slope

  9. Gas release from pressurized closed pores in nuclear fuels

    International Nuclear Information System (INIS)

    Bailey, P.; Donnelly, S.E.; Armour, D.G.; Matzke, H.

    1988-01-01

    Gas release from the nuclear fuels UO 2 and UN out of pressurized closed pores produced by autoclave anneals has been studied by Thermal Desorption Spectrometry (TDS). Investigation of gas release during heating and cooling has indicated stress related mechanical effects leading to gas release. This release occurred in a narrow temperature range between about 1000 and 1500 K for UO 2 , but it continued down to ambient temperature for UN. No burst release was observed above 1500 K for UO 2 . (orig.)

  10. Understanding the mechanisms behind coking pressure: Relationship to pore structure

    Energy Technology Data Exchange (ETDEWEB)

    John J. Duffy; M. Castro Diaz; Colin E. Snape; Karen M. Steel; Merrick R. Mahoney [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2007-09-15

    Three low volatile coals A, B and C with oven wall pressures of 100 kPa, 60 kPa and 20 kPa respectively were investigated using high-temperature rheometry, {sup 1}H NMR, thermogravimetric analysis and SEM, with the primary aim to better understand the mechanisms behind the coking pressure phenomenon. Rheometer plate displacement measurements ({Delta}L) have shown differences in the expansion and contraction behaviour of the three coals, which seem to correlate with changes in rheological properties; while SEM images have shown that the expansion process coincides with development of pore structure. It is considered that the point of maximum plate height ({Delta}L{sub max}) prior to contraction may be indicative of a cell opening or pore network forming process, based on analogies with other foam systems. Such a process may be considered important for coking pressure since it provides a potential mechanism for volatile escape, relieving internal gas pressure and inducing charge contraction. For coal C, which has the highest fluidity {delta}L{sub max} occurs quite early in the softening process and consequently a large degree of contraction is observed; while for the lower fluidity coal B, the process is delayed since pore development and consequently wall thinning progress at a slower rate. When {Delta}L{sub max} is attained, a lower degree of contraction is observed because the event occurs closer to resolidification where the increasing viscosity/elasticity can stabilise the expanded pore structure. For coal A which is relatively high fluidity, but also high coking pressure, a greater degree of swelling is observed prior to cell rupture, which may be due to greater fluid elasticity during the expansion process. This excessive expansion is considered to be a potential reason for its high coking pressure. 58 refs., 15 figs., 1 tab.

  11. Pore Space Connectivity and the Transport Properties of Rocks

    Directory of Open Access Journals (Sweden)

    Bernabé Yves

    2016-07-01

    Full Text Available Pore connectivity is likely one of the most important factors affecting the permeability of reservoir rocks. Furthermore, connectivity effects are not restricted to materials approaching a percolation transition but can continuously and gradually occur in rocks undergoing geological processes such as mechanical and chemical diagenesis. In this study, we compiled sets of published measurements of porosity, permeability and formation factor, performed in samples of unconsolidated granular aggregates, in which connectivity does not change, and in two other materials, sintered glass beads and Fontainebleau sandstone, in which connectivity does change. We compared these data to the predictions of a Kozeny-Carman model of permeability, which does not account for variations in connectivity, and to those of Bernabé et al. (2010, 2011 model, which does [Bernabé Y., Li M., Maineult A. (2010 Permeability and pore connectivity: a new model based on network simulations, J. Geophys. Res. 115, B10203; Bernabé Y., Zamora M., Li M., Maineult A., Tang Y.B. (2011 Pore connectivity, permeability and electrical formation factor: a new model and comparison to experimental data, J. Geophys. Res. 116, B11204]. Both models agreed equally well with experimental data obtained in unconsolidated granular media. But, in the other materials, especially in the low porosity samples that had undergone the greatest amount of sintering or diagenesis, only Bernabé et al. model matched the experimental data satisfactorily. In comparison, predictions of the Kozeny-Carman model differed by orders of magnitude. The advantage of the Bernabé et al. model was its ability to account for a continuous, gradual reduction in pore connectivity during sintering or diagenesis. Although we can only speculate at this juncture about the mechanisms responsible for the connectivity reduction, we propose two possible mechanisms, likely to be active at different stages of sintering and diagenesis

  12. Optimization of transdermal delivery using magainin pore-forming peptide

    OpenAIRE

    Kim, Yeu-Chun; Ludovice, Peter J.; Prausnitz, Mark R.

    2008-01-01

    The skin's outer layer of stratum corneum, which is a thin tissue containing multilamellar lipid bilayers, is the main barrier to drug delivery to the skin. To increase skin permeability, our previous work has shown large enhancement of transdermal permeation using a pore-forming peptide, magainin, which was formulated with N-lauroyl sarcosine (NLS) in 50% ethanol-in-PBS. Mechanistic analysis suggested that magainin and NLS can increase skin permeability by disrupting stratum corneum lipid st...

  13. Experimental research of ZrO{sub 2}/BCP/PCL scaffold with complex pore pattern for bone tissue

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Min Woo; Shin, Hae Ri; Kim, Jong Young [Dept. of Mechanical Engineering, Andong National University, Andong (Korea, Republic of)

    2015-11-15

    Recently, synthetic biopolymers and bioceramics such as poly (-caprolactone)(PCL), hydroxyapatite, tricalcium phosphate, biphasic calcium phosphate(BCP), and zirconia have been used as substrates to generate various tissues or organs in tissue engineering. Thus, the purpose of this study was the characterization of ZrO{sub 2}/BCP/PCL(ZBP) scaffold for bone tissue regeneration. Based on the result of single-line test, blended 3D ZBP scaffolds with fully interconnected pores and new complex pore pattern of -type and staggered-type were successfully fabricated using a polymer deposition system. Furthermore, the effect of ZBP scaffold on mechanical property was analyzed. In addition, in vitro cell interaction of ZBP scaffold on MG63 cells was evaluated using a cell counting kit-8(CCK-8) assay.

  14. Radial symmetry in a chimeric glutamate receptor pore

    Science.gov (United States)

    Wilding, Timothy J.; Lopez, Melany N.; Huettner, James E.

    2014-02-01

    Ionotropic glutamate receptors comprise two conformationally different A/C and B/D subunit pairs. Closed channels exhibit fourfold radial symmetry in the transmembrane domain (TMD) but transition to twofold dimer-of-dimers symmetry for extracellular ligand binding and N-terminal domains. Here, to evaluate symmetry in open pores we analysed interaction between the Q/R editing site near the pore loop apex and the transmembrane M3 helix of kainate receptor subunit GluK2. Chimeric subunits that combined the GluK2 TMD with extracellular segments from NMDA receptors, which are obligate heteromers, yielded channels made up of A/C and B/D subunit pairs with distinct substitutions along M3 and/or Q/R site editing status, in an otherwise identical homotetrameric TMD. Our results indicate that Q/R site interaction with M3 occurs within individual subunits and is essentially the same for both A/C and B/D subunit conformations, suggesting that fourfold pore symmetry persists in the open state.

  15. Toxicity of sediments and pore water from Brunswick Estuary, Georgia

    Science.gov (United States)

    Winger, Parley V.; Lasier, Peter J.; Geitner, Harvey

    1993-01-01

    A chlor-alkali plant in Brunswick, Georgia, USA, discharged >2 kg mercury/d into a tributary of the Turtle River-Brunswick Estuary from 1966 to 1971. Mercury concentrations in sediments collected in 1989 along the tributary near the chlor-alkali plant ranged from 1 to 27 μg/g (dry weight), with the highest concentrations found in surface (0–8 cm) sediments of subtidal zones in the vicinity of the discharge site. Toxicity screening in 1990 using Microtox® bioassays on pore water extracted on site from sediments collected at six stations distributed along the tributary indicated that pore water was highly toxic near the plant discharge. Ten-day toxicity tests on pore water from subsequent sediment samples collected near the plant discharge confirmed high toxicity to Hyalella azteca, and feeding activity was significantly reduced in whole-sediment tests. In addition to mercury in the sediments, other metals (chromium, lead, and zinc) exceeded 50 μg/g, and polychlorobiphenyl (PCB) concentrations ranged from 67 to 95 μg/g. On a molar basis, acid-volatile sulfide concentrations (20–45 μmol/g) in the sediments exceeded the metal concentrations. Because acid-volatile sulfides bind with cationic metals and form metal sulfides, which are generally not bioavailable, toxicities shown by these sediments were attributed to the high concentrations of PCBs and possibly methylmercury.

  16. Chemical modelling of pore water composition from PFBC residues

    International Nuclear Information System (INIS)

    Karlsson, L.G.

    1991-01-01

    The concentration of trace elements varies depending on the source of the coal and also due to the combustion process used. Mercury is one important element among the trace elements in the coal residues, generally recognised as potentially harmful to the biological system. To predict the pore water concentrations of mercury and other important constituents leached from coal combustion residues disposal sites, mechanistic data on chemical reactions are required. The present study is an application of a basially thermodynamical approach using the geochemical code EQ3NR. The presence of discrete solid phases that control the aqueous concentrations of major elements such as aluminium, calcium and silicon are identified. Solid phases are modelled in equilibrium with a hypothetical pore water at a pH range of 7-11. In this study the thermodynamic database of EQ3NR has been complemented with data for cadmium, mercury and lead taken from the OECD/NEA Thermodynamic Database and from a compilation made by Lindsay. Possible solubility limiting phases for the important trace elements arsenic, cadmium, chromium, copper, mercury, nickel and lead have been identified. Concentrations of these trace elements as a function of pH in the hypothetical pore water were calculated using mechanistic thermodynamial data. The thermodynamical approach in this study seems justified because most solid residues that are either present or expected to form during weathering have relatively fast precipitation/dissolution kinetics. (21 refs., 18 figs., 5 tabs.)

  17. Effects of pore design on mechanical properties of nanoporous silicon

    International Nuclear Information System (INIS)

    Winter, Nicholas; Becton, Matthew; Zhang, Liuyang; Wang, Xianqiao

    2017-01-01

    Nanoporous silicon has been emerging as a powerful building block for next-generation sensors, catalysts, transistors, and tissue scaffolds. The capability to design novel devices with desired mechanical properties is paramount to their reliability and serviceability. In order to bring further resolution to the highly variable mechanical characteristics of nanoporous silicon, here we perform molecular dynamics simulations to study the effects of ligament thickness, relative density, and pore geometry/orientation on the mechanical properties of nanoporous silicon, thereby determining its Young's modulus, ultimate strength, and toughness as well as the scaling laws versus the features of interior ligaments. Results show that pore shape and pattern dictate stress accumulation inside the designed structure, leading to the corresponding failure signature, such as stretching-dominated, bending-dominated, or stochastic failure signatures, in nanoporous silicon. The nanostructure of the material is also seen to drive or mute size effects such as “smaller is stronger” and “smaller is ductile”. This investigation provides useful insight into the behavior of nanoporous silicon and how one might leverage its promising applications. - Graphical abstract: Molecular dynamics simulations are performed to study the effects of ligament thickness, relative density, and pore geometry/orientation on the mechanical properties of nanoporous silicon, thereby determining its Young's modulus, ultimate strength, and toughness as well as the scaling trends versus the features of interior ligaments.

  18. Influence factors on etching rate of PET nuclear pore membrane

    International Nuclear Information System (INIS)

    Zuo Zhenzhong; Wu Zhendong; Liang Haiying; Ju Wei; Chen Dongfeng; Fu Yuanyong; Qu Guopu

    2014-01-01

    Background: The nuclear pore membrane is a kind of liquid filtration material manufactured by irradiation and chemical etching. Various conditions in etch process have a great influence on etch rate. Purpose: The influence factors of concentration and temperature of etch solution and the irradiation energy of heavy ions on etch rate was studied. Methods: Four layers of PET (polyethylene terephthalate) films were stacked together and were irradiated with 140-MeV 32 S ions at room temperature under vacuum conditions. Utilizing conductivity measurement technique, the electrical current changes through the u:radiated PET film were monitored during etching, from which the breakthrough time and therefore the track etching rate was calculated. Results: The results show that there is an exponential correlation between etch rate and temperature, and a linear correlation between etch rate and concentration. The track etching rate increases linearly with energy loss rate. Empirical formula for the bulk etching rate as a function of etchant concentration and temperature was also established via fitting of measurements. Conclusion: It is concluded that by using 1.6-MeV·u -1 32 S ions, PET nuclear pore membrane with cylindrical pore shape can be prepared at 85℃ with etchant concentration of l mol·L -1 . (authors)

  19. Cationic PAMAM dendrimers as pore-blocking binary toxin inhibitors.

    Science.gov (United States)

    Förstner, Philip; Bayer, Fabienne; Kalu, Nnanya; Felsen, Susanne; Förtsch, Christina; Aloufi, Abrar; Ng, David Y W; Weil, Tanja; Nestorovich, Ekaterina M; Barth, Holger

    2014-07-14

    Dendrimers are unique highly branched macromolecules with numerous groundbreaking biomedical applications under development. Here we identified poly(amido amine) (PAMAM) dendrimers as novel blockers for the pore-forming B components of the binary anthrax toxin (PA63) and Clostridium botulinum C2 toxin (C2IIa). These pores are essential for delivery of the enzymatic A components of the internalized toxins from endosomes into the cytosol of target cells. We demonstrate that at low μM concentrations cationic PAMAM dendrimers block PA63 and C2IIa to inhibit channel-mediated transport of the A components, thereby protecting HeLa and Vero cells from intoxication. By channel reconstitution and high-resolution current recording, we show that the PAMAM dendrimers obstruct transmembrane PA63 and C2IIa pores in planar lipid bilayers at nM concentrations. These findings suggest a new potential role for the PAMAM dendrimers as effective polyvalent channel-blocking inhibitors, which can protect human target cells from intoxication with binary toxins from pathogenic bacteria.

  20. Pore Topology Effects in Positron Annihilation Spectroscopy of Zeolites.

    Science.gov (United States)

    Zubiaga, Asier; Warringham, Robbie; Mitchell, Sharon; Gerchow, Lars; Cooke, David; Crivelli, Paolo; Pérez-Ramírez, Javier

    2017-03-03

    Positron annihilation spectroscopy (PAS) is a powerful method to study the size and connectivity of pores in zeolites. The lifetime of positronium within the host material is commonly described by the Tao-Eldrup model. However, one of its largest limitations arises from the simple geometries considered for the shape of the pores, which cannot describe accurately the complex topologies in zeolites. Here, an atomic model that combines the Tao potential with the crystallographic structure is introduced to calculate the distribution and lifetime of Ps intrinsic to a given framework. A parametrization of the model is undertaken for a set of widely applied zeolite framework types (*BEA, FAU, FER, MFI, MOR, UTL), before extending the model to all known structures. The results are compared to structural and topological descriptors, and to the Tao-Eldrup model adapted for zeolites, demonstrating the intricate dependence of the lifetime on the pore architecture. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Dawestrema cycloancistrium (Monogenea) from the head pores of arapaimas.

    Science.gov (United States)

    Portes Santos, Cláudia; da Silva, Maralina Torres; Moravec, Franti Ek

    2017-07-24

    Arapaima gigas is one of the main cultured fish species in South America, and monogenean parasites of this species cause large economic losses to fish farmers. During surveys of the parasites of cultured arapaimas from Mexiana Island in the Amazon River Delta, Rio Branco, in northwestern Brazilian Amazonia, and Yurimaguas, Peru, the monogenean Dawestrema cycloancistrium was found in the gills of A. gigas as well as in previously unreported sites, i.e. the head pores and chambers. The aim of this study was to investigate the transmission route of this parasite and its geographical distribution as well as to describe its morphology as observed by light and confocal imaging. Phalloidin labeling confirmed the presence of 2 prostatic reservoirs and showed muscular branches of fibers supporting haptoral sclerites. In arapaimas, the head connects to the gill chambers via 2 perforated scales located at the dorsolateral sides of the distal part of the head. The scales connect to thin channels and chambers situated in the proximal part of the head. These chambers are filled with cephalic mucus, which flows out to the environment through terminal pores. Adults and egg masses of monogeneans were found on the gills and inside the head pores and cavities of fish along with cephalic mucus. This indicates a specialized method of parasite transmission from adult fish to fingerlings during parental care (holding offspring in the mouth) or via head secretions, providing evidence of a new adapted mechanism of dispersion.

  2. In situ temperature tunable pores of shape memory polyurethane membranes

    International Nuclear Information System (INIS)

    Ahn, Joon-Sung; Yu, Woong-Ryeol; Youk, Ji Ho; Ryu, Hee Youk

    2011-01-01

    Conventional shape memory polymers, such as shape memory polyurethanes (SMPU), can exhibit net two-way shape memory behavior (2WSM), i.e., upon heating and subsequent cooling, their macroscopic shapes change reversibly under an applied bias load. This paper is aimed at reporting similar 2WSM behavior, especially by focusing on the size of nanopores/micropores in SMPU membranes, i.e., the size of the pores can be reversibly changed by up to about 300 nm upon repeated heating and cooling. The SMPU membranes were prepared by electrospinning and elongated at temperatures higher than the transition temperature of the SMPU. Under the constant stress, the size change of the pores in the membranes was measured by applying cyclic temperature change. It was observed that the pore size changed from 150 to 440 nm according to the temperature change, demonstrating that the SMPU membrane can be utilized as a smart membrane to selectively separate substances according to their sizes by just controlling temperature

  3. Integration of pore features into the evaluation of fingerprint evidence.

    Science.gov (United States)

    Anthonioz, Alexandre; Champod, Christophe

    2014-01-01

    Fingerprint practitioners rely on level 3 features to make decisions in relation to the source of an unknown friction ridge skin impression. This research proposes to assess the strength of evidence associated with pores when shown in (dis)agreement between a mark and a reference print. Based upon an algorithm designed to automatically detect pores, a metric is defined in order to compare different impressions. From this metric, the weight of the findings is quantified using a likelihood ratio. The results obtained on four configurations and 54 donors show the significant contribution of the pore features and translate into statistical terms what latent fingerprint examiners have developed holistically through experience. The system provides LRs that are indicative of the true state under both the prosecution and the defense propositions. Not only such a system brings transparency regarding the weight to assign to such features, but also forces a discussion in relation to the risks of such a model to mislead. © 2013 American Academy of Forensic Sciences.

  4. Isolation World

    OpenAIRE

    Núñez Martín, Eugeni

    2012-01-01

    El trabajo de fin de grado tiene como nombre “Isolation World”, que en su traducción literal significa “Aislamiento del mundo”, un videojuego diseñado y creado desde cero en su totalidad, utilizando herramientas y conocimiento de lógica en programación que se han ido aprendiendo y desarrollando a lo largo de la carrera.

  5. Evaluation of Optimal Pore Size of (3-Aminopropyltriethoxysilane Grafted MCM-41 for Improved CO2 Adsorption

    Directory of Open Access Journals (Sweden)

    Zhilin Liu

    2015-01-01

    Full Text Available An array of new MCM-41 with substantially larger average pore diameters was synthesized through adding 1,3,5-trimethylbenzene (TMB as the swelling agent to explore the effect of pore size on final adsorbent properties. The pore expanded MCM-41 was also grafted with (3-Aminopropyltriethoxysilane (APTES to determine the optimal pore size for CO2 adsorption. The pore-expanded mesoporous MCM-41s showed relatively less structural regularity but significant increments of pore diameter (4.64 to 7.50 nm; the fraction of mesopore volume also illustrated an increase. The adsorption heat values were correlated with the order of the adsorption capacities for pore expanded MCM-41s. After amine functionalization, the adsorption capacities and heat values showed a significant increase. APTES-grafted pore-expanded MCM-41s depicted a high potential for CO2 capture regardless of the major drawback of the high energy required for regeneration.

  6. Difficulties of supercurrents in narrow pores of 3He-A

    International Nuclear Information System (INIS)

    Thuneberg, E.V.; Kurkijaervi, J.

    1980-01-01

    We consider resistanceless supercurrents through narrow pores and find such currents to vanish in most cases because of end effects at the entries and exists of the pores. Under pressure dc-supercurrents are found to arise. (author)

  7. Capillary pressure at irregularly shaped pore throats: Implications for water retention characteristics

    Science.gov (United States)

    Suh, Hyoung Suk; Kang, Dong Hun; Jang, Jaewon; Kim, Kwang Yeom; Yun, Tae Sup

    2017-12-01

    The random shapes of pore throats in geomaterials hinder accurate estimation of capillary pressure, and conventional pore network models that simply use the Young-Laplace equation assuming circular pore throats overestimate the capillary pressure. As a solution to this problem that does not complicate the pore network model or slow its implementation, we propose a new morphological analysis method to correlate the capillary pressure at an irregular pore channel with its cross-sectional geometry using lattice Boltzmann (LB) simulation and Mayer and Stowe-Princen theory. Geometry-based shape factors for pore throats are shown here to correlate strongly with the capillary pressure obtained by LB simulation. Water retention curves obtained by incorporating the morphological calibration into conventional pore network simulation and their correlative scheme agree well with experimental data. The suggested method is relevant to pore-scale processes such as geological CO2 sequestration, methane bubbling from wetlands, and enhanced carbon recovery.

  8. Effect of pore structure on chemico-osmotic, diffusion and hydraulic properties of mud-stones

    International Nuclear Information System (INIS)

    Takeda, M.; Manaka, M.; Ito, K.; Miyoshi, S.; Tokunaga, T.

    2012-01-01

    Formations in the Horonobe research area of Japan, where the Japan Atomic Energy Agency (JAEA) has been operating an Underground Research Laboratory. The rock samples are of cylindrical shape with 50 mm in diameter and 10 mm in length. The rock samples were immersed in 0.1 M NaCl solutions before experiments. The densities, specific surface area and cation exchange capacity were measured for the remains of drill cores from which the samples were taken. Pore radius distribution, average pore radius and porosity were also evaluated for each drill cores by mercury porosimetry. The permeability and chemical-osmosis experiments were performed in sequence on each rock sample under the confining pressures simulating in-situ effective stress condition. 0.1 M NaCl solution was used as permeant fluid in the permeability experiment, and the same solution was used as initial solution in the subsequent chemical-osmosis experiment. In the permeability experiment, a constant pressure was applied to the upper surface of rock sample. In the chemical-osmosis experiment, the bottom reservoir solution was replaced with 0.6 M NaCl solution. Both experiments were performed with the bottom reservoir isolated from the pressure buffer tank, and the progress of each experiment was monitored by measuring the bottom reservoir pressure. Figure 2 shows the chemico-osmotic, diffusion and hydraulic parameters determined for the Koetoi and Wakkanai mud-stone samples as functions of porosity. The diffusion and hydraulic parameters of these samples generally decrease with the decrease of porosity, while the osmotic efficiency is not a simple function of porosity. A relatively large osmotic efficiency was obtained only from a Wakkanai mud-stone sample with porosity of 0.33. The Wakkanai mud-stone samples have similar average pore radius, ranging from 6.8 to 7.6 nm; however, the Wakkanai mud-stone samples without large osmotic efficiency have bimodal pore structures. These suggest that even if small size pores

  9. Study of the Mechanical Properties and Vibration Isolation Performance of a Molecular Spring Isolator

    Directory of Open Access Journals (Sweden)

    Muchun Yu

    2016-01-01

    Full Text Available Molecular Spring Isolator (MSI is a novel passive vibration isolation technique, providing High-Static-Low-Dynamic (HSLD stiffness based on the use of molecular spring material. The molecular spring material is a solid-liquid mixture consisting of water and hydrophobic nanoporous materials. Under a certain level of external pressure, water molecules can intrude into the hydrophobic pores of nanoporous materials, developing an additional solid-liquid interface. Such interfaces are able to store, release, and transform mechanical energy, providing properties like mechanical spring. Having been only recently developed, the basic mechanic properties of a MSI have not been studied in depth. This paper focuses on the stiffness influence factors, the dynamic frequency response, and the vibration isolation performance of a MSI; these properties help engineers to design MSIs for different engineering applications. First, the working mechanism of a MSI is introduced from a three-dimensional general view of the water infiltration massive hydrophobic nanoporous pores. Next, a wide range of influence factors on the stiffness properties of MSI are studied. In addition, the frequency response functions (FRFs of the MSI vibration isolation system are studied utilizing the matching method based on equivalent piecewise linear (EPL system. Fi