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Sample records for high permeability layers

  1. High-frequency permeability in double-layered structure of amorphous Co-Ta-Zr films

    Ochiai, Y.; Hayakawa, M.; Hayashi, K.; Aso, K.

    1988-01-01

    The high-frequency permeability of amorphous Co-Ta-Zr films was studied and the frequency dependence was described in terms of the eddy-current-loss formula. For the double-layered structure intervened with SiO 2 film, the degradation of the permeability became apparent with the decrease of SiO 2 thickness

  2. A low-frequency asymptotic model of seismic reflection from a high-permeability layer

    Silin, Dmitriy; Goloshubin, Gennady

    2009-03-01

    Analysis of compression wave propagation through a high-permeability layer in a homogeneous poroelastic medium predicts a peak of reflection in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir thickness. This result is obtained through a low-frequency asymptotic analysis of the Biot's model of poroelasticity. A new physical interpretation of some coefficients of the classical poroelasticity is a result of the derivation of the main equations from the Hooke's law, momentum and mass balance equations, and the Darcy's law. The velocity of wave propagation, the attenuation factor, and the wave number, are expressed in the form of power series with respect to a small dimensionless parameter. The latter is equal to the product of the kinematic reservoir fluid mobility, an imaginary unit, and the frequency of the signal. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave reflection from a thin highly-permeable layer (a lens). The practical implications of the theory developed here are seismic modeling, inversion, and attribute analysis.

  3. Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer

    Lobo, Carlos M. S.; Tosin, Giancarlo; Baader, Johann E.; Colnago, Luiz A.

    2017-10-01

    In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers.

  4. Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer.

    Lobo, Carlos M S; Tosin, Giancarlo; Baader, Johann E; Colnago, Luiz A

    2017-10-01

    In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Anti-fouling and high water permeable forward osmosis membrane fabricated via layer by layer assembly of chitosan/graphene oxide

    Salehi, Hasan; Rastgar, Masoud; Shakeri, Alireza

    2017-08-01

    To date, forward osmosis (FO) has received considerable attention due to its potential application in seawater desalination. FO does not require external hydraulic pressure and consequently is believed to have a low fouling propensity. Despite the numerous privileges of FO process, a major challenge ahead for its development is the lack of high performance membranes. In this study, we fabricated a novel highly-efficient FO membrane using layer-by-layer (LbL) assembly of positive chitosan (CS) and negative graphene oxide (GO) nanosheets via electrostatic interaction on a porous support layer. The support layer was prepared by blending hydrophilic sulfonated polyethersulfone (SPES) into polyethersulfone (PES) matrix using wet phase inversion process. Various characterization techniques were used to confirm successful fabrication of LbL membrane. The number of layers formed on the SPES-PES support layer was easily adjusted by repeating the CS and GO deposition cycles. Thin film composite (TFC) membrane was also prepared by the same SPES-PES support layer and polyamide (PA) active layer to compare membranes performances. The water permeability and salt rejection of the fabricated membranes were obtained by two kinds of draw solutions (including Na2SO4 and sucrose) under two different membrane orientations. The results showed that membrane coated by a CS/GO bilayers had water flux of 2-4 orders of magnitude higher than the TFC one. By increasing the number of CS/GO bilayers, the selectivity of the LbL membrane was improved. The novel fabricated LbL membrane showed better fouling resistance than the TFC one in the feed solution containing 200 ppm of sodium alginate as a foulant model.

  6. The mechanism of coking pressure generation I: Effect of high volatile matter coking coal, semi-anthracite and coke breeze on coking pressure and plastic coal layer permeability

    Seiji Nomura; Merrick Mahoney; Koichi Fukuda; Kenji Kato; Anthony Le Bas; Sid McGuire [Nippon Steel Corporation, Chiba (Japan). Environment and Process Technology Center

    2010-07-15

    One of the most important aspects of the cokemaking process is to control and restrain the coking pressure since excessive coking pressure tends to lead to operational problems and oven wall damage. Therefore, in order to understand the mechanism of coking pressure generation, the permeability of the plastic coal layer and the coking pressure for the same single coal and the same blended coal were measured and the relationship between them was investigated. Then the 'inert' (pressure modifier) effect of organic additives such as high volatile matter coking coal, semi-anthracite and coke breeze was studied. The coking pressure peak for box charging with more uniform bulk density distribution was higher than that for top charging. It was found that the coking pressure peaks measured at different institutions (NSC and BHPBilliton) by box charging are nearly the same. The addition of high volatile matter coking coal, semi-anthracite and coke breeze to a low volatile matter, high coking pressure coal greatly increased the plastic layer permeability in laboratory experiments and correspondingly decreased the coking pressure. It was found that, high volatile matter coking coal decreases the coking pressure more than semi-anthracite at the same plastic coal layer permeability, which indicates that the coking pressure depends not only on plastic coal layer permeability but also on other factors. Coking pressure is also affected by the contraction behavior of the coke layer near the oven walls and a large contraction decreases the coal bulk density in the oven center and hence the internal gas pressure in the plastic layer. The effect of contraction on coking pressure needs to be investigated further. 33 refs., 18 figs., 5 tabs.

  7. An asymptotic model of seismic reflection from a permeable layer

    Silin, D.; Goloshubin, G.

    2009-10-15

    Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir thickness. This result is obtained through a low-frequency asymptotic analysis of Biot's model of poroelasticity. A review of the derivation of the main equations from the Hooke's law, momentum and mass balance equations, and Darcy's law suggests an alternative new physical interpretation of some coefficients of the classical poroelasticity. The velocity of wave propagation, the attenuation factor, and the wave number, are expressed in the form of power series with respect to a small dimensionless parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave reflection from a thin highly-permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic modeling, inversion, and at-tribute analysis.

  8. Influence of Core Permeability on Accropode Armour Layer Stability

    Burcharth, H. F.; Christensen, M.; Jensen, T.

    1998-01-01

    Hedar and van der Meer studied the influence of core permeability on the stability of two layer rock armour. In both cases a significant influence was found. However, it is to be expected that for single layer armour there will be an even larger influence on the core permeability. This is because...... the dissipation of wave energy in single layer armour will e smaller than in double layer armour, thus giving room for larger flow velocities in and over armour layer On this background a laboratory stud of single layer Accropode stability was undertaken at Aalborg University in 1995. The test results as well...

  9. Modelling the effects of porous and semi-permeable layers on corrosion processes

    King, F.; Kolar, M.; Shoesmith, D.W.

    1996-09-01

    Porous and semi-permeable layers play a role in many corrosion processes. Porous layers may simply affect the rate of corrosion by affecting the rate of mass transport of reactants and products to and from the corroding surface. Semi-permeable layers can further affect the corrosion process by reacting with products and/or reactants. Reactions in semi-permeable layers include redox processes involving electron transfer, adsorption, ion-exchange and complexation reactions and precipitation/dissolution processes. Examples of porous and semi-permeable layers include non-reactive salt films, precipitate layers consisting of redox-active species in multiple oxidation states (e.g., Fe oxide films), clay and soil layers and biofilms. Examples of these various types of processes will be discussed and modelling techniques developed from studies for the disposal of high-level nuclear waste presented. (author). 48 refs., 1 tab., 12 figs

  10. Permeability of highly compacted bentonite

    Pusch, R.

    1980-12-01

    The object of the study was the water flow through the bentonite which is caused by hydraulic gradients. The study comprised laboratory tests and theoretical considerations. It was found that high bulk densities reduced the permeability to very low values. It was concluded that practically impervious conditions prevail when the gradients are low. Thus with a regional gradient of 10 -2 and a premeability of 10 -13 m/s the flow rate will not be higher than approximately 1 mm in 30 000 years. (G.B.)

  11. Bioinspired Layer-by-Layer Microcapsules Based on Cellulose Nanofibers with Switchable Permeability

    Paulraj, Thomas; Riazanova, Anastasia V; Yao, Kun

    2017-01-01

    Green, all-polysaccharide based microcapsules with mechanically robust capsule walls and fast, stimuli-triggered, and switchable permeability behavior show great promise in applications based on selective and timed permeability. Taking a cue from nature, the build-up and composition of plant......-by-layer technique on sacrificial CaCO3 templates, using plant polysaccharides (pectin, cellulose nanofibers, and xyloglucan) only. In water, the capsule wall was permeable to labeled dextrans with a hydrodynamic diameter of ∼6.6 nm. Upon exposure to NaCl, the porosity of the capsule wall quickly changed allowing...

  12. Effect of dissolved oxygen manipulation on diffusive emissions from NAPL-impacted low permeability soil layers.

    Clifton, Lisa M; Dahlen, Paul R; Johnson, Paul C

    2014-05-06

    Aquifer physical model experiments were performed to investigate if diffusive emissions from nonaqueous phase liquid (NAPL)-impacted low-permeability layers into groundwater moving through adjacent NAPL-free high-permeability layers can be reduced by creating an aerobic biotreatment zone at the interface between the two, and if over time that leads to reduced emissions after treatment ceases. Experiments were performed in two 1.2-m long × 1.2-m high × 5.4 cm wide stainless steel tanks; each with a high-permeability sand layer overlying a low-permeability crushed granite layer containing a NAPL mixture of indane and benzene. Each tank was water-saturated with horizontal flow primarily through the sand layer. The influent water was initially deoxygenated and the emissions and concentration distributions were allowed to reach near-steady conditions. The influent dissolved oxygen (DO) level was increased stepwise to 6.5-8.5 mg/L and 17-20 mg/L, and then decreased back to deoxygenated conditions. Each condition was maintained for at least 45 days. Relative to the near-steady benzene emission at the initial deoxygenated condition, the emission was reduced by about 70% when the DO was 6.5-8.5 mg/L, 90% when the DO was 17-20 mg/L, and ultimately 60% when returning to low DO conditions. While the reductions were substantial during treatment, longer-term reductions after 120 d of elevated DO treatment, relative to an untreated condition predicted by theory, were low: 29% and 6% in Tank 1 and Tank 2, respectively. Results show a 1-2 month lag between the end of DO delivery and rebound to the final near-steady emissions level. This observation has implications for post-treatment performance monitoring sampling at field sites.

  13. Method and Apparatus for High-Permeability Magnetostrictive/Piezo-Fiber Laminates Having Colossal, Near-Ideal Magnetoelectricity

    2007-01-01

    An ME composite laminate of at least one (1-3) piezo-fiber layer coupled with high-permeability alloy magnetostrictive layers, optionally formed of FeBSiC or equivalent. The composite laminate alternates the (1-3) piezo-fiber and high-permeability alloy magnetostrictive layers in a stacked manner. Optionally, the magnetization direction of the high-permeability alloy magnetostrictive layers and polarization direction of the piezo-fiber layer are an (L-L) arrangement. Optionally, thin film pol...

  14. Transverse Chemotactic Migration of Bacteria from High to Low Permeability Regions in a Dual Permeability Porous Microfluidic Device

    Singh, R.; Olson, M. S.

    2011-12-01

    Low permeability regions sandwiched between high permeability regions such as clay lenses are difficult to treat using conventional treatment methods. Trace concentrations of contaminants such as non-aqueous phase liquids (NAPLs) remain trapped in these regions and over the time diffuse out into surrounding water thereby acting as a long term source of groundwater contamination. Bacterial chemotaxis (directed migration toward a contaminant source), may be helpful in enhancing bioremediation of such contaminated sites. This study is focused on simulating a two-dimensional dual-permeability groundwater contamination scenario using microfluidic devices and evaluating transverse chemotactic migration of bacteria from high to low permeability regions. A novel bi-layer polydimethylsiloxane (PDMS) microfluidic device was fabricated using photolithography and soft lithography techniques to simulate contamination of a dual- permeability region due to leakage from an underground storage tank into a low permeability region. This device consists of a porous channel through which a bacterial suspension (Escherchia Coli HCB33) is flown and another channel for injecting contaminant/chemo-attractant (DL-aspertic acid) into the porous channel. The pore arrangement in the porous channel contains a 2-D low permeability region surrounded by high permeability regions on both sides. Experiments were performed under chemotactic and non-chemotactic (replacing attractant with buffer solution in the non porous channel) conditions. Images were captured in transverse pore throats at cross-sections 4.9, 9.8, and 19.6 mm downstream from the attractant injection point and bacteria were enumerated in the middle of each pore throat. Bacterial chemotaxis was quantified in terms of the change in relative bacterial counts in each pore throat at cross-sections 9.8 and 19.6 mm with respect to counts at the cross-section at 4.9 mm. Under non-chemotactic conditions, relative bacterial count was observed

  15. Effect of a low-permeability layer on calculated gas flow at Yucca Mountain

    Lu, Ning; Amter, S.; Ross, B.

    1990-01-01

    Yucca Mountain is being studied to determine its suitability as a location for a high-level nuclear waste repository. Amter and Ross developed a model called TGIF (Topographic Induced Flow) to simulate gas flow under Yucca Mountain. The TGIF model differs significantly from previous gas flow models. It uses a governing equation that is based on the concept of freshwater head, thus avoiding the numerical problems associated with the near-cancellation of the forces due to gravity and the pressure gradient. Unlike most other models, dipping, layered media can be simulated. This paper describes a systematic sensitivity study that was designed to test several aspects of the TGIF model when used to simulate gas flow under Yucca Mountain. Values of three important inputs to the model were systematically varied to form a matrix of 80 runs. The matrix consisted of five values of permeability contrast between a bedded tuff layer and surrounding welded units (in all cases, bulk permeabilities were used to represent the combined effect of both fractures and matrix permeability), four temperature profiles representing different stages of repository cooldown, and four finite-difference grids

  16. Effect of a low-permeability layer on calculated gas flow at Yucca Mountain

    Lu, Ning; Amter, S.; Ross, B. [Disposal Safety, Inc., Washington, DC (USA)

    1990-12-31

    Yucca Mountain is being studied to determine its suitability as a location for a high-level nuclear waste repository. Amter and Ross developed a model called TGIF (Topographic Induced Flow) to simulate gas flow under Yucca Mountain. The TGIF model differs significantly from previous gas flow models. It uses a governing equation that is based on the concept of freshwater head, thus avoiding the numerical problems associated with the near-cancellation of the forces due to gravity and the pressure gradient. Unlike most other models, dipping, layered media can be simulated. This paper describes a systematic sensitivity study that was designed to test several aspects of the TGIF model when used to simulate gas flow under Yucca Mountain. Values of three important inputs to the model were systematically varied to form a matrix of 80 runs. The matrix consisted of five values of permeability contrast between a bedded tuff layer and surrounding welded units (in all cases, bulk permeabilities were used to represent the combined effect of both fractures and matrix permeability), four temperature profiles representing different stages of repository cooldown, and four finite-difference grids.

  17. Mechanics of layered anisotropic poroelastic media with applications to effective stress for fluid permeability

    Berryman, J.G.

    2010-06-01

    The mechanics of vertically layered porous media has some similarities to and some differences from the more typical layered analysis for purely elastic media. Assuming welded solid contact at the solid-solid interfaces implies the usual continuity conditions, which are continuity of the vertical (layering direction) stress components and the horizontal strain components. These conditions are valid for both elastic and poroelastic media. Differences arise through the conditions for the pore pressure and the increment of fluid content in the context of fluid-saturated porous media. The two distinct conditions most often considered between any pair of contiguous layers are: (1) an undrained fluid condition at the interface, meaning that the increment of fluid content is zero (i.e., {delta}{zeta} = 0), or (2) fluid pressure continuity at the interface, implying that the change in fluid pressure is zero across the interface (i.e., {delta}p{sub f} = 0). Depending on the types of measurements being made on the system and the pertinent boundary conditions for these measurements, either (or neither) of these two conditions might be directly pertinent. But these conditions are sufficient nevertheless to be used as thought experiments to determine the expected values of all the poroelastic coefficients. For quasi-static mechanical changes over long time periods, we expect drained conditions to hold, so the pressure must then be continuous. For high frequency wave propagation, the pore-fluid typically acts as if it were undrained (or very nearly so), with vanishing of the fluid increment at the boundaries being appropriate. Poroelastic analysis of both these end-member cases is discussed, and the general equations for a variety of applications to heterogeneous porous media are developed. In particular, effective stress for the fluid permeability of such poroelastic systems is considered; fluid permeabilities characteristic of granular media or tubular pore shapes are treated

  18. High-permeability criterion for BCS classification: segmental/pH dependent permeability considerations.

    Dahan, Arik; Miller, Jonathan M; Hilfinger, John M; Yamashita, Shinji; Yu, Lawrence X; Lennernäs, Hans; Amidon, Gordon L

    2010-10-04

    The FDA classifies a drug substance as high-permeability when the fraction of dose absorbed (F(abs)) in humans is 90% or higher. This direct correlation between human permeability and F(abs) has been recently controversial, since the β-blocker sotalol showed high F(abs) (90%) and low Caco-2 permeability. The purpose of this study was to investigate the scientific basis for this disparity between permeability and F(abs). The effective permeabilities (P(eff)) of sotalol and metoprolol, a FDA standard for the low/high P(eff) class boundary, were investigated in the rat perfusion model, in three different intestinal segments with pHs corresponding to the physiological pH in each region: (1) proximal jejunum, pH 6.5; (2) mid small intestine, pH 7.0; and (3) distal ileum, pH 7.5. Both metoprolol and sotalol showed pH-dependent permeability, with higher P(eff) at higher pH. At any given pH, sotalol showed lower permeability than metoprolol; however, the permeability of sotalol determined at pH 7.5 exceeded/matched metoprolol's at pH 6.5 and 7.0, respectively. Physicochemical analysis based on ionization, pK(a) and partitioning of these drugs predicted the same trend and clarified the mechanism behind these observed results. Experimental octanol-buffer partitioning experiments confirmed the theoretical curves. An oral dose of metoprolol has been reported to be completely absorbed in the upper small intestine; it follows, hence, that metoprolol's P(eff) value at pH 7.5 is not likely physiologically relevant for an immediate release dosage form, and the permeability at pH 6.5 represents the actual relevant value for the low/high permeability class boundary. Although sotalol's permeability is low at pH 6.5 and 7.0, at pH 7.5 it exceeds/matches the threshold of metoprolol at pH 6.5 and 7.0, most likely responsible for its high F(abs). In conclusion, we have shown that, in fact, there is no discrepancy between P(eff) and F(abs) in sotalol's absorption; the data emphasize that

  19. Laboratory-scale measurements of effective relative permeability for layered sands

    Butts, M.G.; Korsgaard, S.

    1996-12-31

    Predictions of the impact of remediation or the extent of contamination resulting from spills of gasoline, solvents and other petroleum products, must often be made in complex geological environments. Such problems can be treated by introducing the concept of effective parameters that incorporate the effects of soil layering or other heterogeneities into a large-scale flow description. Studies that derive effective multiphase parameters are few, and approximations are required to treat the non-linear multiphase flow equations. The purpose of this study is to measure effective relative permeabilities for well-defined multi-layered soils at the laboratory scale. Relative permeabilities were determined for homogeneous and layered, unconsolidated sands using the method of Jones and Roszelle (1978). The experimental data show that endpoint relative permeabilities are important in defining the shape of the relative permeability curves, but these cannot be predicted by estimation methods base on capillary pressure data. The most significant feature of the measured effective relative permeability curves is that the entrapped (residual) oil saturation is significantly larger than the residual saturation of the individual layers. This observation agrees with previous theoretical predictions of large-scale entrapment Butts, 1993 and (1995). Enhanced entrapment in heterogeneous soils has several important implications for spill remediation, for example, the reduced efficiency of direct recovery. (au) 17 refs.

  20. Laboratory-scale measurements of effective relative permeability for layered sands

    Butts, M.G.; Korsgaard, S.

    1996-01-01

    Predictions of the impact of remediation or the extent of contamination resulting from spills of gasoline, solvents and other petroleum products, must often be made in complex geological environments. Such problems can be treated by introducing the concept of effective parameters that incorporate the effects of soil layering or other heterogeneities into a large-scale flow description. Studies that derive effective multiphase parameters are few, and approximations are required to treat the non-linear multiphase flow equations. The purpose of this study is to measure effective relative permeabilities for well-defined multi-layered soils at the laboratory scale. Relative permeabilities were determined for homogeneous and layered, unconsolidated sands using the method of Jones and Roszelle (1978). The experimental data show that endpoint relative permeabilities are important in defining the shape of the relative permeability curves, but these cannot be predicted by estimation methods base on capillary pressure data. The most significant feature of the measured effective relative permeability curves is that the entrapped (residual) oil saturation is significantly larger than the residual saturation of the individual layers. This observation agrees with previous theoretical predictions of large-scale entrapment Butts, 1993 and (1995). Enhanced entrapment in heterogeneous soils has several important implications for spill remediation, for example, the reduced efficiency of direct recovery. (au) 17 refs

  1. Intestinal permeability study of minoxidil: assessment of minoxidil as a high permeability reference drug for biopharmaceutics classification.

    Ozawa, Makoto; Tsume, Yasuhiro; Zur, Moran; Dahan, Arik; Amidon, Gordon L

    2015-01-05

    The purpose of this study was to evaluate minoxidil as a high permeability reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil was determined in in situ intestinal perfusion studies in rodents and permeability studies across Caco-2 cell monolayers. The permeability of minoxidil was compared with that of metoprolol, an FDA reference drug for BCS classification. In rat perfusion studies, the permeability of minoxidil was somewhat higher than that of metoprolol in the jejunum, while minoxidil showed lower permeability than metoprolol in the ileum. The permeability of minoxidil was independent of intestinal segment, while the permeability of metoprolol was region-dependent. Similarly, in mouse perfusion study, the jejunal permeability of minoxidil was 2.5-fold higher than that of metoprolol. Minoxidil and metoprolol showed similar permeability in Caco-2 study at apical pH of 6.5 and basolateral pH of 7.4. The permeability of minoxidil was independent of pH, while metoprolol showed pH-dependent transport in Caco-2 study. Minoxidil exhibited similar permeability in the absorptive direction (AP-BL) in comparison with secretory direction (BL-AP), while metoprolol had higher efflux ratio (ER > 2) at apical pH of 6.5 and basolateral pH of 7.4. No concentration-dependent transport was observed for either minoxidil or metoprolol transport in Caco-2 study. Verapamil did not alter the transport of either compounds across Caco-2 cell monolayers. The permeability of minoxidil was independent of both pH and intestinal segment in intestinal perfusion studies and Caco-2 studies. Caco-2 studies also showed no involvement of carrier mediated transport in the absorption process of minoxidil. These results suggest that minoxidil may be an acceptable reference drug for BCS high permeability classification. However, minoxidil exhibited higher jejunal permeability than metoprolol and thus to use minoxidil as a reference drug would raise the

  2. Soil gas measurements at high permeabilities and below foundation depth

    Johner, H.U; Surbeck, H.

    2000-01-01

    We started a project of soil gas measurements beneath houses. Since the foundations of houses often lie deeper than 0.5 to 1 m - the depth where soil gas measurements are often made - the first approach was to apply the method developed previously to deeper soil layers. The radon availability index (RAI), which was defined empirically, proved to be a reliable indicator for radon problems in nearby houses. The extreme values of permeability, non-Darcy flow and scale dependence of permeability stimulated the development of a multi-probe method. A hydrological model was applied to model the soil gas transport. The soil gas measurements below foundation depth provided a wealth of new information. A good classification of soil properties could be achieved. If soil gas measurements are to be made, the low permeability layer has to be traversed. A minimum depth of 1 .5 m is suggested, profiles to below the foundation depth are preferable. There are also implications for mitigation works. A sub-slab suction system should reach the permeable layer to function well. This also holds for radon wells. If a house is located on a slope, it is most convenient to install the sub-slab suction system on the hillside, as the foundation reaches the deepest levels there

  3. Turbulent thermal boundary layer on a permeable flat plate

    Vigdorovich, I. I.

    2007-01-01

    Scaling laws are established for the profiles of temperature, turbulent heat flux, rms temperature fluctuation, and wall heat transfer in the turbulent boundary layer on a flat plate with transpiration. In the case of blowing, the temperature distribution represented in scaling variables outside the viscous sublayer has a universal form known from experimental data for flows over impermeable flat plates. In the case of suction, the temperature distribution is described by a one-parameter family of curves. A universal law of heat transfer having the form of a generalized Reynolds analogy provides a basis for representation of the heat flux distributions corresponding to different Reynolds numbers and transpiration velocities in terms of a function of one variable. The results are obtained without invoking any special closure hypotheses

  4. Investigation on the Permeability Evolution of Gypsum Interlayer Under High Temperature and Triaxial Pressure

    Tao, Meng; Yechao, You; Jie, Chen; Yaoqing, Hu

    2017-08-01

    The permeability of the surrounding rock is a critical parameter for the designing and assessment of radioactive waste disposal repositories in the rock salt. Generally, in the locations that are chosen for radioactive waste storage, the bedded rock salt is a sedimentary rock that contains NaCl and Na2SO4. Most likely, there are also layers of gypsum ( {CaSO}_{ 4} \\cdot 2 {H}_{ 2} {O)} present in the salt deposit. Radioactive wastes emit a large amount of heat and hydrogen during the process of disposal, which may result in thermal damage of the surrounding rocks and cause a great change in their permeability and tightness. Therefore, it is necessary to investigate the permeability evolution of the gypsum interlayer under high temperature and high pressure in order to evaluate the tightness and security of the nuclear waste repositories in bedded rock salt. In this study, a self-designed rock triaxial testing system by which high temperature and pressure can be applied is used; the μCT225kVFCB micro-CT system is also employed to investigate the permeability and microstructure of gypsum specimens under a constant hydrostatic pressure of 25 MPa, an increasing temperature (ranging from 20 to 650 °C), and a variable inlet gas pressure (1, 2, 4, 6 MPa). The experimental results show: (a) the maximum permeability measured during the whole experiment is less than 10-17 m2, which indicates that the gypsum interlayer has low permeability under high temperature and pressure that meet the requirements for radioactive waste repository. (b) Under the same temperature, the permeability of the gypsum specimen decreases at the beginning and then increases as the pore pressure elevates. When the inlet gas pressure is between 0 and 2 MPa, the Klinkenberg effect is very pronounced. Then, as the pore pressure increases, the movement behavior of gas molecules gradually changes from free motion to forced directional motion. So the role of free movement of gas molecules gradually

  5. Stable catalyst layers for hydrogen permeable composite membranes

    Way, J. Douglas; Wolden, Colin A

    2014-01-07

    The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

  6. Stormwater infiltration and surface runoff pollution reduction performance of permeable pavement layers.

    Niu, Zhi-Guang; Lv, Zhi-Wei; Zhang, Ying; Cui, Zhen-Zhen

    2016-02-01

    In this paper, the laboratory-scale permeable pavement layers, including a surface permeable brick layer, coarse sand bedding layers (thicknesses = 2, 3.5, and 5 cm), and single-graded gravel sub-base layers (thicknesses = 15, 20, 25, and 30 cm), were built to evaluate stormwater infiltration and surface runoff pollution reduction performance. And, the infiltration rate (I) and concentrations of suspended solids (SS), total phosphorus (TP), chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN) were measured under the simulated rainfall intensity of 72.4 mm/h over duration of 60 min. The results indicate that the thickness factor primarily influences the infiltration rate and pollutant removal rate. The highest steady infiltration rate was for surface brick layer 51.0 mm/h, for 5-cm sand bedding layer 32.3 mm/h, and for 30-cm gravel sub-base layer 42.3 mm/h, respectively. The SS average removal rate was relative higher (79.8 ∼ 98.6 %) for all layers due to the interception and filtration. The average removal rates of TP and COD were for surface layer 71.2 and 24.1 %, for 5-cm bedding layer 54.8 and 9.0 %, and for 20-cm sub-base layer 72.2 and 26.1 %. Ammonia nitrogen and TN cannot steadily be removed by layers according to the experiment results. The optimal thickness of bedding sands was 5 cm, and that of sub-base gravels was 20 ∼ 30 cm.

  7. Effect of plate permeability on nonlinear stability of the asymptotic suction boundary layer.

    Wedin, Håkan; Cherubini, Stefania; Bottaro, Alessandro

    2015-07-01

    The nonlinear stability of the asymptotic suction boundary layer is studied numerically, searching for finite-amplitude solutions that bifurcate from the laminar flow state. By changing the boundary conditions for disturbances at the plate from the classical no-slip condition to more physically sound ones, the stability characteristics of the flow may change radically, both for the linearized as well as the nonlinear problem. The wall boundary condition takes into account the permeability K̂ of the plate; for very low permeability, it is acceptable to impose the classical boundary condition (K̂=0). This leads to a Reynolds number of approximately Re(c)=54400 for the onset of linearly unstable waves, and close to Re(g)=3200 for the emergence of nonlinear solutions [F. A. Milinazzo and P. G. Saffman, J. Fluid Mech. 160, 281 (1985); J. H. M. Fransson, Ph.D. thesis, Royal Institute of Technology, KTH, Sweden, 2003]. However, for larger values of the plate's permeability, the lower limit for the existence of linear and nonlinear solutions shifts to significantly lower Reynolds numbers. For the largest permeability studied here, the limit values of the Reynolds numbers reduce down to Re(c)=796 and Re(g)=294. For all cases studied, the solutions bifurcate subcritically toward lower Re, and this leads to the conjecture that they may be involved in the very first stages of a transition scenario similar to the classical route of the Blasius boundary layer initiated by Tollmien-Schlichting (TS) waves. The stability of these nonlinear solutions is also investigated, showing a low-frequency main unstable mode whose growth rate decreases with increasing permeability and with the Reynolds number, following a power law Re(-ρ), where the value of ρ depends on the permeability coefficient K̂. The nonlinear dynamics of the flow in the vicinity of the computed finite-amplitude solutions is finally investigated by direct numerical simulations, providing a viable scenario for

  8. Effect of high density lipoproteins on permeability of rabbit aorta to low density lipoproteins

    Klimov, A.N.; Popov, V.A.; Nagornev, V.A.; Pleskov, V.M.

    1985-01-01

    A study was made on the effect of high density lipoproteins (HDL) on the permeability of rabbit aorta to low density lipoproteins (LDL) after intravenous administration of human HDL and human ( 125 I)LDL to normal and hypercholesterolemic rabbits. Evaluation of radioactivity in plasma and aorta has shown that the administration of a large dose of HDL decreased the aorta permeability rate for ( 125 I)LDL on an average by 19% in normal rabbits, and by 45% in rabbits with moderate hypercholesterolemia. A historadiographic study showed that HDL also decreased the vessel wall permeability to ( 125 I)LDL in normal and particularly in hypercholesterolemic animals. The suggestion was made that HDL at very high molar concentration can hamper LDL transportation through the intact endothelial layer into the intima due to the ability of HDL to compete with LDL in sites of low affinity on the surface of endothelial cells. (author)

  9. Effective High-Frequency Permeability of Compacted Metal Powders

    Volkovskaya, I. I.; Semenov, V. E.; Rybakov, K. I.

    2018-03-01

    We propose a model for determination of the effective complex permeability of compacted metal-powder media. It is based on the equality of the magnetic moment in a given volume of the media with the desired effective permeability to the total magnetic moment of metal particles in the external high-frequency magnetic field, which arises due to excitation of electric eddy currents in the particles. Calculations within the framework of the proposed model allow us to refine the values of the real and imaginary components of the permeability of metal powder compacts in the microwave band. The conditions of applicability of the proposed model are formulated, and their fulfillment is verified for metal powder compacts in the microwave and millimeter wavelength bands.

  10. 21 CFR 876.5860 - High permeability hemodialysis system.

    2010-04-01

    ... hemodialysis system. (a) Identification. A high permeability hemodialysis system is a device intended for use as an artificial kidney system for the treatment of patients with renal failure, fluid overload, or... system removes toxins or excess fluid from the patient's blood using the principles of convection (via a...

  11. Annealing behavior of high permeability amorphous alloys

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co 71 4 Fe 4 6 Si 9 6 B 14 4 were investigated. Annealing this alloy below 400 0 C results in magnetic hardening; annealing above 400 0 C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation

  12. A fractal model for predicting permeability and liquid water relative permeability in the gas diffusion layer (GDL) of PEMFCs

    He, Guangli; Zhao, Zongchang; Ming, Pingwen; Abuliti, Abudula; Yin, Caoyong

    In this study, a fractal model is developed to predict the permeability and liquid water relative permeability of the GDL (TGP-H-120 carbon paper) in proton exchange membrane fuel cells (PEMFCs), based on the micrographs (by SEM, i.e. scanning electron microscope) of the TGP-H-120. Pore size distribution (PSD), maximum pore size, porosity, diameter of the carbon fiber, pore tortuosity, area dimension, hydrophilicity or hydrophobicity, the thickness of GDL and saturation are involved in this model. The model was validated by comparison between the predicted results and experimental data. The results indicate that the water relative permeability in the hydrophobicity case is much higher than in the hydrophilicity case. So, a hydrophobic carbon paper is preferred for efficient removal of liquid water from the cathode of PEMFCs.

  13. Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

    Lei, Qinghua; Wang, Xiaoguang; Xiang, Jiansheng; Latham, John-Paul

    2017-12-01

    A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a "through-going" joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for large-scale assessments.

  14. Effects of Pregnant Leach Solution Temperature on the Permeability of Gravelly Drainage Layer of Heap Leaching Structures

    mehdi amini

    2013-12-01

    Full Text Available In copper heap leaching structures, the ore is leached by an acidic solution. After dissolving the ore mineral, the heap is drained off in the acidic solution using a drainage system (consisting of a network of perforated polyethylene pipes and gravelly drainage layers and is, then, transferred to the leaching plant for copper extraction where the copper is extracted and the remaining solution is dripped over the ore heap for re-leaching. In this process, the reaction between the acidic solution and copper oxide ore is exothermal and the pregnant leach solution (PLS, which is drained off the leaching heap, has a higher temperature than the dripped acidic solution. The PLS temperature variations cause some changes in the viscosity and density which affect the gravelly drainage layer's permeability. In this research, a special permeability measuring system was devised for determining the effects of the PLS temperature variations on the permeability coefficient of the gravelly drainage layer of heap leaching structures. The system, consisting of a thermal acid resistant element and a thermocouple, controls the PLS temperature, which helps measure the permeability coefficient of the gravelly drainage layer. The PLS and gravelly drainage layer of Sarcheshmeh copper mine heap leaching structure No. 1 were used in this study. The permeability coefficient of the gravelly soil was measured against the PLS and pure water at temperatures varying between 3°C to 60°C. Also, the viscosity and density of the PLS and pure water were measured at these temperatures and, using existing theoretical relations, the permeability coefficient of the gravel was computed. A comparison between the experimental and theoretical results revealed a good conformity between the two sets of results. Finally, a case (Taft heap leaching structure, Yazd, Iran was studied and its gravelly drainage layer was designed based on the results of the present research.

  15. Notional Permeability

    Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.

    2012-01-01

    Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath

  16. A fractal analytical model for the permeabilities of fibrous gas diffusion layer in proton exchange membrane fuel cells

    Xiao, Boqi; Fan, Jintu; Ding, Feng

    2014-01-01

    The study of water and gas transport through fibrous gas diffusion layer (GDL) is important to the optimization of proton exchange membrane fuel cells (PEMFCs). In this work, analytical models of dimensionless permeability, and water and gas relative permeabilities of fibrous GDL in PEMFCs are derived using fractal theory. In our models, the structure of fibrous GDL is characterized in terms of porosity, tortuosity fractal dimension (D T ), pore area fractal dimensions (d f ), water phase (d f,w ) and gas phase (d f,g ) fractal dimensions. The predicted dimensionless permeability, water and gas relative permeabilities based on the proposed models are in good agreement with experimental data and predictions of numerical simulations reported in the literature. The model reveals that, although water phase and gas phase fractal dimensions strongly depend on porosity, the water and gas relative permeabilities are independent of porosity and are a function of water saturation only. It is also shown that the dimensionless permeability decreases significantly with the increase of tortuosity fractal dimension. On the other hand, there is only a small decrease in the water and gas relative permeabilities when tortuosity fractal dimension increases. One advantage of the proposed analytical model is that it contains no empirical constant, which is normally required in past models

  17. Effect of porosity heterogeneity on the permeability and tortuosity of gas diffusion layers in polymer electrolyte membrane fuel cells

    Nabovati, Aydin; Hinebaugh, James; Bazylak, Aimy; Amon, Cristina H.

    2014-02-01

    In this paper, we study the effect of porosity heterogeneity on the bulk hydrodynamic properties (permeability and tortuosity) of simulated gas diffusion layers (GDLs). The porosity distributions of the heterogeneous reconstructed samples are similar to those previously reported in the literature for Toray TGP-H 120™ GDLs. We use the lattice Boltzmann method to perform pore-level flow simulations in the reconstructed GDL samples. Using the results of pore-level simulations, the effect of porosity distribution is characterized on the predicted in- and cross-plane permeability and tortuosity. It was found that porosity heterogeneity causes a higher in-plane permeability and lower in-plane tortuosity, while the effect is opposite in the cross-plane direction, that is a lower cross-plane permeability and a higher cross-plane tortuosity. We further investigate the effect of adding poly-tetra-fluoro-ethylene (PTFE) & binder material to the reconstructed GDL samples. Three fiber volume percentages of 50, 75, and 100% are considered. Overall, increasing the fiber volume percentage reduces the predicted in- and cross-plane permeability and tortuosity values. A previously reported relationship for permeability of fibrous materials is fitted to the predicted permeability values, and the magnitude of the fitting parameter is reported as a function of fiber volume percentage.

  18. Relationship between permeability and damage in concretes at high temperature

    Dal Pont, St.

    2004-09-01

    Due to its technical and economical advantages, concrete is nowadays the most used building material in civil engineering. Even if its use is known since nearly two centuries, its behavior has not been yet completely explained due to the complexity of its porous microstructure. This fact is quite evident under particular conditions such as, by instance, during an elevation of temperature. This condition can mainly occur in two cases: due to a casualty (e.g. a fire) or in normal use conditions (e.g. storage of nuclear rejects). This work aims at contributing to the study of the phenomena that can be observed in concrete exposed to high temperatures and, in particular, focuses on the study of the evolution of intrinsic permeability. The characterisation of permeability (which is hardly measurable in hot conditions) is necessary for describing and modelling transport phenomena which occur in porous media. An experimental study has been made in collaboration with the CEA. A real-scale hollow cylinder has been instrumented with gauges for studying the evolution of temperature and gas pressure fields inside concrete. Later, the cylinder has been then numerically modelled by means of a thermo-hydro-chemical (THC) and a thermo-hydro-chemo-mechanical (THCM) model. The THC model, implemented by means of the finite volume method, has allowed a first, qualitative study of the behaviour of concrete submitted to high temperature. This model, which, for sake of simplicity, has neglected all mechanical effects, has allowed the description of the main phenomena occurring inside concrete: mass transport, phase changes, microstructure evolution. Later, the modelling has been completed by means of the THCM model using the Hitecosp code, implemented by means of the finite element method at the university of Padua. This code allows a very complete description of the phenomena occurring inside concrete and takes into consideration the mechanical behavior of concrete by means of an

  19. Maladaptively high and low openness: the case for experiential permeability.

    Piedmont, Ralph L; Sherman, Martin F; Sherman, Nancy C

    2012-12-01

    The domain of Openness within the Five-Factor Model (FFM) has received inconsistent support as a source for maladaptive personality functioning, at least when the latter is confined to the disorders of personality included within the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR; APA, ). However, an advantage of the FFM relative to the DSM-IV-TR is that the former was developed to provide a reasonably comprehensive description of general personality structure. Rather than suggest that the FFM is inadequate because the DSM-IV-TR lacks much representation of Openness, it might be just as reasonable to suggest that the DSM-IV-TR is inadequate because it lacks an adequate representation of maladaptive variants of both high and low Openness. This article discusses the development and validation of a measure of these maladaptive variants, the Experiential Permeability Inventory. © 2012 The Authors. Journal of Personality © 2012, Wiley Periodicals, Inc.

  20. Permeability analysis of Asbuton material used as core layers of water resistance in the body of dam

    Rahim, H.; Tjaronge, M. W.; Thaha, A.; Djamaluddin, R.

    2017-11-01

    In order to increase consumption of the local materials and national products, large reserves of Asbuton material about 662.960 million tons in the Buton Islands became an alternative as a waterproof core layer in the body of dam. The Asbuton material was used in this research is Lawele Granular Asphalt (LGA). This study was an experimental study conducted in the laboratory by conducting density testing (content weight) and permeability on Asbuton material. Testing of the Asbuton material used Falling Head method to find out the permeability value of Asbuton material. The data of test result to be analyzed are the relation between compaction energy and density value also relation between density value and permeability value of Asbuton material. The result shows that increases the number of blow apply to the Asbuton material at each layer will increase the density of the Asbuton material. The density value of Asbuton material that satisfies the requirements for use as an impermeable core layer in the dam body is 1.53 grams/cm3. The increase the density value (the weight of the contents) of the Asbuton material will reduce its permeability value of the Asbuton material.

  1. Nanomechanics and sodium permeability of endothelial surface layer modulated by hawthorn extract WS 1442.

    Wladimir Peters

    Full Text Available The endothelial glycocalyx (eGC plays a pivotal role in the physiology of the vasculature. By binding plasma proteins, the eGC forms the endothelial surface layer (ESL which acts as an interface between bloodstream and endothelial cell surface. The functions of the eGC include mechanosensing of blood flow induced shear stress and thus flow dependent vasodilation. There are indications that levels of plasma sodium concentrations in the upper range of normal and beyond impair flow dependent regulation of blood pressure and may therefore increase the risk for hypertension. Substances, therefore, that prevent sodium induced endothelial dysfunction may be attractive for the treatment of cardiovascular disease. By means of combined atomic force-epifluorescence microscopy we studied the impact of the hawthorn (Crataegus spp. extract WS 1442, a herbal therapeutic with unknown mechanism of action, on the mechanics of the ESL of ex vivo murine aortae. Furthermore, we measured the impact of WS 1442 on the sodium permeability of endothelial EA.hy 926 cell monolayer. The data show that (i the ESL contributes by about 11% to the total endothelial barrier resistance for sodium and (ii WS 1442 strengthens the ESL resistance for sodium up to about 45%. This mechanism may explain some of the vasoprotective actions of this herbal therapeutic.

  2. Highly permeable, cement-bounded backfilling mortars for SMA repositories

    Jacobs, F.; Mayer, G.; Wittmann, F.H.

    1994-03-01

    In low- and intermediate-level waste repositories, gas is produced due e.g. to corrosion. This gas must be able to escape from the repository in order to prevent damage to the repository structure. A cement-based backfill should take over this function. For this purpose, the composition of cement-based materials was varied to study their influence on porosity and permeability. In parallel to this study the behaviour of fresh concrete, the liberation of the heat of hydration and the hardened concrete properties were investigated. To characterize the permeability of cement-based materials the following parameters are important: 1) composition of the material (pore fabric), 2) storage conditions (degree of saturation), 3) degree of hydration (age), 4) measuring fluid. A change in the composition of cement-based materials can vary the permeability by ten orders of magnitude. It is shown that, by using dense aggregates, the transport of the fluid takes place through the matrix and along the aggregate/matrix interface. By using porous aggregates the permeability can be increased by two orders of magnitude. In the case of a dense matrix, porous aggregates do not alter the permeability. Increasing the matrix content or interface content increases permeability. Hence light weight mortars are an obvious choice. Like-grained mixes showed higher permeabilities in combination with better mechanical properties but, in comparison to normal mixes, they showed worse flow properties. With the composition cement-: water-: aggregate content 1:0.4:5.33 the likegrained mix with aggregates ranging from 2 to 3 mm proved to be a suitable material. With a low compaction after 28 days this mix reaches a permeability of 4.10 -12 m 2 and an uniaxial cylinder compressive strength of 16 N/mm 2 . (author) 58 figs., 23 tabs., refs

  3. Hydraulic, water-quality, and temperature performance of three types of permeable pavement under high sediment loading conditions

    Selbig, William R.; Buer, Nicolas

    2018-05-11

    three permeable surfaces.Temperatures below each permeable surface generally followed changes in air temperature with a more gradual response observed in deeper layers. Therefore, permeable pavement may do little to mitigate heated runoff during summer. During winter, deeper layers remained above freezing even when air temperature was below freezing. Although temperatures were not high enough to melt snow or ice accumulated on the surface, temperatures below each permeable pavement did allow void spaces to remain open, which promoted infiltration of melted ice and snow as air temperatures rose above freezing. These open void spaces could potentially reduce the need for application of deicing agents in winter because melted snow and ice would infiltrate, thereby preventing refreezing of pooled water in what is known as the “black ice” effect.

  4. Design, installation, and performance of a multi-layered permeable reactive barrier, Los Alamos National Laboratory

    Kaszuba, John P.; Longmire, Patrick A.; Strietelmeier, Elizabeth A.; Taylor, Tammy P.; Den-Baars, Peter S.

    2004-01-01

    A multi-layered permeable reactive barrier (PRB) has been installed in Mortandad Canyon, on the Pajarito Plateau in the north-central part of LANL, to demonstrate in-situ treatment of a suite of contaminants with dissimilar geochemical properties. The PRB will also mitigate possible vulnerabilities from downgradient contaminant movement within alluvial and deeper perched groundwater. Mortandad Canyon was selected as the location for this demonstration project because the flow of alluvial groundwater is constrained by the geology of the canyon, a large network of monitoring wells already were installed along the canyon reach, and the hydrochemistry and contaminant history of the canyon is well-documented. The PRB uses a funnel-and-gate system with a series of four reactive media cells to immobilize or destroy contaminants present in alluvial groundwater, including strontium-90, plutonium-238,239,240, americium-241, perchlorate, and nitrate. The four cells, ordered by sequence of contact with the groundwater, consist of gravel-sized scoria (for colloid removal); phosphate rock containing apatite (for metals and radionuclides); pecan shells and cotton seed admixed with gravel (bio-barrier, to deplete dissolved oxygen and destroy potential RCRA organic compounds, nitrate and perchlorate); and limestone (pH buffering and anion adsorption). Design elements of the PRB are based on laboratory-scale treatability studies and on a field investigation of hydrologic, geochemical, and geotechnical parameters. The PRB was designed with the following criteria: 1-day residence time within the biobarrier, 10-year lifetime, minimization of surface water infiltration and erosion, optimization of hydraulic capture, and minimization of excavated material requiring disposal. Each layer has been equipped with monitoring wells or ports to allow sampling of groundwater and reactive media, and monitor wells are located immediately adjacent to the up- and down-gradient perimeter of the

  5. Effect of tropical fruit juices on dentine permeability and erosive ability in removing the smear layer: An in vitro study

    Kanittha Kijsamanmith

    2016-06-01

    Conclusion: We conclude that tropical fruit juices, especially green mango and lime, increase dentine permeability and have a strong erosive ability to remove the smear layer, which causes dentine hypersensitivity.

  6. The fraction dose absorbed, in humans, and high jejunal human permeability relationship.

    Dahan, Arik; Lennernäs, Hans; Amidon, Gordon L

    2012-06-04

    The drug intestinal permeability (P(eff)) measure has been widely used as one of the main factors governing both the rate and/or extent of drug absorption (F(abs)) in humans following oral administration. In this communication we emphasize the complexity behind and the care that must be taken with this in vivo P(eff) measurement. Intestinal permeability, considering the whole of the human intestine, is more complex than generally recognized, and this can lead to misjudgment regarding F(abs) and P(eff) in various settings, e.g. drug discovery, formulation design, drug development and regulation. Setting the adequate standard for the low/high permeability class boundary, the different experimental methods for the permeability measurement, and segmental-dependent permeability throughout the human intestine due to different mechanisms are some of the main points that are discussed. Overall, the use of jejunal P(eff) as a surrogate for extent of absorption is sound and scientifically justified; a compound with high jejunal P(eff) will have high F(abs), eliminating the risk for misclassification as a BCS class I drug. Much more care should be taken, however, when jejunal P(eff) does not support a high-permeability classification; a thorough examination may reveal high-permeability after all, attributable to e.g. segmental-dependent permeability due to degree of ionization or transporter expression. In this situation, the use of multiple permeability experimental methods, including the use of metabolism, which except for luminal degradation requires absorption, is prudent and encouraged.

  7. Clinical research on high oxygen permeable contact lens used after photorefractive keratectomy surgery

    Hao-Jiang Yang

    2013-07-01

    Full Text Available AIM: To evaluate the outcome of high oxygen permeable contact lens used after photorefractive keratectomy(PRKsurgery.METHODS: Totally 95 patients(190 eyesafter PRK were included. Patients were randomly assigned to wear high oxygen permeable contact lens in one eye and normal lens in the fellow eye after surgery. The subjective symptoms and corneal epithelial status after PRK were evaluated. Uncorrected visual acuity(UCVAand haze were assessed at 6 months after PRK.RESULTS: Complaints of blurred vision, pain and photophobia were statistically more among the normal lens group than high oxygen permeable contact lens group(PPP=0.35. There was no difference in UCVA and haze 6 months after surgery(P=0.55. CONCLUSION: High oxygen permeable contact lens can significantly produce less the corneal irritated symptoms, reduce the discomfort feeling and promote healing of corneal epithelium after PRK.

  8. Determination of permeability coefficients of ophthalmic drugs through different layers of porcine, rabbit and bovine eyes

    Nagel, Stefan; Guthoff, Rudolf F.; Weitschies, Werner; Seidlitz, Anne; Kristl, Albin; Žakelj, Simon; Loch, Christian

    2015-01-01

    To treat ophthalmic diseases like glaucoma or inflammatory disorders topically applied ophthalmic formulations such as eye drops are usually used. In addition, novel ophthalmic implants releasing drug substances locally into different parts of the eye are available today. In the work presented here, the permeability coefficients of selected drugs (ciprofloxacin hydrochloride, lidocaine hydrochloride, timolol maleate) for ophthalmic tissues were determined using side-by-side diffusion chambers...

  9. Determination of permeability coefficients of ophthalmic drugs through different layers of porcine, rabbit and bovine eyes.

    Loch, Christian; Zakelj, Simon; Kristl, Albin; Nagel, Stefan; Guthoff, Rudolf; Weitschies, Werner; Seidlitz, Anne

    2012-08-30

    To treat ophthalmic diseases like glaucoma or inflammatory disorders topically applied ophthalmic formulations such as eye drops are usually used. In addition, novel ophthalmic implants releasing drug substances locally into different parts of the eye are available today. In the work presented here, the permeability coefficients of selected drugs (ciprofloxacin hydrochloride, lidocaine hydrochloride, timolol maleate) for ophthalmic tissues were determined using side-by-side diffusion chambers (so-called Ussing chambers). Sclera, conjunctiva, cornea, choroidea-retina-complex and a complex of conjunctiva-sclera-choroidea-retina were excised from fresh porcine, rabbit and bovine eyes. In the porcine eye tissues the highest P(app) values were obtained for conjunctiva with the exception of lidocaine. Therefore, it can be estimated that a certain amount of drug diffuses or is transported through conjunctiva after application. The P(app) values for sclera were also higher than those for cornea and even more, the surface area of sclera which is available for drug absorption is much larger than that of cornea when applying an implant. The obtained permeability coefficients for sclera and conjunctiva indicate that the administration of periocular implants can be an alternative to topically applied formulations. The complexes of the tissues were a significantly (p<0.01) stronger barrier to the investigated substances than the separated tissues. Distinct differences in permeability coefficients between the investigated animal tissues were observed. Overall the highest P(app) values for all mounted tissues were obtained with the rabbit, followed by porcine and bovine eyes. Because of these distinct interspecies differences one must be very careful when selecting the proper animal model for the permeability experiments. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Water-Permeable Dialysis Membranes for Multi-Layered Micro Dialysis System

    Naoya eTo

    2015-06-01

    Full Text Available This paper presents the development of water-permeable dialysis membranes that are suitable for an implantable microdialysis system that does not use dialysis fluid. We developed a microdialysis system integrating microfluidic channels and nanoporous filtering membranes made of polyethersulfone (PES, aiming at a fully implantable system that drastically improves the quality of life of patients. Simplicity of the total system is crucial for the implantable dialysis system, where the pumps and storage tanks for the dialysis fluid pose problems. Hence, we focus on hemofiltration, which does not require the dialysis fluid but water-permeable membranes. We investigated the water-permeability of the PES membrane with respect to the concentrations of the PES, the additives, and the solvents in the casting solution. Sufficiently water-permeable membranes were found through in vitro experiments using whole bovine blood. The filtrate was verified to have the concentrations of low-molecular-weight molecules, such as sodium, potassium, urea, and creatinine, while proteins, such as albumin, were successfully blocked by the membrane. We conducted in vivo experiments using rats, where the system was connected to the femoral artery and jugular vein. The filtrate was successfully collected without any leakage of blood inside the system and it did not contain albumin but low-molecular-weight molecules whose concentrations were identical to those of the blood. The rat model with renal failure showed 100% increase of creatinine in 5 h, while rats connected to the system showed only a 7.4% increase, which verified the effectiveness of the proposed microdialysis system.

  11. The low/high BCS permeability class boundary: physicochemical comparison of metoprolol and labetalol.

    Zur, Moran; Gasparini, Marisa; Wolk, Omri; Amidon, Gordon L; Dahan, Arik

    2014-05-05

    Although recognized as overly conservative, metoprolol is currently the common low/high BCS permeability class boundary reference compound, while labetalol was suggested as a potential alternative. The purpose of this study was to identify the various characteristics that the optimal marker should exhibit, and to investigate the suitability of labetalol as the permeability class reference drug. Labetalol's BCS solubility class was determined, and its physicochemical properties and intestinal permeability were thoroughly investigated, both in vitro and in vivo in rats, considering the complexity of the whole of the small intestine. Labetalol was found to be unequivocally a high-solubility compound. In the pH range throughout the small intestine (6.5-7.5), labetalol exhibited pH-dependent permeability, with higher permeability at higher pH values. While in vitro octanol-buffer partitioning (Log D) values of labetalol were significantly higher than those of metoprolol, the opposite was evident in the in vitro PAMPA permeability assay. The results of the in vivo perfusion studies in rats lay between the two contradictory in vitro studies; metoprolol was shown to have moderately higher rat intestinal permeability than labetalol. Theoretical distribution of the ionic species of the drugs was in corroboration with the experimental in vitro and the in vivo data. We propose three characteristics that the optimal permeability class reference drug should exhibit: (1) fraction dose absorbed in the range of 90%; (2) the optimal marker drug should be absorbed largely via passive transcellular permeability, with no/negligible carrier-mediated active intestinal transport (influx or efflux); and (3) the optimal marker drug should preferably be nonionizable. The data presented in this paper demonstrate that neither metoprolol nor labetalol can be regarded as optimal low/high-permeability class boundary standard. While metoprolol is too conservative due to its complete absorption

  12. Mucin dispersions as a model for the oromucosal mucus layer in in vitro and ex vivo buccal permeability studies of small molecules

    Marxen, Eva; Mosgaard, Mette Dalskov; Pedersen, Anne Marie Lynge

    2017-01-01

    The mucus layer is believed to play a part in drug permeation across the oral mucosa. Human freeze-dried saliva (HFDS) and porcine gastric mucin (PGM) was evaluated as model for mucus layer per se or in conjunction with in vitro and ex vivo buccal permeability models. Four small molecules (nicoti...

  13. Modelling water vapour permeability through atomic layer deposition coated photovoltaic barrier defects

    Elrawemi, Mohamed, E-mail: Mohamed.elrawemi@hud.ac.uk [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Blunt, Liam; Fleming, Leigh [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Bird, David, E-mail: David.Bird@uk-cpi.com [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Robbins, David [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Sweeney, Francis [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom)

    2014-11-03

    Transparent barrier films such as Al{sub 2}O{sub 3} used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance. - Highlights: • A model of water vapour permeation through barrier defects is presented. • The effect of the defects on the water vapour permeability is investigated. • Defect density correlates with water vapour permeability. • Large defects may dominate the permeation properties of the barrier film.

  14. In vitro porcine blood-brain barrier model for permeability studies: pCEL-X software pKa(FLUX) method for aqueous boundary layer correction and detailed data analysis.

    Yusof, Siti R; Avdeef, Alex; Abbott, N Joan

    2014-12-18

    In vitro blood-brain barrier (BBB) models from primary brain endothelial cells can closely resemble the in vivo BBB, offering valuable models to assay BBB functions and to screen potential central nervous system drugs. We have recently developed an in vitro BBB model using primary porcine brain endothelial cells. The model shows expression of tight junction proteins and high transendothelial electrical resistance, evidence for a restrictive paracellular pathway. Validation studies using small drug-like compounds demonstrated functional uptake and efflux transporters, showing the suitability of the model to assay drug permeability. However, one limitation of in vitro model permeability measurement is the presence of the aqueous boundary layer (ABL) resulting from inefficient stirring during the permeability assay. The ABL can be a rate-limiting step in permeation, particularly for lipophilic compounds, causing underestimation of the permeability. If the ABL effect is ignored, the permeability measured in vitro will not reflect the permeability in vivo. To address the issue, we explored the combination of in vitro permeability measurement using our porcine model with the pKa(FLUX) method in pCEL-X software to correct for the ABL effect and allow a detailed analysis of in vitro (transendothelial) permeability data, Papp. Published Papp using porcine models generated by our group and other groups are also analyzed. From the Papp, intrinsic transcellular permeability (P0) is derived by simultaneous refinement using a weighted nonlinear regression, taking into account permeability through the ABL, paracellular permeability and filter restrictions on permeation. The in vitro P0 derived for 22 compounds (35 measurements) showed good correlation with P0 derived from in situ brain perfusion data (r(2)=0.61). The analysis also gave evidence for carrier-mediated uptake of naloxone, propranolol and vinblastine. The combination of the in vitro porcine model and the software

  15. Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

    Akhtar, Faheem Hassan

    2017-09-13

    Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

  16. Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

    Akhtar, Faheem Hassan; Kumar, Mahendra; Villalobos, Luis Francisco; Shevate, Rahul; Vovusha, Hakkim; Schwingenschlö gl, Udo; Peinemann, Klaus-Viktor

    2017-01-01

    Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

  17. Numerical Simulation of Hydraulic Fracturing in Low-/High-Permeability, Quasi-Brittle and Heterogeneous Rocks

    Pakzad, R.; Wang, S. Y.; Sloan, S. W.

    2018-04-01

    In this study, an elastic-brittle-damage constitutive model was incorporated into the coupled fluid/solid analysis of ABAQUS to iteratively calculate the equilibrium effective stress of Biot's theory of consolidation. The Young's modulus, strength and permeability parameter of the material were randomly assigned to the representative volume elements of finite element models following the Weibull distribution function. The hydraulic conductivity of elements was associated with their hydrostatic effective stress and damage level. The steady-state permeability test results for sandstone specimens under different triaxial loading conditions were reproduced by employing the same set of material parameters in coupled transient flow/stress analyses of plane-strain models, thereby indicating the reliability of the numerical model. The influence of heterogeneity on the failure response and the absolute permeability was investigated, and the post-peak permeability was found to decrease with the heterogeneity level in the coupled analysis with transient flow. The proposed model was applied to the plane-strain simulation of the fluid pressurization of a cavity within a large-scale block under different conditions. Regardless of the heterogeneity level, the hydraulically driven fractures propagated perpendicular to the minimum principal far-field stress direction for high-permeability models under anisotropic far-field stress conditions. Scattered damage elements appeared in the models with higher degrees of heterogeneity. The partially saturated areas around propagating fractures were simulated by relating the saturation degree to the negative pore pressure in low-permeability blocks under high pressure. By replicating previously reported trends in the fracture initiation and breakdown pressure for different pressurization rates and hydraulic conductivities, the results showed that the proposed model for hydraulic fracture problems is reliable for a wide range of

  18. Recovery of Porosity and Permeability for High Plasticity Clays

    Krogsbøll, Anette; Foged, Niels Nielsen

    to be the case for high plasticity clays that are uncemented, and with a high content of clay minerals, especially smectite. Oedometer tests on samples from the Paleogene period show that 80% or more of the compaction will recover when unloaded, and if unloaded to a stress lower than in situ stress level...

  19. Effects of Low-Permeability Layers in the Hyporheic Zone on Oxygen Consumption Under Losing and Gaining Groundwater Flow Conditions

    Arnon, S.; Krause, S.; Gomez-Velez, J. D.; De Falco, N.

    2017-12-01

    Recent studies at the watershed scale have demonstrated the dominant role that river bedforms play in driving hyporheic exchange and constraining biogeochemical processes along river corridors. At the reach and bedform scales, modeling studies have shown that sediment heterogeneity significantly modifies hyporheic flow patterns within bedforms, resulting in spatially heterogeneous biogeochemical processes. In this work, we summarize a series of flume experiments to evaluate the effect that low-permeability layers, representative of structural heterogeneity, have on hyporheic exchange and oxygen consumption in sandy streambeds. In this case, we systematically changed the geometry of the heterogeneities, the surface channel flow driving the exchange, and groundwater fluxes (gaining/losing) modulating the exchange. The flume was packed with natural sediments, which were amended with compost to minimize carbon limitations. Structural heterogeneities were represented by continuous and discontinuous layers of clay material. Flow patterns were studied using dye imaging through the side walls. Oxygen distribution in the streambed was measured using planar optodes. The experimental observations revealed that the clay layer had a significant effect on flow patterns and oxygen distribution in the streambed under neutral and losing conditions. Under gaining conditions, the aerobic zone was limited to the upper sections of the bedform and thus was less influenced by the clay layers that were located at a depth of 1-3 cm below the water-sediment interface. We are currently analyzing the results with a numerical flow and transport model to quantify the reactions rates under the different flow conditions and spatial sediment structures. Our preliminary results enable us to show the importance of the coupling between flow conditions, local heterogeneity within the streambed and oxygen consumption along bed forms and are expected to improve our ability to model the effect of stream

  20. Water permeability, hybrid layer long-term integrity and reaction mechanism of a two-step adhesive system.

    Grégoire, Geneviève; Dabsie, Firas; Delannée, Mathieu; Akon, Bernadette; Sharrock, Patrick

    2010-07-01

    Our aim was to investigate the reaction mechanism of formation of the hybrid layer by a HEMA-containing self-etch adhesive and to study fluid filtration, contact angle and interfacial ultrastructure by SEM following a 1 year ageing period. Acidic behaviour and chemical interactions between Silorane System Adhesive and dentine were studied by potentiometric titrations, atomic absorption spectroscopy and infrared spectroscopy. The hydrophilicity of the adhesive was evaluated using the sessile drop method and dentine permeability by hydraulic conductance. The morphological study of the dentine/adhesive system interface was conducted using SEM. The Silorane System Adhesive behaved as a multi-acid with several different pK(a) values. When the adhesive was in contact with dentine, the acid was progressively consumed and calcium ions were released. The acrylate substituted phosphonate bound strongly to apatite crystals. The polyacrylic acid copolymer reacted with calcium ions and formed an interpenetrating polymer network (IPN). Water contact angle measurements showed rapid spreading on primer (angles reached 15 degrees at 30s) and larger contact angles when the Silorane bonding layer was added (from over 60 degrees to 44 degrees ). A thick, homogeneous hybrid layer was observed both initially and after 1 year of ageing, with a corresponding hydraulic conductance of -48.50% initially and -52.07% at 12 months. The Silorane System Adhesive is capable of both dissolving calcium ions and binding to apatite surfaces. The results showed the hydrophilicity of the adhesive, which formed an IPN-like hybrid layer that conserved adequate impermeability over a 1-year period. Copyright 2010 Elsevier Ltd. All rights reserved.

  1. A biomimic thermal fabric with high moisture permeability

    Fan Jie

    2013-01-01

    Full Text Available Moisture comfort is an essential factor for functional property of thermal cloth, especially for thick thermal cloth, since thick cloth may hinder effective moisture permeation, and high moisture concentration in the micro-climate between skin and fabric would cause cold feeling. Here, we report a biomimic thermal fabric with excellent warm retention and moisture management properties. In this fabric, the warp yarn system constructs many tree-shaped channel nets in the thickness direction of the fabric. Experimental result indicates that the special hierarchic configuration of warp yarns endows the biomimic thermal fabric with a better warm retention and water vapor management properties compared with the traditional fabrics.

  2. Highly durable and low permeable concrete for LLW facilities

    Yanagibashi, Kunio; Saito, Toshio; Odagawa, Masaro.

    1997-01-01

    Concrete used for LLW facilities is required to be highly durable. The authors evaluated concrete containing glycol ether derivatives and silica fume as admixtures. Compressive strength, diffusion coefficient of water, depth of accelerated carbonation, drying shrinkage, depth of chlorides penetration and resistance to freezing and thawing were investigated using concrete specimens. Compressive strength, depth of accelerated carbonation, diffusion coefficient of 137 Cs were investigated using mortar specimens before and after irradiation of gamma rays. Results showed that using glycol ether derivatives and silica fume was effective in improving the durability. (author)

  3. Effect of persistent high intraocular pressure on microstructure and hydraulic permeability of trabecular meshwork

    Mei Xi; Ren Lin; Xu Qiang; Liu Zhi-Cheng; Zheng Wei

    2015-01-01

    As the aqueous humor leaves the eye, it first passes through the trabecular meshwork (TM). Increased flow resistance in this region causes elevation of intraocular pressure (IOP), which leads to the occurrence of glaucoma. To quantitatively evaluate the effect of high IOP on the configuration and hydraulic permeability of the TM, second harmonic generation (SHG) microscopy was used to image the microstructures of the TM and adjacent tissues in control (normal) and high IOP conditions. Enucleated rabbit eyes were perfused at a pressure of 60 mmHg to achieve the high IOP. Through the anterior chamber of the eye, in situ images were obtained from different depths beneath the surface of the TM. Porosity and specific surface area of the TM in control and high IOP conditions were then calculated to estimate the effect of the high pressure on the permeability of tissue in different depths. We further photographed the histological sections of the TM and compared the in situ images. The following results were obtained in the control condition, where the region of depth was less than 55 μm with crossed branching beams and large pores in the superficial TM. The deeper meshwork is a silk-like tissue with abundant fluorescence separating the small size of pores. The total thickness of pathway tissues composed of TM and juxtacanalicular (JCT) is more than 100 μm. After putting a high pressure on the inner wall of the eye, the TM region progressively collapses and decreases to be less than 40 μm. Fibers of the TM became dense, and the porosity at 34 μm in the high IOP condition is comparable to that at 105 μm in the control condition. As a consequent result, the permeability of the superficial TM decreases rapidly from 120 μm 2 to 49.6 μm 2 and that of deeper TM decreases from 1.66 μm 2 to 0.57 μm 2 . Heterogeneity reflected by descent in permeability reduces from 12.4 μm of the control condition to 3.74 μm of the high IOP condition. The persistently high IOP makes the

  4. High Guanidinium Permeability Reveals Dehydration-Dependent Ion Selectivity in the Plasmodial Surface Anion Channel

    Abdullah A. B. Bokhari

    2014-01-01

    Full Text Available Malaria parasites grow within vertebrate erythrocytes and increase host cell permeability to access nutrients from plasma. This increase is mediated by the plasmodial surface anion channel (PSAC, an unusual ion channel linked to the conserved clag gene family. Although PSAC recognizes and transports a broad range of uncharged and charged solutes, it must efficiently exclude the small Na+ ion to maintain infected cell osmotic stability. Here, we examine possible mechanisms for this remarkable solute selectivity. We identify guanidinium as an organic cation with high permeability into human erythrocytes infected with Plasmodium falciparum, but negligible uptake by uninfected cells. Transport characteristics and pharmacology indicate that this uptake is specifically mediated by PSAC. The rank order of organic and inorganic cation permeabilities suggests cation dehydration as the rate-limiting step in transport through the channel. The high guanidinium permeability of infected cells also allows rapid and stringent synchronization of parasite cultures, as required for molecular and cellular studies of this pathogen. These studies provide important insights into how nutrients and ions are transported via PSAC, an established target for antimalarial drug development.

  5. A modified parallel artificial membrane permeability assay for evaluating the bioconcentration of highly hydrophobic chemicals in fish.

    Kwon, Jung-Hwan; Escher, Beate I

    2008-03-01

    Low cost in vitro tools are needed at the screening stage of assessment of bioaccumulation potential of new and existing chemicals because the number of chemical substances that needs to be tested highly exceeds the capacity of in vivo bioconcentration tests. Thus, the parallel artificial membrane permeability assay (PAMPA) system was modified to predict passive uptake/ elimination rate in fish. To overcome the difficulties associated with low aqueous solubility and high membrane affinity of highly hydrophobic chemicals, we measured the rate of permeation from the donor poly(dimethylsiloxane)(PDMS) disk to the acceptor PDMS disk through aqueous and PDMS membrane boundary layers and term the modified PAMPA system "PDMS-PAMPA". Twenty chemicals were selected for validation of PDMS-PAMPA. The measured permeability is proportional to the passive elimination rate constant in fish and was used to predict the "minimum" in vivo elimination rate constant. The in vivo data were very close to predicted values except for a few polar chemicals and metabolically active chemicals, such as pyrene and benzo[a]pyrene. Thus, PDMS-PAMPA can be an appropriate in vitro system for nonmetabolizable chemicals. Combination with metabolic clearance rates using a battery of metabolic degradation assays would enhance the applicability for metabolizable chemicals.

  6. Hydrogen permeability through metals

    Pisarev, A.A.; Tsvetkov, I.V.; Marenkov, E.D.; Yarko, S.S.

    2011-01-01

    The mechanisms of hydrogen permeability through one-layer and multi-layer membranes are considered. The effect of surface roughness, crystal defects, cracks and pores is described. Mathematical description of the processes is given [ru

  7. Analysis of heterogeneous characteristics in a geothermal area with low permeability and high temperature

    Alfonso Aragón-Aguilar

    2017-09-01

    Full Text Available An analytical methodology for reservoir characterization was applied in the central and southwestern zones of Los Humeros geothermal field (LHGF. This study involves analysis of temperature, pressure, enthalpy and permeability in wells and their distribution along the area. The wells located in the central western side of the geothermal field are productive, whereas those located at the central-eastern side are non-productive. Through temperature profiles, determined at steady state in the analyzed wells, it was observed that at bottom conditions (approximately 2300 m depth, temperatures vary between 280 and 360 °C. The temperatures are higher at the eastern side of central zone of LHGF. A review of transient pressure tests, laboratory measurements of core samples, and correlation of circulation losses during drilling suggest that permeability of the formation is low. The enthalpy behavior in productive wells shows a tendency of increase in the steam fraction. It was found that productivity behavior has inverse relation with permeability of rock formation. Further, it is observed that an imbalance exists between exploitation and recharge. It is concluded from the results that the wells located at central-eastern area have low permeability and high temperature, which indicates possibility of heat storage.

  8. High strain rate deformation of layered nanocomposites.

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  9. High strain rate deformation of layered nanocomposites

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  10. Direct Calculation of Permeability by High-Accurate Finite Difference and Numerical Integration Methods

    Wang, Yi

    2016-07-21

    Velocity of fluid flow in underground porous media is 6~12 orders of magnitudes lower than that in pipelines. If numerical errors are not carefully controlled in this kind of simulations, high distortion of the final results may occur [1-4]. To fit the high accuracy demands of fluid flow simulations in porous media, traditional finite difference methods and numerical integration methods are discussed and corresponding high-accurate methods are developed. When applied to the direct calculation of full-tensor permeability for underground flow, the high-accurate finite difference method is confirmed to have numerical error as low as 10-5% while the high-accurate numerical integration method has numerical error around 0%. Thus, the approach combining the high-accurate finite difference and numerical integration methods is a reliable way to efficiently determine the characteristics of general full-tensor permeability such as maximum and minimum permeability components, principal direction and anisotropic ratio. Copyright © Global-Science Press 2016.

  11. Magnetic field extraction of trap-based electron beams using a high-permeability grid

    Hurst, N. C.; Danielson, J. R.; Surko, C. M.

    2015-01-01

    A method to form high quality electrostatically guided lepton beams is explored. Test electron beams are extracted from tailored plasmas confined in a Penning-Malmberg trap. The particles are then extracted from the confining axial magnetic field by passing them through a high magnetic permeability grid with radial tines (a so-called “magnetic spider”). An Einzel lens is used to focus and analyze the beam properties. Numerical simulations are used to model non-adiabatic effects due to the spider, and the predictions are compared with the experimental results. Improvements in beam quality are discussed relative to the use of a hole in a high permeability shield (i.e., in lieu of the spider), and areas for further improvement are described

  12. An optimized microstructure to minimizing in-plane and through-plane pressure drops of fibrous materials: Counter-intuitive reduction of gas diffusion layer permeability with porosity

    Sadeghifar, Hamidreza

    2018-05-01

    The present study experimentally investigates the realistic functionality of in-plane and through-plane pressure drops of layered fibrous media with porosity, fiber diameter, fiber spacing, fiber-fiber angles and fiber-flow angles. The study also reveals that pressure drop may increase with porosity and fiber diameter under specific circumstances. This counter-intuitive point narrows down the validity range of widely-used permeability-porosity-diameter models or correlations. It is found that, for fibrous materials, the most important parameter that impacts the in-plane pressure drop is not their porosities but the number of fibers extended in the flow direction. It is also concluded that in-plane pressure drop is highly dependent upon the flow direction (fiber-flow angles), especially at lower porosities. Contrary to in-plane pressure drop, through-plane pressure drop is a weak function of fiber-fiber angles but is strongly impacted by fiber spacing, especially at lower porosities. At a given porosity, low through-plane pressure drops occur if fiber spacing does not change practically from one layer to another. Through-plane pressure drop also, insignificantly, increases with the intersecting angles between fibers. An optimized microstructure of fibrous media resulting in minimal in-plane and through-plane pressure drops is also offered for the first time in this work.

  13. Two-phase convection in Ganymede's high-pressure ice layer - Implications for its geological evolution

    Kalousová, Klára; Sotin, Christophe; Choblet, Gaël; Tobie, Gabriel; Grasset, Olivier

    2018-01-01

    Ganymede, the largest moon in the solar system, has a fully differentiated interior with a layer of high-pressure (HP) ice between its deep ocean and silicate mantle. In this paper, we study the dynamics of this layer using a numerical model of two-phase ice-water mixture in two-dimensional Cartesian geometry. While focusing on the generation of water at the silicate/HP ice interface and its upward migration towards the ocean, we investigate the effect of bottom heat flux, the layer thickness, and the HP ice viscosity and permeability. Our results suggest that melt can be generated at the silicate/HP ice interface for small layer thickness ( ≲ 200 km) and high values of heat flux ( ≳ 20 mW m-2) and viscosity ( ≳ 1015 Pa s). Once generated, the water is transported through the layer by the upwelling plumes. Depending on the vigor of convection, it stays liquid or it may freeze before melting again as the plume reaches the temperate (partially molten) layer at the boundary with the ocean. The thickness of this layer as well as the amount of melt that is extracted from it is controlled by the permeability of the HP ice. This process constitutes a means of transporting volatiles and salts that might have dissolved into the melt present at the silicate/HP ice interface. As the moon cools down, the HP ice layer becomes less permeable because the heat flux from the silicates decreases and the HP ice layer thickens.

  14. Vanadium alloy membranes for high hydrogen permeability and suppressed hydrogen embrittlement

    Kim, Kwang Hee; Park, Hyeon Cheol; Lee, Jaeho; Cho, Eunseog; Lee, Sang Mock

    2013-01-01

    The structural properties and hydrogen permeation characteristics of ternary vanadium–iron–aluminum (V–Fe–Al) alloy were investigated. To achieve not only high hydrogen permeability but also strong resistance to hydrogen embrittlement, the alloy composition was modulated to show high hydrogen diffusivity but reduced hydrogen solubility. We demonstrated that matching the lattice constant to the value of pure V by co-alloying lattice-contracting and lattice-expanding elements was quite effective in maintaining high hydrogen diffusivity of pure V

  15. Highly permeable polymeric membranes based on the incorporation of the functional water channel protein Aquaporin Z

    Kumar, Manish; Grzelakowski, Mariusz; Zilles, Julie; Clark, Mark; Meier, Wolfgang

    2007-01-01

    The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA15-PDMS110-PMOXA15) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to ≈800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (Ea) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications. PMID:18077364

  16. Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs.

    Parker, J C; Ivey, C L; Tucker, J A

    1998-04-01

    To determine the initial signaling event in the vascular permeability increase after high airway pressure injury, we compared groups of lungs ventilated at different peak inflation pressures (PIPs) with (gadolinium group) and without (control group) infusion of 20 microM gadolinium chloride, an inhibitor of endothelial stretch-activated cation channels. Microvascular permeability was assessed by using the capillary filtration coefficient (Kfc), a measure of capillary hydraulic conductivity. Kfc was measured after ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratory pressure and with 35 cmH2O PIP with 8 cmH2O positive end-expiratory pressure. In control lungs, Kfc increased significantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In the gadolinium group, Kfc was unchanged from baseline (0.060 +/- 0.010 ml . min-1 . cmH2O-1 . 100 g-1) after any PIP ventilation period. Pulmonary vascular resistance increased significantly from baseline in both groups before the last Kfc measurement but was not different between groups. These results suggest that microvascular permeability is actively modulated by a cellular response to mechanical injury and that stretch-activated cation channels may initiate this response through increases in intracellular calcium concentration.

  17. Tacrolimus is a class II low-solubility high-permeability drug: the effect of P-glycoprotein efflux on regional permeability of tacrolimus in rats.

    Tamura, Shigeki; Ohike, Atsuo; Ibuki, Rinta; Amidon, Gordon L; Yamashita, Shinji

    2002-03-01

    The objective of this study is to investigate the role of P-glycoprotein (P-gp), a membrane efflux pump associated with multidrug resistance (MDR) and a known substrate for tacrolimus, in determining the regional intestinal permeability of tacrolimus in rats. Thus, isolated segments of rat jejunum, ileum, or colon were perfused with tacrolimus solutions containing polyethoxylated hydrogenated castor oil 60 surfactant, and with or without verapamil, a P-gp substrate used to reverse the MDR phenotype. The results indicated that the intrinsic permeability of tacrolimus in the jejunum, calculated on the basis of the concentration of non-micellized free tacrolimus, was quite high ( approximately 1.4 x 10(-4) cm/s). The apparent permeability (P(app)) in the jejunum was unaffected by the presence of verapamil; however, the P(app) in the ileum and the colon increased significantly in the presence of verapamil and were similar to the values observed in the jejunum. The results suggest that systemic absorption of tacrolimus from the gastrointestinal tract could be significantly affected by P-gp efflux mechanisms. It is also possible that differences in P-gp function at various intestinal sites in a subject or at a given intestinal site in various subjects could lead to large intra- and interindividual variability in bioavailability of tacrolimus following oral administration. Copyright 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association .

  18. Error Analysis of High Frequency Core Loss Measurement for Low-Permeability Low-Loss Magnetic Cores

    Niroumand, Farideh Javidi; Nymand, Morten

    2016-01-01

    in magnetic cores is B-H loop measurement where two windings are placed on the core under test. However, this method is highly vulnerable to phase shift error, especially for low-permeability, low-loss cores. Due to soft saturation and very low core loss, low-permeability low-loss magnetic cores are favorable...... in many of the high-efficiency high power-density power converters. Magnetic powder cores, among the low-permeability low-loss cores, are very attractive since they possess lower magnetic losses in compared to gapped ferrites. This paper presents an analytical study of the phase shift error in the core...... loss measuring of low-permeability, low-loss magnetic cores. Furthermore, the susceptibility of this measurement approach has been analytically investigated under different excitations. It has been shown that this method, under square-wave excitation, is more accurate compared to sinusoidal excitation...

  19. Permeability and 3-D melt geometry in shear-induced high melt fraction conduits

    Zhu, W.; Cordonnier, B.; Qi, C.; Kohlstedt, D. L.

    2017-12-01

    Observations of dunite channels in ophiolites and uranium-series disequilibria in mid-ocean ridge basalt suggest that melt transport in the upper mantle beneath mid-ocean ridges is strongly channelized. Formation of high melt fraction conduits could result from mechanical shear, pyroxene dissolution, and lithological partitioning. Deformation experiments (e.g. Holtzman et al., 2003) demonstrate that shear stress causes initially homogeneously distributed melt to segregate into an array of melt-rich bands, flanked by melt-depleted regions. At the same average melt fraction, the permeability of high melt fraction conduits could be orders of magnitude higher than that of their homogenous counterparts. However, it is difficult to determine the permeability of melt-rich bands. Using X-ray synchrotron microtomography, we obtained high-resolution images of 3-dimensional (3-D) melt distribution in a partially molten rock containing shear-induced high melt fraction conduits. Sample CQ0705, an olivine-alkali basalt aggregate with a nominal melt fraction of 4%, was deformed in torsion at a temperature of 1473 K and a confining pressure of 300 MPa to a shear strain of 13.3. A sub-volume of CQ0705 encompassing 3-4 melt-rich bands was imaged. Microtomography data were reduced to binary form so that solid olivine is distinguishable from basalt glass. At a spatial resolution of 160 nm, the 3-D images reveal the shape and connectedness of melt pockets in the melt-rich bands. Thin melt channels formed at grain edges are connected at large melt nodes at grain corners. Initial data analysis shows a clear preferred orientation of melt pockets alignment subparallel to the melt-rich band. We use the experimentally determined geometrical parameters of melt topology to create a digital rock with identical 3-D microstructures. Stokes flow simulations are conducted on the digital rock to obtain the permeability tensor. Using this digital rock physics approach, we determine how deformation

  20. Microbial communities in low permeability, high pH uranium mine tailings: characterization and potential effects.

    Bondici, V F; Lawrence, J R; Khan, N H; Hill, J E; Yergeau, E; Wolfaardt, G M; Warner, J; Korber, D R

    2013-06-01

    To describe the diversity and metabolic potential of microbial communities in uranium mine tailings characterized by high pH, high metal concentration and low permeability. To assess microbial diversity and their potential to influence the geochemistry of uranium mine tailings using aerobic and anaerobic culture-based methods, in conjunction with next generation sequencing and clone library sequencing targeting two universal bacterial markers (the 16S rRNA and cpn60 genes). Growth assays revealed that 69% of the 59 distinct culturable isolates evaluated were multiple-metal resistant, with 15% exhibiting dual-metal hypertolerance. There was a moderately positive correlation coefficient (R = 0·43, P tailings depth was shown to influence bacterial community composition, with the difference in the microbial diversity of the upper (0-20 m) and middle (20-40 m) tailings zones being highly significant (P tailings zone being significant (P tailings environment, along with their demonstrated capacity for transforming metal elements, suggests that these organisms have the potential to influence the long-term geochemistry of the tailings. This study is the first investigation of the diversity and functional potential of micro-organisms present in low permeability, high pH uranium mine tailings. © 2013 The Society for Applied Microbiology.

  1. High-permeability region size on perfusion CT predicts hemorrhagic transformation after intravenous thrombolysis in stroke.

    Josep Puig

    Full Text Available Blood-brain barrier (BBB permeability has been proposed as a predictor of hemorrhagic transformation (HT after tissue plasminogen activator (tPA administration; however, the reliability of perfusion computed tomography (PCT permeability imaging for predicting HT is uncertain. We aimed to determine the performance of high-permeability region size on PCT (HPrs-PCT in predicting HT after intravenous tPA administration in patients with acute stroke.We performed a multimodal CT protocol (non-contrast CT, PCT, CT angiography to prospectively study patients with middle cerebral artery occlusion treated with tPA within 4.5 hours of symptom onset. HT was graded at 24 hours using the European-Australasian Acute Stroke Study II criteria. ROC curves selected optimal volume threshold, and multivariate logistic regression analysis identified predictors of HT.The study included 156 patients (50% male, median age 75.5 years. Thirty-seven (23,7% developed HT [12 (7,7%, parenchymal hematoma type 2 (PH-2]. At admission, patients with HT had lower platelet values, higher NIHSS scores, increased ischemic lesion volumes, larger HPrs-PCT, and poorer collateral status. The negative predictive value of HPrs-PCT at a threshold of 7mL/100g/min was 0.84 for HT and 0.93 for PH-2. The multiple regression analysis selected HPrs-PCT at 7mL/100g/min combined with platelets and baseline NIHSS score as the best model for predicting HT (AUC 0.77. HPrs-PCT at 7mL/100g/min was the only independent predictor of PH-2 (OR 1, AUC 0.68, p = 0.045.HPrs-PCT can help predict HT after tPA, and is particularly useful in identifying patients at low risk of developing HT.

  2. High-permeability region size on perfusion CT predicts hemorrhagic transformation after intravenous thrombolysis in stroke

    Puig, Josep; Blasco, Gerard; Daunis-i-Estadella, Pepus; van Eendendburg, Cecile; Carrillo-García, María; Aboud, Carlos; Hernández-Pérez, María; Serena, Joaquín; Biarnés, Carles; Nael, Kambiz; Liebeskind, David S.; Thomalla, Götz; Menon, Bijoy K.; Demchuk, Andrew; Wintermark, Max; Pedraza, Salvador

    2017-01-01

    Objective Blood-brain barrier (BBB) permeability has been proposed as a predictor of hemorrhagic transformation (HT) after tissue plasminogen activator (tPA) administration; however, the reliability of perfusion computed tomography (PCT) permeability imaging for predicting HT is uncertain. We aimed to determine the performance of high-permeability region size on PCT (HPrs-PCT) in predicting HT after intravenous tPA administration in patients with acute stroke. Methods We performed a multimodal CT protocol (non-contrast CT, PCT, CT angiography) to prospectively study patients with middle cerebral artery occlusion treated with tPA within 4.5 hours of symptom onset. HT was graded at 24 hours using the European-Australasian Acute Stroke Study II criteria. ROC curves selected optimal volume threshold, and multivariate logistic regression analysis identified predictors of HT. Results The study included 156 patients (50% male, median age 75.5 years). Thirty-seven (23,7%) developed HT [12 (7,7%), parenchymal hematoma type 2 (PH-2)]. At admission, patients with HT had lower platelet values, higher NIHSS scores, increased ischemic lesion volumes, larger HPrs-PCT, and poorer collateral status. The negative predictive value of HPrs-PCT at a threshold of 7mL/100g/min was 0.84 for HT and 0.93 for PH-2. The multiple regression analysis selected HPrs-PCT at 7mL/100g/min combined with platelets and baseline NIHSS score as the best model for predicting HT (AUC 0.77). HPrs-PCT at 7mL/100g/min was the only independent predictor of PH-2 (OR 1, AUC 0.68, p = 0.045). Conclusions HPrs-PCT can help predict HT after tPA, and is particularly useful in identifying patients at low risk of developing HT. PMID:29182658

  3. Modelling of hydrogen permeability of membranes for high-purity hydrogen production

    Zaika, Yury V.; Rodchenkova, Natalia I.

    2017-11-01

    High-purity hydrogen is required for clean energy and a variety of chemical technology processes. Different alloys, which may be well-suited for use in gas-separation plants, were investigated by measuring specific hydrogen permeability. One had to estimate the parameters of diffusion and sorption to numerically model the different scenarios and experimental conditions of the material usage (including extreme ones), and identify the limiting factors. This paper presents a nonlinear mathematical model taking into account the dynamics of sorption-desorption processes and reversible capture of diffusing hydrogen by inhomogeneity of the material’s structure, and also modification of the model when the transport rate is high. The results of numerical modelling allow to obtain information about output data sensitivity with respect to variations of the material’s hydrogen permeability parameters. Furthermore, it is possible to analyze the dynamics of concentrations and fluxes that cannot be measured directly. Experimental data for Ta77Nb23 and V85Ni15 alloys were used to test the model. This work is supported by the Russian Foundation for Basic Research (Project No. 15-01-00744).

  4. Phase behaviour of disordered proteins underlying low density and high permeability of liquid organelles

    Wei, Ming-Tzo; Elbaum-Garfinkle, Shana; Holehouse, Alex S.; Chen, Carlos Chih-Hsiung; Feric, Marina; Arnold, Craig B.; Priestley, Rodney D.; Pappu, Rohit V.; Brangwynne, Clifford P.

    2017-11-01

    Many intracellular membraneless organelles form via phase separation of intrinsically disordered proteins (IDPs) or regions (IDRs). These include the Caenorhabditis elegans protein LAF-1, which forms P granule-like droplets in vitro. However, the role of protein disorder in phase separation and the macromolecular organization within droplets remain elusive. Here, we utilize a novel technique, ultrafast-scanning fluorescence correlation spectroscopy, to measure the molecular interactions and full coexistence curves (binodals), which quantify the protein concentration within LAF-1 droplets. The binodals of LAF-1 and its IDR display a number of unusual features, including 'high concentration' binodal arms that correspond to remarkably dilute droplets. We find that LAF-1 and other in vitro and intracellular droplets are characterized by an effective mesh size of ∼3-8 nm, which determines the size scale at which droplet properties impact molecular diffusion and permeability. These findings reveal how specific IDPs can phase separate to form permeable, low-density (semi-dilute) liquids, whose structural features are likely to strongly impact biological function.

  5. Effect of permeable flow on cyclic layering in solidifying magma bodies: Insights from an analog experiment of diffusion-precipitation systems

    Toramaru, A.; Yamauchi, S.

    2012-04-01

    Characteristic structures such as rhythmic layering, cress cumulate, cross bedding, perpendicular feldspar rock etc, are commonly observed in layered intrusion or shallow magmatic intrusions. These structures result from complex processes including thermal and compositional diffusions, crystallization, crystal settling, convection and interaction among three phases (crystals, bubble, melt). In order to understand how the differentiation proceeds in solidifying magma bodies from each characteristic structure together with chemical signatures, it is necessary to evaluate the relative importance among these elemental processes on structures. As an attempt to evaluate the effect of advection on a diffusion-related structure, we carried out an analog experiment of Liesegang system using lead-iodide (PbI2) crystallization in agar media which have been normally used to prohibit convection. In the ordinary Liesegang band formation experiments including only diffusion and crystallization kinetics without any advection and convection, the precipitation bands develop with regular spacing following a geometric progression due to two-component diffusion and reaction with supersaturation. This type of banding structure has been advocated as the same type of cyclic layering or vesicle layering (a sort of rhythmic layering) in dykes or sills. In order to see the effect of one-directional advection on Liesegang band, we apply the electric field (5 V to 25 V for a distance 15 cm) along the concentration gradient in agar media, thereby counteracting flows of lead anion Pb2+ and iodide ion I- are driven at constant velocities. The flows of anions and ions are equivalent to the permeable flows in porous media of crystal mush. The resultant precipitation structures exhibit very curious banding structure in which band spacings do not change with distance, are nearly constant and quite narrow, depending on the voltage, unlike those in ordinary Liesegang bands in which band spacings

  6. Investigation of the Effect of Recycled Asphalt Pavement Material on Permeability and Bearing Capacity in the Base Layer

    Ayşegül Güneş Seferoğlu

    2018-01-01

    Full Text Available The purpose of this research was to investigate the effects of recycled asphalt pavement (RAP and cement content on the permeability and bearing capacity characteristics of aggregate base courses. Mixtures containing untreated RAP ranging between 0 and 100 percent and 1, 2, and 3% cement-treated RAP were subjected to laboratory tests (bitumen content, sieve analysis, modified proctor, soaked California bearing ratio (CBR, and constant-level permeability tests. The results showed that, as the RAP percentage in the mixture increased, CBR values decreased considerably. Moreover, there is a linear increase in the CBR values with cement treatment. Optimum moisture contents (OMC and maximum dry densities (MDD showed a decreasing trend. Increasing the cement percentages in 100% RAP blend increases the OMC and MDD values. The permeability of RAP showed a decrease as the percentage of RAP and cement increased in blends. The study showed that the CBR value of the 20% RAP blend is also obtained in the 100% RAP/3% cement-treated blend. Thus, it has been understood that cement is a suitable material in order to increase the use of RAP. In addition, the increase in the percentage of RAP and cement made the base course more impermeable.

  7. The influence of slip velocity and temperature on permeability during and after high-velocity fault slip

    Tanikawa, W.; Mukoyoshi, H.; Tadai, O.; Hirose, T.; Lin, W.

    2011-12-01

    Fluid transport properties in fault zones play an important role in dynamic processes during large earthquakes. If the permeability in a fault zone is low, high pore-fluid pressures caused by thermal pressurization (Sibson, 1973) or shear-induced compaction (Blanpied et al., 1992) can lead to an apparent reduction of fault strength. Changes in porosity and permeability of fault rocks within a fault zone during earthquakes and the subsequent progressive recovery of these properties may have a large influence on earthquake recurrence (Sleep and Blanpied, 1992). A rotary shear apparatus was used to investigate changes of fluid transport properties in a fault zone by real-time measurement of gas flow rates during and after shearing of hollow sandstone and granite cylinders at various slip rates. Our apparatus measures permeability parallel to the slip plane in both the slip zone and wall rocks. In all cases, permeability decreased rapidly with an increase of friction, but recovered soon after slip, reaching a steady state within several tens of minutes. The rate of reduction of permeability increased with increasing slip velocity. Permeability did not recover to pre-slip levels after low-velocity tests but recovered to exceed them after high-velocity tests. Frictional heating of gases at the slip surface increased gas viscosity, which increased gas flow rate to produce an apparent permeability increase. The irreversible permeability changes of the low-velocity tests were caused by gouge formation due to wearing and smoothing of the slip surface. The increase of permeability after high-velocity tests was caused by mesoscale fracturing in response to rapid temperature rise. Changes of pore fluid viscosity contributed more to changes of flow rate than did permeability changes caused by shear deformation, although test results from different rocks and pore fluids might be different. References Blanpied, M.L., Lockner, D.A., Byerlee, J.D., 1992. An earthquake mechanism

  8. High thermal conductivity lossy dielectric using a multi layer configuration

    Tiegs, Terry N.; Kiggans, Jr., James O.

    2003-01-01

    Systems and methods are described for loss dielectrics. A loss dielectric includes at least one high dielectric loss layer and at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. A method of manufacturing a loss dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. The systems and methods provide advantages because the loss dielectrics are less costly and more environmentally friendly than the available alternatives.

  9. Dual Solutions in a Boundary Layer Flow of a Power Law Fluid over a Moving Permeable Flat Plate with Thermal Radiation, Viscous Dissipation and Heat Generation/Absorption

    Aftab Ahmed

    2018-01-01

    Full Text Available The aim of the present study is to investigate the combined effects of the thermal radiation, viscous dissipation, suction/injection and internal heat generation/absorption on the boundary layer flow of a non-Newtonian power law fluid over a semi infinite permeable flat plate moving in parallel or reversely to a free stream. The resulting system of partial differential equations (PDEs is first transformed into a system of coupled nonlinear ordinary differential equations (ODEs which are then solved numerically by using the shooting technique. It is found that the dual solutions exist when the flat plate and the free stream move in the opposite directions. Dimensionless boundary layer velocity and temperature distributions are plotted and discussed for various values of the emerging physical parameters. Finally, the tables of the relevant boundary derivatives are presented for some values of the governing physical parameters.

  10. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  11. Acute high-intensity interval running increases markers of gastrointestinal damage and permeability but not gastrointestinal symptoms.

    Pugh, Jamie N; Impey, Samuel G; Doran, Dominic A; Fleming, Simon C; Morton, James P; Close, Graeme L

    2017-09-01

    The purpose of this study was to investigate the effects of high-intensity interval running on markers of gastrointestinal (GI) damage and permeability alongside subjective symptoms of GI discomfort. Eleven male runners completed an acute bout of high-intensity interval training (HIIT) (eighteen 400-m runs at 120% maximal oxygen uptake) where markers of GI permeability, intestinal damage, and GI discomfort symptoms were assessed and compared with resting conditions. Compared with rest, HIIT significantly increased serum lactulose/rhamnose ratio (0.051 ± 0.016 vs. 0.031 ± 0.021, p = 0.0047; 95% confidence interval (CI) = 0.006 to 0.036) and sucrose concentrations (0.388 ± 0.217 vs. 0.137 ± 0.148 mg·L -1 ; p HIIT and resting conditions. Plasma intestinal-fatty acid binding protein (I-FABP) was significantly increased (p HIIT whereas no changes were observed during rest. Mild symptoms of GI discomfort were reported immediately and at 24 h post-HIIT, although these symptoms did not correlate to GI permeability or I-FABP. In conclusion, acute HIIT increased GI permeability and intestinal I-FABP release, although these do not correlate with symptoms of GI discomfort. Furthermore, by using serum sampling, we provide data showing that it is possible to detect changes in intestinal permeability that is not observed using urinary sampling over a shorter time-period.

  12. Highly doped layer for tunnel junctions in solar cells

    Fetzer, Christopher M.

    2017-08-01

    A highly doped layer for interconnecting tunnel junctions in multijunction solar cells is presented. The highly doped layer is a delta doped layer in one or both layers of a tunnel diode junction used to connect two or more p-on-n or n-on-p solar cells in a multijunction solar cell. A delta doped layer is made by interrupting the epitaxial growth of one of the layers of the tunnel diode, depositing a delta dopant at a concentration substantially greater than the concentration used in growing the layer of the tunnel diode, and then continuing to epitaxially grow the remaining tunnel diode.

  13. Experimental study of very low permeability rocks using a high accuracy permeameter

    Larive, Elodie

    2002-01-01

    The measurement of fluid flow through 'tight' rocks is important to provide a better understanding of physical processes involved in several industrial and natural problems. These include deep nuclear waste repositories, management of aquifers, gas, petroleum or geothermal reservoirs, or earthquakes prevention. The major part of this work consisted of the design, construction and use of an elaborate experimental apparatus allowing laboratory permeability measurements (fluid flow) of very low permeability rocks, on samples at a centimetric scale, to constrain their hydraulic behaviour at realistic in-situ conditions. The accuracy permeameter allows the use of several measurement methods, the steady-state flow method, the transient pulse method, and the sinusoidal pore pressure oscillation method. Measurements were made with the pore pressure oscillation method, using different waveform periods, at several pore and confining pressure conditions, on different materials. The permeability of one natural standard, Westerly granite, and an artificial one, a micro-porous cement, were measured, and results obtained agreed with previous measurements made on these materials showing the reliability of the permeameter. A study of a Yorkshire sandstone shows a relationship between rock microstructure, permeability anisotropy and thermal cracking. Microstructure, porosity and permeability concepts, and laboratory permeability measurements specifications are presented, the permeameter is described, and then permeability results obtained on the investigated materials are reported [fr

  14. Effects of eddy current and dispersion of magnetic anisotropy on the high-frequency permeability of Fe-based nanocomposites

    Han, M., E-mail: mangui@gmail.com [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Rozanov, K.N.; Zezyulina, P.A. [Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, Moscow (Russian Federation); Wu, Yan-Hui [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China)

    2015-06-01

    Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe{sub 3}(Si) with D0{sub 3} superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9.

  15. Effects of eddy current and dispersion of magnetic anisotropy on the high-frequency permeability of Fe-based nanocomposites

    Han, M.; Rozanov, K.N.; Zezyulina, P.A.; Wu, Yan-Hui

    2015-01-01

    Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe 3 (Si) with D0 3 superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9

  16. Pore pressure propagation in a permeable thin-layer coal seam based on a dual porosity model: A case of risk prediction of water inrush in coalmines

    Zhu, B.; Gao, F.; Yang, J. W.; Zhou, G. Q.

    2016-08-01

    Thin-layer coal seams, a type of filling coal rock body, are considered aquifer systems made up of dual porosity medium with immediate floor. A numerical simulation for the pore pressure propagation along a thin-layer coal seam was carried out for the case of the Zhaogezhuang coalmine in China. By valuing the permeability (Kf ) of the thin-layer coal seam, pore pressure variation with time was simulated and compared to the analytical solutions of a dual porosity model (DPM). The main conclusions were drawn as follow: (1) Seepage in the thin-layer coal seam was predominant in the whole process, and the distance of seepage was lengthened and the pore pressure decreased with increased Kf , (2) A series of simulated hydraulic graphs demonstrated that the pore pressure characteristics of peak-occurring and time-lag effects agreed with the analytical solutions of DPM; (3) By adjusting the parameters of DPM, two results of analytical solutions and numerical solutions fit well, particularly in the thin-layer coal seam, (4) The power law relationship between the peak-values and lag time of pore pressure were derived statistically under consideration of the Kf parameter in the range of 10-8 to 10-10 m2/pa-s orders, and it was reasonable that the Kf of the thin-layer coal seam was in the range of 10-8 m2/pa-s orders. The results were significantly helpful in decision-making for mining water prevention and prediction in practice.

  17. Ultra high pressure liquid chromatography. Column permeability and changes of the eluent properties.

    Gritti, Fabrice; Guiochon, Georges

    2008-04-11

    The behavior of four similar liquid chromatography columns (2.1mm i.d. x 30, 50, 100, and 150 mm, all packed with fine particles, average d(p) approximately 1.7 microm, of bridged ethylsiloxane/silica hybrid-C(18), named BEH-C(18)) was studied in wide ranges of temperature and pressure. The pressure and the temperature dependencies of the viscosity and the density of the eluent (pure acetonitrile) along the columns were also derived, using the column permeabilities and applying the Kozeny-Carman and the heat balance equations. The heat lost through the external surface area of the chromatographic column was directly derived from the wall temperature of the stainless steel tube measured with a precision of +/-0.2 degrees C in still air and +/-0.1 degrees C in the oven compartment. The variations of the density and viscosity of pure acetonitrile as a function of the temperature and pressure was derived from empirical correlations based on precise experimental data acquired between 298 and 373 K and at pressures up to 1.5 kbar. The measurements were made with the Acquity UPLC chromatograph that can deliver a maximum flow rate of 2 mL/min and apply a maximum column inlet pressure of 1038 bar. The average Kozeny-Carman permeability constant of the columns was 144+/-3.5%. The temperature hence the viscosity and the density profiles of the eluent along the column deviate significantly from linear behavior under high-pressure gradients. For a 1000 bar pressure drop, we measured DeltaT=25-30 K, (Deltaeta/eta) approximately 100%, and (Deltarho/rho) approximately 10%. These results show that the radial temperature profiles are never fully developed within 1% for any of the columns, even under still-air conditions. This represents a practical advantage regarding the apparent column efficiency at high flow rates, since the impact of the differential analyte velocity between the column center and the column wall is not maximum. The interpretation of the peak profiles recorded in

  18. Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

    Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

    2015-01-01

    The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85 wt % ethanol aqueous solution at 45 °C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Isoproterenol attenuates high vascular pressure-induced permeability increases in isolated rat lungs.

    Parker, J C; Ivey, C L

    1997-12-01

    To separate the contributions of cellular and basement membrane components of the alveolar capillary barrier to the increased microvascular permeability induced by high pulmonary venous pressures (Ppv), we subjected isolated rat lungs to increases in Ppv, which increased capillary filtration coefficient (Kfc) without significant hemorrhage (31 cmH2O) and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 microM) was infused in one group (Iso) to identify a reversible cellular component of injury, and residual blood volumes were measured to assess extravasation of red blood cells through ruptured basement membranes. In untreated lungs (High Ppv group), Kfc increased 6.2 +/- 1.3 and 38.3 +/- 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2% (P Kfc increases at moderate Ppv, possibly because of an endothelial effect, but it did not affect red cell extravasation at higher vascular pressures.

  20. Permeability prediction in chalks

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

    2011-01-01

    The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability p...... significantly using the effective specific surface as the fluid-flow concept. The FZI unit is appropriate for highly permeable sedimentary rocks such as sandstones and limestones that have small surface areas....

  1. High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

    Salvador, R; Miranda, P C; Roth, Y; Zangen, A

    2009-01-01

    Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/√2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

  2. High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

    Salvador, R.; Miranda, P. C.; Roth, Y.; Zangen, A.

    2009-05-01

    Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/\\sqrt 2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

  3. High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

    Salvador, R; Miranda, P C [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon (Portugal); Roth, Y [Advanced Technology Center, Sheba Medical Center, Tel-Hashomer (Israel); Zangen, A [Neurobiology Department, Weizmann Institute of Science, Rehovot 76100 (Israel)], E-mail: rnsalvador@fc.ul.pt

    2009-05-21

    Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/{radical}2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

  4. Multi-layered breathing architectural envelope

    Lund Larsen, Andreas; Foged, Isak Worre; Jensen, Rasmus Lund

    2014-01-01

    A multi layered breathing envelope is developed as a method of natural ventilation. The two main layers consist of mineral wool and air permeable concrete. The mineral wool works as a dynamic insulation and the permeable concrete as a heat recovery system with a high thermal mass for heat storage...

  5. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  6. Charge modification of the endothelial surface layer modulates the permeability barrier of isolated rat mesenteric small arteries

    van Haaren, Paul M. A.; VanBavel, Ed; Vink, Hans; Spaan, Jos A. E.

    2005-01-01

    We hypothesized that modulation of the effective charge density of the endothelial surface layer ( ESL) results in altered arterial barrier properties to transport of anionic solutes. Rat mesenteric small arteries ( diameter similar to 190 mu m) were isolated, cannulated, perfused, and superfused

  7. Magnetic tweezers with high permeability electromagnets for fast actuation of magnetic beads

    Chen, La; Offenhäusser, Andreas; Krause, Hans-Joachim [Institute of Bioelectronics (ICS-8/PGI-8), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)

    2015-04-15

    As a powerful and versatile scientific instrument, magnetic tweezers have been widely used in biophysical research areas, such as mechanical cell properties and single molecule manipulation. If one wants to steer bead position, the nonlinearity of magnetic properties and the strong position dependence of the magnetic field in most magnetic tweezers lead to quite a challenge in their control. In this article, we report multi-pole electromagnetic tweezers with high permeability cores yielding high force output, good maneuverability, and flexible design. For modeling, we adopted a piece-wise linear dependence of magnetization on field to characterize the magnetic beads. We implemented a bi-linear interpolation of magnetic field in the work space, based on a lookup table obtained from finite element simulation. The electronics and software were custom-made to achieve high performance. In addition, the effects of dimension and defect on structure of magnetic tips also were inspected. In a workspace with size of 0.1 × 0.1 mm{sup 2}, a force of up to 400 pN can be applied on a 2.8 μm superparamagnetic bead in any direction within the plane. Because the magnetic particle is always pulled towards a tip, the pulling forces from the pole tips have to be well balanced in order to achieve control of the particle’s position. Active video tracking based feedback control is implemented, which is able to work at a speed of up to 1 kHz, yielding good maneuverability of the magnetic beads.

  8. Reducing Water Vapor Permeability of Poly(lactic acid Film and Bottle through Layer-by-Layer Deposition of Green-Processed Cellulose Nanocrystals and Chitosan

    Katalin Halász

    2015-01-01

    Full Text Available Layer-by-layer electrostatic self-assembly technique was applied to improve the barrier properties of poly(lactic acid (PLA films and bottles. The LbL process was carried out by the alternate adsorption of chitosan (CH (polycation and cellulose nanocrystals (CNC produced via ultrasonic treatment. Four bilayers (on each side of chitosan and cellulose nanocrystals caused 29 and 26% improvement in barrier properties in case of films and bottles, respectively. According to the results the LbL process with CH and CNC offered a transparent “green” barrier coating on PLA substrates.

  9. Crustal permeability

    Gleeson, Tom; Ingebritsen, Steven E.

    2016-01-01

    Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures.  The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration.  Although there are thousands of research papers on crustal permeability, this is the first book-length treatment.  This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. 

  10. Making synthetic mudstone: Parametric resedimentation studies at high effective stress to determine controls on breakthrough pressure and permeability

    Guiltinan, E. J.; Cardenas, M. B.; Cockrell, L.; Espinoza, N.

    2017-12-01

    The geologic sequestration of CO2 is widely considered a potential solution for decreasing anthropogenic atmospheric CO2 emissions. As CO2 rises buoyantly within a reservoir it pools beneath a caprock and a pressure is exerted upon the pores of the caprock proportionally to the height of the pool. The breakthrough pressure is the point at which CO2 begins to flow freely across the caprock. Understanding the mineralogical and grain size controls on breakthrough pressure is important for screening the security of CO2 sequestration sites. However, breakthrough pressure and permeability measurements on caprocks are difficult to conduct in a systematic manner given the variability in and heterogeneity of naturally occurring mudstones and shales causing significant noise and scatter in the literature. Recent work has even revealed the ability for CO2 to pass through thin shale beds at relatively low pressures. To broaden the understanding of shale breakthrough and permeability, we developed an approach that allows for the creation of resedimented mudstones at high effective stresses. Resedimented samples also include calcium carbonate cement. Using this technique, we explore the controls on entry pressure, breakthrough pressure, and permeability of synthetic mudstones. Understanding the effect of mineralogy and grain size on the permeability and breakthrough pressure of mudstones at reservoir stresses will help in the selection and uncertainty quantification of secure CO2 storage sites.

  11. Composite layers in the high speed steels

    Koson, A.; Rutkowska, A.; Dabrowski, M.

    2002-01-01

    The production process and different properties of TiN, (TiA)(N and TiN + (TiAl)N coatings are described in this work. The coatings were obtained on fast-cutting steel 6-5-2(SW7M) after a typical heat treatment and gas nitriding. The following features were examined: thickness and hardness of produced layers as well as wearing quality (using T-0.5 tester). Composite layer of (TiAl)N has achieved the highest wearing quality in the range of wearing parameters applied. (author)

  12. Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

    Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

    2013-12-01

    Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

  13. A Micro grid design for a kind of household energy efficiency management system based on high permeability

    Li, Siwei; Li, Jun; Liu, Zhuochu; Wang, Min; Yue, Liang

    2017-05-01

    After the access of household distributed photovoltaic, conditions of high permeability generally occur, which cut off the connection between distributed power supply and major network rapidly and use energy storage device to realize electrical energy storage. The above operations cannot be adequate for the power grid health after distributed power supply access any more from the perspective of economy and rationality. This paper uses the integration between device and device, integration between device and system and integration between system and system of household microgrid and household energy efficiency management, to design household microgrid building program and operation strategy containing household energy efficiency management, to achieve efficient integration of household energy efficiency management and household microgrid, to effectively solve problems of high permeability of household distributed power supply and so on.

  14. Mapping the layer count of few-layer hexagonal boron nitride at high lateral spatial resolutions

    Mohsin, Ali; Cross, Nicholas G.; Liu, Lei; Watanabe, Kenji; Taniguchi, Takashi; Duscher, Gerd; Gu, Gong

    2018-01-01

    Layer count control and uniformity of two dimensional (2D) layered materials are critical to the investigation of their properties and to their electronic device applications, but methods to map 2D material layer count at nanometer-level lateral spatial resolutions have been lacking. Here, we demonstrate a method based on two complementary techniques widely available in transmission electron microscopes (TEMs) to map the layer count of multilayer hexagonal boron nitride (h-BN) films. The mass-thickness contrast in high-angle annular dark-field (HAADF) imaging in the scanning transmission electron microscope (STEM) mode allows for thickness determination in atomically clean regions with high spatial resolution (sub-nanometer), but is limited by surface contamination. To complement, another technique based on the boron K ionization edge in the electron energy loss spectroscopy spectrum (EELS) of h-BN is developed to quantify the layer count so that surface contamination does not cause an overestimate, albeit at a lower spatial resolution (nanometers). The two techniques agree remarkably well in atomically clean regions with discrepancies within  ±1 layer. For the first time, the layer count uniformity on the scale of nanometers is quantified for a 2D material. The methodology is applicable to layer count mapping of other 2D layered materials, paving the way toward the synthesis of multilayer 2D materials with homogeneous layer count.

  15. Permeability change with dissolution and precipitation reaction induced by highly alkaline plume in packed bed with amorphous silica particles

    Komatsu, Kyo; Kadowaki, Junichi; Niibori, Yuichi; Mimura, Hitoshi; Usui, Hideo

    2008-01-01

    A large amount of cement is used to construct of the geological disposal system. Such a material alters the pH of groundwater to highly alkaline region. The highly alkaline plume contains rich Ca ion compared to the surrounding environment, and the Ca ion reacts with soluble silicic acid. Its product would deposit on the surface of flow-paths in the natural barrier and decrease the permeability. In this study, the influence of Ca ions in highly alkaline plume on flow-paths has been examined by using packed bed column. The column was packed with the amorphous silica particles of 75-150 μm in diameter. The Ca(OH) 2 solution (0.78 mM, 2.58 mM, 4.37 mM, and 8.48 mM, pH: 12.2-12.4) was continuously injected into the column at a constant flow rate (5 ml/min, and 2 ml/min), and the change of permeability was monitored. At the same time, the concentrations of [Ca] total and [Si] in the eluted solution were measured by the inductively coupled plasma atomic emission spectrometry (ICP-AES). The Ca(OH) 2 solutions were prepared with CO 2 -free pure water, and filtrated through 0.45 μm filter. The permeability was normalized by the initial permeability value. In the experiment results, the permeability dramatically changed with increasing Ca concentration, because Ca ions and H 4 SiO 4 (due to the dissolution of SiO 2 ) produce C-S-H gel between the packed particles in the column. The SEM images and XRD analyses showed that the surface of SiO 2 particles was covered with the C-S-H gel precipitation. On the other hand, when the Ca concentration was relatively low, the permeability did not show remarkable change. For the cross section of SiO 2 particles, EPMA analysis suggested the consumption of Ca in the inner pore of the SiO 2 particles. However, the time-change in the concentrations of Si and Ca was not always simple. Such time-change strongly depended not only on pH or Ca concentration, but also on the flow rates. This suggested that mass transport controls the chemical

  16. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater

    Fukuda, Daisuke; Nara, Yoshitaka; Hayashi, Daisuke; Ogawa, Hideo; Kaneko, Katsuhiko

    2013-01-01

    For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC) specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT). In particular, the influence of fracture width (0.10 and 0.25 mm) on fracture sealing was investigated. Precipitation occurred mainly at the outermost pa...

  17. High frequency permeability and permittivity spectra of BiFeO{sub 3}/(CoTi)-BaM ferrite composites

    Peng, Yun; Wu, Xiaohan; Li, Qifan; Yu, Ting; Feng, Zekun, E-mail: fengzekun@hust.edu.cn [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Zhongyan [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Jiangmen Magsource New Material CO., LTD., 529000 Guangdong (China); Su, Zhijuan; Chen, Yajie; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)

    2015-05-07

    Low magnetic loss ferrite composites consisting of Ba(CoTi){sub 1.2}Fe{sub 9.6}O{sub 19} and BiFeO{sub 3} (BFO) ferrite were investigated for permeability, permittivity, and high frequency losses at 10 MHz–1 GHz. The phase fraction of BiFeO{sub 3} was quantitatively analyzed by X-ray diffraction measurements. An effective medium approach was employed to predict the effective permeability and permittivity for the ferrite composites, which was found to be in good agreement with experimental data. The experiment demonstrated low magnetic losses (<0.128), modified by BFO phase fraction, while retaining high permeability (∼10.86) at 300 MHz. More importantly, the BFO phase resulted in a reduction of magnetic loss by 32%, as BFO phase increased from 2.7 vol. % to 12.6 vol. %. The effect of BFO phase on magnetic and dielectric properties revealed great potential for use in the miniaturization of high efficiency antennas.

  18. Layered compression for high-precision depth data.

    Miao, Dan; Fu, Jingjing; Lu, Yan; Li, Shipeng; Chen, Chang Wen

    2015-12-01

    With the development of depth data acquisition technologies, access to high-precision depth with more than 8-b depths has become much easier and determining how to efficiently represent and compress high-precision depth is essential for practical depth storage and transmission systems. In this paper, we propose a layered high-precision depth compression framework based on an 8-b image/video encoder to achieve efficient compression with low complexity. Within this framework, considering the characteristics of the high-precision depth, a depth map is partitioned into two layers: 1) the most significant bits (MSBs) layer and 2) the least significant bits (LSBs) layer. The MSBs layer provides rough depth value distribution, while the LSBs layer records the details of the depth value variation. For the MSBs layer, an error-controllable pixel domain encoding scheme is proposed to exploit the data correlation of the general depth information with sharp edges and to guarantee the data format of LSBs layer is 8 b after taking the quantization error from MSBs layer. For the LSBs layer, standard 8-b image/video codec is leveraged to perform the compression. The experimental results demonstrate that the proposed coding scheme can achieve real-time depth compression with satisfactory reconstruction quality. Moreover, the compressed depth data generated from this scheme can achieve better performance in view synthesis and gesture recognition applications compared with the conventional coding schemes because of the error control algorithm.

  19. Growth of high purity semiconductor epitaxial layers by liquid phase ...

    Unknown

    semiconductor materials in high purity form by liquid phase epitaxy (LPE) technique. Various possible sources of impurities in such ... reference to the growth of GaAs layers. The technique of growing very high purity layers ... the inner walls of the gas lines and (e) the containers for storing, handling and cleaning of the mate-.

  20. Numerical Simulation of a Non-volcanic Hydrothermal System Caused by Formation of a High Permeability Fracture Zone

    Oka, Daisuke; Ehara, Sachio; Fujimitsu, Yasuhiro

    2010-05-01

    Because in the Japanese islands the earth crust activity is very active, a disposal stratum for high-level radioactive waste produced by reprocessing the spent nuclear fuel from nuclear power plants will be selected in the tectonically stable areas in which the waste can be disposed underground safely for a long term and there is no influence of earthquakes, seismic activities, volcanic activities, upheaval, sedimentation, erosion, climate and global sea level change and so on, which causes the risk of the inflow of the groundwater to destroy the disposal site or the outflow to the ground surface. However, even if the disposal stratum in such condition will be chosen, in case that a new high permeability fracture zone is formed by the earthquake, and a new hydrothermal system may be formed for a long term (thousands or millions years) and the system may affect the disposal site. Therefore, we have to understand the feature of the non-volcanic hydrothermal system through the high permeability fracture zone. We estimated such influence by using HYDROTHERM Ver2.2 (Hayba & Ingebritsen, 1994), which is a three-dimensional numerical reservoir simulator. The model field is the northwestern part of Kego Fault, which was formed by a series of earthquakes called "the 2005 Fukuoka Prefecture Western Offshore Earthquakes" (the main shock of Mjma 7.0 on 20 March 2005) in Kyushu, Japan. The results of the numerical simulations show the development of a low temperature hydrothermal system as a new fracture zone is formed, in case that there is no volcanic heat source. The results of the simulations up to 100,000 years after formation of the fracture zone show that the higher heat flow and the wider and more permeable fracture zone accelerate the development of the hydrothermal system in the fracture zone. As a result of calculation of up to10 million years, we clarified the evolutional process of the non-volcanic hydrothermal system through the high permeability fracture zone. At

  1. High frequency ground temperature fluctuation in a Convective Boundary Layer

    Garai, A.; Kleissl, J.; Lothon, M.; Lohou, F.; Pardyjak, E.; Saïd, F.; Cuxart, J.; Steeneveld, G.J.; Yaguë, C.; Derrien, S.; Alexander, D.; Villagrasa, D.M.

    2012-01-01

    To study influence of the turbulent structures in the convective boundary layer (CBL) on the ground temperature, during the Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST) observational campaign, high frequency ground temperature was recorded through infra-red imagery from 13 June - 8

  2. Permeability of porour rhyolite

    Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

    2003-04-01

    The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures

  3. Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes.

    Shen, Yue-Xiao; Song, Woochul C; Barden, D Ryan; Ren, Tingwei; Lang, Chao; Feroz, Hasin; Henderson, Codey B; Saboe, Patrick O; Tsai, Daniel; Yan, Hengjing; Butler, Peter J; Bazan, Guillermo C; Phillip, William A; Hickey, Robert J; Cremer, Paul S; Vashisth, Harish; Kumar, Manish

    2018-06-12

    Synthetic polymer membranes, critical to diverse energy-efficient separations, are subject to permeability-selectivity trade-offs that decrease their overall efficacy. These trade-offs are due to structural variations (e.g., broad pore size distributions) in both nonporous membranes used for Angstrom-scale separations and porous membranes used for nano to micron-scale separations. Biological membranes utilize well-defined Angstrom-scale pores to provide exceptional transport properties and can be used as inspiration to overcome this trade-off. Here, we present a comprehensive demonstration of such a bioinspired approach based on pillar[5]arene artificial water channels, resulting in artificial water channel-based block copolymer membranes. These membranes have a sharp selectivity profile with a molecular weight cutoff of ~ 500 Da, a size range challenging to achieve with current membranes, while achieving a large improvement in permeability (~65 L m -2  h -1  bar -1  compared with 4-7 L m -2  h -1  bar -1 ) over similarly rated commercial membranes.

  4. Atomic layer deposition of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/TiO{sub 2} barrier coatings to reduce the water vapour permeability of polyetheretherketone

    Ahmadzada, Tamkin, E-mail: tahm4852@uni.sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); McKenzie, David R.; James, Natalie L.; Yin, Yongbai [School of Physics, University of Sydney, NSW 2006 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

    2015-09-30

    We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/TiO{sub 2} nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al{sub 2}O{sub 3}/TiO{sub 2} coating to PEEK, while the single layer Al{sub 2}O{sub 3} coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al{sub 2}O{sub 3}/TiO{sub 2} coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al{sub 2}O{sub 3}/TiO{sub 2} bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al{sub 2}O{sub 3}/TiO{sub 2} coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

  5. Artificial dispersion via high-order homogenization: magnetoelectric coupling and magnetism from dielectric layers

    Liu, Yan; Guenneau, Sébastien; Gralak, Boris

    2013-01-01

    We investigate a high-order homogenization (HOH) algorithm for periodic multi-layered stacks. The mathematical tool of choice is a transfer matrix method. Expressions for effective permeability, permittivity and magnetoelectric coupling are explored by frequency power expansions. On the physical side, this HOH uncovers a magnetoelectric coupling effect (odd-order approximation) and artificial magnetism (even-order approximation) in moderate contrast photonic crystals. Comparing the effective parameters' expressions of a stack with three layers against that of a stack with two layers, we note that the magnetoelectric coupling effect vanishes while the artificial magnetism can still be achieved in a centre-symmetric periodic structure. Furthermore, we numerically check the effective parameters through the dispersion law and transmission property of a stack with two dielectric layers against that of an effective bianisotropic medium: they are in good agreement throughout the low-frequency (acoustic) band until the first stop band, where the analyticity of the logarithm function of the transfer matrix () breaks down. PMID:24101891

  6. Modeling of heat and high viscous fluid distributions with variable viscosity in a permeable channel

    J Hona

    2016-10-01

    Full Text Available The flow field under study is characterized by velocity components, temperature and pressure in non-dimensional formulation. The flow is driven by suction through the horizontal channel with permeable walls fixed at different temperatures. In order to ascertain a better understanding of the dynamic behavior of the flow, the Navier-Stokes equations and the energy equation are solved concurrently applying a similarity transformation technique. The hydrodynamic structures obtained from the numerical integration include flow reversal or backward flow, collision zones due to the coexistence of wall suction and flow reversal inside the channel, the inflection through temperature distribution, the growth of thermal gradients near the walls, and the sensitivity of normal pressure gradients to the difference of temperatures at boundaries. These hydrodynamic structures are investigated considering the influences of the Péclet number P and the sensitivity of viscosity to thermal variations α which are the main control parameters of the problem.

  7. Effects of impurities on hydrogen permeability through palladium alloy membrane at comparatively high pressure and temperature

    Yoshida, Hiroshi; Konishi, Satoshi; Katsuta, Hiroji; Naruse, Yuji

    1982-02-01

    Palladium alloy membrane method is considered to be a useful technique for fusion reactor fuel purification process. To study the feasibility of this method, the effects of impurities on permeation characteristics of palladium alloy membrane were examined. Experiments were carried out at practical conditions: pressure; 120 - 1200 kPa, temperature; about 700 K. No poisoning effect on hydrogen permeability of commercial Pd-Ag (Au.Ru) alloy was observed for impurities such as NH 3 , CH 4 , CO, CO 2 , O 2 and N 2 , which were mixed with hyper-pure H 2 at low concentration level (10 - 10000 ppm). Deterioration occurred by contamination with oil vapor. However, regeneration of the membrane was easily performed by air baking followed by hydrogen reduction. Chemical reactions in the permeation cell were also examined. (author)

  8. Spontaneous layering of porous silicon layers formed at high current densities

    Parkhutik, Vitali; Curiel-Esparza, Jorge; Millan, Mari-Carmen [R and D Center MTM, Technical University of Valencia, Valencia (Spain); Albella, Jose [Institute of Materials Science (ICMM CSIC) Madrid (Spain)

    2005-06-01

    We report here a curious effect of spontaneous fracturing of the silicon layers formed in galvanostatic conditions at medium and high current densities. Instead of formation of homogeneous p-Si layer as at low currents, a stack of thin layers is formed. Each layer is nearly separated from others and possesses rather flat interfaces. The effects is observed using p{sup +}-Si wafers for the p-Si formation and starts being noticeable at above 100 mA/cm{sup 2}. We interpret these results in terms of the porous silicon growth model where generation of dynamic mechanical stress during the p-Si growth causes sharp changes in Si dissolution mechanism from anisotropic etching of individual needle-like pores in silicon to their branching and isotropic etching. At this moment p-Si layer loses its adhesion to the surface of Si wafer and another p-Si layer starts growing. One of the mechanisms triggering on the separation of p-Si layers from one another is a fluctuation of local anodic current in the pore bottoms associated with gas bubble evolution during the p-Si formation. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Bec Model of HIGH-Tc Superconductivity in Layered Cuprates

    Lomnitz, M.; Villarreal, C.; de Llano, M.

    2013-11-01

    High-Tc superconductivity in layered cuprates is described in a BCS-BEC formalism with linearly-dispersive s- and d-wave Cooper pairs moving in quasi-2D finite-width layers around the CuO2 planes. This yields a closed formula for Tc involving the layer width, the Debye frequency, the pairing energy and the in-plane penetration depth. The new formula has no free parameters and reasonably reproduces empirical values of superconducting Tcs for 11 different layered superconductors over a wide doping regime including YBCO itself as well as other compounds like LSCO, BSCCO and TBCCO. In agreement with the London formalism, the formula also yields a fair description of the Tc dependence of the lower critical magnetic field in highly underdoped YBCO.

  10. High voltage switches having one or more floating conductor layers

    Werne, Roger W.; Sampayan, Stephen; Harris, John Richardson

    2015-11-24

    This patent document discloses high voltage switches that include one or more electrically floating conductor layers that are isolated from one another in the dielectric medium between the top and bottom switch electrodes. The presence of the one or more electrically floating conductor layers between the top and bottom switch electrodes allow the dielectric medium between the top and bottom switch electrodes to exhibit a higher breakdown voltage than the breakdown voltage when the one or more electrically floating conductor layers are not present between the top and bottom switch electrodes. This increased breakdown voltage in the presence of one or more electrically floating conductor layers in a dielectric medium enables the switch to supply a higher voltage for various high voltage circuits and electric systems.

  11. Layer-by-Layer Assembly for Preparation of High-Performance Forward Osmosis Membrane

    Yang, Libin; Zhang, Jinglong; Song, Peng; Wang, Zhan

    2018-01-01

    Forward osmosis (FO) membrane with high separation performance is needed to promote its practical applications. Herein, layer-by-layer (LbL) approach was used to prepare a thin and highly cross-linked polyamide layer on a polyacrylonitrile substrate surface to prepare a thin-film composite forward osmosis (TFC-FO) membrane with enhanced FO performance. The effects of monomer concentrations and assembly cycles on the performance of the TFC-FO membranes were systematically investigated. Under the optimal preparation condition, TFC-FO membrane achieved the best performance, exhibiting the water flux of 14.4/6.9 LMH and reverse salt flux of 7.7/3.8 gMH under the pressure retarded osmosis/forward osmosis (PRO/FO) mode using 1M NaCl as the draw against a DI-water feed, and a rejection of 96.1% for 2000 mg/L NaCl aqueous solution. The result indicated that layer-by-layer method was a potential method to regulate the structure and performance of the TFC-FO membrane.

  12. Highly organic natural media as permeable reactive barriers: TCE partitioning and anaerobic degradation profile in eucalyptus mulch and compost.

    Öztürk, Zuhal; Tansel, Berrin; Katsenovich, Yelena; Sukop, Michael; Laha, Shonali

    2012-10-01

    Batch and column experiments were conducted with eucalyptus mulch and commercial compost to evaluate suitability of highly organic natural media to support anaerobic decomposition of trichloroethylene (TCE) in groundwater. Experimental data for TCE and its dechlorination byproducts were analyzed with Hydrus-1D model to estimate the partitioning and kinetic parameters for the sequential dechlorination reactions during TCE decomposition. The highly organic natural media allowed development of a bioactive zone capable of decomposing TCE under anaerobic conditions. The first order TCE biodecomposition reaction rates were 0.23 and 1.2d(-1) in eucalyptus mulch and compost media, respectively. The retardation factors in the eucalyptus mulch and compost columns for TCE were 35 and 301, respectively. The results showed that natural organic soil amendments can effectively support the anaerobic bioactive zone for remediation of TCE contaminated groundwater. The natural organic media are effective environmentally sustainable materials for use in permeable reactive barriers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Fluid-flow measurements in low permeability media with high pressure gradients using neutron imaging: Application to concrete

    Yehya, Mohamad; Andò, Edward; Dufour, Frédéric; Tengattini, Alessandro

    2018-05-01

    This article focuses on a new experimental apparatus for investigating fluid flow under high pressure gradients within low-permeability porous media by means of neutron imaging. A titanium Hassler cell which optimises neutron transparency while allowing high pressure confinement (up to 50 MPa) and injection is designed for this purpose and presented here. This contribution focuses on the development of the proposed methodology thanks to some preliminary results obtained using a new neutron imaging facility named NeXT on the D50 beamline at the Institute Laue Langevin (Grenoble). The preliminary test was conducted by injecting normal water into concrete sample prepared and saturated with heavy water to take advantage of the isotope sensitivity of neutrons. The front between these two types of water is tracked in space and time with a combination of neutron radiography and tomography.

  14. Solute transport processes in a highly permeable fault zone of Lindau fractured rock test site (Germany)

    Himmelsbach, T. [Ruhr-Univ., Bochum (Germany). Dept. of Applied Geology; Hoetzl, H. [Univ. of Karlsruhe (Germany). Dept. of Applied Geology; Maloszewski, P. [GSF-Inst. for Hydrology, Munich-Neuherberg (Germany)

    1998-09-01

    The results of field tracer experiments performed in the Lindau fractured rock test site (southern Black Forest, Germany) and subsequent modeling are presented. A vertical, hydrothermally mineralized fault zone, with a permeability much greater than the surrounding granite mass, lies beneath a planned dam site. A dense network of boreholes and tunnels were used to investigate scaling effects of solute transport processes in fractured rock. A series of tracer experiments using deuterium and dye tracers were performed over varying distances and under different testing procedures, resulting in different flow field conditions. Large-scale tracer experiments were performed under natural flow field conditions, while small-scale tracer experiments were performed under artificially induced radial-convergent and injection-withdrawal flow fields. The tracer concentration curves observed in all experiments were strongly influenced by the matrix diffusion. The curves were evaluated with the one-dimensional single fissure dispersion model (SFDM) adjusted for the different flow field conditions. The fitting model parameters found determined the fracture aperture, and matrix and fissure porosities. The determined fracture aperture varied between the sections having different hydraulic conductivity. The determined values of matrix porosity seemed to be independent of the scale of the experiment. The modeled matrix porosities agreed well with values determined in independent laboratory investigations of drill cores using mercury porosimetry. In situ fissure porosity, determined only in small-scale experiments, was independent of the applied geometry of the artificially induced flow fields. The dispersivities were found to be independent of the scale of experiment but dependent on the flow conditions. The values found in forced gradient tests lie between 0.2 and 0.3 m, while values in experiments performed under natural flow conditions were one order of magnitude higher.

  15. Observations of propagating double layers in a high current discharge

    Lindberg, L.

    1988-01-01

    Observations of current disruptions and strong electric fields along the magnetic field in a high-density (2 x 10 19 m - 3 , highly-ionized, moving, and expanding plasma column are reported. The electric field is interpreted in terms of propagating, strong electric double layers (3-5kV). An initial plasma column is formed in an axial magnetic field (0.1T) by means of a conical theta-pinch plasma gun. When an axial current (max 5kA, 3-5 kV) is drawn through the column spontaneous disruptions and double-layer formation occur within a few microseconds. Floating, secondary emitting Langmuir probes are used. They often indicate very high positive potential peaks (1-2 kV above the anode potential during a few μs) in the plasma on the positive side of the double layer. Short, intense bursts of HF radiation are detected at the disruptions

  16. Optimisation of the microporous layer for a polybenzimidazole-based high temperature PEMFC - effect of carbon content

    Lobato, J.; Canizares, P.; Rodrigo, M.A.; Ubeda, D.; Pinar, F.J.; Linares, J.J. [Department of Chemical Engineering, University of Castilla-La Mancha, Av. Camilo Jose Cela, n 12. 13071, Ciudad Real (Spain)

    2010-10-15

    This work aims at studying the role of the microporous layer (MPL) in electrodes prepared for high temperature PBI-based PEMFC. The two main components of this layer are carbon black and a polymeric binder (Teflon). This work addresses the effect of the MPL carbon amount on the performance of a high temperature PEMFC. Thus, gas diffusion layers (GDLs) containing MPL with different carbon contents (from 0.5 to 4 mg cm{sup -2}) were prepared. Firstly, they were physically characterised by Hg-porosimetry measuring pore size distribution, porosity, tortuosity and mean pore size. Permeability measurements were also performed. The higher the carbon content was the lower both porosity and permeability were. Afterwards, electrodes were prepared with these GDLs and were electrochemically characterised. Electrochemical surface area (ESA) was determined and fuel cell performance was evaluated under different fuel and comburent stoichiometries, supporting these results with impedance spectra. This made it possible to see the benefits of the MPL inclusion in the electrode structure, with a significant increase in the fuel cell performance and ESA. Once the goodness of the MPL was confirmed, result analysis led to an optimum MPL composition of 2 mg cm{sup -2} of carbon for both electrodes, anode and cathode. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  17. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy.

    Ruff, S Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g(-1) day(-1) indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20-50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  18. Methane seep in shallow-water permeable sediment harbors high diversity of anaerobic methanotrophic communities, Elba, Italy

    S Emil Ruff

    2016-03-01

    Full Text Available The anaerobic oxidation of methane (AOM is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME and sulfate-reducing bacteria (SRB, and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic-carbon depleted permeable sands off the Island of Elba (Italy. We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g-1 day-1 indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20–50 cm below seafloor as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3 and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise

  19. Methane Seep in Shallow-Water Permeable Sediment Harbors High Diversity of Anaerobic Methanotrophic Communities, Elba, Italy

    Ruff, S. Emil; Kuhfuss, Hanna; Wegener, Gunter; Lott, Christian; Ramette, Alban; Wiedling, Johanna; Knittel, Katrin; Weber, Miriam

    2016-01-01

    The anaerobic oxidation of methane (AOM) is a key biogeochemical process regulating methane emission from marine sediments into the hydrosphere. AOM is largely mediated by consortia of anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB), and has mainly been investigated in deep-sea sediments. Here we studied methane seepage at four spots located at 12 m water depth in coastal, organic carbon depleted permeable sands off the Island of Elba (Italy). We combined biogeochemical measurements, sequencing-based community analyses and in situ hybridization to investigate the microbial communities of this environment. Increased alkalinity, formation of free sulfide and nearly stoichiometric methane oxidation and sulfate reduction rates up to 200 nmol g-1 day-1 indicated the predominance of sulfate-coupled AOM. With up to 40 cm thickness the zones of AOM activity were unusually large and occurred in deeper sediment horizons (20–50 cm below seafloor) as compared to diffusion-dominated deep-sea seeps, which is likely caused by advective flow of pore water due to the shallow water depth and permeability of the sands. Hydrodynamic forces also may be responsible for the substantial phylogenetic and unprecedented morphological diversity of AOM consortia inhabiting these sands, including the clades ANME-1a/b, ANME-2a/b/c, ANME-3, and their partner bacteria SEEP-SRB1a and SEEP-SRB2. High microbial dispersal, the availability of diverse energy sources and high habitat heterogeneity might explain that the emission spots shared few microbial taxa, despite their physical proximity. Although the biogeochemistry of this shallow methane seep was very different to that of deep-sea seeps, their key functional taxa were very closely related, which supports the global dispersal of key taxa and underlines strong selection by methane as the predominant energy source. Mesophilic, methane-fueled ecosystems in shallow-water permeable sediments may comprise distinct

  20. Hysteresis properties of the amorphous high permeability Co66Fe3Cr3Si15B13 alloy

    V. S. Tsepelev

    2018-04-01

    Full Text Available The scaling law of minor loops was studied on an amorphous alloy Co66Fe3Cr3Si15B13 with a very high initial permeability (more than 150000 and low coercivity (about 0.1 A/m. An analytical expression for the coercive force in the Rayleigh region was derived. The coercive force is connected with the maximal magnetic field Hmax via the reversibility coefficient μi/ηHmax. Reversibility coefficient shows the relationship between reversible and irreversible magnetization processes. A universal dependence of magnetic losses for hysteresis Wh on the remanence Br with a power factor of 1.35 is confirmed for a wide range of magnetic fields strengths.

  1. Vortex Generator Induced Flow in a High Re Boundary Layer

    Velte, Clara Marika; Braud, C.; Coudert, S.

    2014-01-01

    Stereoscopic Particle Image Velocimetry measurements have been conducted in cross-planes behind three different geometries of Vortex Generators (VGs) in a high Reynolds number boundary layer. The VGs have been mounted in a cascade producing counter-rotating vortices and the downstream flow...... development was examined. Three VG geometries were investigated: rectangular, triangular and cambered. The various VG geometries tested are seen to produce different impacts on the boundary layer flow. Helical symmetry of the generated vortices is confirmed for all investigated VG geometries in this high...... Reynolds number boundary layer. From the parameters resulting from this analysis, it is observed at the most upstream measurement position that the rectangular and triangular VGs produce vortices of similar size, strength and velocity induction whilst the cambered VGs produce smaller and weaker vortices...

  2. Vortex Generator Induced Flow in a High Re Boundary Layer

    Velte, Clara Marika; Braud, C.; Coudert, S.

    2012-01-01

    Stereoscopic Particle Image Velocimetry measurements have been conducted in cross-planes behind three different geometries of Vortex Generators (VGs) in a high Reynolds number boundary layer. The VGs have been mounted in a cascade producing counter-rotating vortices and the downstream flow...... development was examined. Three VG geometries were investigated: rectangular, triangular and cambered. The various VG geometries tested are seen to produce different impacts on the boundary layer flow. Helical symmetry of the generated vortices is confirmed for all investigated VG geometries in this high...... Reynolds number boundary layer. From the parameters resulting from this analysis, it is observed at the most upstream measurement position that the rectangular and triangular VGs produce vortices of similar size, strength and velocity induction whilst the cambered VGs produce smaller and weaker vortices...

  3. Confirmation tests of construction method and initial performance quality for low permeable engineered barrier in side part of radioactive waste disposal facilities

    Yamada, Atsuo; Chijimatsu, Masakazu; Akiyama, Yoshihiro; Komine, Hideo; Iizuka, Atsushi

    2016-01-01

    As for the low permeable layer, important functions are expected as an engineered barrier of radioactive waste disposal for low-level waste with comparatively high radiation levels. On examining the construction methods of this low permeable layer, it is important to confirm the possibility of the construction in the conditions similar to the actual constructed conditions with a true scale size. Therefore, the construction examination for the side part of the low permeable layer by bentonite and the performance check test of the low permeable layer were carried out. The result of the construction examination showed that the possibility of the construction were confirmed, and the result of performance check test showed that it was possible to ensure the required performance of the low permeable layer, such as hydraulic conductivity. (author)

  4. Inhibitory effect of high [Mg2+] on the vasopressin-stimulated hydroosmotic permeability of the isolated perfused cortical collecting duct

    Falkenstein D.

    1999-01-01

    Full Text Available High magnesium concentration inhibits the effect of arginine vasopressin (AVP on smooth muscle contraction and platelet aggregation and also influences hepatocyte AVP receptor binding. The aim of this study was to determine the role of magnesium concentration [Mg2+] in AVP-stimulated water transport in the kidney collecting duct. The effect of low and high peritubular [Mg2+] on the AVP-stimulated osmotic water permeability coefficient (Pf was evaluated in the isolated perfused rabbit cortical collecting duct (CCD. Control tubules bathed and perfused with standard Ringer bicarbonate solution containing 1 mM Mg2+ presented a Pf of 223.9 ± 27.2 µm/s. When Mg2+ was not added to the bathing solution, an increase in the AVP-stimulated Pf to 363.1 ± 57.2 µm/s (P<0.05 was observed. An elevation of Mg2+ to 5 mM resulted in a decrease in Pf to 202.9 ± 12.6 µm/s (P<0.05. This decrease in the AVP-stimulated Pf at 5 mM Mg2+ persisted when the CCDs were returned to 1 mM Mg2+, Pf = 130.2 ± 20.3 µm/s, and was not normalized by the addition of 8-[4-chlorophenylthio]-adenosine 3',5'-cyclic monophosphate, a cAMP analogue, to the preparation. These data indicate that magnesium may play a modulatory role in the action of AVP on CCD osmotic water permeability, as observed in other tissues.

  5. Response of the Atmospheric Boundary Layer and Soil Layer to a High Altitude, Dense Aerosol Cover.

    Garratt, J. R.; Pittock, A. B.; Walsh, K.

    1990-01-01

    The response of the atmospheric boundary layer to the appearance of a high-altitude smoke layer has been investigated in a mesoscale numerical model of the atmosphere. Emphasis is placed on the changes in mean boundary-layer structure and near-surface temperatures when smoke of absorption optical depth (AOD) in the, range 0 to 1 is introduced. Calculations have been made at 30°S, for different soil thermal properties and degrees of surface wetness, over a time period of several days during which major smoke-induced cooling occurs. The presence of smoke reduces the daytime mixed-layer depth and, for large enough values of AOD, results in a daytime surface inversion with large cooling confined to heights of less than a few hundred meters. Smoke-induced reductions in daytime soil and air temperatures of several degrees are typical, dependent critically upon soil wetness and smoke AOD. Locations near the coast experience reduced cooling whenever there is a significant onshore flow related to a sea breeze (this would also be the case with a large-scale onshore flow). The sea breeze itself disappears for large enough smoke AOD and, over sloping coastal terrain, a smoke-induced, offshore drainage flow may exist throughout the diurnal cycle.

  6. Designing high-Performance layered thermoelectric materials through orbital engineering

    Zhang, Jiawei; Song, Lirong; Madsen, Georg K. H.

    2016-01-01

    Thermoelectric technology, which possesses potential application in recycling industrial waste heat as energy, calls for novel high-performance materials. The systematic exploration of novel thermoelectric materials with excellent electronic transport properties is severely hindered by limited...... insight into the underlying bonding orbitals of atomic structures. Here we propose a simple yet successful strategy to discover and design high-performance layered thermoelectric materials through minimizing the crystal field splitting energy of orbitals to realize high orbital degeneracy. The approach...... naturally leads to design maps for optimizing the thermoelectric power factor through forming solid solutions and biaxial strain. Using this approach, we predict a series of potential thermoelectric candidates from layered CaAl2Si2-type Zintl compounds. Several of them contain nontoxic, low-cost and earth...

  7. On the applicability of the layered sine-Gordon model for Josephson-coupled high-Tc layered superconductors

    Nandori, I; Jentschura, U D; Nagy, S; Sailer, K; Vad, K; Meszaros, S

    2007-01-01

    We find a mapping of the layered sine-Gordon model to an equivalent gas of topological excitations and determine the long-range interaction potentials of the topological defects. This enables us to make a detailed comparison to the so-called layered vortex gas, which can be obtained from the layered Ginzburg-Landau model. The layered sine-Gordon model has been proposed in the literature as a candidate field-theoretical model for Josephson-coupled high-T c superconductors, and the implications of our analysis for the applicability of the layered sine-Gordon model to high-T c superconductors are discussed. We are led to the conjecture that the layered sine-Gordon and the layered vortex gas models belong to different universality classes. The determination of the critical temperature of the layered sine-Gordon model is based on a renormalization-group analysis

  8. A new infiltration method for coating highly permeable matrices with compound materials for high-power isotope-separator-on-line production target applications

    Kawai, Y.; Bilheux, Jean-Christophe; Stracener, Daniel W; Alton, Gerald D

    2005-01-01

    A new infiltration coating method has been conceived for uniform and controlled thickness deposition of target materials onto highly permeable, complex-structure matrices to form short-diffusion-length isotope-separator-on-line (ISOL) production targets for radioactive ion beam research applications. In this report, the infiltration technique is described in detail and the universal character of the technique illustrated in the form of SEMs of several metal-carbide, metal-oxide and metal-sulfide targets for potential use at present or future radioactive ion beam research facilities

  9. Rational design of intrinsically ultramicroporous polyimides containing bridgehead-substituted triptycene for highly selective and permeable gas separation membranes

    Swaidan, Raja

    2014-08-12

    Highly ultramicroporous, solution-processable polyimides bearing 9,10-bridgehead-substituted triptycene demonstrated the highest BET surface area reported for polyimides (840 m2 g-1) and several new highs in gas selectivity and permeability for hydrogen (1630-3980 barrers, H2/CH4 ∼ 38) and air (230-630 barrers, O 2/N2 = 5.5-5.9) separations. Two new dianhydrides bearing 9,10-diethyl- and 9,10-dipropyltriptycenes indicate that the ultramicroporosity is optimized for fast polymeric sieving with the use of short, bulky isopropyl bridgeheads and methyl-substituted diamines (TrMPD, TMPD, and TMBZ) that increase intrachain rigidity. Mechanically, the triptycene-based analogue of a spirobisindane-based polyimide exhibited 50% increases in both tensile strength at break (94 MPa) and elastic modulus (2460 MPa) with corresponding 90% lower elongations at break (6%) likely due to the ability of highly entangled spiro-based chains to unwind. To guide future polyimide design, structure/property relationships are suggested between the geometry of the contortion center, the diamine and bridgehead substituent, and the mechanical, microstructural, and gas transport properties. © 2014 American Chemical Society.

  10. Rational design of intrinsically ultramicroporous polyimides containing bridgehead-substituted triptycene for highly selective and permeable gas separation membranes

    Swaidan, Raja; Al-Saeedi, Majed; Ghanem, Bader; Litwiller, Eric; Pinnau, Ingo

    2014-01-01

    Highly ultramicroporous, solution-processable polyimides bearing 9,10-bridgehead-substituted triptycene demonstrated the highest BET surface area reported for polyimides (840 m2 g-1) and several new highs in gas selectivity and permeability for hydrogen (1630-3980 barrers, H2/CH4 ∼ 38) and air (230-630 barrers, O 2/N2 = 5.5-5.9) separations. Two new dianhydrides bearing 9,10-diethyl- and 9,10-dipropyltriptycenes indicate that the ultramicroporosity is optimized for fast polymeric sieving with the use of short, bulky isopropyl bridgeheads and methyl-substituted diamines (TrMPD, TMPD, and TMBZ) that increase intrachain rigidity. Mechanically, the triptycene-based analogue of a spirobisindane-based polyimide exhibited 50% increases in both tensile strength at break (94 MPa) and elastic modulus (2460 MPa) with corresponding 90% lower elongations at break (6%) likely due to the ability of highly entangled spiro-based chains to unwind. To guide future polyimide design, structure/property relationships are suggested between the geometry of the contortion center, the diamine and bridgehead substituent, and the mechanical, microstructural, and gas transport properties. © 2014 American Chemical Society.

  11. Hydrogen selective NH{sub 2}-MIL-53(Al) MOF membranes with high permeability

    Zhang, Feng; Zou, Xiaoqin; Gao, Xue; Fan, Songjie; Sun, Fuxing; Ren, Hao; Zhu, Guangshan [State Key Laboratory of Inorganic, Synthesis and Preparative Chemistry, Jilin University, Changchun (China)

    2012-09-11

    Hydrogen-based energy is a promising renewable and clean resource. Thus, hydrogen selective microporous membranes with high performance and high stability are demanded. Novel NH{sub 2}-MIL-53(Al) membranes are evaluated for hydrogen separation for this goal. Continuous NH{sub 2}-MIL-53(Al) membranes have been prepared successfully on macroporous glass frit discs assisted with colloidal seeds. The gas sorption ability of NH{sub 2}-MIL-53(Al) materials is studied by gas adsorption measurement. The isosteric heats of adsorption in a sequence of CO{sub 2}> N{sub 2}> CH{sub 4}{approx} H{sub 2} indicates different interactions between NH{sub 2}-MIL-53(Al) framework and these gases. As-prepared membranes are measured by single and binary gas permeation at different temperatures. The results of singe gas permeation show a decreasing permeance in an order of H{sub 2}> CH{sub 4}> N{sub 2}> CO{sub 2}, suggesting that the diffusion and adsorption properties make significant contributions in the gas permeation through the membrane. In binary gas permeation, the NH{sub 2}-MIL-53(Al) membrane shows high selectivity for H{sub 2} with separation factors of 20.7, 23.9 and 30.9 at room temperature (288 K) for H{sub 2} over CH{sub 4}, N{sub 2} and CO{sub 2}, respectively. In comparison to single gas permeation, a slightly higher separation factor is obtained due to the competitive adsorption effect between the gases in the porous MOF membrane. Additionally, the NH{sub 2}-MIL-53(Al) membrane exhibits very high permeance for H{sub 2} in the mixtures separation (above 1.5 x 10{sup -6} mol m{sup -2} s{sup -1} Pa{sup -1}) due to its large cavity, resulting in a very high separation power. The details of the temperature effect on the permeances of H{sub 2} over other gases are investigated from 288 to 353 K. The supported NH{sub 2}-MIL-53(Al) membranes with high hydrogen separation power possess high stability, resistance to cracking, temperature cycling and show high reproducibility

  12. Similar Simulation Test on Permeability Evolution of Floor During Upper Protective Layer Mining in "Three Soft" Coal Seam%“三软”煤层上保护层开采底板围岩透气性演化相似试验研究

    撒占友; 李磊; 卢守青; 刘杰; 张辉

    2017-01-01

    In order to investigate the permeability evolution law of floor surrounding rock in "three soft" coal seam of high stress zone during the upper protective seam mining,taking the protective seam mining in Ji15-23130 working face of Henan Pingdingshan No.4 mine as the research object,similar experiments are carried out.The results show that the closer distance of the protective layers are,the larger displacement of the bottom is,the higher peak value of the stress curve is,and the smaller the minimum value is,the higher the permeability coefficient is.The permeability coefficient of floor in upper protective layer mining process has successively experienced three stages,they are "slow down-increase dramatically-slow down again",and there is little difference in the improvement of permeability coefficient at different positions of the same layer.The test also shows that the abrupt change and pressure relief in the process of upper protection layer mining is the important reason for the abnormal gas emission in the mining face.%为了探讨高应力区“三软”煤层上保护层开采底板围岩透气性演化规律,以河南平顶山四矿己15-23130工作面作上保护层煤层开采为研究对象,进行相似试验研究.结果表明,距保护层越近,底板位移量越大,应力曲线峰值越高,极小值越小,透气性系数提升越显著;底板透气性系数在上保护层开采过程中依次经历“缓慢下降-大幅提高-再次缓慢降低”3个阶段,同一层位不同水平位置底板透气性系数提高程度差别不大;上保护层开采过程中底板压力陡变卸压是导致工作面瓦斯异常涌出的重要原因.

  13. Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency.

    de Freitas, Normanda L; Gonçalves, José A S; Innocentini, Murilo D M; Coury, José R

    2006-08-25

    The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.

  14. AN EXPERIMENTAL STUDY ON STRENGTH AND PERMEABILITY PROPERTIES OF HIGH STRENGTH CONCRETE

    Yedla Venkatesh * & G. Kalyan

    2017-01-01

    Concrete is the most important engineering material and the addition of some other materials may change the properties of concrete. Mineral additions which are also known as mineral admixtures have been used with cements for many years. There are two types of materials crystalline and non crystalline. High performance concrete (HPC) exceeds the properties and constructability of normal concrete. Micro silica or silica fume is very fine non crystalline material. Silica fume is produced in elec...

  15. Contributions for the modelling of submarine cables – current density and simplified modelling of wired layers

    Silva, Filipe Miguel Faria da; Bak, Claus Leth; Ebdrup, Thomas

    2015-01-01

    formulae. The substitution of round wires by equivalent solid layers is tested and tuned by changing the permeability of the insulation and the resistivity of the of the substitution layer. The tuning of these two parameters allows obtaining similar results for both cases even for materials with high...... permeabilities, like steel....

  16. Creating the High-Resolution Settlement Layer - lessons learned

    Gros, A.

    2017-12-01

    Facebook publishes the High-resolution Settlement Layer (HRSL: https://ciesin.columbia.edu/data/hrsl/) in collaboration with Columbia University's CIESIN institute and the World Bank. So far, data for 13 countries have been published over the past nine months. HRSL data for Burkina Faso, Ghana, Haiti, Ivory Coast, Madagascar, Malawi, Mexico, The Philippines, Rwanda, South Africa, Sri Lanka, Thailand, and Uganda are available for download. We will present a status update and report on lessons learned.

  17. Through process texture evolution of new thin-gauge non-oriented electrical steels with high permeability

    Zhang, Ning; Yang, Ping, E-mail: yangp@mater.ustb.edu.cn; Mao, Wei-Min

    2016-01-01

    This paper demonstrated new methods for producing high permeability thin-gauge non-oriented electrical steels with columnar-grained 3.05% Si cast slabs containing carbon and MnS precipitates, and the texture evolution was investigated. The magnetic properties of 0.2 mm final sheets were greatly improved by the optimized texture comprising {100}〈0vw〉 and strong {hk0}〈001〉 components, and the best combination of B{sub 50} and P{sub 1.5} was exhibited as 1.764 T and 2.45 W/kg respectively. The texture evolution depended on both the moderate inhibiting effect of coarse MnS precipitates and rolling methods. {100}〈0vw〉 texture could be retained from columnar grains, and strong {hk0}〈001〉 texture was obtained by two-stage rolling in distinct ways: On one hand, for the sample corresponding to low second-stage rolling reduction of 60%, based on the large grain size prior to cold rolling, the higher strain of first-stage cold rolling promoted {hk0}〈001〉 nucleation during intermediate annealing. {hk0}〈001〉 grains were further increased after moderate second-stage cold rolling and decarburization annealing, consequently leading to the final strong {100}–{110}〈001〉 texture and uniform microstructure by quantity and size priorities, and the optimum magnetic properties were achieved; on the other hand, secondary recrystallization occurred on fine-grained decarburized matrix at higher second-stage rolling strains and greatly improved the magnetic induction in RD. The level of abnormal Goss grains growth was decreased in the sample corresponding to 80% second-stage rolling reduction, and normal growth of other beneficial grains lowered the magnetic anisotropy, suggesting another potential way for non-oriented electrical steel production. In addition, the effect of carbon was discussed. - Highlights: • New thin-gauge non-oriented electrical steels with high permeability were fabricated. • The magnetic properties were improved by {100}〈0vw〉 and

  18. Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

    Pan, Yichang; Wang, Bo; Lai, Zhiping

    2012-01-01

    Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

  19. Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

    Pan, Yichang

    2012-12-01

    Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

  20. Spermine selectively inhibits high-conductance, but not low-conductance calcium-induced permeability transition pore.

    Elustondo, Pia A; Negoda, Alexander; Kane, Constance L; Kane, Daniel A; Pavlov, Evgeny V

    2015-02-01

    The permeability transition pore (PTP) is a large channel of the mitochondrial inner membrane, the opening of which is the central event in many types of stress-induced cell death. PTP opening is induced by elevated concentrations of mitochondrial calcium. It has been demonstrated that spermine and other polyamines can delay calcium-induced swelling of isolated mitochondria, suggesting their role as inhibitors of the mitochondrial PTP. Here we further investigated the mechanism by which spermine inhibits the calcium-induced, cyclosporine A (CSA) -sensitive PTP by using three indicators: 1) calcium release from the mitochondria detected with calcium green, 2) mitochondrial membrane depolarization using TMRM, and 3) mitochondrial swelling by measuring light absorbance. We found that despite calcium release and membrane depolarization, indicative of PTP activation, mitochondria underwent only partial swelling in the presence of spermine. This was in striking contrast to the high-amplitude swelling detected in control mitochondria and in mitochondria treated with the PTP inhibitor CSA. We conclude that spermine selectively prevents opening of the high-conductance state, while allowing activation of the lower conductance state of the PTP. We propose that the existence of lower conductance, stress-induced PTP might play an important physiological role, as it is expected to allow the release of toxic levels of calcium, while keeping important molecules (e.g., NAD) within the mitochondrial matrix. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Magnetic ageing study of high and medium permeability nanocrystalline FeSiCuNbB alloys

    Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

    2017-04-15

    increasing the energy efficiency is one of the most important issues in modern power electronic systems. In aircraft applications, the energy efficiency must be associated with a maximum reduction of mass and volume, so a high components compactness. A consequence from this compactness is the increase of operating temperature. Thus, the magnetic materials used in these applications, have to work at high temperature. It raises the question of the thermal ageing problem. The reliability of these components operating at this condition becomes a real problem which deserves serious interest. Our work takes part in this context by studying the magnetic material thermal ageing. The nanocrystalline materials are getting more and more used in power electronic applications. Main advantages of nanocrystalline materials compared to ferrite are: high saturation flux density of almost 1.25 T and low dynamic losses for low and medium frequencies. The nanocrystalline Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloys have been chosen in our aging study. This study is based on monitoring the magnetic characteristics for several continuous thermal ageing (100, 150, 200 and 240 °C). An important experimental work of magnetic characterization is being done following a specific monitoring protocol. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The magnetic ageing of the nanocrystalline materials is related to their annealing. • The degradations with ageing are not related to a change of the grain size diameter. • The amount of anisotropies introduced with ageing depends just on ageing conditions.

  2. Small intestinal efflux mediated by MRP2 and BCRP shifts sulfasalazine intestinal permeability from high to low, enabling its colonic targeting.

    Dahan, Arik; Amidon, Gordon L

    2009-08-01

    Sulfasalazine is characterized by low intestinal absorption, which essentially enables its colonic targeting and therapeutic action. The mechanisms behind this low absorption have not yet been elucidated. The purpose of this study was to investigate the role of efflux transporters in the intestinal absorption of sulfasalazine as a potential mechanism for its low small-intestinal absorption and colonic targeting following oral administration. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on sulfasalazine bidirectional permeability were studied across Caco-2 cell monolayers, including dose-response analysis. Sulfasalazine in vivo permeability was then investigated in the rat jejunum by single-pass perfusion, in the presence vs. absence of inhibitors. Sulfasalazine exhibited 19-fold higher basolateral-to-apical (BL-AP) than apical-to-basolateral (AP-BL) Caco-2 permeability, indicative of net mucosal secretion. MRP2 inhibitors (MK-571 and indomethacin) and BCRP inhibitors [fumitremorgin C (FTC) and pantoprazole] significantly increased AP-BL and decreased BL-AP sulfasalazine Caco-2 transport in a concentration-dependent manner. No effect was observed with the P-gp inhibitors verapamil and quinidine. The IC50 values of the specific MRP2 and BCRP inhibitors MK-571 and FTC on sulfasalazine secretion were 21.5 and 2.0 microM, respectively. Simultaneous inhibition of MRP2 and BCRP completely abolished sulfasalazine Caco-2 efflux. Without inhibitors, sulfasalazine displayed low (vs. metoprolol) in vivo intestinal permeability in the rat model. MK-571 or FTC significantly increased sulfasalazine permeability, bringing it to the low-high permeability boundary. With both MK-571 and FTC present, sulfasalazine displayed high permeability. In conclusion, efflux transport mediated by MRP2 and BCRP, but not P-gp, shifts sulfasalazine permeability from high to low, thereby enabling its

  3. Very high geothermal gradient in near surface of the Whataroa Valley adjacent to the Alpine Fault: topographic driving forces and permeable mountains

    Upton, P.; Sutherland, R.; Townend, J.; Coussens, J.; Capova, L.

    2015-12-01

    The first phase of the Deep Fault Drilling Project (DFDP-1B) yielded a geothermal gradient of 62.6 ± 2.1 °C/km from a depth of 126 m where it intersected the Alpine Fault principal slip surface beneath Gaunt Creek (Sutherland et al. 2012). Ambient fluid pressures in DFDP-2B at Whataroa River were 8-10% above hydrostatic and a geothermal gradient of >130°C/km was determined, the geothermal gradient being considerably higher than we had predicted previously. 3D coupled thermal/fluid flow models have been generated of the Whataroa Valley and the DFDP-2 drill site. Modelling confirms that the following features, present in the Whataroa Valley, are a requirement for a geothermal gradient of >130°C/km at a depth of 1km beneath the valley; high topography, permeability on the order of 10-15 m2 in both the mountains and beneath the valleys to depths of > 1km below the valley floor, and abundant fluid. The high permeability and large topographic driving force leads to abundant meteoric water flowing downward through the mountains, hitting the permeability barrier of the Alpine Fault and being pushed upward into the valleys. The high geothermal gradient of the DFDP-2B borehole implies that the valleys also have a very high permeability which is likely a result of rock damage along the Alpine Fault.

  4. Relaxation and gas drainage boreholes for high performance longwall operations in low permeability coal seams

    Imgrund, Thomas [DMT GmbH und Co. KG, Essen (Germany); Bauer, Frank [Hazemag und EPR GmbH, Duelmen (Germany). Mining

    2013-06-15

    With an increasing depth of cover, gas emission control and gas outbursts prevention has become an increasingly important issue in coal mining. Deep multi-seam mining often requires operation in an environment characterised by a high gas content and gas pressure. Control of gas related risks has to be realised during heading and close to the longwall by proper risk assessment and flexible drilling schemes. These cover exploration and relaxation drilling, in-seam drilling for pre-drainage and cross measure drilling for drainage of roof and the floor gas emissions. DMT provides comprehensive solutions based on a scientific background. These solutions are engineered considering their technical feasibility. Hazemag Mining offers a large number of complete machinery including tools systems for the implementation of those solutions. (orig.)

  5. Road drainage system using highly compressible and long-term permeable geotextile. Evaluation of long-term permeability and application to trafficability in a tunnel; Kotaiatsu mezumari taikyugata geotextile haisuizai wo mochiita roban haisui taisaku. Mezumari taikyusei no hyoka to tunnel konai kasetsu doro no trafficability kaizen koka

    Takahashi, S.; Yamagishi, K.; Hirama, K.; Ueno, T. [Obayashi Corp., Tokyo (Japan)

    1998-07-10

    A geotextile drainage material called ART-DRAIN has been developed. It was applied to temporary roads in a tunnel, to evaluate its permeability through a long-term permeability test using a model. The ART-DRAIN is a drainage material for protecting the roads from muddy conditions in a tunnel due to spring water. A filter for permeating fine soil particles was employed to keep the permeability. From the long-term permeability test using a model, appropriate permeability of ART-DRAIN was maintained for three years without blinding. There was only a slight inflow of fine grain soils into the ART-DRAIN. It was confirmed that the permeability was not obstructed by the fine grain soils. The ART-DRAIN was applied to tunnel construction works for the high-speed railway in Kyoto and the national road in mountains. From these applications, factors for enhancing the permeability effect were confirmed, which includes the selection of high quality muck, insurance of the road-bed strength by the initial compaction, use of road drainage materials with high compressible property and permeability of filter, and intervals of drainage. 1 ref., 19 figs., 1 tab.

  6. Nanoparticle layer deposition for highly controlled multilayer formation based on high-coverage monolayers of nanoparticles

    Liu, Yue; Williams, Mackenzie G.; Miller, Timothy J.; Teplyakov, Andrew V.

    2016-01-01

    This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading to complete monolayer formation within the multilayer system without any additional intermediate layers — nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly 100% coverage of these nanoparticles with the use of “click chemistry”. Following this initial deposition, a second complete monolayer of nanoparticles is deposited using a copper-catalyzed “click reaction” with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling. - Highlights: • We investigate the formation of high-coverage monolayers of nanoparticles. • We use “click chemistry” to form these monolayers. • We form multiple layers based on the same strategy. • We confirm the formation of covalent bonds

  7. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater

    Katsuhiko Kaneko

    2013-06-01

    Full Text Available For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT. In particular, the influence of fracture width (0.10 and 0.25 mm on fracture sealing was investigated. Precipitation occurred mainly at the outermost parts of the fractured surface of the specimen for both fracture widths. While significant sealing was observed for the fracture width of 0.10 mm, sealing was not attained for the fracture width of 0.25 mm within the observation period (49 days. Examination of the sealed regions on the macro-fracture was performed using a three-dimensional image registration technique and applying image subtraction between the CT images of the HSULPC specimen before and after maintaining the specimen in simulated seawater. The temporal change of the sealing deposits for the fracture width of 0.10 mm was much larger than that for the fracture width of 0.25 mm. Therefore, it is concluded that the sealability of the fracture in the HSULPC is affected by the fracture width.

  8. Influence of Fracture Width on Sealability in High-Strength and Ultra-Low-Permeability Concrete in Seawater.

    Fukuda, Daisuke; Nara, Yoshitaka; Hayashi, Daisuke; Ogawa, Hideo; Kaneko, Katsuhiko

    2013-06-25

    For cementitious composites and materials, the sealing of fractures can occur in water by the precipitation of calcium compounds. In this study, the sealing behavior in a macro-fractured high-strength and ultra-low-permeability concrete (HSULPC) specimen was investigated in simulated seawater using micro-focus X-ray computed tomography (CT). In particular, the influence of fracture width (0.10 and 0.25 mm) on fracture sealing was investigated. Precipitation occurred mainly at the outermost parts of the fractured surface of the specimen for both fracture widths. While significant sealing was observed for the fracture width of 0.10 mm, sealing was not attained for the fracture width of 0.25 mm within the observation period (49 days). Examination of the sealed regions on the macro-fracture was performed using a three-dimensional image registration technique and applying image subtraction between the CT images of the HSULPC specimen before and after maintaining the specimen in simulated seawater. The temporal change of the sealing deposits for the fracture width of 0.10 mm was much larger than that for the fracture width of 0.25 mm. Therefore, it is concluded that the sealability of the fracture in the HSULPC is affected by the fracture width.

  9. Evaluation of Low or High Permeability of Fractured Rock using Well Head Losses from Step-Drawdown Tests

    Kim, Byung Woo; Kim, Geon Young; Koh, Yong Kwon; Kim, Hyoung Soo

    2012-01-01

    The equation of the step-drawdown test 's w = BQ+CQ p ' written by Rorabaugh (1953) is suitable for drawdown increased non-linearly in the fractured rocks. It was found that value of root mean square error (RMSE) between observed and calculated drawdowns was very low. The calculated C (well head loss coefficient) and P (well head loss exponent) value of well head losses (CQ p ) ranged 3.689 x 10 -19 - 5.825 x 10 -7 and 3.459 - 8.290, respectively. It appeared that the deeper depth in pumping well the larger drawdowns due to pumping rate increase. The well head loss in the fractured rocks, unlike that in porous media, is affected by properties of fractures (fractures of aperture, spacing, and connection) around pumping well. The C and P value in the well head loss is very important to interpret turbulence interval and properties of high or low permeability of fractured rock. As a result, regression analysis of C and P value in the well head losses identified the relationship of turbulence interval and hydraulic properties. The relationship between C and P value turned out very useful to interpret hydraulic properties of the fractured rocks.

  10. Hybrid green permeable pave with hexagonal modular pavement systems

    Rashid, M A; Abustan, I; Hamzah, M O

    2013-01-01

    Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

  11. Layered bismuth selenide utilized as hole transporting layer for highly stable organic photovoltaics

    Yuan, Zhongcheng

    2015-11-01

    Abstract Layered bismuth selenide (L-Bi2Se3) nanoplates were implemented as hole transporting layers (HTLs) for inverted organic solar cells. Device based on L-Bi2Se3 showed increasing power conversion efficiency (PCE) during ambient condition storage process. A PCE of 4.37% was finally obtained after 5 days storage, which outperformed the ones with evaporated-MoO3 using poly(3-hexylthiophene) (P3HT) as donor material and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor. The improved device efficiency can be attributed to the high conductivity and increasing work function of L-Bi2Se3. The work function of L-Bi2Se3 increased with the storage time in ambient condition due to the oxygen atom doping. Ultraviolet photoelectron spectroscopy and high resolution X-ray photoelectron spectroscopy were conducted to verify the increased work function, which originated from the p-type doping process. The device based on L-Bi2Se3 exhibited excellent stability in ambient condition up to 4 months, which was much improved compared to the device based on traditional HTLs. © 2015 Elsevier B.V.

  12. Identification of mineral dust layers in high alpine snow packs

    Greilinger, Marion; Kau, Daniela; Schauer, Gerhard; Kasper-Giebl, Anne

    2017-04-01

    Deserts serve as a major source for aerosols in the atmosphere with mineral dust as a main contributor to primary aerosol mass. Especially the Sahara, the largest desert in the world, contributes roughly half of the primarily emitted aerosol mass found in the atmosphere [1]. The eroded Saharan dust is episodically transported over thousands of kilometers with synoptic wind patterns towards Europe [2] and reaches Austria about 20 to 30 days per year. Once the Saharan dust is removed from the atmosphere via dry or wet deposition processes, the chemical composition of the precipitation or the affected environment is significantly changed. Saharan dust serves on the one hand as high ionic input leading to an increase of ionic species such as calcium, magnesium or sulfate. On the other hand Saharan dust provides a high alkaline input neutralizing acidic components and causing the pH to increase [3]. Based on these changes in the ion composition, the pH and cross plots of the ion and conductivity balance [4] we tried to develop a method to identify Saharan dust layers in high alpine snow packs. We investigated seasonal snow packs of two high alpine sampling sites situated on the surrounding glaciers of the meteorological Sonnblick observatory serving as a global GAW (Global Atmospheric Watch) station located in the National Park Hohe Tauern in the Austrian Alps. Samples with 10 cm resolution representing the whole winter accumulation period were taken just prior to the start of snow melt at the end of April 2016. In both snow packs two layers with clearly different chemical behavior were observed. In comparison with the aerosol data from the Sonnblick observatory, these layers could be clearly identified as Saharan dust layers. Identified Saharan dust layers in the snow pack allow calculations of the ecological impact of deposited ions, with and without Saharan dust, during snow melt. Furthermore the chemical characteristics for the identification of Saharan dust layers

  13. Case study of elevated layers of high sulfate concentration

    McNaughton, D.J.; Orgill, M.M.

    1979-01-01

    During studies in August 1976 that were part of the Multi-State Atmospheric Power Production Pollutant Study (MAP3S), Alkezweeny et al., (1977) noted that in the Milwaukee urban plume, layers of relatively high sulfate concentrations occurred at high altitudes with respect to the boundary layer. This paper represents a progress report on studies undertaken to investigate possible causes for a bimodel vertical profile of sulfate concentrations. Data presented by Alkezweeny et al., (1977) serve as a basis for this study. Data from August 23, 1976, and August 24, 1978, indicate concentrations relatively high in sulfate, at 1000 and 6000 ft, respectively, with lower concentrations at lower altitudes. Concentrations of trace metals also indicate no peaks in the vertical concentration profiles above the surface. Initial studies of the high, elevated sulfate concentrations have centered on the August 23 measurements taken over southeast Wisconsin using synoptic data from the national weather service, emissions data from the national emissions data bank system (EPA), air quality data from the national air surveillance network (EPA), and satellite photographs from the EROS Data Center

  14. High dose implantations of antimony for buried layer applications

    Gailliard, J.P.; Dupuy, M.; Garcia, M.; Roussin, J.C.

    1978-01-01

    Electrical and physical properties of high dose implantations of antimony in silicon have been studied for use in buried layer applications. The results have been obtained both on and oriented silicon wafers. Following implantations which lead to amorphization we perform an annealing at 600 0 C for 10 mn in order to recrystallize the layer. The observed electrical properties (μ, R) show that the concentration of electrically active antimony ions is greater than that predicted from the solubility of antimony in silicon. Further annealing (in the range 1050 0 - 1200 0 ) induces: firstly a precipitation of the Sb and secondly a diffusion and dissolution of the precipitates. There is a different evolution of the defects in the and silicon slices. T.E.M. reveals no defects in the wafers after one hour annealing at 1200 0 C, whereas defects and twins remain in wafers. Having obtained the evolution of R with time and temperature it is then determined the implantation and annealing conditions which lead to the low resistivity (R = 10) needed for buried layer applications. Results with very many industrially made devices are discussed

  15. Layer-by-Layer-Assembled High-Performance Broadband Antireflection Coatings

    Shimomura, Hiroomi; Gemici, Zekeriyya; Cohen, Robert E.; Rubner, Michael F.

    2010-01-01

    uniformity, thickness control, roughness control, mechanical durability, and incorporation of a diverse set of functional organic molecules into nanoparticle thin films are major challenges. We have used the electrostatic layer-by-layer assembly technique

  16. Quantifying porosity, compressibility and permeability in Shale

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Frykman, Peter

    strain data. We found that Kozeny's modelled permeability fall in the same order of magnitude with measured permeability for shale rich in kaolinite but overestimates permeability by two to three orders of magnitudes for shale with high content of smectite. The empirical Yang and Aplin model gives good...... permeability estimate comparable to the measured one for shale rich in smectite. This is probably because Yang and Aplin model was calibrated in London clay which is rich in smectite....

  17. Layer-by-Layer-Assembled High-Performance Broadband Antireflection Coatings

    Shimomura, Hiroomi

    2010-03-24

    Nanoparticles are indispensable ingredients of solution-processed optical, dielectric, and catalytic thin films. Although solution-based methods are promising low-cost alternatives to vacuum methods, they can have significant limitations. Coating uniformity, thickness control, roughness control, mechanical durability, and incorporation of a diverse set of functional organic molecules into nanoparticle thin films are major challenges. We have used the electrostatic layer-by-layer assembly technique to make uniform, conformal multistack nanoparticle thin films for optical applications with precise thickness control over each stack. Two particularly sought-after optical applications are broadband antireflection and structural color. The effects of interstack and surface roughness on optical properties of these constructs (e.g., haze and spectral response) have been studied quantitatively using a combination of Fourier-transform methods and atomic force microscopy measurements. Deconvoluting root-mean-square roughness into its large-, intermediate-, and small-scale components enables enhanced optical simulations. A 4-stack broadband antireflection coating (<0.5% average reflectance in the visible range, and 0.2% haze) composed of alternating high-index (n ≈ 1.96) and low-index (n ≈ 1.28) stacks has been made on glass substrate. Films calcinated at 550 °C endure a one-hour-long cloth cleaning test under 100 kPa normal stress. © 2010 American Chemical Society.

  18. High-density expression of Ca2+-permeable ASIC1a channels in NG2 glia of rat hippocampus.

    Yen-Chu Lin

    Full Text Available NG2 cells, a fourth type of glial cell in the mammalian CNS, undergo reactive changes in response to a wide variety of brain insults. Recent studies have demonstrated that neuronally expressed acid-sensing ion channels (ASICs are implicated in various neurological disorders including brain ischemia and seizures. Acidosis is a common feature of acute neurological conditions. It is postulated that a drop in pH may be the link between the pathological process and activation of NG2 cells. Such postulate immediately prompts the following questions: Do NG2 cells express ASICs? If so, what are their functional properties and subunit composition? Here, using a combination of electrophysiology, Ca2+ imaging and immunocytochemistry, we present evidence to demonstrate that NG2 cells of the rat hippocampus express high density of Ca2+-permeable ASIC1a channels compared with several types of hippocampal neurons. First, nucleated patch recordings from NG2 cells revealed high density of proton-activated currents. The magnitude of proton-activated current was pH dependent, with a pH for half-maximal activation of 6.3. Second, the current-voltage relationship showed a reversal close to the equilibrium potential for Na+. Third, psalmotoxin 1, a blocker specific for the ASIC1a channel, largely inhibited proton-activated currents. Fourth, Ca2+ imaging showed that activation of proton-activated channels led to an increase of [Ca2+]i. Finally, immunocytochemistry showed co-localization of ASIC1a and NG2 proteins in the hippocampus. Thus the acid chemosensor, the ASIC1a channel, may serve for inducing membrane depolarization and Ca2+ influx, thereby playing a crucial role in the NG2 cell response to injury following ischemia.

  19. Structure of highly perfect semiconductor strained-layer superlattices

    Vandenberg, J.M.

    1989-01-01

    High-resolution x-ray diffraction (HRXRD) measurements of strained-layer superlattices (SLS's) have been carried out using a four-crystal monochromator. A wide asymmetric range of sharp higher-order x-ray satellite peaks is observed indicating well-defined periodic structures. Using a kinematical diffraction step model very good agreement between measured and simulated x-ray satellite patterns could be achieved. These results show that this x- ray method is a powerful tool to evaluate the crystal quality of SLS's

  20. Maintenance measures for preservation and recovery of permeable pavement surface infiltration rate--The effects of street sweeping, vacuum cleaning, high pressure washing, and milling.

    Winston, Ryan J; Al-Rubaei, Ahmed M; Blecken, Godecke T; Viklander, Maria; Hunt, William F

    2016-03-15

    The surface infiltration rates (SIR) of permeable pavements decline with time as sediment and debris clog pore spaces. Effective maintenance techniques are needed to ensure the hydraulic functionality and water quality benefits of this stormwater control. Eight different small-scale and full-scale maintenance techniques aimed at recovering pavement permeability were evaluated at ten different permeable pavement sites in the USA and Sweden. Maintenance techniques included manual removal of the upper 2 cm of fill material, mechanical street sweeping, regenerative-air street sweeping, vacuum street sweeping, hand-held vacuuming, high pressure washing, and milling of porous asphalt. The removal of the upper 2 cm of clogging material did not significantly improve the SIR of concrete grid paves (CGP) and permeable interlocking concrete pavers (PICP) due to the inclusion of fines in the joint and bedding stone during construction, suggesting routine maintenance cannot overcome improper construction. For porous asphalt maintenance, industrial hand-held vacuum cleaning, pressure washing, and milling were increasingly successful at recovering the SIR. Milling to a depth of 2.5 cm nearly restored the SIR for a 21-year old porous asphalt pavement to like-new conditions. For PICP, street sweepers employing suction were shown to be preferable to mechanical sweepers; additionally, maintenance efforts may become more intensive over time to maintain a threshold SIR, as maintenance was not 100% effective at removing clogging material. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. The effects of high-Dk rigid contact lens center thickness, material permeability, and blinking on the oxygen uptake of the human cornea.

    Gardner, Hope Patterson; Fink, Barbara A; Mitchell, Lynn G; Hill, Richard M

    2005-06-01

    The human corneal oxygen uptake responses associated with the static (nonblinking) and dynamic (blinking) wear of five rigid gas-permeable materials with high oxygen permeabilities were determined for three different center thicknesses and compared with the responses for the normal open eye and severe hypoxic stress (static wear of polymethylmethacrylate). Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode during two sessions with each of 10 human subjects. Measurements were made on the right eye for the normal open eye (air) and after 5 minutes of static and dynamic wear of polymethylmethacrylate and five rigid gas-permeable contact lens materials: Fluoroperm 92 (paflufocon A, Dk = 92), Fluoroperm 151 (paflufocon D, Dk = 151), 1992 Menicon SF-P (melafocon A, Dk = 102), 1995 Menicon SF-P (melafocon A, Dk = 159), and Menicon Z (tisilfocon A, Dk = 163-250). Lenses were manufactured in three different center thicknesses (0.12, 0.16, and 0.20 mm), with all other parameters remaining constant. Repeated-measures analysis of variance was used and included lens material (five levels), blinking condition (two levels), and lens thickness (three levels) as within-subject effects. Significant differences were found in corneal oxygen responses to lens material (p Dk rigid lens materials studied here, moderate changes in lens thickness or material permeability may result in modest differences in corneal hypoxic relief, whereas blinking results in no significant improvement to corneal oxygenation.

  2. Prebiotic milk oligosaccharides prevent development of obese phenotype, impairment of gut permeability, and microbial dysbiosis in high fat-fed mice.

    Hamilton, M Kristina; Ronveaux, Charlotte C; Rust, Bret M; Newman, John W; Hawley, Melissa; Barile, Daniela; Mills, David A; Raybould, Helen E

    2017-05-01

    Microbial dysbiosis and increased intestinal permeability are targets for prevention or reversal of weight gain in high-fat (HF) diet-induced obesity (DIO). Prebiotic milk oligosaccharides (MO) have been shown to benefit the host intestine but have not been used in DIO. We hypothesized that supplementation with bovine MO would prevent the deleterious effect of HF diet on the gut microbiota and intestinal permeability and attenuate development of the obese phenotype. C57BL/6 mice were fed a control diet, HF (40% fat/kcal), or HF + prebiotic [6%/kg bovine milk oligosaccharides (BMO) or inulin] for 1, 3, or 6 wk. Gut microbiota and intestinal permeability were assessed in the ileum, cecum, and colon. Addition of BMO to the HF diet significantly attenuated weight gain, decreased adiposity, and decreased caloric intake; inulin supplementation also lowered weight gain and adiposity, but this did not reach significance. BMO and inulin completely abolished the HF diet-induced increase in paracellular and transcellular permeability in the small and large intestine. Both BMO and inulin increased abundance of beneficial microbes Bifidobacterium and Lactobacillus in the ileum. However, inulin supplementation altered phylogenetic diversity and decreased species richness. We conclude that addition of BMO to the HF diet completely prevented increases in intestinal permeability and microbial dysbiosis and was partially effective to prevent weight gain in DIO. NEW & NOTEWORTHY This study provides the first report of the effects of prebiotic bovine milk oligosaccharides on the host phenotype of high-fat diet-induced obesity in mice. Copyright © 2017 the American Physiological Society.

  3. Effect of permeability enhancers on paracellular permeability of acyclovir.

    Ates, Muge; Kaynak, Mustafa Sinan; Sahin, Selma

    2016-06-01

    According to Biopharmaceutics Classification System (BCS), acyclovir is a class III (high solubility, low permeability) compound, and it is transported through paracellular route by passive diffusion. The aim of this study was to investigate the effect of various pharmaceutical excipients on the intestinal permeability of acyclovir. The single-pass in-situ intestinal perfusion (SPIP) method was used to estimate the permeability values of acyclovir and metoprolol across different intestinal segments (jejunum, ileum and colon). Permeability coefficient (Peff ) of acyclovir was determined in the absence and presence of a permeation enhancer such as dimethyl β-cyclodextrin (DM-β-CD), sodium lauryl sulfate (SLS), sodium caprate (Cap-Na) and chitosan chloride. All enhancers increased the permeability of paracellularly transported acyclovir. Although Cap-Na has the highest permeability-enhancing effect in all segments, permeation-enhancing effect of chitosan and SLS was only significant in ileum. On the other hand, DM-β-CD slightly decreased the permeability in all intestinal segments. These findings have potential implication concerning the enhancement of absorption of paracellularly transported compounds with limited oral bioavailability. In the case of acyclovir, Cap-Na either alone or in combination with SLS or chitosan has the potential to improve its absorption and bioavailability and has yet to be explored. © 2016 Royal Pharmaceutical Society.

  4. High stability of few layer graphene nanoplatelets in various solvents

    Xu, X; Zhou, Jian; Lubineau, Gilles

    2017-01-01

    Dispersion of few-layer graphene nanoplatelets (GNPs) in liquid media is a crucial step for various applications. Here, we highlight a simple, nondestructive method for preparing stable aqueous colloidal solutions with GNP powder quickly dispersed in 5 wt.% sodium–hypochlorite- (NaClO) and sodium-bromide- (NaBr) salted solvent by bath sonication. This method makes it possible to easily prepare a highly concentrated colloidal solution (1 mgcenterdotml−1) of GNPs that can easily be re-dispersed in water (treated GNPs). The aqueous suspension we prepared remained stable for longer than a few weeks. We made similar tests with various solvents and dispersibility appeared to decrease with decreasing polarity. High-concentration suspensions using our facile dispersion method could be of particular interest to the large community using graphene for a diversity of applications.

  5. High stability of few layer graphene nanoplatelets in various solvents

    Xu, X

    2017-04-25

    Dispersion of few-layer graphene nanoplatelets (GNPs) in liquid media is a crucial step for various applications. Here, we highlight a simple, nondestructive method for preparing stable aqueous colloidal solutions with GNP powder quickly dispersed in 5 wt.% sodium–hypochlorite- (NaClO) and sodium-bromide- (NaBr) salted solvent by bath sonication. This method makes it possible to easily prepare a highly concentrated colloidal solution (1 mgcenterdotml−1) of GNPs that can easily be re-dispersed in water (treated GNPs). The aqueous suspension we prepared remained stable for longer than a few weeks. We made similar tests with various solvents and dispersibility appeared to decrease with decreasing polarity. High-concentration suspensions using our facile dispersion method could be of particular interest to the large community using graphene for a diversity of applications.

  6. Mapping of 222Rn and 4He in soil gas over a karstic limestone-granite boundary: correlation of high indoor 222Rn with zones of enhanced permeability

    O'Connor, P.J.; Gallagher, V.; Van den Boom, G.

    1992-01-01

    Recent indoor radon reconnaissance surveys in Ireland have identified buildings with high radon concentrations (up to 1700 Bq.m -3 ) overlying Carboniferous karstic limestone sequences in the western part of the country. A detailed investigation of indoor 222 Rn and soil gas 222 Rn and 4 He concentrations has been carried out over a karstic limestone-uraniferous granite boundary in County Galway. High indoor 222 Rn concentrations occur in dwellings over both lithologies. Radon migratory routes in bedrock and overburden appear to be controlled by zones of enhanced permeability, e.g. fractures, faults, etc. which are defined by linear arrays of elevated 4 He soil gas values. While the ultimate source of radon remains conjectural, the greatly enhanced permeability of karstified limestone is thought to be of fundamental importance in providing a means of rapid radon transport into overlying soils and buildings. (author)

  7. Permeability Increase with Deep Borehole Controlled Pre-cracking Blasting Technology in Low Permeability and High Gassy Seam"%低透气性高瓦斯煤层深孔控制预裂爆破增透技术

    弓美疆; 池鹏; 张明杰

    2012-01-01

    为了解决低透气性高瓦斯煤层难抽采问题,运用RFPA2D数值模拟软件,建立了2种深孔控制预裂爆破力学模型,通过对模拟结果进行对比分析,得出一套适用于鹤煤八矿底板抽采的爆破参数,并进行了现场试验,爆破后煤层透气性系数平均值达到了2.23 m2/(MPa2.d),比爆破前测定的煤层原始透气性平均值提高了近3.05倍,说明该技术可以明显提高钻孔周围煤体裂隙发育程度,煤体透气性增加,达到了提高煤层瓦斯抽采量和抽采率的目的。%In order to solve the difficult gas drainage problem in low permeability and high gassy seam, the RFPA2D numerical simulation software was applied to establish two deep borehole controlled pre-cracking blasting mechanics models. With the comparison and analysis on the simulation results, a set of blasting parameters obtained which were suitable for floor gas drainage in No. 8 mine of Hegang Coal Mining and the site trial with the parameters was conducted. The results showed that after the blasting, the average value of the seam per- meability coefficient reached at 2. 23 m2/ ( MPa2 ·d) and 3.05 times higher than the average value of the seam in-situ permeability be- fore the blasting conducted. Thus the technology could obviously improve the cracking development degree of coal around the borehole and could improve the permeability of the seam. The target to improve the seam gas drainage value and the gas drainage rate could be reached.

  8. High performance thin layer chromatography profile of Cassytha filiformis

    Mythili Sathiavelu; Sathiavelu Arunachalam

    2012-01-01

    Objective: To study the phenols, flavonoids, saponin profile of the medicinal plant Cassytha filiformis (C. filiformis) using high performance thin layer chromatography (HPTLC). Methods:The extracts were tested to determine the presence of various phytochmeicals like alkaloids, phenolic compounds, flavonoids, carbohydrates, glycosides, saponins, terpenoids, tannins, fixed oils, fats and protein and aminoacids (Harborne and Harborne, 1998). HPTLC studies were carried out by Harborne and Wagner et al method. Different compositions of the mobile phase for HPTLC analysis were tested in order to obtain high resolution and reproducible peaks. Results: The results of the preliminary phytochemical studies confirm the presence of phenols, alkaloids, carbohydrates, saponins, flavanoids, terpenoids and tannins in the methanolic extracts of C. filiformis. The methanolic extracts of C. filiformis displayed the presence of 13 types of phenolic substances with 13 different Rf values ranging from 0.01 to 0.96. The results illustrated the presence of 9 different types of flavonoides with 9 different Rf values ranging from 0.01 to 0.97. The results of HPTLC analysis of saponins demonstrated the presence of 11 different types of saponins with 11 different Rf values ranging from 0.04 to 0.92. Conclusions: In the present study we observed the phenols, flavonoids, saponin profile of the medicinal plant C. filiformis using high performance thin layer chromatography (HPTLC). Hence it was concluded that the phenolic compounds present in the methonolic extract could be responsible for antioxidant activities. Plant derived antioxidants, especially phenols and flavonoids, have been described to have various properties like anticancer, antiaging and prevention of cardiovascular diseases. Furthur, separation and characterization of the bioactive compound from the plant is to be evaluated and reported in near future.

  9. Layered plasma polymer composite membranes

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  10. Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices

    Pavel, Alexandru Cezar

    The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that

  11. High-performance polymer/layered silicate nanocomposites

    Heidecker, Matthew J.

    High-performance layered-silicate nanocomposites of Polycarbonate (PC), poly(ethylene terephthalate) (PET), and their blends were produced via conventional melt-blending techniques. The focus of this thesis was on the fundamentals of dispersion, control of thermal stability, maintenance of melt-blending processing conditions, and on optimization of the composites' mechanical properties via the design of controlled and thermodynamically favorable nano-filler dispersions within the polymer matrices. PET and PC require high temperatures for melt-processing, rendering impractical the use of conventional/commercial organically-modified layered-silicates, since the thermal degradation temperatures of their ammonium surfactants lies below the typical processing temperatures. Thus, different surfactant chemistries must be employed in order to develop melt-processable nanocomposites, also accounting for polymer matrix degradation due to water (PET) or amine compounds (PC). Novel high thermal-stability surfactants were developed and employed in montmorillonite nanocomposites of PET, PC, and PC/PET blends, and were compared to the respective nanocomposites based on conventional quaternary-ammonium modified montmorillonites. Favorable dispersion was achieved in all cases, however, the overall material behavior -- i.e., the combination of crystallization, mechanical properties, and thermal degradation -- was better for the nanocomposites based on the thermally-stable surfactant fillers. Studies were also done to trace, and ultimately limit, the matrix degradation of Polycarbonate/montmorillonite nanocomposites, through varying the montmorillonite surfactant chemistry, processing conditions, and processing additives. Molecular weight degradation was, maybe surprisingly, better controlled in the conventional quaternary ammonium based nanocomposites -- even though the thermal stability of the organically modified montmorillonites was in most cases the lowest. Dependence of the

  12. High Gain and High Directive of Antenna Arrays Utilizing Dielectric Layer on Bismuth Titanate Ceramics

    F. H. Wee

    2012-01-01

    Full Text Available A high gain and high directive microstrip patch array antenna formed from dielectric layer stacked on bismuth titanate (BiT ceramics have been investigated, fabricated, and measured. The antennas are designed and constructed with a combination of two-, four-, and six-BiT elements in an array form application on microwave substrate. For gain and directivity enhancement, a layer of dielectric was stacked on the BiT antenna array. We measured the gain and directivity of BiT array antennas with and without the dielectric layer and found that the gain of BiT array antenna with the dielectric layer was enhanced by about 1.4 dBi of directivity and 1.3 dB of gain over the one without the dielectric layer at 2.3 GHz. The impedance bandwidth of the BiT array antenna both with and without the dielectric layer is about 500 MHz and 350 MHz, respectively, which is suitable for the application of the WiMAX 2.3 GHz system. The utilization of BiT ceramics that covers about 90% of antenna led to high radiation efficiency, and small-size antennas were produced. In order to validate the proposed design, theoretical and measured results are provided and discussed.

  13. Surface-subsurface turbulent interaction at the interface of a permeable bed: influence of the wall permeability

    Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

    2017-12-01

    Coarse-gravel river beds possess a high degree of permeability. Flow interactions between surface and subsurface flow across the bed interface is key to a number of natural processes occurring in the hyporheic zone. In fact, it is increasingly recognized that these interactions drive mass, momentum and energy transport across the interface, and consequently control biochemical processes as well as stability of sediments. The current study explores the role of the wall permeability in surface and subsurface flow interaction under controlled experimental conditions on a physical model of a gravel bed. The present wall model was constructed by five layers of cubically arranged spheres (d=25.4mm, where d is a diameter) providing 48% of porosity. Surface topography was removed by cutting half of a diameter on the top layer of spheres to render the flow surface smooth and highlight the impact of the permeability on the overlying flow. An impermeable smooth wall was also considered as a baseline of comparison for the permeable wall flow. To obtain basic flow statistics, low-frame-rate high-resolution PIV measurements were performed first in the streamwise-wall-normal (x-y) plane and refractive-index matching was employed to optically access the flow within the permeable wall. Time-resolved PIV experiments in the same facility were followed to investigate the flow interaction across the wall interface in sptaio-temporal domain. In this paper, a detailed analysis of the first and second order velocity statistics as well as the amplitude modulation for the flow overlying the permeable smooth wall will be presented.

  14. Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice.

    Neelakantan, Harshini; Vance, Virginia; Wetzel, Michael D; Wang, Hua-Yu Leo; McHardy, Stanton F; Finnerty, Celeste C; Hommel, Jonathan D; Watowich, Stanley J

    2018-01-01

    There is a critical need for new mechanism-of-action drugs that reduce the burden of obesity and associated chronic metabolic comorbidities. A potentially novel target to treat obesity and type 2 diabetes is nicotinamide-N-methyltransferase (NNMT), a cytosolic enzyme with newly identified roles in cellular metabolism and energy homeostasis. To validate NNMT as an anti-obesity drug target, we investigated the permeability, selectivity, mechanistic, and physiological properties of a series of small molecule NNMT inhibitors. Membrane permeability of NNMT inhibitors was characterized using parallel artificial membrane permeability and Caco-2 cell assays. Selectivity was tested against structurally-related methyltransferases and nicotinamide adenine dinucleotide (NAD + ) salvage pathway enzymes. Effects of NNMT inhibitors on lipogenesis and intracellular levels of metabolites, including NNMT reaction product 1-methylnicotianamide (1-MNA) were evaluated in cultured adipocytes. Effects of a potent NNMT inhibitor on obesity measures and plasma lipid were assessed in diet-induced obese mice fed a high-fat diet. Methylquinolinium scaffolds with primary amine substitutions displayed high permeability from passive and active transport across membranes. Importantly, methylquinolinium analogues displayed high selectivity, not inhibiting related SAM-dependent methyltransferases or enzymes in the NAD + salvage pathway. NNMT inhibitors reduced intracellular 1-MNA, increased intracellular NAD + and S-(5'-adenosyl)-l-methionine (SAM), and suppressed lipogenesis in adipocytes. Treatment of diet-induced obese mice systemically with a potent NNMT inhibitor significantly reduced body weight and white adipose mass, decreased adipocyte size, and lowered plasma total cholesterol levels. Notably, administration of NNMT inhibitors did not impact total food intake nor produce any observable adverse effects. These results support development of small molecule NNMT inhibitors as therapeutics to

  15. Efficient dual layer interconnect coating for high temperature electrochemical devices

    Palcut, Marián; Mikkelsen, Lars; Neufeld, Kai

    2012-01-01

    Effects of novel dual layer coatings Co3O4/La0.85Sr0.15MnO3−δ on high temperature oxidation behaviour of candidate steels for interconnects are studied at 1123 K in flowing simulated ambient air (air + 1% H2O) and oxygen. Four alloys are investigated: Crofer 22 APU, Crofer 22 H, E-Brite and AL 29...... that the oxidation reaction is limited by outward Cr3+ diffusion in the chromia scale. The coating effectively reduces the oxidation rate. Reactions and cation inter-diffusion between the coating and the oxide scale are observed. Long term effects of these interactions are discussed and practical implications...

  16. Developments in permeable and low permeability barriers

    Jefferis, S.A.; Norris, G.H.; Thomas, A.O.

    1997-01-01

    The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber

  17. Thermal-permeability structure and recharge conditions of the Mutnovsky high-temperature geothermal field (Kamchatka, Russia)

    Kiryukhin, A. V.; Polyakov, A. Y.; Usacheva, O. O.; Kiryukhin, P. A.

    2018-05-01

    The Mutnovsky geothermal area is part of the Eastern Kamchatka active volcano belt. Mutnovsky, 80 kY old and an aging strato-volcano (a complex of 4 composite volcanic cones), acts as a magma- and water-injector into the 25-km-long North Mutnovsky extension zone. Magmatic injection events (dykes) are associated with plane-oriented MEQ (Micro Earth Quakes) clusters, most of them occurring in the NE sector of the volcano (2 × 10 km2) at elevations from -4 to -2 km, while some magmatic injections occur at elevations from -6.0 to -4.0 km below the Mutnovsky production field. Water recharge of production reservoirs is from the Mutnovsky volcano crater glacier (+1500 to +1800 masl), which was confirmed by water isotopic data (δD, δ18O) of production wells at an earlier stage of development. The Mutnovsky (Dachny) 260-310 °C high-temperature production geothermal reservoir with a volume of 16 km3 is at the junction of NNE- and NE-striking normal faults, which coincides with the current dominant dyke injection orientation. TOUGH2-modeling estimates of the reservoir properties are as follows: the reservoir permeability is 90-600 e-15 m2, the deep upflow recharge is 80 kg/s and the enthalpy is 1420 kJ/kg. Modeling was used to reproduce the history of the Mutnovsky (Dachny) reservoir exploitation since 1983 with an effective power of 48 MWe by 2016. Modeling also showed that the reservoir is capable of yielding 65-83 MWe of sustainable production until 2055, if additional production drilling in the SE part of the field is performed. Moreover, this power value may increase to 87-105 MWe if binary technologies are applied. Modeling also shows that the predicted power is sensitive to local meteoric water influx during development. Conceptual iTOUGH2-EOS1sc thermal hydrodynamic modeling of the Mutnovsky magma-hydrothermal system as a whole reasonably explains its evolution over the last 1500-5000 years in terms of heat recharge (dyke injection from the Mutnovsky-4 funnel) and

  18. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    2008-01-01

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

  19. Exceptionally High Electric Double Layer Capacitances of Oligomeric Ionic Liquids.

    Matsumoto, Michio; Shimizu, Sunao; Sotoike, Rina; Watanabe, Masayoshi; Iwasa, Yoshihiro; Itoh, Yoshimitsu; Aida, Takuzo

    2017-11-15

    Electric double layer (EDL) capacitors are promising as next-generation energy accumulators if their capacitances and operation voltages are both high. However, only few electrolytes can simultaneously fulfill these two requisites. Here we report that an oligomeric ionic liquid such as IL4 TFSI with four imidazolium ion units in its structure provides a wide electrochemical window of ∼5.0 V, similar to monomeric ionic liquids. Furthermore, electrochemical impedance measurements using Au working electrodes demonstrated that IL4 TFSI exhibits an exceptionally high EDL capacitance of ∼66 μF/cm 2 , which is ∼6 times as high as those of monomeric ionic liquids so far reported. We also found that an EDL-based field effect transistor (FET) using IL4 TFSI as a gate dielectric material and SrTiO 3 as a channel material displays a very sharp transfer curve with an enhanced carrier accumulation capability of ∼64 μF/cm 2 , as determined by Hall-effect measurements.

  20. Problems of increasing of thermostability of highly permeable Ni-Zn ferrites and relative materials for telecommunications

    Gonchar, A. E-mail: letyuk@mail.ru; Andreev, V.; Letyuk, L.; Shishkanov, A.; Maiorov, V

    2003-01-01

    The work considers ways of increasing of thermostability of ferrites of the basic systems NiO-ZnO-Fe{sub 2}O{sub 3} and MgO-ZnO-Fe{sub 2}O{sub 3} and relative materials for telecommunication. Sufficient results in increasing of the thermostability were achieved by doping Cu ions and controlling rejection of Fe{sub 2}O{sub 3} content from equimolar composition. These results allow to increase the Curie temperature to 130-140 deg. C for Ni-Zn ferrites with initial permeability 2000.

  1. High-permeance crosslinked PTMSP thin-film composite membranes as supports for CO2 selective layer formation

    Stepan D. Bazhenov

    2016-10-01

    Full Text Available In the development of the composite gas separation membranes for post-combustion CO2 capture, little attention is focused on the optimization of the membrane supports, which satisfy the conditions of this technology. The primary requirements to the membrane supports are concerned with their high CO2 permeance. In this work, the membrane supports with desired characteristics were developed as high-permeance gas separation thin film composite (TFC membranes with the thin defect-free layer from the crosslinked highly permeable polymer, poly[1-(trimethylsilyl-1-propyne] (PTMSP. This layer is insoluble in chloroform and can be used as a gutter layer for the further deposition of the СО2-selective materials from the organic solvents. Crosslinking of PTMSP was performed using polyethyleneimine (PEI and poly (ethyleneglycol diglycidyl ether (PEGDGE as crosslinking agents. Optimal concentrations of PEI in PTMSP and PEGDGE in methanol were selected in order to diminish the undesirable effect on the final membrane gas transport characteristics. The conditions of the kiss-coating technique for the deposition of the thin defect-free PTMSP-based layer, namely, composition of the casting solution and the speed of movement of the porous commercial microfiltration-grade support, were optimized. The procedure of post-treatment with alcohols and alcohol solutions was shown to be crucial for the improvement of gas permeance of the membranes with the crosslinked PTMSP layer having thickness ranging within 1–2.5 μm. The claimed membranes showed the following characteristics: CO2 permeance is equal to 50–54 m3(STP/(m2 h bar (18,500–20,000 GPU, ideal CO2/N2 selectivity is 3.6–3.7, and their selective layers are insoluble in chloroform. Thus, the developed high-permeance TFC membranes are considered as a promising supports for further modification by enhanced CO2 selective layer formation. Keywords: Thin-film composite membrane

  2. Highly permeable double-skinned forward osmosis membranes for anti-fouling in the emulsified oil-water separation process

    Duong, Hoang Hanh Phuoc; Chung, Neal Tai-Shung; Wei, Shawn; Irish, Lana

    2014-01-01

    Forward osmosis (FO) has attracted wide attention in recent years. However, the FO performance may be restricted due to internal concentration polarization (ICP) and fast fouling propensity that occurs in the membrane sublayer. Particularly, these problems significantly affect the membrane performance when treating highly contaminated oily wastewater. Recently, double-skinned flat sheet cellulose acetate (CA) membranes consisting of two selective skins via the phase inversion method have demonstrated less ICP and fouling propensity over typical single-skinned membranes. However, these membranes exhibit low water fluxes of <12 LMH under 2 M NaCl draw solution. Therefore, a novel double-skinned FO membrane with a high water flux has been aimed for in this study for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between (i) a truly dense skin for salt rejection and (ii) a fairly loose dense skin for emulsified oil particle rejection. The former dense skin is a polyamide synthesized via interfacial polymerization, while the latter one is a self-assembled sulfonated pentablock copolymer (Nexar copolymer) layer. The resultant double-skinned membrane exhibits a high water flux of 17.2 LMH and a low reverse salt transport of 4.85 gMH using 0.5 M NaCl as the draw solution and DI water as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation. © 2014 American Chemical Society.

  3. Highly permeable double-skinned forward osmosis membranes for anti-fouling in the emulsified oil-water separation process

    Duong, Hoang Hanh Phuoc

    2014-04-15

    Forward osmosis (FO) has attracted wide attention in recent years. However, the FO performance may be restricted due to internal concentration polarization (ICP) and fast fouling propensity that occurs in the membrane sublayer. Particularly, these problems significantly affect the membrane performance when treating highly contaminated oily wastewater. Recently, double-skinned flat sheet cellulose acetate (CA) membranes consisting of two selective skins via the phase inversion method have demonstrated less ICP and fouling propensity over typical single-skinned membranes. However, these membranes exhibit low water fluxes of <12 LMH under 2 M NaCl draw solution. Therefore, a novel double-skinned FO membrane with a high water flux has been aimed for in this study for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between (i) a truly dense skin for salt rejection and (ii) a fairly loose dense skin for emulsified oil particle rejection. The former dense skin is a polyamide synthesized via interfacial polymerization, while the latter one is a self-assembled sulfonated pentablock copolymer (Nexar copolymer) layer. The resultant double-skinned membrane exhibits a high water flux of 17.2 LMH and a low reverse salt transport of 4.85 gMH using 0.5 M NaCl as the draw solution and DI water as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation. © 2014 American Chemical Society.

  4. High ion temperatures from buried layers irradiated with Vulcan Petawatt

    Karsch, S.; Schreiber, J.; Willingale, L.; Lancaster, K.; Habara, H.; Nilson, P.; Gopal, A.; Wei, M. S.; Stoeckl, C.; Evans, R.; Clarke, R.; Heathcote, R.; Najmudin, Z.; Krushelnick, K.; Neely, D.; Norreys, P. A.

    2005-01-01

    Deuteron acceleration from CH/CD/CH layer targets irradiated with PW laser pulses has been studied using. Thomson parabola spectrometers and neutron TOF spectroscopy. The measured ion and neutron spectra reveal significant MeV deuteron acceleration from the deeply buried CD layer, which scales with the thickness of the overlying CH layer. While the neutron spectra reveal the scaling of the thermal heating with target thickness, the ion spectra indicate the presence of an efficient nonthermal acceleration mechanism inside. the bulk. Possible explanations will be discussed. (Author)

  5. Tunable permittivity and permeability of low loss Z + Y-type ferrite composites for ultra-high frequency applications

    Su, Zhijuan; Hu, Bolin; Chen, Yajie, E-mail: y.chen@neu.edu; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Li, Qifan; Feng, Zekun [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, Xian [Center for Microwave Magnetic Materials and Integrated Circuits, and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-05-07

    A series of Z-type and Y-type ferrite composites with various phase fractions were studied for their RF properties including the measurement of permittivity to permeability spectra over a frequency range of 0.1–10 GHz. Phase identification of the ferrite composites' constituents was determined by X-ray diffraction. An effective medium approximation was used to predict the magnetic and dielectric behavior of the composites. The experiments indicated that the composite having 75 vol. % of Z-type ferrite demonstrated a permeability of ∼12 with a nearly equivalent permittivity, yielding a ratio (μ′/ε′) of 0.91 at a frequency range from 0.55 to 0.75 GHz. The dielectric loss (i.e., tan δ{sub ε}) and magnetic loss (i.e., tan δ{sub μ}) were measured to be lower than 0.08 at f = 0.1–1 GHz and 0.29 at f = 0.1–0.7 GHz, respectively. Furthermore, the loss factors, as tan δ{sub ε}/ε′ and tan δ{sub μ}/μ′, were calculated to be 0.003 and 0.02 at 0.65 GHz, respectively.

  6. Turbulent boundary layer in high Rayleigh number convection in air.

    du Puits, Ronald; Li, Ling; Resagk, Christian; Thess, André; Willert, Christian

    2014-03-28

    Flow visualizations and particle image velocimetry measurements in the boundary layer of a Rayleigh-Bénard experiment are presented for the Rayleigh number Ra=1.4×1010. Our visualizations indicate that the appearance of the flow structures is similar to ordinary (isothermal) turbulent boundary layers. Our particle image velocimetry measurements show that vorticity with both positive and negative sign is generated and that the smallest flow structures are 1 order of magnitude smaller than the boundary layer thickness. Additional local measurements using laser Doppler velocimetry yield turbulence intensities up to I=0.4 as in turbulent atmospheric boundary layers. From our observations, we conclude that the convective boundary layer becomes turbulent locally and temporarily although its Reynolds number Re≈200 is considerably smaller than the value 420 underlying existing phenomenological theories. We think that, in turbulent Rayleigh-Bénard convection, the transition of the boundary layer towards turbulence depends on subtle details of the flow field and is therefore not universal.

  7. Different Methods of Predicting Permeability in Shale

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Krogsbøll, Anette

    by two to five orders of magnitudes at lower vertical effective stress below 40 MPa as the content of clay minerals increases causing heterogeneity in shale material. Indirect permeability from consolidation can give maximum and minimum values of shale permeability needed in simulating fluid flow......Permeability is often very difficult to measure or predict in shale lithology. In this work we are determining shale permeability from consolidation tests data using Wissa et al., (1971) approach and comparing the results with predicted permeability from Kozeny’s model. Core and cuttings materials...... effective stress to 9 μD at high vertical effective stress of 100 MPa. The indirect permeability calculated from consolidation tests falls in the same magnitude at higher vertical effective stress, above 40 MPa, as that of the Kozeny model for shale samples with high non-clay content ≥ 70% but are higher...

  8. Film Permeability Determination Using Static Permeability Cells

    The permeability of tarps to soil fumigant pesticides varies depending on the active ingredient chemical: dimethyl disulfide (DMDS), methyl bromide, chloropicrin, or other. The diffusion rate can be represented by the mass transfer coefficient (MTC).

  9. Development and characterization of high refractive index and high scattering acrylate polymer layers

    Eiselt, Thomas; Gomard, Guillaume; Preinfalk, Jan; Gleißner, Uwe; Lemmer, Uli; Hanemann, Thomas

    2016-11-01

    In this work, we develop a wet-processable scattering layer exhibiting a high refractive index that can be used in organic light-emitting diodes for light outcoupling purposes. The composite layers contain an acrylate casting resin, benzylmethacrylate, and phenanthrene, which is employed to increase the refractive index. The mixtures are first rheologically characterized and then polymerized with heat and UV radiation. For the refractive index measurements, the polymerized samples require a planar surface without air bubbles. To produce flat samples, a special construction consisting of a glass plate, a teflon sheet, a silicone ring (PDMS mold), another teflon sheet, and another glass plate is developed. Glue clamps are used to hold the construction together. The refractive index of the samples can be increased from 1.565 to 1.585 at 20°C at a wavelength of 589 nm following the addition of 20 wt% phenanthrene. A master mixture with a high refractive index is taken for further experiments. Nanoscaled titanium dioxide is added and dispersed into the master mixture and then spin coated on a glass substrate. These layers are optically characterized. Most of the presented layers present the expected haze of over 50%.

  10. The effect of high energy electron irradiation on blood-brain barrier permeability to haloperidol and stobadin in rats

    Trnovec, T; Kallay, Z [Komenskeho Univ., Bratislava (Czechoslovakia). Inst. of Preventive and Clinical Medicine; Volenec, K [Karlova Univ., Hradec Kralove (Czechoslovakia). Lekarska Fakulta; Bezek, S; Durisova, M; Scasnar, V; Kubu, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia). Ustav Experimentalnej Farmakologie; Svoboda, V [Medical Academy J.E. Purkyne, Hradec Kralove (Czechoslovakia)

    1991-10-01

    The heads of rats were irradiated by 4 MeV electrons in doses 90, 180, and 360 Gy. The observed times of deaths ranged 120-600, 60-420, and 150-370 min after 90, 180, and 360 Gy, respectively. A dose dependent decrease of the brain uptake index of haloperidol was observed 1 and 3 h post radiation. On the other hand an increased brain uptake index was found for stobadin after head irradiation with doses of 180 and 360 Gy. Regional cerebral blood flow, blood pressure, and heart rate were not significantly altered in the period following irradiation with 180 Gy. The observed changes in blood-brain barrier (BBB) permeability seem to be the result of the damaged function of morphological structures forming the BBB rather than altered regional blood flow. (orig.).

  11. Bentonite Permeability at Elevated Temperature

    Katherine A. Daniels

    2017-01-01

    Full Text Available Repository designs frequently favour geological disposal of radioactive waste with a backfill material occupying void space around the waste. The backfill material must tolerate the high temperatures produced by decaying radioactive waste to prevent its failure or degradation, leading to increased hydraulic conductivity and reduced sealing performance. The results of four experiments investigating the effect of temperature on the permeability of a bentonite backfill are presented. Bentonite is a clay commonly proposed as the backfill in repository designs because of its high swelling capacity and very low permeability. The experiments were conducted in two sets of purpose-built, temperature controlled apparatus, designed to simulate isotropic pressure and constant volume conditions within the testing range of 4–6 MPa average effective stress. The response of bentonite during thermal loading at temperatures up to 200 °C was investigated, extending the previously considered temperature range. The results provide details of bentonite’s intrinsic permeability, total stress, swelling pressure and porewater pressure during thermal cycles. We find that bentonite’s hydraulic properties are sensitive to thermal loading and the type of imposed boundary condition. However, the permeability change is not large and can mostly be accounted for by water viscosity changes. Thus, under 150 °C, temperature has a minimal impact on bentonite’s hydraulic permeability.

  12. Focal Low and Global High Permeability Predict the Possibility, Risk, and Location of Hemorrhagic Transformation following Intra-Arterial Thrombolysis Therapy in Acute Stroke.

    Li, Y; Xia, Y; Chen, H; Liu, N; Jackson, A; Wintermark, M; Zhang, Y; Hu, J; Wu, B; Zhang, W; Tu, J; Su, Z; Zhu, G

    2017-09-01

    The contrast volume transfer coefficient ( K trans ), which reflects blood-brain barrier permeability, is influenced by circulation and measurement conditions. We hypothesized that focal low BBB permeability values can predict the spatial distribution of hemorrhagic transformation and global high BBB permeability values can predict the likelihood of hemorrhagic transformation. We retrospectively enrolled 106 patients with hemispheric stroke who received intra-arterial thrombolytic treatment. K trans maps were obtained with first-pass perfusion CT data. The K trans values at the region level, obtained with the Alberta Stroke Program Early CT Score system, were compared to determine the differences between the hemorrhagic transformation and nonhemorrhagic transformation regions. The K trans values of the whole ischemic region based on baseline perfusion CT were obtained as a variable to hemorrhagic transformation possibility at the global level. Forty-eight (45.3%) patients had hemorrhagic transformation, and 21 (19.8%) had symptomatic intracranial hemorrhage. At the region level, there were 82 ROIs with hemorrhagic transformation and parenchymal hemorrhage with a mean K trans , 0.5 ± 0.5/min, which was significantly lower than that in the nonhemorrhagic transformation regions ( P transformation ROIs was 0.7 ± 0.6/min. At the global level, there was a significant difference ( P = .01) between the mean K trans values of patients with symptomatic intracranial hemorrhage (1.3 ± 0.9) and those without symptomatic intracranial hemorrhage (0.8 ± 0.4). Only a high K trans value at the global level could predict the occurrence of symptomatic intracranial hemorrhage ( P transformation or symptomatic intracranial hemorrhage at the patient level, whereas focal low K trans values can predict the spatial distributions of hemorrhagic transformation at the region level. © 2017 by American Journal of Neuroradiology.

  13. Structural transformation of implanted diamond layers during high temperature annealing

    Rubanov, S.; Fairchild, B.A.; Suvorova, A.; Olivero, P.; Prawer, S.

    2015-01-01

    In the recent years graphitization of ion-beam induced amorphous layers became the basic tool for device fabrication in diamond. The etchable graphitic layers can be removed to form free-standing membranes into which the desired structures can be sculpted using FIB milling. The optical properties of the devices fabricated using this method are assumed on the model of sharp diamond–air interface. The real quality of this interface could depend on degree of graphitization of the amorphous damage layers after annealing. In the present work the graphitization process was studied using conventional and analytical TEM. It was found that annealing at 550 °C results in a partial graphitization of the implanted volume with formation of the nano-crystalline graphitic phase sandwiched between layers of tetrahedral amorphous carbon. Annealing at 1400 °C resulted in complete graphitization of the amorphous layers. The average size of graphite nano-crystals did not exceed 5 nm with predominant orientation of c-planes normal to the sample surface.

  14. Detection of gas-permeable fuel particles for highl 7490 temperature gas-cooled reactors

    Thiele, B.A.; Stinton, D.P.; Costanzo, D.A.

    1980-01-01

    Fuel for High-Temperature Gas-Cooled Reactors (HTGR) consists of uranium oxide-carbide and thoria microspheres coated with layers of pyrolytic carbon and silicon carbide. The pyrolytic carbon coatings must be gas-tight to perform properly during irradiation. Therefore, particles must be carefully characterized to determine the number of defective particles (ie bare kernels, and cracked or permeable coatings). Although techniques are available to determine the number of bare kernels or cracked coatings, no reliable technique has been available to measure coating permeability. This work describes a technique recently developed to determine whether coatings for a batch of particles are gas-tight or permeable. Although most of this study was performed on Biso-coated particles, the technique applies equally well to Triso-coated particles. About 150 randomly selected Biso-particle batches were studied in this work. These batches were first subjected to an 18-hr chlorination at 15000C, and the volatile thorium tetrachloride released through cracked or very permeable coatings was measured versus chlorination time. Chlorinated batches were also radiographed to detect any thorium that had migrated from the kernel into the coatings. From this work a technique was developed to determine coating permeability. This consists of an 18-hr chlorination of multiple samples without measurement of the heavy metal released. Each batch is then radiographed and the heavy metal diffusion within each particle is examined so it can be determined if a particle batch is permeable, slightly permeable, or gas-tight. (author)

  15. Back Analysis of the Permeability Coefficient of a High Core Rockfill Dam Based on a RBF Neural Network Optimized Using the PSO Algorithm

    Shichun Chi

    2015-01-01

    Full Text Available It is important to determine the seepage field parameters of a high core rockfill dam using the seepage data obtained during operation. For the Nuozhadu high core rockfill dam, a back analysis model is proposed using the radial basis function neural network optimized using a particle swarm optimization algorithm (PSO-RBFNN and the technology of finite element analysis for solving the saturated-unsaturated seepage field. The recorded osmotic pressure curves of osmometers, which are distributed in the maximum cross section, are applied to this back analysis. The permeability coefficients of the dam materials are retrieved using the measured seepage pressure values while the steady state seepage condition exists; that is, the water lever remains unchanged. Meanwhile, the parameters are tested using the unstable saturated-unsaturated seepage field while the water level rises. The results show that the permeability coefficients are reasonable and can be used to study the real behavior of a seepage field of a high core rockfill dam during its operation period.

  16. Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

    Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

    2014-08-01

    The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

  17. Permeability of uncharged organic molecules in reverse osmosis desalination membranes.

    Dražević, Emil; Košutić, Krešimir; Svalina, Marin; Catalano, Jacopo

    2017-06-01

    Reverse osmosis (RO) membranes are primarily designed for removal of salts i.e. for desalination of brackish and seawater, but they have also found applications in removal of organic molecules. While it is clear that steric exclusion is the dominant removal mechanism, the fundamental explanation for how and why the separation occurs remains elusive. Until recently there was no strong microscopic evidences elucidating the structure of the active polyamide layers of RO membranes, and thus they have been conceived as "black boxes"; or as an array of straight capillaries with a distribution of radii; or as polymers with a small amount of polymer free domains. The knowledge of diffusion and sorption coefficients is a prerequisite for understanding the intrinsic permeability of any organic solute in any polymer. At the same time, it is technically challenging to accurately measure these two fundamental parameters in very thin (20-300 nm) water-swollen active layers. In this work we have measured partition and diffusion coefficients and RO permeabilities of ten organic solutes in water-swollen active layers of two types of RO membranes, low (SWC4+) and high flux (XLE). We deduced from our results and recent microscopic studies that the solute flux of organic molecules in polyamide layer of RO membranes occurs in two domains, dense polymer (the key barrier layer) and the water filled domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Permeability Barrier Generation in the Martian Lithosphere

    Schools, Joe; Montési, Laurent

    2015-11-01

    Permeability barriers develop when a magma produced in the interior of a planet rises into the cooler lithosphere and crystallizes more rapidly than the lithosphere can deform (Sparks and Parmentier, 1991). Crystallization products may then clog the porous network in which melt is propagating, reducing the permeability to almost zero, i.e., forming a permeability barrier. Subsequent melts cannot cross the barrier. Permeability barriers have been useful to explain variations in crustal thickness at mid-ocean ridges on Earth (Magde et al., 1997; Hebert and Montési, 2011; Montési et al., 2011). We explore here under what conditions permeability barriers may form on Mars.We use the MELTS thermodynamic calculator (Ghiorso and Sack, 1995; Ghiorso et al., 2002; Asimow et al., 2004) in conjunction with estimated Martian mantle compositions (Morgan and Anders, 1979; Wänke and Dreibus, 1994; Lodders and Fegley, 1997; Sanloup et al., 1999; Taylor 2013) to model the formation of permeability barriers in the lithosphere of Mars. In order to represent potential past and present conditions of Mars, we vary the lithospheric thickness, mantle potential temperature (heat flux), oxygen fugacity, and water content.Our results show that permeability layers can develop in the thermal boundary layer of the simulated Martian lithosphere if the mantle potential temperature is higher than ~1500°C. The various Martian mantle compositions yield barriers in the same locations, under matching variable conditions. There is no significant difference in barrier location over the range of accepted Martian oxygen fugacity values. Water content is the most significant influence on barrier development as it reduces the temperature of crystallization, allowing melt to rise further into the lithosphere. Our lower temperature and thicker lithosphere model runs, which are likely the most similar to modern Mars, show no permeability barrier generation. Losing the possibility of having a permeability

  19. Equivalent physical models and formulation of equivalent source layer in high-resolution EEG imaging

    Yao Dezhong; He Bin

    2003-01-01

    In high-resolution EEG imaging, both equivalent dipole layer (EDL) and equivalent charge layer (ECL) assumed to be located just above the cortical surface have been proposed as high-resolution imaging modalities or as intermediate steps to estimate the epicortical potential. Presented here are the equivalent physical models of these two equivalent source layers (ESL) which show that the strength of EDL is proportional to the surface potential of the layer when the outside of the layer is filled with an insulator, and that the strength of ECL is the normal current of the layer when the outside is filled with a perfect conductor. Based on these equivalent physical models, closed solutions of ECL and EDL corresponding to a dipole enclosed by a spherical layer are given. These results provide the theoretical basis of ESL applications in high-resolution EEG mapping

  20. Equivalent physical models and formulation of equivalent source layer in high-resolution EEG imaging

    Yao Dezhong [School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu City, 610054, Sichuan Province (China); He Bin [The University of Illinois at Chicago, IL (United States)

    2003-11-07

    In high-resolution EEG imaging, both equivalent dipole layer (EDL) and equivalent charge layer (ECL) assumed to be located just above the cortical surface have been proposed as high-resolution imaging modalities or as intermediate steps to estimate the epicortical potential. Presented here are the equivalent physical models of these two equivalent source layers (ESL) which show that the strength of EDL is proportional to the surface potential of the layer when the outside of the layer is filled with an insulator, and that the strength of ECL is the normal current of the layer when the outside is filled with a perfect conductor. Based on these equivalent physical models, closed solutions of ECL and EDL corresponding to a dipole enclosed by a spherical layer are given. These results provide the theoretical basis of ESL applications in high-resolution EEG mapping.

  1. Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer

    Chavarkar, Prashant; Smorchkova, Ioulia P.; Keller, Stacia; Mishra, Umesh; Walukiewicz, Wladyslaw; Wu, Yifeng

    2005-02-01

    A Group III nitride based high electron mobility transistors (HEMT) is disclosed that provides improved high frequency performance. One embodiment of the HEMT comprises a GaN buffer layer, with an Al.sub.y Ga.sub.1-y N (y=1 or y 1) layer on the GaN buffer layer. An Al.sub.x Ga.sub.1-x N (0.ltoreq.x.ltoreq.0.5) barrier layer on to the Al.sub.y Ga.sub.1-y N layer, opposite the GaN buffer layer, Al.sub.y Ga.sub.1-y N layer having a higher Al concentration than that of the Al.sub.x Ga.sub.1-x N barrier layer. A preferred Al.sub.y Ga.sub.1-y N layer has y=1 or y.about.1 and a preferred Al.sub.x Ga.sub.1-x N barrier layer has 0.ltoreq.x.ltoreq.0.5. A 2DEG forms at the interface between the GaN buffer layer and the Al.sub.y Ga.sub.1-y N layer. Respective source, drain and gate contacts are formed on the Al.sub.x Ga.sub.1-x N barrier layer. The HEMT can also comprising a substrate adjacent to the buffer layer, opposite the Al.sub.y Ga.sub.1-y N layer and a nucleation layer between the Al.sub.x Ga.sub.1-x N buffer layer and the substrate.

  2. Self-double-emulsifying drug delivery system (SDEDDS): a new way for oral delivery of drugs with high solubility and low permeability.

    Qi, Xiaole; Wang, Lishuang; Zhu, Jiabi; Hu, Zhenyi; Zhang, Jie

    2011-05-16

    Water-in-oil-in-water (w/o/w) double emulsions are potential for enhancing oral bioavailability of drugs with high solubility and low permeability, but their industrial application is limited due to the instability. Herein, we developed a novel formulation, self-double-emulsifying drug delivery systems (SDEDDS) by formulating mixtures of hydrophilic surfactants and water-in-oil (w/o) emulsions, which were easier to be stable through formulations optimization. SDEDDS can spontaneously emulsify to water-in-oil-in-water (w/o/w) double emulsions in the mixed aqueous gastrointestinal environment, with drugs encapsulated in the internal water phase of the double emulsions. We employed SDEDDS to improve the oral absorption of pidotimod, a peptide-like drug with high solubility and low permeability. The optimized pidotimod-SDEDDS were found to be stable up to 6 months under 25°C. Plasma concentration-time profiles from pharmacokinetic studies in rats dosed with SDEDDS showed 2.56-fold (p<0.05) increased absorption of pidotimod, compared to the pidotimod solution. Histopathologic studies confirmed that SDEDDS exerted absorption promoting effect without serious local damages. These studies demonstrate that SDEDDS may be a promising strategy for peroral delivery of peptide and peptidomimetic drugs. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. A theoretical model for gas permeability in a composite membrane

    Serrano, D. A

    2009-01-01

    We present in this work an analytical expression for permeability in a two-layer composite membrane, which was derived assuming the same hypothesis as those of Adzumi model for permeability in a homogeneous membrane. Whereas in Adzumi model permeability shows a linear dependence on the mean pressure, our model for a composite membrane related permeability to pressure through a rather complex expression, which covers the whole range of flow, from molecular-Knudsen to viscous-Poiseuille regimes. The expression obtained for permeability contained information of membrane structural properties as pore size, porosity and thickness of each layer, as well as gas nature and operational conditions. Our two-layer-model expression turns into Adzumi formula when the structure of the layers approach to each other. [es

  4. Development of vinylic and acetylenic functionalized structures based on high permeable glassy polymers as membrane materials for gas mixtures separation

    Roizard, D.; Kiryukhina, Y.; Masalev, A.; Khotimskiy, V.; Teplyakov, V.; Barth, D.

    2013-03-01

    There are several challenging separation problems in industries which can be solved with the help of membrane technologies. It is the case for instance of the purification of gas energy carriers (i.e. H2, CH4) from CO2 as well as the CO2 recovery from flue gas. Glassy polymers containing trimethylsilyl residues like poly(1-trimethylsilyl-1-propyne) [PTMSP] and polyvinyltrimethylsilane [PVTMS] are known to exhibit good membrane properties for gas separation. This paper reports two ways of improving their performances based on the controlled introduction of selective groups - alkyl imidazomium salts (C4I) and polyethyleneglycol (M-PEG)- able to enhance CO2 selectivity. CO2 Isotherm sorption data and permeability measurements have shown that the membrane performances could be significantly improved when C4I and M-PEG were introduced as residues covalently bounded to the main polymer chain. Moreover the introduced bromine reactive centres could also be used to induce chemical crosslinking giving rise to more resistant and stable membranes to organic vapours. With the C4I groups, the CO2 sorption could be enhanced by a factor 4.4.

  5. Mechanical and transport properties of rocks at high temperatures and pressures. Task II. Fracture permeability of crystalline rocks as a function of temperature, pressure, and hydrothermal alteration. Final report

    Johnson, B.

    1985-11-01

    Pore-fluid chemical interactions on both short and long time scales can significantly change the permeability of a rock. Measurement of the permeability variations requires adaption and modification on standard measurement systems, with special attention given to pore-fluid flow rates and metal corrosion of system components. In this report, system requirements and capabilities are reviewed, analyzed, and recommendations made. Special attention is given to the choice of corrosion resistant metals, fluid-flow systems, back-pressure systems, jacketing materials, and flow-rate measurement. On the basis of this study, an economical, highly flexible, permeability system was designed and built. The system allows measurement of permeability over the darcy to nanodarcy range, using geologically meaningful, chemically reactive, pore fluids under constant volume flow rates as small as 0.2 ml/day at temperatures in excess of 300C, fluid pressures to 20 MPa, and confining pressures to 100 MPa. 7 refs., 3 figs., 1 tab.

  6. High-energy X-ray production in a boundary layer of an accreting neutron star

    Hanawa, Tomoyuki

    1991-01-01

    It is shown by Monte Carlo simulation that high-energy X-rays are produced through Compton scattering in a boundary layer of an accreting neutron star. The following is the mechanism for the high-energy X-ray production. An accreting neutron star has a boundary layer rotating rapidly on the surface. X-rays radiated from the star's surface are scattered in part in the boundary layer. Since the boundary layer rotates at a semirelativistic speed, the scattered X-ray energy is changed by the Compton effect. Some X-rays are scattered repeatedly between the neutron star and the boundary layer and become high-energy X-rays. This mechanism is a photon analog of the second-order Fermi acceleration of cosmic rays. When the boundary layer is semitransparent, high-energy X-rays are produced efficiently. 17 refs

  7. The effect of TiO{sub 2} nanoparticles on water permeability and thermal and mechanical properties of high strength self-compacting concrete

    Nazari, Ali, E-mail: alinazari84@aut.ac.ir [Department of Technical and Engineering Sciences, Islamic Azad University (Saveh Branch), Saveh (Iran, Islamic Republic of); Riahi, Shadi [Department of Technical and Engineering Sciences, Islamic Azad University (Saveh Branch), Saveh (Iran, Islamic Republic of)

    2010-12-15

    Research highlights: {yields} TiO{sub 2} nanoparticles effects on self-compacting concrete. {yields} Strength assessments. {yields} Water permeability. {yields} Thermal properties. {yields} Pore structure. {yields} Microstructure evaluations. - Abstract: In this work, strength assessments and coefficient of water absorption of high performance self-compacting concrete containing different amounts of TiO{sub 2} nanoparticles have been investigated. The results indicate that the strength and the resistance to water permeability of the specimens are improved by adding TiO{sub 2} nanoparticles in the cement paste up to 4.0 wt%. TiO{sub 2} nanoparticles, as a result of increased crystalline Ca(OH){sub 2} amount especially at the early age of hydration, could accelerate C-S-H gel formation and hence increase the strength of the concrete specimens. In addition, TiO{sub 2} nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores. Several empirical relationships have been presented to predict flexural and split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of the peaks related to hydrated products in X-ray diffraction results, all indicate that TiO{sub 2} nanoparticles could improve mechanical and physical properties of the concrete specimens.

  8. The effect of TiO2 nanoparticles on water permeability and thermal and mechanical properties of high strength self-compacting concrete

    Nazari, Ali; Riahi, Shadi

    2010-01-01

    Research highlights: → TiO 2 nanoparticles effects on self-compacting concrete. → Strength assessments. → Water permeability. → Thermal properties. → Pore structure. → Microstructure evaluations. - Abstract: In this work, strength assessments and coefficient of water absorption of high performance self-compacting concrete containing different amounts of TiO 2 nanoparticles have been investigated. The results indicate that the strength and the resistance to water permeability of the specimens are improved by adding TiO 2 nanoparticles in the cement paste up to 4.0 wt%. TiO 2 nanoparticles, as a result of increased crystalline Ca(OH) 2 amount especially at the early age of hydration, could accelerate C-S-H gel formation and hence increase the strength of the concrete specimens. In addition, TiO 2 nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores. Several empirical relationships have been presented to predict flexural and split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of the peaks related to hydrated products in X-ray diffraction results, all indicate that TiO 2 nanoparticles could improve mechanical and physical properties of the concrete specimens.

  9. Metallic few-layered VS2 ultrathin nanosheets: high two-dimensional conductivity for in-plane supercapacitors.

    Feng, Jun; Sun, Xu; Wu, Changzheng; Peng, Lele; Lin, Chenwen; Hu, Shuanglin; Yang, Jinlong; Xie, Yi

    2011-11-09

    With the rapid development of portable electronics, such as e-paper and other flexible devices, practical power sources with ultrathin geometries become an important prerequisite, in which supercapacitors with in-plane configurations are recently emerging as a favorable and competitive candidate. As is known, electrode materials with two-dimensional (2D) permeable channels, high-conductivity structural scaffolds, and high specific surface areas are the indispensible requirements for the development of in-plane supercapacitors with superior performance, while it is difficult for the presently available inorganic materials to make the best in all aspects. In this sense, vanadium disulfide (VS(2)) presents an ideal material platform due to its synergic properties of metallic nature and exfoliative characteristic brought by the conducting S-V-S layers stacked up by weak van der Waals interlayer interactions, offering great potential as high-performance in-plane supercapacitor electrodes. Herein, we developed a unique ammonia-assisted strategy to exfoliate bulk VS(2) flakes into ultrathin VS(2) nanosheets stacked with less than five S-V-S single layers, representing a brand new two-dimensional material having metallic behavior aside from graphene. Moreover, highly conductive VS(2) thin films were successfully assembled for constructing the electrodes of in-plane supercapacitors. As is expected, a specific capacitance of 4760 μF/cm(2) was realized here in a 150 nm in-plane configuration, of which no obvious degradation was observed even after 1000 charge/discharge cycles, offering as a new in-plane supercapacitor with high performance based on quasi-two-dimensional materials.

  10. Layer-by-layer modification of high surface curvature nanoparticles with weak polyelectrolytes using a multiphase solvent precipitation process.

    Nagaraja, Ashvin T; You, Yil-Hwan; Choi, Jeong-Wan; Hwang, Jin-Ha; Meissner, Kenith E; McShane, Michael J

    2016-03-15

    The layer-by-layer modification of ≈5 nm mercaptocarboxylic acid stabilized gold nanoparticles was studied in an effort to illustrate effective means to overcome practical issues in handling and performing surface modification of such extremely small materials. To accomplish this, each layer deposition cycle was separated into a multi-step process wherein solution pH was controlled in two distinct phases of polyelectrolyte adsorption and centrifugation. Additionally, a solvent precipitation step was introduced to make processing more amenable by concentrating the sample and exchanging solution pH before ultracentrifugation. The pH-dependent assembly on gold nanoparticles was assessed after each layer deposition cycle by monitoring the plasmon peak absorbance location, surface charge, and the percentage of nanoparticles recovered. The selection of solution pH during the adsorption phase was found to be a critical parameter to enhance particle recovery and maximize surface charge when coating with weak polyelectrolytes. One bilayer was deposited with a high yield and the modified particles exhibited enhanced colloidal stability across a broad pH range and increased ionic strength. These findings support the adoption of this multi-step processing approach as an effective and generalizable approach to improve stability of high surface curvature particles. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Octopus microvasculature: permeability to ferritin and carbon.

    Browning, J

    1979-01-01

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

  12. Formation and Control of Self-Sealing High Permeability Groundwater Mounds in Impermeable Sediment: Implications for SUDS and Sustainable Pressure Mound Management

    David D. J. Antia

    2009-10-01

    Full Text Available A groundwater mound (or pressure mound is defined as a volume of fluid dominated by viscous flow contained within a sediment volume where the dominant fluid flow is by Knudsen Diffusion. High permeability self-sealing groundwater mounds can be created as part of a sustainable urban drainage scheme (SUDS using infiltration devices. This study considers how they form, and models their expansion and growth as a function of infiltration device recharge. The mounds grow through lateral macropore propagation within a Dupuit envelope. Excess pressure relief is through propagating vertical surge shafts. These surge shafts can, when they intersect the ground surface result, in high volume overland flow. The study considers that the creation of self-sealing groundwater mounds in matrix supported (clayey sediments (intrinsic permeability = 10–8 to 10–30 m3 m–2 s–1 Pa–1 is a low cost, sustainable method which can be used to dispose of large volumes of storm runoff (<20→2,000 m3/24 hr storm/infiltration device and raise groundwater levels. However, the inappropriate location of pressure mounds can result in repeated seepage and ephemeral spring formation associated with substantial volumes of uncontrolled overland flow. The flow rate and flood volume associated with each overland flow event may be substantially larger than the associated recharge to the pressure mound. In some instances, the volume discharged as overland flow in a few hours may exceed the total storm water recharge to the groundwater mound over the previous three weeks. Macropore modeling is used within the context of a pressure mound poro-elastic fluid expulsion model in order to analyze this phenomena and determine (i how this phenomena can be used to extract large volumes of stored filtered storm water (at high flow rates from within a self-sealing high permeability pressure mound and (ii how self-sealing pressure mounds (created using storm water infiltration can be used to

  13. Seed layer technique for high quality epitaxial manganite films

    P. Graziosi

    2016-08-01

    Full Text Available We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening temperature, strain profile and chemical states are derived.

  14. Optimization of nitridation conditions for high quality inter-polysilicon dielectric layers

    Klootwijk, J.H.; Bergveld, H.J.; van Kranenburg, H.; Woerlee, P.H.; Wallinga, Hans

    1996-01-01

    Nitridation of deposited high temperature oxides (HTO) was studied to form high quality inter-polysilicon dielectric layers for embedded non volatile memories. Good quality dielectric layers were obtained earlier by using an optimized deposition of polysilicon and by performing a post-dielectric

  15. EDZ and permeability in clayey rocks

    Levasseur, Severine; Collin, Frederic; Charlier, Robert; Besuelle, Pierre; Chambon, Rene; Viggiani, Cino

    2010-01-01

    Document available in extended abstract form only. Deep geological layers are being considered as potential host rocks for the high level radioactivity waste disposals. During drilling in host rocks, an excavated damaged zone - EDZ is created. The fluid transmissivity may be modified in this damaged zone. This paper deals with the permeability evolution in relation with diffuse and/or localized crack propagation in the material. We mainly focus on argillaceous rocks and on some underground laboratories: Mol URL in Boom clay, Bure URL in Callovo-Oxfordian clay and Mont-Terri URL in Opalinus clay. First, observations of damage around galleries are summarized. Structure of damage in localized zone or in fracture has been observed at underground gallery scale within the excavation damaged zone (EDZ). The first challenge for a correct understanding of all the processes occurring within the EDZ is the characterization at the laboratory scale of the damage and localization processes. The observation of the initiation and propagation of the localized zones needs for advanced techniques. X-ray tomography is a non-destructive imaging technique that allows quantification of internal features of an object in 3D. If mechanical loading of a specimen is applied inside a X-ray CT apparatus, successive 3D images at different loading steps show the evolution of the specimen. However, in general volumetric strain in a shear band is small compared to the shear strain and, unfortunately, in tomographic images grey level is mainly sensitive to the local mass density field. Such a limitation has been recently overcome by complementing X-ray tomography with 3D Volumetric Digital Image Correlation (V-DIC) which allows the determination of the full strain tensor field. Then it is possible to further explore the progression of localized deformation in the specimen. The second challenge is the robust modelling of the strain localized process. In fact, modelling the damage process with finite

  16. Highly ductile multilayered films by layer-by-layer assembly of oppositely charged polyurethanes for biomedical applications.

    Podsiadlo, Paul; Qin, Ming; Cuddihy, Meghan; Zhu, Jian; Critchley, Kevin; Kheng, Eugene; Kaushik, Amit K; Qi, Ying; Kim, Hyoung-Sug; Noh, Si-Tae; Arruda, Ellen M; Waas, Anthony M; Kotov, Nicholas A

    2009-12-15

    Multilayered thin films prepared with the layer-by-layer (LBL) assembly technique are typically "brittle" composites, while many applications such as flexible electronics or biomedical devices would greatly benefit from ductile, and tough nanostructured coatings. Here we present the preparation of highly ductile multilayered films via LBL assembly of oppositely charged polyurethanes. Free-standing films were found to be robust, strong, and tough with ultimate strains as high as 680% and toughness of approximately 30 MJ/m(3). These results are at least 2 orders of magnitude greater than most LBL materials presented until today. In addition to enhanced ductility, the films showed first-order biocompatibility with animal and human cells. Multilayered structures incorporating polyurethanes open up a new research avenue into the preparation of multifunctional nanostructured films with great potential in biomedical applications.

  17. Oxide layer stability in lead-bismuth at high temperature

    Martín, F. J.; Soler, L.; Hernández, F.; Gómez-Briceño, D.

    2004-11-01

    Materials protection by 'in situ' oxidation has been studied in stagnant lead-bismuth, with different oxygen levels (H 2/H 2O ratios of 0.3 and 0.03), at temperatures from 535 °C to 600 °C and times from 100 to 3000 h. The materials tested were the martensitic steels F82Hmod, EM10 and T91 and the austenitic stainless steels, AISI 316L and AISI 304L. The results obtained point to the existence of an apparent threshold temperature above which corrosion occurs and the formation of a protective and stable oxide layer is not possible. This threshold temperature depends on material composition, oxygen concentration in the liquid lead-bismuth and time. The threshold temperature is higher for the austenitic steels, especially for the AISI 304L, and it increases with the oxygen concentration in the lead-bismuth. The oxide layer formed disappear with time and, after 3000 h all the materials, except AISI 304L, suffer corrosion, more severe for the martensitic steels and at the highest temperature tested.

  18. Termination layer compensated tunnelling magnetoresistance in ferrimagnetic Heusler compounds with high perpendicular magnetic anisotropy.

    Jeong, Jaewoo; Ferrante, Yari; Faleev, Sergey V; Samant, Mahesh G; Felser, Claudia; Parkin, Stuart S P

    2016-01-18

    Although high-tunnelling spin polarization has been observed in soft, ferromagnetic, and predicted for hard, ferrimagnetic Heusler materials, there has been no experimental observation to date of high-tunnelling magnetoresistance in the latter. Here we report the preparation of highly textured, polycrystalline Mn3Ge films on amorphous substrates, with very high magnetic anisotropy fields exceeding 7 T, making them technologically relevant. However, the small and negative tunnelling magnetoresistance that we find is attributed to predominant tunnelling from the lower moment Mn-Ge termination layers that are oppositely magnetized to the higher moment Mn-Mn layers. The net spin polarization of the current reflects the different proportions of the two distinct termination layers and their associated tunnelling matrix elements that result from inevitable atomic scale roughness. We show that by engineering the spin polarization of the two termination layers to be of the same sign, even though these layers are oppositely magnetized, high-tunnelling magnetoresistance is possible.

  19. Fabrication of high permeability non-oriented electrical steels by increasing 〈0 0 1〉 recrystallization texture using compacted strip casting processes

    Liu, Hai-Tao, E-mail: liuht@ral.neu.edu.cn [State Key Laboratory of Rolling and Automation, Northeastern University, PO Box 105, Shenyang 110819 (China); Institute of Research of Iron and Steel, Shasteel, Zhangjiagang 215625, Jiangsu (China); Schneider, J. [Institut für Metallformung, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-Str. 4, D-09596 Freiberg (Germany); Li, Hua-Long [Institute of Research of Iron and Steel, Shasteel, Zhangjiagang 215625, Jiangsu (China); Sun, Yu; Gao, Fei; Lu, Hui-Hu; Song, Hong-Yu [State Key Laboratory of Rolling and Automation, Northeastern University, PO Box 105, Shenyang 110819 (China); Li, Lei; Geng, Dian-Qiao [Key Laboratory of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Liu, Zhen-Yu; Wang, Guo-Dong [State Key Laboratory of Rolling and Automation, Northeastern University, PO Box 105, Shenyang 110819 (China)

    2015-01-15

    In this paper we will report on the application of the twin-roll casting technique to get a 2 mm thick material of Fe-3.2%Si alloy, which was finally hot rolled, cold rolled and annealed. After a mild hot rolling to a thickness of 1 mm and a mild cold rolling to a thickness of 0.35 mm, we obtained a high intensity of λ-fiber (〈0 0 1〉|| ND) and η-fiber (〈0 0 1〉|| RD) texture concentrated on cube ({0 0 1}〈0 1 0〉) component and a diminishing intensity of the γ-fiber (〈1 1 1〉|| ND) texture, and a large average grain size in the final processed material. The experimental results for the evolution of the microstructure and texture along the used processing routes were described within the paper in detail. The formation mechanism for the desired recrystallization textures were explained in terms of oriented nucleation, micro-growth selection, accumulated deformation stored energy, geometric softening and orientation pinning. It will be demonstrated that this new processing route using the compact strip casting offers the possibility to fabricate high permeability non-oriented electrical steels without additional fabrication steps like hot band annealing or two step cold rolling with intermediate annealing as in the case of conventional processing route. - Highlights: • High permeability non-oriented electrical steel was fabricated by strip casting processes. • Hot band annealing or two step cold rolling with intermediate annealing was eliminated. • Prevailing of 〈0 0 1〉|| ND and 〈0 0 1〉|| RD textures over diminishing 〈1 1 1〉|| ND texture was realized. • Evolution of microstructure and texture along the used processing routes were described.

  20. Biowaiver extension potential to BCS Class III high solubility-low permeability drugs: bridging evidence for metformin immediate-release tablet.

    Cheng, Ching-Ling; Yu, Lawrence X; Lee, Hwei-Ling; Yang, Chyun-Yu; Lue, Chang-Sha; Chou, Chen-Hsi

    2004-07-01

    The biopharmaceutics classification system (BCS) allows biowaiver for rapid dissolving immediate-release (IR) products of Class I drugs (high solubility and high permeability). The possibility of extending biowaivers to Class III high solubility and low permeability drugs is currently under scrutiny. In vivo bioequivalence data of different formulations of Class III drugs would support such an extension. The objective of this work was to demonstrate the bioequivalence of two marketed IR tablet products of a Class III drug, metformin hydrochloride, that are rapidly dissolving and have similar in vitro dissolution profiles. The effect of race on the systemic exposure of metformin was also explored. A randomized, open-label, two-period crossover study was conducted in 12 healthy Chinese male volunteers. Each subject received a single-dose of 500 mg of each product after an overnight fasting. The plasma concentrations of metformin were followed for 24 h. No significant formulation effect was found for the bioequivalence metrics: areas under concentration-time curve (AUC0-t, AUC0-infinity) and maximal concentration (Cmax). The 90% confidence intervals for the ratio of means were found within the acceptance range of 80-125% for the log-transformed data. Based on these results, it was concluded that the two IR products are bioequivalent. The pharmacokinetic parameters of metformin in Chinese for both products were similar and were in good agreement with those reported for metformin IR tablets in other ethnic populations. This study serves as an example for supporting biowaiver for BCS Class III drugs.

  1. Relationship between permeability and damage in concretes at high temperature; Lien entre la permeabilite et l'endommagement dans les betons a haute temperature

    Dal Pont, St

    2004-09-15

    Due to its technical and economical advantages, concrete is nowadays the most used building material in civil engineering. Even if its use is known since nearly two centuries, its behavior has not been yet completely explained due to the complexity of its porous microstructure. This fact is quite evident under particular conditions such as, by instance, during an elevation of temperature. This condition can mainly occur in two cases: due to a casualty (e.g. a fire) or in normal use conditions (e.g. storage of nuclear rejects). This work aims at contributing to the study of the phenomena that can be observed in concrete exposed to high temperatures and, in particular, focuses on the study of the evolution of intrinsic permeability. The characterisation of permeability (which is hardly measurable in hot conditions) is necessary for describing and modelling transport phenomena which occur in porous media. An experimental study has been made in collaboration with the CEA. A real-scale hollow cylinder has been instrumented with gauges for studying the evolution of temperature and gas pressure fields inside concrete. Later, the cylinder has been then numerically modelled by means of a thermo-hydro-chemical (THC) and a thermo-hydro-chemo-mechanical (THCM) model. The THC model, implemented by means of the finite volume method, has allowed a first, qualitative study of the behaviour of concrete submitted to high temperature. This model, which, for sake of simplicity, has neglected all mechanical effects, has allowed the description of the main phenomena occurring inside concrete: mass transport, phase changes, microstructure evolution. Later, the modelling has been completed by means of the THCM model using the Hitecosp code, implemented by means of the finite element method at the university of Padua. This code allows a very complete description of the phenomena occurring inside concrete and takes into consideration the mechanical behavior of concrete by means of an

  2. Relationship between permeability and damage in concretes at high temperature; Lien entre la permeabilite et l'endommagement dans les betons a haute temperature

    Dal Pont, St

    2004-09-15

    Due to its technical and economical advantages, concrete is nowadays the most used building material in civil engineering. Even if its use is known since nearly two centuries, its behavior has not been yet completely explained due to the complexity of its porous microstructure. This fact is quite evident under particular conditions such as, by instance, during an elevation of temperature. This condition can mainly occur in two cases: due to a casualty (e.g. a fire) or in normal use conditions (e.g. storage of nuclear rejects). This work aims at contributing to the study of the phenomena that can be observed in concrete exposed to high temperatures and, in particular, focuses on the study of the evolution of intrinsic permeability. The characterisation of permeability (which is hardly measurable in hot conditions) is necessary for describing and modelling transport phenomena which occur in porous media. An experimental study has been made in collaboration with the CEA. A real-scale hollow cylinder has been instrumented with gauges for studying the evolution of temperature and gas pressure fields inside concrete. Later, the cylinder has been then numerically modelled by means of a thermo-hydro-chemical (THC) and a thermo-hydro-chemo-mechanical (THCM) model. The THC model, implemented by means of the finite volume method, has allowed a first, qualitative study of the behaviour of concrete submitted to high temperature. This model, which, for sake of simplicity, has neglected all mechanical effects, has allowed the description of the main phenomena occurring inside concrete: mass transport, phase changes, microstructure evolution. Later, the modelling has been completed by means of the THCM model using the Hitecosp code, implemented by means of the finite element method at the university of Padua. This code allows a very complete description of the phenomena occurring inside concrete and takes into consideration the mechanical behavior of concrete by means of an

  3. Conditional analysis near strong shear layers in DNS of isotropic turbulence at high Reynolds number

    Ishihara, Takashi; Kaneda, Yukio [Graduate School of Engineering, Nagoya University (Japan); Hunt, Julian C R, E-mail: ishihara@cse.nagoya-u.ac.jp [University College of London (United Kingdom)

    2011-12-22

    Data analysis of high resolution DNS of isotropic turbulence with the Taylor scale Reynolds number R{sub {lambda}} = 1131 shows that there are thin shear layers consisting of a cluster of strong vortex tubes with typical diameter of order 10{eta}, where {eta} is the Kolmogorov length scale. The widths of the layers are of the order of the Taylor micro length scale. According to the analysis of one of the layers, coarse grained vorticity in the layer are aligned approximately in the plane of the layer so that there is a net mean shear across the layer with a mean velocity jump of the order of the root-mean-square of the fluctuating velocity, and energy dissipation averaged over the layer is larger than ten times the average over the whole flow. The mean and the standard deviation of the energy transfer T(x, {kappa}) from scales larger than 1/{kappa} to scales smaller than 1/{kappa} at position x are largest within the layers (where the most intense vortices and dissipation occur), but are also large just outside the layers (where viscous stresses are weak), by comparison with the average values of T over the whole region. The DNS data are consistent with exterior fluctuation being damped/filtered at the interface of the layer and then selectively amplified within the layer.

  4. Ge nano-layer fabricated by high-fluence low-energy ion implantation

    Lu Tiecheng; Dun Shaobo; Hu Qiang; Zhang Songbao; An Zhu; Duan Yanmin; Zhu Sha; Wei Qiangmin; Wang Lumin

    2006-01-01

    A Ge nano-layer embedded in the surface layer of an amorphous SiO 2 film was fabricated by high-fluence low-energy ion implantation. The component, phase, nano-structure and luminescence properties of the nano-layer were studied by means of Rutherford backscattering, glancing incident X-ray diffraction, laser Raman scattering, transmission electron microscopy and photoluminescence. The relation between nano-particle characteristics and ion fluence was also studied. The results indicate that nano-crystalline Ge and nano-amorphous Ge particles coexist in the nano-layer and the ratio of nano-crystalline Ge to nano-particle Ge increases with increasing ion fluence. The intensity of photoluminescence from the nano-layer increases with increasing ion fluence also. Prepared with certain ion fluences, high-density nano-layers composed of uniform-sized nano-particles can be observed

  5. Cover-layer with High Refractive Index for Near-Field Recording Media

    Kim, Jin-Hong; Lee, Jun-Seok

    2007-06-01

    TiO2 nanoparticles are added into UV-curable resin to increase the refractive index of the cover-layer laminated for cover-layer incident near-field recording media. A high refractive index is required for the cover-layer operating with an optical head with a high numerical aperture. The eye pattern from a cover-layer coated 20 GB read-only memory disc in which the refractive index of the cover-layer is 1.75 is achieved, but the gap servo is unstable owing to the rough surface of the cover-layer. Even though the light loss due to the nanoparticles is negligible, a rough microstructure is developed by adding the nanoparticles into an organic binder material. To achieve a smooth surface for a stable gap servo, the solubility of the nanoparticles should be enhanced by the optimization of the surface of the nanoparticles.

  6. Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

    Zuzuarregui, Ana; Coto, Borja; Rodríguez, Jorge; Gregorczyk, Keith E.; Ruiz de Gopegui, Unai; Barriga, Javier; Knez, Mato

    2015-08-01

    Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

  7. Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

    Zuzuarregui, Ana, E-mail: a.zuzuarregui@nanogune.eu; Gregorczyk, Keith E. [CIC Nanogune Consolider, de Tolosa Hiribidea 76, 20018 San Sebastián (Spain); Coto, Borja; Ruiz de Gopegui, Unai; Barriga, Javier [IK4-Tekniker, Iñaki Goenaga 5, 20600 Eibar (Spain); Rodríguez, Jorge [Torresol Energy (SENER Group), Avda. de Zugazarte 61, 48930 Las Arenas (Spain); Knez, Mato [CIC Nanogune Consolider, de Tolosa Hiribidea 76, 20018 San Sebastián (Spain); IKERBASQUE Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao (Spain)

    2015-08-10

    Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

  8. Highly reflective polymeric substrates functionalized utilizing atomic layer deposition

    Zuzuarregui, Ana; Gregorczyk, Keith E.; Coto, Borja; Ruiz de Gopegui, Unai; Barriga, Javier; Rodríguez, Jorge; Knez, Mato

    2015-01-01

    Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur

  9. Electrokinetic Enhanced Permanganate Delivery for Low Permeability Soil Remediation

    Chowdhury, A. I.; Gerhard, J.; Reynolds, D. A.; Sleep, B. E.; O'Carroll, D. M.

    2016-12-01

    Contaminant mass sequestered in low permeability zones (LPZ) in the subsurface has become a significant concern due to back diffusion of contaminants, leading to contaminant rebound following treatment of the high permeability strata. In-situ remediation technologies such as in-situ chemical oxidation (ISCO) are promising, however, successful delivery of oxidants into silts and clays remains a challenge. Electrokinetics (EK) has been proposed as a technique that can overcome this challenge by delivering oxidants into low permeability soils. This study demonstrates the ability of EK to facilitate permanganate delivery into silt for treatment of trichloroethene (TCE). A two-dimensional sandbox was packed with alternate vertical layers of coarse sand and silt contaminated with high concentrations of aqueous phase TCE. Nine experiments were conducted to compare EK-enhanced in-situ chemical oxidation (EK-ISCO) to ISCO alone or EK alone. Frequent groundwater sampling at multiple locations combined with image analysis provided detailed mapping of TCE, permanganate, and manganese dioxide mass distributions. EK-ISCO successfully delivered the permanganate throughout the silt cross-section while ISCO without EK resulted in permanganate delivery only to the edges of the silt layer. EK-ISCO resulted in a 4.4 order-of-magnitude (OoM) reduction in TCE concentrations in the coarse sand compared to a 3.5 OoM reduction for ISCO alone. This study suggests that electrokinetics coupled with ISCO can achieve enhanced remediation of lower permeability strata, where remediation technologies for successful contaminant mass removal would otherwise be limited.

  10. Vapor Transport Through Fractures and Other High-Permeability Paths: Its Role in the Drift Scale Test at Yucca Mountain, Nevada

    Mukhopadhyay, S.; Tsang, Y. W.

    2001-12-01

    Heating unsaturated fractured tuff sets off a series of complicated thermal-hydrological (TH) processes, which result in large-scale redistribution of moisture in the host rock. Moisture redistribution arises from boiling of water near heat sources, transport of vapor away from those heat sources, condensation of that vapor in cooler rock, and subsequent gravity drainage of condensate through fractures. Vapor transport through high-permeability paths, which include both the fractures in the rock and other conduits, contributes to the evolution of these TH processes in two ways. First, the highly permeable natural fractures provide easy passage for vapor away from the heat sources. Second, these fractures and other highly permeable conduits allow vapor (and the associated energy) to escape the rock through open boundaries of the test domain. The overall impact of vapor transport on the evolution of the TH processes can be more easily understood in the context of the Drift Scale Test (DST), the largest ever in situ heater test in unsaturated fractured tuff. The DST, in which a large volume of rock has been heated for four years now, is located in the middle nonlithophysal (Tptpmn) stratigraphic unit of Yucca Mountain, Nevada. The fractured tuff in Tptpmn contains many well-connected fractures. In the DST, heating is provided by nine cannister heaters placed in a five-meter-diameter Heated Drift (HD) and fifty wing heaters installed orthogonal to the axis of the HD. The test has many instrumentation boreholes, some of which are not sealed by packers or grout and may provide passage for vapor and energy. Of these conduits, the boreholes housing the wing heaters are most important for vapor transport because of their proximity to heat sources. While part of the vapor generated by heating moves away from the heat sources through the fractures and condenses elsewhere in the rock, the rest of the vapor, under gas-pressure difference, enters the HD by way of the high-permeability

  11. Water permeability in human airway epithelium

    Pedersen, Peter Steen; Procida, Kristina; Larsen, Per Leganger

    2005-01-01

    Osmotic water permeability (P(f)) was studied in spheroid-shaped human airway epithelia explants derived from nasal polyps by the use of a new improved tissue collection and isolation procedure. The fluid-filled spheroids were lined with a single cell layer with the ciliated apical cell membrane ...

  12. Highly sensitive multi-layer pressure sensor with an active nanostructured layer of an organic molecular metal

    Laukhin, V; Lebedev, V; Laukhina, E; Rovira, C; Veciana, J

    2016-01-01

    This work addresses to the modern technologies that need to be instrumented with lightweight highly sensitive pressure sensors. The paper presents the development of a new plain flexible thin pressure sensor using a nanostructured layer of the highly sensitive organic piezoresistive metal β-(BEDT-TTF) 2 I 3 as an active component; BEDT-TTF=bis (ethylenedithio)tetrathiafulvalene. The original construction approach permits one to operate the developed sensor on the principle of electrical resistance variations when its piezoresistive layer is elongated under a pressure increase. The pressure sensing element and a set of gold electrodes were integrated into one compact multi-layer design. The construction was optimized to enable one generic design for pressure ranges from 1 to 400 bar. The pressure tests showed that the sensor is able to control a small pressure change as a well definite electrical signal. So the developed type of the sensors is very attractive as a new generation of compact, lightweight, low-cost sensors that might monitor pressure with a good level of measurement accuracy. (paper)

  13. Recovery of ammonia and production of high-grade phosphates from side-stream digester effluents using gas-permeable membranes

    Phosphorus recovery was combined with ammonia recovery using gas-permeable membranes. In a first step, the ammonia and alkalinity were removed from municipal side-stream wastewater using low-rate aeration and a gas-permeable membrane manifold. In a second step, the phosphorus was removed using magne...

  14. Multifunctional high-reflective and antireflective layer systems with easy-to-clean properties

    Gloess, D.; Frach, P.; Gottfried, C.; Klinkenberg, S.; Liebig, J.-S.; Hentsch, W.; Liepack, H.; Krug, M.

    2008-01-01

    High-reflective (HR) and even more antireflective (AR) layer systems are in use for widespread applications. Multifunctional layer systems providing high optical functionality with an easy-to-clean or a self-cleaning behaviour would be preferable for many applications to avoid soiling of the surface. In this paper, the feasibility of fabrication by highly productive pulse magnetron sputtering in an in-line coating plant is investigated. Easy-to-clean properties are achieved by a top layer of photocatalytic and photoinduced hydrophilic TiO 2 . Multifunctional HR layer systems were successfully deposited on glass and polyethylene terephthalate (PET) substrates at a low deposition temperature of 150 deg. C, demonstrating the possibility of coating certain polymer materials. Double-sided multifunctional AR layer systems with a single-sided photoinduced hydrophilic TiO 2 top coating have a resulting reflectivity of about 3% and transmittance of about 97% in the visible range of light

  15. Multi-layer casing of a steam turbine for high steam pressures and temperatures

    Remberg, A.

    1978-01-01

    In previous turbine casings there is no sealing provided between the inner layer and the outer layer, so that the steam pressure acts fully on the casing top and on the shaft seal housing situated there. To reduce the displacement which occurs there due to pressure differences in the various steam spaces, the normal inner casing is made with the shaft sealing housing in an inner layer, which cannot be divided in the axial direction. The inner layer can be inserted from the high pressure side into the unit outer casing. A horizontal section through the turbine in the attached drawing makes the construction and operation of the invention clear. (GL) [de

  16. Direct measurements of air layer profiles under impacting droplets using high-speed color interferometry

    van der Veen, Roeland; Tran, Tuan; Lohse, Detlef; Sun, Chao

    2012-01-01

    A drop impacting on a solid surface deforms before the liquid makes contact with the surface. We directly measure the time evolution of the air layer profile under the droplet using high-speed color interferometry, obtaining the air layer thickness before and during the wetting process. Based on the

  17. A hierarchy of high-order theories for modes in an elastic layer

    Sorokin, Sergey V.; Chapman, C. John

    2015-01-01

    A hierarchy of high-order theories for symmetric and skew-symmetric modes in an infinitely long elastic layer of the constant thickness is derived. For each member of the hierarchy, boundary conditions for layers of the finite length are formulated. The forcing problems at several approximation...

  18. Compact rock material gas permeability properties

    Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

    2014-09-15

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens’ permeability evolution is related to the relative particle movements and microcrack closure.

  19. Surface Morphology Transformation Under High-Temperature Annealing of Ge Layers Deposited on Si(100).

    Shklyaev, A A; Latyshev, A V

    2016-12-01

    We study the surface morphology and chemical composition of SiGe layers after their formation under high-temperature annealing at 800-1100 °C of 30-150 nm Ge layers deposited on Si(100) at 400-500 °C. It is found that the annealing leads to the appearance of the SiGe layers of two types, i.e., porous and continuous. The continuous layers have a smoothened surface morphology and a high concentration of threading dislocations. The porous and continuous layers can coexist. Their formation conditions and the ratio between their areas on the surface depend on the thickness of deposited Ge layers, as well as on the temperature and the annealing time. The data obtained suggest that the porous SiGe layers are formed due to melting of the strained Ge layers and their solidification in the conditions of SiGe dewetting on Si. The porous and dislocation-rich SiGe layers may have properties interesting for applications.

  20. Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

    Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S

    2009-01-01

    In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

  1. Maglev performance of a double-layer bulk high temperature superconductor above a permanent magnet guideway

    Deng, Z; Wang, J; Zheng, J; Lin, Q; Zhang, Y; Wang, S [Applied Superconductivity Laboratory, Southwest Jiaotong University, Chengdu, 610031 (China)], E-mail: asclab@asclab.cn

    2009-05-15

    In order to improve the performance of the present high temperature superconducting (HTS) maglev vehicle system, the maglev performance of single- and double-layer bulk high temperature superconductors (HTSC) was investigated above a permanent magnet guideway (PMG). It is found that the maglev performance of a double-layer bulk HTSC is not a simple addition of each layer's levitation and guidance force. Moreover, the applied magnetic field at the position of the upper layer bulk HTSC is not completely shielded by the lower layer bulk HTSC either. 53.5% of the levitation force and 27.5% of the guidance force of the upper layer bulk HTSC are excited in the double-layer bulk HTSC arrangement in the applied field-cooling condition and working gap, bringing a corresponding improvement of 16.9% and 8.8% to the conventional single-layer bulk HTSC. The present research implies that the cost performance of upper layer bulk HTSC is a little low for the whole HTS maglev system.

  2. Measurement of relative permeability of fuel cell diffusion media

    Hussaini, I.S.; Wang, C.Y.

    2010-01-01

    Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions

  3. Permeabilidade a quente de refratários para revestimento de cubas eletrolíticas Hot permeability of refractories for aluminum electrolytic cells lining at high temperatures

    D. Y. Miyaji

    2007-03-01

    Full Text Available Na indústria do alumínio primário, um dos principais responsáveis pela deterioração do revestimento refratário nas cubas de redução eletrolítica é o ataque por banho criolítico com alta concentração de NaF, que penetra e reage com o refratário podendo, em condições extremas, causar a parada prematura de operação da cuba e grandes prejuízos econômicos. Baseando-se nos mais recentes estudos de caracterização de refratários para cubas, uma boa correlação tem sido encontrada entre a resistência à corrosão e a permeabilidade, a qual é calculada pela equação de Forchheimer para a obtenção das constantes k1 Darciana (efeito viscoso e k2 não Darciana (efeito inercial. Entretanto, na maioria das situações, as medidas da permeabilidade têm sido efetuadas à temperatura ambiente, embora o refratário em uso esteja a superior temperatura. Este trabalho visa avaliar como esta permeabilidade se altera em temperaturas de até 700 ºC buscando, assim, uma melhor correlação dos resultados com as condições reais de operação. Pretende-se também, investigar essa propriedade em refratários empregados no revestimento de cadinhos para o transporte de alumínio líquido, com o intuito de verificar a aplicabilidade da permeametria como uma ferramenta de caracterização desses materiais cujo interesse de aplicação e desenvolvimento tem sido cada vez maior.In the aluminium primary industry, one of the main causes for electrolytic cells lining deterioration is the chemical attack by high NaF content cryolitic bath, that penetrates and reacts with the refractory, shortening the cell’s service life and resulting great economic losses. Based on the most recent studies on characterization of alumino-silicate refractories for aluminum cell linings, a good correlation has been found between its chemical attack by molten fluorides and the permeability, which is calculated by Forchheimer’s equation in order to obtain the Darcian

  4. Soils - Mean Permeability

    Kansas Data Access and Support Center — This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The...

  5. Permeable pavement study (Edison)

    U.S. Environmental Protection Agency — While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types...

  6. WATER VAPOUR PERMEABILITY PROPERTIES OF CELLULAR WOOD MATERIAL AND CONDENSATION RISK OF COMPOSITE PANEL WALLS

    Janis IEJAVS

    2016-09-01

    Full Text Available Invention of light weight cellular wood material (CWM with a trade mark of Dendrolight is one of innovations in wood industry of the last decade. The aim of the research was to define the water vapour permeability properties of CWM and to analyse the condensation risk of various wall envelopes where solid wood cellular material is used. To determine the water vapour permeability of CWM, test samples were produced in the factory using routine production technology and tested according to the standard EN 12086:2014. Water vapour permeability factor (μ and other properties of six different configurations of CWM samples were determined. Using the experimental data the indicative influence of geometrical parameters such as lamella thickness, number of lamellas and material direction were investigated and evaluated. To study the condensation risk within the wall envelope containing CWM calculation method given in LVS EN ISO 13788:2012 was used. To ease the calculation process previously developed JavaScript calculation software that had only capability to calculate thermal transmittance was extended so that condensation risk in multi-layer composite walls can be analysed. Water vapour permeability factor in CWM is highly direction dependant. If parallel and perpendicular direction of CWM is compared the value of water vapour permeability factor can differentiate more than two times. Another significant factor for condensation risk analysis is overall thickness of CWM since it directly influences the equivalent air layer thickness. The influence of other factors such as lamella thickness, or groove depth is minor when water vapour permeability properties are compared. From the analysis of CWM performance in building envelope it can be concluded that uninsulated CWM panels used during winter months will pose the risk of condensation damage to structure, but the risk can be reduced or prevented if insulation layer is applied to the CWM panel wall

  7. Active Boundary Layer Control on a Highly Loaded Turbine Exit Case Profile

    Julia Kurz

    2018-03-01

    Full Text Available A highly loaded turbine exit guide vane with active boundary layer control was investigated experimentally in the High Speed Cascade Wind Tunnel at the University of the German Federal Armed Forces, Munich. The experiments include profile Mach number distributions, wake traverse measurements as well as boundary layer investigations with a flattened Pitot probe. Active boundary layer control by fluidic oscillators was applied to achieve improved performance in the low Reynolds number regime. Low solidity, which can be applied to reduce the number of blades, increases the risk of flow separation resulting in increased total pressure losses. Active boundary layer control is supposed to overcome these negative effects. The experiments show that active boundary layer control by fluidic oscillators is an appropriate way to suppress massive open separation bubbles in the low Reynolds number regime.

  8. High energy PIXE: A tool to characterize multi-layer thick samples

    Subercaze, A.; Koumeir, C.; Métivier, V.; Servagent, N.; Guertin, A.; Haddad, F.

    2018-02-01

    High energy PIXE is a useful and non-destructive tool to characterize multi-layer thick samples such as cultural heritage objects. In a previous work, we demonstrated the possibility to perform quantitative analysis of simple multi-layer samples using high energy PIXE, without any assumption on their composition. In this work an in-depth study of the parameters involved in the method previously published is proposed. Its extension to more complex samples with a repeated layer is also presented. Experiments have been performed at the ARRONAX cyclotron using 68 MeV protons. The thicknesses and sequences of a multi-layer sample including two different layers of the same element have been determined. Performances and limits of this method are presented and discussed.

  9. Layer-by-Layer Assembly of Polyelectrolyte Multilayer onto PET Fabric for Highly Tunable Dyeing with Water Soluble Dyestuffs

    Shili Xiao

    2017-12-01

    Full Text Available Poly(ethyleneterephthalate (PET is a multi-purpose and widely used synthetic polymer in many industrial fields because of its remarkable advantages such as low cost, light weight, high toughness and resistance to chemicals, and high abrasion resistance. However, PET suffers from poor dyeability due to its non-polar nature, benzene ring structure as well as high crystallinity. In this study, PET fabrics were firstly treated with an alkaline solution to produce carboxylic acid functional groups on the surface of the PET fabric, and then was modified by polyelectrolyte polymer through the electrostatic layer-by-layer self-assembly technology. The polyelectrolyte multilayer-deposited PET fabric was characterized using scanning electron microscopy SEM, contact angle, Fourier transform infrared (FTIR and X-ray photoelectron spectroscopy (XPS. The dyeability of PET fabrics before and after surface modification was systematically investigated. It showed that the dye-uptake of the polyelectrolyte multilayer-deposited PET fabric has been enhanced compared to that of the pristine PET fabric. In addition, its dyeability is strongly dependent on the surface property of the polyelectrolyte multilayer-deposited PET fabric and the properties of dyestuffs.

  10. Intestinal Permeability: The Basics

    Ingvar Bjarnason

    1995-01-01

    Full Text Available The authors review some of the more fundamental principles underlying the noninvasive assessment of intestinal permeability in humans, the choice of test markers and their analyses, and the practical aspects of test dose composition and how these can be changed to allow the specific assessment of regional permeability changes and other intestinal functions. The implications of increased intestinal permeability in the pathogenesis of human disease is discussed in relation to findings in patients with Crohn’s disease. A common feature of increased intestinal permeability is the development of a low grade enteropathy, and while quantitatively similar changes may be found in Crohn’s disease these seem to predict relapse of disease. Moreover, factors associated with relapse of Crohn’s disease have in common an action to increase intestinal permeability. While increased intestinal permeability does not seem to be important in the etiology of Crohn’s disease it may be a central mechanism in the clinical relapse of disease.

  11. Plasma resonance in anisotropic layered high-Tc superconductors

    Sakai, Shigeki; Pedersen, Niels Falsig

    1999-01-01

    The plasma resonance is described theoretically by the inductive coupling model for a large stacked Josephson-junction system such as the intrinsic Josephson-junction array in anisotropic high- T-c superconductors. Eigenmodes of the plasma oscillation are analytically described and a numerical...

  12. Surface sedimentation at permeable pavement systems

    Støvring, Jan; Dam, Torben; Jensen, Marina Bergen

    2018-01-01

    Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance of restorat......Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance...

  13. Scientific perspectives on extending the provision for waivers of in vivo bioavailability and bioequivalence studies for drug products containing high solubility-low permeability drugs (BCS-Class 3).

    Stavchansky, Salomon

    2008-06-01

    Recently, there has been increased interest in extending the provision for waivers of in vivo bioavailability and bioequivalence (BA-BE) studies that appeared in the guidance published by the Food and Drug Administration (FDA) (1) to pharmaceutical products containing Class 3 drugs (High solubility-Low Permeability). The extension of the Biopharmaceutics Classification System (BCS) to Class 3 drugs is meritorious because of its impact on public health policy considerations. The rate limiting step in the absorption of Class 3 drugs is the permeability through the intestinal membrane. This commentary will focus its attention on the scientific considerations which need to be examined to assess the risk and the benefit prior to granting a waiver of in vivo bioavailability and/or bioequivalence studies for Class 3 drugs. It will examine the forces affecting the interconnectivity of the neuronal, immunological and hormonal systems in the gastrointestinal tract that may affect its permeability and functionality. It will also challenge the assumption that in vitro dissolution and in vitro permeability studies in tissue cultures in the presence and absence of excipients are good predictors for in vivo dissolution and in vivo permeability which are at the heart of the BCS.

  14. High Resolution ground penetrating radar (GPR) measurements at the laboratory scale to model porosity and permeability in the Miami Limestone in South Florida.

    Mount, G. J.; Comas, X.

    2015-12-01

    Subsurface water flow within the Biscayne aquifer is controlled by the heterogeneous distribution of porosity and permeability in the karst Miami Limestone and the presence of numerous dissolution and mega-porous features. The dissolution features and other high porosity areas can create preferential flow paths and direct recharge to the aquifer, which may not be accurately conceptualized in groundwater flow models. As hydrologic conditions are undergoing restoration in the Everglades, understanding the distribution of these high porosity areas within the subsurface would create a better understanding of subsurface flow. This research utilizes ground penetrating radar to estimate the spatial variability of porosity and dielectric permittivity of the Miami Limestone at centimeter scale resolution at the laboratory scale. High frequency GPR antennas were used to measure changes in electromagnetic wave velocity through limestone samples under varying volumetric water contents. The Complex Refractive Index Model (CRIM) was then applied in order to estimate porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates ranged from 45.2-66.0% from the CRIM model and correspond well with estimates of porosity from analytical and digital image techniques. Dielectric permittivity values of the limestone solid phase ranged from 7.0 and 13.0, which are similar to values in the literature. This research demonstrates the ability of GPR to identify the cm scale spatial variability of aquifer properties that influence subsurface water flow which could have implications for groundwater flow models in the Biscayne and potentially other shallow karst aquifers.

  15. Plasma resonance and flux dynamics in layered high-Tc superconductors

    Pedersen, Niels Falsig; Sakai, S.

    2000-01-01

    Flux dynamics of layered high Tc superconductors are considered with special emphasis on the small oscillation modes. In particular we find the dispersion relation for the plasma modes and discuss the spectra to be observed in microwave experiments.......Flux dynamics of layered high Tc superconductors are considered with special emphasis on the small oscillation modes. In particular we find the dispersion relation for the plasma modes and discuss the spectra to be observed in microwave experiments....

  16. The Determination of Polyethylene Glycol in Untreated Urine Samples by High Performance Liquid Chromatography for Intestinal Permeability Studies

    Larsen, Elfinn; Pedersen, Walther Batsberg; Philipsen, E.

    1985-01-01

    Polyethylene glycol in urine samples has been investigated by high performance liquid chromatography. The molecular weights ranged from 634 to 1338. The urine samples were applied to the chromatographic system without any pre-treatment. For samples with a concentration of 0.2% polyethylene glycol...

  17. Characterization of composite high density polyethylene and layered zirconium phosphate

    Lino, Adan S.; Silva, Daniela F.; Mendes, Luis C.

    2011-01-01

    Zirconium phosphate (ZrP) (2 w%), synthesized by direct precipitation method, was used in the preparation of composite with high density polyethylene (HDPE), through extrusion processing in the molten state. Wide angle x-ray diffraction (WAXD), stress-strain mechanical analysis and scanning electron microscopy (SEM) techniques were used for ZrP, neat polymer and composite mechanical and morphologic characterization. Although there was a slight increase in the Young modulus, WAXD and SEM analysis showed that the intercalation of the HDPE matrix in the filler galleries did not occur, probably due to the insufficient lamellae spacing to intercalate the polymer chains. Then, a microcomposite was achieved. (author)

  18. Predictions and Experimental Microstructural Characterization of High Strain Rate Failure Modes in Layered Aluminum Composites

    Khanikar, Prasenjit

    Different aluminum alloys can be combined, as composites, for tailored dynamic applications. Most investigations pertaining to metallic alloy layered composites, however, have been based on quasi-static approaches. The dynamic failure of layered metallic composites, therefore, needs to be characterized in terms of strength, toughness, and fracture response. A dislocation-density based crystalline plasticity formulation, finite-element techniques, rational crystallographic orientation relations and a new fracture methodology were used to predict the failure modes associated with the high strain rate behavior of aluminum layered composites. Two alloy layers, a high strength alloy, aluminum 2195, and an aluminum alloy 2139, with high toughness, were modeled with representative microstructures that included precipitates, dispersed particles, and different grain boundary (GB) distributions. The new fracture methodology, based on an overlap method and phantom nodes, is used with a fracture criteria specialized for fracture on different cleavage planes. One of the objectives of this investigation, therefore, was to determine the optimal arrangements of the 2139 and 2195 aluminum alloys for a metallic layered composite that would combine strength, toughness and fracture resistance for high strain-rate applications. Different layer arrangements were investigated for high strain-rate applications, and the optimal arrangement was with the high toughness 2139 layer on the bottom, which provided extensive shear strain localization, and the high strength 2195 layer on the top for high strength resistance. The layer thickness of the bottom high toughness layer also affected the bending behavior of the roll-boned interface and the potential delamination of the layers. Shear strain localization, dynamic cracking and delamination were the mutually competing failure mechanisms for the layered metallic composite, and control of these failure modes can be optimized for high strain

  19. Atomic Layer Deposition of Chemical Passivation Layers and High Performance Anti-Reflection Coatings on Back-Illuminated Detectors

    Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Nikzad, Shouleh (Inventor)

    2014-01-01

    A back-illuminated silicon photodetector has a layer of Al2O3 deposited on a silicon oxide surface that receives electromagnetic radiation to be detected. The Al2O3 layer has an antireflection coating deposited thereon. The Al2O3 layer provides a chemically resistant separation layer between the silicon oxide surface and the antireflection coating. The Al2O3 layer is thin enough that it is optically innocuous. Under deep ultraviolet radiation, the silicon oxide layer and the antireflection coating do not interact chemically. In one embodiment, the silicon photodetector has a delta-doped layer near (within a few nanometers of) the silicon oxide surface. The Al2O3 layer is expected to provide similar protection for doped layers fabricated using other methods, such as MBE, ion implantation and CVD deposition.

  20. Magnetic properties evolution of a high permeability nanocrystalline FeCuNbSiB during thermal ageing

    Lekdim, Atef; Morel, Laurent; Raulet, Marie-Ange

    2017-07-01

    It is found to be one of the major issues while designing an aircraft, mass and volume have to be reduced in order to achieve energy efficiency. This leads to a high compactness of the electrical components which enables them to withstand at high temperatures. The magnetic components which are responsible for the electrical energy conversion, therefore exposed to high temperatures in working conditions. Their thermal ageing becomes a serious problem and deserves a particular attention. The FeCuNbSiB nanocrystalline materials have been selected for this ageing study because they are used in power electronic systems very frequently. The objective of the study is based on monitoring the magnetic characteristics under the condition of several continuous thermal ageing (100, 150, 200 and 240 °C). An important, experimental work of magnetic characterization is being done through a specific monitoring protocol and X-ray diffraction (XRD) along with magnetostriction measurements was carried out to support the study of the evolution of the anisotropy energies with aging. The latter is discussed in this paper to explain and give the hypothesis about the aging phenomena. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

  1. Tromboembolismo pulmonar masivo de alto riesgo asociado a foramen oval permeable High-risk massive pulmonary thromboembolism associated with patent foramen ovale

    Antonio Miranda

    2012-04-01

    Full Text Available La alta mortalidad de los pacientes con tromboembolismo pulmonar masivo de alto riesgo amerita un enfoque terapéutico enérgico e invasivo que incluya la embolectomía pulmonar quirúrgica en aquellos pacientes con contraindicación para trombolisis o trombolisis fallida. Describimos un caso de tromboembolismo pulmonar masivo de alto riesgo que recibió tratamiento quirúrgico en vez de trombolisis debido a que al momento del diagnóstico presentaba un trombo móvil a través de un foramen oval permeable con altísima posibilidad de embolismo paradójico arterial.High mortality rate associated with massive pulmonary embolism requires an aggressive invasive approach including surgical pulmonary embolectomy when thrombolytic therapy has failed or is contraindicated. We describe a case of high-risk massive pulmonary embolism who underwent surgical treatment due to the presence of a mobile intracardiac clot in a patent foramen ovale, and the possible risk of paradoxical arterial embolism.

  2. Polymeric nanoparticles for increased oral bioavailability and rapid absorption using celecoxib as a model of a low-solubility, high-permeability drug.

    Morgen, Michael; Bloom, Corey; Beyerinck, Ron; Bello, Akintunde; Song, Wei; Wilkinson, Karen; Steenwyk, Rick; Shamblin, Sheri

    2012-02-01

    To demonstrate drug/polymer nanoparticles can increase the rate and extent of oral absorption of a low-solubility, high-permeability drug. Amorphous drug/polymer nanoparticles containing celecoxib were prepared using ethyl cellulose and either sodium caseinate or bile salt. Nanoparticles were characterized using dynamic light scattering, transmission and scanning electron microscopy, and differential scanning calorimetry. Drug release and resuspension studies were performed using high-performance liquid chromatography. Pharmacokinetic studies were performed in dogs and humans. A physical model is presented describing the nanoparticle state of matter and release performance. Nanoparticles dosed orally in aqueous suspensions provided higher systemic exposure and faster attainment of peak plasma concentrations than commercial capsules, with median time to maximum drug concentration (Tmax) of 0.75 h in humans for nanoparticles vs. 3 h for commercial capsules. Nanoparticles released celecoxib rapidly and provided higher dissolved-drug concentrations than micronized crystalline drug. Nanoparticle suspensions are stable for several days and can be spray-dried to form dry powders that resuspend in water. Drug/polymer nanoparticles are well suited for providing rapid oral absorption and increased bioavailability of BCS Class II drugs.

  3. Reduced cerebral glucose metabolism and increased brain capillary permeability following high-dose methotrexate chemotherapy: a positron emission tomographic study

    Phillips, P.C.; Dhawan, V.; Strother, S.C.; Sidtis, J.J.; Evans, A.C.; Allen, J.C.; Rottenberg, D.A.

    1987-01-01

    Regional glucose metabolic rate constants and blood-to-brain transport of rubidium were estimated using positron emission tomography in an adolescent patient with a brain tumor, before and after chemotherapy with intravenous high-dose methotrexate. Widespread depression of cerebral glucose metabolism was apparent 24 hours after drug administration, which may reflect reduced glucose phosphorylation, and the influx rate constant for 82 Rb was increased, indicating a drug-induced alteration in blood-brain barrier function. Associated changes in neuropsychological performance, electroencephalogram, and plasma amino acid concentration were identified in the absence of evidence of systemic methotrexate toxicity, suggesting primary methotrexate neurotoxicity

  4. The use of reflective and permeable pavements as a potential practice for heat island mitigation and stormwater management

    Li, H; Harvey, J T; Holland, T J; Kayhanian, M

    2013-01-01

    To help address the built environmental issues of both heat island and stormwater runoff, strategies that make pavements cooler and permeable have been investigated through measurements and modeling of a set of pavement test sections. The investigation included the hydraulic and thermal performance of the pavements. The permeability results showed that permeable interlocking concrete pavers have the highest permeability (or infiltration rate, ∼0.5 cm s −1 ). The two permeable asphalt pavements showed the lowest permeability, but still had an infiltration rate of ∼0.1 cm s −1 , which is adequate to drain rainwater without generating surface runoff during most typical rain events in central California. An increase in albedo can significantly reduce the daytime high surface temperature in summer. Permeable pavements under wet conditions could give lower surface temperatures than impermeable pavements. The cooling effect highly depends on the availability of moisture near the surface layer and the evaporation rate. The peak cooling effect of watering for the test sections was approximately 15–35 °C on the pavement surface temperature in the early afternoon during summer in central California. The evaporative cooling effect on the pavement surface temperature at 4:00 pm on the third day (25 h after watering) was still 2–7 °C lower compared to that on the second day, without considering the higher air temperature on the third day. A separate and related simulation study performed by UCPRC showed that full depth permeable pavements, if designed properly, can carry both light-duty traffic and certain heavy-duty vehicles while retaining the runoff volume captured from an average California storm event. These preliminarily results indicated the technical feasibility of combined reflective and permeable pavements for addressing the built environment issues related to both heat island mitigation and stormwater runoff management. (letter)

  5. Detection and control of as-produced pyrocarbon permeability in biso-coated high-temperature gas-cooled reactor fuel particles

    Stinton, D.P.; Thiele, B.A.; Lackey, W.J.; Morgan, C.S.

    1980-05-01

    About 60 Biso-coated particle batches with coatings deposited in either 0.13- or 0.24-m dia coaters were studied in this work. These batches were carefully characterized for permeability by neon-helium intrusion, long-term chlorination followed by radiography, and fission gas release. These methods of permeability measurement were compared and correlated with deposition conditions as well as pyrocarbon properties. The results from several irradiation tests were also used to evaluate the validity of the permeability measurements. The neon-helium and long-term chlorination techniques correlated very clearly. Coatings with neon-to-helium ratios below 0.3 were gastight by the chlorination procedure, whereas those with ratios above 0.4 were permeable. The fission gas release technique was unable to distinguish between slightly permeable coatings and gastight ones. Therefore, neon-helium and long-term chlorination procedures are preferred over the fission gas release technique. Results from several irradiation tests verified that coatings with neon-to-helium ratios below 0.3 were gastight, whereas those with ratios above about 0.4 were permeable. 10 figures, 2 tables

  6. Layer-by-layer assembled highly absorbing hundred-layer films containing a phthalocyanine dye: Fabrication and photosensibilization by thermal treatment

    Sergeeva, Alena S.; Volkova, Elena K.; Bratashov, Daniil N.; Shishkin, Mikhail I.; Atkin, Vsevolod S.; Markin, Aleksey V.; Skaptsov, Aleksandr A.; Volodkin, Dmitry V.; Gorin, Dmitry A.

    2015-01-01

    Highly absorbing hundred-layer films based on poly(diallyldimethylammonium chloride) (PDADMAC) of various molecular weights and on sulfonated copper phthalocyanine (CuPcTs) were prepared using layer-by-layer assembly. The multilayer films grew linearly up to 54 bilayers, indicating that the same amount of CuPcTs was adsorbed at each deposition step. This amount, however, was dependent on the molecular weight of PDADMAC in the range 100-500 kDa: the higher the molecular weight, the more CuPcTs molecules were adsorbed. This can be explained by the larger surface charge number density specific to longer polymer chains. Domains of pure PDADMAC and of the PDADMAC/CuPcTs complex were formed in the films during the assembly. Uniform distribution of CuPcTs over the films could be achieved by thermal treatment, leading to an α → β phase transition in phthalocyanine at 300 °C. Annealing caused changes in the film absorbance spectra, resulting in a 30-nm red shift of the peak maxima and in a strong (up to 62%) decrease in optical density. Thermogravimetric analysis revealed thermodegradation of PDADMAC during annealing above 270 °C, giving rise to micrometer-sized cracks within the films, as evidenced by scanning electron microscopy. - Highlights: • The films exhibit the linear dependence of the adsorption on the bilayer number varied from 2 until 54. • Polyelectrolyte of the highest MW shows the maximal adsorption of copper phthalocyanine molecules. • Annealing of the films causes a red-shift of the maxima in the absorbance spectra. • Cracks and micropores emerged in the multilayer films during the annealing

  7. Pt–Al2O3 dual layer atomic layer deposition coating in high aspect ratio nanopores

    Pardon, Gaspard; Gatty, Hithesh K; Stemme, Göran; Wijngaart, Wouter van der; Roxhed, Niclas

    2013-01-01

    Functional nanoporous materials are promising for a number of applications ranging from selective biofiltration to fuel cell electrodes. This work reports the functionalization of nanoporous membranes using atomic layer deposition (ALD). ALD is used to conformally deposit platinum (Pt) and aluminum oxide (Al 2 O 3 ) on Pt in nanopores to form a metal–insulator stack inside the nanopore. Deposition of these materials inside nanopores allows the addition of extra functionalities to nanoporous materials such as anodic aluminum oxide (AAO) membranes. Conformal deposition of Pt on such materials enables increased performances for electrochemical sensing applications or fuel cell electrodes. An additional conformal Al 2 O 3 layer on such a Pt film forms a metal–insulator–electrolyte system, enabling field effect control of the nanofluidic properties of the membrane. This opens novel possibilities in electrically controlled biofiltration. In this work, the deposition of these two materials on AAO membranes is investigated theoretically and experimentally. Successful process parameters are proposed for a reliable and cost-effective conformal deposition on high aspect ratio three-dimensional nanostructures. A device consisting of a silicon chip supporting an AAO membrane of 6 mm diameter and 1.3 μm thickness with 80 nm diameter pores is fabricated. The pore diameter is reduced to 40 nm by a conformal deposition of 11 nm Pt and 9 nm Al 2 O 3 using ALD. (paper)

  8. Pt-Al{sub 2}O{sub 3} dual layer atomic layer deposition coating in high aspect ratio nanopores

    Pardon, Gaspard; Gatty, Hithesh K; Stemme, Goeran; Wijngaart, Wouter van der; Roxhed, Niclas [KTH Royal Institute of Technology, School of Electrical Engineering, Micro and Nanosystems, Osquldas Vaeg 10, SE-10044 Stockholm (Sweden)

    2013-01-11

    Functional nanoporous materials are promising for a number of applications ranging from selective biofiltration to fuel cell electrodes. This work reports the functionalization of nanoporous membranes using atomic layer deposition (ALD). ALD is used to conformally deposit platinum (Pt) and aluminum oxide (Al{sub 2}O{sub 3}) on Pt in nanopores to form a metal-insulator stack inside the nanopore. Deposition of these materials inside nanopores allows the addition of extra functionalities to nanoporous materials such as anodic aluminum oxide (AAO) membranes. Conformal deposition of Pt on such materials enables increased performances for electrochemical sensing applications or fuel cell electrodes. An additional conformal Al{sub 2}O{sub 3} layer on such a Pt film forms a metal-insulator-electrolyte system, enabling field effect control of the nanofluidic properties of the membrane. This opens novel possibilities in electrically controlled biofiltration. In this work, the deposition of these two materials on AAO membranes is investigated theoretically and experimentally. Successful process parameters are proposed for a reliable and cost-effective conformal deposition on high aspect ratio three-dimensional nanostructures. A device consisting of a silicon chip supporting an AAO membrane of 6 mm diameter and 1.3 {mu}m thickness with 80 nm diameter pores is fabricated. The pore diameter is reduced to 40 nm by a conformal deposition of 11 nm Pt and 9 nm Al{sub 2}O{sub 3} using ALD. (paper)

  9. Pt-Al2O3 dual layer atomic layer deposition coating in high aspect ratio nanopores

    Pardon, Gaspard; Gatty, Hithesh K.; Stemme, Göran; van der Wijngaart, Wouter; Roxhed, Niclas

    2013-01-01

    Functional nanoporous materials are promising for a number of applications ranging from selective biofiltration to fuel cell electrodes. This work reports the functionalization of nanoporous membranes using atomic layer deposition (ALD). ALD is used to conformally deposit platinum (Pt) and aluminum oxide (Al2O3) on Pt in nanopores to form a metal-insulator stack inside the nanopore. Deposition of these materials inside nanopores allows the addition of extra functionalities to nanoporous materials such as anodic aluminum oxide (AAO) membranes. Conformal deposition of Pt on such materials enables increased performances for electrochemical sensing applications or fuel cell electrodes. An additional conformal Al2O3 layer on such a Pt film forms a metal-insulator-electrolyte system, enabling field effect control of the nanofluidic properties of the membrane. This opens novel possibilities in electrically controlled biofiltration. In this work, the deposition of these two materials on AAO membranes is investigated theoretically and experimentally. Successful process parameters are proposed for a reliable and cost-effective conformal deposition on high aspect ratio three-dimensional nanostructures. A device consisting of a silicon chip supporting an AAO membrane of 6 mm diameter and 1.3 μm thickness with 80 nm diameter pores is fabricated. The pore diameter is reduced to 40 nm by a conformal deposition of 11 nm Pt and 9 nm Al2O3 using ALD.

  10. Layered Cu-based electrode for high-dielectric constant oxide thin film-based devices

    Fan, W.; Saha, S.; Carlisle, J.A.; Auciello, O.; Chang, R.P.H.; Ramesh, R.

    2003-01-01

    Ti-Al/Cu/Ta multilayered electrodes were fabricated on SiO 2 /Si substrates by ion beam sputtering deposition, to overcome the problems of Cu diffusion and oxidation encountered during the high dielectric constant (κ) materials integration. The Cu and Ta layers remained intact through the annealing in oxygen environment up to 600 deg. C. The thin oxide layer, formed on the Ti-Al surface, effectively prevented the oxygen penetration toward underneath layers. Complex oxide (Ba x Sr 1-x )TiO 3 (BST) thin films were grown on the layered Ti-Al/Cu/Ta electrodes using rf magnetron sputtering. The deposited BST films exhibited relatively high permittivity (150), low dielectric loss (0.007) at zero bias, and low leakage current -8 A/cm 2 at 100 kV/cm

  11. The TRPC1 Ca2+-permeable channel inhibits exercise-induced protection against high-fat diet-induced obesity and type II diabetes.

    Krout, Danielle; Schaar, Anne; Sun, Yuyang; Sukumaran, Pramod; Roemmich, James N; Singh, Brij B; Claycombe-Larson, Kate J

    2017-12-15

    The transient receptor potential canonical channel-1 (TRPC1) is a Ca 2+ -permeable channel found in key metabolic organs and tissues, including the hypothalamus, adipose tissue, and skeletal muscle. Loss of TRPC1 may alter the regulation of cellular energy metabolism resulting in insulin resistance thereby leading to diabetes. Exercise reduces insulin resistance, but it is not known whether TRPC1 is involved in exercise-induced insulin sensitivity. The role of TRPC1 in adiposity and obesity-associated metabolic diseases has not yet been determined. Our results show that TRPC1 functions as a major Ca 2+ entry channel in adipocytes. We have also shown that fat mass and fasting glucose concentrations were lower in TRPC1 KO mice that were fed a high-fat (HF) (45% fat) diet and exercised as compared with WT mice fed a HF diet and exercised. Adipocyte numbers were decreased in both subcutaneous and visceral adipose tissue of TRPC1 KO mice fed a HF diet and exercised. Finally, autophagy markers were decreased and apoptosis markers increased in TRPC1 KO mice fed a HF diet and exercised. Overall, these findings suggest that TRPC1 plays an important role in the regulation of adiposity via autophagy and apoptosis and that TRPC1 inhibits the positive effect of exercise on type II diabetes risk under a HF diet-induced obesity environment.

  12. Biostable glucose permeable polymer

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  13. Transformable ferroelectric control of dynamic magnetic permeability

    Jiang, Changjun; Jia, Chenglong; Wang, Fenglong; Zhou, Cai; Xue, Desheng

    2018-02-01

    Magnetic permeability, which measures the response of a material to an applied magnetic field, is crucial to the performance of magnetic devices and related technologies. Its dynamic value is usually a complex number with real and imaginary parts that describe, respectively, how much magnetic power can be stored and lost in the material. Control of permeability is therefore closely related to energy redistribution within a magnetic system or energy exchange between magnetic and other degrees of freedom via certain spin-dependent interactions. To avoid a high power consumption, direct manipulation of the permeability with an electric field through magnetoelectric coupling leads to high efficiency and simple operation, but remains a big challenge in both the fundamental physics and material science. Here we report unambiguous evidence of ferroelectric control of dynamic magnetic permeability in a Co /Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (Co/PMN-PT) heterostructure, in which the ferroelectric PMN-PT acts as an energy source for the ferromagnetic Co film via an interfacial linear magnetoelectric interaction. The electric field tuning of the magnitude and line shape of the permeability offers a highly localized means of controlling magnetization with ultralow power consumption. Additionally, the emergence of negative permeability promises a new way of realizing functional nanoscale metamaterials with adjustable refraction index.

  14. Simple single-emitting layer hybrid white organic light emitting with high color stability

    Nguyen, C.; Lu, Z. H.

    2017-10-01

    Simultaneously achieving a high efficiency and color quality at luminance levels required for solid-state lighting has been difficult for white organic light emitting diodes (OLEDs). Single-emitting layer (SEL) white OLEDs, in particular, exhibit a significant tradeoff between efficiency and color stability. Furthermore, despite the simplicity of SEL white OLEDs being its main advantage, the reported device structures are often complicated by the use of multiple blocking layers. In this paper, we report a highly simplified three-layered white OLED that achieves a low turn-on voltage of 2.7 V, an external quantum efficiency of 18.9% and power efficiency of 30 lm/W at 1000 cd/cm2. This simple white OLED also shows good color quality with a color rendering index of 75, CIE coordinates (0.42, 0.46), and little color shifting at high luminance. The device consists of a SEL sandwiched between a hole transport layer and an electron transport layer. The SEL comprises a thermally activated delayer fluorescent molecule having dual functions as a blue emitter and as a host for other lower energy emitters. The improved color stability and efficiency in such a simple device structure is explained as due to the elimination of significant energy barriers at various organic-organic interfaces in the traditional devices having multiple blocking layers.

  15. Experimental Investigation of Surface Layer Properties of High Thermal Conductivity Tool Steel after Electrical Discharge Machining

    Rafał Świercz

    2017-12-01

    Full Text Available New materials require the use of advanced technology in manufacturing complex shape parts. One of the modern materials widely used in the tool industry for injection molds or hot stamping dies is high conductivity tool steel (HTCS 150. Due to its hardness (55 HRC and thermal conductivity at 66 W/mK, this material is difficult to machine by conventional treatment and is being increasingly manufactured by nonconventional technology such as electrical discharge machining (EDM. In the EDM process, material is removed from the workpiece by a series of electrical discharges that cause changes to the surface layers properties. The final state of the surface layer directly influences the durability of the produced elements. This paper presents the influence of EDM process parameters: discharge current Ic and the pulse time ton on surface layer properties. The experimental investigation was carried out with an experimental methodology design. Surface layers properties including roughness 3D parameters, the thickness of the white layer, heat affected zone, tempered layer and occurring micro cracks were investigated and described. The influence of the response surface methodology (RSM of discharge current Ic and the pulse time ton on the thickness of the white layer and roughness parameters Sa, Sds and Ssc were described and established.

  16. Stationary and Dynamic Permeability and Coupling Coefficient Measurements in Sintered Glass Bead Systems

    Gueven, I.; Steeb, H.; Luding, S.

    2014-12-01

    Electrokinetic waves describe the coupling between seismic and electromagnetic waves that exist in porous media. The coupling between them arise from an electrochemical boundary layer between grain and fluid interface of saturated porous media. Acoustical waves cause a disturbance of the electrical fluid charge within the double layer, which therefore creates an electric streaming current (seismoelectric effect). Inversely, electromagnetic waves can generate mechanical signals (electroseismic effect). Electrokinetic conversion potentially combines high seismic resolution with good electromagnetic hydrocarbon sensitivity. The (stationary and frequency-dependent) streaming potential coefficient is a key property, which gives rise to the coupling between electromagnetic and acoustical waves. It depends strongly on the fluid conductivity, porosity, tortuosity, permeability, pore throat and zeta potential of porous media. We examine experimentally both, the stationary and dynamic permeabilities and coupling coefficients of sintered glass bead systems. For this purpose a multi-purpose measuring cell was developed which allows us to carry out - besides common ultrasound experiments - also to perform stationary and frequency-dependent permeability and coupling coefficient measurements. For the experiments sintered mono- and slightly polydisperse glass bead samples with different glass bead diameters between 0.4 and 8mm and porosities ranging between 21 and 39% were used. The stationary and dynamic permeability and streaming potential measurements are supported by μCT scans which enable us a deeper insight into the porous medium. Based on the μCT scans of the produced sintered glass bead samples essential influence parameters, like tortuosity, porosity, effective particle diameters and pore throats in different regions of the entire scanned region have been analyzed in detail to understand the laboratory experiments, cf. Illustration 1. In addition lattice Boltzmann

  17. Effects of thin high-Z layers on the hydrodynamics of laser-accelerated plastic targets

    Obenschain, S.P.; Colombant, D.G.; Karasik, M.; Pawley, C.J.; Serlin, V.; Schmitt, A.J.; Weaver, J.L.; Gardner, J.H.; Phillips, L.; Aglitskiy, Y.; Chan, Y.; Dahlburg, J.P.; Klapisch, M.

    2002-01-01

    Experimental results and simulations that study the effects of thin metallic layers with high atomic number (high-Z) on the hydrodynamics of laser accelerated plastic targets are presented. These experiments employ a laser pulse with a low-intensity foot that rises into a high-intensity main pulse. This pulse shape simulates the generic shape needed for high-gain fusion implosions. Imprint of laser nonuniformity during start up of the low intensity foot is a well-known seed for hydrodynamic instability. Large reductions are observed in hydrodynamic instability seeded by laser imprint when certain minimum thickness gold or palladium layers are applied to the laser-illuminated surface of the targets. The experiment indicates that the reduction in imprint is at least as large as that obtained by a 6 times improvement in the laser uniformity. Simulations supported by experiments are presented showing that during the low intensity foot the laser light can be nearly completely absorbed by the high-Z layer. X rays originating from the high-Z layer heat the underlying lower-Z plastic target material and cause large buffering plasma to form between the layer and the accelerated target. This long-scale plasma apparently isolates the target from laser nonuniformity and accounts for the observed large reduction in laser imprint. With onset of the higher intensity main pulse, the high-Z layer expands and the laser light is transmitted. This technique will be useful in reducing laser imprint in pellet implosions and thereby allow the design of more robust targets for high-gain laser fusion

  18. Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

    Marr, Michael; Kesler, Olivera

    2012-12-01

    Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

  19. Atomic layer deposition for high-efficiency crystalline silicon solar cells

    Macco, B.; van de Loo, B.W.H.; Kessels, W.M.M.; Bachmann, J.

    2017-01-01

    This chapter illustrates that Atomic Layer Deposition (ALD) is in fact an enabler of novel high-efficiency Si solar cells, owing to its merits such as a high material quality, precise thickness control, and the ability to prepare film stacks in a well-controlled way. It gives an overview of the

  20. Far scrape-off layer particle and heat fluxes in high density

    Müller, H. W.; Bernert, M.; Carralero, D.

    2014-01-01

    The far scrape-off layer transport is studied in ASDEX Upgrade H-mode discharges with high divertor neutral density N0,div, high power across the separatrix Psep and nitrogen seeding to control the divertor temperature. Such conditions are expected for ITER but usually not investigated in terms...

  1. Cell permeability beyond the rule of 5.

    Matsson, Pär; Doak, Bradley C; Over, Björn; Kihlberg, Jan

    2016-06-01

    Drug discovery for difficult targets that have large and flat binding sites is often better suited to compounds beyond the "rule of 5" (bRo5). However, such compounds carry higher pharmacokinetic risks, such as low solubility and permeability, and increased efflux and metabolism. Interestingly, recent drug approvals and studies suggest that cell permeable and orally bioavailable drugs can be discovered far into bRo5 space. Tactics such as reduction or shielding of polarity by N-methylation, bulky side chains and intramolecular hydrogen bonds may be used to increase cell permeability in this space, but often results in decreased solubility. Conformationally flexible compounds can, however, combine high permeability and solubility, properties that are keys for cell permeability and intestinal absorption. Recent developments in computational conformational analysis will aid design of such compounds and hence prediction of cell permeability. Transporter mediated efflux occurs for most investigated drugs in bRo5 space, however it is commonly overcome by high local intestinal concentrations on oral administration. In contrast, there is little data to support significant impact of transporter-mediated intestinal absorption in bRo5 space. Current knowledge of compound properties that govern transporter effects of bRo5 drugs is limited and requires further fundamental and comprehensive studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. High-temperature adsorption layers based on fluoridated polyimide and diatomite carrier

    Yakovleva, E. Yu.; Shundrina, I. K.; Gerasimov, E. Yu.

    2017-09-01

    A way of preparing separation layers by the pyrolysis of fluorinated polyimide obtained from 2,4,6-trimethyl- m-phenylenediamine (2,4,6-TM mPDA) and 2,2-bis(3',4'-dicarboxyphenyl)hexafluoropropane (6FDA) applied onto a diatomite carrier is described. Thermogravimetry, elemental analysis, low-temperature nitrogen adsorption, high-resolution electron microscopy, and gas chromatography are used to study changes in the texture and chromatographic characteristics of these layers. It is found that changes in the structure and the effectivity of separation characteristic of the layers depend on the temperature of pyrolysis, which ranges from 250 to 1100°C. It is established that a layer of separation is formed at 250-350°C, and the order of elution of hydrocarbons is similar to their chromatographic behavior on such stationary phases as OV-101. Layers of amorphous carbon formed on the surfaces of individual particles on a diatomite surface at 500-700°C. These layers ensure highly stable and selective separation of permanent gases and hydrocarbons when they are present together.

  3. Very high coercivities of top-layer diffusion Au/FePt thin films

    Yuan, F.T.; Chen, S.K.; Liao, W.M.; Hsu, C.W.; Hsiao, S.N.; Chang, W.C.

    2006-01-01

    The Au/FePt samples were prepared by depositing a gold cap layer at room temperature onto a fully ordered FePt layer, followed by an annealing at 800 deg. C for the purpose of interlayer diffusion. After the deposition of the gold layer and the high-temperature annealing, the gold atoms do not dissolve into the FePt Ll 0 lattice. Compared with the continuous FePt film, the TEM photos of the bilayer Au(60 nm)/FePt(60 nm) show a granular structure with FePt particles embedded in Au matrix. The coercivity of Au(60 nm)/FePt(60 nm) sample is 23.5 kOe, which is 85% larger than that of the FePt film without Au top layer. The enhancement in coercivity can be attributed to the formation of isolated structure of FePt ordered phase

  4. Layered titanium disilicide stabilized by oxide coating for highly reversible lithium insertion and extraction.

    Zhou, Sa; Simpson, Zachary I; Yang, Xiaogang; Wang, Dunwei

    2012-09-25

    The discovery of new materials has played an important role in battery technology development. Among the newly discovered materials, those with layered structures are often of particular interest because many have been found to permit highly repeatable ionic insertion and extraction. Examples include graphite and LiCoO(2) as anode and cathode materials, respectively. Here we report C49 titanium disilicide (TiSi(2)) as a new layered anode material, within which lithium ions can react with the Si-only layers. This result is enabled by the strategy of coating a thin (lithium-ion storage capacity of TiSi(2) is a result of its layered structure is expected to have major fundamental and practical implications.

  5. Preparation of a Highly Conductive Seed Layer for Calcium Sensor Fabrication with Enhanced Sensing Performance

    Ahmad, Rafiq

    2018-03-16

    The seed layer plays a crucial role in achieving high electrical conductivity and ensuring higher performance of devices. In this study, we report fabrication of a solution-gated field-effect transistor (FET) sensor based on zinc oxide nanorods (ZnO NRs) modified iron oxide nanoparticles (α-FeO NPs) grown on a highly conductive sandwich-like seed layer (ZnO seed layer/Ag nanowires/ZnO seed layer). The sandwich-like seed layer and ZnO NRs modification with α-FeO NPs provide excellent conductivity and prevent possible ZnO NRs surface damage from low pH enzyme immobilization, respectively. The highly conductive solution-gated FET sensor employed the calmodulin (CaM) immobilization on the surface of α-FeO-ZnO NRs for selective detection of calcium ions (Ca). The solution-gated FET sensor exhibited a substantial change in conductance upon introduction of different concentrations of Ca and showed high sensitivity (416.8 μA cm mM) and wide linear range (0.01-3.0 mM). In addition, the total Ca concentration in water and serum samples was also measured. Compared to the analytically obtained data, our sensor was found to measure Ca in the water and serum samples accurately, suggesting a potential alternative for Ca determination in water and serum samples, specifically used for drinking/irrigation and clinical analysis.

  6. Layer-by-layer assembled polyaniline nanofiber/multiwall carbon nanotube thin film electrodes for high-power and high-energy storage applications.

    Hyder, Md Nasim; Lee, Seung Woo; Cebeci, Fevzi Ç; Schmidt, Daniel J; Shao-Horn, Yang; Hammond, Paula T

    2011-11-22

    Thin film electrodes of polyaniline (PANi) nanofibers and functionalized multiwall carbon nanotubes (MWNTs) are created by layer-by-layer (LbL) assembly for microbatteries or -electrochemical capacitors. Highly stable cationic PANi nanofibers, synthesized from the rapid aqueous phase polymerization of aniline, are assembled with carboxylic acid functionalized MWNT into LbL films. The pH-dependent surface charge of PANi nanofibers and MWNTs allows the system to behave like weak polyelectrolytes with controllable LbL film thickness and morphology by varying the number of bilayers. The LbL-PANi/MWNT films consist of a nanoscale interpenetrating network structure with well developed nanopores that yield excellent electrochemical performance for energy storage applications. These LbL-PANi/MWNT films in lithium cell can store high volumetric capacitance (~238 ± 32 F/cm(3)) and high volumetric capacity (~210 mAh/cm(3)). In addition, rate-dependent galvanostatic tests show LbL-PANi/MWNT films can deliver both high power and high energy density (~220 Wh/L(electrode) at ~100 kW/L(electrode)) and could be promising positive electrode materials for thin film microbatteries or electrochemical capacitors. © 2011 American Chemical Society

  7. The surface layer observed by a high-resolution sodar at DOME C, Antarctica

    Stefania Argentini

    2014-01-01

    Full Text Available One year field experiment has started on December 2011 at the French - Italian station of Concordia at Dome C, East Antarctic Plateau. The objective of the experiment is the study of the surface layer turbulent processes under stable/very stable stratifications, and the mechanisms leading to the formation of the warming events. A sodar was improved to achieve the vertical/time resolution needed to study these processes. The system, named Surface Layer sodar (SL-sodar, may operate both in high vertical resolution (low range and low vertical resolution (high range modes. In situ turbulence and radiation measurements were also provided in the framework of this experiment. A few preliminary results, concerning the standard summer diurnal cycle, a summer warming event, and unusually high frequency boundary layer atmospheric gravity waves are presented.

  8. Sensitivity of boundary-layer stability to base-state distortions at high Mach numbers

    Park, Junho; Zaki, Tamer

    2017-11-01

    The stability diagram of high-speed boundary layers has been established by evaluating the linear instability modes of the similarity profile, over wide ranges of Reynolds and Mach numbers. In real flows, however, the base state can deviate from the similarity profile. Both the base velocity and temperature can be distorted, for example due to roughness and thermal wall treatments. We review the stability problem of high-speed boundary layer, and derive a new formulation of the sensitivity to base-state distortion using forward and adjoint parabolized stability equations. The new formulation provides qualitative and quantitative interpretations on change in growth rate due to modifications of mean-flow and mean-temperature in heated high-speed boundary layers, and establishes the foundation for future control strategies. This work has been funded by the Air Force Office of Scientific Research (AFOSR) Grant: FA9550-16-1-0103.

  9. Sialic acid (SA)-modified selenium nanoparticles coated with a high blood-brain barrier permeability peptide-B6 peptide for potential use in Alzheimer's disease.

    Yin, Tiantian; Yang, Licong; Liu, Yanan; Zhou, Xianbo; Sun, Jing; Liu, Jie

    2015-10-01

    The blood-brain barrier (BBB) is a formidable gatekeeper toward exogenous substances, playing an important role in brain homeostasis and maintaining a healthy microenvironment for complex neuronal activities. However, it also greatly hinders drug permeability into the brain and limits the management of brain diseases. The development of new drugs that show improved transport across the BBB represents a promising strategy for Alzheimer's disease (AD) intervention. Whereas, previous study of receptor-mediated endogenous BBB transport systems has focused on a strategy of using transferrin to facilitate brain drug delivery system, a system that still suffers from limitations including synthesis procedure, stability and immunological response. In the present study, we synthetised sialic acid (SA)-modified selenium (Se) nanoparticles conjugated with an alternative peptide-B6 peptide (B6-SA-SeNPs, a synthetic selenoprotein analogue), which shows high permeability across the BBB and has the potential to serve as a novel nanomedicine for disease modification in AD. Laser-scanning confocal microscopy, flow cytometry analysis and inductively coupled plasma-atomic emission spectroscopy ICP-AES revealed high cellular uptake of B6-SA-SeNPs by cerebral endothelial cells (bEnd.3). The transport efficiency of B6-SA-SeNPs was evaluated in a Transwell experiment based on in vitro BBB model. It provided direct evidence for B6-SA-SeNPs crossing the BBB and being absorbed by PC12 cells. Moreover, inhibitory effects of B6-SA-SeNPs on amyloid-β peptide (Aβ) fibrillation could be demonstrated in PC12 cells and bEnd3 cells. B6-SA-SeNPs could not only effectively inhibit Aβ aggregation but could disaggregate preformed Aβ fibrils into non-toxic amorphous oligomers. These results suggested that B6-SA-SeNPs may provide a promising platform, particularly for the application of nanoparticles in the treatment of brain diseases. Alzheimer's disease (AD) is the world's most common form of

  10. Pulsed EM Field Response of a Thin, High-Contrast, Finely Layered Structure With Dielectric and Conductive Properties

    De Hoop, A.T.; Jiang, L.

    2009-01-01

    The response of a thin, high-contrast, finely layered structure with dielectric and conductive properties to an incident, pulsed, electromagnetic field is investigated theoretically. The fine layering causes the standard spatial discretization techniques to solve Maxwell's equations numerically to

  11. Wear resistance of layers hard faced by the high-alloyed filler metal

    Dušan Arsić; Vukić Lazić; Ruzica R. Nikolic; Milan Mutavdžić; Srbislav Aleksandrović; Milan Djordjević

    2016-01-01

    The objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by ...

  12. A high-latitude, low-latitude boundary layer model of the convection current system

    Siscoe, G.L.; Lotko, W.; Sonnerup, B.U.O.

    1991-01-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer (∼1000 km), whereas thicknesses inferred from satellite data tend to be greater

  13. An Experimental Study of Micron-Size Zero-Valent Iron Emplacement in Permeable Porous Media Using Polymer-Enhanced Fluids

    Oostrom, Mart; Wietsma, Thomas W.; Covert, Matthew A.; Vermeul, Vince R.

    2005-12-22

    At the Hanford Site, an extensive In Situ Redox Manipulation (ISRM) permeable reactive barrier was installed to prevent chromate from reaching the Columbia River. However, chromium has been detected in several wells, indicating a premature loss of the reductive capacity in the aquifer. One possible cause for premature chromate breakthrough is associated with the presence of high-permeability zones in the aquifer. In these zones, groundwater moves relatively fast and is able to oxidize iron more rapidly. There is also a possibility that the high-permeability flow paths are deficient in reducing equivalents (e.g. reactive iron), required for barrier performance. One way enhancement of the current barrier reductive capacity can be achieved is by the addition of micron-scale zero-valent iron to the high-permeability zones within the aquifer. The potential emplacement of zero-valent iron (Fe0) into high-permeability Hanford sediments (Ringold Unit E gravels) using shear-thinning fluids containing polymers was investigated in three-dimensional wedge-shaped aquifer models. Polymers were used to create a suspension viscous enough to keep the Fe0 in solution for extended time periods to improve colloid movement into the porous media without causing a permanent detrimental decrease in hydraulic conductivity. Porous media were packed in the wedge-shaped flow cell to create either a heterogeneous layered system with a high-permeability zone in between two low-permeability zones or a high-permeability channel surrounded by low-permeability materials. The injection flow rate, polymer type, polymer concentration, and injected pore volumes were determined based on preliminary short- and long-column experiments.

  14. Highly efficient white organic light-emitting devices consisting of undoped ultrathin yellow phosphorescent layer

    Liu, Shengqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Ma, Zhu; Zhao, Juan [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2013-02-15

    High-efficiency white organic light-emitting devices (WOLEDs) based on an undoped ultrathin yellow light-emitting layer and a doped blue light-emitting layer were demonstrated. While the thickness of blue light-emitting layer, formed by doping a charge-trapping phosphor, iridium(III) bis(4 Prime ,6 Prime -difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) in a wide bandgap host, was kept constant, the thickness of neat yellow emissive layer of novel phosphorescent material, bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2 Prime }]iridium (acetylacetonate) [(t-bt){sub 2}Ir(acac)] was varied to optimize the device performance. The optimized device exhibited maximum luminance, current efficiency and power efficiency of 24,000 cd/m{sup 2} (at 15.2 V), 79.0 cd/A (at 1550 cd/m{sup 2}) and 40.5 lm/W (at 1000 cd/m{sup 2}), respectively. Besides, the white-light emission covered a wide range of visible spectrum, and the Commission Internationale de l'Eclairage coordinates were (0.32, 0.38) with a color temperature of 5800 K at 8 V. Moreover, high external quantum efficiency was also obtained in the high-efficiency WOLEDs. The performance enhancement was attributed to the proper thickness of (t-bt){sub 2}Ir(acac) layer that enabled adequate current density and enough phosphorescent dye to trap electrons. - Highlights: Black-Right-Pointing-Pointer Highly efficient WOLEDs based on two complementary layers were fabricated. Black-Right-Pointing-Pointer The yellow emissive layer was formed by utilizing undoping system. Black-Right-Pointing-Pointer The blue emissive layer was made by host-guest doping system. Black-Right-Pointing-Pointer The thickness of the yellow emissive layer was varied to make device optimization. Black-Right-Pointing-Pointer The optimized device achieved high power efficiency of 40.5 lm/W.

  15. Negative permeability from random particle composites

    Hussain, Shahid, E-mail: shussain2@qinetiq.com

    2017-04-15

    Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies. - Highlights: • Negative permeability from random particle composites is

  16. Ambient Layer-by-Layer ZnO Assembly for Highly Efficient Polymer Bulk Heterojunction Solar Cells

    Eita, Mohamed Samir; El Labban, Abdulrahman; Cruciani, Federico; Usman, Anwar; Beaujuge, Pierre; Mohammed, Omar F.

    2015-01-01

    The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in fl exible devices. Here, a layer-by-layer (LbL) protocol is reported as a facile, room

  17. Stratigraphy of the north polar layered deposits of Mars from high-resolution topography

    Becerra, Patricio; Byrne, Shane; Sori, Michael M.; Sutton, Sarah; Herkenhoff, Kenneth E.

    2016-01-01

    The stratigraphy of the layered deposits of the polar regions of Mars is theorized to contain a record of recent climate change linked to insolation changes driven by variations in the planet's orbital and rotational parameters. In order to confidently link stratigraphic signals to insolation periodicities, a description of the stratigraphy is required based on quantities that directly relate to intrinsic properties of the layers. We use stereo Digital Terrain Models (DTMs) from the High Resolution Imaging Science Experiment (HiRISE) to derive a characteristic of North Polar Layered Deposits (NPLD) strata that can be correlated over large distances: the topographic protrusion of layers exposed in troughs, which is a proxy for the layers’ resistance to erosion. Using a combination of image analysis and a signal-matching algorithm to correlate continuous depth-protrusion signals taken from DTMs at different locations, we construct a stratigraphic column that describes the upper ~500 m of at least 7% of the area of the NPLD, and find accumulation rates that vary by factors of up to two. We find that, when coupled with observations of exposed layers in orbital images, the topographic expression of the strata is consistently continuous through large distances in the top 300 – 500 m of the NPLD, suggesting it is better related to intrinsic layer properties than brightness alone.

  18. A design method for two-layer beams consisting of normal and fibered high strength concrete

    Iskhakov, I.; Ribakov, Y.

    2007-01-01

    Two-layer fibered concrete beams can be analyzed using conventional methods for composite elements. The compressed zone of such beam section is made of high strength concrete (HSC), and the tensile one of normal strength concrete (NSC). The problems related to such type of beams are revealed and studied. An appropriate depth of each layer is prescribed. Compatibility conditions between HSC and NSC layers are found. It is based on the shear deformations equality on the layers border in a section with maximal depth of the compression zone. For the first time a rigorous definition of HSC is given using a comparative analysis of deformability and strength characteristics of different concrete classes. According to this definition, HSC has no download branch in the stress-strain diagram, the stress-strain function has minimum exponent, the ductility parameter is minimal and the concrete tensile strength remains constant with an increase in concrete compression strength. The application fields of two-layer concrete beams based on different static schemes and load conditions make known. It is known that the main disadvantage of HSCs is their low ductility. In order to overcome this problem, fibers are added to the HSC layer. Influence of different fiber volume ratios on structural ductility is discussed. An upper limit of the required fibers volume ratio is found based on compatibility equation of transverse tensile concrete deformations and deformations of fibers

  19. Symmetry of order-parameters in high-Tc layered superconductors

    Rajagopal, A.K.; Jha, Sudhanshu S.

    1997-01-01

    It is well known that the anisotropy and wave-vector dependence of the energy-gap function determine many important properties of a superconductor which are relevant for device applications. Apart from a weak dependence on the wave-vector k - > in the direction perpendicular to the reciprocal layer-plane of a high-T c layered superconductor, it is shown that anisotropic superconducting order parameters for intra-layer pairing in the class of such materials with orthorhombic crystal structures, can have either pure s-wave like symmetry or mixed d-wave and anisotropic extended s-wave like symmetries in the reciprocal layer-plane. However, in such materials with tetragonal crystal structures, it is possible to have a pure s-wave like symmetry, which may be either isotropic or anisotropic in the layer k - >-space, or a pure d-wave like symmetry, as far the k - >-dependence in the reciprocal layer plane is concerned. In view of this, some suggestions for analysing experimental data will also be presented. (author)

  20. A high-resolution tracking hodoscope based on capillary layers filled with liquid scintillator

    Bay, A; Bruski, N; Buontempo, S; Currat, C; D'Ambrosio, N; Ekimov, A V; Ereditato, A; Fabre, Jean-Paul; Fanti, V; Frekers, D; Frenkel, A; Golovkin, S V; Govorun, V N; Harrison, K; Koppenburg, P; Kozarenko, E N; Kreslo, I E; Liberti, B; Martellotti, G; Medvedkov, A M; Mondardini, M R; Penso, G; Siegmund, W P; Vasilchenko, V G; Vilain, P; Wilquet, G; Winter, Klaus; Wörtche, H J

    2001-01-01

    Results are given on tests of a high-resolution tracking hodoscope based on layers of \\hbox{26-$\\mu$m-bore} glass capillaries filled with organic liquid scintillator (1-methylnaphthalene doped with R39). The detector prototype consisted of three 2-mm-thick parallel layers, with surface areas of $2.1 \\times 21$~cm$^2$. The layers had a centre-to-centre spacing of 6~mm, and were read by an optoelectronic chain comprising two electrostatically focused image intensifiers and an Electron-Bombarded Charge-Coupled Device (EBCCD). Tracks of cosmic-ray particles were recorded and analysed. The observed hit density was 6.6~hits/mm for particles crossing the layers perpendicularly, at a distance of 1~cm from the capillaries' readout end, and 4.2~hits/mm for particles at a distance of 20~cm. A track segment reconstructed in a single layer had an rms residual of $\\sim$~20~$\\mu$m, and allowed determination of the track position in a neighbouring layer with a precision of $\\sim$~170~$\\mu$m. This latter value corresponded to...

  1. Monitoring layer-by-layer assembly of polyelectrolyte multi-layers using high-order cladding mode in long-period fiber gratings

    Tian, F.; Kaňka, Jiří; Li, X.; Du, H.

    -, č. 196 (2014), s. 475-479 ISSN 0925-4005 R&D Projects: GA MŠk(CZ) LH11038 Institutional support: RVO:67985882 Keywords : Layer-by-layer assembly * Polyelectrolyte * Cladding mode Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 4.097, year: 2014

  2. Few-layer SnSe{sub 2} transistors with high on/off ratios

    Pei, Tengfei; Bao, Lihong, E-mail: lhbao@iphy.ac.cn; Wang, Guocai; Ma, Ruisong; Yang, Haifang; Li, Junjie; Gu, Changzhi; Du, Shixuan; Gao, Hong-jun [Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100190 (China); Pantelides, Sokrates [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States); Material Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37381 (United States)

    2016-02-01

    We report few-layer SnSe{sub 2} field effect transistors (FETs) with high current on/off ratios. By trying different gate configurations, 300 nm SiO{sub 2} and 70 nm HfO{sub 2} as back gate only and 70 nm HfO{sub 2} as back gate combined with a top capping layer of polymer electrolyte, few-layer SnSe{sub 2} FET with a current on/off ratio of 10{sup 4} can be obtained. This provides a reliable solution for electrically modulating quasi-two-dimensional materials with high electron density (over 10{sup 13} cm{sup −2}) for field-effect transistor applications.

  3. Synthetic Control of Kinetic Reaction Pathway and Cationic Ordering in High-Ni Layered Oxide Cathodes

    Wang, Dawei [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Kou, Ronghui [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Ren, Yang [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Sun, Cheng-Jun [X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne IL 60439 USA; Zhao, Hu [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; Zhang, Ming-Jian [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA; School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Li, Yan [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Huq, Ashifia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 USA; Ko, J. Y. Peter [The Cornell High Energy Synchrotron Source, Cornell University, Ithaca NY 14853 USA; Pan, Feng [School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen Guangdong 518055 P. R. China; Sun, Yang-Kook [Department of Energy Engineering, Hanyang University, Seoul 133-791 South Korea; Yang, Yong [Collaborative Innovation Center of Chemistry for Energy Materials, State Key Laboratory Physical Chemistry Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen Fujian 361005 China; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Bai, Jianming [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton NY 11973 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne IL 60439 USA; Wang, Feng [Sustainable Energy Technologies Department, Brookhaven National Laboratory, Upton NY 11973 USA

    2017-08-25

    Nickel-rich layered transition metal oxides, LiNi1-x(MnCo)(x)O-2 (1-x >= 0.5), are appealing candidates for cathodes in next-generation lithium-ion batteries (LIBs) for electric vehicles and other large-scale applications, due to their high capacity and low cost. However, synthetic control of the structural ordering in such a complex quaternary system has been a great challenge, especially in the presence of high Ni content. Herein, synthesis reactions for preparing layered LiNi0.7Mn0.15Co0.15O2 (NMC71515) by solid-state methods are investigated through a combination of time-resolved in situ high-energy X-ray diffraction and absorption spectroscopy measurements. The real-time observation reveals a strong temperature dependence of the kinetics of cationic ordering in NMC71515 as a result of thermal-driven oxidation of transition metals and lithium/oxygen loss that concomitantly occur during heat treatment. Through synthetic control of the kinetic reaction pathway, a layered NMC71515 with low cationic disordering and a high reversible capacity is prepared in air. The findings may help to pave the way for designing high-Ni layered oxide cathodes for LIBs.

  4. 深部岩体在高压水头作用下的渗透性状况试验%Experimental examination of permeability of deep rock mass under high water pressure

    黄震; 姜振泉; 孙晓倩; 曹丁涛; 王宗胜; 辛斌

    2015-01-01

    Water injection experiment is a particularly useful technique to determine the permeability of rock mass in deep geotechnical engineering. To probe the permeability of lower coal seam floor, high borehole pressure water injection experiment has been carried out to analyse the three segments of rock masses in one coal mine in Yanzhou, and numerous data have been obtained. Based on the formula of permeability coefficient as well as the analysis of the data, permeability coefficients of three segments of rock masses have been determined, and a generalized model has been established to describe the rela-tionship between permeability coefficients and pressure. The results show that the test pressure and the water discharge will suddenly change when the hydraulic fracturing occurs. The curves of permeability coefficient and pressure are provided with a significant geometric segmentation, which is stable before mutation and linear after mutation. Fissures will restore to be closed after water injection experiment, and the rock masses still have strong anti-permeability.%现场压水试验是揭示深部岩土工程中岩体渗透性能的可靠方法,为探究深部煤层底板岩体的渗透性,采用钻孔高压压水测试手段,对兖州矿区某矿下组煤底板三段岩体进行了现场压水试验,获得了大量压水测试数据.结合渗透系数计算公式,对试验数据进行了分析,获得了不同深度及不同岩性岩体的渗透系数值及渗透系数与压力关系的概化模式.研究结果表明:岩体发生渗流时,测试水压和流量会发生突变.岩体的渗透系数-压力关系曲线在几何形态表现出明显的分段性,即可分为突变点前的平稳段和突变点后的线性变化段.压水结束后,岩体裂隙会发生闭合,且仍具有较强的抗渗性.

  5. Deposition of LDH on plasma treated polylactic acid to reduce water permeability

    Bugatti, Valeria

    2013-04-01

    A simple and scalable deposition process was developed to prepare polylactic acid (PLA) coatings with enhanced water barrier properties for food packaging applications. This method based on electrostatic interactions between the positively charged layers of layered double hydroxides (LDHs) modified with ionic liquids (ILs) and the negatively charged plasma treated polylactic acid leads to homogeneous, stable, and highly durable coatings. Deposition of the LDH coatings increases the surface hydrophobicity of the neat PLA, which results to a decrease in water permeability by about 35%. © 2013 Elsevier Inc.

  6. Application of Mastic Asphalt Waterproofing Layer in High-Speed Railway Track in Cold Regions

    Song Liu

    2018-04-01

    Full Text Available Freeze-thaw damage is a typical distress incurred in road and railway engineering in cold regions. Concrete waterproofing layer is commonly used in high-speed railway tracks to prevent the penetration of surface water, however, it cracks easily under thermal stress, especially in cold regions. Recently solutions have been proposed to increase the waterproofing layer’s cracking resistance by using asphalt layers. Nonetheless, the use of emulsified asphalt as well as dense-graded asphalt mixture were not effective enough. To improve the effectiveness, in this study, mastic asphalt was designed for application as the waterproofing layer on the subgrade surface of high-speed railway tracks in cold regions. The overall performance of mastic asphalt was preliminarily evaluated by laboratory tests, then a 200-m test section was constructed for field validation in northeastern China as part of a new high-speed railway line, and water content sensors were placed inside the subgrade to monitor the performance of the mastic asphalt waterproofing layer (MAWL. The subsequent field investigation and monitoring data during the two years operation showed that MAWL dramatically outperformed the conventional concrete waterproofing layer in terms of waterproof performance. Plenty of serious cracks were found in the conventional concrete waterproofing layer, but only a limited number of local cracks were observed in MAWL. As a result, MAWL keeps the water content of subgrade at a stable level. In addition, MAWL showed relatively high stability during the two years investigation period, and no obvious deterioration was observed in the test section.

  7. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

    Xuezhi Shi

    2016-12-01

    Full Text Available To increase building rate and save cost, the selective laser melting (SLM of Ti6Al4V with a high layer thickness (200 μm and low cost coarse powders (53 μm–106 μm at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm3/s, which is about 2 times–9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  8. Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V.

    Shi, Xuezhi; Ma, Shuyuan; Liu, Changmeng; Chen, Cheng; Wu, Qianru; Chen, Xianping; Lu, Jiping

    2016-12-01

    To increase building rate and save cost, the selective laser melting (SLM) of Ti6Al4V with a high layer thickness (200 μm) and low cost coarse powders (53 μm-106 μm) at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm³/s, which is about 2 times-9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure.

  9. High dose, heavy ion implantation into metals: the use of sacrificial surface layers to enhance retention

    Clapham, L.

    1994-01-01

    While of considerable interest for the production of metallic alloys, high dose, heavy ion implantation is highly problematical, since the process is limited by sputtering effects. Sputtering is less significant, however, for light target materials, such as C and Al. This paper summarizes studies involving the use of light materials (such as C and Al) which act as slowly sputtering ''sacrificial layers'' when deposited on metallic targets prior to heavy ion implantation. The use of C and Al sacrificial coatings has enabled implanted ion retentions of 100% to be obtained in a number of ion-metal target systems, where the retentions in uncoated samples were as low as 20%. Ion implantation invariably leads to mixing at the sacrificial layer-metal target interface. This mixing may be detrimental in certain systems, so it is useful to be able to minimize or remove this mixed region. To achieve this, a number of techniques have been investigated: (1) removal of the mixed region in the latter stages of the implant; (2) using a barrier layer or chemical effects to minimize mixing at the sacrificial layer-metal interface; (3) choosing a sacrificial layer material which forms a mixed region which has desirable properties. The results of these investigations, for a number of different ion-target systems, are outlined in this paper. (orig.)

  10. High quality ZnO layers with adjustable refractive indices for integrated optics applications

    Heideman, Rene; Lambeck, Paul; Gardeniers, Johannes G.E.

    1995-01-01

    Thin (approx. 1 μm) crystalline ZnO films with a good optical quality and a good (0002) texture are grown under two considerably different process parameter sets using a r.f. planar magnetron sputtering unit. The optical parameters of the two corresponding ZnO layers are distinctly different: high

  11. Atomic layer deposition of high-mobility hydrogen-doped zinc oxide

    Macco, B.; Knoops, H.C.M.; Verheijen, M.A.; Beyer, W.; Creatore, M.; Kessels, W.M.M.

    2017-01-01

    In this work, atomic layer deposition (ALD) has been employed to prepare high-mobility H-doped zinc oxide (ZnO:H) films. Hydrogen doping was achieved by interleaving the ZnO ALD cycles with H2 plasma treatments. It has been shown that doping with H2 plasma offers key advantages over traditional

  12. Thin-Film layers with Interfaces that reduce RF Losses on High-Resistivity Silicon Substrates

    Evseev, S. B.; Milosavljevic, S.; Nanver, L. K.

    2017-01-01

    Radio-Frequency (RF) losses on High-Resistivity Silicon (HRS) substrates were studied for several different surface passivation layers comprising thin-films of SiC, SiN and SiO2 In many combinations, losses from conductive surface channels were reduced and increasing the number of interfaces between

  13. Silent spread of highly pathogenic Avian Influenza H5N1 virus amongst vaccinated commercial layers

    Poetri, O.N.; Boven, M.; Claassen, I.J.T.M.; Koch, G.; Wibawan, I.W.; Stegeman, A.; Broek, van den J.; Bouma, A.

    2014-01-01

    The aim of this study was to determine whether a single vaccination of commercial layer type chickens with an inactivated vaccine containing highly pathogenic avian influenza virus strain H5N1 A/chicken/Legok/2003, carried out on the farm, was sufficient to protect against infection with the

  14. High-temperature oxidation of tungsten covered by layer of glass-enamel melt

    Vasnetsova, V.B.; Shardakov, N.T.; Kudyakov, V.Ya.; Deryabin, V.A.

    1997-01-01

    Corrosion losses of tungsten covered by the layer of glass-enamel melt were determined at 800, 850, 900, 950 deg C. It is shown that the rate of high-temperature oxidation of tungsten decreases after application of glass-enamel melt on its surface. This is probably conditioned by reduction of area of metal interaction with oxidizing atmosphere

  15. Fabrication and research of high purity germanium detectors with abrupt and thin diffusion layer

    Rodriguez Cabal, A. E.; Diaz Garcia, A.

    1997-01-01

    A different high purity germanium detector's fabrication method is described. A very thin diffusion film with an abrupt change of the type of conductivity is obtained. The fine diffusion layer thickness makes possibly their utilization in experimental systems in which all the data are elaborated directly on the computer. (author) [es

  16. High heat flux testing of TiC coated molybdenum with a tungsten intermediate layer

    Fujitsuka, Masakazu; Fukutomi, Masao; Okada, Masatoshi

    1988-01-01

    The use of low atomic number (Z) material coatings for fusion reactor first-wall components has proved to be a valuable technique to reduce the plasma radiation losses. Molybdenum coated with titanium carbide is considered very promising since it has a good capability of receiving heat from the plasma. An interfacial reaction between the TiC film and the molybdenum substrate, however, causes a severe deterioration of the film at elevated temperatures. In order to solve this problem a TiC coated molybdenum with an intermediate tungsten layer was developed. High temperature properties of this material was evaluated by a newly devised electron beam heating apparatus. TiC coatings prepared on a vacuum-heat-treated molybdenum with a tungsten intermediate layer showed good high temperature stability and survived 2.0 s pulses of heating at a power density as high as 53 MW/m 2 . The melt area of the TiC coatings in high heat flux testings also markedly decreased when a tungsten intermediate layer was applied. The melting mechanism of the TiC coatings with and without a tungsten intermediate layer was discussed by EPMA measurements. (author)

  17. Mechanism for the formation of sporadic-E layers in the high-latitude ionosphere

    Vlasov, M.N.; Mishin, E.V.; Telegin, V.A.

    1980-09-01

    A model of the collective interaction of precipitating electrons and the ionospheric plasma is used to explain the formation of short-duration sporadic-E layers in the high-latitude ionosphere. The changes produced in electron density by this collective interaction mechanism are considered.

  18. Boundary layer plasmas as a source for high-latitude, early afternoon, auroral arcs

    Lundin, R.; Evans, D.S.

    1985-02-01

    Simultaneous measurements of hot boundary layer plasma from PROGNOZ-7 and particle precipitation from the TIROS/NOAA satellite in nearly magnetically conjugate regions have been used to study the dynamo process responsible for the formation of high latitude, early afternoon, auroral arcs. Characteristic for the PROGNOZ-7 observations in the dayside boundary layer at high latitudes is the frequent occurrence of regions with injected magnetosheath plasma embedded in a 'halo' of antisunward flowing magnetosphere plasma. The injected magnetosheath plasma have several features which indicate that it also acts as a local source of EMF in the boundary layer. The process resembles that of a local MHD dynamo driven by the excess drift velocity of the injected magnetosheath plasma relative to the background magnetospheric plasma. The dynamo region is capable of driving fielc-aligned currents that couple to the ionosphere, where the upward current is associated with the high latitude auroral arcs. We demonstrate that the large-scale morphology as well as the detailed data intercomparison between PROGNOZ-7 and TIROS-N both agree well with a local injection of magnetosheath plasma into the dayside boundary layer as the main dynamo process powering the high-latitude, early afternoon auroral arcs. (Author)

  19. Highly Stable Operation of Lithium Metal Batteries Enabled by the Formation of a Transient High Concentration Electrolyte Layer

    Zheng, Jianming; Yan, Pengfei; Mei, Donghai; Engelhard, Mark H.; Cartmell, Samuel S.; Polzin, Bryant; Wang, Chong M.; Zhang, Jiguang; Xu, Wu

    2016-02-08

    Lithium (Li) metal has been extensively investigated as an anode for rechargeable battery applications due to its ultrahigh specific capacity and the lowest redox potential. However, significant challenges including dendrite growth and low Coulombic efficiency are still hindering the practical applications of rechargeable Li metal batteries. Here, we demonstrate that long-term cycling of Li metal batteries can be realized by the formation of a transient high concentration electrolyte layer near the surface of Li metal anode during high rate discharge process. The highly concentrated Li+ ions in this transient layer will immediately solvate with the available solvent molecules and facilitate the formation of a stable and flexible SEI layer composed of a poly(ethylene carbonate) framework integrated with other organic/inorganic lithium salts. This SEI layer largely suppresses the corrosion of Li metal anode by free organic solvents and enables the long-term operation of Li metal batteries. The fundamental findings in this work provide a new direction for the development and operation of Li metal batteries that could be operated at high current densities for a wide range of applications.

  20. High-Quality Ultrathin Gold Layers with an APTMS Adhesion for Optimal Performance of Surface Plasmon Polariton-Based Devices

    Sukham, Johneph; Takayama, Osamu; Lavrinenko, Andrei

    2017-01-01

    , in particular, when the Au layer is not much thicker than the adhesion layers. We experimentally compared the performances of the ultrathin gold films to show the pivotal influence of adhesion layers on highly confined propagating plasmonic modes, using Cr and 3-aminopropyl trimethoxysilane (APTMS) adhesion...

  1. Electron Beam Evaporated TiO2 Layer for High Efficiency Planar Perovskite Solar Cells on Flexible Polyethylene Terephthalate Substrates

    Qiu, Weiming; Paetzold, Ulrich W; Gehlhaar, Robert; Smirnov, Vladimir; Boyen, Hans-Gerd; Tait, Jeffrey Gerhart; Conings, Bert; Zhang, Weimin; Nielsen, Christian; McCulloch, Iain; Froyen, Ludo; Heremans, Paul; Cheyns, David

    2015-01-01

    The TiO2 layer made by electron beam (e-beam) induced evaporation is demonstrated as electron transport layer (ETL) in high efficiency planar junction perovskite solar cells. The temperature of the substrate and the thickness of the TiO2 layer can

  2. Thermally activated flux creep in strongly layered high-temperature superconductors

    Chakravarty, S.; Ivlev, B.I.; Ovchinnikov, Y.N.

    1990-01-01

    Thermal activation energies for single vortices and vortex bundles in the presence of a magnetic field parallel to the layers are calculated. The pinning considered is intrinsic and is due to the strongly layered structure of high-temperature superconductors. The magnetic field and the current dependence of the activation energy are studied in detail. The calculation of the activation energy is used to determine the current-voltage characteristic. It may be possible to observe the effects discussed in this paper in a pure enough sample

  3. Measurement of oxide-layer thickness of internal granules in high-purity aluminium

    Takacs, S.; Ditroi, F.; Mahunka, I.

    1989-01-01

    Charged-particle activation analysis was used for the determination of bulk oxygen concentration in aluminium. High-purity aluminium samples and mixtures containing different amounts of alumina were irradiated by 13 MeV 3 He particles. The aim of the investigation was to determine the oxide-layer thickness on the surface of internal aluminium granules. The measurement was carried out by determining the bulk oxygen concentration in the samples, and calculating the oxide-layer thickness, by using model conditions about the microstructure of the aluminium samples. (author) 5 refs

  4. Third Generation (3G) Site Characterization: Cryogenic Core Collection and High Throughput Core Analysis - An Addendum to Basic Research Addressing Contaminants in Low Permeability Zones - A State of the Science Review

    2016-07-29

    Styrofoam insulation for keeping the core frozen during MRI .................................. 78 Figure 5-2. Schematic of reference and core setting in... Hollow -Stem Auger HTCA High-Throughput Core Analysis IC Ion Chromatograph ID Inner Diameter k Permeability LN Liquid Nitrogen LNAPL Light...vibration, or “over drilling” using a hollow -stem auger. The ratio of the length of the collected core to the depth over which the sample tube is

  5. Scientific Perspectives on Extending the Provision for Waivers of In vivo Bioavailability and Bioequivalence Studies for Drug Products Containing High Solubility-Low Permeability Drugs (BCS-Class 3)

    Stavchansky, Salomon

    2008-01-01

    Recently, there has been increased interest in extending the provision for waivers of in vivo bioavailability and bioequivalence (BA–BE) studies that appeared in the guidance published by the Food and Drug Administration (FDA) (1) to pharmaceutical products containing Class 3 drugs (High solubility–Low Permeability). The extension of the Biopharmaceutics Classification System (BCS) to Class 3 drugs is meritorious because of its impact on public health policy considerations. The rate limiting ...

  6. Response of the convecting high-latitude F layer to a powerful HF wave

    G. I. Mingaleva

    1997-10-01

    Full Text Available A numerical model of the high-latitude ionosphere, which takes into account the convection of the ionospheric plasma, has been developed and utilized to simulate the F-layer response at auroral latitudes to high-power radio waves. The model produces the time variations of the electron density, positive ion velocity, and ion and electron temperature profiles within a magnetic field tube carried over an ionospheric heater by the convection electric field. The simulations have been performed for the point with the geographic coordinates of the ionospheric HF heating facility near Tromso, Norway, when it is located near the midnight magnetic meridian. The calculations have been made for equinox, at high-solar-activity, and low-geomagnetic-activity conditions. The results indicate that significant variations of the electron temperature, positive ion velocity, and electron density profiles can be produced by HF heating in the convecting high-latitude F layer.

  7. Response of the convecting high-latitude F layer to a powerful HF wave

    G. I. Mingaleva

    Full Text Available A numerical model of the high-latitude ionosphere, which takes into account the convection of the ionospheric plasma, has been developed and utilized to simulate the F-layer response at auroral latitudes to high-power radio waves. The model produces the time variations of the electron density, positive ion velocity, and ion and electron temperature profiles within a magnetic field tube carried over an ionospheric heater by the convection electric field. The simulations have been performed for the point with the geographic coordinates of the ionospheric HF heating facility near Tromso, Norway, when it is located near the midnight magnetic meridian. The calculations have been made for equinox, at high-solar-activity, and low-geomagnetic-activity conditions. The results indicate that significant variations of the electron temperature, positive ion velocity, and electron density profiles can be produced by HF heating in the convecting high-latitude F layer.

  8. High Field Linear Magnetoresistance Sensors with Perpendicular Anisotropy L10-FePt Reference Layer

    X. Liu

    2016-01-01

    Full Text Available High field linear magnetoresistance is an important feature for magnetic sensors applied in magnetic levitating train and high field positioning measurements. Here, we investigate linear magnetoresistance in Pt/FePt/ZnO/Fe/Pt multilayer magnetic sensor, where FePt and Fe ferromagnetic layers exhibit out-of-plane and in-plane magnetic anisotropy, respectively. Perpendicular anisotropy L10-FePt reference layer with large coercivity and high squareness ratio was obtained by in situ substrate heating. Linear magnetoresistance is observed in this sensor in a large range between +5 kOe and −5 kOe with the current parallel to the film plane. This L10-FePt based sensor is significant for the expansion of linear range and the simplification of preparation for future high field magnetic sensors.

  9. Foam film permeability: theory and experiment.

    Farajzadeh, R; Krastev, R; Zitha, Pacelli L J

    2008-02-28

    The mass transfer of gas through foam films is a prototype of various industrial and biological processes. The aim of this paper is to give a perspective and critical overview of studies carried out to date on the mass transfer of gas through foam films. Contemporary experimental data are summarized, and a comprehensive overview of the theoretical models used to explain the observed effects is given. A detailed description of the processes that occur when a gas molecule passes through each layer that forms a foam film is shown. The permeability of the film-building surfactant monolayers plays an important role for the whole permeability process. It can be successfully described by the models used to explain the permeability of surfactant monolayers on aqueous sub-phase. For this reason, the present paper briefly discusses the surfactant-induced resistance to mass transfer of gases through gas-liquid interface. One part of the paper discusses the experimental and theoretical aspects of the foam film permeability in a train of foam films in a matrix or a cylinder. This special case is important to explain the gas transfer in porous media or in foams. Finally, this paper will highlight the gaps and challenges and sketch possible directions for future research.

  10. Crystal layered structure and superconducting high-Tc behaviour of the mercurocuprates

    Kuzemsky, A.L.; Kuzemskaya, I.G.; Cheglokov, A.A.

    1998-10-01

    The high-T c superconducting behaviour of the mercurocuprate family HgBa 2 Ca n-1 Cu n O 2n+2+δ was analyzed from the point of view of their layered crystal structure. A dependence of superconducting critical temperature for different members of mercurocuprate family was studied in terms of phenomenological model of layered superconductors. The redistribution of charge was taken into account. This leads to an observable nonmonotonic ''bell''-shaped dependence of T c (n) with a maximum at n=3 and provides a quantitative explanation of the experiments. It was shown that the correlations between the copper valence, lattice parameters, extra oxygen contents and number of layers are essential factors for the physical behaviour and HTSC characterization of the mercurocuprates. (author)

  11. Atomic layer deposited high-k dielectric on graphene by functionalization through atmospheric plasma treatment

    Shin, Jeong Woo; Kang, Myung Hoon; Oh, Seongkook; Yang, Byung Chan; Seong, Kwonil; Ahn, Hyo-Sok; Lee, Tae Hoon; An, Jihwan

    2018-05-01

    Atomic layer-deposited (ALD) dielectric films on graphene usually show noncontinuous and rough morphology owing to the inert surface of graphene. Here, we demonstrate the deposition of thin and uniform ALD ZrO2 films with no seed layer on chemical vapor-deposited graphene functionalized by atmospheric oxygen plasma treatment. Transmission electron microscopy showed that the ALD ZrO2 films were highly crystalline, despite a low ALD temperature of 150 °C. The ALD ZrO2 film served as an effective passivation layer for graphene, which was shown by negative shifts in the Dirac voltage and the enhanced air stability of graphene field-effect transistors after ALD of ZrO2. The ALD ZrO2 film on the functionalized graphene may find use in flexible graphene electronics and biosensors owing to its low process temperature and its capacity to improve device performance and stability.

  12. Experimental investigation of the effects of high-frequency electroactive morphing on the shear-layer

    Scheller, Johannes; Rizzo, Karl-Joseph; Jodin, Gurvan; Duhayon, Eric; Rouchon, Jean-François; Hunt, Julian; Braza, Marianna

    2015-11-01

    Time-resolved PIV measurements are conducted at a Reynolds number of 270 . 000 downstream of the trailing edge of a NACA4412 airfoil equipped with trailing-edge piezoelectric tab actuators to investigate the high-frequency low-amplitude actuation's effect on the shear-layer. A comparison of the time-averaged Reynolds stress tensor components at different actuation frequency reveals a significant impact of the actuation on the shear-layer dynamics. A proper orthogonal decomposition analysis is conducted in order to investigate the actuation's impact on the vortex breakdown. It will be shown that a specific low-amplitude actuation frequency enables a reduction of the predominant shear-layer frequencies.

  13. A high voltage SOI pLDMOS with a partial interface equipotential floating buried layer

    Wu Lijuan; Zhang Wentong; Zhang Bo; Li Zhaoji

    2013-01-01

    A novel silicon-on-insulator (SOI) high-voltage pLDMOS is presented with a partial interface equipotential floating buried layer (FBL) and its analytical model is analyzed in this paper. The surface heavily doped p-top layers, interface floating buried N + /P + layers, and three-step field plates are designed carefully in the FBL SOI pLDMOS to optimize the electric field distribution of the drift region and reduce the specific resistance. On the condition of ESIMOX (epoxy separated by implanted oxygen), it has been shown that the breakdown voltage of the FBL SOI pLDMOS is increased from −232 V of the conventional SOI to −425 V and the specific resistance R on,sp is reduced from 0.88 to 0.2424 Ω·cm 2 . (semiconductor devices)

  14. Unstacked double-layer templated graphene for high-rate lithium-sulphur batteries

    Zhao, Meng-Qiang; Zhang, Qiang; Huang, Jia-Qi; Tian, Gui-Li; Nie, Jing-Qi; Peng, Hong-Jie; Wei, Fei

    2014-03-01

    Preventing the stacking of graphene is essential to exploiting its full potential in energy-storage applications. The introduction of spacers into graphene layers always results in a change in the intrinsic properties of graphene and/or induces complexity at the interfaces. Here we show the synthesis of an intrinsically unstacked double-layer templated graphene via template-directed chemical vapour deposition. The as-obtained graphene is composed of two unstacked graphene layers separated by a large amount of mesosized protuberances and can be used for high-power lithium-sulphur batteries with excellent high-rate performance. Even after 1,000 cycles, high reversible capacities of ca. 530 mA h g-1 and 380 mA h g-1 are retained at 5 C and 10 C, respectively. This type of double-layer graphene is expected to be an important platform that will enable the investigation of stabilized three-dimensional topological porous systems and demonstrate the potential of unstacked graphene materials for advanced energy storage, environmental protection, nanocomposite and healthcare applications.

  15. Paintings - high-energy protons detect pigments and paint-layers

    Denker, A.; Opitz-Coutureau, J.

    2004-01-01

    High-energy PIXE was used to identify pigment composition, sequencing and the thickness of paint-layers. Before applying the technique to valuable masterpieces, mock-ups were examined in a collaboration with the Kunsthistorisches Museum, Vienna. The results of high-energy PIXE were compared to conventional cross-section analysis. In addition, the non-destructiveness of the technique was investigated thoroughly. After this preparative work, two ancient paintings have been examined and the results are presented in this paper

  16. Experimental studies on the performance of novel layered materials under highly dynamic loads

    Shukla, A, E-mail: shuklaa@egr.uri.ed [Dynamic Photomechanics Laboratory Department of Mechanical Engineering and Applied Mechanics University of Rhode Island, Kingston, RI 02881 (United States)

    2009-08-01

    This paper focuses on the experimental observations of the performance of different layered composite material systems subjected to blast loadings. These material systems include layered composites and sandwich composite materials. A controlled blast loading of pre-defined pressure magnitude and rise time were obtained using a shock tube apparatus. Rectangular plate elements of the desired material system were subjected to such a controlled blast loading and the effects of the blast loading on these elements were studied using optical and residual strength measurements. A high speed imaging technique was utilized to study the damage modes and mechanisms in real time. It was observed that layering of a conventional composite material with a soft visco-elastic polymer provided better blast resistance and sandwiching the polymer greatly enhanced its survivability under extreme air blast conditions. Aside from layering the conventional composite material with a soft visco-elastic polymer, it was observed that layering or grading the core can successfully mitigate the impact damage and thus improve the overall blast resistance as well. In addition to these, three dimensional (3D) woven skin and core reinforcements were introduced in the conventional sandwich composites and their effects on the blast resistance were studied experimentally. It was observed that these reinforcements also enhance the blast resistance of conventional sandwich composites by changing the mechanism of failure initiation and propagation in these sandwich structures.

  17. High-Sensitive Two-Layer Photoresistors Based on p-Cd x Hg1- x Te with a Converted Near-Surface Layer

    Ismailov, N. D.; Talipov, N. Kh.; Voitsekhovskii, A. V.

    2018-04-01

    The results of an experimental study of photoelectric characteristics of two-layer photoresistors based on p-Cd x Hg1- x Te (x = 0.24-0.28) with a thin near-surface layer of n-type obtained by treatment in atmospheric gas plasma are presented. It is shown that the presence of a potential barrier between the p- and n-regions causes high photosensitivity and speed of operation of such photoresistors at T = 77 K

  18. High-Sensitive Two-Layer Photoresistors Based on p-Cd x Hg1-x Te with a Converted Near-Surface Layer

    Ismailov, N. D.; Talipov, N. Kh.; Voitsekhovskii, A. V.

    2018-04-01

    The results of an experimental study of photoelectric characteristics of two-layer photoresistors based on p-Cd x Hg1-x Te (x = 0.24-0.28) with a thin near-surface layer of n-type obtained by treatment in atmospheric gas plasma are presented. It is shown that the presence of a potential barrier between the p- and n-regions causes high photosensitivity and speed of operation of such photoresistors at T = 77 K

  19. Ambient Layer-by-Layer ZnO Assembly for Highly Efficient Polymer Bulk Heterojunction Solar Cells

    Eita, Mohamed Samir

    2015-02-04

    The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in fl exible devices. Here, a layer-by-layer (LbL) protocol is reported as a facile, room-temperature, solution-processed method to prepare electron transport layers from commercial ZnO nanoparticles and polyacrylic acid (PAA) with a controlled and tunable porous structure, which provides large interfacial contacts with the active layer. Applying the LbL approach to bulk heterojunction polymer solar cells with an optimized ZnO layer thickness of H25 nm yields solar cell power-conversion effi ciencies (PCEs) of ≈6%, exceeding the effi ciency of amorphous ZnO interlayers formed by conventional sputtering methods. Interestingly, annealing the ZnO/PAA interlayers in nitrogen and air environments in the range of 60-300 ° C reduces the device PCEs by almost 20% to 50%, indicating the importance of conformational changes inherent to the PAA polymer in the LbL-deposited fi lms to solar cell performance. This protocol suggests a new fabrication method for solution-processed polymer solar cell devices that does not require postprocessing thermal annealing treatments and that is applicable to fl exible devices printed on plastic substrates.

  20. Large-Area Synthesis of High-Quality Uniform Few-Layer MoTe2.

    Zhou, Lin; Xu, Kai; Zubair, Ahmad; Liao, Albert D; Fang, Wenjing; Ouyang, Fangping; Lee, Yi-Hsien; Ueno, Keiji; Saito, Riichiro; Palacios, Tomás; Kong, Jing; Dresselhaus, Mildred S

    2015-09-23

    The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe2) crystals is crucial for its various applications based on the attractive properties of this emerging material. In this work, we developed a chemical vapor deposition synthesis to produce large-area, uniform, and highly crystalline few-layer 2H and 1T' MoTe2 films. It was found that these two different phases of MoTe2 can be grown depending on the choice of Mo precursor. Because of the highly crystalline structure, the as-grown few-layer 2H MoTe2 films display electronic properties that are comparable to those of mechanically exfoliated MoTe2 flakes. Our growth method paves the way for the large-scale application of MoTe2 in high-performance nanoelectronics and optoelectronics.

  1. Receptivity and Forced Response to Acoustic Disturbances in High-Speed Boundary Layers

    Balakumar, P.; King, Rudolph A.; Chou, Amanda; Owens, Lewis R.; Kegerise, Michael A.

    2016-01-01

    Supersonic boundary-layer receptivity to freestream acoustic disturbances is investigated by solving the Navier-Stokes equations for Mach 3.5 flow over a sharp flat plate and a 7-deg half-angle cone. The freestream disturbances are generated from a wavy wall placed at the nozzle wall. The freestream acoustic disturbances radiated by the wavy wall are obtained by solving the linearized Euler equations. The results for the flat plate show that instability modes are generated at all the incident angles ranging from zero to highly oblique. However, the receptivity coefficient decreases by about 20 times when the incident angle increases from zero to a highly oblique angle of 68 degrees. The results for the cone show that no instability modes are generated when the acoustic disturbances impinge the cone obliquely. The results show that the perturbations generated inside the boundary layer by the acoustic disturbances are the response of the boundary layer to the external forcing. The amplitude of the forced disturbances inside the boundary layer are about 2.5 times larger than the incoming field for zero azimuthal wavenumber and they are about 1.5 times for large azimuthal wavenumbers.

  2. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene

    Piotr Michałowski, Paweł; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-01

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm‑2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  3. Effects of AlN Coating Layer on High Temperature Characteristics of Langasite SAW Sensors

    Lin Shu

    2016-09-01

    Full Text Available High temperature characteristics of langasite surface acoustic wave (SAW devices coated with an AlN thin film have been investigated in this work. The AlN films were deposited on the prepared SAW devices by mid-frequency magnetron sputtering. The SAW devices coated with AlN films were measured from room temperature to 600 °C. The results show that the SAW devices can work up to 600 °C. The AlN coating layer can protect and improve the performance of the SAW devices at high temperature. The SAW velocity increases with increasing AlN coating layer thickness. The temperature coefficients of frequency (TCF of the prepared SAW devices decrease with increasing thickness of AlN coating layers, while the electromechanical coupling coefficient (K2 of the SAW devices increases with increasing AlN film thickness. The K2 of the SAW devices increases by about 20% from room temperature to 600 °C. The results suggest that AlN coating layer can not only protect the SAW devices from environmental contamination, but also improve the K2 of the SAW devices.

  4. Highly efficient and reliable high power LEDs with patterned sapphire substrate and strip-shaped distributed current blocking layer

    Zhou, Shengjun [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yuan, Shu; Liu, Yingce [Quantum Wafer Inc., Foshan 528251 (China); Guo, L. Jay [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 (United States); Liu, Sheng, E-mail: victor_liu63@126.com [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Ding, Han [State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-11-15

    Graphical abstract: - Highlights: • TEM is used to characterize threading dislocation existing in GaN epitaxial layer. • Effect of threading dislocation on optical and electrical of LEDs is discussed. • Strip-shaped SiO{sub 2} DCBL is designed to improve current spreading performance of LEDs. - Abstract: We demonstrated that the improvement in optical and electrical performance of high power LEDs was achieved using cone-shaped patterned sapphire substrate (PSS) and strip-shaped SiO{sub 2} distributed current blocking layer (DCBL). We found through transmission electron microscopy (TEM) observation that densities of both the screw dislocation and edge dislocation existing in GaN epitaxial layer grown on PSS were much less than that of GaN epitaxial layer grown on flat sapphire substrate (FSS). Compared to LED grown on FSS, LED grown on PSS showed higher sub-threshold forward-bias voltage and lower reverse leakage current, resulting in an enhancement in device reliability. We also designed a strip-shaped SiO{sub 2} DCBL beneath a strip-shaped p-electrode, which prevents the current from being concentrated on regions immediately adjacent the strip-shaped p-electrode, thereby facilitating uniform current spreading into the active region. By implementing strip-shaped SiO{sub 2} DCBL, light output power of high power PSS-LED chip could be further increased by 13%.

  5. Combined Permeability Improvement Technology of High-pressure Hydraulic Slotting with Hydraulic Fracturing and Its Application%高压水力割缝和压裂联合增透技术及应用

    秦江涛; 陈玉涛

    2016-01-01

    针对白皎煤矿突出煤层构造应力高、透气性系数低、瓦斯抽采效果差等问题,在238底板瓦斯抽采巷对B4煤层采用了水力割缝和压裂联合增透技术,应用结果表明该技术相比水力压裂技术和普通抽采技术提高了煤层透气性,瓦斯抽采纯量较水力压裂钻孔提高了1.33倍,瓦斯体积分数是普通抽采钻孔的2.76倍,联合增透钻孔汇总瓦斯体积分数保持在30%以上且无衰减,具有良好的抽采效果.%To counter the problems of high structural stress, low air permeability coefficient and poor gas drainage effect of the outburst coal seam in Baijiao Mine, the gas drainage test in B4 seam by 238 floor drainage roadway was carried out with the combined permeability improvement technology of high-pressure hydraulic slotting with hydraulic fracturing. The application results showed that this technology improved the permeability of the coal seam as compared to the hydraulic fracturing technology and the conventional gas drainage technology. The pure gas drainage volume increased 1. 33 times to that by hydraulic fracturing, the volume fraction of gas was 2. 76 times higher than that by the conventional drainage boreholes, the summary volume fraction of gas with the combined permeability improvement technology maintained over 30% without any attenuation, so this technology has good drainage effect.

  6. High-efficiency green phosphorescent organic light-emitting diodes with double-emission layer and thick N-doped electron transport layer

    Nobuki, Shunichiro, E-mail: shunichiro.nobuki.nb@hitachi.com [Hitachi Research Laboratory, Hitachi Ltd., 7-1-1 Omika-cho, Hitachi-city, Ibaraki 319-1292 (Japan); Wakana, Hironori; Ishihara, Shingo [Hitachi Research Laboratory, Hitachi Ltd., 7-1-1 Omika-cho, Hitachi-city, Ibaraki 319-1292 (Japan); Mikami, Akiyoshi [Dept. of Electrical Engineering, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichimachi, Ishikawa 921-8501 (Japan)

    2014-03-03

    We have developed green phosphorescent organic light-emitting diodes (OLEDs) with high external quantum efficiency of 59.7% and power efficiency of 243 lm/W at 2.73 V at 0.053 mA/cm{sup 2}. A double emission layer and a thick n-doped electron transport layer were adopted to improve the exciton recombination factor. A high refractive index hemispherical lens was attached to a high refractive index substrate for extracting light trapped inside the substrate and the multiple-layers of OLEDs to air. Additionally, we analyzed an energy loss mechanism to clarify room for the improvement of our OLEDs including the charge balance factor. - Highlights: • We developed high efficiency green phosphorescent organic light-emitting diode (OLED). • Our OLED had external quantum efficiency of 59.7% and power efficiency of 243 lm/W. • A double emission layer and thick n-doped electron transport layer were adopted. • High refractive index media (hemispherical lens and substrate) were also used. • We analyzed an energy loss mechanism to clarify the charge balance factor of our OLED.

  7. Influence of Cholesterol on the Oxygen Permeability of Membranes: Insight from Atomistic Simulations.

    Dotson, Rachel J; Smith, Casey R; Bueche, Kristina; Angles, Gary; Pias, Sally C

    2017-06-06

    Cholesterol is widely known to alter the physical properties and permeability of membranes. Several prior works have implicated cell membrane cholesterol as a barrier to tissue oxygenation, yet a good deal remains to be explained with regard to the mechanism and magnitude of the effect. We use molecular dynamics simulations to provide atomic-resolution insight into the influence of cholesterol on oxygen diffusion across and within the membrane. Our simulations show strong overall agreement with published experimental data, reproducing the shapes of experimental oximetry curves with high accuracy. We calculate the upper-limit transmembrane oxygen permeability of a 1-palmitoyl,2-oleoylphosphatidylcholine phospholipid bilayer to be 52 ± 2 cm/s, close to the permeability of a water layer of the same thickness. With addition of cholesterol, the permeability decreases somewhat, reaching 40 ± 2 cm/s at the near-saturating level of 62.5 mol % cholesterol and 10 ± 2 cm/s in a 100% cholesterol mimic of the experimentally observed noncrystalline cholesterol bilayer domain. These reductions in permeability can only be biologically consequential in contexts where the diffusional path of oxygen is not water dominated. In our simulations, cholesterol reduces the overall solubility of oxygen within the membrane but enhances the oxygen transport parameter (solubility-diffusion product) near the membrane center. Given relatively low barriers to passing from membrane to membrane, our findings support hydrophobic channeling within membranes as a means of cellular and tissue-level oxygen transport. In such a membrane-dominated diffusional scheme, the influence of cholesterol on oxygen permeability is large enough to warrant further attention. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. Steam-water relative permeability

    Ambusso, W.; Satik, C.; Home, R.N. [Stanford Univ., CA (United States)

    1997-12-31

    A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

  9. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    Keturakis, Christopher J. [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Ben [Brandeis University, Waltham, MA 02453 (United States); Blenheim, Alex [Department of Mechanical Engineering, Pennsylvania State University, College Park, PA 16802 (United States); Miller, Alfred C.; Pafchek, Rob [Zettlemoyer Center for Surface Studies, Lehigh University, Bethlehem, PA 18015 (United States); Notis, Michael R., E-mail: mrn1@lehigh.edu [Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015 (United States); Wachs, Israel E., E-mail: iew0@lehigh.edu [Operando Molecular Spectroscopy and Catalysis Research Laboratory, Department of Chemical Engineering, Lehigh University, Bethlehem, PA 18015 (United States)

    2016-07-15

    Highlights: • Five ancient silver alloy coins (225 BCE–244 CE) were analyzed using surface characterization techniques. • Both destructive and non-destructive surface characterization methods were developed. • Alloying with copper, even in small amounts, leads to the formation of an outer Cu{sub 2}O corrosion layer. - Abstract: Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE–244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1–3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300–1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu{sub 2}O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu{sub 2}O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu{sub 2}O layer. Depth profiling revealed the presence of K, Na, Cl, and

  10. Analysis of corrosion layers in ancient Roman silver coins with high resolution surface spectroscopic techniques

    Keturakis, Christopher J.; Notis, Ben; Blenheim, Alex; Miller, Alfred C.; Pafchek, Rob; Notis, Michael R.; Wachs, Israel E.

    2016-01-01

    Highlights: • Five ancient silver alloy coins (225 BCE–244 CE) were analyzed using surface characterization techniques. • Both destructive and non-destructive surface characterization methods were developed. • Alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O corrosion layer. - Abstract: Determination of the microchemistry of surface corrosion layers on ancient silver alloy coins is important both in terms of understanding the nature of archaeological environmental conditions to which these ancient coins were exposed and also to help in their conservation. In this present study, five ancient silver alloy coins (225 BCE–244 CE) were used as test vehicles to measure their immediate surface microchemistry and evaluate the appropriateness and limitations of High Sensitivity-Low Energy Ion Scattering Spectroscopy (HS-LEIS, 0.3 nm depth analysis), High Resolution-X-ray Photoelectron Spectroscopy (HR-XPS, 1–3 nm depth analysis) and High Resolution-Raman Spectroscopy (HR-Raman, ∼1000 nm depth analysis). Additional information about the deeper corrosion layers, up to ∼300–1000 nm, was provided by dynamic HS-LEIS and HR-Raman spectroscopy. While not archeologically significant, the use of these coins of small commercial value provides data that is more representative of the weaker signals typically obtained from ancient corroded objects, which can be in stark contrast to pristine data often obtained from carefully prepared alloys of known composition. The oldest coins, from 225 to 214 BCE, possessed an outermost surface layer containing Cu 2 O, Na, Al, Pb, and adsorbed hydrocarbons, while the more recent coins, from 98 to 244 CE, contained Cu 2 O, Ag, N, F, Na, Al, S, Cl, and adsorbed hydrocarbons in similar corresponding surface layers. It thus appears that alloying with copper, even in small amounts, leads to the formation of an outer Cu 2 O layer. Depth profiling revealed the presence of K, Na, Cl, and S as key

  11. Permeability measuremens of brazilian Eucalyptus

    Marcio Rogério da Silva

    2010-09-01

    Full Text Available The permeability of Brazilian Eucalyptus grandis and Eucalyptus citriodora wood was measured in a custom build gas analysis chamber in order to determine which species could be successfully treated with preservatives. Liquid permeability was tested using an emulsion of Neen oil and a control of distillated water. Air was used to test the gas phase permeability. For both Eucalyptus grandis and Eucalyptus citriodora, the longitudinal permeability of gas was shown to be about twice as great as the liquid phase permeability. No radial permeability was observed for either wood. The permeability of air and water through the sapwood of Eucalyptus grandis was greater than that through the sapwood of Eucalyptus citriodora. The permeability of neen oil preservative through the sapwood of Eucalyptus grandis was also greater than through the sapwood of E. Citradora, but the difference was not statistically significant. Scanning Electron Microscopy images showed that the distribution and obstruction in the vessels could be correlated with observed permeability properties. Irrespective of the causes of differences in permeability between the species, the fluid phase flux through the sapwood of both species was significant, indicating that both Eucalyptus grandis and Eucalyptus citriodora could be successfully treated with wood preservative.

  12. The Effect of Excipients on the Permeability of BCS Class III Compounds and Implications for Biowaivers

    Parr, Alan; Hidalgo, Ismael J.; Bode, Chris; Brown, William; Yazdanian, Mehran; Gonzalez, Mario A.; Sagawa, Kazuko; Miller, Kevin; Jiang, Wenlei; Stippler, Erika S.

    2015-01-01

    Purpose Currently, the FDA allows biowaivers for Class I (high solubility and high permeability) and Class III (high solubility and low permeability) compounds of the Biopharmaceutics Classification System (BCS). Scientific evidence should be provided to support biowaivers for BCS Class I and Class III (high solubility and low permeability) compounds. Methods Data on the effects of excipients on drug permeability are needed to demonstrate that commonly used excipients do not affect the permea...

  13. Layer-by-layer assembled TiO2 films with high ultraviolet light-shielding property

    Li, Xiaozhou; Wang, Lin; Pei, Yuxin; Jiang, Jinqiang

    2014-01-01

    Ultraviolet (UV) B is hazardous to human, plants and animals. With the rapid growth of ozone holes over the earth, the exploration of optical materials that can cut off harmful UV radiation is important. In this work, fusiform TiO 2 nanoparticles were synthesized by a hydrothermal synthesis method. The thin films assembled with TiO 2 nanoparticles and oppositely charged polyelectrolytes were fabricated via a layer-by-layer assembly method. The fabrication of poly(ethylene imine) (PEI)/TiO 2 multilayer films was verified by ultraviolet–visible spectra measurements, scanning electron microscopy and atomic force microscopy. The as-prepared PEI/TiO 2 multilayer films can effectively absorb harmful UVB light and filter off visible light. Most importantly, the PEI/TiO 2 films can be deposited directly on various kinds of hydrophilic substrates such as quartz, glass, silicon and hydrophobic substrates such as polystyrene, polypropylene, polyethylene and polymethyl methacrylate when the hydrophilic substrates were modified to obtain a hydrophilic surface. - Highlights: • PEI/TiO 2 films were fabricated via a layer-by-layer self-assembly method. • The films could effectively absorb harmful UVB light and filter off visible light. • The films could deposit directly on either hydrophilic or hydrophobic substrates

  14. Layer-by-layer assembled TiO{sub 2} films with high ultraviolet light-shielding property

    Li, Xiaozhou [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Wang, Lin, E-mail: wanglin0317@nwsuaf.edu.cn [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Pei, Yuxin [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Jiang, Jinqiang [State Key Lab of Applied Surface and Colloid Chemistry, College of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an 710062 (China)

    2014-11-28

    Ultraviolet (UV) B is hazardous to human, plants and animals. With the rapid growth of ozone holes over the earth, the exploration of optical materials that can cut off harmful UV radiation is important. In this work, fusiform TiO{sub 2} nanoparticles were synthesized by a hydrothermal synthesis method. The thin films assembled with TiO{sub 2} nanoparticles and oppositely charged polyelectrolytes were fabricated via a layer-by-layer assembly method. The fabrication of poly(ethylene imine) (PEI)/TiO{sub 2} multilayer films was verified by ultraviolet–visible spectra measurements, scanning electron microscopy and atomic force microscopy. The as-prepared PEI/TiO{sub 2} multilayer films can effectively absorb harmful UVB light and filter off visible light. Most importantly, the PEI/TiO{sub 2} films can be deposited directly on various kinds of hydrophilic substrates such as quartz, glass, silicon and hydrophobic substrates such as polystyrene, polypropylene, polyethylene and polymethyl methacrylate when the hydrophilic substrates were modified to obtain a hydrophilic surface. - Highlights: • PEI/TiO{sub 2} films were fabricated via a layer-by-layer self-assembly method. • The films could effectively absorb harmful UVB light and filter off visible light. • The films could deposit directly on either hydrophilic or hydrophobic substrates.

  15. Effect of desensitizing agents on dentin permeability.

    Ishihata, Hiroshi; Kanehira, Masafumi; Nagai, Tomoko; Finger, Werner J; Shimauchi, Hidetoshi; Komatsu, Masashi

    2009-06-01

    To investigate the in vitro efficacy of two dentin desensitizing products at reducing liquid permeability through human dentin discs. The tested hypothesis was that the products, in spite of different chemical mechanisms were not different at reducing or eliminating flow through dentin discs. Dentin slices (1 mm thick) were prepared from 16 extracted human third molars and their permeability was indirectly recorded in a split chamber model, using a chemiluminescence technique, after EDTA treatment (control), after soaking with albumin, and after desensitizer application. Two products were studied: MS Coat, a self-curing resin-containing oxalate product, and Gluma Desensitizer, a glutaraldehyde/HEMA-based agent without initiator. The dentin slices were mounted between an upper chamber, filled with an aqueous solution of 1% potassium ferricyanide and 0.3% hydrogen peroxide, and a lower chamber filled with 1% sodium hydroxide solution and 0.02% luminol. The upper solution was pressurized, and upon contact with the luminol solution a photochemical signal was generated and recorded as a measure of permeability throughout two consecutive pressurizing cycles at 2.5 and 13 kPa (26 and 133 cm H2O), respectively. The permeability of the control and albumin-soaked samples was similarly high. After application of the desensitizing agents, dentin permeability was reduced to virtually zero at both pressure levels (P < 0.001).

  16. Fused Methoxynaphthyl Phenanthrimidazole Semiconductors as Functional Layer in High Efficient OLEDs.

    Jayabharathi, Jayaraman; Ramanathan, Periyasamy; Karunakaran, Chockalingam; Thanikachalam, Venugopal

    2016-01-01

    Efficient hole transport materials based on novel fused methoxynaphthyl phenanthrimidazole core structure were synthesised and characterized. Their device performances in phosphorescent organic light emitting diodes were investigated. The high thermal stability in combination with the reversible oxidation process made promising candidates as hole-transporting materials for organic light-emitting devices. Highly efficient Alq3-based organic light emitting devices have been developed using phenanthrimidazoles as functional layers between NPB [4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl] and Alq3 [tris(8-hydroxyquinoline)aluminium] layers. Using the device of ITO/NPB/4/Alq3/LiF/Al, a maximum luminous efficiency of 5.99 cd A(-1) was obtained with a maximum brightness of 40,623 cd m(-2) and a power efficiency of 5.25 lm W(-1).

  17. Performance assessment of the disposal of vitrified high-level waste in a clay layer

    Mallants, Dirk; Marivoet, Jan; Sillen, Xavier

    2001-01-01

    Deep disposal is considered a safe solution to the management of high-level radioactive waste. The safety is usually demonstrated by means of a performance assessment. This paper discusses the methodological aspects and some of the results obtained for the performance assessment of the disposal of vitrified high-level waste in a clay layer in Belgium. The calculations consider radionuclide migration through the following multi-barrier components, all of which contribute to the overall safety: (1) engineered barriers and the host clay layer, (2) overlying aquifer, and (3) biosphere. The interfaces between aquifers and biosphere are limited to the well and river pathway. Results of the performance assessment calculations are given in terms of the time evolution of the dose rates of the most important fission and activation products and actinides. The role of the glass matrix in the overall performance of the repository is also discussed

  18. Method for the manufacture of a superconductive Nb3Sn layer on a niobium surface for high frequency applications

    Martens, H.

    1978-01-01

    A manufacturing method for depositing an Nb 3 Sn layer on a niobium surface for high frequency applications comprising developing a tin vapor atmosphere which also contains a highly volatile tin compound in the gaseous state, and holding the portions of the surface which are to be provided with the Nb 3 Sn layer at a temperature of between 900 0 and 1500 0 C for a predetermined period of time to form the Nb 3 Sn layer permitting niobium surfaces of any shape to be provided with Nb 3 Sn layers of high uniformity and quality

  19. Detection of extremely high bit density signals with a narrow track width GMR head in double layered perpendicular recording media

    Kiya, T.; Honda, N.; Ariake, J.; Ouchi, K.; Iwasaki, S.

    2001-01-01

    Recording resolution, medium noise and thermal stability have been investigated for double layered perpendicular magnetic recording media. The recording performance was improved by introducing a stacked intermediate layer between a soft magnetic backlayer and a storage layer due to increased crystal orientation with a small magnetic domain size and suppressed initial growing layer of the storage layer. The reproduced output at an extremely high linear density of 950 kFRPI was detected by using a contact-type CF-SPT head for write and a GMR head with a narrow read track width of 0.4 μm

  20. Study on coated layer material performance of coated particle fuel FBR (2). High temperature property and capability of coating to thick layer of TiN

    Naganuma, Masayuki; Mizuno, Tomoyasu

    2002-08-01

    'Helium Gas Cooled Coated Particle Fuel FBR' is one of attractive core concepts in the Feasibility Study on Commercialized Fast Reactor Cycle System in Japan, and the design study is presently proceeded. As one of key technologies of this concept, the coated layer material is important, and ceramics is considered to be a candidate material because of the superior refractory. Based on existing knowledge, TiN is regarded to be a possible candidate material, to which some property tests and evaluations have been conducted. In this study, preliminary tests about the high temperature property and the capability of thick layer coating of TiN have been conducted. Results of these tests come to the following conclusions. Heating tests of two kinds of TiN layer specimens coated by PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) were conducted. As a result, as for CVD coating specimens, remarkable charge was not observed on the layer up to 2,000degC, therefore we concluded that the layer by CVD had applicability up to high temperature of actual operation level. On the other hand, as for PVD coating specimens, an unstable behavior that the layer changed to a mesh like texture was observed on a 2,000degC heated specimen, therefore the applied PVD method is not considered to be promising as the coating technique. The surface conditions of some parts inside CVD device were investigated in order to evaluate possibility of TiN thick coating (∼100 μm). As a result, around 500 μm of TiN coating layer was observed on the condition of multilayer. Therefore, we conclude that CVD has capability of coating up to thick layer in actual coated particle fuel fabrication. (author)

  1. High Reynolds number rough wall turbulent boundary layer experiments using Braille surfaces

    Harris, Michael; Monty, Jason; Nova, Todd; Allen, James; Chong, Min

    2007-11-01

    This paper details smooth, transitional and fully rough turbulent boundary layer experiments in the New Mexico State high Reynolds number rough wall wind tunnel. The initial surface tested was generated with a Braille printer and consisted of an uniform array of Braille points. The average point height being 0.5mm, the spacing between the points in the span was 0.5mm and the surface consisted of span wise rows separated by 4mm. The wavelength to peak ratio was 8:1. The boundary layer thickness at the measurement location was 190mm giving a large separation of roughness height to layer thickness. The maximum friction velocity was uτ=1.5m/s at Rex=3.8 x10^7. Results for the skin friction co-efficient show that this surface follows a Nikuradse type inflectional curve and that Townsends outer layer similarity hypothesis is valid for rough wall flows with a large separation of scales. Mean flow and turbulence statistics will be presented.

  2. Effective deleting of residual photoconductivity in high-resistance layers GaAs

    Sadaev, B.S.; Kadirova, I.T.; Sharipov, E.I.

    2004-01-01

    Full text: The phenomenon of residual photoconductivity as the storage of optical memory (OM) represents practical interest in micro and optoelectronics. The finding - out of the nature OM represents undoubtedly and scientific interest. Now residual photoconductivity (RPC) is explained by potential barriers arising because of non-monocharacteristical of distribution components of the semiconductor or carriers of a current in volume. Depending on a nature non-monocharacteristical the time relaxation RPC changes in a wide limit. The special interest represents RPC created by impurity. In the given work the results of research of a nature RPC created photos by ionization of the filled centres of chrome in compensated epitaxilogic layers arsenide galls are resulted. Epitaxilogic layers were brought up by a vertical method ZFE. Highness was reached (achieved) by special indemnification of the residual donors deep acceptors of chrome. Substrates served n-GoAs. Lassitude of i-layers has made 70-80 microns. Specific resistance of layers has made (1/3) 108 om·sm. (T= 300 K). The structures were photosensitive as at low (T = 77 K) and at room temperatures. The photosensitivity of structures in impurity to a strip of absorption chrome (= 1,4 microns) was comparable (compared) with own. The researches show, that the structures have RPC. Size RPC the greatest ambassador impurity of illumination is carrying out photoionization Cr2 + - of the centres. That is established, RPC impurity of a photocurrent is effectively erased only at certain length of a wave of external illumination

  3. Trajectory of a synthetic jet issuing into a high Reynolds number turbulent boundary layer

    Berk, Tim; Baidya, Rio; de Silva, Charitha; Marusic, Ivan; Hutchins, Nicholas; Ganapathisubramani, Bharathram

    2017-11-01

    Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For several pulsed/synthetic jet in cross-flow applications the variation of the jet trajectory in the mean flow with jet and boundary layer parameters is important. This trajectory will provide an indication of the penetration depth of the pulsed/synthetic jet into a boundary layer. Trajectories of a synthetic jet in a turbulent boundary layer are measured for a range of actuation parameters in both low- and high Reynolds numbers (up to Reτ = 13000). The important parameters influencing the trajectory are determined from these measurements. The Reynolds number of the boundary layer is shown to only have a small effect on the trajectory. In fact, the critical parameters are found to be the Strouhal number of the jet based on jet dimensions as well as the velocity ratio of the jet (defined as a ratio between peak jet velocity and the freestream velocity). An expression for the trajectory of the synthetic (or pulsed) jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow. T.B. and B.G. are grateful to the support from the ERC (Grant Agreement No. 277472) and the EPSRC (Grant ref. no. EP/L006383/1).

  4. Attractive mechanical properties of a lightweight highly sensitive bi layer thermistor: polycarbonate/organic molecular conductor

    Laukhina, E; Lebedev, V; Rovira, C; Laukhin, V; Veciana, J

    2016-01-01

    The paper covers some of the basic mechanical characteristics of a recently developed bi layer thermistor: polycarbonate/(001) oriented layer of organic molecular conductor α’-(BEDT-TTF) 2 I x Br 3-x , were BEDT-TTF=bis(ethylenedithio)tetrathiafulvalen. The nano and macro mechanical properties have been studied in order to use this flexible, low cost thermistor in sensing applications by proper way. The nano-mechanical properties of the temperature sensitive semiconducting layer of α’-(BEDT-TTF) 2 I x Br 3-x were tested using nanoindentation method. The value of Young's modulus in direction being perpendicular to the layer plan was found as 9.0 ±1.4 GPa. The macro mechanical properties of the thermistor were studied using a 5848 MicroTester. The tensile tests showed that basic mechanical characteristics of the thermistor are close to those of polycarbonate films. This indicates a good mechanical strength of the developed sensor. Therefore, the thermistor can be used in technologies that need to be instrumented with highly robustness lightweight low cost temperature sensors. The paper also reports synthetic details on fabricating temperature sensing e-textile. As the temperature control is becoming more and more important in biomedical technologies like healthcare monitoring, this work strongly contributes on the ongoing research on engineering sensitive conducting materials for biomedical applications. (paper)

  5. A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations

    Jihan M Badr

    2013-01-01

    Background: Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. Materials and Method: In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Ha...

  6. A comparative study of near-wall turbulence in high and low Reynolds number boundary layers

    Metzger, M.M.; Klewicki, J.C.

    2001-01-01

    The present study explores the effects of Reynolds number, over three orders of magnitude, in the viscous wall region of a turbulent boundary layer. Complementary experiments were conducted both in the boundary layer wind tunnel at the University of Utah and in the atmospheric surface layer which flows over the salt flats of the Great Salt Lake Desert in western Utah. The Reynolds numbers, based on momentum deficit thickness, of the two flows were R θ =2x10 3 and R θ ≅5x10 6 , respectively. High-resolution velocity measurements were obtained from a five-element vertical rake of hot-wires spanning the buffer region. In both the low and high R θ flows, the length of the hot-wires measured less than 6 viscous units. To facilitate reliable comparisons, both the laboratory and field experiments employed the same instrumentation and procedures. Data indicate that, even in the immediate vicinity of the surface, strong influences from low-frequency motions at high R θ produce noticeable Reynolds number differences in the streamwise velocity and velocity gradient statistics. In particular, the peak value in the root mean square streamwise velocity profile, when normalized by viscous scales, was found to exhibit a logarithmic dependence on Reynolds number. The mean streamwise velocity profile, on the other hand, appears to be essentially independent of Reynolds number. Spectra and spatial correlation data suggest that low-frequency motions at high Reynolds number engender intensified local convection velocities which affect the structure of both the velocity and velocity gradient fields. Implications for turbulent production mechanisms and coherent motions in the buffer layer are discussed

  7. Preparation of Fe-Pt perpendicular double-layered media with high electric resistivity backlayer

    Uchida, Masaru; Suzuki, Toshio; Ouchi, Kazuhiro

    2001-01-01

    High electric resistivity materials, oxide-added Fe-Si, were investigated as a soft-magnetic backlayer for Fe-Pt perpendicular double-layered media. It was found that there is a possibility of using (Fe-Si)-MgO as a backlayer. To promote a hetero-epitaxial growth of ordered Fe-Pt FCT(0 0 1), the backlayer needed a BCC(2 0 0) crystal orientation, in a situation where surface topology also played an important role

  8. Dispersion engineering of thick high-Q silicon nitride ring-resonators via atomic layer deposition.

    Riemensberger, Johann; Hartinger, Klaus; Herr, Tobias; Brasch, Victor; Holzwarth, Ronald; Kippenberg, Tobias J

    2012-12-03

    We demonstrate dispersion engineering of integrated silicon nitride based ring resonators through conformal coating with hafnium dioxide deposited on top of the structures via atomic layer deposition. Both, magnitude and bandwidth of anomalous dispersion can be significantly increased. The results are confirmed by high resolution frequency-comb-assisted-diode-laser spectroscopy and are in very good agreement with the simulated modification of the mode spectrum.

  9. Ammonia and urea permeability of mammalian aquaporins

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    significant at alkaline pH. It is debated whether the H(+) ion passes via the aquaporin or by some external route; the investigation of this problem requires the aquaporin-expressing cell to be voltage-clamped. The ammonia-permeable aquaporins differ from other aquaporins by having a less restrictive aromatic...... groups differ in the amino acid composition of their aromatic/arginine regions. The location of the ammonia-permeable aquaporins in the body parallels that of the Rh proteins. This applies to erythrocytes and to cells associated with nitrogen homeostasis and high rates of anabolism. In the liver, AQPs 8...

  10. Atomic Layer Deposition of Nickel on ZnO Nanowire Arrays for High-Performance Supercapacitors.

    Ren, Qing-Hua; Zhang, Yan; Lu, Hong-Liang; Wang, Yong-Ping; Liu, Wen-Jun; Ji, Xin-Ming; Devi, Anjana; Jiang, An-Quan; Zhang, David Wei

    2018-01-10

    A novel hybrid core-shell structure of ZnO nanowires (NWs)/Ni as a pseudocapacitor electrode was successfully fabricated by atomic layer deposition of a nickel shell, and its capacitive performance was systemically investigated. Transmission electron microscopy and X-ray photoelectron spectroscopy results indicated that the NiO was formed at the interface between ZnO and Ni where the Ni was oxidized by ZnO during the ALD of the Ni layer. Electrochemical measurement results revealed that the Ti/ZnO NWs/Ni (1500 cycles) electrode with a 30 nm thick Ni-NiO shell layer had the best supercapacitor properties including ultrahigh specific capacitance (∼2440 F g -1 ), good rate capability (80.5%) under high current charge-discharge conditions, and a relatively better cycling stability (86.7% of the initial value remained after 750 cycles at 10 A g -1 ). These attractive capacitive behaviors are mainly attributed to the unique core-shell structure and the combined effect of ZnO NW arrays as short charge transfer pathways for ion diffusion and electron transfer as well as conductive Ni serving as channel for the fast electron transport to Ti substrate. This high-performance Ti/ZnO NWs/Ni hybrid structure is expected to be one of a promising electrodes for high-performance supercapacitor applications.

  11. Wake Instabilities Behind Discrete Roughness Elements in High Speed Boundary Layers

    Choudhari, Meelan; Li, Fei; Chang, Chau-Lyan; Norris, Andrew; Edwards, Jack

    2013-01-01

    Computations are performed to study the flow past an isolated, spanwise symmetric roughness element in zero pressure gradient boundary layers at Mach 3.5 and 5.9, with an emphasis on roughness heights of less than 55 percent of the local boundary layer thickness. The Mach 5.9 cases include flow conditions that are relevant to both ground facility experiments and high altitude flight ("cold wall" case). Regardless of the Mach number, the mean flow distortion due to the roughness element is characterized by long-lived streamwise streaks in the roughness wake, which can support instability modes that did not exist in the absence of the roughness element. The higher Mach number cases reveal a variety of instability mode shapes with velocity fluctuations concentrated in different localized regions of high base flow shear. The high shear regions vary from the top of a mushroom shaped structure characterizing the centerline streak to regions that are concentrated on the sides of the mushroom. Unlike the Mach 3.5 case with nearly same values of scaled roughness height k/delta and roughness height Reynolds number Re(sub kk), the odd wake modes in both Mach 5.9 cases are significantly more unstable than the even modes of instability. Additional computations for a Mach 3.5 boundary layer indicate that the presence of a roughness element can also enhance the amplification of first mode instabilities incident from upstream. Interactions between multiple roughness elements aligned along the flow direction are also explored.

  12. Nacre-Templated Synthesis of Highly Dispersible Carbon Nanomeshes for Layered Membranes with High-Flux Filtration and Sensing Properties.

    Kong, Meng; Li, Mingjie; Shang, Ruoxu; Wu, Jingyu; Yan, Peisong; Xu, Dongmei; Li, Chaoxu

    2018-01-24

    Marine shells not only represent a rapidly accumulating type of fishery wastes but also offer a unique sort of hybrid nanomaterials produced greenly and massively in nature. The elaborate "brick and mortar" structures of nacre enabled the synthesis of carbon nanomeshes with <1 nm thickness, hierarchical porosity, and high specific surface area through pyrolysis, in which two-dimensional (2D) organic layers served as the carbonaceous precursor and aragonite platelets as the hard template. Mineral bridges within 2D organic layers templated the formation of mesh pores of 20-70 nm. In contrast to other hydrophobic carbon nanomaterials, these carbon nanomeshes showed super dispersibility in diverse solvents and thus processability for membranes through filtration, patterning, spray-coating, and ink-writing. The carbon membranes with layered structures were capable of serving not only for high-flux filtration and continuous flow absorption but also for electrochemical and strain sensing with high sensitivity. Thus, utilization of marine shells, on one hand, relieves the environmental concern of shellfish waste, on the other hand, offers a facile, green, low-cost, and massive approach to synthesize unique carbon nanomeshes alternative to graphene nanomeshes and applicable in environmental adsorption, filtration, wearable sensors, and flexible microelectronics.

  13. Numerical Well Testing Interpretation Model and Applications in Crossflow Double-Layer Reservoirs by Polymer Flooding

    Haiyang Yu

    2014-01-01

    Full Text Available This work presents numerical well testing interpretation model and analysis techniques to evaluate formation by using pressure transient data acquired with logging tools in crossflow double-layer reservoirs by polymer flooding. A well testing model is established based on rheology experiments and by considering shear, diffusion, convection, inaccessible pore volume (IPV, permeability reduction, wellbore storage effect, and skin factors. The type curves were then developed based on this model, and parameter sensitivity is analyzed. Our research shows that the type curves have five segments with different flow status: (I wellbore storage section, (II intermediate flow section (transient section, (III mid-radial flow section, (IV crossflow section (from low permeability layer to high permeability layer, and (V systematic radial flow section. The polymer flooding field tests prove that our model can accurately determine formation parameters in crossflow double-layer reservoirs by polymer flooding. Moreover, formation damage caused by polymer flooding can also be evaluated by comparison of the interpreted permeability with initial layered permeability before polymer flooding. Comparison of the analysis of numerical solution based on flow mechanism with observed polymer flooding field test data highlights the potential for the application of this interpretation method in formation evaluation and enhanced oil recovery (EOR.

  14. High performance diamond-like carbon layers obtained by pulsed laser deposition for conductive electrode applications

    Stock, F.; Antoni, F.; Le Normand, F.; Muller, D.; Abdesselam, M.; Boubiche, N.; Komissarov, I.

    2017-09-01

    For the future, one of the biggest challenge faced to the technologies of flat panel display and various optoelectronic and photovoltaic devices is to find an alternative to the use of transparent conducting oxides like ITO. In this new approach, the objective is to grow high conductive thin-layer graphene (TLG) on the top of diamond-like carbon (DLC) layers presenting high performance. DLC prepared by pulsed laser deposition (PLD) have attracted special interest due to a unique combination of their properties, close to those of monocrystalline diamond, like its transparency, hardness and chemical inertia, very low roughness, hydrogen-free and thus high thermal stability up to 1000 K. In our future work, we plane to explore the synthesis of conductive TLG on top of insulating DLC thin films. The feasibility and obtained performances of the multi-layered structure will be explored in great details in the short future to develop an alternative to ITO with comparable performance (conductivity of transparency). To select the best DLC candidate for this purpose, we focus this work on the physicochemical properties of the DLC thin films deposited by PLD from a pure graphite target at two wavelengths (193 and 248 nm) at various laser fluences. A surface graphenization process, as well as the required efficiency of the complete structure (TLG/DLC) will clearly be related to the DLC properties, especially to the initial sp3/sp2 hybridization ratio. Thus, an exhaustive description of the physicochemical properties of the DLC layers is a fundamental step in the research of comparable performance to ITO.

  15. Drag reduction using wrinkled surfaces in high Reynolds number laminar boundary layer flows

    Raayai-Ardakani, Shabnam; McKinley, Gareth H.

    2017-09-01

    Inspired by the design of the ribbed structure of shark skin, passive drag reduction methods using stream-wise riblet surfaces have previously been developed and tested over a wide range of flow conditions. Such textures aligned in the flow direction have been shown to be able to reduce skin friction drag by 4%-8%. Here, we explore the effects of periodic sinusoidal riblet surfaces aligned in the flow direction (also known as a "wrinkled" texture) on the evolution of a laminar boundary layer flow. Using numerical analysis with the open source Computational Fluid Dynamics solver OpenFOAM, boundary layer flow over sinusoidal wrinkled plates with a range of wavelength to plate length ratios ( λ / L ), aspect ratios ( 2 A / λ ), and inlet velocities are examined. It is shown that in the laminar boundary layer regime, the riblets are able to retard the viscous flow inside the grooves creating a cushion of stagnant fluid that the high-speed fluid above can partially slide over, thus reducing the shear stress inside the grooves and the total integrated viscous drag force on the plate. Additionally, we explore how the boundary layer thickness, local average shear stress distribution, and total drag force on the wrinkled plate vary with the aspect ratio of the riblets as well as the length of the plate. We show that riblets with an aspect ratio of close to unity lead to the highest reduction in the total drag, and that because of the interplay between the local stress distribution on the plate and stream-wise evolution of the boundary layer the plate has to exceed a critical length to give a net decrease in the total drag force.

  16. High Enthalpy Effects on Two Boundary Layer Disturbances in Supersonic and Hypersonic Flow

    Wagnild, Ross Martin

    The fluid flow phenomenon of boundary layer transition is a complicated and difficult process to model and predict. The importance of the state of the boundary layer with regard to vehicle design cannot be understated. The high enthalpy environment in which high speed vehicles operate in further complicates the transition process by adding several more degrees of freedom. In this environment, the internal properties of the gas can stabilize or destabilize the boundary layer as well as modify the disturbances that cause transition. In the current work, the interaction of two types of disturbances with the high enthalpy flow environment are analyzed. The first is known as a second mode disturbance, which is acoustic in nature. The second type is known as a transient growth disturbance and is associated with flows behind roughness elements. Theoretical analyses, linear stability analyses, and computation fluid dynamics (CFD) are used to determine the ways in which these disturbances interact with the high enthalpy environment as well as the consequences of these interactions. First, acoustic wave are directly studied in order to gain a basic understanding of the response of second mode disturbances in the high enthalpy boundary layer. Next, this understanding is used in interpreting the results of several computations attempting to simulate the flow through a high enthalpy flow facility as well as experiments attempting to take advantage of the acoustic interaction with the high enthalpy environment. Because of the difficulty in modeling these experiments, direct simulations of acoustic waves in a hypersonic flow of a gas with molecular vibration are performed. Lastly, compressible transient growth disturbances are simulated using a linear optimal disturbance solver as well as a CFD solver. The effect of an internal molecular process on this type of disturbance is tested through the use of a vibrational mode. It is the goal of the current work to reinforce the

  17. High temperature study on the thermal properties of few-layer Mo0.5W0.5S2 and effects of capping layers

    Hong Gu

    Full Text Available We investigated the thermal properties of few-layer Mo0.5W0.5S2 using a series of samples with different kinds of capping layers. Temperature-dependent Raman measurements were conducted in the range of 300–500 K, with power-dependent measurements also carried out. It indicated, for the few-layer Mo0.5W0.5S2, the temperature coefficients of the WS2-like E12g mode, MoS2-like E12g mode and A1g mode were −0.0155 cm−1/K, −0.0146 cm−1/K, and −0.0130 cm−1/K, respectively. And the thermal conductivity was estimated to be 44.8 W/mK. Moreover, the Mo0.5W0.5S2 samples coated with capping layers (ZrO2, HfO2 both showed a better thermal stability and a larger thermal conductivity than the one without. The results revealed that the capping layer should be an important factor in the thermal property. Keywords: Mo0.5W0.5S2, TMDs, Thermal properties, High temperature, Capping layers, Raman

  18. Determination of hydrogen permeability in uncoated and coated superalloys

    Bhattacharyya, S.; Vesely, E. J., Jr.; Hill, V. L.

    1981-01-01

    Hydrogen permeability, diffusivity, and solubility data were obtained for eight wrought and cast high temperature alloys over the range 650 to 815 C. Data were obtained for both uncoated alloys and wrought alloys coated with four commercially available coatings. Activation energies for permeability, diffusivity and solubility were calculated.

  19. CBE growth of high-quality ZnO epitaxial layers

    El-Shaer, A.; Bakin, A.; Mofor, A.C.; Kreye, M.; Waag, A. [Institute of Semiconductor Technology, Technical University Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany); Blaesing, J.; Krost, A. [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Stoimenos, J. [Physics Department, Aristotele University, Univ. Campus, 54006 Thessaloniki (Greece); Pecz, B. [Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary); Heuken, M. [Aixtron AG, Kackertstr. 15-17, 52072 Aachen (Germany)

    2006-03-15

    Further improvements on the recently reported novel approach to zinc oxide Chemical Beam Epitaxy (CBE) are presented. Hydrogen peroxide is employed as a very efficient novel oxidant. ZnO layers with a thickness from 100 nm to 600 nm were grown on c-sapphire using a MgO buffer. PL-mapping as well as conductivity mapping shows a good uniformity across the 2 inch ZnO-on-sapphire epiwafers. The measured surface roughness for the best layers is as low as 0.26 nm. HRXRD measurements of the obtained ZnO layers show excellent quality of the single crystalline ZnO. The FWHM of the HRXRD (0002) rocking curves measured for the 2 inch ZnO-on-sapphire wafers is as low as 27 arcsec with a very high lateral homogeneity across the whole wafer. Plane view HRTEM observations reveal the very good quality of the ZnO films. The results indicate that CBE is a suitable technique to fabricate ZnO of very high structural quality, which can eventually be used as an alternative to bulk ZnO substrates. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Thermal and hydrodynamic study of a whirling liquid hydrogen layer under high heat flux

    Ewald, R.

    1969-01-01

    In order to achieve a cold neutrons source (λ ≥ 4.10 -10 m) in a high flux reactor (∼ 10 15 neutrons/cm 2 .s), a whirling liquid hydrogen layer (145 mm OD, effective thickness 15 mm, height about 180 mm) was formed, out-of-pile, in a cylindrical transparent glass vessel. The whirling motion was obtained by tangential injection of the liquid, near the wall. Thermal and hydrodynamical conditions of formation and laws of similarity of such a layer were studied. The characteristics of this whirling flow were observed as a function of mass flow rate (5 to 27 g/s; 4.3 to 23 l/mn), and of spillway width (18 and 25 mm). Six different nozzles were used : 1.0; 1.5; 1.9; 2.25; 2.65 and 3.0 mm ID. The total heat influx was found between 8.6 and 10.4 kW. The heat flux density was about 9.4 W/cm 2 and the mean layer density around 80 per cent of that of the liquid hydrogen at 20.4 Kelvin. High speed movies were used to analyze the boiling regime. (author) [fr

  1. Diffractive intermediate layer enables broadband light trapping for high efficiency ultrathin c-Si tandem cells

    Li, Guijun, E-mail: gliad@connect.ust.hk; Ho, Jacob Y. L.; Li, He; Kwok, Hoi-Sing [State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2014-06-09

    Light management through the intermediate reflector in the tandem cell configuration is of great practical importance for achieving high stable efficiency and also low cost production. So far, however, the intermediate reflectors employed currently are mainly focused on the light absorption enhancement of the top cell. Here, we present a diffractive intermediate layer that allows for light trapping over a broadband wavelength for the ultrathin c-Si tandem solar cell. Compared with the standard intermediate reflector, this nanoscale architectural intermediate layer results in a 35% and 21% remarkable enhancement of the light absorption in the top (400–800 nm) and bottom (800–1100 nm) cells simultaneously, and ultrathin c-Si tandem cells with impressive conversion efficiency of 13.3% are made on the glass substrate.

  2. Diffractive intermediate layer enables broadband light trapping for high efficiency ultrathin c-Si tandem cells

    Li, Guijun; Ho, Jacob Y. L.; Li, He; Kwok, Hoi-Sing

    2014-01-01

    Light management through the intermediate reflector in the tandem cell configuration is of great practical importance for achieving high stable efficiency and also low cost production. So far, however, the intermediate reflectors employed currently are mainly focused on the light absorption enhancement of the top cell. Here, we present a diffractive intermediate layer that allows for light trapping over a broadband wavelength for the ultrathin c-Si tandem solar cell. Compared with the standard intermediate reflector, this nanoscale architectural intermediate layer results in a 35% and 21% remarkable enhancement of the light absorption in the top (400–800 nm) and bottom (800–1100 nm) cells simultaneously, and ultrathin c-Si tandem cells with impressive conversion efficiency of 13.3% are made on the glass substrate.

  3. Few-layer molybdenum disulfide transistors and circuits for high-speed flexible electronics

    Cheng, Rui; Jiang, Shan; Chen, Yu; Liu, Yuan; Weiss, Nathan; Cheng, Hung-Chieh; Wu, Hao; Huang, Yu; Duan, Xiangfeng

    2014-01-01

    Two-dimensional layered materials, such as molybdenum disulfide, are emerging as an exciting material system for future electronics due to their unique electronic properties and atomically thin geometry. Here we report a systematic investigation of MoS2 transistors with optimized contact and device geometry, to achieve self-aligned devices with performance including an intrinsic gain over 30, an intrinsic cut-off frequency fT up to 42 GHz and a maximum oscillation frequency fMAX up to 50 GHz, exceeding the reported values for MoS2 transistors to date (fT ~ 0.9 GHz, fMAX ~ 1 GHz). Our results show that logic inverters or radio frequency amplifiers can be formed by integrating multiple MoS2 transistors on quartz or flexible substrates with voltage gain in the gigahertz regime. This study demonstrates the potential of two-dimensional layered semiconductors for high-speed flexible electronics. PMID:25295573

  4. Measurement of relative permeability of fuel cell diffusion media

    Hussaini, I.S.

    2010-06-01

    Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented and new correlations for in-plane relative permeability of water and air are established. © 2010 Elsevier B.V. All rights reserved.

  5. A Highly Expressed High-Molecular-Weight S-Layer Complex of Pelosinus sp. Strain UFO1 Binds Uranium

    Thorgersen, Michael P. [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology; Lancaster, W. Andrew [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology; Rajeev, Lara [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Biological Systems and Engineering Division; Ge, Xiaoxuan [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology; Vaccaro, Brian J. [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology; Poole, Farris L. [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology; Arkin, Adam P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Biological Systems and Engineering Division; Mukhopadhyay, Aindrila [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Biological Systems and Engineering Division; Adams, Michael W. W. [Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology

    2016-12-02

    Cell suspensions of Pelosinus sp. strain UFO1 were previously shown, using spectroscopic analysis, to sequester uranium as U(IV) complexed with carboxyl and phosphoryl group ligands on proteins. The goal of our present study was to characterize the proteins involved in uranium binding. Virtually all of the uranium in UFO1 cells was associated with a heterodimeric protein, which was termed the uranium-binding complex (UBC). The UBC was composed of two S-layer domain proteins encoded by UFO1_4202 and UFO1_4203. Samples of UBC purified from the membrane fraction contained 3.3 U atoms/heterodimer, but significant amounts of phosphate were not detected. The UBC had an estimated molecular mass by gel filtration chromatography of 15 MDa, and it was proposed to contain 150 heterodimers (UFO1_4203 and UFO1_4202) and about 500 uranium atoms. The UBC was also the dominant extracellular protein, but when purified from the growth medium, it contained only 0.3 U atoms/heterodimer. The two genes encoding the UBC were among the most highly expressed genes within the UFO1 genome, and their expressions were unchanged by the presence or absence of uranium. Therefore, the UBC appears to be constitutively expressed and is the first line of defense against uranium, including by secretion into the extracellular medium. Although S-layer proteins were previously shown to bind U(VI), here we showed that U(IV) binds to S-layer proteins, we identified the proteins involved, and we quantitated the amount of uranium bound. Widespread uranium contamination from industrial sources poses hazards to human health and to the environment. Here in this paper, we identified a highly abundant uranium-binding complex (UBC) from Pelosinus sp. strain UFO1. The complex makes up the primary protein component of the S-layer of strain UFO1 and binds 3.3 atoms of U(IV) per heterodimer. Finally, while other bacteria have been shown to bind U(VI) on their S-layer, we demonstrate here an example of U(IV) bound by

  6. Experiments on the flow field physics of confluent boundary layers for high-lift systems

    Nelson, Robert C.; Thomas, F. O.; Chu, H. C.

    1994-01-01

    The use of sub-scale wind tunnel test data to predict the behavior of commercial transport high lift systems at in-flight Reynolds number is limited by the so-called 'inverse Reynolds number effect'. This involves an actual deterioration in the performance of a high lift device with increasing Reynolds number. A lack of understanding of the relevant flow field physics associated with numerous complicated viscous flow interactions that characterize flow over high-lift devices prohibits computational fluid dynamics from addressing Reynolds number effects. Clearly there is a need for research that has as its objective the clarification of the fundamental flow field physics associated with viscous effects in high lift systems. In this investigation, a detailed experimental investigation is being performed to study the interaction between the slat wake and the boundary layer on the primary airfoil which is known as a confluent boundary layer. This little-studied aspect of the multi-element airfoil problem deserves special attention due to its importance in the lift augmentation process. The goal of this research is is to provide an improved understanding of the flow physics associated with high lift generation. This process report will discuss the status of the research being conducted at the Hessert Center for Aerospace Research at the University of Notre Dame. The research is sponsored by NASA Ames Research Center under NASA grant NAG2-905. The report will include a discussion of the models that have been built or that are under construction, a description of the planned experiments, a description of a flow visualization apparatus that has been developed for generating colored smoke for confluent boundary layer studies and some preliminary measurements made using our new 3-component fiber optic LDV system.

  7. Observations of high droplet number concentrations in Southern Ocean boundary layer clouds

    T. Chubb

    2016-01-01

    Full Text Available Cloud physics data collected during the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER Pole-to-Pole Observations (HIPPO campaigns provide a snapshot of unusual wintertime microphysical conditions in the boundary layer over the Southern Ocean. On 29 June 2011, the HIAPER sampled the boundary layer in a region of pre-frontal warm air advection between 58 and 48° S to the south of Tasmania. Cloud droplet number concentrations were consistent with climatological values in the northernmost profiles but were exceptionally high for wintertime in the Southern Ocean at 100–200 cm−3 in the southernmost profiles. Sub-micron (0.06  < D <  1 µm aerosol concentrations for the southern profiles were up to 400 cm−3. Analysis of back trajectories and atmospheric chemistry observations revealed that while conditions in the troposphere were more typical of a clean remote ocean airmass, there was some evidence of continental or anthropogenic influence. However, the hypothesis of long-range transport of continental aerosol fails to explain the magnitude of the aerosol and cloud droplet concentration in the boundary layer. Instead, the gale force surface winds in this case (wind speed at 167 m above sea level was  > 25 m s−1 were most likely responsible for production of sea spray aerosol which influenced the microphysical properties of the boundary layer clouds. The smaller size and higher number concentration of cloud droplets is inferred to increase the albedo of these clouds, and these conditions occur regularly, and are expected to increase in frequency, over windy parts of the Southern Ocean.

  8. Research on High Layer Thickness Fabricated of 316L by Selective Laser Melting

    Shuo Wang

    2017-09-01

    Full Text Available Selective laser melting (SLM is a potential additive manufacturing (AM technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 μs-40 μm-240 μm. Also, the building rate can be up to 12 mm3/s, which is about 3–10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 μs to 200 μs, the grain size is gradually grown up from 0.98 μm to 2.23 μm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.

  9. High energy density layered-spinel hybrid cathodes for lithium ion rechargeable batteries

    Basu, S., E-mail: sbasumajumder@yahoo.com [Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721 302 (India); Dahiya, P.P.; Akhtar, Mainul [Materials Science Center, Indian Institute of Technology Kharagpur, Kharagpur 721 302 (India); Ray, S.K. [Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721 302 (India); Chang, J.K. [Institute of Materials Science and Engineering, National Central University, Taiwan (China); Majumder, S.B. [Materials Science Center, Indian Institute of Technology Kharagpur, Kharagpur 721 302 (India)

    2016-11-15

    Highlights: • Structural integration of layered domains in spinel matrix of the composite particles. • Highest discharge capacity (275 mAh g{sup −1}) in composite with 30.0 mole% Li{sub 2}MnO{sub 3}. • Reasonably good rate capability of layered-spinel composite cathode. • Capacity fading with cycling is related to cubic to tetragonal structural phase transition. - Abstract: High energy density Li{sub 2}MnO{sub 3} (layered)–LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} (spinel) composite cathodes have been synthesized using auto-combustion route. Rietveld refinements together with the analyses of high resolution transmission electron micrographs confirm the structural integration of Li{sub 2}MnO{sub 3} nano-domains into the LiMn{sub 1.5}Ni{sub 0.5}O{sub 4} matrix of the composite cathodes. The discharge capacity of the composite cathodes are due to the intercalation of Li{sup +} ion in the tetrahedral (8a) and octahedral (16c) sites of the spinel component and also the insertion of Li{sup +} in the freshly prepared MnO{sub 2} lattice, formed after Li{sub 2}O extraction from the Li{sub 2}MnO{sub 3} domains. The capacity fading of the composite cathodes are explained to be due to the layered to spinel transition of the Li{sub 2}MnO{sub 3} component and Li{sup +} insertion into the octahedral site of the spinel lattices which trigger cubic to tetragonal phase transition resulting volume expansion which eventually retard the Li{sup +} intercalation with cycling.

  10. Smooth- and rough-wall boundary layer structure from high spatial range particle image velocimetry

    Squire, D. T.; Morrill-Winter, C.; Hutchins, N.; Marusic, I.; Schultz, M. P.; Klewicki, J. C.

    2016-10-01

    Two particle image velocimetry arrangements are used to make true spatial comparisons between smooth- and rough-wall boundary layers at high Reynolds numbers across a very wide range of streamwise scales. Together, the arrangements resolve scales ranging from motions on the order of the Kolmogorov microscale to those longer than twice the boundary layer thickness. The rough-wall experiments were obtained above a continuous sandpaper sheet, identical to that used by Squire et al. [J. Fluid Mech. 795, 210 (2016), 10.1017/jfm.2016.196], and cover a range of friction and equivalent sand-grain roughness Reynolds numbers (12 000 ≲δ+≲ 18000, 62 ≲ks+≲104 ). The smooth-wall experiments comprise new and previously published data spanning 6500 ≲δ+≲17 000 . Flow statistics from all experiments show similar Reynolds number trends and behaviors to recent, well-resolved hot-wire anemometry measurements above the same rough surface. Comparisons, at matched δ+, between smooth- and rough-wall two-point correlation maps and two-point magnitude-squared coherence maps demonstrate that spatially the outer region of the boundary layer is the same between the two flows. This is apparently true even at wall-normal locations where the total (inner-normalized) energy differs between the smooth and rough wall. Generally, the present results provide strong support for Townsend's [The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, 1956), Vol. 1] wall-similarity hypothesis in high Reynolds number fully rough boundary layer flows.

  11. Research on High Layer Thickness Fabricated of 316L by Selective Laser Melting.

    Wang, Shuo; Liu, Yude; Shi, Wentian; Qi, Bin; Yang, Jin; Zhang, Feifei; Han, Dong; Ma, Yingyi

    2017-09-08

    Selective laser melting (SLM) is a potential additive manufacturing (AM) technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 μs-40 μm-240 μm. Also, the building rate can be up to 12 mm³/s, which is about 3-10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 μs to 200 μs, the grain size is gradually grown up from 0.98 μm to 2.23 μm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.

  12. Formation of high aspect ratio polyamide-6 nanofibers via electrically induced double layer during electrospinning

    Nirmala, R.; Nam, Ki Taek; Park, Soo-Jin; Shin, Yu-Shik; Navamathavan, R.; Kim, Hak Yong

    2010-01-01

    In the present study, the formation of high aspect ratio nanofibers in polyamide-6 was investigated as a function of applied voltage ranging from 15 to 25 kV using electrospinning technique. All other experimental parameters were kept constant. The electrospun polyamide-6 nanofibers were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF). FE-SEM images of polyamide-6 nanofibers showed that the diameter of the electrospun fiber was decreased with increasing applied voltage. At the critical applied voltage, the polymer solution was completely ionized to form the dense high aspect ratio nanofibers in between the main nanofibers. The diameter of the polyamide-6 nanofibers was observed to be in the range of 75-110 nm, whereas the high aspect ratio structures consisted of regularly distributed very fine nanofibers with diameters of about 9-28 nm. Trends in fiber diameter and diameter distribution were discussed for the high aspect ratio nanofibers. TEM results revealed that the formation of double layers in polyamide-6 nanofibers and then split-up into ultrafine fibers. The electrically induced double layer in combination with the polyelectrolytic nature of solution is proposed as the suitable mechanisms for the formation of high aspect ratio nanofibers in polyamide-6.

  13. Organic contaminant removal efficiency of sodium bentonite/clay (BC) mixtures in high permeability regions utilizing reclaimed wastewater: A meso-scale study

    Xiao, Yang; Li, Yunkai; Ning, Zigong; Li, Pengxiang; Yang, Peiling; Liu, Chengcheng; Liu, Zhongwei; Xu, Feipeng; Hynds, Paul Dylan

    2018-03-01

    Wastewater reclamation now represents an effective measure for sustainable water resource management in arid regions, however wastewater components (organic micropollutants) may potentially impact local ecological and/or human health. Previous studies have shown that sodium bentonite/natural clay (BC) mixes may be used to effectively reduce riverbed infiltration in regions characterized by excessively high hydraulic conductivity. Accordingly, the current study sought to investigate the contaminant removal efficiency (Re) of several BC mass ratios in simulated dry riverbeds. Results indicate that the measured Re of NH4+-N, CODcr and BOD5 increased in concurrence with an increasing sodium bentonite ratio, up to a maximum Re of 97.4% (NH4+-N), 55.2% (CODcr), and 51.5% (BOD5). The primary contaminant removal site was shown to be the infiltration-reducing (BC) layer, accounting for approximately 40%, 60%, and 70% of NH4+-N, CODcr and BOD5 removal, respectively. Conversely, the removal efficiency of NO3-N was found to be low (managing recharge of non-potable aquifers with reclaimed wastewater.

  14. In situ permeable flow sensors at the Savannah River Integrated Demonstration: Phase 2 results

    Ballard, S.

    1994-08-01

    A suite of In Situ Permeable Flow Sensors was deployed at the site of the Savannah River Integrated Demonstration to monitor the interaction between the groundwater flow regime and air injected into the saturated subsurface through a horizontal well. One of the goals of the experiment was to determine if a groundwater circulation system was induced by the air injection process. The data suggest that no such circulation system was established, perhaps due to the heterogeneous nature of the sediments through which the injected gas has to travel. The steady state and transient groundwater flow patterns observed suggest that the injected air followed high permeability pathways from the injection well to the water table. The preferential pathways through the essentially horizontal impermeable layers appear to have been created by drilling activities at the site

  15. Steady flow in voids and closed cracks in permeable media

    Rae, J.

    1985-03-01

    This paper considers what happens when a steady flow in a permeable medium meets two concentric spheres which have different permeabilities. This can form a first stage model for water flow near an engineered cavity in rock or a concreted waste package placed in filler material as in a nuclear waste repository. Results are obtained in terms of the simplest spherical harmonics, which lets them be used easily. Included are the well-known result that a highly permeable sphere will see only a few times the flux which would occur if it had the permeability of its surroundings, and the less well-known result, though unsurprising, that a spherical region surrounded by a highly permeable shell will see almost no flow, as it will almost all by-pass. A companion paper will include more geometrical effects by replacing the spheres by ellipsoids. (author)

  16. Nonlinear electron acoustic structures generated on the high-potential side of a double layer

    R. Pottelette

    2009-04-01

    Full Text Available High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30% of the total electron density. As compared to the background hot electron population, this trapped component has a very cold temperature in the direction parallel to the static magnetic field. Accordingly, the differential drift between the trapped and background hot electron populations generates high frequency electron acoustic waves in a direction quasi-parallel to the magnetic field. The density of the trapped electron population can be deduced from the frequency where the electron acoustic spectrum maximizes. In the auroral midcavity region, the electron acoustic waves may be modulated by an additional turbulence generated in the ion acoustic range thanks to the presence of a pre-accelerated ion beam located on the high-potential side of the double layer. Electron holes characterized by bipolar pulses in the electric field are sometimes detected in correlation with these electron acoustic wave packets.

  17. High-Quality Ultrathin Gold Layers For Use In Plasmonic And Metamaterials Applications

    Sukham, Johneph; Takayama, Osamu; Lavrinenko, Andrei

    2018-01-01

    The propagation of electromagnetic waves can be manipulated at the nanoscale by surface plasmons supported by ultra thin metal layers. An adhesion layer, with thickness in the order of few nanometerss is used for depositing ultra thin metal gold layers. Cr and Ti are the most popular metallic...... adhesion layers. Apart from them, a non metallic silane based wetting layer like (3-Aminopropyl)trimethoxysilane (APTMS) can be used. The behaviour of the propagating surface plasmons due to the influence of these adhesion layers has not been thoroughly investigated. To study the influence of the adhesion...... layers on propagating plasmons for use in plasmonic and metamaterial applications,we experimentally compared the performances of the ultra-thin gold layers using Cr and APTMS adhesion layers and without any adhesion layer. We show that the gold layers using APTMS adhesion exhibit short range surface...

  18. Synthetic Rock Analogue for Permeability Studies of Rock Salt with Mudstone

    Hongwu Yin

    2017-09-01

    Full Text Available Knowledge about the permeability of surrounding rock (salt rock and mudstone interlayer is an important topic, which acts as a key parameter to characterize the tightness of gas storage. The goal of experiments that test the permeability of gas storage facilities in rock salt is to develop a synthetic analogue to use as a permeability model. To address the permeability of a mudstone/salt layered and mixed rock mass in Jintan, Jiangsu Province, synthetic mixed and layered specimens using the mudstone and the salt were fabricated for permeability testing. Because of the gas “slippage effect”, test results are corrected by the Klinkenberg method, and the permeability of specimens is obtained by regression fitting. The results show that the permeability of synthetic pure rock salt is 6.9 × 10−20 m2, and its porosity is 3.8%. The permeability of synthetic mudstone rock is 2.97 × 10−18 m2, with a porosity 17.8%. These results are close to those obtained from intact natural specimens. We also find that with the same mudstone content, the permeability of mixed specimens is about 40% higher than for the layered specimens, and with an increase in the mudstone content, the Klinkenberg permeability increases for both types of specimens. The permeability and mudstone content have a strong exponential relationship. When the mudstone content is below 40%, the permeability increases only slightly with mudstone content, whereas above this threshold, the permeability increases rapidly with mudstone content. The results of the study are of use in the assessment of the tightness of natural gas storage facilities in mudstone-rich rock salt formations in China.

  19. Permeability of different size waste particles

    Sabina Gavelytė

    2015-10-01

    Full Text Available The world and life style is changing, but the most popular disposal route for waste is landfill globally until now. We have to think about waste prevention and preparing for re-use or recycling firstly, according to the waste disposal hierarchy. Disposed waste to the landfill must be the last opportunity. In a landfill, during waste degradation processes leachate is formed that can potentially cause clogging of bottom drainage layers. To ensure stability of a landfill construction, the physical properties of its components have to be controlled. The hydrology of precipitation, evaporation, runoff and the hydraulic performance of the capping and liner materials are important controls of the moisture content. The water balance depends also on the waste characteristics and waste particle size distribution. The aim of this paper is to determine the hydraulic permeability in a landfill depending on the particle size distribution of municipal solid waste disposed. The lab experiment results were compared with the results calculated with DEGAS model. Samples were taken from a landfill operated for five years. The samples particle sizes are: >100 mm, 80 mm, 60 mm, 40 mm, 20 mm, 0.01 mm and <0.01 mm. The permeability test was conducted using the column test. The paper presents the results of experiment and DEGAS model water permeability with waste particle size.

  20. High performance EUV multilayer structures insensitive to capping layer optical parameters.

    Pelizzo, Maria Guglielmina; Suman, Michele; Monaco, Gianni; Nicolosi, Piergiorgio; Windt, David L

    2008-09-15

    We have designed and tested a-periodic multilayer structures containing protective capping layers in order to obtain improved stability with respect to any possible changes of the capping layer optical properties (due to oxidation and contamination, for example)-while simultaneously maximizing the EUV reflection efficiency for specific applications, and in particular for EUV lithography. Such coatings may be particularly useful in EUV lithographic apparatus, because they provide both high integrated photon flux and higher stability to the harsh operating environment, which can affect seriously the performance of the multilayer-coated projector system optics. In this work, an evolutive algorithm has been developed in order to design these a-periodic structures, which have been proven to have also the property of stable performance with respect to random layer thickness errors that might occur during coating deposition. Prototypes have been fabricated, and tested with EUV and X-ray reflectometry, and secondary electron spectroscopy. The experimental results clearly show improved performance of our new a-periodic coatings design compared with standard periodic multilayer structures.

  1. Organic-Inorganic Hybrid Interfacial Layer for High-Performance Planar Perovskite Solar Cells.

    Yang, Hao; Cong, Shan; Lou, Yanhui; Han, Liang; Zhao, Jie; Sun, Yinghui; Zou, Guifu

    2017-09-20

    4,7-Diphenyl-1,10-phenanthroline (Bphen) is an efficient electron transport and hole blocking material in organic photoelectric devices. Here, we report cesium carbonate (Cs 2 CO 3 ) doped Bphen as cathode interfacial layer in CH 3 NH 3 PbI 3-x Cl x based planar perovskite solar cells (PSCs). Investigation finds that introducing Cs 2 CO 3 suppresses the crystallization of Bphen and benefits a smooth interface contact between the perovskite and electrode, resulting in the decrease in carrier recombination and the perovskite degradation. In addition, the matching energy level of Bphen film in the PSCs effectively blocks the holes diffusion to cathode. The resultant power conversion efficiency (PCE) achieves as high as 17.03% in comparison with 12.67% of reference device without doping. Besides, experiments also demonstrate the stability of PSCs have large improvement because the suppressed crystallization of Bphen by doping Cs 2 CO 3 as a superior barrier layer blocks the Ag atom and surrounding moisture access to the vulnerable perovskite layer.

  2. Impact of thickness on the structural properties of high tin content GeSn layers

    Aubin, J.; Hartmann, J. M.; Gassenq, A.; Milord, L.; Pauc, N.; Reboud, V.; Calvo, V.

    2017-09-01

    We have grown various thicknesses of GeSn layers in a 200 mm industrial Reduced Pressure - Chemical Vapor Deposition cluster tool using digermane (Ge2H6) and tin tetrachloride (SnCl4). The growth pressure (100 Torr) and the F(Ge2H6)/F(SnCl4) mass-flow ratio were kept constant, and incorporation of tin in the range of 10-15% was achieved with a reduction in temperature: 325 °C for 10% to 301 °C for 15% of Sn. The layers were grown on 2.5 μm thick Ge Strain Relaxed Buffers, themselves on Si(0 0 1) substrates. We used X-ray Diffraction, Atomic Force Microscopy, Raman spectroscopy and Scanning Electron Microscopy to measure the Sn concentration, the strain state, the surface roughness and thickness as a function of growth duration. A dramatic degradation of the film was seen when the Sn concentration and layer thickness were too high resulting in rough/milky surfaces and significant Sn segregation.

  3. High bandwidth pixel detector modules for the ATLAS Insertable B-Layer

    Backhaus, Malte

    2014-01-01

    The investigation of the nature of the recently discovered electro-weak symmetry breaking mechanism of the standard model of particle physics as well as the search for physics beyond the standard model with the LHC require to collect even more data. To achieve this goal, the luminosity of the LHC will be increased in two steps. The increased luminosity results in serious challenges for the inner tracking systems of the experiments at the LHC. The ATLAS pixel detector will also be upgraded in a two stage program. During the shutdown in 2013 and 2014 a fourth hybrid pixel detector layer, the socalled Insertable B-Layer (IBL) is inserted inside the existing pixel detector. This thesis focuses on the characterization, performance measurement, and production quality assurance of the central sensitive elements of the IBL, the modules. This includes a full characterization of the readout chip (FE-I4) and of the assembled modules. A completely new inner tracking system is mandatory in ATLAS after the second luminosity increase in the shutdown of 2022 and 2023. The final chapter of this thesis introduces a new module concept that uses an industrial high voltage CMOS technology as sensor layer, which is capacitively coupled to the FE-I4 readout chip.

  4. Neutral wetting brush layers for block copolymer thin films using homopolymer blends processed at high temperatures

    Ceresoli, M; Palermo, M; Ferrarese Lupi, F; Seguini, G; Perego, M; Zuccheri, G; Phadatare, S D; Antonioli, D; Gianotti, V; Sparnacci, K; Laus, M

    2015-01-01

    Binary homopolymer blends of two hydroxyl-terminated polystyrene (PS-OH) and polymethylmethacrylate (PMMA-OH) homopolymers (Mn ∼ 16000 g mol"−"1) were grafted on SiO_2 substrates by high-temperature (T > 150 °C), short-time (t < 600 s) thermal treatments. The resulting brush layer was tested to screen preferential interactions of the SiO_2 substrate with the different symmetric and asymmetric PS-b-PMMA block copolymers deposited on top of the grafted molecules. By properly adjusting the blend composition and the processing parameters, an efficient surface neutralization path was identified, enabling the formation, in the block copolymer film, of homogeneous textures of lamellae or cylinders perpendicularly oriented with respect to the substrate. A critical interplay between the phase segregation of the homopolymer blends and their grafting process on the SiO_2 was observed. In fact, the polar SiO_2 is preferential for the PMMA-rich phase that forms a homogeneous layer on the substrate, while the PS-rich phase is located at the polymer-air interface. During the thermal treatment, phase segregation and grafting proceed simultaneously. Complete wetting of the PS rich phase on the PMMA rich phase leads to the formation of a PS/PMMA bilayer. In this case, the progressive diffusion of PS chains toward the polymer-SiO_2 interface during the thermal treatment allows tuning of the brush layer composition. (paper)

  5. Regenerable Cu-intercalated MnO2 layered cathode for highly cyclable energy dense batteries

    Yadav, Gautam G.; Gallaway, Joshua W.; Turney, Damon E.; Nyce, Michael; Huang, Jinchao; Wei, Xia; Banerjee, Sanjoy

    2017-03-06

    Manganese dioxide cathodes are inexpensive and have high theoretical capacity (based on two electrons) of 617 mAh g-1, making them attractive for low-cost, energy-dense batteries. They are used in non-rechargeable batteries with anodes like zinc. Only ~10% of the theoretical capacity is currently accessible in rechargeable alkaline systems. Attempts to access the full capacity using additives have been unsuccessful. We report a class of Bi-birnessite (a layered manganese oxide polymorph mixed with bismuth oxide (Bi2O3)) cathodes intercalated with Cu2+ that deliver near-full two-electron capacity reversibly for >6,000 cycles. The key to rechargeability lies in exploiting the redox potentials of Cu to reversibly intercalate into the Bi-birnessite-layered structure during its dissolution and precipitation process for stabilizing and enhancing its charge transfer characteristics. This process holds promise for other applications like catalysis and intercalation of metal ions into layered structures. A large prismatic rechargeable Zn-birnessite cell delivering ~140 Wh l-1 is shown.

  6. Design of single-layer high-efficiency transmitting phase-gradient metasurface and high gain antenna

    Zhang, Di; Yang, Xiaoqing; Su, Piqiang; Luo, Jiefang; Chen, Huijie; Yuan, Jianping; Li, Lixin

    2017-12-01

    In this paper, based on rotation phase-gradient principle, a single-layer, high-efficiency transmitting metasurface is designed and applied to high-gain antenna. In the case of circularly polarized incident wave, the PCR (polarization conversions ratio) of the metasurface element is greater than 90% in the band of 9.11-10.48 GHz. The transmitting wave emerges an anomalous refraction when left-handed circularly polarized wave are incident perpendicularly to the 1D phase-gradient metasurface, which is composed of cycle arrangement of 6 units with step value of 30°. The simulated anomalous refraction angle is 40.1°, coincided with the theoretical design value (40.6°). For further application, the 2D focused metasurface is designed to enhance the antenna performance while the left-handed circularly polarized antenna is placed at the focus. The simulated max gain is increased by 12 dB (182%) and the half-power beamwidth is reduced by 74.6°. The measured results are coincided with the simulations, which indicates the antenna has high directivity. The designed single-layer transmission metasurface has advantages of thin thickness (only 1.5 mm), high efficiency and light weight, and will have important application prospects in polarization conversion and beam control.

  7. Electrokinetic effects and fluid permeability

    Berryman, J.G.

    2003-01-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery

  8. Development of Modal Analysis for the Study of Global Modes in High Speed Boundary Layer Flows

    Brock, Joseph Michael

    Boundary layer transition for compressible flows remains a challenging and unsolved problem. In the context of high-speed compressible flow, transitional and turbulent boundary-layers produce significantly higher surface heating caused by an increase in skin-friction. The higher heating associated with transitional and turbulent boundary layers drives thermal protection systems (TPS) and mission trajectory bounds. Proper understanding of the mechanisms that drive transition is crucial to the successful design and operation of the next generation spacecraft. Currently, prediction of boundary-layer transition is based on experimental efforts and computational stability analysis. Computational analysis, anchored by experimental correlations, offers an avenue to assess/predict stability at a reduced cost. Classical methods of Linearized Stability Theory (LST) and Parabolized Stability Equations (PSE) have proven to be very useful for simple geometries/base flows. Under certain conditions the assumptions that are inherent to classical methods become invalid and the use of LST/PSE is inaccurate. In these situations, a global approach must be considered. A TriGlobal stability analysis code, Global Mode Analysis in US3D (GMAUS3D), has been developed and implemented into the unstructured solver US3D. A discussion of the methodology and implementation will be presented. Two flow configurations are presented in an effort to validate/verify the approach. First, stability analysis for a subsonic cylinder wake is performed and results compared to literature. Second, a supersonic blunt cone is considered to directly compare LST/PSE analysis and results generated by GMAUS3D.

  9. Production of High-quality Few-layer Graphene Flakes by Intercalation and Exfoliation

    Alzahrani, Areej A.

    2017-11-30

    Graphene, a two-dimensional nanomaterial, has been given much attention since it was first isolated in 2004. Driving this intensive research effort are the unique properties of this one atom thick sheet of carbon, in particular its electrical, thermal and mechanical properties. While the technological applications proposed for graphene abound, its low-cost production in large scales is still a matter of interrogation. Simple methods to obtain few-layered graphene flakes of high structural quality are being investigated with the exfoliation of graphite taking a prominent place in this arena. From the many suggested approaches, the most promising involve the use of liquid media assisted by intercalants and shear forces acting on the basal layers of graphite. In this thesis, it is discussed how a novel method was developed to produce flakes with consistent lateral dimensions that are also few-layered and retain the expected structural and chemical characteristics of graphene. Here, the source material was a commercially available graphiteintercalated compound, also known as expandable graphite. Several exfoliation-inducing tools were investigated including the use of blenders, homogenizers, and ultrasonic processors. To aid in this process, various solvents and intercalants were explored under different reactive conditions. The more efficient approach in yielding defect-free thin flakes was the use of thermally expanded graphite in boiling dimethylformamide followed by ultrasonic processing and centrifugation. In parallel, a method to fraction the flakes as a function of their lateral size was developed. Ultimately, it was possible to obtain samples of graphene flakes with a lateral dimension of a few micrometers (<5 μm) and thickness of 1-3 nm (i.e. <10 layers).

  10. Experimental study on the soil structure and permeability in aerated zone at CIRP's field test site

    Du Zhongde; Zhao Yingjie; Guo Zhiming

    2000-01-01

    Measurement of soil grain and pore size distribution, observation of soil microstructure and permeability test are used to study soil structure and permeability. The results show that soil heterogeneity in vertical soil profile is much great. The mean heterogeneity coefficient is 14.7. The eccentric rate of saturated permeability coefficient in vertical and horizontal direction is from 0.65 to 1.00. The mean coefficient is 0.93. So the soil can be considered to be isotropic from the view point of the groundwater dynamics. The permeability coefficient has more difference in different soil layers. In vertical profile, the saturated permeability coefficient is relatively great in upper and under layers. It is relatively small in middle layers

  11. 高压水力压裂和二氧化碳相变致裂联合增透技术%Combined permeability improved technology with high pressure hydraulic fracturing and carbon dioxide phase change cracking

    秦江涛; 陈玉涛; 黄文祥

    2017-01-01

    针对白皎煤矿地质构造复杂、构造应力大、煤层透气性差、抽采瓦斯效果差的问题,提出了高压水力压裂和二氧化碳相变致裂联合增透技术,分析了水力压裂和二氧化碳相变致裂联合增透技术的原理;并在238底板巷对B4煤层进行了联合增透对比试验研究.试验结果表明:试验区域煤层透气性显著提高,单孔初抽瓦斯体积分数分别是高压水力压裂试验区域和普通抽采试验区域平均瓦斯体积分数的1.70、3.48倍;瓦斯抽采纯量较水力压裂区域和普通抽采区域分别提高了1.49、3.04倍;抽采65 d以后,高压水力压裂和二氧化碳相变致裂联合增透区域汇总瓦斯体积分数仍保持在40%以上,抽采效果良好,该技术可供类似矿井借鉴.%According to the problems of complicated geological tectonics,high tectonic stress,poor seam permeability and poor gas drainage effect in Baijiao Mine,a permeability improved technology combined with a high pressure hydraulic fracturing and carbon dioxide phase change cracking was provided and the principle of the hydraulic fracturing and carbon dioxide combined permeability improved technology was analyzed.A comparison experiment study was conducted on the combined permeability improvement of No.B4 Seam in No.238 floor gateway.The experiment results showed that the permeability of the seam in the technical experiment area was remarkably improved and the initial drained gas volume fraction of a single borehole was 1.70 times and 3.48 times higher than the average volume fractions of the high pressure hydraulic fracturing area and the conventional gas drainage trial area individually.The gas drainage pure volume was improved by 1.49 and 3.04 times higher than the hydraulic fracturing area and the conventional gas drainage area individually.After 65 days of the gas drainage operation,the total gas volume fraction of the high pressure hydraulic fracturing and carbon dioxide phase change

  12. The penetration, diffusion and energy deposition of high-energy photon in layered media

    Zhengming, Luo; Chengjun, Gou; Laub, Wolfram

    2002-01-01

    This paper presents a new theory for calculating the transport of high-energy photons and their secondary charged particles. We call this new algorithm characteristic line method, which is completely analytic. Using this new method we can not only accurately calculate the transport behavior of energetic photons, but also precisely describes the transport behavior and energy deposition of secondary electrons, photoelectrons, Compton recoil electrons and positron-electron pairs. Its calculation efficiency is much higher than the Monte Carlo method's. The theory can be directly applied to layered media situation and obtain a pencil-beam-modeled solution. Therefore, it may be applied to clinical applications for radiation therapy

  13. High speed display algorithm for 3D medical images using Multi Layer Range Image

    Ban, Hideyuki; Suzuki, Ryuuichi

    1993-01-01

    We propose high speed algorithm that display 3D voxel images obtained from medical imaging systems such as MRI. This algorithm convert voxel image data to 6 Multi Layer Range Image (MLRI) data, which is an augmentation of the range image data. To avoid the calculation for invisible voxels, the algorithm selects at most 3 MLRI data from 6 in accordance with the view direction. The proposed algorithm displays 256 x 256 x 256 voxel data within 0.6 seconds using 22 MIPS Workstation without a special hardware such as Graphics Engine. Real-time display will be possible on 100 MIPS class Workstation by our algorithm. (author)

  14. A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block.

    Lee, Seok Woo; Lee, Seung S; Yang, Eui-Hyeok

    2009-01-01

    This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V.

  15. A Study on Field Emission Characteristics of Planar Graphene Layers Obtained from a Highly Oriented Pyrolyzed Graphite Block.

    Lee, Seok Woo

    2009-07-12

    This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene layers were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed on an insulating substrate, with the resulting field emission behavior investigated using a nanomanipulator operating inside a scanning electron microscope. A pair of tungsten tips controlled by the nanomanipulator enabled electric connection with the graphene layers without postfabrication. The maximum emitted current from the graphene layers was 170 nA and the turn-on voltage was 12.1 V.

  16. Sandwich-like graphene/polypyrrole/layered double hydroxide nanowires for high-performance supercapacitors

    Li, Xuejin; Zhang, Yu; Xing, Wei; Li, Li; Xue, Qingzhong; Yan, Zifeng

    2016-11-01

    Electrode design in nanoscale is considered to be ultra-important to construct a superb capacitor. Herein, a sandwich-like composite was made by combining graphene/polypyrrole (GPPY) with nickel-aluminum layered double hydroxide nanowires (NiAl-NWs) via a facile hydrothermal method. This sandwich-like architecture is promising in energy storage applications due to three unique features: (1) the conductive GPPY substrate not only effectively prevents the layered double hydroxides species from aggregating, but also considerably facilitates the electron transmission; (2) the ultrathin NiAl-NWs ensure a maximum exposure of active Ni2+, which can improve the efficiency of rapid redox reactions even at high current densities; (3) the sufficient space between anisotropic NiAl-NWs can accommodate a large volume change of the nanowires to avoid their collapse or distortion during the reduplicative redox reactions. Keeping all these unique features in mind, when the as-prepared composite was applied to supercapacitors, it presented an enhanced capacitive performance in terms of high specific capacitance (845 F g-1), excellent rate performance (67% retained at 30 A g-1), remarkable cyclic stability (92% maintained after 5000 cycles) and large energy density (40.1 Wh·Kg-1). This accomplishment in the present work inspires an innovative strategy of nanoscale electrode design for high-rate performance supercapacitor electrodes containing pseuducapacitive metal oxide.

  17. Development of a novel two-layer multiplate magnetorheological clutch for high-power applications

    Wang, Daoming; Tian, Zuzhi; Meng, Qingrui; Hou, Youfu

    2013-01-01

    A novel magnetorheological (MR) clutch for high-power applications is designed, simulated and tested. The clutch is implemented in a two-layer multiplate transmission form and adopts a two-way liquid cooling method to improve the heat dissipation capability. In this paper, a brief introduction to the transmission form of the proposed MR clutch is given first. Then, theoretical analyses of the output torque, magnetic circuit and temperature characteristic are conducted and further design details are presented and discussed, followed by a magnetostatic simulation of the designed circuit. A prototype of the clutch was fabricated and several tests were carried out to evaluate the torque transmission, time response and steady slip power of the prototype. The results show that the proposed MR clutch can produce a maximum output torque of 1545 N m and possesses a high steady slip power of up to 35 kW. Therefore, the developed two-layer multiplate MR clutch is promising for applications in many high-power situations. (paper)

  18. Development and Breakdown of Goertler Vortices in High Speed Boundary Layers

    Li, Fei; Choudhari, Meelan; Chang, Chau-Lyan; Wu, Minwei; Greene, Ptrick T.

    2010-01-01

    The nonlinear development of G rtler instability over a concave surface gives rise to a highly distorted stationary flow in the boundary layer that has strong velocity gradients in both spanwise and wall-normal directions. This distorted flow is susceptible to strong, high frequency secondary instability that leads to the onset of transition. For high Mach number flows, the boundary layer is also subject to the second mode instability. The nonlinear development of G rtler vortices and the ensuing growth and breakdown of secondary instability, the G rtler vortex interactions with second mode instabilities as well as oblique second mode interactions are examined in the context of both internal and external hypersonic configurations using nonlinear parabolized stability equations, 2-D eigenvalue analysis and direct numerical simulation. For G rtler vortex development inside the Purdue Mach 6 Ludwieg tube wind tunnel, multiple families of unstable secondary eigenmodes are identified and their linear and nonlinear evolution is examined. The computation of secondary instability is continued past the onset of transition to elucidate the physical mechanisms underlying the laminar breakdown process. Nonlinear breakdown scenarios associated with transition over a Mach 6 compression cone configuration are also explored.

  19. Wear resistance of layers hard faced by the high-alloyed filler metal

    Dušan Arsić

    2016-10-01

    Full Text Available The objective of this work was to determine the wear resistance of layers hard faced by the high-alloyed filler metal, with or without the austenite inter-layer, on parts that operate at different sliding speeds in conditions without lubrication. The samples were hard faced with the filler metal E 10-UM-60-C with high content of C, Cr and W. Used filler metal belongs into group of alloys aimed for reparatory hard facing of parts damaged by abrasive and erosive wear and it is characterized by high hardness and wear resistance. In experiments, the sliding speed and the normal loading were varied and the wear scar was monitored, based on which the volume of the worn material was calculated analytically. The contact duration time was monitored over the sliding path of 300 mm. The most intensive wear was established for the loading force of 100 N and the sliding speed of 1 m.s-1, though the significant wear was also noticed in conditions of the small loading and speed of 0.25 m.s-1, which was even greater that at larger speeds.

  20. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    Sun, R.X.; Zheng, J.; Liao, X.L.; Che, T.; Gou, Y.F.; He, D.B.; Deng, Z.G.

    2014-01-01

    Highlights: • Thickness optimization of double-layer bulk HTSC arrangement is studied. • The new bulk HTSC arrangement makes better use of the flux distribution of the magnetic rails. • Levitation performance can be enhanced with the optimization. • The optimization can meet large levitation force requirements for HTS Maglev system. - Abstract: A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems

  1. Thickness dependence of the levitation performance of double-layer high-temperature superconductor bulks above a magnetic rail

    Sun, R.X.; Zheng, J.; Liao, X.L.; Che, T.; Gou, Y.F.; He, D.B.; Deng, Z.G., E-mail: zgdeng@gmail.com

    2014-10-15

    Highlights: • Thickness optimization of double-layer bulk HTSC arrangement is studied. • The new bulk HTSC arrangement makes better use of the flux distribution of the magnetic rails. • Levitation performance can be enhanced with the optimization. • The optimization can meet large levitation force requirements for HTS Maglev system. - Abstract: A double-layer high-temperature superconductor (HTSC) arrangement was proposed and proved to be able to bring improvements to both levitation force and guidance force compared with present single-layer HTSC arrangement. To fully exploit the applied magnetic field by a magnetic rail, the thickness dependence of a double-layer HTSC arrangement on the levitation performance was further investigated in the paper. In this study, the lower-layer bulk was polished step by step to different thicknesses, and the upper-layer bulk with constant thickness was directly superimposed on the lower-layer one. The levitation force and the force relaxation of the double-layer HTSC arrangement were measured above a Halbach magnetic rail. Experimental result shows that a bigger levitation force and a less levitation force decay could be achieved by optimizing the thickness of the lower-layer bulk HTSC. This thickness optimization method could be applied together with former reported double-layer HTSC arrangement method with aligned growth sector boundaries pattern. This series of study on the optimized combination method do bring a significant improvement on the levitation performance of present HTS maglev systems.

  2. Steps in growth of Nb-doped layered titanates with very high surface area suitable for water purification

    Milanović, Marija; Nikolić, Ljubica M.; Stijepović, Ivan; Kontos, Athanassios G.; Giannakopoulos, Konstantinos P.

    2014-01-01

    Nb-doped layered titanates, as highly efficient adsorbents, have been synthesized by hydrothermal reaction for variable duration and at 150 °C in a highly alkaline solution with NbCl 5 as the Nb source. The results have shown the formation of nanosheets already after 1 h of hydrothermal processing, but morphology and phase composition change as the reaction proceeds. The prepared layered titanates have been structurally investigated via scanning and transmission electron microscopy, X-ray diffraction, as well as Raman and Fourier transform infrared spectroscopies. The steps of layered titanate growth have been followed and an intermediate layered anatase phase is identified. Thus optimized growth of mesoporous titanate materials with 10% Nb atomic content present very high specific surface area of 345.3 m 2  g −1 , and perform as very efficient adsorbents for wastewater treatment applications. - Highlights: • Nb-doped layered titanates have been prepared by a hydrothermal procedure. • Introduction of Nb to precursor lowers the rate of layered titanate formation. • Steps in growth of Nb-doped layered titanates are considered. • Nb-doped layered titanates show high/fast MB adsorption from concentrated solution

  3. The gradient crystalline structure and microhardness in the treated layer of TC17 via high energy shot peening

    Li, Huimin; Liu, Yingang; Li, Miaoquan; Liu, Hongjie

    2015-01-01

    Graphical abstract: - Highlights: • The gradient nanocrystalline structure was induced in treated layer of TC17. • The thickness of nanograin layer with an average grain size of 10.5 nm was 20 μm. • The composition of the treated layer of TC17 was discussed. • The gradient variation of the microhardness was obtained in treated layer of TC17. - Abstract: The gradient nanocrystalline structure from the topmost surface to the matrix of a bulk coarse-grained TC17 was attained by using high energy shot peening treatment at an air pressure of 0.35 MPa and a processing duration of 30 min. The thickness from the topmost surface with a grain size of about 10.5 nm to the matrix with a micrometer structure was about 120 μm, and the thickness in the nanocrystalline layer was about 20 μm. The microscopic and nanocrystalline structure characteristic in the treated layer were investigated via X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The nanograins layer, the nanometer-thick laminated structure layer, the refined grains layer and the low-strain matrix layer occurred in sequence from the topmost surface to the matrix, and therefore the gradient nanocrystalline structure in the treated layer was produced by using high energy shot peening. TEM investigation confirmed that the dislocation activity with very high stacking fault energy induced by surface severe plastic deformation mainly controlled the grain refinement. The microhardness (HV 0.02 ) from the topmost surface to the matrix gradually increased by 43% from 440 to 629 and the gradient variation of the microhardness with the depths from the topmost surface to the matrix of treated TC17 was obtained.

  4. The Influence Of Dead Layer Effect On The Characteristics Of The High Purity Germanium P-Type Detector

    Ngo Quang Huy

    2011-01-01

    The present work aims at reviewing the studies of the influence of dead layer effect on the characteristics of a high purity germanium (HPGe) p-type detector, obtained by the author and his colleagues in the recent years. The object for study was the HPGe GC1518 detector-based gamma spectrometer of the Center for Nuclear Techniques, Ho Chi Minh City. The studying problems were: The modeling of an HPGe detector-based gamma spectrometer with using the MCNP code; the method of determining the thickness of dead layer by experimental measurements of gamma spectra and the calculations using MCNP code; the influence of material parameters and dead layer on detector efficiency; the increase of dead layer thickness over the operating time of the GC1518 detector; the influence of dead layer thickness increase on the decrease of detector efficiency; the dead layer effect for the gamma spectra measured in the GC1518 detector. (author)

  5. Effect of radiation on the laminar convective heat transfer through a layer of highly porous medium

    Lee, K.; Howell, J.R.

    1986-01-01

    A numerical investigation is reported of the coupled forced convective and radiative transfer through a highly porous medium. The porosity range investigated is high enough that the fluid inertia terms in the momentum equation cannot be neglected; i.e., the simple form of Darcy's law is invalid. The geometry studied is a plane layer of highly porous medium resting on one impermeable boundary and exposed to a two-dimensional laminar external flow field. The objective is to determine the effective overall heat transfer coefficients for such a geometry. The results are applicable to diverse situations, including insulation batts exposed to external flow, the heat loss and drying rates of grain fields and forest areas, and the drying of beds of porous material exposed to convective and radiative heating

  6. A topology optimization method for design of negative permeability metamaterials

    Diaz, A. R.; Sigmund, Ole

    2010-01-01

    A methodology based on topology optimization for the design of metamaterials with negative permeability is presented. The formulation is based on the design of a thin layer of copper printed on a dielectric, rectangular plate of fixed dimensions. An effective media theory is used to estimate the ...

  7. In?situ permeability from integrated poroelastic reflection coefficients

    Van Dalen, K.N.; Ghose, R.; Drijkoningen, C.G.; Smeulders, D.M.J.

    2010-01-01

    A reliable estimate of the in?situ permeability of a porous layer in the subsurface is extremely difficult to obtain. We have observed that at the field seismic frequency band the poroelastic behavior for different seismic wavetypes can differ in such a way that their combination gives unique

  8. Nickel/cobalt layered double hydroxide hollow microspheres with hydrangea-like morphology for high-performance supercapacitors

    Tao, Yan; Ruiyi, Li; Tingting, Yang; Zaijun, Li

    2015-01-01

    Graphical abstract: We report a new template synthesis of nickel/cobalt layered double hydroxides (Ni/Co-LDH) without any adscititious alkali source, oxidant and step for removal of the template. The perfect match between generation rate of Ni/Co-LDH nanoflakes and removal rate of template creates elaborate three-dimensional architecture with well-defined hollow interior and hydrangea-like exterior. The unique structure improves faradaic redox reaction and mass transfer during the redox process, thus the Ni/Co-LDH electrode provides excellent electrochemical performance for supercapacitors. - Highlights: • The study demonstrated a new strategy for template synthesis of Ni/Co-LDH without any adscititious alkali source, oxidant and step for removal of the template. • The perfect match between generation rate of Ni/Co-LDH nanoflakes and removal rate of SiO 2 template create hollow microspheres with hydrangea-like morphology. • The unique structure of Ni/Co-LDH will greatly improve faradaic redox reaction and mass transfer during the redox process. • The Ni/Co-LDH electrode displays high specific capacitance, good charge/discharge capability, large energy density and superior cycle stability. • The study provides a prominent approach to fabricate various hollow nanomaterials for supercapacitors, Li-ion batteries, catalyst and sensors. - Abstract: Electroactive materials with hollow nanostructures received great attractiveness due to large surface area, low density and superior structure permeablity. The paper reported a new template synthesis of nickel/cobalt layered double hydroxides (Ni/Co-LDH) without any adscititious alkali source, oxidant and step for removal of the template. Nickel nitrate, cobalt nitrate and SiO 2 nanosphere were dispersed in an ethanol solution. Then, the mixed soution was heated at 160 °C for 6 h to obtain Ni/Co-LDH product. During the process, ethanol and nitrate underwent a redox reaction releasing hydroxide ions, which will react

  9. THE THICKNESS DEPENDENCE OF OXYGEN PERMEABILITY IN SOL-GEL DERIVED CGO-COFE2O4 THIN FILMS ON POROUS CERAMIC SUBSTRATES: A SPUTTERED BLOCKING LAYER FOR THICKNESS CONTROL

    Brinkman, K

    2009-01-08

    Mixed conductive oxides are a topic of interest for applications in oxygen separation membranes as well as use in producing hydrogen fuel through the partial oxidation of methane. The oxygen flux through the membrane is governed both by the oxygen ionic conductivity as well as the material's electronic conductivity; composite membranes like Ce{sub 0.8}Gd{sub 0.2}O{sub 2-{delta}} (CGO)-CoFe{sub 2}O{sub 4} (CFO) use gadolinium doped ceria oxides as the ionic conducting material combined with cobalt iron spinel which serves as the electronic conductor. In this study we employ {approx} 50 nm sputtered CeO{sub 2} layers on the surface of porous CGO ceramic substrates which serve as solution 'blocking' layers during the thin film fabrication process facilitating the control of film thickness. Films with thickness of {approx} 2 and 4 microns were prepared by depositing 40 and 95 separate sol-gel layers respectively. Oxygen flux measurements indicated that the permeation increased with decreasing membrane thickness; thin film membrane with thickness on the micron level showed flux values an order of magnitude greater (0.03 {micro}mol/cm{sup 2} s) at 800 C as compared to 1mm thick bulk ceramic membranes (0.003 {micro}mol/cm{sup 2}).

  10. Compiling and Mapping Global Permeability of the Unconsolidated and Consolidated Earth: GLobal HYdrogeology MaPS 2.0 (GLHYMPS 2.0)

    Huscroft, Jordan; Gleeson, Tom; Hartmann, Jens; Börker, Janine

    2018-02-01

    The spatial distribution of subsurface parameters such as permeability are increasingly relevant for regional to global climate, land surface, and hydrologic models that are integrating groundwater dynamics and interactions. Despite the large fraction of unconsolidated sediments on Earth's surface with a wide range of permeability values, current global, high-resolution permeability maps distinguish solely fine-grained and coarse-grained unconsolidated sediments. Representative permeability values are derived for a wide variety of unconsolidated sediments and applied to a new global map of unconsolidated sediments to produce the first geologically constrained, two-layer global map of shallower and deeper permeability. The new mean logarithmic permeability of the Earth's surface is -12.7 ± 1.7 m2 being 1 order of magnitude higher than that derived from previous maps, which is consistent with the dominance of the coarser sediments. The new data set will benefit a variety of scientific applications including the next generation of climate, land surface, and hydrology models at regional to global scales.

  11. Fabrication of Crack-Free Barium Titanate Thin Film with High Dielectric Constant Using Sub-Micrometric Scale Layer-by-Layer E-Jet Deposition

    Junsheng Liang

    2016-01-01

    Full Text Available Dense and crack-free barium titanate (BaTiO3, BTO thin films with a thickness of less than 4 μm were prepared by using sub-micrometric scale, layer-by-layer electrohydrodynamic jet (E-jet deposition of the suspension ink which is composed of BTO nanopowder and BTO sol. Impacts of the jet height and line-to-line pitch of the deposition on the micro-structure of BTO thin films were investigated. Results show that crack-free BTO thin films can be prepared with 4 mm jet height and 300 μm line-to-line pitch in this work. Dielectric constant of the prepared BTO thin film was recorded as high as 2940 at 1 kHz at room temperature. Meanwhile, low dissipation factor of the BTO thin film of about 8.6% at 1 kHz was also obtained. The layer-by-layer E-jet deposition technique developed in this work has been proved to be a cost-effective, flexible and easy to control approach for the preparation of high-quality solid thin film.

  12. A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations.

    Badr, Jihan M

    2013-01-01

    Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Harmonization (ICH) guidelines. The method employed thin layer chromatography aluminum sheets precoated with silica gel as the stationary phase and the mobile phase consisted of chloroform:methanol:ammonia (97:3:0.2), which gave compact bands of yohimbine hydrochloride. Linear regression data for the calibration curves of standard yohimbine hydrochloride showed a good linear relationship over a concentration range of 80-1000 ng/spot with respect to the area and correlation coefficient (R(2)) was 0.9965. The method was evaluated regarding accuracy, precision, selectivity, and robustness. Limits of detection and quantitation were recorded as 5 and 40 ng/spot, respectively. The proposed method efficiently separated yohimbine hydrochloride from other components even in complex mixture containing powdered plants. The amount of yohimbine hydrochloride ranged from 2.3 to 5.2 mg/tablet or capsule in preparations containing the pure alkaloid, while it varied from zero (0) to 1.5-1.8 mg/capsule in dietary supplements containing powdered yohimbe bark. We concluded that this method employing high performance thin layer chromatography (HPTLC) in quantitative determination of yohimbine hydrochloride in pharmaceutical preparations is efficient, simple, accurate, and validated.

  13. Ammonia, hydrogen sulfide, carbon dioxide and particulate matter emissions from California high-rise layer houses

    Lin, X.-J.; Cortus, E. L.; Zhang, R.; Jiang, S.; Heber, A. J.

    2012-01-01

    Ammonia and hydrogen sulfide are hazardous substances that are regulated by the U.S. Environmental Protection Agency through community right-to-know legislation (EPCRA, EPA, 2011). The emissions of ammonia and hydrogen sulfide from large commercial layer facilities are of concern to legislators and nearby neighbors. Particulate matter (PM 10 and PM 2.5) released from layer houses are two of seven criteria pollutants for which EPA has set National Ambient Air Quality Standards as required by the Clean Air Act. Therefore, it is important to quantify the baseline emissions of these pollutants. The emissions of ammonia, hydrogen sulfide, carbon dioxide and PM from two California high-rise layer houses were monitored for two years from October 2007 to October 2009. Each house had 32,500 caged laying hens. The monitoring site was setup in compliance with a U.S. EPA-approved quality assurance project plan. The results showed the average daily mean emission rates of ammonia, hydrogen sulfide and carbon dioxide were 0.95 ± 0.67 (standard deviation) g d -1 bird -1, 1.27 ± 0.78 mg d -1 bird -1 and 91.4 ± 16.5 g d -1 bird -1, respectively. The average daily mean emission rates of PM 2.5, PM 10 and total suspended particulate (TSP) were 5.9 ± 12.6, 33.4 ± 27.4, and 78.0 ± 42.7 mg d -1 bird -1, respectively. It was observed that ammonia emission rates in summer were lower than in winter because the high airflow stabilized the manure by drying it. The reductions due to lower moisture content were greater than the increases due to higher temperature. However, PM 10 emission rates in summer were higher than in winter because the drier conditions coupled with higher internal air velocities increased PM 10 release from feathers, feed and manure.

  14. Permeability testing of biomaterial membranes

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

    2008-09-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

  15. Permeability testing of biomaterial membranes

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B; Ahlers, M

    2008-01-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation

  16. Relative Permeability of Fractured Rock

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  17. Structural properties of ultraviolet cured polysilazane gas barrier layers on polymer substrates

    Morlier, Arnaud; Cros, Stéphane; Garandet, Jean-Paul; Alberola, Nicole

    2014-01-01

    Perhydropolysilazane (PHPS) conversion to silica through high energy ultraviolet irradiation has been studied. Precursor conversion speed and structural properties of the UV cured PHPS have been investigated and showed that this conversion method is fast but that complete conversion into silica is not achieved in an oxygen depleted atmosphere for layer thicknesses higher than 30 nm, resulting in a composite structure with concentration gradients. We further show that Fourier transform infrared spectroscopy data allow investigating the local structure and composition over the depth of the obtained layers. Gas permeability of the thin UV cured PHPS layers deposited on polymers has been studied. We used a high sensitivity permeation measurement technique to determine water vapor and oxygen permeabilities of the barrier layers and show the correlation between helium, oxygen and water permeability of these materials. Oxygen and water vapor transmission rates of respectively 0.06 cm 3 /m 2 /day/bar and 0.2 g/m 2 /day have been obtained with layers deposited on a polymer substrate. - Highlights: • Perhydropolysilazane has been converted into dense layers by vacuum UV irradiation. • Cured perhydropolysilazane layers have an inhomogeneous structure. • The cured material consists in 3 spontaneously formed layers. • Oxygen and water transmission rates of 0.06 cm 3 /m 2 /day/bar and 0.02 g/m 2 /day are reached

  18. Insights into Evaporative Droplet Dynamics in the High-Wind Atmospheric Boundary Layer

    Peng, T.; Richter, D. H.

    2017-12-01

    Sea-spray droplets ejected into the air-sea boundary layer take part in a series of complex transport processes. To model the air-sea exchange of heat and moisture under high-wind conditions, it is important yet challenging to understand influences of evaporative droplets in the atmospheric boundary layer. We implement a high-resolution Eulerian-Lagrangian algorithm with droplets laden in a turbulent open-channel flow to reveal the dynamic and thermodynamic characteristics of evaporating sea spray. Our past numerical simulations demonstrated an overall weak modification to the total heat flux by evaporative droplets. This is due to redistributed sensible and latent heat fluxes from relatively small droplets that respond rapidly to the ambient environment or the limited residence time of larger droplets. However, droplets with a slower thermodynamic response to the environment indicate a potential to enhance the total heat flux, but this is dependent on concentration and suspension time. In the current study, we focus on correlations between the residence time and thermodynamic statistics of droplets in order to better understand how best to parameterize in large-scale models. In addition, we focus in detail on the different scales of turbulence to further characterize the range of influence that evaporating droplets have on the surrounding fluid.

  19. Hydrothermal synthesis of highly nitrogen-doped few-layer graphene via solid–gas reaction

    Liang, Xianqing; Zhong, Jun; Shi, Yalin; Guo, Jin; Huang, Guolong; Hong, Caihao; Zhao, Yidong

    2015-01-01

    Highlights: • A novel approach to synthesis of N-doped few-layer graphene has been developed. • The high doping levels of N in products are achieved. • XPS and XANES results reveal a thermal transformation of N bonding configurations. • The developed method is cost-effective and eco-friendly. - Abstract: Nitrogen-doped (N-doped) graphene sheets with high doping concentration were facilely synthesized through solid–gas reaction of graphene oxide (GO) with ammonia vapor in a self-designed hydrothermal system. The morphology, surface chemistry and electronic structure of N-doped graphene sheets were investigated by TEM, AFM, XRD, XPS, XANES and Raman characterizations. Upon hydrothermal treatment, up to 13.22 at% of nitrogen could be introduced into the crumpled few-layer graphene sheets. Both XPS and XANES analysis reveal that the reaction between oxygen functional groups in GO and ammonia vapor produces amide and amine species in hydrothermally treated GO (HTGO). Subsequent thermal annealing of the resultant HTGO introduces a gradual transformation of nitrogen bonding configurations in graphene sheets from amine N to pyridinic and graphitic N with the increase of annealing temperature. This study provides a simple but cost-effective and eco-friendly method to prepare N-doped graphene materials in large-scale for potential applications

  20. Ru nanostructure fabrication using an anodic aluminum oxide nanotemplate and highly conformal Ru atomic layer deposition

    Kim, Woo-Hee; Park, Sang-Joon; Son, Jong-Yeog; Kim, Hyungjun [Department of Material Science and Engineering, POSTECH Pohang University of Science and Technology, San 31, Hyoja-Dong, Nam-Gu, Pohang 790-784 (Korea, Republic of)

    2008-01-30

    We fabricated metallic nanostructures directly on Si substrates through a hybrid nanoprocess combining atomic layer deposition (ALD) and a self-assembled anodic aluminum oxide (AAO) nanotemplate. ALD Ru films with Ru(DMPD)(EtCp) as a precursor and O{sub 2} as a reactant exhibited high purity and low resistivity with negligible nucleation delay and low roughness. These good growth characteristics resulted in the excellent conformality for nanometer-scale vias and trenches. Additionally, AAO nanotemplates were fabricated directly on Si and Ti/Si substrates through a multiple anodization process. AAO nanotemplates with various hole sizes (30-100 nm) and aspect ratios (2:1-20:1) were fabricated by controlling the anodizing process parameters. The barrier layers between AAO nanotemplates and Si substrates were completely removed by reactive ion etching (RIE) using BCl{sub 3} plasma. By combining the ALD Ru and the AAO nanotemplate, Ru nanostructures with controllable sizes and shapes were prepared on Si and Ti/Si substrates. The Ru nanowire array devices as a platform for sensor devices exhibited befitting properties of good ohmic contact and high surface/volume ratio.

  1. Effects of buried high-Z layers on fast electron propagation

    Yang, Xiaohu; Zhuo, Hongbin; Ma, Yanyun; Shao, Fuqiu; Xu, Han; Yin Yan; Borghesi, M.

    2014-01-01

    The transport through high density plasmas of relativistic electron beams generated by ultra-intense laser-plasma interaction has potential applications in laser-driven ion acceleration and in the fast igniter scheme for inertial confinement fusion. By extending a prior model [A.R. Bell, J.R. Davies, S.M. Guerin, Phys. Rev. E 58, 2471 (1998)], the magnetic field generated during the transport of a fast electron beam driven by an ultra-intense laser in a solid target is derived analytically and applied to estimate the effect of such field on fast electron propagation through a buried high-Z layer in a lower-Z target. It is found that the effect gets weaker with the increase of the depth of the buried layer, the divergence of the fast electrons, and the laser intensity, indicating that magnetic field effects on the fast electron divergence as measured from K a X-ray emission may need to be considered for moderate laser intensities. On the basis of the calculations, some considerations are made on how one can mitigate the effect of the magnetic field generated at the interface. (authors)

  2. High-efficiency/CRI/color stability warm white organic light-emitting diodes by incorporating ultrathin phosphorescence layers in a blue fluorescence layer

    Miao Yanqin

    2018-01-01

    Full Text Available By incorporating ultrathin (80, low correlated color temperature of <3600 K, and high color stability at a wide voltage range of 5 V–9 V. These hybrid WOLEDs also reveal high forward-viewing external quantum efficiencies (EQE of 17.82%–19.34%, which are close to the theoretical value of 20%, indicating an almost complete exciton harvesting. In addition, the electroluminescence spectra of the hybrid WOLEDs can be easily improved by only changing the incorporating sequence of the ultrathin phosphorescence layers without device efficiency loss. For example, the hybrid WOLED with an incorporation sequence of ultrathin red/yellow/green phosphorescence layers exhibits an ultra-high CRI of 96 and a high EQE of 19.34%. To the best of our knowledge, this is the first WOLED with good tradeoff among device efficiency, CRI, and color stability. The introduction of ultrathin (<0.1 nm phosphorescence layers can also greatly reduce the consumption of phosphorescent emitters as well as simplify device structures and fabrication process, thus leading to low cost. Such a finding is very meaningful for the potential commercialization of hybrid WOLEDs.

  3. Three-layer GSO depth-of-interaction detector for high-energy gamma camera

    Yamamoto, S.; Watabe, H.; Kawachi, N.; Fujimaki, S.; Kato, K.; Hatazawa, J.

    2014-01-01

    Using Ce-doped Gd 2 SiO 5 (GSO) of different Ce concentrations, three-layer DOI block detectors were developed to reduce the parallax error at the edges of a pinhole gamma camera for high-energy gamma photons. GSOs with Ce concentrations of 1.5 mol% (decay time ∼40 ns), 0.5 mol% crystal (∼60 ns), 0.4 mol% (∼80 ns) were selected for the depth of interaction (DOI) detectors. These three types of GSOs were optically coupled in the depth direction, arranged in a 22×22 matrix and coupled to a flat panel photomultiplier tube (FP-PMT, Hamamatsu H8500). Sizes of these GSO cells were 1.9 mm×1.9 mm×4 mm, 1.9 mm×1.9 mm×5 mm, and 1.9 mm×1.9 mm×6 mm for 1.5 mol%, 0.5 mol%, and 0.4 mol%, respectively. With these combinations of GSOs, all spots corresponding to GSO cells were clearly resolved in the position histogram. Pulse shape spectra showed three peaks for these three decay times of GSOs. The block detector was contained in a 2-cm-thick tungsten shield, and a pinhole collimator with a 0.5-mm aperture was mounted. With pulse shape discrimination, we separated the point source images of the Cs-137 for each DOI layer. The point source image of the lower layer was detected at the most central part of the field-of-view, and the distribution was the smallest. The point source image of the higher layer was detected at the most peripheral part of the field-of-view, and the distribution was widest. With this information, the spatial resolution of the pinhole gamma camera can be improved. We conclude that DOI detection is effective for pinhole gamma cameras for high energy gamma photons

  4. High-frequency instabilities of stationary crossflow vortices in a hypersonic boundary layer

    Li, Fei; Choudhari, Meelan; Paredes, Pedro; Duan, Lian

    2016-09-01

    Hypersonic boundary layer flows over a circular cone at moderate incidence angle can support strong crossflow instability in between the windward and leeward rays on the plane of symmetry. Due to more efficient excitation of stationary crossflow vortices by surface roughness, such boundary layer flows may transition to turbulence via rapid amplification of the high-frequency secondary instabilities of finite-amplitude stationary crossflow vortices. The amplification characteristics of these secondary instabilities are investigated for crossflow vortices generated by an azimuthally periodic array of roughness elements over a 7° half-angle circular cone in a Mach 6 free stream. The analysis is based on both quasiparallel stability theory in the form of a partial-differential-equation-based eigenvalue analysis and plane marching parabolized stability equations that account for the effects of the nonparallel basic state on the growth of secondary disturbances. Depending on the local amplitude of the stationary crossflow mode, the most unstable high-frequency disturbances either originate from the second (i.e., Mack) mode instabilities of the unperturbed boundary layer or correspond to genuine secondary instabilities that reduce to stable disturbances at sufficiently small amplitudes of the stationary crossflow vortex. The predicted frequencies of the dominant secondary disturbances of either type are similar to those measured during wind tunnel experiments at Purdue University and the Technical University of Braunschweig, Germany. Including transverse surface curvature within the quasiparallel predictions does not alter the topology of the unstable modes; however, the resulting changes in both mode shape and disturbance growth rate are rather significant and curvature can be either stabilizing or destabilizing depending on the disturbance frequency and mode type. Nonparallel effects are shown to be strongly destabilizing for secondary instabilities originating from

  5. Highly Sensitive Bulk Silicon Chemical Sensors with Sub-5 nm Thin Charge Inversion Layers.

    Fahad, Hossain M; Gupta, Niharika; Han, Rui; Desai, Sujay B; Javey, Ali

    2018-03-27

    There is an increasing demand for mass-producible, low-power gas sensors in a wide variety of industrial and consumer applications. Here, we report chemical-sensitive field-effect-transistors (CS-FETs) based on bulk silicon wafers, wherein an electrostatically confined sub-5 nm thin charge inversion layer is modulated by chemical exposure to achieve a high-sensitivity gas-sensing platform. Using hydrogen sensing as a "litmus" test, we demonstrate large sensor responses (>1000%) to 0.5% H 2 gas, with fast response (<60 s) and recovery times (<120 s) at room temperature and low power (<50 μW). On the basis of these performance metrics as well as standardized benchmarking, we show that bulk silicon CS-FETs offer similar or better sensing performance compared to emerging nanostructures semiconductors while providing a highly scalable and manufacturable platform.

  6. Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

    Xia, Chuan

    2018-02-12

    Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

  7. Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

    Xia, Chuan; Guo, Jing; Li, Peng; Zhang, Xixiang; Alshareef, Husam N.

    2018-01-01

    Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

  8. Graphene electric double layer capacitor with ultra-high-power performance

    Miller, John R.; Outlaw, R.A.; Holloway, B.C.

    2011-01-01

    We have demonstrated, for the first time, efficient 120 Hz filtering by an electric double layer capacitor (EDLC). The key to this ultra-high-power performance is electrodes made from vertically oriented graphene nanosheets grown directly on metal current collectors. This design minimized both electronic and ionic resistance and produced capacitors having RC time-constants of less than 200 μs. Significantly, graphene nanosheets have a preponderance of exposed edge planes that greatly increase stored charge over designs relying on basal plane surfaces. Collectively these factors make vertically oriented graphene nanosheet electrodes ideally suited for producing high-frequency EDLCs. Capacitors constructed with these electrodes are predicted to be significantly smaller than aluminum electrolyte capacitors that they could functionally replace plus be manufactured using standard semiconductor process equipment, creating interesting commercial opportunities.

  9. A micro-structured Si-based electrodes for high capacity electrical double layer capacitors

    Krikscikas, Valdas; Oguchi, Hiroyuki; Hara, Motoaki; Kuwano, Hiroki; Yanazawa, Hiroshi

    2014-01-01

    We challenged to make basis for Si electrodes of electric double layer capacitors (EDLC) used as a power source of micro-sensor nodes. Mcroelectromechanical systems (MEMS) processes were successfully introduced to fabricate micro-structured Si-based electrodes to obtain high surface area which leads to high capacity of EDLCs. Study of fundamental properties revealed that the microstructured electrodes benefit from good wettability to electrolytes, but suffer from electric resistance. We found that this problem can be solved by metal-coating of the electrode surface. Finally we build an EDLC consisting of Au-coated micro-structured Si electrodes. This EDLC showed capacity of 14.3 mF/cm 2 , which is about 530 times larger than that of an EDLC consisting of flat Au electrodes

  10. Morphological features of the copper surface layer under sliding with high density electric current

    Fadin, V. V., E-mail: fvv@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Aleutdinova, M. I., E-mail: aleut@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Seversk Technological Institute, Branch of State Autonomous Educational Institution of Higher Professional Education “National Research Nuclear University “MEPhI”, Seversk, 636036 (Russian Federation); Rubtsov, V. Ye., E-mail: rvy@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Aleutdinova, V. A., E-mail: valery-aleut@yandex.ru [National Research St. Petersburg State Polytechnical University, St. Petersburg, 195251 (Russian Federation)

    2015-10-27

    Conductivity and wear intensity of copper under the influence of dry friction and electric current with contact density higher 100 A/cm{sup 2} are presented. It is shown that an increase in hardness and heat outflow from a friction zone leads to the reduction of wear intensity and current contact density increase corresponding to the beginning of catastrophic wear. Structural changes, such as the formation of FeO oxide and α-Fe particles in the copper surface layer, have also been found. It is observed that a worn surface is deformed according to a viscous liquid mechanism. Such singularity is explained in terms of appearance of high-excited atomic states in deforming micro-volumes near contact spots that lead to easy stress relaxation by local plastic shears in the vicinity of stress concentrators. In common this effect allows to achieve high wear resistance.

  11. Large Magnetoresistance at High Bias Voltage in Double-layer Organic Spin Valves

    Subedi, R. C.; Liang, S. H.; Geng, R.; Zhang, Q. T.; Lou, L.; Wang, J.; Han, X. F.; Nguyen, T. D.

    We report studies of magnetoresistance (MR) in double-layer organic spin valves (DOSV) using tris (8-hydroxyquinolinato) aluminum (Alq3) spacers. The device exhibits three distinct resistance levels depending on the relative magnetizations of the ferromagnetic electrodes. We observed a much weaker bias voltage dependence of MR in the device compared to that in the conventional organic spin valve (OSV). The MR magnitude reduces by the factor of two at 0.7 V bias voltage in the DOSV compared to 0.02 V in the conventional OSV. Remarkably, the MR magnitude reaches 0.3% at 6 V bias in the DOSVs, the largest MR response ever reported in OSVs at this bias. Our finding may have a significant impact on achieving high efficient bipolar OSVs strictly performed at high voltages. University of Georgia start-up fund, Ministry of Education, Singapore, National Natural Science Foundation of China.

  12. Highly efficient single-layer dendrimer light-emitting diodes with balanced charge transport

    Anthopoulos, Thomas D.; Markham, Jonathan P. J.; Namdas, Ebinazar B.; Samuel, Ifor D. W.; Lo, Shih-Chun; Burn, Paul L.

    2003-06-01

    High-efficiency single-layer-solution-processed green light-emitting diodes based on a phosphorescent dendrimer are demonstrated. A peak external quantum efficiency of 10.4% (35 cd/A) was measured for a first generation fac-tris(2-phenylpyridine) iridium cored dendrimer when blended with 4,4'-bis(N-carbazolyl)biphenyl and electron transporting 1,3,5-tris(2-N-phenylbenzimidazolyl)benzene at 8.1 V. A maximum power efficiency of 12.8 lm/W was measured also at 8.1 V and 550 cd/m2. These results indicate that, by simple blending of bipolar and electron-transporting molecules, highly efficient light-emitting diodes can be made employing a very simple device structure.

  13. Double-layered metal grating for high-performance refractive index sensing.

    Li, Guozhen; Shen, Yang; Xiao, Guohui; Jin, Chongjun

    2015-04-06

    The detection of minuscule changes in the local refractive index by localized surface plasmon resonances (LSPRs), carried by metal nanostructures, has been used successfully in applications such as real-time and label-free detection of molecular binding events. However, localized plasmons demonstrate 1-2 orders of magnitude lower figure of merit (FOM) compared with their propagating counterparts. Here, we propose and experimentally demonstrate a high-performance refractive index sensor based on a structure of double-layered metal grating (DMG) with an FOM and FOM* reaching 38 and 40 respectively under normal incidence. Such a high FOM and FOM* arise from a result of a sharp fano resonance, which is caused by the coherent interference between the LSPR from the individual top gold stripes and Wood's anomaly (WA). Moreover, a small conformal decay length of ~68 nm is determined in DMG, indicating that the DMG is a promising candidate for label-free biomedical sensing.

  14. Transparent anodes for polymer photovoltaics: Oxygen permeability of PEDOT

    Andersen, M.; Carlé, Jon Eggert; Cruys-Bagger, N.

    2007-01-01

    The oxygen permeability of the transparent organic anode poly(3,4,-ethylene dioxythiophene) with paratoluenesulphonate as the anion (PEDOT:pTS) was determined to be 2.5 +/- 0.7 x 10(-15) cm(3) (STP) CM cm(-2) S-1 Pa-1, and is thus comparable in magnitude to the oxygen permeability of polyethylene......The oxygen permeability of the transparent organic anode poly(3,4,-ethylene dioxythiophene) with paratoluenesulphonate as the anion (PEDOT:pTS) was determined to be 2.5 +/- 0.7 x 10(-15) cm(3) (STP) CM cm(-2) S-1 Pa-1, and is thus comparable in magnitude to the oxygen permeability...... of polyethyleneterephthalate (PET). The oxygen diffusion through bilayers of polyethylene (PE) and PEDOT:pTS and bilayers of PET and PEDOT:pTS was established. The bilayer structures were applied as the carrier substrate and the transparent anode in polymer-based photovoltaic devices employing a mixture of poly(1-methoxy-4......-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV) and [6,6]-phenyt-C-61-butanoicacidmethylester (PCBM) as the active layer and aluminium as the cathode. The oxygen permeability of the layers and the aluminium cathode was correlated with the lifetime of the solar cell devices. It was found that the performance...

  15. High Performance Nano-Constituent Buffer Layer Thin Films to Enable Low Cost Integrated On-the-Move Communications Systems

    Cole, M. W; Nothwang, W. D; Hubbard, C; Ngo, E; Hirsch, S

    2004-01-01

    .... Utilizing a coplanar device design we successfully designed, fabricated, characterized, and optimized a high performance Ta2O5 thin film passive buffer layer on Si substrates, which will allow...

  16. Calculation of large scale relative permeabilities from stochastic properties of the permeability field and fluid properties

    Lenormand, R.; Thiele, M.R. [Institut Francais du Petrole, Rueil Malmaison (France)

    1997-08-01

    The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities using stochastic properties of the permeability field. In heterogeneous media, the spreading of an injected fluid is mainly sue to the permeability heterogeneity and viscosity fingering. At large scale, when the heterogeneous medium is replaced by a homogeneous one, we need to introduce a homogenized (or pseudo) relative permeability to obtain the same spreading. Generally, is derived by using fine-grid numerical simulations (Kyte and Berry). However, this operation is time consuming and cannot be performed for all the meshes of the reservoir. We propose an alternate method which uses the information given by the stochastic properties of the field without any numerical simulation. The method is based on recent developments on homogenized transport equations (the {open_quotes}MHD{close_quotes} equation, Lenormand SPE 30797). The MHD equation accounts for the three basic mechanisms of spreading of the injected fluid: (1) Dispersive spreading due to small scale randomness, characterized by a macrodispersion coefficient D. (2) Convective spreading due to large scale heterogeneities (layers) characterized by a heterogeneity factor H. (3) Viscous fingering characterized by an apparent viscosity ration M. In the paper, we first derive the parameters D and H as functions of variance and correlation length of the permeability field. The results are shown to be in good agreement with fine-grid simulations. The are then derived a function of D, H and M. The main result is that this approach lead to a time dependent . Finally, the calculated are compared to the values derived by history matching using fine-grid numerical simulations.

  17. Few-layered Ni(OH)2 nanosheets for high-performance supercapacitors

    Sun, Wenping; Rui, Xianhong; Ulaganathan, Mani; Madhavi, Srinivasan; Yan, Qingyu

    2015-11-01

    Few-layered Ni(OH)2 nanosheets (4-5 nm in thickness) are synthesized towards high-performance supercapacitors. The ultrathin Ni(OH)2 nanosheets show high specific capacitance and good rate capability in both three-electrode and asymmetric devices. In the three-electrode device, the Ni(OH)2 nanosheets deliver a high capacitance of 2064 F g-1 at 2 A g-1, and the capacitance still has a retention of 1837 F g-1 at a high current density of 20 A g-1. Such excellent performance is by far one of the best for Ni(OH)2 electrodes. In the two-electrode asymmetric device, the specific capacitance is 248 F g-1 at 1 A g-1, and reaches 113 F g-1 at 20 A g-1. The capacitance of the asymmetric device maintains to be 166 F g-1 during the 4000th cycle at 2 A g-1, suggesting good cycling stability of the device. Besides, the asymmetric device exhibits gravimetric energy density of 22 Wh kg-1 at a power density of 0.8 kW kg-1. The present results demonstrate that the ultrathin Ni(OH)2 nanosheets are highly attractive electrode materials for achieving fast charging/discharging and high-capacity supercapacitors.

  18. Highly efficient red phosphorescent organic light-emitting diodes based on solution processed emissive layer

    Liu, Baiquan; Xu, Miao; Tao, Hong; Ying, Lei; Zou, Jianhua; Wu, Hongbin; Peng, Junbiao

    2013-01-01

    Highly efficient red phosphorescent organic polymer light-emitting diodes (PhOLEDs) were fabricated based on a solution-processed small-molecule host 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) by doping an iridium complex, tris(1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine)iridium (III) (Ir(MPCPPZ) 3 ). A hole blocking layer 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI) with a function of electron transport was thermally deposited onto the top of CBP layer. The diode with the structure of ITO/PEDOT:PSS (50 nm)/CBP:Ir(MPCPPZ) 3 (55 nm)/TPBI (30 nm)/Ba (4 nm)/Al (120 nm) showed an external quantum efficiency (QE ext ) of 19.3% and luminous efficiency (LE) of 18.3 cd/A at a current density of 0.16 mA/cm 2 , and Commission International de I'Eclairage (CIE) coordinates of (0.607, 0.375). It was suggested that the diodes using TPBI layer exhibited nearly 100% internal quantum efficiency and one order magnitude enhanced LE or QE ext efficiencies. -- Highlights: • Efficient red PhOLEDs based on a solution-processed small-molecule host were fabricated. • By altering volume ratio of chloroform/chlorobenzene solvent, we got best film quality of CBP. • EQE of the diode was 19.3%, indicating nearly 100% internal quantum yield was achieved

  19. Highly efficient computer algorithm for identifying layer thickness of atomically thin 2D materials

    Lee, Jekwan; Cho, Seungwan; Park, Soohyun; Bae, Hyemin; Noh, Minji; Kim, Beom; In, Chihun; Yang, Seunghoon; Lee, Sooun; Seo, Seung Young; Kim, Jehyun; Lee, Chul-Ho; Shim, Woo-Young; Jo, Moon-Ho; Kim, Dohun; Choi, Hyunyong

    2018-03-01

    The fields of layered material research, such as transition-metal dichalcogenides (TMDs), have demonstrated that the optical, electrical and mechanical properties strongly depend on the layer number N. Thus, efficient and accurate determination of N is the most crucial step before the associated device fabrication. An existing experimental technique using an optical microscope is the most widely used one to identify N. However, a critical drawback of this approach is that it relies on extensive laboratory experiences to estimate N; it requires a very time-consuming image-searching task assisted by human eyes and secondary measurements such as atomic force microscopy and Raman spectroscopy, which are necessary to ensure N. In this work, we introduce a computer algorithm based on the image analysis of a quantized optical contrast. We show that our algorithm can apply to a wide variety of layered materials, including graphene, MoS2, and WS2 regardless of substrates. The algorithm largely consists of two parts. First, it sets up an appropriate boundary between target flakes and substrate. Second, to compute N, it automatically calculates the optical contrast using an adaptive RGB estimation process between each target, which results in a matrix with different integer Ns and returns a matrix map of Ns onto the target flake position. Using a conventional desktop computational power, the time taken to display the final N matrix was 1.8 s on average for the image size of 1280 pixels by 960 pixels and obtained a high accuracy of 90% (six estimation errors among 62 samples) when compared to the other methods. To show the effectiveness of our algorithm, we also apply it to TMD flakes transferred on optically transparent c-axis sapphire substrates and obtain a similar result of the accuracy of 94% (two estimation errors among 34 samples).

  20. Highly efficient polymer solar cells with printed photoactive layer: rational process transfer from spin-coating

    Zhao, Kui

    2016-09-05

    Scalable and continuous roll-to-roll manufacturing is at the heart of the promise of low-cost and high throughput manufacturing of solution-processed photovoltaics. Yet, to date the vast majority of champion organic solar cells reported in the literature rely on spin-coating of the photoactive bulk heterojunction (BHJ) layer, with the performance of printed solar cells lagging behind in most instances. Here, we investigate the performance gap between polymer solar cells prepared by spin-coating and blade-coating the BHJ layer for the important class of modern polymers exhibiting no long range crystalline order. We find that thickness parity does not always yield performance parity even when using identical formulations. Significant differences in the drying kinetics between the processes are found to be responsible for BHJ nanomorphology differences. We propose an approach which benchmarks the film drying kinetics and associated BHJ nanomorphology development against those of the champion laboratory devices prepared by spin-coating the BHJ layer by adjusting the process temperature. If the optimization requires the solution concentration to be changed, then it is crucial to maintain the additive-to-solute volume ratio. Emulating the drying kinetics of spin-coating is also shown to help achieve morphological and performance parities. We put this approach to the test and demonstrate printed PTB7:PC71BM polymer solar cells with efficiency of 9% and 6.5% PCEs on glass and flexible PET substrates, respectively. We further demonstrate performance parity for two other popular donor polymer systems exhibiting rigid backbones and absence of a long range crystalline order, achieving a PCE of 9.7%, the highest efficiency reported to date for a blade coated organic solar cell. The rational process transfer illustrated in this study should help the broader and successful adoption of scalable printing methods for these material systems.

  1. 0-6635 : water quality performance of permeable friction course on curbed sections.

    2013-08-01

    The Texas Department of Transportation : (TxDOT) has funded a number of studies to : investigate the pollutant removal associated : with use of the permeable friction course (PFC) : on highways. PFC is placed in layers : approximately 2 inches thick ...

  2. Phytochemical analysis of ethanolic extract of Dichrostachys Cinerea W and Arn leaves by a thin layer chromatography, high performance thin layer chromatography and column chromatography

    M Vijayalakshmi; K Periyanayagam; K Kavitha; K Akilandeshwari

    2013-01-01

    Background: The leaves of Dichrostachys cinerea are used as laxative, diuretic, painkiller. It is also used in the treatment of gonorrhoea, boils, oedema, gout, veneral diseases and nasopharyngeal affections, etc. Materials and Methods: The Phytochemical investigation of ethanolic extract of D. cinerea leaves were performed by standard chemical tests, thin layer chromatography (TLC) by using various solvent systems, and by high performance liquid chromatography (HPTLC). Two compounds were...

  3. Geothermal Permeability Enhancement - Final Report

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  4. Low vanadium ion permeabilities of sulfonated poly(phthalazinone ether ketone)s provide high efficiency and stability for vanadium redox flow batteries

    Chen, Liyun; Zhang, Shouhai; Chen, Yuning; Jian, Xigao

    2017-07-01

    A series of novel sulfonated poly(phthalazinone ether ketone)s containing pendant phenyl moieties (SPPEK-Ps) are synthesized and thoroughly characterized. The chemical structures of the polymers are confirmed by 1H NMR and FTIR analysis. The physicochemical properties and single cell performance of SPPEK-P membranes are systematically evaluated, revealing that the membranes are thermally, chemically and mechanically stable. The area resistances of SPPEK-P-90 and SPPEK-P-100 are 0.75 Ω cm2 and 0.34 Ω cm2, respectively. SPPEK-P membranes are impermeable to the bulky hydrated VO2+ ion and exhibited low V3+ ion permeability (SPPEK-P-90, 2.53 × 10-5 cm min-1) (Nafion 115 membrane: 9.0 × 10-4 cm min-1). Tests of SPPEK-P-90 in vanadium redox flow batteries (VRFBs) demonstrate a comparable columbic efficiency (CE) and energy efficiency (EE) to that of Nafion 115, where the CE is 98% and the EE is 83% at 60 mA cm-2. Moreover, the SPPEK-P-90 membrane exhibits stable performance in cell over 100 charge-discharge cycles (∼450 h).

  5. Effect of quasiparticles on interlayer transport in highly anisotropic layered superconductors

    Artemenko, S.N.; Bulaevskii, L.N.; Maley, M.P.; Vinokur, V.M.

    1999-01-01

    We have performed a microscopic calculation of the dielectric response function in highly anisotropic layered superconductors and used the developed approach to obtain the frequency-dependent London penetration length and conductivity in the case of d-wave pairing for currents perpendicular to the layers. We consider a BCS model with coherent interlayer tunneling of electrons and take into account contributions from both superconducting electrons and quasiparticles to the dielectric response. We show that quasiparticles change the low-temperature behavior of the penetration length in the intermediate frequency range where the frequency is smaller than the superconducting order parameter but larger than the inverse quasiparticle scattering time. The obtained results are used to describe the low-temperature behavior of the Josephson plasma resonance, in particular the temperature dependence of the resonance frequency and the resonance linewidth in zero external magnetic field. We compare our results with the available experimental data for Tl 2 Ba 2 CuO 6 and Bi 2 Sr 2 CaCu 2 O 8+δ (Bi-2212) and show that results of a BCS model with coherent interlayer tunneling for the dc c-axis resistivity in the superconducting state are inconsistent with experimental data for underdoped and optimally doped Bi-2212 crystals. copyright 1999 The American Physical Society

  6. High-fiber diets with reduced crude protein for commercial layers

    MFFM Praes

    2014-06-01

    Full Text Available This study aimed at evaluating diets containing different fiber sources and two crude protein levels on the performance, egg quality, and nitrogen metabolism of commercial layers. In total, 392 48-wk-old Isa Brown layers were distributed according to a completely randomized experimental design in a 3x2+1 (control factorial arrangement, resulting in seven treatments with seven replicates of eight birds each. Treatments consisted of three fiber feedstuffs (cottonseed hulls, soybean hulls, and rice hulls and two dietary crude protein levels (12% and 16%. Cottonseed hulls associated with the high crude protein level (16% resulted in the worst feed conversion ratio per dozen eggs. Diets with 16% crude protein resulted in the highest feed intake, egg production, egg weight, egg mass values, and improved feed conversion ratio (kg eggs/kg feed. The dietary inclusion of soybean hulls determined low yolk pigmentation, and of rice hulls, low egg specific gravity. The 16% crude protein diet with rice hulls promoted the best feed conversion ratio. Hens fed the reference diet presented higher egg mass and better feed conversion ratio per kg eggs and per dozen eggs. Hens fed the diets with low crude protein level (12% had reduced nitrogen excretion, but presented worse egg production.

  7. Few-layer molybdenum disulfide transistors and circuits for high-speed flexible electronics.

    Cheng, Rui; Jiang, Shan; Chen, Yu; Liu, Yuan; Weiss, Nathan; Cheng, Hung-Chieh; Wu, Hao; Huang, Yu; Duan, Xiangfeng

    2014-10-08

    Two-dimensional layered materials, such as molybdenum disulfide, are emerging as an exciting material system for future electronics due to their unique electronic properties and atomically thin geometry. Here we report a systematic investigation of MoS2 transistors with optimized contact and device geometry, to achieve self-aligned devices with performance including an intrinsic gain over 30, an intrinsic cut-off frequency fT up to 42 GHz and a maximum oscillation frequency fMAX up to 50 GHz, exceeding the reported values for MoS2 transistors to date (fT~0.9 GHz, fMAX~1 GHz). Our results show that logic inverters or radio frequency amplifiers can be formed by integrating multiple MoS2 transistors on quartz or flexible substrates with voltage gain in the gigahertz regime. This study demonstrates the potential of two-dimensional layered semiconductors for high-speed flexible electronics.

  8. On the instabilities of supersonic mixing layers - A high-Mach-number asymptotic theory

    Balsa, Thomas F.; Goldstein, M. E.

    1990-01-01

    The stability of a family of tanh mixing layers is studied at large Mach numbers using perturbation methods. It is found that the eigenfunction develops a multilayered structure, and the eigenvalue is obtained by solving a simplified version of the Rayleigh equation (with homogeneous boundary conditions) in one of these layers which lies in either of the external streams. This analysis leads to a simple hypersonic similarity law which explains how spatial and temporal phase speeds and growth rates scale with Mach number and temperature ratio. Comparisons are made with numerical results, and it is found that this similarity law provides a good qualitative guide for the behavior of the instability at high Mach numbers. In addition to this asymptotic theory, some fully numerical results are also presented (with no limitation on the Mach number) in order to explain the origin of the hypersonic modes (through mode splitting) and to discuss the role of oblique modes over a very wide range of Mach number and temperature ratio.

  9. High-latitude Pc 1 bursts arising in the dayside boundary layer region

    Hansen, H.J.; Fraser, B.J.; Menk, F.W.; Hu, Y.D.; Newell, P.T.; Meng, C.I.; Morris, R.J.

    1992-01-01

    Dayside Pc 1 geomagnetic pulsation bursts have been studied using a three-station array of induction magnetometers located at high latitudes. Associated magnetic variations in the form of solitary pulses often lead the Pc 1 bursts by 1 to 2 min. These pulses are typically associated with riometer absorption events and consequently the precipitation of fluxes of keV electrons. The Pc 1 bursts are interpreted as resulting from ion cyclotron waves which have propagated to the ionosphere from the equatorial boundary layer region. The associated boundary layer ions, identified by the low-altitude DMSP F7 satellite, range between 1 and 5 keV in energy. These particles are considered to be the most likely free energy source for the ion cyclotron waves. It is considered that such resonant ions enter the magnetosphere via the cleft and cusp because this enables a prenoon time of occurrence of most of the observations to be explained. Measured time delays of 40 to 120 s between the associated riometer absorption and Pc 2 bursts are consistent with an ion cyclotron wave generations region located in the equatorial magnetosphere

  10. New Findings by High-Order DNS for Late Flow Transition in a Boundary Layer

    Chaoqun Liu

    2011-01-01

    Full Text Available This paper serves as a summary of new discoveries by DNS for late stages of flow transition in a boundary layer. The widely spread concept “vortex breakdown” is found theoretically impossible and never happened in practice. The ring-like vortex is found the only form existing inside the flow field. The ring-like vortex formation is the result of the interaction between two pairs of counter-rotating primary and secondary streamwise vortices. Following the first Helmholtz vortex conservation law, the primary vortex tube rolls up and is stretched due to the velocity gradient. In order to maintain vorticity conservation, a bridge must be formed to link two Λ-vortex legs. The bridge finally develops as a new ring. This process keeps going on to form a multiple ring structure. The U-shaped vortices are not new but existing coherent vortex structure. Actually, the U-shaped vortex, which is a third level vortex, serves as a second neck to supply vorticity to the multiple rings. The small vortices can be found on the bottom of the boundary layer near the wall surface. It is believed that the small vortices, and thus turbulence, are generated by the interaction of positive spikes and other higher level vortices with the solid wall. The mechanism of formation of secondary vortex, second sweep, positive spike, high shear distribution, downdraft and updraft motion, and multiple ring-circle overlapping is also investigated.

  11. Electrochemical Deposition of Conformal and Functional Layers on High Aspect Ratio Silicon Micro/Nanowires.

    Ozel, Tuncay; Zhang, Benjamin A; Gao, Ruixuan; Day, Robert W; Lieber, Charles M; Nocera, Daniel G

    2017-07-12

    Development of new synthetic methods for the modification of nanostructures has accelerated materials design advances to furnish complex architectures. Structures based on one-dimensional (1D) silicon (Si) structures synthesized using top-down and bottom-up methods are especially prominent for diverse applications in chemistry, physics, and medicine. Yet further elaboration of these structures with distinct metal-based and polymeric materials, which could open up new opportunities, has been difficult. We present a general electrochemical method for the deposition of conformal layers of various materials onto high aspect ratio Si micro- and nanowire arrays. The electrochemical deposition of a library of coaxial layers comprising metals, metal oxides, and organic/inorganic semiconductors demonstrate the materials generality of the synthesis technique. Depositions may be performed on wire arrays with varying diameter (70 nm to 4 μm), pitch (5 μ to 15 μ), aspect ratio (4:1 to 75:1), shape (cylindrical, conical, hourglass), resistivity (0.001-0.01 to 1-10 ohm/cm 2 ), and substrate orientation. Anisotropic physical etching of wires with one or more coaxial shells yields 1D structures with exposed tips that can be further site-specifically modified by an electrochemical deposition approach. The electrochemical deposition methodology described herein features a wafer-scale synthesis platform for the preparation of multifunctional nanoscale devices based on a 1D Si substrate.

  12. Direct Numerical Simulations of High-Speed Turbulent Boundary Layers over Riblets

    Duan, Lian; Choudhari, Meelan, M.

    2014-01-01

    Direct numerical simulations (DNS) of spatially developing turbulent boundary layers over riblets with a broad range of riblet spacings are conducted to investigate the effects of riblets on skin friction at high speeds. Zero-pressure gradient boundary layers under two flow conditions (Mach 2:5 with T(sub w)/T(sub r) = 1 and Mach 7:2 with T(sub w)/T(sub r) = 0:5) are considered. The DNS results show that the drag-reduction curve (delta C(sub f)/C(sub f) vs l(sup +)(sub g )) at both supersonic speeds follows the trend of low-speed data and consists of a `viscous' regime for small riblet size, a `breakdown' regime with optimal drag reduction, and a `drag-increasing' regime for larger riblet sizes. At l l(sup +)(sub g) approx. 10 (corresponding to s+ approx 20 for the current triangular riblets), drag reduction of approximately 7% is achieved at both Mach numbers, and con rms the observations of the few existing experiments under supersonic conditions. The Mach- number dependence of the drag-reduction curve occurs for riblet sizes that are larger than the optimal size, with smaller slopes of (delta C(sub f)/C(sub f) for larger freestream Mach numbers. The Reynolds analogy holds with 2(C(sub h)=C(sub f) approximately equal to that of at plates for both drag-reducing and drag-increasing configurations.

  13. Polyfurfuryl alcohol derived activated carbons for high power electrical double layer capacitors

    Ruiz, V. [CSIRO Division of Energy Technology, Box 312, Clayton South, Vic. 3169 (Australia); Pandolfo, A.G., E-mail: tony.pandolfo@csiro.a [CSIRO Division of Energy Technology, Box 312, Clayton South, Vic. 3169 (Australia)

    2010-10-30

    Polyfurfuryl alcohol (PFA) derived activated carbons were prepared by the acid catalysed polymerization of furfuryl alcohol, followed by potassium hydroxide activation. Activated carbons with apparent BET surface areas ranging from 1070 to 2600 m{sup 2} g{sup -1}, and corresponding average micropore sizes between 0.6 and 1.6 nm were obtained. The porosity of these carbons can be carefully controlled during activation and their performance as electrode materials in electric double layer capacitors (EDLCs) in a non-aqueous electrolyte (1 M Et{sub 4}NBF{sub 4}/ACN) is investigated. Carbon materials with a low average pore size (<{approx}0.6 nm) exhibited electrolyte accessibility issues and an associated decrease in capacitance at high charging rates. PFA carbons with larger average pore sizes exhibited greatly improved performance, with specific electrode capacitances of 150 F g{sup -1} at an operating voltage window of 0-2.5 V; which corresponds to 32 Wh kg{sup -1} and 38 kW kg{sup -1} on an active material basis. These carbons also displayed an outstanding performance at high current densities delivering up to 100 F g{sup -1} at current densities as high as 250 A g{sup -1}. The exceptionally high capacitance and power of this electrode material is attributed to its good electronic conductivity and a highly effective combination of micro- and fine mesoporosity.

  14. Skin-friction measurements in high-enthalpy hypersonic boundary layers

    Goyne, C. P.; Stalker, R. J.; Paull, A.

    2003-06-01

    Skin-friction measurements are reported for high-enthalpy and high-Mach-number laminar, transitional and turbulent boundary layers. The measurements were performed in a free-piston shock tunnel with air-flow Mach number, stagnation enthalpy and Reynolds numbers in the ranges of 4.4 6.7, 3 13 MJ kg(-1) and 0.16× 10(6) 21× 10(6) , respectively. Wall temperatures were near 300 K and this resulted in ratios of wall enthalpy to flow-stagnation enthalpy in the range of 0.1 0.02. The experiments were performed using rectangular ducts. The measurements were accomplished using a new skin-friction gauge that was developed for impulse facility testing. The gauge was an acceleration compensated piezoelectric transducer and had a lowest natural frequency near 40 kHz. Turbulent skin-friction levels were measured to within a typical uncertainty of ± 7%. The systematic uncertainty in measured skin-friction coefficient was high for the tested laminar conditions; however, to within experimental uncertainty, the skin-friction and heat-transfer measurements were in agreement with the laminar theory of van Driest (1952). For predicting turbulent skin-friction coefficient, it was established that, for the range of Mach numbers and Reynolds numbers of the experiments, with cold walls and boundary layers approaching the turbulent equilibrium state, the Spalding & Chi (1964) method was the most suitable of the theories tested. It was also established that if the heat transfer rate to the wall is to be predicted, then the Spalding & Chi (1964) method should be used in conjunction with a Reynolds analogy factor near unity. If more accurate results are required, then an experimentally observed relationship between the Reynolds analogy factor and the skin-friction coefficient may be applied.

  15. Permeability, storage and hydraulic diffusivity controlled by earthquakes

    Brodsky, E. E.; Fulton, P. M.; Xue, L.

    2016-12-01

    Earthquakes can increase permeability in fractured rocks. In the farfield, such permeability increases are attributed to seismic waves and can last for months after the initial earthquake. Laboratory studies suggest that unclogging of fractures by the transient flow driven by seismic waves is a viable mechanism. These dynamic permeability increases may contribute to permeability enhancement in the seismic clouds accompanying hydraulic fracking. Permeability enhancement by seismic waves could potentially be engineered and the experiments suggest the process will be most effective at a preferred frequency. We have recently observed similar processes inside active fault zones after major earthquakes. A borehole observatory in the fault that generated the M9.0 2011 Tohoku earthquake reveals a sequence of temperature pulses during the secondary aftershock sequence of an M7.3 aftershock. The pulses are attributed to fluid advection by a flow through a zone of transiently increased permeability. Directly after the M7.3 earthquake, the newly damaged fault zone is highly susceptible to further permeability enhancement, but ultimately heals within a month and becomes no longer as sensitive. The observation suggests that the newly damaged fault zone is more prone to fluid pulsing than would be expected based on the long-term permeability structure. Even longer term healing is seen inside the fault zone of the 2008 M7.9 Wenchuan earthquake. The competition between damage and healing (or clogging and unclogging) results in dynamically controlled permeability, storage and hydraulic diffusivity. Recent measurements of in situ fault zone architecture at the 1-10 meter scale suggest that active fault zones often have hydraulic diffusivities near 10-2 m2/s. This uniformity is true even within the damage zone of the San Andreas fault where permeability and storage increases balance each other to achieve this value of diffusivity over a 400 m wide region. We speculate that fault zones

  16. Permeability of cork to gases.

    Faria, David P; Fonseca, Ana L; Pereira, Helen; Teodoro, Orlando M N D

    2011-04-27

    The permeability of gases through uncompressed cork was investigated. More than 100 samples were assessed from different plank qualities to provide a picture of the permeability distribution. A novel technique based on a mass spectrometer leak detector was used to directly measure the helium flow through the central area of small disks 10 mm in diameter and 2 mm thick. The permeability for nitrogen, oxygen, and other gases was measured by the pressure rise technique. Boiled and nonboiled cork samples from different sections were evaluated. An asymmetric frequency distribution ranging 3 orders of magnitude (roughly from 1 to 1000 μmol/(cm·atm·day)) for selected samples without macroscopic defects was found, having a peak below 100 μmol/(cm·atm·day). Correlation was found between density and permeability: higher density samples tend to show lower permeability. However, boiled cork showed a mean lower permeability despite having a lower density. The transport mechanism of gases through cork was also examined. Calculations suggest that gases permeate uncompressed cork mainly through small channels between cells under a molecular flow regime. The diameter of such channels was estimated to be in the range of 100 nm, in agreement with the plasmodesmata size in the cork cell walls.

  17. Microstructure and chemical analysis of Hf-based high-k dielectric layers in metal-insulator-metal capacitors

    Thangadurai, P. [Department of Materials Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel); Mikhelashvili, V.; Eisenstein, G. [Department of Electrical Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel); Kaplan, W.D., E-mail: kaplan@tx.technion.ac.i [Department of Materials Engineering, Technion - Israel Institute of Technology, Haifa 32000 (Israel)

    2010-05-31

    The microstructure and chemistry of the high-k gate dielectric significantly influences the performance of metal-insulator-metal (MIM) and metal-oxide-semiconductor devices. In particular, the local structure, chemistry, and inter-layer mixing are important phenomena to be understood. In the present study, high resolution and analytical transmission electron microscopy are combined to study the local structure, morphology, and chemistry in MIM capacitors containing a Hf-based high-k dielectric. The gate dielectric, bottom and gate electrodes were deposited on p-type Si(100) wafers by electron beam evaporation. Four chemically distinguishable sub-layers were identified within the dielectric stack. One is an unintentionally formed 4.0 nm thick interfacial layer of Ta{sub 2}O{sub 5} at the interface between the Ta electrode and the dielectric. The other three layers are based on HfN{sub x}O{sub y} and HfTiO{sub y}, and intermixing between the nearby sub-layers including deposited SiO{sub 2}. Hf-rich clusters were found in the HfN{sub x}O{sub y} layer adjacent to the Ta{sub 2}O{sub 5} layer.

  18. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  19. Complementary study of the internal porous silicon layers formed under high-dose implantation of helium ions

    Lomov, A. A., E-mail: lomov@ftian.ru; Myakon’kikh, A. V. [Russian Academy of Sciences, Institute of Physics and Technology (Russian Federation); Chesnokov, Yu. M. [National Research Centre “Kurchatov Institute” (Russian Federation); Shemukhin, A. A.; Oreshko, A. P. [Moscow State University (Russian Federation)

    2017-03-15

    The surface layers of Si(001) substrates subjected to plasma-immersion implantation of helium ions with an energy of 2–5 keV and a dose of 5 × 10{sup 17} cm{sup –2} have been investigated using high-resolution X-ray reflectivity, Rutherford backscattering, and transmission electron microscopy. The electron density depth profile in the surface layer formed by helium ions is obtained, and its elemental and phase compositions are determined. This layer is found to have a complex structure and consist of an upper amorphous sublayer and a layer with a porosity of 30–35% beneath. It is shown that the porous layer has the sharpest boundaries at a lower energy of implantable ions.

  20. The Permeability Enhancing Mechanism of DMSO in Ceramide Bilayers Simulated by Molecular Dynamics

    Notman, Rebecca; den Otter, Wouter K.; Noro, Massimo G.; Briels, W. J.; Anwar, Jamshed

    2007-01-01

    The lipids of the topmost layer of the skin, the stratum corneum, represent the primary barrier to molecules penetrating the skin. One approach to overcoming this barrier for the purpose of delivery of active molecules into or via the skin is to employ chemical permeability enhancers, such as dimethylsulfoxide (DMSO). How these molecules exert their effect at the molecular level is not understood. We have investigated the interaction of DMSO with gel-phase bilayers of ceramide 2, the predominant lipid in the stratum corneum, by means of molecular dynamics simulations. The simulations satisfactorily reproduce the phase behavior and the known structural parameters of ceramide 2 bilayers in water. The effect of DMSO on the gel-phase bilayers was investigated at various concentrations over the range 0.0−0.6 mol fraction DMSO. The DMSO molecules accumulate in the headgroup region and weaken the lateral forces between the ceramides. At high concentrations of DMSO (≥0.4 mol fraction), the ceramide bilayers undergo a phase transition from the gel phase to the liquid crystalline phase. The liquid-crystalline phase of ceramides is expected to be markedly more permeable to solutes than the gel phase. The results are consistent with the experimental evidence that high concentrations of DMSO fluidize the stratum corneum lipids and enhance permeability. PMID:17513383